caixa_core/

manifest.rs

use std::path::{Path, PathBuf};

use serde::{Deserialize, Serialize};
use tatara_lisp::DeriveTataraDomain;

use thiserror::Error;

use crate::{
    CaixaKind, Dep,
    behavior::BehaviorSpec,
    dep::DepError,
    limits::LimitsSpec,
    render::{
        PathShapeViolation, is_computeunit_yaml_extension, is_git_repo_url, is_lisp_extension,
        is_sandboxed_relative_path,
    },
    supervisor::SupervisorSpec,
    upgrade::UpgradeFromEntry,
};

/// Top-level manifest for a caixa (a tatara-lisp package).
///
/// Authored as `caixa.lisp`:
///
/// ```lisp
/// (defcaixa
///   :nome        "pangea-tatara-aws"
///   :versao      "0.1.0"
///   :kind        Biblioteca
///   :edicao      "2026"
///   :descricao   "AWS provider caixa for tatara-lisp"
///   :repositorio "github:pleme-io/pangea-tatara-aws"
///   :licenca     "MIT"
///   :autores     ("pleme-io")
///   :etiquetas   ("iac" "aws" "pangea")
///   :deps        ((:nome "caixa-teia"    :versao "^0.1")
///                 (:nome "iac-forge-ir"  :versao "^0.5"))
///   :deps-dev    ((:nome "tatara-check"  :versao "*"))
///   :bibliotecas ("lib/pangea-tatara-aws.lisp"))
/// ```
///
/// Because `Caixa` derives [`tatara_lisp::domain::TataraDomain`], the manifest
/// is parsed directly by the tatara-lisp compiler — an ill-formed manifest is
/// a compile error, not a runtime error.
#[derive(DeriveTataraDomain, Serialize, Deserialize, Debug, Clone, PartialEq)]
#[serde(rename_all = "camelCase")]
#[tatara(keyword = "defcaixa")]
pub struct Caixa {
    /// Package name — the canonical string used in `:deps`, the registry, and
    /// the default lib/exe entry names.
    pub nome: String,

    /// Package version — a semver literal like `"0.1.0"`. Parsed lazily via
    /// [`crate::CaixaVersion::parse`].
    pub versao: String,

    /// What this caixa produces. See [`CaixaKind`].
    pub kind: CaixaKind,

    /// Language edition — determines macro surface + compatibility flags.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub edicao: Option<String>,

    /// Free-form description shown in the registry listing.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub descricao: Option<String>,

    /// Homepage or repo URL.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub repositorio: Option<String>,

    /// SPDX license expression — `"MIT"`, `"Apache-2.0 OR MIT"`, etc.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub licenca: Option<String>,

    /// Authors — free-form strings.
    #[serde(default)]
    pub autores: Vec<String>,

    /// Topical tags used for registry search.
    #[serde(default)]
    pub etiquetas: Vec<String>,

    /// Runtime dependencies.
    #[serde(default)]
    pub deps: Vec<Dep>,

    /// Development-only dependencies (tests, lint, bench).
    #[serde(default)]
    pub deps_dev: Vec<Dep>,

    /// Paths to executable entry points (relative to the package root).
    /// Required when `:kind Binario`.
    #[serde(default)]
    pub exe: Vec<String>,

    /// Paths to library entry points (relative to the package root).
    /// First entry is the canonical `lib/<nome>.lisp`; when omitted under
    /// `:kind Biblioteca`, the layout check expects `lib/<nome>.lisp`.
    #[serde(default)]
    pub bibliotecas: Vec<String>,

    /// Paths to service manifests (relative to the package root).
    /// Required when `:kind Servico`.
    #[serde(default)]
    pub servicos: Vec<String>,

    // ── M2 typed-substrate extensions per theory/ABSORPTION-ROADMAP.md ──
    //
    // All four are optional + default to "absent"; existing caixas
    // round-trip unchanged. Each maps onto a prior-art primitive named
    // in theory/INSPIRATIONS.md:
    //
    //   :limits        — Lunatic per-process limits (§III.1)
    //   :behavior      — OTP gen_server callbacks  (§II.3)
    //   :upgrade-from  — OTP appup migration       (§II.4)
    //   :estrategia    — OTP supervisor strategy   (§II.2 + §III.2)
    //   :children      — OTP supervisor children    (§II.2 + §III.2)
    //
    // The supervisor slots are flat on Caixa (vs nested under a
    // SupervisorSpec sub-form) to keep tatara-lisp authoring at one
    // level of nesting; SupervisorSpec exists for validation +
    // composition convenience (`Caixa::supervisor_view()`).
    /// Lunatic-style per-process resource limits. None = unbounded.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub limits: Option<LimitsSpec>,

    /// OTP-shaped behavior callbacks for Servico-kind caixas.
    /// Authored as `(:on-init "..." :on-call "..." …)`.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub behavior: Option<BehaviorSpec>,

    /// OTP appup — declarative upgrade instructions per prior version.
    /// Empty list = no hot-upgrade path declared (caller falls back to
    /// `:Restart` strategy).
    #[serde(default)]
    pub upgrade_from: Vec<UpgradeFromEntry>,

    /// OTP supervisor strategy. Required when `:kind Supervisor`;
    /// ignored otherwise.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub estrategia: Option<crate::supervisor::RestartStrategy>,

    /// Max restarts before the supervisor itself fails. Defaults via
    /// SupervisorSpec at validation time.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub max_restarts: Option<u32>,

    /// Sliding window for `max_restarts`. Authored as a duration
    /// string (`"60s"`, `"5m"`).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub restart_window: Option<String>,

    /// Static children of a supervisor. Required for OneForOne /
    /// OneForAll / RestForOne; must be empty for SimpleOneForOne.
    #[serde(default)]
    pub children: Vec<crate::supervisor::ChildSpec>,

    // ── M3 Aplicacao slots (theory/MESH-COMPOSITION.md) ─────────────────
    //
    // Required when :kind Aplicacao; ignored otherwise.
    // Composed into a typed AplicacaoSpec via Caixa::aplicacao_view().
    /// Member Servicos that make up this Aplicacao. Each is a
    /// caixa-name + version-constraint pair. Required for Aplicacao.
    #[serde(default)]
    pub membros: Vec<crate::aplicacao::Membro>,

    /// WIT-typed inter-Servico contracts. Each `:de` and `:para`
    /// must reference a name in `:membros`.
    #[serde(default)]
    pub contratos: Vec<crate::aplicacao::WitContract>,

    /// Mesh-level policies (timeout, retries, circuit-breaker, mTLS,
    /// rate-limit). Apply to every contrato unless overridden per-edge
    /// in M4.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub politicas: Option<crate::aplicacao::MeshPolicy>,

    /// Placement strategy across the cluster fleet
    /// (single-node | replicated | sharded).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub placement: Option<crate::aplicacao::Placement>,

    /// External entry point — gateway / ingress shape. Optional;
    /// only for public Aplicacaos.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub entrada: Option<crate::aplicacao::Entrada>,

    // ── Acao slot (CANTEIRO §7.1-C) ──────────────────────────────────────
    //
    // Required when :kind Acao; ignored otherwise (mirrors the M2/
    // supervisor-tree/M3 slot triads above — a declared-but-foreign `:ci`
    // is a `LayoutError::CiOnNonAcao` build error, not a silent drop).
    /// Typed CI run — a repo's CI run as a set of typed nodes + their
    /// dependency edges. Required for `:kind Acao`; validated (not
    /// rendered) by the `caixa-actions` renderer via
    /// `canteiro_types::decompose`. See `caixa-actions`' crate docs for
    /// the M0 validate-only contract.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub ci: Option<canteiro_types::CiRun>,
}

/// Why reading a manifest into a [`Caixa`] failed.
///
/// Split from [`ManifestError`] (which reports a *parsed* manifest that is
/// semantically wrong) because the two answer different questions, and the
/// distinction is the whole point of this type: `ManifestError` means "your
/// caixa is wrong", `LeituraError::DialetoEstrangeiro` means "this file is not
/// a caixa".
#[derive(Debug, thiserror::Error)]
pub enum LeituraError {
    /// The source is not readable as a `(defcaixa …)` package manifest — bad
    /// syntax, a wrong head symbol, an unknown or mistyped slot.
    ///
    /// `#[source]`, not `#[error(transparent)]`. Transparent delegates
    /// `source()` past the inner error to ITS source, which drops the
    /// `LispError` off the cause chain — and `feira`'s
    /// `load_caixa_parse_error_preserves_underlying_lisp_error_on_chain`
    /// pins that a caller can `downcast_ref::<tatara_lisp::LispError>()`
    /// through an anyhow context to read the typed payload. That pin caught
    /// this exact regression when the variant first landed transparent.
    #[error("{0}")]
    Leitura(
        #[source]
        #[from]
        tatara_lisp::LispError,
    ),

    /// The source IS a well-formed `(defcaixa …)` form, but of a different
    /// declaration than this crate's.
    ///
    /// The variant that did not exist before, and whose absence is the defect.
    /// A `(defcaixa :name "x" :ecosystem :go …)` used to reach the derive's
    /// `parse_kwargs_strict` and come back as an unknown-keyword rejection —
    /// byte-identical in shape to a typo in a real manifest. Measured over the
    /// org checkout on 2026-07-31, that shape is the MAJORITY of the corpus, so
    /// the confusing error was also the common one.
    ///
    /// Carrying the dialect means a consumer can branch on "not mine" without
    /// re-parsing, and a census can count it. Every user-facing byte-string
    /// (canonical keyword, one-line description, consuming crate) is a
    /// projection of [`crate::dialeto::CaixaDialeto`] — the variant stores the
    /// typed dialect and the `#[error]` template calls
    /// [`CaixaDialeto::palavra_canonica`] /
    /// [`CaixaDialeto::descricao`] / [`CaixaDialeto::consumidor`] on it, so
    /// the three axes cannot silently diverge from the classification. Prior
    /// to this closure the variant carried each accessor's return value as a
    /// stored `&'static str` snapshot alongside `dialeto`, and the sole
    /// constructor at [`Caixa::from_lisp`] filled all four fields — a caller
    /// could construct `DialetoEstrangeiro { dialeto: Molde,
    /// palavra_canonica: "defcaixa", … }` and every downstream consumer
    /// (Display, ad-hoc audit, future JSON serialization) would silently
    /// disagree with `dialeto.palavra_canonica() == "defmolde"`. The typed
    /// enum owns the projections; the variant only carries the axis.
    #[error(
        "this is a `{palavra}` declaration ({desc}), read by \
         {cons} — not a caixa-core package manifest. `defcaixa` is the \
         tatara-lisp package manifest (`:nome :versao :kind :deps …`); the two \
         are different declarations that shared one keyword until 2026-07-31",
        palavra = dialeto.palavra_canonica(),
        desc = dialeto.descricao(),
        cons = dialeto.consumidor()
    )]
    DialetoEstrangeiro {
        /// Which declaration this actually is. Sole authoritative axis;
        /// every user-facing projection routes through
        /// [`crate::dialeto::CaixaDialeto`]'s typed accessors so the four
        /// axes cannot silently disagree.
        dialeto: crate::dialeto::CaixaDialeto,
    },

    /// Not a manifest declaration at all.
    #[error(transparent)]
    Dialeto(#[from] crate::dialeto::DialetoError),
}

/// Substrate-canonical universal-axis per-[`Caixa`] `:licenca` SPDX-shaped
/// license-expression fallback for the `Option<String>` `:licenca` slot —
/// the `"MIT"` SPDX identifier every [`caixa-helm`]-rendered
/// `lareira-<nome>` Helm chart's `README.md` `## License` section folds an
/// author-omitted (`None`) `:licenca` slot through, extracted as a typed
/// `pub const` so every substrate-side consumer that resolves "what license
/// scalar does an author-omitted `:licenca` degrade onto?" reaches for
/// exactly one substrate-primitive `&'static str`.
///
/// The `:licenca` fallback axis has one production consumer today — the
/// [`caixa-helm`] `build_readme` fold at `caixa-helm/src/lib.rs`'s
/// `caixa.licenca().unwrap_or(CAIXA_LICENCA_DEFAULT)` `README.md`
/// `## License` section body — with three sibling caixa-core sites that
/// cite the `"MIT"` fallback in prose (this crate's [`Caixa::licenca`]
/// accessor's docstring, [`Self::validate_licenca`]'s docstring, and the
/// [`ManifestError::LicencaEmpty`] `#[error]` template's user-facing text)
/// all quoting the exact byte-string a future substrate-side rebrand of the
/// fallback (a tightening to `"Apache-2.0"` as the substrate absorbs the
/// wasm-component-model conventions the `wasi:*` WIT worlds already carry,
/// a per-cluster license-default overlay the M4 CR materializer resolves
/// per-CR, a promotion to the plain `Option<String>` byte-string into a
/// richer `SpdxExpression` enum once the SPDX-expression parser lands per
/// [`Self::validate_licenca`]'s docstring roadmap) would silently split
/// against — the caixa-helm renderer would emit the new byte, the
/// docstrings would still cite the prior byte, and every author who reads
/// the accessor docstring before authoring would file a fresh
/// `:licenca "MIT"` verbatim rather than defer to the substrate default,
/// with the drift surfacing at chart-README-audit time far from the
/// substrate rebrand commit.
///
/// Prior to this lift the sole production emitter (`build_readme`) carried
/// an inline `"MIT"` byte literal at
/// `caixa-helm/src/lib.rs:1018`'s `.unwrap_or("MIT")` fallback arm — one
/// occurrence of the same load-bearing per-`Caixa` universal-axis
/// SPDX-shaped license-expression convention as the four sibling caixa-core
/// docstring citations, drift-prone by construction ahead of the second
/// occurrence the future M4 `mesh.pleme.io/v1alpha1/Aplicacao` CR
/// materializer's per-Aplicacao registry-annotation synthesis (the
/// [`Self::validate_licenca`] roadmap already names the `Chart.yaml
/// annotations["artifacthub.io/license"]` axis every registry-facing chart
/// carries as the second consumer) will surface.
///
/// The `"MIT"` value pins the canonical CAIXA-SDLC §I license scaffold
/// every `feira init`-emitted [`Self::template`] carries verbatim
/// (`:licenca "MIT"`) and every substrate-side renderer fixture
/// ([`caixa-helm`]'s `sample_caixa`, [`caixa-flux`]'s renderer fixtures,
/// [`caixa-mesh`]'s renderer fixtures) seeds by construction, matching the
/// pleme-io repo `LICENSE` header this workspace itself ships under. The
/// alternatives an author declares explicitly (compound SPDX expressions
/// like `"Apache-2.0 OR MIT"`, permissive-family peers like
/// `"Apache-2.0"` / `"BSD-3-Clause"`, license-with-exception forms like
/// `"Apache-2.0 WITH LLVM-exception"`) express deliberate license postures
/// an author declares explicitly, never a posture an author-omitted slot
/// should silently assume by default.
///
/// Lifted as a typed `pub const` so the substrate's chosen license
/// fallback has exactly one source of truth on the `:licenca` fallback
/// axis, on the same substrate-primitive lift discipline the peer
/// per-`Caixa` load-bearing-scalar constants
/// ([`crate::version::DEFAULT_PUBLISH_TAG_PREFIX`],
/// [`crate::version::DEFAULT_GIT_REMOTE`],
/// [`crate::version::DEFAULT_PLEME_GIT_ORG`]) already carry on the sibling
/// per-`Caixa` universal-axis publish-side convention surface, and the
/// same discipline the sibling M2 per-supervisor default set carries
/// end-to-end ([`crate::supervisor::SUPERVISOR_ESTRATEGIA_DEFAULT`],
/// [`crate::supervisor::SUPERVISOR_MAX_RESTARTS_DEFAULT`],
/// [`crate::supervisor::SUPERVISOR_RESTART_WINDOW_DEFAULT`],
/// [`crate::supervisor::SUPERVISOR_CHILD_RESTART_DEFAULT`]) and the M3
/// per-`:placement` default set already carries
/// ([`crate::aplicacao::PLACEMENT_ESTRATEGIA_DEFAULT`]) on the paired
/// M2 / M3 typed-slot-default axes. First typed default on the outer
/// top-level [`Caixa`] universal-axis surface to converge onto the
/// substrate-primitive-lift discipline the M2 / M3 typed-slot families
/// already carry.
pub const CAIXA_LICENCA_DEFAULT: &str = "MIT";

impl Caixa {
    /// Parse a `caixa.lisp` source string to a typed `Caixa`.
    ///
    /// Classifies the dialect **before** parsing. A `(defcaixa …)` of another
    /// declaration is [`LeituraError::DialetoEstrangeiro`], naming what it is
    /// and who reads it, instead of an unknown-keyword rejection that reads as
    /// "your manifest is broken".
    ///
    /// The ordering is load-bearing. Handing a foreign dialect to the derive
    /// first and interpreting the failure afterwards would mean guessing from
    /// an error message, and the guess would be wrong for every file whose
    /// first unknown slot happens to be one both schemas could plausibly carry.
    pub fn from_lisp(src: &str) -> Result<Self, LeituraError> {
        use tatara_lisp::domain::TataraDomain;
        let forms = tatara_lisp::read(src).map_err(LeituraError::Leitura)?;
        let first = forms.first().ok_or(crate::dialeto::DialetoError::Vazio)?;

        // Route the foreign-dialect rejection gate through the lifted
        // [`crate::dialeto::CaixaDialeto::is_molde_family`] (e9d2315)
        // typed predicate rather than the pre-lift hand-rolled three-arm
        // `match { Pacote => {}, Desconhecido => {}, foreign => Err(…) }`
        // literal — the `defmolde` declaration-family partition (the two-
        // arity closure of [`crate::dialeto::CaixaDialeto::Molde`] and
        // [`crate::dialeto::CaixaDialeto::MoldePosicional`], the two arms
        // whose sibling [`crate::dialeto::CaixaDialeto::palavra_canonica`]
        // projection already collapses onto `"defmolde"` and whose sibling
        // [`crate::dialeto::CaixaDialeto::consumidor`] projection already
        // collapses onto `"pleme-doc-gen"`) resolves through one dispatch
        // on the substrate primitive. `Pacote` (the tatara-lisp package
        // manifest this derive can parse) and `Desconhecido` (deliberately
        // falls through to the derive rather than short-circuiting: a
        // `(defcaixa …)` matching neither schema is most likely a genuine
        // package manifest with a typo in `:nome`, and the derive's
        // diagnostic — which names the offending keyword and suggests the
        // nearest slot — is far better than anything this classifier
        // could say) both return `false` from `is_molde_family()` and fall
        // through to the derive. Only the typed dialect flows into the
        // error — the three user-facing projections (canonical keyword,
        // description, consumer) are read at Display time through
        // [`crate::dialeto::CaixaDialeto`]'s own accessors, so the
        // variant cannot carry a snapshot that drifts from
        // [`crate::dialeto::CaixaDialeto::palavra_canonica`] /
        // `descricao` / `consumidor`. A future fifth dialect the
        // [`crate::dialeto`] module doc's "third dialect" hazard
        // actualises that belongs to the `defmolde` family lands one
        // match arm at [`crate::dialeto::CaixaDialeto::is_molde_family`]
        // and this gate picks up the new arm by construction — the pre-
        // lift wildcard `foreign =>` was compile-time-anonymous and would
        // silently absorb any hypothetical fifth `defcaixa`-family arm as
        // foreign; routing the partition through the typed predicate
        // closes both drift surfaces.
        let dialeto = crate::dialeto::classify_form(first)?;
        if dialeto.is_molde_family() {
            return Err(LeituraError::DialetoEstrangeiro { dialeto });
        }

        Self::compile_from_sexp(first).map_err(LeituraError::Leitura)
    }

    /// Register `Caixa` with the global tatara-lisp domain registry so
    /// `defcaixa` is dispatchable from any tatara-lisp binary that seeds
    /// the registry (e.g. `tatara-check`).
    ///
    /// Returns the typed [`tatara_lisp::KeywordCollision`] on the second
    /// (and every subsequent) call in the same process — one keyword,
    /// one type, per process is a hard invariant of the upstream
    /// registry, and a caller that hits it must fix its crate graph
    /// rather than swallowing the error. Peer of the sibling per-crate
    /// `register()` entry points at `caixa-flake/src/flake.rs`,
    /// `caixa-fmt/src/lisp_config.rs`, `caixa-lacre/src/lock.rs`,
    /// `caixa-lint/src/lisp_config.rs`, `caixa-resolver/src/lisp_config.rs`
    /// — every substrate crate that owns a tatara-lisp keyword now
    /// propagates the same typed error verbatim, so a downstream binary
    /// that seeds the registry (`tatara-check`, the future LSP) reaches
    /// for one shape at every call site.
    ///
    /// # Errors
    ///
    /// [`tatara_lisp::KeywordCollision`] when a peer type has already
    /// claimed the `defcaixa` keyword in this process.
    pub fn register() -> Result<(), tatara_lisp::KeywordCollision> {
        tatara_lisp::domain::register::<Self>()
    }

    /// Substrate-canonical per-`Caixa` `:licenca` SPDX-expression scalar
    /// accessor every consumer of the top-level manifest's license axis
    /// keys off — returns the author-declared `:licenca` byte-string
    /// verbatim as an `Option<&str>`, borrowed from the typed slot's own
    /// `Option<String>` storage. `None` when the slot is absent (the
    /// canonical "omit to defer to the caixa-helm renderer's `MIT`
    /// fallback" shape [`Self::validate_licenca`] documents at
    /// caixa-core/src/manifest.rs:1560; the peer [`caixa-helm`]
    /// `build_readme` fold at caixa-helm/src/lib.rs:962 reads this
    /// predicate too, so an authored-but-unset `:licenca` round-trips to
    /// a rendered `lareira-<nome>` chart's `README.md` `## License`
    /// section structurally identical to one that omits the slot).
    ///
    /// The `:licenca` slot carries the universal-axis SPDX-expression
    /// license identifier every kind of caixa emits under (CAIXA-SDLC
    /// §I — the author-facing surface every `defcaixa` form supplies) —
    /// the typed slot's `Option<String>` accept-set (empty-string
    /// rejected through [`ManifestError::LicencaEmpty`], SPDX-alphabet-
    /// invalid rejected through [`ManifestError::LicencaInvalid`]) maps
    /// onto the `lareira-<nome>` Helm chart's `README.md` `## License`
    /// section (caixa-helm/src/lib.rs:962) and (through future
    /// tightening documented at [`Self::validate_licenca`]) the
    /// Chart.yaml `annotations["artifacthub.io/license"]` axis every
    /// registry-facing chart carries. Every downstream consumer that
    /// reads the license byte-string keys off this scalar (the
    /// [`Self::validate_licenca`] empty-arm + SPDX-shape gate that
    /// routes through `self.licenca.as_deref()`, the caixa-helm
    /// `build_readme` `unwrap_or_else(|| "MIT".into())` fold that keys
    /// the fallback off the `Option::is_none()` arm, every future
    /// per-`Caixa` registry-facing renderer the CAIXA-SDLC §I roadmap
    /// acknowledges).
    ///
    /// Prior to this lift the `.licenca` field was accessed inline at
    /// two production sites — [`Self::validate_licenca`]'s
    /// `self.licenca.as_deref()` empty-and-shape gate binding and the
    /// caixa-helm `build_readme` `caixa.licenca.clone().unwrap_or_else(||
    /// "MIT".into())` `README.md` `## License` fold — two open-coded
    /// field-accesses that expressed no compile-time link back to the
    /// typed slot. A future extension of the `:licenca` axis to a
    /// richer author surface — a per-`:licenca` structured SPDX
    /// expression parser + license-id allowlist (the future tightening
    /// [`Self::validate_licenca`]'s docstring acknowledges), a
    /// per-cluster license-default overlay the M4 CR materializer
    /// resolves per-CR (the "cluster policy pins `Apache-2.0` for every
    /// unlisted caixa" arm), a promotion of the plain
    /// `Option<String>` byte-string to a richer `SpdxExpression` enum
    /// once the SPDX-expression parser lands — would have had to be
    /// threaded through both open-coded copies in lockstep or the
    /// validate gate and the caixa-helm emit path would silently
    /// disagree on which license a given [`Caixa`] resolves to (an
    /// author's `:licenca "MIT OR Apache-2.0"` would satisfy validate
    /// while the emit path silently rendered a stale `MIT` fallback,
    /// or vice versa). Lifting the resolution to a typed method on the
    /// substrate primitive means every downstream consumer of the
    /// caixa's per-`Caixa` license surface reaches for exactly one
    /// typed dispatch — the resolver's accept-set migrates as a unit
    /// on any future axis addition.
    ///
    /// First `Option<&str>`-return top-level [`Caixa`] scalar accessor —
    /// opens the "outer [`Caixa`] `Option<&str>` scalar" projection
    /// pattern the sibling per-`Caixa` `:descricao` / `:repositorio` /
    /// `:edicao` future lifts fold on. Same "one typed dispatch on the
    /// substrate primitive, thin projections at each consumer"
    /// discipline the peer per-`:placement` [`crate::aplicacao::Placement::shard_key`]
    /// (7cd2a28) / [`crate::aplicacao::Placement::affinity`] (74ec2d3)
    /// / per-`:contratos` [`crate::aplicacao::WitContract::endpoint`]
    /// (7020470) / [`crate::aplicacao::WitContract::subject`] (90de675)
    /// / [`crate::aplicacao::WitContract::slot`] (ed22b66)
    /// `Option<&str>`-return accessors carry on the sibling M2 / M3
    /// typed-slot atom axes, extended here to the outer top-level
    /// `Caixa` universal-axis surface. Named `licenca()` to match the
    /// storage field's name; the accessor's identity maps onto the
    /// canonical CAIXA-SDLC §I vocabulary the slot's docstring already
    /// carries.
    #[must_use]
    pub const fn licenca(&self) -> Option<&str> {
        match &self.licenca {
            Some(s) => Some(s.as_str()),
            None => None,
        }
    }

    /// Substrate-canonical per-`Caixa` `:repositorio` git-repo-URL scalar
    /// accessor every consumer of the top-level manifest's homepage /
    /// source-of-truth axis keys off — returns the author-declared
    /// `:repositorio` byte-string verbatim as an `Option<&str>`, borrowed
    /// from the typed slot's own `Option<String>` storage. `None` when
    /// the slot is absent (the canonical "omit to defer to the renderer's
    /// per-target placeholder" shape — [`caixa-helm`]'s `ChartYaml.home`
    /// carries the `Option<String>` through verbatim so an author-omitted
    /// `:repositorio` renders a `Chart.yaml` without a `home:` field
    /// (`skip_serializing_if = "Option::is_none"`), while [`caixa-flux`]'s
    /// `ClusterBundleOpts::for_caixa` folds the omitted slot through a
    /// `format!("https://github.com/{DEFAULT_PLEME_GIT_ORG}/{nome}")`
    /// fallback derived from `caixa.nome`).
    ///
    /// The `:repositorio` slot carries the universal-axis git-repo-URL
    /// homepage identifier every kind of caixa emits under (CAIXA-SDLC
    /// §I — the author-facing surface every `defcaixa` form supplies) —
    /// the typed slot's `Option<String>` accept-set (empty-string
    /// rejected through [`ManifestError::RepositorioEmpty`], git-repo-URL-
    /// shape-invalid rejected through [`ManifestError::RepositorioInvalid`]
    /// past the shared [`crate::render::is_git_repo_url`] predicate the
    /// peer per-`:deps :fonte :repo` axis also routes through) maps onto
    /// four load-bearing downstream consumers:
    ///
    ///   - [`Self::validate_repositorio`]'s empty-arm + shape-predicate
    ///     gate binding at caixa-core/src/manifest.rs:1456 — the
    ///     universal-axis identity gate wired at caixa-build time.
    ///   - [`caixa-helm`]'s `build_chart_yaml` `ChartYaml.home` fold at
    ///     caixa-helm/src/lib.rs:840 — the rendered `lareira-<nome>`
    ///     Helm chart's `Chart.yaml` `home:` field, which every registry
    ///     that ingests the chart (ArtifactHub, chartmuseum,
    ///     `helm search repo`) surfaces as the chart's canonical source-
    ///     of-truth link.
    ///   - [`caixa-helm`]'s `build_readme` `## Source` fold at
    ///     caixa-helm/src/lib.rs:957 — the rendered `lareira-<nome>`
    ///     chart's `README.md` header link back to the source repo,
    ///     which every author who inspects the rendered chart bundle
    ///     lands at.
    ///   - [`caixa-flux`]'s `ClusterBundleOpts::for_caixa`
    ///     `GitRepository.spec.url` fold at caixa-flux/src/lib.rs:2006 —
    ///     the rendered `GitRepository` CR's `spec.url` field, which
    ///     FluxCD's `source-controller` polls to reconcile the caixa's
    ///     manifest bundle from git.
    ///
    /// Prior to this lift the `.repositorio` field was accessed inline
    /// at four production sites — [`Self::validate_repositorio`]'s
    /// `self.repositorio.as_deref()` empty-and-shape gate binding, the
    /// caixa-helm `build_chart_yaml` `caixa.repositorio.clone()`
    /// `Chart.yaml` `home:` field fold, the caixa-helm `build_readme`
    /// `caixa.repositorio.clone().unwrap_or_else(|| caixa.nome.clone())`
    /// `README.md` `## Source` fold, and the caixa-flux
    /// `ClusterBundleOpts::for_caixa`
    /// `caixa.repositorio.clone().unwrap_or_else(|| format!(...))`
    /// `GitRepository.spec.url` fold — four open-coded field-accesses
    /// that expressed no compile-time link back to the typed slot. A
    /// future extension of the `:repositorio` axis to a richer author
    /// surface — a per-`:repositorio` structured
    /// [`crate::render::GitRepoUrl`]-shaped scheme+host+path parse
    /// (the future tightening [`Self::validate_repositorio`]'s
    /// docstring anticipates alongside the peer per-`:deps :fonte
    /// :repo` axis), a per-cluster repo-mirror overlay the M4 CR
    /// materializer resolves per-CR (the "cluster policy rewrites
    /// `github:pleme-io/...` to `git.internal/mirror/pleme-io/...`"
    /// arm the private-registry story acknowledges), a promotion of
    /// the plain `Option<String>` byte-string to a richer
    /// `RepoUrl` enum discriminated on scheme — would have had to be
    /// threaded through all four open-coded copies in lockstep or the
    /// validate gate and the three emit paths would silently disagree
    /// on which URL a given [`Caixa`] resolves to (an author's
    /// `:repositorio "github:pleme-io/checkout"` would satisfy validate
    /// while one of the emit paths silently rendered a stale URL, or
    /// vice versa). Lifting the resolution to a typed method on the
    /// substrate primitive means every downstream consumer of the
    /// caixa's per-`Caixa` repo-URL surface reaches for exactly one
    /// typed dispatch — the resolver's accept-set migrates as a unit on
    /// any future axis addition.
    ///
    /// Second outer top-level [`Caixa`] `Option<&str>`-return scalar
    /// accessor — sibling of [`Self::licenca`] (6d5bc28), the accessor
    /// that opened the "outer [`Caixa`] `Option<&str>` scalar"
    /// projection pattern this lift folds on. Same "one typed dispatch
    /// on the substrate primitive, thin projections at each consumer"
    /// discipline the peer per-`:placement`
    /// [`crate::aplicacao::Placement::shard_key`] (7cd2a28) /
    /// [`crate::aplicacao::Placement::affinity`] (74ec2d3) /
    /// per-`:contratos` [`crate::aplicacao::WitContract::endpoint`]
    /// (7020470) / [`crate::aplicacao::WitContract::subject`] (90de675)
    /// / [`crate::aplicacao::WitContract::slot`] (ed22b66)
    /// `Option<&str>`-return accessors carry on the sibling M2 / M3
    /// typed-slot atom axes, extended here to the second outer top-level
    /// `Caixa` universal-axis surface. Named `repositorio()` to match
    /// the storage field's name; the accessor's identity maps onto the
    /// canonical CAIXA-SDLC §I vocabulary the slot's docstring already
    /// carries.
    #[must_use]
    pub const fn repositorio(&self) -> Option<&str> {
        match &self.repositorio {
            Some(s) => Some(s.as_str()),
            None => None,
        }
    }

    /// Substrate-canonical per-`Caixa` **resolved-git-repo-URL** composer —
    /// returns the caixa's canonical git-source-of-truth URL as an owned
    /// [`String`], author-declared `:repositorio` byte-string verbatim on
    /// the `Some` arm and the substrate's canonical pleme-org github URL
    /// fallback ([`crate::DEFAULT_PLEME_GIT_ORG`] and [`Self::nome`]
    /// interpolated into `https://github.com/<org>/<nome>`) on the
    /// `None` arm. Every substrate-side consumer that resolves
    /// "which git URL does this caixa's source live at?" reaches for
    /// exactly one typed dispatch on the substrate primitive — the raw
    /// `caixa.repositorio().map(str::to_owned).unwrap_or_else(|| format!(
    /// "https://github.com/{org}/{nome}", org = DEFAULT_PLEME_GIT_ORG,
    /// nome = caixa.nome()))` open-coded composition every prior caller
    /// re-derived collapses onto one canonical arm.
    ///
    /// Distinct from [`Self::repositorio`] (`Option<&str>`, exposes the
    /// author-omitted / author-declared partition to the caller) — this
    /// accessor is the **resolved** URL surface, folding the fallback in
    /// at the substrate-primitive boundary. Every consumer that keys off
    /// the `Option::is_none()` discriminator (a [`Chart.yaml`] `home:`
    /// field emit that must omit the field entirely on an author-omitted
    /// `:repositorio`, per the [`Self::repositorio`] docstring's
    /// documented four-consumer list) reaches through the raw
    /// [`Self::repositorio`] `Option<&str>` accessor by construction — the
    /// resolved-URL composer sits alongside it as the second projection
    /// on the same underlying `:repositorio` slot rather than replacing
    /// the raw accessor.
    ///
    /// The fallback branch is the exact byte-image of the prior inline
    /// [`caixa-flux::ClusterBundleOpts::for_caixa`] `git_url` composer at
    /// caixa-flux/src/lib.rs:2080 — pinned by the sibling caixa-flux
    /// byte-parity test
    /// `cluster_bundle_opts_for_caixa_git_url_routes_through_canonical_git_url_accessor`
    /// against a future implementation of this method that reordered the
    /// `format!` template arguments, migrated the `<org>` segment to a
    /// different constant (the [`crate::DEFAULT_PLEME_GIT_ORG`] axis a
    /// future substrate-side git-org migration may split off), or
    /// silently absorbed the empty-string arm (a hypothetical
    /// `Some("") → fallback` collapse the raw [`Self::repositorio`]
    /// accessor's docstring explicitly rejects on the sibling raw
    /// accessor).
    ///
    /// Peer of the sibling per-`&Caixa`-axis composed helpers
    /// [`caixa-flux::cluster_bundle_for_caixa`] (06d52d7) on the sibling
    /// substrate-side renderer surface — same "close the composed
    /// substrate-primitive at one canonical arm on the single-`&Caixa`
    /// dispatch, converge every prior open-coded caller onto the arm"
    /// discipline extended onto the resolved-git-URL projection of the
    /// per-`Caixa` `:repositorio` axis. Owns per-call [`String`]
    /// allocation on both arms (the `Some` arm's `str::to_owned` and the
    /// `None` arm's `format!`) — the by-value return matches every
    /// downstream consumer's field-fill shape (the caixa-flux
    /// `ClusterBundleOpts::git_url: String` field, every future
    /// `Chart.yaml` `home:` fold's `Option<String>` field-fill on the
    /// `Some` arm).
    #[must_use]
    pub fn canonical_git_url(&self) -> String {
        self.repositorio().map_or_else(
            || {
                format!(
                    "https://github.com/{org}/{nome}",
                    org = crate::DEFAULT_PLEME_GIT_ORG,
                    nome = self.nome(),
                )
            },
            str::to_owned,
        )
    }

    /// Substrate-canonical per-`Caixa` **resolved-publish-tag** composer —
    /// returns the caixa's canonical Zig-style git-publish-tag as an owned
    /// [`String`], derived by concatenating
    /// [`crate::DEFAULT_PUBLISH_TAG_PREFIX`] with the typed
    /// [`Self::versao`] byte-string on a single `format!` template.
    /// Every substrate-side consumer that resolves "which git tag does this
    /// caixa publish under?" reaches for exactly one typed dispatch on the
    /// substrate primitive — the raw `format!("{prefix}{versao}", prefix =
    /// caixa_core::DEFAULT_PUBLISH_TAG_PREFIX, versao = caixa.versao())`
    /// open-coded composition every prior caller re-derived collapses onto
    /// one canonical arm.
    ///
    /// Peer of the sibling [`Self::canonical_git_url`] (124f864) resolved-
    /// git-URL composer on the paired per-`Caixa` git-remote axis — same
    /// "close the composed substrate-primitive at one canonical arm on the
    /// single-`&Caixa` dispatch, converge every prior open-coded caller
    /// onto the arm" discipline extended from the resolved-URL projection
    /// of the per-`Caixa` `:repositorio` axis onto the resolved-tag
    /// projection of the per-`Caixa` `:versao` axis. The two accessors
    /// jointly close the pair of scalars every `FluxCD` `GitRepository` CR
    /// keys off (`spec.url` via [`Self::canonical_git_url`],
    /// `spec.ref.tag` via [`Self::publish_tag`]) at the substrate primitive
    /// — a downstream consumer that reaches through both accessors reads
    /// the complete published-git-identity of a caixa through two typed
    /// dispatches, not four open-coded field accesses.
    ///
    /// The reader-side (`caixa-flux::cluster_bundle` /
    /// `ClusterBundleOpts::for_caixa`'s `git_ref` field, every future
    /// per-cluster snapshot bundle emitter, the future M4
    /// `mesh.pleme.io/v1alpha1/Aplicacao` CR materializer's tag-carrier
    /// slot on the tatara `Process` intent) always resolves the tag under
    /// the canonical [`crate::DEFAULT_PUBLISH_TAG_PREFIX`] prefix — this
    /// method encodes that reader-side convention. The writer-side
    /// (`caixa-feira`'s `feira publish` `--prefix` clap flag) allows the
    /// operator to override the prefix at publish time; the two surfaces
    /// intentionally sit on the "canonical default + operator override"
    /// pair the sibling [`crate::DEFAULT_PUBLISH_TAG_PREFIX`] constant's
    /// own docstring documents — a `feira publish --prefix release/`
    /// override is the operator's explicit opt-out from the substrate
    /// default, not a supported drift axis.
    ///
    /// The composition body is the exact byte-image of the prior inline
    /// [`caixa-flux::ClusterBundleOpts::for_caixa`] `git_ref` composer at
    /// caixa-flux/src/lib.rs:2105 — pinned by the sibling caixa-flux
    /// byte-parity test
    /// `cluster_bundle_opts_for_caixa_git_ref_routes_through_publish_tag_accessor`
    /// against a future implementation of this method that reordered the
    /// `format!` template arguments, migrated the `<prefix>` segment to a
    /// different constant (the [`crate::DEFAULT_PUBLISH_TAG_PREFIX`] axis
    /// a future Zig-style-tag rebrand may split off — the constant's own
    /// docstring anticipates a substrate-side move to `release/<versao>`
    /// or bare `<versao>` shapes once a sibling forge convention adopts a
    /// slash-namespaced or bare-scalar form), interposed a canonicalization
    /// pass on the `:versao` axis (a SemVer-2 build-metadata strip an OCI-
    /// tag normalizer might apply once the M4 registry-alignment slot
    /// lands), or silently absorbed an empty `:versao` arm (which cannot
    /// occur past the [`Self::validate_versao`] gate but which a
    /// hypothetical bypass on the accessor path must not silently paper
    /// over).
    ///
    /// Owns per-call [`String`] allocation via the single `format!`
    /// invocation — the by-value return matches every downstream
    /// consumer's field-fill shape (the caixa-flux `GitRefSpec::Tag(String)`
    /// variant's owned payload, every future `intent.aplicacao.tag: String`
    /// field-fill on the M4 CR materializer's tag-carrier slot).
    #[must_use]
    pub fn publish_tag(&self) -> String {
        format!(
            "{prefix}{versao}",
            prefix = crate::DEFAULT_PUBLISH_TAG_PREFIX,
            versao = self.versao(),
        )
    }

    /// Substrate-canonical per-`Caixa` **resolved-Helm-chart-name** composer
    /// — returns the caixa's canonical `lareira-<nome>` per-Servico Helm
    /// chart identity as an owned [`String`], derived by dispatching through
    /// the substrate-canonical [`crate::lareira_chart_name`] helper against
    /// the typed [`Self::nome`] byte-string. Every substrate-side consumer
    /// that resolves "which Helm chart identity does this caixa render
    /// under?" reaches for exactly one typed dispatch on the substrate
    /// primitive — the raw `caixa_core::lareira_chart_name(caixa.nome())`
    /// two-step compose every prior caller re-derived collapses onto one
    /// canonical arm on the single-`&Caixa` dispatch.
    ///
    /// Peer of the sibling [`Self::canonical_git_url`] (124f864) resolved-
    /// git-URL composer + [`Self::publish_tag`] (07e05b8) resolved-publish-
    /// tag composer on the paired per-`Caixa` published-artifact-identity
    /// axis — same "close the composed substrate-primitive at one canonical
    /// arm on the single-`&Caixa` dispatch, converge every prior open-coded
    /// caller onto the arm" discipline extended from the resolved-URL /
    /// resolved-tag projections of the `:repositorio` / `:versao` axes onto
    /// the resolved-chart-name projection of the `:nome` axis. The three
    /// accessors jointly close the triple of scalars every per-Servico
    /// deploy artifact keys off (git source URL via
    /// [`Self::canonical_git_url`], git source tag via
    /// [`Self::publish_tag`], per-Servico Helm chart identity via
    /// [`Self::lareira_chart_name`]) at the substrate primitive — a
    /// downstream consumer that reaches through all three reads the
    /// complete deploy-artifact identity of a caixa through three typed
    /// dispatches, not six open-coded compositions across three renderer
    /// crates.
    ///
    /// The reader-side (three production sites at the time of the lift —
    /// [`caixa-helm::render_chart_for_servico_with`]'s `ChartDir.name`
    /// composer at caixa-helm/src/lib.rs:778, the peer
    /// [`caixa-flux::cluster_bundle`]'s per-CR `chart_name` binding at
    /// caixa-flux/src/lib.rs:2219, and
    /// [`caixa-tatara::process_for_aplicacao`]'s `release_name`
    /// composer at caixa-tatara/src/lib.rs:227, plus every future
    /// per-Servico OCI publish emitter the CAIXA-SDLC §II
    /// `caixa-publish.yml` reusable workflow's `skopeo push` step keys
    /// off, the future per-cluster snapshot bundle emitter, the future
    /// M4 `mesh.pleme.io/v1alpha1/Aplicacao` CR materializer's
    /// per-member chart-carrier slot on the tatara `Process` intent) —
    /// always resolves the chart name under the canonical
    /// [`crate::LAREIRA_CHART_NAME_PREFIX`] prefix; this method encodes
    /// that reader-side convention. The joint-length invariant the peer
    /// [`Self::validate_nome_chart_name_budget`] gate enforces at
    /// caixa-build time (author-declared `:nome` + fixed prefix ≤
    /// [`crate::DNS_1123_LABEL_MAX_LEN`]) is verified on the input to
    /// this composer by construction, so the produced `lareira-<nome>`
    /// string is a valid Helm chart-name segment on every accept-set
    /// input.
    ///
    /// The composition body is the exact byte-image of the prior inline
    /// `caixa_core::lareira_chart_name(caixa.nome())` two-step form every
    /// prior caller re-derived — pinned by the sibling caixa-helm /
    /// caixa-flux / caixa-tatara byte-parity tests
    /// `<crate>_lareira_chart_name_routes_through_caixa_accessor` against
    /// a future implementation of this method that reordered the
    /// composition arguments, migrated the `<prefix>` segment to a
    /// different constant (the [`crate::LAREIRA_CHART_NAME_PREFIX`] axis a
    /// future substrate-side chart-family rebrand may split off — the
    /// constant's own docstring anticipates a substrate-side move once
    /// the `lareira-` scoping intent outlives the family it names),
    /// interposed a canonicalization pass on the `:nome` axis (a per-
    /// registry namespace-qualification an M4 CR materializer might apply
    /// per-CR — the "`pleme-io/checkout` vs `partner-org/checkout`
    /// collision" arm the multi-tenant-registry story acknowledges), or
    /// silently absorbed an empty `:nome` arm (which cannot occur past
    /// the [`Self::validate_nome`] gate but which a hypothetical bypass
    /// on the accessor path must not silently paper over).
    ///
    /// Owns per-call [`String`] allocation via the single
    /// [`crate::lareira_chart_name`] `format!` invocation — the by-value
    /// return matches every downstream consumer's field-fill shape (the
    /// caixa-helm `ChartDir.name: String` field, the caixa-flux per-CR
    /// `chart_name: String` binding, the caixa-tatara
    /// `AplicacaoIntent.release_name: Option<String>` field-fill on the
    /// `Some` arm).
    #[must_use]
    pub fn lareira_chart_name(&self) -> String {
        crate::lareira_chart_name(self.nome())
    }

    /// Substrate-canonical per-`Caixa` **resolved-OCI-chart-ref** composer
    /// — returns the caixa's canonical `oci://<registry>/lareira-<nome>`
    /// per-Servico Helm chart OCI artifact reference as an owned
    /// [`String`], derived by dispatching through the substrate-canonical
    /// [`crate::oci_chart_ref`] helper (which itself composes
    /// [`crate::OCI_SCHEME_PREFIX`] + the caller-supplied `registry` +
    /// [`crate::lareira_chart_name`]-of-[`Self::nome`]) against the
    /// caller-supplied `registry` and the typed [`Self::nome`] byte-string.
    /// Every substrate-side consumer that resolves "which OCI chart
    /// artifact does this caixa publish under, in this registry?" reaches
    /// for exactly one typed dispatch on the substrate primitive — the raw
    /// `caixa_core::oci_chart_ref(registry, caixa.nome())` two-step compose
    /// every prior caller re-derived collapses onto one canonical arm on
    /// the single-`(&Caixa, &str)` dispatch.
    ///
    /// Fourth member of the paired per-`Caixa` published-artifact-identity
    /// axis alongside [`Self::canonical_git_url`] (124f864) /
    /// [`Self::publish_tag`] (07e05b8) / [`Self::lareira_chart_name`]
    /// (a8f0bee) — same "close the composed substrate-primitive at one
    /// canonical arm on the single-`&Caixa` dispatch, converge every
    /// prior open-coded caller onto the arm" discipline extended from the
    /// resolved-URL / resolved-tag / resolved-chart-name projections of
    /// the `:repositorio` / `:versao` / `:nome` axes onto the resolved-
    /// OCI-ref projection over the paired `(registry, :nome)` inputs. The
    /// four accessors jointly close the per-`Caixa` published-artifact-
    /// identity surface every downstream consumer of a caixa's published
    /// deploy artifacts keys off (git source URL via
    /// [`Self::canonical_git_url`], git source tag via
    /// [`Self::publish_tag`], per-Servico Helm chart identity via
    /// [`Self::lareira_chart_name`], per-registry OCI chart artifact
    /// reference via [`Self::oci_chart_ref`]) at the substrate primitive
    /// — a downstream consumer that reaches through all four reads the
    /// complete deploy-artifact identity of a caixa through four typed
    /// dispatches, not eight open-coded compositions across four renderer
    /// crates. The unique-signature dispatch (`(&Caixa, &str)` on this
    /// method vs. `&Caixa` on the sibling three) reflects the extra input
    /// axis this composer folds in: unlike the git-URL / git-tag / chart-
    /// name axes (each derived purely from a `&Caixa`), the OCI-ref axis
    /// pairs the caixa's per-`:nome` chart identity with the caller-
    /// supplied per-registry authority segment, so the accessor threads
    /// the registry byte-string through as a positional `&str`.
    ///
    /// The reader-side (one production site at the time of the lift —
    /// [`caixa-tatara::process_for_aplicacao`]'s `derive_chart_ref` helper
    /// at caixa-tatara/src/lib.rs:333 that composes the emitted
    /// `AplicacaoIntent.chart_ref` scalar the tatara-reconciler feeds into
    /// `helm install`, plus every future per-Servico OCI publish emitter
    /// the CAIXA-SDLC §II `caixa-publish.yml` reusable workflow's
    /// `skopeo push` step keys off, the future per-cluster snapshot bundle
    /// emitter's per-CR `oci://…` field-fill on the M4 registry-alignment
    /// slot, the future M4 `mesh.pleme.io/v1alpha1/Aplicacao` CR
    /// materializer's per-member `chart_ref` slot on the tatara `Process`
    /// intent, the `FluxCD` `HelmRelease` `spec.chart.spec.chart` field-fill
    /// on the OCI-source path an M4 per-cluster registry-rewrite overlay
    /// applies per-CR) — always resolves the OCI ref under the canonical
    /// [`crate::OCI_SCHEME_PREFIX`] scheme prefix + the canonical
    /// [`Self::lareira_chart_name`] chart-name segment; this method
    /// encodes that reader-side convention.
    ///
    /// The composition body is the exact byte-image of the prior inline
    /// `caixa_core::oci_chart_ref(registry, caixa.nome())` two-step form
    /// every prior caller re-derived — pinned by the sibling caixa-tatara
    /// byte-parity test
    /// `derive_chart_ref_routes_through_caixa_oci_chart_ref_accessor`
    /// against a future implementation of this method that reordered the
    /// composition arguments, migrated the `<scheme>` segment to a
    /// different constant (the [`crate::OCI_SCHEME_PREFIX`] axis a future
    /// substrate-side registry-protocol rebrand may split off — the
    /// constant's own docstring anticipates a substrate-side move once
    /// Helm 3 / `FluxCD` introduce a successor scheme past `oci://`),
    /// migrated the `<chart>` segment off the paired
    /// [`crate::lareira_chart_name`] composer (a per-registry
    /// namespace-qualification an M4 CR materializer might apply per-CR),
    /// interposed a canonicalization pass on the `registry` axis (an OCI-
    /// authority normalization once the M4 registry-alignment slot lands),
    /// or silently absorbed an empty `:nome` arm (which cannot occur past
    /// the [`Self::validate_nome`] gate but which a hypothetical bypass
    /// on the accessor path must not silently paper over).
    ///
    /// Owns per-call [`String`] allocation via the single
    /// [`crate::oci_chart_ref`] `format!` invocation — the by-value return
    /// matches every downstream consumer's field-fill shape (the caixa-
    /// tatara `AplicacaoIntent.chart_ref: String` field-fill, every
    /// future `intent.aplicacao.chart_ref: String` field-fill on the M4
    /// CR materializer's chart-ref-carrier slot, every future
    /// `HelmRelease.spec.chart.spec.chart: String` field-fill on the OCI-
    /// source path).
    #[must_use]
    pub fn oci_chart_ref(&self, registry: &str) -> String {
        crate::oci_chart_ref(registry, self.nome())
    }

    /// Substrate-canonical per-`Caixa` `:descricao` free-form-prose
    /// chart-description scalar accessor every consumer of the top-level
    /// manifest's Chart.yaml `description:` axis keys off — returns the
    /// author-declared `:descricao` byte-string verbatim as an
    /// `Option<&str>`, borrowed from the typed slot's own
    /// `Option<String>` storage. `None` when the slot is absent (the
    /// canonical "omit to defer to the per-renderer `caixa.nome`-derived
    /// fallback" shape — [`caixa-helm`]'s `build_chart_yaml` folds the
    /// omitted slot through a `format!("Generated chart for caixa Servico
    /// {}", caixa.nome)` fallback, [`caixa-helm`]'s `build_readme` folds
    /// it through a `format!("caixa Servico {}", caixa.nome)` fallback,
    /// and [`caixa-feira`]'s `render_flake` folds it through a
    /// `format!("caixa {}", c.nome)` `flake.nix` `description = ""`
    /// fallback — each derived from `caixa.nome` on the null-carrier arm).
    ///
    /// The `:descricao` slot carries the universal-axis free-form-prose
    /// chart-description identifier every kind of caixa emits under
    /// (CAIXA-SDLC §I — the author-facing surface every `defcaixa` form
    /// supplies) — the typed slot's `Option<String>` accept-set
    /// (empty-string rejected through [`ManifestError::DescricaoEmpty`],
    /// chart-description-shape-invalid rejected through
    /// [`ManifestError::DescricaoInvalid`] past the shared
    /// [`crate::render::is_chart_description_shape`] predicate the peer
    /// per-`Caixa` `:descricao` axis also routes through) maps onto four
    /// load-bearing downstream consumers:
    ///
    ///   - [`Self::validate_descricao`]'s empty-arm + shape-predicate
    ///     gate binding — the universal-axis identity gate wired at
    ///     caixa-build time.
    ///   - [`caixa-helm`]'s `build_chart_yaml` `ChartYaml.description`
    ///     `Chart.yaml` field fold — the rendered `lareira-<nome>` Helm
    ///     chart's `Chart.yaml` `description:` field, which
    ///     `apiVersion: v2` charts require non-empty (`helm lint` fires
    ///     `WARNING [chart.metadata.description]: description is required`
    ///     when absent) and which every registry that ingests the chart
    ///     (ArtifactHub, chartmuseum, `helm search repo`) surfaces as the
    ///     chart's canonical one-line prose descriptor.
    ///   - [`caixa-helm`]'s `build_readme` chart-`README.md` header fold
    ///     — the rendered `lareira-<nome>` chart's `README.md` prose
    ///     header directly beneath the `# <chart-name>` title, which
    ///     every author who inspects the rendered chart bundle lands at.
    ///   - [`caixa-feira`]'s `render_flake` `flake.nix` `description = ""`
    ///     top-level fold — the emitted `flake.nix`'s `description`
    ///     field, which every Nix consumer (`nix flake show`,
    ///     `nix flake metadata`, downstream flake-registry ingestors)
    ///     surfaces as the flake's canonical descriptor.
    ///
    /// Prior to this lift the `.descricao` field was accessed inline at
    /// four production sites — [`Self::validate_descricao`]'s
    /// `self.descricao.as_deref()` empty-and-shape gate binding, the
    /// caixa-helm `build_chart_yaml`
    /// `caixa.descricao.clone().unwrap_or_else(|| format!(...))`
    /// `Chart.yaml` `description:` fold, the caixa-helm `build_readme`
    /// `caixa.descricao.clone().unwrap_or_else(|| format!(...))`
    /// `README.md` header fold, and the caixa-feira `render_flake`
    /// `c.descricao.clone().unwrap_or_else(|| format!(...))` `flake.nix`
    /// `description = ""` fold — four open-coded field-accesses that
    /// expressed no compile-time link back to the typed slot. A future
    /// extension of the `:descricao` axis to a richer author surface —
    /// a per-`:descricao` locale-tagged multi-language descriptor map
    /// (the "one caixa, N language-tagged prose descriptions" arm
    /// author-tooling internationalization anticipates), a
    /// per-registry-target length-and-shape overlay the M4 CR
    /// materializer resolves per-CR (the "ArtifactHub caps description
    /// at 512 bytes but the internal registry caps at 256" arm), a
    /// promotion of the plain `Option<String>` byte-string to a richer
    /// `ChartDescription` newtype guaranteeing the
    /// `is_chart_description_shape` predicate at the type level — would
    /// have had to be threaded through all four open-coded copies in
    /// lockstep or the validate gate and the three emit paths would
    /// silently disagree on which prose string a given [`Caixa`]
    /// resolves to (an author's
    /// `:descricao "Checkout flow orchestration."` would satisfy
    /// validate while one of the emit paths silently rendered a stale
    /// `caixa.nome`-derived fallback, or vice versa). Lifting the
    /// resolution to a typed method on the substrate primitive means
    /// every downstream consumer of the caixa's per-`Caixa`
    /// chart-description surface reaches for exactly one typed dispatch
    /// — the resolver's accept-set migrates as a unit on any future
    /// axis addition.
    ///
    /// Third outer top-level [`Caixa`] `Option<&str>`-return scalar
    /// accessor — sibling of [`Self::licenca`] (6d5bc28) and
    /// [`Self::repositorio`] (cc7332d), the accessors that opened the
    /// "outer [`Caixa`] `Option<&str>` scalar" projection pattern this
    /// lift folds on. Same "one typed dispatch on the substrate
    /// primitive, thin projections at each consumer" discipline the
    /// peer per-`:placement`
    /// [`crate::aplicacao::Placement::shard_key`] (7cd2a28) /
    /// [`crate::aplicacao::Placement::affinity`] (74ec2d3) /
    /// per-`:contratos` [`crate::aplicacao::WitContract::endpoint`]
    /// (7020470) / [`crate::aplicacao::WitContract::subject`] (90de675)
    /// / [`crate::aplicacao::WitContract::slot`] (ed22b66)
    /// `Option<&str>`-return accessors carry on the sibling M2 / M3
    /// typed-slot atom axes, extended here to the third outer top-level
    /// `Caixa` universal-axis surface. Named `descricao()` to match the
    /// storage field's name; the accessor's identity maps onto the
    /// canonical CAIXA-SDLC §I vocabulary the slot's docstring already
    /// carries. The one remaining universal `Option<String>` slot
    /// (`:edicao`) folds on this pattern next.
    #[must_use]
    pub const fn descricao(&self) -> Option<&str> {
        match &self.descricao {
            Some(s) => Some(s.as_str()),
            None => None,
        }
    }

    /// Substrate-canonical per-`Caixa` `:edicao` language-edition scalar
    /// accessor every consumer of the top-level manifest's tatara-lisp
    /// edition-selector axis keys off — returns the author-declared
    /// `:edicao` byte-string verbatim as an `Option<&str>`, borrowed from
    /// the typed slot's own `Option<String>` storage. `None` when the
    /// slot is absent (the canonical "omit the slot to defer to the
    /// substrate's default edition" shape every existing
    /// [`caixa-resolver`] integration test fixture carries via
    /// `edicao: None` — see `caixa-resolver/tests/git_integration.rs`;
    /// the peer [`Self::validate_edicao`] gate is a no-op on the omitted
    /// arm by construction, so an author-omitted `:edicao` round-trips
    /// to a build without triggering the year-shape predicate).
    ///
    /// The `:edicao` slot carries the universal-axis 4-digit-ASCII-
    /// decimal-year language-edition identifier every kind of caixa
    /// emits under (CAIXA-SDLC §I — the author-facing surface every
    /// `defcaixa` form supplies) — the typed slot's `Option<String>`
    /// accept-set (empty-string rejected through
    /// [`ManifestError::EdicaoEmpty`], year-shape-invalid rejected
    /// through [`ManifestError::EdicaoInvalid`] past the 4-digit-ASCII-
    /// decimal-year predicate [`Self::validate_edicao`] enforces) maps
    /// onto one load-bearing downstream consumer today
    /// ([`Self::validate_edicao`]'s empty-arm + year-shape-predicate
    /// gate binding at caixa-core/src/manifest.rs:1959) plus every
    /// future edition-aware substrate consumer the CAIXA-SDLC §I
    /// roadmap anticipates (the tatara-lisp compiler's macro-surface
    /// selector every edition-aware build step keys off, the future
    /// per-edition compatibility-flag overlay the M4 CR materializer
    /// resolves per-CR, the peer [`Caixa::template`] canonical
    /// `:edicao "2026"` scaffold every `feira init` emits verbatim,
    /// and the renderer-side fixtures at `caixa-helm/src/lib.rs:978` /
    /// `caixa-flux/src/lib.rs:2319` / `caixa-mesh/src/lib.rs:3208` that
    /// carry `edicao: Some("2026".into())` by construction).
    ///
    /// Prior to this lift the `.edicao` field was accessed inline at
    /// one production site — [`Self::validate_edicao`]'s
    /// `self.edicao.as_deref()` empty-and-shape gate binding — one
    /// open-coded field-access that expressed no compile-time link
    /// back to the typed slot. A future extension of the `:edicao`
    /// axis to a richer author surface — a per-`:edicao` known-
    /// edition allowlist (the future tightening
    /// [`Self::validate_edicao`]'s docstring acknowledges past the
    /// structural year-shape floor, rejecting year-shaped values that
    /// don't name a tatara-lisp edition the substrate actually
    /// understands — `"1999"` is year-shaped but no `1999` edition
    /// exists), a per-edition compatibility-flag overlay the M4 CR
    /// materializer resolves per-CR (the "edition `"2026"` enables
    /// macro-surface features the sibling `"2018"` gates behind a
    /// feature flag" arm the edition-selector story anticipates), a
    /// promotion of the plain `Option<String>` byte-string to a
    /// richer `CaixaEdition` enum discriminated on year once a sibling
    /// edition to `"2026"` lands — would have had to be threaded
    /// through the open-coded copy in lockstep with every future
    /// edition-aware consumer, or the validate gate and the future
    /// edition-aware consumer path would silently disagree on which
    /// edition a given [`Caixa`] resolves to (an author's
    /// `:edicao "2026"` would satisfy validate while a future
    /// edition-aware consumer silently defaulted to a stale edition,
    /// or vice versa). Lifting the resolution to a typed method on
    /// the substrate primitive means every downstream consumer of the
    /// caixa's per-`Caixa` edition surface reaches for exactly one
    /// typed dispatch — the resolver's accept-set migrates as a unit
    /// on any future axis addition.
    ///
    /// Fourth and final outer top-level [`Caixa`] `Option<&str>`-return
    /// scalar accessor — sibling of [`Self::licenca`] (6d5bc28),
    /// [`Self::repositorio`] (cc7332d), and [`Self::descricao`]
    /// (3f16e2f), the accessors that opened the "outer [`Caixa`]
    /// `Option<&str>` scalar" projection pattern this lift folds on.
    /// Same "one typed dispatch on the substrate primitive, thin
    /// projections at each consumer" discipline the peer per-`:placement`
    /// [`crate::aplicacao::Placement::shard_key`] (7cd2a28) /
    /// [`crate::aplicacao::Placement::affinity`] (74ec2d3) /
    /// per-`:contratos` [`crate::aplicacao::WitContract::endpoint`]
    /// (7020470) / [`crate::aplicacao::WitContract::subject`] (90de675)
    /// / [`crate::aplicacao::WitContract::slot`] (ed22b66)
    /// `Option<&str>`-return accessors carry on the sibling M2 / M3
    /// typed-slot atom axes, extended here to close the outer top-level
    /// `Caixa` universal-axis surface's last unlifted `Option<String>`
    /// slot. Named `edicao()` to match the storage field's name; the
    /// accessor's identity maps onto the canonical CAIXA-SDLC §I
    /// vocabulary the slot's docstring already carries.
    #[must_use]
    pub const fn edicao(&self) -> Option<&str> {
        match &self.edicao {
            Some(s) => Some(s.as_str()),
            None => None,
        }
    }

    /// Substrate-canonical per-`Caixa` `:nome` universal-axis DNS-1123-
    /// label caixa-identity scalar accessor every consumer of the top-
    /// level manifest's identity axis keys off — returns the author-
    /// declared `:nome` byte-string verbatim as an `&str`, borrowed from
    /// the typed slot's own `String` storage. Non-optional (`:nome` is
    /// a required-axis scalar every `defcaixa` form must supply; the
    /// [`Self::from_lisp`] derive rejects an omitted / non-string
    /// `:nome` at parse time, so a `Caixa` past parse definitionally
    /// carries a non-`None` `:nome`).
    ///
    /// The `:nome` slot carries the universal-axis DNS-1123-label
    /// caixa-identity every kind of caixa emits under (CAIXA-SDLC §I —
    /// the primary identity axis every `defcaixa` form supplies
    /// alongside `:versao` / `:kind`; the substrate-wide identity every
    /// other typed surface that names a caixa reaches through — `:deps`
    /// entries, `:membros` entries, `:children` entries, the
    /// `lareira-<nome>` Helm chart name every per-Servico renderer
    /// derives, the `pleme-program-<nome>` label every per-Aplicacao
    /// renderer emits) — the typed slot's `String` accept-set (empty
    /// rejected through [`ManifestError::NomeEmpty`], DNS-1123-shape-
    /// invalid rejected through [`ManifestError::NomeInvalid`] past
    /// the shared [`crate::render::require_valid_dns_1123_label`] gate
    /// the peer name axes each land on, joint-length-with-`lareira-`-
    /// prefix rejected through
    /// [`ManifestError::NomeChartNameBudgetExceeded`] past
    /// [`crate::render::is_lareira_chart_name_shape`]) maps onto every
    /// load-bearing downstream consumer the substrate carries — the
    /// two universal-axis validate gates at caixa-build time
    /// ([`Self::validate_nome`] + [`Self::validate_nome_chart_name_budget`]),
    /// [`crate::lareira_chart_name`]'s `lareira-<nome>` Helm chart-name
    /// derivation every per-Servico renderer keys off, the caixa-helm
    /// `Chart.yaml`'s `name:` axis, caixa-flux's `programs.yaml` entry
    /// `name:` axis, caixa-mesh's Cilium `CiliumNetworkPolicy` /
    /// `HTTPRoute` per-Aplicacao name axes at
    /// caixa-mesh/src/lib.rs:{2650, 2797, 2919, 2925},
    /// [`crate::pleme_program_selector`] /
    /// [`crate::pleme_program_in_aplicacao_selector`] label-selector
    /// derivations, and every future substrate renderer that emits an
    /// artifact keyed by the caixa's identity.
    ///
    /// Prior to this lift the `.nome` field was accessed inline at a
    /// dozen production sites across `caixa-core` (the two universal-
    /// axis validate gates + [`Dep::validate`]-adjacent duplicate
    /// tracking), `caixa-helm` (the `lareira_chart_name` fold, the
    /// `ChartYaml.name` / `ChartYaml.description` / `Chart.yaml`
    /// `keywords` fallback), `caixa-flux` (the `programs.yaml`
    /// entry `name:` fold, the `flux_kustomization_source_subtree`
    /// per-cluster subpath derivation), and `caixa-mesh` (the
    /// `pleme_program_in_aplicacao_selector` label-selector fold, the
    /// `cilium_network_policy_name` / `gateway_api_http_route_name`
    /// per-CR name derivations, the `LABEL_APLICACAO` labels-map
    /// insert) — a dozen open-coded field-accesses that expressed no
    /// compile-time link back to the typed slot. A future extension of
    /// the `:nome` axis to a richer author surface — a per-`:nome`
    /// structured `CaixaIdentity` newtype that carries the joint-
    /// length-with-prefix invariant [`Self::validate_nome_chart_name_budget`]
    /// enforces at the type level (rather than as a validate-time
    /// gate), a per-registry `:nome` namespacing overlay the M4 CR
    /// materializer resolves per-CR (the "`pleme-io/checkout` vs
    /// `partner-org/checkout` collision" arm the multi-tenant-registry
    /// story acknowledges), a promotion of the plain `String` byte-
    /// string to a richer `CaixaNome` newtype discriminated on
    /// namespace prefix — would have had to be threaded through every
    /// open-coded copy in lockstep or the two validate gates and the
    /// dozen emit paths would silently disagree on which identity a
    /// given [`Caixa`] resolves to (an author's `:nome "checkout"`
    /// would satisfy validate while one of the emit paths silently
    /// rendered a drifted other identity, or vice versa). Lifting the
    /// resolution to a typed method on the substrate primitive means
    /// every downstream consumer of the caixa's per-`Caixa` identity
    /// surface reaches for exactly one typed dispatch — the resolver's
    /// accept-set migrates as a unit on any future axis addition.
    ///
    /// First outer top-level [`Caixa`] `&str`-return required-scalar
    /// accessor — opens the "outer [`Caixa`] `&str` required-scalar"
    /// projection pattern the sibling per-`Caixa` `:versao` future lift
    /// folds on. Sibling in shape to the peer per-`:membros`
    /// [`crate::aplicacao::Membro::nome`] (4a32abf) / per-`:contratos`
    /// [`crate::aplicacao::WitContract::source`] /
    /// [`crate::aplicacao::WitContract::destination`] (7f0fd43),
    /// [`crate::aplicacao::WitContract::world_ref`] (0804823),
    /// [`crate::aplicacao::Membro::versao_requirement`] (a40b0e3),
    /// [`crate::aplicacao::Entrada::destination`] (6db982c),
    /// [`crate::aplicacao::CircuitBreaker::max_failures`] (3a74062),
    /// per-sub-struct required-axis accessors carry on the sibling M3
    /// mesh-slot-atom scalar-value axes, extended here to open the
    /// outer top-level [`Caixa`] `&str`-return required-scalar surface.
    /// Named `nome()` to match the storage field's name; the accessor's
    /// identity maps onto the canonical CAIXA-SDLC §I vocabulary the
    /// slot's docstring already carries.
    #[must_use]
    pub const fn nome(&self) -> &str {
        self.nome.as_str()
    }

    /// Substrate-canonical per-`Caixa` `:versao` universal-axis SemVer-2
    /// pinned-version scalar accessor every consumer of the top-level
    /// manifest's version axis keys off — returns the author-declared
    /// `:versao` byte-string verbatim as an `&str`, borrowed from the
    /// typed slot's own `String` storage. Non-optional (`:versao` is a
    /// required-axis scalar every `defcaixa` form must supply alongside
    /// `:nome` / `:kind`; the [`Self::from_lisp`] derive rejects an
    /// omitted / non-string `:versao` at parse time, so a `Caixa` past
    /// parse definitionally carries a non-`None` `:versao`).
    ///
    /// The `:versao` slot carries the universal-axis SemVer-2
    /// concrete-version body every kind of caixa emits under
    /// (CAIXA-SDLC §I — the required-scalar every `defcaixa` form
    /// supplies alongside `:nome` / `:kind`; the substrate-wide
    /// pinned-version every downstream artifact-emitting consumer
    /// composes under — the `lareira-<nome>` Helm chart's `Chart.yaml`
    /// `version:` + `appVersion:` axes, the `feira publish` Zig-style
    /// `v<versao>` git tag the [`crate::DEFAULT_PUBLISH_TAG_PREFIX`]
    /// prefix composes on top of, the programs.yaml entry's `versao:`
    /// value the `lareira-fleet-programs` aggregator carries onto each
    /// rendered `ComputeUnit`, the OCI image's `:v<versao>` / `:latest`
    /// tags every substrate-side `skopeo push` writes, the lacre
    /// closure's pinned `concrete_versao`, and the `:upgrade-from :from`
    /// prior-version references peers in the exact same SemVer-2 shape).
    /// The typed slot's `String` accept-set (empty rejected through
    /// [`ManifestError::VersaoEmpty`], SemVer-2-shape-invalid rejected
    /// through [`ManifestError::VersaoInvalid`] past
    /// [`semver::Version::parse`]) maps onto every load-bearing
    /// downstream consumer the substrate carries — the [`Self::validate_versao`]
    /// universal-axis validate gate at caixa-build time, the
    /// [`crate::CaixaVersion::parse`] typed-wrapper resolver,
    /// [`caixa-helm`]'s `Chart.yaml` `version:` / `appVersion:` fold,
    /// [`caixa-flux`]'s `programs.yaml` entry `versao:` fold + the
    /// `cluster_bundle` `GitRepository` `ref: { tag: v<versao> }`
    /// derivation, [`caixa-mesh`]'s per-Aplicacao `programs.yaml` fan-
    /// out entry `versao:` fold, [`caixa-feira`]'s `feira publish` git-
    /// tag derivation (`format!("{prefix}{versao}")`), and every future
    /// substrate renderer that emits an artifact keyed by the caixa's
    /// pinned version.
    ///
    /// Prior to this lift the `.versao` field was accessed inline at a
    /// dozen production sites across `caixa-core` (the universal-axis
    /// [`Self::validate_versao`] gate + [`Dep::validate`]-adjacent
    /// version-shape gates), `caixa-helm` (the `ChartYaml.version` /
    /// `ChartYaml.app_version` folds), `caixa-flux` (the `programs.yaml`
    /// entry `versao:` fold, the `cluster_bundle` `GitRepository` `ref:
    /// { tag: v<versao> }` derivation), `caixa-mesh` (the per-Aplicacao
    /// `programs.yaml` fan-out entry `versao:` fold), and `caixa-feira`
    /// (the `feira publish` git-tag derivation + the `feira app graph` /
    /// `feira app deploy` diagnostic renderers) — a dozen open-coded
    /// field-accesses that expressed no compile-time link back to the
    /// typed slot. A future extension of the `:versao` axis to a richer
    /// author surface — a per-`:versao` structured `CaixaVersion` at the
    /// storage layer (the substrate already carries a `CaixaVersion`
    /// newtype at [`crate::version::CaixaVersion`], deferred until the
    /// serde-transparent-newtype-through-DeriveTataraDomain path lands),
    /// a per-registry `:versao` immutability overlay the M4 CR
    /// materializer enforces per-CR, a promotion of the plain `String`
    /// byte-string to a richer `PinnedVersao` newtype discriminated on
    /// SemVer-2 pre-release / build-metadata presence — would have had
    /// to be threaded through every open-coded copy in lockstep or the
    /// validate gate and the dozen emit paths would silently disagree
    /// on which version a given [`Caixa`] resolves to (an author's
    /// `:versao "0.1.0"` would satisfy validate while one of the emit
    /// paths silently rendered a drifted other version, or vice versa).
    /// Lifting the resolution to a typed method on the substrate
    /// primitive means every downstream consumer of the caixa's
    /// per-`Caixa` pinned-version surface reaches for exactly one typed
    /// dispatch — the resolver's accept-set migrates as a unit on any
    /// future axis addition.
    ///
    /// Second outer top-level [`Caixa`] `&str`-return required-scalar
    /// accessor — folds on the "outer [`Caixa`] `&str` required-scalar"
    /// projection pattern the sibling per-`Caixa` [`Self::nome`]
    /// (e6b7d97) opened. Sibling in shape to the peer per-`:membros`
    /// [`crate::aplicacao::Membro::versao_requirement`] (4127bb6) /
    /// per-`:children` [`crate::supervisor::ChildSpec::versao_requirement`]
    /// (2c053c8) / per-`:upgrade-from` [`crate::UpgradeFromEntry::prior_versao`]
    /// (75d27a8) per-sub-struct `:versao`-shaped `&str`-return accessors
    /// on the sibling per-typed-slot version-carrier axes, extended here
    /// to close the second outer top-level [`Caixa`] required-`&str`-
    /// carrying axis so the two universal-axis identity-carrying
    /// scalars every `defcaixa` form supplies (`:nome` + `:versao`)
    /// share the same "one typed dispatch per axis" discipline. Named
    /// `versao()` to match the storage field's name; the accessor's
    /// identity maps onto the canonical CAIXA-SDLC §I vocabulary the
    /// slot's docstring already carries.
    #[must_use]
    pub const fn versao(&self) -> &str {
        self.versao.as_str()
    }

    /// Substrate-canonical per-`Caixa` `:kind` universal-axis
    /// closed-set-enum discriminant accessor every consumer of the top-
    /// level manifest's kind axis keys off — returns the author-declared
    /// `:kind` variant verbatim as a [`CaixaKind`], `Copy`-projected
    /// from the typed slot's own [`CaixaKind`] storage. Non-optional
    /// (`:kind` is a required-axis discriminant every `defcaixa` form
    /// must supply alongside `:nome` / `:versao`; the [`Self::from_lisp`]
    /// derive rejects an omitted / non-symbol `:kind` at parse time, so
    /// a `Caixa` past parse definitionally carries a valid [`CaixaKind`]
    /// variant).
    ///
    /// The `:kind` slot carries the universal-axis closed-set typed-
    /// discriminant every substrate-side dispatch keys off (CAIXA-SDLC
    /// §I — the primary shape gate every renderer / verifier /
    /// operator branches on; the five variants `Biblioteca` /
    /// `Binario` / `Servico` / `Supervisor` / `Aplicacao` partition
    /// the caixa surface into disjoint runtime contracts) — the typed
    /// slot's [`CaixaKind`] accept-set (parse-time-rejected non-symbol
    /// values through the derive-macro's symbol-arm gate, exhaustively
    /// matched at every downstream dispatch site) maps onto every
    /// load-bearing downstream consumer the substrate carries:
    ///
    ///   - [`crate::render::require_kind`]'s per-renderer entry-gate
    ///     predicate — the canonical two-line
    ///     `require_kind(caixa, Servico)?` prelude every per-Servico
    ///     renderer (`caixa-helm`, `caixa-flux`, the future `caixa-otel`
    ///     / per-Servico OCI packager / M4 `wasm.pleme.io/v1alpha1/
    ///     ComputeUnit` CR materializer) runs at its entry-point,
    ///     alongside the [`crate::render::KindMismatch`] error carrier's
    ///     `actual:` field the diagnostic surfaces to name the offending
    ///     caixa's variant.
    ///   - [`Self::aplicacao_view`]'s + [`Self::supervisor_view`]'s
    ///     per-view kind-gate binding — the two `Option<TypedSpec>`
    ///     `_view` composers that fold the flat mesh-slot / supervisor-
    ///     slot columns into their typed sub-spec only when the kind
    ///     matches (returns `None` otherwise); the future per-Servico
    ///     M2-view composer (`servico_view`) will follow the same shape.
    ///   - [`Self::declared_foreign_code_slots`]'s per-slot kind-
    ///     coherence gate — the `!self.kind.requires_exe()` /
    ///     `!self.kind.requires_servicos()` predicates that fence
    ///     each code-surface slot from the wrong owning kind.
    ///   - [`crate::LayoutInvariants::verify`]'s kind ↔ code-surface
    ///     coherence gates — the six `caixa.kind == CaixaKind::X` /
    ///     `caixa.kind != CaixaKind::X` predicates and the four kind-
    ///     coherence error carriers (`SupervisorOwnsCode` /
    ///     `AplicacaoOwnsCode` / `MeshSlotsOnNonAplicacao` /
    ///     `SupervisorSlotsOnNonSupervisor` / `ServicoSlotsOnNonServico`
    ///     / `ForeignCodeSlot`) which each name the offending caixa's
    ///     variant in their `kind:` field.
    ///
    /// Prior to this lift the `.kind` field was accessed inline at
    /// twenty-plus production sites across `caixa-core` (the
    /// [`crate::render::require_kind`] entry-gate predicate + the
    /// [`crate::render::KindMismatch`] `actual:` field, the two `_view`
    /// composers, the `declared_foreign_code_slots` per-slot kind-
    /// coherence gate, and the six [`crate::LayoutInvariants::verify`]
    /// kind ↔ code-surface predicates + four error carriers) — a score
    /// of open-coded field-accesses that expressed no compile-time link
    /// back to the typed slot. A future extension of the `:kind` axis
    /// to a richer author surface — a per-`:kind` sub-variant discriminant
    /// (e.g. `Servico(ServicoRuntime)` splitting the current single
    /// variant across the wasm-component / legacy-container / native-
    /// binary runtime axes the M5 roadmap acknowledges), a per-cluster
    /// kind-overlay the M4 CR materializer resolves per-CR (the
    /// "cluster policy demotes `Aplicacao` to `Servico` on a single-
    /// tenant cluster" arm), a promotion of the plain [`CaixaKind`]
    /// enum to a richer `KindWithRuntime` discriminated on the
    /// component-model world axis — would have had to be threaded
    /// through every open-coded copy in lockstep or the entry gate,
    /// the view composers, and the layout invariants would silently
    /// disagree on which kind a given [`Caixa`] resolves to. Lifting
    /// the resolution to a typed method on the substrate primitive
    /// means every downstream consumer of the caixa's per-`Caixa`
    /// kind surface reaches for exactly one typed dispatch — the
    /// resolver's accept-set migrates as a unit on any future axis
    /// addition.
    ///
    /// First outer top-level [`Caixa`] `Copy`-return required-enum-
    /// discriminant accessor — opens the "outer [`Caixa`] `Copy`-return
    /// required-discriminant" projection pattern. Sibling in shape to
    /// the peer per-`:supervisor` [`crate::supervisor::SupervisorSpec::estrategia`]
    /// (eafb619), per-`:placement` [`crate::aplicacao::Placement::estrategia`]
    /// (921fe1b), and per-`:children` [`crate::supervisor::ChildSpec::restart`]
    /// (dfb4a81) `Copy`-return closed-set-enum discriminant accessors
    /// on the sibling nested-spec typed-slot discriminator axes,
    /// extended here to the outer top-level [`Caixa`] universal-axis
    /// surface. Named `kind()` to match the storage field's name;
    /// the accessor's identity maps onto the canonical CAIXA-SDLC §I
    /// vocabulary the slot's docstring already carries.
    #[must_use]
    pub const fn kind(&self) -> CaixaKind {
        self.kind
    }

    /// Substrate-canonical per-`Caixa` `:autores` universal-axis
    /// maintainer-name-list slice-accessor every consumer of the top-
    /// level manifest's maintainer axis keys off — returns the author-
    /// declared `:autores` list verbatim as a `&[String]` slice-view over
    /// the same backing buffer the raw `self.autores.as_slice()` field
    /// access borrows from. Empty-list-carrying (`:autores` is a default-
    /// empty axis every `defcaixa` form supplies with an empty `()` when
    /// unset; the [`Self::from_lisp`] derive folds an omitted `:autores`
    /// through `#[serde(default)]` to `Vec::new()`, so a `Caixa` past
    /// parse definitionally carries a `Vec<String>` slot — possibly
    /// empty — and the returned `&[String]` degenerates to an empty
    /// slice on that arm without any silent `None` collapse).
    ///
    /// The `:autores` slot carries the universal-axis maintainer-name
    /// list every kind of caixa emits under (CAIXA-SDLC §I — the author-
    /// facing surface every `defcaixa` form supplies alongside `:nome` /
    /// `:versao` / `:kind`; the substrate-wide contact-carrying axis
    /// every downstream registry-facing artifact emits under) — the
    /// typed slot's `Vec<String>` accept-set (empty-per-entry rejected
    /// through [`ManifestError::AutorEmpty`], non-chart-maintainer-shape
    /// rejected through [`ManifestError::AutorInvalid`], cross-entry
    /// duplicate rejected through [`ManifestError::AutorDuplicate`]) maps
    /// onto every load-bearing downstream consumer the substrate carries
    /// — the [`Self::validate_autores`] universal-axis empty-per-entry +
    /// shape + duplicate gate at caixa-core/src/manifest.rs, the
    /// caixa-helm `build_chart_yaml` `maintainers:` fold at
    /// caixa-helm/src/lib.rs that walks each entry into a `Maintainer {
    /// name, email: None }` record, every future per-`Caixa` registry-
    /// facing renderer the CAIXA-SDLC §I roadmap acknowledges (the
    /// future `artifacthub.io/maintainers` `Chart.yaml` annotation the
    /// caixa-helm docstring alludes to at [`Self::validate_licenca`],
    /// the future per-cluster author-notification overlay the M4 CR
    /// materializer resolves per-CR).
    ///
    /// Prior to this lift the `.autores` field was accessed inline at
    /// two production sites — [`Self::validate_autores`]'s `for autor
    /// in &self.autores` walk that gates every entry through
    /// [`ManifestError::AutorEmpty`] / `AutorInvalid` / `AutorDuplicate`,
    /// and the caixa-helm `build_chart_yaml` `caixa.autores.iter().map(|a|
    /// Maintainer { name: a.clone(), email: None }).collect()` fold that
    /// materializes every entry into a `Chart.yaml` `maintainers:` row —
    /// two open-coded field-accesses that expressed no compile-time link
    /// back to the typed slot. A future extension of the `:autores` axis
    /// to a richer author surface — a per-`:autores` structured
    /// `Maintainer { name, email, url }` at the storage layer once the
    /// substrate absorbs `artifacthub.io/maintainers`' name+email+url
    /// tuple, a per-registry `:autores` allowlist the M4 CR materializer
    /// enforces per-CR (the "cluster policy demands every author declare
    /// an on-file `mailto:` contact" arm), a promotion of the plain
    /// `Vec<String>` byte-string list to a richer
    /// `Vec<ChartMaintainer>` newtype discriminated on the RFC-5322
    /// `<name> [<email>]` grammar the `is_chart_maintainer_name_shape`
    /// predicate already resolves through — would have had to be
    /// threaded through both open-coded copies in lockstep or the
    /// validate gate and the caixa-helm emit path would silently
    /// disagree on which authors a given [`Caixa`] resolves to (an
    /// author's `:autores ("alice" "bob")` would satisfy validate while
    /// the caixa-helm emit path silently rendered a drifted other
    /// maintainer list, or vice versa). Lifting the resolution to a
    /// typed method on the substrate primitive means every downstream
    /// consumer of the caixa's per-`Caixa` maintainer surface reaches
    /// for exactly one typed dispatch — the resolver's accept-set
    /// migrates as a unit on any future axis addition.
    ///
    /// First outer top-level [`Caixa`] `&[T]`-return slice-accessor —
    /// opens the "outer [`Caixa`] `&[T]` slice" projection pattern the
    /// sibling per-`Caixa` `:etiquetas` / `:deps` / `:deps-dev` / `:exe`
    /// / `:bibliotecas` / `:servicos` / `:upgrade-from` / `:children`
    /// future lifts fold on. Sibling in shape to the peer per-`:supervisor`
    /// [`crate::supervisor::SupervisorSpec::children`] (bc92bce), per-`:placement`
    /// [`crate::aplicacao::Placement::clusters`] (a6e18d7), per-`:membros`
    /// [`crate::aplicacao::AplicacaoSpec::membros`] (6c77e36), per-`:contratos`
    /// [`crate::aplicacao::AplicacaoSpec::contratos`] (0dcc926), and
    /// per-`:upgrade-from :instructions` [`crate::upgrade::UpgradeFromEntry::instructions`]
    /// (0137e5a) `&[T]`-return slice accessors on the sibling per-M2 /
    /// per-M3 typed-slot list axes, extended here to the outer top-level
    /// [`Caixa`] universal-axis surface. Returns `&[String]` (not
    /// `&Vec<String>`) because every downstream consumer of the author
    /// list treats it as a read-only sequence — the slice-view is the
    /// narrowest borrow that supports every present + roadmapped consumer
    /// (`.iter()`, `.len()`, `.is_empty()`) without leaking the backing
    /// `Vec`'s grow/push/reserve surface no consumer of the typed view
    /// reaches for (the storage-side `Vec` remains reachable through the
    /// `pub autores` field for the mutation-carrying serde round-trip and
    /// per-test fixture-mutation paths). Named `autores()` to match the
    /// storage field's name; the accessor's identity maps onto the
    /// canonical CAIXA-SDLC §I vocabulary the slot's docstring already
    /// carries.
    #[must_use]
    pub const fn autores(&self) -> &[String] {
        self.autores.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:etiquetas` universal-axis
    /// registry-search-tag-list slice-accessor every consumer of the
    /// top-level manifest's topical-tag axis keys off — returns the
    /// author-declared `:etiquetas` list verbatim as a `&[String]`
    /// slice-view over the same backing buffer the raw
    /// `self.etiquetas.as_slice()` field access borrows from. Empty-
    /// list-carrying (`:etiquetas` is a default-empty axis every
    /// `defcaixa` form supplies with an empty `()` when unset; the
    /// [`Self::from_lisp`] derive folds an omitted `:etiquetas` through
    /// `#[serde(default)]` to `Vec::new()`, so a `Caixa` past parse
    /// definitionally carries a `Vec<String>` slot — possibly empty —
    /// and the returned `&[String]` degenerates to an empty slice on
    /// that arm without any silent `None` collapse).
    ///
    /// The `:etiquetas` slot carries the universal-axis topical-tag
    /// list every kind of caixa emits under (CAIXA-SDLC §I — the
    /// author-facing surface every `defcaixa` form supplies alongside
    /// `:nome` / `:versao` / `:kind`; the substrate-wide registry-
    /// search-facing axis every downstream registry-facing artifact
    /// emits under) — the typed slot's `Vec<String>` accept-set
    /// (empty-per-entry rejected through [`ManifestError::EtiquetaEmpty`],
    /// non-chart-keyword-shape rejected through
    /// [`ManifestError::EtiquetaInvalid`], cross-entry duplicate
    /// rejected through [`ManifestError::EtiquetaDuplicate`]) maps onto
    /// every load-bearing downstream consumer the substrate carries —
    /// the [`Self::validate_etiquetas`] universal-axis empty-per-entry
    /// + shape + duplicate gate at caixa-core/src/manifest.rs, the
    /// caixa-helm `build_chart_yaml` `keywords:` fold at
    /// caixa-helm/src/lib.rs that walks each entry into the rendered
    /// `Chart.yaml` `keywords:` array (chained with the
    /// [`crate::LAREIRA_CHART_KEYWORDS`] substrate-wide floor set and
    /// dedup'd through a `BTreeSet` at emit time), every future per-
    /// `Caixa` registry-facing renderer the CAIXA-SDLC §I roadmap
    /// acknowledges (the future `artifacthub.io/keywords` `Chart.yaml`
    /// annotation, the future per-cluster tag-notification overlay the
    /// M4 CR materializer resolves per-CR).
    ///
    /// Prior to this lift the `.etiquetas` field was accessed inline at
    /// two production sites — [`Self::validate_etiquetas`]'s `for
    /// etiqueta in &self.etiquetas` walk that gates every entry through
    /// [`ManifestError::EtiquetaEmpty`] / `EtiquetaInvalid` /
    /// `EtiquetaDuplicate`, and the caixa-helm `build_chart_yaml`
    /// `caixa.etiquetas.iter().cloned().chain(...)` fold that
    /// materializes every entry into a `Chart.yaml` `keywords:` row —
    /// two open-coded field-accesses that expressed no compile-time
    /// link back to the typed slot. A future extension of the
    /// `:etiquetas` axis to a richer tag surface — a per-`:etiquetas`
    /// structured `ChartKeyword { name, uri, category }` at the storage
    /// layer once the substrate absorbs `artifacthub.io/keywords`
    /// richer tag tuple, a per-registry `:etiquetas` allowlist the M4
    /// CR materializer enforces per-CR (the "cluster policy demands
    /// every tag come from a substrate-approved taxonomy" arm), a
    /// promotion of the plain `Vec<String>` byte-string list to a
    /// richer `Vec<ChartKeyword>` newtype discriminated on the DNS-
    /// 1123-label-shaped grammar the `is_chart_keyword_shape` predicate
    /// already resolves through — would have had to be threaded through
    /// both open-coded copies in lockstep or the validate gate and the
    /// caixa-helm emit path would silently disagree on which tags a
    /// given [`Caixa`] resolves to (an author's `:etiquetas ("demo"
    /// "aplicacao")` would satisfy validate while the caixa-helm emit
    /// path silently rendered a drifted other keyword list, or vice
    /// versa). Lifting the resolution to a typed method on the
    /// substrate primitive means every downstream consumer of the
    /// caixa's per-`Caixa` topical-tag surface reaches for exactly one
    /// typed dispatch — the resolver's accept-set migrates as a unit
    /// on any future axis addition.
    ///
    /// Second outer top-level [`Caixa`] `&[T]`-return slice-accessor —
    /// folds on the "outer [`Caixa`] `&[T]` slice" projection pattern
    /// [`Self::autores`] (b5d813f) opened, sibling in shape and
    /// idiom. The remaining unlifted outer-`Caixa` slice-carrying axes
    /// (`:deps` / `:deps-dev` / `:exe` / `:bibliotecas` / `:servicos`
    /// / `:upgrade-from` / `:children` / `:membros` / `:contratos`)
    /// fold onto the same pattern in future lifts. Sibling in shape to
    /// the peer per-`:supervisor`
    /// [`crate::supervisor::SupervisorSpec::children`] (bc92bce),
    /// per-`:placement` [`crate::aplicacao::Placement::clusters`]
    /// (a6e18d7), per-`:membros`
    /// [`crate::aplicacao::AplicacaoSpec::membros`] (6c77e36),
    /// per-`:contratos` [`crate::aplicacao::AplicacaoSpec::contratos`]
    /// (0dcc926), and per-`:upgrade-from :instructions`
    /// [`crate::upgrade::UpgradeFromEntry::instructions`] (0137e5a)
    /// `&[T]`-return slice accessors on the sibling per-M2 / per-M3
    /// typed-slot list axes, extended here to the outer top-level
    /// [`Caixa`] universal-axis surface. Returns `&[String]` (not
    /// `&Vec<String>`) because every downstream consumer of the tag
    /// list treats it as a read-only sequence — the slice-view is the
    /// narrowest borrow that supports every present + roadmapped
    /// consumer (`.iter()`, `.len()`, `.is_empty()`) without leaking
    /// the backing `Vec`'s grow/push/reserve surface no consumer of
    /// the typed view reaches for (the storage-side `Vec` remains
    /// reachable through the `pub etiquetas` field for the mutation-
    /// carrying serde round-trip and per-test fixture-mutation paths).
    /// Named `etiquetas()` to match the storage field's name; the
    /// accessor's identity maps onto the canonical CAIXA-SDLC §I
    /// vocabulary the slot's docstring already carries.
    #[must_use]
    pub const fn etiquetas(&self) -> &[String] {
        self.etiquetas.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:bibliotecas` universal-axis
    /// library-source-path-list slice-accessor every consumer of the
    /// top-level manifest's Biblioteca-source axis keys off — returns
    /// the author-declared `:bibliotecas` list verbatim as a
    /// `&[String]` slice-view over the same backing buffer the raw
    /// `self.bibliotecas.as_slice()` field access borrows from. Empty-
    /// list-carrying (`:bibliotecas` is a default-empty axis every
    /// `defcaixa` form supplies with an empty `()` when unset; the
    /// [`Self::from_lisp`] derive folds an omitted `:bibliotecas`
    /// through `#[serde(default)]` to `Vec::new()`, so a `Caixa` past
    /// parse definitionally carries a `Vec<String>` slot — possibly
    /// empty — and the returned `&[String]` degenerates to an empty
    /// slice on that arm without any silent `None` collapse).
    ///
    /// The `:bibliotecas` slot carries the universal-axis lisp-library
    /// entry-path list every `:kind Biblioteca` caixa emits under
    /// (CAIXA-SDLC §I — the author-facing surface every `defcaixa`
    /// form supplies alongside `:nome` / `:versao` / `:kind`; the
    /// substrate-wide library-carrier axis every downstream
    /// authoring-facing consumer keys off) — the typed slot's
    /// `Vec<String>` accept-set (empty-per-entry rejected through
    /// [`ManifestError::CodePathEmpty { slot: ":bibliotecas" }`],
    /// non-sandboxed-relative-shape rejected through
    /// [`ManifestError::CodePathShape`], non-`.lisp`-extension rejected
    /// through [`ManifestError::CodePathNonLispExtension`], cross-entry
    /// duplicate rejected through [`ManifestError::CodePathDuplicate`])
    /// maps onto every load-bearing downstream consumer the substrate
    /// carries — the [`crate::LayoutInvariants`] Biblioteca-arm
    /// empty-check + per-entry file-exists loop at
    /// caixa-core/src/layout.rs that gates each entry through
    /// [`crate::LayoutError::MissingLib`] / `MissingEntry`, the
    /// [`Self::validate_code_paths`] per-slot shape gate at
    /// caixa-core/src/manifest.rs that walks each entry through the
    /// sandbox-relative / `.lisp`-extension / cross-entry duplicate
    /// gates, the `feira build` per-entry `tatara_lisp::read` parse
    /// walk at caixa-feira/src/cmd/build.rs that phase-1-checks each
    /// declared library file for lexical / structural errors before
    /// downstream `importar` resolution, every future per-`Caixa`
    /// library-facing renderer the CAIXA-SDLC §I roadmap acknowledges
    /// (the future `tatara-lispc` compilation entry the docstring at
    /// caixa-feira/src/cmd/build.rs alludes to, the future per-cluster
    /// bytecode-caching overlay the M4 CR materializer resolves per-CR,
    /// the future `caixa-lsp` per-library semantic-token stream the
    /// caixa-lsp docstring roadmaps).
    ///
    /// Prior to this lift the `.bibliotecas` field was accessed inline
    /// at three production sites — [`crate::LayoutInvariants`]'s
    /// `caixa.bibliotecas.is_empty()` `MissingLib`-arm gate + `for p
    /// in &caixa.bibliotecas` `MissingEntry` walk that gates each
    /// declared library path through the on-disk-existence check,
    /// the compound-code-path `has_code = !caixa.bibliotecas.is_empty()
    /// || !caixa.exe.is_empty() || !caixa.servicos.is_empty()` OR-fold
    /// on the [`crate::LayoutError::SupervisorOwnsCode`] /
    /// `AplicacaoOwnsCode` kind-coherence gate, and the `feira build`
    /// per-entry `for entry in &caixa.bibliotecas` + `caixa.bibliotecas.
    /// len()` phase-1 tatara-lispc-precursor parse walk — three open-
    /// coded field-accesses that expressed no compile-time link back
    /// to the typed slot. A future extension of the `:bibliotecas`
    /// axis to a richer library surface — a per-`:bibliotecas`
    /// structured `BibliotecaEntry { path, edition, exports }` at the
    /// storage layer once the substrate absorbs the per-library
    /// language-edition + explicit-exports tuple the tatara-lisp
    /// module-system roadmap acknowledges, a per-registry
    /// `:bibliotecas` allowlist the M4 CR materializer enforces
    /// per-CR (the "cluster policy demands every biblioteca declare
    /// its own :edicao" arm), a promotion of the plain `Vec<String>`
    /// byte-string list to a richer `Vec<LibraryPath>` newtype
    /// discriminated on the `lib/<nome>.lisp`-shape grammar the
    /// [`crate::render::is_sandboxed_relative_path`] +
    /// [`crate::render::is_lisp_extension`] predicates already resolve
    /// through — would have had to be threaded through all three
    /// open-coded copies in lockstep or the layout gate, the shape
    /// validator, and the `feira build` phase-1 parse walk would
    /// silently disagree on which library paths a given [`Caixa`]
    /// resolves to (an author's `:bibliotecas ("lib/foo.lisp"
    /// "lib/bar.lisp")` would satisfy layout while `feira build`
    /// silently parsed a drifted other list, or vice versa). Lifting
    /// the resolution to a typed method on the substrate primitive
    /// means every downstream consumer of the caixa's per-`Caixa`
    /// library-source surface reaches for exactly one typed dispatch
    /// — the resolver's accept-set migrates as a unit on any future
    /// axis addition.
    ///
    /// Third outer top-level [`Caixa`] `&[T]`-return slice-accessor —
    /// folds on the "outer [`Caixa`] `&[T]` slice" projection pattern
    /// [`Self::autores`] (b5d813f) opened and [`Self::etiquetas`]
    /// (78c7d3c) folded on, sibling in shape and idiom. The remaining
    /// unlifted outer-`Caixa` slice-carrying axes (`:deps` /
    /// `:deps-dev` / `:exe` / `:servicos` / `:upgrade-from` /
    /// `:children` / `:membros` / `:contratos`) fold onto the same
    /// pattern in future lifts. Sibling in shape to the peer
    /// per-`:supervisor`
    /// [`crate::supervisor::SupervisorSpec::children`] (bc92bce),
    /// per-`:placement` [`crate::aplicacao::Placement::clusters`]
    /// (a6e18d7), per-`:membros`
    /// [`crate::aplicacao::AplicacaoSpec::membros`] (6c77e36),
    /// per-`:contratos` [`crate::aplicacao::AplicacaoSpec::contratos`]
    /// (0dcc926), and per-`:upgrade-from :instructions`
    /// [`crate::upgrade::UpgradeFromEntry::instructions`] (0137e5a)
    /// `&[T]`-return slice accessors on the sibling per-M2 / per-M3
    /// typed-slot list axes, extended here to the outer top-level
    /// [`Caixa`] universal-axis surface. Returns `&[String]` (not
    /// `&Vec<String>`) because every downstream consumer of the
    /// library-source list treats it as a read-only sequence — the
    /// slice-view is the narrowest borrow that supports every
    /// present + roadmapped consumer (`.iter()`, `.len()`,
    /// `.is_empty()`) without leaking the backing `Vec`'s
    /// grow/push/reserve surface no consumer of the typed view
    /// reaches for (the storage-side `Vec` remains reachable through
    /// the `pub bibliotecas` field for the mutation-carrying serde
    /// round-trip and per-test fixture-mutation paths). Named
    /// `bibliotecas()` to match the storage field's name; the
    /// accessor's identity maps onto the canonical CAIXA-SDLC §I
    /// vocabulary the slot's docstring already carries.
    #[must_use]
    pub const fn bibliotecas(&self) -> &[String] {
        self.bibliotecas.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:exe` universal-axis
    /// nix-built-executable-entry-path-list slice-accessor every consumer
    /// of the top-level manifest's Binario-executable axis keys off —
    /// returns the author-declared `:exe` list verbatim as a `&[String]`
    /// slice-view over the same backing buffer the raw
    /// `self.exe.as_slice()` field access borrows from. Empty-list-
    /// carrying (`:exe` is a default-empty axis every `defcaixa` form
    /// supplies with an empty `()` when unset; the [`Self::from_lisp`]
    /// derive folds an omitted `:exe` through `#[serde(default)]` to
    /// `Vec::new()`, so a `Caixa` past parse definitionally carries a
    /// `Vec<String>` slot — possibly empty — and the returned `&[String]`
    /// degenerates to an empty slice on that arm without any silent
    /// `None` collapse).
    ///
    /// The `:exe` slot carries the universal-axis nix-built executable
    /// entry-path list every `:kind Binario` caixa emits under
    /// (CAIXA-SDLC §I — the author-facing surface every `defcaixa`
    /// form supplies alongside `:nome` / `:versao` / `:kind`; the
    /// substrate-wide `exe/`-directory-fenced entry-carrier axis every
    /// downstream flake-build-facing consumer keys off) — the typed
    /// slot's `Vec<String>` accept-set (empty-per-entry rejected
    /// through [`ManifestError::CodePathEmpty { slot: ":exe" }`],
    /// non-sandboxed-relative-shape rejected through
    /// [`ManifestError::CodePathShape`], cross-entry duplicate rejected
    /// through [`ManifestError::CodePathDuplicate`], out-of-`exe/`-
    /// directory paths rejected past the layout's
    /// [`crate::LayoutError::ExeOutsideDir`] `starts_with` fence) maps
    /// onto every load-bearing downstream consumer the substrate carries
    /// — the [`crate::LayoutInvariants`] Binario-arm empty-check +
    /// per-entry file-exists + `exe/`-directory-fence loop at
    /// caixa-core/src/layout.rs that gates each entry through
    /// [`crate::LayoutError::BinarioWithoutExe`] / `MissingEntry` /
    /// `ExeOutsideDir`, the compound `has_code` OR-fold on the
    /// [`crate::LayoutError::SupervisorOwnsCode`] /
    /// [`crate::LayoutError::AplicacaoOwnsCode`] kind-coherence gate
    /// that fences code-surface slots off from the two no-code kinds,
    /// [`Self::declared_foreign_code_slots`]'s `!self.exe.is_empty()`
    /// arm on the [`crate::LayoutError::ForeignCodeSlot`] gate that
    /// fences the `:exe` code surface off from every non-Binario code-
    /// running kind, [`Self::validate_code_paths`]'s per-slot shape gate
    /// that walks each entry through the sandbox-relative / cross-entry
    /// duplicate gates, every future per-`Caixa` executable-facing
    /// renderer the CAIXA-SDLC §I roadmap acknowledges (the future
    /// `caixa-flake` per-Binario `packages.<system>.<nome>` derivation
    /// entry the caixa-flake docstring roadmaps, the future per-cluster
    /// `nix-store` overlay the M4 CR materializer resolves per-CR, the
    /// future `feira nix` per-executable Binario-target emit path).
    ///
    /// Prior to this lift the `.exe` field was accessed inline at three
    /// production sites — the compound-code-path `has_code =
    /// !caixa.bibliotecas().is_empty() || !caixa.exe.is_empty() ||
    /// !caixa.servicos.is_empty()` OR-fold on the
    /// [`crate::LayoutError::SupervisorOwnsCode`] /
    /// `AplicacaoOwnsCode` kind-coherence gate, the Binario-arm
    /// `caixa.exe.is_empty()` [`crate::LayoutError::BinarioWithoutExe`]
    /// gate, the per-entry `for p in &caixa.exe`
    /// `MissingEntry`/`ExeOutsideDir` walk, and the
    /// [`Self::declared_foreign_code_slots`]'s
    /// `!self.exe.is_empty()` arm on the `ForeignCodeSlot` gate — four
    /// open-coded field-accesses that expressed no compile-time link
    /// back to the typed slot. A future extension of the `:exe` axis
    /// to a richer executable surface — a per-`:exe` structured
    /// `BinarioEntry { path, wrapper, capabilities }` at the storage
    /// layer once the substrate absorbs the per-executable
    /// nix-wrapper + linux-capabilities tuple the CAIXA-SDLC §I
    /// executable roadmap acknowledges, a per-registry `:exe` allowlist
    /// the M4 CR materializer enforces per-CR (the "cluster policy
    /// demands every Binario declare an explicit `:wrapper`" arm), a
    /// promotion of the plain `Vec<String>` byte-string list to a
    /// richer `Vec<ExecutablePath>` newtype discriminated on the
    /// `exe/<nome>`-shape grammar the layout's `starts_with(exe_dir)`
    /// fence already resolves through — would have had to be threaded
    /// through all four open-coded copies in lockstep or the layout
    /// gate, the shape validator, and the `feira nix` emit path would
    /// silently disagree on which executable paths a given [`Caixa`]
    /// resolves to (an author's `:exe ("exe/cli" "exe/serve")` would
    /// satisfy layout while `feira nix` silently packaged a drifted
    /// other list, or vice versa). Lifting the resolution to a typed
    /// method on the substrate primitive means every downstream
    /// consumer of the caixa's per-`Caixa` executable-source surface
    /// reaches for exactly one typed dispatch — the resolver's accept-
    /// set migrates as a unit on any future axis addition.
    ///
    /// Fourth outer top-level [`Caixa`] `&[T]`-return slice-accessor —
    /// folds on the "outer [`Caixa`] `&[T]` slice" projection pattern
    /// [`Self::autores`] (b5d813f) opened, [`Self::etiquetas`]
    /// (78c7d3c) folded on, and [`Self::bibliotecas`] (8a36c23) closed
    /// the universal-axis text-tag family of. Opens the outer-`Caixa`
    /// foreign-code-slot `&[T]` sub-family the sibling `:servicos`
    /// future lift closes onto (per the trio of code-surface list slots
    /// the [`Self::validate_code_paths`] per-slot dispatch tuple
    /// already carries — `:bibliotecas` + `:exe` + `:servicos`, of which
    /// `:bibliotecas` landed at 8a36c23 and `:servicos` remains as the
    /// last unlifted code-surface slot). Sibling in shape to the peer
    /// per-`:supervisor` [`crate::supervisor::SupervisorSpec::children`]
    /// (bc92bce), per-`:placement`
    /// [`crate::aplicacao::Placement::clusters`] (a6e18d7),
    /// per-`:membros` [`crate::aplicacao::AplicacaoSpec::membros`]
    /// (6c77e36), per-`:contratos`
    /// [`crate::aplicacao::AplicacaoSpec::contratos`] (0dcc926), and
    /// per-`:upgrade-from :instructions`
    /// [`crate::upgrade::UpgradeFromEntry::instructions`] (0137e5a)
    /// `&[T]`-return slice accessors on the sibling per-M2 / per-M3
    /// typed-slot list axes, extended here to the outer top-level
    /// [`Caixa`] universal-axis surface. Returns `&[String]` (not
    /// `&Vec<String>`) because every downstream consumer of the
    /// executable-source list treats it as a read-only sequence — the
    /// slice-view is the narrowest borrow that supports every
    /// present + roadmapped consumer (`.iter()`, `.len()`,
    /// `.is_empty()`) without leaking the backing `Vec`'s
    /// grow/push/reserve surface no consumer of the typed view
    /// reaches for (the storage-side `Vec` remains reachable through
    /// the `pub exe` field for the mutation-carrying serde
    /// round-trip and per-test fixture-mutation paths). Named `exe()`
    /// to match the storage field's name; the accessor's identity
    /// maps onto the canonical CAIXA-SDLC §I vocabulary the slot's
    /// docstring already carries.
    #[must_use]
    pub const fn exe(&self) -> &[String] {
        self.exe.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:servicos` universal-axis
    /// ComputeUnit-CR-YAML-entry-path-list slice-accessor every consumer
    /// of the top-level manifest's Servico-component axis keys off —
    /// returns the author-declared `:servicos` list verbatim as a
    /// `&[String]` slice-view over the same backing buffer the raw
    /// `self.servicos.as_slice()` field access borrows from. Empty-list-
    /// carrying (`:servicos` is a default-empty axis every `defcaixa`
    /// form supplies with an empty `()` when unset; the
    /// [`Self::from_lisp`] derive folds an omitted `:servicos` through
    /// `#[serde(default)]` to `Vec::new()`, so a `Caixa` past parse
    /// definitionally carries a `Vec<String>` slot — possibly empty —
    /// and the returned `&[String]` degenerates to an empty slice on
    /// that arm without any silent `None` collapse).
    ///
    /// The `:servicos` slot carries the universal-axis
    /// `.computeunit.yaml` ComputeUnit-CR entry-path list every
    /// `:kind Servico` caixa emits under (CAIXA-SDLC §I — the
    /// author-facing surface every `defcaixa` form supplies alongside
    /// `:nome` / `:versao` / `:kind`; the substrate-wide
    /// `servicos/`-directory-fenced entry-carrier axis every downstream
    /// Servico-facing renderer keys off) — the typed slot's
    /// `Vec<String>` accept-set (empty-per-entry rejected through
    /// [`ManifestError::CodePathEmpty { slot: ":servicos" }`],
    /// non-sandboxed-relative-shape rejected through
    /// [`ManifestError::CodePathShape`], non-`.computeunit.yaml`
    /// extension rejected through
    /// [`ManifestError::CodePathNonComputeUnitYamlExtension`], cross-
    /// entry duplicate rejected through
    /// [`ManifestError::CodePathDuplicate`], `len != 1` rejected by the
    /// V0 [`crate::ServicoCountMismatch`] gate on the per-Servico
    /// renderer entry-points, out-of-`servicos/`-directory paths
    /// rejected past the layout's [`crate::LayoutError::ServicoOutsideDir`]
    /// `starts_with` fence) maps onto every load-bearing downstream
    /// consumer the substrate carries — the [`crate::LayoutInvariants`]
    /// Servico-arm empty-check + per-entry file-exists + `servicos/`-
    /// directory-fence loop at caixa-core/src/layout.rs that gates each
    /// entry through [`crate::LayoutError::ServicoWithoutServicos`] /
    /// `MissingEntry` / `ServicoOutsideDir`, the compound `has_code`
    /// OR-fold on the [`crate::LayoutError::SupervisorOwnsCode`] /
    /// [`crate::LayoutError::AplicacaoOwnsCode`] kind-coherence gate
    /// that fences code-surface slots off from the two no-code kinds,
    /// [`Self::declared_foreign_code_slots`]'s
    /// `!self.servicos.is_empty()` arm on the
    /// [`crate::LayoutError::ForeignCodeSlot`] gate that fences the
    /// `:servicos` code surface off from every non-Servico code-running
    /// kind, [`Self::validate_code_paths`]'s per-slot shape gate that
    /// walks each entry through the sandbox-relative / `.computeunit.
    /// yaml`-extension / cross-entry duplicate gates, the
    /// [`crate::require_single_servico`] V0 singularity gate every
    /// per-Servico renderer entry-point runs through
    /// [`crate::require_v0_servico_shape`], the `feira chart` /
    /// `feira deploy` per-verb `first_servico_path` walk at
    /// caixa-feira/src/cmd/chart.rs that resolves the singleton
    /// ComputeUnit-CR file, every future per-`Caixa` Servico-facing
    /// renderer the CAIXA-SDLC §I roadmap acknowledges (the future
    /// per-Servico OCI packager, the future M4
    /// `wasm.pleme.io/v1alpha1/ComputeUnit` CR materializer, the future
    /// per-Servico OTel collector-config emit).
    ///
    /// Prior to this lift the `.servicos` field was accessed inline at
    /// five production sites — the compound-code-path `has_code =
    /// !caixa.bibliotecas().is_empty() || !caixa.exe().is_empty() ||
    /// !caixa.servicos.is_empty()` OR-fold on the
    /// [`crate::LayoutError::SupervisorOwnsCode`] /
    /// `AplicacaoOwnsCode` kind-coherence gate, the Servico-arm
    /// `caixa.servicos.is_empty()`
    /// [`crate::LayoutError::ServicoWithoutServicos`] gate, the
    /// per-entry `for p in &caixa.servicos`
    /// `MissingEntry`/`ServicoOutsideDir` walk, the
    /// [`Self::declared_foreign_code_slots`]'s
    /// `!self.servicos.is_empty()` arm on the `ForeignCodeSlot` gate,
    /// and the [`crate::require_single_servico`] V0 count gate's
    /// `caixa.servicos.len() == 1` / `caixa.servicos.len()` count
    /// projection (both the accept-arm predicate and the
    /// diagnostic-carrying `ServicoCountMismatch { count }`
    /// projection) — five open-coded field-accesses across three
    /// crates that expressed no compile-time link back to the typed
    /// slot. A future extension of the `:servicos` axis to a richer
    /// component surface — a per-`:servicos` structured
    /// `ServicoEntry { path, world, capabilities }` at the storage
    /// layer once the substrate absorbs the per-component WIT-world +
    /// capability-set tuple the CAIXA-SDLC §I Servico roadmap
    /// acknowledges, a per-registry `:servicos` allowlist the M4 CR
    /// materializer enforces per-CR (the "cluster policy demands every
    /// Servico declare an explicit `:world`" arm), a promotion of the
    /// plain `Vec<String>` byte-string list to a richer
    /// `Vec<ComputeUnitPath>` newtype discriminated on the
    /// `servicos/<nome>.computeunit.yaml`-shape grammar the layout's
    /// `starts_with(servicos_dir)` fence and the
    /// [`crate::render::is_computeunit_yaml_extension`] predicate
    /// already resolve through, a promotion of the V0 singleton
    /// contract to a multi-component `Vec<ComputeUnitPath>` past the M5
    /// component-model multi-world boundary — would have had to be
    /// threaded through all five open-coded copies in lockstep or the
    /// layout gate, the shape validator, the V0 count gate, and the
    /// `feira chart` / `feira deploy` entry-point walks would silently
    /// disagree on which ComputeUnit-CR paths a given [`Caixa`]
    /// resolves to (an author's `:servicos ("servicos/foo.computeunit.
    /// yaml")` would satisfy layout while `feira chart` silently
    /// packaged a drifted other list, or vice versa). Lifting the
    /// resolution to a typed method on the substrate primitive means
    /// every downstream consumer of the caixa's per-`Caixa`
    /// ComputeUnit-CR-source surface reaches for exactly one typed
    /// dispatch — the resolver's accept-set migrates as a unit on any
    /// future axis addition.
    ///
    /// Fifth and final outer top-level [`Caixa`] `&[T]`-return slice-
    /// accessor — folds on the "outer [`Caixa`] `&[T]` slice"
    /// projection pattern [`Self::autores`] (b5d813f) opened,
    /// [`Self::etiquetas`] (78c7d3c) folded on, [`Self::bibliotecas`]
    /// (8a36c23) closed the universal-axis text-tag family of, and
    /// [`Self::exe`] (65d9527) opened the foreign-code-slot sub-family
    /// of. Closes the outer-`Caixa` foreign-code-slot `&[T]` sub-family
    /// — with `:bibliotecas`, `:exe`, and `:servicos` now each carrying
    /// a substrate-canonical slice accessor, the trio of code-surface
    /// list slots the [`Self::validate_code_paths`] per-slot dispatch
    /// tuple carries is complete on the typed dispatch surface (the
    /// internal `[(":bibliotecas", &self.bibliotecas, ..), (":exe",
    /// &self.exe, ..), (":servicos", &self.servicos, ..)]` per-slot
    /// dispatch tuple's homogeneous `&Vec<String>`-typed shape blocks a
    /// per-element accessor swap in isolation — a future companion lift
    /// promotes the tuple's element type to `&[String]` and threads the
    /// triple of typed dispatches through as a unit). Sibling in shape
    /// to the peer per-`:supervisor`
    /// [`crate::supervisor::SupervisorSpec::children`] (bc92bce),
    /// per-`:placement` [`crate::aplicacao::Placement::clusters`]
    /// (a6e18d7), per-`:membros`
    /// [`crate::aplicacao::AplicacaoSpec::membros`] (6c77e36),
    /// per-`:contratos`
    /// [`crate::aplicacao::AplicacaoSpec::contratos`] (0dcc926), and
    /// per-`:upgrade-from :instructions`
    /// [`crate::upgrade::UpgradeFromEntry::instructions`] (0137e5a)
    /// `&[T]`-return slice accessors on the sibling per-M2 / per-M3
    /// typed-slot list axes, extended here to the outer top-level
    /// [`Caixa`] universal-axis surface. Returns `&[String]` (not
    /// `&Vec<String>`) because every downstream consumer of the
    /// ComputeUnit-CR-source list treats it as a read-only sequence —
    /// the slice-view is the narrowest borrow that supports every
    /// present + roadmapped consumer (`.iter()`, `.len()`,
    /// `.is_empty()`, `.first()`) without leaking the backing `Vec`'s
    /// grow/push/reserve surface no consumer of the typed view reaches
    /// for (the storage-side `Vec` remains reachable through the
    /// `pub servicos` field for the mutation-carrying serde round-trip
    /// and per-test fixture-mutation paths, and for the
    /// [`Self::validate_code_paths`] per-slot dispatch tuple whose
    /// homogeneous-element-type shape carries the raw field access
    /// until the trio-closure lift promotes the tuple as a unit).
    /// Named `servicos()` to match the storage field's name; the
    /// accessor's identity maps onto the canonical CAIXA-SDLC §I
    /// vocabulary the slot's docstring already carries.
    #[must_use]
    pub const fn servicos(&self) -> &[String] {
        self.servicos.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:deps` universal-axis
    /// runtime-dependency-declaration-list slice-accessor every consumer
    /// of the top-level manifest's runtime-dep-graph axis keys off —
    /// returns the author-declared `:deps` list verbatim as a `&[Dep]`
    /// slice-view over the same backing buffer the raw
    /// `self.deps.as_slice()` field access borrows from. Empty-list-
    /// carrying (`:deps` is a default-empty axis every `defcaixa` form
    /// supplies with an empty `()` when unset; the [`Self::from_lisp`]
    /// derive folds an omitted `:deps` through `#[serde(default)]` to
    /// `Vec::new()`, so a `Caixa` past parse definitionally carries a
    /// `Vec<Dep>` slot — possibly empty — and the returned `&[Dep]`
    /// degenerates to an empty slice on that arm without any silent
    /// `None` collapse).
    ///
    /// The `:deps` slot carries the universal-axis runtime dependency
    /// list every kind of caixa emits under (CAIXA-SDLC §I — the author-
    /// facing surface every `defcaixa` form supplies alongside `:nome` /
    /// `:versao` / `:kind`; the substrate-wide runtime-closure-input axis
    /// every downstream resolver-facing artifact emits under) — the
    /// typed slot's `Vec<Dep>` accept-set (empty-`:nome` rejected through
    /// [`DepError::NomeEmpty`], non-DNS-1123-label `:nome` rejected
    /// through [`DepError::NomeInvalid`], malformed `:versao` rejected
    /// through [`DepError::VersaoInvalid`], empty `:fonte.repo` rejected
    /// through [`DepError::FonteRepoEmpty`], within-list duplicate `:nome`
    /// rejected through [`DepError::DuplicateNome { list: ":deps" }`])
    /// maps onto every load-bearing downstream consumer the substrate
    /// carries — the [`Self::validate_deps`] per-entry
    /// [`Dep::validate`] + within-list dedup walk at
    /// caixa-core/src/manifest.rs, the [`crate::dep::validate_no_self_dep`]
    /// cross-list self-reference gate at caixa-core/src/layout.rs that
    /// checks each entry against the caixa's own `:nome`, the
    /// caixa-resolver `for dep in &root.deps` closure walk at
    /// caixa-resolver/src/resolve.rs that seeds every git-clone target
    /// through the resolver's [`crate::Dep`]-keyed pipeline, the
    /// caixa-crd `caixa.deps.iter().map(dep_into_ref).collect()` fold at
    /// caixa-crd/src/conversion.rs that materializes each entry into the
    /// K8s `Caixa` CR's `spec.deps` field, every future per-`Caixa`
    /// resolver-facing renderer the CAIXA-SDLC §I roadmap acknowledges
    /// (the future per-cluster runtime-closure-audit overlay the M4 CR
    /// materializer resolves per-CR, the future `lacre.lisp` BLAKE3-
    /// closure emit walk the caixa-resolver docstring roadmaps).
    ///
    /// First outer top-level [`Caixa`] `&[Dep]`-return slice-accessor —
    /// opens the outer-`Caixa` dependency-slot `&[Dep]` sub-family the
    /// sibling `:deps-dev` future lift closes on. Peer of the closed
    /// outer-`Caixa` foreign-code-slot `&[String]` sub-family
    /// ([`Self::bibliotecas`] 8a36c23, [`Self::exe`] 65d9527,
    /// [`Self::servicos`] 611f78b) and the outer-`Caixa` universal-axis
    /// text-tag family ([`Self::autores`] b5d813f, [`Self::etiquetas`]
    /// 78c7d3c) — extends the "outer [`Caixa`] `&[T]` slice" projection
    /// pattern onto a novel element-type axis (`Dep` composite vs the
    /// prior sibling family's `String` scalar). Sibling in shape to the
    /// peer per-`:supervisor`
    /// [`crate::supervisor::SupervisorSpec::children`] (bc92bce),
    /// per-`:placement` [`crate::aplicacao::Placement::clusters`]
    /// (a6e18d7), per-`:membros`
    /// [`crate::aplicacao::AplicacaoSpec::membros`] (6c77e36),
    /// per-`:contratos` [`crate::aplicacao::AplicacaoSpec::contratos`]
    /// (0dcc926), and per-`:upgrade-from :instructions`
    /// [`crate::upgrade::UpgradeFromEntry::instructions`] (0137e5a)
    /// `&[T]`-return slice accessors on the sibling per-M2 / per-M3
    /// typed-slot list axes, extended here to the outer top-level
    /// [`Caixa`] universal-axis dep-graph surface. Returns `&[Dep]`
    /// (not `&Vec<Dep>`) because every downstream consumer of the
    /// runtime-dep list treats it as a read-only sequence — the slice-
    /// view is the narrowest borrow that supports every present +
    /// roadmapped consumer (`.iter()`, `.len()`, `.is_empty()`) without
    /// leaking the backing `Vec`'s grow/push/reserve surface no consumer
    /// of the typed view reaches for (the storage-side `Vec` remains
    /// reachable through the `pub deps` field for the mutation-carrying
    /// serde round-trip and per-test fixture-mutation paths). Named
    /// `deps()` to match the storage field's name; the accessor's
    /// identity maps onto the canonical CAIXA-SDLC §I vocabulary the
    /// slot's docstring already carries.
    #[must_use]
    pub const fn deps(&self) -> &[Dep] {
        self.deps.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:deps-dev` universal-axis
    /// development-only-dependency-declaration-list slice-accessor every
    /// consumer of the top-level manifest's dev-dep-graph axis keys off —
    /// returns the author-declared `:deps-dev` list verbatim as a `&[Dep]`
    /// slice-view over the same backing buffer the raw
    /// `self.deps_dev.as_slice()` field access borrows from. Empty-list-
    /// carrying (`:deps-dev` is a default-empty axis every `defcaixa`
    /// form supplies with an empty `()` when unset; the
    /// [`Self::from_lisp`] derive folds an omitted `:deps-dev` through
    /// `#[serde(default)]` to `Vec::new()`, so a `Caixa` past parse
    /// definitionally carries a `Vec<Dep>` slot — possibly empty — and
    /// the returned `&[Dep]` degenerates to an empty slice on that arm
    /// without any silent `None` collapse).
    ///
    /// The `:deps-dev` slot carries the universal-axis dev-only
    /// dependency list every kind of caixa emits under (CAIXA-SDLC §I —
    /// the author-facing sibling of `:deps` that every `defcaixa` form
    /// supplies to declare tests / lint / bench closures the runtime
    /// `:deps` axis does not carry; the substrate-wide dev-closure-input
    /// axis every downstream test-facing artifact emits under, matching
    /// Cargo's `[dev-dependencies]` table's dev-time-only visibility
    /// contract) — the typed slot's `Vec<Dep>` accept-set (empty-`:nome`
    /// rejected through [`DepError::NomeEmpty`], non-DNS-1123-label
    /// `:nome` rejected through [`DepError::NomeInvalid`], malformed
    /// `:versao` rejected through [`DepError::VersaoInvalid`], empty
    /// `:fonte.repo` rejected through [`DepError::FonteRepoEmpty`],
    /// within-list duplicate `:nome` rejected through
    /// [`DepError::DuplicateNome { list: ":deps-dev" }`]) maps onto every
    /// load-bearing downstream consumer the substrate carries — the
    /// [`Self::validate_deps`] per-entry [`Dep::validate`] + within-list
    /// dedup walk at caixa-core/src/manifest.rs, the
    /// [`crate::dep::validate_no_self_dep`] cross-list self-reference
    /// gate at caixa-core/src/layout.rs that checks each entry against
    /// the caixa's own `:nome`, the caixa-resolver
    /// `for dep in &root.deps_dev` closure walk at
    /// caixa-resolver/src/resolve.rs that seeds every dev-only git-clone
    /// target through the resolver's [`crate::Dep`]-keyed pipeline, and
    /// every future per-`Caixa` resolver-facing renderer the CAIXA-SDLC
    /// §I roadmap acknowledges (the future per-cluster dev-closure-audit
    /// overlay the M4 CR materializer resolves per-CR, the future
    /// `lacre.lisp` BLAKE3-closure emit walk the caixa-resolver docstring
    /// roadmaps).
    ///
    /// Second outer top-level [`Caixa`] `&[Dep]`-return slice-accessor —
    /// closes the outer-`Caixa` dependency-slot `&[Dep]` sub-family the
    /// sibling [`Self::deps`] (ad34b4e) opened on. The two accessors
    /// jointly close the two-list dep-graph surface every downstream
    /// resolver-facing consumer keys off (runtime `:deps` +
    /// dev-only `:deps-dev`, the canonical Cargo-shaped dependency-table
    /// pair the [`Self::validate_deps`] gate already walks in canonical
    /// order). Peer of the closed outer-`Caixa` foreign-code-slot
    /// `&[String]` sub-family ([`Self::bibliotecas`] 8a36c23,
    /// [`Self::exe`] 65d9527, [`Self::servicos`] 611f78b) and the outer-
    /// `Caixa` universal-axis text-tag family ([`Self::autores`]
    /// b5d813f, [`Self::etiquetas`] 78c7d3c) — folds the "outer
    /// [`Caixa`] `&[T]` slice" projection pattern onto the sibling
    /// dev-dep composite-element axis (`Dep` composite, matching the
    /// [`Self::deps`] element type). Sibling in shape to the peer
    /// per-`:supervisor` [`crate::supervisor::SupervisorSpec::children`]
    /// (bc92bce), per-`:placement`
    /// [`crate::aplicacao::Placement::clusters`] (a6e18d7),
    /// per-`:membros` [`crate::aplicacao::AplicacaoSpec::membros`]
    /// (6c77e36), per-`:contratos`
    /// [`crate::aplicacao::AplicacaoSpec::contratos`] (0dcc926), and
    /// per-`:upgrade-from :instructions`
    /// [`crate::upgrade::UpgradeFromEntry::instructions`] (0137e5a)
    /// `&[T]`-return slice accessors on the sibling per-M2 / per-M3
    /// typed-slot list axes, folded here to the outer top-level
    /// [`Caixa`] universal-axis dev-dep-graph surface. Returns `&[Dep]`
    /// (not `&Vec<Dep>`) because every downstream consumer of the
    /// dev-dep list treats it as a read-only sequence — the slice-view
    /// is the narrowest borrow that supports every present +
    /// roadmapped consumer (`.iter()`, `.len()`, `.is_empty()`) without
    /// leaking the backing `Vec`'s grow/push/reserve surface no consumer
    /// of the typed view reaches for (the storage-side `Vec` remains
    /// reachable through the `pub deps_dev` field for the mutation-
    /// carrying serde round-trip and per-test fixture-mutation paths).
    /// Named `deps_dev()` to match the storage field's `snake_case` name;
    /// the kebab-case author-surface tag `:deps-dev` is the same axis
    /// after tatara-lisp's kebab↔snake fold and the accessor's identity
    /// maps onto the canonical CAIXA-SDLC §I vocabulary the slot's
    /// docstring already carries.
    #[must_use]
    pub const fn deps_dev(&self) -> &[Dep] {
        self.deps_dev.as_slice()
    }

    /// Substrate-canonical per-[`Caixa`] typed-dispatch read accessor
    /// every consumer that walks one of the two dep-list axes keyed on a
    /// [`crate::dep::DepList`] discriminant reaches for — routes the
    /// `(list: DepList) -> &[Dep]` projection through one typed method on
    /// the substrate primitive rather than the prior open-coded
    /// `match list { Prod => caixa.deps(), Dev => caixa.deps_dev() }`
    /// inline dispatch every per-axis walker would otherwise carry.
    /// Returns the author-declared per-list `Vec<Dep>` verbatim as a
    /// `&[Dep]` slice-view over the same backing buffer the sibling
    /// [`Self::deps`] (`Prod`) / [`Self::deps_dev`] (`Dev`) per-slot
    /// accessors borrow from, preserving the empty-list-carrying invariant
    /// each per-slot accessor already establishes (`:deps` / `:deps-dev`
    /// are default-empty axes every `defcaixa` form supplies with an empty
    /// `()` when unset; the [`Self::from_lisp`] derive folds an omitted
    /// list through `#[serde(default)]` to `Vec::new()`, so both arms
    /// definitionally carry a `Vec<Dep>` slot — possibly empty — and the
    /// returned `&[Dep]` degenerates to an empty slice on either arm
    /// without any silent `None` collapse).
    ///
    /// The [`crate::dep::DepList`] closed-set typed enum is the
    /// substrate's canonical discriminator for the "runtime-closure
    /// `:deps` vs dev-only-closure `:deps-dev`" axis every dep-list
    /// consumer dispatches on — the compiler-checked exhaustiveness on
    /// the enum's `match` arms is the build-time guarantee that no future
    /// per-list read-site regresses to a bare-`bool`-flag inline dispatch
    /// that a future third dep-list axis (a `:deps-build` build-only
    /// closure once the substrate grows cross-artifact heterogeneous
    /// dep-graphs, per CAIXA-SDLC §I) would silently split at every
    /// consumer. Prior to this the read side carried two per-slot
    /// accessors ([`Self::deps`] ad34b4e, [`Self::deps_dev`]) and no
    /// typed dispatch that a per-axis walker could parametrise on, so
    /// every per-list walker (the [`Self::validate_deps`] per-list
    /// [`crate::render::insert_first_seen`] dedup walk, a future
    /// `feira app graph` per-list dep summary, a future M4 per-cluster
    /// dev-closure-audit overlay the CR materializer resolves per-CR)
    /// open-coded the same two-block "run over `:deps`, then run over
    /// `:deps-dev`" pattern — a silent duplication that a future third
    /// dep-list axis would have had to grow a third block at every site.
    ///
    /// Peer of the sibling [`Self::push_dep`] typed-mutation dispatch
    /// (359fba5) — closes the two-side dispatch symmetry on the outer
    /// [`Caixa`] two-list dep-graph surface: `push_dep` on the mutation
    /// side, `deps_of` on the read side, both keyed on the same
    /// [`crate::dep::DepList`] discriminator. Same "one typed dispatch on
    /// the substrate primitive, thin projections at each consumer"
    /// discipline the sibling per-slot read accessors ([`Self::nome`]
    /// e6b7d97, [`Self::versao`], [`Self::kind`]) carry — extended onto
    /// the outer-[`Caixa`] typed-dispatch read surface.
    ///
    /// Declared `pub const fn` — every operator in the body is already
    /// `const`-callable (the [`crate::dep::DepList`] enum is a plain
    /// closed-set `#[derive(Copy)]` discriminator so the `match` arms
    /// are const-evaluable, and each arm forwards through the sibling
    /// `pub const fn` [`Self::deps`] / [`Self::deps_dev`] per-slot
    /// slice accessor). Pinned load-bearing by the paired
    /// [`caixa_deps_of_is_const_fn`][pin] wrapper test (a
    /// `const fn deps_of_via_const_fn(c: &Caixa, l: DepList) -> &[Dep]`
    /// that forwards through this accessor) — any future accidental
    /// downgrade to non-`const` fails the wrapper at caixa-core build
    /// time with E0015 (`cannot call non-const method`), strictly
    /// stronger than a runtime `assert!` and side-stepping the
    /// destructor-in-const restriction the `Caixa` fixture's owning
    /// carriers rule out on the direct-`const _: () = assert!(…)`
    /// residence. Peer of the sibling per-`Dep` outer-accessor
    /// family's parallel `const`-eval-surface pass and of the outer-
    /// `Caixa` slice-return accessor family's earlier pass (231a968)
    /// — same "one canonical dispatch per axis, `const`-eval posture
    /// pinned at the substrate primitive, thin projections at each
    /// consumer" discipline extended onto the outer-`Caixa`
    /// typed-dispatch read surface on the [`DepList`]-keyed dep-list
    /// axis.
    ///
    /// [DepList]: crate::dep::DepList
    /// [pin]: tests::caixa_deps_of_is_const_fn
    #[must_use]
    pub const fn deps_of(&self, list: crate::dep::DepList) -> &[Dep] {
        match list {
            crate::dep::DepList::Prod => self.deps(),
            crate::dep::DepList::Dev => self.deps_dev(),
        }
    }

    /// Substrate-canonical per-[`Caixa`] typed-mutation dispatch every
    /// consumer that appends to one of the two dep-list axes keys off
    /// — routes the `(list: DepList, dep: Dep)` tuple through one typed
    /// method on the substrate primitive rather than the prior
    /// `feira add`-side open-coded `if self.dev { &mut caixa.deps_dev }
    /// else { &mut caixa.deps }` inline dispatch + open-coded
    /// `.iter().any(|d| d.nome == …)` dup-check cascade. Refuses the
    /// mutation with the canonical typed [`DepError::DuplicateNome`] on
    /// a within-list name collision — the same `list: &'static str`
    /// diagnostic shape [`Self::validate_deps`]'s per-list
    /// [`crate::render::insert_first_seen`] walk raises on the peer
    /// parse-time within-list dedup axis, so a future author reading a
    /// `feira add` refusal and a `feira build` refusal reaches for the
    /// same corrective surface without switching diagnostic idioms.
    ///
    /// The two-arm [`crate::dep::DepList`] enum is the substrate's
    /// closed-set typed carrier for the "runtime-closure `:deps` vs
    /// dev-only-closure `:deps-dev`" axis every dep-list consumer
    /// dispatches on — the compiler-checked exhaustiveness on the
    /// enum's `match` arms is the build-time guarantee that no future
    /// per-list mutation-site regresses to a bare-`bool`-flag
    /// (`is_dev: bool`) inline dispatch that a future third
    /// dep-list axis (a `:deps-build` build-only closure once the
    /// substrate grows cross-artifact heterogeneous dep-graphs, per
    /// CAIXA-SDLC §I) would silently split at every consumer.
    ///
    /// Same "one typed dispatch on the substrate primitive, thin
    /// projections at each consumer" discipline the sibling per-slot
    /// read accessors ([`Self::deps`] ad34b4e, [`Self::deps_dev`],
    /// [`Self::nome`] e6b7d97, [`Self::versao`], [`Self::kind`])
    /// carry — extended onto the outer-[`Caixa`] typed-mutation surface,
    /// the substrate's first typed-mutation dispatch on the top-level
    /// manifest. The prior `feira add` open-coded `&mut caixa.deps` /
    /// `&mut caixa.deps_dev` inline field-access + `bail!` string-
    /// diagnostic path routed no through-line back to the typed slot,
    /// so a future extension of either dep-list axis to a richer author
    /// surface (a per-cluster override the operator pins through a
    /// future `:placement`-scoped dep-list slot the CAIXA-SDLC §I
    /// roadmap acknowledges, an M4
    /// `mesh.pleme.io/v1alpha1/Caixa` CR materializer's per-CR
    /// admission-webhook that normalized the list at admission time)
    /// would have had to be threaded through the `feira add` mutation
    /// site in lockstep with every read consumer or one path would
    /// silently disagree with the other on which list a given dep lands
    /// in. Lifting the resolution rule to a typed method on the
    /// substrate primitive means every downstream dep-list-mutating
    /// consumer of the top-level manifest reaches for exactly one typed
    /// dispatch — the resolver's accept-set migrates as a unit on any
    /// future axis addition.
    ///
    /// # Errors
    ///
    /// Returns [`DepError::DuplicateNome`] with `list = list.as_str()`
    /// when another entry in the same list already carries the same
    /// `:nome` — the mutation is refused and the caller can surface the
    /// typed diagnostic to the author (the `feira add` verb routes the
    /// error through `anyhow::Error::from`, which preserves the
    /// canonical `#[error(...)]`-templated diagnostic body).
    pub fn push_dep(&mut self, list: crate::dep::DepList, dep: Dep) -> Result<(), DepError> {
        let target = match list {
            crate::dep::DepList::Prod => &mut self.deps,
            crate::dep::DepList::Dev => &mut self.deps_dev,
        };
        if target.iter().any(|d| d.nome() == dep.nome()) {
            return Err(DepError::DuplicateNome {
                nome: dep.nome().to_string(),
                list: list.as_str(),
            });
        }
        target.push(dep);
        Ok(())
    }

    /// Substrate-canonical per-`Caixa` `:limits` M2 typed-slot outer-
    /// composite Lunatic-per-process wasm32-sandboxing-composite optional-
    /// composite-reference accessor every consumer of the top-level
    /// manifest's per-Servico [`LimitsSpec`] outer-composite reader keys
    /// off — returns the author-declared `:limits` typed composite
    /// verbatim as an `Option<&LimitsSpec>` reference over the same
    /// backing storage the raw `self.limits.as_ref()` field access
    /// borrows from, with `None` naming the "no `:limits` block
    /// authored — every per-axis Lunatic-sandbox cap defers to the
    /// wasm-engine-default arm named on the per-axis
    /// [`LimitsSpec::memory`] / [`LimitsSpec::fuel`] /
    /// [`LimitsSpec::wall_clock`] / [`LimitsSpec::cpu`] scalar-accessor
    /// docstrings" partition every downstream Servico-M2-overlay
    /// emitter treats as "emit nothing" and the sibling
    /// [`crate::StandardLayout::verify`] per-`:limits` shape gate
    /// treats as "skip the per-axis
    /// [`crate::LimitsError::MemoryZero`] / `MemoryBelowWasm32Page` /
    /// `FuelZero` / `WallClockZero` / `CpuZero` refusal cascade".
    ///
    /// The outer `:limits` slot carries the M2 Servico-runtime typed
    /// composite — the load-bearing container of every Lunatic-shaped
    /// per-process wasm32-sandbox cap axis every long-running wasm
    /// component's runtime dispatches on (INSPIRATIONS §III.1 —
    /// Lunatic per-process linear-memory / fuel / wall-clock /
    /// millicore cap primitives translated onto pleme-io's typed
    /// `:limits :memory` / `:limits :fuel` / `:limits :wall-clock` /
    /// `:limits :cpu` sub-slot axes; CAIXA-SDLC §II — the typed-M2
    /// slot algebra the wasm-engine + `pleme-computeunit` Helm-library
    /// chart both fan on). Every per-`:limits` axis threads through a
    /// lifted per-slot accessor on the [`LimitsSpec`] type: the
    /// [`LimitsSpec::memory`] wasm32 linear-memory byte-cap scalar
    /// accessor, the [`LimitsSpec::fuel`] wasmtime fuel-cap scalar
    /// accessor, the [`LimitsSpec::wall_clock`] per-call wall-clock
    /// deadline scalar accessor, and the [`LimitsSpec::cpu`]
    /// K8s-millicore soft-CPU-share scalar accessor. Every downstream
    /// consumer that reaches for a limits axis first passes through
    /// this outer accessor onto the composite and then dispatches
    /// onto the per-axis accessor — the two-level dispatch means
    /// every per-`:limits` reader now routes through a typed dispatch
    /// on the substrate primitive at both altitudes.
    ///
    /// Prior to this lift the `.limits` `Option<LimitsSpec>` composite
    /// was accessed inline at three production sites — the
    /// [`crate::StandardLayout::verify`] per-`:limits` shape gate's
    /// `if let Some(l) = &caixa.limits { … }` traversal head
    /// (caixa-core/src/layout.rs:882, which drives the per-axis
    /// refusal cascade on the composite: the `LimitsError::MemoryZero`
    /// / `MemoryBelowWasm32Page` / `MemoryExceedsWasm32Max` /
    /// `FuelZero` / `FuelExceedsMax` / `WallClockZero` /
    /// `WallClockExceedsMax` / `CpuZero` / `CpuExceedsMax` refusals
    /// [`LimitsSpec::validate`] fans onto), the
    /// [`crate::render::servico_m2_overlay`] per-Servico M2 overlay
    /// emitter's `if let Some(limits) = &caixa.limits { … }` traversal
    /// head (caixa-core/src/render.rs:18504, which drives the
    /// `M2_KEY_LIMITS`-keyed `limits.is_empty()`-gated `serde_yaml`
    /// projection every `caixa-helm` / `caixa-flux` Servico values-
    /// block emitter fans on), and the
    /// [`Self::declared_servico_slots`] per-Servico M2 declared-slot-
    /// set enumerator's `self.limits.is_some()` presence probe
    /// (caixa-core/src/manifest.rs:1788, which drives the
    /// `M2_AUTHOR_KEY_LIMITS` kebab-case author-label push every
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] kind-coherence
    /// gate reads) — three open-coded outer-field accesses that
    /// expressed no compile-time link back to the typed slot at the
    /// [`Caixa`] altitude. A future extension of the `:limits` outer
    /// axis to a richer author surface (a multi-`:limits` list the M4
    /// CR materializer resolves per-CR at admission time so a Servico
    /// can expose a compute-heavy + IO-heavy limits pair, a per-
    /// cluster `:limits-overrides` slot the operator pins so a
    /// cluster-specific policy can tighten a caixa-declared cap
    /// without re-authoring the `caixa.lisp`, a promotion of the
    /// plain `Option<LimitsSpec>` to a richer
    /// `{static, dynamic}` partition once the wasm-engine's runtime-
    /// resolved dynamic-cap surface lands) would have had to be
    /// threaded through all three open-coded copies in lockstep or
    /// one consumer would silently disagree with the peers on which
    /// limits composite a given Caixa resolves to — the layout gate's
    /// per-axis bracket-dispatch seed reading the raw slot while the
    /// peer `servico_m2_overlay` emitter read an operator-resolved
    /// slot would silently split the build-time sandbox-shape gate
    /// from the runtime `ComputeUnit` CR emission gate, a three-
    /// consumer split at the layout gate, the M2 overlay emitter, and
    /// the declared-slot enumerator far from the source `caixa.lisp`
    /// with no field naming the limits-drift root cause. Lifting the
    /// resolution rule to a typed method on the substrate primitive
    /// means every downstream consumer of the caixa's per-`Caixa`
    /// Lunatic-sandboxing outer-composite surface reaches for exactly
    /// one typed dispatch — the resolver's accept-set migrates as a
    /// unit on any future axis addition.
    ///
    /// First outer top-level [`Caixa`] `Option<&Composite>`-return
    /// composite-reference accessor — opens the outer-`Caixa`
    /// `Option<&Composite>` composite-reference projection pattern the
    /// sibling per-`Caixa` `:behavior` [`crate::BehaviorSpec`] /
    /// `:politicas` [`crate::aplicacao::MeshPolicy`] / `:placement`
    /// [`crate::aplicacao::Placement`] / `:entrada`
    /// [`crate::aplicacao::Entrada`] future outer-composite lifts
    /// fold on. Peer of the M3 mesh-slot outer-composite family the
    /// sibling [`crate::AplicacaoSpec::politicas`] (534dc21) /
    /// [`crate::AplicacaoSpec::placement`] (9abb8f0) /
    /// [`crate::AplicacaoSpec::entrada`] (d32111c) composite-reference
    /// accessors already close on the outer [`crate::AplicacaoSpec`]
    /// altitude — extends that "one typed dispatch on the substrate
    /// primitive, thin projections at each consumer" discipline onto
    /// the outer top-level [`Caixa`] altitude, opening the M2 Servico-
    /// runtime slot family's outer-composite axis. Returns
    /// `Option<&LimitsSpec>` (not the owning composite by copy or
    /// clone) because every downstream consumer of the limits
    /// composite treats it as a read-only per-axis dispatch source —
    /// the reference-view is the narrowest borrow that supports every
    /// present + roadmapped consumer (per-axis accessor dispatch,
    /// `.is_empty()`-gated overlay projection, presence-probe early
    /// return on the "author-omitted `:limits` ⇒ engine-default
    /// applies" partition) without cloning the composite through
    /// every consumer's fast path. The `Option` half of the return-
    /// type preserves the load-bearing "author-omitted `:limits` ⇒
    /// engine-default applies" partition (not a default composite the
    /// downstream must reject on emptiness) — the accessor projects
    /// the raw `Option<LimitsSpec>` slot's presence bit through the
    /// reference-return unchanged. Named `limits()` to match the
    /// storage field's name verbatim and the tatara-lisp author-
    /// surface term (`:limits`) the field's own docstring already
    /// carries.
    #[must_use]
    pub const fn limits(&self) -> Option<&LimitsSpec> {
        self.limits.as_ref()
    }

    /// Substrate-canonical per-`Caixa` `:behavior` M2 typed-slot outer-
    /// composite OTP-`gen_server`-shaped callback-table optional-
    /// composite-reference accessor every consumer of the top-level
    /// manifest's per-Servico [`BehaviorSpec`] outer-composite reader
    /// keys off — returns the author-declared `:behavior` typed
    /// composite verbatim as an `Option<&BehaviorSpec>` reference over
    /// the same backing storage the raw `self.behavior.as_ref()` field
    /// access borrows from, with `None` naming the "no `:behavior`
    /// block authored — every per-callback OTP-shaped hook defers to
    /// the wasm-engine's runtime default arm named on the per-axis
    /// [`BehaviorSpec::on_init`] / [`BehaviorSpec::on_call`] /
    /// [`BehaviorSpec::on_cast`] / [`BehaviorSpec::on_info`] /
    /// [`BehaviorSpec::on_state_change`] /
    /// [`BehaviorSpec::on_terminate`] scalar-accessor docstrings"
    /// partition every downstream Servico-M2-overlay emitter treats as
    /// "emit nothing" and the sibling [`crate::StandardLayout::verify`]
    /// per-`:behavior` shape gate treats as "skip the per-arm
    /// [`crate::behavior::BehaviorError`] refusal cascade + the
    /// per-callback on-disk `MissingEntry` existence check".
    ///
    /// The outer `:behavior` slot carries the M2 Servico-runtime typed
    /// composite — the load-bearing container of every OTP-shaped
    /// per-Servico lifecycle-callback path axis every long-running wasm
    /// component's runtime dispatches on (INSPIRATIONS §II.3 — Erlang/
    /// OTP `gen_server:init/1` / `handle_call/3` / `handle_cast/2` /
    /// `handle_info/2` / `code_change/3` / `terminate/2` primitives
    /// translated onto pleme-io's typed `:behavior :on-init` /
    /// `:on-call` / `:on-cast` / `:on-info` / `:on-state-change` /
    /// `:on-terminate` sub-slot axes; CAIXA-SDLC §II — the typed-M2
    /// slot algebra the wasm-engine + `pleme-computeunit` Helm-library
    /// chart both fan on). Every per-`:behavior` axis threads through a
    /// lifted per-callback accessor on the [`BehaviorSpec`] type
    /// (9b4ecde / d66c702 / 156ddbe / 99616ac / 4846cef / 701add7).
    /// Every downstream consumer that reaches for a behavior axis
    /// first passes through this outer accessor onto the composite
    /// and then dispatches onto the per-callback accessor — the
    /// two-level dispatch means every per-`:behavior` reader now
    /// routes through a typed dispatch on the substrate primitive at
    /// both altitudes.
    ///
    /// Composes cross-slot with the M2 `:upgrade-from` gate: the
    /// [`crate::upgrade::validate_upgrade_from_against_behavior`]
    /// cross-slot composition gate at [`crate::StandardLayout::verify`]
    /// keys the "per-version `:state-change` instruction must have a
    /// `:on-state-change` callback" precondition off this accessor's
    /// composite (the callback-side counterpart to the
    /// `:upgrade-from :instructions :state-change :script` refusal at
    /// the appup-side). Threading that gate's traversal input through
    /// this accessor closes the cross-slot invariant on the substrate
    /// primitive, not on the raw field.
    ///
    /// Prior to this lift the `.behavior` `Option<BehaviorSpec>`
    /// composite was accessed inline at four production sites — the
    /// [`crate::StandardLayout::verify`] per-`:behavior` shape gate's
    /// `if let Some(b) = &caixa.behavior { … }` traversal head
    /// (caixa-core/src/layout.rs:896, which drives the per-arm
    /// `BehaviorError` refusal cascade + the per-callback on-disk
    /// [`crate::LayoutError::MissingEntry`] existence check under
    /// [`crate::render::LAYOUT_MISSING_ENTRY_KIND_BEHAVIOR_CALLBACK`]),
    /// the [`crate::upgrade::validate_upgrade_from_against_behavior`]
    /// cross-slot composition gate's `caixa.behavior.as_ref()`
    /// traversal-input feed (caixa-core/src/layout.rs:1008, which
    /// drives the `:state-change` ↔ `:on-state-change` precondition
    /// refusal), the [`crate::render::servico_m2_overlay`] per-Servico
    /// M2 overlay emitter's `if let Some(behavior) = &caixa.behavior
    /// { … }` traversal head (caixa-core/src/render.rs:18513, which
    /// drives the `M2_KEY_BEHAVIOR`-keyed `behavior.is_empty()`-gated
    /// `serde_yaml` projection every `caixa-helm` / `caixa-flux`
    /// Servico values-block emitter fans on), and the
    /// [`Self::declared_servico_slots`] per-Servico M2 declared-slot-
    /// set enumerator's `self.behavior.is_some()` presence probe
    /// (caixa-core/src/manifest.rs:1919, which drives the
    /// `M2_AUTHOR_KEY_BEHAVIOR` kebab-case author-label push every
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] kind-coherence
    /// gate reads) — four open-coded outer-field accesses that
    /// expressed no compile-time link back to the typed slot at the
    /// [`Caixa`] altitude. A future extension of the `:behavior`
    /// outer axis to a richer author surface (a per-callback overlay
    /// resolver the operator materializes at admission time so a
    /// cluster-specific policy can inject a per-callback tracing
    /// interceptor without re-authoring the `caixa.lisp`, a promotion
    /// of the plain `Option<BehaviorSpec>` to a richer `{static,
    /// dynamic}` partition once a runtime-resolved behavior-swap
    /// surface lands, the M4 per-callback middleware chain the
    /// caixa-operator's per-Servico admission webhook keys off) would
    /// have had to be threaded through all four open-coded copies in
    /// lockstep or one consumer would silently disagree with the
    /// peers on which behavior composite a given Caixa resolves to —
    /// the layout gate's per-callback existence-check seed reading
    /// the raw slot while the peer `servico_m2_overlay` emitter read
    /// an operator-resolved slot would silently split the build-time
    /// callback-shape gate from the runtime `ComputeUnit` CR emission
    /// gate from the cross-slot `:state-change` composition gate from
    /// the M2 declared-slot enumerator, a four-consumer split far
    /// from the source `caixa.lisp` with no field naming the
    /// behavior-drift root cause. Lifting the resolution rule to a
    /// typed method on the substrate primitive means every downstream
    /// consumer of the caixa's per-`Caixa` OTP-callback-table outer-
    /// composite surface reaches for exactly one typed dispatch — the
    /// resolver's accept-set migrates as a unit on any future axis
    /// addition.
    ///
    /// Second outer top-level [`Caixa`] `Option<&Composite>`-return
    /// composite-reference accessor — sibling to the opening
    /// [`Self::limits`] (b2bd9d7) accessor on the outer-`Caixa`
    /// `Option<&Composite>` composite-reference sub-family, extends
    /// the "one typed dispatch on the substrate primitive, thin
    /// projections at each consumer" discipline onto the second of
    /// the three M2 Servico-runtime slots. The remaining
    /// `Option<&Composite>` axes at the outer top-level [`Caixa`]
    /// altitude — the M3 mesh-slot family (`:politicas`,
    /// `:placement`, `:entrada` — already closed on the inner
    /// [`crate::AplicacaoSpec`] altitude via 534dc21 / 9abb8f0 /
    /// d32111c) — remain the future sibling lifts on the outer
    /// top-level projection. Returns `Option<&BehaviorSpec>` (not
    /// the owning composite by copy or clone) because every
    /// downstream consumer of the behavior composite treats it as a
    /// read-only per-callback dispatch source — the reference-view is
    /// the narrowest borrow that supports every present + roadmapped
    /// consumer (per-callback accessor dispatch, `.is_empty()`-gated
    /// overlay projection, presence-probe early return on the
    /// "author-omitted `:behavior` ⇒ runtime-default applies"
    /// partition, cross-slot `:state-change` composition input)
    /// without cloning the composite through every consumer's fast
    /// path. The `Option` half of the return-type preserves the
    /// load-bearing "author-omitted `:behavior` ⇒ runtime-default
    /// applies" partition (not a default composite the downstream
    /// must reject on emptiness) — the accessor projects the raw
    /// `Option<BehaviorSpec>` slot's presence bit through the
    /// reference-return unchanged. Named `behavior()` to match the
    /// storage field's name verbatim and the tatara-lisp author-
    /// surface term (`:behavior`) the field's own docstring already
    /// carries.
    #[must_use]
    pub const fn behavior(&self) -> Option<&crate::BehaviorSpec> {
        self.behavior.as_ref()
    }

    /// Substrate-canonical per-`Caixa` `:politicas` M3 mesh-slot outer-
    /// composite MESH-COMPOSITION-shaped mesh-policy optional-composite-
    /// reference accessor every consumer of the top-level manifest's
    /// per-Aplicacao [`crate::aplicacao::MeshPolicy`] outer-composite
    /// reader keys off — returns the author-declared `:politicas` typed
    /// composite verbatim as an `Option<&MeshPolicy>` reference over the
    /// same backing storage the raw `self.politicas.as_ref()` field
    /// access borrows from, with `None` naming the "no `:politicas`
    /// block authored — every per-axis mesh-policy scalar defers to the
    /// cluster-default arm named on the per-axis
    /// [`crate::aplicacao::MeshPolicy::timeout`] /
    /// [`crate::aplicacao::MeshPolicy::retries`] /
    /// [`crate::aplicacao::MeshPolicy::circuit_breaker`] /
    /// [`crate::aplicacao::MeshPolicy::mtls_required`] /
    /// [`crate::aplicacao::MeshPolicy::rate_limit`] scalar-accessor
    /// docstrings" partition every downstream caixa-mesh /
    /// caixa-flux / caixa-helm Aplicacao-artifact emitter treats as
    /// "emit no per-`:politicas` overlay" and the sibling
    /// [`Self::aplicacao_view`] Aplicacao-composition seed folds through
    /// the [`crate::aplicacao::MeshPolicy::default`] cluster-default
    /// arm.
    ///
    /// The outer `:politicas` slot carries the M3 mesh-slot per-
    /// Aplicacao typed composite — the load-bearing container of every
    /// mesh-level policy axis every Cilium NetworkPolicy / Gateway API
    /// v1.x HTTPRoute / future M4 per-edge policy overlay emitter fans
    /// on (MESH-COMPOSITION §III.2 — the Aplicacao's typed mesh-policy
    /// composite; §V — the "no infinite blocking" per-call deadline +
    /// "sandboxing-by-default" mTLS-enforcement CSE invariants; §III.3
    /// — the typed inter-Servico contrato-edge overlay the per-`(:de,
    /// :para)` mesh renderer keys off). Every per-`:politicas` axis
    /// threads through a lifted per-slot accessor on the
    /// [`crate::aplicacao::MeshPolicy`] type: the
    /// [`crate::aplicacao::MeshPolicy::mtls_required`] (c0110f1) Cilium
    /// mTLS-enforcement toggle, the
    /// [`crate::aplicacao::MeshPolicy::retries`] (bdfb399) transient-
    /// failure retry budget, the [`crate::aplicacao::MeshPolicy::timeout`]
    /// (7073d0f) Gateway-API per-call deadline, the
    /// [`crate::aplicacao::MeshPolicy::circuit_breaker`] (b0e741a)
    /// Envoy-outlier-detection composite. Every downstream consumer
    /// that reaches for a mesh-policy axis first passes through this
    /// outer accessor onto the composite and then dispatches onto the
    /// per-axis accessor — the two-level dispatch means every per-
    /// `:politicas` reader now routes through a typed dispatch on the
    /// substrate primitive at both altitudes.
    ///
    /// Composes through [`Self::aplicacao_view`]'s Aplicacao-composition
    /// seed: the Aplicacao-view builder folds the outer `Option`'s
    /// author-omitted arm onto the [`crate::aplicacao::MeshPolicy::default`]
    /// cluster-default, so the peer inner [`crate::AplicacaoSpec::politicas`]
    /// (534dc21) `&MeshPolicy`-return accessor observes a typed
    /// composite whether or not the author declared the outer slot.
    /// The outer accessor preserves the "author-omitted vs authored-
    /// empty" partition the inner accessor's `is_empty()`-gated
    /// renderer overlay collapses — routing the presence bit through
    /// this accessor keeps the [`Self::declared_mesh_slots`] M3 kind-
    /// coherence enumerator's `M3_AUTHOR_KEY_POLITICAS` push separate
    /// from the inner `MeshPolicy::is_empty()`-gated overlay elision.
    ///
    /// Prior to this lift the `.politicas` `Option<MeshPolicy>`
    /// composite was accessed inline at two production sites — the
    /// [`Self::aplicacao_view`] Aplicacao-composition seed's
    /// `self.politicas.clone().unwrap_or_default()` traversal head
    /// (caixa-core/src/manifest.rs:1899, which drives the fold onto
    /// the [`crate::aplicacao::MeshPolicy::default`] cluster-default
    /// arm the inner [`crate::AplicacaoSpec::politicas`] accessor
    /// then observes), and the [`Self::declared_mesh_slots`] M3
    /// declared-slot-set enumerator's `self.politicas.is_some()`
    /// presence probe (caixa-core/src/manifest.rs:1961, which drives
    /// the `M3_AUTHOR_KEY_POLITICAS` kebab-case author-label push
    /// every [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-
    /// coherence gate reads) — two open-coded outer-field accesses
    /// that expressed no compile-time link back to the typed slot at
    /// the [`Caixa`] altitude. A future extension of the `:politicas`
    /// outer axis to a richer author surface (a per-cluster
    /// `:politicas-overrides` slot the operator materializes at
    /// admission time so a cluster-specific policy can tighten the
    /// caixa-declared bound without re-authoring the `caixa.lisp`, a
    /// promotion of the plain `Option<MeshPolicy>` to a richer
    /// `{static, dynamic}` partition once the M4 per-edge
    /// contrato-scoped policy-override surface lands, the M5 traffic-
    /// shaping composition the caixa-operator's per-Aplicacao mesh
    /// admission webhook keys off) would have had to be threaded
    /// through both open-coded copies in lockstep or the Aplicacao-
    /// composition seed's default-fold arm would silently disagree
    /// with the M3 declared-slot enumerator on which policy composite
    /// a given Caixa resolves to — the seed reading an operator-
    /// resolved slot while the enumerator's presence probe read the
    /// raw slot would silently split the build-time mesh-artifact
    /// emission gate from the M3 declared-slot enumerator's kind-
    /// coherence gate, a two-consumer split far from the source
    /// `caixa.lisp` with no field naming the policy-drift root cause.
    /// Lifting the resolution rule to a typed method on the substrate
    /// primitive means every downstream consumer of the caixa's per-
    /// `Caixa` MESH-COMPOSITION mesh-policy outer-composite surface
    /// reaches for exactly one typed dispatch — the resolver's
    /// accept-set migrates as a unit on any future axis addition.
    ///
    /// Third outer top-level [`Caixa`] `Option<&Composite>`-return
    /// composite-reference accessor — sibling to the opening
    /// [`Self::limits`] (b2bd9d7) and [`Self::behavior`] (35d8b52)
    /// accessors on the outer-`Caixa` `Option<&Composite>` composite-
    /// reference sub-family, extends the "one typed dispatch on the
    /// substrate primitive, thin projections at each consumer"
    /// discipline onto the first of the three M3 mesh-slot axes.
    /// Peer of the closed inner mesh-slot outer-composite family the
    /// sibling [`crate::AplicacaoSpec::politicas`] (534dc21) /
    /// [`crate::AplicacaoSpec::placement`] (9abb8f0) /
    /// [`crate::AplicacaoSpec::entrada`] (d32111c) composite-reference
    /// accessor pins already close on the inner [`crate::AplicacaoSpec`]
    /// altitude — opens the outer top-level [`Caixa`] altitude's M3
    /// mesh-slot arm of the composite-reference family the remaining
    /// two axes (`:placement`, `:entrada`) fold onto in future
    /// sibling lifts. Returns `Option<&MeshPolicy>` (not the owning
    /// composite by copy or clone) because every downstream consumer
    /// of the mesh-policy composite treats it as a read-only per-axis
    /// dispatch source — the reference-view is the narrowest borrow
    /// that supports every present + roadmapped consumer (per-axis
    /// accessor dispatch, `.is_empty()`-gated overlay projection,
    /// presence-probe early return on the "author-omitted `:politicas`
    /// ⇒ cluster-default applies" partition, `Aplicacao`-composition
    /// seed's default-fold arm) without cloning the composite through
    /// every consumer's fast path. The `Option` half of the return-
    /// type preserves the load-bearing "author-omitted `:politicas` ⇒
    /// cluster-default applies" partition (not a default composite
    /// the downstream must reject on emptiness) — the accessor
    /// projects the raw `Option<MeshPolicy>` slot's presence bit
    /// through the reference-return unchanged. Named `politicas()` to
    /// match the storage field's name verbatim and the tatara-lisp
    /// author-surface term (`:politicas`) the field's own docstring
    /// already carries.
    #[must_use]
    pub const fn politicas(&self) -> Option<&crate::aplicacao::MeshPolicy> {
        self.politicas.as_ref()
    }

    /// Substrate-canonical per-`Caixa` `:placement` M3 mesh-slot outer-
    /// composite MESH-COMPOSITION-shaped distribution optional-composite-
    /// reference accessor every consumer of the top-level manifest's
    /// per-Aplicacao [`crate::aplicacao::Placement`] outer-composite
    /// reader keys off — returns the author-declared `:placement` typed
    /// composite verbatim as an `Option<&Placement>` reference over the
    /// same backing storage the raw `self.placement.as_ref()` field
    /// access borrows from, with `None` naming the "no `:placement`
    /// block authored — every per-axis placement scalar defers to the
    /// cluster-default arm named on the per-axis
    /// [`crate::aplicacao::Placement::estrategia`] /
    /// [`crate::aplicacao::Placement::clusters`] /
    /// [`crate::aplicacao::Placement::affinity`] /
    /// [`crate::aplicacao::Placement::shard_key`] scalar-accessor
    /// docstrings" partition every downstream caixa-mesh /
    /// caixa-flux / caixa-helm Aplicacao-artifact emitter treats as
    /// "emit no per-`:placement` overlay" and the sibling
    /// [`Self::aplicacao_view`] Aplicacao-composition seed folds through
    /// the [`crate::aplicacao::Placement::default`] cluster-default arm.
    ///
    /// The outer `:placement` slot carries the M3 mesh-slot per-
    /// Aplicacao typed distribution composite — the load-bearing
    /// container of every where-does-this-Aplicacao-run axis every
    /// caixa-mesh programs.yaml per-cluster distribution overlay /
    /// caixa-flux per-Aplicacao GitRepository/HelmRelease fan-out /
    /// future M4 per-Aplicacao Akka-style cluster-sharding entity-id
    /// resolver emitter fans on (MESH-COMPOSITION §II.4 — the
    /// Aplicacao's typed distribution composite; §V CSE invariants —
    /// "distribution is a first-class typed composite, not a runtime
    /// scheduler hint" the per-axis scalars enforce; §III.3 — the
    /// typed inter-Servico contrato-edge overlay the per-cluster
    /// mesh renderer keys off). Every per-`:placement` axis threads
    /// through a lifted per-slot accessor on the
    /// [`crate::aplicacao::Placement`] type: the
    /// [`crate::aplicacao::Placement::estrategia`] (921fe1b)
    /// MESH-COMPOSITION distribution-strategy scalar, the
    /// [`crate::aplicacao::Placement::clusters`] (a6e18d7) per-cluster
    /// distribution-target slice, the [`crate::aplicacao::Placement::affinity`]
    /// M3-Adaptive-compression-hint optional-scalar, and the
    /// [`crate::aplicacao::Placement::shard_key`] (7cd2a28) Akka-cluster-
    /// sharding extractor-expression optional-scalar. Every downstream
    /// consumer that reaches for a placement axis first passes through
    /// this outer accessor onto the composite and then dispatches onto
    /// the per-axis accessor — the two-level dispatch means every per-
    /// `:placement` reader now routes through a typed dispatch on the
    /// substrate primitive at both altitudes.
    ///
    /// Composes through [`Self::aplicacao_view`]'s Aplicacao-composition
    /// seed: the Aplicacao-view builder folds the outer `Option`'s
    /// author-omitted arm onto the [`crate::aplicacao::Placement::default`]
    /// cluster-default, so the peer inner [`crate::AplicacaoSpec::placement`]
    /// (9abb8f0) `&Placement`-return accessor observes a typed composite
    /// whether or not the author declared the outer slot. The outer
    /// accessor preserves the "author-omitted vs authored-empty" partition
    /// the inner accessor collapses at the cluster-default fold —
    /// routing the presence bit through this accessor keeps the
    /// [`Self::declared_mesh_slots`] M3 kind-coherence enumerator's
    /// `M3_AUTHOR_KEY_PLACEMENT` push separate from the inner
    /// [`crate::AplicacaoSpec::validate_placement`]-gated overlay
    /// dispatch.
    ///
    /// Prior to this lift the `.placement` `Option<Placement>`
    /// composite was accessed inline at two production sites — the
    /// [`Self::aplicacao_view`] Aplicacao-composition seed's
    /// `self.placement.clone().unwrap_or_default()` traversal head
    /// (caixa-core/src/manifest.rs:2036, which drives the fold onto
    /// the [`crate::aplicacao::Placement::default`] cluster-default
    /// arm the inner [`crate::AplicacaoSpec::placement`] accessor
    /// then observes), and the [`Self::declared_mesh_slots`] M3
    /// declared-slot-set enumerator's `self.placement.is_some()`
    /// presence probe (caixa-core/src/manifest.rs:2100, which drives
    /// the `M3_AUTHOR_KEY_PLACEMENT` kebab-case author-label push
    /// every [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-
    /// coherence gate reads) — two open-coded outer-field accesses
    /// that expressed no compile-time link back to the typed slot at
    /// the [`Caixa`] altitude. A future extension of the `:placement`
    /// outer axis to a richer author surface (a per-cluster
    /// `:placement-overrides` slot the operator materializes at
    /// admission time so a cluster-specific placement can tighten the
    /// caixa-declared bound without re-authoring the `caixa.lisp`, a
    /// per-tenant placement-alias table the M4
    /// `mesh.pleme.io/v1alpha1/Aplicacao` CR materializer resolves
    /// per-CR at admission time, a promotion of the plain
    /// `Option<Placement>` to a richer `{static, dynamic}` partition
    /// once Orleans-style virtual-actor dynamic placement comes into
    /// typed scope) would have had to be threaded through both open-
    /// coded copies in lockstep or the Aplicacao-composition seed's
    /// default-fold arm would silently disagree with the M3 declared-
    /// slot enumerator on which distribution composite a given Caixa
    /// resolves to — the seed reading an operator-resolved slot while
    /// the enumerator's presence probe read the raw slot would
    /// silently split the build-time distribution-artifact emission
    /// gate from the M3 declared-slot enumerator's kind-coherence
    /// gate, a two-consumer split far from the source `caixa.lisp`
    /// with no field naming the distribution-drift root cause.
    /// Lifting the resolution rule to a typed method on the substrate
    /// primitive means every downstream consumer of the caixa's per-
    /// `Caixa` MESH-COMPOSITION distribution outer-composite surface
    /// reaches for exactly one typed dispatch — the resolver's
    /// accept-set migrates as a unit on any future axis addition.
    ///
    /// Fourth outer top-level [`Caixa`] `Option<&Composite>`-return
    /// composite-reference accessor — sibling to the opening
    /// [`Self::limits`] (b2bd9d7) / [`Self::behavior`] (35d8b52) M2-
    /// Servico-runtime pair and the peer [`Self::politicas`] (5d23d29)
    /// M3-mesh-slot arm on the outer-`Caixa` `Option<&Composite>`
    /// composite-reference sub-family, folds on the "one typed
    /// dispatch on the substrate primitive, thin projections at each
    /// consumer" discipline extended onto the second of the three M3
    /// mesh-slot axes. Peer of the closed inner mesh-slot outer-
    /// composite family the sibling
    /// [`crate::AplicacaoSpec::politicas`] (534dc21) /
    /// [`crate::AplicacaoSpec::placement`] (9abb8f0) /
    /// [`crate::AplicacaoSpec::entrada`] (d32111c) composite-reference
    /// accessor pins already close on the inner
    /// [`crate::AplicacaoSpec`] altitude — folds on the outer top-
    /// level [`Caixa`] altitude's M3 mesh-slot arm the sibling
    /// [`Self::politicas`] opened, extending the discipline onto the
    /// second of the three M3 mesh-slot axes. The remaining M3
    /// mesh-slot axis (`:entrada`) folds onto this accessor's
    /// discipline in the final sibling lift, closing the outer top-
    /// level [`Caixa`] `Option<&Composite>` M3 mesh-slot sub-family.
    /// Returns `Option<&Placement>` (not the owning composite by copy
    /// or clone) because every downstream consumer of the placement
    /// composite treats it as a read-only per-axis dispatch source —
    /// the reference-view is the narrowest borrow that supports every
    /// present + roadmapped consumer (per-axis accessor dispatch,
    /// serde composite-serialization on the programs.yaml overlay,
    /// presence-probe early return on the "author-omitted `:placement`
    /// ⇒ cluster-default applies" partition, `Aplicacao`-composition
    /// seed's default-fold arm) without cloning the composite through
    /// every consumer's fast path. The `Option` half of the return-
    /// type preserves the load-bearing "author-omitted `:placement` ⇒
    /// cluster-default applies" partition (not a default composite
    /// the downstream must reject on emptiness) — the accessor
    /// projects the raw `Option<Placement>` slot's presence bit
    /// through the reference-return unchanged. Named `placement()` to
    /// match the storage field's name verbatim and the tatara-lisp
    /// author-surface term (`:placement`) the field's own docstring
    /// already carries.
    #[must_use]
    pub const fn placement(&self) -> Option<&crate::aplicacao::Placement> {
        self.placement.as_ref()
    }

    /// Substrate-canonical per-`Caixa` `:entrada` M3 mesh-slot outer-
    /// composite MESH-COMPOSITION-shaped external-gateway optional-
    /// composite-reference accessor every consumer of the top-level
    /// manifest's per-Aplicacao [`crate::aplicacao::Entrada`] outer-
    /// composite reader keys off — returns the author-declared
    /// `:entrada` typed composite verbatim as an `Option<&Entrada>`
    /// reference over the same backing storage the raw
    /// `self.entrada.as_ref()` field access borrows from, with `None`
    /// naming the "no `:entrada` block authored — this Aplicacao is
    /// cluster-internal, no `Gateway`/`HTTPRoute` fan-out emitted"
    /// partition every downstream caixa-mesh Gateway-API artifact
    /// emitter treats as "emit no gateway-listener + no `HTTPRoute`
    /// backend for this Aplicacao" and the sibling
    /// [`Self::aplicacao_view`] Aplicacao-composition seed forwards
    /// verbatim (unlike the peer `:politicas` / `:placement` arms,
    /// `:entrada` has no cluster-default fold — an omitted `:entrada`
    /// stays `None` on the projected [`crate::AplicacaoSpec`] and the
    /// peer inner [`crate::AplicacaoSpec::entrada`] accessor observes
    /// the same `Option<&Entrada>` presence bit unchanged).
    ///
    /// The outer `:entrada` slot carries the M3 mesh-slot per-
    /// Aplicacao typed external-gateway composite — the load-bearing
    /// container of every how-does-the-outside-world-reach-this-
    /// Aplicacao axis every caixa-mesh `Gateway`/`HTTPRoute` fan-out
    /// emitter fans on (MESH-COMPOSITION §II.5 — the Aplicacao's typed
    /// external-entry composite; §V CSE invariants — "the external
    /// gateway is a first-class typed composite, not a per-Servico
    /// ingress annotation" the per-axis scalars enforce; §III.4 — the
    /// typed hostname + backend-Servico pair the per-cluster Gateway-
    /// API renderer keys off). Every per-`:entrada` axis threads
    /// through a lifted per-slot accessor on the
    /// [`crate::aplicacao::Entrada`] type: the
    /// [`crate::aplicacao::Entrada::host`] Gateway-API `Listener.hostname`
    /// scalar, the [`crate::aplicacao::Entrada::para`] backend-Servico
    /// caixa-name scalar, the [`crate::aplicacao::Entrada::paths`]
    /// per-rule `HTTPPathMatch` list, the [`crate::aplicacao::Entrada::port`]
    /// backend `trigger.service.port` scalar, and the
    /// [`crate::aplicacao::Entrada::resolved_paths`] URL-path fallback
    /// resolver every HTTPRoute-aware renderer consumes. Every
    /// downstream consumer that reaches for an entry axis first passes
    /// through this outer accessor onto the composite and then
    /// dispatches onto the per-axis accessor — the two-level dispatch
    /// means every per-`:entrada` reader now routes through a typed
    /// dispatch on the substrate primitive at both altitudes.
    ///
    /// Composes through [`Self::aplicacao_view`]'s Aplicacao-composition
    /// seed: the Aplicacao-view builder forwards the outer `Option`
    /// arm verbatim (no default fold — `:entrada` is inherently
    /// optional; a cluster-internal Aplicacao has no external gateway
    /// at all, not "an external gateway that defaults to nothing"), so
    /// the peer inner [`crate::AplicacaoSpec::entrada`] (d32111c)
    /// `Option<&Entrada>`-return accessor observes the same presence
    /// bit whether or not the author declared the outer slot. Routing
    /// the presence bit through this accessor keeps the
    /// [`Self::declared_mesh_slots`] M3 kind-coherence enumerator's
    /// `M3_AUTHOR_KEY_ENTRADA` push separate from the inner
    /// [`crate::AplicacaoSpec::validate_entrada`]-gated
    /// hostname/backend/path emission dispatch.
    ///
    /// Prior to this lift the `.entrada` `Option<Entrada>` composite
    /// was accessed inline at two production sites — the
    /// [`Self::aplicacao_view`] Aplicacao-composition seed's
    /// `self.entrada.clone()` traversal head (caixa-core/src/manifest.rs:2182,
    /// which drives the forward onto the peer inner
    /// [`crate::AplicacaoSpec::entrada`] accessor the caixa-mesh
    /// Gateway-API fan-out then observes), and the
    /// [`Self::declared_mesh_slots`] M3 declared-slot-set enumerator's
    /// `self.entrada.is_some()` presence probe (caixa-core/src/manifest.rs:2248,
    /// which drives the `M3_AUTHOR_KEY_ENTRADA` kebab-case author-
    /// label push every [`crate::LayoutError::MeshSlotsOnNonAplicacao`]
    /// kind-coherence gate reads) — two open-coded outer-field
    /// accesses that expressed no compile-time link back to the typed
    /// slot at the [`Caixa`] altitude. A future extension of the
    /// `:entrada` outer axis to a richer author surface (a per-cluster
    /// `:entrada-overrides` slot the operator materializes at admission
    /// time so a cluster-specific hostname can pin the caixa-declared
    /// bound without re-authoring the `caixa.lisp`, a per-tenant
    /// gateway-alias table the M4 `mesh.pleme.io/v1alpha1/Aplicacao`
    /// CR materializer resolves per-CR at admission time, a promotion
    /// of the plain `Option<Entrada>` to a richer
    /// `{public, private, internal}` partition once Cilium-identity-
    /// scoped internal gateways come into typed scope) would have had
    /// to be threaded through both open-coded copies in lockstep or the
    /// Aplicacao-composition seed's forward arm would silently
    /// disagree with the M3 declared-slot enumerator on which external-
    /// gateway composite a given Caixa resolves to — the seed reading
    /// an operator-resolved slot while the enumerator's presence probe
    /// read the raw slot would silently split the build-time gateway-
    /// artifact emission gate from the M3 declared-slot enumerator's
    /// kind-coherence gate, a two-consumer split far from the source
    /// `caixa.lisp` with no field naming the entry-drift root cause.
    /// Lifting the resolution rule to a typed method on the substrate
    /// primitive means every downstream consumer of the caixa's per-
    /// `Caixa` MESH-COMPOSITION external-gateway outer-composite
    /// surface reaches for exactly one typed dispatch — the resolver's
    /// accept-set migrates as a unit on any future axis addition.
    ///
    /// Fifth and final outer top-level [`Caixa`] `Option<&Composite>`-
    /// return composite-reference accessor — closes the outer-`Caixa`
    /// `Option<&Composite>` composite-reference sub-family opened by
    /// [`Self::limits`] (b2bd9d7) / [`Self::behavior`] (35d8b52) on the
    /// M2 Servico-runtime arm and extended onto the M3 mesh-slot arm
    /// by [`Self::politicas`] (5d23d29) / [`Self::placement`] (4fb8074),
    /// folds on the "one typed dispatch on the substrate primitive,
    /// thin projections at each consumer" discipline extended onto the
    /// third and final M3 mesh-slot axis. Peer of the closed inner
    /// mesh-slot outer-composite family the sibling
    /// [`crate::AplicacaoSpec::politicas`] (534dc21) /
    /// [`crate::AplicacaoSpec::placement`] (9abb8f0) /
    /// [`crate::AplicacaoSpec::entrada`] (d32111c) composite-reference
    /// accessor pins already close on the inner
    /// [`crate::AplicacaoSpec`] altitude — this lift closes the mirror
    /// sub-family on the outer top-level [`Caixa`] altitude, so both
    /// altitudes of the outer-composite reference-return discipline
    /// (per-`Caixa` outer-slot presence + per-`AplicacaoSpec` inner-
    /// slot presence) now carry the full five-arm accept-set behind a
    /// typed dispatch on the substrate primitive. Returns
    /// `Option<&Entrada>` (not the owning composite by copy or clone)
    /// because every downstream consumer of the entrada composite
    /// treats it as a read-only per-axis dispatch source — the
    /// reference-view is the narrowest borrow that supports every
    /// present + roadmapped consumer (per-axis accessor dispatch,
    /// serde composite-serialization on the programs.yaml overlay,
    /// presence-probe early return on the "author-omitted `:entrada`
    /// ⇒ cluster-internal Aplicacao" partition, `Aplicacao`-composition
    /// seed's forward arm) without cloning the composite through every
    /// consumer's fast path. The `Option` half of the return-type
    /// preserves the load-bearing "author-omitted `:entrada` ⇒
    /// cluster-internal Aplicacao" partition (not a default composite
    /// the downstream must reject on emptiness — a cluster-internal
    /// Aplicacao has no external gateway at all, not "a default gateway
    /// that emits nothing"); the accessor projects the raw
    /// `Option<Entrada>` slot's presence bit through the reference-
    /// return unchanged. Named `entrada()` to match the storage field's
    /// name verbatim and the tatara-lisp author-surface term
    /// (`:entrada`) the field's own docstring already carries.
    #[must_use]
    pub const fn entrada(&self) -> Option<&crate::aplicacao::Entrada> {
        self.entrada.as_ref()
    }

    /// Substrate-canonical per-`Caixa` `:ci` slot accessor — returns the
    /// author-declared typed CI run (`canteiro_types::CiRun`) verbatim as
    /// an `Option<&CiRun>`, borrowed from the typed slot's own
    /// `Option<CiRun>` storage. `None` when the slot is absent (every
    /// non-`Acao` kind, and an `Acao` caixa that hasn't declared `:ci`
    /// yet — the latter is caught by [`crate::LayoutError::MissingCi`],
    /// not silently accepted).
    ///
    /// Named `ci()` to match the storage field's name and the
    /// tatara-lisp author surface (`:ci`); mirrors the sibling
    /// `Option<&Composite>` accessors on this same `Caixa` altitude
    /// ([`Self::limits`], [`Self::behavior`], [`Self::politicas`],
    /// [`Self::placement`], [`Self::entrada`]) — one typed dispatch on
    /// the substrate primitive rather than an open-coded `self.ci.as_ref()`
    /// at every consumer.
    #[must_use]
    pub const fn ci(&self) -> Option<&canteiro_types::CiRun> {
        self.ci.as_ref()
    }

    /// Substrate-canonical per-`Caixa` `:estrategia` M2 supervisor-tree-
    /// slot flat-spread OTP-shaped sibling-restart-strategy discriminant
    /// accessor every consumer of the top-level manifest's per-Supervisor
    /// restart-strategy axis keys off — returns the author-declared
    /// `:estrategia` variant verbatim as an `Option<RestartStrategy>`,
    /// `Copy`-projected from the typed slot's own
    /// `Option<crate::supervisor::RestartStrategy>` storage. Optional
    /// (`:estrategia` is a flat-spread supervisor-only slot every
    /// non-`Supervisor`-kind `defcaixa` carries as `None` by
    /// `#[serde(default)]`, and every `Supervisor`-kind `defcaixa` may
    /// still omit to defer to [`RestartStrategy::default`] —
    /// [`RestartStrategy::OneForOne`] — through the [`Self::supervisor_view`]
    /// `unwrap_or_default()` fold; a returned `None` degenerates to the
    /// [`SupervisorSpec::default`]-inherited strategy without any silent
    /// promotion to a fresh explicit variant at the accessor boundary).
    ///
    /// The `:estrategia` slot carries the M2 typed OTP-shaped sibling-
    /// restart-strategy discriminant every substrate-side per-Supervisor
    /// dispatch fans on (INSPIRATIONS §II.2 — OTP `supervisor:strategy`
    /// closed-set `one_for_one | one_for_all | rest_for_one |
    /// simple_one_for_one` algebra translated onto pleme-io's typed
    /// [`RestartStrategy`] enum; CAIXA-SDLC §II — the M2 supervisor-tree
    /// slot algebra the operator's hierarchical reconciliation scheduler
    /// fans on). The slot is *flat-spread* on the outer top-level `Caixa`
    /// (per the field-shape docstring at caixa-core/src/manifest.rs — "The
    /// supervisor slots are flat on Caixa (vs nested under a
    /// `SupervisorSpec` sub-form) to keep tatara-lisp authoring at one
    /// level of nesting"), so the accessor's altitude is the outer
    /// [`Caixa`] surface rather than the composed [`SupervisorSpec`]
    /// altitude the sibling [`crate::supervisor::SupervisorSpec::estrategia`]
    /// (eafb619) accessor keys off. The two typed axes — the outer
    /// author-surface `Option<RestartStrategy>` on the [`Caixa`] altitude
    /// (author-omitted arm carried as `None`) and the inner post-
    /// composition `RestartStrategy` on the [`SupervisorSpec`] altitude
    /// (`Option` collapsed through the [`Self::supervisor_view`]
    /// `unwrap_or_default()` fold) — now share one accessor discipline for
    /// the shared substrate concept "the author-declared OTP-shaped
    /// sibling-restart-strategy variant that partitions the downstream
    /// per-Supervisor renderer's per-arm fan-out"; the outer-altitude
    /// `None` arm is the pre-composition presence bit every declared-slot
    /// enumerator ([`Self::declared_supervisor_slots`]) reads, and the
    /// inner-altitude non-`Option` `RestartStrategy` is the post-
    /// composition partition-dispatch input every strategy-arm consumer
    /// ([`SupervisorSpec::validate`], the future wasm-operator's per-
    /// Supervisor sibling-restart branch, the future M4
    /// `mesh.pleme.io/v1alpha1/Supervisor` CR materializer's admission
    /// webhook) fans on.
    ///
    /// Prior to this lift the `.estrategia` field was accessed inline at
    /// two production sites in `caixa-core/src/manifest.rs` — the
    /// [`Self::declared_supervisor_slots`] `SUPERVISOR_AUTHOR_KEY_ESTRATEGIA`
    /// presence-probe arm at `if self.estrategia.is_some()` (which drives
    /// the [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] kind-
    /// coherence gate's per-slot label push) and the [`Self::supervisor_view`]
    /// `SupervisorSpec` construction site at `estrategia:
    /// self.estrategia.unwrap_or_default()` (which composes the flat-
    /// spread outer author-surface `Option<RestartStrategy>` onto the
    /// inner post-composition [`SupervisorSpec`] `RestartStrategy` field
    /// the [`SupervisorSpec::estrategia`] accessor keys off) — two open-
    /// coded field-accesses that expressed no compile-time link back to
    /// the typed slot. A future extension of the outer `:estrategia` axis
    /// to a richer author surface (a per-cluster strategy override the
    /// operator pins through a future `:estrategia-overrides` overlay the
    /// MESH-COMPOSITION §III.2 supervision-canary roadmap acknowledges,
    /// a per-tenant strategy-alias table the M4 CR materializer resolves
    /// per-CR, a per-Supervisor dynamic strategy derivation the future
    /// adaptive-supervision engine computes from child-failure-history
    /// topology, a per-child-cohort strategy split the future
    /// `RestForCohort` extension the INSPIRATIONS.md §II.2 Erlang/OTP
    /// absorption roadmap acknowledges, a promotion of the plain
    /// `Option<RestartStrategy>` to a richer
    /// `AuthorDeclaredStrategy { declared, overlay }` newtype once the
    /// operator-resolved overlay lands) would have had to be threaded
    /// through both open-coded copies in lockstep or the enumerator's
    /// presence probe and the composition site's `unwrap_or_default()`
    /// fold would silently disagree on which strategy a given [`Caixa`]
    /// resolves to (an author's `:estrategia OneForAll` would satisfy
    /// the enumerator's presence probe while the composition site
    /// silently rendered a stale `OneForOne`, or vice versa). Lifting
    /// the resolution rule to a typed method on the substrate primitive
    /// means every downstream consumer of the caixa's per-`Caixa` outer-
    /// altitude sibling-restart-strategy surface reaches for exactly one
    /// typed dispatch — the resolver's accept-set migrates as a unit on
    /// any future axis addition.
    ///
    /// First outer top-level [`Caixa`] `Option<Copy>`-return supervisor-
    /// tree-slot flat-spread accessor for M2 supervisor-slot Copy-carry
    /// axes — opens the outer-`Caixa` `Option<Copy>` flat-spread
    /// projection pattern the sibling per-`Caixa` `:max-restarts`
    /// `Option<u32>` and (through the future duration-newtype landing)
    /// `:restart-window` `Option<Duration>` future outer-scalar lifts
    /// fold on. Peer of the inner-altitude [`crate::supervisor::SupervisorSpec::estrategia`]
    /// (eafb619) `Copy`-return sibling-restart-strategy scalar accessor on
    /// the post-composition [`SupervisorSpec`] altitude — same "one
    /// typed dispatch on the substrate primitive, thin projections at
    /// each consumer" discipline extended onto the pre-composition outer
    /// author-surface [`Caixa`] altitude for the same OTP-shaped
    /// sibling-restart-strategy axis. Peer of the closed outer-`Caixa`
    /// `Option<&Composite>` composite-reference family the sibling
    /// [`Self::limits`] (b2bd9d7) / [`Self::behavior`] (35d8b52) /
    /// [`Self::politicas`] (5d23d29) / [`Self::placement`] (4fb8074) /
    /// [`Self::entrada`] (e4128e4) accessor pins already carry on the
    /// outer `Option<&Composite>` altitude — extends the outer-`Caixa`
    /// typed-slot accessor discipline onto the flat-spread M2 supervisor-
    /// tree `Option<Copy>`-discriminant sub-family the sibling M3
    /// [`crate::aplicacao::Placement::estrategia`] (921fe1b)
    /// `PlacementStrategy` `Copy`-composite-enum scalar accessor already
    /// pins on the inner-altitude per-`:placement` composite. Named
    /// `estrategia()` to match the storage field's name and the
    /// per-[`SupervisorSpec`] peer [`crate::supervisor::SupervisorSpec::estrategia`]
    /// / per-[`crate::aplicacao::Placement`] peer
    /// [`crate::aplicacao::Placement::estrategia`] method-name discipline
    /// verbatim; the accessor's identity name maps onto the canonical
    /// OTP-shape supervision vocabulary the [`RestartStrategy`] enum's
    /// docstring already carries.
    #[must_use]
    pub const fn estrategia(&self) -> Option<crate::supervisor::RestartStrategy> {
        self.estrategia
    }

    /// Substrate-canonical per-`Caixa` `:max-restarts` M2 supervisor-tree-
    /// slot flat-spread OTP-`MaxIntensity`-shaped restart-budget-count
    /// scalar accessor every consumer of the top-level manifest's per-
    /// Supervisor `:max-restarts` restart-budget-count axis keys off —
    /// returns the author-declared `:max-restarts` typed `Option<u32>`
    /// verbatim, `Copy`-projected from the typed slot's own `Option<u32>`
    /// storage (`u32` is `Copy`, so `Option<u32>` is `Copy` and the
    /// accessor returns by value; no borrow of `&self` past the call).
    /// Optional (`:max-restarts` is a flat-spread supervisor-only slot
    /// every non-`Supervisor`-kind `defcaixa` carries as `None` by
    /// `#[serde(default)]`, and every `Supervisor`-kind `defcaixa` may
    /// still omit to defer to the [`Self::supervisor_view`]
    /// `unwrap_or(5)` fold's OTP-canonical `{intensity, 5, 60}` default).
    ///
    /// The `:max-restarts` slot carries the M2 typed Erlang/OTP-shaped
    /// `MaxIntensity` restart-budget count that pairs with the sibling
    /// `:restart-window` `Period` to form the `MaxIntensity / Period`
    /// restart-intensity ratio the supervisor trips its own escalation on
    /// (INSPIRATIONS §II.2 — Erlang/OTP `supervisor` `{intensity, 5, 60}`
    /// worker-supervisor default; RUNTIME-PATTERNS §II.2; CAIXA-SDLC §II
    /// — the M2 supervisor-tree slot algebra the operator's hierarchical
    /// reconciliation scheduler fans on). The slot is *flat-spread* on
    /// the outer top-level `Caixa` (per the field-shape docstring at
    /// caixa-core/src/manifest.rs — "The supervisor slots are flat on
    /// Caixa (vs nested under a `SupervisorSpec` sub-form)"), so the
    /// accessor's altitude is the outer [`Caixa`] surface rather than the
    /// composed [`SupervisorSpec`] altitude the sibling
    /// [`crate::supervisor::SupervisorSpec::max_restarts`] accessor keys
    /// off. The two typed axes — the outer author-surface `Option<u32>`
    /// on the [`Caixa`] altitude (author-omitted arm carried as `None`)
    /// and the inner post-composition `u32` on the [`SupervisorSpec`]
    /// altitude (`Option` collapsed through the [`Self::supervisor_view`]
    /// `unwrap_or(5)` fold) — now share one accessor discipline for the
    /// shared substrate concept "the author-declared OTP-shaped
    /// restart-budget count every downstream per-Supervisor consumer's
    /// restart-intensity budget-vs-count comparator fans on".
    ///
    /// Prior to this lift the `.max_restarts` field was accessed inline
    /// at two production sites in `caixa-core/src/manifest.rs` — the
    /// [`Self::declared_supervisor_slots`] `SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS`
    /// presence-probe arm at `if self.max_restarts.is_some()` (which
    /// drives the [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`]
    /// kind-coherence gate's per-slot label push) and the
    /// [`Self::supervisor_view`] `SupervisorSpec` construction site at
    /// `max_restarts: self.max_restarts.unwrap_or(5)` (which composes the
    /// flat-spread outer author-surface `Option<u32>` onto the inner
    /// post-composition [`SupervisorSpec`] `u32` field the
    /// [`SupervisorSpec::max_restarts`] accessor keys off) — two open-
    /// coded field-accesses that expressed no compile-time link back to
    /// the typed slot. A future extension of the outer `:max-restarts`
    /// axis to a richer author surface (a per-cluster restart-budget
    /// override the operator pins through a future `:max-restarts-overrides`
    /// overlay the MESH-COMPOSITION §III.2 supervision-canary roadmap
    /// acknowledges, a per-tenant restart-budget-alias table the M4 CR
    /// materializer resolves per-CR, a per-Supervisor dynamic restart-
    /// budget derivation the future adaptive-supervision engine computes
    /// from child-failure-history topology, a promotion of the plain
    /// `Option<u32>` count to a richer `{MaxR, MaxT}` per-child-cohort
    /// restart-budget-partition once the INSPIRATIONS §II.2 Erlang/OTP
    /// per-child-cohort roadmap lands) would have had to be threaded
    /// through both open-coded copies in lockstep or the enumerator's
    /// presence probe and the composition site's `unwrap_or(5)` fold
    /// would silently disagree on which restart-budget a given [`Caixa`]
    /// resolves to (an author's `:max-restarts 10` would satisfy the
    /// enumerator's presence probe while the composition site silently
    /// composed the OTP-canonical `5`, or vice versa). Lifting the
    /// resolution rule to a typed method on the substrate primitive means
    /// every downstream consumer of the caixa's per-`Caixa` outer-altitude
    /// restart-budget-count surface reaches for exactly one typed dispatch
    /// — the resolver's accept-set migrates as a unit on any future axis
    /// addition.
    ///
    /// Second outer top-level [`Caixa`] `Option<Copy>`-return supervisor-
    /// tree-slot flat-spread accessor for M2 supervisor-slot Copy-carry
    /// axes — folds on the outer-`Caixa` `Option<Copy>` flat-spread
    /// projection pattern the sibling per-`Caixa`
    /// [`Self::estrategia`] (ed04d3c) accessor opened, extends the
    /// sub-family onto the sibling `Option<u32>` restart-budget-count arm.
    /// Peer of the inner-altitude
    /// [`crate::supervisor::SupervisorSpec::max_restarts`] `u32` accessor
    /// on the post-composition [`SupervisorSpec`] altitude — same "one
    /// typed dispatch on the substrate primitive, thin projections at
    /// each consumer" discipline extended onto the pre-composition outer
    /// author-surface [`Caixa`] altitude for the same OTP-`MaxIntensity`-
    /// shaped restart-budget-count axis. Named `max_restarts()` to match
    /// the storage field's name and the per-[`SupervisorSpec`] peer
    /// [`crate::supervisor::SupervisorSpec::max_restarts`] method-name
    /// discipline verbatim; the accessor's identity maps onto the
    /// canonical OTP-shape supervision vocabulary the `:max-restarts`
    /// field's docstring already carries.
    #[must_use]
    pub const fn max_restarts(&self) -> Option<u32> {
        self.max_restarts
    }

    /// Substrate-canonical per-`Caixa` `:restart-window` M2 supervisor-
    /// tree-slot flat-spread OTP-`Period`-shaped restart-intensity-
    /// denominator raw-duration-string scalar accessor every consumer of
    /// the top-level manifest's per-Supervisor `:restart-window` sliding-
    /// window axis keys off — returns the author-declared `:restart-window`
    /// typed `Option<String>` verbatim as an `Option<&str>`, borrowed
    /// from the typed slot's own `Option<String>` storage. `None` when
    /// the slot is absent (the canonical "never reset — every restart
    /// across the supervisor's lifetime counts against the sibling
    /// `:max-restarts` budget" sentinel every non-`Supervisor`-kind
    /// `defcaixa` carries by `#[serde(default)]` and every
    /// `Supervisor`-kind `defcaixa` may still omit to defer to the
    /// [`Self::supervisor_view`] `restart_window: None` composition
    /// through the [`crate::supervisor::duration_codec::parse`] soft-
    /// swallow `.and_then(|s| … .ok())` fold).
    ///
    /// The `:restart-window` slot carries the raw M2 typed Erlang/OTP-
    /// shaped `Period` sliding-observation-interval duration string that
    /// pairs with the sibling `:max-restarts` `MaxIntensity` restart-
    /// budget count to form the `MaxIntensity / Period` restart-intensity
    /// ratio the supervisor trips its own escalation on (INSPIRATIONS
    /// §II.2 — Erlang/OTP `supervisor` `{intensity, 5, 60}` worker-
    /// supervisor default; RUNTIME-PATTERNS §II.2). The outer-`Caixa`
    /// slot stores the raw duration string (`"60s"`, `"5m"`, `"500ms"`)
    /// authored under `:restart-window` — the typed [`SupervisorSpec`]
    /// holds an `Option<Duration>` routed through the shared
    /// [`crate::supervisor::duration_codec`] via `with = "duration_codec"`
    /// — so the outer altitude's accessor returns `Option<&str>` (raw
    /// authoring surface) while the inner altitude's
    /// [`crate::supervisor::SupervisorSpec::restart_window`] returns
    /// `Option<Duration>` (parsed typed surface). The parse-refusal arm
    /// is closed by the sibling [`Self::validate_restart_window`] gate
    /// that surfaces [`ManifestError::RestartWindowMalformed`] naming
    /// the offending value; the view-construction path
    /// [`Self::supervisor_view`] soft-swallows the same parse error to
    /// `None` to keep the view best-effort.
    ///
    /// Prior to this lift the `.restart_window` field was accessed inline
    /// at three production sites in `caixa-core/src/manifest.rs` — the
    /// [`Self::declared_supervisor_slots`]
    /// `SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW` presence-probe arm at
    /// `if self.restart_window.is_some()` (which drives the
    /// [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] kind-
    /// coherence gate's per-slot label push), the
    /// [`Self::validate_restart_window`] `let Some(s) =
    /// self.restart_window.as_deref()` empty-and-shape gate binding
    /// (which folds the raw string through the shared
    /// [`crate::supervisor::duration_codec::parse`] to surface
    /// [`ManifestError::RestartWindowMalformed`] naming the offending
    /// value), and the [`Self::supervisor_view`] `self.restart_window
    /// .as_deref().and_then(…)` view-construction fold (which composes
    /// the flat-spread outer author-surface `Option<String>` onto the
    /// inner post-composition [`SupervisorSpec`] `Option<Duration>`
    /// field the [`SupervisorSpec::restart_window`] accessor keys off) —
    /// three open-coded field-accesses that expressed no compile-time
    /// link back to the typed slot. A future extension of the outer
    /// `:restart-window` axis to a richer author surface (a per-cluster
    /// window override, a per-tenant window-alias table, a per-Supervisor
    /// dynamic window derivation the future adaptive-supervision engine
    /// computes from child-failure-history topology, a promotion of the
    /// plain `Option<String>` raw duration to a typed `Option<Duration>`
    /// once the future author-surface parser lands at the [`Caixa`]
    /// altitude and the raw-string form is retired) would have had to be
    /// threaded through every open-coded copy in lockstep or the three
    /// consumers would silently disagree on which raw string a given
    /// [`Caixa`] resolves to. Lifting the resolution rule to a typed
    /// method on the substrate primitive means every downstream consumer
    /// of the caixa's per-`Caixa` outer-altitude restart-window raw-
    /// string surface reaches for exactly one typed dispatch — the
    /// resolver's accept-set migrates as a unit on any future axis
    /// addition.
    ///
    /// Third outer top-level [`Caixa`] supervisor-tree-slot flat-spread
    /// accessor — folds on the outer-`Caixa` M2 supervisor-tree flat-
    /// spread projection pattern the sibling per-`Caixa`
    /// [`Self::estrategia`] (ed04d3c) `Option<Copy>` and
    /// [`Self::max_restarts`] `Option<Copy>` accessors opened, extends
    /// the sub-family onto the sibling `Option<&str>` raw-duration-
    /// string arm (the outer altitude's raw-string form; the inner
    /// altitude's parsed [`Duration`] form is the peer
    /// [`crate::supervisor::SupervisorSpec::restart_window`] accessor).
    /// Peer of the sibling per-`Caixa` `Option<&str>`-return scalar
    /// accessors ([`Self::licenca`] / [`Self::repositorio`] /
    /// [`Self::descricao`] / [`Self::edicao`]) on the universal-axis
    /// outer scalar-projection family the outer-`Caixa` `Option<&str>`
    /// sub-family already carries — same "one typed dispatch on the
    /// substrate primitive, thin projections at each consumer"
    /// discipline extended onto the M2 supervisor-tree flat-spread
    /// `Option<&str>` raw-duration-string arm. Named `restart_window()`
    /// to match the storage field's name and the per-[`SupervisorSpec`]
    /// peer [`crate::supervisor::SupervisorSpec::restart_window`]
    /// method-name discipline verbatim; the accessor's identity maps
    /// onto the canonical OTP-shape supervision vocabulary the
    /// `:restart-window` field's docstring already carries.
    #[must_use]
    pub const fn restart_window(&self) -> Option<&str> {
        match &self.restart_window {
            Some(s) => Some(s.as_str()),
            None => None,
        }
    }

    /// Substrate-canonical per-`Caixa` `:upgrade-from` M2 typed-slot
    /// outer-composite OTP-appup-shaped per-prior-version migration-
    /// entry-list slice accessor every consumer of the top-level
    /// manifest's per-Servico hot-upgrade-block `&[UpgradeFromEntry]`
    /// slice-view keys off — returns the author-declared `:upgrade-from`
    /// typed `Vec<UpgradeFromEntry>` verbatim as a
    /// `&[UpgradeFromEntry]` slice-view over the same backing buffer
    /// the raw `self.upgrade_from.as_slice()` field access borrows
    /// from. Empty-slice-carrying (the "no hot-upgrade path declared"
    /// arm every `defcaixa` without an `:upgrade-from` block carries;
    /// the [`Self::from_lisp`] derive folds an omitted `:upgrade-from`
    /// through `#[serde(default)]` to `Vec::new()`, so a `Caixa` past
    /// parse definitionally carries a `Vec<UpgradeFromEntry>` slot —
    /// possibly empty — and the returned `&[UpgradeFromEntry]`
    /// degenerates to an empty slice on that arm without any silent
    /// `None` collapse).
    ///
    /// The outer `:upgrade-from` slot carries the M2 typed OTP-appup
    /// migration block — the load-bearing container of every per-
    /// prior-`:versao` migration-instruction list the wasm-operator
    /// dispatches on at hot-upgrade time (INSPIRATIONS §II.4 — OTP
    /// `.appup` per-prior-version `LoadModule | StateChange |
    /// SoftPurge | Purge | Restart` instruction algebra translated
    /// onto pleme-io's typed `:upgrade-from :from` + `:instructions`
    /// entry list; CAIXA-SDLC §II — the typed-M2 slot algebra the
    /// operator's hot-upgrade dispatch fans on). Every per-entry axis
    /// threads through a lifted per-entry accessor on the
    /// [`UpgradeFromEntry`] type: the
    /// [`UpgradeFromEntry::prior_versao`] SemVer-shaped previous-
    /// version scalar accessor and the
    /// [`UpgradeFromEntry::instructions`] `&[UpgradeInstruction]`-
    /// return per-entry instruction-list accessor (0137e5a). Every
    /// downstream consumer of the hot-upgrade path first passes
    /// through this outer accessor onto the slice and then dispatches
    /// per-entry through the inner accessors — the two-level dispatch
    /// means every per-`:upgrade-from` reader now routes through a
    /// typed dispatch on the substrate primitive at both altitudes.
    ///
    /// Prior to this lift the `.upgrade_from` `Vec<UpgradeFromEntry>`
    /// slot was accessed inline at production sites across three
    /// files — the [`Self::declared_servico_slots`] M2 declared-slot
    /// enumerator's `self.upgrade_from.is_empty()` presence probe
    /// (caixa-core/src/manifest.rs, which drives the
    /// `M2_AUTHOR_KEY_UPGRADE_FROM` kebab-case author-label push every
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] kind-coherence
    /// gate reads), the [`crate::StandardLayout::verify`] per-
    /// `:upgrade-from` three-stage validation pass (caixa-core/src/
    /// layout.rs, which fans onto the
    /// [`crate::upgrade::validate_upgrade_from`] per-entry shape +
    /// cross-entry duplicate gate, the
    /// [`crate::upgrade::validate_upgrade_from_against_versao`]
    /// SemVer-precedence cross-slot gate, the
    /// [`crate::upgrade::validate_upgrade_from_against_behavior`]
    /// `:state-change` ↔ `:on-state-change` cross-slot composition
    /// gate, and the per-instruction script-path existence-probe walk
    /// that reads each entry's [`UpgradeFromEntry::instructions`] to
    /// resolve every declared migration script against the layout
    /// root), and the [`crate::render::servico_m2_overlay`] per-
    /// Servico M2 overlay emitter's `!caixa.upgrade_from.is_empty()`
    /// presence gate + `serde_yaml::to_value(&caixa.upgrade_from)`
    /// projection (caixa-core/src/render.rs, which drives the
    /// `M2_KEY_UPGRADE_FROM`-keyed `serde_yaml` projection every
    /// `caixa-helm` / `caixa-flux` Servico values-block emitter fans
    /// on and lands as the ComputeUnit CR's `spec.upgradeFrom` field).
    /// A future extension of the outer `:upgrade-from` axis (a per-
    /// cluster `:upgrade-overrides` overlay the wasm-engine operator
    /// resolves at admission time so a cluster-specific migration
    /// policy can tighten a caixa-declared step without re-authoring
    /// the `caixa.lisp`, promotion of the plain
    /// `Vec<UpgradeFromEntry>` to a richer `{static, dynamic}`
    /// partition once runtime-resolved hot-upgrade instructions land,
    /// per-entry priority annotation once multi-strategy fan-out
    /// lands) would have had to be threaded through all six open-
    /// coded copies in lockstep or one consumer would silently
    /// disagree with the peers on which upgrade slice a given Caixa
    /// resolves to — a six-consumer split at the enumerator, the
    /// three-stage validate pass, the script-path probe walk, and the
    /// M2 overlay emitter, far from the source `caixa.lisp` with no
    /// field naming the upgrade-drift root cause. Lifting the
    /// resolution rule to a typed method on the substrate primitive
    /// means every downstream consumer of the caixa's per-`Caixa`
    /// OTP-appup outer-slice surface reaches for exactly one typed
    /// dispatch — the resolver's accept-set migrates as a unit on any
    /// future axis addition.
    ///
    /// First outer top-level [`Caixa`] `&[Composite]`-return slice
    /// accessor for M2 / M3 typed-slot vec-carry axes — opens the
    /// outer-`Caixa` `&[Composite]` composite-slice projection
    /// pattern the sibling `:children`
    /// [`crate::supervisor::ChildSpec`] / `:membros`
    /// [`crate::aplicacao::Membro`] / `:contratos`
    /// [`crate::aplicacao::WitContract`] future outer-composite-slice
    /// lifts fold on. Peer of the closed outer-`Caixa` scalar
    /// `Option<&Composite>` composite-reference family the sibling
    /// [`Self::limits`] (b2bd9d7) / [`Self::behavior`] (35d8b52) /
    /// [`Self::politicas`] (5d23d29) / [`Self::placement`] (4fb8074) /
    /// [`Self::entrada`] (e4128e4) accessors closed on the outer
    /// `Option<&Composite>` altitude, extended here to the outer-
    /// `Caixa` `&[Composite]` vec-carry altitude. Peer at the inner
    /// altitude of [`crate::upgrade::UpgradeFromEntry::instructions`]
    /// (0137e5a) — same "one typed dispatch on the substrate
    /// primitive, thin projections at each consumer" discipline
    /// folded onto the outer top-level [`Caixa`] altitude, opening the
    /// M2 vec-carry slot family's outer-composite-slice axis. Sibling
    /// in shape to the peer outer-`Caixa` `&[Dep]`-return
    /// [`Self::deps`] (ad34b4e) / [`Self::deps_dev`] (f7fd81e) and
    /// `&[String]`-return [`Self::autores`] (b5d813f) /
    /// [`Self::etiquetas`] (78c7d3c) / [`Self::bibliotecas`]
    /// (8a36c23) / [`Self::exe`] (65d9527) / [`Self::servicos`]
    /// (611f78b) slice-accessors on the sibling outer-`Caixa` scalar-
    /// element vec-carry axes — folds the "outer [`Caixa`] `&[T]`
    /// slice" projection pattern onto the sibling M2 typed-composite-
    /// element axis (`UpgradeFromEntry` composite, matching the
    /// per-inner [`UpgradeFromEntry::instructions`] element type at a
    /// different altitude).
    ///
    /// Returns `&[UpgradeFromEntry]` (not `&Vec<UpgradeFromEntry>`)
    /// because every downstream consumer of the hot-upgrade list
    /// treats it as a read-only sequence — the slice-view is the
    /// narrowest borrow that supports every present + roadmapped
    /// consumer (`.iter()`, `.len()`, `.is_empty()`, `serde` slice-
    /// serialization through
    /// `serde_yaml::to_value(&[UpgradeFromEntry])`) without leaking
    /// the backing `Vec`'s grow/push/reserve surface no consumer of
    /// the typed view reaches for (the storage-side `Vec` remains
    /// reachable through the `pub upgrade_from` field for the
    /// mutation-carrying serde round-trip and per-test fixture-
    /// mutation paths). Named `upgrade_from()` to match the storage
    /// field's `snake_case` name; the kebab-case author-surface tag
    /// `:upgrade-from` is the same axis after tatara-lisp's
    /// kebab↔snake fold and the accessor's identity maps onto the
    /// canonical CAIXA-SDLC §II vocabulary the slot's docstring
    /// already carries.
    #[must_use]
    pub const fn upgrade_from(&self) -> &[UpgradeFromEntry] {
        self.upgrade_from.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:children` M2 supervisor-tree-
    /// slot outer-composite OTP-shaped per-supervisor static-child-list
    /// slice accessor every consumer of the top-level manifest's per-
    /// Supervisor `&[ChildSpec]` slice-view keys off — returns the
    /// author-declared `:children` typed `Vec<crate::supervisor::ChildSpec>`
    /// verbatim as a `&[crate::supervisor::ChildSpec]` slice-view over
    /// the same backing buffer the raw `self.children.as_slice()` field
    /// access borrows from. Empty-slice-carrying (the "no static children
    /// declared" arm every non-`Supervisor`-kind `defcaixa` carries by
    /// #[serde(default)] and every `SimpleOneForOne` supervisor carries
    /// by [`crate::supervisor::SupervisorError::SimpleOneForOneWithStaticChildren`]
    /// gate; the returned `&[ChildSpec]` degenerates to an empty slice
    /// on those arms without any silent `None` collapse).
    ///
    /// The outer `:children` slot carries the M2 typed OTP-supervisor
    /// static-child list — the load-bearing container of every per-
    /// child `{caixa, versao, restart}` triple the wasm-operator's
    /// hierarchical reconciler dispatches on at supervisor-tree
    /// materialization time (INSPIRATIONS §II.2 — OTP `supervisor:init/1`
    /// static-child list translated onto pleme-io's typed
    /// [`crate::supervisor::ChildSpec`] entry list; CAIXA-SDLC §II —
    /// the typed-M2 slot algebra the operator's per-supervisor fan-out
    /// dispatch fans on). Every per-child axis threads through a lifted
    /// per-entry accessor on the [`crate::supervisor::ChildSpec`] type:
    /// the [`crate::supervisor::ChildSpec::nome`] DNS-1123-label
    /// child-caixa-identity scalar accessor, the peer versao SemVer-2
    /// version-requirement scalar accessor, and the
    /// [`crate::supervisor::ChildSpec::restart`] `Copy`-composite-enum
    /// per-child post-exit restart-decision-policy discriminant
    /// accessor (dfb4a81). Every downstream consumer of the supervisor-
    /// tree path first passes through this outer accessor onto the
    /// slice and then dispatches per-child through the inner accessors
    /// — the two-level dispatch means every per-`:children` reader now
    /// routes through a typed dispatch on the substrate primitive at
    /// both altitudes.
    ///
    /// Prior to this lift the `.children` `Vec<ChildSpec>` slot was
    /// accessed inline at three production sites across two files —
    /// the [`Self::declared_supervisor_slots`] supervisor-tree
    /// declared-slot enumerator's `!self.children.is_empty()` presence
    /// probe (caixa-core/src/manifest.rs, which drives the
    /// `SUPERVISOR_AUTHOR_KEY_CHILDREN` kebab-case author-label push
    /// every [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`]
    /// kind-coherence gate reads), the [`Self::supervisor_view`]
    /// per-supervisor typed-view composer's `self.children.clone()`
    /// per-child fold-in path (caixa-core/src/manifest.rs, which
    /// materializes the typed [`crate::supervisor::SupervisorSpec`]
    /// view every [`crate::StandardLayout::verify`] Supervisor-arm gate
    /// dispatches on), and the [`crate::StandardLayout::verify`] per-
    /// `:children :caixa` self-parent refusal probe's
    /// `&caixa.children`-borrowed
    /// [`crate::supervisor::validate_no_self_supervision`] input
    /// (caixa-core/src/layout.rs, which pins the "no child names the
    /// supervisor's own `:nome`" cross-slot coherence gate). A future
    /// extension of the outer `:children` axis (a per-cluster
    /// `:children-overrides` overlay the wasm-engine operator resolves
    /// at admission time so a cluster-specific child-set can tighten
    /// a caixa-declared list without re-authoring the `caixa.lisp`,
    /// promotion of the plain `Vec<ChildSpec>` to a richer
    /// `{static, dynamic}` partition once Erlang/OTP's
    /// `simple_one_for_one`-shaped dynamic-child slot lands as a typed
    /// axis, per-child priority annotation once multi-strategy fan-out
    /// lands) would have had to be threaded through all three open-
    /// coded copies in lockstep or one consumer would silently
    /// disagree with the peers on which child slice a given Caixa
    /// resolves to — the enumerator's presence probe reading the raw
    /// slot while the peer view-composer's fold-in path read an
    /// operator-resolved slot would silently split the paired
    /// declared-slot enumerator and typed-view composition, and the
    /// [`crate::supervisor::validate_no_self_supervision`] self-parent
    /// refusal probe reading a third borrow would silently drift the
    /// cross-slot coherence gate's traversal input from the two peers,
    /// a three-consumer split at the enumerator, the view composer,
    /// and the self-parent gate far from the source `caixa.lisp` with
    /// no field naming the child-set-drift root cause. Lifting the
    /// resolution rule to a typed method on the substrate primitive
    /// means every downstream consumer of the caixa's per-`Caixa`
    /// OTP-supervisor outer-slice surface reaches for exactly one
    /// typed dispatch — the resolver's accept-set migrates as a unit
    /// on any future axis addition.
    ///
    /// Second outer top-level [`Caixa`] `&[Composite]`-return slice
    /// accessor for M2 / M3 typed-slot vec-carry axes — folds on the
    /// outer-`Caixa` `&[Composite]` composite-slice sub-family the
    /// sibling [`Self::upgrade_from`] (2a1f907) accessor opened, peer
    /// at the outer altitude of the closed inner-`SupervisorSpec`
    /// [`crate::SupervisorSpec::children`] (bc92bce) accessor on the
    /// same OTP-supervisor static-child-list axis — same "byte-equal,
    /// borrow-shared" outer-accessor discipline extended onto the
    /// second outer-`Caixa` `&[Composite]` vec-carry axis. Sibling in
    /// shape to the peer outer-`Caixa` `&[Dep]`-return [`Self::deps`]
    /// (ad34b4e) / [`Self::deps_dev`] (f7fd81e) and `&[String]`-return
    /// [`Self::autores`] (b5d813f) / [`Self::etiquetas`] (78c7d3c) /
    /// [`Self::bibliotecas`] (8a36c23) / [`Self::exe`] (65d9527) /
    /// [`Self::servicos`] (611f78b) slice-accessors on the sibling
    /// outer-`Caixa` scalar-element vec-carry axes — folds the "outer
    /// [`Caixa`] `&[T]` slice" projection pattern onto the sibling
    /// M2 typed-composite-element axis
    /// ([`crate::supervisor::ChildSpec`] composite, matching the
    /// per-inner [`crate::SupervisorSpec::children`] element type at a
    /// different altitude).
    ///
    /// Returns `&[crate::supervisor::ChildSpec]` (not
    /// `&Vec<ChildSpec>`) because every downstream consumer of the
    /// child list treats it as a read-only sequence — the slice-view
    /// is the narrowest borrow that supports every present +
    /// roadmapped consumer (`.iter()`, `.len()`, `.is_empty()`, the
    /// [`crate::supervisor::validate_no_self_supervision`] `&[ChildSpec]`
    /// input, `serde` slice-serialization) without leaking the backing
    /// `Vec`'s grow/push/reserve surface no consumer of the typed view
    /// reaches for (the storage-side `Vec` remains reachable through
    /// the `pub children` field for the mutation-carrying serde round-
    /// trip and per-test fixture-mutation paths, including the
    /// [`Self::supervisor_view`] fold-in path that clones the slot
    /// into the typed view). Named `children()` to match the storage
    /// field's name verbatim and the tatara-lisp author-surface term
    /// (`:children`) the field's own docstring already carries; the
    /// accessor's identity maps onto the canonical OTP supervision
    /// vocabulary the [`Caixa::children`] field's docstring already
    /// reaches for ("Static children of a supervisor").
    #[must_use]
    pub const fn children(&self) -> &[crate::supervisor::ChildSpec] {
        self.children.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:membros` M3 mesh-slot outer-
    /// composite MESH-COMPOSITION-shaped per-Aplicacao member-list slice
    /// accessor every consumer of the top-level manifest's per-Aplicacao
    /// `&[crate::aplicacao::Membro]` slice-view keys off — returns the
    /// author-declared `:membros` typed `Vec<crate::aplicacao::Membro>`
    /// verbatim as a `&[crate::aplicacao::Membro]` slice-view over the
    /// same backing buffer the raw `self.membros.as_slice()` field access
    /// borrows from. Empty-slice-carrying (the "no members declared" arm
    /// every non-`Aplicacao`-kind `defcaixa` carries by `#[serde(default)]`
    /// and every partially-authored Aplicacao carries before the
    /// [`crate::AplicacaoError::MembrosEmpty`] gate fires; the returned
    /// `&[Membro]` degenerates to an empty slice on those arms without any
    /// silent `None` collapse).
    ///
    /// The outer `:membros` slot carries the M3 typed MESH-COMPOSITION
    /// per-Aplicacao member list — the load-bearing container of every
    /// per-member `{caixa, versao}` pair the caixa-mesh renderer's
    /// per-Aplicacao program-emission dispatch fans on at mesh-artifact
    /// materialization time (MESH-COMPOSITION §III.1 — the typed graph's
    /// vertex set the `:contratos` `:de`/`:para` edges resolve against and
    /// the `:entrada :para` external-gateway destination validates
    /// against; CAIXA-SDLC §II — the typed-M3 slot algebra the operator's
    /// per-Aplicacao fan-out dispatch fans on). Every per-member axis
    /// threads through a lifted per-entry accessor on the
    /// [`crate::aplicacao::Membro`] type: the
    /// [`crate::aplicacao::Membro::nome`] DNS-1123-label member-caixa-
    /// identity scalar accessor (4a32abf) and the peer
    /// [`crate::aplicacao::Membro::versao_requirement`] SemVer-2
    /// version-requirement scalar accessor (a40b0e3). Every downstream
    /// consumer of the mesh-graph path first passes through this outer
    /// accessor onto the slice and then dispatches per-member through
    /// the inner accessors — the two-level dispatch means every per-
    /// `:membros` reader now routes through a typed dispatch on the
    /// substrate primitive at both altitudes.
    ///
    /// Prior to this lift the `.membros` `Vec<Membro>` slot was accessed
    /// inline at three production sites across two files — the
    /// [`Self::declared_mesh_slots`] mesh-slot declared-slot
    /// enumerator's `!self.membros.is_empty()` presence probe
    /// (caixa-core/src/manifest.rs, which drives the
    /// `M3_AUTHOR_KEY_MEMBROS` kebab-case author-label push every
    /// [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-coherence
    /// gate reads), the [`Self::aplicacao_view`] per-Aplicacao typed-view
    /// composer's `self.membros.clone()` per-member fold-in path
    /// (caixa-core/src/manifest.rs, which materializes the typed
    /// [`crate::aplicacao::AplicacaoSpec`] view every
    /// [`crate::StandardLayout::verify`] Aplicacao-arm gate dispatches
    /// on), and the [`crate::StandardLayout::verify`] per-`:membros
    /// :caixa` self-membership refusal probe's `&caixa.membros`-borrowed
    /// [`crate::aplicacao::validate_no_self_membership`] input
    /// (caixa-core/src/layout.rs, which pins the "no member names the
    /// Aplicacao's own `:nome`" cross-slot coherence gate). A future
    /// extension of the outer `:membros` axis (a per-cluster
    /// `:membros-overrides` overlay the wasm-engine operator resolves at
    /// admission time so a cluster-specific member-set can tighten a
    /// caixa-declared list without re-authoring the `caixa.lisp`,
    /// promotion of the plain `Vec<Membro>` to a richer
    /// `{static, dynamic}` partition once runtime-resolved Aplicacao
    /// members land as a typed axis, per-member priority annotation once
    /// multi-strategy fan-out lands) would have had to be threaded
    /// through all three open-coded copies in lockstep or one consumer
    /// would silently disagree with the peers on which member slice a
    /// given Caixa resolves to — the enumerator's presence probe reading
    /// the raw slot while the peer view-composer's fold-in path read an
    /// operator-resolved slot would silently split the paired
    /// declared-slot enumerator and typed-view composition, and the
    /// [`crate::aplicacao::validate_no_self_membership`] self-membership
    /// refusal probe reading a third borrow would silently drift the
    /// cross-slot coherence gate's traversal input from the two peers, a
    /// three-consumer split at the enumerator, the view composer, and
    /// the self-membership gate far from the source `caixa.lisp` with no
    /// field naming the member-set-drift root cause. Lifting the
    /// resolution rule to a typed method on the substrate primitive
    /// means every downstream consumer of the caixa's per-`Caixa`
    /// MESH-COMPOSITION outer-slice surface reaches for exactly one
    /// typed dispatch — the resolver's accept-set migrates as a unit on
    /// any future axis addition.
    ///
    /// Third outer top-level [`Caixa`] `&[Composite]`-return slice
    /// accessor for M2 / M3 typed-slot vec-carry axes — opens the outer-
    /// `Caixa` M3 mesh-slot arm of the `&[Composite]` composite-slice
    /// sub-family the sibling M2 [`Self::upgrade_from`] (2a1f907) /
    /// [`Self::children`] (c17b51e) accessors opened for the M2 vec-carry
    /// altitude. Peer at the outer altitude of the closed inner-
    /// [`crate::AplicacaoSpec::membros`] (6c77e36) accessor on the same
    /// MESH-COMPOSITION per-Aplicacao member-list axis — the two
    /// altitudes now share the same "byte-equal, borrow-shared" outer-
    /// accessor discipline. Sibling in shape to the peer outer-`Caixa`
    /// `&[Dep]`-return [`Self::deps`] (ad34b4e) / [`Self::deps_dev`]
    /// (f7fd81e) and `&[String]`-return [`Self::autores`] (b5d813f) /
    /// [`Self::etiquetas`] (78c7d3c) / [`Self::bibliotecas`] (8a36c23) /
    /// [`Self::exe`] (65d9527) / [`Self::servicos`] (611f78b) slice-
    /// accessors on the sibling outer-`Caixa` scalar-element vec-carry
    /// axes — folds the "outer [`Caixa`] `&[T]` slice" projection
    /// pattern onto the sibling M3 typed-composite-element axis
    /// ([`crate::aplicacao::Membro`] composite, matching the per-inner
    /// [`crate::AplicacaoSpec::membros`] element type at a different
    /// altitude).
    ///
    /// Returns `&[crate::aplicacao::Membro]` (not `&Vec<Membro>`)
    /// because every downstream consumer of the member list treats it
    /// as a read-only sequence — the slice-view is the narrowest borrow
    /// that supports every present + roadmapped consumer (`.iter()`,
    /// `.len()`, `.is_empty()`, the
    /// [`crate::aplicacao::validate_no_self_membership`] `&[Membro]`
    /// input, `serde` slice-serialization) without leaking the backing
    /// `Vec`'s grow/push/reserve surface no consumer of the typed view
    /// reaches for (the storage-side `Vec` remains reachable through the
    /// `pub membros` field for the mutation-carrying serde round-trip
    /// and per-test fixture-mutation paths, including the
    /// [`Self::aplicacao_view`] fold-in path that clones the slot into
    /// the typed view). Named `membros()` to match the storage field's
    /// name verbatim and the tatara-lisp author-surface term
    /// (`:membros`) the field's own docstring already carries; the
    /// accessor's identity maps onto the canonical MESH-COMPOSITION
    /// vocabulary the [`Caixa::membros`] field's docstring already
    /// reaches for ("Member Servicos that make up this Aplicacao").
    #[must_use]
    pub const fn membros(&self) -> &[crate::aplicacao::Membro] {
        self.membros.as_slice()
    }

    /// Substrate-canonical per-`Caixa` `:contratos` M3 mesh-slot outer-
    /// composite MESH-COMPOSITION-shaped per-Aplicacao WIT-typed
    /// inter-Servico contract-list slice accessor every consumer of the
    /// top-level manifest's per-Aplicacao `&[crate::aplicacao::WitContract]`
    /// slice-view keys off — returns the author-declared `:contratos`
    /// typed `Vec<crate::aplicacao::WitContract>` verbatim as a
    /// `&[crate::aplicacao::WitContract]` slice-view over the same
    /// backing buffer the raw `self.contratos.as_slice()` field access
    /// borrows from. Empty-slice-carrying (the "no contracts declared"
    /// arm every non-`Aplicacao`-kind `defcaixa` carries by
    /// `#[serde(default)]` and every leaf Aplicacao carrying only a
    /// single member with no inter-Servico edge carries; the returned
    /// `&[WitContract]` degenerates to an empty slice on those arms
    /// without any silent `None` collapse).
    ///
    /// The outer `:contratos` slot carries the M3 typed MESH-COMPOSITION
    /// per-Aplicacao WIT-typed inter-Servico edge list — the load-bearing
    /// container of every per-edge `{de, para, wit, endpoint | subject |
    /// slot}` quadruple the caixa-mesh renderer's per-Aplicacao
    /// `CiliumNetworkPolicy` fan-out (one L7 policy per edge —
    /// MESH-COMPOSITION §III.2 point 2) and per-`(:de, :para)`
    /// adjacency-list seed dispatch on at mesh-artifact materialization
    /// time (MESH-COMPOSITION §III.1 — the typed graph's edge set the
    /// `:membros` vertex set resolves against, closed by the
    /// [`crate::AplicacaoError::ContractoUnknownMember`] / cycle-refusal
    /// gates in §III.3; CAIXA-SDLC §II — the typed-M3 slot algebra the
    /// operator's per-Aplicacao fan-out dispatch fans on). Every
    /// per-edge axis threads through a lifted per-entry accessor on the
    /// [`crate::aplicacao::WitContract`] type: the peer `de` / `para`
    /// DNS-1123-label member-caixa-name endpoint scalar accessors, the
    /// [`crate::aplicacao::WitContract::endpoint`] (7020470) HTTP-shape
    /// / [`crate::aplicacao::WitContract::subject`] (90de675)
    /// NATS-pub-sub-shape / [`crate::aplicacao::WitContract::slot`]
    /// (ed22b66) `wasi:keyvalue/store`-shape payload-carrier accessors,
    /// and the WIT-world discriminant. Every downstream consumer of the
    /// mesh-graph edge path first passes through this outer accessor
    /// onto the slice and then dispatches per-contract through the
    /// inner accessors — the two-level dispatch means every
    /// per-`:contratos` reader now routes through a typed dispatch on
    /// the substrate primitive at both altitudes.
    ///
    /// Prior to this lift the `.contratos` `Vec<WitContract>` slot was
    /// accessed inline at two production sites in
    /// caixa-core/src/manifest.rs — the [`Self::declared_mesh_slots`]
    /// mesh-slot declared-slot enumerator's
    /// `!self.contratos.is_empty()` presence probe (which drives the
    /// `M3_AUTHOR_KEY_CONTRATOS` kebab-case author-label push every
    /// [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-coherence
    /// gate reads) and the [`Self::aplicacao_view`] per-Aplicacao
    /// typed-view composer's `self.contratos.clone()` per-contract
    /// fold-in path (which materializes the typed
    /// [`crate::aplicacao::AplicacaoSpec`] view every
    /// [`crate::StandardLayout::verify`] Aplicacao-arm gate and every
    /// downstream `caixa-mesh` renderer dispatches on). A future
    /// extension of the outer `:contratos` axis (a per-cluster
    /// `:contratos-overrides` overlay the wasm-engine operator resolves
    /// at admission time so a cluster-specific edge-set can tighten a
    /// caixa-declared list without re-authoring the `caixa.lisp`,
    /// promotion of the plain `Vec<WitContract>` to a richer
    /// `{static, dynamic}` partition once runtime-resolved contract
    /// edges land, per-edge policy annotation once the M4 per-edge
    /// policy overlay axis lands) would have had to be threaded through
    /// both open-coded copies in lockstep or one consumer would
    /// silently disagree with the peer on which edge slice a given
    /// Caixa resolves to — the enumerator's presence probe reading the
    /// raw slot while the peer view-composer's fold-in path read an
    /// operator-resolved slot would silently split the paired
    /// declared-slot enumerator and typed-view composition, a
    /// two-consumer split at the enumerator and the view composer far
    /// from the source `caixa.lisp` with no field naming the edge-set-
    /// drift root cause. Lifting the resolution rule to a typed method
    /// on the substrate primitive means every downstream consumer of
    /// the caixa's per-`Caixa` MESH-COMPOSITION outer-slice surface
    /// reaches for exactly one typed dispatch — the resolver's
    /// accept-set migrates as a unit on any future axis addition.
    ///
    /// Fourth and final outer top-level [`Caixa`] `&[Composite]`-return
    /// slice accessor for M2 / M3 typed-slot vec-carry axes — closes
    /// the outer-`Caixa` `&[Composite]` composite-slice sub-family the
    /// sibling M2 [`Self::upgrade_from`] (2a1f907) / [`Self::children`]
    /// (c17b51e) accessors opened and the M3 [`Self::membros`]
    /// (0f26987) accessor folded on, and closes the outer-`Caixa` M3
    /// mesh-slot arm of the composite-slice sub-family the sibling
    /// [`Self::membros`] accessor opened for the M3 vec-carry altitude.
    /// Peer at the outer altitude of the closed inner-
    /// [`crate::AplicacaoSpec::contratos`] (0dcc926) accessor on the
    /// same MESH-COMPOSITION per-Aplicacao contract-list axis — the two
    /// altitudes now share the same "byte-equal, borrow-shared" outer-
    /// accessor discipline. Sibling in shape to the peer outer-`Caixa`
    /// `&[Dep]`-return [`Self::deps`] (ad34b4e) / [`Self::deps_dev`]
    /// (f7fd81e) and `&[String]`-return [`Self::autores`] (b5d813f) /
    /// [`Self::etiquetas`] (78c7d3c) / [`Self::bibliotecas`] (8a36c23) /
    /// [`Self::exe`] (65d9527) / [`Self::servicos`] (611f78b) slice-
    /// accessors on the sibling outer-`Caixa` scalar-element vec-carry
    /// axes — folds the "outer [`Caixa`] `&[T]` slice" projection
    /// pattern onto the sibling M3 typed-composite-element axis
    /// ([`crate::aplicacao::WitContract`] composite, matching the
    /// per-inner [`crate::AplicacaoSpec::contratos`] element type at a
    /// different altitude).
    ///
    /// Returns `&[crate::aplicacao::WitContract]` (not
    /// `&Vec<WitContract>`) because every downstream consumer of the
    /// contract list treats it as a read-only sequence — the slice-view
    /// is the narrowest borrow that supports every present + roadmapped
    /// consumer (`.iter()`, `.len()`, `.is_empty()`, per-edge WIT-world
    /// discriminant dispatch, `serde` slice-serialization) without
    /// leaking the backing `Vec`'s grow/push/reserve surface no
    /// consumer of the typed view reaches for (the storage-side `Vec`
    /// remains reachable through the `pub contratos` field for the
    /// mutation-carrying serde round-trip and per-test fixture-mutation
    /// paths, including the [`Self::aplicacao_view`] fold-in path that
    /// clones the slot into the typed view). Named `contratos()` to
    /// match the storage field's name verbatim and the tatara-lisp
    /// author-surface term (`:contratos`) the field's own docstring
    /// already carries; the accessor's identity maps onto the canonical
    /// MESH-COMPOSITION vocabulary the [`Caixa::contratos`] field's
    /// docstring already reaches for ("WIT-typed inter-Servico
    /// contracts").
    #[must_use]
    pub const fn contratos(&self) -> &[crate::aplicacao::WitContract] {
        self.contratos.as_slice()
    }

    /// Compose the Aplicacao-related flat slots into a single typed
    /// [`crate::aplicacao::AplicacaoSpec`] for validation +
    /// downstream renderer consumption. Returns `None` when the
    /// caixa isn't a `:kind Aplicacao`.
    #[must_use]
    pub fn aplicacao_view(&self) -> Option<crate::aplicacao::AplicacaoSpec> {
        if !self.kind().is_aplicacao() {
            return None;
        }
        Some(crate::aplicacao::AplicacaoSpec {
            membros: self.membros().to_vec(),
            contratos: self.contratos().to_vec(),
            politicas: self.politicas().cloned().unwrap_or_default(),
            placement: self.placement().cloned().unwrap_or_default(),
            entrada: self.entrada().cloned(),
        })
    }

    /// The kebab-case `:slot` tags of every M3 mesh slot this caixa
    /// *declares* a value on, in canonical declaration order
    /// (`:membros` → `:contratos` → `:politicas` → `:placement` →
    /// `:entrada`). A slot counts as declared when its backing field
    /// carries a value — a non-empty `Vec`, or a `Some(...)`.
    ///
    /// The M3 mesh slots compose the typed graph of a `:kind Aplicacao`
    /// (MESH-COMPOSITION §III.1). [`Self::aplicacao_view`] only folds
    /// them into a validatable [`crate::aplicacao::AplicacaoSpec`] when
    /// the kind matches (returns `None` otherwise), and the caixa-mesh /
    /// caixa-flux / caixa-helm renderers only emit them for an
    /// Aplicacao. On any *other* kind a declared mesh slot is the
    /// manifest field's documented "ignored otherwise" (see the
    /// `:membros` … `:entrada` field docs): it silently passes
    /// [`Caixa::from_lisp`] and then vanishes — never validated, never
    /// rendered — far from the source caixa.lisp.
    /// [`crate::StandardLayout::verify`] consults this to reject that
    /// silent-drop at caixa-build time
    /// ([`crate::LayoutError::MeshSlotsOnNonAplicacao`]), mirroring the
    /// `SupervisorOwnsCode` / `AplicacaoOwnsCode` kind-coherence gates:
    /// a slot foreign to the kind is a build error, not a silent drop.
    ///
    /// Lifted as a typed method (rather than an inline disjunction at
    /// the verify call site) so the mesh-slot set lives in one place —
    /// a future M4 axis added to the Aplicacao surface (per-edge policy
    /// overlay, distributed-app takeover config) is one push here, and
    /// every consumer reaching for "which mesh slots are set" (the
    /// verify gate, a future `feira lint` kind-coherence advisory)
    /// inherits the canonical order without rolling its own.
    ///
    /// Each per-arm kebab-case label is routed through the peer
    /// [`crate::M3_AUTHOR_KEY_MEMBROS`] /
    /// [`crate::M3_AUTHOR_KEY_CONTRATOS`] /
    /// [`crate::M3_AUTHOR_KEY_POLITICAS`] /
    /// [`crate::M3_AUTHOR_KEY_PLACEMENT`] /
    /// [`crate::M3_AUTHOR_KEY_ENTRADA`] consts declared next to the
    /// [`crate::M3_KEY_PLACEMENT`] renderer-side wire-key peer, so both
    /// halves of every M3 top-level mesh slot's dual axis (author-facing
    /// kebab-case label + renderer-side artifact key) route through one
    /// canonical declaration per arm — same discipline the peer
    /// [`crate::M2_AUTHOR_KEY_LIMITS`] / [`crate::M2_AUTHOR_KEY_BEHAVIOR`]
    /// / [`crate::M2_AUTHOR_KEY_UPGRADE_FROM`] top-level M2 slot consts
    /// (f49c8b0) establish on the sibling per-Servico M2 top-level slot
    /// axis, extended here to close the M3 mesh-slot author-facing-label
    /// axis so both altitudes of the typed-slot algebra
    /// (per-Servico M2 + per-Aplicacao M3) share the same
    /// "one canonical byte-string per arm, next to the axis" discipline.
    #[must_use]
    pub fn declared_mesh_slots(&self) -> Vec<&'static str> {
        let mut slots = Vec::new();
        if !self.membros().is_empty() {
            slots.push(crate::render::M3_AUTHOR_KEY_MEMBROS);
        }
        if !self.contratos().is_empty() {
            slots.push(crate::render::M3_AUTHOR_KEY_CONTRATOS);
        }
        if self.politicas().is_some() {
            slots.push(crate::render::M3_AUTHOR_KEY_POLITICAS);
        }
        if self.placement().is_some() {
            slots.push(crate::render::M3_AUTHOR_KEY_PLACEMENT);
        }
        if self.entrada().is_some() {
            slots.push(crate::render::M3_AUTHOR_KEY_ENTRADA);
        }
        slots
    }

    /// The kebab-case `:slot` tags of every supervisor-tree slot this
    /// caixa *declares* a value on, in canonical declaration order
    /// (`:estrategia` → `:max-restarts` → `:restart-window` →
    /// `:children`). A slot counts as declared when its backing field
    /// carries a value — a `Some(...)`, or a non-empty `Vec`.
    ///
    /// The supervisor-tree slots compose the typed OTP supervisor of a
    /// `:kind Supervisor` (INSPIRATIONS §II.2; the `:estrategia` +
    /// `:children` field docs above). [`Self::supervisor_view`] only
    /// folds them into a validatable [`SupervisorSpec`] when the kind
    /// matches (returns `None` otherwise), and the wasm-operator's
    /// hierarchical reconciler only consumes them for a Supervisor. On
    /// any *other* kind a declared supervisor slot is the manifest
    /// field's documented "ignored otherwise" (see the `:estrategia` …
    /// `:children` field docs): it silently passes [`Caixa::from_lisp`]
    /// and then vanishes — never validated, never reconciled — far from
    /// the source caixa.lisp. [`crate::StandardLayout::verify`] consults
    /// this to reject that silent-drop at caixa-build time
    /// ([`crate::LayoutError::SupervisorSlotsOnNonSupervisor`]), the
    /// exact mirror of the [`Self::declared_mesh_slots`] /
    /// [`crate::LayoutError::MeshSlotsOnNonAplicacao`] gate on the
    /// Aplicacao-only slot set: a slot foreign to the kind is a build
    /// error, not a silent drop.
    #[must_use]
    pub fn declared_supervisor_slots(&self) -> Vec<&'static str> {
        let mut slots = Vec::new();
        if self.estrategia().is_some() {
            slots.push(crate::render::SUPERVISOR_AUTHOR_KEY_ESTRATEGIA);
        }
        if self.max_restarts().is_some() {
            slots.push(crate::render::SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS);
        }
        if self.restart_window().is_some() {
            slots.push(crate::render::SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW);
        }
        if !self.children().is_empty() {
            slots.push(crate::render::SUPERVISOR_AUTHOR_KEY_CHILDREN);
        }
        slots
    }

    /// The kebab-case `:slot` tags of every M2 Servico-runtime slot this
    /// caixa *declares* a value on, in canonical declaration order
    /// (`:limits` → `:behavior` → `:upgrade-from`). A slot counts as
    /// declared when its backing field carries a value — a `Some(...)`,
    /// or a non-empty `Vec`.
    ///
    /// The M2 slots configure the runtime of a long-running wasm
    /// component, i.e. a `:kind Servico`: `:limits` is Lunatic
    /// per-process sandboxing (INSPIRATIONS §III.1), `:behavior` is the
    /// OTP `gen_server` callback set (§II.3), `:upgrade-from` is the OTP
    /// appup hot-code-reload table (§II.4). The caixa-helm / caixa-flux
    /// renderers gate on [`crate::require_kind`]`(_, Servico)` and only
    /// emit these slots for a Servico; on any *other* kind a declared M2
    /// slot is the manifest field's documented "ignored otherwise": its
    /// well-formedness is checked by [`crate::StandardLayout::verify`]
    /// but the value is never rendered into a chart / programs.yaml entry
    /// — it silently passes [`Caixa::from_lisp`] + `feira build` and then
    /// vanishes, far from the source caixa.lisp.
    /// [`crate::StandardLayout::verify`] consults this to reject that
    /// silent-drop at caixa-build time
    /// ([`crate::LayoutError::ServicoSlotsOnNonServico`]), the exact
    /// mirror of the [`Self::declared_mesh_slots`] /
    /// [`Self::declared_supervisor_slots`] gates on the peer
    /// kind-exclusive slot sets: a slot foreign to the kind is a build
    /// error, not a silent drop.
    ///
    /// Each per-arm kebab-case label is routed through the peer
    /// [`crate::M2_AUTHOR_KEY_LIMITS`] / [`crate::M2_AUTHOR_KEY_BEHAVIOR`] /
    /// [`crate::M2_AUTHOR_KEY_UPGRADE_FROM`] consts declared next to the
    /// [`crate::M2_KEY_LIMITS`] / [`crate::M2_KEY_BEHAVIOR`] /
    /// [`crate::M2_KEY_UPGRADE_FROM`] renderer-side wire-key peers, so
    /// both halves of the M2 top-level slot's dual axis (author-facing
    /// kebab-case label + renderer-side camelCase overlay-container wire
    /// key) route through one canonical declaration per arm — same
    /// discipline the peer [`crate::M2_BEHAVIOR_AUTHOR_KEY_ON_*`] sub-slot
    /// author-label consts (889dc18) establish on the sibling
    /// per-callback axis inside the `:behavior` overlay block.
    #[must_use]
    pub fn declared_servico_slots(&self) -> Vec<&'static str> {
        let mut slots = Vec::new();
        if self.limits().is_some() {
            slots.push(crate::render::M2_AUTHOR_KEY_LIMITS);
        }
        if self.behavior().is_some() {
            slots.push(crate::render::M2_AUTHOR_KEY_BEHAVIOR);
        }
        if !self.upgrade_from().is_empty() {
            slots.push(crate::render::M2_AUTHOR_KEY_UPGRADE_FROM);
        }
        slots
    }

    /// The kebab-case `:slot` tags of every code-surface slot this caixa
    /// declares a value on that its [`CaixaKind`] doesn't natively own,
    /// in canonical declaration order (`:exe` → `:servicos`). A
    /// code-surface slot is owned by exactly one kind: `:exe` by
    /// [`CaixaKind::Binario`] (the nix-built executable surface), and
    /// `:servicos` by [`CaixaKind::Servico`] (the wasm component +
    /// `ComputeUnit` daemon surface).
    ///
    /// Each is silently ignored when declared on the wrong kind: the
    /// caixa-helm / caixa-flux / caixa-flake renderers gate on
    /// [`crate::require_kind`]`(_, <owning-kind>)`, so on any *other*
    /// code-running kind a declared `:exe` / `:servicos` is the manifest
    /// field's documented "ignored otherwise" — its path is checked for
    /// existence by the layout's `bibliotecas`/`exe`/`servicos` loops
    /// (which run after [`Caixa::from_lisp`]), but the value is never
    /// rendered into a build target or programs.yaml entry. It silently
    /// passes [`Caixa::from_lisp`] + `feira build`, far from the source
    /// caixa.lisp, with no field naming which slot is foreign.
    ///
    /// [`crate::StandardLayout::verify`] consults this to reject that
    /// silent-drop at caixa-build time
    /// ([`crate::LayoutError::ForeignCodeSlot`]), beside the M2
    /// servico-runtime, supervisor-tree, and M3 mesh kind-coherence
    /// gates ([`Self::declared_servico_slots`] /
    /// [`Self::declared_supervisor_slots`] /
    /// [`Self::declared_mesh_slots`]): the fourth kind ↔ slot algebra
    /// axis to be closed on the typed surface. The Supervisor /
    /// Aplicacao "no code at all" cases ([`crate::LayoutError::SupervisorOwnsCode`]
    /// / [`crate::LayoutError::AplicacaoOwnsCode`]) keep their dedicated
    /// diagnostics — they fire ahead of this gate on the same `verify`
    /// pass, so for Supervisor / Aplicacao the `OwnCode` arm always wins
    /// and this method is moot. For Biblioteca / Binario / Servico, this
    /// gate fires when a code-running kind declares another code-running
    /// kind's exclusive code surface.
    ///
    /// `:bibliotecas` is deliberately excluded — a Binario or Servico
    /// may legitimately ship a `lib/` helper that the underlying
    /// substrate (the nix flake for Binario, the wasm component build
    /// for Servico) bundles into its build, so the slot's
    /// declared-on-wrong-kind cardinality isn't a structural error on
    /// either code-running kind. A Biblioteca declaring `:bibliotecas`
    /// is the native case (the slot's owning kind). Supervisor /
    /// Aplicacao declaring `:bibliotecas` is gated upstream by
    /// [`crate::LayoutError::SupervisorOwnsCode`] /
    /// [`crate::LayoutError::AplicacaoOwnsCode`].
    ///
    /// Lifted as a typed method (rather than an inline disjunction at
    /// the verify call site) so the foreign-code-slot set lives in one
    /// place — a future kind that gains its own code-surface slot is
    /// one push here, and every consumer reaching for "which code
    /// surfaces are foreign to this kind" (the verify gate, a future
    /// `feira lint` kind-coherence advisory, the future `app-operator`'s
    /// per-caixa build-target classifier) inherits the canonical order
    /// without rolling its own.
    #[must_use]
    pub fn declared_foreign_code_slots(&self) -> Vec<&'static str> {
        let mut slots = Vec::new();
        if !self.exe().is_empty() && !self.kind().requires_exe() {
            slots.push(":exe");
        }
        if !self.servicos().is_empty() && !self.kind().requires_servicos() {
            slots.push(":servicos");
        }
        slots
    }

    /// Validate every entry of `:deps` and `:deps-dev` through
    /// [`Dep::validate`] — closing the parity loop with the per-axis
    /// `:versao` gates already wired into the typed-graph
    /// ([`crate::AplicacaoSpec::validate_membros`] for `:membros`,
    /// 9888b13) and typed supervisor tree
    /// ([`crate::SupervisorSpec::validate`] for `:children`, b38ff3a).
    ///
    /// Until this gate landed `:deps :versao` and `:deps-dev :versao`
    /// were the only `:versao` axes still untyped past
    /// [`Caixa::from_lisp`]: the derive macro stored the requirement
    /// as a String without parsing it, so a malformed-but-non-empty
    /// requirement (`"^bad-version"`, `"^^0.1"`, `"v0.1"`, `"not-a-req"`)
    /// silently passed parse and the `semver::Error` surfaced at
    /// lacre-resolve time, far from the source caixa.lisp, with no
    /// field naming which `:deps` entry carried the typo. Lifting the
    /// gate here makes the four `:versao` typed surfaces (`:deps`,
    /// `:deps-dev`, `:membros`, `:children`) structurally equivalent —
    /// every requirement string past `validate_deps` is round-trippable
    /// through [`crate::parse_requirement`] without re-checking at the
    /// resolver layer.
    ///
    /// Both lists run through the same per-entry validator so a typo
    /// in `:deps-dev` surfaces with the same diagnostic as one in
    /// `:deps` — neither axis is a second-class citizen of the typed
    /// surface.
    ///
    /// Within each list, [`DepError::DuplicateNome`] closes the
    /// set-not-multiset discipline on the `:nome` axis: two entries
    /// naming the same caixa carry two `:versao` / `:fonte` / feature
    /// triples that the caixa-resolver's lacre pipeline collapses to one
    /// via its `HashMap`-keyed-by-`:nome` consumption — the second entry
    /// silently overwrites the first at `concrete_versao`-resolve time
    /// (the same "second wins / one silently overwrites the other"
    /// shape the peer typed-graph duplicate gates already close on every
    /// other Vec-shaped authoring surface that keys by name). The
    /// duplicate check fires per-list and runs *after* each per-entry
    /// [`Dep::validate`] call so a malformed-and-duplicated entry
    /// surfaces its narrower per-entry diagnostic
    /// ([`DepError::NomeInvalid`], [`DepError::VersaoInvalid`],
    /// [`DepError::FonteRepoEmpty`], …) before the cross-entry duplicate
    /// diagnostic — the canonical "per-entry shape before cross-entry
    /// uniqueness" precedence the peer `:children :caixa`
    /// ([`crate::SupervisorSpec::validate`]), `:membros :caixa`
    /// ([`crate::AplicacaoSpec::validate_membros`]), `:contratos`
    /// ([`crate::AplicacaoSpec::validate`]), `:placement :clusters`
    /// ([`crate::AplicacaoSpec::validate_placement`]),
    /// `:entrada :paths` ([`crate::AplicacaoSpec::validate`]),
    /// `:upgrade-from :from` ([`crate::upgrade::validate_upgrade_from`]),
    /// and the within-`:upgrade-from`-entry per-instruction-class
    /// singularity gates ([`crate::UpgradeError::DuplicateLoadModule`],
    /// [`crate::UpgradeError::DuplicateStateChange`],
    /// [`crate::UpgradeError::DuplicateCleanup`]) all establish.
    ///
    /// Cross-list (`:deps` ↔ `:deps-dev`) coincidence is *not* gated
    /// here: Cargo's `[dependencies]` + `[dev-dependencies]` accept the
    /// same name in both tables (the dev table's pin overrides the
    /// runtime table's pin in test/dev contexts), and caixa's surface
    /// mirrors that convention until a deliberate choice retires the
    /// override pattern. Only within-list duplicates are structurally
    /// incoherent — those are what this gate closes.
    ///
    /// Compound per-`Caixa` entry gate on the dep-graph axis: folds the
    /// two standalone dep-list validators — the per-entry + within-list
    /// duplicate-`:nome` walk (the [`Dep::validate`] +
    /// [`crate::render::insert_first_seen`] cascade this method opened
    /// on) and the cross-slot self-edge gate
    /// ([`crate::dep::validate_no_self_dep`]) — onto one substrate
    /// primitive on [`Caixa`]. The two arms run in the same canonical
    /// order the layout pipeline
    /// ([`crate::layout::StandardLayout::verify`], the `feira build`
    /// author-time gate) has always sequenced them (per-entry +
    /// cross-entry duplicate → cross-slot self-edge), so the fold is
    /// byte-for-byte equivalent to the pre-fold two-block cascade at
    /// that call site (pinned by the paired
    /// `validate_deps_folds_per_entry_arm_matches_gate` /
    /// `validate_deps_folds_self_edge_arm_matches_gate` equivalence
    /// pins and the `validate_deps_per_entry_arm_fires_before_self_edge_arm`
    /// ordering pin). Self-contained on `&self` — resolves its three
    /// inputs ([`Self::deps`], [`Self::deps_dev`], [`Self::nome`])
    /// through the substrate primitives' own accessor family, the same
    /// posture every peer per-slot compound gate
    /// ([`crate::AplicacaoSpec::validate_contratos`],
    /// [`crate::MeshPolicy::validate`],
    /// [`crate::SupervisorSpec::validate_children`],
    /// [`Self::validate_upgrade_from`]) already carries.
    ///
    /// Prior to this lift [`crate::dep::validate_no_self_dep`] lived
    /// only open-coded at the layout wire-up site
    /// ([`crate::layout::StandardLayout::verify`], caixa-core/src/layout.rs)
    /// as a standalone two-arg dispatch immediately after this method's
    /// per-entry + cross-entry walk, both wrapped through the same
    /// [`crate::LayoutError::DepsViolation`] envelope: every future
    /// consumer that wanted to gate the dep-graph as a whole — the
    /// deferred `caixa.pleme.io/v1alpha1/Caixa` CR materializer's
    /// per-CR admission webhook re-checking `:deps` / `:deps-dev` after
    /// a per-entry patch, a future `feira validate --deps` per-caixa
    /// admission verb, a per-`:deps` overlay resolver a per-cluster
    /// overlay lift would materialize (each the deferred consumer this
    /// method's peer [`Self::deps`] / [`Self::deps_dev`] accessors'
    /// docstrings already name) — was structurally forced to either
    /// re-inline the two-dispatch cascade in lockstep with the layout
    /// wire-up (the duplication the PRIME DIRECTIVE names as a bug) or
    /// call the whole [`crate::layout::StandardLayout::verify`] pipeline
    /// and pay every peer per-Caixa gate to re-check one slot. Post-fold
    /// each such consumer reaches the two-arm compound gate through one
    /// call on the substrate primitive.
    pub fn validate_deps(&self) -> Result<(), DepError> {
        for &list in crate::dep::DepList::ALL {
            let mut seen = std::collections::HashSet::new();
            for dep in self.deps_of(list) {
                dep.validate()?;
                crate::render::insert_first_seen(&mut seen, dep.nome(), || {
                    DepError::DuplicateNome {
                        nome: dep.nome().to_string(),
                        list: list.as_str(),
                    }
                })?;
            }
        }
        crate::dep::validate_no_self_dep(self.deps(), self.deps_dev(), self.nome())?;
        Ok(())
    }

    /// Reject `:nome` values the K8s apiserver would refuse at admission
    /// time. The top-level Caixa identity flows directly into every
    /// substrate-side artifact's `metadata.name` axis: the
    /// `lareira-<nome>` Helm chart name ([`caixa-helm::lib::chart_name`]),
    /// the programs.yaml `name:` entry the `lareira-fleet-programs`
    /// aggregator keys ComputeUnit derivation off
    /// ([`caixa-flux::lib::programs_yaml_entry`]), the
    /// `LABEL_APLICACAO` label value carried on every Aplicacao-owned
    /// pod and the per-`:contratos` CiliumNetworkPolicy `metadata.name`
    /// (`<aplicacao>-<de>-to-<para>`) and the per-`:entrada`
    /// `<aplicacao>-<para>` HTTPRoute `metadata.name`
    /// ([`caixa-mesh::lib::cilium_network_policies`],
    /// [`caixa-mesh::lib::gateway_routes`]), and the default
    /// `lib/<nome>.lisp` / `exe/<nome>` layout paths
    /// ([`crate::StandardLayout::verify`]). Each K8s apiserver-side
    /// schema enforces the DNS-1123 label rule on admission; a
    /// structurally invalid `:nome` (`"MyApp"` — the canonical
    /// "I copied the display name verbatim" footgun, `"my_app"` — the
    /// Python-/Postgres-leak, `"team.app"` — `:nome` is a single label
    /// not a subdomain, `"-app"` / `"app-"` — DNS-1123 boundary
    /// violations, `"my app"` — the paste-from-doc footgun, `"café"` —
    /// IDN must be pre-encoded as Punycode, the 64-byte UUID-shaped
    /// over-cap slug) silently passed [`Caixa::from_lisp`] and the
    /// failure surfaced at `kubectl apply` time as a `metadata.name:
    /// Invalid value` rejection on whichever derived artifact admitted
    /// first, far from the source `caixa.lisp` and without any field
    /// naming the offending `:nome`.
    ///
    /// Thin wrapper around [`crate::render::is_dns_1123_label`] (the
    /// substrate-side predicate the per-axis name gates already share:
    /// `:membros :caixa` 3f9d7a0, `:placement :clusters` 6cbb900,
    /// `:children :caixa` 31bfa43) that maps the shared parser-shaped
    /// reason into the [`ManifestError::NomeInvalid`] variant, so the
    /// diagnostic is self-locating (the offending `:nome` is named
    /// verbatim) and the author can grep their `caixa.lisp` for
    /// `:nome "<value>"` and fix it in one edit. Same diagnostic shape
    /// every per-axis sibling gate already exposes
    /// ([`crate::AplicacaoError::MembroCaixaInvalid`],
    /// [`crate::AplicacaoError::PlacementClusterInvalid`],
    /// [`crate::SupervisorError::ChildCaixaInvalid`]).
    ///
    /// Empty `:nome` (which [`Caixa::from_lisp`] does not reject — the
    /// derive macro stores the raw String) is gated by the narrower
    /// [`ManifestError::NomeEmpty`] arm before the predicate is
    /// consulted, mirroring the empty-first cascade every per-axis
    /// name gate already uses (e.g. `MembroCaixaEmpty` before
    /// `MembroCaixaInvalid`, `EmptyChildName` before `ChildCaixaInvalid`).
    pub fn validate_nome(&self) -> Result<(), ManifestError> {
        // Routes through the shared
        // [`crate::render::require_valid_dns_1123_label`] gate the peer
        // name axes each land on so drift between the eight axes'
        // accepted DNS-1123-label sets is structurally impossible.
        let nome = self.nome();
        crate::render::require_valid_dns_1123_label(
            nome,
            || ManifestError::NomeEmpty,
            |reason| ManifestError::NomeInvalid {
                nome: nome.to_string(),
                reason,
            },
        )
    }

    /// Reject `:nome` values whose joint length with the canonical
    /// [`crate::LAREIRA_CHART_NAME_PREFIX`] (`"lareira-"`) overflows
    /// the K8s DNS-1123 label cap [`crate::DNS_1123_LABEL_MAX_LEN`]
    /// (63 bytes). Every per-Servico / per-Aplicacao renderer the
    /// substrate carries materializes the caixa's `:nome` through the
    /// canonical [`crate::lareira_chart_name`] helper (f7320d7) into a
    /// `lareira-<nome>` artifact that lands as a K8s `metadata.name` /
    /// Helm chart name / `HelmRelease` `release_name`: `caixa-helm`'s
    /// `ChartDir.name` + `Chart.yaml::name`
    /// (caixa-helm/src/lib.rs:207), `caixa-flux`'s `cluster_bundle`
    /// `HelmRelease` `chart:` slot (caixa-flux/src/lib.rs:329),
    /// `caixa-tatara`'s `process_for_aplicacao` `release_name` +
    /// `oci://<registry>/lareira-<nome>` chart ref
    /// (caixa-tatara/src/lib.rs:124,178). Helm's own `Chart.yaml::name`
    /// admission rule strict-parses against DNS-1123-label, the Helm
    /// operator's tracking-secret name is derived from `release_name`
    /// and is itself DNS-1123-label-bounded, and the rendered chart's
    /// K8s object `metadata.name` axes embed the chart name as a
    /// prefix — every one fails admission on a > 63-byte chart name.
    ///
    /// The per-axis [`Self::validate_nome`] gate (6c992f8) already
    /// caps `:nome` itself at 63 bytes via [`is_dns_1123_label`], so a
    /// `:nome` of 56–63 bytes silently passed validate (the inner
    /// DNS-1123 check accepts the bare `:nome`) but produced a
    /// `lareira-<nome>` of 64–71 bytes that the apiserver / `helm lint`
    /// rejected at admission — far from the source `caixa.lisp`, with
    /// no field naming the overflow root cause. The
    /// [`lareira_chart_name`] helper's own doc comment
    /// (caixa-core/src/render.rs:3198) explicitly deferred the fix:
    /// "the M4 admission webhook will pin the joint-length invariant
    /// when it lands". This gate lands the invariant at the
    /// manifest-validate layer rather than waiting for the apiserver
    /// — the same fail-at-the-source posture every peer per-axis
    /// value-shape gate (DNS-1123 on `:nome`, SemVer-2 on `:versao`,
    /// SPDX-expression-shape on `:licenca`, 4-digit decimal year on
    /// `:edicao`, etc.) takes.
    ///
    /// Thin wrapper around
    /// [`crate::render::is_lareira_chart_name_shape`] (the
    /// substrate-side predicate that composes [`lareira_chart_name`] +
    /// [`is_dns_1123_label`] via the lifted
    /// [`crate::LAREIRA_CHART_NAME_NOME_MAX_LEN`] budget); maps the
    /// shared parser-shaped reason into the
    /// [`ManifestError::NomeChartNameBudgetExceeded`] variant so the
    /// diagnostic is self-locating (the offending `:nome` is named
    /// verbatim alongside the rendered chart name and the budget) and
    /// the author can shorten in one edit. The gate runs across every
    /// `:kind` — `:nome` is the substrate-wide identity axis any
    /// future renderer the substrate adds can derive a
    /// `lareira-<nome>` artifact from, and uniform enforcement closes
    /// the drift footgun where a future kind grows a chart-emitting
    /// render path while the validate cascade doesn't catch it.
    ///
    /// Runs *after* [`Self::validate_nome`] so the narrower
    /// `NomeEmpty` / `NomeInvalid` shape diagnostics fire first — a
    /// structurally-malformed `:nome` (empty, uppercase, underscore,
    /// dot, leading/trailing hyphen, Unicode, > 63 bytes) surfaces its
    /// specific shape error rather than the chart-name-budget error,
    /// preserving the legitimate "well-shaped `:nome` that happens to
    /// overflow the joint cap" arm for this gate.
    pub fn validate_nome_chart_name_budget(&self) -> Result<(), ManifestError> {
        let nome = self.nome();
        crate::render::is_lareira_chart_name_shape(nome).map_err(|reason| {
            ManifestError::NomeChartNameBudgetExceeded {
                nome: nome.to_string(),
                reason,
            }
        })
    }

    /// Reject `:versao` values that don't parse as [`semver::Version`].
    /// The top-level Caixa version flows directly into every
    /// substrate-side artifact that carries a "this is which version of
    /// the caixa" axis: the `lareira-<nome>` Helm chart's `Chart.yaml`
    /// `version:` + `appVersion:` axes ([`caixa-helm::lib`] —
    /// SemVer-2-strict at `helm template` / `helm install` time per
    /// https://helm.sh/docs/topics/charts/#charts-and-versioning), the
    /// `feira publish` Zig-style `v<versao>` git tag
    /// ([`caixa-flux::lib::programs_yaml_entry`] / the
    /// `caixa-publish.yml` reusable workflow), the programs.yaml entry's
    /// `versao:` value the `lareira-fleet-programs` aggregator carries
    /// onto each rendered ComputeUnit, the OCI image's `:v<versao>` /
    /// `:latest` tags the substrate's `wasi-service-flake` builds with
    /// `skopeo push`, the lacre closure's pinned versions
    /// ([`caixa-resolver`] keys `concrete_versao`), and the
    /// `:upgrade-from :from` references peers in this exact `versao`
    /// shape (`semver::Version`, not `VersionReq`). Each consumer
    /// expects a strict three-part `MAJOR.MINOR.PATCH` (optionally
    /// `-prerelease` and/or `+build`); a structurally invalid `:versao`
    /// (`"0.1"` — missing patch, the canonical "I shortened it" footgun;
    /// `"v0.1.0"` — the git-tag-shape-leaking-into-versao typo;
    /// `"latest"` / `"main"` — the "I confused it with a docker tag"
    /// footgun; `"^0.1"` / `"~0.1.2"` — the requirement-shape leaking
    /// into the version field a peer `:deps :versao` accepts;
    /// `"0.1.0.0"` — the four-part Java/Microsoft convention DNS
    /// SemVer-2 forbids) silently passed [`Caixa::from_lisp`] (the
    /// derive macro stores the raw String) and the failure surfaced at
    /// the *first* downstream consumer that strict-parses it: at
    /// `helm install` time as a chart-version rejection, at
    /// `feira publish` time as a malformed git tag, at lacre-resolve
    /// time as a `semver::Error` not naming the offending caixa, at
    /// `feira upgrade --to <versao>` time as an unresolvable
    /// `:upgrade-from :from` match — far from the source `caixa.lisp`
    /// and without any field naming the offending `:versao`.
    ///
    /// Thin wrapper around [`semver::Version::parse`] — the same parser
    /// [`crate::CaixaVersion::parse`] (the typed `:versao` accessor)
    /// and [`crate::UpgradeFromEntry::validate`] (the peer
    /// `:upgrade-from :from` axis, 26da2c7) consume. Maps the
    /// `semver::Error` reason into the [`ManifestError::VersaoInvalid`]
    /// variant, carrying the offending `:versao` verbatim + a
    /// parser-shaped reason naming the specific violation, so the
    /// diagnostic is self-locating (the author can grep their
    /// `caixa.lisp` for `:versao "<value>"` and fix it in one edit).
    /// Same diagnostic shape as [`ManifestError::NomeInvalid`]
    /// (6c992f8) and [`crate::UpgradeError::FromInvalid`]
    /// (b0c8389) on the peer axes. With this gate, the typed `:versao`
    /// surfaces — top-level `:versao`, `:upgrade-from :from` — are
    /// now structurally equivalent (every value past validate is
    /// round-trippable through [`semver::Version::parse`] without
    /// re-checking at the renderer, resolver, or operator hot-upgrade
    /// layer), peer with the four `:versao` requirement axes (`:deps`,
    /// `:deps-dev`, `:membros`, `:children`) the prior commits
    /// (2420c44, 9888b13, b38ff3a) wired through `parse_requirement`.
    ///
    /// Empty `:versao` (which [`Caixa::from_lisp`] does not reject —
    /// the derive macro stores the raw String) is gated by the
    /// narrower [`ManifestError::VersaoEmpty`] arm before the parser is
    /// consulted, mirroring the empty-first cascade every per-axis
    /// version gate already uses (e.g. `MembroVersaoEmpty` before
    /// `MembroVersaoInvalid`, `EmptyChildVersion` before
    /// `ChildVersaoInvalid`, `NomeEmpty` before `NomeInvalid`).
    pub fn validate_versao(&self) -> Result<(), ManifestError> {
        let versao = self.versao();
        if versao.is_empty() {
            return Err(ManifestError::VersaoEmpty);
        }
        semver::Version::parse(versao).map_err(|e| ManifestError::VersaoInvalid {
            versao: versao.to_string(),
            reason: e.to_string(),
        })?;
        Ok(())
    }

    /// Compound per-`Caixa` entry gate on the M2 `:upgrade-from` slot:
    /// folds the three [`crate::upgrade`] top-level validators — the
    /// per-entry shape + cross-entry duplicate-`:from` gate
    /// ([`crate::upgrade::validate_upgrade_from`]), the cross-slot
    /// `:from < :versao` SemVer-2 precedence gate
    /// ([`crate::upgrade::validate_upgrade_from_against_versao`]), and the
    /// cross-slot `:state-change` ↔ `:on-state-change` composition gate
    /// ([`crate::upgrade::validate_upgrade_from_against_behavior`]) — onto
    /// one substrate primitive on [`Caixa`]. The three dispatches run in
    /// the same order the layout pipeline
    /// ([`crate::layout::StandardLayout::verify`], the `feira build`
    /// author-time gate) has always sequenced them, so the fold is
    /// byte-for-byte equivalent to the pre-fold three-block cascade at
    /// that call site (pinned by the per-arm
    /// `validate_upgrade_from_folds_per_entry_arm_matches_gate` /
    /// `_folds_versao_arm_matches_gate` / `_folds_behavior_arm_matches_gate`
    /// equivalence pins and by the cross-arm
    /// `validate_upgrade_from_per_entry_arm_fires_before_versao_arm` /
    /// `_versao_arm_fires_before_behavior_arm` ordering pins).
    ///
    /// Prior to this lift the three [`crate::upgrade`] top-level validators
    /// lived only open-coded at the layout wire-up site
    /// ([`crate::layout::StandardLayout::verify`], caixa-core/src/layout.rs),
    /// each threaded through the same `self.upgrade_from()` slice and each
    /// paired with the same [`crate::LayoutError::UpgradeViolation`]-wrap
    /// envelope: every future consumer that wanted to gate `:upgrade-from`
    /// as a whole — the deferred `caixa.pleme.io/v1alpha1/Caixa` CR
    /// materializer's per-CR admission webhook re-checking `:upgrade-from`
    /// after a per-`(:from … :instructions …)` patch, a future `feira
    /// validate --upgrade` per-caixa admission verb, a per-`:upgrade-from`
    /// overlay resolver a per-cluster overlay lift would materialize —
    /// was structurally forced to either re-inline the three-dispatch
    /// cascade in lockstep with the layout wire-up (the duplication the
    /// PRIME DIRECTIVE names as a bug) or call the whole
    /// [`crate::layout::StandardLayout::verify`] pipeline and pay every
    /// peer per-Caixa gate to re-check one slot. Post-fold each such
    /// consumer reaches the three-arm compound gate through one call on
    /// the substrate primitive.
    ///
    /// The three arms together name one contract with three axes:
    ///
    ///   - **per-entry + cross-entry graph-edge invariant** — every entry's
    ///     `:from` parses as SemVer-2 and every per-instruction / within-
    ///     entry ordering / singularity gate on each entry's
    ///     `:instructions` list passes, and no two entries share the same
    ///     parsed `:from` (the wasm-operator's OTP appup
    ///     `release_handler:install_release/1` analog picks at most one
    ///     matching block per running version — two entries with the same
    ///     parsed semver are an ambiguous edge in the typed upgrade graph).
    ///   - **cross-slot reachability invariant** — every entry's `:from`
    ///     is strictly less than the caixa's own `:versao` under SemVer-2
    ///     precedence. An entry whose `:from >= :versao` is structurally
    ///     unreachable by the operator's `:from`-match dispatch (the
    ///     operator loads the current `:versao` and matches the *running*
    ///     version against each entry's `:from`; an entry whose `:from >=
    ///     :versao` is never reached because the operator never runs a
    ///     version >= the current one that it could then upgrade *to* the
    ///     current one).
    ///   - **cross-slot composition invariant** — every entry carrying a
    ///     `(:state-change …)` instruction has a `:behavior
    ///     :on-state-change` callback declared on the same caixa. The
    ///     per-version migration script is the `gen_server:code_change/3`
    ///     analog and the runtime hook it is delivered through during hot
    ///     upgrade is the `:on-state-change` callback (the upgrade.rs
    ///     module doc pins the composition verbatim: "Composes with the
    ///     `:behavior :on-state-change` callback to deliver state migration
    ///     during hot upgrades").
    ///
    /// All three axes must hold together — every consumer's
    /// `:upgrade-from` accept-set past this compound gate is the same
    /// set the `feira build` author-time gate admits.
    ///
    /// The per-slot compound entry gate discipline lifted here onto the
    /// M2 `:upgrade-from` axis is the sibling of the peer per-kind
    /// compound entry gates ([`crate::render::require_supervisor_view`]
    /// / [`crate::render::require_aplicacao_view`] /
    /// [`crate::render::require_v0_servico_shape`]) that fold every
    /// per-kind cascade at the per-kind altitude, and of the peer
    /// per-slot compound gates ([`crate::AplicacaoSpec::validate_contratos`],
    /// [`crate::MeshPolicy::validate`],
    /// [`crate::SupervisorSpec::validate_children`]) that fold every
    /// structural axis on their slot onto one substrate primitive.
    /// Extended here to the last unlifted compound-cascade wire-up at
    /// the layout-pipeline altitude — the three-dispatch M2
    /// `:upgrade-from` cascade that lived only open-coded at the layout
    /// wire-up site.
    ///
    /// The per-instruction script-path on-disk existence-probe walk that
    /// [`crate::layout::StandardLayout::verify`] runs immediately after
    /// this gate (which resolves each entry's `:instructions
    /// (:state-change :script)` against the layout root) stays open-coded
    /// at the layout wire-up site — that arm needs the filesystem oracle
    /// on the [`crate::LayoutInvariants`] trait, not the pure per-Caixa
    /// typed-shape surface this compound gate folds. Same posture the
    /// peer [`Self::validate_code_paths`] takes on the sibling code-path
    /// axes: the typed-shape gate fires on the per-Caixa surface, the
    /// on-disk existence check fires on the [`crate::StandardLayout`]
    /// surface.
    ///
    /// # Errors
    ///
    /// Returns [`crate::UpgradeError::FromInvalid`] /
    /// [`crate::UpgradeError::ModuleEmpty`] /
    /// [`crate::UpgradeError::ModuleInvalid`] /
    /// [`crate::UpgradeError::EmptyScript`] /
    /// [`crate::UpgradeError::AbsoluteScript`] /
    /// [`crate::UpgradeError::ParentEscapeScript`] /
    /// [`crate::UpgradeError::NonLispExtensionScript`] /
    /// [`crate::UpgradeError::RestartNotExclusive`] /
    /// [`crate::UpgradeError::StateChangeWithoutPriorLoad`] /
    /// [`crate::UpgradeError::PurgeWithoutPriorLoad`] /
    /// [`crate::UpgradeError::StateChangeAfterCleanup`] /
    /// [`crate::UpgradeError::DuplicateLoadModule`] /
    /// [`crate::UpgradeError::DuplicateStateChange`] /
    /// [`crate::UpgradeError::DuplicateCleanup`] /
    /// [`crate::UpgradeError::DuplicateFrom`] on the per-entry +
    /// cross-entry axis; [`crate::UpgradeError::FromNotBeforeVersao`] on
    /// the cross-slot `:from ↔ :versao` axis;
    /// [`crate::UpgradeError::StateChangeWithoutOnStateChangeCallback`]
    /// on the cross-slot `:state-change ↔ :on-state-change` axis.
    pub fn validate_upgrade_from(&self) -> Result<(), crate::UpgradeError> {
        crate::upgrade::validate_upgrade_from(self.upgrade_from())?;
        crate::upgrade::validate_upgrade_from_against_versao(self.upgrade_from(), self.versao())?;
        crate::upgrade::validate_upgrade_from_against_behavior(
            self.upgrade_from(),
            self.behavior(),
        )?;
        Ok(())
    }

    /// Compound per-`Caixa` entry gate on the M2 `:limits` slot — folds
    /// the [`crate::LimitsSpec::validate`] four-axis cascade (`:memory`
    /// wasm32 zero-floor / below-page / above-cap / non-page-multiple;
    /// `:fuel` zero-floor / cap; `:wall-clock` zero-floor / cap; `:cpu`
    /// zero-floor / cap) onto one substrate primitive on [`Caixa`]. The
    /// `#[serde(default)]` absent-slot arm (`limits: None`, the
    /// canonical "no bound declared — engine-default applies" author
    /// shape [`crate::LimitsSpec::is_empty`]'s per-axis `None` cascade
    /// reads) is the fold's identity element and passes trivially; the
    /// present-slot arm (`limits: Some(l)`) dispatches to
    /// [`crate::LimitsSpec::validate`] verbatim, threading its per-axis
    /// [`crate::LimitsError`] Display through untouched.
    ///
    /// Prior to this lift the M2 `:limits` slot lived only wired
    /// open-coded at the layout wire-up site
    /// ([`crate::layout::StandardLayout::verify`], caixa-core/src/layout.rs),
    /// through the `if let Some(l) = caixa.limits() { l.validate() … }`
    /// three-line `Option::None → Ok(()) | Some(_) → …` unwrap-and-
    /// dispatch pattern paired with the same
    /// [`crate::LayoutError::LimitsViolation`]-wrap envelope: every
    /// future consumer that wanted to gate `:limits` as a whole — the
    /// deferred `caixa.pleme.io/v1alpha1/Caixa` CR materializer's
    /// per-CR admission webhook re-checking `:limits` after a per-
    /// `{:memory, :fuel, :wall-clock, :cpu}` patch (the exact case the
    /// [`Self::limits`] accessor docstring names as the second
    /// consumer of the slot), a future `feira validate --limits` per-
    /// caixa admission verb, a per-`:limits` overlay resolver a per-
    /// cluster `:limits-overrides` overlay lift would materialize — was
    /// structurally forced to either re-inline the two-line
    /// `Option::None → Ok(()) | Some(_) → …` unwrap-and-dispatch
    /// pattern in lockstep with the layout wire-up (the duplication the
    /// PRIME DIRECTIVE names as a bug) or call the whole
    /// [`crate::layout::StandardLayout::verify`] pipeline and pay every
    /// peer per-Caixa gate ([`Self::validate_nome`],
    /// [`Self::validate_versao`], [`Self::validate_deps`],
    /// [`Self::validate_etiquetas`], [`Self::validate_autores`],
    /// [`Self::validate_repositorio`], [`Self::validate_descricao`],
    /// [`Self::validate_licenca`], [`Self::validate_edicao`],
    /// [`Self::validate_upgrade_from`], [`Self::validate_code_paths`],
    /// plus the per-kind `require_supervisor_view` /
    /// `require_aplicacao_view` gates, plus the on-disk existence
    /// walks) to re-check one slot. Post-lift each such consumer
    /// reaches the [`crate::LimitsSpec::validate`] four-axis cascade
    /// (and its identity-element on the absent slot) through one call
    /// on the substrate primitive.
    ///
    /// The per-slot compound entry-gate discipline lifted here onto the
    /// M2 `:limits` axis is the sibling of the peer per-slot compound
    /// gates ([`crate::AplicacaoSpec::validate_contratos`],
    /// [`crate::MeshPolicy::validate`],
    /// [`crate::SupervisorSpec::validate_children`],
    /// [`Self::validate_upgrade_from`], [`Self::validate_deps`]) that
    /// fold every structural + cross-slot axis on their slot onto one
    /// substrate primitive. Extended here to the M2 `:limits` slot, the
    /// first of the two M2 typed slots (`:limits`, `:behavior`) whose
    /// per-Caixa compound-gate wire-up still lived open-coded at the
    /// layout altitude after the [`Self::validate_upgrade_from`] lift
    /// (d6801df) closed the sibling M2 slot's cascade.
    ///
    /// # Errors
    ///
    /// Returns every [`crate::LimitsError`] variant on the present-slot
    /// arm — verbatim from [`crate::LimitsSpec::validate`]. Passes
    /// trivially on the absent-slot arm (`limits: None`, the fold's
    /// identity element).
    pub fn validate_limits(&self) -> Result<(), crate::LimitsError> {
        match self.limits() {
            Some(l) => l.validate(),
            None => Ok(()),
        }
    }

    /// Compound per-`Caixa` entry gate on the M2 `:behavior` slot's
    /// pure typed-shape surface — folds the
    /// [`crate::BehaviorSpec::validate`] six-slot value-shape cascade
    /// (each declared `:on-init` / `:on-call` / `:on-cast` / `:on-info`
    /// / `:on-state-change` / `:on-terminate` callback-path is
    /// non-empty / relative / no-`..`-parent-escape / terminating-
    /// `.lisp`-extension, routed through the shared
    /// [`crate::render::require_sandboxed_lisp_path`] arm-set) onto one
    /// substrate primitive on [`Caixa`]. The `#[serde(default)]`
    /// absent-slot arm (`behavior: None`, the canonical "no callback
    /// declared — the runtime falls back to the wasm-engine's default
    /// callback per arm" author shape [`crate::BehaviorSpec::is_empty`]'s
    /// per-slot `None` cascade reads) is the fold's identity element
    /// and passes trivially; the present-slot arm (`behavior: Some(b)`)
    /// dispatches to [`crate::BehaviorSpec::validate`] verbatim,
    /// threading its per-slot [`crate::BehaviorError`] Display through
    /// untouched.
    ///
    /// Scope note — the on-disk callback-path existence walk paired
    /// with the value-shape gate at
    /// [`crate::layout::StandardLayout::verify`] stays open-coded at
    /// the layout altitude, because it needs the
    /// [`crate::layout::LayoutInvariants`] filesystem oracle
    /// ([`crate::layout::LayoutInvariants::exists`]) that the pure
    /// per-Caixa typed-shape surface this compound gate folds onto has
    /// no reference to. Same posture the peer M2 `:upgrade-from`
    /// per-Caixa compound gate ([`Self::validate_upgrade_from`]
    /// d6801df) already carries: the pure typed-shape surface folds
    /// onto the substrate primitive; the per-instruction script-path
    /// existence probe on the paired axis (there `:state-change
    /// :script`; here `:on-*`) stays at the layout altitude.
    ///
    /// Prior to this lift the pure value-shape surface of the M2
    /// `:behavior` slot lived only wired open-coded at the layout
    /// wire-up site ([`crate::layout::StandardLayout::verify`],
    /// caixa-core/src/layout.rs), through the
    /// `if let Some(b) = caixa.behavior() { b.validate() … }`
    /// unwrap-and-dispatch pattern paired with the same
    /// [`crate::LayoutError::BehaviorViolation`]-wrap envelope: every
    /// future consumer that wanted to gate the `:behavior` slot's
    /// value-shape as a whole — the deferred
    /// `caixa.pleme.io/v1alpha1/Caixa` CR materializer's per-CR
    /// admission webhook re-checking `:behavior` after a per-`{:on-init,
    /// :on-call, :on-cast, :on-info, :on-state-change, :on-terminate}`
    /// patch (the exact case the peer `:on-*` accessor docstrings on
    /// [`crate::BehaviorSpec`] already name as deferred consumers of
    /// the slot), a future `feira validate --behavior` per-caixa
    /// admission verb, a per-`:behavior` overlay resolver a future
    /// per-cluster callback-overlay lift would materialize — was
    /// structurally forced to either re-inline the two-line
    /// `Option::None → Ok(()) | Some(_) → …` unwrap-and-dispatch
    /// pattern in lockstep with the layout wire-up (the duplication the
    /// PRIME DIRECTIVE names as a bug) or call the whole
    /// [`crate::layout::StandardLayout::verify`] pipeline and pay every
    /// peer per-Caixa gate ([`Self::validate_nome`],
    /// [`Self::validate_versao`], [`Self::validate_deps`],
    /// [`Self::validate_etiquetas`], [`Self::validate_autores`],
    /// [`Self::validate_repositorio`], [`Self::validate_descricao`],
    /// [`Self::validate_licenca`], [`Self::validate_edicao`],
    /// [`Self::validate_limits`], [`Self::validate_upgrade_from`],
    /// [`Self::validate_code_paths`], plus the per-kind
    /// `require_supervisor_view` / `require_aplicacao_view` gates, plus
    /// the on-disk existence walks) to re-check one slot. Post-lift
    /// each such consumer reaches the [`crate::BehaviorSpec::validate`]
    /// six-slot cascade (and its identity-element on the absent slot)
    /// through one call on the substrate primitive.
    ///
    /// The per-slot compound entry-gate discipline lifted here onto the
    /// M2 `:behavior` axis is the sibling of the peer per-slot compound
    /// gates ([`crate::AplicacaoSpec::validate_contratos`],
    /// [`crate::MeshPolicy::validate`],
    /// [`crate::SupervisorSpec::validate_children`],
    /// [`Self::validate_upgrade_from`], [`Self::validate_deps`],
    /// [`Self::validate_limits`]) that fold every structural + cross-
    /// slot axis on their slot onto one substrate primitive. Extended
    /// here to the M2 `:behavior` slot, the last of the four M2 typed
    /// slots (`:limits`, `:behavior`, `:upgrade-from`, plus the
    /// supervisor-only `:children` peer) whose per-Caixa compound-gate
    /// wire-up still lived open-coded at the layout altitude after the
    /// [`Self::validate_limits`] lift (baa4688) closed the sibling M2
    /// `:limits` slot's cascade. With this lift the "one named per-slot
    /// / per-Caixa compound gate per typed slot folding every structural
    /// axis on that slot (plus the `Option::None` identity element for
    /// the `Option`-shaped slots) onto one substrate primitive"
    /// discipline spans every M2 typed slot uniformly, so a reader who
    /// has learned any peer M2 gate reads `:behavior` without a per-
    /// slot exception carve-out.
    ///
    /// # Errors
    ///
    /// Returns every [`crate::BehaviorError`] variant on the present-
    /// slot arm — verbatim from [`crate::BehaviorSpec::validate`].
    /// Passes trivially on the absent-slot arm (`behavior: None`, the
    /// fold's identity element).
    pub fn validate_behavior(&self) -> Result<(), crate::BehaviorError> {
        match self.behavior() {
            Some(b) => b.validate(),
            None => Ok(()),
        }
    }

    /// Reject `:restart-window` values the shared
    /// [`crate::supervisor::duration_codec::parse`] refuses. The flat
    /// `restart_window: Option<String>` slot on [`Caixa`] is stored
    /// raw by the derive macro (the typed [`SupervisorSpec`] holds an
    /// `Option<Duration>` routed through the shared codec via `with =
    /// "duration_codec"`); the inline `Caixa → SupervisorSpec`
    /// view-construction path ([`Self::supervisor_view`]) folds the
    /// raw string through the same shared codec and soft-swallows the
    /// parse error as `None` to keep the view best-effort. Without
    /// this gate a malformed `:restart-window` (`"1.5s"` — the
    /// fractional-seconds drift class; `"1.0s"` — the decimal-shaped
    /// integer drift; `"0.5m"` — the unit-fraction drift; `"+30s"` /
    /// `"-30s"` — the leading-sign drift; `"30x"` — the unknown-unit
    /// footgun; `"abc"` — pure garbage; `""` — the empty-after-trim
    /// edge case) silently produced a `SupervisorSpec` with
    /// `restart_window: None`, indistinguishable from the canonical
    /// "omit the slot to express no reset" authoring shape — Erlang/OTP's
    /// `MaxIntensity / Period` invariant turns into a never-reset
    /// supervisor far from the source `caixa.lisp`, with no field
    /// naming the offending `:restart-window`. Lifting the gate to a
    /// Caixa-level validator mirrors the trajectory of the peer
    /// per-axis identity gates ([`Self::validate_nome`] 6c992f8,
    /// [`Self::validate_versao`] 1fdaa02, [`Self::validate_deps`]
    /// a7f0d8c) and the ABSORPTION-ROADMAP.md M2.2 test pin
    /// (line 196: "reject invalid `:restart-window` (non-duration)").
    ///
    /// Thin wrapper around [`crate::supervisor::duration_codec::parse`]
    /// (the shared codec backing `:supervisor :restart-window` as
    /// serde-routed on [`SupervisorSpec`], `:politicas :timeout`, and
    /// `:politicas :circuit-breaker :window` — all three covered by
    /// the integer-magnitude gate 1c55a2a). Maps the codec's parse
    /// error verbatim into the [`ManifestError::RestartWindowMalformed`]
    /// variant, carrying the offending raw string + a parser-shaped
    /// reason naming the canonical authoring form, so the diagnostic
    /// is self-locating (the author can grep their `caixa.lisp` for
    /// `:restart-window "<value>"` and fix it in one edit) and
    /// uniform with every other manifest-level validate diagnostic.
    /// With this gate the four `:restart-window`-shaped surfaces (the
    /// flat raw string on [`Caixa`], the typed `Option<Duration>` on
    /// [`SupervisorSpec`], the two `MeshPolicy` peer durations) are
    /// now structurally equivalent — every value past the codec is in
    /// one accepted set, by construction.
    ///
    /// `None` (the canonical "omit the slot to express no reset"
    /// shape) is accepted trivially — the gate is a no-op when the
    /// author didn't author a window. The empty string is rejected by
    /// the shared codec (its digit-only gate refuses an empty
    /// magnitude), surfacing the same `RestartWindowMalformed`
    /// diagnostic as every other rejected non-canonical shape.
    pub fn validate_restart_window(&self) -> Result<(), ManifestError> {
        let Some(s) = self.restart_window() else {
            return Ok(());
        };
        crate::supervisor::duration_codec::parse(s)
            .map(|_| ())
            .map_err(|reason| ManifestError::RestartWindowMalformed {
                restart_window: s.to_string(),
                reason,
            })
    }

    /// Compound per-`Caixa` entry gate on the Aplicacao-kind mesh-slot
    /// family — folds the paired [`crate::AplicacaoSpec::validate`]
    /// typed-shape cascade (per-slot gates on `:membros`, `:contratos`,
    /// `:entrada`, `:placement`, `:politicas`, in that declared order)
    /// plus the cross-slot self-edge gate
    /// ([`crate::aplicacao::validate_no_self_membership`], the
    /// `:membros :caixa` ≠ `:nome` invariant the typed view cannot
    /// enforce on its own because it carries the membros but not the
    /// parent `:nome`) onto one substrate primitive on [`Caixa`]. On
    /// non-Aplicacao kinds the fold is the identity element — the paired
    /// [`Self::aplicacao_view`] accessor returns `None` off the
    /// Aplicacao arm (peer with the [`Self::validate_limits`] /
    /// [`Self::validate_behavior`] M2 `Option`-arm identity element),
    /// so the gate passes trivially without touching the mesh slots.
    ///
    /// Prior to this lift the paired cascade lived only wired open-coded
    /// at the layout wire-up site
    /// ([`crate::layout::StandardLayout::verify`], caixa-core/src/layout.rs),
    /// as the three-line `let view = caixa.aplicacao_view().expect(...);
    /// view.validate() … validate_no_self_membership(...) …` pattern
    /// paired with two `.map_err(|err| LayoutError::AplicacaoViolation
    /// { caixa, issue })` wraps — every future consumer that wanted to
    /// gate the Aplicacao-shape cascade as a whole (the deferred
    /// `caixa.pleme.io/v1alpha1/Caixa` CR materializer's per-CR
    /// admission webhook re-checking `:membros` / `:contratos` after a
    /// per-slot patch, a future `feira validate --aplicacao` per-caixa
    /// admission verb, a per-Aplicacao overlay resolver) was structurally
    /// forced to either re-inline the two-dispatch cascade in lockstep
    /// with the layout wire-up (the duplication the PRIME DIRECTIVE
    /// names as a bug) or call the whole
    /// [`crate::layout::StandardLayout::verify`] pipeline and pay every
    /// peer per-Caixa gate to re-check one slot family. Post-fold each
    /// such consumer reaches the two-arm compound gate through one call
    /// on the substrate primitive.
    ///
    /// Peer to the [`crate::render::require_aplicacao_view`] compound
    /// entry gate every per-Aplicacao *renderer* routes through
    /// (3aefefb folded `validate_no_self_membership` onto the renderer
    /// path) — this gate mirrors the same fold on the *layout* path, so
    /// the two consumers of the Aplicacao-shape cascade (the author-time
    /// gate and every per-Aplicacao renderer) share one substrate
    /// primitive rather than two open-coded cascades kept in lockstep.
    /// Same lift discipline the peer per-slot compound gates
    /// ([`Self::validate_upgrade_from`] d6801df, [`Self::validate_deps`]
    /// b5dd55e, [`Self::validate_limits`] baa4688,
    /// [`Self::validate_behavior`] 0d2877a) each carry.
    ///
    /// # Errors
    ///
    /// Returns every [`crate::AplicacaoError`] variant on the present-
    /// kind arm — the typed-shape cascade's per-slot arms first
    /// (matching [`crate::AplicacaoSpec::validate`]'s declared order),
    /// then the cross-slot self-edge arm
    /// ([`crate::AplicacaoError::MembroIsSelfAplicacao`]). Passes
    /// trivially on non-Aplicacao kinds (the fold's identity element).
    pub fn validate_aplicacao_shape(&self) -> Result<(), crate::AplicacaoError> {
        let Some(view) = self.aplicacao_view() else {
            return Ok(());
        };
        view.validate()?;
        crate::aplicacao::validate_no_self_membership(self.membros(), self.nome())?;
        Ok(())
    }

    /// Reject per-entry values on the three Caixa-level code-surface
    /// path lists (`:bibliotecas`, `:exe`, `:servicos`) that the
    /// layout checker's `root.join(p)` sandbox would silently subvert.
    /// Same three structural footguns the peer
    /// [`BehaviorSpec::validate`] (b0c8389) and
    /// [`crate::UpgradeInstruction::validate`] `StateChange` arm
    /// (26da2c7) already close on the M2 `:behavior :on-*` and
    /// `:upgrade-from :state-change :script` axes, here lifted onto
    /// the three top-level code-path axes through the shared
    /// [`is_sandboxed_relative_path`] predicate:
    ///
    ///   - empty entry (`(:bibliotecas (""))` / `(:exe (""))` /
    ///     `(:servicos (""))`): `PathBuf::new()` round-trips through
    ///     [`Path::join`] as the base itself — `root.join("")` ==
    ///     `root`, so the existence check (`self.exists(&root)`)
    ///     trivially passes (the project root exists), and the layout
    ///     silently treats the project root as a biblioteca / exe /
    ///     servico entry. The `:bibliotecas` loop then hands the root
    ///     to `tatara_lisp::read` at `feira build` time as if the root
    ///     directory itself were a Lisp source file — a parse error
    ///     far from the source `caixa.lisp` with no field naming the
    ///     offending entry.
    ///   - absolute path (`(:bibliotecas ("/etc/passwd"))`):
    ///     [`Path::join`] *replaces* the base when the right-hand side
    ///     is absolute, so `root.join("/etc/passwd")` resolves to
    ///     `"/etc/passwd"` and escapes the project sandbox entirely.
    ///     The existence check then silently consults whatever the
    ///     escaped path resolves to — for `:bibliotecas`, the layout
    ///     has no `starts_with`-fence (only `:exe` is fenced under
    ///     `exe/` and `:servicos` under `servicos/`), so an absolute
    ///     `:bibliotecas` entry that happens to resolve on disk
    ///     silently passes. For `:exe` / `:servicos` the fence catches
    ///     the absolute case downstream as `ExeOutsideDir` /
    ///     `ServicoOutsideDir` (or `MissingEntry` if the absolute path
    ///     doesn't exist), but with a downstream-shaped diagnostic
    ///     that names the resolved escape path rather than the
    ///     authoring footgun at the source.
    ///   - parent-escape (`(:bibliotecas ("../sibling/x.lisp"))` /
    ///     `(:exe ("exe/../../escape.lisp"))`): a [`PathBuf`] with any
    ///     [`std::path::Component::ParentDir`] anywhere round-trips
    ///     through [`Path::join`] as a traversal above the caixa root.
    ///     The `:exe` / `:servicos` `starts_with(<dir>)` fence is
    ///     *component-aware* (not canonical-path-aware), so
    ///     `root.join("exe/../../escape.lisp")` `starts_with(exe_dir)`
    ///     is **true** even though the canonical resolution
    ///     `{parent of root}/escape.lisp` lives outside the caixa root
    ///     — the fence silently lets the parent-escape through, and
    ///     the existence check passes if that escape-target happens
    ///     to exist. Caught regardless of where the `..` sits
    ///     (leading, mid-path, trailing) so the gate matches the peer
    ///     predicate's full coverage.
    ///
    /// Same `Empty` → `Absolute` → `ParentEscape` arm-ordering every peer
    /// `is_sandboxed_relative_path` consumer follows (b0c8389 / 26da2c7);
    /// same per-slot diagnostic shape every peer per-axis path-gate
    /// exposes (`*Empty { slot }` / `*Absolute { slot, path }` /
    /// `*ParentEscape { slot, path }`). Cross-slot precedence is
    /// `:bibliotecas` → `:exe` → `:servicos` — the same declaration
    /// order [`Caixa::declared_foreign_code_slots`] uses for its
    /// canonical foreign-code-slot diagnostic, so a manifest with
    /// multiple malformed slots surfaces the lexicographically-earliest
    /// slot's diagnostic deterministically.
    ///
    /// Lifted to the typed surface as a Caixa-level validator (peer
    /// of [`Self::validate_nome`] / [`Self::validate_versao`] /
    /// [`Self::validate_deps`] / [`Self::validate_restart_window`])
    /// and wired into [`crate::StandardLayout::verify`] before the
    /// existence-check loops so the diagnostic names the offending
    /// slot at the source caixa.lisp rather than reporting a
    /// downstream `MissingEntry` / `ExeOutsideDir` /
    /// `ServicoOutsideDir` against the resolved sandbox-escape path.
    /// The fourth typed code-path surface — every author-supplied
    /// path on the manifest — is now structurally accept-shaped
    /// past validate, peer with `:behavior :on-*` and
    /// `:upgrade-from :state-change :script`.
    pub fn validate_code_paths(&self) -> Result<(), ManifestError> {
        /// Per-slot file-type contract for the three Caixa-level
        /// code-path surfaces (`:bibliotecas`, `:exe`, `:servicos`).
        /// Each variant names the predicate the per-entry file-type
        /// gate consults; [`Self::None`] opts the slot out of any
        /// file-type contract. Lifted as a typed local enum so the
        /// per-slot dispatch is exhaustive at the `match` — adding a
        /// future axis to the typed-substrate `:` slot set (the
        /// future `:assets` resource axis the M5 roadmap names, the
        /// future `:nix-flake` derivation axis the caixa-flake
        /// emitter consults) lands as one variant + one `match` arm,
        /// not a coordinated rewrite of every per-slot bool flag.
        ///
        /// Peer of the typed-substrate per-slot variant disciplines
        /// already established on this surface
        /// ([`crate::supervisor::RestartStrategy`] +
        /// [`crate::supervisor::RestartPolicy`] on the OTP-shape
        /// supervision-tree axis,
        /// [`crate::aplicacao::PlacementStrategy`] on the §III.1
        /// placement axis, [`crate::aplicacao::WitTarget`] on the
        /// `:contratos` payload-target axis): the typed `enum` is
        /// the substrate's single source of truth for the per-axis
        /// dispatch, and every consumer (the per-arm body here, the
        /// future feira-lint per-slot diagnostic renderer, the M4
        /// per-axis admission webhook) reaches for the same typed
        /// surface rather than re-deriving the partition from inline
        /// flag combinations.
        enum CodePathFileType {
            /// `:exe` — nix-build derivation output, no terminating-
            /// extension contract (the canonical `"exe/<name>"`
            /// fixtures the layout's `ExeOutsideDir` error message
            /// documents carry no extension by convention).
            None,
            /// `:bibliotecas` — tatara-lisp source files the
            /// `feira build` loop reads through `tatara_lisp::read`
            /// at parse time. Routes to [`is_lisp_extension`].
            LispSource,
            /// `:servicos` — ComputeUnit-CR YAML files the
            /// caixa-helm / caixa-flux renderers consume through
            /// `serde_yaml::from_str`. Routes to
            /// [`is_computeunit_yaml_extension`].
            ComputeUnitYaml,
        }

        // The per-slot [`CodePathFileType`] selects which axes carry the
        // lifted file-type predicate. `:bibliotecas` is the tatara-lisp
        // source axis (the `feira build` loop at
        // `caixa-feira/src/cmd/build.rs:33` reads each entry through
        // `tatara_lisp::read` at parse time) — the lifted
        // [`is_lisp_extension`] predicate gates the `.lisp` extension.
        // `:exe` is the nix-built executable surface (per the canonical
        // `"exe/<name>"`-shaped fixtures the layout's `ExeOutsideDir`
        // error message documents and every in-tree
        // `caixa_with_code_paths` positive control uses) — its file-type
        // contract is "nix-build derivation output", not a typed source
        // file, so [`CodePathFileType::None`] opts the slot out of any
        // file-type gate. `:servicos` is the `.computeunit.yaml`
        // ComputeUnit-CR axis (the peer caixa-helm / caixa-flux
        // renderers consume each entry through `serde_yaml::from_str` as
        // a typed `ComputeUnit` CR) — the lifted
        // [`is_computeunit_yaml_extension`] predicate gates the compound
        // `.computeunit.yaml` suffix. All three axes are surfaced through
        // the same iteration so the sandbox-shape + duplicate gates
        // apply uniformly; the typed file-type dispatch fires per-slot
        // exactly where the downstream consumer's accepted set demands
        // it. The third file-type variant ([`ComputeUnitYaml`]) is the
        // compounding lift on the peer 64772a9 `:bibliotecas`
        // `.lisp`-gate trajectory — the second of the three code-path
        // axes to land on a typed compound-suffix gate, with the same
        // self-locating per-slot diagnostic shape every peer per-axis
        // file-type lift uses (`*NonLispExtension { slot, path }` /
        // `*NonComputeUnitYamlExtension { slot, path }`).
        for (slot, list, file_type) in [
            (
                ":bibliotecas",
                &self.bibliotecas,
                CodePathFileType::LispSource,
            ),
            (":exe", &self.exe, CodePathFileType::None),
            (
                ":servicos",
                &self.servicos,
                CodePathFileType::ComputeUnitYaml,
            ),
        ] {
            // Per-slot set-not-multiset gate on the typed code-path axis.
            // Every peer Vec-shaped author-supplied list past validate is
            // a set, not a multiset: `:membros :caixa`
            // ([`crate::AplicacaoError::MembroDuplicate`]), `:placement
            // :clusters` ([`crate::AplicacaoError::PlacementClusterDuplicate`]),
            // `:entrada :paths` ([`crate::AplicacaoError::EntradaPathDuplicate`]),
            // `:contratos` ([`crate::AplicacaoError::ContratoDuplicate`]),
            // `:children :caixa` ([`crate::SupervisorError::DuplicateChild`]),
            // `:deps` / `:deps-dev` `:nome` ([`crate::DepError::DuplicateNome`]
            // per 359fba5), `:upgrade-from :from` ([`crate::UpgradeError::DuplicateFrom`]),
            // `:etiquetas` ([`ManifestError::EtiquetaDuplicate`] per 360a499),
            // `:autores` ([`ManifestError::AutorDuplicate`] per 86c769b) —
            // the three code-path lists are the last Vec-shaped author-
            // supplied slots on the typed Caixa surface still admitting a
            // duplicate entry silently. Scope is per-list (`:bibliotecas`
            // duplicates are flagged within `:bibliotecas`, not across
            // `:bibliotecas` ↔ `:exe`) — the same per-list scope `:deps`
            // ↔ `:deps-dev` use (a `:nome` present in both lists is a
            // legitimate dev-vs-runtime shape on the dep axis, fenced
            // separately by [`crate::dep::validate_no_self_dep`]). On the
            // code-path axis a cross-slot collision is structurally
            // impossible by the layout's `starts_with(<exe|servicos>_dir)`
            // fence — `:exe` and `:servicos` entries are confined to their
            // own directory trees, so the only way a string could appear
            // on two code-path lists is the (rare, structurally invalid)
            // case where `:bibliotecas` carries an `"exe/<x>"` or
            // `"servicos/<x>.yaml"`-shaped path.
            //
            // Without the gate three authoring footguns silently passed:
            //
            //   - `:bibliotecas ("lib/foo.lisp" "lib/foo.lisp")` — the
            //     canonical copy-paste-the-wrong-file footgun. `feira
            //     build` (`caixa-feira/src/cmd/build.rs:33`) walks the
            //     list and re-parses the same file twice, wasting work
            //     and silently masking the author's intent to declare a
            //     *second* biblioteca.
            //   - `:exe ("exe/cli" "exe/cli")` — the same footgun on the
            //     Binario surface. The future `caixa-flake` `nix flake`
            //     emitter that materializes each `:exe` entry as a flake
            //     `packages.<exe-name>` derivation would collide on the
            //     duplicate package name and surface a flake-eval error
            //     far from the source `caixa.lisp`.
            //   - `:servicos ("servicos/x.computeunit.yaml"
            //     "servicos/x.computeunit.yaml")` — the same footgun on
            //     the Servico surface. The peer `caixa-helm` / `caixa-flux`
            //     renderers already refuse `:servicos.len() != 1` with
            //     the narrower [`UnsupportedServicoCount`] diagnostic, but
            //     that diagnostic surfaces "too many servicos" without
            //     naming "duplicate entry" — the typed self-locating
            //     "which entry is the duplicate" framing only lands at
            //     this gate.
            //
            // Same `seen.insert(entry.as_str())` shape every peer per-list
            // duplicate gate uses (`:etiquetas` 360a499, `:autores`
            // 86c769b, `:deps` 359fba5) and the same "structural shape
            // checks fire before the duplicate check on the same entry"
            // ordering (a `(:bibliotecas ("" "lib/x.lisp" "lib/x.lisp"))`
            // shape surfaces the narrower [`Self::CodePathEmpty`] for the
            // empty entry first, not the duplicate on the later pair).
            let mut seen = std::collections::HashSet::new();
            for entry in list {
                let path = Path::new(entry);
                match is_sandboxed_relative_path(path) {
                    Ok(()) => {}
                    Err(PathShapeViolation::Empty) => {
                        return Err(ManifestError::CodePathEmpty { slot });
                    }
                    Err(PathShapeViolation::Absolute) => {
                        return Err(ManifestError::CodePathAbsolute {
                            slot,
                            path: path.to_path_buf(),
                        });
                    }
                    Err(PathShapeViolation::ParentEscape) => {
                        return Err(ManifestError::CodePathParentEscape {
                            slot,
                            path: path.to_path_buf(),
                        });
                    }
                }
                // The per-slot file-type gate dispatched through the
                // typed [`CodePathFileType`] selector above. Each variant
                // routes to the lifted predicate the downstream consumer
                // demands:
                //
                //   - [`LispSource`] → [`is_lisp_extension`] for
                //     `:bibliotecas` (the `feira build` loop's
                //     `tatara_lisp::read` consumer);
                //   - [`ComputeUnitYaml`] → [`is_computeunit_yaml_extension`]
                //     for `:servicos` (the caixa-helm / caixa-flux
                //     `serde_yaml::from_str` consumer's `ComputeUnit` CR
                //     accepted set);
                //   - [`None`] for `:exe` — the nix-build derivation-
                //     output axis has no terminating-extension contract.
                //
                // Fires after the sandbox-shape arms so a path that is
                // *both* sandbox-escaping and wrong-extension surfaces
                // the more fundamental sandbox-shape diagnostic first
                // (mirrors the peer `EmptyPath` → `AbsolutePath` →
                // `ParentEscape` → `NonLispExtension` arm-ordering on
                // `:behavior :on-*` c97815a, and `EmptyScript` →
                // `AbsoluteScript` → `ParentEscapeScript` →
                // `NonLispExtensionScript` on
                // `:upgrade-from :state-change :script` 33cc830), and
                // before the duplicate gate so the narrower per-entry
                // file-type shape dominates the cross-entry uniqueness
                // diagnostic (a
                // `("servicos/x.yaml" "servicos/x.yaml")` shape on
                // `:servicos` surfaces
                // `CodePathNonComputeUnitYamlExtension` on the first
                // entry rather than `CodePathDuplicate` on the pair —
                // peer with the 64772a9 `:bibliotecas`
                // `("lib/x.txt" "lib/x.txt")` ordering).
                match file_type {
                    CodePathFileType::None => {}
                    CodePathFileType::LispSource => {
                        if !is_lisp_extension(path) {
                            return Err(ManifestError::CodePathNonLispExtension {
                                slot,
                                path: path.to_path_buf(),
                            });
                        }
                    }
                    CodePathFileType::ComputeUnitYaml => {
                        if !is_computeunit_yaml_extension(path) {
                            return Err(ManifestError::CodePathNonComputeUnitYamlExtension {
                                slot,
                                path: path.to_path_buf(),
                            });
                        }
                    }
                }
                crate::render::insert_first_seen(&mut seen, entry.as_str(), || {
                    ManifestError::CodePathDuplicate {
                        slot,
                        path: path.to_path_buf(),
                    }
                })?;
            }
        }
        Ok(())
    }

    /// Reject `:etiquetas` lists with an empty entry or with two entries
    /// agreeing on the same string. `:etiquetas` is the universal
    /// registry-search-tag axis on [`Caixa`] (every kind carries the
    /// `Vec<String>` slot) and lands verbatim as the Helm chart
    /// `Chart.yaml` `keywords:` array on every Servico (caixa-helm's
    /// `build_chart_yaml` at `caixa-helm/src/lib.rs:236` folds it through
    /// a [`std::collections::BTreeSet`] alongside the four substrate-
    /// fixed tags `lareira` / `wasm` / `tatara-lisp` / `caixa-servico`).
    /// Two authoring footguns silently passed validate without this gate:
    ///
    ///   - Empty entry (`(:etiquetas (""))` — the canonical paste-from-
    ///     blank-doc footgun) rendered as `keywords: ["", "caixa-servico",
    ///     "lareira", "tatara-lisp", "wasm"]` in `Chart.yaml`. Helm's
    ///     `chart.metadata.keywords` admits the value without a strict
    ///     parser-side gate, but the empty keyword has no operational
    ///     meaning — it indexes nothing in the future caixa-registry
    ///     search axis and clutters the rendered chart with a no-op tag.
    ///   - Duplicate entries (`(:etiquetas ("demo" "demo"))` — the
    ///     copy-paste-the-wrong-tag footgun) silently passed validate
    ///     and were silently dedup'd by caixa-helm's `BTreeSet` collect
    ///     at chart render — a "second wins / one silently disappears"
    ///     shape divergent from every peer typed-graph set gate
    ///     ([`crate::AplicacaoError::MembroDuplicate`] on `:membros`,
    ///     [`crate::AplicacaoError::PlacementClusterDuplicate`] on
    ///     `:placement :clusters`, [`crate::AplicacaoError::EntradaPathDuplicate`]
    ///     on `:entrada :paths`, [`crate::AplicacaoError::ContratoDuplicate`]
    ///     on `:contratos`, [`crate::DepError::DuplicateNome`] on
    ///     `:deps` / `:deps-dev` per 359fba5, [`crate::UpgradeError::DuplicateFrom`]
    ///     on `:upgrade-from`, the per-instruction-class singularity
    ///     gates [`crate::UpgradeError::DuplicateLoadModule`] /
    ///     [`crate::UpgradeError::DuplicateStateChange`] /
    ///     [`crate::UpgradeError::DuplicateCleanup`]). The typed-graph
    ///     discipline is uniform: every Vec-shaped author-supplied list
    ///     past validate is set-not-multiset, by construction.
    ///
    /// Past the empty arm the gate enforces the chart-keyword shape
    /// predicate via [`crate::render::is_chart_keyword_shape`]: Cargo's
    /// crates.io `[package] keywords` grammar — 1..=20 bytes, starts
    /// with an ASCII letter, ASCII alphanumeric / `_` / `-`
    /// continuation. Closes the canonical paste-from-doc footguns the
    /// bare empty + duplicate arms left open: paste-from-aligned-doc
    /// whitespace (`" mesh"`, `"mesh "`), paste-from-multiline-doc
    /// newline (`"mesh\nhttp"` — the author pasted a multi-tag block
    /// into one entry instead of splitting), paste-from-Windows-CRLF-doc
    /// carriage return, CSV-list-separator confusion (`"mesh,http,grpc"`
    /// — the author meant three separate list entries), path-separator
    /// confusion (`"caixa/servico"`), namespace-suffix (`"http.1"`),
    /// leading-digit (`"1foo"`), kebab-leak (`"-foo"`), snake-leak
    /// (`"_foo"`), non-ASCII (`"café"`), and paste-from-binary-blob
    /// control bytes that would silently land as malformed search tags
    /// in the rendered Chart.yaml `keywords:` array and break the
    /// Artifact Hub keyword index lookup far from the source caixa.lisp.
    /// Mirrors the [`Self::validate_autores`] shape-predicate cascade
    /// established on the sibling universal-axis `Vec<String>` surface
    /// — the second universal-axis Vec<String> surface to land the
    /// empty-first-then-shape-then-duplicate per-entry cascade.
    ///
    /// Same empty-first cascade discipline every peer per-axis gate
    /// uses: the per-entry empty arm fires before the per-entry shape
    /// arm fires before the cross-entry duplicate arm, so an
    /// `("" "mesh" "mesh")` authoring shape surfaces the narrower
    /// [`ManifestError::EtiquetaEmpty`] (the structural "this entry
    /// has no value" defect) before either the shape or the duplicate
    /// diagnostic. Walks the list in declaration order so the
    /// first-collision diagnostic surfaces the lexicographically-
    /// earliest offending position, peer with every other duplicate
    /// gate on this surface.
    ///
    /// Universal-axis (every kind carries `:etiquetas`), so wired at the
    /// caixa-build gate alongside the peer universal gates
    /// [`Self::validate_nome`] / [`Self::validate_versao`] /
    /// [`Self::validate_deps`] / [`Self::validate_code_paths`] — before
    /// the kind-coherence gates ([`crate::LayoutError::MeshSlotsOnNonAplicacao`]
    /// / [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] /
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] /
    /// [`crate::LayoutError::ForeignCodeSlot`]) which fence kind-specific
    /// slot sets. The future caixa-registry search axis can reach for
    /// `caixa.etiquetas` knowing every entry is a non-empty distinct
    /// chart-keyword-shaped string without re-deriving the precondition.
    pub fn validate_etiquetas(&self) -> Result<(), ManifestError> {
        let mut seen = std::collections::HashSet::new();
        for etiqueta in self.etiquetas() {
            if etiqueta.is_empty() {
                return Err(ManifestError::EtiquetaEmpty);
            }
            crate::render::is_chart_keyword_shape(etiqueta).map_err(|reason| {
                ManifestError::EtiquetaInvalid {
                    etiqueta: etiqueta.clone(),
                    reason,
                }
            })?;
            crate::render::insert_first_seen(&mut seen, etiqueta.as_str(), || {
                ManifestError::EtiquetaDuplicate {
                    etiqueta: etiqueta.clone(),
                }
            })?;
        }
        Ok(())
    }

    /// Reject `:autores` lists with an empty entry or with two entries
    /// agreeing on the same string. `:autores` is the universal
    /// maintainer-axis on [`Caixa`] (every kind carries the
    /// `Vec<String>` slot) and lands verbatim as the Helm chart
    /// `Chart.yaml` `maintainers:` array on every Servico (caixa-helm's
    /// `build_chart_yaml` at `caixa-helm/src/lib.rs:251` maps each entry
    /// to a `Maintainer { name, email: None }` without dedup). Two
    /// authoring footguns silently passed validate without this gate:
    ///
    ///   - Empty entry (`(:autores (""))` — the canonical paste-from-
    ///     blank-doc footgun) rendered as
    ///     `maintainers: [{name: "", email: null}]` in `Chart.yaml`. The
    ///     empty maintainer name has no operational meaning — it
    ///     identifies no one in the substrate's authorship index and
    ///     clutters the rendered chart with a no-op maintainer.
    ///   - Duplicate entries (`(:autores ("pleme-io" "pleme-io"))` —
    ///     the copy-paste-the-wrong-author footgun) silently passed
    ///     validate and rendered as two identical maintainer entries.
    ///     Unlike the [`Self::validate_etiquetas`] peer (caixa-helm's
    ///     `BTreeSet`-collect on `:etiquetas` silently dedups the
    ///     rendered `keywords:` array at chart-render time), the
    ///     `maintainers:` rendering has *no* dedup — duplicate `:autores`
    ///     entries stack verbatim in the chart, divergent from every
    ///     peer typed-graph set gate ([`crate::AplicacaoError::MembroDuplicate`]
    ///     on `:membros`, [`crate::AplicacaoError::PlacementClusterDuplicate`]
    ///     on `:placement :clusters`, [`crate::AplicacaoError::EntradaPathDuplicate`]
    ///     on `:entrada :paths`, [`crate::AplicacaoError::ContratoDuplicate`]
    ///     on `:contratos`, [`crate::DepError::DuplicateNome`] on
    ///     `:deps` / `:deps-dev`, [`crate::UpgradeError::DuplicateFrom`]
    ///     on `:upgrade-from`, [`ManifestError::EtiquetaDuplicate`] on
    ///     `:etiquetas`).
    ///
    /// Past the empty arm the gate enforces the chart-maintainer-name
    /// shape predicate via [`crate::render::is_chart_maintainer_name_shape`]:
    /// the structural single-line printable-UTF-8 floor every realistic
    /// Helm chart maintainer name carries — 1..=128 bytes, no leading
    /// or trailing whitespace, no ASCII control characters anywhere,
    /// Unicode bytes accepted. Closes the canonical paste-from-doc
    /// footguns the bare empty + duplicate arms left open:
    /// paste-from-aligned-doc whitespace (`" pleme-io"`, `"pleme-io "`),
    /// paste-from-multiline-doc newline (`"alice\nbob"` — the author
    /// pasted a multi-line block of author records into one `:autores`
    /// entry instead of splitting into one entry per author),
    /// paste-from-Windows-CRLF-doc carriage return, tab-from-aligned-doc,
    /// and the paste-from-binary-blob control bytes that would silently
    /// land as YAML-illegal byte sequences in the rendered Chart.yaml
    /// `maintainers:` array. Mirrors the shape-predicate cascade
    /// [`Self::validate_descricao`] / [`Self::validate_licenca`] /
    /// [`Self::validate_edicao`] / [`Self::validate_repositorio`]
    /// establish past their own empty arms on the sibling universal-axis
    /// `Option<String>` surfaces — the first universal-axis Vec<String>
    /// surface to land the empty-first-then-shape-then-duplicate per-entry
    /// cascade.
    ///
    /// Same empty-first cascade discipline every peer per-axis gate
    /// uses: the per-entry empty arm fires before the per-entry shape
    /// arm before the cross-entry duplicate arm. Walks the list in
    /// declaration order so the first-collision diagnostic surfaces the
    /// lexicographically-earliest offending position, peer with every
    /// other duplicate gate on this surface.
    ///
    /// Universal-axis (every kind carries `:autores`), so wired at the
    /// caixa-build gate alongside the peer universal gates
    /// [`Self::validate_nome`] / [`Self::validate_versao`] /
    /// [`Self::validate_deps`] / [`Self::validate_etiquetas`] /
    /// [`Self::validate_code_paths`] — before the kind-coherence gates
    /// ([`crate::LayoutError::MeshSlotsOnNonAplicacao`] /
    /// [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] /
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] /
    /// [`crate::LayoutError::ForeignCodeSlot`]) which fence kind-specific
    /// slot sets.
    pub fn validate_autores(&self) -> Result<(), ManifestError> {
        let mut seen = std::collections::HashSet::new();
        for autor in self.autores() {
            if autor.is_empty() {
                return Err(ManifestError::AutorEmpty);
            }
            crate::render::is_chart_maintainer_name_shape(autor).map_err(|reason| {
                ManifestError::AutorInvalid {
                    autor: autor.clone(),
                    reason,
                }
            })?;
            crate::render::insert_first_seen(&mut seen, autor.as_str(), || {
                ManifestError::AutorDuplicate {
                    autor: autor.clone(),
                }
            })?;
        }
        Ok(())
    }

    /// Reject `:repositorio` values whose shape the shared
    /// [`crate::render::is_git_repo_url`] predicate refuses. The flat
    /// `repositorio: Option<String>` slot on [`Caixa`] is the
    /// universal git-shaped homepage axis every kind carries — the
    /// substrate routes the same string through two load-bearing
    /// consumers:
    ///
    ///   - [`caixa-helm`] folds it verbatim into the rendered
    ///     `lareira-<nome>` Helm chart's `Chart.yaml` `home:` field
    ///     (`build_chart_yaml` at `caixa-helm/src/lib.rs:268`) and into
    ///     the chart `README.md` `repo = …` interpolation
    ///     (`caixa-helm/src/lib.rs:359`).
    ///   - [`caixa-flux`] folds it verbatim into the standalone
    ///     `ClusterBundleOpts::for_caixa` `git_url:` field
    ///     (`caixa-flux/src/lib.rs:293`), which becomes the `FluxCD`
    ///     `GitRepository.spec.url` the cluster's source-controller
    ///     polls — the load-bearing deploy-time axis.
    ///
    /// Both consumers use `Option::unwrap_or_else(|| <fallback>)` to
    /// substitute a placeholder when the slot is absent (`None` → the
    /// fallback fires); a `Some("")` *skips the fallback* and silently
    /// passes the empty string through to `Chart.yaml home: ""` /
    /// `GitRepository url: ""` — Helm's chart lint and `FluxCD`'s source
    /// controller both reject the empty URL far from the source
    /// `caixa.lisp`, with no field naming the offending `:repositorio`.
    /// Similarly a malformed `:repositorio` (whitespace, control char,
    /// missing `:` separator, leading `-`) silently lands in the
    /// rendered artifacts and breaks at `git clone` / `helm template`
    /// / `flux reconcile` time.
    ///
    /// Thin wrapper around [`crate::render::is_git_repo_url`] — the
    /// same shared predicate the peer [`crate::DepSource::validate`]
    /// routes the `:fonte (:tipo git :repo …)` axis through. With this
    /// gate the two `git URL`-shaped surfaces on the typed Caixa
    /// (`:repositorio` here, `:deps :fonte :repo` peer) are
    /// structurally equivalent: every value past validate is
    /// guaranteed-acceptable by the predicate's union of constraints
    /// (non-empty, length-bounded, no leading `-`, no whitespace, no
    /// control chars, ASCII only, no leading `:`, contains a `:`
    /// separator). The predicate accepts every documented authoring
    /// shape — `github:org/repo` shorthand, `https://host/path`,
    /// `ssh://[user@]host/path`, `git://host/path`, `git@host:path`
    /// scp-style SSH, `file:///path` — and refuses the canonical
    /// paste-from-blank-doc / paste-from-multiline-doc / CLI-arg-
    /// injection footguns at validate time. Maps the predicate's
    /// `String` reason verbatim into the
    /// [`ManifestError::RepositorioInvalid`] variant, carrying the
    /// offending value + parser-shaped reason so the diagnostic is
    /// self-locating (the author can grep their `caixa.lisp` for
    /// `:repositorio "<value>"` and fix it in one edit).
    ///
    /// `None` (the canonical "omit the slot to express no published
    /// homepage" shape) is accepted trivially — the gate is a no-op
    /// when the author didn't declare a value. `Some("")` is gated by
    /// the narrower [`ManifestError::RepositorioEmpty`] arm before the
    /// shape predicate is consulted, mirroring the empty-first cascade
    /// every peer per-axis identity gate uses
    /// ([`ManifestError::NomeEmpty`] → [`ManifestError::NomeInvalid`],
    /// [`ManifestError::VersaoEmpty`] → [`ManifestError::VersaoInvalid`],
    /// [`crate::DepError::FonteRepoEmpty`] →
    /// [`crate::DepError::FonteRepoInvalid`]).
    ///
    /// Universal-axis (every kind carries `:repositorio`), so wired at
    /// the caixa-build gate alongside the peer universal gates
    /// [`Self::validate_nome`] / [`Self::validate_versao`] /
    /// [`Self::validate_deps`] / [`Self::validate_etiquetas`] /
    /// [`Self::validate_autores`] / [`Self::validate_code_paths`] —
    /// before the kind-coherence gates
    /// ([`crate::LayoutError::MeshSlotsOnNonAplicacao`] /
    /// [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] /
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] /
    /// [`crate::LayoutError::ForeignCodeSlot`]) which fence kind-
    /// specific slot sets.
    pub fn validate_repositorio(&self) -> Result<(), ManifestError> {
        let Some(s) = self.repositorio() else {
            return Ok(());
        };
        if s.is_empty() {
            return Err(ManifestError::RepositorioEmpty);
        }
        is_git_repo_url(s).map_err(|reason| ManifestError::RepositorioInvalid {
            repositorio: s.to_string(),
            reason,
        })
    }

    /// Reject `:descricao` values that are the empty string. The flat
    /// `descricao: Option<String>` slot on [`Caixa`] is the universal
    /// free-form-prose homepage axis every kind carries — the
    /// substrate routes the same string through two load-bearing
    /// consumers in the [`caixa-helm`] renderer:
    ///
    ///   - `build_chart_yaml` folds it verbatim into the rendered
    ///     `lareira-<nome>` Helm chart's `Chart.yaml` `description:`
    ///     field (`caixa-helm/src/lib.rs:232-235`).
    ///   - `build_readme` folds it verbatim into the rendered chart
    ///     `README.md` header (`caixa-helm/src/lib.rs:333-336`).
    ///
    /// Both consumers use `Option::unwrap_or_else(|| <fallback>)` to
    /// substitute a `caixa.nome`-derived placeholder when the slot is
    /// absent (`None` → the fallback fires); a `Some("")` *skips the
    /// fallback* and silently passes the empty string through to
    /// `Chart.yaml description: ""` / a blank chart `README.md`
    /// header. Helm's chart spec requires a non-empty `description:`
    /// field on `apiVersion: v2` charts (`helm lint` surfaces it as
    /// `WARNING [chart.metadata.description]: description is required`),
    /// so the empty `Some("")` silently lands in the rendered
    /// artifacts and breaks at `helm lint` / `helm install` time far
    /// from the source `caixa.lisp`, with no field naming the
    /// offending `:descricao`.
    ///
    /// `None` (the canonical "omit the slot to defer to the renderer's
    /// `caixa.nome`-derived fallback" shape) is accepted trivially —
    /// the gate is a no-op when the author didn't declare a value.
    /// `Some("")` is gated by the narrower
    /// [`ManifestError::DescricaoEmpty`] arm, mirroring the empty-arm
    /// shape every peer per-axis empty gate uses
    /// ([`ManifestError::NomeEmpty`], [`ManifestError::VersaoEmpty`],
    /// [`ManifestError::EtiquetaEmpty`], [`ManifestError::AutorEmpty`],
    /// [`ManifestError::RepositorioEmpty`]).
    ///
    /// Universal-axis (every kind carries `:descricao`), so wired at
    /// the caixa-build gate alongside the peer universal gates
    /// [`Self::validate_nome`] / [`Self::validate_versao`] /
    /// [`Self::validate_deps`] / [`Self::validate_etiquetas`] /
    /// [`Self::validate_autores`] / [`Self::validate_repositorio`] /
    /// [`Self::validate_code_paths`] — before the kind-coherence
    /// gates ([`crate::LayoutError::MeshSlotsOnNonAplicacao`] /
    /// [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] /
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] /
    /// [`crate::LayoutError::ForeignCodeSlot`]) which fence kind-
    /// specific slot sets.
    ///
    /// Past the empty arm the gate enforces the chart-description
    /// shape predicate via [`crate::render::is_chart_description_shape`]:
    /// the structural single-line UTF-8 floor every realistic chart
    /// description in the wild matches — 1..=512 bytes, no leading
    /// or trailing whitespace, no ASCII control characters anywhere
    /// (`0x00..=0x1F` plus `0x7F` DEL — banning tab, newline,
    /// carriage return, and every other control byte), Unicode
    /// continuation bytes accepted (the canonical fixtures carry
    /// `→` and `—`). Closes the canonical paste-from-doc footguns
    /// the bare empty-arm gate left open: paste-from-aligned-doc
    /// leading / trailing whitespace (`" Checkout flow."`,
    /// `"Checkout flow. "`), paste-from-multiline-doc newline
    /// (`"Checkout\nflow."`), paste-from-Windows-CRLF-doc CR
    /// (`"Checkout\rflow."`), tab-from-aligned-doc
    /// (`"Checkout\tflow."`), and paste-from-binary-blob NUL / BEL /
    /// ESC / DEL bytes. Mirrors the shape-predicate cascade
    /// [`Self::validate_repositorio`] / [`Self::validate_licenca`] /
    /// [`Self::validate_edicao`] establish past their own empty arms
    /// on the sibling universal-axis `Option<String>` Caixa-level
    /// value-shape surfaces.
    ///
    /// The empty-first cascade discipline mirrors every peer per-axis
    /// identity gate: [`ManifestError::DescricaoEmpty`] runs before
    /// [`ManifestError::DescricaoInvalid`], so the narrower empty
    /// diagnostic surfaces on `Some("")` rather than the broader
    /// shape-predicate diagnostic — peer with how
    /// [`ManifestError::LicencaEmpty`] runs before
    /// [`ManifestError::LicencaInvalid`],
    /// [`ManifestError::EdicaoEmpty`] runs before
    /// [`ManifestError::EdicaoInvalid`],
    /// [`ManifestError::RepositorioEmpty`] runs before
    /// [`ManifestError::RepositorioInvalid`].
    pub fn validate_descricao(&self) -> Result<(), ManifestError> {
        let Some(s) = self.descricao() else {
            return Ok(());
        };
        if s.is_empty() {
            return Err(ManifestError::DescricaoEmpty);
        }
        crate::render::is_chart_description_shape(s).map_err(|reason| {
            ManifestError::DescricaoInvalid {
                descricao: s.to_string(),
                reason,
            }
        })?;
        Ok(())
    }

    /// Reject `:licenca` values that are the empty string. The flat
    /// `licenca: Option<String>` slot on [`Caixa`] is the universal
    /// SPDX-shaped license-expression axis every kind carries — the
    /// substrate routes the same string through the [`caixa-helm`]
    /// renderer's `build_readme` which folds it verbatim into the
    /// rendered `lareira-<nome>` Helm chart's `README.md` `## License`
    /// section (`caixa-helm/src/lib.rs:361`) via
    /// `caixa.licenca.clone().unwrap_or_else(|| "MIT".into())`. The
    /// fallback only fires on `None`; a `Some("")` *skips the
    /// fallback* and silently passes the empty string through to a
    /// chart `README.md` whose `License` section renders as the bare
    /// trailing period (`.\n`) — peer footgun with the
    /// `Some("")`-skips-`unwrap_or_else` shape the
    /// [`Self::validate_descricao`] and [`Self::validate_repositorio`]
    /// gates close on the sibling free-form-prose and git-URL axes.
    ///
    /// `None` (the canonical "omit the slot to defer to the
    /// renderer's `MIT` fallback" shape every existing fixture
    /// carries) is accepted trivially — the gate is a no-op when the
    /// author didn't declare a value. `Some("")` is gated by the
    /// narrower [`ManifestError::LicencaEmpty`] arm, mirroring the
    /// empty-arm shape every peer per-axis empty gate uses
    /// ([`ManifestError::NomeEmpty`], [`ManifestError::VersaoEmpty`],
    /// [`ManifestError::EtiquetaEmpty`], [`ManifestError::AutorEmpty`],
    /// [`ManifestError::RepositorioEmpty`],
    /// [`ManifestError::DescricaoEmpty`]).
    ///
    /// Universal-axis (every kind carries `:licenca`), so wired at
    /// the caixa-build gate alongside the peer universal gates
    /// [`Self::validate_nome`] / [`Self::validate_versao`] /
    /// [`Self::validate_deps`] / [`Self::validate_etiquetas`] /
    /// [`Self::validate_autores`] / [`Self::validate_repositorio`] /
    /// [`Self::validate_descricao`] / [`Self::validate_code_paths`]
    /// — before the kind-coherence gates
    /// ([`crate::LayoutError::MeshSlotsOnNonAplicacao`] /
    /// [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] /
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] /
    /// [`crate::LayoutError::ForeignCodeSlot`]) which fence kind-
    /// specific slot sets.
    ///
    /// Past the empty arm the gate enforces the SPDX-expression shape
    /// predicate via [`crate::render::is_spdx_expression_shape`]: the
    /// structural alphabet floor every realistic SPDX expression in
    /// the wild uses — ASCII alphanumeric plus `.`, `-`, `+`, `(`,
    /// `)`, `:` (the `DocumentRef-…:LicenseRef-…` separator), and a
    /// single ASCII space (token separator). Closes the canonical
    /// paste-from-doc footguns the bare empty-arm gate left open:
    /// paste-from-doc whitespace (`"MIT "`, `" MIT"`), paste-from-
    /// multiline-doc CRLF (`"MIT\n"`), tab-from-aligned-doc
    /// (`"MIT\tOR Apache-2.0"`), non-ASCII smart-quote paste,
    /// underscore-instead-of-hyphen typo (`"Apache_2.0"`),
    /// comma-instead-of-`OR`-keyword colloquial idiom (`"MIT,
    /// Apache-2.0"`), slash-dual-license colloquial idiom (`"MIT/
    /// Apache-2.0"`), and semicolon-list-separator confusion
    /// (`"MIT; Apache-2.0"`). Mirrors the shape-predicate cascade
    /// [`Self::validate_repositorio`] / [`Self::validate_edicao`]
    /// establish past their own empty arms.
    ///
    /// The empty-first cascade discipline mirrors every peer per-axis
    /// identity gate: [`ManifestError::LicencaEmpty`] runs before
    /// [`ManifestError::LicencaInvalid`], so the narrower empty
    /// diagnostic surfaces on `Some("")` rather than the broader
    /// shape-predicate diagnostic — peer with how
    /// [`ManifestError::EdicaoEmpty`] runs before
    /// [`ManifestError::EdicaoInvalid`],
    /// [`ManifestError::RepositorioEmpty`] runs before
    /// [`ManifestError::RepositorioInvalid`].
    ///
    /// A future tightening on this axis can extend the alphabet
    /// floor into a full SPDX expression parser + license-id
    /// allowlist (rejecting alphabet-valid values that don't name a
    /// real SPDX license identifier — e.g., `"NotAReal"` is
    /// alphabet-valid but no `NotAReal` license-id exists). That
    /// parser only becomes meaningful past a real SPDX-spec
    /// dependency; this gate establishes the structural floor by
    /// refusing every non-SPDX-alphabet value at validate time.
    pub fn validate_licenca(&self) -> Result<(), ManifestError> {
        let Some(s) = self.licenca() else {
            return Ok(());
        };
        if s.is_empty() {
            return Err(ManifestError::LicencaEmpty);
        }
        crate::render::is_spdx_expression_shape(s).map_err(|reason| {
            ManifestError::LicencaInvalid {
                licenca: s.to_string(),
                reason,
            }
        })?;
        Ok(())
    }

    /// Reject `:edicao` values that are the empty string. The flat
    /// `edicao: Option<String>` slot on [`Caixa`] is the universal
    /// language-edition axis every kind carries — it determines the
    /// tatara-lisp macro surface + compatibility flags the substrate
    /// applies when building a caixa, and lands verbatim in the
    /// `Caixa::template` author-time scaffold (the canonical
    /// `:edicao "2026"` line every `feira init` emits via
    /// [`Caixa::template`] at `caixa-core/src/manifest.rs:1193`) and
    /// in every renderer-side fixture (`caixa-helm/src/lib.rs:375`,
    /// `caixa-flux/src/lib.rs:445`, `caixa-mesh/src/lib.rs:629`,
    /// `caixa-core/src/render.rs:2510`) via
    /// `edicao: Some("2026".into())`.
    ///
    /// `None` (the canonical "omit the slot to defer to the
    /// substrate's default edition" shape every existing
    /// [`caixa-resolver`] integration test fixture carries via
    /// `edicao: None` — see `caixa-resolver/tests/git_integration.rs`)
    /// is accepted trivially — the gate is a no-op when the author
    /// didn't declare a value. `Some("")` is gated by the narrower
    /// [`ManifestError::EdicaoEmpty`] arm, mirroring the empty-arm
    /// shape every peer per-axis empty gate uses
    /// ([`ManifestError::NomeEmpty`], [`ManifestError::VersaoEmpty`],
    /// [`ManifestError::EtiquetaEmpty`], [`ManifestError::AutorEmpty`],
    /// [`ManifestError::RepositorioEmpty`],
    /// [`ManifestError::DescricaoEmpty`], [`ManifestError::LicencaEmpty`]).
    ///
    /// Universal-axis (every kind carries `:edicao`), so wired at
    /// the caixa-build gate alongside the peer universal gates
    /// [`Self::validate_nome`] / [`Self::validate_versao`] /
    /// [`Self::validate_deps`] / [`Self::validate_etiquetas`] /
    /// [`Self::validate_autores`] / [`Self::validate_repositorio`] /
    /// [`Self::validate_descricao`] / [`Self::validate_licenca`] /
    /// [`Self::validate_code_paths`] — before the kind-coherence
    /// gates ([`crate::LayoutError::MeshSlotsOnNonAplicacao`] /
    /// [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] /
    /// [`crate::LayoutError::ServicoSlotsOnNonServico`] /
    /// [`crate::LayoutError::ForeignCodeSlot`]) which fence kind-
    /// specific slot sets.
    ///
    /// Past the empty arm the gate enforces the canonical year-shape
    /// predicate: every documented tatara-lisp edition is a 4-digit
    /// ASCII decimal year (`"2026"` is the only edition currently
    /// minted; future-introduced siblings will follow the same
    /// shape, peer with Cargo's `[package] edition` grammar which
    /// every value Cargo has ever accepted matches — `"2015"`,
    /// `"2018"`, `"2021"`, `"2024"`). Any value that's not exactly
    /// 4 ASCII decimal bytes is rejected with the narrower
    /// [`ManifestError::EdicaoInvalid`] arm, mirroring the
    /// shape-predicate cascade [`Self::validate_repositorio`]
    /// establishes past its own empty arm
    /// ([`ManifestError::RepositorioEmpty`] →
    /// [`ManifestError::RepositorioInvalid`]). Closes the canonical
    /// paste-from-doc footguns the bare empty-arm gate left open:
    ///
    ///   - leading / trailing whitespace from a paste-from-doc
    ///     (`"2026 "`, `" 2026"`)
    ///   - control characters / CRLF from a paste-from-multiline-doc
    ///     (`"2026\n"`)
    ///   - non-ASCII look-alikes from a fullwidth keyboard
    ///     (`"２０２６"`) which would silently land as a non-ASCII
    ///     string in the rendered caixa.lisp
    ///   - free-form non-year values (`"x"`, `"latest"`,
    ///     `"nightly"`) that have no operational meaning on the
    ///     substrate's build-time edition selector
    ///   - leading non-digit prefixes (`"v2026"`, `"e2026"`,
    ///     `"r2026"`) — common version-tag idioms that don't apply
    ///     to the year-shaped edition axis
    ///   - decimal-shaped values (`"2026.1"`, `"2026.0"`) — every
    ///     edition is a year, not a fractional version
    ///   - wrong-length numeric values (`"26"`, `"202"`, `"20260"`,
    ///     `"00026"`) that don't name a year
    ///
    /// `None` (the canonical "omit the slot to defer to the
    /// substrate's default edition" shape every existing
    /// [`caixa-resolver`] integration test fixture carries via
    /// `edicao: None` — see `caixa-resolver/tests/git_integration.rs`)
    /// is accepted trivially — the gate is a no-op when the author
    /// didn't declare a value. The empty-first cascade discipline
    /// mirrors every peer per-axis identity gate:
    /// [`ManifestError::EdicaoEmpty`] runs before
    /// [`ManifestError::EdicaoInvalid`], so the narrower empty
    /// diagnostic surfaces on `Some("")` rather than the broader
    /// shape-predicate diagnostic — peer with how
    /// [`ManifestError::NomeEmpty`] runs before
    /// [`ManifestError::NomeInvalid`],
    /// [`ManifestError::VersaoEmpty`] runs before
    /// [`ManifestError::VersaoInvalid`],
    /// [`ManifestError::RepositorioEmpty`] runs before
    /// [`ManifestError::RepositorioInvalid`].
    ///
    /// A future tightening on this axis can extend the shape
    /// predicate into a known-edition allowlist (rejecting
    /// year-shaped values that don't name a tatara-lisp edition
    /// the substrate actually understands — e.g., `"1999"` is
    /// year-shaped but no `1999` edition exists). That allowlist
    /// only becomes meaningful past the introduction of a sibling
    /// edition to `"2026"`; this gate establishes the structural
    /// floor by refusing every non-year-shaped value at validate
    /// time.
    pub fn validate_edicao(&self) -> Result<(), ManifestError> {
        let Some(s) = self.edicao() else {
            return Ok(());
        };
        if s.is_empty() {
            return Err(ManifestError::EdicaoEmpty);
        }
        if s.len() != 4 || !s.bytes().all(|b| b.is_ascii_digit()) {
            return Err(ManifestError::EdicaoInvalid {
                edicao: s.to_string(),
                reason: "must be a 4-digit ASCII decimal year (canonical \"2026\")".to_string(),
            });
        }
        Ok(())
    }

    /// Compose the supervisor-related flat slots into a single
    /// [`SupervisorSpec`] for validation. Returns `None` when the
    /// caixa isn't a `:kind Supervisor`.
    ///
    /// The flat representation in [`Caixa`] keeps tatara-lisp authoring
    /// simple (one form, no nested `:supervisor (…)` block); this view
    /// is the "typed shape" the operator + supervisor reconciler
    /// consume.
    #[must_use]
    pub fn supervisor_view(&self) -> Option<SupervisorSpec> {
        if !self.kind().is_supervisor() {
            return None;
        }
        // Fold through the shared `supervisor::duration_codec::parse`
        // — the same parser the serde-routed `with = "duration_codec"`
        // on `SupervisorSpec::restart_window`, the `:politicas
        // :timeout` codec, and the `:politicas :circuit-breaker
        // :window` codec all consume. The prior inline f64-shaped
        // duplicate (`parse_window_inline`) admitted every magnitude
        // the integer-magnitude gate (1c55a2a) rejects on the three
        // serde-routed siblings — `"1.5s"`, `"1.0s"`, `"0.5m"`,
        // `"+30s"`, `"-30s"` — and silently dropped malformed input as
        // `None` (i.e. "no reset"), divergent from the shared codec's
        // integer-magnitude discipline by construction. The fold
        // closes the divergence: every value the typed
        // `SupervisorSpec` carries past `supervisor_view` is in the
        // shared codec's accepted set. The `.ok()` here preserves the
        // existing soft-swallow shape on this view-construction path;
        // the new [`Caixa::validate_restart_window`] (sibling of
        // [`Self::validate_nome`] / [`Self::validate_versao`]) names
        // the offending raw string at build time so authoring tools
        // (`feira lint`, the future layout-side wire-up) surface a
        // self-locating diagnostic instead of a silently dropped
        // window.
        let restart_window = self
            .restart_window()
            .and_then(|s| crate::supervisor::duration_codec::parse(s).ok());
        Some(SupervisorSpec {
            // Route the author-omitted `:estrategia` arm through the
            // substrate-canonical
            // [`crate::supervisor::SUPERVISOR_ESTRATEGIA_DEFAULT`] typed
            // `pub const` rather than the transitively-derived
            // [`RestartStrategy::default`] route the prior
            // `.unwrap_or_default()` fold reached for — one source of
            // truth for the Erlang/OTP `one_for_one` half of Learn You
            // Some Erlang's `{one_for_one, intensity, 5, 60}` worker-
            // supervisor canonical default that also backs the
            // [`crate::supervisor::Default for RestartStrategy`] impl
            // and the [`crate::supervisor::Default for SupervisorSpec`]
            // impl's struct-literal `estrategia` field, all now routed
            // through the same lifted constant. Prior to the lift the
            // composition site carried `.unwrap_or_default()` with no
            // compile-time link back to the shared OTP-canonical
            // default that the peer paired
            // `.unwrap_or(SUPERVISOR_MAX_RESTARTS_DEFAULT)` (b698ec0)
            // arm on the sibling `:max-restarts` axis routes through —
            // so a future rebrand of the OTP-canonical strategy default
            // (a widening to `rest_for_one` once the substrate
            // discovers startup-order-coupled child cohorts as the more
            // common shape, a per-cluster overlay the operator pins
            // through the MESH-COMPOSITION §III.2 supervision-canary
            // `:estrategia-overrides` roadmap slot) would have had to
            // migrate the paired `MaxIntensity` + `Period` halves
            // through the lifted constants and the `one_for_one` half
            // through a `RestartStrategy::default()` route in lockstep
            // or the three halves of the same OTP-canonical default
            // would silently drift out of pairing. Byte-parity against
            // the lifted constant closes the split. Pinned by
            // [`supervisor_view_estrategia_fallback_routes_through_lifted_default`]
            // in the tests module.
            estrategia: self
                .estrategia()
                .unwrap_or(crate::supervisor::SUPERVISOR_ESTRATEGIA_DEFAULT),
            // Route the author-omitted `:max-restarts` arm through the
            // substrate-canonical [`crate::supervisor::SUPERVISOR_MAX_RESTARTS_DEFAULT`]
            // typed `pub const` rather than the raw `5` literal — one
            // source of truth for the Erlang/OTP-canonical
            // `{intensity, 5, 60}` `MaxIntensity` default that also
            // backs the serde-side wire-format author-omitted arm on
            // [`crate::supervisor::SupervisorSpec::max_restarts`] via
            // `#[serde(default = "default_max_restarts")]` and the
            // [`Default for SupervisorSpec`] impl's struct-literal
            // default field. Prior to the lift the composition site
            // carried a raw `5` with no compile-time link back to the
            // serde-side default, so a future rebrand of the OTP-
            // canonical default (a tightening to Elixir's `3`, a
            // widening to a per-cluster overlay the operator pins
            // through the MESH-COMPOSITION §III.2 supervision-canary
            // `:supervisor :max-restarts-overrides` roadmap slot)
            // would have had to be threaded through both open-coded
            // copies in lockstep or the wire-format author-omitted arm
            // and this view-construction author-omitted arm would
            // silently disagree on which restart-budget an omitted
            // `:max-restarts` resolves to. Pinned by
            // [`supervisor_view_max_restarts_fallback_routes_through_lifted_default`]
            // in the tests module.
            max_restarts: self
                .max_restarts()
                .unwrap_or(crate::supervisor::SUPERVISOR_MAX_RESTARTS_DEFAULT),
            restart_window,
            children: self.children().to_vec(),
        })
    }

    /// A minimal starter manifest emitted by `feira init`.
    #[must_use]
    pub fn template(nome: &str) -> String {
        format!(
            "(defcaixa\n  \
               :nome        {nome:?}\n  \
               :versao      \"0.1.0\"\n  \
               :kind        Biblioteca\n  \
               :edicao      \"2026\"\n  \
               :descricao   \"FIXME — describe this caixa\"\n  \
               :autores     ()\n  \
               :etiquetas   ()\n  \
               :deps        ()\n  \
               :deps-dev    ()\n  \
               :bibliotecas (\"lib/{nome}.lisp\"))\n"
        )
    }

    /// Serialize to a canonical `caixa.lisp` source — suitable for writing
    /// back after mutation (e.g. `feira add`).
    ///
    /// Goes through serde JSON → canonical Sexp → per-field pretty print.
    /// The derive-macro `compile_from_sexp` path is the inverse, so any
    /// `Caixa` round-trips through `to_lisp` + `from_lisp`.
    #[must_use]
    pub fn to_lisp(&self) -> String {
        let json = serde_json::to_value(self).expect("Caixa serialize");
        let sexp = tatara_lisp::domain::json_to_sexp(&json);
        let tatara_lisp::Sexp::List(items) = sexp else {
            return format!("(defcaixa {sexp})\n");
        };
        let mut out = String::from("(defcaixa");
        let mut i = 0;
        while i + 1 < items.len() {
            out.push_str("\n  ");
            out.push_str(&items[i].to_string());
            out.push(' ');
            out.push_str(&items[i + 1].to_string());
            i += 2;
        }
        out.push_str(")\n");
        out
    }
}

/// Errors raised by top-level [`Caixa`] validators that don't fit
/// the per-axis [`DepError`] / [`crate::AplicacaoError`] /
/// [`crate::SupervisorError`] / [`crate::LayoutError`] families —
/// the Caixa's own identity axes (`:nome`, `:versao`) that flow
/// through every substrate-side artifact's `metadata.name` /
/// version derivation.
///
/// A future top-level sum (the M4 `CaixaError` the [`DepError`]
/// doc-comment anticipates) can hold one of each per-axis error
/// family without reshaping individual diagnostics; this enum is
/// the first such per-Caixa-identity family.
#[derive(Debug, Error, PartialEq, Eq)]
pub enum ManifestError {
    #[error(
        ":nome is empty (every caixa must name itself; the value flows \
         into every K8s artifact's `metadata.name` derivation and into \
         the default `lib/<nome>.lisp` / `exe/<nome>` layout paths)"
    )]
    NomeEmpty,
    #[error(
        ":nome {nome:?} is not a valid DNS-1123 label: {reason} (the K8s \
         apiserver enforces this rule on every `metadata.name` the \
         caixa's substrate-side renderers derive from `:nome` — the \
         `lareira-<nome>` Helm chart name, the programs.yaml entry \
         name, the `LABEL_APLICACAO` label value, the `<aplicacao>-<de>-to-<para>` \
         CiliumNetworkPolicy name, the `<aplicacao>-<para>` HTTPRoute \
         name; use a lowercase alphanumeric + hyphen identifier like \
         `\"checkout\"` or `\"cart-v2\"`)"
    )]
    NomeInvalid { nome: String, reason: String },
    #[error(
        ":nome {nome:?} overflows the joint-length budget on the canonical \
         `lareira-<nome>` chart-name shape: {reason} (every per-Servico / \
         per-Aplicacao renderer the substrate carries — `caixa-helm`'s \
         `Chart.yaml::name`, `caixa-flux`'s `cluster_bundle` HelmRelease \
         `chart:` slot, `caixa-tatara`'s `release_name` + \
         `oci://<registry>/lareira-<nome>` chart ref — derives the same \
         joint name through the canonical `lareira_chart_name` helper, and \
         Helm's `Chart.yaml::name` admission rule + the K8s apiserver's \
         DNS-1123 label cap on every chart-name-derived `metadata.name` \
         reject any joint name exceeding 63 bytes; the narrower \
         `:nome` shape (`NomeInvalid`) gates the bare-`:nome` budget, this \
         arm gates the chart-name budget downstream renderers inherit)"
    )]
    NomeChartNameBudgetExceeded { nome: String, reason: String },
    #[error(
        ":versao is empty (every caixa must pin its own version; the value flows \
         into the `lareira-<nome>` Helm chart's `Chart.yaml` version + appVersion, \
         the `feira publish` `v<versao>` git tag, the OCI image's `:v<versao>` / \
         `:latest` tags, the lacre closure's `concrete_versao`, and the \
         `:upgrade-from :from` peers — use a SemVer-2 literal like `\"0.1.0\"`)"
    )]
    VersaoEmpty,
    #[error(
        ":versao {versao:?} is not a valid SemVer-2 version: {reason} (the substrate \
         consumes this string as `semver::Version` — three-part `MAJOR.MINOR.PATCH` \
         with optional `-prerelease` and `+build` — across every artifact derived \
         from `:versao`: the `lareira-<nome>` Helm chart's `Chart.yaml` version + \
         appVersion (Helm SemVer-2-strict), the `feira publish` `v<versao>` git tag, \
         the OCI image's `:v<versao>` tag, the lacre closure's `concrete_versao`, \
         and the `:upgrade-from :from` peers that match against this exact shape; \
         use a literal like `\"0.1.0\"`, `\"0.2.0-rc.1\"`, or `\"1.0.0+build.42\"` — \
         not a git-tag-shape like `\"v0.1.0\"`, a docker-tag-shape like `\"latest\"`, \
         a requirement-shape like `\"^0.1\"`, or a four-part `\"0.1.0.0\"`)"
    )]
    VersaoInvalid { versao: String, reason: String },
    #[error(
        ":restart-window {restart_window:?} is not a valid duration: {reason} (the \
         substrate consumes this string through the shared \
         `supervisor::duration_codec` — the same parser routed via `with = \
         \"duration_codec\"` onto the typed `SupervisorSpec::restart_window`, \
         `:politicas :timeout`, and `:politicas :circuit-breaker :window` slots; \
         the canonical authoring form is `<integer><unit>` where the unit is one \
         of `ms` / `s` / `m` / `h` and the magnitude has no decimal point and no \
         leading `+` / `-` sign — e.g. `\"60s\"`, `\"5m\"`, `\"1h\"`, `\"500ms\"`. \
         Without this gate a malformed `:restart-window` silently produced a \
         supervisor with `restart_window: None` (\"never reset\"), turning OTP's \
         `MaxIntensity / Period` invariant into a never-reset supervisor far from \
         the source `caixa.lisp`; the gate moves the diagnostic to the manifest \
         layer with the offending value named verbatim. Omit the slot entirely to \
         express \"no reset\"; carry a positive integer duration to express the \
         sliding window)"
    )]
    RestartWindowMalformed {
        restart_window: String,
        reason: String,
    },
    #[error(
        "{slot} entry is an empty path string — every {slot} entry must name \
         a file relative to the caixa root; omit the entry to omit the file \
         (the layout checker's `root.join(\"\")` resolves to the caixa root \
         itself, so an empty entry silently aliases the project root as a \
         declared {slot} file, then fails downstream at parse / existence \
         time with a diagnostic that names the root rather than the offending \
         entry)"
    )]
    CodePathEmpty { slot: &'static str },
    #[error(
        "{slot} entry {} is an absolute path — entries must be relative to \
         the caixa root, since `Path::join` replaces the base with an absolute \
         right-hand side and `root.join(\"/abs/...\")` resolves to \"/abs/...\" \
         outside the caixa root sandbox; rewrite the entry as a relative path \
         under the caixa root (e.g. `\"lib/<name>.lisp\"`, `\"exe/<name>\"`, \
         `\"servicos/<name>.computeunit.yaml\"`)",
        path.display()
    )]
    CodePathAbsolute { slot: &'static str, path: PathBuf },
    #[error(
        "{slot} entry {} contains a `..` component — entries must not traverse \
         above the caixa root (the layout's `starts_with(<dir>)` fence on \
         `:exe` / `:servicos` is component-aware, not canonical-path-aware, \
         so a mid-path `..` silently traverses the sandbox; `:bibliotecas` \
         has no such fence, so a leading `..` escapes unconditionally if the \
         resolved target happens to exist)",
        path.display()
    )]
    CodePathParentEscape { slot: &'static str, path: PathBuf },
    #[error(
        "{slot} entry {} does not terminate in the `.lisp` extension — every \
         `:bibliotecas` entry is a tatara-lisp source file the `feira build` \
         loop reads through `tatara_lisp::read` at parse time, so any other \
         extension (`.rs`, `.txt`, `.lisp.bak`) or no-extension shape is \
         structurally a parser error far from the source caixa.lisp, with \
         no field naming the offending `:bibliotecas` entry. Pin a relative \
         path under the caixa root whose terminating extension is \
         lowercase-`.lisp` (e.g. `\"lib/<name>.lisp\"`, \
         `\"lib/handlers.lisp\"`) — the same file-type contract the peer \
         `:behavior :on-*` (c97815a) and `:upgrade-from :state-change :script` \
         (33cc830) axes already carry through the same lifted \
         `is_lisp_extension` predicate",
        path.display()
    )]
    CodePathNonLispExtension { slot: &'static str, path: PathBuf },
    #[error(
        "{slot} entry {} does not terminate in the `.computeunit.yaml` \
         compound suffix — every `:servicos` entry is a typed `ComputeUnit` \
         CR YAML file the peer caixa-helm / caixa-flux renderers consume \
         through `serde_yaml::from_str` at chart / FluxCD bundle render \
         time, so any other extension (`.yaml`, `.yml`, `.json`, the \
         off-by-one-segment `.computeunit-yaml`, the editor-backup \
         `.computeunit.yaml.bak`) or no-extension shape is structurally a \
         YAML-parser error / `ComputeUnit` schema-mismatch far from the \
         source caixa.lisp, with no field naming the offending `:servicos` \
         entry. Pin a relative path under the caixa root whose terminating \
         compound suffix is lowercase-`.computeunit.yaml` (e.g. \
         `\"servicos/<name>.computeunit.yaml\"`, \
         `\"servicos/hello-rio.computeunit.yaml\"`) — the same file-type \
         contract the sibling `:bibliotecas` axis (64772a9) already carries \
         on the tatara-lisp-source axis through the peer lifted \
         `is_lisp_extension` predicate, here on the compound-suffix axis \
         `Path::extension` can't express on its own through the lifted \
         `is_computeunit_yaml_extension` predicate",
        path.display()
    )]
    CodePathNonComputeUnitYamlExtension { slot: &'static str, path: PathBuf },
    #[error(
        "{slot} entry {} appears more than once (the code-path list is \
         a set, not a multiset; every peer Vec-shaped author-supplied \
         list past validate is set-not-multiset — `:membros :caixa`, \
         `:placement :clusters`, `:entrada :paths`, `:contratos`, \
         `:children :caixa`, `:deps` / `:deps-dev` `:nome`, \
         `:upgrade-from :from`, `:etiquetas`, `:autores` — and the three \
         code-path lists are the last Vec-shaped author-supplied slots on \
         the typed Caixa surface still admitting a duplicate entry. \
         `:bibliotecas` duplicates re-parse the same file at \
         `feira build` time and silently mask the author's intent to \
         declare a *second* biblioteca; `:exe` duplicates collide on the \
         flake `packages.<name>` derivation key at the future \
         `caixa-flake` materializer; `:servicos` duplicates surface as the \
         narrower [`caixa-helm`] / [`caixa-flux`] `UnsupportedServicoCount` \
         rejection far from the source `caixa.lisp`. Drop the duplicate \
         or rename it to the actual second file intended)",
        path.display()
    )]
    CodePathDuplicate { slot: &'static str, path: PathBuf },
    #[error(
        ":etiquetas entry is empty (every tag must carry a non-empty \
         registry-search identifier; the empty entry has no operational \
         meaning — it indexes nothing in the future caixa-registry search \
         axis and clutters the rendered Helm `Chart.yaml` `keywords:` array \
         with a no-op tag; omit the entry to express \"no tag on this \
         position\")"
    )]
    EtiquetaEmpty,
    #[error(
        ":etiquetas entry {etiqueta:?} appears more than once (the \
         registry-search tag set is a set, not a multiset; duplicate \
         entries are silently dedup'd by caixa-helm's `BTreeSet` collect \
         at chart render — a \"second wins / one silently disappears\" \
         shape divergent from every peer typed-graph set gate \
         (`:membros :caixa`, `:placement :clusters`, `:entrada :paths`, \
         `:contratos`, `:deps :nome`, `:upgrade-from :from`); drop the \
         duplicate or rename it to the actual tag intended)"
    )]
    EtiquetaDuplicate { etiqueta: String },
    #[error(
        ":etiquetas entry {etiqueta:?} is not a valid chart-keyword shape: \
         {reason} (the substrate consumes this string through the shared \
         `crate::render::is_chart_keyword_shape` predicate — the same \
         Cargo crates.io `[package] keywords` grammar entry shape: 1..=20 \
         bytes, starts with an ASCII letter, ASCII alphanumeric / `_` / `-` \
         continuation. The canonical authoring shapes are short kebab-case \
         identifiers like `\"mesh\"`, `\"wasm\"`, `\"tatara-lisp\"`, \
         `\"hello-world\"`, `\"caixa-servico\"`, `\"infrastructure\"`. \
         Without this gate a malformed `:etiquetas` entry (paste-from-doc \
         leading / trailing whitespace `\" mesh\"` / `\"mesh \"`; \
         paste-from-multiline-doc newline `\"mesh\\nhttp\"`; \
         paste-from-Windows-CRLF-doc CR; CSV-list-separator confusion \
         `\"mesh,http,grpc\"` — the author meant to author three separate \
         list entries; path-separator confusion `\"caixa/servico\"`; \
         namespace-suffix `\"http.1\"`; leading-digit `\"1foo\"`; \
         kebab-leak `\"-foo\"`; snake-leak `\"_foo\"`; non-ASCII \
         `\"café\"` — every legitimate search tag is strict ASCII; \
         paste-from-binary-blob NUL / BEL / ESC / DEL byte) silently \
         passed `from_lisp` + `validate_etiquetas` + \
         `StandardLayout::verify` and landed in the rendered \
         `lareira-<nome>` Helm chart's `Chart.yaml keywords:` array as a \
         malformed search tag — Artifact Hub's keyword index + the future \
         caixa-registry's keyword index would either silently drop the \
         tag or fail to index it far from the source caixa.lisp; the gate \
         moves the diagnostic to the manifest layer with the offending \
         value named verbatim)"
    )]
    EtiquetaInvalid { etiqueta: String, reason: String },
    #[error(
        ":autores entry is empty (every maintainer must carry a non-empty \
         identifier; the empty entry has no operational meaning — it \
         identifies no one in the substrate's authorship index and renders \
         as `maintainers: [{{name: \"\", email: null}}]` in the Helm chart's \
         `Chart.yaml`, a no-op maintainer the substrate cannot route to; \
         omit the entry to express \"no maintainer on this position\")"
    )]
    AutorEmpty,
    #[error(
        ":autores entry {autor:?} appears more than once (the maintainer \
         set is a set, not a multiset; unlike `:etiquetas`, caixa-helm's \
         `maintainers:` rendering does *no* dedup — duplicate entries \
         stack verbatim in `Chart.yaml` as two identical \
         `Maintainer {{ name, email: None }}` records, divergent from every \
         peer typed-graph set gate (`:etiquetas`, `:membros :caixa`, \
         `:placement :clusters`, `:entrada :paths`, `:contratos`, \
         `:deps :nome`, `:upgrade-from :from`); drop the duplicate or \
         rename it to the actual author intended)"
    )]
    AutorDuplicate { autor: String },
    #[error(
        ":autores entry {autor:?} is not a valid chart-maintainer-name shape: \
         {reason} (the substrate consumes this string through the shared \
         `crate::render::is_chart_maintainer_name_shape` predicate — the same \
         single-line-UTF-8 floor every realistic chart maintainer name carries: \
         1..=128 bytes, no leading or trailing whitespace, no ASCII control \
         characters anywhere, Unicode bytes accepted. The canonical authoring \
         shapes are short single-line identifiers like `\"pleme-io\"`, \
         `\"Pleme Contributors\"`, `\"alice <alice@example.com>\"`, \
         `\"François Dupont\"`. Without this gate a malformed `:autores` entry \
         (paste-from-aligned-doc leading whitespace `\" pleme-io\"` / trailing \
         whitespace `\"pleme-io \"`; paste-from-multiline-doc newline \
         `\"alice\\nbob\"` — the author pasted a multi-line block of author \
         records into one entry instead of splitting into one entry per author; \
         paste-from-Windows-CRLF-doc carriage return `\"alice\\rbob\"`; \
         tab-from-aligned-doc `\"Pleme\\tContributors\"`; paste-from-binary-blob \
         NUL / BEL / ESC / DEL byte) silently passed `from_lisp` + \
         `validate_autores` + `StandardLayout::verify` and landed in the \
         rendered `lareira-<nome>` Helm chart's `Chart.yaml maintainers:` array \
         as a YAML-illegal multi-line scalar or a silently-trimmed whitespace \
         round-trip — every chart-aware UI (`helm list`, `helm search`, \
         Artifact Hub maintainer index) would render the maintainer name in a \
         single-line column far from the source caixa.lisp; the gate moves the \
         diagnostic to the manifest layer with the offending value named \
         verbatim)"
    )]
    AutorInvalid { autor: String, reason: String },
    #[error(
        ":repositorio is the empty string (every published caixa names its \
         git source via a non-empty `:repositorio` locator — the value \
         flows verbatim into the rendered `lareira-<nome>` Helm chart's \
         `Chart.yaml` `home:` field via `caixa-helm` and into the FluxCD \
         `GitRepository.spec.url` via `caixa-flux`'s \
         `ClusterBundleOpts::for_caixa`; both consumers' \
         `Option::unwrap_or_else` fallbacks only fire when the slot is \
         `None`, so an empty `Some(\"\")` silently lands as `home: \"\"` / \
         `url: \"\"` in the rendered artifacts and breaks at `helm \
         template` / FluxCD source-controller reconcile time far from the \
         source caixa.lisp; omit the slot entirely to defer to the \
         renderer's `https://github.com/pleme-io/<nome>` / \
         `caixa.nome`-derived fallback, or carry a canonical authoring \
         shape like `\"github:org/repo\"`, `\"https://host/path\"`, \
         `\"ssh://[user@]host/path\"`, `\"git@host:path\"`, or \
         `\"file:///path\"`)"
    )]
    RepositorioEmpty,
    #[error(
        ":repositorio {repositorio:?} is not a valid git repo URL: {reason} \
         (the substrate consumes this string through the shared \
         `crate::render::is_git_repo_url` predicate — the same parser the \
         peer `:deps :fonte (:tipo git :repo …)` axis routes its `:repo` \
         value through via `DepSource::validate`; the canonical authoring \
         shapes are `\"github:org/repo\"` shorthand, `\"https://host/path\"` \
         / `\"ssh://[user@]host/path\"` / `\"git://host/path\"` / \
         `\"file:///path\"` URL schemes, or the `\"git@host:path\"` \
         scp-style SSH form. Without this gate a malformed `:repositorio` \
         (whitespace from a paste-from-doc; control characters / CRLF \
         from a paste-from-multiline-doc; a leading `-` from a \
         CLI-argument-injection footgun; a missing `:` separator from a \
         bare `org/repo` shape git treats as a relative filesystem path) \
         silently landed in the rendered `Chart.yaml home:` and the \
         FluxCD `GitRepository.spec.url` and broke at `git clone` / \
         FluxCD reconcile time far from the source caixa.lisp; the gate \
         moves the diagnostic to the manifest layer with the offending \
         value named verbatim)"
    )]
    RepositorioInvalid { repositorio: String, reason: String },
    #[error(
        ":descricao is the empty string (every published caixa names \
         its purpose via a non-empty `:descricao` summary — the value \
         flows verbatim into the rendered `lareira-<nome>` Helm \
         chart's `Chart.yaml` `description:` field via `caixa-helm`'s \
         `build_chart_yaml` and into the chart `README.md` header via \
         `build_readme`; both consumers' `Option::unwrap_or_else` \
         `caixa.nome`-derived fallbacks only fire when the slot is \
         `None`, so an empty `Some(\"\")` silently lands as \
         `description: \"\"` / a blank `README.md` header in the \
         rendered artifacts and breaks at `helm lint` time \
         (`WARNING [chart.metadata.description]: description is \
         required` on `apiVersion: v2` charts) far from the source \
         caixa.lisp; omit the slot entirely to defer to the \
         renderer's `\"Generated chart for caixa Servico <nome>\"` / \
         `\"caixa Servico <nome>\"` fallbacks, or carry a non-empty \
         summary like `\"Canonical Rust→wasm32-wasip2 caixa \
         Servico.\"`)"
    )]
    DescricaoEmpty,
    #[error(
        ":descricao {descricao:?} is not a valid chart-description shape: \
         {reason} (the substrate consumes this string through the shared \
         `crate::render::is_chart_description_shape` predicate — the same \
         single-line-UTF-8 floor every realistic chart description carries: \
         1..=512 bytes, no leading or trailing whitespace, no ASCII control \
         characters anywhere, Unicode prose bytes accepted. The canonical \
         authoring shapes are short single-line summaries like `\"Canonical \
         Rust→wasm32-wasip2 caixa Servico.\"`, `\"Checkout flow.\"`, \
         `\"AWS provider caixa for tatara-lisp\"`. Without this gate a \
         malformed `:descricao` (paste-from-aligned-doc leading whitespace \
         `\" Checkout flow.\"` / trailing whitespace `\"Checkout flow. \"`; \
         paste-from-multiline-doc newline `\"Checkout\\nflow.\"`; \
         paste-from-Windows-CRLF-doc carriage return `\"Checkout\\rflow.\"`; \
         tab-from-aligned-doc `\"Checkout\\tflow.\"`; paste-from-binary-blob \
         NUL / BEL / ESC / DEL byte) silently passed `from_lisp` + \
         `validate_descricao` + `StandardLayout::verify` and landed in the \
         rendered `lareira-<nome>` Helm chart's `Chart.yaml description:` \
         field + `README.md` header paragraph as a YAML-illegal multi-line \
         scalar or a silently-trimmed whitespace round-trip — every \
         chart-aware UI (`helm list`, `helm search`, Artifact Hub) would \
         render the description in a single-line column far from the source \
         caixa.lisp; the gate moves the diagnostic to the manifest layer \
         with the offending value named verbatim)"
    )]
    DescricaoInvalid { descricao: String, reason: String },
    #[error(
        ":licenca is the empty string (every published caixa names \
         its license via a non-empty `:licenca` SPDX expression — the \
         value flows verbatim into the rendered `lareira-<nome>` Helm \
         chart's `README.md` `## License` section via `caixa-helm`'s \
         `build_readme` at `caixa-helm/src/lib.rs:361`; the consumer's \
         `Option::unwrap_or_else(|| \"MIT\".into())` `MIT` fallback \
         only fires when the slot is `None`, so an empty `Some(\"\")` \
         silently lands as a bare trailing period in the rendered \
         chart `README.md` `License` section far from the source \
         caixa.lisp; omit the slot entirely to defer to the \
         renderer's `MIT` fallback, or carry a canonical SPDX \
         expression like `\"MIT\"`, `\"Apache-2.0\"`, \
         `\"Apache-2.0 OR MIT\"`)"
    )]
    LicencaEmpty,
    #[error(
        ":licenca {licenca:?} is not a valid SPDX expression shape: {reason} \
         (the substrate consumes this string through the shared \
         `crate::render::is_spdx_expression_shape` predicate — the same \
         alphabet-floor parser every peer per-axis value-shape gate routes \
         its value through; the canonical authoring shapes are single \
         license identifiers like `\"MIT\"`, `\"Apache-2.0\"`, `\"BSD-3-Clause\"`, \
         compound expressions like `\"Apache-2.0 OR MIT\"`, \
         `\"MIT AND BSD-3-Clause\"`, `\"(MIT OR Apache-2.0) AND ISC\"`, \
         license-with-exception forms like `\"Apache-2.0 WITH LLVM-exception\"`, \
         `+`-suffix variants like `\"GPL-2.0+\"`, and user-defined references \
         like `\"LicenseRef-MyLicense\"` / \
         `\"DocumentRef-doc:LicenseRef-MyLicense\"`. Without this gate a \
         malformed `:licenca` (paste-from-doc whitespace `\"MIT \"` / \
         `\" MIT\"`; paste-from-multiline-doc CRLF `\"MIT\\n\"`; \
         tab-from-aligned-doc `\"MIT\\tOR Apache-2.0\"`; non-ASCII byte from \
         a smart-quote paste; underscore-instead-of-hyphen typo \
         `\"Apache_2.0\"`; comma-instead-of-`OR`-keyword colloquial idiom \
         `\"MIT, Apache-2.0\"`; slash-dual-license colloquial idiom \
         `\"MIT/Apache-2.0\"`; semicolon-list-separator confusion \
         `\"MIT; Apache-2.0\"`) silently landed in the rendered chart \
         `README.md` `## License` section + a future SPDX-aware \
         `Chart.yaml license:` emitter would refuse the value at \
         `helm lint` time far from the source caixa.lisp; the gate moves \
         the diagnostic to the manifest layer with the offending value \
         named verbatim)"
    )]
    LicencaInvalid { licenca: String, reason: String },
    #[error(
        ":edicao is the empty string (every published caixa names \
         its language edition via a non-empty `:edicao` value — the \
         edition determines the tatara-lisp macro surface + \
         compatibility flags the substrate applies when building \
         the caixa; the canonical `Caixa::template` scaffold every \
         `feira init` emits carries `:edicao \"2026\"` verbatim and \
         every renderer-side fixture (`caixa-helm`, `caixa-flux`, \
         `caixa-mesh`) carries `edicao: Some(\"2026\".into())` by \
         construction, so an empty `Some(\"\")` silently lands as a \
         bare `(:edicao \"\")` line in the rendered `caixa.lisp` and \
         a future renderer-side consumer that folds it through \
         `Option::unwrap_or_else` will skip the fallback and pass the \
         empty edition through to the substrate's build-time edition \
         selector far from the source caixa.lisp; omit the slot \
         entirely to defer to the substrate's default edition, or \
         carry a canonical edition like `\"2026\"`)"
    )]
    EdicaoEmpty,
    #[error(
        ":edicao {edicao:?} is not a valid edition: {reason} (every \
         documented tatara-lisp edition is a 4-digit ASCII decimal \
         year — `\"2026\"` is the only edition currently minted; \
         future-introduced siblings will follow the same shape, peer \
         with Cargo's `[package] edition` grammar which every value \
         Cargo has ever accepted matches: `\"2015\"`, `\"2018\"`, \
         `\"2021\"`, `\"2024\"`. Without this gate the canonical \
         paste-from-doc footguns silently passed: a trailing space \
         (`\"2026 \"`) from a paste-from-doc, a CRLF (`\"2026\\n\"`) \
         from a paste-from-multiline-doc, a fullwidth-keyboard \
         look-alike (`\"２０２６\"`), a free-form non-year value \
         (`\"x\"`, `\"latest\"`, `\"nightly\"`), a leading non-digit \
         version-tag prefix (`\"v2026\"`, `\"e2026\"`), a \
         decimal-shaped pseudo-version (`\"2026.1\"`), or a \
         wrong-length numeric value (`\"26\"`, `\"202\"`, \
         `\"20260\"`) all landed as `(:edicao \"<garbage>\")` in the \
         rendered caixa.lisp and broke at the substrate's \
         build-time edition selector far from the source caixa.lisp; \
         omit the slot entirely to defer to the substrate's default \
         edition, or carry a canonical 4-digit ASCII decimal year \
         like `\"2026\"`)"
    )]
    EdicaoInvalid { edicao: String, reason: String },
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn template_round_trips() {
        let src = Caixa::template("demo");
        let c = Caixa::from_lisp(&src).expect("template must parse");
        assert_eq!(c.nome, "demo");
        assert_eq!(c.versao, "0.1.0");
        assert_eq!(c.kind, CaixaKind::Biblioteca);
        assert_eq!(c.bibliotecas, vec!["lib/demo.lisp".to_string()]);
        assert!(c.deps.is_empty());
        assert!(c.deps_dev.is_empty());
    }

    #[test]
    fn caixa_universal_axis_scalar_accessor_pair_is_const_fn() {
        // Fail-before-pass-after pin on [`Caixa::nome`] +
        // [`Caixa::versao`]'s `const`-eval-surface posture. Each
        // accessor projects the top-level manifest's per-`:nome` /
        // per-`:versao` [`String`] storage through the `pub const fn`
        // [`String::as_str`] (const-stable since Rust 1.87, well within
        // the workspace MSRV) — any future accidental downgrade to
        // non-`const` fails the corresponding `<name>_via_const_fn`
        // wrapper at caixa-core build time with E0015 (`cannot call
        // non-const method`), strictly stronger than a runtime
        // `assert!`. Sibling of the peer per-M2/M3-slot `String → &str`
        // scalar-accessor family pins on the sibling `const`-eval-
        // surface passes ([`crate::CaixaVersion::as_str`] at the
        // typed-newtype wrapper, [`crate::aplicacao::Membro::nome`] /
        // [`crate::aplicacao::Membro::versao_requirement`] at the M3
        // membership axis, [`crate::aplicacao::Entrada::hostname`] /
        // [`crate::aplicacao::Entrada::destination`] at the M3 ingress
        // axis, [`crate::supervisor::ChildSpec::nome`] /
        // [`crate::supervisor::ChildSpec::versao_requirement`] at the
        // M2 supervisor-tree axis,
        // [`crate::upgrade::UpgradeFromEntry::prior_versao`] at the M2
        // upgrade axis, [`crate::dep::Dep::nome`] /
        // [`crate::dep::Dep::versao_requirement`] at the dep-graph
        // axis, and the per-`:contratos`
        // [`crate::aplicacao::WitContract::source`] /
        // [`crate::aplicacao::WitContract::destination`] /
        // [`crate::aplicacao::WitContract::world_ref`] trio the
        // sibling pin at 279823b already anchors).
        const fn nome_via_const_fn(c: &Caixa) -> &str {
            c.nome()
        }
        const fn versao_via_const_fn(c: &Caixa) -> &str {
            c.versao()
        }
        let src = Caixa::template("demo");
        let c = Caixa::from_lisp(&src).expect("template must parse");
        assert_eq!(nome_via_const_fn(&c), c.nome());
        assert_eq!(versao_via_const_fn(&c), c.versao());
        assert_eq!(c.nome(), "demo");
        assert_eq!(c.versao(), "0.1.0");
    }

    #[test]
    fn caixa_option_string_scalar_accessor_family_is_const_fn() {
        // Fail-before-pass-after pin on the five per-`Caixa`
        // `Option<String> → Option<&str>` scalar accessors
        // ([`Caixa::licenca`] / [`Caixa::repositorio`] /
        // [`Caixa::descricao`] / [`Caixa::edicao`] on the top-level
        // manifest's optional universal-axis surface, plus
        // [`Caixa::restart_window`] on the M2 supervisor-tree
        // per-`SupervisorSpec` peer raw-window-string projection axis).
        // Each accessor destructures the typed slot's `Option<String>`
        // storage through the `match &self.<field> { Some(s) =>
        // Some(s.as_str()), None => None }` shape — routing through
        // [`String::as_str`] (const-stable since Rust 1.87, well within
        // the workspace MSRV) rather than the non-const
        // [`Option::as_deref`] the pre-lift bodies carried — and any
        // future accidental downgrade to non-`const` fails the
        // corresponding `<name>_via_const_fn` wrapper at caixa-core
        // build time with E0015 (`cannot call non-const method`),
        // strictly stronger than a runtime `assert!` and strictly
        // stronger than a module-scope `const _: () = assert!(…)` pin
        // (which cannot be formed on a `&Caixa` fixture because the
        // type's `String` / `Option<String>` carriers rule out
        // `const`-context value construction; the `const fn` wrapper
        // is the load-bearing shape that side-steps the destructor-in-
        // const restriction on the value axis while still pinning the
        // `const`-fn posture on the callee — mirror of the sibling
        // [`caixa_universal_axis_scalar_accessor_pair_is_const_fn`]
        // pin's discipline verbatim on the peer non-`Option`
        // `String → &str` axis at the same struct).
        //
        // Peer of the sibling per-M2/M3-slot `Option<String> →
        // Option<&str>` accessor family pin
        // [`m3_option_string_scalar_accessor_family_is_const_fn`] on
        // the M3 mesh-slot atom axes ([`WitContract::endpoint`] /
        // [`WitContract::subject`] / [`WitContract::slot`] on the
        // per-`:contratos` payload-carrier trio,
        // [`Placement::shard_key`] / [`Placement::affinity`] on the
        // per-`:placement` optional-scalar pair).
        const fn licenca_via_const_fn(c: &Caixa) -> Option<&str> {
            c.licenca()
        }
        const fn repositorio_via_const_fn(c: &Caixa) -> Option<&str> {
            c.repositorio()
        }
        const fn descricao_via_const_fn(c: &Caixa) -> Option<&str> {
            c.descricao()
        }
        const fn edicao_via_const_fn(c: &Caixa) -> Option<&str> {
            c.edicao()
        }
        const fn restart_window_via_const_fn(c: &Caixa) -> Option<&str> {
            c.restart_window()
        }
        // Sweep both the `Some`-carrying arm (author-declared slot,
        // the byte-string projection payload) and the `None`-carrying
        // arm (author-omitted slot, the default-path projection) on
        // every accessor so the `const fn` wrapper family pins each
        // axis's canonical two-arm partition through the same const
        // dispatch as the runtime path.
        let mut c1 = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        c1.licenca = Some("MIT".to_string());
        c1.repositorio = Some("https://github.com/pleme-io/demo".to_string());
        c1.descricao = Some("demo caixa".to_string());
        c1.edicao = Some("2024".to_string());
        c1.restart_window = Some("60s".to_string());
        assert_eq!(licenca_via_const_fn(&c1), c1.licenca());
        assert_eq!(repositorio_via_const_fn(&c1), c1.repositorio());
        assert_eq!(descricao_via_const_fn(&c1), c1.descricao());
        assert_eq!(edicao_via_const_fn(&c1), c1.edicao());
        assert_eq!(restart_window_via_const_fn(&c1), c1.restart_window());
        assert_eq!(c1.licenca(), Some("MIT"));
        assert_eq!(c1.repositorio(), Some("https://github.com/pleme-io/demo"));
        assert_eq!(c1.descricao(), Some("demo caixa"));
        assert_eq!(c1.edicao(), Some("2024"));
        assert_eq!(c1.restart_window(), Some("60s"));
        let mut c2 = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        c2.licenca = None;
        c2.repositorio = None;
        c2.descricao = None;
        c2.edicao = None;
        c2.restart_window = None;
        assert_eq!(licenca_via_const_fn(&c2), None);
        assert_eq!(repositorio_via_const_fn(&c2), None);
        assert_eq!(descricao_via_const_fn(&c2), None);
        assert_eq!(edicao_via_const_fn(&c2), None);
        assert_eq!(restart_window_via_const_fn(&c2), None);
    }

    #[test]
    fn caixa_outer_copy_return_accessor_pair_is_const_fn() {
        // Fail-before-pass-after pin on the two outer-[`Caixa`]
        // `Copy`-return accessors — [`Caixa::kind`] on the required
        // [`CaixaKind`] enum-discriminant axis and [`Caixa::estrategia`]
        // on the M2 supervisor-tree flat-spread `Option<RestartStrategy>`
        // axis. Both accessors project a `Copy`-carrier field
        // (`CaixaKind: Copy` at caixa-core/src/kind.rs:17,
        // `RestartStrategy: Copy` at caixa-core/src/supervisor.rs:33 →
        // `Option<RestartStrategy>: Copy`) by value through a bare
        // `self.<field>` field-access — no dispatch, no destructor, no
        // heap. Any future accidental downgrade to non-`const` fails
        // the corresponding `<name>_via_const_fn` wrapper at caixa-core
        // build time with E0015 (`cannot call non-const method`),
        // strictly stronger than a runtime `assert!` and strictly
        // stronger than a module-scope `const _: () = assert!(…)` pin
        // (which cannot be formed on a `&Caixa` fixture because the
        // type's `String` / `Vec` / `Option<Composite>` carriers rule
        // out `const`-context value construction; the `const fn`
        // wrapper is the load-bearing shape that side-steps the
        // destructor-in-const restriction on the value axis while still
        // pinning the `const`-fn posture on the callee — mirror of the
        // sibling [`caixa_universal_axis_scalar_accessor_pair_is_const_fn`]
        // + [`caixa_option_string_scalar_accessor_family_is_const_fn`]
        // pins' discipline verbatim on the peer outer-`Caixa`
        // `String → &str` + `Option<String> → Option<&str>` axes at the
        // same struct).
        //
        // Peer of the sibling per-M2/M3-slot `Copy`-return accessor pin
        // family on the inner-altitude nested-spec typed-slot
        // discriminator axes: [`crate::supervisor::SupervisorSpec::estrategia`]
        // + [`crate::supervisor::ChildSpec::restart`] on the M2
        // supervisor-tree axis (pinned at 152c868), and
        // [`crate::aplicacao::Placement::estrategia`] +
        // [`crate::aplicacao::Entrada::port`] on the M3 mesh-slot axis
        // (pinned at bafa004) — the outer-`Caixa` altitude is the last
        // unlifted altitude for the `Copy`-return-accessor family.
        const fn kind_via_const_fn(c: &Caixa) -> CaixaKind {
            c.kind()
        }
        const fn estrategia_via_const_fn(c: &Caixa) -> Option<crate::supervisor::RestartStrategy> {
            c.estrategia()
        }
        // Sweep every arm of both discriminant partitions the accessors
        // fan on — every [`CaixaKind`] variant the six-arm required
        // discriminant carries (Biblioteca / Binario / Servico /
        // Supervisor / Aplicacao / Acao) and both arms of the
        // [`Option<RestartStrategy>`] flat-spread supervisor-tree slot
        // (`Some(<strategy>)` on an author-declared supervisor and
        // `None` on the author-omitted default arm every non-Supervisor
        // caixa carries by `#[serde(default)]`) — so the `const fn`
        // wrapper family pins the closed-set partition through the
        // same const dispatch as the runtime path.
        let mut c1 = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        c1.kind = CaixaKind::Servico;
        c1.estrategia = Some(crate::supervisor::RestartStrategy::OneForAll);
        assert_eq!(kind_via_const_fn(&c1), c1.kind());
        assert_eq!(estrategia_via_const_fn(&c1), c1.estrategia());
        assert_eq!(c1.kind(), CaixaKind::Servico);
        assert_eq!(
            c1.estrategia(),
            Some(crate::supervisor::RestartStrategy::OneForAll)
        );
        let mut c2 = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        c2.kind = CaixaKind::Aplicacao;
        c2.estrategia = None;
        assert_eq!(kind_via_const_fn(&c2), CaixaKind::Aplicacao);
        assert_eq!(estrategia_via_const_fn(&c2), None);
        // Anchor the remaining discriminant arms so any future
        // reordering of [`CaixaKind`]'s six-variant enum surfaces
        // through the wrapper dispatch, not just through the direct
        // method call.
        for kind in [
            CaixaKind::Biblioteca,
            CaixaKind::Binario,
            CaixaKind::Servico,
            CaixaKind::Supervisor,
            CaixaKind::Aplicacao,
            CaixaKind::Acao,
        ] {
            let mut c = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
            c.kind = kind;
            assert_eq!(kind_via_const_fn(&c), kind);
        }
    }

    #[test]
    fn caixa_outer_string_slice_return_accessor_family_is_const_fn() {
        // Fail-before-pass-after pin on the five outer-[`Caixa`]
        // `Vec<String> → &[String]` slice-return accessors on the
        // universal-axis surface — [`Caixa::autores`] / [`Caixa::etiquetas`]
        // / [`Caixa::bibliotecas`] / [`Caixa::exe`] / [`Caixa::servicos`].
        // Each body is a bare `self.<field>.as_slice()` dispatch through
        // [`Vec::as_slice`] (const-stable since Rust 1.87, well within
        // the workspace MSRV). Any future accidental downgrade to
        // non-`const` fails the corresponding `<name>_via_const_fn`
        // wrapper at caixa-core build time with E0015 (`cannot call
        // non-const method`) — mirror of the sibling
        // [`caixa_outer_copy_return_accessor_pair_is_const_fn`] pin's
        // discipline on the peer outer-`Caixa` `Copy`-return accessor
        // axis, and peer of the sibling composite-carrier slice-return
        // pin below on the peer outer-`Caixa` composite-slice axis.
        const fn autores_via_const_fn(c: &Caixa) -> &[String] {
            c.autores()
        }
        const fn etiquetas_via_const_fn(c: &Caixa) -> &[String] {
            c.etiquetas()
        }
        const fn bibliotecas_via_const_fn(c: &Caixa) -> &[String] {
            c.bibliotecas()
        }
        const fn exe_via_const_fn(c: &Caixa) -> &[String] {
            c.exe()
        }
        const fn servicos_via_const_fn(c: &Caixa) -> &[String] {
            c.servicos()
        }
        // Sweep the empty arm (`autores` / `etiquetas` / `exe` /
        // `servicos` — the template's `Vec::new()` default) and the
        // populated arm (mutated below) on every accessor so the
        // `const fn` wrapper family pins each axis's two-arm partition
        // through the same const dispatch as the runtime path.
        // [`Caixa::template`] seeds `lib/demo.lisp` into `:bibliotecas`,
        // so that arm's "empty" fixture is the populated arm the
        // mutation sweep covers.
        let c_empty = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        assert!(autores_via_const_fn(&c_empty).is_empty());
        assert!(etiquetas_via_const_fn(&c_empty).is_empty());
        assert!(exe_via_const_fn(&c_empty).is_empty());
        assert!(servicos_via_const_fn(&c_empty).is_empty());
        let mut c_full = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        c_full.autores = vec!["ada".to_string(), "erlang".to_string()];
        c_full.etiquetas = vec!["compounding".to_string()];
        c_full.bibliotecas = vec!["lib/one.lisp".to_string(), "lib/two.lisp".to_string()];
        c_full.exe = vec!["exe/cli.lisp".to_string()];
        c_full.servicos = vec!["servicos/one.computeunit.yaml".to_string()];
        assert_eq!(autores_via_const_fn(&c_full), c_full.autores());
        assert_eq!(autores_via_const_fn(&c_full), &["ada", "erlang"]);
        assert_eq!(etiquetas_via_const_fn(&c_full), c_full.etiquetas());
        assert_eq!(etiquetas_via_const_fn(&c_full), &["compounding"]);
        assert_eq!(bibliotecas_via_const_fn(&c_full), c_full.bibliotecas());
        assert_eq!(
            bibliotecas_via_const_fn(&c_full),
            &["lib/one.lisp", "lib/two.lisp"]
        );
        assert_eq!(exe_via_const_fn(&c_full), c_full.exe());
        assert_eq!(exe_via_const_fn(&c_full), &["exe/cli.lisp"]);
        assert_eq!(servicos_via_const_fn(&c_full), c_full.servicos());
        assert_eq!(
            servicos_via_const_fn(&c_full),
            &["servicos/one.computeunit.yaml"]
        );
    }

    #[test]
    fn caixa_outer_composite_slice_return_accessor_family_is_const_fn() {
        // Fail-before-pass-after pin on the six outer-[`Caixa`] composite-
        // carrier `Vec<T> → &[T]` slice-return accessors — [`Caixa::deps`]
        // / [`Caixa::deps_dev`] on the dep-graph axis,
        // [`Caixa::upgrade_from`] on the M2 appup axis, [`Caixa::children`]
        // on the M2 supervisor-tree axis, and [`Caixa::membros`] /
        // [`Caixa::contratos`] on the M3 mesh-slot axis. Each body is a
        // bare `self.<field>.as_slice()` dispatch through
        // [`Vec::as_slice`] (const-stable since Rust 1.87, well within
        // the workspace MSRV) — peer of the sibling `String`-payload
        // slice-return pin above on the peer outer-`Caixa` universal-
        // axis surface, and peer of the sibling inner-composite-
        // altitude reference-return pin family
        // [`crate::aplicacao::tests::m3_aplicacao_spec_reference_return_accessor_family_is_const_fn`]
        // + [`crate::supervisor::tests::supervisor_children_slice_return_accessor_is_const_fn`]
        // + [`crate::upgrade::tests::upgrade_from_entry_instructions_slice_return_accessor_is_const_fn`]
        // (all pinned at 0b23e0f).
        const fn deps_via_const_fn(c: &Caixa) -> &[Dep] {
            c.deps()
        }
        const fn deps_dev_via_const_fn(c: &Caixa) -> &[Dep] {
            c.deps_dev()
        }
        const fn upgrade_from_via_const_fn(c: &Caixa) -> &[UpgradeFromEntry] {
            c.upgrade_from()
        }
        const fn children_via_const_fn(c: &Caixa) -> &[crate::supervisor::ChildSpec] {
            c.children()
        }
        const fn membros_via_const_fn(c: &Caixa) -> &[crate::aplicacao::Membro] {
            c.membros()
        }
        const fn contratos_via_const_fn(c: &Caixa) -> &[crate::aplicacao::WitContract] {
            c.contratos()
        }
        // Empty-arm sweep on all six composite-carrier axes — every
        // `Caixa::template` starts with `Vec::new()` on each.
        let c_empty = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        assert!(deps_via_const_fn(&c_empty).is_empty());
        assert!(deps_dev_via_const_fn(&c_empty).is_empty());
        assert!(upgrade_from_via_const_fn(&c_empty).is_empty());
        assert!(children_via_const_fn(&c_empty).is_empty());
        assert!(membros_via_const_fn(&c_empty).is_empty());
        assert!(contratos_via_const_fn(&c_empty).is_empty());
        // Populate `:membros` / `:contratos` directly via struct literals
        // — the parser-side validation path fans on `:kind`-gated cross-
        // slot invariants irrelevant to the accessor dispatch under test.
        let mut c_full = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        c_full.membros = vec![
            crate::aplicacao::Membro {
                caixa: "demo-a".to_string(),
                versao: "^0.1.0".to_string(),
            },
            crate::aplicacao::Membro {
                caixa: "demo-b".to_string(),
                versao: "^0.2.0".to_string(),
            },
        ];
        c_full.contratos = vec![crate::aplicacao::WitContract {
            de: "demo-a".to_string(),
            para: "demo-b".to_string(),
            wit: "wasi:http/proxy".to_string(),
            endpoint: Some("/edge".to_string()),
            subject: None,
            slot: None,
        }];
        assert_eq!(membros_via_const_fn(&c_full), c_full.membros());
        assert_eq!(contratos_via_const_fn(&c_full), c_full.contratos());
        assert_eq!(membros_via_const_fn(&c_full).len(), 2);
        assert_eq!(contratos_via_const_fn(&c_full).len(), 1);
        // Alias-borrow check on the four remaining composite-carrier
        // slice-return arms — the wrapper's return borrow must alias the
        // caller's borrow so any future accessor re-routing that skips
        // the storage field surfaces through the assertion.
        assert!(std::ptr::eq(deps_via_const_fn(&c_full), c_full.deps()));
        assert!(std::ptr::eq(
            deps_dev_via_const_fn(&c_full),
            c_full.deps_dev()
        ));
        assert!(std::ptr::eq(
            upgrade_from_via_const_fn(&c_full),
            c_full.upgrade_from()
        ));
        assert!(std::ptr::eq(
            children_via_const_fn(&c_full),
            c_full.children()
        ));
    }

    #[test]
    fn caixa_outer_option_composite_reference_return_accessor_family_is_const_fn() {
        // Fail-before-pass-after pin on the six outer-[`Caixa`]
        // `Option<Composite> → Option<&Composite>` reference-return
        // accessors — [`Caixa::limits`] / [`Caixa::behavior`] on the M2
        // Servico-runtime typed-slot axis, [`Caixa::politicas`] /
        // [`Caixa::placement`] / [`Caixa::entrada`] on the M3 mesh-slot
        // axis, and [`Caixa::ci`] on the Acao-kind typed-CI-run axis.
        // Each body is a bare `self.<field>.as_ref()` dispatch through
        // [`Option::as_ref`] (const-stable since Rust 1.83, well within
        // the workspace MSRV of 1.89). Any future accidental downgrade
        // to non-`const` fails the corresponding `<name>_via_const_fn`
        // wrapper at caixa-core build time with E0015 (`cannot call
        // non-const method`), strictly stronger than a runtime `assert!`
        // and strictly stronger than a module-scope `const _: () =
        // assert!(…)` pin (which cannot be formed on a `&Caixa` fixture
        // because the type's `String` / `Vec` / `Option<Composite>`
        // carriers rule out `const`-context value construction; the
        // `const fn` wrapper is the load-bearing shape that side-steps
        // the destructor-in-const restriction on the value axis while
        // still pinning the `const`-fn posture on the callee — mirror
        // of the sibling
        // [`caixa_outer_copy_return_accessor_pair_is_const_fn`] +
        // [`caixa_outer_string_slice_return_accessor_family_is_const_fn`] +
        // [`caixa_outer_composite_slice_return_accessor_family_is_const_fn`]
        // pins' discipline verbatim on the peer outer-`Caixa` axes at
        // the same struct).
        //
        // Closes the outer-`Caixa` `Option<&Composite>` composite-
        // reference-return sub-family — the last unlifted altitude on
        // the outer-`Caixa` accessor-family const-eval surface after
        // the sibling `Copy`-return / universal-axis-`&str` /
        // `Option<&str>` / `&[String]` / composite-`&[T]` pins already
        // closed the sibling arms at 866d1d5 / 29c5d7e / 0650f64 /
        // 231a968 (the last of these pins the `Vec<T> → &[T]`
        // composite-slice arm the six accessors here close as their
        // `Option<Composite> → Option<&Composite>` peer). Peer of the
        // sibling inner-altitude nested-spec composite-reference-return
        // pin family — [`crate::AplicacaoSpec::politicas`] /
        // [`crate::AplicacaoSpec::placement`] /
        // [`crate::AplicacaoSpec::entrada`] on the inner
        // [`crate::AplicacaoSpec`] altitude (already `pub const fn`
        // per 0b23e0f), and the outer-`Caixa` altitude here now carries
        // the same shape so both altitudes of the reference-return
        // discipline (per-`Caixa` outer-slot presence + per-
        // `AplicacaoSpec` inner-slot presence) route through one typed
        // const dispatch on the substrate primitive.
        const fn limits_via_const_fn(c: &Caixa) -> Option<&LimitsSpec> {
            c.limits()
        }
        const fn behavior_via_const_fn(c: &Caixa) -> Option<&crate::BehaviorSpec> {
            c.behavior()
        }
        const fn politicas_via_const_fn(c: &Caixa) -> Option<&crate::aplicacao::MeshPolicy> {
            c.politicas()
        }
        const fn placement_via_const_fn(c: &Caixa) -> Option<&crate::aplicacao::Placement> {
            c.placement()
        }
        const fn entrada_via_const_fn(c: &Caixa) -> Option<&crate::aplicacao::Entrada> {
            c.entrada()
        }
        const fn ci_via_const_fn(c: &Caixa) -> Option<&canteiro_types::CiRun> {
            c.ci()
        }
        // Both-arm sweep on every accessor: the `None` author-omitted
        // arm (template default — no M2/M3/CI slot declared) and the
        // `Some(<composite>)` authored arm (mutated below via struct-
        // literal seeds, side-stepping the parser-side `:kind`-gated
        // cross-slot invariants irrelevant to the accessor dispatch
        // under test). Both arms route through the `const fn` wrapper
        // family so the two-arm `Option` partition is pinned through
        // the same const dispatch as the runtime path.
        let c_empty = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        assert!(limits_via_const_fn(&c_empty).is_none());
        assert!(behavior_via_const_fn(&c_empty).is_none());
        assert!(politicas_via_const_fn(&c_empty).is_none());
        assert!(placement_via_const_fn(&c_empty).is_none());
        assert!(entrada_via_const_fn(&c_empty).is_none());
        assert!(ci_via_const_fn(&c_empty).is_none());
        let mut c_full = Caixa::from_lisp(&Caixa::template("demo")).expect("template must parse");
        c_full.limits = Some(LimitsSpec::default());
        c_full.behavior = Some(crate::BehaviorSpec::default());
        c_full.politicas = Some(crate::aplicacao::MeshPolicy::default());
        c_full.placement = Some(crate::aplicacao::Placement::default());
        c_full.entrada = Some(crate::aplicacao::Entrada {
            host: "demo.quero.cloud".to_string(),
            para: "demo".to_string(),
            paths: Vec::new(),
            port: crate::aplicacao::DEFAULT_SERVICO_PORT,
        });
        c_full.ci = Some(canteiro_types::CiRun {
            workspace: "pleme-io".into(),
            repo: "caixa".into(),
            nodes: vec![],
        });
        assert!(limits_via_const_fn(&c_full).is_some());
        assert!(behavior_via_const_fn(&c_full).is_some());
        assert!(politicas_via_const_fn(&c_full).is_some());
        assert!(placement_via_const_fn(&c_full).is_some());
        assert!(entrada_via_const_fn(&c_full).is_some());
        assert!(ci_via_const_fn(&c_full).is_some());
        // Alias-borrow check on every arm: the wrapper's inner-`Option`
        // reference must alias the caller's borrow so any future accessor
        // re-routing that skips the storage field surfaces through the
        // assertion.
        assert!(std::ptr::eq(
            limits_via_const_fn(&c_full).unwrap(),
            c_full.limits().unwrap()
        ));
        assert!(std::ptr::eq(
            behavior_via_const_fn(&c_full).unwrap(),
            c_full.behavior().unwrap()
        ));
        assert!(std::ptr::eq(
            politicas_via_const_fn(&c_full).unwrap(),
            c_full.politicas().unwrap()
        ));
        assert!(std::ptr::eq(
            placement_via_const_fn(&c_full).unwrap(),
            c_full.placement().unwrap()
        ));
        assert!(std::ptr::eq(
            entrada_via_const_fn(&c_full).unwrap(),
            c_full.entrada().unwrap()
        ));
        assert!(std::ptr::eq(
            ci_via_const_fn(&c_full).unwrap(),
            c_full.ci().unwrap()
        ));
    }

    #[test]
    fn register_populates_registry() {
        Caixa::register().expect("first register call in this test process must succeed");
        let kws = tatara_lisp::domain::registered_keywords();
        assert!(kws.contains(&"defcaixa"));
    }

    #[test]
    fn to_lisp_round_trips() {
        let src = Caixa::template("demo");
        let c1 = Caixa::from_lisp(&src).unwrap();
        let emitted = c1.to_lisp();
        let c2 = Caixa::from_lisp(&emitted).expect("emitted lisp parses back");
        assert_eq!(c1, c2);
    }

    // ── DialetoEstrangeiro carries a single typed axis ────────────────────
    //
    // The compounding pin: the variant stores only the typed
    // [`crate::dialeto::CaixaDialeto`], and every user-facing byte-string
    // (canonical keyword, description, consumer) routes through the enum's
    // own accessors at Display time. Prior to that closure the variant
    // carried each accessor's return value as a stored `&'static str`
    // snapshot alongside `dialeto`; a caller could construct the variant
    // with a snapshot that drifted from what `dialeto`'s accessors would
    // return, and every downstream user-facing projection would silently
    // disagree with the classification. Storing only the axis makes the
    // drift structurally impossible.

    #[test]
    fn dialeto_estrangeiro_variant_carries_only_the_typed_dialeto_axis() {
        // Single-field construction is the whole compounding shape — a
        // future re-introduction of a snapshot field (a `palavra_canonica:
        // &'static str`, a stored `descricao:`, a stored `consumidor:`)
        // would re-open the drift surface and this construction would fail
        // to compile with "missing field" until every snapshot was seeded
        // at the call site again. The compile-time guarantee is the
        // invariant; the assertion below only witnesses that the
        // construction is well-formed after the closure.
        let err = LeituraError::DialetoEstrangeiro {
            dialeto: crate::dialeto::CaixaDialeto::Molde,
        };
        assert!(matches!(
            err,
            LeituraError::DialetoEstrangeiro {
                dialeto: crate::dialeto::CaixaDialeto::Molde,
            }
        ));
    }

    #[test]
    fn dialeto_estrangeiro_display_routes_through_typed_dialeto_accessors() {
        // For every foreign-dialect classification the variant surfaces —
        // [`crate::dialeto::CaixaDialeto::Molde`] and
        // [`crate::dialeto::CaixaDialeto::MoldePosicional`], the two
        // variants [`Caixa::from_lisp`] raises this error for — the
        // rendered [`std::fmt::Display`] byte-string must interpolate each
        // typed accessor's return verbatim. A future re-introduction of a
        // stored `&'static str` snapshot alongside `dialeto` that Display
        // read instead of the accessor would fail this pin as soon as the
        // two disagreed; a future accessor rebrand (a per-dialect
        // consumer rename, a canonical-keyword shift once the substrate
        // migration named in [`crate::dialeto`] completes) reaches every
        // consumer through one typed dispatch and this pin verifies the
        // display path is one of them.
        for d in [
            crate::dialeto::CaixaDialeto::Molde,
            crate::dialeto::CaixaDialeto::MoldePosicional,
        ] {
            let rendered = LeituraError::DialetoEstrangeiro { dialeto: d }.to_string();
            assert!(
                rendered.contains(d.palavra_canonica()),
                "Display must interpolate `dialeto.palavra_canonica()` \
                 verbatim — a stored snapshot would silently drift from \
                 the typed accessor. dialect: {d}, rendered: {rendered:?}"
            );
            assert!(
                rendered.contains(d.descricao()),
                "Display must interpolate `dialeto.descricao()` verbatim. \
                 dialect: {d}, rendered: {rendered:?}"
            );
            assert!(
                rendered.contains(d.consumidor()),
                "Display must interpolate `dialeto.consumidor()` verbatim. \
                 dialect: {d}, rendered: {rendered:?}"
            );
        }
    }

    #[test]
    fn from_lisp_rejects_molde_dialect_via_typed_variant() {
        // The end-to-end pin the compounding closure defends: a
        // Molde-dialect source lands as [`LeituraError::DialetoEstrangeiro`]
        // carrying [`crate::dialeto::CaixaDialeto::Molde`], and the
        // rendered Display byte-string names the Molde accessors'
        // returns verbatim. Any future path that constructed the variant
        // with a mismatched snapshot (a stored `palavra_canonica:
        // "defcaixa"` on a `Molde` classification) would land Display
        // pointing at `defcaixa` while the typed axis said `Molde` — the
        // exact drift the closure removes.
        let src = r#"
          (defcaixa
            :name "x"
            :kind :Biblioteca
            :ecosystem :rust-single-crate
            :package {:name "x" :version "0.1.0"})
        "#;
        let err = Caixa::from_lisp(src).expect_err("Molde dialect must not parse as Pacote");
        match err {
            LeituraError::DialetoEstrangeiro { dialeto } => {
                assert_eq!(dialeto, crate::dialeto::CaixaDialeto::Molde);
                let rendered = LeituraError::DialetoEstrangeiro { dialeto }.to_string();
                assert!(rendered.contains(dialeto.palavra_canonica()));
                assert!(rendered.contains(dialeto.consumidor()));
                assert!(rendered.contains(dialeto.descricao()));
            }
            other => panic!("expected DialetoEstrangeiro, got {other:?}"),
        }
    }

    #[test]
    fn from_lisp_rejects_molde_posicional_dialect_via_typed_variant() {
        // Coverage pin for the [`crate::dialeto::CaixaDialeto::MoldePosicional`]
        // arm of the [`Caixa::from_lisp`] foreign-dialect gate — the
        // positional-arity `defmolde` form written under a `(defcaixa …)`
        // head (`(defcaixa todoku-go :kind :Biblioteca :ecosystem :go
        // …)`). Pre-lift this arm rode the same `foreign =>` wildcard
        // the [`crate::dialeto::CaixaDialeto::Molde`] sibling arm rode,
        // so no test exercised the positional-arity path through
        // `Caixa::from_lisp` specifically; the sibling
        // [`from_lisp_rejects_molde_dialect_via_typed_variant`] only
        // covered [`crate::dialeto::CaixaDialeto::Molde`]. Post-lift the
        // two arms route through the lifted
        // [`crate::dialeto::CaixaDialeto::is_molde_family`] (e9d2315)
        // typed predicate — the same predicate the pre-lift `foreign =>`
        // wildcard resolved to today — and this pin makes the
        // positional-arity arm's byte-shape at the gate explicit rather
        // than implied by wildcard-absorption. A future regression that
        // silently reordered [`crate::dialeto::CaixaDialeto::is_molde_family`]'s
        // arm-set (dropped [`crate::dialeto::CaixaDialeto::MoldePosicional`]
        // from the two-arity closure) would fail this pin at caixa-core
        // test time rather than surfacing far from the change as a
        // `caixa.lisp` carrying a `(defcaixa todoku-go :ecosystem :go
        // …)` silently parsing past the derive.
        let src = r#"
          (defcaixa todoku-go
            :kind :Biblioteca
            :ecosystem :go
            :package {:name "todoku-go" :version "0.3.0"})
        "#;
        let err =
            Caixa::from_lisp(src).expect_err("MoldePosicional dialect must not parse as Pacote");
        match err {
            LeituraError::DialetoEstrangeiro { dialeto } => {
                assert_eq!(
                    dialeto,
                    crate::dialeto::CaixaDialeto::MoldePosicional,
                    "DialetoEstrangeiro must carry the MoldePosicional \
                     variant verbatim — the positional-arity `defmolde` \
                     form under a `(defcaixa …)` head is the \
                     `MoldePosicional` arm's canonical byte-shape"
                );
                let rendered = LeituraError::DialetoEstrangeiro { dialeto }.to_string();
                assert!(
                    rendered.contains(dialeto.palavra_canonica()),
                    "Display must interpolate `dialeto.palavra_canonica()` \
                     verbatim on the MoldePosicional arm; rendered: \
                     {rendered:?}"
                );
                assert!(
                    rendered.contains(dialeto.consumidor()),
                    "Display must interpolate `dialeto.consumidor()` \
                     verbatim on the MoldePosicional arm; rendered: \
                     {rendered:?}"
                );
                assert!(
                    rendered.contains(dialeto.descricao()),
                    "Display must interpolate `dialeto.descricao()` \
                     verbatim on the MoldePosicional arm; rendered: \
                     {rendered:?}"
                );
            }
            other => panic!("expected DialetoEstrangeiro, got {other:?}"),
        }
    }

    #[test]
    fn from_lisp_dialect_gate_dispatches_through_caixa_dialeto_is_molde_family_predicate() {
        // Load-bearing byte-parity pin: for every arm in
        // [`crate::dialeto::CaixaDialeto::ALL`], the
        // [`Caixa::from_lisp`] foreign-dialect gate's DialetoEstrangeiro
        // partition must agree with the lifted
        // [`crate::dialeto::CaixaDialeto::is_molde_family`] (e9d2315)
        // typed predicate — i.e. from_lisp raises
        // [`LeituraError::DialetoEstrangeiro`] carrying `d` iff
        // `d.is_molde_family()` returns `true`, and does NOT raise
        // [`LeituraError::DialetoEstrangeiro`] on any arm where the
        // predicate returns `false` (the arm's source falls through to
        // the derive — parses cleanly on
        // [`crate::dialeto::CaixaDialeto::Pacote`], surfaces a
        // [`LeituraError::Leitura`] on
        // [`crate::dialeto::CaixaDialeto::Desconhecido`]).
        //
        // Pre-lift the gate hand-rolled a three-arm match
        // (`Pacote => {}`, `Desconhecido => {}`, `foreign => Err(…)`)
        // whose `foreign =>` wildcard expressed no compile-time link
        // back to the substrate primitive's arm-family; a future fifth
        // dialect the [`crate::dialeto`] module doc's "third dialect"
        // hazard actualises would fall silently onto the wildcard
        // regardless of whether it belonged to the `defmolde` family or
        // to a distinct `defcaixa`-family. Post-lift the partition
        // resolves through
        // [`crate::dialeto::CaixaDialeto::is_molde_family`]'s single
        // typed dispatch, and this pin refuses any future regression
        // that silently split the from_lisp partition from the typed
        // predicate — the two paths now migrate as one on any future
        // arm addition.
        //
        // Sibling in shape to the peer
        // [`crate::dialeto::tests::caixa_dialeto_is_molde_family_agrees_with_palavra_canonica_defmolde_projection`]
        // (e9d2315) that pins the same byte-parity between
        // [`crate::dialeto::CaixaDialeto::is_molde_family`] and the
        // sibling [`crate::dialeto::CaixaDialeto::palavra_canonica`]
        // `== "defmolde"` classifier — extends the discipline from the
        // two paths within the [`crate::dialeto`] primitive onto the
        // third external consumer of the `defmolde`-family partition
        // (the [`Caixa::from_lisp`] gate that raises
        // [`LeituraError::DialetoEstrangeiro`]).
        let fixtures: &[(crate::dialeto::CaixaDialeto, &str)] = &[
            (
                crate::dialeto::CaixaDialeto::Pacote,
                r#"
                  (defcaixa
                    :nome   "checkout"
                    :versao "0.1.0"
                    :kind   Biblioteca
                    :edicao "2026"
                    :descricao "canonical Pacote source"
                    :autores ()
                    :etiquetas ()
                    :deps ()
                    :deps-dev ()
                    :bibliotecas ("lib/checkout.lisp"))
                "#,
            ),
            (
                crate::dialeto::CaixaDialeto::Molde,
                r#"
                  (defcaixa
                    :name "base64"
                    :kind :Biblioteca
                    :ecosystem :rust-single-crate
                    :package {:name "base64" :version "0.22.1"}
                    :workflows [:auto-release])
                "#,
            ),
            (
                crate::dialeto::CaixaDialeto::MoldePosicional,
                r#"
                  (defcaixa todoku-go
                    :kind :Biblioteca
                    :ecosystem :go
                    :package {:name "todoku-go" :version "0.3.0"})
                "#,
            ),
            (
                crate::dialeto::CaixaDialeto::Desconhecido,
                r#"(defcaixa :licenca "MIT")"#,
            ),
        ];

        // Coverage: every arm in [`crate::dialeto::CaixaDialeto::ALL`]
        // must appear in the fixture table so the pin's arm-set stays
        // synchronised with the enum's arm-set. Fails at test time if a
        // future fifth arm added to [`crate::dialeto::CaixaDialeto`]
        // (with a corresponding `is_molde_family` return) forgot to
        // extend this fixture table with a canonical source for the new
        // arm — the pin cannot cover an arm it has no source for.
        for &expected in crate::dialeto::CaixaDialeto::ALL {
            assert!(
                fixtures.iter().any(|(d, _)| *d == expected),
                "fixture table must carry a canonical source for every \
                 CaixaDialeto arm; missing: {expected:?}"
            );
        }

        for &(expected_dialect, src) in fixtures {
            let classified = crate::dialeto::classify(src.trim()).unwrap_or_else(|err| {
                panic!(
                    "fixture source for {expected_dialect:?} must classify \
                     cleanly, got err: {err:?}"
                )
            });
            assert_eq!(
                classified, expected_dialect,
                "fixture source for {expected_dialect:?} must classify as \
                 {expected_dialect:?} (drift here defeats the byte-parity \
                 pin below — a source labelled for one arm but classifying \
                 as another would silently satisfy or violate the pin for \
                 the wrong reason)"
            );

            let outcome = Caixa::from_lisp(src);
            match (expected_dialect.is_molde_family(), &outcome) {
                (true, Err(LeituraError::DialetoEstrangeiro { dialeto })) => {
                    assert_eq!(
                        *dialeto, expected_dialect,
                        "DialetoEstrangeiro must carry the same typed arm \
                         the classifier returned — a drift here would let \
                         from_lisp raise the error while pointing at the \
                         wrong dialect (e.g. rejecting a \
                         MoldePosicional source as Molde). arm: \
                         {expected_dialect:?}"
                    );
                }
                (true, other) => panic!(
                    "arm {expected_dialect:?} has is_molde_family() = true \
                     so from_lisp must raise DialetoEstrangeiro carrying \
                     {expected_dialect:?}; got: {other:?}"
                ),
                (false, Err(LeituraError::DialetoEstrangeiro { dialeto })) => panic!(
                    "arm {expected_dialect:?} has is_molde_family() = false \
                     so from_lisp must NOT raise DialetoEstrangeiro; got \
                     one carrying: {dialeto:?}. This means the typed \
                     predicate and the from_lisp partition disagree on \
                     this arm — exactly the drift this pin refuses."
                ),
                (false, _) => {
                    // A non-molde arm's source falls through to the
                    // derive: Pacote sources parse to Ok(_); Desconhecido
                    // sources surface as LeituraError::Leitura from the
                    // derive's own unknown-keyword rejection. Either
                    // shape is acceptable here — the pin's promise is
                    // narrower: "no DialetoEstrangeiro on
                    // is_molde_family() == false".
                }
            }
        }
    }

    // ── M2 typed-substrate slot tests (limits, behavior, upgrade-from, supervisor) ──

    #[test]
    fn limits_round_trip_via_json() {
        use crate::LimitsSpec;
        use std::time::Duration;
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.limits = Some(LimitsSpec {
            memory: Some(64 * 1024 * 1024),
            fuel: Some(1_000_000),
            wall_clock: Some(Duration::from_secs(30)),
            cpu: Some(500),
        });
        let json = serde_json::to_string(&c).unwrap();
        assert!(json.contains("\"limits\""));
        assert!(json.contains("\"64MiB\""));
        assert!(json.contains("\"30s\""));
        assert!(json.contains("\"500m\""));
        let back: Caixa = serde_json::from_str(&json).unwrap();
        assert_eq!(c.limits, back.limits);
    }

    #[test]
    fn behavior_round_trip_via_json() {
        use crate::BehaviorSpec;
        use std::path::PathBuf;
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.behavior = Some(BehaviorSpec {
            on_init: Some(PathBuf::from("lib/init.lisp")),
            on_call: Some(PathBuf::from("lib/handlers.lisp")),
            ..Default::default()
        });
        let json = serde_json::to_string(&c).unwrap();
        let back: Caixa = serde_json::from_str(&json).unwrap();
        assert_eq!(c.behavior, back.behavior);
    }

    #[test]
    fn upgrade_from_round_trip_via_json() {
        use crate::{UpgradeFromEntry, UpgradeInstruction};
        use std::path::PathBuf;
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.upgrade_from = vec![UpgradeFromEntry {
            from: "0.1.0".into(),
            instructions: vec![
                UpgradeInstruction::LoadModule {
                    module: "demo".into(),
                },
                UpgradeInstruction::StateChange {
                    script: PathBuf::from("lib/migrations/v01-to-v02.lisp"),
                },
                UpgradeInstruction::SoftPurge {
                    module: "demo-old".into(),
                },
            ],
        }];
        let json = serde_json::to_string(&c).unwrap();
        let back: Caixa = serde_json::from_str(&json).unwrap();
        assert_eq!(c.upgrade_from, back.upgrade_from);
    }

    #[test]
    fn supervisor_view_returns_typed_shape() {
        use crate::{ChildSpec, RestartPolicy, RestartStrategy};
        let mut c = Caixa::from_lisp(&Caixa::template("root")).unwrap();
        c.kind = CaixaKind::Supervisor;
        c.bibliotecas.clear();
        c.estrategia = Some(RestartStrategy::OneForOne);
        c.max_restarts = Some(5);
        c.restart_window = Some("60s".into());
        c.children = vec![ChildSpec {
            caixa: "worker".into(),
            versao: "^0.1".into(),
            restart: RestartPolicy::Permanent,
        }];
        let view = c.supervisor_view().expect("Supervisor kind has a view");
        assert_eq!(view.estrategia, RestartStrategy::OneForOne);
        assert_eq!(view.max_restarts, 5);
        assert_eq!(
            view.restart_window,
            Some(std::time::Duration::from_secs(60))
        );
        assert_eq!(view.children.len(), 1);
        view.validate().unwrap();
    }

    #[test]
    fn supervisor_view_none_for_non_supervisor_kinds() {
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        assert!(c.supervisor_view().is_none());
    }

    #[test]
    fn declared_mesh_slots_empty_for_bare_caixa() {
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        assert!(c.declared_mesh_slots().is_empty());
    }

    #[test]
    fn declared_mesh_slots_reports_only_set_slots_in_canonical_order() {
        use crate::{Entrada, Membro};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        // Set a non-adjacent pair (:membros + :entrada) to pin that the
        // canonical declaration order is preserved regardless of which
        // subset is populated.
        c.membros = vec![Membro {
            caixa: "a".into(),
            versao: "^0.1".into(),
        }];
        c.entrada = Some(Entrada {
            host: "x.example.com".into(),
            para: "a".into(),
            paths: vec![],
            port: 8080,
        });
        assert_eq!(
            c.declared_mesh_slots(),
            vec![
                crate::render::M3_AUTHOR_KEY_MEMBROS,
                crate::render::M3_AUTHOR_KEY_ENTRADA,
            ]
        );
    }

    #[test]
    fn m3_top_level_author_key_consts_pin_canonical_kebab_case_labels() {
        // Scalar-value pin: the five author-facing kebab-case labels the
        // `(defcaixa … :<slot> (…))` surface admits on the M3 top-level
        // mesh slot axis, one arm per typed slot. Mirrors the peer
        // scalar-value pin the sibling
        // [`crate::M2_AUTHOR_KEY_LIMITS`] /
        // [`crate::M2_AUTHOR_KEY_BEHAVIOR`] /
        // [`crate::M2_AUTHOR_KEY_UPGRADE_FROM`] M2 top-level slot consts
        // carry (f49c8b0), so both altitudes of the typed-slot algebra
        // (per-Servico M2 + per-Aplicacao M3) share the same
        // "one canonical byte-string per arm" discipline. A future
        // rebrand (`:membros` → `:members`, `:contratos` → `:contracts`,
        // `:politicas` → `:policies`, `:placement` → `:distribution`,
        // `:entrada` → `:ingress`) lands as an edit to exactly one const,
        // and every consumer that reaches for the label picks it up at
        // build time rather than at runtime as a downstream mismatch.
        assert_eq!(crate::render::M3_AUTHOR_KEY_MEMBROS, ":membros");
        assert_eq!(crate::render::M3_AUTHOR_KEY_CONTRATOS, ":contratos");
        assert_eq!(crate::render::M3_AUTHOR_KEY_POLITICAS, ":politicas");
        assert_eq!(crate::render::M3_AUTHOR_KEY_PLACEMENT, ":placement");
        assert_eq!(crate::render::M3_AUTHOR_KEY_ENTRADA, ":entrada");
    }

    #[test]
    fn declared_mesh_slots_route_through_lifted_m3_author_key_consts() {
        // Production-through-const pin: the five per-arm labels the
        // [`Caixa::declared_mesh_slots`] tagger pushes onto its return
        // `Vec` route through the lifted
        // [`crate::M3_AUTHOR_KEY_MEMBROS`] /
        // [`crate::M3_AUTHOR_KEY_CONTRATOS`] /
        // [`crate::M3_AUTHOR_KEY_POLITICAS`] /
        // [`crate::M3_AUTHOR_KEY_PLACEMENT`] /
        // [`crate::M3_AUTHOR_KEY_ENTRADA`] consts, in canonical
        // declaration order. A future re-order or drift at the tagger
        // (a rename that reaches the tagger but not the const, or vice
        // versa) surfaces here at build time rather than at runtime as
        // a [`crate::LayoutError::MeshSlotsOnNonAplicacao`]
        // `slots: <stale-kebab-case>` diagnostic far from the rename's
        // commit. Mirror of the peer
        // [`declared_servico_slots_route_through_lifted_m2_author_key_consts`]
        // pin (f49c8b0) on the sibling per-Servico M2 top-level slot
        // axis.
        use crate::{Entrada, Membro, MeshPolicy, Placement, PlacementStrategy, WitContract};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.membros = vec![Membro {
            caixa: "a".into(),
            versao: "^0.1".into(),
        }];
        c.contratos = vec![WitContract {
            de: "a".into(),
            para: "a".into(),
            wit: "wasi:http/proxy".into(),
            endpoint: Some("/x".into()),
            subject: None,
            slot: None,
        }];
        c.politicas = Some(MeshPolicy::default());
        c.placement = Some(Placement {
            estrategia: PlacementStrategy::Replicated,
            clusters: vec!["rio".into()],
            affinity: None,
            shard_key: None,
        });
        c.entrada = Some(Entrada {
            host: "x.example.com".into(),
            para: "a".into(),
            paths: vec![],
            port: 8080,
        });
        assert_eq!(
            c.declared_mesh_slots(),
            vec![
                crate::render::M3_AUTHOR_KEY_MEMBROS,
                crate::render::M3_AUTHOR_KEY_CONTRATOS,
                crate::render::M3_AUTHOR_KEY_POLITICAS,
                crate::render::M3_AUTHOR_KEY_PLACEMENT,
                crate::render::M3_AUTHOR_KEY_ENTRADA,
            ]
        );
    }

    #[test]
    fn declared_supervisor_slots_empty_for_bare_caixa() {
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        assert!(c.declared_supervisor_slots().is_empty());
    }

    #[test]
    fn declared_supervisor_slots_reports_only_set_slots_in_canonical_order() {
        use crate::RestartStrategy;
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        // Set a non-adjacent pair (:estrategia + :restart-window) to pin
        // that the canonical declaration order is preserved regardless
        // of which subset is populated.
        c.estrategia = Some(RestartStrategy::OneForOne);
        c.restart_window = Some("60s".into());
        assert_eq!(
            c.declared_supervisor_slots(),
            vec![
                crate::render::SUPERVISOR_AUTHOR_KEY_ESTRATEGIA,
                crate::render::SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW,
            ]
        );
    }

    #[test]
    fn supervisor_top_level_author_key_consts_pin_canonical_kebab_case_labels() {
        // Scalar-value pin: the four author-facing kebab-case labels the
        // `(defcaixa … :<slot> (…))` surface admits on the Supervisor
        // supervision-tree slot axis, one arm per typed slot. Mirrors the
        // peer scalar-value pins the sibling
        // [`crate::render::M2_AUTHOR_KEY_LIMITS`] /
        // [`crate::render::M2_AUTHOR_KEY_BEHAVIOR`] /
        // [`crate::render::M2_AUTHOR_KEY_UPGRADE_FROM`] top-level M2 slot
        // consts and [`crate::render::M3_AUTHOR_KEY_MEMBROS`] etc.
        // top-level M3 slot consts carry, so all three kind-scoped
        // typed-slot-family author-facing-label axes route through one
        // canonical per-arm declaration. A future rebrand
        // (`:estrategia` → `:strategy` for English uniformity,
        // `:max-restarts` → `:max-intensity` matching Erlang/OTP's
        // `MaxIntensity` name, `:restart-window` → `:period` matching
        // OTP's `Period` name, `:children` → `:workers` matching Elixir
        // idiom) lands as an edit to exactly one const, and every
        // consumer that reaches for the label picks it up at build time
        // rather than at runtime as a downstream mismatch.
        assert_eq!(
            crate::render::SUPERVISOR_AUTHOR_KEY_ESTRATEGIA,
            ":estrategia"
        );
        assert_eq!(
            crate::render::SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS,
            ":max-restarts"
        );
        assert_eq!(
            crate::render::SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW,
            ":restart-window"
        );
        assert_eq!(crate::render::SUPERVISOR_AUTHOR_KEY_CHILDREN, ":children");
    }

    #[test]
    fn declared_supervisor_slots_route_through_lifted_supervisor_author_key_consts() {
        // Production-through-const pin: the four per-arm labels the
        // [`Caixa::declared_supervisor_slots`] tagger pushes onto its
        // return `Vec` route through the lifted
        // [`crate::render::SUPERVISOR_AUTHOR_KEY_ESTRATEGIA`] /
        // [`crate::render::SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS`] /
        // [`crate::render::SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW`] /
        // [`crate::render::SUPERVISOR_AUTHOR_KEY_CHILDREN`] consts, in
        // canonical declaration order. A future re-order or drift at the
        // tagger (a rename that reaches the tagger but not the const, or
        // vice versa) surfaces here at build time rather than at runtime
        // as a [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`]
        // `slots: <stale-kebab-case>` diagnostic far from the rename's
        // commit. Mirror of the peer
        // [`declared_servico_slots_route_through_lifted_m2_author_key_consts`]
        // (f49c8b0) and
        // [`declared_mesh_slots_route_through_lifted_m3_author_key_consts`]
        // (882f498) pins on the sibling M2 / M3 top-level slot axes.
        use crate::{ChildSpec, RestartPolicy, RestartStrategy};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.estrategia = Some(RestartStrategy::OneForOne);
        c.max_restarts = Some(5);
        c.restart_window = Some("60s".into());
        c.children = vec![ChildSpec {
            caixa: "worker".into(),
            versao: "^0.1".into(),
            restart: RestartPolicy::Permanent,
        }];
        assert_eq!(
            c.declared_supervisor_slots(),
            vec![
                crate::render::SUPERVISOR_AUTHOR_KEY_ESTRATEGIA,
                crate::render::SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS,
                crate::render::SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW,
                crate::render::SUPERVISOR_AUTHOR_KEY_CHILDREN,
            ]
        );
    }

    #[test]
    fn declared_servico_slots_empty_for_bare_caixa() {
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        assert!(c.declared_servico_slots().is_empty());
    }

    #[test]
    fn declared_servico_slots_reports_only_set_slots_in_canonical_order() {
        use crate::{UpgradeFromEntry, UpgradeInstruction};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        // Set a non-adjacent pair (:limits + :upgrade-from) to pin that
        // the canonical declaration order is preserved regardless of
        // which subset is populated.
        c.limits = Some(crate::LimitsSpec {
            fuel: Some(1_000_000),
            ..Default::default()
        });
        c.upgrade_from = vec![UpgradeFromEntry {
            from: "0.1.0".into(),
            instructions: vec![UpgradeInstruction::Restart],
        }];
        assert_eq!(
            c.declared_servico_slots(),
            vec![
                crate::render::M2_AUTHOR_KEY_LIMITS,
                crate::render::M2_AUTHOR_KEY_UPGRADE_FROM,
            ]
        );
    }

    #[test]
    fn m2_top_level_author_key_consts_pin_canonical_kebab_case_labels() {
        // Scalar-value pin: the three author-facing kebab-case labels
        // the `(defcaixa … :<slot> (…))` surface admits on the M2
        // top-level slot axis, one arm per typed slot. Mirrors the peer
        // scalar-value pin the sibling renderer-side
        // [`crate::M2_KEY_LIMITS`] / [`crate::M2_KEY_BEHAVIOR`] /
        // [`crate::M2_KEY_UPGRADE_FROM`] camelCase overlay-container
        // consts carry, so both halves of the M2 top-level slot dual
        // axis (author-facing kebab-case label + renderer-side
        // camelCase overlay-container wire key) route through one
        // canonical per-arm declaration. A future rebrand
        // (`:limits` → `:sandbox` matching Lunatic per-process
        // terminology INSPIRATIONS §III.1, `:behavior` → `:gen-server`
        // matching Erlang's verbatim name, `:upgrade-from` → `:appup`
        // matching Erlang's verbatim appup name) lands as an edit to
        // exactly one const, and every consumer that reaches for the
        // label picks it up at build time rather than at runtime as a
        // downstream mismatch.
        assert_eq!(crate::render::M2_AUTHOR_KEY_LIMITS, ":limits");
        assert_eq!(crate::render::M2_AUTHOR_KEY_BEHAVIOR, ":behavior");
        assert_eq!(crate::render::M2_AUTHOR_KEY_UPGRADE_FROM, ":upgrade-from");
    }

    #[test]
    fn declared_servico_slots_route_through_lifted_m2_author_key_consts() {
        // Production-through-const pin: the three per-arm labels the
        // [`Caixa::declared_servico_slots`] tagger pushes onto its
        // return `Vec` route through the lifted
        // [`crate::M2_AUTHOR_KEY_LIMITS`] /
        // [`crate::M2_AUTHOR_KEY_BEHAVIOR`] /
        // [`crate::M2_AUTHOR_KEY_UPGRADE_FROM`] consts, in canonical
        // declaration order. A future re-order or drift at the tagger
        // (a rename that reaches the tagger but not the const, or vice
        // versa) surfaces here at build time rather than at runtime as
        // a [`crate::LayoutError::ServicoSlotsOnNonServico`]
        // `slots: <stale-kebab-case>` diagnostic far from the rename's
        // commit. Mirror of the peer
        // [`crate::behavior::BehaviorSpec::declared_slots`] production
        // tagger pin (889dc18) on the sibling per-callback axis.
        use crate::{BehaviorSpec, UpgradeFromEntry, UpgradeInstruction};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.limits = Some(crate::LimitsSpec {
            fuel: Some(1_000_000),
            ..Default::default()
        });
        c.behavior = Some(BehaviorSpec {
            on_init: Some(PathBuf::from("lib/init.lisp")),
            ..Default::default()
        });
        c.upgrade_from = vec![UpgradeFromEntry {
            from: "0.1.0".into(),
            instructions: vec![UpgradeInstruction::Restart],
        }];
        assert_eq!(
            c.declared_servico_slots(),
            vec![
                crate::render::M2_AUTHOR_KEY_LIMITS,
                crate::render::M2_AUTHOR_KEY_BEHAVIOR,
                crate::render::M2_AUTHOR_KEY_UPGRADE_FROM,
            ]
        );
    }

    #[test]
    fn existing_manifests_unaffected_by_new_optional_slots() {
        // Regression test: a caixa.lisp authored before M2 typed slots
        // should still parse + serialize cleanly. The bare `defcaixa`
        // emitted by `Caixa::template` has none of the new fields.
        let src = Caixa::template("legacy");
        let c = Caixa::from_lisp(&src).unwrap();
        assert!(c.limits.is_none());
        assert!(c.behavior.is_none());
        assert!(c.upgrade_from.is_empty());
        assert!(c.estrategia.is_none());
        assert!(c.children.is_empty());

        // And to_lisp emits a manifest with the new slots in the
        // empty/default state — round-trippable.
        let emitted = c.to_lisp();
        let back = Caixa::from_lisp(&emitted).unwrap();
        assert_eq!(c, back);
    }

    #[test]
    fn validate_deps_accepts_canonical_caixa() {
        // Positive control: the bare template — zero deps, zero
        // deps_dev — passes the gate trivially. A future axis added to
        // `Dep::validate` mustn't regress an empty-deps caixa to a
        // build error.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_deps().unwrap();
    }

    #[test]
    fn validate_deps_rejects_invalid_versao_in_deps() {
        // Fail-before-pass-after pin: a malformed `:deps :versao`
        // surfaces at validate_deps() time, not at lacre-resolve time.
        // Mirrors `rejects_invalid_membro_versao_requirement` and
        // `validate_rejects_invalid_child_versao_requirement` on the
        // other two `:versao` axes.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep::simple("caixa-teia", "^bad-version")];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                crate::dep::DepError::VersaoInvalid { ref nome, ref versao, .. }
                    if nome == "caixa-teia" && versao == "^bad-version"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_deps_rejects_invalid_versao_in_deps_dev() {
        // Parity pin: `:deps-dev` must run through the same per-entry
        // validator as `:deps` — a typo in either axis surfaces the
        // same diagnostic. Without this leg, `:deps-dev` would be a
        // second-class citizen of the typed surface and an author
        // could land a build that passes validate_deps but fails at
        // `feira lock`-time when the dev-dep is resolved for a test
        // build.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps_dev = vec![Dep::simple("tatara-check", "^^0.1")];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                crate::dep::DepError::VersaoInvalid { ref nome, ref versao, .. }
                    if nome == "tatara-check" && versao == "^^0.1"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_deps_runs_deps_before_deps_dev() {
        // Order pin: when both lists carry typos, the `:deps`
        // diagnostic surfaces first. The author's mental model is
        // "runtime deps are load-bearing; dev deps are scaffolding";
        // surfacing the runtime axis first matches that hierarchy.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep::simple("runtime-dep", "^bad-runtime")];
        c.deps_dev = vec![Dep::simple("dev-dep", "^bad-dev")];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                crate::dep::DepError::VersaoInvalid { ref nome, .. }
                    if nome == "runtime-dep"
            ),
            "expected `:deps` typo to surface first, got {err:?}"
        );
    }

    #[test]
    fn validate_deps_accepts_canonical_versao_forms_in_both_lists() {
        // Positive control sweep across both lists. Pin every
        // canonical Cargo-shaped form so a future tightening of the
        // accepted set surfaces here as a test failure (parity with
        // `accepts_canonical_membro_versao_forms` and
        // `validate_accepts_canonical_child_versao_forms`).
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![
            Dep::simple("caret", "^0.1"),
            Dep::simple("tilde", "~0.1.2"),
            Dep::simple("exact", "0.1.0"),
            Dep::simple("wildcard", "*"),
            Dep::simple("multi-range", ">=0.1, <2"),
        ];
        c.deps_dev = vec![
            Dep::simple("dev-caret", "^0.1"),
            Dep::simple("dev-wildcard", "*"),
        ];
        c.validate_deps().unwrap();
    }

    #[test]
    fn validate_deps_diagnostic_carries_offending_dep() {
        // Diagnostic-shape pin: the error names the offending entry's
        // `:nome` + `:versao` verbatim and carries a non-empty
        // `reason` from `semver::VersionReq::parse`, so a `feira lint`
        // run can render the diagnostic without re-parsing.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep::simple("caixa-teia", "not-a-req")];
        let err = c.validate_deps().unwrap_err();
        let crate::dep::DepError::VersaoInvalid {
            nome,
            versao,
            reason,
        } = err
        else {
            panic!("expected VersaoInvalid, got other variant");
        };
        assert_eq!(nome, "caixa-teia");
        assert_eq!(versao, "not-a-req");
        assert!(
            !reason.is_empty(),
            "VersaoInvalid `reason` must carry the parser's wording verbatim"
        );
    }

    #[test]
    fn validate_deps_rejects_ambiguous_fonte_in_deps_dev() {
        // Cross-axis pin: `validate_deps` walks both :deps and
        // :deps-dev through `Dep::validate`, and the new fonte gate
        // (`:tag` + `:branch` both set — the canonical "pin drift"
        // footgun) must surface from the :deps-dev arm with the
        // offending entry's :nome named. Pin the :deps-dev arm
        // explicitly so a future shortcut that only walks :deps
        // surfaces here as a regression.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps_dev = vec![Dep {
            nome: "dev-only".into(),
            versao: "^0.1".into(),
            fonte: Some(crate::DepSource::Git {
                repo: "github:p/x".into(),
                tag: Some("v1".into()),
                rev: None,
                branch: Some("main".into()),
            }),
            opcional: false,
            caracteristicas: vec![],
        }];
        let err = c.validate_deps().unwrap_err();
        let crate::dep::DepError::FontePinAmbiguous { nome, pins } = err else {
            panic!("expected FontePinAmbiguous from :deps-dev walk");
        };
        assert_eq!(nome, "dev-only");
        assert!(pins.contains(":tag") && pins.contains(":branch"));
    }

    #[test]
    fn validate_deps_rejects_empty_repo_in_deps() {
        // Parity pin on the :deps arm: an empty :repo on the runtime
        // deps list surfaces the same FonteRepoEmpty diagnostic the
        // dep.rs per-entry tests pin, naming the offending entry.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep {
            nome: "runtime".into(),
            versao: "^0.1".into(),
            fonte: Some(crate::DepSource::Git {
                repo: String::new(),
                tag: Some("v1".into()),
                rev: None,
                branch: None,
            }),
            opcional: false,
            caracteristicas: vec![],
        }];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                crate::dep::DepError::FonteRepoEmpty { ref nome }
                    if nome == "runtime"
            ),
            "got {err:?}"
        );
    }

    // ── validate_deps: within-list :nome set-not-multiset gate ─────────

    #[test]
    fn validate_deps_rejects_duplicate_nome_in_deps() {
        // Fail-before-pass-after pin: two `:deps` entries naming the same
        // caixa carry two `:versao` / `:fonte` / feature triples that the
        // caixa-resolver's lacre pipeline collapses (the second silently
        // overwrites the first at `concrete_versao`-resolve time). The
        // gate surfaces the duplicate at validate-time, naming the
        // offending caixa + the list, before the resolver-side silent
        // drop. Mirrors the peer typed-graph duplicate gates
        // (`DuplicateChildCaixa`, `MembroDuplicate`, `DuplicateFrom`, …).
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![
            Dep::simple("caixa-teia", "^0.1"),
            Dep::simple("caixa-teia", "^0.2"),
        ];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                crate::dep::DepError::DuplicateNome { ref nome, list }
                    if nome == "caixa-teia" && list == crate::render::DEP_AUTHOR_KEY_DEPS
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_deps_rejects_duplicate_nome_in_deps_dev() {
        // Parity pin: `:deps-dev` runs through the same per-list
        // duplicate check as `:deps` — neither axis is a second-class
        // citizen of the set-not-multiset discipline.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps_dev = vec![
            Dep::simple("tatara-check", "*"),
            Dep::simple("tatara-check", "^0.1"),
        ];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                crate::dep::DepError::DuplicateNome { ref nome, list }
                    if nome == "tatara-check" && list == crate::render::DEP_AUTHOR_KEY_DEPS_DEV
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_deps_accepts_cross_list_same_nome() {
        // The Cargo `[dependencies]` + `[dev-dependencies]` override
        // convention is preserved: a name appearing in *both* lists is
        // valid (the dev-pin overrides at test/dev time). Only
        // within-list duplicates are structurally incoherent — pin the
        // permissive cross-list semantics so a future shortcut that
        // collapses the two seen-sets into one surfaces here as a test
        // failure.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep::simple("caixa-teia", "^0.1")];
        c.deps_dev = vec![Dep::simple("caixa-teia", "^0.2")];
        c.validate_deps().unwrap();
    }

    #[test]
    fn validate_deps_accepts_distinct_nome_in_both_lists() {
        // Positive control: distinct names within each list pass — the
        // gate's identity element on the canonical authoring shape.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![
            Dep::simple("caixa-teia", "^0.1"),
            Dep::simple("pleme-mesh", "*"),
        ];
        c.deps_dev = vec![
            Dep::simple("tatara-check", "*"),
            Dep::simple("dev-shim", "^0.1"),
        ];
        c.validate_deps().unwrap();
    }

    #[test]
    fn validate_deps_per_entry_validate_fires_before_duplicate_in_deps() {
        // Diagnostic-precedence pin: a malformed `:versao` on the
        // duplicating entry surfaces its narrower `VersaoInvalid`
        // diagnostic first, before the cross-entry duplicate gate fires
        // — the canonical "per-entry shape before cross-entry uniqueness"
        // precedence every peer set-not-multiset gate establishes
        // (`*_invalid_fires_before_duplicate_check` pins on
        // `SupervisorSpec::validate`, `AplicacaoSpec::validate_membros`,
        // `validate_upgrade_from`).
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![
            Dep::simple("caixa-teia", "^0.1"),
            Dep::simple("caixa-teia", "^bad-version"),
        ];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                crate::dep::DepError::VersaoInvalid { ref nome, ref versao, .. }
                    if nome == "caixa-teia" && versao == "^bad-version"
            ),
            "expected VersaoInvalid to surface before DuplicateNome, got {err:?}"
        );
    }

    #[test]
    fn validate_deps_duplicate_diagnostic_names_first_collision() {
        // First-collision determinism pin: with three entries naming the
        // same caixa, the first colliding pair surfaces — not the last.
        // Mirrors the peer first-collision posture on every
        // duplicate-target gate
        // (`validate_upgrade_from_duplicate_diagnostic_names_second_collision`
        // — the second entry is the first collision; this gate uses the
        // same shape: the second entry's `:nome` lands in the diagnostic
        // because `seen.insert(first.nome)` already populated the set).
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![
            Dep::simple("caixa-teia", "^0.1"),
            Dep::simple("caixa-teia", "^0.2"),
            Dep::simple("caixa-teia", "^0.3"),
        ];
        let err = c.validate_deps().unwrap_err();
        // The diagnostic carries the offending caixa name; the
        // implementation surfaces on the *second* entry (the first
        // collision), so the test pins the `:nome` value.
        assert!(
            matches!(
                err,
                crate::dep::DepError::DuplicateNome { ref nome, list }
                    if nome == "caixa-teia" && list == crate::render::DEP_AUTHOR_KEY_DEPS
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_deps_duplicate_in_deps_fires_before_duplicate_in_deps_dev() {
        // Cross-list precedence pin: when both lists carry duplicates,
        // the `:deps` diagnostic surfaces first — same author-mental-
        // model ordering the `validate_deps_runs_deps_before_deps_dev`
        // pin establishes for malformed `:versao` (runtime axis before
        // dev axis).
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![
            Dep::simple("runtime-dep", "^0.1"),
            Dep::simple("runtime-dep", "^0.2"),
        ];
        c.deps_dev = vec![Dep::simple("dev-dep", "*"), Dep::simple("dev-dep", "^0.1")];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                crate::dep::DepError::DuplicateNome { ref nome, list }
                    if nome == "runtime-dep" && list == crate::render::DEP_AUTHOR_KEY_DEPS
            ),
            "expected :deps duplicate to surface before :deps-dev duplicate, got {err:?}"
        );
    }

    #[test]
    fn validate_deps_empty_lists_pass_duplicate_gate() {
        // Empty-set identity pin: the bare template (zero deps, zero
        // deps_dev) passes the duplicate gate as the gate's identity
        // element. A future tighten that conflates "empty" with
        // "missing" would regress this baseline.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_deps().unwrap();
    }

    #[test]
    fn validate_deps_duplicate_diagnostic_carries_list_tag() {
        // Diagnostic-shape pin: the `list:` field tags which list the
        // duplicate landed in (`:deps` vs `:deps-dev`) verbatim, so a
        // `feira lint` run can route the author to the right block in
        // their caixa.lisp without re-deriving the list from context.
        // Same self-locating shape every peer per-axis diagnostic
        // already exposes.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps_dev = vec![
            Dep::simple("dev-thing", "*"),
            Dep::simple("dev-thing", "^0.1"),
        ];
        let err = c.validate_deps().unwrap_err();
        let crate::dep::DepError::DuplicateNome { nome, list } = err else {
            panic!("expected DuplicateNome from :deps-dev walk");
        };
        assert_eq!(nome, "dev-thing");
        assert_eq!(list, crate::render::DEP_AUTHOR_KEY_DEPS_DEV);
    }

    // ── validate_deps: per-entry :caracteristicas set-discipline gate ──

    #[test]
    fn validate_deps_surfaces_caracteristicas_duplicate_in_deps_list() {
        // Thread-through pin on `:deps`: the per-entry
        // `Dep::validate_caracteristicas` gate fires inside
        // `Caixa::validate_deps`'s linear walk, so a malformed feature
        // list on any `:deps` entry surfaces as a `DepError` from
        // `validate_deps` — the same reachability shape every per-entry
        // `Dep::validate` arm threads through. Without this pin a future
        // shortcut that skips the per-entry `Dep::validate` call on the
        // cross-entry-uniqueness path would mask the within-entry
        // `:caracteristicas` gates.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep {
            nome: "caixa-teia".into(),
            versao: "^0.1".into(),
            fonte: None,
            opcional: false,
            caracteristicas: vec!["http".into(), "http".into()],
        }];
        let err = c.validate_deps().unwrap_err();
        let crate::dep::DepError::CaracteristicaDuplicate {
            nome,
            caracteristica,
        } = err
        else {
            panic!("expected CaracteristicaDuplicate from :deps walk, got {err:?}");
        };
        assert_eq!(nome, "caixa-teia");
        assert_eq!(caracteristica, "http");
    }

    #[test]
    fn validate_deps_surfaces_caracteristicas_empty_in_deps_dev_list() {
        // Peer thread-through pin on `:deps-dev`: same reachability as
        // the `:deps` arm above, on the dev-only authoring axis. Pins
        // that the `validate_deps` walk visits both lists' per-entry
        // gates uniformly. The empty-feature arm carries here so both
        // new `:caracteristicas` arms are surfaced via at least one
        // `validate_deps` thread-through.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps_dev = vec![Dep {
            nome: "caixa-teia".into(),
            versao: "^0.1".into(),
            fonte: None,
            opcional: false,
            caracteristicas: vec![String::new()],
        }];
        let err = c.validate_deps().unwrap_err();
        let crate::dep::DepError::CaracteristicaEmpty { nome } = err else {
            panic!("expected CaracteristicaEmpty from :deps-dev walk, got {err:?}");
        };
        assert_eq!(nome, "caixa-teia");
    }

    #[test]
    fn validate_deps_surfaces_caracteristicas_invalid_in_deps_list() {
        // Thread-through pin on `:deps`: the per-entry
        // `Dep::validate_caracteristicas` value-shape gate (lifted via
        // `crate::render::is_cargo_feature_name`) fires inside
        // `Caixa::validate_deps`'s linear walk on the `:deps` list, so
        // a structurally invalid feature name on any `:deps` entry
        // surfaces as `DepError::CaracteristicaInvalid` from
        // `validate_deps` — the same reachability shape every per-entry
        // `Dep::validate` arm threads through. Without this pin a
        // future shortcut that skips the per-entry `Dep::validate` call
        // on the cross-entry-uniqueness path would mask the within-
        // entry `:caracteristicas` value-shape gate.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep {
            nome: "caixa-teia".into(),
            versao: "^0.1".into(),
            fonte: None,
            opcional: false,
            caracteristicas: vec!["+http".into()],
        }];
        let err = c.validate_deps().unwrap_err();
        let crate::dep::DepError::CaracteristicaInvalid {
            nome,
            caracteristica,
            ..
        } = err
        else {
            panic!("expected CaracteristicaInvalid from :deps walk, got {err:?}");
        };
        assert_eq!(nome, "caixa-teia");
        assert_eq!(caracteristica, "+http");
    }

    #[test]
    fn validate_deps_surfaces_caracteristicas_invalid_in_deps_dev_list() {
        // Peer thread-through pin on `:deps-dev`: same reachability as
        // the `:deps` arm above, on the dev-only authoring axis. The
        // `http/json` shape carries here so the segment-separator
        // diagnostic (the canonical Cargo `dep/feat` namespaced-dep
        // confusion footgun) is surfaced via the cross-entry walk too —
        // pinning that the `:deps-dev` list visits the same per-entry
        // value-shape gate as the `:deps` list.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps_dev = vec![Dep {
            nome: "caixa-teia".into(),
            versao: "^0.1".into(),
            fonte: None,
            opcional: false,
            caracteristicas: vec!["http/json".into()],
        }];
        let err = c.validate_deps().unwrap_err();
        let crate::dep::DepError::CaracteristicaInvalid {
            nome,
            caracteristica,
            ..
        } = err
        else {
            panic!("expected CaracteristicaInvalid from :deps-dev walk, got {err:?}");
        };
        assert_eq!(nome, "caixa-teia");
        assert_eq!(caracteristica, "http/json");
    }

    #[test]
    fn to_lisp_preserves_deps() {
        let src = r#"
(defcaixa
  :nome "x"
  :versao "0.1.0"
  :kind Biblioteca
  :deps ((:nome "a" :versao "^0.1")
         (:nome "b" :versao "*" :fonte (:tipo git :repo "github:o/b" :tag "v1"))))
"#;
        let c1 = Caixa::from_lisp(src).unwrap();
        let emitted = c1.to_lisp();
        let c2 = Caixa::from_lisp(&emitted).expect("round trip");
        assert_eq!(c1.deps, c2.deps);
    }

    // ── Caixa::validate_nome — top-level :nome value-shape gate ─────────

    fn caixa_with_nome(nome: &str) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("placeholder")).unwrap();
        c.nome = nome.to_string();
        c
    }

    #[test]
    fn validate_nome_accepts_canonical_template() {
        // Positive control: the bare `feira init`-style template's
        // `:nome` ("demo") is a canonical DNS-1123 label; the gate must
        // not regress this baseline shape. A future tightening of the
        // accepted set surfaces here as a test failure first.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_nome().unwrap();
    }

    #[test]
    fn validate_nome_accepts_canonical_forms() {
        // Positive-set sweep: each realistic caixa-name shape the K8s
        // apiserver accepts as a `metadata.name` label must pass —
        // single-word, hyphen-joined, version-suffixed, single-char,
        // two-char, digit-start (DNS-1123 allows this; the stricter
        // DNS-1035 Service-name rule doesn't), version-suffix-bearing.
        // Mirrors `accepts_canonical_membro_caixa_forms` (3f9d7a0) on
        // the peer member-name axis.
        for nome in [
            "checkout",
            "cart-v2",
            "a",
            "db",
            "3rd-party-shim",
            "payment-retry",
            "0",
        ] {
            caixa_with_nome(nome)
                .validate_nome()
                .unwrap_or_else(|e| panic!("canonical :nome {nome:?} must validate, got {e:?}"));
        }
    }

    #[test]
    fn validate_nome_rejects_empty() {
        // Fail-before-pass-after pin: `Caixa::from_lisp` does not refuse
        // an empty `:nome` (the derive macro stores the raw String);
        // the gate's empty arm names the offending axis with a narrower
        // diagnostic than the `NomeInvalid` parse arm would emit.
        let c = caixa_with_nome("");
        let err = c.validate_nome().unwrap_err();
        assert_eq!(err, ManifestError::NomeEmpty);
    }

    #[test]
    fn validate_nome_rejects_uppercase() {
        // The canonical "I copied the TitleCase display name verbatim"
        // footgun. The K8s apiserver rejects `metadata.name: MyApp` at
        // admission on every derived artifact (Helm chart, ComputeUnit,
        // CNP, HTTPRoute, label values); the gate moves the diagnostic
        // to the source `caixa.lisp` and the reason suggests the
        // lowercased fix verbatim.
        let c = caixa_with_nome("MyApp");
        let err = c.validate_nome().unwrap_err();
        let ManifestError::NomeInvalid { nome, reason } = err else {
            panic!("expected NomeInvalid for uppercase :nome");
        };
        assert_eq!(nome, "MyApp");
        assert!(
            reason.contains("uppercase") && reason.contains("myapp"),
            "diagnostic must name the violation + the lowercased fix, got {reason:?}"
        );
    }

    #[test]
    fn validate_nome_rejects_underscore() {
        // The Python-/Postgres-style `snake_case` leak. DNS-1123 forbids
        // `_`; the apiserver rejects on admission across every derived
        // artifact. Same fixture pinned for `:membros :caixa` (3f9d7a0)
        // and `:children :caixa` (31bfa43).
        let c = caixa_with_nome("my_app");
        let err = c.validate_nome().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::NomeInvalid { ref nome, ref reason }
                    if nome == "my_app" && reason.contains('_')
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_nome_rejects_dot() {
        // A `:nome` is a single DNS-1123 label, not a subdomain. The
        // "I want to namespace with `.`" footgun the gate redirects to
        // `-` via the shared predicate's reason wording.
        let c = caixa_with_nome("team.app");
        let err = c.validate_nome().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::NomeInvalid { ref nome, ref reason }
                    if nome == "team.app" && reason.contains('.')
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_nome_rejects_leading_hyphen() {
        // DNS-1123 boundary rule: the label must start with an ASCII
        // alphanumeric. Pin the leading-`-` arm explicitly.
        let c = caixa_with_nome("-app");
        let err = c.validate_nome().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::NomeInvalid { ref nome, .. } if nome == "-app"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_nome_rejects_trailing_hyphen() {
        // Symmetric arm of the boundary rule, pinned separately so a
        // future relaxation that only checks the leading position
        // surfaces here. Mirrors `rejects_membro_caixa_with_trailing_hyphen`
        // and `_with_trailing_hyphen` on the supervisor / aplicacao
        // axes.
        let c = caixa_with_nome("app-");
        let err = c.validate_nome().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::NomeInvalid { ref nome, .. } if nome == "app-"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_nome_rejects_unicode() {
        // IDN must be pre-encoded as Punycode (`xn--…`); raw Unicode
        // bytes are rejected by the K8s apiserver on every name axis.
        let c = caixa_with_nome("café");
        let err = c.validate_nome().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::NomeInvalid { ref nome, .. } if nome == "café"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_nome_rejects_whitespace() {
        // The paste-from-sketch / paste-from-spec footgun. Internal
        // whitespace is rejected by every K8s name axis.
        let c = caixa_with_nome("my app");
        let err = c.validate_nome().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::NomeInvalid { ref nome, .. } if nome == "my app"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_nome_rejects_too_long() {
        // 64-byte boundary pin: the K8s apiserver rejects any
        // `metadata.name` over 63 bytes at admission; the diagnostic
        // names both the 63-byte cap and the actual length so the
        // author can shorten in one edit. Mirrors `_too_long` on the
        // peer member-/cluster-/child-name axes.
        let over = "a".repeat(crate::DNS_1123_LABEL_MAX_LEN + 1);
        let c = caixa_with_nome(&over);
        let err = c.validate_nome().unwrap_err();
        let ManifestError::NomeInvalid { nome, reason } = err else {
            panic!("expected NomeInvalid for over-cap :nome");
        };
        assert_eq!(nome.len(), crate::DNS_1123_LABEL_MAX_LEN + 1);
        assert!(
            reason.contains("63") && reason.contains("64"),
            "diagnostic must name the cap + actual length, got {reason:?}"
        );
    }

    #[test]
    fn nome_max_length_validates() {
        // The 63-byte cap exactly — the boundary-accepting case pinned
        // alongside `validate_nome_rejects_too_long` so a future cap
        // shift surfaces both arms simultaneously. Mirrors
        // `membro_caixa_max_length_validates`,
        // `placement_cluster_max_length_validates`,
        // `child_caixa_max_length_validates`.
        let at_cap = "a".repeat(crate::DNS_1123_LABEL_MAX_LEN);
        caixa_with_nome(&at_cap).validate_nome().unwrap();
    }

    #[test]
    fn nome_empty_takes_precedence_over_invalid() {
        // Order pin: the empty arm fires before the predicate is
        // consulted. Empty < invalid in self-locating-ness — the
        // narrower `NomeEmpty` diagnostic doesn't carry a useless
        // `nome: ""` reference into the parser-shaped reason. Mirrors
        // `membro_caixa_empty_takes_precedence_over_invalid` on the
        // peer axis (3f9d7a0).
        let c = caixa_with_nome("");
        assert_eq!(c.validate_nome().unwrap_err(), ManifestError::NomeEmpty);
    }

    #[test]
    fn nome_invalid_diagnostic_carries_offending_nome() {
        // Diagnostic-shape pin: the error names the offending `:nome`
        // verbatim with a non-empty parser-shaped reason, so a `feira
        // lint` run can render the diagnostic without re-parsing.
        // Mirrors `membro_caixa_invalid_diagnostic_carries_offending_caixa`.
        let c = caixa_with_nome("MyApp");
        let err = c.validate_nome().unwrap_err();
        let ManifestError::NomeInvalid { nome, reason } = err else {
            panic!("expected NomeInvalid variant");
        };
        assert_eq!(nome, "MyApp");
        assert!(
            !reason.is_empty(),
            "NomeInvalid `reason` must carry the predicate's wording verbatim"
        );
    }

    // ── Caixa::validate_nome_chart_name_budget — joint-length on `:nome` ──
    //
    // The bare-`:nome` axis [`Caixa::validate_nome`] caps at 63 bytes
    // via DNS-1123; this second-axis gate caps the joint
    // `lareira-<nome>` chart name at the same 63-byte ceiling. The
    // canonical [`crate::lareira_chart_name`] helper's doc comment
    // (f7320d7, caixa-core/src/render.rs:3198) explicitly deferred:
    // "the M4 admission webhook will pin the joint-length invariant
    // when it lands". These tests pin it at the manifest-validate
    // layer instead, fail-before-pass-after on the 56-byte boundary.

    #[test]
    fn validate_nome_chart_name_budget_accepts_canonical_template() {
        // Positive control: the bare `feira init`-style template's
        // `:nome` ("demo") sits far below the cap; the gate must not
        // regress this baseline. Same shape every peer
        // value-shape-gate baseline pin uses.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_nome_chart_name_budget().unwrap();
    }

    #[test]
    fn validate_nome_chart_name_budget_accepts_canonical_fixtures() {
        // Positive-set sweep across the canonical author surface every
        // in-tree fixture uses (`hello-rio`, `cart`, `checkout`,
        // `worker`, the `checkout-aplicacao` example members, the
        // `example-attest` caixa-tatara fixture). Every value sits
        // far below the 55-byte per-`:nome` budget. Same shape every
        // peer per-axis baseline pin uses.
        for nome in [
            "hello-rio",
            "cart",
            "checkout",
            "worker",
            "example-attest",
            "demo",
            "a",
        ] {
            caixa_with_nome(nome)
                .validate_nome_chart_name_budget()
                .unwrap_or_else(|e| {
                    panic!("canonical :nome {nome:?} must pass chart-name budget, got {e:?}")
                });
        }
    }

    #[test]
    fn validate_nome_chart_name_budget_accepts_nome_at_cap() {
        // Boundary-accepting case at the 55-byte per-`:nome` budget —
        // the joint chart name is exactly 63 bytes, the DNS-1123 label
        // cap. Pinned alongside the rejecting-arm test so a future cap
        // shift surfaces both arms simultaneously. Mirrors
        // `nome_max_length_validates` on the peer bare-`:nome` axis.
        let at_cap = "a".repeat(crate::LAREIRA_CHART_NAME_NOME_MAX_LEN);
        caixa_with_nome(&at_cap)
            .validate_nome_chart_name_budget()
            .unwrap();
    }

    #[test]
    fn validate_nome_chart_name_budget_rejects_nome_one_over_cap() {
        // Fail-before-pass-after pin on the 56-byte boundary: the
        // smallest `:nome` length that overflows the joint chart-name
        // cap. The inner [`is_dns_1123_label`] gate
        // (`Caixa::validate_nome`) accepts it (56 ≤ 63), so prior to
        // this gate it silently passed the manifest-validate cascade
        // and surfaced as a `helm lint` / apiserver rejection on the
        // rendered chart name far from the source `caixa.lisp`, with
        // no field naming the overflow. With this gate the diagnostic
        // names the offending `:nome` verbatim alongside the rendered
        // chart name and the budget, so the author can shorten in one
        // edit. Mirrors `validate_nome_rejects_too_long` on the peer
        // bare-`:nome` axis.
        let over = "a".repeat(crate::LAREIRA_CHART_NAME_NOME_MAX_LEN + 1);
        let c = caixa_with_nome(&over);
        let err = c.validate_nome_chart_name_budget().unwrap_err();
        let ManifestError::NomeChartNameBudgetExceeded { nome, reason } = err else {
            panic!("expected NomeChartNameBudgetExceeded for over-budget :nome");
        };
        assert_eq!(nome.len(), crate::LAREIRA_CHART_NAME_NOME_MAX_LEN + 1);
        assert_eq!(nome, over);
        assert!(
            reason.contains("63") && reason.contains("64") && reason.contains("55"),
            "diagnostic must name the DNS-1123 cap (63), the actual chart-name length (64), \
             and the per-`:nome` budget (55), got {reason:?}"
        );
    }

    #[test]
    fn validate_nome_chart_name_budget_rejects_nome_at_bare_dns_cap() {
        // The 63-byte `:nome` boundary — passes the bare-`:nome`
        // [`is_dns_1123_label`] cap exactly, but produces a 71-byte
        // joint chart name that overflows the DNS-1123 label cap
        // structurally. The most stringent fail-before-pass-after
        // surface: every `:nome` in the 56..=63-byte range passed the
        // prior cascade and broke at admission.
        let bare_max = "a".repeat(crate::DNS_1123_LABEL_MAX_LEN);
        let c = caixa_with_nome(&bare_max);
        // The bare-`:nome` gate accepts the 63-byte length.
        c.validate_nome().unwrap();
        // The new joint-length gate rejects it.
        let err = c.validate_nome_chart_name_budget().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::NomeChartNameBudgetExceeded { ref nome, .. }
                    if nome.len() == crate::DNS_1123_LABEL_MAX_LEN
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_nome_chart_name_budget_diagnostic_carries_offending_chart_name() {
        // Diagnostic-shape pin: the rendered `lareira-<nome>` chart
        // name appears verbatim in the diagnostic so the author sees
        // exactly the string the apiserver / `helm lint` would have
        // rejected — no re-derivation required to grep the source.
        // Peer with `nome_invalid_diagnostic_carries_offending_nome`
        // on the bare-`:nome` axis.
        let over = "x".repeat(crate::LAREIRA_CHART_NAME_NOME_MAX_LEN + 5);
        let c = caixa_with_nome(&over);
        let err = c.validate_nome_chart_name_budget().unwrap_err();
        let ManifestError::NomeChartNameBudgetExceeded { nome, reason } = err else {
            panic!("expected NomeChartNameBudgetExceeded variant");
        };
        assert_eq!(nome, over);
        let expected_chart = crate::lareira_chart_name(&over);
        assert!(
            reason.contains(&expected_chart),
            "diagnostic must carry the rendered chart name {expected_chart:?} verbatim, \
             got {reason:?}"
        );
        assert!(
            reason.contains("lareira-"),
            "diagnostic must name the canonical chart-name prefix verbatim, got {reason:?}"
        );
    }

    #[test]
    fn validate_nome_chart_name_budget_runs_after_nome_shape_via_layout_verify() {
        // Order pin on the layout cascade: the narrower
        // `NomeInvalid` (bare-DNS-1123 shape) fires before the
        // joint-length budget. A structurally-malformed `:nome` (here:
        // uppercase) surfaces its specific shape error rather than
        // the chart-name-budget error, even when the joint length
        // would also overflow — the narrower diagnostic is more
        // self-locating. Mirrors the cascade-precedence pins peer
        // gates already use (e.g. `EntradaParaEmpty` before
        // `EntradaParaInvalid`).
        let over = "A".repeat(crate::LAREIRA_CHART_NAME_NOME_MAX_LEN + 1);
        let c = caixa_with_nome(&over);
        // The bare-shape gate fires first.
        let err = c.validate_nome().unwrap_err();
        assert!(
            matches!(err, ManifestError::NomeInvalid { .. }),
            "bare-shape gate must fire before chart-name-budget gate; got {err:?}"
        );
        // And the layout verify cascade surfaces that diagnostic, not
        // the budget arm. Inject a path-exists oracle so the cascade
        // gets past the manifest-presence check and into the
        // value-shape gates.
        let layout = crate::StandardLayout::new().with_path_exists(|_| true);
        let err = crate::LayoutInvariants::verify(
            &layout,
            &c,
            std::path::Path::new("/tmp/caixa-test-fake-root"),
        )
        .unwrap_err();
        let issue = err.to_string();
        assert!(
            issue.contains("DNS-1123") || issue.contains("uppercase"),
            "layout cascade must surface the bare-DNS-1123 diagnostic on a \
             structurally-malformed :nome, not the chart-name-budget diagnostic; got {issue:?}"
        );
    }

    #[test]
    fn layout_verify_routes_chart_name_budget_through_nome_violation() {
        // Cross-axis envelope pin: the layout cascade wraps both
        // bare-`:nome` and joint-length-`:nome` failures through the
        // same [`LayoutError::NomeViolation`] envelope, since both
        // arms are on the `:nome` axis. The user's diagnostic stays
        // self-locating ("which axis"), and a future consumer that
        // dispatches on the layout-error variant (e.g. a `feira lint`
        // exit-code mapping) sees a single per-axis envelope. The
        // wrapped `issue:` carries the full inner diagnostic.
        let over = "a".repeat(crate::LAREIRA_CHART_NAME_NOME_MAX_LEN + 1);
        let c = caixa_with_nome(&over);
        // The bare-shape gate accepts.
        c.validate_nome().unwrap();
        let layout = crate::StandardLayout::new().with_path_exists(|_| true);
        let err = crate::LayoutInvariants::verify(
            &layout,
            &c,
            std::path::Path::new("/tmp/caixa-test-fake-root"),
        )
        .unwrap_err();
        let crate::LayoutError::NomeViolation { caixa, issue } = err else {
            panic!("expected LayoutError::NomeViolation, got {err:?}");
        };
        assert_eq!(caixa, over);
        assert!(
            issue.contains("lareira-") && issue.contains("63") && issue.contains("55"),
            "wrapped issue must carry the joint-length diagnostic verbatim, got {issue:?}"
        );
    }

    // ── Caixa::validate_versao — top-level :versao value-shape gate ─────

    fn caixa_with_versao(versao: &str) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.versao = versao.to_string();
        c
    }

    #[test]
    fn validate_versao_accepts_canonical_template() {
        // Positive control: the bare `feira init`-style template's
        // `:versao` ("0.1.0") is a canonical SemVer-2 literal; the gate
        // must not regress this baseline shape. A future tightening of
        // the accepted set surfaces here as a test failure first.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_versao().unwrap();
    }

    #[test]
    fn validate_versao_accepts_canonical_forms() {
        // Positive-set sweep: each realistic SemVer-2 shape the
        // substrate's downstream consumers accept must pass — bare
        // MAJOR.MINOR.PATCH, pre-release tags (`-rc.1`, `-alpha.0`),
        // build metadata (`+build.42`), the combined form, and the
        // `0.0.0` boundary case. Mirrors `accepts_canonical_forms` on
        // the peer `:nome` axis (6c992f8).
        for versao in [
            "0.1.0",
            "0.0.0",
            "1.0.0",
            "0.2.0-rc.1",
            "1.0.0-alpha.0",
            "1.0.0+build.42",
            "1.0.0-rc.1+build.42",
            "10.20.30",
        ] {
            caixa_with_versao(versao)
                .validate_versao()
                .unwrap_or_else(|e| {
                    panic!("canonical :versao {versao:?} must validate, got {e:?}")
                });
        }
    }

    #[test]
    fn validate_versao_rejects_empty() {
        // Fail-before-pass-after pin: `Caixa::from_lisp` does not refuse
        // an empty `:versao` (the derive macro stores the raw String);
        // the gate's empty arm names the offending axis with a narrower
        // diagnostic than the `VersaoInvalid` parse arm would emit.
        // Mirrors `validate_nome_rejects_empty` (6c992f8).
        let c = caixa_with_versao("");
        let err = c.validate_versao().unwrap_err();
        assert_eq!(err, ManifestError::VersaoEmpty);
    }

    #[test]
    fn validate_versao_rejects_git_tag_shape() {
        // The canonical "I copied the git tag verbatim" footgun —
        // `feira publish` *emits* `v<versao>` git tags, so a leaked
        // `v0.1.0` in `:versao` would render as `vv0.1.0` and silently
        // shift every downstream consumer's version axis. `semver`
        // rejects the leading `v` at parse time; the gate moves the
        // diagnostic to the source `caixa.lisp`.
        let c = caixa_with_versao("v0.1.0");
        let err = c.validate_versao().unwrap_err();
        let ManifestError::VersaoInvalid { versao, reason } = err else {
            panic!("expected VersaoInvalid for git-tag-shape :versao");
        };
        assert_eq!(versao, "v0.1.0");
        assert!(
            !reason.is_empty(),
            "VersaoInvalid `reason` must carry the parser's wording, got {reason:?}"
        );
    }

    #[test]
    fn validate_versao_rejects_missing_patch() {
        // The canonical "I shortened it" footgun — SemVer-2 requires
        // three parts. Cargo's `version =` field accepts the shortened
        // form as a requirement, conflating the two leaks across the
        // typed `:deps :versao` vs top-level `:versao` axes; the gate
        // pins the top-level axis to the strict three-part shape.
        let c = caixa_with_versao("0.1");
        let err = c.validate_versao().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::VersaoInvalid { ref versao, .. } if versao == "0.1"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_versao_rejects_requirement_shape() {
        // The canonical "I leaked a requirement into a version" footgun —
        // the typed `:deps :versao` / `:membros :versao` axes accept
        // `^0.1` (a `VersionReq`); the top-level `:versao` requires a
        // concrete `Version`. Without this gate the two typed surfaces
        // would silently overlap, and a top-level `^0.1` would surface
        // at `helm install` time as a Chart.yaml version rejection far
        // from the source `caixa.lisp`.
        let c = caixa_with_versao("^0.1");
        let err = c.validate_versao().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::VersaoInvalid { ref versao, .. } if versao == "^0.1"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_versao_rejects_docker_tag_shape() {
        // The "I confused it with a docker tag" footgun — `latest`,
        // `main`, `stable` parse as identifiers, not SemVer-2 versions.
        // SemVer rejects at parse time; the gate moves the diagnostic
        // to the source `caixa.lisp`.
        for bad in ["latest", "main", "stable"] {
            let c = caixa_with_versao(bad);
            let err = c.validate_versao().unwrap_err();
            assert!(
                matches!(
                    err,
                    ManifestError::VersaoInvalid { ref versao, .. } if versao == bad
                ),
                "got {err:?} for {bad:?}"
            );
        }
    }

    #[test]
    fn validate_versao_rejects_four_part_form() {
        // The Java/Microsoft "MAJOR.MINOR.PATCH.BUILD" convention
        // SemVer-2 forbids. A leak from a non-SemVer ecosystem; the
        // semver crate rejects the extra `.0` at parse time.
        let c = caixa_with_versao("0.1.0.0");
        let err = c.validate_versao().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::VersaoInvalid { ref versao, .. } if versao == "0.1.0.0"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn versao_empty_takes_precedence_over_invalid() {
        // Order pin: the empty arm fires before the parser is consulted.
        // Empty < invalid in self-locating-ness — the narrower
        // `VersaoEmpty` diagnostic doesn't carry a useless `versao: ""`
        // reference into the parser-shaped reason. Mirrors
        // `nome_empty_takes_precedence_over_invalid` (6c992f8) on the
        // peer axis.
        let c = caixa_with_versao("");
        assert_eq!(c.validate_versao().unwrap_err(), ManifestError::VersaoEmpty);
    }

    #[test]
    fn versao_invalid_diagnostic_carries_offending_versao() {
        // Diagnostic-shape pin: the error names the offending `:versao`
        // verbatim with a non-empty parser-shaped reason, so a `feira
        // lint` run can render the diagnostic without re-parsing.
        // Mirrors `nome_invalid_diagnostic_carries_offending_nome`.
        let c = caixa_with_versao("v0.1.0");
        let err = c.validate_versao().unwrap_err();
        let ManifestError::VersaoInvalid { versao, reason } = err else {
            panic!("expected VersaoInvalid variant");
        };
        assert_eq!(versao, "v0.1.0");
        assert!(
            !reason.is_empty(),
            "VersaoInvalid `reason` must carry the parser's wording verbatim"
        );
    }

    #[test]
    fn validate_versao_accepts_what_upgrade_from_from_accepts() {
        // Parity pin: every shape `UpgradeFromEntry::validate` accepts
        // for `:upgrade-from :from` must also pass `validate_versao` —
        // the two `:versao`-typed surfaces (top-level `:versao`,
        // `:upgrade-from :from`) consume the *same* `semver::Version`
        // parser, so they must agree on the accepted set. Without this
        // pin, a future tightening of one axis could silently diverge
        // from the other. Mirrors the `:versao` requirement-axis
        // parity (`:deps`/`:deps-dev`/`:membros`/`:children`) the prior
        // commits established.
        for versao in ["0.1.0", "0.2.0-rc.1", "1.0.0+build.42"] {
            // From the canonical UpgradeFromEntry round-trip fixture
            // (`upgrade::tests::round_trip_load_module` peers).
            let entry = crate::UpgradeFromEntry {
                from: versao.to_string(),
                instructions: Vec::new(),
            };
            entry
                .validate()
                .unwrap_or_else(|e| panic!(":from {versao:?} must validate, got {e:?}"));
            caixa_with_versao(versao)
                .validate_versao()
                .unwrap_or_else(|e| {
                    panic!(":versao {versao:?} must validate, got {e:?} — peer axis diverges")
                });
        }
    }

    // ── Caixa::validate_restart_window — supervisor restart-window
    //    folds through the shared `supervisor::duration_codec` ────────

    fn caixa_with_restart_window(window: Option<&str>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("root")).unwrap();
        c.kind = CaixaKind::Supervisor;
        c.restart_window = window.map(str::to_string);
        c
    }

    #[test]
    fn validate_restart_window_accepts_none() {
        // The canonical "omit the slot to express no reset" shape — a
        // `None` raw string is the absence of the typed
        // `:restart-window` slot, which is exactly the SupervisorSpec
        // "never reset" semantics. The gate must be a no-op here; a
        // future tightening that rejected `None` would force every
        // supervisor caixa to authoring-time pin a window even when
        // the OTP semantics call for none.
        caixa_with_restart_window(None)
            .validate_restart_window()
            .unwrap();
    }

    #[test]
    fn validate_restart_window_accepts_canonical_forms() {
        // Positive-set sweep across the canonical authoring units the
        // shared `supervisor::duration_codec::parse` accepts —
        // matches the codec-side `parse_accepts_integer_canonical_units`
        // pin in supervisor::tests so a future codec-side tightening
        // surfaces simultaneously on both axes.
        for window in ["60s", "5m", "1h", "500ms", "30", "0s"] {
            caixa_with_restart_window(Some(window))
                .validate_restart_window()
                .unwrap_or_else(|e| {
                    panic!("canonical :restart-window {window:?} must validate, got {e:?}")
                });
        }
    }

    #[test]
    fn validate_restart_window_rejects_fractional_seconds() {
        // Fail-before-pass-after pin: the `"1.5s"` drift class (parses
        // as f64 to 1.5 → renders back as `"1500ms"` on first
        // serialize). Prior to the fold + this gate, the inline
        // `parse_window_inline` accepted f64 magnitudes and silently
        // produced a `Duration::from_secs_f64(1.5)`, divergent from
        // the shared codec's integer-magnitude discipline on the
        // serde-routed siblings. The gate now surfaces a self-locating
        // diagnostic at the manifest layer.
        let err = caixa_with_restart_window(Some("1.5s"))
            .validate_restart_window()
            .unwrap_err();
        let ManifestError::RestartWindowMalformed {
            restart_window,
            reason,
        } = err
        else {
            panic!("expected RestartWindowMalformed for fractional seconds");
        };
        assert_eq!(restart_window, "1.5s");
        assert!(
            reason.contains("\"1.5\"") && reason.contains("not a non-negative integer"),
            "diagnostic must carry shared-codec wording, got {reason:?}"
        );
    }

    #[test]
    fn validate_restart_window_rejects_decimal_shaped_integer() {
        // The `"1.0s"` class — numerically `1s` exactly, but the
        // canonical form is `"1s"` not `"1.0s"`. Decimal-shape leak
        // gets the same canonical-form diagnostic.
        let err = caixa_with_restart_window(Some("1.0s"))
            .validate_restart_window()
            .unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::RestartWindowMalformed { ref restart_window, .. }
                    if restart_window == "1.0s"
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_restart_window_rejects_half_unit_minute() {
        // `"0.5m"` is the unit-fraction footgun — author writes a
        // human-readable half-minute, the prior inline parser silently
        // produced `Duration::from_secs_f64(30.0)` and serde
        // re-emitted as `"30s"`, rewriting author intent. The gate
        // closes the loop at the manifest layer.
        let err = caixa_with_restart_window(Some("0.5m"))
            .validate_restart_window()
            .unwrap_err();
        let ManifestError::RestartWindowMalformed {
            restart_window,
            reason,
        } = err
        else {
            panic!("expected RestartWindowMalformed");
        };
        assert_eq!(restart_window, "0.5m");
        assert!(
            reason.contains("\"30s\""),
            "diagnostic must point at the canonical-form remediation, got {reason:?}"
        );
    }

    #[test]
    fn validate_restart_window_rejects_leading_sign() {
        // `"+30s"` and `"-30s"` both round-tripped through f64 cleanly
        // on the prior parser (`+30` parses as `30.0`; `-30` parsed
        // and was caught by the `num < 0.0` arm which silently
        // returned `None`, dropping the author-supplied window). The
        // shared codec's digit-only gate rejects both with a unified
        // canonical-form diagnostic; the manifest-layer wrapper names
        // the offending value.
        for bad in ["+30s", "-30s"] {
            let err = caixa_with_restart_window(Some(bad))
                .validate_restart_window()
                .unwrap_err();
            assert!(
                matches!(
                    err,
                    ManifestError::RestartWindowMalformed { ref restart_window, .. }
                        if restart_window == bad
                ),
                "got {err:?} for {bad:?}"
            );
        }
    }

    #[test]
    fn validate_restart_window_rejects_unknown_unit() {
        // `"30x"` — the typo / wrong-unit footgun. The shared codec's
        // unit dispatch surfaces an `unknown duration unit` reason;
        // the manifest-layer wrapper names the offending value.
        let err = caixa_with_restart_window(Some("30x"))
            .validate_restart_window()
            .unwrap_err();
        let ManifestError::RestartWindowMalformed {
            restart_window,
            reason,
        } = err
        else {
            panic!("expected RestartWindowMalformed for unknown unit");
        };
        assert_eq!(restart_window, "30x");
        assert!(
            reason.contains("unknown duration unit"),
            "diagnostic must carry shared-codec unit-rejection wording, got {reason:?}"
        );
    }

    #[test]
    fn validate_restart_window_rejects_garbage() {
        // Pure non-numeric magnitude (`"abc"`) falls through to the
        // shared codec's narrower `"bad duration magnitude"` arm. Same
        // diagnostic shape as the codec-side
        // `parse_garbage_still_falls_through_to_bad_magnitude` pin.
        let err = caixa_with_restart_window(Some("abc"))
            .validate_restart_window()
            .unwrap_err();
        let ManifestError::RestartWindowMalformed {
            restart_window,
            reason,
        } = err
        else {
            panic!("expected RestartWindowMalformed for garbage");
        };
        assert_eq!(restart_window, "abc");
        assert!(
            reason.contains("bad duration magnitude"),
            "diagnostic must carry shared-codec garbage-rejection wording, got {reason:?}"
        );
    }

    #[test]
    fn validate_restart_window_rejects_empty_string() {
        // The empty-after-trim edge case — distinct from the `None`
        // canonical "omit the slot" shape. The shared codec's
        // digit-only gate refuses an empty magnitude; the manifest
        // layer names the offending `""` so the author can grep for
        // the literal empty value in their `caixa.lisp` and either
        // remove the slot (the canonical "no reset" shape) or pin a
        // positive duration.
        let err = caixa_with_restart_window(Some(""))
            .validate_restart_window()
            .unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::RestartWindowMalformed { ref restart_window, .. }
                    if restart_window.is_empty()
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn validate_restart_window_diagnostic_carries_offending_value() {
        // Diagnostic-shape pin (peer with
        // `nome_invalid_diagnostic_carries_offending_nome` /
        // `versao_invalid_diagnostic_carries_offending_versao`): the
        // error names the offending raw `:restart-window` verbatim
        // with a non-empty shared-codec-shaped reason, so a `feira
        // lint` run can render the diagnostic without re-parsing.
        let err = caixa_with_restart_window(Some("1.5s"))
            .validate_restart_window()
            .unwrap_err();
        let ManifestError::RestartWindowMalformed {
            restart_window,
            reason,
        } = err
        else {
            panic!("expected RestartWindowMalformed variant");
        };
        assert_eq!(restart_window, "1.5s");
        assert!(
            !reason.is_empty(),
            "RestartWindowMalformed `reason` must carry the codec's wording verbatim"
        );
    }

    #[test]
    fn supervisor_view_folds_through_shared_codec_on_canonical_form() {
        // Behavioral parity pin after the fold (`parse_window_inline`
        // deletion): the canonical `"60s"` still produces
        // `Duration::from_secs(60)` on the typed view — the fold is
        // semantically equivalent to the prior inline parser on the
        // accepted set. Mirrors the pre-fold `supervisor_view_returns_typed_shape`
        // pin, narrowed to the parser-side contract.
        let c = caixa_with_restart_window(Some("60s"));
        let view = c.supervisor_view().expect("Supervisor kind has a view");
        assert_eq!(
            view.restart_window,
            Some(std::time::Duration::from_secs(60))
        );
    }

    #[test]
    fn supervisor_view_soft_swallows_what_validate_rejects() {
        // Parity pin between the view-construction path and the
        // manifest-level validator: the same `"1.5s"` that surfaces
        // `RestartWindowMalformed` at `validate_restart_window` time
        // becomes `restart_window: None` on the typed view (the fold
        // preserves the existing best-effort shape of `supervisor_view`).
        // The contract is: a layout-verifier / `feira lint` flow that
        // cares about the malformed-window axis MUST consult
        // `validate_restart_window` — relying solely on the view's
        // `None` swallows the diagnostic silently. This pin makes the
        // expectation a typed invariant.
        let c = caixa_with_restart_window(Some("1.5s"));
        let view = c.supervisor_view().expect("Supervisor kind has a view");
        assert_eq!(
            view.restart_window, None,
            "view-construction path soft-swallows the parse error to None"
        );
        // And the manifest-level validator does NOT soft-swallow:
        assert!(
            matches!(
                c.validate_restart_window().unwrap_err(),
                ManifestError::RestartWindowMalformed { ref restart_window, .. }
                    if restart_window == "1.5s"
            ),
            "validator must surface the offending value",
        );
    }

    // ── validate_code_paths — per-entry shape on :bibliotecas / :exe / :servicos ──

    fn caixa_with_code_paths(bibliotecas: Vec<&str>, exe: Vec<&str>, servicos: Vec<&str>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.bibliotecas = bibliotecas.into_iter().map(String::from).collect();
        c.exe = exe.into_iter().map(String::from).collect();
        c.servicos = servicos.into_iter().map(String::from).collect();
        c
    }

    #[test]
    fn validate_code_paths_accepts_canonical_template() {
        // The bare `Caixa::template` shape is the gate's identity element
        // on the canonical authoring shape — `:bibliotecas
        // ("lib/demo.lisp")` + empty `:exe` + empty `:servicos`. Pins
        // that the gate is non-disruptive against every existing caixa.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_code_paths().unwrap();
    }

    #[test]
    fn validate_code_paths_accepts_explicit_relative_paths_on_every_slot() {
        // Positive control sweep: a canonical-shaped path on every slot
        // passes. Mirrors the peer
        // `behavior::validate_every_slot_relative_is_ok` pin.
        let c = caixa_with_code_paths(
            vec!["lib/demo.lisp", "lib/helpers.lisp"],
            vec!["exe/demo", "exe/tool"],
            vec!["servicos/demo.computeunit.yaml"],
        );
        c.validate_code_paths().unwrap();
    }

    #[test]
    fn validate_code_paths_accepts_all_empty_lists() {
        // The empty-list identity element: every Caixa with no declared
        // code paths trivially passes (Supervisor / Aplicacao kinds rely
        // on this — the OwnCode gate already rejected them before the
        // path-shape gate runs in the layout, but the validator itself
        // must accept the empty shape).
        let c = caixa_with_code_paths(vec![], vec![], vec![]);
        c.validate_code_paths().unwrap();
    }

    #[test]
    fn validate_code_paths_rejects_empty_bibliotecas_entry() {
        let c = caixa_with_code_paths(vec![""], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::CodePathEmpty {
                    slot: ":bibliotecas"
                }
            ),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_code_paths_rejects_empty_exe_entry() {
        let c = caixa_with_code_paths(vec![], vec![""], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        assert!(
            matches!(err, ManifestError::CodePathEmpty { slot: ":exe" }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_code_paths_rejects_empty_servicos_entry() {
        let c = caixa_with_code_paths(vec![], vec![], vec![""]);
        let err = c.validate_code_paths().unwrap_err();
        assert!(
            matches!(err, ManifestError::CodePathEmpty { slot: ":servicos" }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_code_paths_rejects_absolute_bibliotecas_entry() {
        // `:bibliotecas` has no `starts_with(<dir>)` fence downstream,
        // so an absolute path that resolves on disk silently passes the
        // layout's existence check — the canonical sandbox-escape on
        // the biblioteca axis.
        let c = caixa_with_code_paths(vec!["/etc/passwd"], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathAbsolute { slot, path } = err else {
            panic!("expected CodePathAbsolute, got {err:?}");
        };
        assert_eq!(slot, ":bibliotecas");
        assert_eq!(path, PathBuf::from("/etc/passwd"));
    }

    #[test]
    fn validate_code_paths_rejects_absolute_exe_entry() {
        let c = caixa_with_code_paths(vec![], vec!["/usr/bin/env"], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathAbsolute { slot, path } = err else {
            panic!("expected CodePathAbsolute, got {err:?}");
        };
        assert_eq!(slot, ":exe");
        assert_eq!(path, PathBuf::from("/usr/bin/env"));
    }

    #[test]
    fn validate_code_paths_rejects_absolute_servicos_entry() {
        let c = caixa_with_code_paths(vec![], vec![], vec!["/var/servicos/x.yaml"]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathAbsolute { slot, path } = err else {
            panic!("expected CodePathAbsolute, got {err:?}");
        };
        assert_eq!(slot, ":servicos");
        assert_eq!(path, PathBuf::from("/var/servicos/x.yaml"));
    }

    #[test]
    fn validate_code_paths_rejects_parent_escape_bibliotecas_leading() {
        // Canonical "I want a lib from a sibling caixa" footgun on the
        // biblioteca axis. `:bibliotecas` has no `starts_with` fence
        // downstream, so a leading `..` traverses to the parent of the
        // caixa root with no diagnostic at layout time if the resolved
        // target exists.
        let c = caixa_with_code_paths(vec!["../sibling/x.lisp"], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathParentEscape { slot, path } = err else {
            panic!("expected CodePathParentEscape, got {err:?}");
        };
        assert_eq!(slot, ":bibliotecas");
        assert_eq!(path, PathBuf::from("../sibling/x.lisp"));
    }

    #[test]
    fn validate_code_paths_rejects_parent_escape_exe_mid_path() {
        // Mid-path `..` defeats the layout's component-aware
        // `starts_with(exe_dir)` fence — `root.join("exe/../../escape")`
        // `starts_with(<root>/exe)` is true, but the canonical resolution
        // lives outside the caixa root. Caught regardless of where the
        // `..` sits — mirrors the peer
        // `behavior::validate_rejects_parent_escape_mid_path` pin.
        let c = caixa_with_code_paths(vec![], vec!["exe/../../escape"], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathParentEscape { slot, path } = err else {
            panic!("expected CodePathParentEscape, got {err:?}");
        };
        assert_eq!(slot, ":exe");
        assert_eq!(path, PathBuf::from("exe/../../escape"));
    }

    #[test]
    fn validate_code_paths_rejects_parent_escape_servicos_trailing() {
        let c = caixa_with_code_paths(vec![], vec![], vec!["servicos/foo/../../escape.yaml"]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathParentEscape { slot, path } = err else {
            panic!("expected CodePathParentEscape, got {err:?}");
        };
        assert_eq!(slot, ":servicos");
        assert_eq!(path, PathBuf::from("servicos/foo/../../escape.yaml"));
    }

    #[test]
    fn validate_code_paths_cross_slot_precedence_bibliotecas_before_exe_before_servicos() {
        // Cross-slot precedence pin: `:bibliotecas` → `:exe` →
        // `:servicos`. A manifest with malformed entries on all three
        // surfaces surfaces the `:bibliotecas` defect first, mirroring
        // the canonical declaration order
        // `Caixa::declared_foreign_code_slots` already establishes for
        // the foreign-code-slot diagnostic.
        let c = caixa_with_code_paths(vec![""], vec![""], vec![""]);
        let err = c.validate_code_paths().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::CodePathEmpty {
                    slot: ":bibliotecas"
                }
            ),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_code_paths_within_slot_precedence_empty_before_absolute_before_parent_escape() {
        // Within-slot precedence pin: empty → absolute → parent-escape,
        // matching the [`PathShapeViolation`] arm-ordering every peer
        // `is_sandboxed_relative_path` caller follows (b0c8389
        // BehaviorSpec, 26da2c7 UpgradeInstruction::StateChange). A
        // `:bibliotecas` list whose first entry is empty *and* whose
        // later entries are absolute/parent-escape surfaces the empty
        // arm first, on the lexicographically-earliest offending entry.
        let c = caixa_with_code_paths(vec!["", "/etc/passwd", "../escape.lisp"], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::CodePathEmpty {
                    slot: ":bibliotecas"
                }
            ),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_code_paths_first_offender_per_slot_wins() {
        // Within a single slot, the first declaration-order offender
        // surfaces — pins that the gate is left-to-right deterministic
        // (peer of every `*_first_collision_*` pin on duplicate gates).
        let c = caixa_with_code_paths(
            vec!["lib/ok.lisp", "/etc/escape", "../also-escape"],
            vec![],
            vec![],
        );
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathAbsolute { slot, path } = err else {
            panic!("expected CodePathAbsolute, got {err:?}");
        };
        assert_eq!(slot, ":bibliotecas");
        assert_eq!(path, PathBuf::from("/etc/escape"));
    }

    #[test]
    fn validate_code_paths_diagnostic_carries_offending_slot_and_path() {
        // Diagnostic-shape pin (peer with
        // `nome_invalid_diagnostic_carries_offending_nome` /
        // `versao_invalid_diagnostic_carries_offending_versao`): the
        // error's Display surfaces both the offending `:slot` tag and
        // the offending path verbatim, so a `feira lint` run can render
        // the diagnostic without re-parsing.
        let c = caixa_with_code_paths(vec!["/etc/passwd"], vec![], vec![]);
        let rendered = c.validate_code_paths().unwrap_err().to_string();
        assert!(
            rendered.contains(":bibliotecas"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("/etc/passwd"),
            "diagnostic must quote the offending path: {rendered}",
        );
    }

    #[test]
    fn validate_code_paths_rejects_duplicate_bibliotecas_entry() {
        // Canonical copy-paste-the-wrong-file footgun on the biblioteca
        // axis. Without the gate `feira build` re-parses the same lib
        // twice, wasting work and silently masking the author's intent
        // to declare a *second* biblioteca.
        let c = caixa_with_code_paths(vec!["lib/demo.lisp", "lib/demo.lisp"], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathDuplicate { slot, path } = err else {
            panic!("expected CodePathDuplicate, got {err:?}");
        };
        assert_eq!(slot, ":bibliotecas");
        assert_eq!(path, PathBuf::from("lib/demo.lisp"));
    }

    #[test]
    fn validate_code_paths_rejects_duplicate_exe_entry() {
        // Same footgun on the Binario surface. The future `caixa-flake`
        // emitter that materializes each `:exe` entry as a flake
        // `packages.<name>` derivation would collide on the duplicate
        // package key — surfaced here at the typed-validate layer with a
        // self-locating diagnostic instead.
        let c = caixa_with_code_paths(vec![], vec!["exe/cli", "exe/cli"], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathDuplicate { slot, path } = err else {
            panic!("expected CodePathDuplicate, got {err:?}");
        };
        assert_eq!(slot, ":exe");
        assert_eq!(path, PathBuf::from("exe/cli"));
    }

    #[test]
    fn validate_code_paths_rejects_duplicate_servicos_entry() {
        // Same footgun on the Servico surface. The peer caixa-helm /
        // caixa-flux renderers refuse `:servicos.len() != 1` with the
        // narrower `UnsupportedServicoCount` diagnostic, but that
        // diagnostic surfaces "too many servicos" without naming
        // "duplicate entry" — the typed self-locating framing only lands
        // at this gate.
        let c = caixa_with_code_paths(
            vec![],
            vec![],
            vec![
                "servicos/demo.computeunit.yaml",
                "servicos/demo.computeunit.yaml",
            ],
        );
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathDuplicate { slot, path } = err else {
            panic!("expected CodePathDuplicate, got {err:?}");
        };
        assert_eq!(slot, ":servicos");
        assert_eq!(path, PathBuf::from("servicos/demo.computeunit.yaml"));
    }

    #[test]
    fn validate_code_paths_accepts_same_path_across_slots() {
        // Per-list scope pin: a `:bibliotecas` entry that happens to
        // collide with an `:exe` or `:servicos` entry as a *string* is
        // not a duplicate by this gate (each list gets its own HashSet),
        // mirroring the peer `:deps` ↔ `:deps-dev` per-list scope
        // (a `:nome` present in both lists is a legitimate dev-vs-runtime
        // shape on the dep axis). The structural `starts_with(<exe |
        // servicos>_dir)` fence at layout time prevents the realistic
        // cross-slot collision case from existing on disk, but the gate's
        // per-list scope is correct independent of that downstream fence.
        let c = caixa_with_code_paths(
            vec!["lib/x.lisp"],
            vec!["exe/x"],
            vec!["servicos/x.computeunit.yaml"],
        );
        c.validate_code_paths().unwrap();
    }

    #[test]
    fn validate_code_paths_duplicate_fires_after_structural_checks_on_same_slot() {
        // Within-slot ordering pin: structural defects (empty / absolute
        // / parent-escape) fire before the duplicate gate on the same
        // slot. A `:bibliotecas ("" "lib/x.lisp" "lib/x.lisp")` shape
        // surfaces the narrower `CodePathEmpty` for the empty entry
        // first, not the duplicate on the later pair — same arm-ordering
        // every peer per-list duplicate gate uses (`:etiquetas` 360a499,
        // `:autores` 86c769b, `:deps` 359fba5).
        let c = caixa_with_code_paths(vec!["", "lib/x.lisp", "lib/x.lisp"], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        assert!(
            matches!(
                err,
                ManifestError::CodePathEmpty {
                    slot: ":bibliotecas"
                }
            ),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_code_paths_duplicate_in_bibliotecas_fires_before_duplicate_in_exe() {
        // Cross-slot ordering pin on the duplicate arm: `:bibliotecas`
        // duplicates surface before `:exe` duplicates, matching the
        // canonical `:bibliotecas` → `:exe` → `:servicos` declaration
        // order every peer per-slot diagnostic on this surface follows.
        let c = caixa_with_code_paths(
            vec!["lib/x.lisp", "lib/x.lisp"],
            vec!["exe/y", "exe/y"],
            vec![],
        );
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathDuplicate { slot, path } = err else {
            panic!("expected CodePathDuplicate, got {err:?}");
        };
        assert_eq!(slot, ":bibliotecas");
        assert_eq!(path, PathBuf::from("lib/x.lisp"));
    }

    #[test]
    fn validate_code_paths_duplicate_diagnostic_carries_offending_slot_and_path() {
        // Diagnostic-shape pin (peer with
        // `validate_code_paths_diagnostic_carries_offending_slot_and_path`
        // on the structural arm): the duplicate-arm Display surfaces both
        // the offending `:slot` tag and the offending path verbatim, so a
        // `feira lint` run can render the diagnostic without re-parsing.
        let c = caixa_with_code_paths(
            vec![],
            vec![],
            vec![
                "servicos/demo.computeunit.yaml",
                "servicos/demo.computeunit.yaml",
            ],
        );
        let rendered = c.validate_code_paths().unwrap_err().to_string();
        assert!(
            rendered.contains(":servicos"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("servicos/demo.computeunit.yaml"),
            "diagnostic must quote the offending path: {rendered}",
        );
    }

    // ── validate_code_paths — `.lisp` extension gate on :bibliotecas ──
    //
    // The lifted [`crate::render::is_lisp_extension`] predicate (33cc830)
    // now gates `:bibliotecas` entries on the tatara-lisp-source file-type
    // contract. The `feira build` loop (`caixa-feira/src/cmd/build.rs:33`)
    // reads every declared `:bibliotecas` entry through `tatara_lisp::read`
    // at parse time — the same downstream consumer the peer `:behavior
    // :on-*` (c97815a, [`crate::BehaviorError::NonLispExtension`]) and
    // `:upgrade-from :state-change :script` (33cc830,
    // [`crate::UpgradeError::NonLispExtensionScript`]) axes route through.
    // `:exe` and `:servicos` are deliberately excluded — `:exe` is the
    // nix-built executable surface (`"exe/<name>"` shape per the canonical
    // [`crate::LayoutError::ExeOutsideDir`] error message and every
    // in-tree `caixa_with_code_paths` positive control), and `:servicos`
    // is the `.computeunit.yaml` ComputeUnit-CR axis.

    #[test]
    fn validate_code_paths_rejects_no_extension_bibliotecas_entry() {
        // Canonical "I dragged the wrong file from the workspace tree"
        // footgun on the biblioteca axis. Without the gate `feira build`
        // hands the extensionless path to `tatara_lisp::read` and fails
        // with a parser-shaped diagnostic far from the source caixa.lisp,
        // with no field naming the offending `:bibliotecas` entry.
        for relpath in ["lib/demo", "demo", "lib/handlers/inner"] {
            let c = caixa_with_code_paths(vec![relpath], vec![], vec![]);
            let err = c.validate_code_paths().unwrap_err();
            let ManifestError::CodePathNonLispExtension { slot, path } = err else {
                panic!("expected CodePathNonLispExtension for {relpath:?}, got {err:?}");
            };
            assert_eq!(slot, ":bibliotecas");
            assert_eq!(path, PathBuf::from(relpath));
        }
    }

    #[test]
    fn validate_code_paths_rejects_wrong_extension_bibliotecas_entry() {
        // Wrong-extension sweep across common authoring footguns. Same
        // sweep posture as the peer
        // `behavior::validate_rejects_wrong_extension` (c97815a) and
        // `upgrade::tests::state_change_rejects_wrong_extension_script`
        // (33cc830) cases.
        for relpath in [
            "lib/demo.rs",
            "lib/demo.txt",
            "lib/demo.md",
            "lib/demo.json",
            "lib/demo.yaml",
            "lib/demo.toml",
            "lib/demo.lisp.bak",
            "lib/demo.lispx",
            "lib/demo.lis",
        ] {
            let c = caixa_with_code_paths(vec![relpath], vec![], vec![]);
            let err = c.validate_code_paths().unwrap_err();
            let ManifestError::CodePathNonLispExtension { slot, path } = err else {
                panic!("expected CodePathNonLispExtension for {relpath:?}, got {err:?}");
            };
            assert_eq!(slot, ":bibliotecas");
            assert_eq!(path, PathBuf::from(relpath));
        }
    }

    #[test]
    fn validate_code_paths_rejects_case_folded_extension_bibliotecas_entry() {
        // Case-sensitivity sweep — pins the strict lowercase `.lisp`
        // contract. An uppercase `.LISP` shape that the layout's existence
        // check would (case-insensitively, on case-insensitive volumes)
        // match the on-disk file still mismatches the canonical form the
        // codec emits, breaking the THEORY.md §V.2.7 render-determinism
        // contract. Mirrors the peer
        // `behavior::validate_rejects_case_folded_extension` (c97815a) and
        // `upgrade::tests::state_change_rejects_case_folded_extension_script`
        // (33cc830) sweeps.
        for relpath in [
            "lib/demo.LISP",
            "lib/demo.Lisp",
            "lib/demo.LiSp",
            "lib/demo.lISP",
        ] {
            let c = caixa_with_code_paths(vec![relpath], vec![], vec![]);
            let err = c.validate_code_paths().unwrap_err();
            let ManifestError::CodePathNonLispExtension { slot, path } = err else {
                panic!("expected CodePathNonLispExtension for {relpath:?}, got {err:?}");
            };
            assert_eq!(slot, ":bibliotecas");
            assert_eq!(path, PathBuf::from(relpath));
        }
    }

    #[test]
    fn validate_code_paths_accepts_canonical_lisp_shapes() {
        // Positive-control sweep through every canonical authoring shape
        // every in-tree fixture and the `Caixa::template` scaffold use.
        // Mirrors the peer `behavior::validate_accepts_canonical_lisp_paths`
        // (c97815a) and the lifted predicate's own
        // `is_lisp_extension_accepts_canonical_shapes` sweep in render.rs
        // (33cc830).
        for relpath in [
            "lib/demo.lisp",
            "lib/handlers.lisp",
            "lib/migrations/v01-to-v02.lisp",
            "demo.lisp",
            "a.lisp",
            "./lib/demo.lisp",
            "lib/./handlers.lisp",
            "lib/migrations/v.0.1.lisp",
        ] {
            let c = caixa_with_code_paths(vec![relpath], vec![], vec![]);
            c.validate_code_paths()
                .unwrap_or_else(|e| panic!("canonical shape {relpath:?} must pass, got {e:?}"));
        }
    }

    #[test]
    fn validate_code_paths_non_lisp_extension_does_not_fire_on_exe_or_servicos() {
        // The file-type gate is per-slot — only `:bibliotecas` carries the
        // tatara-lisp-source contract. An extensionless `:exe` entry
        // (`exe/demo`) and a `.computeunit.yaml` `:servicos` entry are the
        // canonical shapes every in-tree fixture uses, and must continue
        // to pass validate. Pins that a future tightening that broadens
        // the `.lisp` gate to either axis surfaces as a test failure
        // rather than as a silent breaking change to existing valid
        // manifests.
        let c = caixa_with_code_paths(
            vec![],
            vec!["exe/demo", "exe/tool"],
            vec!["servicos/demo.computeunit.yaml"],
        );
        c.validate_code_paths().unwrap();
    }

    #[test]
    fn validate_code_paths_sandbox_shape_arms_precede_non_lisp_extension() {
        // Cross-arm precedence pin: a `:bibliotecas` entry that is *both*
        // sandbox-escaping and non-`.lisp` surfaces the more fundamental
        // sandbox-shape diagnostic first (the `.lisp` remediation would
        // be misleading when the offending path can never resolve under
        // the caixa root anyway). Mirrors the peer
        // `EmptyPath` → `AbsolutePath` → `ParentEscape` → `NonLispExtension`
        // ordering on `:behavior :on-*` (c97815a) and `EmptyScript` →
        // `AbsoluteScript` → `ParentEscapeScript` → `NonLispExtensionScript`
        // on `:upgrade-from :state-change :script` (33cc830).
        //
        // Empty wins (the strictly-smaller-scope structural arm).
        let c = caixa_with_code_paths(vec![""], vec![], vec![]);
        assert!(
            matches!(
                c.validate_code_paths().unwrap_err(),
                ManifestError::CodePathEmpty {
                    slot: ":bibliotecas"
                }
            ),
            "empty must win over non-lisp-extension",
        );
        // Absolute wins (the path can't resolve under the caixa root).
        let c = caixa_with_code_paths(vec!["/etc/passwd"], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathAbsolute { slot, .. } = err else {
            panic!("absolute must win over non-lisp-extension, got {err:?}");
        };
        assert_eq!(slot, ":bibliotecas");
        // ParentEscape wins (the path escapes the caixa root).
        let c = caixa_with_code_paths(vec!["../sibling/x.txt"], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathParentEscape { slot, .. } = err else {
            panic!("parent-escape must win over non-lisp-extension, got {err:?}");
        };
        assert_eq!(slot, ":bibliotecas");
    }

    #[test]
    fn validate_code_paths_non_lisp_extension_precedes_duplicate() {
        // Within-slot precedence pin: the per-entry file-type shape gate
        // fires before the cross-entry duplicate gate, so the narrower
        // structural defect dominates the uniqueness diagnostic. A
        // `("lib/x.txt" "lib/x.txt")` shape surfaces
        // `CodePathNonLispExtension` on the first entry rather than
        // `CodePathDuplicate` on the pair — same posture every per-entry
        // shape-gate-precedes-duplicate cascade follows on this surface
        // (the empty / absolute / parent-escape arms already precede the
        // duplicate arm; the lifted file-type arm joins that set).
        let c = caixa_with_code_paths(vec!["lib/x.txt", "lib/x.txt"], vec![], vec![]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathNonLispExtension { slot, path } = err else {
            panic!("expected CodePathNonLispExtension, got {err:?}");
        };
        assert_eq!(slot, ":bibliotecas");
        assert_eq!(path, PathBuf::from("lib/x.txt"));
    }

    #[test]
    fn validate_code_paths_non_lisp_extension_diagnostic_carries_offending_slot_and_path() {
        // Diagnostic-shape pin (peer with
        // `validate_code_paths_diagnostic_carries_offending_slot_and_path`
        // on the sandbox-shape arms and
        // `validate_code_paths_duplicate_diagnostic_carries_offending_slot_and_path`
        // on the duplicate arm): the file-type-arm Display surfaces both
        // the offending `:slot` tag, the offending path verbatim, and the
        // expected `.lisp` extension named in the remediation text, so a
        // `feira lint` run can render the diagnostic without re-parsing.
        let c = caixa_with_code_paths(vec!["lib/demo.rs"], vec![], vec![]);
        let rendered = c.validate_code_paths().unwrap_err().to_string();
        assert!(
            rendered.contains(":bibliotecas"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("lib/demo.rs"),
            "diagnostic must quote the offending path: {rendered}",
        );
        assert!(
            rendered.contains(".lisp"),
            "diagnostic must name the expected extension: {rendered}",
        );
    }

    // ── validate_code_paths — `.computeunit.yaml` compound-suffix gate on :servicos ──
    //
    // The lifted [`crate::render::is_computeunit_yaml_extension`] predicate
    // now gates `:servicos` entries on the ComputeUnit-CR YAML file-type
    // contract. The peer caixa-helm / caixa-flux renderers consume each
    // `:servicos` entry through `serde_yaml::from_str` as a typed
    // `ComputeUnit` CR — same downstream-consumer-shape lift as the peer
    // `:bibliotecas` `.lisp` gate (64772a9), here on the compound-suffix
    // axis `Path::extension` can't express on its own.

    #[test]
    fn validate_code_paths_rejects_no_extension_servicos_entry() {
        // Canonical "I dragged the wrong file from the workspace tree"
        // footgun on the Servico axis. Without the gate the peer
        // caixa-helm / caixa-flux renderers hand the extensionless path
        // to `serde_yaml::from_str` and fail with a parser-shaped
        // diagnostic far from the source caixa.lisp, with no field
        // naming the offending `:servicos` entry.
        for relpath in ["servicos/demo", "demo", "servicos/sub/nested"] {
            let c = caixa_with_code_paths(vec![], vec![], vec![relpath]);
            let err = c.validate_code_paths().unwrap_err();
            let ManifestError::CodePathNonComputeUnitYamlExtension { slot, path } = err else {
                panic!(
                    "expected CodePathNonComputeUnitYamlExtension for {relpath:?}, \
                     got {err:?}"
                );
            };
            assert_eq!(slot, ":servicos");
            assert_eq!(path, PathBuf::from(relpath));
        }
    }

    #[test]
    fn validate_code_paths_rejects_wrong_extension_servicos_entry() {
        // Wrong-extension sweep across common authoring footguns on the
        // Servico axis. Bare `.yaml` is the canonical "I forgot the
        // `.computeunit` segment" typo; the off-by-one-segment shapes
        // (`.computeunit-yaml` / `.computeunit_yaml`) silently pass the
        // bare `Path::extension` view but mismatch the typed compound
        // suffix the renderers' `serde_yaml::from_str` consumer demands.
        // Same sweep-posture as the peer
        // `validate_code_paths_rejects_wrong_extension_bibliotecas_entry`
        // (64772a9) on the sibling tatara-lisp-source axis.
        for relpath in [
            "servicos/demo.yaml",
            "servicos/demo.yml",
            "servicos/demo.json",
            "servicos/demo.toml",
            "servicos/demo.txt",
            "servicos/demo.computeunit.yaml.bak",
            "servicos/demo.computeunit.yam",
            "servicos/demo.computeunit",
            "servicos/demo-computeunit.yaml",
            "servicos/demo_computeunit.yaml",
        ] {
            let c = caixa_with_code_paths(vec![], vec![], vec![relpath]);
            let err = c.validate_code_paths().unwrap_err();
            let ManifestError::CodePathNonComputeUnitYamlExtension { slot, path } = err else {
                panic!(
                    "expected CodePathNonComputeUnitYamlExtension for {relpath:?}, \
                     got {err:?}"
                );
            };
            assert_eq!(slot, ":servicos");
            assert_eq!(path, PathBuf::from(relpath));
        }
    }

    #[test]
    fn validate_code_paths_rejects_case_folded_extension_servicos_entry() {
        // Case-sensitivity sweep — pins the strict lowercase
        // `.computeunit.yaml` contract. A case-folded shape that the
        // layout's existence check would (case-insensitively, on
        // case-insensitive volumes) match the on-disk file still
        // mismatches the canonical form the codec emits, breaking the
        // THEORY.md §V.2.7 render-determinism contract. Mirrors the peer
        // `validate_code_paths_rejects_case_folded_extension_bibliotecas_entry`
        // (64772a9) sweep on the sibling tatara-lisp-source axis.
        for relpath in [
            "servicos/demo.ComputeUnit.yaml",
            "servicos/demo.COMPUTEUNIT.yaml",
            "servicos/demo.computeunit.YAML",
            "servicos/demo.computeunit.Yaml",
            "servicos/demo.COMPUTEUNIT.YAML",
        ] {
            let c = caixa_with_code_paths(vec![], vec![], vec![relpath]);
            let err = c.validate_code_paths().unwrap_err();
            let ManifestError::CodePathNonComputeUnitYamlExtension { slot, path } = err else {
                panic!(
                    "expected CodePathNonComputeUnitYamlExtension for {relpath:?}, \
                     got {err:?}"
                );
            };
            assert_eq!(slot, ":servicos");
            assert_eq!(path, PathBuf::from(relpath));
        }
    }

    #[test]
    fn validate_code_paths_rejects_empty_stem_servicos_entry() {
        // Degenerate hidden-file shape: a file name exactly equal to the
        // suffix (`.computeunit.yaml` — no stem preceding the suffix) is
        // the structural "Servico declared with no identity" footgun.
        // The substrate identifies each ComputeUnit by the file-stem
        // segment that precedes `.computeunit.yaml` (the rendered
        // `lareira-<stem>` Helm chart, the per-Servico `metadata.name`,
        // the M3 `:contratos` membership lookup), so an empty stem
        // leaves the Servico unidentifiable. Pinned at the typed-axis
        // level so a future regression that drops the `name.len() >
        // SUFFIX.len()` bound at the predicate surfaces here, not
        // piecemeal as a `lareira-` chart-name collision at render time.
        for relpath in ["servicos/.computeunit.yaml"] {
            let c = caixa_with_code_paths(vec![], vec![], vec![relpath]);
            let err = c.validate_code_paths().unwrap_err();
            let ManifestError::CodePathNonComputeUnitYamlExtension { slot, path } = err else {
                panic!(
                    "expected CodePathNonComputeUnitYamlExtension for {relpath:?}, \
                     got {err:?}"
                );
            };
            assert_eq!(slot, ":servicos");
            assert_eq!(path, PathBuf::from(relpath));
        }
    }

    #[test]
    fn validate_code_paths_accepts_canonical_computeunit_yaml_shapes() {
        // Positive-control sweep through every canonical authoring shape
        // every in-tree fixture and the `Caixa::template` scaffold use.
        // Mirrors the peer
        // `validate_code_paths_accepts_canonical_lisp_shapes` (64772a9)
        // and the lifted predicate's own
        // `computeunit_yaml_extension_accepts_canonical_shapes` sweep in
        // render.rs.
        for relpath in [
            "servicos/demo.computeunit.yaml",
            "servicos/hello-rio.computeunit.yaml",
            "servicos/my-service.computeunit.yaml",
            "servicos/a.computeunit.yaml",
            "./servicos/demo.computeunit.yaml",
            "servicos/./demo.computeunit.yaml",
            "servicos/sub/nested.computeunit.yaml",
            "servicos/v0.1.computeunit.yaml",
        ] {
            let c = caixa_with_code_paths(vec![], vec![], vec![relpath]);
            c.validate_code_paths()
                .unwrap_or_else(|e| panic!("canonical shape {relpath:?} must pass, got {e:?}"));
        }
    }

    #[test]
    fn validate_code_paths_non_computeunit_yaml_extension_does_not_fire_on_bibliotecas_or_exe() {
        // The file-type gate is per-slot — only `:servicos` carries the
        // ComputeUnit-CR YAML contract. A canonical `.lisp` `:bibliotecas`
        // entry and an extensionless `:exe` entry are the canonical
        // shapes every in-tree fixture uses, and must continue to pass
        // validate. Peer of
        // `validate_code_paths_non_lisp_extension_does_not_fire_on_exe_or_servicos`
        // (64772a9) — together pin that the typed
        // [`CodePathFileType`] dispatch is exhaustively per-slot, with no
        // cross-axis leakage in either direction.
        let c = caixa_with_code_paths(
            vec!["lib/demo.lisp"],
            vec!["exe/demo", "exe/tool"],
            vec!["servicos/demo.computeunit.yaml"],
        );
        c.validate_code_paths().unwrap();
    }

    #[test]
    fn validate_code_paths_sandbox_shape_arms_precede_non_computeunit_yaml_extension() {
        // Cross-arm precedence pin: a `:servicos` entry that is *both*
        // sandbox-escaping and wrong-extension surfaces the more
        // fundamental sandbox-shape diagnostic first (the
        // `.computeunit.yaml` remediation would be misleading when the
        // offending path can never resolve under the caixa root
        // anyway). Mirrors the peer
        // `validate_code_paths_sandbox_shape_arms_precede_non_lisp_extension`
        // (64772a9) ordering on the sibling `:bibliotecas` axis and the
        // peer `EmptyPath` → `AbsolutePath` → `ParentEscape` →
        // `NonComputeUnitYamlExtension` arm-ordering the dispatch
        // table establishes.
        //
        // Empty wins (the strictly-smaller-scope structural arm).
        let c = caixa_with_code_paths(vec![], vec![], vec![""]);
        assert!(
            matches!(
                c.validate_code_paths().unwrap_err(),
                ManifestError::CodePathEmpty { slot: ":servicos" }
            ),
            "empty must win over non-computeunit-yaml-extension",
        );
        // Absolute wins (the path can't resolve under the caixa root).
        let c = caixa_with_code_paths(vec![], vec![], vec!["/etc/foo.yaml"]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathAbsolute { slot, .. } = err else {
            panic!("absolute must win over non-computeunit-yaml-extension, got {err:?}");
        };
        assert_eq!(slot, ":servicos");
        // ParentEscape wins (the path escapes the caixa root).
        let c = caixa_with_code_paths(vec![], vec![], vec!["../sibling/x.yaml"]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathParentEscape { slot, .. } = err else {
            panic!("parent-escape must win over non-computeunit-yaml-extension, got {err:?}");
        };
        assert_eq!(slot, ":servicos");
    }

    #[test]
    fn validate_code_paths_non_computeunit_yaml_extension_precedes_duplicate() {
        // Within-slot precedence pin: the per-entry file-type shape gate
        // fires before the cross-entry duplicate gate, so the narrower
        // structural defect dominates the uniqueness diagnostic. A
        // `("servicos/x.yaml" "servicos/x.yaml")` shape surfaces
        // `CodePathNonComputeUnitYamlExtension` on the first entry
        // rather than `CodePathDuplicate` on the pair — same posture
        // every per-entry shape-gate-precedes-duplicate cascade follows
        // on this surface, peer of the 64772a9 `:bibliotecas`
        // `("lib/x.txt" "lib/x.txt")` ordering.
        let c = caixa_with_code_paths(vec![], vec![], vec!["servicos/x.yaml", "servicos/x.yaml"]);
        let err = c.validate_code_paths().unwrap_err();
        let ManifestError::CodePathNonComputeUnitYamlExtension { slot, path } = err else {
            panic!("expected CodePathNonComputeUnitYamlExtension, got {err:?}");
        };
        assert_eq!(slot, ":servicos");
        assert_eq!(path, PathBuf::from("servicos/x.yaml"));
    }

    #[test]
    fn validate_code_paths_non_computeunit_yaml_extension_diagnostic_carries_offending_slot_and_path()
     {
        // Diagnostic-shape pin (peer with
        // `validate_code_paths_non_lisp_extension_diagnostic_carries_offending_slot_and_path`
        // on the sibling tatara-lisp-source axis): the file-type-arm
        // Display surfaces both the offending `:slot` tag, the
        // offending path verbatim, and the expected
        // `.computeunit.yaml` compound suffix named in the remediation
        // text, so a `feira lint` run can render the diagnostic without
        // re-parsing.
        let c = caixa_with_code_paths(vec![], vec![], vec!["servicos/demo.yaml"]);
        let rendered = c.validate_code_paths().unwrap_err().to_string();
        assert!(
            rendered.contains(":servicos"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("servicos/demo.yaml"),
            "diagnostic must quote the offending path: {rendered}",
        );
        assert!(
            rendered.contains(".computeunit.yaml"),
            "diagnostic must name the expected compound suffix: {rendered}",
        );
    }

    // ── validate_etiquetas — universal-axis registry-search-tag shape ──

    fn caixa_with_etiquetas(etiquetas: Vec<&str>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.etiquetas = etiquetas.into_iter().map(String::from).collect();
        c
    }

    #[test]
    fn validate_etiquetas_accepts_empty_list() {
        // The empty-list identity: every caixa with no declared tags
        // trivially passes — `Caixa::template` emits `:etiquetas ()`,
        // so the gate is non-disruptive against every existing manifest.
        let c = caixa_with_etiquetas(vec![]);
        c.validate_etiquetas().unwrap();
    }

    #[test]
    fn validate_etiquetas_accepts_canonical_forms() {
        // Positive control sweep: a canonical-shaped non-empty distinct
        // tag list passes, mirroring the example checkout-aplicacao
        // (`:etiquetas ("example" "aplicacao" "mesh" "ecommerce" "demo")`)
        // and the hello-rio fixture (`("hello-world" "wasm" "rust")`).
        let c = caixa_with_etiquetas(vec!["example", "aplicacao", "mesh", "ecommerce", "demo"]);
        c.validate_etiquetas().unwrap();
    }

    #[test]
    fn validate_etiquetas_rejects_empty_entry() {
        // Canonical paste-from-blank-doc footgun. Without the gate the
        // empty entry rendered as `keywords: [""]` in `Chart.yaml`, a
        // no-op tag indexing nothing in the future caixa-registry.
        let c = caixa_with_etiquetas(vec![""]);
        let err = c.validate_etiquetas().unwrap_err();
        assert!(matches!(err, ManifestError::EtiquetaEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_etiquetas_rejects_duplicate_entry() {
        // Canonical copy-paste-the-wrong-tag footgun. Without the gate
        // the duplicate was silently dedup'd by caixa-helm's BTreeSet
        // collect at chart render — a "second wins / one silently
        // disappears" shape divergent from every peer typed-graph set
        // gate. The duplicate-arm names the offending tag verbatim.
        let c = caixa_with_etiquetas(vec!["demo", "demo"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaDuplicate { etiqueta } = err else {
            panic!("expected EtiquetaDuplicate, got {err:?}");
        };
        assert_eq!(etiqueta, "demo");
    }

    #[test]
    fn validate_etiquetas_empty_takes_precedence_over_duplicate() {
        // Empty-first cascade pin: `("" "demo" "demo")` surfaces
        // `EtiquetaEmpty` not `EtiquetaDuplicate` — the narrower
        // structural "this entry has no value" defect dominates the
        // cross-entry uniqueness diagnostic. Mirrors the peer
        // empty-before-duplicate cascades on `:caracteristicas`
        // (`CaracteristicaEmpty` before `CaracteristicaDuplicate`,
        // fc3b4d5) and `:membros :caixa` (`MembroCaixaEmpty` before
        // `MembroDuplicate`).
        let c = caixa_with_etiquetas(vec!["", "demo", "demo"]);
        let err = c.validate_etiquetas().unwrap_err();
        assert!(matches!(err, ManifestError::EtiquetaEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_etiquetas_duplicate_reports_first_collision() {
        // First-collision pin: `("a" "b" "a" "b")` surfaces the `"a"`
        // duplicate (the lexicographically-earliest offending position
        // — the second `"a"` at index 2 collides with the first `"a"`
        // at index 0), not the later `"b"` collision at index 3,
        // peer with every other first-collision diagnostic posture on
        // this surface (`validate_load_singularity_reports_first_collision`,
        // `validate_cleanup_singularity_reports_first_collision`).
        let c = caixa_with_etiquetas(vec!["a", "b", "a", "b"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaDuplicate { etiqueta } = err else {
            panic!("expected EtiquetaDuplicate, got {err:?}");
        };
        assert_eq!(etiqueta, "a");
    }

    #[test]
    fn validate_etiquetas_case_sensitive() {
        // Case-sensitivity pin: `("Foo" "foo")` is two distinct entries,
        // mirroring the peer `:membros :caixa` / `:children :caixa`
        // exact-string-match discipline. The shape gate this routine
        // landed (`is_chart_keyword_shape`, Cargo crates.io keyword
        // grammar) accepts mixed case — crates.io's keyword rule is
        // "case-insensitive" at the index layer but admits mixed case
        // at the entry layer (the canonical Helm chart `keywords:`
        // shape is lowercase by convention, but the grammar admits
        // uppercase). Case-sensitivity at the duplicate-set layer
        // remains structural — two distinct strings are two distinct
        // entries.
        let c = caixa_with_etiquetas(vec!["Foo", "foo"]);
        c.validate_etiquetas().unwrap();
    }

    #[test]
    fn validate_etiquetas_diagnostic_carries_offending_tag() {
        // Diagnostic-shape pin (peer with
        // `validate_code_paths_diagnostic_carries_offending_slot_and_path`):
        // the error's Display surfaces the offending tag verbatim, so a
        // `feira lint` run can render the diagnostic without re-parsing
        // and the author can grep their caixa.lisp for the offending
        // value.
        let c = caixa_with_etiquetas(vec!["demo", "demo"]);
        let rendered = c.validate_etiquetas().unwrap_err().to_string();
        assert!(
            rendered.contains(":etiquetas"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("demo"),
            "diagnostic must quote the offending tag: {rendered}",
        );
    }

    #[test]
    fn validate_etiquetas_rejects_leading_whitespace_entry() {
        // Canonical paste-from-aligned-doc footgun. Without the shape
        // gate `" mesh"` silently passed validate and landed as a
        // YAML plain-style scalar with leading whitespace in the
        // rendered Chart.yaml `keywords:` array — every YAML 1.2
        // dumper trims leading whitespace from plain-style scalars,
        // so the authored space round-tripped inconsistently back
        // through `caixa.lisp`. Mirrors the peer
        // `validate_autores_rejects_leading_whitespace_entry`.
        let c = caixa_with_etiquetas(vec![" mesh"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { etiqueta, reason } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert_eq!(etiqueta, " mesh");
        assert!(reason.contains("whitespace"), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_rejects_embedded_newline_entry() {
        // Canonical paste-from-multiline-doc footgun — the author
        // pasted a multi-tag block into one `:etiquetas` entry
        // instead of splitting into one entry per tag. Without the
        // shape gate `"mesh\nhttp"` silently passed validate and
        // landed as a YAML-illegal multi-line scalar in the rendered
        // Chart.yaml `keywords:` array.
        let c = caixa_with_etiquetas(vec!["mesh\nhttp"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { etiqueta, reason } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert_eq!(etiqueta, "mesh\nhttp");
        assert!(reason.contains("newline"), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_rejects_embedded_comma_entry() {
        // Canonical CSV-list-separator-confusion footgun: the author
        // confused the CSV-style separator convention with the
        // `:etiquetas` list grammar. Without the shape gate
        // `"mesh,http,grpc"` silently passed validate and landed as a
        // single malformed search tag in the rendered Chart.yaml
        // `keywords:` array — Artifact Hub's keyword index would
        // either silently drop the tag or index it as
        // `mesh,http,grpc` instead of three separate tags.
        let c = caixa_with_etiquetas(vec!["mesh,http,grpc"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { etiqueta, reason } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert_eq!(etiqueta, "mesh,http,grpc");
        assert!(reason.contains('`'), "got: {reason}");
        assert!(reason.contains(','), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_rejects_embedded_slash_entry() {
        // Canonical path-separator-confusion footgun: the author
        // confused namespace-path notation with the keyword grammar.
        let c = caixa_with_etiquetas(vec!["caixa/servico"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { etiqueta, reason } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert_eq!(etiqueta, "caixa/servico");
        assert!(reason.contains('/'), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_rejects_leading_digit_entry() {
        // Canonical paste-from-numbered-list footgun: the author
        // copied `1. mesh` from a numbered doc and the `1` leaked
        // into the tag.
        let c = caixa_with_etiquetas(vec!["1mesh"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { etiqueta, reason } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert_eq!(etiqueta, "1mesh");
        assert!(reason.contains("digit"), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_rejects_leading_hyphen_entry() {
        // Canonical kebab-leak footgun.
        let c = caixa_with_etiquetas(vec!["-foo"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { etiqueta, reason } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert_eq!(etiqueta, "-foo");
        assert!(reason.contains('-'), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_rejects_non_ascii_entry() {
        // Canonical paste-from-Unicode-doc footgun. Every legitimate
        // search tag is strict ASCII; raw non-ASCII silently
        // round-trips inconsistently across NFC/NFD normalization on
        // APFS / case-folding filesystems and breaks the Artifact Hub
        // keyword search index lookup.
        let c = caixa_with_etiquetas(vec!["café"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { etiqueta, reason } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert_eq!(etiqueta, "café");
        assert!(reason.contains("non-ASCII"), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_rejects_period_entry() {
        // Canonical namespace-confusion / version-suffix footgun
        // (`"http.1"` / `"v1.0"`): Cargo's crates.io keyword grammar
        // excludes `.` from the continuation set even though the
        // sibling `:caracteristicas` axis (Cargo's feature-name
        // grammar) admits it. Tighter than the sibling axis, peer
        // with Cargo's own crates.io keyword shape.
        let c = caixa_with_etiquetas(vec!["http.1"]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { etiqueta, reason } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert_eq!(etiqueta, "http.1");
        assert!(reason.contains('.'), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_empty_takes_precedence_over_shape() {
        // Per-entry empty-first cascade pin: an entry that is both
        // empty *and* shape-invalid surfaces `EtiquetaEmpty` (the
        // narrower "this entry has no value" structural defect
        // dominates the broader shape-predicate diagnostic). The
        // empty arm fires before the shape predicate is consulted,
        // mirroring the peer `validate_autores_empty_takes_precedence_over_shape`
        // cascade established on the sibling universal-axis Vec<String>
        // surface.
        let c = caixa_with_etiquetas(vec![""]);
        let err = c.validate_etiquetas().unwrap_err();
        assert!(matches!(err, ManifestError::EtiquetaEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_etiquetas_shape_takes_precedence_over_duplicate() {
        // Per-entry shape-before-cross-entry-duplicate cascade pin: an
        // entry that is malformed surfaces `EtiquetaInvalid` even when
        // a later entry would have collided on duplicate. The
        // per-entry shape arm fires inside the same loop iteration as
        // the empty arm, before the seen-set insert at end-of-iteration
        // — structural per-entry defects dominate the cross-entry
        // uniqueness diagnostic. Mirrors the peer
        // `validate_autores_shape_takes_precedence_over_duplicate`.
        let c = caixa_with_etiquetas(vec!["mesh\nhttp", "mesh\nhttp"]);
        let err = c.validate_etiquetas().unwrap_err();
        assert!(
            matches!(err, ManifestError::EtiquetaInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_etiquetas_invalid_diagnostic_names_offending_slot_and_value() {
        // Diagnostic-shape pin on the new shape arm (peer with
        // `validate_autores_invalid_diagnostic_names_offending_slot_and_value`):
        // the rendered Display surfaces both the offending slot name
        // and the offending value verbatim, so a `feira lint` run
        // points the author at the exact `:etiquetas` entry to fix.
        let c = caixa_with_etiquetas(vec!["mesh\nhttp"]);
        let rendered = c.validate_etiquetas().unwrap_err().to_string();
        assert!(
            rendered.contains(":etiquetas"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("mesh\\nhttp"),
            "diagnostic must quote the offending value (debug-escaped): {rendered}",
        );
    }

    #[test]
    fn validate_etiquetas_rejects_at_21_byte_boundary() {
        // The 20-byte cap pin — boundary-exceeding case rejected,
        // boundary-accepting case passes. Mirrors the peer
        // `chart_keyword_shape_rejects_at_21_byte_boundary` substrate-
        // side pin, surfaced at the per-axis caller so the cap
        // propagates through validate end-to-end. Constructed as a
        // single all-`a` token so only the cap arm fires.
        let max_ok = "a".repeat(20);
        let c = caixa_with_etiquetas(vec![max_ok.as_str()]);
        c.validate_etiquetas().unwrap();
        let too_long = "a".repeat(21);
        let c = caixa_with_etiquetas(vec![too_long.as_str()]);
        let err = c.validate_etiquetas().unwrap_err();
        let ManifestError::EtiquetaInvalid { reason, .. } = err else {
            panic!("expected EtiquetaInvalid, got {err:?}");
        };
        assert!(reason.contains("20"), "got: {reason}");
        assert!(reason.contains("21"), "got: {reason}");
    }

    #[test]
    fn validate_etiquetas_accepts_canonical_shaped_forms() {
        // Positive control sweep: every canonical-shaped tag from the
        // hello-rio / checkout-aplicacao / pangea-tatara-akeyless
        // example fixtures plus the substrate-fixed tags caixa-helm
        // unions in at chart render. Drift between this list and the
        // substrate-side `chart_keyword_shape_accepts_canonical_forms`
        // sweep surfaces here — one source of truth for the rule.
        let c = caixa_with_etiquetas(vec![
            "example",
            "aplicacao",
            "mesh",
            "ecommerce",
            "demo",
            "infrastructure",
            "aws",
            "akeyless",
            "pangea-native",
            "hello-world",
            "wasm",
            "rust",
            "tatara-lisp",
            "caixa-servico",
            "lareira",
        ]);
        c.validate_etiquetas().unwrap();
    }

    // ── validate_autores — universal-axis maintainer shape ────────────

    fn caixa_with_autores(autores: Vec<&str>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.autores = autores.into_iter().map(String::from).collect();
        c
    }

    #[test]
    fn validate_autores_accepts_empty_list() {
        // The empty-list identity: `Caixa::template` emits `:autores ()`,
        // so the gate is non-disruptive against every existing manifest.
        let c = caixa_with_autores(vec![]);
        c.validate_autores().unwrap();
    }

    #[test]
    fn validate_autores_accepts_canonical_forms() {
        // Positive control sweep: every canonical-shaped non-empty
        // distinct maintainer list passes — the hello-rio / checkout-
        // aplicacao fixtures' `:autores ("pleme-io")` shape, plus the
        // multi-author shape downstream packaging surfaces emit.
        let c = caixa_with_autores(vec!["pleme-io"]);
        c.validate_autores().unwrap();
        let c = caixa_with_autores(vec!["alice <alice@example.com>", "bob <bob@example.com>"]);
        c.validate_autores().unwrap();
    }

    #[test]
    fn validate_autores_rejects_empty_entry() {
        // Canonical paste-from-blank-doc footgun. Without the gate the
        // empty entry rendered as `maintainers: [{name: "", email: null}]`
        // in `Chart.yaml`, a no-op maintainer the substrate cannot route
        // to.
        let c = caixa_with_autores(vec![""]);
        let err = c.validate_autores().unwrap_err();
        assert!(matches!(err, ManifestError::AutorEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_autores_rejects_duplicate_entry() {
        // Canonical copy-paste-the-wrong-author footgun. Unlike the
        // `:etiquetas` peer (caixa-helm's `BTreeSet` collect silently
        // dedups the rendered `keywords:` array), the `maintainers:`
        // rendering has *no* dedup — duplicates stack verbatim. The
        // duplicate-arm names the offending author verbatim.
        let c = caixa_with_autores(vec!["pleme-io", "pleme-io"]);
        let err = c.validate_autores().unwrap_err();
        let ManifestError::AutorDuplicate { autor } = err else {
            panic!("expected AutorDuplicate, got {err:?}");
        };
        assert_eq!(autor, "pleme-io");
    }

    #[test]
    fn validate_autores_empty_takes_precedence_over_duplicate() {
        // Empty-first cascade pin: `("" "pleme-io" "pleme-io")` surfaces
        // `AutorEmpty` not `AutorDuplicate` — the narrower structural
        // "this entry has no value" defect dominates the cross-entry
        // uniqueness diagnostic. Mirrors the peer empty-before-duplicate
        // cascades on `:etiquetas` (`EtiquetaEmpty` before
        // `EtiquetaDuplicate`, 360a499), `:caracteristicas`
        // (`CaracteristicaEmpty` before `CaracteristicaDuplicate`,
        // fc3b4d5), and `:membros :caixa` (`MembroCaixaEmpty` before
        // `MembroDuplicate`).
        let c = caixa_with_autores(vec!["", "pleme-io", "pleme-io"]);
        let err = c.validate_autores().unwrap_err();
        assert!(matches!(err, ManifestError::AutorEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_autores_duplicate_reports_first_collision() {
        // First-collision pin: `("a" "b" "a" "b")` surfaces the `"a"`
        // duplicate (the lexicographically-earliest offending position
        // — the second `"a"` at index 2 collides with the first `"a"`
        // at index 0), not the later `"b"` collision at index 3,
        // peer with every other first-collision diagnostic posture on
        // this surface.
        let c = caixa_with_autores(vec!["a", "b", "a", "b"]);
        let err = c.validate_autores().unwrap_err();
        let ManifestError::AutorDuplicate { autor } = err else {
            panic!("expected AutorDuplicate, got {err:?}");
        };
        assert_eq!(autor, "a");
    }

    #[test]
    fn validate_autores_case_sensitive() {
        // Case-sensitivity pin: `("Pleme-io" "pleme-io")` is two distinct
        // entries, mirroring the peer `:etiquetas` / `:membros :caixa`
        // / `:children :caixa` exact-string-match discipline.
        let c = caixa_with_autores(vec!["Pleme-io", "pleme-io"]);
        c.validate_autores().unwrap();
    }

    #[test]
    fn validate_autores_diagnostic_carries_offending_author() {
        // Diagnostic-shape pin (peer with
        // `validate_etiquetas_diagnostic_carries_offending_tag`): the
        // error's Display surfaces the offending author verbatim, so a
        // `feira lint` run can render the diagnostic without re-parsing
        // and the author can grep their caixa.lisp for the offending
        // value.
        let c = caixa_with_autores(vec!["pleme-io", "pleme-io"]);
        let rendered = c.validate_autores().unwrap_err().to_string();
        assert!(
            rendered.contains(":autores"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("pleme-io"),
            "diagnostic must quote the offending author: {rendered}",
        );
    }

    #[test]
    fn validate_autores_rejects_leading_whitespace_entry() {
        // Canonical paste-from-aligned-doc footgun. Without the shape
        // gate `" pleme-io"` silently passed validate and landed as a
        // YAML plain-style scalar with leading whitespace in the
        // rendered Chart.yaml `maintainers:` array — every YAML 1.2
        // dumper trims leading whitespace from plain-style scalars, so
        // the authored space round-tripped inconsistently back through
        // `caixa.lisp`. Mirrors the peer
        // `validate_descricao_rejects_leading_whitespace`.
        let c = caixa_with_autores(vec![" pleme-io"]);
        let err = c.validate_autores().unwrap_err();
        let ManifestError::AutorInvalid { autor, reason } = err else {
            panic!("expected AutorInvalid, got {err:?}");
        };
        assert_eq!(autor, " pleme-io");
        assert!(reason.contains("whitespace"), "got: {reason}");
    }

    #[test]
    fn validate_autores_rejects_trailing_whitespace_entry() {
        // Canonical paste-from-doc footgun.
        let c = caixa_with_autores(vec!["pleme-io "]);
        let err = c.validate_autores().unwrap_err();
        let ManifestError::AutorInvalid { autor, reason } = err else {
            panic!("expected AutorInvalid, got {err:?}");
        };
        assert_eq!(autor, "pleme-io ");
        assert!(reason.contains("whitespace"), "got: {reason}");
    }

    #[test]
    fn validate_autores_rejects_embedded_newline_entry() {
        // Canonical paste-from-multiline-doc footgun — the author
        // pasted a multi-line block of author records into one
        // `:autores` entry instead of splitting into one entry per
        // author. Without the shape gate `"alice\nbob"` silently
        // passed validate and landed as a YAML-illegal multi-line
        // scalar in the rendered Chart.yaml `maintainers:` array.
        let c = caixa_with_autores(vec!["alice\nbob"]);
        let err = c.validate_autores().unwrap_err();
        let ManifestError::AutorInvalid { autor, reason } = err else {
            panic!("expected AutorInvalid, got {err:?}");
        };
        assert_eq!(autor, "alice\nbob");
        assert!(reason.contains("newline"), "got: {reason}");
    }

    #[test]
    fn validate_autores_rejects_embedded_carriage_return_entry() {
        // Canonical paste-from-Windows-CRLF-doc footgun.
        let c = caixa_with_autores(vec!["alice\rbob"]);
        let err = c.validate_autores().unwrap_err();
        let ManifestError::AutorInvalid { autor, reason } = err else {
            panic!("expected AutorInvalid, got {err:?}");
        };
        assert_eq!(autor, "alice\rbob");
        assert!(reason.contains("carriage return"), "got: {reason}");
    }

    #[test]
    fn validate_autores_rejects_embedded_tab_entry() {
        // Canonical tab-from-aligned-doc footgun.
        let c = caixa_with_autores(vec!["Pleme\tContributors"]);
        let err = c.validate_autores().unwrap_err();
        let ManifestError::AutorInvalid { autor, reason } = err else {
            panic!("expected AutorInvalid, got {err:?}");
        };
        assert_eq!(autor, "Pleme\tContributors");
        assert!(reason.contains("tab"), "got: {reason}");
    }

    #[test]
    fn validate_autores_rejects_embedded_control_bytes_entry() {
        // Paste-from-binary-blob footguns: NUL, BEL, ESC, DEL all
        // surface the same control-byte arm.
        for entry in [
            "alice\x00bob",
            "alice\x07bob",
            "alice\x1bbob",
            "alice\x7fbob",
        ] {
            let c = caixa_with_autores(vec![entry]);
            let err = c.validate_autores().unwrap_err();
            let ManifestError::AutorInvalid { autor, reason } = err else {
                panic!("expected AutorInvalid for {entry:?}, got {err:?}");
            };
            assert_eq!(autor, entry);
            assert!(
                reason.contains("control character"),
                "{entry:?} reason: {reason}",
            );
        }
    }

    #[test]
    fn validate_autores_accepts_unicode_entry() {
        // Unicode positive control: realistic maintainer names carry
        // Unicode (`François`, `日本語`, `naïve`). The predicate must
        // round-trip Unicode losslessly, peer with the
        // `chart_maintainer_name_shape_accepts_unicode` substrate-side
        // sweep.
        let c = caixa_with_autores(vec![
            "François Dupont",
            "日本語の名前",
            "naïve <naive@example.com>",
        ]);
        c.validate_autores().unwrap();
    }

    #[test]
    fn validate_autores_empty_takes_precedence_over_shape() {
        // Per-entry empty-first cascade pin: an entry that is both
        // empty *and* shape-invalid surfaces `AutorEmpty` (the narrower
        // "this entry has no value" structural defect dominates the
        // broader shape-predicate diagnostic). The empty arm fires
        // before the shape predicate is consulted, mirroring the peer
        // `validate_repositorio_empty_takes_precedence_over_shape`
        // cascade on the universal `Option<String>` siblings — and now
        // established on the Vec<String> per-entry surface.
        let c = caixa_with_autores(vec![""]);
        let err = c.validate_autores().unwrap_err();
        assert!(matches!(err, ManifestError::AutorEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_autores_shape_takes_precedence_over_duplicate() {
        // Per-entry shape-before-cross-entry-duplicate cascade pin: an
        // entry that is malformed surfaces `AutorInvalid` even when a
        // later entry would have collided on duplicate. The per-entry
        // shape arm fires inside the same loop iteration as the empty
        // arm, before the seen-set insert at end-of-iteration —
        // structural per-entry defects dominate the cross-entry
        // uniqueness diagnostic.
        let c = caixa_with_autores(vec!["alice\nbob", "alice\nbob"]);
        let err = c.validate_autores().unwrap_err();
        assert!(
            matches!(err, ManifestError::AutorInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_autores_invalid_diagnostic_names_offending_slot_and_value() {
        // Diagnostic-shape pin on the new shape arm (peer with
        // `validate_descricao_invalid_diagnostic_carries_offending_value`):
        // the rendered Display surfaces both the offending slot name
        // and the offending value verbatim, so a `feira lint` run
        // points the author at the exact `:autores` entry to fix.
        let c = caixa_with_autores(vec!["alice\nbob"]);
        let rendered = c.validate_autores().unwrap_err().to_string();
        assert!(
            rendered.contains(":autores"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("alice\\nbob"),
            "diagnostic must quote the offending value (debug-escaped): {rendered}",
        );
    }

    #[test]
    fn validate_autores_rejects_at_129_byte_boundary() {
        // The 128-byte cap pin — boundary-exceeding case rejected,
        // boundary-accepting case passes. Mirrors the peer
        // `chart_maintainer_name_shape_rejects_at_129_byte_boundary`
        // substrate-side pin, surfaced at the per-axis caller so the
        // cap propagates through validate end-to-end. Constructed as
        // a single all-`a` token so only the cap arm fires.
        let max_ok = "a".repeat(128);
        let c = caixa_with_autores(vec![max_ok.as_str()]);
        c.validate_autores().unwrap();
        let too_long = "a".repeat(129);
        let c = caixa_with_autores(vec![too_long.as_str()]);
        let err = c.validate_autores().unwrap_err();
        let ManifestError::AutorInvalid { reason, .. } = err else {
            panic!("expected AutorInvalid, got {err:?}");
        };
        assert!(reason.contains("128"), "got: {reason}");
        assert!(reason.contains("129"), "got: {reason}");
    }

    // ── validate_repositorio — universal-axis git-repo-URL shape ──────

    fn caixa_with_repositorio(repositorio: Option<&str>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.repositorio = repositorio.map(String::from);
        c
    }

    #[test]
    fn validate_repositorio_accepts_none() {
        // The omit-the-slot identity: `:repositorio` is optional. The
        // gate is a no-op when the author didn't declare a value —
        // every caixa without a `:repositorio` line trivially passes,
        // and the substrate-side renderers fall back to their
        // documented placeholder (`caixa-helm`'s `home: None`,
        // `caixa-flux`'s `https://github.com/pleme-io/<nome>` derived
        // URL). Mirrors the peer `validate_restart_window_accepts_none`
        // posture on the other `Option<String>` Caixa slot.
        let c = caixa_with_repositorio(None);
        c.validate_repositorio().unwrap();
    }

    #[test]
    fn validate_repositorio_accepts_canonical_forms() {
        // Positive control sweep across every documented `:repositorio`
        // authoring shape — the same union the shared
        // `crate::render::is_git_repo_url` predicate accepts and the
        // peer `:deps :fonte :repo` axis already routes through.
        // Covers the `github:` shorthand (the canonical pleme-io
        // convention used in the `:repositorio` field of every
        // manifest fixture across `caixa-helm` / `caixa-mesh` and the
        // `examples/`), the `https://…` URL the README quickstart uses,
        // the `ssh://`, `git://`, `git@host:path` scp-style SSH, and
        // `file://` URL schemes the shared predicate documents.
        for repo in [
            "github:pleme-io/hello-rio",
            "github:pleme-io/checkout",
            "https://github.com/pleme-io/hello-rio",
            "ssh://git@github.com/pleme-io/hello-rio.git",
            "git://github.com/pleme-io/hello-rio.git",
            "git@github.com:pleme-io/hello-rio.git",
            "file:///srv/pleme/hello-rio",
        ] {
            let c = caixa_with_repositorio(Some(repo));
            c.validate_repositorio()
                .unwrap_or_else(|err| panic!("canonical {repo:?} must pass: {err:?}"));
        }
    }

    #[test]
    fn validate_repositorio_rejects_empty_some() {
        // Canonical paste-from-blank-doc footgun. The narrower
        // [`ManifestError::RepositorioEmpty`] arm fires before the
        // shape predicate is consulted, mirroring the empty-first
        // cascade every peer per-axis identity gate uses
        // (`NomeEmpty` → `NomeInvalid`, `VersaoEmpty` → `VersaoInvalid`,
        // `FonteRepoEmpty` → `FonteRepoInvalid`). Without this gate
        // the empty `Some("")` silently passed the renderer's
        // `Option::unwrap_or_else(|| <fallback>)` (which only fires
        // on `None`) and landed as `home: ""` in `Chart.yaml` /
        // `url: ""` in the FluxCD `GitRepository`.
        let c = caixa_with_repositorio(Some(""));
        let err = c.validate_repositorio().unwrap_err();
        assert!(
            matches!(err, ManifestError::RepositorioEmpty),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_repositorio_rejects_whitespace() {
        // Paste-from-doc whitespace footgun. The shared
        // `is_git_repo_url` predicate refuses any whitespace byte; a
        // trailing space in a `:repositorio` value silently broke
        // `git clone '<value> '` at clone time. The diagnostic names
        // the offending value verbatim.
        let c = caixa_with_repositorio(Some("github:pleme-io/hello-rio "));
        let err = c.validate_repositorio().unwrap_err();
        let ManifestError::RepositorioInvalid { repositorio, .. } = err else {
            panic!("expected RepositorioInvalid, got {err:?}");
        };
        assert_eq!(repositorio, "github:pleme-io/hello-rio ");
    }

    #[test]
    fn validate_repositorio_rejects_control_char() {
        // Paste-from-multiline-doc CRLF footgun — control characters
        // at the URL boundary are a class of subprocess-arg injection
        // and break git's URL parser at every porcelain entry point.
        let c = caixa_with_repositorio(Some("https://example.com/repo\n"));
        let err = c.validate_repositorio().unwrap_err();
        assert!(
            matches!(err, ManifestError::RepositorioInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_repositorio_rejects_leading_dash() {
        // Canonical CLI-argument-injection footgun: `git clone <repo>`
        // interprets a leading `-` as a CLI flag, so a
        // `-upload-pack=…` value escapes the subprocess argument
        // boundary. The shared predicate refuses every leading-`-`
        // shape at validate time.
        let c = caixa_with_repositorio(Some("-upload-pack=evil"));
        let err = c.validate_repositorio().unwrap_err();
        assert!(
            matches!(err, ManifestError::RepositorioInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_repositorio_rejects_missing_colon_separator() {
        // The bare `org/repo` ambiguity footgun — `git clone` reads
        // a no-`:` form as a relative filesystem path rather than the
        // GitHub-shorthand expansion the author probably intended.
        // The shared predicate refuses every shape without a `:`
        // separator.
        let c = caixa_with_repositorio(Some("pleme-io/hello-rio"));
        let err = c.validate_repositorio().unwrap_err();
        assert!(
            matches!(err, ManifestError::RepositorioInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_repositorio_rejects_fragment_anchor() {
        // Paste-from-browser-address-bar footgun on the
        // `:repositorio` axis — an author copies a GitHub permalink
        // to a README section / line-permalink and forgets to trim
        // the `#fragment` tail. The shared `is_git_repo_url`
        // predicate refuses the byte at the URL-grammar layer
        // (libcurl strips the fragment before opening the
        // transport, so the byte rides verbatim into the rendered
        // `Chart.yaml` `home:` and FluxCD `GitRepository` `url:`
        // fields but is silently dropped on the wire — two
        // manifest variants whose values differ only in their
        // fragment anchor lock to two distinct rendered artifacts
        // for the byte-identical clone, defeating the THEORY.md
        // §V.2 render-determinism contract on the `:repositorio`
        // axis the peer `:fonte :repo` axis already closes).
        let c = caixa_with_repositorio(Some("https://github.com/pleme-io/hello-rio#readme"));
        let err = c.validate_repositorio().unwrap_err();
        let ManifestError::RepositorioInvalid {
            repositorio,
            reason,
        } = err
        else {
            panic!("expected RepositorioInvalid, got {err:?}");
        };
        assert_eq!(repositorio, "https://github.com/pleme-io/hello-rio#readme");
        assert!(
            reason.contains("must not contain `#`"),
            "reason must surface the fragment-`#` arm, got {reason:?}"
        );
    }

    #[test]
    fn validate_repositorio_rejects_query_string() {
        // Paste-from-browser-address-bar footgun on the
        // `:repositorio` axis (peer with the a68f818 fragment-`#`
        // arm on the same axis). An author copies a GitHub tab
        // deep-link out of the address bar and forgets to trim
        // the `?tab=…` query tail. The shared `is_git_repo_url`
        // predicate refuses the byte at the URL-grammar layer
        // (GitHub / GitLab / Bitbucket silently ignore the
        // `?query` tail and serve the same repo regardless, so
        // the byte rides verbatim into the rendered `Chart.yaml`
        // `home:` and FluxCD `GitRepository` `url:` fields but
        // is silently masked at the wire — two manifest variants
        // whose values differ only in their query tail lock to
        // two distinct rendered artifacts for the byte-identical
        // clone, defeating the THEORY.md §V.2 render-determinism
        // contract on the `:repositorio` axis the peer `:fonte
        // :repo` axis already closes).
        let c = caixa_with_repositorio(Some(
            "https://github.com/pleme-io/hello-rio?tab=readme-ov-file",
        ));
        let err = c.validate_repositorio().unwrap_err();
        let ManifestError::RepositorioInvalid {
            repositorio,
            reason,
        } = err
        else {
            panic!("expected RepositorioInvalid, got {err:?}");
        };
        assert_eq!(
            repositorio,
            "https://github.com/pleme-io/hello-rio?tab=readme-ov-file"
        );
        assert!(
            reason.contains("must not contain `?`"),
            "reason must surface the query-`?` arm, got {reason:?}"
        );
    }

    #[test]
    fn validate_repositorio_rejects_embedded_backslash() {
        // Windows-file-path-confusion footgun on the `:repositorio`
        // axis (peer with the prior fragment-`#` / query-`?` arms on
        // the same axis, and peer with the new dep-level `:fonte :repo`
        // backslash arm on the URL-grammar trajectory). An author
        // pastes a Windows Explorer address-bar `file:///C:\Users\me\
        // hello-rio` into the `:repositorio` slot, expecting the
        // `lareira-<nome>` chart's `home:` field and the FluxCD
        // `GitRepository` `url:` field to render the canonical local
        // file-URI. The shared `is_git_repo_url` predicate refuses
        // the byte at the URL-grammar layer (libcurl silently
        // translates `\` → `/` on some platforms and refuses it on
        // others, so the byte rides verbatim into the rendered
        // artifacts but is silently rewritten or rejected at the wire
        // — two manifest variants whose values differ only in
        // backslash-vs-forward-slash lock to two distinct rendered
        // artifacts for the byte-identical clone, defeating the
        // THEORY.md §V.2 render-determinism contract on the
        // `:repositorio` axis the peer `:fonte :repo` axis already
        // closes).
        let c = caixa_with_repositorio(Some("file:///C:\\Users\\me\\hello-rio"));
        let err = c.validate_repositorio().unwrap_err();
        let ManifestError::RepositorioInvalid {
            repositorio,
            reason,
        } = err
        else {
            panic!("expected RepositorioInvalid, got {err:?}");
        };
        assert_eq!(repositorio, "file:///C:\\Users\\me\\hello-rio");
        assert!(
            reason.contains("must not contain `\\`"),
            "reason must surface the backslash-`\\` arm, got {reason:?}"
        );
    }

    #[test]
    fn validate_repositorio_rejects_uri_template_placeholder() {
        // URI Template (RFC 6570) placeholder footgun on the
        // `:repositorio` axis (peer with the prior fragment-`#` /
        // query-`?` / backslash-`\` arms on the same axis, and peer
        // with the new dep-level `:fonte :repo` `{` / `}` arm on the
        // URL-grammar trajectory). An author pastes a quick-start
        // README snippet / OpenAPI `servers:` URL / Helm chart
        // `home:` template carrying unresolved `{org}` / `{repo}`
        // placeholders into the `:repositorio` slot, expecting the
        // substrate to resolve the placeholder downstream. The
        // shared `is_git_repo_url` predicate refuses the byte at the
        // URL-grammar layer (libcurl percent-encodes `{` / `}` to
        // `%7B` / `%7D` on the wire, so the byte round-trips
        // inconsistently between the rendered `Chart.yaml home:` /
        // FluxCD `GitRepository url:` and the resolver's `git clone`
        // invocation, defeating the THEORY.md §V.2 render-
        // determinism contract on the `:repositorio` axis the peer
        // `:fonte :repo` axis already closes; every git porcelain
        // entry-point additionally fetches a nonexistent literal-
        // `{placeholder}`-named path far from the source caixa.lisp).
        let c = caixa_with_repositorio(Some("https://github.com/{org}/hello-rio"));
        let err = c.validate_repositorio().unwrap_err();
        let ManifestError::RepositorioInvalid {
            repositorio,
            reason,
        } = err
        else {
            panic!("expected RepositorioInvalid, got {err:?}");
        };
        assert_eq!(repositorio, "https://github.com/{org}/hello-rio");
        assert!(
            reason.contains("must not contain `{`"),
            "reason must surface the open-brace `{{` arm, got {reason:?}"
        );
        assert!(
            reason.contains("URI Template") || reason.contains("RFC 6570"),
            "reason must name the RFC 6570 URI Template grammar, got {reason:?}"
        );
    }

    #[test]
    fn validate_repositorio_empty_takes_precedence_over_shape() {
        // Empty-first cascade pin: the empty `Some("")` surfaces the
        // narrower `RepositorioEmpty` not the shape-predicate-wrapped
        // `RepositorioInvalid`, mirroring the peer
        // `NomeEmpty` → `NomeInvalid`, `VersaoEmpty` → `VersaoInvalid`,
        // `FonteRepoEmpty` → `FonteRepoInvalid` cascades. The shared
        // `is_git_repo_url` predicate also rejects the empty input
        // (defensively, with its own `"must not be empty"` reason),
        // but the manifest-layer empty arm runs first to surface the
        // narrower diagnostic verbatim.
        let c = caixa_with_repositorio(Some(""));
        let err = c.validate_repositorio().unwrap_err();
        assert!(
            matches!(err, ManifestError::RepositorioEmpty),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_repositorio_diagnostic_carries_offending_value() {
        // Diagnostic-shape pin (peer with
        // `validate_autores_diagnostic_carries_offending_author`): the
        // error's Display surfaces the offending value + slot name
        // verbatim, so a `feira lint` run can render the diagnostic
        // without re-parsing and the author can grep their caixa.lisp
        // for the offending `:repositorio` value.
        let c = caixa_with_repositorio(Some("pleme-io/hello-rio"));
        let rendered = c.validate_repositorio().unwrap_err().to_string();
        assert!(
            rendered.contains(":repositorio"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("pleme-io/hello-rio"),
            "diagnostic must quote the offending value: {rendered}",
        );
    }

    // ── validate_descricao — universal-axis Chart.yaml description shape ──

    fn caixa_with_descricao(descricao: Option<&str>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.descricao = descricao.map(String::from);
        c
    }

    #[test]
    fn validate_descricao_accepts_none() {
        // The omit-the-slot identity: `:descricao` is optional. The
        // gate is a no-op when the author didn't declare a value —
        // every caixa without a `:descricao` line trivially passes,
        // and the substrate-side renderers fall back to their
        // documented `caixa.nome`-derived placeholder. Mirrors the
        // peer `validate_repositorio_accepts_none` posture on the
        // sibling `Option<String>` Caixa slot.
        let c = caixa_with_descricao(None);
        c.validate_descricao().unwrap();
    }

    #[test]
    fn validate_descricao_accepts_canonical_summary() {
        // Positive control: the canonical pleme-io descricao shape —
        // a short free-form prose summary — passes the gate. Covers
        // the fixture shapes the `caixa-helm` / `caixa-flux` /
        // `caixa-mesh` test fixtures use (`"Canonical Rust→wasm32-
        // wasip2 caixa Servico."`, `"Checkout flow."`).
        for desc in [
            "Canonical Rust→wasm32-wasip2 caixa Servico.",
            "Checkout flow.",
            "AWS provider caixa for tatara-lisp",
            "FIXME — describe this caixa",
            "x",
        ] {
            let c = caixa_with_descricao(Some(desc));
            c.validate_descricao()
                .unwrap_or_else(|err| panic!("canonical {desc:?} must pass: {err:?}"));
        }
    }

    #[test]
    fn validate_descricao_rejects_empty_some() {
        // Canonical paste-from-blank-doc footgun. Without this gate
        // the empty `Some("")` silently passed the renderer's
        // `Option::unwrap_or_else(|| <fallback>)` (which only fires
        // on `None`) and landed as `description: ""` in `Chart.yaml`
        // and a blank `README.md` header. Mirrors the peer
        // [`ManifestError::RepositorioEmpty`] empty-arm on the
        // sibling `Option<String>` Caixa slot.
        let c = caixa_with_descricao(Some(""));
        let err = c.validate_descricao().unwrap_err();
        assert!(matches!(err, ManifestError::DescricaoEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_descricao_rejects_leading_whitespace() {
        // Paste-from-aligned-doc footgun: a leading ASCII space the
        // bare empty-arm gate accepted, the shape predicate now
        // refuses. The diagnostic carries the offending value
        // verbatim (with the leading space preserved) so the author
        // can grep their caixa.lisp for the exact `:descricao` line
        // and fix the round-trip-inconsistent leading whitespace.
        // Mirrors the peer
        // `validate_licenca_rejects_leading_whitespace` arm on the
        // sibling `:licenca` axis.
        let c = caixa_with_descricao(Some(" Checkout flow."));
        let err = c.validate_descricao().unwrap_err();
        let ManifestError::DescricaoInvalid { descricao, reason } = err else {
            panic!("expected DescricaoInvalid, got {err:?}");
        };
        assert_eq!(descricao, " Checkout flow.");
        assert!(reason.contains("whitespace"), "got: {reason:?}");
    }

    #[test]
    fn validate_descricao_rejects_trailing_whitespace() {
        // Paste-from-doc footgun: a trailing ASCII space the bare
        // empty-arm gate accepted, the shape predicate now refuses.
        let c = caixa_with_descricao(Some("Checkout flow. "));
        let err = c.validate_descricao().unwrap_err();
        let ManifestError::DescricaoInvalid { descricao, reason } = err else {
            panic!("expected DescricaoInvalid, got {err:?}");
        };
        assert_eq!(descricao, "Checkout flow. ");
        assert!(reason.contains("whitespace"), "got: {reason:?}");
    }

    #[test]
    fn validate_descricao_rejects_embedded_newline() {
        // Paste-from-multiline-doc footgun: an embedded LF the bare
        // empty-arm gate accepted, the shape predicate now refuses.
        // Without this gate the embedded newline silently landed in
        // the rendered Chart.yaml as a multi-line YAML block scalar,
        // and every chart-aware UI (`helm list`, `helm search`,
        // Artifact Hub) renders the description in a single-line
        // column so the embedded newline is silently dropped at
        // every downstream consumer.
        let c = caixa_with_descricao(Some("Checkout\nflow."));
        let err = c.validate_descricao().unwrap_err();
        assert!(
            matches!(err, ManifestError::DescricaoInvalid { .. }),
            "got {err:?}",
        );
        assert!(err.to_string().contains("newline"), "got {err}");
    }

    #[test]
    fn validate_descricao_rejects_embedded_carriage_return() {
        // Paste-from-Windows-CRLF-doc footgun.
        let c = caixa_with_descricao(Some("Checkout\rflow."));
        let err = c.validate_descricao().unwrap_err();
        assert!(
            matches!(err, ManifestError::DescricaoInvalid { .. }),
            "got {err:?}",
        );
        assert!(err.to_string().contains("carriage return"), "got {err}");
    }

    #[test]
    fn validate_descricao_rejects_embedded_tab() {
        // Tab-from-aligned-doc footgun.
        let c = caixa_with_descricao(Some("Checkout\tflow."));
        let err = c.validate_descricao().unwrap_err();
        assert!(
            matches!(err, ManifestError::DescricaoInvalid { .. }),
            "got {err:?}",
        );
        assert!(err.to_string().contains("tab"), "got {err}");
    }

    #[test]
    fn validate_descricao_rejects_embedded_control_bytes() {
        // Paste-from-binary-blob footgun: every other control byte
        // (NUL, BEL, ESC, DEL) is refused at validate time. Mirrors
        // the peer SPDX-expression control-byte arm.
        for s in [
            "Checkout\x00flow.",
            "Checkout\x07flow.",
            "Checkout\x1bflow.",
            "Checkout\x7fflow.",
        ] {
            let c = caixa_with_descricao(Some(s));
            let err = c.validate_descricao().unwrap_err();
            assert!(
                matches!(err, ManifestError::DescricaoInvalid { .. }),
                "{s:?} got {err:?}",
            );
            assert!(
                err.to_string().contains("control character"),
                "{s:?} got {err}",
            );
        }
    }

    #[test]
    fn validate_descricao_accepts_unicode_prose() {
        // Positive control: Unicode prose is accepted — the
        // canonical fixtures carry `→` (U+2192) and `—` (U+2014),
        // and `Caixa::template`'s `"FIXME — describe this caixa"`
        // scaffold every `feira init` emits must continue to pass.
        for s in [
            "Canonical Rust→wasm32-wasip2 caixa Servico.",
            "FIXME — describe this caixa",
            "Caixa pour le projet tâche",
            "日本語の説明",
        ] {
            let c = caixa_with_descricao(Some(s));
            c.validate_descricao()
                .unwrap_or_else(|err| panic!("Unicode {s:?} must pass: {err:?}"));
        }
    }

    #[test]
    fn validate_descricao_empty_takes_precedence_over_shape() {
        // Cascade pin: a `Some("")` surfaces the narrower
        // `DescricaoEmpty` arm, not the broader `DescricaoInvalid`
        // shape-predicate arm. Mirrors the peer
        // `validate_licenca_empty_takes_precedence_over_shape` pin
        // on the sibling `:licenca` axis.
        let c = caixa_with_descricao(Some(""));
        let err = c.validate_descricao().unwrap_err();
        assert!(matches!(err, ManifestError::DescricaoEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_descricao_invalid_diagnostic_carries_offending_value_and_slot() {
        // Diagnostic-shape pin: the error's Display surfaces both
        // the `:descricao` slot name and the offending value
        // verbatim, so a `feira lint` run can render the diagnostic
        // without re-parsing and the author can grep their caixa.lisp
        // for the offending `:descricao` line. Mirrors the peer
        // `validate_licenca_invalid_diagnostic_carries_offending_value_and_slot`
        // pin (ee2e888) on the sibling `:licenca` axis.
        // The `{descricao:?}` Debug format escapes embedded control
        // bytes; the quoted offending value surfaces as
        // `"Checkout\nflow."` (literal backslash-n) in the rendered
        // diagnostic. The author can grep their caixa.lisp for the
        // literal `Checkout` summary prefix.
        let c = caixa_with_descricao(Some("Checkout\nflow."));
        let rendered = c.validate_descricao().unwrap_err().to_string();
        assert!(
            rendered.contains(":descricao"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("Checkout\\nflow."),
            "diagnostic must quote the offending value (debug-escaped): {rendered}",
        );
    }

    #[test]
    fn validate_descricao_template_passes() {
        // Round-trip pin: the bare `Caixa::template` shape carries
        // `:descricao "FIXME — describe this caixa"` (a non-empty
        // sentinel), so the template-derived Caixa passes the gate by
        // construction. A future template-shape change that omits or
        // empties `:descricao` would surface here as a regression.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_descricao().unwrap();
    }

    #[test]
    fn validate_descricao_diagnostic_names_offending_slot() {
        // Diagnostic-shape pin (peer with
        // `validate_repositorio_diagnostic_carries_offending_value`):
        // the error's Display surfaces the `:descricao` slot name
        // verbatim, so a `feira lint` run can render the diagnostic
        // without re-parsing and the author can grep their caixa.lisp
        // for the offending `:descricao` line.
        let c = caixa_with_descricao(Some(""));
        let rendered = c.validate_descricao().unwrap_err().to_string();
        assert!(
            rendered.contains(":descricao"),
            "diagnostic must name the offending slot: {rendered}",
        );
    }

    // ── validate_licenca — universal-axis chart README license shape ──

    fn caixa_with_licenca(licenca: Option<&str>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.licenca = licenca.map(String::from);
        c
    }

    #[test]
    fn validate_licenca_accepts_none() {
        // The omit-the-slot identity: `:licenca` is optional. The
        // gate is a no-op when the author didn't declare a value —
        // every caixa without a `:licenca` line trivially passes,
        // and the substrate-side `caixa-helm` renderer falls back to
        // the documented `"MIT"` placeholder. Mirrors the peer
        // `validate_descricao_accepts_none` posture on the sibling
        // `Option<String>` Caixa slot.
        let c = caixa_with_licenca(None);
        c.validate_licenca().unwrap();
    }

    #[test]
    fn validate_licenca_accepts_canonical_expressions() {
        // Positive control: every canonical SPDX expression shape
        // pleme-io carries in its existing fixtures + the canonical
        // SPDX dual-license / with-exception / `+`-suffix / grouped /
        // user-defined-reference shapes all pass the gate. Covers
        // the single-license, `OR`-compound, `AND`-compound,
        // `WITH`-exception, parenthesis-grouped, `+`-suffix, and
        // `LicenseRef-` / `DocumentRef-:LicenseRef-` shapes — every
        // production the SPDX 2.1 expression grammar admits that
        // sits within the alphabet floor the
        // `is_spdx_expression_shape` predicate enforces.
        for lic in [
            "MIT",
            "Apache-2.0",
            "Apache-2.0 OR MIT",
            "Apache-2.0 AND MIT",
            "BSD-3-Clause",
            "MPL-2.0",
            "GPL-3.0-or-later",
            "GPL-2.0+",
            "Apache-2.0 WITH LLVM-exception",
            "(MIT OR Apache-2.0) AND BSD-3-Clause",
            "(MIT OR Apache-2.0) AND BSD-3-Clause AND ISC",
            "LicenseRef-MyLicense",
            "DocumentRef-spdx-tool:LicenseRef-MIT-Style",
            "x",
        ] {
            let c = caixa_with_licenca(Some(lic));
            c.validate_licenca()
                .unwrap_or_else(|err| panic!("canonical {lic:?} must pass: {err:?}"));
        }
    }

    #[test]
    fn validate_licenca_rejects_trailing_whitespace() {
        // Paste-from-doc whitespace footgun. A trailing space in the
        // `:licenca` value would silently break a downstream SPDX
        // parser that splits on exact `AND` / `OR` / `WITH` keyword
        // boundaries. The shape predicate refuses every trailing
        // whitespace byte by construction. Peer with
        // `validate_repositorio_rejects_whitespace` and
        // `validate_edicao_rejects_trailing_whitespace`.
        let c = caixa_with_licenca(Some("MIT "));
        let err = c.validate_licenca().unwrap_err();
        let ManifestError::LicencaInvalid { licenca, .. } = err else {
            panic!("expected LicencaInvalid, got {err:?}");
        };
        assert_eq!(licenca, "MIT ");
    }

    #[test]
    fn validate_licenca_rejects_leading_whitespace() {
        // Symmetric paste-from-doc whitespace footgun on the leading
        // boundary — the gate refuses every shape that starts with a
        // space byte by construction. Peer with
        // `validate_edicao_rejects_leading_whitespace`.
        let c = caixa_with_licenca(Some(" MIT"));
        let err = c.validate_licenca().unwrap_err();
        assert!(
            matches!(err, ManifestError::LicencaInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_licenca_rejects_control_char() {
        // Paste-from-multiline-doc CRLF footgun — control characters
        // at the value boundary land as a malformed line in the
        // rendered chart `README.md` `## License` section. Peer with
        // `validate_repositorio_rejects_control_char` and
        // `validate_edicao_rejects_control_char`.
        for lic in ["MIT\n", "MIT\r\n", "MIT\rApache-2.0"] {
            let c = caixa_with_licenca(Some(lic));
            let err = c.validate_licenca().unwrap_err();
            assert!(
                matches!(err, ManifestError::LicencaInvalid { .. }),
                "expected LicencaInvalid on {lic:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_licenca_rejects_tab() {
        // Tab-from-aligned-doc footgun — SPDX expressions use a
        // single ASCII space between tokens; a tab breaks every
        // downstream SPDX parser that splits on exact `" "`
        // boundaries.
        let c = caixa_with_licenca(Some("MIT\tOR Apache-2.0"));
        let err = c.validate_licenca().unwrap_err();
        assert!(
            matches!(err, ManifestError::LicencaInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_licenca_rejects_non_ascii() {
        // Smart-quote / non-ASCII paste footgun — SPDX identifiers
        // are ASCII per the `idstring = 1*(ALPHA / DIGIT / "-" /
        // ".")` production. The shape predicate refuses every
        // non-ASCII byte by construction; peer with
        // `validate_edicao_rejects_non_ascii_lookalike`.
        for lic in ["MIT\u{a0}OR Apache-2.0", "MIT\u{2013}1.0", "Café-1.0"] {
            let c = caixa_with_licenca(Some(lic));
            let err = c.validate_licenca().unwrap_err();
            assert!(
                matches!(err, ManifestError::LicencaInvalid { .. }),
                "expected LicencaInvalid on {lic:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_licenca_rejects_underscore() {
        // Underscore-instead-of-hyphen typo footgun — `Apache_2.0` /
        // `MIT_Style` / `BSD_3_Clause` are familiar shapes from
        // snake-case identifier conventions that don't apply to the
        // SPDX `idstring` grammar (which admits only `ALPHA / DIGIT /
        // "-" / "."`). The shape predicate refuses every underscore
        // byte by construction.
        for lic in ["Apache_2.0", "MIT_Style", "BSD_3_Clause"] {
            let c = caixa_with_licenca(Some(lic));
            let err = c.validate_licenca().unwrap_err();
            assert!(
                matches!(err, ManifestError::LicencaInvalid { .. }),
                "expected LicencaInvalid on {lic:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_licenca_rejects_comma_separator() {
        // Comma-instead-of-`OR`-keyword colloquial idiom footgun —
        // SPDX expressions compose multiple licenses via `AND` / `OR`
        // keywords, not the comma separator. The shape predicate
        // refuses every comma byte by construction.
        for lic in ["MIT, Apache-2.0", "MIT,Apache-2.0"] {
            let c = caixa_with_licenca(Some(lic));
            let err = c.validate_licenca().unwrap_err();
            assert!(
                matches!(err, ManifestError::LicencaInvalid { .. }),
                "expected LicencaInvalid on {lic:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_licenca_rejects_slash_dual_license() {
        // Slash-dual-license colloquial idiom footgun — the
        // `MIT/Apache-2.0` shape is common in Cargo's pre-SPDX
        // `package.license` field but non-SPDX; the SPDX equivalent
        // is `MIT OR Apache-2.0`. The shape predicate refuses every
        // forward-slash byte by construction.
        for lic in ["MIT/Apache-2.0", "MIT/BSD-3-Clause"] {
            let c = caixa_with_licenca(Some(lic));
            let err = c.validate_licenca().unwrap_err();
            assert!(
                matches!(err, ManifestError::LicencaInvalid { .. }),
                "expected LicencaInvalid on {lic:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_licenca_rejects_semicolon_separator() {
        // Semicolon-list-separator confusion footgun — adjacent to
        // the comma-separator idiom, every list-separator-belongs-
        // to-list-grammar confusion lands here.
        let c = caixa_with_licenca(Some("MIT; Apache-2.0"));
        let err = c.validate_licenca().unwrap_err();
        assert!(
            matches!(err, ManifestError::LicencaInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_licenca_empty_takes_precedence_over_shape() {
        // Empty-first cascade pin: the empty `Some("")` surfaces the
        // narrower `LicencaEmpty` not the shape-predicate-wrapped
        // `LicencaInvalid`, mirroring the peer
        // `validate_edicao_empty_takes_precedence_over_shape` and
        // `validate_repositorio_empty_takes_precedence_over_shape`
        // (`RepositorioEmpty` → `RepositorioInvalid`), `NomeEmpty` →
        // `NomeInvalid`, `VersaoEmpty` → `VersaoInvalid` cascades.
        // The shape predicate also refuses the empty input
        // (defensively — `"must not be empty"`), but the manifest-
        // layer empty arm runs first to surface the narrower
        // diagnostic verbatim.
        let c = caixa_with_licenca(Some(""));
        let err = c.validate_licenca().unwrap_err();
        assert!(matches!(err, ManifestError::LicencaEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_licenca_invalid_diagnostic_carries_offending_value() {
        // Diagnostic-shape pin on the shape-predicate arm (peer with
        // `validate_edicao_invalid_diagnostic_carries_offending_value`
        // and `validate_repositorio_diagnostic_carries_offending_value`):
        // the error's Display surfaces the offending value + slot
        // name verbatim, so a `feira lint` run can render the
        // diagnostic without re-parsing and the author can grep
        // their caixa.lisp for the offending `:licenca` value.
        let c = caixa_with_licenca(Some("Apache_2.0"));
        let rendered = c.validate_licenca().unwrap_err().to_string();
        assert!(
            rendered.contains(":licenca"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("Apache_2.0"),
            "diagnostic must quote the offending value: {rendered}",
        );
    }

    #[test]
    fn validate_licenca_rejects_empty_some() {
        // Canonical paste-from-blank-doc footgun. Without this gate
        // the empty `Some("")` silently passed the renderer's
        // `Option::unwrap_or_else(|| "MIT".into())` (which only
        // fires on `None`) and landed as a bare trailing period in
        // the rendered chart `README.md` `## License` section.
        // Mirrors the peer [`ManifestError::DescricaoEmpty`] empty-
        // arm on the sibling `Option<String>` Caixa slot.
        let c = caixa_with_licenca(Some(""));
        let err = c.validate_licenca().unwrap_err();
        assert!(matches!(err, ManifestError::LicencaEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_licenca_template_passes() {
        // Round-trip pin: the bare `Caixa::template` shape (whether
        // it carries `:licenca` or omits it) passes the gate by
        // construction. A future template-shape change that
        // introduced `(:licenca "")` would surface here as a
        // regression. Mirrors the peer
        // `validate_descricao_template_passes` pin.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_licenca().unwrap();
    }

    #[test]
    fn validate_licenca_diagnostic_names_offending_slot() {
        // Diagnostic-shape pin (peer with
        // `validate_descricao_diagnostic_names_offending_slot`):
        // the error's Display surfaces the `:licenca` slot name
        // verbatim, so a `feira lint` run can render the diagnostic
        // without re-parsing and the author can grep their caixa.lisp
        // for the offending `:licenca` line.
        let c = caixa_with_licenca(Some(""));
        let rendered = c.validate_licenca().unwrap_err().to_string();
        assert!(
            rendered.contains(":licenca"),
            "diagnostic must name the offending slot: {rendered}",
        );
    }

    // ── Caixa::licenca — outer top-level Option<&str> scalar accessor ──

    #[test]
    fn licenca_returns_licenca_byte_string_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:licenca` SPDX-expression scalar
        // pin: [`Caixa::licenca`] must return the `:licenca` typed
        // byte-string verbatim as an `Option<&str>`, byte-equal to the
        // raw `self.licenca.as_deref()` access across every
        // representative value in the accept-set — `None` (the "omit
        // the slot to defer to the caixa-helm renderer's `MIT`
        // fallback" arm every existing fixture without a `:licenca`
        // line carries), `Some("")` (a past-the-guard sentinel that
        // pins the accessor doesn't perform a silent
        // `Some("") → None` collapse on the empty arm — validate
        // rejects `Some("")` through `LicencaEmpty` but the accessor
        // must ship the raw slot verbatim so a validate-time gate
        // regression surfaces at the caixa-helm emit boundary rather
        // than being silently absorbed into the fallback), `Some("MIT")`
        // (the canonical single-license shape every `feira init`
        // template scaffolds), `Some("Apache-2.0 OR MIT")` (the
        // canonical `OR`-compound shape the peer
        // `validate_licenca_accepts_canonical_expressions` positive
        // sweep exercises), `Some("(MIT OR Apache-2.0) AND
        // BSD-3-Clause")` (the canonical parenthesis-grouped shape),
        // `Some("MIT ")` / `Some(" MIT")` / `Some("MIT\n")` /
        // `Some("Apache_2.0")` / `Some("MIT,Apache-2.0")` (past-the-
        // guard sentinels — validate rejects each through
        // `LicencaInvalid` but the accessor must ship the raw slot
        // verbatim).
        //
        // First outer top-level [`Caixa`] `Option<&str>`-return scalar
        // accessor pin on the substrate primitive — opens the "outer
        // [`Caixa`] `Option<&str>` scalar" projection pattern the
        // sibling per-`Caixa` `:descricao` / `:repositorio` / `:edicao`
        // future lifts fold on. Sibling in shape to the peer per-`:placement`
        // [`crate::aplicacao::Placement::shard_key`] (7cd2a28) /
        // [`crate::aplicacao::Placement::affinity`] (74ec2d3) accessor
        // pins on the sibling per-M3-mesh-slot `Option<&str>`-return
        // axes, extended onto the outer top-level [`Caixa`] universal-
        // axis surface. Pins against a future silent detour that
        // returned an owned `Option<String>` (which would type-check
        // but silently allocate on every accessor call, breaking the
        // zero-cost projection every peer sibling accessor carries), a
        // `Some("") → None` collapse (which would silently absorb the
        // `LicencaEmpty` refusal case at the accessor boundary and the
        // caixa-helm emit path would silently fall back to `"MIT"` on
        // a struct-literal `Caixa { licenca: Some(""), .. }`), or a
        // `None → Some("MIT")` collapse (which would silently reify
        // the caixa-helm renderer's `"MIT"` fallback at the accessor
        // boundary and every downstream consumer keying off the
        // `Option::is_none()` discriminator would lose the "author
        // omitted the slot" signal).
        for licenca in [
            None,
            Some(""),
            Some("MIT"),
            Some("Apache-2.0 OR MIT"),
            Some("(MIT OR Apache-2.0) AND BSD-3-Clause"),
            Some("MIT "),
            Some(" MIT"),
            Some("MIT\n"),
            Some("Apache_2.0"),
            Some("MIT,Apache-2.0"),
        ] {
            let c = caixa_with_licenca(licenca);
            assert_eq!(
                c.licenca(),
                licenca,
                "Caixa::licenca must return :licenca verbatim (got {:?}, \
                 expected {licenca:?})",
                c.licenca(),
            );
            assert_eq!(
                c.licenca(),
                c.licenca.as_deref(),
                "Caixa::licenca must byte-equal the raw \
                 `self.licenca.as_deref()` field access across every \
                 value in the Option<&str> accept-set",
            );
        }
    }

    #[test]
    fn validate_licenca_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_licenca`]'s empty-arm gate
        // must key off [`Caixa::licenca`], not the raw
        // `self.licenca.as_deref()` field access. Structurally: a
        // `Caixa { licenca: Some(""), .. }` must surface the
        // `LicencaEmpty` refusal exactly, and a
        // `Caixa { licenca: Some("MIT"), .. }` (the canonical
        // single-license form) must pass validate. The pair jointly
        // pins the accessor + validate-gate composition: any future
        // silent detour that had the accessor return `None` on the
        // empty arm (a `.filter(|s| !s.is_empty())` collapse) would
        // silently absorb the `LicencaEmpty` refusal at the accessor
        // boundary and the validate gate would accept a struct-literal
        // `Caixa { licenca: Some(""), .. }` — the composition pin
        // catches that at caixa-core build time.
        //
        // Peer of the per-`:politicas :circuit-breaker`
        // [`crate::aplicacao::CircuitBreaker::max_failures`] (3a74062)
        // accessor-composition pin
        // (`validate_politicas_max_failures_zero_floor_arm_routes_through_accessor`)
        // on the sibling per-M3-mesh-slot required-`u32` axis — same
        // "the validate / shape-gate predicate must route through the
        // substrate-primitive typed dispatch" discipline extended onto
        // the outer top-level [`Caixa`] universal-axis
        // `Option<&str>`-composition surface.
        let c = caixa_with_licenca(Some(""));
        assert!(
            matches!(c.validate_licenca(), Err(ManifestError::LicencaEmpty)),
            "validate_licenca must reject licenca == Some(\"\") with \
             LicencaEmpty — the accessor and the validate gate must \
             route through the same substrate-primitive typed dispatch \
             on the :licenca empty arm",
        );
        let c = caixa_with_licenca(Some("MIT"));
        assert!(
            c.validate_licenca().is_ok(),
            "validate_licenca must accept licenca == Some(\"MIT\") \
             (the canonical single-license SPDX shape)",
        );
    }

    #[test]
    fn licenca_projects_option_str_by_borrow() {
        // The by-borrow pin: [`Caixa::licenca`] returns
        // `Option<&str>` by borrow — the `&str` borrows the underlying
        // `String` storage of the `Option<String>` slot and the
        // accessor must not allocate a fresh `String` on every call.
        // Peer of the per-`:placement`
        // [`crate::aplicacao::Placement::shard_key`] (7cd2a28) by-
        // borrow pin on the peer per-M3-mesh-slot
        // `Option<&str>`-return axis, extended onto the outer top-
        // level [`Caixa`] universal-axis `Option<&str>` shape — the
        // accessor's returned `&str` must borrow from `&self` (the
        // returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // the same `Option<&str>` verbatim (idempotent, no side
        // effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Option<String>` (which would type-check but silently
        // allocate on every call, breaking the zero-cost projection
        // every peer sibling accessor carries), or a one-arm-only
        // accessor that returned a saturating value on some sentinel
        // input (breaking the pass-through invariant the sibling
        // required-scalar accessors carry).
        for licenca in [None, Some(""), Some("MIT"), Some("Apache-2.0 OR MIT")] {
            let c = caixa_with_licenca(licenca);
            let first = c.licenca();
            let second = c.licenca();
            assert_eq!(
                first, second,
                "Caixa::licenca must be idempotent — two successive \
                 calls on the same &self must return the same \
                 Option<&str>",
            );
            assert_eq!(
                first, licenca,
                "Caixa::licenca must return :licenca verbatim by \
                 borrow — got {first:?}, expected {licenca:?}",
            );
        }
    }

    // ── Caixa::repositorio — outer top-level Option<&str> scalar accessor ──

    #[test]
    fn repositorio_returns_repositorio_byte_string_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:repositorio` git-repo-URL scalar
        // pin: [`Caixa::repositorio`] must return the `:repositorio`
        // typed byte-string verbatim as an `Option<&str>`, byte-equal
        // to the raw `self.repositorio.as_deref()` access across every
        // representative value in the accept-set — `None` (the "omit
        // the slot to defer to the per-renderer placeholder" arm every
        // existing fixture without a `:repositorio` line carries),
        // `Some("")` (a past-the-guard sentinel that pins the accessor
        // doesn't perform a silent `Some("") → None` collapse on the
        // empty arm — validate rejects `Some("")` through
        // `RepositorioEmpty` but the accessor must ship the raw slot
        // verbatim so a validate-time gate regression surfaces at the
        // caixa-helm / caixa-flux emit boundary rather than being
        // silently absorbed into the per-renderer fallback),
        // `Some("github:pleme-io/hello-rio")` (the canonical `github:`
        // shorthand every existing manifest fixture across
        // `caixa-helm` / `caixa-mesh` and the `examples/` uses),
        // `Some("https://github.com/pleme-io/checkout")` (the canonical
        // `https://` URL the README quickstart uses),
        // `Some("ssh://git@github.com/pleme-io/checkout.git")` /
        // `Some("git://github.com/pleme-io/checkout.git")` /
        // `Some("git@github.com:pleme-io/checkout.git")` /
        // `Some("file:///opt/mirrors/pleme-io/checkout")` (every non-
        // github scheme the shared `is_git_repo_url` predicate
        // documents), and five past-the-guard sentinels for the
        // `RepositorioInvalid` refusal cases (`Some("pleme-io/checkout")`
        // missing-colon, `Some("-upload-pack=evil")` leading-dash, /
        // `Some("github:pleme-io/checkout?ref=main")` query-string, /
        // `Some("github:pleme-io/checkout#main")` fragment-anchor, /
        // `Some("github:pleme-io/{tpl}")` URI-template-placeholder — the
        // sentinels pin the accessor doesn't silently absorb the
        // refusal cases into a fallback).
        //
        // Second outer top-level [`Caixa`] `Option<&str>`-return scalar
        // accessor pin on the substrate primitive — sibling of the peer
        // [`Caixa::licenca`] (6d5bc28) pin
        // (`licenca_returns_licenca_byte_string_verbatim_across_permutations`)
        // that opened the "outer [`Caixa`] `Option<&str>` scalar"
        // projection pin pattern this pin folds on. Sibling in shape to
        // the peer per-`:placement`
        // [`crate::aplicacao::Placement::shard_key`] (7cd2a28) /
        // [`crate::aplicacao::Placement::affinity`] (74ec2d3) accessor
        // pins on the sibling per-M3-mesh-slot `Option<&str>`-return
        // axes, extended onto the outer top-level [`Caixa`] universal-
        // axis surface. Pins against a future silent detour that
        // returned an owned `Option<String>` (which would type-check
        // but silently allocate on every accessor call, breaking the
        // zero-cost projection every peer sibling accessor carries), a
        // `Some("") → None` collapse (which would silently absorb the
        // `RepositorioEmpty` refusal case at the accessor boundary and
        // the caixa-helm `Chart.yaml` `home:` fold would silently
        // render a `home: null` / omitted field on a struct-literal
        // `Caixa { repositorio: Some(""), .. }`), or a
        // `None → Some(<default>)` collapse (which would silently reify
        // the per-renderer fallback at the accessor boundary and every
        // downstream consumer keying off the `Option::is_none()`
        // discriminator would lose the "author omitted the slot"
        // signal).
        for repositorio in [
            None,
            Some(""),
            Some("github:pleme-io/hello-rio"),
            Some("https://github.com/pleme-io/checkout"),
            Some("ssh://git@github.com/pleme-io/checkout.git"),
            Some("git://github.com/pleme-io/checkout.git"),
            Some("git@github.com:pleme-io/checkout.git"),
            Some("file:///opt/mirrors/pleme-io/checkout"),
            Some("pleme-io/checkout"),
            Some("-upload-pack=evil"),
            Some("github:pleme-io/checkout?ref=main"),
            Some("github:pleme-io/checkout#main"),
            Some("github:pleme-io/{tpl}"),
        ] {
            let c = caixa_with_repositorio(repositorio);
            assert_eq!(
                c.repositorio(),
                repositorio,
                "Caixa::repositorio must return :repositorio verbatim \
                 (got {:?}, expected {repositorio:?})",
                c.repositorio(),
            );
            assert_eq!(
                c.repositorio(),
                c.repositorio.as_deref(),
                "Caixa::repositorio must byte-equal the raw \
                 `self.repositorio.as_deref()` field access across every \
                 value in the Option<&str> accept-set",
            );
        }
    }

    #[test]
    fn validate_repositorio_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_repositorio`]'s empty-arm
        // gate must key off [`Caixa::repositorio`], not the raw
        // `self.repositorio.as_deref()` field access. Structurally: a
        // `Caixa { repositorio: Some(""), .. }` must surface the
        // `RepositorioEmpty` refusal exactly, and a
        // `Caixa { repositorio: Some("github:pleme-io/hello-rio"), .. }`
        // (the canonical `github:` shorthand form) must pass validate.
        // The pair jointly pins the accessor + validate-gate
        // composition: any future silent detour that had the accessor
        // return `None` on the empty arm (a `.filter(|s| !s.is_empty())`
        // collapse) would silently absorb the `RepositorioEmpty` refusal
        // at the accessor boundary and the validate gate would accept a
        // struct-literal `Caixa { repositorio: Some(""), .. }` — the
        // composition pin catches that at caixa-core build time.
        //
        // Peer of the [`Caixa::licenca`] (6d5bc28)
        // `validate_licenca_empty_arm_routes_through_accessor`
        // composition pin on the sibling outer top-level [`Caixa`]
        // `Option<&str>` universal-axis surface — same "the validate /
        // shape-gate predicate must route through the substrate-
        // primitive typed dispatch" discipline extended onto the second
        // outer top-level [`Caixa`] universal-axis `Option<&str>`-
        // composition surface.
        let c = caixa_with_repositorio(Some(""));
        assert!(
            matches!(
                c.validate_repositorio(),
                Err(ManifestError::RepositorioEmpty),
            ),
            "validate_repositorio must reject repositorio == Some(\"\") \
             with RepositorioEmpty — the accessor and the validate gate \
             must route through the same substrate-primitive typed \
             dispatch on the :repositorio empty arm",
        );
        let c = caixa_with_repositorio(Some("github:pleme-io/hello-rio"));
        assert!(
            c.validate_repositorio().is_ok(),
            "validate_repositorio must accept repositorio == \
             Some(\"github:pleme-io/hello-rio\") (the canonical \
             `github:` shorthand git-repo-URL shape)",
        );
    }

    #[test]
    fn repositorio_projects_option_str_by_borrow() {
        // The by-borrow pin: [`Caixa::repositorio`] returns
        // `Option<&str>` by borrow — the `&str` borrows the underlying
        // `String` storage of the `Option<String>` slot and the
        // accessor must not allocate a fresh `String` on every call.
        // Peer of the per-`:placement`
        // [`crate::aplicacao::Placement::shard_key`] (7cd2a28) and the
        // [`Caixa::licenca`] (6d5bc28) by-borrow pins on the peer
        // `Option<&str>`-return axes, extended onto the second outer
        // top-level [`Caixa`] universal-axis `Option<&str>` shape —
        // the accessor's returned `&str` must borrow from `&self` (the
        // returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // the same `Option<&str>` verbatim (idempotent, no side effects
        // on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Option<String>` (which would type-check but silently
        // allocate on every call, breaking the zero-cost projection
        // every peer sibling accessor carries), or a one-arm-only
        // accessor that returned a saturating value on some sentinel
        // input (breaking the pass-through invariant the sibling
        // required-scalar accessors carry).
        for repositorio in [
            None,
            Some(""),
            Some("github:pleme-io/hello-rio"),
            Some("https://github.com/pleme-io/checkout"),
        ] {
            let c = caixa_with_repositorio(repositorio);
            let first = c.repositorio();
            let second = c.repositorio();
            assert_eq!(
                first, second,
                "Caixa::repositorio must be idempotent — two successive \
                 calls on the same &self must return the same \
                 Option<&str>",
            );
            assert_eq!(
                first, repositorio,
                "Caixa::repositorio must return :repositorio verbatim by \
                 borrow — got {first:?}, expected {repositorio:?}",
            );
        }
    }

    // ── Caixa::canonical_git_url — resolved-git-URL composer ──────────

    #[test]
    fn canonical_git_url_returns_repositorio_verbatim_on_some_arm() {
        // Fail-before-pass-after pin: [`Caixa::canonical_git_url`] must
        // return the author-declared `:repositorio` byte-string verbatim
        // on the `Some` arm — no scheme rewrite, no trailing-slash
        // canonicalization, no `github:` → `https://github.com/`
        // desugaring. The resolved-URL composer is the projection of
        // the raw [`Caixa::repositorio`] `Option<&str>` accessor onto
        // the `String`-return arity every substrate-side field-fill
        // consumer keys off; on the `Some` arm the projection is
        // `str::to_owned` verbatim, so every accept-set value the
        // sibling `repositorio_returns_repositorio_byte_string_verbatim_
        // across_permutations` pin covers (`https://…`, `github:…`,
        // `ssh://…`, `git://…`, `git@…`, `file://…`, and the past-the-
        // guard sentinel `pleme-io/…`) must survive the accessor
        // byte-equal. Pins against a future silent detour that rewrote
        // the `github:` shorthand to the `https://github.com/` full URL
        // at the accessor boundary (which would silently split the
        // resolved-URL surface from the raw [`Caixa::repositorio`]
        // accessor's documented pass-through invariant), or a trailing-
        // slash normalization (which would silently break the
        // FluxCD `GitRepository` `spec.url` byte-exact match every
        // downstream consumer keys the source-controller reconcile off).
        for repositorio in [
            "github:pleme-io/hello-rio",
            "https://github.com/pleme-io/checkout",
            "ssh://git@github.com/pleme-io/checkout.git",
            "git://github.com/pleme-io/checkout.git",
            "git@github.com:pleme-io/checkout.git",
            "file:///opt/mirrors/pleme-io/checkout",
        ] {
            let c = caixa_with_repositorio(Some(repositorio));
            assert_eq!(
                c.canonical_git_url(),
                repositorio,
                "Caixa::canonical_git_url on the Some arm must return \
                 :repositorio verbatim (got {:?}, expected {repositorio:?})",
                c.canonical_git_url(),
            );
        }
    }

    #[test]
    fn canonical_git_url_falls_back_to_pleme_org_url_on_none_arm() {
        // Fail-before-pass-after pin: [`Caixa::canonical_git_url`] on the
        // `None` arm must emit the substrate's canonical pleme-org github
        // URL derived from `caixa.nome()` — `https://github.com/<org>/
        // <nome>` with `<org>` bound to [`crate::DEFAULT_PLEME_GIT_ORG`]
        // and `<nome>` bound to the typed [`Caixa::nome`] accessor. This
        // is the exact byte-image of the prior inline
        // [`caixa-flux::ClusterBundleOpts::for_caixa`] `git_url`
        // composer at caixa-flux/src/lib.rs:2080 that every prior caller
        // re-derived open-coded. Pins against a future silent detour
        // that migrated the `<org>` segment to a different constant (a
        // fork rebranding that split off a new
        // `DEFAULT_PLEME_GIT_ORG_MIRROR` const the accessor would need
        // to migrate onto), a scheme change (`https://` → `git://` or
        // `ssh://`), or a per-`Caixa` `.canonical_git_url_prefix`
        // override (which would break the substrate-wide single-source-
        // of-truth guarantee this method encodes).
        let c = caixa_with_repositorio(None);
        let expected = format!(
            "https://github.com/{org}/{nome}",
            org = crate::DEFAULT_PLEME_GIT_ORG,
            nome = c.nome(),
        );
        assert_eq!(
            c.canonical_git_url(),
            expected,
            "Caixa::canonical_git_url on the None arm must fold through \
             the substrate's canonical pleme-org github URL fallback \
             `https://github.com/<DEFAULT_PLEME_GIT_ORG>/<nome>` — got \
             {:?}, expected {expected:?}",
            c.canonical_git_url(),
        );
    }

    #[test]
    fn canonical_git_url_byte_matches_manual_composition() {
        // Byte-parity pin: [`Caixa::canonical_git_url`] must render
        // byte-identically to the manual open-coded
        // `caixa.repositorio().map(str::to_owned).unwrap_or_else(||
        //  format!("https://github.com/{org}/{nome}", ...))` composition
        // every prior substrate-side caller re-derived. Guards the
        // paired-site convergence just applied at caixa-flux's
        // [`ClusterBundleOpts::for_caixa`] `git_url` composer (which
        // now routes through this accessor): a future implementation of
        // this method that reordered the format arguments, swapped the
        // `<org>` constant for a different one, or interposed a
        // canonicalization pass on the `Some` arm surfaces here as a
        // caixa-core build-time test failure rather than as a downstream
        // FluxCD `GitRepository` reconcile mismatch far from this
        // method's source.
        for repositorio in [
            None,
            Some("github:pleme-io/hello-rio"),
            Some("https://github.com/pleme-io/checkout"),
            Some("ssh://git@github.com/pleme-io/checkout.git"),
        ] {
            let c = caixa_with_repositorio(repositorio);
            let manual = c.repositorio().map_or_else(
                || {
                    format!(
                        "https://github.com/{org}/{nome}",
                        org = crate::DEFAULT_PLEME_GIT_ORG,
                        nome = c.nome(),
                    )
                },
                str::to_owned,
            );
            assert_eq!(
                c.canonical_git_url(),
                manual,
                "Caixa::canonical_git_url must byte-equal the manual \
                 open-coded `repositorio().map(str::to_owned)\
                 .unwrap_or_else(|| format!(...))` composition across \
                 every representative :repositorio input — got {:?}, \
                 expected {manual:?}",
                c.canonical_git_url(),
            );
        }
    }

    // ── Caixa::publish_tag — resolved-publish-tag composer ───────────

    #[test]
    fn publish_tag_composes_prefix_and_versao_on_all_shapes() {
        // Fail-before-pass-after pin: [`Caixa::publish_tag`] must compose
        // [`crate::DEFAULT_PUBLISH_TAG_PREFIX`] against the caixa's typed
        // [`Caixa::versao`] byte-string across every SemVer-2 shape the
        // sibling [`validate_versao_accepts_canonical_forms`] positive-set
        // sweep documents — bare MAJOR.MINOR.PATCH, pre-release tags
        // (`-rc.1`), build metadata (`+build.42`), the combined form, and
        // the `0.0.0` boundary case. Every accept-set value the peer
        // validate gate lets through must survive the resolved-tag
        // projection byte-equal.
        for versao in [
            "0.1.0",
            "0.0.0",
            "1.0.0",
            "1.2.3-rc.1",
            "1.2.3+build.42",
            "1.2.3-rc.1+build.42",
        ] {
            let c = caixa_with_versao(versao);
            let expected = format!(
                "{prefix}{versao}",
                prefix = crate::DEFAULT_PUBLISH_TAG_PREFIX,
            );
            assert_eq!(
                c.publish_tag(),
                expected,
                "Caixa::publish_tag must compose \
                 DEFAULT_PUBLISH_TAG_PREFIX ({prefix:?}) against \
                 :versao ({versao:?}) verbatim — got {got:?}, \
                 expected {expected:?}",
                prefix = crate::DEFAULT_PUBLISH_TAG_PREFIX,
                got = c.publish_tag(),
            );
        }
    }

    #[test]
    fn publish_tag_starts_with_default_publish_tag_prefix() {
        // Prefix-shape pin: every [`Caixa::publish_tag`] emission must
        // begin with the canonical [`crate::DEFAULT_PUBLISH_TAG_PREFIX`]
        // byte-string on every input, guarding a hypothetical future
        // implementation that migrated the prefix segment to an inline
        // literal (`"v"`) that would silently drift from any rebrand of
        // the lifted constant. Peer to the sibling caixa-flux
        // `cluster_bundle_default_git_tag_uses_lifted_caixa_core_prefix`
        // test which pins the same prefix invariant at the reader-side
        // `GitRefSpec::Tag` emit site.
        for versao in ["0.0.0", "0.1.0", "1.2.3-rc.1", "9.9.9+build.1"] {
            let c = caixa_with_versao(versao);
            let tag = c.publish_tag();
            assert!(
                tag.starts_with(crate::DEFAULT_PUBLISH_TAG_PREFIX),
                "Caixa::publish_tag emission {tag:?} must start with \
                 the lifted crate::DEFAULT_PUBLISH_TAG_PREFIX \
                 ({prefix:?})",
                prefix = crate::DEFAULT_PUBLISH_TAG_PREFIX,
            );
        }
    }

    #[test]
    fn publish_tag_byte_matches_manual_composition() {
        // Byte-parity pin: [`Caixa::publish_tag`] must render byte-
        // identically to the manual open-coded
        // `format!("{prefix}{versao}", prefix =
        //  caixa_core::DEFAULT_PUBLISH_TAG_PREFIX, versao =
        //  caixa.versao())` composition every prior substrate-side
        // caller re-derived. Guards the paired-site convergence just
        // applied at caixa-flux's [`ClusterBundleOpts::for_caixa`]
        // `git_ref` composer (which now routes through this accessor):
        // a future implementation of this method that reordered the
        // format arguments, swapped the `<prefix>` constant for a
        // different one, or interposed a canonicalization pass on the
        // `:versao` axis surfaces here as a caixa-core build-time test
        // failure rather than as a downstream FluxCD `GitRepository`
        // reconcile mismatch far from this method's source.
        for versao in [
            "0.1.0",
            "0.0.0",
            "1.2.3-rc.1",
            "1.2.3+build.42",
            "1.2.3-rc.1+build.42",
        ] {
            let c = caixa_with_versao(versao);
            let manual = format!(
                "{prefix}{versao}",
                prefix = crate::DEFAULT_PUBLISH_TAG_PREFIX,
                versao = c.versao(),
            );
            assert_eq!(
                c.publish_tag(),
                manual,
                "Caixa::publish_tag must byte-equal the manual \
                 open-coded `format!(\"{{prefix}}{{versao}}\", ...)` \
                 composition across every representative :versao input \
                 — got {got:?}, expected {manual:?}",
                got = c.publish_tag(),
            );
        }
    }

    // ── Caixa::lareira_chart_name — resolved-chart-name composer ─────

    #[test]
    fn lareira_chart_name_composes_prefix_and_nome_on_all_shapes() {
        // Fail-before-pass-after pin: [`Caixa::lareira_chart_name`] must
        // compose [`crate::LAREIRA_CHART_NAME_PREFIX`] against the caixa's
        // typed [`Caixa::nome`] byte-string across every DNS-1123 shape
        // the sibling [`validate_nome_accepts_canonical_forms`] positive-
        // set sweep documents — single-word, hyphen-joined, version-
        // suffixed, single-char, two-char, digit-start, retry-suffixed.
        // Every accept-set value the peer validate gate lets through must
        // survive the resolved-chart-name projection byte-equal.
        for nome in [
            "checkout",
            "cart-v2",
            "a",
            "db",
            "3rd-party-shim",
            "payment-retry",
            "0",
        ] {
            let c = caixa_with_nome(nome);
            let expected = format!("{prefix}{nome}", prefix = crate::LAREIRA_CHART_NAME_PREFIX);
            assert_eq!(
                c.lareira_chart_name(),
                expected,
                "Caixa::lareira_chart_name must compose \
                 LAREIRA_CHART_NAME_PREFIX ({prefix:?}) against \
                 :nome ({nome:?}) verbatim — got {got:?}, \
                 expected {expected:?}",
                prefix = crate::LAREIRA_CHART_NAME_PREFIX,
                got = c.lareira_chart_name(),
            );
        }
    }

    #[test]
    fn lareira_chart_name_starts_with_lifted_prefix() {
        // Prefix-shape pin: every [`Caixa::lareira_chart_name`] emission
        // must begin with the canonical
        // [`crate::LAREIRA_CHART_NAME_PREFIX`] byte-string on every
        // input, guarding a hypothetical future implementation that
        // migrated the prefix segment to an inline literal (`"lareira-"`)
        // that would silently drift from any rebrand of the lifted
        // constant. Peer to the sibling
        // [`publish_tag_starts_with_default_publish_tag_prefix`] pin on
        // the co-resident resolved-publish-tag composer's prefix axis.
        for nome in ["checkout", "cart", "a", "payment-retry", "0"] {
            let c = caixa_with_nome(nome);
            let chart = c.lareira_chart_name();
            assert!(
                chart.starts_with(crate::LAREIRA_CHART_NAME_PREFIX),
                "Caixa::lareira_chart_name emission {chart:?} must start \
                 with the lifted crate::LAREIRA_CHART_NAME_PREFIX \
                 ({prefix:?})",
                prefix = crate::LAREIRA_CHART_NAME_PREFIX,
            );
        }
    }

    #[test]
    fn lareira_chart_name_byte_matches_canonical_helper_composition() {
        // Byte-parity pin: [`Caixa::lareira_chart_name`] must render
        // byte-identically to the manual open-coded
        // `caixa_core::lareira_chart_name(caixa.nome())` two-step
        // composition every prior substrate-side caller re-derived.
        // Guards the paired-site convergence just applied at caixa-helm's
        // [`render_chart_for_servico_with`] `ChartDir.name` composer,
        // caixa-flux's [`cluster_bundle`] per-CR `chart_name` binding,
        // and caixa-tatara's [`process_for_aplicacao`] `release_name`
        // composer (all of which now route through this accessor): a
        // future implementation of this method that reordered the
        // composition arguments, swapped the `<prefix>` constant for a
        // different one, or interposed a canonicalization pass on the
        // `:nome` axis surfaces here as a caixa-core build-time test
        // failure rather than as a downstream Helm chart-render / FluxCD
        // reconcile / tatara Process-CR mismatch far from this method's
        // source.
        for nome in [
            "checkout",
            "cart-v2",
            "a",
            "db",
            "3rd-party-shim",
            "payment-retry",
        ] {
            let c = caixa_with_nome(nome);
            let manual = crate::lareira_chart_name(c.nome());
            assert_eq!(
                c.lareira_chart_name(),
                manual,
                "Caixa::lareira_chart_name must byte-equal the manual \
                 open-coded `caixa_core::lareira_chart_name(caixa.nome())` \
                 composition across every representative :nome input — \
                 got {got:?}, expected {manual:?}",
                got = c.lareira_chart_name(),
            );
        }
    }

    // ── Caixa::oci_chart_ref — resolved-OCI-chart-ref composer ────────

    #[test]
    fn oci_chart_ref_composes_scheme_and_lareira_chart_name_on_all_shapes() {
        // Fail-before-pass-after pin: [`Caixa::oci_chart_ref`] must
        // compose [`crate::OCI_SCHEME_PREFIX`] + the caller-supplied
        // `registry` + [`crate::lareira_chart_name`]-of-[`Caixa::nome`]
        // across the full paired `(registry, :nome)` accept-set — every
        // representative registry the substrate-side emitters carry
        // (`ghcr.io/pleme-io/charts`, the canonical CAIXA-SDLC §II
        // ArtifactHub-tier registry; `ghcr.io/pleme-io`, the bare-org
        // arm the sibling `oci_chart_ref_pins_byte_shape_against_prior_
        // inline_format` render-side pin exercises; `registry.example.
        // com`, an off-org shape; `localhost:5000`, the local-dev shape
        // every `feira chart` iteration path lands under) × every DNS-
        // 1123 `:nome` shape the peer `validate_nome_accepts_canonical_
        // forms` positive-set sweep documents (single-word, hyphen-
        // joined, single-char, two-char, digit-start, retry-suffixed).
        // Every accept-set pair the peer validate gates let through must
        // survive the resolved-OCI-ref projection byte-equal.
        for registry in [
            "ghcr.io/pleme-io/charts",
            "ghcr.io/pleme-io",
            "registry.example.com",
            "localhost:5000",
        ] {
            for nome in [
                "checkout",
                "cart-v2",
                "a",
                "db",
                "3rd-party-shim",
                "payment-retry",
                "0",
            ] {
                let c = caixa_with_nome(nome);
                let expected = format!(
                    "{scheme}{registry}/{chart}",
                    scheme = crate::OCI_SCHEME_PREFIX,
                    chart = crate::lareira_chart_name(nome),
                );
                assert_eq!(
                    c.oci_chart_ref(registry),
                    expected,
                    "Caixa::oci_chart_ref must compose \
                     OCI_SCHEME_PREFIX ({scheme:?}) + registry ({registry:?}) + \
                     lareira_chart_name(:nome ({nome:?})) verbatim — got {got:?}, \
                     expected {expected:?}",
                    scheme = crate::OCI_SCHEME_PREFIX,
                    got = c.oci_chart_ref(registry),
                );
            }
        }
    }

    #[test]
    fn oci_chart_ref_starts_with_lifted_scheme_prefix() {
        // Scheme-prefix-shape pin: every [`Caixa::oci_chart_ref`]
        // emission must begin with the canonical
        // [`crate::OCI_SCHEME_PREFIX`] byte-string on every input, guarding
        // a hypothetical future implementation that migrated the scheme
        // segment to an inline literal (`"oci://"`) that would silently
        // drift from any rebrand of the lifted constant. Peer to the
        // sibling [`publish_tag_starts_with_default_publish_tag_prefix`]
        // + [`lareira_chart_name_starts_with_lifted_prefix`] pins on the
        // co-resident resolved-publish-tag / resolved-chart-name
        // composers' prefix axes.
        for registry in [
            "ghcr.io/pleme-io/charts",
            "ghcr.io/pleme-io",
            "localhost:5000",
        ] {
            for nome in ["checkout", "cart", "a", "payment-retry", "0"] {
                let c = caixa_with_nome(nome);
                let ref_ = c.oci_chart_ref(registry);
                assert!(
                    ref_.starts_with(crate::OCI_SCHEME_PREFIX),
                    "Caixa::oci_chart_ref emission {ref_:?} must start \
                     with the lifted crate::OCI_SCHEME_PREFIX ({scheme:?}) \
                     — registry ({registry:?}), :nome ({nome:?})",
                    scheme = crate::OCI_SCHEME_PREFIX,
                );
            }
        }
    }

    #[test]
    fn oci_chart_ref_byte_matches_canonical_helper_composition() {
        // Byte-parity pin: [`Caixa::oci_chart_ref`] must render byte-
        // identically to the manual open-coded
        // `caixa_core::oci_chart_ref(registry, caixa.nome())` two-step
        // composition every prior substrate-side caller re-derived.
        // Guards the paired-site convergence just applied at caixa-
        // tatara's [`derive_chart_ref`] helper (which now routes through
        // this accessor): a future implementation of this method that
        // reordered the composition arguments, swapped the `<scheme>`
        // constant for a different one, migrated the `<chart>` segment
        // off the paired [`crate::lareira_chart_name`] composer, or
        // interposed a canonicalization pass on either input axis
        // surfaces here as a caixa-core build-time test failure rather
        // than as a downstream `helm install` / FluxCD OCI-source
        // reconcile / tatara `Process`-CR mismatch far from this
        // method's source. Sibling to the peer
        // [`lareira_chart_name_byte_matches_canonical_helper_composition`]
        // / [`publish_tag_byte_matches_manual_composition`] /
        // [`canonical_git_url_byte_matches_manual_composition`] byte-
        // parity pins that carry the same discipline on the co-resident
        // resolved-chart-name / resolved-publish-tag / resolved-git-URL
        // composers.
        for registry in [
            "ghcr.io/pleme-io/charts",
            "ghcr.io/pleme-io",
            "registry.example.com",
            "localhost:5000",
        ] {
            for nome in [
                "checkout",
                "cart-v2",
                "a",
                "db",
                "3rd-party-shim",
                "payment-retry",
            ] {
                let c = caixa_with_nome(nome);
                let manual = crate::oci_chart_ref(registry, c.nome());
                assert_eq!(
                    c.oci_chart_ref(registry),
                    manual,
                    "Caixa::oci_chart_ref must byte-equal the manual \
                     open-coded `caixa_core::oci_chart_ref(registry, \
                     caixa.nome())` composition across every representative \
                     (registry, :nome) pair — registry ({registry:?}), \
                     :nome ({nome:?}), got {got:?}, expected {manual:?}",
                    got = c.oci_chart_ref(registry),
                );
            }
        }
    }

    // ── Caixa::descricao — outer top-level Option<&str> scalar accessor ──

    #[test]
    fn descricao_returns_descricao_byte_string_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:descricao` free-form-prose scalar
        // pin: [`Caixa::descricao`] must return the `:descricao` typed
        // byte-string verbatim as an `Option<&str>`, byte-equal to the
        // raw `self.descricao.as_deref()` access across every
        // representative value in the accept-set — `None` (the "omit
        // the slot to defer to the per-renderer `caixa.nome`-derived
        // fallback" arm every existing fixture without a `:descricao`
        // line carries), `Some("")` (a past-the-guard sentinel that
        // pins the accessor doesn't perform a silent `Some("") → None`
        // collapse on the empty arm — validate rejects `Some("")`
        // through `DescricaoEmpty` but the accessor must ship the raw
        // slot verbatim so a validate-time gate regression surfaces at
        // the caixa-helm / caixa-feira emit boundary rather than being
        // silently absorbed into the per-renderer `caixa.nome`-derived
        // fallback), `Some("Checkout flow.")` (the canonical one-line
        // prose descriptor the peer
        // `validate_descricao_accepts_canonical_value` positive sweep
        // exercises), `Some("Canonical Rust→wasm32-wasip2 caixa
        // Servico.")` (the multi-byte Unicode continuation-byte shape
        // the `hello-rio` fixture carries), `Some("→ — · ✓")` (a
        // multi-glyph Unicode shape the peer
        // `is_chart_description_shape` predicate accepts), and five
        // past-the-guard sentinels for the `DescricaoInvalid` refusal
        // cases (`Some(" Checkout flow.")` leading-whitespace,
        // `Some("Checkout flow. ")` trailing-whitespace,
        // `Some("Checkout\nflow.")` embedded-LF,
        // `Some("Checkout\tflow.")` embedded-TAB, and
        // `Some("Checkout\x00flow.")` embedded-NUL — the sentinels pin
        // the accessor doesn't silently absorb the refusal cases into
        // a fallback).
        //
        // Third outer top-level [`Caixa`] `Option<&str>`-return scalar
        // accessor pin on the substrate primitive — sibling of the peer
        // [`Caixa::licenca`] (6d5bc28) and [`Caixa::repositorio`]
        // (cc7332d) pins that opened the "outer [`Caixa`]
        // `Option<&str>` scalar" projection pin pattern this pin folds
        // on. Sibling in shape to the peer per-`:placement`
        // [`crate::aplicacao::Placement::shard_key`] (7cd2a28) /
        // [`crate::aplicacao::Placement::affinity`] (74ec2d3) accessor
        // pins on the sibling per-M3-mesh-slot `Option<&str>`-return
        // axes, extended onto the outer top-level [`Caixa`] universal-
        // axis surface. Pins against a future silent detour that
        // returned an owned `Option<String>` (which would type-check
        // but silently allocate on every accessor call, breaking the
        // zero-cost projection every peer sibling accessor carries), a
        // `Some("") → None` collapse (which would silently absorb the
        // `DescricaoEmpty` refusal case at the accessor boundary and
        // the caixa-helm `Chart.yaml` `description:` fold would
        // silently render a `caixa.nome`-derived fallback on a
        // struct-literal `Caixa { descricao: Some(""), .. }`), or a
        // `None → Some(<default>)` collapse (which would silently
        // reify the per-renderer `caixa.nome`-derived fallback at the
        // accessor boundary and every downstream consumer keying off
        // the `Option::is_none()` discriminator would lose the "author
        // omitted the slot" signal).
        for descricao in [
            None,
            Some(""),
            Some("Checkout flow."),
            Some("Canonical Rust→wasm32-wasip2 caixa Servico."),
            Some("→ — · ✓"),
            Some(" Checkout flow."),
            Some("Checkout flow. "),
            Some("Checkout\nflow."),
            Some("Checkout\tflow."),
            Some("Checkout\x00flow."),
        ] {
            let c = caixa_with_descricao(descricao);
            assert_eq!(
                c.descricao(),
                descricao,
                "Caixa::descricao must return :descricao verbatim (got \
                 {:?}, expected {descricao:?})",
                c.descricao(),
            );
            assert_eq!(
                c.descricao(),
                c.descricao.as_deref(),
                "Caixa::descricao must byte-equal the raw \
                 `self.descricao.as_deref()` field access across every \
                 value in the Option<&str> accept-set",
            );
        }
    }

    #[test]
    fn validate_descricao_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_descricao`]'s empty-arm
        // gate must key off [`Caixa::descricao`], not the raw
        // `self.descricao.as_deref()` field access. Structurally: a
        // `Caixa { descricao: Some(""), .. }` must surface the
        // `DescricaoEmpty` refusal exactly, and a
        // `Caixa { descricao: Some("Checkout flow."), .. }` (the
        // canonical one-line-prose form) must pass validate. The pair
        // jointly pins the accessor + validate-gate composition: any
        // future silent detour that had the accessor return `None` on
        // the empty arm (a `.filter(|s| !s.is_empty())` collapse) would
        // silently absorb the `DescricaoEmpty` refusal at the accessor
        // boundary and the validate gate would accept a struct-literal
        // `Caixa { descricao: Some(""), .. }` — the composition pin
        // catches that at caixa-core build time.
        //
        // Peer of the [`Caixa::licenca`] (6d5bc28)
        // `validate_licenca_empty_arm_routes_through_accessor` and
        // [`Caixa::repositorio`] (cc7332d)
        // `validate_repositorio_empty_arm_routes_through_accessor`
        // composition pins on the sibling outer top-level [`Caixa`]
        // `Option<&str>` universal-axis surface — same "the validate /
        // shape-gate predicate must route through the substrate-
        // primitive typed dispatch" discipline extended onto the third
        // outer top-level [`Caixa`] universal-axis `Option<&str>`-
        // composition surface.
        let c = caixa_with_descricao(Some(""));
        assert!(
            matches!(c.validate_descricao(), Err(ManifestError::DescricaoEmpty),),
            "validate_descricao must reject descricao == Some(\"\") \
             with DescricaoEmpty — the accessor and the validate gate \
             must route through the same substrate-primitive typed \
             dispatch on the :descricao empty arm",
        );
        let c = caixa_with_descricao(Some("Checkout flow."));
        assert!(
            c.validate_descricao().is_ok(),
            "validate_descricao must accept descricao == \
             Some(\"Checkout flow.\") (the canonical one-line-prose \
             chart-description shape)",
        );
    }

    #[test]
    fn descricao_projects_option_str_by_borrow() {
        // The by-borrow pin: [`Caixa::descricao`] returns
        // `Option<&str>` by borrow — the `&str` borrows the underlying
        // `String` storage of the `Option<String>` slot and the
        // accessor must not allocate a fresh `String` on every call.
        // Peer of the [`Caixa::licenca`] (6d5bc28) and
        // [`Caixa::repositorio`] (cc7332d) by-borrow pins on the peer
        // outer top-level [`Caixa`] `Option<&str>`-return axes, and of
        // the per-`:placement`
        // [`crate::aplicacao::Placement::shard_key`] (7cd2a28) by-
        // borrow pin on the peer per-M3-mesh-slot `Option<&str>`-
        // return axis, extended onto the third outer top-level
        // [`Caixa`] universal-axis `Option<&str>` shape — the
        // accessor's returned `&str` must borrow from `&self` (the
        // returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // the same `Option<&str>` verbatim (idempotent, no side
        // effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Option<String>` (which would type-check but silently
        // allocate on every call, breaking the zero-cost projection
        // every peer sibling accessor carries), or a one-arm-only
        // accessor that returned a saturating value on some sentinel
        // input (breaking the pass-through invariant the sibling
        // required-scalar accessors carry).
        for descricao in [
            None,
            Some(""),
            Some("Checkout flow."),
            Some("Canonical Rust→wasm32-wasip2 caixa Servico."),
        ] {
            let c = caixa_with_descricao(descricao);
            let first = c.descricao();
            let second = c.descricao();
            assert_eq!(
                first, second,
                "Caixa::descricao must be idempotent — two successive \
                 calls on the same &self must return the same \
                 Option<&str>",
            );
            assert_eq!(
                first, descricao,
                "Caixa::descricao must return :descricao verbatim by \
                 borrow — got {first:?}, expected {descricao:?}",
            );
        }
    }

    // ── validate_edicao — universal-axis language-edition shape ──

    fn caixa_with_edicao(edicao: Option<&str>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.edicao = edicao.map(String::from);
        c
    }

    #[test]
    fn validate_edicao_accepts_none() {
        // The omit-the-slot identity: `:edicao` is optional. The
        // gate is a no-op when the author didn't declare a value —
        // every caixa without an `:edicao` line trivially passes,
        // and the substrate-side build pipeline falls back to the
        // documented default edition. Mirrors the peer
        // `validate_licenca_accepts_none` posture on the sibling
        // `Option<String>` Caixa slot.
        let c = caixa_with_edicao(None);
        c.validate_edicao().unwrap();
    }

    #[test]
    fn validate_edicao_accepts_canonical_value() {
        // Positive control: the canonical `"2026"` edition every
        // existing renderer-side fixture (`caixa-helm`, `caixa-flux`,
        // `caixa-mesh`) carries by construction passes the gate.
        // Future-introduced sibling editions (`"2027"`, `"2030"`,
        // `"2049"`) that match the same 4-digit ASCII decimal year
        // shape must also trivially pass — the structural shape
        // predicate accepts every well-formed year regardless of
        // whether the substrate yet understands the specific value
        // (a future known-edition allowlist tightens that).
        for ed in ["2026", "2027", "2030", "2049"] {
            let c = caixa_with_edicao(Some(ed));
            c.validate_edicao()
                .unwrap_or_else(|err| panic!("canonical {ed:?} must pass: {err:?}"));
        }
    }

    #[test]
    fn validate_edicao_rejects_empty_some() {
        // Canonical paste-from-blank-doc footgun. Without this gate
        // the empty `Some("")` silently lands as `(:edicao "")` in
        // the rendered caixa.lisp and a future renderer-side
        // consumer's `Option::unwrap_or_else` (which only fires on
        // `None`) skips its fallback. Mirrors the peer
        // [`ManifestError::LicencaEmpty`] empty-arm on the sibling
        // `Option<String>` Caixa slot.
        let c = caixa_with_edicao(Some(""));
        let err = c.validate_edicao().unwrap_err();
        assert!(matches!(err, ManifestError::EdicaoEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_edicao_rejects_free_form_non_year() {
        // Free-form non-year footgun: the bare `"x"` / `"latest"` /
        // `"nightly"` shapes carry no operational meaning on the
        // substrate's build-time edition selector. Until this gate
        // landed the bare empty-arm check let every such value
        // through and broke far from the source caixa.lisp. Peer
        // with the shape-predicate cascade
        // `validate_repositorio_rejects_missing_colon_separator`
        // establishes past its own empty arm.
        for ed in ["x", "latest", "nightly", "stable"] {
            let c = caixa_with_edicao(Some(ed));
            let err = c.validate_edicao().unwrap_err();
            assert!(
                matches!(err, ManifestError::EdicaoInvalid { .. }),
                "expected EdicaoInvalid on {ed:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_edicao_rejects_trailing_whitespace() {
        // Paste-from-doc whitespace footgun. A trailing space in
        // the `:edicao` value would silently break the substrate's
        // build-time edition match-table lookup at the rendered
        // artifact's edition-selector consumer. The shape predicate
        // refuses every whitespace byte by construction (any byte
        // outside `0-9` fails `is_ascii_digit`). Peer with
        // `validate_repositorio_rejects_whitespace`.
        let c = caixa_with_edicao(Some("2026 "));
        let err = c.validate_edicao().unwrap_err();
        let ManifestError::EdicaoInvalid { edicao, .. } = err else {
            panic!("expected EdicaoInvalid, got {err:?}");
        };
        assert_eq!(edicao, "2026 ");
    }

    #[test]
    fn validate_edicao_rejects_leading_whitespace() {
        // Symmetric paste-from-doc whitespace footgun on the leading
        // boundary — the gate refuses every shape with a non-digit
        // byte by construction.
        let c = caixa_with_edicao(Some(" 2026"));
        let err = c.validate_edicao().unwrap_err();
        assert!(
            matches!(err, ManifestError::EdicaoInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_edicao_rejects_control_char() {
        // Paste-from-multiline-doc CRLF footgun — control characters
        // at the value boundary break the substrate's build-time
        // edition-selector parser. Peer with
        // `validate_repositorio_rejects_control_char`.
        let c = caixa_with_edicao(Some("2026\n"));
        let err = c.validate_edicao().unwrap_err();
        assert!(
            matches!(err, ManifestError::EdicaoInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_edicao_rejects_non_ascii_lookalike() {
        // Fullwidth-keyboard look-alike footgun — `"２０２６"` is
        // the U+FF12 U+FF10 U+FF12 U+FF16 sequence (CJK fullwidth
        // digits), 4 codepoints but 12 UTF-8 bytes; the substrate's
        // edition selector wants an ASCII year, and the gate
        // refuses every non-ASCII shape by construction (length in
        // bytes is 12 ≠ 4, *and* every byte falls outside
        // `is_ascii_digit`'s `0-9` range).
        let c = caixa_with_edicao(Some("２０２６"));
        let err = c.validate_edicao().unwrap_err();
        assert!(
            matches!(err, ManifestError::EdicaoInvalid { .. }),
            "got {err:?}",
        );
    }

    #[test]
    fn validate_edicao_rejects_version_tag_prefix() {
        // Common version-tag idiom footgun — `"v2026"` / `"e2026"`
        // / `"r2026"` are familiar shapes from git-tag / Rust
        // edition / release-tag conventions that don't apply to
        // the year-shaped edition axis. The shape predicate refuses
        // every leading non-digit prefix.
        for ed in ["v2026", "e2026", "r2026"] {
            let c = caixa_with_edicao(Some(ed));
            let err = c.validate_edicao().unwrap_err();
            assert!(
                matches!(err, ManifestError::EdicaoInvalid { .. }),
                "expected EdicaoInvalid on {ed:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_edicao_rejects_decimal_shape() {
        // Decimal-shaped pseudo-version footgun — `"2026.1"` /
        // `"2026.0"` are familiar shapes from semver / float
        // conventions that don't apply to the year-shaped edition
        // axis. The shape predicate refuses every non-digit byte
        // (`.` falls outside `is_ascii_digit`).
        for ed in ["2026.1", "2026.0", "2026.0.1"] {
            let c = caixa_with_edicao(Some(ed));
            let err = c.validate_edicao().unwrap_err();
            assert!(
                matches!(err, ManifestError::EdicaoInvalid { .. }),
                "expected EdicaoInvalid on {ed:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_edicao_rejects_wrong_length_numeric() {
        // Wrong-length numeric footgun — `"26"` (truncated) /
        // `"202"` (truncated) / `"20260"` (extra digit) / `"00026"`
        // (zero-padded too wide) all parse as integers but don't
        // name a 4-digit year. The shape predicate refuses every
        // value whose length isn't exactly 4 bytes.
        for ed in ["26", "202", "20260", "00026", "9"] {
            let c = caixa_with_edicao(Some(ed));
            let err = c.validate_edicao().unwrap_err();
            assert!(
                matches!(err, ManifestError::EdicaoInvalid { .. }),
                "expected EdicaoInvalid on {ed:?}, got {err:?}",
            );
        }
    }

    #[test]
    fn validate_edicao_empty_takes_precedence_over_shape() {
        // Empty-first cascade pin: the empty `Some("")` surfaces
        // the narrower `EdicaoEmpty` not the shape-predicate-
        // wrapped `EdicaoInvalid`, mirroring the peer
        // `validate_repositorio_empty_takes_precedence_over_shape`
        // (`RepositorioEmpty` → `RepositorioInvalid`),
        // `NomeEmpty` → `NomeInvalid`, `VersaoEmpty` →
        // `VersaoInvalid`, `FonteRepoEmpty` → `FonteRepoInvalid`
        // cascades. The shape predicate also refuses the empty
        // input (defensively — `s.len() != 4`), but the
        // manifest-layer empty arm runs first to surface the
        // narrower diagnostic verbatim.
        let c = caixa_with_edicao(Some(""));
        let err = c.validate_edicao().unwrap_err();
        assert!(matches!(err, ManifestError::EdicaoEmpty), "got {err:?}",);
    }

    #[test]
    fn validate_edicao_template_passes() {
        // Round-trip pin: the bare `Caixa::template` shape (which
        // carries `:edicao "2026"` verbatim) passes the gate by
        // construction. A future template-shape change that
        // introduced `(:edicao "")` or a non-year value would
        // surface here as a regression. Mirrors the peer
        // `validate_licenca_template_passes` pin.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.validate_edicao().unwrap();
    }

    #[test]
    fn validate_edicao_diagnostic_names_offending_slot() {
        // Diagnostic-shape pin (peer with
        // `validate_licenca_diagnostic_names_offending_slot`): the
        // error's Display surfaces the `:edicao` slot name verbatim,
        // so a `feira lint` run can render the diagnostic without
        // re-parsing and the author can grep their caixa.lisp for
        // the offending `:edicao` line.
        let c = caixa_with_edicao(Some(""));
        let rendered = c.validate_edicao().unwrap_err().to_string();
        assert!(
            rendered.contains(":edicao"),
            "diagnostic must name the offending slot: {rendered}",
        );
    }

    #[test]
    fn validate_edicao_invalid_diagnostic_carries_offending_value() {
        // Diagnostic-shape pin on the shape-predicate arm (peer
        // with `validate_repositorio_diagnostic_carries_offending_value`):
        // the error's Display surfaces the offending value + slot
        // name verbatim, so a `feira lint` run can render the
        // diagnostic without re-parsing and the author can grep
        // their caixa.lisp for the offending `:edicao` value.
        let c = caixa_with_edicao(Some("v2026"));
        let rendered = c.validate_edicao().unwrap_err().to_string();
        assert!(
            rendered.contains(":edicao"),
            "diagnostic must name the offending slot: {rendered}",
        );
        assert!(
            rendered.contains("v2026"),
            "diagnostic must quote the offending value: {rendered}",
        );
    }

    // ── Caixa::edicao — outer top-level Option<&str> scalar accessor ──

    #[test]
    fn edicao_returns_edicao_byte_string_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:edicao` language-edition scalar
        // pin: [`Caixa::edicao`] must return the `:edicao` typed
        // byte-string verbatim as an `Option<&str>`, byte-equal to the
        // raw `self.edicao.as_deref()` access across every representative
        // value in the accept-set — `None` (the "omit the slot to defer
        // to the substrate's default edition" arm every existing
        // [`caixa-resolver`] fixture without an `:edicao` line carries),
        // `Some("")` (a past-the-guard sentinel that pins the accessor
        // doesn't perform a silent `Some("") → None` collapse on the
        // empty arm — validate rejects `Some("")` through `EdicaoEmpty`
        // but the accessor must ship the raw slot verbatim so a
        // validate-time gate regression surfaces at any future edition-
        // aware consumer's boundary rather than being silently absorbed
        // into the substrate's default edition), `Some("2026")` (the
        // canonical 4-digit-ASCII-decimal-year shape every `feira init`
        // template scaffolds via [`Caixa::template`] and every
        // renderer-side fixture at `caixa-helm/src/lib.rs:978` /
        // `caixa-flux/src/lib.rs:2319` / `caixa-mesh/src/lib.rs:3208`
        // carries by construction), `Some("2018")` / `Some("2021")` /
        // `Some("2024")` (canonical 4-digit-ASCII-decimal-year shapes
        // peer with Cargo's `[package] edition` grammar every future-
        // introduced sibling to `"2026"` will follow), and eight
        // past-the-guard sentinels for the `EdicaoInvalid` refusal cases
        // (`Some("2026 ")` trailing-whitespace, `Some(" 2026")` leading-
        // whitespace, `Some("2026\n")` embedded-LF, `Some("２０２６")`
        // fullwidth-non-ASCII-lookalike, `Some("v2026")` version-tag-
        // prefix, `Some("2026.1")` decimal-shape, `Some("26")` wrong-
        // length-numeric, `Some("latest")` free-form-non-year — the
        // sentinels pin the accessor doesn't silently absorb the
        // refusal cases into a substrate-default-edition fallback).
        //
        // Fourth and final outer top-level [`Caixa`] `Option<&str>`-
        // return scalar accessor pin on the substrate primitive —
        // sibling of the peer [`Caixa::licenca`] (6d5bc28),
        // [`Caixa::repositorio`] (cc7332d), and [`Caixa::descricao`]
        // (3f16e2f) pins that opened the "outer [`Caixa`]
        // `Option<&str>` scalar" projection pin pattern this pin folds
        // on. Sibling in shape to the peer per-`:placement`
        // [`crate::aplicacao::Placement::shard_key`] (7cd2a28) /
        // [`crate::aplicacao::Placement::affinity`] (74ec2d3) accessor
        // pins on the sibling per-M3-mesh-slot `Option<&str>`-return
        // axes, extended onto the outer top-level [`Caixa`] universal-
        // axis surface's last unlifted `Option<String>` slot. Pins
        // against a future silent detour that returned an owned
        // `Option<String>` (which would type-check but silently
        // allocate on every accessor call, breaking the zero-cost
        // projection every peer sibling accessor carries), a
        // `Some("") → None` collapse (which would silently absorb the
        // `EdicaoEmpty` refusal case at the accessor boundary and any
        // future edition-aware consumer would silently fall back to
        // the substrate's default edition on a struct-literal
        // `Caixa { edicao: Some(""), .. }`), or a
        // `None → Some("2026")` collapse (which would silently reify
        // the substrate's default edition at the accessor boundary
        // and every downstream consumer keying off the
        // `Option::is_none()` discriminator would lose the "author
        // omitted the slot" signal).
        for edicao in [
            None,
            Some(""),
            Some("2026"),
            Some("2018"),
            Some("2021"),
            Some("2024"),
            Some("2026 "),
            Some(" 2026"),
            Some("2026\n"),
            Some("２０２６"),
            Some("v2026"),
            Some("2026.1"),
            Some("26"),
            Some("latest"),
        ] {
            let c = caixa_with_edicao(edicao);
            assert_eq!(
                c.edicao(),
                edicao,
                "Caixa::edicao must return :edicao verbatim (got {:?}, \
                 expected {edicao:?})",
                c.edicao(),
            );
            assert_eq!(
                c.edicao(),
                c.edicao.as_deref(),
                "Caixa::edicao must byte-equal the raw \
                 `self.edicao.as_deref()` field access across every \
                 value in the Option<&str> accept-set",
            );
        }
    }

    #[test]
    fn validate_edicao_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_edicao`]'s empty-arm gate
        // must key off [`Caixa::edicao`], not the raw
        // `self.edicao.as_deref()` field access. Structurally: a
        // `Caixa { edicao: Some(""), .. }` must surface the
        // `EdicaoEmpty` refusal exactly, and a
        // `Caixa { edicao: Some("2026"), .. }` (the canonical
        // 4-digit-ASCII-decimal-year form) must pass validate. The
        // pair jointly pins the accessor + validate-gate composition:
        // any future silent detour that had the accessor return `None`
        // on the empty arm (a `.filter(|s| !s.is_empty())` collapse)
        // would silently absorb the `EdicaoEmpty` refusal at the
        // accessor boundary and the validate gate would accept a
        // struct-literal `Caixa { edicao: Some(""), .. }` — the
        // composition pin catches that at caixa-core build time.
        //
        // Peer of the [`Caixa::licenca`] (6d5bc28)
        // `validate_licenca_empty_arm_routes_through_accessor`,
        // [`Caixa::repositorio`] (cc7332d)
        // `validate_repositorio_empty_arm_routes_through_accessor`,
        // and [`Caixa::descricao`] (3f16e2f)
        // `validate_descricao_empty_arm_routes_through_accessor`
        // composition pins on the sibling outer top-level [`Caixa`]
        // `Option<&str>` universal-axis surface — same "the validate /
        // shape-gate predicate must route through the substrate-
        // primitive typed dispatch" discipline extended onto the
        // fourth and final outer top-level [`Caixa`] universal-axis
        // `Option<&str>`-composition surface, closing the accessor-
        // composition family.
        let c = caixa_with_edicao(Some(""));
        assert!(
            matches!(c.validate_edicao(), Err(ManifestError::EdicaoEmpty)),
            "validate_edicao must reject edicao == Some(\"\") with \
             EdicaoEmpty — the accessor and the validate gate must \
             route through the same substrate-primitive typed dispatch \
             on the :edicao empty arm",
        );
        let c = caixa_with_edicao(Some("2026"));
        assert!(
            c.validate_edicao().is_ok(),
            "validate_edicao must accept edicao == Some(\"2026\") \
             (the canonical 4-digit-ASCII-decimal-year shape)",
        );
    }

    #[test]
    fn edicao_projects_option_str_by_borrow() {
        // The by-borrow pin: [`Caixa::edicao`] returns
        // `Option<&str>` by borrow — the `&str` borrows the underlying
        // `String` storage of the `Option<String>` slot and the
        // accessor must not allocate a fresh `String` on every call.
        // Peer of the [`Caixa::licenca`] (6d5bc28),
        // [`Caixa::repositorio`] (cc7332d), and [`Caixa::descricao`]
        // (3f16e2f) by-borrow pins on the peer outer top-level
        // [`Caixa`] `Option<&str>`-return axes, and of the
        // per-`:placement`
        // [`crate::aplicacao::Placement::shard_key`] (7cd2a28) by-
        // borrow pin on the peer per-M3-mesh-slot `Option<&str>`-
        // return axis, extended onto the fourth and final outer top-
        // level [`Caixa`] universal-axis `Option<&str>` shape — the
        // accessor's returned `&str` must borrow from `&self` (the
        // returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // the same `Option<&str>` verbatim (idempotent, no side
        // effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Option<String>` (which would type-check but silently
        // allocate on every call, breaking the zero-cost projection
        // every peer sibling accessor carries), or a one-arm-only
        // accessor that returned a saturating value on some sentinel
        // input (breaking the pass-through invariant the sibling
        // required-scalar accessors carry).
        for edicao in [None, Some(""), Some("2026"), Some("2018")] {
            let c = caixa_with_edicao(edicao);
            let first = c.edicao();
            let second = c.edicao();
            assert_eq!(
                first, second,
                "Caixa::edicao must be idempotent — two successive \
                 calls on the same &self must return the same \
                 Option<&str>",
            );
            assert_eq!(
                first, edicao,
                "Caixa::edicao must return :edicao verbatim by \
                 borrow — got {first:?}, expected {edicao:?}",
            );
        }
    }

    #[test]
    fn nome_returns_nome_byte_string_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:nome` universal-axis DNS-1123-
        // label caixa-identity scalar pin: [`Caixa::nome`] must return
        // the `:nome` typed `String` verbatim as `&str`, byte-equal to
        // the raw field access across every representative value in
        // the accept-set — the canonical `"demo"` template baseline
        // (the same `feira init`-scaffolded default the sibling
        // `validate_nome_accepts_canonical_template` positive-control
        // gate pins), plus every sibling per-typed-slot atom accessor's
        // canonical positive-arm byte-string (`"catalog"` per
        // [`crate::aplicacao::Membro::nome`], `"cart"` per the peer
        // per-`:contratos` `:de`, `"hello-rio"` per the canonical
        // `caixa-helm`/`caixa-flux` cross-crate integration-test
        // fixture, `"checkout"` per the M3 mesh-slot Aplicacao
        // canonical example), plus every past-the-guard sentinel for
        // the `NomeEmpty` / `NomeInvalid` / `NomeChartNameBudgetExceeded`
        // refusal cases (`""`, `"Bad_Name"`, `"a"` × 56 — 56 bytes fits
        // the bare DNS-1123 63-byte cap but overflows the joint
        // `lareira-<nome>` chart-name budget the sibling
        // [`Caixa::validate_nome_chart_name_budget`] gate closes on).
        //
        // The past-the-guard sentinels pin the accessor doesn't
        // silently absorb the refusal cases into a template-derived
        // fallback (a future `.nome().is_empty().then(|| "demo")`
        // collapse would silently absorb the `NomeEmpty` refusal at
        // the accessor boundary and the validate gate would accept a
        // struct-literal `Caixa { nome: "".into(), .. }` — the pin
        // catches that at caixa-core build time).
        //
        // First outer top-level [`Caixa`] `&str`-return required-
        // scalar accessor pin — opens the "outer [`Caixa`] `&str`
        // required-scalar" projection pattern the sibling per-`Caixa`
        // `:versao` future lift folds on. Sibling in shape to the peer
        // per-`:membros` [`crate::aplicacao::Membro::nome`] (4a32abf)
        // required-`String`-carry accessor pin on the sibling per-
        // sub-struct required-axis, extended onto the outer top-level
        // [`Caixa`] universal-axis required-`String`-carry axis.
        for nome in [
            "demo",
            "catalog",
            "cart",
            "hello-rio",
            "checkout",
            "",
            "Bad_Name",
            "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
        ] {
            let c = caixa_with_nome(nome);
            assert_eq!(
                c.nome(),
                nome,
                "Caixa::nome must return :nome verbatim (got {}, \
                 expected {nome})",
                c.nome(),
            );
            assert_eq!(
                c.nome(),
                c.nome.as_str(),
                "Caixa::nome must byte-equal the raw .nome field \
                 access across every value in the String accept-set",
            );
        }
    }

    #[test]
    fn validate_nome_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_nome`]'s empty-arm must
        // key off [`Caixa::nome`], not the raw `.nome` field access.
        // Structurally: a `Caixa { nome: "".into(), .. }` must surface
        // the `NomeEmpty` refusal exactly, and the canonical `"demo"`
        // template baseline (the peer positive-arm the sibling
        // `validate_nome_accepts_canonical_template` gate carves out)
        // must pass validate. The pair jointly pins the accessor +
        // validate-gate composition: any future silent detour that
        // had the accessor return a fresh `"demo"` on the empty arm
        // (a `.nome().is_empty().then(|| "demo")` fallback collapse)
        // would silently absorb the `NomeEmpty` refusal at the
        // accessor boundary and the validate gate would accept a
        // struct-literal `Caixa { nome: "".into(), .. }` — the
        // composition pin catches that at caixa-core build time.
        //
        // Peer of the sibling per-`Caixa`
        // `validate_licenca_empty_arm_routes_through_accessor` (6d5bc28)
        // / `validate_repositorio_empty_arm_routes_through_accessor`
        // (cc7332d) / `validate_descricao_empty_arm_routes_through_accessor`
        // (3f16e2f) / `validate_edicao_empty_arm_routes_through_accessor`
        // (2641cbd) composition pins on the sibling outer top-level
        // [`Caixa`] `Option<&str>` axes — same "the validate /
        // shape-gate predicate must route through the substrate-
        // primitive typed dispatch" discipline extended onto the peer
        // outer top-level [`Caixa`] required-`&str` composition axis.
        let c = caixa_with_nome("");
        assert!(
            matches!(c.validate_nome(), Err(ManifestError::NomeEmpty)),
            "validate_nome must reject nome == \"\" with NomeEmpty — \
             the accessor and the validate gate must route through the \
             same substrate-primitive typed dispatch on the :nome \
             empty-arm",
        );
        let c = caixa_with_nome("demo");
        assert!(
            c.validate_nome().is_ok(),
            "validate_nome must accept nome == \"demo\" (the canonical \
             DNS-1123-label template baseline)",
        );
    }

    #[test]
    fn nome_projects_str_by_borrow() {
        // The by-borrow pin: [`Caixa::nome`] returns `&str` by borrow
        // — the `&str` borrows the underlying `String` storage of the
        // required `nome` slot and the accessor must not allocate a
        // fresh `String` on every call. Peer of the [`Caixa::licenca`]
        // (6d5bc28) / [`Caixa::repositorio`] (cc7332d) /
        // [`Caixa::descricao`] (3f16e2f) / [`Caixa::edicao`] (2641cbd)
        // by-borrow pins on the peer outer top-level [`Caixa`]
        // `Option<&str>`-return axes, extended onto the first outer
        // top-level [`Caixa`] required-`&str`-return axis — the
        // accessor's returned `&str` must borrow from `&self` (the
        // returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // the same `&str` verbatim (idempotent, no side effects on
        // `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `String` (which would type-check but silently allocate on
        // every call, breaking the zero-cost projection every peer
        // sibling accessor carries), an accidental
        // `.nome.to_lowercase()` detour that returned a fresh
        // allocation through an already-DNS-1123-lowercase-only
        // string (breaking a future `const fn` regression), or a
        // one-arm-only accessor that returned a canonicalized value
        // on some sentinel input (breaking the pass-through invariant
        // the sibling required-scalar accessors carry).
        for nome in ["demo", "catalog", "hello-rio", "checkout"] {
            let c = caixa_with_nome(nome);
            let first = c.nome();
            let second = c.nome();
            assert_eq!(
                first, second,
                "Caixa::nome must be idempotent — two successive calls \
                 on the same &self must return the same &str",
            );
            assert_eq!(
                first, nome,
                "Caixa::nome must return :nome verbatim by borrow — \
                 got {first}, expected {nome}",
            );
        }
    }

    #[test]
    fn versao_returns_versao_byte_string_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:versao` universal-axis SemVer-2
        // pinned-version scalar pin: [`Caixa::versao`] must return the
        // `:versao` typed `String` verbatim as `&str`, byte-equal to the
        // raw `.versao` field access across every representative value
        // in the accept-set — the canonical `"0.1.0"` template baseline
        // (the same `feira init`-scaffolded default the sibling
        // `validate_versao_accepts_canonical_template` positive-control
        // gate pins), plus every canonical SemVer-2 shape the sibling
        // `validate_versao_accepts_canonical_forms` positive-arm sweep
        // covers (`"0.0.0"`, `"1.0.0"`, `"0.2.0-rc.1"`,
        // `"1.0.0-alpha.0"`, `"1.0.0+build.42"`, `"1.0.0-rc.1+build.42"`,
        // `"10.20.30"`), plus every past-the-guard sentinel for the
        // `VersaoEmpty` / `VersaoInvalid` refusal cases (`""` the empty
        // arm, `"v0.1.0"` the git-tag-shape-leak footgun, `"0.1"` the
        // missing-patch footgun, `"^0.1"` the requirement-shape-leak
        // footgun, `"0.1.0.0"` the four-part-Java-convention footgun,
        // `"latest"` the docker-tag-shape footgun — the sentinels pin
        // the accessor doesn't silently absorb the refusal cases into a
        // template-derived fallback like `"0.1.0"`).
        //
        // The past-the-guard sentinels pin the accessor doesn't silently
        // absorb the refusal cases into a template-derived fallback (a
        // future `.versao().is_empty().then(|| "0.1.0")` collapse would
        // silently absorb the `VersaoEmpty` refusal at the accessor
        // boundary and the validate gate would accept a struct-literal
        // `Caixa { versao: "".into(), .. }` — the pin catches that at
        // caixa-core build time).
        //
        // Second outer top-level [`Caixa`] `&str`-return required-scalar
        // accessor pin — folds on the "outer [`Caixa`] `&str` required-
        // scalar" projection pattern the sibling per-`Caixa`
        // [`Caixa::nome`] (e6b7d97) opened. Sibling in shape to the peer
        // per-`:membros` [`crate::aplicacao::Membro::versao_requirement`]
        // (4127bb6) / per-`:children`
        // [`crate::supervisor::ChildSpec::versao_requirement`] (2c053c8)
        // / per-`:upgrade-from`
        // [`crate::UpgradeFromEntry::prior_versao`] (75d27a8) per-sub-
        // struct `:versao`-shaped `&str`-return accessor pins on the
        // sibling per-typed-slot version-carrier axes, extended onto the
        // second outer top-level [`Caixa`] universal-axis required-
        // `String`-carry axis so the two universal-axis identity-
        // carrying scalars every `defcaixa` form supplies (`:nome` +
        // `:versao`) share the same "one typed dispatch per axis" pin
        // discipline.
        for versao in [
            "0.1.0",
            "0.0.0",
            "1.0.0",
            "0.2.0-rc.1",
            "1.0.0-alpha.0",
            "1.0.0+build.42",
            "1.0.0-rc.1+build.42",
            "10.20.30",
            "",
            "v0.1.0",
            "0.1",
            "^0.1",
            "0.1.0.0",
            "latest",
        ] {
            let c = caixa_with_versao(versao);
            assert_eq!(
                c.versao(),
                versao,
                "Caixa::versao must return :versao verbatim (got {}, \
                 expected {versao})",
                c.versao(),
            );
            assert_eq!(
                c.versao(),
                c.versao.as_str(),
                "Caixa::versao must byte-equal the raw .versao field \
                 access across every value in the String accept-set",
            );
        }
    }

    #[test]
    fn validate_versao_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_versao`]'s empty-arm gate
        // must key off [`Caixa::versao`], not the raw `.versao` field
        // access. Structurally: a `Caixa { versao: "".into(), .. }` must
        // surface the `VersaoEmpty` refusal exactly, and the canonical
        // `"0.1.0"` template baseline (the peer positive-arm the sibling
        // `validate_versao_accepts_canonical_template` gate carves out)
        // must pass validate. The pair jointly pins the accessor +
        // validate-gate composition: any future silent detour that had
        // the accessor return a fresh `"0.1.0"` on the empty arm
        // (a `.versao().is_empty().then(|| "0.1.0")` fallback collapse)
        // would silently absorb the `VersaoEmpty` refusal at the
        // accessor boundary and the validate gate would accept a
        // struct-literal `Caixa { versao: "".into(), .. }` — the
        // composition pin catches that at caixa-core build time.
        //
        // Peer of the sibling per-`Caixa`
        // `validate_nome_empty_arm_routes_through_accessor` (e6b7d97)
        // composition pin on the sibling outer top-level [`Caixa`]
        // required-`&str` universal-axis surface — same "the validate /
        // shape-gate predicate must route through the substrate-
        // primitive typed dispatch" discipline extended onto the peer
        // outer top-level [`Caixa`] required-`&str` universal-axis
        // pinned-version composition axis, closing the second
        // coordinate of the "one canonical typed dispatch per per-Caixa
        // required-`&str` universal-axis" discipline.
        let c = caixa_with_versao("");
        assert!(
            matches!(c.validate_versao(), Err(ManifestError::VersaoEmpty)),
            "validate_versao must reject versao == \"\" with VersaoEmpty — \
             the accessor and the validate gate must route through the \
             same substrate-primitive typed dispatch on the :versao \
             empty-arm",
        );
        let c = caixa_with_versao("0.1.0");
        assert!(
            c.validate_versao().is_ok(),
            "validate_versao must accept versao == \"0.1.0\" (the \
             canonical SemVer-2 template baseline)",
        );
    }

    #[test]
    fn versao_projects_str_by_borrow() {
        // The by-borrow pin: [`Caixa::versao`] returns `&str` by borrow
        // — the `&str` borrows the underlying `String` storage of the
        // required `versao` slot and the accessor must not allocate a
        // fresh `String` on every call. Peer of the [`Caixa::nome`]
        // (e6b7d97) by-borrow pin on the sibling outer top-level
        // [`Caixa`] required-`&str`-return axis, extended onto the
        // second outer top-level [`Caixa`] required-`&str`-return
        // universal-axis pinned-version surface — the accessor's
        // returned `&str` must borrow from `&self` (the returned
        // reference's lifetime is tied to `&self`), and calling the
        // accessor twice on the same [`Caixa`] must yield the same
        // `&str` verbatim (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `String` (which would type-check but silently allocate on
        // every call, breaking the zero-cost projection every peer
        // sibling accessor carries), an accidental
        // `semver::Version::parse(&self.versao).unwrap().to_string()`
        // detour that returned a canonicalized fresh allocation through
        // an already-canonical byte-string (breaking a future `const fn`
        // regression and silently absorbing the `VersaoInvalid` refusal
        // at the accessor boundary), or a one-arm-only accessor that
        // returned a canonicalized value on some sentinel input
        // (breaking the pass-through invariant the sibling required-
        // scalar accessors carry).
        for versao in ["0.1.0", "1.0.0", "0.2.0-rc.1", "1.0.0+build.42"] {
            let c = caixa_with_versao(versao);
            let first = c.versao();
            let second = c.versao();
            assert_eq!(
                first, second,
                "Caixa::versao must be idempotent — two successive \
                 calls on the same &self must return the same &str",
            );
            assert_eq!(
                first, versao,
                "Caixa::versao must return :versao verbatim by borrow \
                 — got {first}, expected {versao}",
            );
        }
    }

    fn caixa_with_kind(kind: CaixaKind) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.kind = kind;
        c
    }

    #[test]
    fn kind_returns_kind_variant_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:kind` universal-axis closed-set-
        // enum discriminant pin: [`Caixa::kind`] must return the `:kind`
        // typed [`CaixaKind`] variant verbatim by `Copy`, byte-equal to
        // the raw `.kind` field access across every variant in the
        // closed accept-set (`Biblioteca` — the library kind that
        // exports lisp forms; `Binario` — the nix-built executable kind
        // under `exe/`; `Servico` — the wasm-component daemon kind
        // under `servicos/`; `Supervisor` — the OTP-shaped hierarchical
        // reconciliation kind; `Aplicacao` — the M3 typed-mesh
        // composition kind).
        //
        // Pins against a future silent detour that re-derived the kind
        // from a peer axis (an accidental fallback to
        // `if !servicos.is_empty() { Servico } else if
        // !membros.is_empty() { Aplicacao } else { Biblioteca }`
        // collapse that read the code-surface / mesh-slot columns into
        // the kind discriminator), a variant remap the operator
        // authors on one consumer without the other, or a stale-derive
        // detour that substituted [`CaixaKind::Biblioteca`] as the
        // default when the field held any other variant (which would
        // silently collapse the distinction between "author explicitly
        // declared `:kind Servico`" and "author declared any other
        // kind" every downstream renderer-dispatch site depends on).
        //
        // First outer top-level [`Caixa`] `Copy`-return required-enum-
        // discriminant accessor pin — opens the "outer [`Caixa`]
        // `Copy`-return required-discriminant" projection pattern.
        // Sibling in shape to the peer per-`:supervisor`
        // [`crate::supervisor::SupervisorSpec::estrategia`] (eafb619),
        // per-`:placement` [`crate::aplicacao::Placement::estrategia`]
        // (921fe1b), and per-`:children`
        // [`crate::supervisor::ChildSpec::restart`] (dfb4a81)
        // `Copy`-return closed-set-enum discriminant accessor pins on
        // the sibling nested-spec typed-slot discriminator axes,
        // extended here to the outer top-level [`Caixa`] universal-
        // axis surface.
        for kind in [
            CaixaKind::Biblioteca,
            CaixaKind::Binario,
            CaixaKind::Servico,
            CaixaKind::Supervisor,
            CaixaKind::Aplicacao,
        ] {
            let c = caixa_with_kind(kind);
            assert_eq!(
                c.kind(),
                kind,
                "Caixa::kind must return :kind verbatim (got {:?}, \
                 expected {kind:?})",
                c.kind(),
            );
            assert_eq!(
                c.kind(),
                c.kind,
                "Caixa::kind accessor and .kind field access must \
                 byte-equal — the accessor is the substrate-primitive \
                 typed dispatch every downstream kind-gate consumer \
                 must route through",
            );
        }
    }

    #[test]
    fn require_kind_reads_through_lifted_kind_accessor() {
        // Two-consumer coherence pin: the [`crate::render::require_kind`]
        // entry-gate predicate (the canonical two-line
        // `require_kind(caixa, Servico)?` prelude every per-Servico /
        // per-Aplicacao renderer runs at its entry-point) and the
        // sibling [`crate::render::KindMismatch`] error carrier's
        // `actual:` field (which names the offending caixa's variant
        // in the diagnostic) must both key off the lifted accessor, so
        // any future rebrand on the typed slot's reader shape lands at
        // exactly one place. Pins the two-site coherence by exercising
        // every off-diagonal `(actual, expected)` pair across the
        // closed accept-set — the `KindMismatch { actual, expected }`
        // surfaced on the mismatch arm must byte-equal the pair the
        // accessor returns for each side.
        //
        // Peer of the sibling per-`:placement`
        // `validate_placement_reads_through_lifted_estrategia_accessor`
        // (921fe1b) two-arm consumer-coherence pin on the M3 mesh-slot
        // `Copy`-return discriminant axis — same "the entry-gate
        // predicate and the error carrier's `actual:` field must route
        // through the substrate-primitive typed dispatch" discipline
        // extended onto the outer top-level [`Caixa`] universal-axis
        // discriminant surface.
        for expected in [
            CaixaKind::Biblioteca,
            CaixaKind::Binario,
            CaixaKind::Servico,
            CaixaKind::Supervisor,
            CaixaKind::Aplicacao,
        ] {
            for actual in [
                CaixaKind::Biblioteca,
                CaixaKind::Binario,
                CaixaKind::Servico,
                CaixaKind::Supervisor,
                CaixaKind::Aplicacao,
            ] {
                let c = caixa_with_kind(actual);
                let result = crate::render::require_kind(&c, expected);
                if expected == actual {
                    assert!(
                        result.is_ok(),
                        "require_kind must accept when actual == expected \
                         (actual={actual:?}, expected={expected:?})",
                    );
                } else {
                    let err = result.expect_err("require_kind must reject when actual != expected");
                    assert_eq!(
                        err.actual,
                        c.kind(),
                        "KindMismatch.actual must byte-equal Caixa::kind() \
                         — the error carrier's `actual:` field reads \
                         through the lifted accessor",
                    );
                    assert_eq!(
                        err.expected, expected,
                        "KindMismatch.expected must byte-equal the \
                         expected variant passed to require_kind",
                    );
                }
            }
        }
    }

    #[test]
    fn aplicacao_view_kind_gate_routes_through_accessor() {
        // Composition pin: [`Caixa::aplicacao_view`]'s kind-gate arm
        // must key off [`Caixa::kind`], not the raw `.kind` field
        // access. Structurally: a `Caixa { kind: X, .. }` for any
        // non-`Aplicacao` variant must fold to `None` on the
        // `aplicacao_view` composer (the "kind mismatch → no typed
        // view" contract every downstream Aplicacao consumer keys off
        // via `?`), and a `Caixa { kind: Aplicacao, .. }` must fold to
        // `Some(_)`. The pair jointly pins the accessor + view-gate
        // composition: any future silent detour that had the accessor
        // return a fresh [`CaixaKind::Aplicacao`] on some sentinel
        // input would silently absorb the kind-mismatch case at the
        // accessor boundary and every per-Aplicacao renderer would
        // silently render a non-Aplicacao caixa's mesh slots — the
        // composition pin catches that at caixa-core build time.
        //
        // Peer of the sibling per-`Caixa`
        // `validate_nome_empty_arm_routes_through_accessor` (e6b7d97) /
        // `validate_versao_empty_arm_routes_through_accessor` (20c0539)
        // composition pins on the sibling outer top-level [`Caixa`]
        // required-`&str` universal-axis surfaces — same "the
        // composer / validate gate must route through the substrate-
        // primitive typed dispatch" discipline extended onto the
        // outer top-level [`Caixa`] `Copy`-return required-
        // discriminant composition axis.
        for kind in [
            CaixaKind::Biblioteca,
            CaixaKind::Binario,
            CaixaKind::Servico,
            CaixaKind::Supervisor,
        ] {
            let c = caixa_with_kind(kind);
            assert!(
                c.aplicacao_view().is_none(),
                "aplicacao_view must return None on non-Aplicacao \
                 kind {kind:?} — the composer's kind-gate must route \
                 through Caixa::kind()",
            );
        }
        let c = caixa_with_kind(CaixaKind::Aplicacao);
        assert!(
            c.aplicacao_view().is_some(),
            "aplicacao_view must return Some on kind Aplicacao — \
             the composer's kind-gate must accept the matching arm \
             through Caixa::kind()",
        );
    }

    #[test]
    fn supervisor_view_kind_gate_routes_through_accessor() {
        // Composition pin (mirror of the sibling
        // `aplicacao_view_kind_gate_routes_through_accessor` on the
        // second `_view` composer): [`Caixa::supervisor_view`]'s kind-
        // gate arm must key off [`Caixa::kind`], not the raw `.kind`
        // field access. A `Caixa { kind: X, .. }` for any non-
        // `Supervisor` variant must fold to `None` on the
        // `supervisor_view` composer, and a `Caixa { kind:
        // Supervisor, .. }` must fold to `Some(_)`. Same peer
        // composition pin discipline on the second `_view` composer
        // axis.
        for kind in [
            CaixaKind::Biblioteca,
            CaixaKind::Binario,
            CaixaKind::Servico,
            CaixaKind::Aplicacao,
        ] {
            let c = caixa_with_kind(kind);
            assert!(
                c.supervisor_view().is_none(),
                "supervisor_view must return None on non-Supervisor \
                 kind {kind:?} — the composer's kind-gate must route \
                 through Caixa::kind()",
            );
        }
        let mut c = caixa_with_kind(CaixaKind::Supervisor);
        // A Supervisor caixa needs a strategy + at least one child to
        // fold to a Some(_) that also validates; the composer itself
        // requires only the kind arm, so bare kind flip is enough to
        // pin the `Some(_)` return, but we populate the minimum
        // supervisor shape so a future strengthening of the composer
        // to reject an empty spec doesn't false-positive this pin.
        c.estrategia = Some(crate::supervisor::RestartStrategy::OneForOne);
        c.children = vec![crate::supervisor::ChildSpec {
            caixa: "child".into(),
            versao: "^0.1".into(),
            restart: crate::supervisor::RestartPolicy::Permanent,
        }];
        assert!(
            c.supervisor_view().is_some(),
            "supervisor_view must return Some on kind Supervisor — \
             the composer's kind-gate must accept the matching arm \
             through Caixa::kind()",
        );
    }

    #[test]
    fn kind_projects_by_copy() {
        // The by-`Copy` pin: [`Caixa::kind`] returns a fresh
        // [`CaixaKind`] by `Copy` — the accessor must not borrow from
        // `&self` (the returned value is owned, `Copy`-projected from
        // the underlying [`CaixaKind`] storage; two calls on the same
        // [`Caixa`] must yield byte-equal values). Peer of the peer
        // per-`:placement` `Placement::estrategia` / per-`:supervisor`
        // `SupervisorSpec::estrategia` / per-`:children`
        // `ChildSpec::restart` `Copy`-return discriminant accessor
        // pins on the sibling nested-spec typed-slot discriminator
        // axes, extended onto the first outer top-level [`Caixa`]
        // required-`Copy`-return axis — pins against a future silent
        // detour that returned `&CaixaKind` (which would type-check
        // but silently constrain every consumer's callsite to a
        // borrow-shaped dispatch, breaking the zero-cost `Copy`
        // projection every peer sibling accessor carries).
        for kind in [
            CaixaKind::Biblioteca,
            CaixaKind::Binario,
            CaixaKind::Servico,
            CaixaKind::Supervisor,
            CaixaKind::Aplicacao,
        ] {
            let c = caixa_with_kind(kind);
            let first: CaixaKind = c.kind();
            let second: CaixaKind = c.kind();
            assert_eq!(
                first, second,
                "Caixa::kind must be idempotent — two successive \
                 calls on the same &self must return the same \
                 CaixaKind variant",
            );
            assert_eq!(
                first, kind,
                "Caixa::kind must return :kind verbatim by Copy — \
                 got {first:?}, expected {kind:?}",
            );
        }
    }

    // ── Caixa::autores — outer top-level &[T] slice accessor ──────────

    #[test]
    fn autores_returns_autores_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:autores` universal-axis maintainer-
        // name-list slice pin: [`Caixa::autores`] must return the
        // `:autores` typed [`Vec<String>`] list verbatim as a
        // `&[String]`, byte-equal to the raw `self.autores.as_slice()`
        // access across every representative value in the accept-set —
        // `[]` (the "no maintainers declared" arm every existing
        // fixture without an `:autores` line carries), `[""]` (a past-
        // the-guard sentinel that pins the accessor doesn't perform a
        // silent `[""] → []` collapse on the empty-entry arm — validate
        // rejects `[""]` through `AutorEmpty` but the accessor must
        // ship the raw slot verbatim so a validate-time gate regression
        // surfaces at the caixa-helm emit boundary rather than being
        // silently absorbed into a maintainer-drop), `["pleme-io"]` (the
        // canonical single-maintainer form every `feira init` template
        // scaffolds), `["alice", "bob"]` (a canonical multi-maintainer
        // form), `["alice <alice@example.com>", "bob <bob@example.com>"]`
        // (the canonical RFC-5322 `<name> <email>` form the
        // `is_chart_maintainer_name_shape` predicate accepts), and
        // `["pleme-io", "pleme-io"]` (a past-the-guard duplicate
        // sentinel — validate rejects through `AutorDuplicate` but the
        // accessor must ship the raw slot verbatim).
        //
        // First outer top-level [`Caixa`] `&[T]`-return slice accessor
        // pin on the substrate primitive — opens the "outer [`Caixa`]
        // `&[T]` slice" projection pattern the sibling per-`Caixa`
        // `:etiquetas` / `:deps` / `:deps-dev` / `:exe` / `:bibliotecas`
        // / `:servicos` / `:upgrade-from` / `:children` future lifts
        // fold on. Sibling in shape to the peer per-`:supervisor`
        // [`crate::supervisor::SupervisorSpec::children`] (bc92bce),
        // per-`:placement` [`crate::aplicacao::Placement::clusters`]
        // (a6e18d7), per-`:membros`
        // [`crate::aplicacao::AplicacaoSpec::membros`] (6c77e36),
        // per-`:contratos` [`crate::aplicacao::AplicacaoSpec::contratos`]
        // (0dcc926), and per-`:upgrade-from :instructions`
        // [`crate::upgrade::UpgradeFromEntry::instructions`] (0137e5a)
        // `&[T]`-return slice accessor pins on the sibling per-M2 /
        // per-M3 typed-slot list axes, extended onto the outer top-
        // level [`Caixa`] universal-axis surface. Pins against a future
        // silent detour that returned an owned `Vec<String>` (which
        // would type-check but silently clone on every accessor call,
        // breaking the zero-cost projection every peer sibling slice
        // accessor carries), a `[""] → []` collapse (which would
        // silently absorb the `AutorEmpty` refusal case at the accessor
        // boundary), or a `["a", "a"] → ["a"]` dedup collapse (which
        // would silently absorb the `AutorDuplicate` refusal case at
        // the accessor boundary and the caixa-helm `maintainers:` fold
        // would silently render a dedupped list on a struct-literal
        // `Caixa { autores: vec!["a".into(), "a".into()], .. }`).
        for autores in [
            vec![],
            vec![""],
            vec!["pleme-io"],
            vec!["alice", "bob"],
            vec!["alice <alice@example.com>", "bob <bob@example.com>"],
            vec!["pleme-io", "pleme-io"],
        ] {
            let c = caixa_with_autores(autores.clone());
            let expected: Vec<String> = autores.iter().map(|s| (*s).to_string()).collect();
            assert_eq!(
                c.autores(),
                expected.as_slice(),
                "Caixa::autores must return :autores verbatim (got {:?}, \
                 expected {expected:?})",
                c.autores(),
            );
            assert_eq!(
                c.autores(),
                c.autores.as_slice(),
                "Caixa::autores must byte-equal the raw \
                 `self.autores.as_slice()` field access across every \
                 value in the Vec<String> accept-set",
            );
        }
    }

    #[test]
    fn validate_autores_empty_entry_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_autores`]'s per-entry
        // empty-arm gate must key off [`Caixa::autores`], not the raw
        // `&self.autores` field-borrow walk. Structurally: a
        // `Caixa { autores: vec!["".into()], .. }` must surface the
        // `AutorEmpty` refusal exactly, and a
        // `Caixa { autores: vec!["pleme-io".into()], .. }` (the
        // canonical single-maintainer form) must pass validate. The
        // pair jointly pins the accessor + validate-gate composition:
        // any future silent detour that had the accessor return an
        // empty slice on the `[""]` arm (a
        // `.iter().filter(|s| !s.is_empty()).collect()` collapse)
        // would silently absorb the `AutorEmpty` refusal at the
        // accessor boundary and the validate gate would accept a
        // struct-literal `Caixa { autores: vec!["".into()], .. }` —
        // the composition pin catches that at caixa-core build time.
        //
        // Peer of the per-`Caixa` [`Caixa::validate_licenca`] (6d5bc28)
        // accessor-composition pin
        // (`validate_licenca_empty_arm_routes_through_accessor`) on the
        // sibling `Option<&str>`-composition axis and the
        // per-`:politicas :circuit-breaker`
        // [`crate::aplicacao::CircuitBreaker::max_failures`] (3a74062)
        // accessor-composition pin
        // (`validate_politicas_max_failures_zero_floor_arm_routes_through_accessor`)
        // on the sibling required-`u32`-composition axis — same "the
        // validate / shape-gate predicate must route through the
        // substrate-primitive typed dispatch" discipline extended onto
        // the outer top-level [`Caixa`] universal-axis `&[T]`-
        // composition surface.
        let c = caixa_with_autores(vec![""]);
        assert!(
            matches!(c.validate_autores(), Err(ManifestError::AutorEmpty)),
            "validate_autores must reject autores == vec![\"\"] with \
             AutorEmpty — the accessor and the validate gate must \
             route through the same substrate-primitive typed dispatch \
             on the :autores per-entry empty arm",
        );
        let c = caixa_with_autores(vec!["pleme-io"]);
        assert!(
            c.validate_autores().is_ok(),
            "validate_autores must accept autores == vec![\"pleme-io\"] \
             (the canonical single-maintainer shape every `feira init` \
             template scaffolds)",
        );
    }

    #[test]
    fn autores_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::autores`] returns `&[String]` by
        // borrow — the returned slice borrows the underlying
        // `Vec<String>` storage of the `:autores` slot and the
        // accessor must not clone the backing `Vec` on every call.
        // Peer of the per-`:membros`
        // [`crate::aplicacao::AplicacaoSpec::membros`] (6c77e36) /
        // per-`:contratos` [`crate::aplicacao::AplicacaoSpec::contratos`]
        // (0dcc926) / per-`:placement`
        // [`crate::aplicacao::Placement::clusters`] (a6e18d7) /
        // per-`:supervisor` [`crate::supervisor::SupervisorSpec::children`]
        // (bc92bce) by-borrow pins on the sibling per-M2 / per-M3
        // typed-slot `&[T]`-return axes, extended onto the outer top-
        // level [`Caixa`] universal-axis `&[String]` shape — the
        // accessor's returned slice must borrow from `&self` (the
        // returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // slices that are pointer-equal (the underlying byte-buffer is
        // the storage `Vec`'s allocation, not a fresh copy) as well as
        // value-equal (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<String>` (which would type-check but silently clone on
        // every call, breaking the zero-cost projection every peer
        // sibling slice accessor carries), a `&Vec<String>` return
        // (which would leak the backing `Vec`'s grow/push/reserve
        // surface no downstream consumer reaches for), or a one-arm-
        // only accessor that returned a saturating value on some
        // sentinel input (breaking the pass-through invariant the
        // sibling slice accessors carry).
        for autores in [
            vec![],
            vec!["pleme-io"],
            vec!["alice", "bob"],
            vec!["pleme-io", "pleme-io"],
        ] {
            let c = caixa_with_autores(autores.clone());
            let expected: Vec<String> = autores.iter().map(|s| (*s).to_string()).collect();
            let first = c.autores();
            let second = c.autores();
            assert_eq!(
                first, second,
                "Caixa::autores must be idempotent — two successive \
                 calls on the same &self must return the same \
                 &[String]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::autores must borrow the underlying Vec<String> \
                 storage — two successive calls must return slices \
                 with the same backing pointer (a fresh Vec<String> \
                 clone would change the pointer on every call)",
            );
            assert_eq!(
                first,
                expected.as_slice(),
                "Caixa::autores must return :autores verbatim by \
                 borrow — got {first:?}, expected {expected:?}",
            );
        }
    }

    // ── Caixa::etiquetas — outer top-level &[T] slice accessor ────────

    #[test]
    fn etiquetas_returns_etiquetas_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:etiquetas` universal-axis
        // registry-search-tag-list slice pin: [`Caixa::etiquetas`] must
        // return the `:etiquetas` typed [`Vec<String>`] list verbatim
        // as a `&[String]`, byte-equal to the raw
        // `self.etiquetas.as_slice()` access across every representative
        // value in the accept-set — `[]` (the "no tags declared" arm
        // every existing fixture without an `:etiquetas` line carries),
        // `[""]` (a past-the-guard sentinel that pins the accessor
        // doesn't perform a silent `[""] → []` collapse on the empty-
        // entry arm — validate rejects `[""]` through `EtiquetaEmpty`
        // but the accessor must ship the raw slot verbatim so a
        // validate-time gate regression surfaces at the caixa-helm emit
        // boundary rather than being silently absorbed into a keyword-
        // drop), `["demo"]` (the canonical single-tag form every
        // `feira init` template scaffolds), `["example", "aplicacao",
        // "mesh", "ecommerce", "demo"]` (the canonical multi-tag form
        // the checkout-aplicacao fixture emits), and `["demo", "demo"]`
        // (a past-the-guard duplicate sentinel — validate rejects
        // through `EtiquetaDuplicate` but the accessor must ship the
        // raw slot verbatim so the caixa-helm `BTreeSet::collect` dedup
        // at chart-render time isn't silently promoted into the
        // accessor boundary and struct-literal
        // `Caixa { etiquetas: vec!["demo".into(), "demo".into()], .. }`
        // fixtures continue to expose the duplicate at the accessor).
        //
        // Second outer top-level [`Caixa`] `&[T]`-return slice accessor
        // pin on the substrate primitive — folds on the "outer
        // [`Caixa`] `&[T]` slice" projection pattern
        // `autores_returns_autores_slice_verbatim_across_permutations`
        // (b5d813f) opened, sibling in shape and idiom. Pins against a
        // future silent detour that returned an owned `Vec<String>`
        // (which would type-check but silently clone on every accessor
        // call, breaking the zero-cost projection every peer sibling
        // slice accessor carries), a `[""] → []` collapse (which would
        // silently absorb the `EtiquetaEmpty` refusal case at the
        // accessor boundary), or a `["a", "a"] → ["a"]` dedup collapse
        // (which would silently absorb the `EtiquetaDuplicate` refusal
        // case at the accessor boundary — the caixa-helm chart-render
        // `BTreeSet::collect` dedup is downstream of the accessor and
        // must not be silently promoted into it).
        for etiquetas in [
            vec![],
            vec![""],
            vec!["demo"],
            vec!["example", "aplicacao", "mesh", "ecommerce", "demo"],
            vec!["demo", "demo"],
        ] {
            let c = caixa_with_etiquetas(etiquetas.clone());
            let expected: Vec<String> = etiquetas.iter().map(|s| (*s).to_string()).collect();
            assert_eq!(
                c.etiquetas(),
                expected.as_slice(),
                "Caixa::etiquetas must return :etiquetas verbatim (got \
                 {:?}, expected {expected:?})",
                c.etiquetas(),
            );
            assert_eq!(
                c.etiquetas(),
                c.etiquetas.as_slice(),
                "Caixa::etiquetas must byte-equal the raw \
                 `self.etiquetas.as_slice()` field access across every \
                 value in the Vec<String> accept-set",
            );
        }
    }

    #[test]
    fn validate_etiquetas_empty_entry_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_etiquetas`]'s per-entry
        // empty-arm gate must key off [`Caixa::etiquetas`], not the raw
        // `&self.etiquetas` field-borrow walk. Structurally: a
        // `Caixa { etiquetas: vec!["".into()], .. }` must surface the
        // `EtiquetaEmpty` refusal exactly, and a
        // `Caixa { etiquetas: vec!["demo".into()], .. }` (the canonical
        // single-tag form) must pass validate. The pair jointly pins
        // the accessor + validate-gate composition: any future silent
        // detour that had the accessor return an empty slice on the
        // `[""]` arm (a
        // `.iter().filter(|s| !s.is_empty()).collect()` collapse) would
        // silently absorb the `EtiquetaEmpty` refusal at the accessor
        // boundary and the validate gate would accept a struct-literal
        // `Caixa { etiquetas: vec!["".into()], .. }` — the composition
        // pin catches that at caixa-core build time.
        //
        // Peer of the per-`Caixa` `validate_autores_empty_arm_routes_
        // through_accessor` (b5d813f) accessor-composition pin on the
        // sibling `&[T]`-composition axis — same "the validate / shape-
        // gate predicate must route through the substrate-primitive
        // typed dispatch" discipline extended onto the sibling outer
        // top-level [`Caixa`] `&[T]`-composition surface.
        let c = caixa_with_etiquetas(vec![""]);
        assert!(
            matches!(c.validate_etiquetas(), Err(ManifestError::EtiquetaEmpty)),
            "validate_etiquetas must reject etiquetas == vec![\"\"] \
             with EtiquetaEmpty — the accessor and the validate gate \
             must route through the same substrate-primitive typed \
             dispatch on the :etiquetas per-entry empty arm",
        );
        let c = caixa_with_etiquetas(vec!["demo"]);
        assert!(
            c.validate_etiquetas().is_ok(),
            "validate_etiquetas must accept etiquetas == vec![\"demo\"] \
             (the canonical single-tag shape every `feira init` \
             template scaffolds)",
        );
    }

    #[test]
    fn etiquetas_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::etiquetas`] returns `&[String]`
        // by borrow — the returned slice borrows the underlying
        // `Vec<String>` storage of the `:etiquetas` slot and the
        // accessor must not clone the backing `Vec` on every call.
        // Peer of the per-`Caixa` `autores_projects_slice_by_borrow`
        // (b5d813f) by-borrow pin on the sibling outer top-level
        // [`Caixa`] `&[String]`-return axis — the accessor's returned
        // slice must borrow from `&self` (the returned reference's
        // lifetime is tied to `&self`), and calling the accessor twice
        // on the same [`Caixa`] must yield slices that are pointer-
        // equal (the underlying byte-buffer is the storage `Vec`'s
        // allocation, not a fresh copy) as well as value-equal
        // (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<String>` (which would type-check but silently clone on
        // every call, breaking the zero-cost projection every peer
        // sibling slice accessor carries), a `&Vec<String>` return
        // (which would leak the backing `Vec`'s grow/push/reserve
        // surface no downstream consumer reaches for), or a one-arm-
        // only accessor that returned a saturating value on some
        // sentinel input (breaking the pass-through invariant the
        // sibling slice accessors carry).
        for etiquetas in [
            vec![],
            vec!["demo"],
            vec!["example", "aplicacao", "mesh"],
            vec!["demo", "demo"],
        ] {
            let c = caixa_with_etiquetas(etiquetas.clone());
            let expected: Vec<String> = etiquetas.iter().map(|s| (*s).to_string()).collect();
            let first = c.etiquetas();
            let second = c.etiquetas();
            assert_eq!(
                first, second,
                "Caixa::etiquetas must be idempotent — two successive \
                 calls on the same &self must return the same \
                 &[String]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::etiquetas must borrow the underlying \
                 Vec<String> storage — two successive calls must \
                 return slices with the same backing pointer (a fresh \
                 Vec<String> clone would change the pointer on every \
                 call)",
            );
            assert_eq!(
                first,
                expected.as_slice(),
                "Caixa::etiquetas must return :etiquetas verbatim by \
                 borrow — got {first:?}, expected {expected:?}",
            );
        }
    }

    // ── Caixa::bibliotecas — outer top-level &[T] slice accessor ──────

    #[test]
    fn bibliotecas_returns_bibliotecas_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:bibliotecas` universal-axis
        // library-source-path-list slice pin: [`Caixa::bibliotecas`]
        // must return the `:bibliotecas` typed [`Vec<String>`] list
        // verbatim as a `&[String]`, byte-equal to the raw
        // `self.bibliotecas.as_slice()` access across every
        // representative value in the accept-set — `[]` (the "no
        // libraries declared" arm every `:kind` other than `Biblioteca`
        // + every `Biblioteca` relying on the canonical
        // `lib/<nome>.lisp` implicit-default path carries; the
        // layout's [`crate::LayoutInvariants`] `MissingLib` arm-gate
        // fires exactly on this empty-slot + `Biblioteca`-kind
        // combination), `[""]` (a past-the-guard sentinel that pins
        // the accessor doesn't perform a silent `[""] → []` collapse
        // on the empty-entry arm — validate rejects `[""]` through
        // `CodePathEmpty { slot: ":bibliotecas" }` but the accessor
        // must ship the raw slot verbatim so a validate-time gate
        // regression surfaces at the `feira build` phase-1 parse
        // boundary rather than being silently absorbed into a
        // library-drop), `["lib/demo.lisp"]` (the canonical single-
        // entry form `Caixa::template` scaffolds and every `feira init`
        // template emits), `["lib/demo.lisp", "lib/helpers.lisp"]`
        // (the canonical multi-library form the
        // `validate_code_paths_accepts_explicit_relative_paths_on_
        // every_slot` fixture emits), and `["lib/foo.lisp",
        // "lib/foo.lisp"]` (a past-the-guard duplicate sentinel —
        // validate rejects through `CodePathDuplicate { slot:
        // ":bibliotecas" }` per the per-slot set-not-multiset gate,
        // but the accessor must ship the raw slot verbatim so the
        // `feira build` `for entry in caixa.bibliotecas()` parse walk
        // sees the duplicate at the accessor boundary and struct-
        // literal `Caixa { bibliotecas: vec!["lib/foo.lisp".into(),
        // "lib/foo.lisp".into()], .. }` fixtures continue to expose
        // the duplicate at the accessor).
        //
        // Third outer top-level [`Caixa`] `&[T]`-return slice accessor
        // pin on the substrate primitive — folds on the "outer
        // [`Caixa`] `&[T]` slice" projection pattern
        // `autores_returns_autores_slice_verbatim_across_permutations`
        // (b5d813f) opened and
        // `etiquetas_returns_etiquetas_slice_verbatim_across_permutations`
        // (78c7d3c) folded on, sibling in shape and idiom. Pins
        // against a future silent detour that returned an owned
        // `Vec<String>` (which would type-check but silently clone on
        // every accessor call, breaking the zero-cost projection
        // every peer sibling slice accessor carries), a `[""] → []`
        // collapse (which would silently absorb the `CodePathEmpty`
        // refusal case at the accessor boundary), or a `["lib/foo.lisp",
        // "lib/foo.lisp"] → ["lib/foo.lisp"]` dedup collapse (which
        // would silently absorb the `CodePathDuplicate` refusal case
        // at the accessor boundary — the per-slot set-not-multiset
        // gate is downstream of the accessor and must not be silently
        // promoted into it).
        for bibliotecas in [
            vec![],
            vec![""],
            vec!["lib/demo.lisp"],
            vec!["lib/demo.lisp", "lib/helpers.lisp"],
            vec!["lib/foo.lisp", "lib/foo.lisp"],
        ] {
            let c = caixa_with_code_paths(bibliotecas.clone(), vec![], vec![]);
            let expected: Vec<String> = bibliotecas.iter().map(|s| (*s).to_string()).collect();
            assert_eq!(
                c.bibliotecas(),
                expected.as_slice(),
                "Caixa::bibliotecas must return :bibliotecas verbatim \
                 (got {:?}, expected {expected:?})",
                c.bibliotecas(),
            );
            assert_eq!(
                c.bibliotecas(),
                c.bibliotecas.as_slice(),
                "Caixa::bibliotecas must byte-equal the raw \
                 `self.bibliotecas.as_slice()` field access across \
                 every value in the Vec<String> accept-set",
            );
        }
    }

    #[test]
    fn validate_code_paths_bibliotecas_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_code_paths`]'s per-entry
        // empty-arm gate on the `:bibliotecas` slot must key off
        // [`Caixa::bibliotecas`], not a divergent raw
        // `&self.bibliotecas` field-borrow walk. Structurally: a
        // `Caixa { bibliotecas: vec!["".into()], .. }` must surface
        // the `CodePathEmpty { slot: ":bibliotecas" }` refusal
        // exactly, and a `Caixa { bibliotecas: vec!["lib/demo.lisp".
        // into()], .. }` (the canonical single-library form
        // `Caixa::template` scaffolds) must pass validate. The pair
        // jointly pins the accessor + validate-gate composition: any
        // future silent detour that had the accessor return an empty
        // slice on the `[""]` arm (a `.iter().filter(|s|
        // !s.is_empty()).collect()` collapse) would silently absorb
        // the `CodePathEmpty` refusal at the accessor boundary and
        // the validate gate would accept a struct-literal
        // `Caixa { bibliotecas: vec!["".into()], .. }` — the
        // composition pin catches that at caixa-core build time.
        //
        // Peer of the per-`Caixa` `validate_autores_empty_arm_routes_
        // through_accessor` (b5d813f) and
        // `validate_etiquetas_empty_entry_arm_routes_through_accessor`
        // (78c7d3c) accessor-composition pins on the sibling `&[T]`-
        // composition axes — same "the validate / shape-gate
        // predicate must route through the substrate-primitive typed
        // dispatch" discipline extended onto the sibling outer top-
        // level [`Caixa`] `&[T]`-composition surface. Nominally the
        // in-tree `validate_code_paths` production body still keys
        // off the internal `[(":bibliotecas", &self.bibliotecas,
        // CodePathFileType::LispSource), (":exe", &self.exe, ..),
        // (":servicos", &self.servicos, ..)]` per-slot dispatch tuple
        // (the tuple's homogeneous slice-typed shape blocks a per-
        // element accessor swap in isolation — a future companion
        // lift for `:exe` and `:servicos` on the same outer-`Caixa`
        // `&[T]` slice-accessor axis closes that tuple onto the
        // triple of typed dispatches as a unit); the composition pin
        // catches any future accessor-side silent filter drop against
        // that eventual tuple-closure regardless of whether the
        // `:bibliotecas` slot is threaded through the accessor or the
        // raw field access at the tuple's construction site.
        let c = caixa_with_code_paths(vec![""], vec![], vec![]);
        assert!(
            matches!(
                c.validate_code_paths(),
                Err(ManifestError::CodePathEmpty {
                    slot: ":bibliotecas"
                })
            ),
            "validate_code_paths must reject bibliotecas == vec![\"\"] \
             with CodePathEmpty {{ slot: \":bibliotecas\" }} — the \
             accessor and the validate gate must route through the \
             same substrate-primitive typed dispatch on the \
             :bibliotecas per-entry empty arm",
        );
        let c = caixa_with_code_paths(vec!["lib/demo.lisp"], vec![], vec![]);
        assert!(
            c.validate_code_paths().is_ok(),
            "validate_code_paths must accept bibliotecas == \
             vec![\"lib/demo.lisp\"] (the canonical single-library \
             shape every `feira init` template scaffolds)",
        );
    }

    #[test]
    fn bibliotecas_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::bibliotecas`] returns
        // `&[String]` by borrow — the returned slice borrows the
        // underlying `Vec<String>` storage of the `:bibliotecas` slot
        // and the accessor must not clone the backing `Vec` on every
        // call. Peer of the per-`Caixa` `autores_projects_slice_by_borrow`
        // (b5d813f) and `etiquetas_projects_slice_by_borrow` (78c7d3c)
        // by-borrow pins on the sibling outer top-level [`Caixa`]
        // `&[String]`-return axes — the accessor's returned slice
        // must borrow from `&self` (the returned reference's lifetime
        // is tied to `&self`), and calling the accessor twice on the
        // same [`Caixa`] must yield slices that are pointer-equal
        // (the underlying byte-buffer is the storage `Vec`'s
        // allocation, not a fresh copy) as well as value-equal
        // (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<String>` (which would type-check but silently clone on
        // every call, breaking the zero-cost projection every peer
        // sibling slice accessor carries), a `&Vec<String>` return
        // (which would leak the backing `Vec`'s grow/push/reserve
        // surface no downstream consumer reaches for), or a one-arm-
        // only accessor that returned a saturating value on some
        // sentinel input (breaking the pass-through invariant the
        // sibling slice accessors carry).
        for bibliotecas in [
            vec![],
            vec!["lib/demo.lisp"],
            vec!["lib/demo.lisp", "lib/helpers.lisp"],
            vec!["lib/foo.lisp", "lib/foo.lisp"],
        ] {
            let c = caixa_with_code_paths(bibliotecas.clone(), vec![], vec![]);
            let expected: Vec<String> = bibliotecas.iter().map(|s| (*s).to_string()).collect();
            let first = c.bibliotecas();
            let second = c.bibliotecas();
            assert_eq!(
                first, second,
                "Caixa::bibliotecas must be idempotent — two \
                 successive calls on the same &self must return the \
                 same &[String]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::bibliotecas must borrow the underlying \
                 Vec<String> storage — two successive calls must \
                 return slices with the same backing pointer (a \
                 fresh Vec<String> clone would change the pointer on \
                 every call)",
            );
            assert_eq!(
                first,
                expected.as_slice(),
                "Caixa::bibliotecas must return :bibliotecas verbatim \
                 by borrow — got {first:?}, expected {expected:?}",
            );
        }
    }

    // ── Caixa::exe — outer top-level &[T] slice accessor ──────────────

    #[test]
    fn exe_returns_exe_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:exe` universal-axis
        // nix-built-executable-entry-path-list slice pin: [`Caixa::exe`]
        // must return the `:exe` typed [`Vec<String>`] list verbatim as
        // a `&[String]`, byte-equal to the raw `self.exe.as_slice()`
        // access across every representative value in the accept-set —
        // `[]` (the "no executable declared" arm every `:kind` other
        // than `Binario` carries; the layout's [`crate::LayoutInvariants`]
        // `BinarioWithoutExe` arm-gate fires exactly on this empty-slot
        // + `Binario`-kind combination), `[""]` (a past-the-guard
        // sentinel that pins the accessor doesn't perform a silent
        // `[""] → []` collapse on the empty-entry arm — validate rejects
        // `[""]` through `CodePathEmpty { slot: ":exe" }` but the
        // accessor must ship the raw slot verbatim so a validate-time
        // gate regression surfaces at the layout / `feira nix` boundary
        // rather than being silently absorbed into an executable-drop),
        // `["exe/cli"]` (the canonical single-entry Binario form every
        // in-tree `caixa_with_code_paths` positive control uses),
        // `["exe/cli", "exe/serve"]` (the canonical multi-executable
        // form the `validate_code_paths_accepts_explicit_relative_paths_
        // on_every_slot` fixture emits), and `["exe/cli", "exe/cli"]`
        // (a past-the-guard duplicate sentinel — validate rejects
        // through `CodePathDuplicate { slot: ":exe" }` per the per-slot
        // set-not-multiset gate, but the accessor must ship the raw
        // slot verbatim so struct-literal `Caixa { exe: vec!["exe/cli".
        // into(), "exe/cli".into()], .. }` fixtures continue to expose
        // the duplicate at the accessor).
        //
        // Fourth outer top-level [`Caixa`] `&[T]`-return slice accessor
        // pin on the substrate primitive — folds on the "outer
        // [`Caixa`] `&[T]` slice" projection pattern
        // `autores_returns_autores_slice_verbatim_across_permutations`
        // (b5d813f) opened,
        // `etiquetas_returns_etiquetas_slice_verbatim_across_permutations`
        // (78c7d3c) folded on, and
        // `bibliotecas_returns_bibliotecas_slice_verbatim_across_permutations`
        // (8a36c23) closed the universal-axis text-tag family of.
        // Opens the outer-`Caixa` foreign-code-slot `&[T]` sub-family
        // the sibling `:servicos` future lift closes onto. Pins against
        // a future silent detour that returned an owned `Vec<String>`
        // (which would type-check but silently clone on every accessor
        // call, breaking the zero-cost projection every peer sibling
        // slice accessor carries), a `[""] → []` collapse (which would
        // silently absorb the `CodePathEmpty` refusal case at the
        // accessor boundary), or an `["exe/cli", "exe/cli"] →
        // ["exe/cli"]` dedup collapse (which would silently absorb the
        // `CodePathDuplicate` refusal case at the accessor boundary —
        // the per-slot set-not-multiset gate is downstream of the
        // accessor and must not be silently promoted into it).
        for exe in [
            vec![],
            vec![""],
            vec!["exe/cli"],
            vec!["exe/cli", "exe/serve"],
            vec!["exe/cli", "exe/cli"],
        ] {
            let c = caixa_with_code_paths(vec![], exe.clone(), vec![]);
            let expected: Vec<String> = exe.iter().map(|s| (*s).to_string()).collect();
            assert_eq!(
                c.exe(),
                expected.as_slice(),
                "Caixa::exe must return :exe verbatim (got {:?}, \
                 expected {expected:?})",
                c.exe(),
            );
            assert_eq!(
                c.exe(),
                c.exe.as_slice(),
                "Caixa::exe must byte-equal the raw \
                 `self.exe.as_slice()` field access across every value \
                 in the Vec<String> accept-set",
            );
        }
    }

    #[test]
    fn validate_code_paths_exe_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_code_paths`]'s per-entry
        // empty-arm gate on the `:exe` slot must key off
        // [`Caixa::exe`], not a divergent raw `&self.exe` field-borrow
        // walk. Structurally: a `Caixa { exe: vec!["".into()], .. }`
        // must surface the `CodePathEmpty { slot: ":exe" }` refusal
        // exactly, and a `Caixa { exe: vec!["exe/cli".into()], .. }`
        // (the canonical single-executable form every in-tree
        // `caixa_with_code_paths` positive control uses) must pass
        // validate. The pair jointly pins the accessor + validate-gate
        // composition: any future silent detour that had the accessor
        // return an empty slice on the `[""]` arm (a
        // `.iter().filter(|s| !s.is_empty()).collect()` collapse) would
        // silently absorb the `CodePathEmpty` refusal at the accessor
        // boundary and the validate gate would accept a struct-literal
        // `Caixa { exe: vec!["".into()], .. }` — the composition pin
        // catches that at caixa-core build time.
        //
        // Peer of the per-`Caixa`
        // `validate_code_paths_bibliotecas_empty_arm_routes_through_accessor`
        // (8a36c23), `validate_autores_empty_arm_routes_through_accessor`
        // (b5d813f), and
        // `validate_etiquetas_empty_entry_arm_routes_through_accessor`
        // (78c7d3c) accessor-composition pins on the sibling `&[T]`-
        // composition axes — same "the validate / shape-gate predicate
        // must route through the substrate-primitive typed dispatch"
        // discipline extended onto the sibling outer top-level [`Caixa`]
        // `&[T]`-composition surface. Nominally the in-tree
        // `validate_code_paths` production body still keys off the
        // internal `[(":bibliotecas", &self.bibliotecas,
        // CodePathFileType::LispSource), (":exe", &self.exe, ..),
        // (":servicos", &self.servicos, ..)]` per-slot dispatch tuple
        // (the tuple's homogeneous slice-typed shape blocks a per-
        // element accessor swap in isolation — a future companion lift
        // for `:servicos` on the same outer-`Caixa` `&[T]` slice-
        // accessor axis closes that tuple onto the triple of typed
        // dispatches as a unit); the composition pin catches any future
        // accessor-side silent filter drop against that eventual tuple-
        // closure regardless of whether the `:exe` slot is threaded
        // through the accessor or the raw field access at the tuple's
        // construction site.
        let c = caixa_with_code_paths(vec![], vec![""], vec![]);
        assert!(
            matches!(
                c.validate_code_paths(),
                Err(ManifestError::CodePathEmpty { slot: ":exe" })
            ),
            "validate_code_paths must reject exe == vec![\"\"] \
             with CodePathEmpty {{ slot: \":exe\" }} — the \
             accessor and the validate gate must route through the \
             same substrate-primitive typed dispatch on the \
             :exe per-entry empty arm",
        );
        let c = caixa_with_code_paths(vec![], vec!["exe/cli"], vec![]);
        assert!(
            c.validate_code_paths().is_ok(),
            "validate_code_paths must accept exe == vec![\"exe/cli\"] \
             (the canonical single-executable shape every in-tree \
             `caixa_with_code_paths` positive control uses)",
        );
    }

    #[test]
    fn exe_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::exe`] returns `&[String]` by
        // borrow — the returned slice borrows the underlying
        // `Vec<String>` storage of the `:exe` slot and the accessor
        // must not clone the backing `Vec` on every call. Peer of the
        // per-`Caixa` `autores_projects_slice_by_borrow` (b5d813f),
        // `etiquetas_projects_slice_by_borrow` (78c7d3c), and
        // `bibliotecas_projects_slice_by_borrow` (8a36c23) by-borrow
        // pins on the sibling outer top-level [`Caixa`] `&[String]`-
        // return axes — the accessor's returned slice must borrow from
        // `&self` (the returned reference's lifetime is tied to
        // `&self`), and calling the accessor twice on the same
        // [`Caixa`] must yield slices that are pointer-equal (the
        // underlying byte-buffer is the storage `Vec`'s allocation,
        // not a fresh copy) as well as value-equal (idempotent, no
        // side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<String>` (which would type-check but silently clone on
        // every call, breaking the zero-cost projection every peer
        // sibling slice accessor carries), a `&Vec<String>` return
        // (which would leak the backing `Vec`'s grow/push/reserve
        // surface no downstream consumer reaches for), or a one-arm-
        // only accessor that returned a saturating value on some
        // sentinel input (breaking the pass-through invariant the
        // sibling slice accessors carry).
        for exe in [
            vec![],
            vec!["exe/cli"],
            vec!["exe/cli", "exe/serve"],
            vec!["exe/cli", "exe/cli"],
        ] {
            let c = caixa_with_code_paths(vec![], exe.clone(), vec![]);
            let expected: Vec<String> = exe.iter().map(|s| (*s).to_string()).collect();
            let first = c.exe();
            let second = c.exe();
            assert_eq!(
                first, second,
                "Caixa::exe must be idempotent — two successive calls \
                 on the same &self must return the same &[String]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::exe must borrow the underlying Vec<String> \
                 storage — two successive calls must return slices \
                 with the same backing pointer (a fresh Vec<String> \
                 clone would change the pointer on every call)",
            );
            assert_eq!(
                first,
                expected.as_slice(),
                "Caixa::exe must return :exe verbatim by borrow — \
                 got {first:?}, expected {expected:?}",
            );
        }
    }

    // ── Caixa::servicos — outer top-level &[T] slice accessor ─────────

    #[test]
    fn servicos_returns_servicos_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:servicos` universal-axis
        // ComputeUnit-CR-YAML-entry-path-list slice pin:
        // [`Caixa::servicos`] must return the `:servicos` typed
        // [`Vec<String>`] list verbatim as a `&[String]`, byte-equal to
        // the raw `self.servicos.as_slice()` access across every
        // representative value in the accept-set — `[]` (the "no
        // ComputeUnit-CR declared" arm every `:kind` other than
        // `Servico` carries; the layout's [`crate::LayoutInvariants`]
        // `ServicoWithoutServicos` arm-gate fires exactly on this
        // empty-slot + `Servico`-kind combination), `[""]` (a past-the-
        // guard sentinel that pins the accessor doesn't perform a
        // silent `[""] → []` collapse on the empty-entry arm — validate
        // rejects `[""]` through `CodePathEmpty { slot: ":servicos" }`
        // but the accessor must ship the raw slot verbatim so a
        // validate-time gate regression surfaces at the layout /
        // per-Servico renderer boundary rather than being silently
        // absorbed into a component-drop),
        // `["servicos/demo.computeunit.yaml"]` (the canonical
        // singleton V0-shape every in-tree `caixa_with_code_paths`
        // positive control uses; the same shape
        // [`crate::require_single_servico`] admits),
        // `["servicos/a.computeunit.yaml", "servicos/b.computeunit.
        // yaml"]` (a past-the-guard `len != 1` sentinel — the V0
        // singularity gate rejects through `ServicoCountMismatch
        // { count: 2 }` but the accessor must ship the raw slot
        // verbatim so struct-literal `Caixa { servicos: vec![...,
        // ...], .. }` fixtures continue to expose the count at the
        // accessor), and `["servicos/a.computeunit.yaml",
        // "servicos/a.computeunit.yaml"]` (a past-the-guard duplicate
        // sentinel — validate rejects through
        // `CodePathDuplicate { slot: ":servicos" }` per the per-slot
        // set-not-multiset gate, but the accessor must ship the raw
        // slot verbatim so struct-literal fixtures continue to expose
        // the duplicate at the accessor).
        //
        // Fifth and final outer top-level [`Caixa`] `&[T]`-return
        // slice accessor pin on the substrate primitive — folds on the
        // "outer [`Caixa`] `&[T]` slice" projection pattern
        // `autores_returns_autores_slice_verbatim_across_permutations`
        // (b5d813f) opened,
        // `etiquetas_returns_etiquetas_slice_verbatim_across_permutations`
        // (78c7d3c) folded on,
        // `bibliotecas_returns_bibliotecas_slice_verbatim_across_permutations`
        // (8a36c23) closed the universal-axis text-tag family of, and
        // `exe_returns_exe_slice_verbatim_across_permutations`
        // (65d9527) opened the foreign-code-slot sub-family of. Closes
        // the outer-`Caixa` foreign-code-slot `&[T]` sub-family — the
        // trio of code-surface list slots (`:bibliotecas` + `:exe` +
        // `:servicos`) now each carries a substrate-canonical slice
        // accessor. Pins against a future silent detour that returned
        // an owned `Vec<String>` (which would type-check but silently
        // clone on every accessor call, breaking the zero-cost
        // projection every peer sibling slice accessor carries), a
        // `[""] → []` collapse (which would silently absorb the
        // `CodePathEmpty` refusal case at the accessor boundary), an
        // `[a, a] → [a]` dedup collapse (which would silently absorb
        // the `CodePathDuplicate` refusal case at the accessor
        // boundary — the per-slot set-not-multiset gate is downstream
        // of the accessor and must not be silently promoted into it),
        // or a `[a, b] → [a]` singleton collapse (which would silently
        // absorb the V0 `ServicoCountMismatch` refusal case at the
        // accessor boundary — the V0 singularity gate is downstream of
        // the accessor and must not be silently promoted into it).
        for servicos in [
            vec![],
            vec![""],
            vec!["servicos/demo.computeunit.yaml"],
            vec!["servicos/a.computeunit.yaml", "servicos/b.computeunit.yaml"],
            vec!["servicos/a.computeunit.yaml", "servicos/a.computeunit.yaml"],
        ] {
            let c = caixa_with_code_paths(vec![], vec![], servicos.clone());
            let expected: Vec<String> = servicos.iter().map(|s| (*s).to_string()).collect();
            assert_eq!(
                c.servicos(),
                expected.as_slice(),
                "Caixa::servicos must return :servicos verbatim (got \
                 {:?}, expected {expected:?})",
                c.servicos(),
            );
            assert_eq!(
                c.servicos(),
                c.servicos.as_slice(),
                "Caixa::servicos must byte-equal the raw \
                 `self.servicos.as_slice()` field access across every \
                 value in the Vec<String> accept-set",
            );
        }
    }

    #[test]
    fn validate_code_paths_servicos_empty_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_code_paths`]'s per-entry
        // empty-arm gate on the `:servicos` slot must key off
        // [`Caixa::servicos`], not a divergent raw `&self.servicos`
        // field-borrow walk. Structurally: a `Caixa { servicos:
        // vec!["".into()], .. }` must surface the `CodePathEmpty
        // { slot: ":servicos" }` refusal exactly, and a `Caixa
        // { servicos: vec!["servicos/demo.computeunit.yaml".into()],
        // .. }` (the canonical singleton V0-shape every in-tree
        // `caixa_with_code_paths` positive control uses) must pass
        // validate. The pair jointly pins the accessor + validate-gate
        // composition: any future silent detour that had the accessor
        // return an empty slice on the `[""]` arm (a `.iter().filter
        // (|s| !s.is_empty()).collect()` collapse) would silently
        // absorb the `CodePathEmpty` refusal at the accessor boundary
        // and the validate gate would accept a struct-literal
        // `Caixa { servicos: vec!["".into()], .. }` — the composition
        // pin catches that at caixa-core build time.
        //
        // Peer of the per-`Caixa`
        // `validate_code_paths_bibliotecas_empty_arm_routes_through_accessor`
        // (8a36c23), `validate_code_paths_exe_empty_arm_routes_through_accessor`
        // (65d9527), `validate_autores_empty_arm_routes_through_accessor`
        // (b5d813f), and
        // `validate_etiquetas_empty_entry_arm_routes_through_accessor`
        // (78c7d3c) accessor-composition pins on the sibling `&[T]`-
        // composition axes — same "the validate / shape-gate predicate
        // must route through the substrate-primitive typed dispatch"
        // discipline extended onto the sibling outer top-level
        // [`Caixa`] `&[T]`-composition surface, closing the trio of
        // code-surface accessor-composition pins on the same axis.
        // Nominally the in-tree `validate_code_paths` production body
        // still keys off the internal
        // `[(":bibliotecas", &self.bibliotecas,
        // CodePathFileType::LispSource), (":exe", &self.exe, ..),
        // (":servicos", &self.servicos, ..)]` per-slot dispatch tuple
        // (the tuple's homogeneous `&Vec<String>`-typed shape blocks a
        // per-element accessor swap in isolation — a future companion
        // lift promotes the tuple's element type to `&[String]` and
        // threads the triple of typed dispatches through as a unit);
        // the composition pin catches any future accessor-side silent
        // filter drop against that eventual tuple-closure regardless
        // of whether the `:servicos` slot is threaded through the
        // accessor or the raw field access at the tuple's construction
        // site.
        let c = caixa_with_code_paths(vec![], vec![], vec![""]);
        assert!(
            matches!(
                c.validate_code_paths(),
                Err(ManifestError::CodePathEmpty { slot: ":servicos" })
            ),
            "validate_code_paths must reject servicos == vec![\"\"] \
             with CodePathEmpty {{ slot: \":servicos\" }} — the \
             accessor and the validate gate must route through the \
             same substrate-primitive typed dispatch on the \
             :servicos per-entry empty arm",
        );
        let c = caixa_with_code_paths(vec![], vec![], vec!["servicos/demo.computeunit.yaml"]);
        assert!(
            c.validate_code_paths().is_ok(),
            "validate_code_paths must accept servicos == \
             vec![\"servicos/demo.computeunit.yaml\"] (the canonical \
             singleton V0-shape every in-tree `caixa_with_code_paths` \
             positive control uses)",
        );
    }

    #[test]
    fn servicos_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::servicos`] returns `&[String]` by
        // borrow — the returned slice borrows the underlying
        // `Vec<String>` storage of the `:servicos` slot and the
        // accessor must not clone the backing `Vec` on every call.
        // Peer of the per-`Caixa` `autores_projects_slice_by_borrow`
        // (b5d813f), `etiquetas_projects_slice_by_borrow` (78c7d3c),
        // `bibliotecas_projects_slice_by_borrow` (8a36c23), and
        // `exe_projects_slice_by_borrow` (65d9527) by-borrow pins on
        // the sibling outer top-level [`Caixa`] `&[String]`-return
        // axes — the accessor's returned slice must borrow from
        // `&self` (the returned reference's lifetime is tied to
        // `&self`), and calling the accessor twice on the same
        // [`Caixa`] must yield slices that are pointer-equal (the
        // underlying byte-buffer is the storage `Vec`'s allocation,
        // not a fresh copy) as well as value-equal (idempotent, no
        // side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<String>` (which would type-check but silently clone on
        // every call, breaking the zero-cost projection every peer
        // sibling slice accessor carries), a `&Vec<String>` return
        // (which would leak the backing `Vec`'s grow/push/reserve
        // surface no downstream consumer reaches for), or a one-arm-
        // only accessor that returned a saturating value on some
        // sentinel input (breaking the pass-through invariant the
        // sibling slice accessors carry).
        for servicos in [
            vec![],
            vec!["servicos/demo.computeunit.yaml"],
            vec!["servicos/a.computeunit.yaml", "servicos/b.computeunit.yaml"],
            vec!["servicos/a.computeunit.yaml", "servicos/a.computeunit.yaml"],
        ] {
            let c = caixa_with_code_paths(vec![], vec![], servicos.clone());
            let expected: Vec<String> = servicos.iter().map(|s| (*s).to_string()).collect();
            let first = c.servicos();
            let second = c.servicos();
            assert_eq!(
                first, second,
                "Caixa::servicos must be idempotent — two successive \
                 calls on the same &self must return the same &[String]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::servicos must borrow the underlying \
                 Vec<String> storage — two successive calls must \
                 return slices with the same backing pointer (a fresh \
                 Vec<String> clone would change the pointer on every \
                 call)",
            );
            assert_eq!(
                first,
                expected.as_slice(),
                "Caixa::servicos must return :servicos verbatim by \
                 borrow — got {first:?}, expected {expected:?}",
            );
        }
    }

    // ── Caixa::deps — outer top-level &[Dep] slice accessor ───────────

    fn caixa_with_deps(deps: Vec<Dep>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = deps;
        c
    }

    #[test]
    fn deps_returns_deps_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:deps` universal-axis runtime-
        // dependency-declaration-list slice pin: [`Caixa::deps`] must
        // return the `:deps` typed [`Vec<Dep>`] list verbatim as a
        // `&[Dep]`, element-equal to the raw `self.deps.as_slice()`
        // access across every representative value in the accept-set —
        // `[]` (the "no runtime deps declared" arm every existing
        // fixture without a `:deps` line carries; the
        // [`Caixa::template`] scaffold emits `:deps ()`), a canonical
        // single-entry list (the shape most consumer caixas carry), a
        // canonical two-entry list (the multi-dep runtime closure), and
        // two past-the-guard sentinels — a `[""]`-`:nome` entry
        // ([`Self::validate_deps`] rejects through `NomeEmpty` /
        // `NomeInvalid` but the accessor must ship the raw slot
        // verbatim) and a `[a, a]` duplicate (validate rejects through
        // `DuplicateNome { list: ":deps" }` but the accessor must ship
        // the raw slot verbatim so struct-literal fixtures continue to
        // expose the duplicate at the accessor).
        //
        // First outer top-level [`Caixa`] `&[Dep]`-return slice accessor
        // pin on the substrate primitive — opens the outer-`Caixa`
        // dependency-slot `&[Dep]` sub-family the sibling `:deps-dev`
        // future lift closes on. Peer of the closed outer-`Caixa`
        // foreign-code-slot `&[String]` sub-family
        // (`bibliotecas_returns_bibliotecas_slice_verbatim_across_permutations`
        // 8a36c23, `exe_returns_exe_slice_verbatim_across_permutations`
        // 65d9527, `servicos_returns_servicos_slice_verbatim_across_permutations`
        // 611f78b) and the outer-`Caixa` universal-axis text-tag family
        // (`autores_returns_autores_slice_verbatim_across_permutations`
        // b5d813f, `etiquetas_returns_etiquetas_slice_verbatim_across_permutations`
        // 78c7d3c) — extends the "outer [`Caixa`] `&[T]` slice"
        // projection pattern onto a novel element-type axis (`Dep`
        // composite vs the prior sibling family's `String` scalar).
        // Pins against a future silent detour that returned an owned
        // `Vec<Dep>` (which would type-check but silently clone on every
        // accessor call, breaking the zero-cost projection every peer
        // sibling slice accessor carries), a `[""] → []` collapse (which
        // would silently absorb the `NomeEmpty` refusal case at the
        // accessor boundary), or a `[a, a] → [a]` dedup collapse (which
        // would silently absorb the `DuplicateNome` refusal case at the
        // accessor boundary).
        for deps in [
            vec![],
            vec![Dep::simple("", "^0.1")],
            vec![Dep::simple("caixa-teia", "^0.1")],
            vec![
                Dep::simple("caixa-teia", "^0.1"),
                Dep::simple("caixa-core", "^0.1"),
            ],
            vec![
                Dep::simple("caixa-teia", "^0.1"),
                Dep::simple("caixa-teia", "^0.2"),
            ],
        ] {
            let c = caixa_with_deps(deps.clone());
            assert_eq!(
                c.deps(),
                deps.as_slice(),
                "Caixa::deps must return :deps verbatim (got {:?}, \
                 expected {deps:?})",
                c.deps(),
            );
            assert_eq!(
                c.deps(),
                c.deps.as_slice(),
                "Caixa::deps must element-equal the raw \
                 `self.deps.as_slice()` field access across every \
                 value in the Vec<Dep> accept-set",
            );
        }
    }

    #[test]
    fn validate_deps_duplicate_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_deps`]'s within-`:deps`
        // duplicate-`:nome` gate must key off [`Caixa::deps`], not the
        // raw `&self.deps` field-borrow walk. Structurally: a `Caixa
        // { deps: vec![Dep::simple("d", "^0.1"), Dep::simple("d",
        // "^0.2")], .. }` must surface the `DuplicateNome { list:
        // ":deps" }` refusal exactly, and a `Caixa { deps: vec![
        // Dep::simple("d", "^0.1")], .. }` (the canonical single-entry
        // form) must pass validate. The pair jointly pins the accessor +
        // validate-gate composition: any future silent detour that had
        // the accessor return a dedupped slice on the `[a, a]` arm (a
        // `.iter().unique_by(|d| d.nome.as_str()).collect()` collapse)
        // would silently absorb the `DuplicateNome` refusal at the
        // accessor boundary and the validate gate would accept a
        // struct-literal `Caixa` carrying the drift — the composition
        // pin catches that at caixa-core build time.
        //
        // Peer of the per-`Caixa`
        // `validate_autores_empty_entry_arm_routes_through_accessor`
        // (b5d813f), `validate_etiquetas_empty_entry_arm_routes_through_accessor`
        // (78c7d3c), `validate_code_paths_bibliotecas_empty_arm_routes_through_accessor`
        // (8a36c23), `validate_code_paths_exe_empty_arm_routes_through_accessor`
        // (65d9527), and `validate_code_paths_servicos_empty_arm_routes_through_accessor`
        // (611f78b) accessor-composition pins on the sibling `&[T]`-
        // composition axes — same "the validate gate must route through
        // the substrate-primitive typed dispatch" discipline extended
        // onto the sibling outer top-level [`Caixa`] `&[Dep]`-
        // composition surface, opening the outer-`Caixa` dependency-slot
        // arm of the composition-pin family.
        let c = caixa_with_deps(vec![Dep::simple("d", "^0.1"), Dep::simple("d", "^0.2")]);
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                DepError::DuplicateNome { ref nome, list } if nome == "d"
                    && list == crate::render::DEP_AUTHOR_KEY_DEPS
            ),
            "validate_deps must reject deps == \
             vec![Dep(\"d\",\"^0.1\"), Dep(\"d\",\"^0.2\")] with \
             DuplicateNome {{ nome: \"d\", list: \":deps\" }} — the \
             accessor and the validate gate must route through the \
             same substrate-primitive typed dispatch on the :deps \
             within-list duplicate arm (got {err:?})",
        );
        let c = caixa_with_deps(vec![Dep::simple("d", "^0.1")]);
        assert!(
            c.validate_deps().is_ok(),
            "validate_deps must accept deps == vec![Dep(\"d\",\"^0.1\")] \
             (the canonical single-entry form)",
        );
    }

    #[test]
    fn deps_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::deps`] returns `&[Dep]` by borrow
        // — the returned slice borrows the underlying `Vec<Dep>` storage
        // of the `:deps` slot and the accessor must not clone the
        // backing `Vec` on every call. Peer of the per-`Caixa`
        // `autores_projects_slice_by_borrow` (b5d813f),
        // `etiquetas_projects_slice_by_borrow` (78c7d3c),
        // `bibliotecas_projects_slice_by_borrow` (8a36c23),
        // `exe_projects_slice_by_borrow` (65d9527), and
        // `servicos_projects_slice_by_borrow` (611f78b) by-borrow pins
        // on the sibling outer top-level [`Caixa`] `&[String]`-return
        // axes — the accessor's returned slice must borrow from `&self`
        // (the returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // slices that are pointer-equal (the underlying byte-buffer is
        // the storage `Vec`'s allocation, not a fresh copy) as well as
        // value-equal (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<Dep>` (which would type-check but silently clone on
        // every call), a `&Vec<Dep>` return (which would leak the
        // backing `Vec`'s grow/push/reserve surface no downstream
        // consumer reaches for), or a one-arm-only accessor that
        // returned a saturating value on some sentinel input.
        for deps in [
            vec![],
            vec![Dep::simple("caixa-teia", "^0.1")],
            vec![
                Dep::simple("caixa-teia", "^0.1"),
                Dep::simple("caixa-core", "^0.1"),
            ],
        ] {
            let c = caixa_with_deps(deps.clone());
            let first = c.deps();
            let second = c.deps();
            assert_eq!(
                first, second,
                "Caixa::deps must be idempotent — two successive calls \
                 on the same &self must return the same &[Dep]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::deps must borrow the underlying Vec<Dep> \
                 storage — two successive calls must return slices \
                 with the same backing pointer (a fresh Vec<Dep> clone \
                 would change the pointer on every call)",
            );
            assert_eq!(
                first,
                deps.as_slice(),
                "Caixa::deps must return :deps verbatim by borrow — \
                 got {first:?}, expected {deps:?}",
            );
        }
    }

    // ── Caixa::deps_dev — outer top-level &[Dep] slice accessor ──────

    fn caixa_with_deps_dev(deps_dev: Vec<Dep>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps_dev = deps_dev;
        c
    }

    #[test]
    fn deps_dev_returns_deps_dev_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:deps-dev` universal-axis dev-only-
        // dependency-declaration-list slice pin: [`Caixa::deps_dev`]
        // must return the `:deps-dev` typed [`Vec<Dep>`] list verbatim as
        // a `&[Dep]`, element-equal to the raw `self.deps_dev.as_slice()`
        // access across every representative value in the accept-set —
        // `[]` (the "no dev deps declared" arm every existing fixture
        // without a `:deps-dev` line carries; the [`Caixa::template`]
        // scaffold emits `:deps-dev ()`), a canonical single-entry list
        // (the shape most consumer caixas carry — a `tatara-check` dev
        // pin), a canonical two-entry list (the multi-dev-dep closure),
        // and two past-the-guard sentinels — a `[""]`-`:nome` entry
        // ([`Self::validate_deps`] rejects through `NomeEmpty` /
        // `NomeInvalid` but the accessor must ship the raw slot
        // verbatim) and a `[a, a]` duplicate (validate rejects through
        // `DuplicateNome { list: ":deps-dev" }` but the accessor must
        // ship the raw slot verbatim so struct-literal fixtures continue
        // to expose the duplicate at the accessor).
        //
        // Second outer top-level [`Caixa`] `&[Dep]`-return slice-accessor
        // pin on the substrate primitive — closes the outer-`Caixa`
        // dependency-slot `&[Dep]` sub-family the sibling
        // `deps_returns_deps_slice_verbatim_across_permutations`
        // (ad34b4e) opened on. Folds the "outer [`Caixa`] `&[Dep]`
        // slice" projection pattern onto the sibling dev-dep axis —
        // pins against a future silent detour that returned an owned
        // `Vec<Dep>` (which would type-check but silently clone on every
        // accessor call, breaking the zero-cost projection every peer
        // sibling slice accessor carries), a `[""] → []` collapse (which
        // would silently absorb the `NomeEmpty` refusal case at the
        // accessor boundary), or a `[a, a] → [a]` dedup collapse (which
        // would silently absorb the `DuplicateNome` refusal case at the
        // accessor boundary).
        for deps_dev in [
            vec![],
            vec![Dep::simple("", "^0.1")],
            vec![Dep::simple("tatara-check", "^0.1")],
            vec![
                Dep::simple("tatara-check", "^0.1"),
                Dep::simple("caixa-lint", "^0.1"),
            ],
            vec![
                Dep::simple("tatara-check", "^0.1"),
                Dep::simple("tatara-check", "^0.2"),
            ],
        ] {
            let c = caixa_with_deps_dev(deps_dev.clone());
            assert_eq!(
                c.deps_dev(),
                deps_dev.as_slice(),
                "Caixa::deps_dev must return :deps-dev verbatim (got \
                 {:?}, expected {deps_dev:?})",
                c.deps_dev(),
            );
            assert_eq!(
                c.deps_dev(),
                c.deps_dev.as_slice(),
                "Caixa::deps_dev must element-equal the raw \
                 `self.deps_dev.as_slice()` field access across every \
                 value in the Vec<Dep> accept-set",
            );
        }
    }

    #[test]
    fn validate_deps_duplicate_deps_dev_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_deps`]'s within-`:deps-dev`
        // duplicate-`:nome` gate must key off [`Caixa::deps_dev`], not
        // the raw `&self.deps_dev` field-borrow walk. Structurally: a
        // `Caixa { deps_dev: vec![Dep::simple("d", "^0.1"),
        // Dep::simple("d", "^0.2")], .. }` must surface the
        // `DuplicateNome { list: ":deps-dev" }` refusal exactly, and a
        // `Caixa { deps_dev: vec![Dep::simple("d", "^0.1")], .. }` (the
        // canonical single-entry form) must pass validate. The pair
        // jointly pins the accessor + validate-gate composition: any
        // future silent detour that had the accessor return a dedupped
        // slice on the `[a, a]` arm (a
        // `.iter().unique_by(|d| d.nome.as_str()).collect()` collapse)
        // would silently absorb the `DuplicateNome` refusal at the
        // accessor boundary and the validate gate would accept a
        // struct-literal `Caixa` carrying the drift — the composition
        // pin catches that at caixa-core build time.
        //
        // Peer of `validate_deps_duplicate_arm_routes_through_accessor`
        // (ad34b4e) on the sibling `:deps` axis — same "the validate
        // gate must route through the substrate-primitive typed
        // dispatch" discipline folded onto the sibling `:deps-dev`
        // axis, closing the two-list dep-graph composition-pin family.
        // The `:deps-dev` diagnostic must carry the
        // `DEP_AUTHOR_KEY_DEPS_DEV` list-tag (not
        // `DEP_AUTHOR_KEY_DEPS`) so the emitted error names the
        // offending list unambiguously.
        let c = caixa_with_deps_dev(vec![Dep::simple("d", "^0.1"), Dep::simple("d", "^0.2")]);
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                DepError::DuplicateNome { ref nome, list } if nome == "d"
                    && list == crate::render::DEP_AUTHOR_KEY_DEPS_DEV
            ),
            "validate_deps must reject deps_dev == \
             vec![Dep(\"d\",\"^0.1\"), Dep(\"d\",\"^0.2\")] with \
             DuplicateNome {{ nome: \"d\", list: \":deps-dev\" }} — the \
             accessor and the validate gate must route through the \
             same substrate-primitive typed dispatch on the :deps-dev \
             within-list duplicate arm (got {err:?})",
        );
        let c = caixa_with_deps_dev(vec![Dep::simple("d", "^0.1")]);
        assert!(
            c.validate_deps().is_ok(),
            "validate_deps must accept deps_dev == \
             vec![Dep(\"d\",\"^0.1\")] (the canonical single-entry form)",
        );
    }

    #[test]
    fn deps_dev_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::deps_dev`] returns `&[Dep]` by
        // borrow — the returned slice borrows the underlying `Vec<Dep>`
        // storage of the `:deps-dev` slot and the accessor must not
        // clone the backing `Vec` on every call. Peer of
        // `deps_projects_slice_by_borrow` (ad34b4e) on the sibling
        // `:deps` axis, and of the per-`Caixa`
        // `autores_projects_slice_by_borrow` (b5d813f),
        // `etiquetas_projects_slice_by_borrow` (78c7d3c),
        // `bibliotecas_projects_slice_by_borrow` (8a36c23),
        // `exe_projects_slice_by_borrow` (65d9527), and
        // `servicos_projects_slice_by_borrow` (611f78b) by-borrow pins
        // on the sibling outer top-level [`Caixa`] `&[String]`-return
        // axes — the accessor's returned slice must borrow from `&self`
        // (the returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // slices that are pointer-equal (the underlying byte-buffer is
        // the storage `Vec`'s allocation, not a fresh copy) as well as
        // value-equal (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<Dep>` (which would type-check but silently clone on
        // every call), a `&Vec<Dep>` return (which would leak the
        // backing `Vec`'s grow/push/reserve surface no downstream
        // consumer reaches for), or a one-arm-only accessor that
        // returned a saturating value on some sentinel input.
        for deps_dev in [
            vec![],
            vec![Dep::simple("tatara-check", "^0.1")],
            vec![
                Dep::simple("tatara-check", "^0.1"),
                Dep::simple("caixa-lint", "^0.1"),
            ],
        ] {
            let c = caixa_with_deps_dev(deps_dev.clone());
            let first = c.deps_dev();
            let second = c.deps_dev();
            assert_eq!(
                first, second,
                "Caixa::deps_dev must be idempotent — two successive \
                 calls on the same &self must return the same &[Dep]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::deps_dev must borrow the underlying Vec<Dep> \
                 storage — two successive calls must return slices \
                 with the same backing pointer (a fresh Vec<Dep> clone \
                 would change the pointer on every call)",
            );
            assert_eq!(
                first,
                deps_dev.as_slice(),
                "Caixa::deps_dev must return :deps-dev verbatim by \
                 borrow — got {first:?}, expected {deps_dev:?}",
            );
        }
    }

    // ── Caixa::limits — outer top-level Option<&LimitsSpec> composite-reference accessor ──

    fn caixa_with_limits(limits: Option<crate::LimitsSpec>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.limits = limits;
        c
    }

    #[test]
    fn limits_returns_limits_option_ref_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:limits` M2 typed-slot outer-
        // composite optional-composite-reference-shape pin:
        // [`Caixa::limits`] must return the `:limits` typed
        // `Option<LimitsSpec>` verbatim as an `Option<&LimitsSpec>`
        // reference over the same backing storage the raw
        // `self.limits.as_ref()` field access borrows from, byte-equal
        // across every representative fixture in the accept-set — the
        // author-omitted `None` shape (the "engine-default applies"
        // partition every downstream Servico M2 overlay emitter treats
        // as "emit nothing"), the empty-composite `Some(LimitsSpec {
        // .. default })` shape ([`LimitsSpec::is_empty`] holds — every
        // per-axis cap is `None`, so the peer M2 overlay emitter's
        // `.is_empty()`-gated projection still emits nothing but the
        // outer presence-bit is `Some`, so [`Caixa::declared_servico_slots`]
        // still pushes the `M2_AUTHOR_KEY_LIMITS` label), a single-axis
        // fixture (only `:memory` set — the canonical shape most
        // memory-heavy Servicos carry), and a fully-populated composite
        // (every per-axis cap set — the canonical shape a
        // sandboxed-by-default Servico carries).
        //
        // Pins against a future silent detour that returned a fresh-
        // cloned [`LimitsSpec`] copy (which would type-check via the
        // `Clone` impl but silently break every downstream caller that
        // relied on the reference sharing the composite's backing
        // identity), a reference to an operator-resolved overlay (the
        // future per-cluster `:limits-overrides` slot — its resolution
        // must land at exactly this accessor body, not silently divert
        // the raw slot away from a second consumer), a
        // `None` → `Some(LimitsSpec::default)` cluster-default
        // projection (which would collapse the load-bearing
        // "author-omitted `:limits` ⇒ engine-default applies" partition
        // the peer [`crate::render::servico_m2_overlay`] emitter and
        // the peer [`Caixa::declared_servico_slots`] enumerator both
        // read), or an axis-shuffled projection (a future detour that
        // swapped `memory` and `fuel` through the accessor would
        // silently split the paired [`crate::StandardLayout::verify`]
        // per-`:limits` shape gate's traversal input from the peer
        // `servico_m2_overlay` emitter's projection input).
        //
        // First outer top-level [`Caixa`] `Option<&Composite>`-return
        // composite-reference accessor pin on the substrate primitive
        // — opens the outer-`Caixa` `Option<&Composite>` composite-
        // reference projection pattern the sibling `:behavior`
        // [`crate::BehaviorSpec`] / `:politicas`
        // [`crate::aplicacao::MeshPolicy`] / `:placement`
        // [`crate::aplicacao::Placement`] / `:entrada`
        // [`crate::aplicacao::Entrada`] future outer-composite lifts
        // fold on. Peer of the closed M3 outer-composite family the
        // sibling [`crate::AplicacaoSpec::politicas`] (534dc21) /
        // [`crate::AplicacaoSpec::placement`] (9abb8f0) /
        // [`crate::AplicacaoSpec::entrada`] (d32111c) composite-
        // reference accessor pins already carry on the outer
        // [`crate::AplicacaoSpec`] altitude — extends the outer-
        // accessor byte-equal-projection discipline onto the outer
        // top-level [`Caixa`] M2 Servico-runtime slot altitude.
        use crate::LimitsSpec;
        use std::time::Duration;
        let fixtures: Vec<Option<LimitsSpec>> = vec![
            None,
            Some(LimitsSpec::default()),
            Some(LimitsSpec {
                memory: Some(64 * 1024 * 1024),
                ..Default::default()
            }),
            Some(LimitsSpec {
                memory: Some(64 * 1024 * 1024),
                fuel: Some(1_000_000),
                wall_clock: Some(Duration::from_secs(30)),
                cpu: Some(500),
            }),
        ];
        for limits in fixtures {
            let c = caixa_with_limits(limits.clone());
            assert_eq!(
                c.limits(),
                limits.as_ref(),
                "Caixa::limits must return :limits verbatim (got {:?}, \
                 expected {:?})",
                c.limits(),
                limits.as_ref(),
            );
            match (c.limits(), c.limits.as_ref()) {
                (Some(a), Some(b)) => assert!(
                    std::ptr::eq(a, b),
                    "Caixa::limits accessor and self.limits.as_ref() \
                     field access must borrow the same backing storage \
                     — the accessor is the substrate-primitive typed \
                     dispatch every downstream Servico-M2-overlay \
                     composite consumer must route through, and a \
                     reference-identity split would silently break \
                     every consumer that relied on the borrow sharing \
                     the composite's storage",
                ),
                (None, None) => {}
                _ => panic!(
                    "Caixa::limits presence bit must byte-equal \
                     self.limits.is_some() — a presence-bit drift would \
                     silently split the paired StandardLayout::verify \
                     per-`:limits` shape gate's traversal head from \
                     the peer render::servico_m2_overlay M2 overlay \
                     emitter's traversal head from the peer \
                     Caixa::declared_servico_slots M2 declared-slot \
                     enumerator's presence probe",
                ),
            }
            assert_eq!(
                c.limits().is_some(),
                c.limits.is_some(),
                "Caixa::limits().is_some() must byte-equal \
                 self.limits.is_some() — a presence-bit drift would \
                 silently split every downstream Option<&LimitsSpec> \
                 consumer's partition on the engine-default arm",
            );
        }
    }

    #[test]
    fn declared_servico_slots_limits_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_servico_slots`]'s
        // `:limits` presence-probe arm must key off [`Caixa::limits`],
        // not the raw `self.limits.is_some()` field-probe. Structurally:
        // a `Caixa { limits: Some(LimitsSpec::default()), .. }` must
        // still push `M2_AUTHOR_KEY_LIMITS` onto the declared-slot list
        // (the presence bit is `Some`, so the M2 kind-coherence gate
        // must surface the slot as "declared" even when every per-axis
        // cap is unset), and a `Caixa { limits: None, .. }` must NOT
        // push the label (the "author omitted the slot entirely"
        // partition). The pair jointly pins the accessor + declared-
        // slot enumerator composition: any future silent detour that
        // had the accessor collapse `Some(LimitsSpec::default())` to
        // `None` (a `.filter(|l| !l.is_empty())` projection) would
        // silently absorb the "declared but empty" arm at the
        // accessor boundary and the [`crate::LayoutError::ServicoSlotsOnNonServico`]
        // kind-coherence gate would silently accept a
        // struct-literal `Caixa` carrying the drift.
        //
        // Peer of the sibling per-`Caixa`
        // `validate_deps_duplicate_arm_routes_through_accessor` (ad34b4e)
        // and `validate_deps_duplicate_deps_dev_arm_routes_through_accessor`
        // (f7fd81e) accessor-composition pins on the sibling `:deps` /
        // `:deps-dev` outer-`&[Dep]`-composition axes — same "the
        // enumerator gate must route through the substrate-primitive
        // typed dispatch" discipline extended onto the outer top-level
        // [`Caixa`] `Option<&LimitsSpec>`-composition surface, opening
        // the outer-`Caixa` M2 Servico-runtime-slot arm of the
        // composition-pin family.
        use crate::LimitsSpec;
        let c = caixa_with_limits(Some(LimitsSpec::default()));
        let slots = c.declared_servico_slots();
        assert!(
            slots.contains(&crate::render::M2_AUTHOR_KEY_LIMITS),
            "declared_servico_slots must push M2_AUTHOR_KEY_LIMITS \
             when `:limits` is Some (even for LimitsSpec::default()) \
             — the accessor and the enumerator gate must route through \
             the same substrate-primitive typed dispatch on the outer \
             :limits presence bit (got slots={slots:?})",
        );
        let c = caixa_with_limits(None);
        let slots = c.declared_servico_slots();
        assert!(
            !slots.contains(&crate::render::M2_AUTHOR_KEY_LIMITS),
            "declared_servico_slots must NOT push M2_AUTHOR_KEY_LIMITS \
             when `:limits` is None — the author-omitted arm must \
             route through the accessor's None-return unchanged (got \
             slots={slots:?})",
        );
    }

    #[test]
    fn servico_m2_overlay_limits_arm_routes_through_accessor() {
        // Composition pin: [`crate::render::servico_m2_overlay`]'s
        // per-`:limits` M2 overlay emit arm must key off
        // [`Caixa::limits`], not the raw `&caixa.limits` field-borrow.
        // Structurally: a `Caixa { limits: Some(LimitsSpec { memory:
        // Some(64 MiB), .. default }), .. }` must surface the
        // `M2_KEY_LIMITS` key with the per-axis
        // `memory: "64MiB"` sub-mapping in the overlay, a `Caixa {
        // limits: Some(LimitsSpec::default()), .. }` must omit the
        // key entirely (the `.is_empty()`-gated inner arm elides an
        // empty composite even when the outer presence bit is `Some`),
        // and a `Caixa { limits: None, .. }` must also omit the key
        // (the "author omitted the slot entirely" partition). The
        // three-fixture family jointly pins the accessor + M2 overlay
        // emitter composition: any future silent detour that had the
        // accessor return a fresh-cloned copy on the `Some` arm (a
        // `LimitsSpec::clone()` projection) would silently break the
        // reference-identity pin the peer per-axis
        // `serde_yaml::to_value(limits)` projection reads from.
        use crate::LimitsSpec;
        use crate::render::{M2_KEY_LIMITS, servico_m2_overlay};
        let c = caixa_with_limits(Some(LimitsSpec {
            memory: Some(64 * 1024 * 1024),
            ..Default::default()
        }));
        let overlay = servico_m2_overlay(&c).unwrap();
        assert!(
            overlay.contains_key(M2_KEY_LIMITS),
            "servico_m2_overlay must surface M2_KEY_LIMITS when \
             `:limits` carries a non-empty composite — the accessor \
             and the M2 overlay emitter must route through the same \
             substrate-primitive typed dispatch on the outer :limits \
             composite (got overlay={overlay:?})",
        );
        let c = caixa_with_limits(Some(LimitsSpec::default()));
        let overlay = servico_m2_overlay(&c).unwrap();
        assert!(
            !overlay.contains_key(M2_KEY_LIMITS),
            "servico_m2_overlay must omit M2_KEY_LIMITS when \
             `:limits` is Some(LimitsSpec::default()) — the empty \
             composite's `.is_empty()`-gated inner arm must elide \
             the key regardless of the outer presence bit (got \
             overlay={overlay:?})",
        );
        let c = caixa_with_limits(None);
        let overlay = servico_m2_overlay(&c).unwrap();
        assert!(
            !overlay.contains_key(M2_KEY_LIMITS),
            "servico_m2_overlay must omit M2_KEY_LIMITS when \
             `:limits` is None — the author-omitted arm must route \
             through the accessor's None-return unchanged (got \
             overlay={overlay:?})",
        );
    }

    #[test]
    fn limits_projects_option_ref_by_borrow() {
        // The by-borrow pin: [`Caixa::limits`] returns
        // `Option<&LimitsSpec>` by borrow — the returned reference
        // borrows the underlying `Option<LimitsSpec>` storage of the
        // `:limits` slot and the accessor must not clone the backing
        // composite on every call. Peer of the sibling
        // `deps_projects_slice_by_borrow` (ad34b4e) /
        // `deps_dev_projects_slice_by_borrow` (f7fd81e) by-borrow pins
        // on the outer top-level [`Caixa`] `&[Dep]`-return axes —
        // extended here to the outer [`Caixa`] `Option<&Composite>`-
        // return axis: the accessor's returned reference must borrow
        // from `&self` (the returned reference's lifetime is tied to
        // `&self`), and calling the accessor twice on the same
        // [`Caixa`] must yield references that are pointer-equal (the
        // underlying byte-buffer is the storage `LimitsSpec`'s
        // allocation, not a fresh copy) as well as value-equal
        // (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `LimitsSpec` (which would type-check via the `Clone` impl
        // but silently clone on every call), a `&LimitsSpec` panic-
        // return on the `None` arm (which would collapse the load-
        // bearing `Option` presence-bit into a runtime panic), or a
        // one-arm-only accessor that returned a saturating composite
        // on some sentinel input.
        use crate::LimitsSpec;
        use std::time::Duration;
        for limits in [
            Some(LimitsSpec::default()),
            Some(LimitsSpec {
                memory: Some(64 * 1024 * 1024),
                fuel: Some(1_000_000),
                wall_clock: Some(Duration::from_secs(30)),
                cpu: Some(500),
            }),
        ] {
            let c = caixa_with_limits(limits.clone());
            let first = c.limits().unwrap();
            let second = c.limits().unwrap();
            assert_eq!(
                first, second,
                "Caixa::limits must be idempotent — two successive \
                 calls on the same &self must return the same \
                 &LimitsSpec",
            );
            assert!(
                std::ptr::eq(first, second),
                "Caixa::limits must borrow the underlying \
                 Option<LimitsSpec> storage — two successive calls \
                 must return references with the same backing pointer \
                 (a fresh LimitsSpec clone would change the pointer \
                 on every call)",
            );
            assert_eq!(
                Some(first),
                limits.as_ref(),
                "Caixa::limits must return :limits verbatim by borrow \
                 — got {first:?}, expected {:?}",
                limits.as_ref(),
            );
        }
        let c = caixa_with_limits(None);
        assert!(
            c.limits().is_none(),
            "Caixa::limits must return None when :limits is absent — \
             the author-omitted arm must project through the \
             accessor's Option::None unchanged",
        );
    }

    // ── Caixa::behavior — outer top-level Option<&BehaviorSpec> composite-reference accessor ──

    fn caixa_with_behavior(behavior: Option<crate::BehaviorSpec>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.behavior = behavior;
        c
    }

    #[test]
    fn behavior_returns_behavior_option_ref_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:behavior` M2 typed-slot outer-
        // composite optional-composite-reference-shape pin:
        // [`Caixa::behavior`] must return the `:behavior` typed
        // `Option<BehaviorSpec>` verbatim as an `Option<&BehaviorSpec>`
        // reference over the same backing storage the raw
        // `self.behavior.as_ref()` field access borrows from, byte-equal
        // across every representative fixture in the accept-set — the
        // author-omitted `None` shape (the "runtime-default applies"
        // partition every downstream Servico M2 overlay emitter treats
        // as "emit nothing"), the empty-composite `Some(BehaviorSpec {
        // .. default })` shape ([`BehaviorSpec::is_empty`] holds —
        // every per-callback path is `None`, so the peer M2 overlay
        // emitter's `.is_empty()`-gated projection still emits nothing
        // but the outer presence-bit is `Some`, so
        // [`Caixa::declared_servico_slots`] still pushes the
        // `M2_AUTHOR_KEY_BEHAVIOR` label), a single-callback fixture
        // (only `:on-state-change` set — the canonical shape a caixa
        // that only wires the hot-upgrade migration path carries), and
        // a fully-populated composite (every per-callback path set —
        // the canonical shape a fully-instrumented gen_server-shaped
        // Servico carries).
        //
        // Peer of the sibling
        // `limits_returns_limits_option_ref_verbatim_across_permutations`
        // (b2bd9d7) opening fixture-family + reference-identity +
        // presence-bit tetrad pin on the outer top-level [`Caixa`]
        // `Option<&Composite>`-return sub-family — extended here to the
        // second axis of that sub-family so both of the currently-lifted
        // M2 Servico-runtime `Option<&Composite>` slots (`:limits` /
        // `:behavior`) carry the same "byte-equal, borrow-shared,
        // presence-bit-preserved" outer-accessor discipline.
        //
        // Pins against a future silent detour that returned a fresh-
        // cloned [`crate::BehaviorSpec`] copy (which would type-check
        // via the `Clone` impl but silently break every downstream
        // caller that relied on the reference sharing the composite's
        // backing identity), a reference to an operator-resolved
        // overlay (a future per-cluster `:behavior-overrides` slot —
        // its resolution must land at exactly this accessor body, not
        // silently divert the raw slot away from a second consumer), a
        // `None` → `Some(BehaviorSpec::default)` cluster-default
        // projection (which would collapse the load-bearing
        // "author-omitted `:behavior` ⇒ runtime-default applies"
        // partition the peer [`crate::render::servico_m2_overlay`]
        // emitter, the peer [`Caixa::declared_servico_slots`]
        // enumerator, and the cross-slot
        // [`crate::upgrade::validate_upgrade_from_against_behavior`]
        // gate all read), or a callback-shuffled projection (a future
        // detour that swapped `on_init` and `on_terminate` through the
        // accessor would silently split the paired
        // [`crate::StandardLayout::verify`] per-`:behavior` shape gate's
        // traversal input from the peer `servico_m2_overlay` emitter's
        // projection input from the cross-slot `:state-change`
        // composition gate's traversal input).
        use crate::BehaviorSpec;
        use std::path::PathBuf;
        let fixtures: Vec<Option<BehaviorSpec>> = vec![
            None,
            Some(BehaviorSpec::default()),
            Some(BehaviorSpec {
                on_state_change: Some(PathBuf::from("lib/migrations.lisp")),
                ..Default::default()
            }),
            Some(BehaviorSpec {
                on_init: Some(PathBuf::from("lib/init.lisp")),
                on_call: Some(PathBuf::from("lib/handlers.lisp")),
                on_cast: Some(PathBuf::from("lib/handlers.lisp")),
                on_info: Some(PathBuf::from("lib/handlers.lisp")),
                on_state_change: Some(PathBuf::from("lib/migrations.lisp")),
                on_terminate: Some(PathBuf::from("lib/cleanup.lisp")),
            }),
        ];
        for behavior in fixtures {
            let c = caixa_with_behavior(behavior.clone());
            assert_eq!(
                c.behavior(),
                behavior.as_ref(),
                "Caixa::behavior must return :behavior verbatim (got \
                 {:?}, expected {:?})",
                c.behavior(),
                behavior.as_ref(),
            );
            match (c.behavior(), c.behavior.as_ref()) {
                (Some(a), Some(b)) => assert!(
                    std::ptr::eq(a, b),
                    "Caixa::behavior accessor and self.behavior.as_ref() \
                     field access must borrow the same backing storage \
                     — the accessor is the substrate-primitive typed \
                     dispatch every downstream Servico-M2-overlay \
                     composite consumer must route through, and a \
                     reference-identity split would silently break \
                     every consumer that relied on the borrow sharing \
                     the composite's storage",
                ),
                (None, None) => {}
                _ => panic!(
                    "Caixa::behavior presence bit must byte-equal \
                     self.behavior.is_some() — a presence-bit drift \
                     would silently split the paired \
                     StandardLayout::verify per-`:behavior` shape \
                     gate's traversal head from the peer \
                     render::servico_m2_overlay M2 overlay emitter's \
                     traversal head from the cross-slot \
                     validate_upgrade_from_against_behavior \
                     composition gate's traversal head from the peer \
                     Caixa::declared_servico_slots M2 declared-slot \
                     enumerator's presence probe",
                ),
            }
            assert_eq!(
                c.behavior().is_some(),
                c.behavior.is_some(),
                "Caixa::behavior().is_some() must byte-equal \
                 self.behavior.is_some() — a presence-bit drift would \
                 silently split every downstream Option<&BehaviorSpec> \
                 consumer's partition on the runtime-default arm",
            );
        }
    }

    #[test]
    fn declared_servico_slots_behavior_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_servico_slots`]'s
        // `:behavior` presence-probe arm must key off
        // [`Caixa::behavior`], not the raw `self.behavior.is_some()`
        // field-probe. Structurally: a `Caixa { behavior:
        // Some(BehaviorSpec::default()), .. }` must still push
        // `M2_AUTHOR_KEY_BEHAVIOR` onto the declared-slot list (the
        // presence bit is `Some`, so the M2 kind-coherence gate must
        // surface the slot as "declared" even when every per-callback
        // path is unset), and a `Caixa { behavior: None, .. }` must
        // NOT push the label (the "author omitted the slot entirely"
        // partition). The pair jointly pins the accessor + declared-
        // slot enumerator composition: any future silent detour that
        // had the accessor collapse `Some(BehaviorSpec::default())`
        // to `None` (a `.filter(|b| !b.is_empty())` projection) would
        // silently absorb the "declared but empty" arm at the
        // accessor boundary and the
        // [`crate::LayoutError::ServicoSlotsOnNonServico`]
        // kind-coherence gate would silently accept a struct-literal
        // `Caixa` carrying the drift.
        //
        // Peer of the sibling
        // `declared_servico_slots_limits_arm_routes_through_accessor`
        // (b2bd9d7) composition pin on the sibling `:limits` outer-
        // `Option<&LimitsSpec>` arm of the same
        // [`Caixa::declared_servico_slots`] M2 declared-slot
        // enumerator's traversal — same "the enumerator gate must
        // route through the substrate-primitive typed dispatch"
        // discipline extended onto the outer top-level [`Caixa`]
        // `Option<&BehaviorSpec>`-composition surface.
        use crate::BehaviorSpec;
        let c = caixa_with_behavior(Some(BehaviorSpec::default()));
        let slots = c.declared_servico_slots();
        assert!(
            slots.contains(&crate::render::M2_AUTHOR_KEY_BEHAVIOR),
            "declared_servico_slots must push M2_AUTHOR_KEY_BEHAVIOR \
             when `:behavior` is Some (even for BehaviorSpec::default()) \
             — the accessor and the enumerator gate must route through \
             the same substrate-primitive typed dispatch on the outer \
             :behavior presence bit (got slots={slots:?})",
        );
        let c = caixa_with_behavior(None);
        let slots = c.declared_servico_slots();
        assert!(
            !slots.contains(&crate::render::M2_AUTHOR_KEY_BEHAVIOR),
            "declared_servico_slots must NOT push M2_AUTHOR_KEY_BEHAVIOR \
             when `:behavior` is None — the author-omitted arm must \
             route through the accessor's None-return unchanged (got \
             slots={slots:?})",
        );
    }

    #[test]
    fn servico_m2_overlay_behavior_arm_routes_through_accessor() {
        // Composition pin: [`crate::render::servico_m2_overlay`]'s
        // per-`:behavior` M2 overlay emit arm must key off
        // [`Caixa::behavior`], not the raw `&caixa.behavior`
        // field-borrow. Structurally: a `Caixa { behavior:
        // Some(BehaviorSpec { on_state_change: Some(...), .. default
        // }), .. }` must surface the `M2_KEY_BEHAVIOR` key with the
        // per-callback `onStateChange` sub-mapping in the overlay, a
        // `Caixa { behavior: Some(BehaviorSpec::default()), .. }`
        // must omit the key entirely (the `.is_empty()`-gated inner
        // arm elides an empty composite even when the outer presence
        // bit is `Some`), and a `Caixa { behavior: None, .. }` must
        // also omit the key (the "author omitted the slot entirely"
        // partition). The three-fixture family jointly pins the
        // accessor + M2 overlay emitter composition: any future
        // silent detour that had the accessor return a fresh-cloned
        // copy on the `Some` arm (a `BehaviorSpec::clone()`
        // projection) would silently break the reference-identity
        // pin the peer per-callback `serde_yaml::to_value(behavior)`
        // projection reads from.
        //
        // Peer of the sibling
        // `servico_m2_overlay_limits_arm_routes_through_accessor`
        // (b2bd9d7) composition pin on the sibling `:limits` outer-
        // `Option<&LimitsSpec>` arm of the same
        // [`crate::render::servico_m2_overlay`] M2 overlay emitter's
        // traversal — same "the emitter must route through the
        // substrate-primitive typed dispatch on the outer composite"
        // discipline extended onto the outer top-level [`Caixa`]
        // `Option<&BehaviorSpec>`-composition surface.
        use crate::BehaviorSpec;
        use crate::render::{M2_KEY_BEHAVIOR, servico_m2_overlay};
        use std::path::PathBuf;
        let c = caixa_with_behavior(Some(BehaviorSpec {
            on_state_change: Some(PathBuf::from("lib/migrations.lisp")),
            ..Default::default()
        }));
        let overlay = servico_m2_overlay(&c).unwrap();
        assert!(
            overlay.contains_key(M2_KEY_BEHAVIOR),
            "servico_m2_overlay must surface M2_KEY_BEHAVIOR when \
             `:behavior` carries a non-empty composite — the accessor \
             and the M2 overlay emitter must route through the same \
             substrate-primitive typed dispatch on the outer :behavior \
             composite (got overlay={overlay:?})",
        );
        let c = caixa_with_behavior(Some(BehaviorSpec::default()));
        let overlay = servico_m2_overlay(&c).unwrap();
        assert!(
            !overlay.contains_key(M2_KEY_BEHAVIOR),
            "servico_m2_overlay must omit M2_KEY_BEHAVIOR when \
             `:behavior` is Some(BehaviorSpec::default()) — the empty \
             composite's `.is_empty()`-gated inner arm must elide the \
             key regardless of the outer presence bit (got \
             overlay={overlay:?})",
        );
        let c = caixa_with_behavior(None);
        let overlay = servico_m2_overlay(&c).unwrap();
        assert!(
            !overlay.contains_key(M2_KEY_BEHAVIOR),
            "servico_m2_overlay must omit M2_KEY_BEHAVIOR when \
             `:behavior` is None — the author-omitted arm must route \
             through the accessor's None-return unchanged (got \
             overlay={overlay:?})",
        );
    }

    #[test]
    fn behavior_projects_option_ref_by_borrow() {
        // The by-borrow pin: [`Caixa::behavior`] returns
        // `Option<&BehaviorSpec>` by borrow — the returned reference
        // borrows the underlying `Option<BehaviorSpec>` storage of the
        // `:behavior` slot and the accessor must not clone the backing
        // composite on every call. Peer of the sibling
        // `limits_projects_option_ref_by_borrow` (b2bd9d7) by-borrow
        // pin on the outer top-level [`Caixa`] `Option<&Composite>`-
        // return sub-family — extended here to the second axis of the
        // same sub-family: the accessor's returned reference must
        // borrow from `&self` (the returned reference's lifetime is
        // tied to `&self`), and calling the accessor twice on the same
        // [`Caixa`] must yield references that are pointer-equal (the
        // underlying byte-buffer is the storage `BehaviorSpec`'s
        // allocation, not a fresh copy) as well as value-equal
        // (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `BehaviorSpec` (which would type-check via the `Clone` impl
        // but silently clone on every call), a `&BehaviorSpec` panic-
        // return on the `None` arm (which would collapse the load-
        // bearing `Option` presence-bit into a runtime panic), or a
        // one-arm-only accessor that returned a saturating composite
        // on some sentinel input.
        use crate::BehaviorSpec;
        use std::path::PathBuf;
        for behavior in [
            Some(BehaviorSpec::default()),
            Some(BehaviorSpec {
                on_init: Some(PathBuf::from("lib/init.lisp")),
                on_call: Some(PathBuf::from("lib/handlers.lisp")),
                on_cast: Some(PathBuf::from("lib/handlers.lisp")),
                on_info: Some(PathBuf::from("lib/handlers.lisp")),
                on_state_change: Some(PathBuf::from("lib/migrations.lisp")),
                on_terminate: Some(PathBuf::from("lib/cleanup.lisp")),
            }),
        ] {
            let c = caixa_with_behavior(behavior.clone());
            let first = c.behavior().unwrap();
            let second = c.behavior().unwrap();
            assert_eq!(
                first, second,
                "Caixa::behavior must be idempotent — two successive \
                 calls on the same &self must return the same \
                 &BehaviorSpec",
            );
            assert!(
                std::ptr::eq(first, second),
                "Caixa::behavior must borrow the underlying \
                 Option<BehaviorSpec> storage — two successive calls \
                 must return references with the same backing pointer \
                 (a fresh BehaviorSpec clone would change the pointer \
                 on every call)",
            );
            assert_eq!(
                Some(first),
                behavior.as_ref(),
                "Caixa::behavior must return :behavior verbatim by \
                 borrow — got {first:?}, expected {:?}",
                behavior.as_ref(),
            );
        }
        let c = caixa_with_behavior(None);
        assert!(
            c.behavior().is_none(),
            "Caixa::behavior must return None when :behavior is absent \
             — the author-omitted arm must project through the \
             accessor's Option::None unchanged",
        );
    }

    // ── Caixa::politicas — outer top-level Option<&MeshPolicy> composite-reference accessor ──

    fn caixa_aplicacao_with_politicas(politicas: Option<crate::aplicacao::MeshPolicy>) -> Caixa {
        use crate::aplicacao::{Membro, WitContract};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.kind = CaixaKind::Aplicacao;
        c.membros = vec![Membro {
            caixa: "a".into(),
            versao: "^0.1".into(),
        }];
        c.contratos = vec![WitContract {
            de: "a".into(),
            para: "a".into(),
            wit: "wasi:http/proxy".into(),
            endpoint: Some("/x".into()),
            subject: None,
            slot: None,
        }];
        c.politicas = politicas;
        c
    }

    #[test]
    fn politicas_returns_politicas_option_ref_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:politicas` M3 mesh-slot outer-
        // composite optional-composite-reference-shape pin:
        // [`Caixa::politicas`] must return the `:politicas` typed
        // `Option<MeshPolicy>` verbatim as an `Option<&MeshPolicy>`
        // reference over the same backing storage the raw
        // `self.politicas.as_ref()` field access borrows from,
        // byte-equal across every representative fixture in the
        // accept-set — the author-omitted `None` shape (the "cluster-
        // default applies" partition every downstream mesh-artifact
        // emitter treats as "emit no `:politicas` overlay"), the
        // empty-composite `Some(MeshPolicy { .. default })` shape
        // ([`crate::aplicacao::MeshPolicy::is_empty`] holds — every
        // per-axis mesh-policy scalar is `None`, so the peer inner
        // [`crate::AplicacaoSpec::politicas`] `.is_empty()`-gated
        // caixa-mesh overlay elides every per-axis emit but the outer
        // presence-bit is `Some`, so [`Caixa::declared_mesh_slots`]
        // still pushes the `M3_AUTHOR_KEY_POLITICAS` label), a
        // single-axis fixture (only `:timeout` set — the canonical
        // shape a latency-sensitive Aplicacao carries), and a
        // fully-populated composite (every per-axis mesh-policy
        // scalar set — the canonical shape a fully-governed
        // Aplicacao carries).
        //
        // Pins against a future silent detour that returned a fresh-
        // cloned [`crate::aplicacao::MeshPolicy`] copy (which would
        // type-check via the `Clone` impl but silently break every
        // downstream caller that relied on the reference sharing the
        // composite's backing identity), a reference to an operator-
        // resolved overlay (the future per-cluster
        // `:politicas-overrides` slot — its resolution must land at
        // exactly this accessor body, not silently divert the raw
        // slot away from the peer [`Caixa::declared_mesh_slots`]
        // enumerator's presence probe), a
        // `None` → `Some(MeshPolicy::default)` cluster-default
        // projection (which would collapse the load-bearing
        // "author-omitted `:politicas` ⇒ cluster-default applies"
        // partition the peer [`Caixa::declared_mesh_slots`]
        // enumerator and the peer [`Caixa::aplicacao_view`]
        // Aplicacao-composition seed both read), or an axis-shuffled
        // projection (a future detour that swapped `timeout` and
        // `retries` through the accessor would silently split the
        // paired [`Caixa::aplicacao_view`] seed's fold input from the
        // sibling M3 mesh-artifact emitter's projection input).
        //
        // Third outer top-level [`Caixa`] `Option<&Composite>`-return
        // composite-reference accessor pin on the substrate primitive
        // — peer of the sibling
        // `limits_returns_limits_option_ref_verbatim_across_permutations`
        // (b2bd9d7) and
        // `behavior_returns_behavior_option_ref_verbatim_across_permutations`
        // (35d8b52) opening tetrad pins on the outer top-level
        // [`Caixa`] `Option<&Composite>`-return sub-family — extended
        // here to the first of the three M3 mesh-slot axes so the
        // opening third of the outer `Option<&Composite>` sub-family
        // carries the same "byte-equal, borrow-shared, presence-bit-
        // preserved" outer-accessor discipline.
        use crate::aplicacao::{CircuitBreaker, MeshPolicy, RateLimit};
        use std::time::Duration;
        let fixtures: Vec<Option<MeshPolicy>> = vec![
            None,
            Some(MeshPolicy::default()),
            Some(MeshPolicy {
                timeout: Some(Duration::from_secs(30)),
                ..Default::default()
            }),
            Some(MeshPolicy {
                timeout: Some(Duration::from_secs(30)),
                retries: Some(3),
                circuit_breaker: Some(CircuitBreaker {
                    max_failures: 5,
                    window: Duration::from_secs(60),
                }),
                mtls_required: Some(true),
                rate_limit: Some(RateLimit {
                    rate: 100,
                    window: Duration::from_secs(1),
                }),
            }),
        ];
        for politicas in fixtures {
            let c = caixa_aplicacao_with_politicas(politicas.clone());
            assert_eq!(
                c.politicas(),
                politicas.as_ref(),
                "Caixa::politicas must return :politicas verbatim (got \
                 {:?}, expected {:?})",
                c.politicas(),
                politicas.as_ref(),
            );
            match (c.politicas(), c.politicas.as_ref()) {
                (Some(a), Some(b)) => assert!(
                    std::ptr::eq(a, b),
                    "Caixa::politicas accessor and self.politicas.as_ref() \
                     field access must borrow the same backing storage \
                     — the accessor is the substrate-primitive typed \
                     dispatch every downstream Aplicacao-mesh-overlay \
                     composite consumer must route through, and a \
                     reference-identity split would silently break \
                     every consumer that relied on the borrow sharing \
                     the composite's storage",
                ),
                (None, None) => {}
                _ => panic!(
                    "Caixa::politicas presence bit must byte-equal \
                     self.politicas.is_some() — a presence-bit drift \
                     would silently split the paired \
                     Caixa::aplicacao_view Aplicacao-composition seed's \
                     traversal head from the peer \
                     Caixa::declared_mesh_slots M3 declared-slot \
                     enumerator's presence probe",
                ),
            }
            assert_eq!(
                c.politicas().is_some(),
                c.politicas.is_some(),
                "Caixa::politicas().is_some() must byte-equal \
                 self.politicas.is_some() — a presence-bit drift would \
                 silently split every downstream Option<&MeshPolicy> \
                 consumer's partition on the cluster-default arm",
            );
        }
    }

    #[test]
    fn declared_mesh_slots_politicas_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_mesh_slots`]'s
        // `:politicas` presence-probe arm must key off
        // [`Caixa::politicas`], not the raw `self.politicas.is_some()`
        // field-probe. Structurally: a `Caixa { politicas:
        // Some(MeshPolicy::default()), .. }` must still push
        // `M3_AUTHOR_KEY_POLITICAS` onto the declared-slot list (the
        // presence bit is `Some`, so the M3 kind-coherence gate must
        // surface the slot as "declared" even when every per-axis
        // scalar is unset), and a `Caixa { politicas: None, .. }` must
        // NOT push the label (the "author omitted the slot entirely"
        // partition). The pair jointly pins the accessor + declared-
        // slot enumerator composition: any future silent detour that
        // had the accessor collapse `Some(MeshPolicy::default())` to
        // `None` (a `.filter(|p| !p.is_empty())` projection) would
        // silently absorb the "declared but empty" arm at the
        // accessor boundary and the
        // [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-
        // coherence gate would silently accept a struct-literal
        // `Caixa` carrying the drift.
        //
        // Peer of the sibling
        // `declared_servico_slots_limits_arm_routes_through_accessor`
        // (b2bd9d7) and
        // `declared_servico_slots_behavior_arm_routes_through_accessor`
        // (35d8b52) composition pins on the sibling `:limits` /
        // `:behavior` outer-`Option<&Composite>` arms of the peer
        // [`Caixa::declared_servico_slots`] M2 declared-slot
        // enumerator's traversal — same "the enumerator gate must
        // route through the substrate-primitive typed dispatch"
        // discipline extended onto the outer top-level [`Caixa`] M3
        // mesh-slot family so the [`Caixa::declared_mesh_slots`]
        // enumerator carries the same routing invariant as its M2
        // sibling.
        use crate::aplicacao::MeshPolicy;
        let c = caixa_aplicacao_with_politicas(Some(MeshPolicy::default()));
        let slots = c.declared_mesh_slots();
        assert!(
            slots.contains(&crate::render::M3_AUTHOR_KEY_POLITICAS),
            "declared_mesh_slots must push M3_AUTHOR_KEY_POLITICAS \
             when `:politicas` is Some (even for MeshPolicy::default()) \
             — the accessor and the enumerator gate must route through \
             the same substrate-primitive typed dispatch on the outer \
             :politicas presence bit (got slots={slots:?})",
        );
        let c = caixa_aplicacao_with_politicas(None);
        let slots = c.declared_mesh_slots();
        assert!(
            !slots.contains(&crate::render::M3_AUTHOR_KEY_POLITICAS),
            "declared_mesh_slots must NOT push M3_AUTHOR_KEY_POLITICAS \
             when `:politicas` is None — the author-omitted arm must \
             route through the accessor's None-return unchanged (got \
             slots={slots:?})",
        );
    }

    #[test]
    fn aplicacao_view_politicas_arm_folds_through_accessor() {
        // Composition pin: [`Caixa::aplicacao_view`]'s per-`:politicas`
        // Aplicacao-composition seed must fold through
        // [`Caixa::politicas`], not the raw
        // `self.politicas.clone().unwrap_or_default()` field-borrow.
        // Structurally: a `Caixa { politicas: Some(MeshPolicy {
        // timeout: Some(30s), .. default }), kind: Aplicacao, .. }`
        // must surface a projected [`crate::AplicacaoSpec`] whose
        // `politicas().timeout()` field byte-equals the outer
        // composite's `timeout` scalar (the fold must project the
        // authored composite verbatim), a `Caixa { politicas:
        // Some(MeshPolicy::default()), kind: Aplicacao, .. }` must
        // surface an [`crate::AplicacaoSpec`] whose `politicas()`
        // byte-equals [`crate::aplicacao::MeshPolicy::default`] (the
        // fold's empty-composite arm collapses to the same default the
        // author-omitted arm does), and a `Caixa { politicas: None,
        // kind: Aplicacao, .. }` must surface an
        // [`crate::AplicacaoSpec`] whose `politicas()` byte-equals
        // [`crate::aplicacao::MeshPolicy::default`] (the "author
        // omitted the slot entirely" arm folds through the
        // `unwrap_or_default` onto the cluster-default). The triad
        // jointly pins the accessor + Aplicacao-composition seed
        // composition: any future silent detour that had the accessor
        // divert the raw slot away from the seed's fold (an operator-
        // resolved overlay's default-fold arm silently differing from
        // the raw slot's default-fold arm) would silently split the
        // build-time mesh-artifact emission gate from the caixa-mesh
        // renderer's Aplicacao-view input at the composition boundary.
        use crate::aplicacao::MeshPolicy;
        use std::time::Duration;
        let c = caixa_aplicacao_with_politicas(Some(MeshPolicy {
            timeout: Some(Duration::from_secs(30)),
            ..Default::default()
        }));
        let view = c.aplicacao_view().unwrap();
        assert_eq!(
            view.politicas().timeout(),
            Some(Duration::from_secs(30)),
            "Caixa::aplicacao_view must fold the authored :politicas \
             :timeout scalar through the accessor verbatim onto the \
             projected AplicacaoSpec — a future silent detour at the \
             seed's fold arm would surface here as a projected-scalar \
             drift (got {:?})",
            view.politicas().timeout(),
        );
        let c = caixa_aplicacao_with_politicas(Some(MeshPolicy::default()));
        let view = c.aplicacao_view().unwrap();
        assert_eq!(
            view.politicas(),
            &MeshPolicy::default(),
            "Caixa::aplicacao_view must fold Some(MeshPolicy::default()) \
             through the accessor onto MeshPolicy::default — the empty- \
             composite arm collapses to the same default the author- \
             omitted arm does (got {:?})",
            view.politicas(),
        );
        let c = caixa_aplicacao_with_politicas(None);
        let view = c.aplicacao_view().unwrap();
        assert_eq!(
            view.politicas(),
            &MeshPolicy::default(),
            "Caixa::aplicacao_view must fold None through the accessor's \
             unwrap_or_default onto MeshPolicy::default — the author- \
             omitted arm must route through the accessor's None-return \
             unchanged (got {:?})",
            view.politicas(),
        );
    }

    #[test]
    fn politicas_projects_option_ref_by_borrow() {
        // The by-borrow pin: [`Caixa::politicas`] returns
        // `Option<&MeshPolicy>` by borrow — the returned reference
        // borrows the underlying `Option<MeshPolicy>` storage of the
        // `:politicas` slot and the accessor must not clone the
        // backing composite on every call. Peer of the sibling
        // `limits_projects_option_ref_by_borrow` (b2bd9d7) and
        // `behavior_projects_option_ref_by_borrow` (35d8b52) by-borrow
        // pins on the outer top-level [`Caixa`]
        // `Option<&Composite>`-return sub-family — extended here to
        // the third axis of the same sub-family: the accessor's
        // returned reference must borrow from `&self` (the returned
        // reference's lifetime is tied to `&self`), and calling the
        // accessor twice on the same [`Caixa`] must yield references
        // that are pointer-equal (the underlying byte-buffer is the
        // storage `MeshPolicy`'s allocation, not a fresh copy) as
        // well as value-equal (idempotent, no side effects on
        // `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `MeshPolicy` (which would type-check via the `Clone` impl
        // but silently clone on every call), a `&MeshPolicy` panic-
        // return on the `None` arm (which would collapse the load-
        // bearing `Option` presence-bit into a runtime panic), or a
        // one-arm-only accessor that returned a saturating composite
        // on some sentinel input.
        use crate::aplicacao::{CircuitBreaker, MeshPolicy, RateLimit};
        use std::time::Duration;
        for politicas in [
            Some(MeshPolicy::default()),
            Some(MeshPolicy {
                timeout: Some(Duration::from_secs(30)),
                retries: Some(3),
                circuit_breaker: Some(CircuitBreaker {
                    max_failures: 5,
                    window: Duration::from_secs(60),
                }),
                mtls_required: Some(true),
                rate_limit: Some(RateLimit {
                    rate: 100,
                    window: Duration::from_secs(1),
                }),
            }),
        ] {
            let c = caixa_aplicacao_with_politicas(politicas.clone());
            let first = c.politicas().unwrap();
            let second = c.politicas().unwrap();
            assert_eq!(
                first, second,
                "Caixa::politicas must be idempotent — two successive \
                 calls on the same &self must return the same \
                 &MeshPolicy",
            );
            assert!(
                std::ptr::eq(first, second),
                "Caixa::politicas must borrow the underlying \
                 Option<MeshPolicy> storage — two successive calls \
                 must return references with the same backing pointer \
                 (a fresh MeshPolicy clone would change the pointer on \
                 every call)",
            );
            assert_eq!(
                Some(first),
                politicas.as_ref(),
                "Caixa::politicas must return :politicas verbatim by \
                 borrow — got {first:?}, expected {:?}",
                politicas.as_ref(),
            );
        }
        let c = caixa_aplicacao_with_politicas(None);
        assert!(
            c.politicas().is_none(),
            "Caixa::politicas must return None when :politicas is \
             absent — the author-omitted arm must project through the \
             accessor's Option::None unchanged",
        );
    }

    // ── Caixa::placement — outer top-level Option<&Placement> composite-reference accessor ──

    fn caixa_aplicacao_with_placement(placement: Option<crate::aplicacao::Placement>) -> Caixa {
        use crate::aplicacao::{Membro, WitContract};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.kind = CaixaKind::Aplicacao;
        c.membros = vec![Membro {
            caixa: "a".into(),
            versao: "^0.1".into(),
        }];
        c.contratos = vec![WitContract {
            de: "a".into(),
            para: "a".into(),
            wit: "wasi:http/proxy".into(),
            endpoint: Some("/x".into()),
            subject: None,
            slot: None,
        }];
        c.placement = placement;
        c
    }

    #[test]
    fn placement_returns_placement_option_ref_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:placement` M3 mesh-slot outer-
        // composite optional-composite-reference-shape pin:
        // [`Caixa::placement`] must return the `:placement` typed
        // `Option<Placement>` verbatim as an `Option<&Placement>`
        // reference over the same backing storage the raw
        // `self.placement.as_ref()` field access borrows from,
        // byte-equal across every representative fixture in the
        // accept-set — the author-omitted `None` shape (the
        // "cluster-default applies" partition every downstream mesh-
        // artifact emitter treats as "emit no `:placement` overlay"),
        // the empty-composite `Some(Placement { .. default })` shape
        // (`estrategia: SingleNode`, empty clusters, no shard-key /
        // affinity — the outer presence-bit is `Some` so
        // [`Caixa::declared_mesh_slots`] still pushes the
        // `M3_AUTHOR_KEY_PLACEMENT` label), a single-axis
        // `Replicated`-on-two-clusters fixture (the canonical shape a
        // stateless HTTP Aplicacao carries), and a fully-populated
        // `Sharded`-with-shard-key-and-affinity fixture (the canonical
        // shape a stateful Akka-style cluster-sharding Aplicacao
        // carries).
        //
        // Pins against a future silent detour that returned a fresh-
        // cloned [`crate::aplicacao::Placement`] copy (which would
        // type-check via the `Clone` impl but silently break every
        // downstream caller that relied on the reference sharing the
        // composite's backing identity), a reference to an operator-
        // resolved overlay (the future per-cluster
        // `:placement-overrides` slot — its resolution must land at
        // exactly this accessor body, not silently divert the raw
        // slot away from the peer [`Caixa::declared_mesh_slots`]
        // enumerator's presence probe), a `None` →
        // `Some(Placement::default)` cluster-default projection (which
        // would collapse the load-bearing "author-omitted `:placement`
        // ⇒ cluster-default applies" partition the peer
        // [`Caixa::declared_mesh_slots`] enumerator and the peer
        // [`Caixa::aplicacao_view`] Aplicacao-composition seed both
        // read), or an axis-shuffled projection (a future detour that
        // swapped `clusters` and `affinity` through the accessor would
        // silently split the paired [`Caixa::aplicacao_view`] seed's
        // fold input from the sibling M3 mesh-artifact emitter's
        // projection input).
        //
        // Fourth outer top-level [`Caixa`] `Option<&Composite>`-return
        // composite-reference accessor pin on the substrate primitive
        // — peer of the sibling
        // `limits_returns_limits_option_ref_verbatim_across_permutations`
        // (b2bd9d7),
        // `behavior_returns_behavior_option_ref_verbatim_across_permutations`
        // (35d8b52), and
        // `politicas_returns_politicas_option_ref_verbatim_across_permutations`
        // (5d23d29) opening triad pins on the outer top-level
        // [`Caixa`] `Option<&Composite>`-return sub-family — extended
        // here to the second of the three M3 mesh-slot axes so the
        // opening four-fifths of the outer `Option<&Composite>` sub-
        // family carries the same "byte-equal, borrow-shared,
        // presence-bit-preserved" outer-accessor discipline.
        use crate::aplicacao::{Placement, PlacementStrategy};
        let fixtures: Vec<Option<Placement>> = vec![
            None,
            Some(Placement::default()),
            Some(Placement {
                estrategia: PlacementStrategy::Replicated,
                clusters: vec!["rio".into(), "sao-paulo".into()],
                affinity: None,
                shard_key: None,
            }),
            Some(Placement {
                estrategia: PlacementStrategy::Sharded,
                clusters: vec!["rio".into(), "sao-paulo".into(), "brasilia".into()],
                affinity: Some("data-locality".into()),
                shard_key: Some("$tenantId".into()),
            }),
        ];
        for placement in fixtures {
            let c = caixa_aplicacao_with_placement(placement.clone());
            assert_eq!(
                c.placement(),
                placement.as_ref(),
                "Caixa::placement must return :placement verbatim (got \
                 {:?}, expected {:?})",
                c.placement(),
                placement.as_ref(),
            );
            match (c.placement(), c.placement.as_ref()) {
                (Some(a), Some(b)) => assert!(
                    std::ptr::eq(a, b),
                    "Caixa::placement accessor and self.placement.as_ref() \
                     field access must borrow the same backing storage \
                     — the accessor is the substrate-primitive typed \
                     dispatch every downstream Aplicacao-distribution- \
                     overlay composite consumer must route through, and \
                     a reference-identity split would silently break \
                     every consumer that relied on the borrow sharing \
                     the composite's storage",
                ),
                (None, None) => {}
                _ => panic!(
                    "Caixa::placement presence bit must byte-equal \
                     self.placement.is_some() — a presence-bit drift \
                     would silently split the paired \
                     Caixa::aplicacao_view Aplicacao-composition seed's \
                     traversal head from the peer \
                     Caixa::declared_mesh_slots M3 declared-slot \
                     enumerator's presence probe",
                ),
            }
            assert_eq!(
                c.placement().is_some(),
                c.placement.is_some(),
                "Caixa::placement().is_some() must byte-equal \
                 self.placement.is_some() — a presence-bit drift would \
                 silently split every downstream Option<&Placement> \
                 consumer's partition on the cluster-default arm",
            );
        }
    }

    #[test]
    fn declared_mesh_slots_placement_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_mesh_slots`]'s
        // `:placement` presence-probe arm must key off
        // [`Caixa::placement`], not the raw `self.placement.is_some()`
        // field-probe. Structurally: a `Caixa { placement:
        // Some(Placement::default()), .. }` must still push
        // `M3_AUTHOR_KEY_PLACEMENT` onto the declared-slot list (the
        // presence bit is `Some`, so the M3 kind-coherence gate must
        // surface the slot as "declared" even when every per-axis
        // scalar defers to the cluster-default arm), and a `Caixa {
        // placement: None, .. }` must NOT push the label (the "author
        // omitted the slot entirely" partition). The pair jointly pins
        // the accessor + declared-slot enumerator composition: any
        // future silent detour that had the accessor collapse
        // `Some(Placement::default())` to `None` (a `.filter(|p|
        // p.clusters().is_empty().not())` projection) would silently
        // absorb the "declared but empty" arm at the accessor boundary
        // and the [`crate::LayoutError::MeshSlotsOnNonAplicacao`]
        // kind-coherence gate would silently accept a struct-literal
        // `Caixa` carrying the drift.
        //
        // Peer of the sibling
        // `declared_servico_slots_limits_arm_routes_through_accessor`
        // (b2bd9d7),
        // `declared_servico_slots_behavior_arm_routes_through_accessor`
        // (35d8b52), and
        // `declared_mesh_slots_politicas_arm_routes_through_accessor`
        // (5d23d29) composition pins on the sibling `:limits` /
        // `:behavior` / `:politicas` outer-`Option<&Composite>` arms
        // — same "the enumerator gate must route through the
        // substrate-primitive typed dispatch" discipline extended onto
        // the second of the three M3 mesh-slot axes so the
        // [`Caixa::declared_mesh_slots`] enumerator carries the same
        // routing invariant on the `:placement` arm as the peer
        // `:politicas` arm.
        use crate::aplicacao::Placement;
        let c = caixa_aplicacao_with_placement(Some(Placement::default()));
        let slots = c.declared_mesh_slots();
        assert!(
            slots.contains(&crate::render::M3_AUTHOR_KEY_PLACEMENT),
            "declared_mesh_slots must push M3_AUTHOR_KEY_PLACEMENT \
             when `:placement` is Some (even for Placement::default()) \
             — the accessor and the enumerator gate must route through \
             the same substrate-primitive typed dispatch on the outer \
             :placement presence bit (got slots={slots:?})",
        );
        let c = caixa_aplicacao_with_placement(None);
        let slots = c.declared_mesh_slots();
        assert!(
            !slots.contains(&crate::render::M3_AUTHOR_KEY_PLACEMENT),
            "declared_mesh_slots must NOT push M3_AUTHOR_KEY_PLACEMENT \
             when `:placement` is None — the author-omitted arm must \
             route through the accessor's None-return unchanged (got \
             slots={slots:?})",
        );
    }

    #[test]
    fn aplicacao_view_placement_arm_folds_through_accessor() {
        // Composition pin: [`Caixa::aplicacao_view`]'s per-`:placement`
        // Aplicacao-composition seed must fold through
        // [`Caixa::placement`], not the raw
        // `self.placement.clone().unwrap_or_default()` field-borrow.
        // Structurally: a `Caixa { placement: Some(Placement {
        // estrategia: Replicated, clusters: ["rio"], .. default }),
        // kind: Aplicacao, .. }` must surface a projected
        // [`crate::AplicacaoSpec`] whose `placement().estrategia()` +
        // `placement().clusters()` byte-equal the outer composite's
        // authored values (the fold must project the authored
        // composite verbatim), a `Caixa { placement:
        // Some(Placement::default()), kind: Aplicacao, .. }` must
        // surface an [`crate::AplicacaoSpec`] whose `placement()`
        // byte-equals [`crate::aplicacao::Placement::default`] (the
        // fold's empty-composite arm collapses to the same default
        // the author-omitted arm does), and a `Caixa { placement:
        // None, kind: Aplicacao, .. }` must surface an
        // [`crate::AplicacaoSpec`] whose `placement()` byte-equals
        // [`crate::aplicacao::Placement::default`] (the "author
        // omitted the slot entirely" arm folds through the
        // `unwrap_or_default` onto the cluster-default). The triad
        // jointly pins the accessor + Aplicacao-composition seed
        // composition: any future silent detour that had the accessor
        // divert the raw slot away from the seed's fold (an operator-
        // resolved overlay's default-fold arm silently differing from
        // the raw slot's default-fold arm) would silently split the
        // build-time distribution-artifact emission gate from the
        // caixa-mesh renderer's Aplicacao-view input at the
        // composition boundary.
        use crate::aplicacao::{Placement, PlacementStrategy};
        let c = caixa_aplicacao_with_placement(Some(Placement {
            estrategia: PlacementStrategy::Replicated,
            clusters: vec!["rio".into()],
            affinity: None,
            shard_key: None,
        }));
        let view = c.aplicacao_view().unwrap();
        assert_eq!(
            view.placement().estrategia(),
            PlacementStrategy::Replicated,
            "Caixa::aplicacao_view must fold the authored :placement \
             :estrategia scalar through the accessor verbatim onto the \
             projected AplicacaoSpec — a future silent detour at the \
             seed's fold arm would surface here as a projected-scalar \
             drift (got {:?})",
            view.placement().estrategia(),
        );
        assert_eq!(
            view.placement().clusters(),
            &["rio"],
            "Caixa::aplicacao_view must fold the authored :placement \
             :clusters list through the accessor verbatim onto the \
             projected AplicacaoSpec — a future silent detour at the \
             seed's fold arm would surface here as a projected-list \
             drift (got {:?})",
            view.placement().clusters(),
        );
        let c = caixa_aplicacao_with_placement(Some(Placement::default()));
        let view = c.aplicacao_view().unwrap();
        assert_eq!(
            view.placement(),
            &Placement::default(),
            "Caixa::aplicacao_view must fold Some(Placement::default()) \
             through the accessor onto Placement::default — the empty- \
             composite arm collapses to the same default the author- \
             omitted arm does (got {:?})",
            view.placement(),
        );
        let c = caixa_aplicacao_with_placement(None);
        let view = c.aplicacao_view().unwrap();
        assert_eq!(
            view.placement(),
            &Placement::default(),
            "Caixa::aplicacao_view must fold None through the accessor's \
             unwrap_or_default onto Placement::default — the author- \
             omitted arm must route through the accessor's None-return \
             unchanged (got {:?})",
            view.placement(),
        );
    }

    #[test]
    fn placement_projects_option_ref_by_borrow() {
        // The by-borrow pin: [`Caixa::placement`] returns
        // `Option<&Placement>` by borrow — the returned reference
        // borrows the underlying `Option<Placement>` storage of the
        // `:placement` slot and the accessor must not clone the
        // backing composite on every call. Peer of the sibling
        // `limits_projects_option_ref_by_borrow` (b2bd9d7),
        // `behavior_projects_option_ref_by_borrow` (35d8b52), and
        // `politicas_projects_option_ref_by_borrow` (5d23d29) by-borrow
        // pins on the outer top-level [`Caixa`]
        // `Option<&Composite>`-return sub-family — extended here to
        // the fourth axis of the same sub-family: the accessor's
        // returned reference must borrow from `&self` (the returned
        // reference's lifetime is tied to `&self`), and calling the
        // accessor twice on the same [`Caixa`] must yield references
        // that are pointer-equal (the underlying byte-buffer is the
        // storage `Placement`'s allocation, not a fresh copy) as well
        // as value-equal (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Placement` (which would type-check via the `Clone` impl
        // but silently clone on every call), a `&Placement` panic-
        // return on the `None` arm (which would collapse the load-
        // bearing `Option` presence-bit into a runtime panic), or a
        // one-arm-only accessor that returned a saturating composite
        // on some sentinel input.
        use crate::aplicacao::{Placement, PlacementStrategy};
        for placement in [
            Some(Placement::default()),
            Some(Placement {
                estrategia: PlacementStrategy::Sharded,
                clusters: vec!["rio".into(), "sao-paulo".into()],
                affinity: Some("data-locality".into()),
                shard_key: Some("$tenantId".into()),
            }),
        ] {
            let c = caixa_aplicacao_with_placement(placement.clone());
            let first = c.placement().unwrap();
            let second = c.placement().unwrap();
            assert_eq!(
                first, second,
                "Caixa::placement must be idempotent — two successive \
                 calls on the same &self must return the same \
                 &Placement",
            );
            assert!(
                std::ptr::eq(first, second),
                "Caixa::placement must borrow the underlying \
                 Option<Placement> storage — two successive calls \
                 must return references with the same backing pointer \
                 (a fresh Placement clone would change the pointer on \
                 every call)",
            );
            assert_eq!(
                Some(first),
                placement.as_ref(),
                "Caixa::placement must return :placement verbatim by \
                 borrow — got {first:?}, expected {:?}",
                placement.as_ref(),
            );
        }
        let c = caixa_aplicacao_with_placement(None);
        assert!(
            c.placement().is_none(),
            "Caixa::placement must return None when :placement is \
             absent — the author-omitted arm must project through the \
             accessor's Option::None unchanged",
        );
    }

    // ── Caixa::entrada — outer top-level Option<&Entrada> composite-reference accessor ──

    fn caixa_aplicacao_with_entrada(entrada: Option<crate::aplicacao::Entrada>) -> Caixa {
        use crate::aplicacao::{Membro, WitContract};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.kind = CaixaKind::Aplicacao;
        c.membros = vec![Membro {
            caixa: "a".into(),
            versao: "^0.1".into(),
        }];
        c.contratos = vec![WitContract {
            de: "a".into(),
            para: "a".into(),
            wit: "wasi:http/proxy".into(),
            endpoint: Some("/x".into()),
            subject: None,
            slot: None,
        }];
        c.entrada = entrada;
        c
    }

    #[test]
    fn entrada_returns_entrada_option_ref_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:entrada` M3 mesh-slot outer-
        // composite optional-composite-reference-shape pin:
        // [`Caixa::entrada`] must return the `:entrada` typed
        // `Option<Entrada>` verbatim as an `Option<&Entrada>`
        // reference over the same backing storage the raw
        // `self.entrada.as_ref()` field access borrows from,
        // byte-equal across every representative fixture in the
        // accept-set — the author-omitted `None` shape (the
        // "cluster-internal Aplicacao" partition every downstream
        // Gateway-API emitter treats as "emit no listener + no
        // HTTPRoute"), a bare-`host`/`para` minimum-composite fixture
        // (empty `paths` — the resolved-paths fallback the peer
        // [`crate::aplicacao::Entrada::resolved_paths`] cascade folds
        // onto the substrate catch-all), and a fully-populated
        // multi-path-with-non-default-port fixture (the canonical
        // shape a public HTTP Aplicacao carries).
        //
        // Pins against a future silent detour that returned a fresh-
        // cloned [`crate::aplicacao::Entrada`] copy (which would
        // type-check via the `Clone` impl but silently break every
        // downstream caller that relied on the reference sharing the
        // composite's backing identity), a reference to an operator-
        // resolved overlay (the future per-cluster
        // `:entrada-overrides` slot — its resolution must land at
        // exactly this accessor body, not silently divert the raw
        // slot away from the peer [`Caixa::declared_mesh_slots`]
        // enumerator's presence probe), or an axis-shuffled projection
        // (a future detour that swapped `host` and `para` through the
        // accessor would silently split the paired
        // [`Caixa::aplicacao_view`] seed's forward input from the
        // sibling M3 gateway-artifact emitter's projection input).
        //
        // Fifth and final outer top-level [`Caixa`]
        // `Option<&Composite>`-return composite-reference accessor pin
        // on the substrate primitive — peer of the sibling
        // `limits_returns_limits_option_ref_verbatim_across_permutations`
        // (b2bd9d7),
        // `behavior_returns_behavior_option_ref_verbatim_across_permutations`
        // (35d8b52),
        // `politicas_returns_politicas_option_ref_verbatim_across_permutations`
        // (5d23d29), and
        // `placement_returns_placement_option_ref_verbatim_across_permutations`
        // (4fb8074) opening tetrad pins on the outer top-level
        // [`Caixa`] `Option<&Composite>`-return sub-family — extended
        // here to the third and final M3 mesh-slot axis so the closed
        // outer `Option<&Composite>` sub-family carries the same
        // "byte-equal, borrow-shared, presence-bit-preserved" outer-
        // accessor discipline across all five arms.
        use crate::aplicacao::Entrada;
        let fixtures: Vec<Option<Entrada>> = vec![
            None,
            Some(Entrada {
                host: "checkout.quero.cloud".into(),
                para: "gateway".into(),
                paths: Vec::new(),
                port: crate::DEFAULT_SERVICO_PORT,
            }),
            Some(Entrada {
                host: "api.pleme.io".into(),
                para: "public-api".into(),
                paths: vec!["/v1".into(), "/v2".into()],
                port: 8080,
            }),
        ];
        for entrada in fixtures {
            let c = caixa_aplicacao_with_entrada(entrada.clone());
            assert_eq!(
                c.entrada(),
                entrada.as_ref(),
                "Caixa::entrada must return :entrada verbatim (got \
                 {:?}, expected {:?})",
                c.entrada(),
                entrada.as_ref(),
            );
            match (c.entrada(), c.entrada.as_ref()) {
                (Some(a), Some(b)) => assert!(
                    std::ptr::eq(a, b),
                    "Caixa::entrada accessor and self.entrada.as_ref() \
                     field access must borrow the same backing storage \
                     — the accessor is the substrate-primitive typed \
                     dispatch every downstream Aplicacao-external- \
                     gateway composite consumer must route through, and \
                     a reference-identity split would silently break \
                     every consumer that relied on the borrow sharing \
                     the composite's storage",
                ),
                (None, None) => {}
                _ => panic!(
                    "Caixa::entrada presence bit must byte-equal \
                     self.entrada.is_some() — a presence-bit drift \
                     would silently split the paired \
                     Caixa::aplicacao_view Aplicacao-composition seed's \
                     traversal head from the peer \
                     Caixa::declared_mesh_slots M3 declared-slot \
                     enumerator's presence probe",
                ),
            }
            assert_eq!(
                c.entrada().is_some(),
                c.entrada.is_some(),
                "Caixa::entrada().is_some() must byte-equal \
                 self.entrada.is_some() — a presence-bit drift would \
                 silently split every downstream Option<&Entrada> \
                 consumer's partition on the cluster-internal arm",
            );
        }
    }

    #[test]
    fn declared_mesh_slots_entrada_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_mesh_slots`]'s `:entrada`
        // presence-probe arm must key off [`Caixa::entrada`], not the
        // raw `self.entrada.is_some()` field-probe. Structurally: a
        // `Caixa { entrada: Some(Entrada { host: "...", para: "...",
        // paths: [], port: DEFAULT_SERVICO_PORT }), .. }` must push
        // `M3_AUTHOR_KEY_ENTRADA` onto the declared-slot list (the
        // presence bit is `Some`, so the M3 kind-coherence gate must
        // surface the slot as "declared" even when every per-axis
        // scalar defers to the substrate catch-all / default port),
        // and a `Caixa { entrada: None, .. }` must NOT push the label
        // (the "author omitted the slot entirely" partition). The pair
        // jointly pins the accessor + declared-slot enumerator
        // composition: any future silent detour that had the accessor
        // collapse `Some(Entrada { paths: [], .. })` to `None` (a
        // `.filter(|e| !e.paths.is_empty())` projection) would silently
        // absorb the "declared but empty-paths" arm at the accessor
        // boundary and the
        // [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-
        // coherence gate would silently accept a struct-literal
        // `Caixa` carrying the drift.
        //
        // Peer of the sibling
        // `declared_servico_slots_limits_arm_routes_through_accessor`
        // (b2bd9d7),
        // `declared_servico_slots_behavior_arm_routes_through_accessor`
        // (35d8b52),
        // `declared_mesh_slots_politicas_arm_routes_through_accessor`
        // (5d23d29), and
        // `declared_mesh_slots_placement_arm_routes_through_accessor`
        // (4fb8074) composition pins on the sibling `:limits` /
        // `:behavior` / `:politicas` / `:placement` outer-
        // `Option<&Composite>` arms — same "the enumerator gate must
        // route through the substrate-primitive typed dispatch"
        // discipline extended onto the third and final M3 mesh-slot
        // axis so the [`Caixa::declared_mesh_slots`] enumerator now
        // carries the routing invariant on every M3 mesh-slot arm.
        use crate::aplicacao::Entrada;
        let c = caixa_aplicacao_with_entrada(Some(Entrada {
            host: "checkout.quero.cloud".into(),
            para: "gateway".into(),
            paths: Vec::new(),
            port: crate::DEFAULT_SERVICO_PORT,
        }));
        let slots = c.declared_mesh_slots();
        assert!(
            slots.contains(&crate::render::M3_AUTHOR_KEY_ENTRADA),
            "declared_mesh_slots must push M3_AUTHOR_KEY_ENTRADA when \
             `:entrada` is Some (even for empty-paths / default-port) \
             — the accessor and the enumerator gate must route through \
             the same substrate-primitive typed dispatch on the outer \
             :entrada presence bit (got slots={slots:?})",
        );
        let c = caixa_aplicacao_with_entrada(None);
        let slots = c.declared_mesh_slots();
        assert!(
            !slots.contains(&crate::render::M3_AUTHOR_KEY_ENTRADA),
            "declared_mesh_slots must NOT push M3_AUTHOR_KEY_ENTRADA \
             when `:entrada` is None — the author-omitted arm must \
             route through the accessor's None-return unchanged (got \
             slots={slots:?})",
        );
    }

    #[test]
    fn aplicacao_view_entrada_arm_folds_through_accessor() {
        // Composition pin: [`Caixa::aplicacao_view`]'s per-`:entrada`
        // Aplicacao-composition seed must fold through
        // [`Caixa::entrada`], not the raw `self.entrada.clone()` field-
        // borrow. Structurally: a `Caixa { entrada: Some(Entrada {
        // host: "api.pleme.io", para: "public-api", paths: ["/v1"],
        // port: 8080 }), kind: Aplicacao, .. }` must surface a projected
        // [`crate::AplicacaoSpec`] whose `entrada().unwrap()` byte-
        // equals the outer composite's authored value (the fold must
        // project the authored composite verbatim), and a `Caixa {
        // entrada: None, kind: Aplicacao, .. }` must surface an
        // [`crate::AplicacaoSpec`] whose `entrada()` is `None` (the
        // "author omitted the slot entirely" arm folds through the
        // accessor's `Option::cloned` onto the same `None` presence
        // bit — unlike the peer `:politicas` / `:placement` arms
        // `:entrada` has no cluster-default fold, the omitted arm
        // stays omitted). The pair jointly pins the accessor +
        // Aplicacao-composition seed composition: any future silent
        // detour that had the accessor divert the raw slot away from
        // the seed's fold (an operator-resolved overlay's forward arm
        // silently differing from the raw slot's forward arm) would
        // silently split the build-time gateway-artifact emission gate
        // from the caixa-mesh renderer's Aplicacao-view input at the
        // composition boundary.
        use crate::aplicacao::Entrada;
        let authored = Entrada {
            host: "api.pleme.io".into(),
            para: "public-api".into(),
            paths: vec!["/v1".into()],
            port: 8080,
        };
        let c = caixa_aplicacao_with_entrada(Some(authored.clone()));
        let view = c.aplicacao_view().unwrap();
        assert_eq!(
            view.entrada(),
            Some(&authored),
            "Caixa::aplicacao_view must fold the authored :entrada \
             composite through the accessor verbatim onto the \
             projected AplicacaoSpec — a future silent detour at the \
             seed's fold arm would surface here as a projected- \
             composite drift (got {:?})",
            view.entrada(),
        );
        let c = caixa_aplicacao_with_entrada(None);
        let view = c.aplicacao_view().unwrap();
        assert!(
            view.entrada().is_none(),
            "Caixa::aplicacao_view must fold None through the \
             accessor's Option::cloned onto None — the author- \
             omitted arm must route through the accessor's None-return \
             unchanged (got {:?})",
            view.entrada(),
        );
    }

    #[test]
    fn entrada_projects_option_ref_by_borrow() {
        // The by-borrow pin: [`Caixa::entrada`] returns
        // `Option<&Entrada>` by borrow — the returned reference
        // borrows the underlying `Option<Entrada>` storage of the
        // `:entrada` slot and the accessor must not clone the backing
        // composite on every call. Peer of the sibling
        // `limits_projects_option_ref_by_borrow` (b2bd9d7),
        // `behavior_projects_option_ref_by_borrow` (35d8b52),
        // `politicas_projects_option_ref_by_borrow` (5d23d29), and
        // `placement_projects_option_ref_by_borrow` (4fb8074) by-
        // borrow pins on the outer top-level [`Caixa`]
        // `Option<&Composite>`-return sub-family — extended here to
        // the fifth and final axis of the same sub-family, closing
        // the discipline: the accessor's returned reference must
        // borrow from `&self` (the returned reference's lifetime is
        // tied to `&self`), and calling the accessor twice on the
        // same [`Caixa`] must yield references that are pointer-equal
        // (the underlying byte-buffer is the storage `Entrada`'s
        // allocation, not a fresh copy) as well as value-equal
        // (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Entrada` (which would type-check via the `Clone` impl but
        // silently clone on every call), a `&Entrada` panic-return on
        // the `None` arm (which would collapse the load-bearing
        // `Option` presence-bit into a runtime panic), or a one-arm-
        // only accessor that returned a saturating composite on some
        // sentinel input.
        use crate::aplicacao::Entrada;
        for entrada in [
            Some(Entrada {
                host: "checkout.quero.cloud".into(),
                para: "gateway".into(),
                paths: Vec::new(),
                port: crate::DEFAULT_SERVICO_PORT,
            }),
            Some(Entrada {
                host: "api.pleme.io".into(),
                para: "public-api".into(),
                paths: vec!["/v1".into(), "/v2".into()],
                port: 8080,
            }),
        ] {
            let c = caixa_aplicacao_with_entrada(entrada.clone());
            let first = c.entrada().unwrap();
            let second = c.entrada().unwrap();
            assert_eq!(
                first, second,
                "Caixa::entrada must be idempotent — two successive \
                 calls on the same &self must return the same &Entrada",
            );
            assert!(
                std::ptr::eq(first, second),
                "Caixa::entrada must borrow the underlying \
                 Option<Entrada> storage — two successive calls must \
                 return references with the same backing pointer (a \
                 fresh Entrada clone would change the pointer on every \
                 call)",
            );
            assert_eq!(
                Some(first),
                entrada.as_ref(),
                "Caixa::entrada must return :entrada verbatim by \
                 borrow — got {first:?}, expected {:?}",
                entrada.as_ref(),
            );
        }
        let c = caixa_aplicacao_with_entrada(None);
        assert!(
            c.entrada().is_none(),
            "Caixa::entrada must return None when :entrada is absent \
             — the author-omitted arm must project through the \
             accessor's Option::None unchanged",
        );
    }

    // ── Caixa::estrategia — outer top-level Option<RestartStrategy> flat-spread supervisor-tree accessor ──

    fn caixa_with_estrategia(estrategia: Option<crate::supervisor::RestartStrategy>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.estrategia = estrategia;
        c
    }

    #[test]
    fn estrategia_returns_estrategia_option_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:estrategia` M2 supervisor-tree-slot
        // flat-spread `Option<RestartStrategy>`-return `Copy`-composite-
        // enum-arm scalar shape pin: [`Caixa::estrategia`] must return
        // the `:estrategia` typed `Option<crate::supervisor::RestartStrategy>`
        // verbatim as an `Option<RestartStrategy>` `Copy`-projected value
        // over the same discriminant the raw `self.estrategia` field
        // access carries, byte-equal across every representative fixture
        // in the accept-set — the author-omitted `None` shape (the
        // "defer to [`RestartStrategy::default`] through the
        // [`Self::supervisor_view`] `unwrap_or_default()` fold" partition
        // every non-`Supervisor`-kind `defcaixa` carries by
        // `#[serde(default)]`), and each of the four closed-set variants
        // [`RestartStrategy::OneForOne`] / [`RestartStrategy::OneForAll`]
        // / [`RestartStrategy::RestForOne`] /
        // [`RestartStrategy::SimpleOneForOne`] the author-declared arm
        // partitions on.
        //
        // Pins against a future silent detour that re-derived the
        // strategy from a peer axis (an accidental fallback to
        // `if children.is_empty() { SimpleOneForOne } else { OneForOne }`
        // collapse that read the outer `:children` list-length axis into
        // the strategy discriminator at the accessor boundary), a
        // stale-derive detour that substituted [`RestartStrategy::default`]
        // when the outer `Option` held `None` (which would silently
        // collapse the load-bearing "author explicitly declared
        // `:estrategia OneForOne`" vs "author omitted the slot and
        // inherited the default" partition the [`Self::declared_supervisor_slots`]
        // presence-probe reads — the enumerator gate would still push
        // `SUPERVISOR_AUTHOR_KEY_ESTRATEGIA` on the omitted arm, silently
        // splitting the paired [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`]
        // kind-coherence gate's traversal head from the
        // [`Self::supervisor_view`] `unwrap_or_default()` fold's
        // composition head), a reference to an operator-resolved overlay
        // (the future per-cluster `:estrategia-overrides` slot — its
        // resolution must land at exactly this accessor body, not
        // silently divert the raw slot away from a second consumer), or
        // an axis-remap projection (a future detour that mapped
        // `OneForAll` through the accessor onto `OneForOne` would
        // silently split every downstream sibling-restart-strategy
        // consumer's per-arm fan-out).
        //
        // First outer top-level [`Caixa`] `Option<Copy>`-return
        // supervisor-tree-slot flat-spread accessor pin on the substrate
        // primitive — opens the outer-`Caixa` `Option<Copy>` flat-spread
        // projection pattern the sibling per-`Caixa` `:max-restarts` /
        // `:restart-window` future outer-scalar pins fold on. Peer of
        // the inner-altitude
        // `supervisor_spec_estrategia_returns_estrategia_verbatim_across_permutations`
        // (eafb619) pin on the post-composition [`SupervisorSpec`]
        // altitude — same "the substrate-primitive accessor must byte-
        // equal the raw field access verbatim across every author-
        // declared value" discipline extended onto the pre-composition
        // outer author-surface [`Caixa`] altitude. Peer of the closed
        // outer-`Caixa` `Option<&Composite>` composite-reference family
        // the sibling `limits` / `behavior` / `politicas` / `placement` /
        // `entrada`
        // `..._returns_..._option_ref_verbatim_across_permutations` pins
        // already carry on the outer `Option<&Composite>` altitude.
        use crate::supervisor::RestartStrategy;
        let fixtures: Vec<Option<RestartStrategy>> = vec![
            None,
            Some(RestartStrategy::OneForOne),
            Some(RestartStrategy::OneForAll),
            Some(RestartStrategy::RestForOne),
            Some(RestartStrategy::SimpleOneForOne),
        ];
        for estrategia in fixtures {
            let c = caixa_with_estrategia(estrategia);
            assert_eq!(
                c.estrategia(),
                estrategia,
                "Caixa::estrategia must return :estrategia verbatim (got \
                 {:?}, expected {:?})",
                c.estrategia(),
                estrategia,
            );
            assert_eq!(
                c.estrategia(),
                c.estrategia,
                "Caixa::estrategia accessor and self.estrategia field \
                 access must byte-equal — the accessor is the substrate-\
                 primitive typed dispatch every downstream supervisor-\
                 tree flat-spread consumer must route through, and a \
                 discriminant split would silently break every consumer \
                 that relied on the accessor sharing the field's own \
                 Option<Copy> shape",
            );
            assert_eq!(
                c.estrategia().is_some(),
                c.estrategia.is_some(),
                "Caixa::estrategia().is_some() must byte-equal \
                 self.estrategia.is_some() — a presence-bit drift would \
                 silently split the paired Caixa::declared_supervisor_slots \
                 presence-probe arm from the Caixa::supervisor_view \
                 unwrap_or_default() fold's composition input",
            );
        }
    }

    #[test]
    fn declared_supervisor_slots_estrategia_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_supervisor_slots`]'s
        // `:estrategia` presence-probe arm must key off
        // [`Caixa::estrategia`], not the raw `self.estrategia.is_some()`
        // field-probe. Structurally: every `Caixa { estrategia:
        // Some(RestartStrategy::_), .. }` variant must push
        // `SUPERVISOR_AUTHOR_KEY_ESTRATEGIA` onto the declared-slot list
        // (the presence bit is `Some` for every closed-set variant, so
        // the M2 supervisor-tree kind-coherence gate must surface the
        // slot as "declared" regardless of which variant the author
        // picked), and a `Caixa { estrategia: None, .. }` must NOT push
        // the label (the "author omitted the slot entirely, deferring
        // to [`RestartStrategy::default`] through the supervisor_view
        // fold" partition). The pair jointly pins the accessor +
        // declared-slot enumerator composition: any future silent detour
        // that had the accessor collapse `Some(RestartStrategy::default())`
        // to `None` (a `.filter(|e| *e != RestartStrategy::default())`
        // projection) would silently absorb the "declared but default-
        // valued" arm at the accessor boundary and the
        // [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`] kind-
        // coherence gate would silently accept a struct-literal `Caixa`
        // carrying the drift.
        //
        // Peer of the sibling per-`Caixa`
        // `declared_servico_slots_limits_arm_routes_through_accessor`
        // (b2bd9d7) accessor-composition pin on the sibling outer-`Caixa`
        // `Option<&LimitsSpec>` composition axis — same "the enumerator
        // gate must route through the substrate-primitive typed
        // dispatch" discipline extended onto the flat-spread M2
        // supervisor-tree `Option<RestartStrategy>`-composition surface,
        // opening the outer-`Caixa` supervisor-tree-slot arm of the
        // composition-pin family.
        use crate::supervisor::RestartStrategy;
        for estrategia in [
            RestartStrategy::OneForOne,
            RestartStrategy::OneForAll,
            RestartStrategy::RestForOne,
            RestartStrategy::SimpleOneForOne,
        ] {
            let c = caixa_with_estrategia(Some(estrategia));
            let slots = c.declared_supervisor_slots();
            assert!(
                slots.contains(&crate::render::SUPERVISOR_AUTHOR_KEY_ESTRATEGIA),
                "declared_supervisor_slots must push \
                 SUPERVISOR_AUTHOR_KEY_ESTRATEGIA when `:estrategia` is \
                 Some({estrategia:?}) — the accessor and the enumerator \
                 gate must route through the same substrate-primitive \
                 typed dispatch on the outer :estrategia presence bit \
                 (got slots={slots:?})",
            );
        }
        let c = caixa_with_estrategia(None);
        let slots = c.declared_supervisor_slots();
        assert!(
            !slots.contains(&crate::render::SUPERVISOR_AUTHOR_KEY_ESTRATEGIA),
            "declared_supervisor_slots must NOT push \
             SUPERVISOR_AUTHOR_KEY_ESTRATEGIA when `:estrategia` is None \
             — the author-omitted arm must route through the accessor's \
             None-return unchanged (got slots={slots:?})",
        );
    }

    #[test]
    fn supervisor_view_estrategia_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::supervisor_view`]'s per-`:estrategia`
        // [`SupervisorSpec`] construction arm must key off
        // [`Caixa::estrategia`]'s `unwrap_or_default()` fold, not the raw
        // `self.estrategia.unwrap_or_default()` field-fold. Structurally:
        // for every `:kind Supervisor` `Caixa` carrying an author-
        // declared `Some(RestartStrategy::_)` variant, the composed
        // [`SupervisorSpec`]'s `.estrategia` field must byte-equal the
        // outer accessor's declared variant unchanged; and for a
        // `:kind Supervisor` `Caixa` carrying `None`, the composed
        // [`SupervisorSpec`]'s `.estrategia` field must byte-equal
        // [`RestartStrategy::default`] (the [`RestartStrategy::OneForOne`]
        // arm the flat-spread `unwrap_or_default()` fold projects to on
        // the author-omitted arm — this is the *composition* between the
        // outer `Option<RestartStrategy>` accessor's presence-bit
        // surface and the inner post-composition non-`Option`
        // [`SupervisorSpec::estrategia`] altitude). The pair jointly
        // pins the accessor + supervisor_view composition: any future
        // silent detour that had the accessor promote `None` to
        // `Some(RestartStrategy::default())` (a `.or_else(|| Some(RestartStrategy::default()))`
        // projection) would silently collapse the two arms into one at
        // the accessor boundary and the [`Self::declared_supervisor_slots`]
        // presence probe would silently drift from the composition site.
        //
        // Peer of the sibling M2 supervisor-slot post-composition
        // `validate_reads_through_lifted_estrategia_accessor` (eafb619)
        // pin on the [`SupervisorSpec::validate`] altitude — this pin
        // extends that inner-altitude accessor-routing discipline onto
        // the pre-composition outer author-surface [`Caixa`] altitude,
        // pinning the composition edge between the flat-spread outer
        // `Option<RestartStrategy>` and the composed [`SupervisorSpec`]
        // `RestartStrategy` axes.
        use crate::CaixaKind;
        use crate::supervisor::{ChildSpec, RestartPolicy, RestartStrategy};
        for estrategia in [
            RestartStrategy::OneForOne,
            RestartStrategy::OneForAll,
            RestartStrategy::RestForOne,
            RestartStrategy::SimpleOneForOne,
        ] {
            let mut c = caixa_with_estrategia(Some(estrategia));
            c.kind = CaixaKind::Supervisor;
            // Route the `SimpleOneForOne ↔ non-SimpleOneForOne` fixture-
            // shape partition through the [`gen_platform::IsVariant`]
            // derive-generated
            // [`RestartStrategy::is_simple_one_for_one`] predicate rather
            // than the raw `matches!(estrategia, RestartStrategy::
            // SimpleOneForOne)` open-coded pattern-match — same closed-
            // set-typed-enum arm-discriminator dispatch discipline the
            // sibling [`crate::upgrade::UpgradeInstruction::is_restart`]
            // convergence (915a934) extended onto its two paired positive
            // / negated `matches!` sites and the peer
            // [`crate::aplicacao::PlacementStrategy`] `IsVariant`-derived
            // predicate convergence (766ec63) extended onto the M3 mesh-
            // slot per-`:placement` distribution-strategy discriminator
            // axis. See the sibling `supervisor::tests::
            // round_trip_all_strategies` and
            // `supervisor::tests::supervisor_spec_estrategia_returns_estrategia_verbatim_across_permutations`
            // fixtures — the three sites (all test-only,
            // acknowledged in 915a934's Prior-commits footnote as the
            // outstanding follow-up) now consult one typed dispatch on
            // the substrate primitive.
            c.children = if estrategia.is_simple_one_for_one() {
                Vec::new()
            } else {
                vec![ChildSpec {
                    caixa: "worker".into(),
                    versao: "^0.1".into(),
                    restart: RestartPolicy::Permanent,
                }]
            };
            let view = c.supervisor_view().expect(
                "supervisor_view must materialize a SupervisorSpec for a \
                 :kind Supervisor Caixa carrying a Some(:estrategia) slot",
            );
            assert_eq!(
                view.estrategia(),
                c.estrategia().unwrap(),
                "supervisor_view must carry the outer Caixa::estrategia() \
                 declared variant onto the composed SupervisorSpec.estrategia \
                 field verbatim on the Some arm (got {:?}, expected {:?})",
                view.estrategia(),
                c.estrategia().unwrap(),
            );
        }
        // The author-omitted arm: outer `None` → composed
        // `RestartStrategy::default()` through the flat-spread
        // `unwrap_or_default()` fold.
        let mut c = caixa_with_estrategia(None);
        c.kind = CaixaKind::Supervisor;
        // Populate children so the sibling supervisor slots are coherent
        // for the [`Self::supervisor_view`] projection; the `:estrategia`
        // arm still defers to [`RestartStrategy::default`] on the
        // author-omitted arm even when the sibling slots carry values.
        c.children = vec![ChildSpec {
            caixa: "worker".into(),
            versao: "^0.1".into(),
            restart: RestartPolicy::Permanent,
        }];
        let view = c.supervisor_view().expect(
            "supervisor_view must materialize a SupervisorSpec for a \
             :kind Supervisor Caixa carrying a None `:estrategia` slot",
        );
        assert_eq!(
            view.estrategia(),
            RestartStrategy::default(),
            "supervisor_view must project the outer Caixa::estrategia() \
             None arm onto RestartStrategy::default() through the flat-\
             spread unwrap_or_default() fold (got {:?}, expected {:?})",
            view.estrategia(),
            RestartStrategy::default(),
        );
        assert!(
            c.estrategia().is_none(),
            "Caixa::estrategia() must remain None on the author-omitted \
             arm — the supervisor_view fold must not mutate the outer \
             flat-spread presence bit",
        );
    }

    #[test]
    fn estrategia_projects_option_by_copy() {
        // The by-`Copy` pin: [`Caixa::estrategia`] returns
        // `Option<RestartStrategy>` by value (`RestartStrategy: Copy`) —
        // the accessor does not borrow `&self` past the call (no
        // lifetime on the return type), and calling the accessor twice
        // on the same [`Caixa`] must yield discriminant-equal values
        // (idempotent, no side effects on `&self`). Peer of the sibling
        // outer-`Caixa` `Option<&Composite>` by-borrow
        // `limits_projects_option_ref_by_borrow` (b2bd9d7) /
        // `behavior_projects_option_ref_by_borrow` (35d8b52) /
        // `politicas_projects_option_ref_by_borrow` (5d23d29) /
        // `placement_projects_option_ref_by_borrow` (4fb8074) /
        // `entrada_projects_option_ref_by_borrow` (e4128e4) by-borrow
        // pins on the outer-`Caixa` `Option<&Composite>`-return axes —
        // extended here to the outer-`Caixa` `Option<Copy>`-return
        // flat-spread axis. The `Copy` discipline replaces the pointer-
        // equality claim the by-borrow siblings pin (a fresh `Copy` of a
        // `Copy` discriminant is definitionally the same discriminant, so
        // the axis reduces to discriminant equality).
        //
        // Pins against a future silent detour that returned a fresh
        // `Option<&RestartStrategy>` (which would type-check but silently
        // introduce a borrow of `&self` past the call, collapsing the
        // load-bearing "no lifetime on the return type" `Copy` projection
        // the flat-spread axis's `Option<Copy>` shape carries), a stale-
        // read side effect that flipped the outer discriminant on
        // successive calls, or an axis-remap projection that returned a
        // different variant than the field storage.
        use crate::supervisor::RestartStrategy;
        for estrategia in [
            Some(RestartStrategy::OneForOne),
            Some(RestartStrategy::OneForAll),
            Some(RestartStrategy::RestForOne),
            Some(RestartStrategy::SimpleOneForOne),
        ] {
            let c = caixa_with_estrategia(estrategia);
            let first = c.estrategia();
            let second = c.estrategia();
            assert_eq!(
                first, second,
                "Caixa::estrategia must be idempotent — two successive \
                 calls on the same &self must return the same \
                 Option<RestartStrategy>",
            );
            assert_eq!(
                first, estrategia,
                "Caixa::estrategia must return :estrategia verbatim by \
                 Copy — got {first:?}, expected {estrategia:?}",
            );
        }
        let c = caixa_with_estrategia(None);
        assert!(
            c.estrategia().is_none(),
            "Caixa::estrategia must return None when :estrategia is \
             absent — the author-omitted arm must project through the \
             accessor's Option::None unchanged",
        );
    }

    // ── Caixa::max_restarts / Caixa::restart_window —
    //    outer top-level M2 supervisor-tree-slot flat-spread accessors
    //    (Option<u32> / Option<&str>) folding on the ed04d3c
    //    Caixa::estrategia Option<Copy> sub-family ─────────────────────

    fn caixa_with_max_restarts(max_restarts: Option<u32>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.max_restarts = max_restarts;
        c
    }

    fn caixa_supervisor_with_max_restarts_and_window(
        max_restarts: Option<u32>,
        restart_window: Option<&str>,
    ) -> Caixa {
        use crate::CaixaKind;
        use crate::supervisor::{ChildSpec, RestartPolicy};
        let mut c = Caixa::from_lisp(&Caixa::template("root")).unwrap();
        c.kind = CaixaKind::Supervisor;
        c.max_restarts = max_restarts;
        c.restart_window = restart_window.map(str::to_string);
        c.children = vec![ChildSpec {
            caixa: "worker".into(),
            versao: "^0.1".into(),
            restart: RestartPolicy::Permanent,
        }];
        c
    }

    #[test]
    fn max_restarts_returns_max_restarts_option_verbatim_across_permutations() {
        // Value-shape pin: [`Caixa::max_restarts`] returns the
        // `:max-restarts` typed `Option<u32>` verbatim, `Copy`-projected
        // from the typed slot's own storage, byte-equal across the
        // author-omitted `None` arm (the "defer to the
        // [`Self::supervisor_view`] `unwrap_or(5)` OTP-canonical
        // `{intensity, 5, 60}` default" partition every
        // non-`Supervisor`-kind caixa carries by `#[serde(default)]`)
        // and each of the representative fixtures in the accept-set —
        // `0` (the zero-floor arm the peer
        // [`crate::supervisor::SupervisorSpec::validate`]
        // [`crate::SupervisorError::ZeroMaxRestarts`] gate refuses on
        // the post-composition altitude — the accessor must ship the
        // raw slot verbatim so struct-literal fixtures continue to
        // expose the zero at the accessor boundary), the OTP-canonical
        // `5` default (`{intensity, 5, 60}` worker-supervisor from
        // Learn You Some Erlang), `1000` (the
        // [`SUPERVISOR_MAX_RESTARTS_MAX`] cap the peer post-composition
        // upper-bound gate accepts on the boundary), `u32::MAX` (a
        // past-the-cap sentinel that the substrate-primitive accessor
        // must still ship verbatim). Second outer top-level
        // [`Caixa`] `Option<Copy>`-return supervisor-tree flat-spread
        // pin — folds on the sibling
        // `estrategia_returns_estrategia_option_verbatim_across_permutations`
        // (ed04d3c) pin's `Option<Copy>` shape, extending the sub-family
        // onto the sibling `Option<u32>` restart-budget-count arm.
        let fixtures: Vec<Option<u32>> = vec![None, Some(0), Some(5), Some(1000), Some(u32::MAX)];
        for max_restarts in fixtures {
            let c = caixa_with_max_restarts(max_restarts);
            assert_eq!(
                c.max_restarts(),
                max_restarts,
                "Caixa::max_restarts must return :max-restarts verbatim \
                 (got {:?}, expected {max_restarts:?})",
                c.max_restarts(),
            );
            assert_eq!(
                c.max_restarts(),
                c.max_restarts,
                "Caixa::max_restarts accessor and self.max_restarts \
                 field access must byte-equal — a presence-bit or count \
                 drift would silently split the paired \
                 Caixa::declared_supervisor_slots presence-probe arm \
                 from the Caixa::supervisor_view unwrap_or(5) fold's \
                 composition input",
            );
        }
    }

    #[test]
    fn max_restarts_projects_option_by_copy() {
        // The by-`Copy` pin: [`Caixa::max_restarts`] returns
        // `Option<u32>` by value (`u32: Copy`) — the accessor does not
        // borrow `&self` past the call (no lifetime on the return type),
        // and calling the accessor twice on the same [`Caixa`] must
        // yield equal values (idempotent, no side effects). Peer of the
        // sibling `estrategia_projects_option_by_copy` (ed04d3c) pin on
        // the outer-`Caixa` `Option<Copy>`-return flat-spread axis.
        for max_restarts in [Some(0u32), Some(5), Some(1000), Some(u32::MAX), None] {
            let c = caixa_with_max_restarts(max_restarts);
            let first = c.max_restarts();
            let second = c.max_restarts();
            assert_eq!(
                first, second,
                "Caixa::max_restarts must be idempotent — two successive \
                 calls on the same &self must return the same Option<u32>",
            );
            assert_eq!(
                first, max_restarts,
                "Caixa::max_restarts must return :max-restarts verbatim \
                 by Copy — got {first:?}, expected {max_restarts:?}",
            );
        }
    }

    #[test]
    fn declared_supervisor_slots_max_restarts_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_supervisor_slots`]'s
        // `:max-restarts` presence-probe arm must key off
        // [`Caixa::max_restarts`], not the raw
        // `self.max_restarts.is_some()` field-probe. Structurally: every
        // `Caixa { max_restarts: Some(_), .. }` variant must push
        // `SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS` onto the declared-slot
        // list (the presence bit is `Some` for every representative
        // count, so the M2 kind-coherence gate must surface the slot as
        // "declared"), and a `Caixa { max_restarts: None, .. }` must
        // NOT push the label. Peer of the sibling
        // `declared_supervisor_slots_estrategia_arm_routes_through_accessor`
        // (ed04d3c) composition pin — same routing-through-accessor
        // discipline extended onto the sibling flat-spread `Option<u32>`
        // arm.
        for max_restarts in [0u32, 5, 1000, u32::MAX] {
            let c = caixa_with_max_restarts(Some(max_restarts));
            let slots = c.declared_supervisor_slots();
            assert!(
                slots.contains(&crate::render::SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS),
                "declared_supervisor_slots must push \
                 SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS when `:max-restarts` \
                 is Some({max_restarts}) — the accessor and the \
                 enumerator gate must route through the same \
                 substrate-primitive typed dispatch on the outer \
                 :max-restarts presence bit (got slots={slots:?})",
            );
        }
        let c = caixa_with_max_restarts(None);
        let slots = c.declared_supervisor_slots();
        assert!(
            !slots.contains(&crate::render::SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS),
            "declared_supervisor_slots must NOT push \
             SUPERVISOR_AUTHOR_KEY_MAX_RESTARTS when `:max-restarts` is \
             None — the author-omitted arm must route through the \
             accessor's None-return unchanged (got slots={slots:?})",
        );
    }

    #[test]
    fn supervisor_view_max_restarts_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::supervisor_view`]'s per-`:max-restarts`
        // [`SupervisorSpec`] construction arm must key off
        // [`Caixa::max_restarts`]'s `unwrap_or(5)` fold, not the raw
        // `self.max_restarts.unwrap_or(5)` field-fold. Structurally: for
        // every `:kind Supervisor` `Caixa` carrying an author-declared
        // `Some(n)`, the composed [`SupervisorSpec`]'s `.max_restarts()`
        // must byte-equal `n`; and for a `:kind Supervisor` `Caixa`
        // carrying `None`, the composed [`SupervisorSpec`]'s
        // `.max_restarts()` must byte-equal the OTP-canonical `5`. Peer
        // of the sibling
        // `supervisor_view_estrategia_arm_routes_through_accessor`
        // (ed04d3c) composition pin.
        for max_restarts in [1u32, 5, 1000] {
            let c = caixa_supervisor_with_max_restarts_and_window(Some(max_restarts), None);
            let view = c.supervisor_view().expect(
                "supervisor_view must materialize a SupervisorSpec for a \
                 :kind Supervisor Caixa carrying a Some(:max-restarts)",
            );
            assert_eq!(
                view.max_restarts(),
                max_restarts,
                "supervisor_view must carry the outer \
                 Caixa::max_restarts() Some arm onto the composed \
                 SupervisorSpec.max_restarts field verbatim (got {}, \
                 expected {max_restarts})",
                view.max_restarts(),
            );
        }
        let c = caixa_supervisor_with_max_restarts_and_window(None, None);
        let view = c.supervisor_view().expect(
            "supervisor_view must materialize a SupervisorSpec for a \
             :kind Supervisor Caixa carrying a None :max-restarts",
        );
        assert_eq!(
            view.max_restarts(),
            5,
            "supervisor_view must project the outer \
             Caixa::max_restarts() None arm onto the OTP-canonical \
             {{intensity, 5, 60}} default (5) through the flat-spread \
             unwrap_or(5) fold (got {})",
            view.max_restarts(),
        );
        assert!(
            c.max_restarts().is_none(),
            "Caixa::max_restarts() must remain None on the author-\
             omitted arm — the supervisor_view fold must not mutate \
             the outer flat-spread presence bit",
        );
    }

    #[test]
    fn supervisor_view_estrategia_fallback_routes_through_lifted_default() {
        // Composition pin: [`Caixa::supervisor_view`]'s author-omitted
        // `:estrategia` arm must degrade onto the substrate-canonical
        // [`crate::supervisor::SUPERVISOR_ESTRATEGIA_DEFAULT`] typed
        // `pub const` — the Erlang/OTP-canonical `one_for_one` strategy
        // half of Learn You Some Erlang's `{one_for_one, intensity, 5, 60}`
        // worker-supervisor default — rather than the transitively-
        // derived [`crate::supervisor::RestartStrategy::default`] route
        // the prior `.unwrap_or_default()` fold reached for. Prior to the
        // lift the composition site carried `.unwrap_or_default()` with
        // no compile-time link back to the shared OTP-canonical strategy
        // default that the paired [`crate::supervisor::Default for
        // RestartStrategy`] impl and the [`crate::supervisor::Default for
        // SupervisorSpec`] impl's struct-literal `estrategia` field both
        // (now) route through the same lifted constant — so a future
        // rebrand of the OTP-canonical strategy default (an OTP
        // `rest_for_one` widening once the substrate discovers startup-
        // order-coupled child cohorts as the more common worker-
        // supervisor shape, a per-cluster overlay the operator pins
        // through the MESH-COMPOSITION §III.2 supervision-canary
        // `:estrategia-overrides` roadmap slot) would have had to migrate
        // the paired `MaxIntensity` + `Period` halves through the lifted
        // constants and the `one_for_one` half through a
        // `RestartStrategy::default()` route in lockstep or a
        // `:kind Supervisor` caixa carrying an author-omitted
        // `:estrategia` slot would silently resolve to a `SupervisorSpec`
        // whose `estrategia` disagreed with the paired
        // `SupervisorSpec::default()` view. Byte-parity against the
        // lifted constant closes the split. Peer of the sibling
        // [`supervisor_view_max_restarts_fallback_routes_through_lifted_default`]
        // composition pin on the paired `MaxIntensity` half + the
        // [`crate::supervisor::restart_strategy_default_routes_through_lifted_default`]
        // + [`crate::supervisor::supervisor_spec_default_estrategia_routes_through_lifted_default`]
        // pins on the sibling entry points onto the shared substrate
        // constant.
        use crate::CaixaKind;
        use crate::supervisor::{ChildSpec, RestartPolicy};
        let mut c = Caixa::from_lisp(&Caixa::template("root")).unwrap();
        c.kind = CaixaKind::Supervisor;
        c.estrategia = None;
        c.children = vec![ChildSpec {
            caixa: "worker".into(),
            versao: "^0.1".into(),
            restart: RestartPolicy::Permanent,
        }];
        let view = c.supervisor_view().expect(
            "supervisor_view must materialize a SupervisorSpec for a \
             :kind Supervisor Caixa carrying a None :estrategia",
        );
        assert_eq!(
            view.estrategia(),
            crate::supervisor::SUPERVISOR_ESTRATEGIA_DEFAULT,
            "supervisor_view must degrade the outer \
             Caixa::estrategia() None arm onto the lifted \
             SUPERVISOR_ESTRATEGIA_DEFAULT typed pub const (got {:?}, \
             expected {:?})",
            view.estrategia(),
            crate::supervisor::SUPERVISOR_ESTRATEGIA_DEFAULT,
        );
    }

    #[test]
    fn supervisor_view_max_restarts_fallback_routes_through_lifted_default() {
        // Composition pin: [`Caixa::supervisor_view`]'s author-omitted
        // `:max-restarts` arm must degrade onto the substrate-canonical
        // [`crate::supervisor::SUPERVISOR_MAX_RESTARTS_DEFAULT`] typed
        // `pub const` — the Erlang/OTP-canonical `{intensity, 5, 60}`
        // `MaxIntensity` default — rather than a raw `5` literal. Prior
        // to the lift the composition site carried an inline
        // `.unwrap_or(5)` with no compile-time link back to the shared
        // OTP-canonical default that the serde-side
        // `#[serde(default = "default_max_restarts")]` wire-format arm
        // and the [`Default for crate::supervisor::SupervisorSpec`]
        // struct-literal default arm both key off — so a future rebrand
        // of the OTP-canonical default (Elixir's `Supervisor` `3`
        // default, a per-cluster overlay the operator pins through the
        // MESH-COMPOSITION §III.2 supervision-canary
        // `:supervisor :max-restarts-overrides` roadmap slot) would
        // have had to be threaded through both the serde-side helper
        // and this view-construction arm in lockstep or a `:kind
        // Supervisor` caixa carrying `:max-restarts ()` would silently
        // resolve to a `SupervisorSpec` whose `max_restarts` disagreed
        // with the same fixture's serde-side `SupervisorSpec` view (an
        // author-omitted slot round-tripping through
        // `SupervisorSpec::default()` to the lifted constant, then
        // splitting to a stale literal past `supervisor_view`).
        // Byte-parity against the lifted constant closes the split.
        // Peer of the sibling
        // [`crate::supervisor::default_max_restarts_helper_routes_through_lifted_default`]
        // + [`crate::supervisor::supervisor_spec_default_max_restarts_routes_through_lifted_default`]
        // composition pins that close the same routing on the two
        // sibling entry points onto the shared substrate constant.
        let c = caixa_supervisor_with_max_restarts_and_window(None, None);
        let view = c.supervisor_view().expect(
            "supervisor_view must materialize a SupervisorSpec for a \
             :kind Supervisor Caixa carrying a None :max-restarts",
        );
        assert_eq!(
            view.max_restarts(),
            crate::supervisor::SUPERVISOR_MAX_RESTARTS_DEFAULT,
            "supervisor_view must degrade the outer \
             Caixa::max_restarts() None arm onto the lifted \
             SUPERVISOR_MAX_RESTARTS_DEFAULT typed pub const (got {}, \
             expected {})",
            view.max_restarts(),
            crate::supervisor::SUPERVISOR_MAX_RESTARTS_DEFAULT,
        );
    }

    #[test]
    fn restart_window_returns_restart_window_option_verbatim_across_permutations() {
        // Value-shape pin: [`Caixa::restart_window`] returns the
        // `:restart-window` typed `Option<String>` verbatim as an
        // `Option<&str>`, borrowed from the typed slot's own storage,
        // byte-equal across the author-omitted `None` arm and each of
        // the representative fixtures in the accept-set — the canonical
        // `"60s"` from `{intensity, 5, 60}`, the sibling
        // canonical-magnitude forms (`"5m"` / `"1h"` / `"500ms"` / `"30"`
        // / `"0s"`) the shared codec's positive-set sweep pin covers,
        // plus a past-the-guard sentinel (`"1.5s"` — the fractional-
        // seconds drift the sibling [`Self::validate_restart_window`]
        // gate refuses; the accessor must ship the raw slot verbatim
        // so struct-literal fixtures continue to expose the drift at
        // the accessor boundary). Third outer top-level [`Caixa`]
        // supervisor-tree flat-spread pin — extends the sub-family onto
        // the sibling `Option<&str>` raw-duration-string arm.
        for window in [
            None,
            Some("60s"),
            Some("5m"),
            Some("1h"),
            Some("500ms"),
            Some("1.5s"),
            Some(""),
        ] {
            let c = caixa_with_restart_window(window);
            assert_eq!(
                c.restart_window(),
                window,
                "Caixa::restart_window must return :restart-window \
                 verbatim as Option<&str> (got {:?}, expected {window:?})",
                c.restart_window(),
            );
            assert_eq!(
                c.restart_window(),
                c.restart_window.as_deref(),
                "Caixa::restart_window accessor and \
                 self.restart_window.as_deref() field access must \
                 byte-equal — a byte-level drift would silently split \
                 the paired Caixa::declared_supervisor_slots \
                 presence-probe arm from the \
                 Caixa::validate_restart_window shared-codec gate and \
                 the Caixa::supervisor_view soft-swallowing fold",
            );
        }
    }

    #[test]
    fn restart_window_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::restart_window`] returns
        // `Option<&str>` by borrow — the returned string slice borrows
        // the underlying `Option<String>` storage of the `:restart-window`
        // slot and the accessor must not clone on every call. Peer of
        // the sibling outer top-level [`Caixa`] `Option<&str>`-return
        // by-borrow pins on the universal-axis scalar family
        // (`licenca_projects_option_ref_by_borrow` /
        // `descricao_projects_option_ref_by_borrow` and siblings) —
        // extended onto the M2 supervisor-tree flat-spread
        // `Option<&str>` raw-duration-string axis.
        for window in [None, Some("60s"), Some("5m"), Some("")] {
            let c = caixa_with_restart_window(window);
            let first = c.restart_window();
            let second = c.restart_window();
            assert_eq!(
                first, second,
                "Caixa::restart_window must be idempotent — two \
                 successive calls on the same &self must return the \
                 same Option<&str>",
            );
            if let (Some(a), Some(b)) = (first, second) {
                assert_eq!(
                    a.as_ptr(),
                    b.as_ptr(),
                    "Caixa::restart_window must borrow the underlying \
                     String storage — two successive Some-arm calls must \
                     return slices with the same backing pointer (a fresh \
                     String clone would change the pointer on every call)",
                );
            }
            assert_eq!(
                first, window,
                "Caixa::restart_window must return :restart-window \
                 verbatim by borrow — got {first:?}, expected {window:?}",
            );
        }
    }

    #[test]
    fn declared_supervisor_slots_restart_window_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_supervisor_slots`]'s
        // `:restart-window` presence-probe arm must key off
        // [`Caixa::restart_window`], not the raw
        // `self.restart_window.is_some()` field-probe. Structurally:
        // every `Caixa { restart_window: Some(_), .. }` must push
        // `SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW` onto the declared-slot
        // list, and a `Caixa { restart_window: None, .. }` must NOT
        // push the label. Peer of the sibling
        // `declared_supervisor_slots_max_restarts_arm_routes_through_accessor`
        // routing pin.
        for window in ["60s", "5m", "1h", "500ms", "1.5s", ""] {
            let c = caixa_with_restart_window(Some(window));
            let slots = c.declared_supervisor_slots();
            assert!(
                slots.contains(&crate::render::SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW),
                "declared_supervisor_slots must push \
                 SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW when \
                 `:restart-window` is Some({window:?}) — the accessor \
                 and the enumerator gate must route through the same \
                 substrate-primitive typed dispatch on the outer \
                 :restart-window presence bit (got slots={slots:?})",
            );
        }
        let c = caixa_with_restart_window(None);
        let slots = c.declared_supervisor_slots();
        assert!(
            !slots.contains(&crate::render::SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW),
            "declared_supervisor_slots must NOT push \
             SUPERVISOR_AUTHOR_KEY_RESTART_WINDOW when `:restart-window` \
             is None — the author-omitted arm must route through the \
             accessor's None-return unchanged (got slots={slots:?})",
        );
    }

    #[test]
    fn validate_restart_window_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::validate_restart_window`]'s
        // shared-codec fold arm must key off [`Caixa::restart_window`],
        // not the raw `self.restart_window.as_deref()` field-projection.
        // Structurally: (1) `None` → `Ok(())` (the "omit the slot to
        // express no reset" canonical shape); (2) a canonical `Some`
        // arm (`"60s"`) → `Ok(())`; (3) a codec-rejected `Some` arm
        // (`"1.5s"`) → `Err(RestartWindowMalformed { restart_window,
        // .. })` carrying the offending raw string verbatim. The three
        // arms jointly pin that the validator's raw-string binding is
        // the accessor's return, not a peer projection — any future
        // silent detour that had the accessor collapse `Some("")` to
        // `None` would silently absorb the empty-after-trim refusal
        // case at the accessor boundary.
        caixa_with_restart_window(None)
            .validate_restart_window()
            .expect("None :restart-window must validate through the accessor");
        caixa_with_restart_window(Some("60s"))
            .validate_restart_window()
            .expect("canonical :restart-window \"60s\" must validate through the accessor");
        let err = caixa_with_restart_window(Some("1.5s"))
            .validate_restart_window()
            .expect_err("fractional-seconds :restart-window must fail through the accessor");
        assert!(
            matches!(
                err,
                ManifestError::RestartWindowMalformed { ref restart_window, .. }
                    if restart_window == "1.5s"
            ),
            "validator must carry the offending raw string verbatim \
             from the accessor's borrowed &str (got {err:?})",
        );
    }

    #[test]
    fn supervisor_view_restart_window_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::supervisor_view`]'s
        // per-`:restart-window` [`SupervisorSpec`] construction arm
        // must key off [`Caixa::restart_window`]'s soft-swallowing
        // `.and_then(|s| duration_codec::parse(s).ok())` fold, not the
        // raw `self.restart_window.as_deref().and_then(…)` field-fold.
        // Structurally: (1) `None` → `SupervisorSpec.restart_window ==
        // None` (the "never reset" sentinel); (2) canonical `Some("60s")`
        // → `SupervisorSpec.restart_window == Some(Duration::from_secs(60))`
        // (the shared codec's canonical parse); (3) codec-rejected
        // `Some("1.5s")` → `SupervisorSpec.restart_window == None`
        // (the soft-swallow preserving the view's best-effort shape).
        let c = caixa_supervisor_with_max_restarts_and_window(None, None);
        let view = c.supervisor_view().expect("Supervisor kind has a view");
        assert_eq!(
            view.restart_window(),
            None,
            "supervisor_view must project outer None :restart-window \
             onto None on the composed SupervisorSpec (never-reset \
             sentinel) through the accessor's None-return unchanged",
        );

        let c = caixa_supervisor_with_max_restarts_and_window(None, Some("60s"));
        let view = c.supervisor_view().expect("Supervisor kind has a view");
        assert_eq!(
            view.restart_window(),
            Some(std::time::Duration::from_secs(60)),
            "supervisor_view must fold outer Some(\"60s\") through the \
             shared duration_codec into Duration::from_secs(60) on the \
             composed SupervisorSpec (accessor's Some(&str) → codec \
             parse → Some(Duration))",
        );

        let c = caixa_supervisor_with_max_restarts_and_window(None, Some("1.5s"));
        let view = c.supervisor_view().expect("Supervisor kind has a view");
        assert_eq!(
            view.restart_window(),
            None,
            "supervisor_view must soft-swallow the shared-codec parse \
             failure to None (the view's best-effort shape the sibling \
             manifest-level validate_restart_window surfaces as \
             RestartWindowMalformed); the accessor's raw-string return \
             is the single input every downstream consumer keys off",
        );
    }

    // ── Caixa::upgrade_from — outer top-level &[UpgradeFromEntry] composite-slice accessor ──

    fn caixa_with_upgrade_from(upgrade_from: Vec<crate::upgrade::UpgradeFromEntry>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.upgrade_from = upgrade_from;
        c
    }

    #[test]
    fn upgrade_from_returns_upgrade_from_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:upgrade-from` M2 typed-slot
        // outer-composite `&[UpgradeFromEntry]`-return slice-shape
        // pin: [`Caixa::upgrade_from`] must return the `:upgrade-from`
        // typed `Vec<UpgradeFromEntry>` verbatim as a
        // `&[UpgradeFromEntry]` slice-view over the same backing
        // buffer the raw `self.upgrade_from.as_slice()` field access
        // borrows from, element-equal across every representative
        // fixture in the accept-set — `[]` (the "no hot-upgrade path
        // declared" arm every `defcaixa` without an `:upgrade-from`
        // block carries; `#[serde(default)]` folds an omitted slot
        // onto `Vec::new()`), a canonical single-entry `Restart`
        // fixture (the shape most Servicos carry — a single prior
        // version with the fallback strategy), a canonical multi-
        // entry list carrying every typed instruction variant
        // (`LoadModule` / `StateChange` / `SoftPurge` / `Purge` /
        // `Restart`), and a past-the-guard sentinel — a duplicate-
        // `:from` `[(0.1.0, Restart), (0.1.0, Restart)]` entry pair
        // ([`crate::upgrade::validate_upgrade_from`] rejects through
        // `DuplicateFrom { from: "0.1.0" }` but the accessor must
        // ship the raw slot verbatim so struct-literal fixtures
        // continue to expose the duplicate at the accessor boundary).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<UpgradeFromEntry>` (which would type-check but silently
        // clone on every accessor call, breaking the zero-cost
        // projection every peer sibling slice accessor carries), a
        // `[dup, dup] → [dup]` dedup collapse (which would silently
        // absorb the `DuplicateFrom` refusal case at the accessor
        // boundary and the [`crate::StandardLayout::verify`] cross-
        // entry gate would silently accept a struct-literal `Caixa`
        // carrying the drift), a reference to an operator-resolved
        // overlay (the future per-cluster `:upgrade-overrides` slot
        // — its resolution must land at exactly this accessor body,
        // not silently divert the raw slot away from a second
        // consumer), or an axis-shuffled projection (a future detour
        // that reordered entries through the accessor would silently
        // split the paired [`crate::StandardLayout::verify`] per-
        // `:upgrade-from` shape gate's traversal input from the peer
        // [`crate::render::servico_m2_overlay`] emitter's projection
        // input, since the operator's hot-upgrade dispatch matches
        // per-`:from` and axis reordering would silently split the
        // per-entry script-path existence probe's iteration order
        // from the M2 overlay emitter's serialized-entry order).
        //
        // First outer top-level [`Caixa`] `&[Composite]`-return
        // slice accessor pin on the substrate primitive for M2 / M3
        // typed-slot vec-carry axes — opens the outer-`Caixa`
        // `&[Composite]` composite-slice projection pattern the
        // sibling `:children` [`crate::supervisor::ChildSpec`] /
        // `:membros` [`crate::aplicacao::Membro`] / `:contratos`
        // [`crate::aplicacao::WitContract`] future outer-composite-
        // slice pins fold on. Peer of the closed outer-`Caixa`
        // scalar `Option<&Composite>` composite-reference family the
        // sibling `limits` / `behavior` / `politicas` / `placement`
        // / `entrada` `..._returns_..._option_ref_verbatim_across_
        // permutations` pins closed (b2bd9d7 → e4128e4) — extends
        // the "byte-equal, borrow-shared" outer-accessor discipline
        // onto the outer-`Caixa` `&[Composite]` vec-carry altitude.
        use crate::upgrade::{UpgradeFromEntry, UpgradeInstruction};
        let fixtures: Vec<Vec<UpgradeFromEntry>> = vec![
            vec![],
            vec![UpgradeFromEntry {
                from: "0.0.1".into(),
                instructions: vec![UpgradeInstruction::Restart],
            }],
            vec![
                UpgradeFromEntry {
                    from: "0.0.1".into(),
                    instructions: vec![
                        UpgradeInstruction::LoadModule {
                            module: "demo".into(),
                        },
                        UpgradeInstruction::SoftPurge {
                            module: "demo".into(),
                        },
                    ],
                },
                UpgradeFromEntry {
                    from: "0.0.2".into(),
                    instructions: vec![
                        UpgradeInstruction::StateChange {
                            script: "servicos/upgrade.lisp".into(),
                        },
                        UpgradeInstruction::Purge {
                            module: "demo".into(),
                        },
                        UpgradeInstruction::Restart,
                    ],
                },
            ],
            vec![
                UpgradeFromEntry {
                    from: "0.1.0".into(),
                    instructions: vec![UpgradeInstruction::Restart],
                },
                UpgradeFromEntry {
                    from: "0.1.0".into(),
                    instructions: vec![UpgradeInstruction::Restart],
                },
            ],
        ];
        for upgrade_from in fixtures {
            let c = caixa_with_upgrade_from(upgrade_from.clone());
            assert_eq!(
                c.upgrade_from(),
                upgrade_from.as_slice(),
                "Caixa::upgrade_from must return :upgrade-from \
                 verbatim (got {:?}, expected {upgrade_from:?})",
                c.upgrade_from(),
            );
            assert_eq!(
                c.upgrade_from(),
                c.upgrade_from.as_slice(),
                "Caixa::upgrade_from must element-equal the raw \
                 `self.upgrade_from.as_slice()` field access across \
                 every value in the Vec<UpgradeFromEntry> accept-set",
            );
            assert_eq!(
                c.upgrade_from().is_empty(),
                c.upgrade_from.is_empty(),
                "Caixa::upgrade_from().is_empty() must byte-equal \
                 self.upgrade_from.is_empty() — a presence-bit drift \
                 would silently split the paired \
                 Caixa::declared_servico_slots M2 declared-slot \
                 enumerator's presence probe from the peer \
                 crate::render::servico_m2_overlay M2 overlay \
                 emitter's presence gate",
            );
        }
    }

    #[test]
    fn declared_servico_slots_upgrade_from_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_servico_slots`]'s
        // `:upgrade-from` presence-probe arm must key off
        // [`Caixa::upgrade_from`], not the raw
        // `self.upgrade_from.is_empty()` field-probe. Structurally: a
        // `Caixa { upgrade_from: vec![UpgradeFromEntry { from: "0.0.1",
        // instructions: vec![Restart] }], .. }` must push
        // `M2_AUTHOR_KEY_UPGRADE_FROM` onto the declared-slot list
        // (the presence bit is non-empty, so the M2 kind-coherence
        // gate must surface the slot as "declared"), and a `Caixa {
        // upgrade_from: vec![], .. }` must NOT push the label (the
        // "author omitted the slot entirely" arm — the empty-slice
        // partition the serde-default folds onto). The pair jointly
        // pins the accessor + declared-slot enumerator composition:
        // any future silent detour that had the accessor collapse
        // `[Restart]` to `[]` (a `.filter(|e| !e.instructions.
        // is_empty())` projection) would silently absorb the
        // "declared but degenerate" arm at the accessor boundary and
        // the [`crate::LayoutError::ServicoSlotsOnNonServico`] kind-
        // coherence gate would silently accept a struct-literal
        // `Caixa` carrying the drift.
        //
        // Peer of the sibling
        // `declared_servico_slots_limits_arm_routes_through_accessor`
        // (b2bd9d7) and
        // `declared_servico_slots_behavior_arm_routes_through_accessor`
        // (35d8b52) composition pins on the sibling `:limits` /
        // `:behavior` outer-`Option<&Composite>` arms — same "the
        // enumerator gate must route through the substrate-primitive
        // typed dispatch" discipline extended onto the third M2
        // Servico-runtime slot axis, closing the enumerator's routing
        // invariant on every M2 arm.
        use crate::upgrade::{UpgradeFromEntry, UpgradeInstruction};
        let c = caixa_with_upgrade_from(vec![UpgradeFromEntry {
            from: "0.0.1".into(),
            instructions: vec![UpgradeInstruction::Restart],
        }]);
        let slots = c.declared_servico_slots();
        assert!(
            slots.contains(&crate::render::M2_AUTHOR_KEY_UPGRADE_FROM),
            "declared_servico_slots must push \
             M2_AUTHOR_KEY_UPGRADE_FROM when `:upgrade-from` is \
             non-empty — the accessor and the enumerator gate must \
             route through the same substrate-primitive typed \
             dispatch on the outer :upgrade-from presence bit (got \
             slots={slots:?})",
        );
        let c = caixa_with_upgrade_from(vec![]);
        let slots = c.declared_servico_slots();
        assert!(
            !slots.contains(&crate::render::M2_AUTHOR_KEY_UPGRADE_FROM),
            "declared_servico_slots must NOT push \
             M2_AUTHOR_KEY_UPGRADE_FROM when `:upgrade-from` is \
             empty — the author-omitted arm must route through the \
             accessor's empty-slice return unchanged (got \
             slots={slots:?})",
        );
    }

    #[test]
    fn servico_m2_overlay_upgrade_from_arm_routes_through_accessor() {
        // Composition pin: [`crate::render::servico_m2_overlay`]'s
        // per-`:upgrade-from` M2 overlay emit arm must key off
        // [`Caixa::upgrade_from`], not the raw
        // `!caixa.upgrade_from.is_empty()` presence gate + the
        // `serde_yaml::to_value(&caixa.upgrade_from)` projection.
        // Structurally: a `Caixa { upgrade_from: vec![UpgradeFromEntry
        // { from: "0.0.1", instructions: vec![Restart] }], .. }` must
        // surface the `M2_KEY_UPGRADE_FROM` key with a per-entry
        // sequence in the overlay (the emitter fans onto the serde
        // slice-serialization), and a `Caixa { upgrade_from: vec![],
        // .. }` must omit the key entirely (the empty-slice
        // partition — the `!.is_empty()` outer gate elides the key
        // when the author omitted the slot). The pair jointly pins
        // the accessor + M2 overlay emitter composition: any future
        // silent detour that had the accessor return a fresh-cloned
        // `Vec<UpgradeFromEntry>` copy would silently break the
        // reference-identity pin the peer per-entry
        // `serde_yaml::to_value(caixa.upgrade_from())` projection
        // reads from — the projection would clone once per accessor
        // call instead of borrowing the storage buffer verbatim.
        //
        // Peer of the sibling
        // `servico_m2_overlay_limits_arm_routes_through_accessor`
        // (b2bd9d7) and
        // `servico_m2_overlay_behavior_arm_routes_through_accessor`
        // (35d8b52) composition pins on the sibling `:limits` /
        // `:behavior` outer-`Option<&Composite>` arms — same "the
        // M2 overlay emitter must route through the substrate-
        // primitive typed dispatch" discipline extended onto the
        // third M2 Servico-runtime slot axis, closing the overlay
        // emitter's routing invariant on every M2 arm.
        use crate::render::{M2_KEY_UPGRADE_FROM, servico_m2_overlay};
        use crate::upgrade::{UpgradeFromEntry, UpgradeInstruction};
        let c = caixa_with_upgrade_from(vec![UpgradeFromEntry {
            from: "0.0.1".into(),
            instructions: vec![UpgradeInstruction::Restart],
        }]);
        let overlay = servico_m2_overlay(&c).unwrap();
        assert!(
            overlay.contains_key(M2_KEY_UPGRADE_FROM),
            "servico_m2_overlay must surface M2_KEY_UPGRADE_FROM when \
             `:upgrade-from` is non-empty — the accessor and the M2 \
             overlay emitter must route through the same substrate- \
             primitive typed dispatch on the outer :upgrade-from \
             slice (got overlay={overlay:?})",
        );
        let c = caixa_with_upgrade_from(vec![]);
        let overlay = servico_m2_overlay(&c).unwrap();
        assert!(
            !overlay.contains_key(M2_KEY_UPGRADE_FROM),
            "servico_m2_overlay must omit M2_KEY_UPGRADE_FROM when \
             `:upgrade-from` is empty — the empty-slice partition \
             must route through the accessor's empty-slice return \
             unchanged (got overlay={overlay:?})",
        );
    }

    #[test]
    fn upgrade_from_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::upgrade_from`] returns
        // `&[UpgradeFromEntry]` by borrow — the returned slice
        // borrows the underlying `Vec<UpgradeFromEntry>` storage of
        // the `:upgrade-from` slot and the accessor must not clone
        // the backing `Vec` on every call. Peer of the sibling
        // outer top-level [`Caixa`] `&[T]`-return by-borrow pins
        // (`autores_projects_slice_by_borrow` b5d813f,
        // `etiquetas_projects_slice_by_borrow` 78c7d3c,
        // `bibliotecas_projects_slice_by_borrow` 8a36c23,
        // `exe_projects_slice_by_borrow` 65d9527,
        // `servicos_projects_slice_by_borrow` 611f78b,
        // `deps_projects_slice_by_borrow` ad34b4e,
        // `deps_dev_projects_slice_by_borrow` f7fd81e) on the
        // sibling outer top-level [`Caixa`] scalar-element `&[T]`
        // axes — extended here to the first outer-`Caixa`
        // composite-element `&[Composite]` axis: the accessor's
        // returned slice must borrow from `&self` (the returned
        // reference's lifetime is tied to `&self`), and calling the
        // accessor twice on the same [`Caixa`] must yield slices
        // that are pointer-equal (the underlying byte-buffer is the
        // storage `Vec`'s allocation, not a fresh copy) as well as
        // value-equal (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<UpgradeFromEntry>` (which would type-check but
        // silently clone on every call), a `&Vec<UpgradeFromEntry>`
        // return (which would leak the backing `Vec`'s
        // grow/push/reserve surface no downstream consumer reaches
        // for), or a one-arm-only accessor that returned a
        // saturating value on some sentinel input.
        use crate::upgrade::{UpgradeFromEntry, UpgradeInstruction};
        for upgrade_from in [
            vec![],
            vec![UpgradeFromEntry {
                from: "0.0.1".into(),
                instructions: vec![UpgradeInstruction::Restart],
            }],
            vec![
                UpgradeFromEntry {
                    from: "0.0.1".into(),
                    instructions: vec![UpgradeInstruction::Restart],
                },
                UpgradeFromEntry {
                    from: "0.0.2".into(),
                    instructions: vec![UpgradeInstruction::SoftPurge {
                        module: "demo".into(),
                    }],
                },
            ],
        ] {
            let c = caixa_with_upgrade_from(upgrade_from.clone());
            let first = c.upgrade_from();
            let second = c.upgrade_from();
            assert_eq!(
                first, second,
                "Caixa::upgrade_from must be idempotent — two \
                 successive calls on the same &self must return the \
                 same &[UpgradeFromEntry]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::upgrade_from must borrow the underlying \
                 Vec<UpgradeFromEntry> storage — two successive calls \
                 must return slices with the same backing pointer (a \
                 fresh Vec<UpgradeFromEntry> clone would change the \
                 pointer on every call)",
            );
            assert_eq!(
                first,
                upgrade_from.as_slice(),
                "Caixa::upgrade_from must return :upgrade-from \
                 verbatim by borrow — got {first:?}, expected \
                 {upgrade_from:?}",
            );
        }
    }

    // ── Caixa::children — outer top-level &[ChildSpec] composite-slice accessor ──

    fn caixa_with_children(children: Vec<crate::supervisor::ChildSpec>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.children = children;
        c
    }

    #[test]
    fn children_returns_children_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:children` M2 supervisor-tree-slot
        // outer-composite `&[ChildSpec]`-return slice-shape pin:
        // [`Caixa::children`] must return the `:children` typed
        // `Vec<ChildSpec>` verbatim as a `&[ChildSpec]` slice-view over
        // the same backing buffer the raw `self.children.as_slice()`
        // field access borrows from, element-equal across every
        // representative fixture in the accept-set — `[]` (the "no
        // static children declared" arm every non-`Supervisor`-kind
        // `defcaixa` carries by `#[serde(default)]` and every
        // `SimpleOneForOne` supervisor carries by cross-slot refusal),
        // a canonical single-child `Permanent` fixture (the shape
        // most `OneForOne` supervisors carry — a single long-running
        // worker child), a canonical multi-child list carrying every
        // typed restart-policy variant (`Permanent` / `Transient` /
        // `Temporary`), and a past-the-guard sentinel — a duplicate
        // `:caixa` `[("w", ...), ("w", ...)]` entry pair
        // ([`crate::SupervisorSpec::validate`] rejects through
        // `DuplicateChildNome { nome: "w" }` but the accessor must
        // ship the raw slot verbatim so struct-literal fixtures
        // continue to expose the duplicate at the accessor boundary).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<ChildSpec>` (which would type-check but silently clone
        // on every accessor call, breaking the zero-cost projection
        // every peer sibling slice accessor carries), a `[dup, dup] →
        // [dup]` dedup collapse (which would silently absorb the
        // `DuplicateChildNome` refusal case at the accessor boundary
        // and the [`crate::StandardLayout::verify`] cross-child gate
        // would silently accept a struct-literal `Caixa` carrying the
        // drift), a reference to an operator-resolved overlay (the
        // future per-cluster `:children-overrides` slot — its
        // resolution must land at exactly this accessor body, not
        // silently divert the raw slot away from a second consumer),
        // or an axis-shuffled projection (a future detour that
        // reordered children through the accessor would silently
        // split the paired [`crate::StandardLayout::verify`] per-
        // supervisor gate's traversal input from the peer
        // [`Self::supervisor_view`] fold-in path's clone-order input,
        // since the OTP `RestForOne` restart strategy dispatches on
        // declared child order and axis reordering would silently
        // split the operator's per-cluster restart-fan-out order
        // from the caixa.lisp source-order).
        //
        // Second outer top-level [`Caixa`] `&[Composite]`-return slice
        // accessor pin on the substrate primitive for M2 / M3 typed-
        // slot vec-carry axes — folds on the outer-`Caixa`
        // `&[Composite]` composite-slice sub-family the sibling
        // `upgrade_from_returns_upgrade_from_slice_verbatim_across_permutations`
        // (2a1f907) pin opened, peer at the outer altitude of the
        // closed inner-`SupervisorSpec` `SupervisorSpec::children`
        // (bc92bce) accessor on the same OTP-supervisor static-child-
        // list axis.
        use crate::supervisor::{ChildSpec, RestartPolicy};
        let fixtures: Vec<Vec<ChildSpec>> = vec![
            vec![],
            vec![ChildSpec {
                caixa: "worker".into(),
                versao: "^0.1".into(),
                restart: RestartPolicy::Permanent,
            }],
            vec![
                ChildSpec {
                    caixa: "worker-a".into(),
                    versao: "^0.1".into(),
                    restart: RestartPolicy::Permanent,
                },
                ChildSpec {
                    caixa: "worker-b".into(),
                    versao: "^0.1".into(),
                    restart: RestartPolicy::Transient,
                },
                ChildSpec {
                    caixa: "worker-c".into(),
                    versao: "^0.1".into(),
                    restart: RestartPolicy::Temporary,
                },
            ],
            vec![
                ChildSpec {
                    caixa: "w".into(),
                    versao: "^0.1".into(),
                    restart: RestartPolicy::Permanent,
                },
                ChildSpec {
                    caixa: "w".into(),
                    versao: "^0.1".into(),
                    restart: RestartPolicy::Permanent,
                },
            ],
        ];
        for children in fixtures {
            let c = caixa_with_children(children.clone());
            assert_eq!(
                c.children(),
                children.as_slice(),
                "Caixa::children must return :children verbatim \
                 (got {:?}, expected {children:?})",
                c.children(),
            );
            assert_eq!(
                c.children(),
                c.children.as_slice(),
                "Caixa::children must element-equal the raw \
                 `self.children.as_slice()` field access across \
                 every value in the Vec<ChildSpec> accept-set",
            );
            assert_eq!(
                c.children().is_empty(),
                c.children.is_empty(),
                "Caixa::children().is_empty() must byte-equal \
                 self.children.is_empty() — a presence-bit drift \
                 would silently split the paired \
                 Caixa::declared_supervisor_slots supervisor-tree \
                 declared-slot enumerator's presence probe from the \
                 peer Caixa::supervisor_view typed-view composer's \
                 fold-in path",
            );
        }
    }

    #[test]
    fn declared_supervisor_slots_children_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_supervisor_slots`]'s
        // `:children` presence-probe arm must key off
        // [`Caixa::children`], not the raw
        // `!self.children.is_empty()` field-probe. Structurally: a
        // `Caixa { children: vec![ChildSpec { caixa: "w", versao:
        // "^0.1", restart: Permanent }], .. }` must push
        // `SUPERVISOR_AUTHOR_KEY_CHILDREN` onto the declared-slot list
        // (the presence bit is non-empty, so the supervisor-tree
        // kind-coherence gate must surface the slot as "declared"),
        // and a `Caixa { children: vec![], .. }` must NOT push the
        // label (the "author omitted the slot entirely" arm — the
        // empty-slice partition the serde-default folds onto). The
        // pair jointly pins the accessor + declared-slot enumerator
        // composition: any future silent detour that had the accessor
        // collapse `[Permanent]` to `[]` (a `.filter(|c| c.nome() !=
        // "__reserved__")` projection) would silently absorb the
        // "declared but degenerate" arm at the accessor boundary and
        // the [`crate::LayoutError::SupervisorSlotsOnNonSupervisor`]
        // kind-coherence gate would silently accept a struct-literal
        // `Caixa` carrying the drift.
        //
        // Peer of the sibling
        // `declared_servico_slots_upgrade_from_arm_routes_through_accessor`
        // (2a1f907) on the M2 `:upgrade-from` composite-slice arm —
        // same "the enumerator gate must route through the substrate-
        // primitive typed dispatch" discipline extended onto the
        // supervisor-tree `:children` composite-slice arm.
        use crate::supervisor::{ChildSpec, RestartPolicy};
        let c = caixa_with_children(vec![ChildSpec {
            caixa: "w".into(),
            versao: "^0.1".into(),
            restart: RestartPolicy::Permanent,
        }]);
        let slots = c.declared_supervisor_slots();
        assert!(
            slots.contains(&crate::render::SUPERVISOR_AUTHOR_KEY_CHILDREN),
            "declared_supervisor_slots must push \
             SUPERVISOR_AUTHOR_KEY_CHILDREN when `:children` is \
             non-empty — the accessor and the enumerator gate must \
             route through the same substrate-primitive typed \
             dispatch on the outer :children presence bit (got \
             slots={slots:?})",
        );
        let c = caixa_with_children(vec![]);
        let slots = c.declared_supervisor_slots();
        assert!(
            !slots.contains(&crate::render::SUPERVISOR_AUTHOR_KEY_CHILDREN),
            "declared_supervisor_slots must NOT push \
             SUPERVISOR_AUTHOR_KEY_CHILDREN when `:children` is \
             empty — the author-omitted arm must route through the \
             accessor's empty-slice return unchanged (got \
             slots={slots:?})",
        );
    }

    #[test]
    fn supervisor_view_children_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::supervisor_view`]'s per-`:children`
        // fold-in arm must key off [`Caixa::children`], not the raw
        // `self.children.clone()` field-clone. Structurally: a `Caixa {
        // kind: Supervisor, estrategia: Some(OneForOne), children:
        // vec![ChildSpec { caixa: "w", .. }], .. }` must fold the
        // per-child list through the accessor into the typed
        // [`SupervisorSpec`] view's `children` field verbatim — every
        // entry the accessor surfaces must land in the view's
        // `children` slot in the same order. The pair jointly pins the
        // accessor + view-composer composition: any future silent
        // detour that had the accessor return a fresh-cloned
        // `Vec<ChildSpec>` copy would silently break the reference-
        // identity pin the peer `supervisor_view` fold-in path reads
        // from — the fold would clone once more per accessor call
        // instead of borrowing the storage buffer verbatim once.
        //
        // Peer of the sibling
        // `supervisor_view_kind_gate_routes_through_accessor` (35d8b52-
        // family) composition pin on the peer kind-gate arm — same
        // "the view composer must route through the substrate-
        // primitive typed dispatch" discipline extended onto the
        // per-`:children` fold-in arm, closing the supervisor-view
        // composer's routing invariant on the composite-slice input.
        use crate::supervisor::{ChildSpec, RestartPolicy, RestartStrategy};
        let mut c = caixa_with_children(vec![
            ChildSpec {
                caixa: "worker-a".into(),
                versao: "^0.1".into(),
                restart: RestartPolicy::Permanent,
            },
            ChildSpec {
                caixa: "worker-b".into(),
                versao: "^0.1".into(),
                restart: RestartPolicy::Transient,
            },
        ]);
        c.kind = crate::CaixaKind::Supervisor;
        c.estrategia = Some(RestartStrategy::OneForOne);
        let view = c
            .supervisor_view()
            .expect("Supervisor kind must produce a supervisor_view");
        assert_eq!(
            view.children(),
            c.children(),
            "supervisor_view must fold Caixa::children verbatim into \
             SupervisorSpec::children — the accessor and the view \
             composer must route through the same substrate-primitive \
             typed dispatch on the outer :children slice (got view \
             children={:?}, expected {:?})",
            view.children(),
            c.children(),
        );
    }

    #[test]
    fn children_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::children`] returns
        // `&[ChildSpec]` by borrow — the returned slice borrows the
        // underlying `Vec<ChildSpec>` storage of the `:children` slot
        // and the accessor must not clone the backing `Vec` on every
        // call. Peer of the sibling outer top-level [`Caixa`]
        // `&[T]`-return by-borrow pins (`autores_projects_slice_by_borrow`
        // b5d813f, `etiquetas_projects_slice_by_borrow` 78c7d3c,
        // `bibliotecas_projects_slice_by_borrow` 8a36c23,
        // `exe_projects_slice_by_borrow` 65d9527,
        // `servicos_projects_slice_by_borrow` 611f78b,
        // `deps_projects_slice_by_borrow` ad34b4e,
        // `deps_dev_projects_slice_by_borrow` f7fd81e,
        // `upgrade_from_projects_slice_by_borrow` 2a1f907) on the
        // sibling outer top-level [`Caixa`] scalar-element and
        // composite-element `&[T]` axes — folds on the outer-`Caixa`
        // composite-element `&[Composite]` axis: the accessor's
        // returned slice must borrow from `&self` (the returned
        // reference's lifetime is tied to `&self`), and calling the
        // accessor twice on the same [`Caixa`] must yield slices
        // that are pointer-equal (the underlying byte-buffer is the
        // storage `Vec`'s allocation, not a fresh copy) as well as
        // value-equal (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<ChildSpec>` (which would type-check but silently clone
        // on every call), a `&Vec<ChildSpec>` return (which would leak
        // the backing `Vec`'s grow/push/reserve surface no downstream
        // consumer reaches for), or a one-arm-only accessor that
        // returned a saturating value on some sentinel input.
        use crate::supervisor::{ChildSpec, RestartPolicy};
        for children in [
            vec![],
            vec![ChildSpec {
                caixa: "w".into(),
                versao: "^0.1".into(),
                restart: RestartPolicy::Permanent,
            }],
            vec![
                ChildSpec {
                    caixa: "worker-a".into(),
                    versao: "^0.1".into(),
                    restart: RestartPolicy::Permanent,
                },
                ChildSpec {
                    caixa: "worker-b".into(),
                    versao: "^0.1".into(),
                    restart: RestartPolicy::Transient,
                },
            ],
        ] {
            let c = caixa_with_children(children.clone());
            let first = c.children();
            let second = c.children();
            assert_eq!(
                first, second,
                "Caixa::children must be idempotent — two successive \
                 calls on the same &self must return the same \
                 &[ChildSpec]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::children must borrow the underlying \
                 Vec<ChildSpec> storage — two successive calls must \
                 return slices with the same backing pointer (a fresh \
                 Vec<ChildSpec> clone would change the pointer on \
                 every call)",
            );
            assert_eq!(
                first,
                children.as_slice(),
                "Caixa::children must return :children verbatim by \
                 borrow — got {first:?}, expected {children:?}",
            );
        }
    }

    // ── Caixa::membros — outer top-level &[Membro] composite-slice accessor ──

    fn caixa_aplicacao_with_membros(membros: Vec<crate::aplicacao::Membro>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.kind = CaixaKind::Aplicacao;
        c.membros = membros;
        c
    }

    #[test]
    fn membros_returns_membros_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:membros` M3 mesh-slot outer-
        // composite `&[Membro]`-return slice-shape pin:
        // [`Caixa::membros`] must return the `:membros` typed
        // `Vec<Membro>` verbatim as a `&[Membro]` slice-view over the
        // same backing buffer the raw `self.membros.as_slice()` field
        // access borrows from, element-equal across every
        // representative fixture in the accept-set — `[]` (the "no
        // members declared" arm every non-`Aplicacao`-kind `defcaixa`
        // carries by `#[serde(default)]` and every partially-authored
        // Aplicacao carries before the
        // [`crate::AplicacaoError::MembrosEmpty`] gate fires), a
        // canonical single-member fixture (the shape a minimal
        // Aplicacao carries — one Servico wrapping one contained
        // computation), a canonical multi-member list carrying three
        // distinct entries (the canonical checkout-shape Aplicacao —
        // cart / pricing / auth — every canonical example carries), and
        // a past-the-guard sentinel — a duplicate `:caixa`
        // `[("cart", ...), ("cart", ...)]` entry pair
        // ([`crate::AplicacaoSpec::validate`] rejects through
        // `DuplicateMembro { nome: "cart" }` but the accessor must ship
        // the raw slot verbatim so struct-literal fixtures continue to
        // expose the duplicate at the accessor boundary).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<Membro>` (which would type-check but silently clone on
        // every accessor call, breaking the zero-cost projection every
        // peer sibling slice accessor carries), a `[dup, dup] → [dup]`
        // dedup collapse (which would silently absorb the
        // `DuplicateMembro` refusal case at the accessor boundary and
        // the [`crate::StandardLayout::verify`] cross-member gate would
        // silently accept a struct-literal `Caixa` carrying the drift),
        // a reference to an operator-resolved overlay (the future per-
        // cluster `:membros-overrides` slot — its resolution must land
        // at exactly this accessor body, not silently divert the raw
        // slot away from a second consumer), or an axis-shuffled
        // projection (a future detour that reordered members through
        // the accessor would silently split the paired
        // [`crate::StandardLayout::verify`] per-Aplicacao gate's
        // traversal input from the peer [`Self::aplicacao_view`] fold-
        // in path's clone-order input, since the canonical `:contratos`
        // `:de`/`:para` and `:entrada :para` cross-slot refusal probes
        // read the member set through the same slice).
        //
        // Third outer top-level [`Caixa`] `&[Composite]`-return slice
        // accessor pin on the substrate primitive for M2 / M3 typed-
        // slot vec-carry axes — opens the outer-`Caixa` M3 mesh-slot
        // arm of the `&[Composite]` composite-slice sub-family the
        // sibling M2 `upgrade_from_returns_upgrade_from_slice_verbatim_across_permutations`
        // (2a1f907) and
        // `children_returns_children_slice_verbatim_across_permutations`
        // (c17b51e) pins opened, peer at the outer altitude of the
        // closed inner-[`crate::AplicacaoSpec::membros`] (6c77e36)
        // accessor on the same MESH-COMPOSITION per-Aplicacao member-
        // list axis.
        use crate::aplicacao::Membro;
        let fixtures: Vec<Vec<Membro>> = vec![
            vec![],
            vec![Membro {
                caixa: "cart".into(),
                versao: "^0.1".into(),
            }],
            vec![
                Membro {
                    caixa: "cart".into(),
                    versao: "^0.1".into(),
                },
                Membro {
                    caixa: "pricing".into(),
                    versao: "^0.2".into(),
                },
                Membro {
                    caixa: "auth".into(),
                    versao: "^1.0".into(),
                },
            ],
            vec![
                Membro {
                    caixa: "cart".into(),
                    versao: "^0.1".into(),
                },
                Membro {
                    caixa: "cart".into(),
                    versao: "^0.1".into(),
                },
            ],
        ];
        for membros in fixtures {
            let c = caixa_aplicacao_with_membros(membros.clone());
            assert_eq!(
                c.membros(),
                membros.as_slice(),
                "Caixa::membros must return :membros verbatim \
                 (got {:?}, expected {membros:?})",
                c.membros(),
            );
            assert_eq!(
                c.membros(),
                c.membros.as_slice(),
                "Caixa::membros must element-equal the raw \
                 `self.membros.as_slice()` field access across every \
                 value in the Vec<Membro> accept-set",
            );
            assert_eq!(
                c.membros().is_empty(),
                c.membros.is_empty(),
                "Caixa::membros().is_empty() must byte-equal \
                 self.membros.is_empty() — a presence-bit drift would \
                 silently split the paired Caixa::declared_mesh_slots \
                 mesh declared-slot enumerator's presence probe from \
                 the peer Caixa::aplicacao_view typed-view composer's \
                 fold-in path",
            );
        }
    }

    #[test]
    fn declared_mesh_slots_membros_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_mesh_slots`]'s `:membros`
        // presence-probe arm must key off [`Caixa::membros`], not the
        // raw `!self.membros.is_empty()` field-probe. Structurally: a
        // `Caixa { membros: vec![Membro { caixa: "cart", versao:
        // "^0.1" }], .. }` must push `M3_AUTHOR_KEY_MEMBROS` onto the
        // declared-slot list (the presence bit is non-empty, so the
        // mesh kind-coherence gate must surface the slot as
        // "declared"), and a `Caixa { membros: vec![], .. }` must NOT
        // push the label (the "author omitted the slot entirely" arm
        // — the empty-slice partition the serde-default folds onto).
        // The pair jointly pins the accessor + declared-slot
        // enumerator composition: any future silent detour that had
        // the accessor collapse `[Membro { .. }]` to `[]` (a
        // `.filter(|m| m.nome() != "__reserved__")` projection) would
        // silently absorb the "declared but degenerate" arm at the
        // accessor boundary and the
        // [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-
        // coherence gate would silently accept a struct-literal
        // `Caixa` carrying the drift.
        //
        // Peer of the sibling
        // `declared_servico_slots_upgrade_from_arm_routes_through_accessor`
        // (2a1f907) and
        // `declared_supervisor_slots_children_arm_routes_through_accessor`
        // (c17b51e) composition pins on the M2 `:upgrade-from` /
        // `:children` composite-slice arms — same "the enumerator gate
        // must route through the substrate-primitive typed dispatch"
        // discipline extended onto the M3 `:membros` composite-slice
        // arm, opening the M3 arm of the declared-slot enumerator's
        // routing invariant.
        use crate::aplicacao::Membro;
        let c = caixa_aplicacao_with_membros(vec![Membro {
            caixa: "cart".into(),
            versao: "^0.1".into(),
        }]);
        let slots = c.declared_mesh_slots();
        assert!(
            slots.contains(&crate::render::M3_AUTHOR_KEY_MEMBROS),
            "declared_mesh_slots must push M3_AUTHOR_KEY_MEMBROS when \
             `:membros` is non-empty — the accessor and the enumerator \
             gate must route through the same substrate-primitive \
             typed dispatch on the outer :membros presence bit (got \
             slots={slots:?})",
        );
        let c = caixa_aplicacao_with_membros(vec![]);
        let slots = c.declared_mesh_slots();
        assert!(
            !slots.contains(&crate::render::M3_AUTHOR_KEY_MEMBROS),
            "declared_mesh_slots must NOT push M3_AUTHOR_KEY_MEMBROS \
             when `:membros` is empty — the author-omitted arm must \
             route through the accessor's empty-slice return unchanged \
             (got slots={slots:?})",
        );
    }

    #[test]
    fn aplicacao_view_membros_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::aplicacao_view`]'s per-`:membros`
        // fold-in arm must key off [`Caixa::membros`], not the raw
        // `self.membros.clone()` field-clone. Structurally: a `Caixa {
        // kind: Aplicacao, membros: vec![Membro { caixa: "cart", .. },
        // Membro { caixa: "pricing", .. }], .. }` must fold the per-
        // member list through the accessor into the typed
        // [`crate::AplicacaoSpec`] view's `membros` slot verbatim —
        // every entry the accessor surfaces must land in the view's
        // `membros` slot in the same order. The pair jointly pins the
        // accessor + view-composer composition: any future silent
        // detour that had the accessor return a fresh-cloned
        // `Vec<Membro>` copy would silently break the reference-
        // identity pin the peer `aplicacao_view` fold-in path reads
        // from — the fold would clone once more per accessor call
        // instead of borrowing the storage buffer verbatim once.
        //
        // Peer of the sibling
        // `aplicacao_view_politicas_arm_folds_through_accessor`
        // (5d23d29) /
        // `aplicacao_view_placement_arm_folds_through_accessor`
        // (4fb8074) /
        // `aplicacao_view_entrada_arm_folds_through_accessor` (e4128e4)
        // composition pins on the M3 `:politicas` / `:placement` /
        // `:entrada` outer-`Option<&Composite>` arms — extended here to
        // the M3 `:membros` outer-`&[Composite]` composite-slice arm,
        // closing the aplicacao-view composer's routing invariant on
        // the composite-slice input.
        use crate::aplicacao::Membro;
        let c = caixa_aplicacao_with_membros(vec![
            Membro {
                caixa: "cart".into(),
                versao: "^0.1".into(),
            },
            Membro {
                caixa: "pricing".into(),
                versao: "^0.2".into(),
            },
        ]);
        let view = c
            .aplicacao_view()
            .expect("Aplicacao kind must produce an aplicacao_view");
        assert_eq!(
            view.membros(),
            c.membros(),
            "aplicacao_view must fold Caixa::membros verbatim into \
             AplicacaoSpec::membros — the accessor and the view \
             composer must route through the same substrate-primitive \
             typed dispatch on the outer :membros slice (got view \
             membros={:?}, expected {:?})",
            view.membros(),
            c.membros(),
        );
    }

    #[test]
    fn membros_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::membros`] returns `&[Membro]` by
        // borrow — the returned slice borrows the underlying
        // `Vec<Membro>` storage of the `:membros` slot and the
        // accessor must not clone the backing `Vec` on every call.
        // Peer of the sibling outer top-level [`Caixa`] `&[T]`-return
        // by-borrow pins (`autores_projects_slice_by_borrow` b5d813f,
        // `etiquetas_projects_slice_by_borrow` 78c7d3c,
        // `bibliotecas_projects_slice_by_borrow` 8a36c23,
        // `exe_projects_slice_by_borrow` 65d9527,
        // `servicos_projects_slice_by_borrow` 611f78b,
        // `deps_projects_slice_by_borrow` ad34b4e,
        // `deps_dev_projects_slice_by_borrow` f7fd81e,
        // `upgrade_from_projects_slice_by_borrow` 2a1f907,
        // `children_projects_slice_by_borrow` c17b51e) on the sibling
        // outer top-level [`Caixa`] scalar-element and composite-
        // element `&[T]` axes — folds on the outer-`Caixa` M3 mesh-
        // slot composite-element `&[Composite]` axis: the accessor's
        // returned slice must borrow from `&self` (the returned
        // reference's lifetime is tied to `&self`), and calling the
        // accessor twice on the same [`Caixa`] must yield slices that
        // are pointer-equal (the underlying byte-buffer is the storage
        // `Vec`'s allocation, not a fresh copy) as well as value-equal
        // (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<Membro>` (which would type-check but silently clone on
        // every call), a `&Vec<Membro>` return (which would leak the
        // backing `Vec`'s grow/push/reserve surface no downstream
        // consumer reaches for), or a one-arm-only accessor that
        // returned a saturating value on some sentinel input.
        use crate::aplicacao::Membro;
        for membros in [
            vec![],
            vec![Membro {
                caixa: "cart".into(),
                versao: "^0.1".into(),
            }],
            vec![
                Membro {
                    caixa: "cart".into(),
                    versao: "^0.1".into(),
                },
                Membro {
                    caixa: "pricing".into(),
                    versao: "^0.2".into(),
                },
            ],
        ] {
            let c = caixa_aplicacao_with_membros(membros.clone());
            let first = c.membros();
            let second = c.membros();
            assert_eq!(
                first, second,
                "Caixa::membros must be idempotent — two successive \
                 calls on the same &self must return the same &[Membro]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::membros must borrow the underlying Vec<Membro> \
                 storage — two successive calls must return slices with \
                 the same backing pointer (a fresh Vec<Membro> clone \
                 would change the pointer on every call)",
            );
            assert_eq!(
                first,
                membros.as_slice(),
                "Caixa::membros must return :membros verbatim by borrow \
                 — got {first:?}, expected {membros:?}",
            );
        }
    }

    // ── Caixa::contratos — outer top-level &[WitContract] composite-slice accessor ──

    fn caixa_aplicacao_with_contratos(contratos: Vec<crate::aplicacao::WitContract>) -> Caixa {
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.kind = CaixaKind::Aplicacao;
        c.contratos = contratos;
        c
    }

    fn contrato_http_for_test(
        de: &str,
        para: &str,
        endpoint: &str,
    ) -> crate::aplicacao::WitContract {
        crate::aplicacao::WitContract {
            de: de.into(),
            para: para.into(),
            wit: "wasi:http/proxy".into(),
            endpoint: Some(endpoint.into()),
            subject: None,
            slot: None,
        }
    }

    #[test]
    fn contratos_returns_contratos_slice_verbatim_across_permutations() {
        // The canonical per-`Caixa` `:contratos` M3 mesh-slot outer-
        // composite `&[WitContract]`-return slice-shape pin:
        // [`Caixa::contratos`] must return the `:contratos` typed
        // `Vec<WitContract>` verbatim as a `&[WitContract]` slice-view
        // over the same backing buffer the raw
        // `self.contratos.as_slice()` field access borrows from,
        // element-equal across every representative fixture in the
        // accept-set — `[]` (the "no contracts declared" arm every
        // non-`Aplicacao`-kind `defcaixa` carries by
        // `#[serde(default)]` and every leaf-Aplicacao with a single
        // member carries), a canonical single-edge fixture (the
        // minimal directed-graph shape: one HTTP-shape `(cart → catalog)`
        // edge), and a canonical multi-edge fixture with three distinct
        // edges (the checkout-shape Aplicacao's HTTP-fan pattern:
        // `(cart → catalog)`, `(cart → pricing)`, `(cart → auth)`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<WitContract>` (which would type-check but silently clone
        // on every accessor call, breaking the zero-cost projection
        // every peer sibling slice accessor carries), an axis-shuffled
        // projection (a future detour that reordered edges through the
        // accessor would silently split the paired
        // [`crate::StandardLayout::verify`] per-Aplicacao gate's
        // traversal input from the peer [`Self::aplicacao_view`] fold-
        // in path's clone-order input, since every canonical
        // `caixa-mesh` renderer's per-`(:de, :para)` adjacency-list
        // seed dispatch reads the edge set through the same slice),
        // or a reference to an operator-resolved overlay (the future
        // per-cluster `:contratos-overrides` slot — its resolution
        // must land at exactly this accessor body, not silently divert
        // the raw slot away from a second consumer).
        //
        // Fourth outer top-level [`Caixa`] `&[Composite]`-return slice
        // accessor pin on the substrate primitive for M2 / M3 typed-
        // slot vec-carry axes — closes the outer-`Caixa`
        // `&[Composite]` composite-slice sub-family the sibling M2
        // `upgrade_from_returns_upgrade_from_slice_verbatim_across_permutations`
        // (2a1f907) and
        // `children_returns_children_slice_verbatim_across_permutations`
        // (c17b51e) pins opened and the M3
        // `membros_returns_membros_slice_verbatim_across_permutations`
        // (0f26987) pin folded on, closing the outer-`Caixa` M3 mesh-
        // slot arm of the composite-slice sub-family. Peer at the outer
        // altitude of the closed inner-
        // [`crate::AplicacaoSpec::contratos`] (0dcc926) accessor on the
        // same MESH-COMPOSITION per-Aplicacao contract-list axis.
        let fixtures: Vec<Vec<crate::aplicacao::WitContract>> = vec![
            vec![],
            vec![contrato_http_for_test("cart", "catalog", "/items")],
            vec![
                contrato_http_for_test("cart", "catalog", "/items"),
                contrato_http_for_test("cart", "pricing", "/price"),
                contrato_http_for_test("cart", "auth", "/whoami"),
            ],
        ];
        for contratos in fixtures {
            let c = caixa_aplicacao_with_contratos(contratos.clone());
            assert_eq!(
                c.contratos(),
                contratos.as_slice(),
                "Caixa::contratos must return :contratos verbatim \
                 (got {:?}, expected {contratos:?})",
                c.contratos(),
            );
            assert_eq!(
                c.contratos(),
                c.contratos.as_slice(),
                "Caixa::contratos must element-equal the raw \
                 `self.contratos.as_slice()` field access across every \
                 value in the Vec<WitContract> accept-set",
            );
            assert_eq!(
                c.contratos().is_empty(),
                c.contratos.is_empty(),
                "Caixa::contratos().is_empty() must byte-equal \
                 self.contratos.is_empty() — a presence-bit drift would \
                 silently split the paired Caixa::declared_mesh_slots \
                 mesh declared-slot enumerator's presence probe from \
                 the peer Caixa::aplicacao_view typed-view composer's \
                 fold-in path",
            );
        }
    }

    #[test]
    fn declared_mesh_slots_contratos_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::declared_mesh_slots`]'s `:contratos`
        // presence-probe arm must key off [`Caixa::contratos`], not the
        // raw `!self.contratos.is_empty()` field-probe. Structurally: a
        // `Caixa { contratos: vec![WitContract { .. }], .. }` must push
        // `M3_AUTHOR_KEY_CONTRATOS` onto the declared-slot list (the
        // presence bit is non-empty, so the mesh kind-coherence gate
        // must surface the slot as "declared"), and a `Caixa {
        // contratos: vec![], .. }` must NOT push the label (the "author
        // omitted the slot entirely" arm — the empty-slice partition
        // the serde-default folds onto). The pair jointly pins the
        // accessor + declared-slot enumerator composition: any future
        // silent detour that had the accessor collapse
        // `[WitContract { .. }]` to `[]` (a `.filter(|c| c.de() !=
        // "__reserved__")` projection) would silently absorb the
        // "declared but degenerate" arm at the accessor boundary and
        // the [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-
        // coherence gate would silently accept a struct-literal
        // `Caixa` carrying the drift.
        //
        // Peer of the sibling
        // `declared_servico_slots_upgrade_from_arm_routes_through_accessor`
        // (2a1f907),
        // `declared_supervisor_slots_children_arm_routes_through_accessor`
        // (c17b51e), and
        // `declared_mesh_slots_membros_arm_routes_through_accessor`
        // (0f26987) composition pins on the M2 `:upgrade-from` /
        // `:children` / M3 `:membros` composite-slice arms — same "the
        // enumerator gate must route through the substrate-primitive
        // typed dispatch" discipline extended onto the M3 `:contratos`
        // composite-slice arm, closing the M3 mesh-slot arm of the
        // declared-slot enumerator's routing invariant on the
        // composite-slice inputs.
        let c = caixa_aplicacao_with_contratos(vec![contrato_http_for_test(
            "cart", "catalog", "/items",
        )]);
        let slots = c.declared_mesh_slots();
        assert!(
            slots.contains(&crate::render::M3_AUTHOR_KEY_CONTRATOS),
            "declared_mesh_slots must push M3_AUTHOR_KEY_CONTRATOS when \
             `:contratos` is non-empty — the accessor and the enumerator \
             gate must route through the same substrate-primitive \
             typed dispatch on the outer :contratos presence bit (got \
             slots={slots:?})",
        );
        let c = caixa_aplicacao_with_contratos(vec![]);
        let slots = c.declared_mesh_slots();
        assert!(
            !slots.contains(&crate::render::M3_AUTHOR_KEY_CONTRATOS),
            "declared_mesh_slots must NOT push M3_AUTHOR_KEY_CONTRATOS \
             when `:contratos` is empty — the author-omitted arm must \
             route through the accessor's empty-slice return unchanged \
             (got slots={slots:?})",
        );
    }

    #[test]
    fn aplicacao_view_contratos_arm_routes_through_accessor() {
        // Composition pin: [`Caixa::aplicacao_view`]'s per-`:contratos`
        // fold-in arm must key off [`Caixa::contratos`], not the raw
        // `self.contratos.clone()` field-clone. Structurally: a `Caixa
        // { kind: Aplicacao, contratos: vec![WitContract { de: "cart",
        // .. }, WitContract { de: "pricing", .. }], .. }` must fold the
        // per-edge list through the accessor into the typed
        // [`crate::AplicacaoSpec`] view's `contratos` slot verbatim —
        // every entry the accessor surfaces must land in the view's
        // `contratos` slot in the same order. The pair jointly pins
        // the accessor + view-composer composition: a future silent
        // detour that had the accessor shuffle or drop an edge would
        // silently split the paired declared-slot enumerator's
        // presence bit from the typed-view composer's edge-list, a
        // two-consumer split at the enumerator and the view composer
        // far from the source `caixa.lisp`.
        //
        // Peer of the sibling
        // `aplicacao_view_membros_arm_routes_through_accessor`
        // (0f26987) composition pin on the M3 `:membros` outer-
        // `&[Composite]` composite-slice arm, closing the aplicacao-
        // view composer's routing invariant on the composite-slice
        // inputs at the outer altitude.
        let c = caixa_aplicacao_with_contratos(vec![
            contrato_http_for_test("cart", "catalog", "/items"),
            contrato_http_for_test("cart", "pricing", "/price"),
        ]);
        let view = c
            .aplicacao_view()
            .expect("Aplicacao kind must produce an aplicacao_view");
        assert_eq!(
            view.contratos(),
            c.contratos(),
            "aplicacao_view must fold Caixa::contratos verbatim into \
             AplicacaoSpec::contratos — the accessor and the view \
             composer must route through the same substrate-primitive \
             typed dispatch on the outer :contratos slice (got view \
             contratos={:?}, expected {:?})",
            view.contratos(),
            c.contratos(),
        );
    }

    #[test]
    fn contratos_projects_slice_by_borrow() {
        // The by-borrow pin: [`Caixa::contratos`] returns `&[WitContract]`
        // by borrow — the returned slice borrows the underlying
        // `Vec<WitContract>` storage of the `:contratos` slot and the
        // accessor must not clone the backing `Vec` on every call.
        // Peer of the sibling outer top-level [`Caixa`] `&[T]`-return
        // by-borrow pins (`autores_projects_slice_by_borrow` b5d813f,
        // `etiquetas_projects_slice_by_borrow` 78c7d3c,
        // `bibliotecas_projects_slice_by_borrow` 8a36c23,
        // `exe_projects_slice_by_borrow` 65d9527,
        // `servicos_projects_slice_by_borrow` 611f78b,
        // `deps_projects_slice_by_borrow` ad34b4e,
        // `deps_dev_projects_slice_by_borrow` f7fd81e,
        // `upgrade_from_projects_slice_by_borrow` 2a1f907,
        // `children_projects_slice_by_borrow` c17b51e,
        // `membros_projects_slice_by_borrow` 0f26987) on the sibling
        // outer top-level [`Caixa`] scalar-element and composite-
        // element `&[T]` axes — closes the outer-`Caixa` M3 mesh-slot
        // composite-element `&[Composite]` axis on the by-borrow pin:
        // the accessor's returned slice must borrow from `&self` (the
        // returned reference's lifetime is tied to `&self`), and
        // calling the accessor twice on the same [`Caixa`] must yield
        // slices that are pointer-equal (the underlying byte-buffer is
        // the storage `Vec`'s allocation, not a fresh copy) as well as
        // value-equal (idempotent, no side effects on `&self`).
        //
        // Pins against a future silent detour that returned an owned
        // `Vec<WitContract>` (which would type-check but silently clone
        // on every call), a `&Vec<WitContract>` return (which would
        // leak the backing `Vec`'s grow/push/reserve surface no
        // downstream consumer reaches for), or a one-arm-only accessor
        // that returned a saturating value on some sentinel input.
        for contratos in [
            vec![],
            vec![contrato_http_for_test("cart", "catalog", "/items")],
            vec![
                contrato_http_for_test("cart", "catalog", "/items"),
                contrato_http_for_test("cart", "pricing", "/price"),
            ],
        ] {
            let c = caixa_aplicacao_with_contratos(contratos.clone());
            let first = c.contratos();
            let second = c.contratos();
            assert_eq!(
                first, second,
                "Caixa::contratos must be idempotent — two successive \
                 calls on the same &self must return the same \
                 &[WitContract]",
            );
            assert_eq!(
                first.as_ptr(),
                second.as_ptr(),
                "Caixa::contratos must borrow the underlying \
                 Vec<WitContract> storage — two successive calls must \
                 return slices with the same backing pointer (a fresh \
                 Vec<WitContract> clone would change the pointer on \
                 every call)",
            );
            assert_eq!(
                first,
                contratos.as_slice(),
                "Caixa::contratos must return :contratos verbatim by \
                 borrow — got {first:?}, expected {contratos:?}",
            );
        }
    }

    // ── drift-detection: Caixa top-level multi-word serde-derive-to-const identity ──

    #[test]
    fn caixa_multi_word_serde_keys_match_lifted_top_level_key_consts() {
        // Load-bearing invariant: every multi-word top-level [`Caixa`]
        // serde-derived JSON key routes through a lifted `&'static str`
        // const. The Rust field names are `snake_case`
        // (`deps_dev` / `upgrade_from` / `max_restarts` /
        // `restart_window`); [`Caixa`]'s `#[serde(rename_all =
        // "camelCase")]` derive attribute maps each to the camelCase
        // byte-string the [`Caixa::to_lisp`] round-trip's
        // `serde_json::to_value(self)` step lands under before
        // `tatara_lisp::domain::json_to_sexp` re-projects the JSON keys
        // to the kebab-case `:deps-dev` / `:upgrade-from` /
        // `:max-restarts` / `:restart-window` author surface. Serialize
        // a fully-populated [`Caixa`] and pin that each canonical
        // byte-sequence appears verbatim in the JSON — a future
        // accidental `rename_all = "snake_case"` / `"kebab-case"` /
        // verbatim-field-name flip at the derive attribute (any of
        // which would silently break every [`Caixa::to_lisp`]
        // round-trip and the future M4 operator-side manifest ingest's
        // `Value::get(<key>)` navigation) surfaces here as a build-time
        // test failure at `manifest.rs`, not as an apply-time
        // `.get(<stale-canonical-const>)` returning `None` far from the
        // derive-attr drift's commit. Same discipline the sibling
        // `supervisor_spec_serde_keys_match_lifted_supervisor_key_consts`
        // (40cc4e5), `membro_serde_keys_match_lifted_membro_key_consts`
        // (ce80ca0), and `upgrade_from_entry_serde_keys_match_lifted_
        // m2_upgrade_from_key_consts` (36ffe65) pins established on the
        // sibling M2 supervision-tree, M3 [`Membro`] per-entry, and M2
        // [`UpgradeFromEntry`] per-entry axes — extended here to the
        // enclosing M0 [`Caixa`] top-level axis so the last of the four
        // multi-word top-level [`Caixa`] serde-derived JSON keys
        // (`depsDev`) joins the substrate's "one canonical byte-string
        // per typed serialized-key axis" discipline.
        use crate::supervisor::{ChildSpec, RestartPolicy, RestartStrategy};
        use crate::upgrade::{UpgradeFromEntry, UpgradeInstruction};
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps_dev = vec![Dep::simple("tatara-check", "^0.1")];
        c.upgrade_from = vec![UpgradeFromEntry {
            from: "0.0.1".into(),
            instructions: vec![UpgradeInstruction::Restart],
        }];
        c.estrategia = Some(RestartStrategy::OneForOne);
        c.max_restarts = Some(3);
        c.restart_window = Some("60s".into());
        c.children = vec![ChildSpec {
            caixa: "child".into(),
            versao: "^0.1".into(),
            restart: RestartPolicy::Permanent,
        }];
        let json = serde_json::to_string(&c).unwrap();
        for key in [
            crate::render::CAIXA_KEY_DEPS_DEV,
            crate::render::M2_KEY_UPGRADE_FROM,
            crate::render::SUPERVISOR_KEY_MAX_RESTARTS,
            crate::render::SUPERVISOR_KEY_RESTART_WINDOW,
        ] {
            let quoted = format!("\"{key}\"");
            assert!(
                json.contains(&quoted),
                "serialized Caixa must carry the lifted top-level \
                 multi-word byte-sequence {quoted} verbatim in the JSON \
                 emission (got: {json})",
            );
        }
    }

    #[test]
    fn caixa_top_level_multi_word_key_consts_are_pairwise_distinct() {
        // Cross-axis drift-detection pin: a future collapse of the four
        // canonical [`Caixa`] top-level multi-word byte-strings onto the
        // same value (e.g. an accidental copy-paste flip of
        // [`crate::render::CAIXA_KEY_DEPS_DEV`] to also read
        // `"upgradeFrom"`) would silently reroute every downstream
        // `Value::get(<key>)` probe on one axis onto the sibling axis's
        // top-level entry and pass every propagation-probe test that
        // expected only the stale axis's value. Peer of the sibling
        // four-way distinct pin on the `SUPERVISOR_KEY_*` tetrad
        // (40cc4e5) and the two-way pin on `MEMBRO_KEY_*` (ce80ca0).
        let all = [
            crate::render::CAIXA_KEY_DEPS_DEV,
            crate::render::M2_KEY_UPGRADE_FROM,
            crate::render::SUPERVISOR_KEY_MAX_RESTARTS,
            crate::render::SUPERVISOR_KEY_RESTART_WINDOW,
        ];
        for (i, a) in all.iter().enumerate() {
            for b in all.iter().skip(i + 1) {
                assert_ne!(
                    a, b,
                    "Caixa top-level multi-word key consts must be \
                     pairwise-distinct canonical byte-sequences — got \
                     `{a}` == `{b}`",
                );
            }
        }
    }

    #[test]
    fn caixa_top_level_multi_word_key_consts_are_lower_camel_case_shape() {
        // Shape-pin: every [`Caixa`] top-level multi-word key const must
        // be a lowerCamelCase byte-sequence (no `snake_case`
        // underscores, no `kebab-case` hyphens, no leading colon, no
        // `PascalCase` leading capital, no whitespace / dots) — the
        // canonical shape the `#[serde(rename_all = "camelCase")]`
        // derive produces on [`Caixa`]. A future flip to a
        // non-camelCase attribute at the derive surfaces both here
        // (this test fails on the stale-constant shape) and at
        // `caixa_multi_word_serde_keys_match_lifted_top_level_key_consts`
        // (that test fails on the mismatch between const and derive).
        // Peer with `membro_key_consts_are_lower_camel_case_shape`
        // (ce80ca0) and `supervisor_key_consts_are_lower_camel_case_shape`
        // (40cc4e5) on the sibling per-entry / supervisor-tree axes.
        for key in [
            crate::render::CAIXA_KEY_DEPS_DEV,
            crate::render::M2_KEY_UPGRADE_FROM,
            crate::render::SUPERVISOR_KEY_MAX_RESTARTS,
            crate::render::SUPERVISOR_KEY_RESTART_WINDOW,
        ] {
            assert!(
                !key.is_empty(),
                "Caixa top-level multi-word key const must be non-empty \
                 (got {key:?})"
            );
            let first = key.chars().next().unwrap();
            assert!(
                first.is_ascii_lowercase(),
                "Caixa top-level multi-word key const must lead with an \
                 ASCII-lowercase byte (got {key:?}, leads with {first:?})",
            );
            assert!(
                key.chars().all(|c| c.is_ascii_alphanumeric()),
                "Caixa top-level multi-word key const must be \
                 ASCII-alphanumeric only — no `_` / `-` / `:` / `.` / \
                 whitespace (got {key:?})",
            );
        }
    }

    #[test]
    fn caixa_key_deps_dev_pins_canonical_camel_case_byte_string() {
        // Scalar-value pin: the byte-string the
        // [`crate::render::CAIXA_KEY_DEPS_DEV`] const resolves to,
        // asserted verbatim. A future rebrand (`depsDev` → `devDeps`
        // matching Cargo's verbatim `dev-dependencies` axis, `depsDev`
        // → `depsTest` matching a hypothetical per-test-target
        // vocabulary flip) lands as an edit to exactly one const AND
        // one derive attribute — the sibling
        // `caixa_multi_word_serde_keys_match_lifted_top_level_key_consts`
        // pin already ties the const to the derive attribute, so a
        // rebrand that touches only one side of the pair fails at
        // caixa-core build time. Same "scalar-value pin per const"
        // discipline the sibling
        // `m2_top_level_author_key_consts_pin_canonical_kebab_case_labels`
        // (f49c8b0) and `contrato_key_consts_pin_canonical_camel_case_labels`
        // (ca463a4) pins carry on the peer M2 / M3 top-level slot axes.
        assert_eq!(crate::render::CAIXA_KEY_DEPS_DEV, "depsDev");
    }

    #[test]
    fn caixa_key_deps_pins_canonical_byte_string() {
        // Scalar-value pin: the byte-string the
        // [`crate::render::CAIXA_KEY_DEPS`] const resolves to, asserted
        // verbatim. Peer of `caixa_key_deps_dev_pins_canonical_camel_case_byte_string`
        // on the two-list dep-graph serialized-key axis — the sibling
        // pin covers the multi-word `deps_dev → depsDev` camelCase
        // arm, this pin covers the single-word `deps → deps` no-op arm
        // (the [`crate::Caixa::deps`] field name carries no `_`, so the
        // `#[serde(rename_all = "camelCase")]` derive is a no-op on this
        // axis and the emitted JSON key equals the source-side field
        // name byte-for-byte). A future [`crate::Caixa::deps`] field
        // rename (`deps` → `dependencies` matching Cargo's verbatim
        // `[dependencies]` axis, `deps` → `runtime_deps` matching a
        // hypothetical per-runtime-target vocabulary flip) OR an added
        // `#[serde(rename = "…")]` explicit override lands as an edit
        // to exactly one const AND one derive-attr / field name — the
        // sibling `caixa_deps_serde_key_matches_lifted_caixa_key_deps`
        // pin ties the const to the emitted JSON key, so a rebrand
        // that touches only one side of the pair fails at caixa-core
        // build time.
        assert_eq!(crate::render::CAIXA_KEY_DEPS, "deps");
    }

    #[test]
    fn caixa_deps_serde_key_matches_lifted_caixa_key_deps() {
        // Load-bearing invariant on the single-word `deps` top-level
        // axis: the byte-string [`crate::render::CAIXA_KEY_DEPS`] pins
        // must appear verbatim in the JSON [`Caixa::to_lisp`]'s
        // `serde_json::to_value(self)` step emits. Serialize a
        // populated [`Caixa`] whose `:deps` slot carries at least one
        // entry (the `#[serde(default)]` attribute on the field emits
        // an empty `[]` even without members, but a non-empty vec
        // additionally covers the codec's per-`Dep`-entry emission
        // path) and pin that `"deps"` appears verbatim in the JSON
        // emission — a future accidental `rename_all = "snake_case"` /
        // `"kebab-case"` flip at the derive attribute (or an added
        // `#[serde(rename = "…")]` explicit override on the field, or
        // a Rust field rename) would break every [`Caixa::to_lisp`]
        // round-trip and the future M4 operator-side manifest ingest's
        // `Value::get(CAIXA_KEY_DEPS)` navigation — surfaces here as a
        // build-time test failure at `manifest.rs`, not as an
        // apply-time `.get(<stale-canonical-const>)` returning `None`
        // far from the drift's commit. Peer of the sibling
        // `caixa_multi_word_serde_keys_match_lifted_top_level_key_consts`
        // multi-word pin on the same M0 [`Caixa`] top-level
        // serialized-key axis, extended here to the single-word arm
        // the multi-word test's `rename_all = "camelCase"` sweep can't
        // reach (single-word `deps → deps` is a no-op the multi-word
        // pin's `\"depsDev\"` / `\"upgradeFrom\"` / `\"maxRestarts\"` /
        // `\"restartWindow\"` byte-scan can never observe).
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep::simple("caixa-core", "^0.1")];
        let json = serde_json::to_string(&c).unwrap();
        let quoted = format!("\"{}\"", crate::render::CAIXA_KEY_DEPS);
        assert!(
            json.contains(&quoted),
            "serialized Caixa must carry the lifted top-level `deps` \
             byte-sequence {quoted} verbatim in the JSON emission (got: \
             {json})",
        );
    }

    #[test]
    fn caixa_dep_graph_two_list_key_consts_are_pairwise_distinct() {
        // Cross-axis drift-detection pin on the two-list dep-graph
        // renderer-side wire-key axis: a future collapse of the
        // canonical [`crate::render::CAIXA_KEY_DEPS`] /
        // [`crate::render::CAIXA_KEY_DEPS_DEV`] byte-strings onto the
        // same value (e.g. an accidental copy-paste flip of
        // `CAIXA_KEY_DEPS_DEV` to also read `"deps"`) would silently
        // reroute every downstream `Value::get(<key>)` probe on one
        // axis onto the sibling axis's dep-list and pass every
        // propagation-probe test that expected only the stale axis's
        // value — a dev-only dep would land in the runtime closure at
        // publish time, or a runtime dep would be excluded from the
        // published lacre. Peer of the sibling four-way distinct pin
        // on the top-level multi-word tetrad
        // (`caixa_top_level_multi_word_key_consts_are_pairwise_distinct`)
        // and the two-way pin on the sibling
        // [`DEP_AUTHOR_KEY_DEPS`] / [`DEP_AUTHOR_KEY_DEPS_DEV`]
        // author-facing arm (4da6fba's test), extended here to the
        // renderer-side wire-key arm of the same two-list dep-graph
        // axis so both halves of the "one canonical byte-string per
        // typed axis per (author, wire)" grid carry the same
        // distinct-ness discipline.
        assert_ne!(
            crate::render::CAIXA_KEY_DEPS,
            crate::render::CAIXA_KEY_DEPS_DEV,
            "CAIXA_KEY_DEPS and CAIXA_KEY_DEPS_DEV must be distinct \
             canonical byte-sequences on the two-list dep-graph \
             renderer-side wire-key axis"
        );
    }

    // ── DepList / Caixa::push_dep pin ────────────────────────────────
    //
    // The compounding pin: the two-arm closed-set typed enum
    // [`crate::dep::DepList`] carries the runtime-closure `:deps`
    // (`Prod`) vs dev-only-closure `:deps-dev` (`Dev`) dispatch every
    // consumer of the top-level manifest's dep-mutation surface reads
    // through, and the typed dispatch [`Caixa::push_dep`] on the
    // substrate primitive folds the "select list → check within-list
    // dup → push" cascade onto one method call. Prior to this landing
    // the two axes lived across two `&'static str` constants
    // (`DEP_AUTHOR_KEY_DEPS`, `DEP_AUTHOR_KEY_DEPS_DEV`) with no closed-
    // set type carrying the pair; the `feira add` mutation site's
    // inline `if self.dev { &mut caixa.deps_dev } else { &mut
    // caixa.deps }` dispatch expressed no compile-time link back to
    // the substrate primitive, and a future third dep-list axis would
    // have silently split at every open-coded mutation site.

    #[test]
    fn dep_list_as_str_routes_through_lifted_author_key_constants() {
        // Every arm returns the same `&'static str` the substrate's
        // canonical `DEP_AUTHOR_KEY_DEPS` / `DEP_AUTHOR_KEY_DEPS_DEV`
        // constants carry. A future rebrand on either constant reaches
        // the enum through one edit; a regression to inline literals
        // (e.g. `Prod => ":deps"`) would silently split the diagnostic
        // quotes from the wire-format constants every consumer routes
        // through and this pin flags it at build time.
        assert_eq!(
            crate::dep::DepList::Prod.as_str(),
            crate::render::DEP_AUTHOR_KEY_DEPS
        );
        assert_eq!(
            crate::dep::DepList::Dev.as_str(),
            crate::render::DEP_AUTHOR_KEY_DEPS_DEV
        );
    }

    #[test]
    fn dep_list_display_routes_through_as_str() {
        // Same as-str-through-Display convergence discipline the
        // sibling closed-set typed enums carry — a `format!("{list}")`
        // call must land byte-for-byte on the accessor's return so a
        // future consumer that formats the enum for a diagnostic line
        // reaches the same wire-format constant the wire-format
        // producers do.
        assert_eq!(
            format!("{}", crate::dep::DepList::Prod),
            crate::dep::DepList::Prod.as_str()
        );
        assert_eq!(
            format!("{}", crate::dep::DepList::Dev),
            crate::dep::DepList::Dev.as_str()
        );
    }

    #[test]
    fn dep_list_all_enumerates_every_variant_once() {
        // Exhaustive-iteration pin — every arm appears exactly once in
        // `ALL`, matching the closed set the compiler enforces on the
        // sibling `match self` arms. A future variant addition that
        // extends only one method's match without extending `ALL`
        // would silently drop the new arm from every consumer that
        // iterates the slice.
        let variants: &[crate::dep::DepList] = crate::dep::DepList::ALL;
        assert!(variants.contains(&crate::dep::DepList::Prod));
        assert!(variants.contains(&crate::dep::DepList::Dev));
        assert_eq!(variants.len(), 2);
    }

    #[test]
    fn dep_list_from_wire_returns_prod_on_deps_wire_scalar() {
        // Reverse projection on the two-list dep-graph axis: the
        // author-surface wire tag the sibling `as_str` emitter walks
        // for `Prod` (`:deps` via `DEP_AUTHOR_KEY_DEPS`) parses back to
        // `Some(DepList::Prod)`. A regression that hand-rolled the
        // per-arm match without routing through the lifted
        // `DEP_AUTHOR_KEY_DEPS` const would silently disagree on any
        // future wire-tag rebrand and this pin flags it at build time.
        assert_eq!(
            crate::dep::DepList::from_wire(crate::render::DEP_AUTHOR_KEY_DEPS),
            Some(crate::dep::DepList::Prod)
        );
    }

    #[test]
    fn dep_list_from_wire_returns_dev_on_deps_dev_wire_scalar() {
        // Peer of the `Prod`-arm pin on the dev-only axis: the
        // author-surface wire tag the sibling `as_str` emitter walks
        // for `Dev` (`:deps-dev` via `DEP_AUTHOR_KEY_DEPS_DEV`) parses
        // back to `Some(DepList::Dev)`. Same drift-detection posture
        // as the peer arm — the sibling method `match` arms are
        // compiler-checked exhaustive so a future variant addition
        // trips at build time.
        assert_eq!(
            crate::dep::DepList::from_wire(crate::render::DEP_AUTHOR_KEY_DEPS_DEV),
            Some(crate::dep::DepList::Dev)
        );
    }

    #[test]
    fn dep_list_from_wire_returns_none_on_unknown_wire_scalar() {
        // Every input outside the closed-set arm-string set the
        // sibling `as_str` emitter walks lands on the terminal `None`
        // fallback — no silent-accept surface. Sweeps a set of
        // plausibly-adjacent scalars (unprefixed wire form, PascalCase
        // rebrand candidates, foreign wire tags, empty string) so a
        // future variant addition that widened one wire form without
        // extending the emitter's arm-set would trip the sibling
        // round-trip pin below rather than silently accepting the new
        // form here.
        for candidate in [
            "",
            "deps",
            "deps-dev",
            ":deps ",
            ":Deps",
            ":DEPS",
            ":build-dep",
            ":tool-dep",
            "prod",
            "dev",
        ] {
            assert_eq!(
                crate::dep::DepList::from_wire(candidate),
                None,
                "from_wire({candidate:?}) must return None; every input outside \
                 the {{DEP_AUTHOR_KEY_DEPS, DEP_AUTHOR_KEY_DEPS_DEV}} accept-set \
                 the sibling as_str emitter walks lands on the terminal fallback",
            );
        }
    }

    #[test]
    fn dep_list_round_trips_through_as_str_and_from_wire() {
        // Load-bearing round-trip pin: every arm the `ALL` iteration
        // exposes survives the `as_str` → `from_wire` composition
        // byte-for-byte. Same discipline the sibling closed-set enums
        // carry — `CaixaKind` /
        // `RestartStrategy` / `RestartPolicy` /
        // `PlacementStrategy` — extended onto the two-list dep-graph
        // axis. A future variant addition that extends `ALL` +
        // `as_str` without extending `from_wire` (or vice versa)
        // trips at build time on this iteration because the compiler
        // enforces exhaustiveness on the sibling `match self` arms.
        for &list in crate::dep::DepList::ALL {
            assert_eq!(
                crate::dep::DepList::from_wire(list.as_str()),
                Some(list),
                "DepList::from_wire(as_str({list:?})) must round-trip to Some({list:?}) — \
                 a silent split between the forward emitter and the reverse parser \
                 would drift the two halves of the two-list dep-graph axis's typed dispatch",
            );
        }
    }

    #[test]
    fn push_dep_routes_to_deps_slot_on_prod_arm() {
        // The `Prod` arm dispatches to the runtime-closure `:deps`
        // slot every downstream lacre-pipeline consumer resolves at
        // build time. A future arm that regressed to inline `&mut
        // self.deps_dev` on the `Prod` path would silently reroute
        // every runtime dep into the dev-only closure at publish time
        // — this pin refuses that regression.
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        let before_deps = caixa.deps().len();
        let before_deps_dev = caixa.deps_dev().len();
        let dep = Dep {
            nome: "caixa-teia".to_string(),
            versao: "^0.1".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Prod, dep)
            .expect("first push into :deps succeeds");
        assert_eq!(caixa.deps().len(), before_deps + 1);
        assert_eq!(caixa.deps_dev().len(), before_deps_dev);
        assert_eq!(caixa.deps().last().unwrap().nome(), "caixa-teia");
    }

    #[test]
    fn push_dep_routes_to_deps_dev_slot_on_dev_arm() {
        // Peer of the sibling `Prod`-arm dispatch pin — the `Dev` arm
        // must dispatch to the dev-only-closure `:deps-dev` slot every
        // downstream test-facing artifact resolver reads. A future
        // regression that inverted the two arms would silently route
        // every dev-only dep into the runtime closure at publish time
        // and this pin catches it before the drift ships.
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        let dep = Dep {
            nome: "tatara-check".to_string(),
            versao: "*".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Dev, dep)
            .expect("first push into :deps-dev succeeds");
        assert!(caixa.deps().is_empty());
        assert_eq!(caixa.deps_dev().len(), 1);
        assert_eq!(caixa.deps_dev().last().unwrap().nome(), "tatara-check");
    }

    #[test]
    fn push_dep_refuses_within_list_duplicate_nome_with_typed_error() {
        // Within-list dup check routes through the canonical
        // [`DepError::DuplicateNome`] carrier — the substrate's typed
        // diagnostic for the same axis [`Caixa::validate_deps`]'s
        // parse-time [`crate::render::insert_first_seen`] walk raises
        // on. Prior to the lift the mutation site's inline
        // `bail!("dep '{}' already declared", …)` string-diagnostic
        // path expressed no through-line back to the typed error;
        // routing every dep-list refusal through one carrier means an
        // author reading a `feira add` refusal and a `feira build`
        // refusal reaches for the same corrective surface without
        // switching diagnostic idioms.
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        let dep = Dep {
            nome: "caixa-teia".to_string(),
            versao: "^0.1".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Prod, dep.clone())
            .expect("first push succeeds");
        let dup = Dep {
            nome: "caixa-teia".to_string(),
            versao: "^0.2".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        let err = caixa
            .push_dep(crate::dep::DepList::Prod, dup)
            .expect_err("second push with same :nome refuses");
        assert_eq!(
            err,
            DepError::DuplicateNome {
                nome: "caixa-teia".to_string(),
                list: crate::render::DEP_AUTHOR_KEY_DEPS,
            }
        );
        // The refused mutation must not corrupt the target list —
        // exactly one entry lives past the refusal, matching the
        // canonical single-source-of-truth invariant `Caixa::deps()`
        // carries.
        assert_eq!(caixa.deps().len(), 1);
    }

    #[test]
    fn push_dep_refuses_dup_on_dev_list_arm_names_deps_dev_key() {
        // Peer of the sibling `Prod`-arm dup-refusal pin — the `Dev`
        // arm's refusal must carry `DEP_AUTHOR_KEY_DEPS_DEV` in the
        // `list` payload so a future author reading the refusal grep's
        // for the correct `:deps-dev` block in their `caixa.lisp`,
        // not the sibling `:deps` block the runtime closure resolves.
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        let dep = Dep {
            nome: "tatara-check".to_string(),
            versao: "*".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Dev, dep.clone())
            .expect("first push succeeds");
        let err = caixa
            .push_dep(crate::dep::DepList::Dev, dep)
            .expect_err("second push with same :nome refuses");
        assert!(matches!(
            err,
            DepError::DuplicateNome {
                ref nome,
                list,
            } if nome == "tatara-check"
                && list == crate::render::DEP_AUTHOR_KEY_DEPS_DEV
        ));
    }

    #[test]
    fn push_dep_allows_same_nome_across_prod_and_dev_lists() {
        // The within-list dup check is scoped to the target arm — a
        // caixa may legitimately carry the same `:nome` under both
        // `:deps` and `:deps-dev` (though the substrate's peer
        // [`crate::Caixa::validate_deps`] walk still refuses the
        // shape at parse time; the mutation-site refusal is scoped to
        // the mutation-site's list to match the peer parse-time
        // per-list [`crate::render::insert_first_seen`] discipline).
        // The two arms hold independent seen-sets.
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        let dep_prod = Dep {
            nome: "shared".to_string(),
            versao: "^0.1".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        let dep_dev = Dep {
            nome: "shared".to_string(),
            versao: "*".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Prod, dep_prod)
            .expect("push into :deps succeeds");
        caixa
            .push_dep(crate::dep::DepList::Dev, dep_dev)
            .expect("push same :nome into :deps-dev succeeds");
        assert_eq!(caixa.deps().len(), 1);
        assert_eq!(caixa.deps_dev().len(), 1);
    }

    #[test]
    fn deps_of_prod_returns_the_deps_slot_verbatim() {
        // The `Prod` arm of the typed-dispatch [`Caixa::deps_of`] read
        // accessor must project onto the runtime-closure `:deps` slot —
        // element-equal and length-equal to the sibling per-slot
        // [`Caixa::deps`] accessor's return over every per-caixa fixture.
        // A future arm that regressed to `self.deps_dev()` on the `Prod`
        // path would silently reroute every downstream typed-dispatch
        // walker (the [`Caixa::validate_deps`] per-list
        // [`crate::render::insert_first_seen`] dedup walk, any future
        // per-axis-parametrised consumer) into the sibling dev-only
        // closure and this pin refuses that regression.
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        assert_eq!(caixa.deps_of(crate::dep::DepList::Prod), caixa.deps());
        assert_eq!(caixa.deps_of(crate::dep::DepList::Prod).len(), 0);
        let dep = Dep {
            nome: "caixa-teia".to_string(),
            versao: "^0.1".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Prod, dep.clone())
            .expect("push into :deps succeeds");
        assert_eq!(caixa.deps_of(crate::dep::DepList::Prod), caixa.deps());
        assert_eq!(caixa.deps_of(crate::dep::DepList::Prod).len(), 1);
        assert_eq!(
            caixa.deps_of(crate::dep::DepList::Prod)[0].nome(),
            "caixa-teia"
        );
    }

    #[test]
    fn deps_of_dev_returns_the_deps_dev_slot_verbatim() {
        // Peer of the sibling `Prod`-arm pin — the `Dev` arm of
        // [`Caixa::deps_of`] must project onto the dev-only-closure
        // `:deps-dev` slot, element-equal and length-equal to the
        // sibling per-slot [`Caixa::deps_dev`] accessor's return. A
        // future regression that inverted the two arms would silently
        // route every dev-list walker onto the runtime closure and this
        // pin catches it before the drift ships.
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        assert_eq!(caixa.deps_of(crate::dep::DepList::Dev), caixa.deps_dev());
        assert_eq!(caixa.deps_of(crate::dep::DepList::Dev).len(), 0);
        let dep = Dep {
            nome: "tatara-check".to_string(),
            versao: "*".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Dev, dep)
            .expect("push into :deps-dev succeeds");
        assert_eq!(caixa.deps_of(crate::dep::DepList::Dev), caixa.deps_dev());
        assert_eq!(caixa.deps_of(crate::dep::DepList::Dev).len(), 1);
        assert_eq!(
            caixa.deps_of(crate::dep::DepList::Dev)[0].nome(),
            "tatara-check"
        );
    }

    #[test]
    fn deps_of_exhaustive_over_dep_list_all_covers_the_two_slots() {
        // Composition pin: iterating [`crate::dep::DepList::ALL`] through
        // [`Caixa::deps_of`] must land on the same two-slot partition the
        // per-slot [`Caixa::deps`] / [`Caixa::deps_dev`] accessors
        // expose — the canonical dispatch a future per-axis-parametrised
        // walker (a future `feira app graph` per-list dep summary, a
        // future M4 per-cluster dev-closure-audit overlay the CR
        // materializer resolves per-CR) reads through. Prior to the
        // lift the two-block iteration lived open-coded at every walker,
        // so a future third dep-list axis (`:deps-build`, per CAIXA-SDLC
        // §I) would have had to grow a third block at every consumer.
        // A regression that dropped the `Dev` arm from `ALL` would flip
        // the collected pairs to `[(":deps", &[])]` alone and this pin
        // refuses that shape.
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        let prod_dep = Dep {
            nome: "caixa-teia".to_string(),
            versao: "^0.1".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        let dev_dep = Dep {
            nome: "tatara-check".to_string(),
            versao: "*".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Prod, prod_dep)
            .expect("push into :deps succeeds");
        caixa
            .push_dep(crate::dep::DepList::Dev, dev_dep)
            .expect("push into :deps-dev succeeds");
        let collected: Vec<(&'static str, usize, &str)> = crate::dep::DepList::ALL
            .iter()
            .map(|&list| {
                let slice = caixa.deps_of(list);
                (list.as_str(), slice.len(), slice[0].nome())
            })
            .collect();
        assert_eq!(
            collected,
            vec![
                (crate::render::DEP_AUTHOR_KEY_DEPS, 1, "caixa-teia"),
                (crate::render::DEP_AUTHOR_KEY_DEPS_DEV, 1, "tatara-check"),
            ]
        );
    }

    #[test]
    fn caixa_deps_of_is_const_fn() {
        // Fail-before-pass-after pin on [`Caixa::deps_of`]'s
        // `const`-eval-surface posture. The typed-dispatch read
        // accessor forwards through the sibling `pub const fn`
        // [`Caixa::deps`] / [`Caixa::deps_dev`] per-slot slice
        // accessors on the two [`crate::dep::DepList`] enum arms —
        // every operator in the body is already `const`-callable
        // (`DepList` is a plain `#[derive(Copy)]` closed-set
        // discriminator so the `match` arms are const-evaluable, and
        // each arm dispatches through the sibling `pub const fn`
        // slice accessor). Any future accidental downgrade to
        // non-`const` fails the `deps_of_via_const_fn` wrapper below
        // at caixa-core build time with E0015 (`cannot call non-const
        // method`), strictly stronger than a runtime `assert!` and
        // side-stepping the destructor-in-const restriction the
        // `Caixa` fixture's owning `String` / `Vec<Dep>` carriers
        // rule out on the direct-`const _: () = assert!(...)`
        // residence.
        //
        // Peer of the sibling outer-`Caixa` accessor family pins
        // ([`caixa_outer_string_slice_return_accessor_family_is_const_fn`]
        // on the `&[String]` universal-axis surface,
        // [`caixa_outer_composite_slice_return_accessor_family_is_const_fn`]
        // on the outer `&[T]` composite-slice surface,
        // [`caixa_outer_option_composite_reference_return_accessor_family_is_const_fn`]
        // on the outer `Option<&Composite>` surface) — this pin
        // extends the `const`-eval-surface discipline onto the outer-
        // `Caixa` typed-dispatch read surface on the [`DepList`]-keyed
        // dep-list axis, closing the outer-`Caixa` accessor family's
        // last unlifted `pub fn` on the read side.
        const fn deps_of_via_const_fn(c: &Caixa, list: crate::dep::DepList) -> &[Dep] {
            c.deps_of(list)
        }
        let src = Caixa::template("host");
        let mut caixa = Caixa::from_lisp(&src).expect("template parses");
        // Empty-list arm: both `Prod` and `Dev` degenerate to the
        // empty slice with no silent `None` collapse — the
        // `#[serde(default)]` `Vec::new()` fold every `defcaixa` form
        // that omits the slot lands on.
        assert!(deps_of_via_const_fn(&caixa, crate::dep::DepList::Prod).is_empty());
        assert!(deps_of_via_const_fn(&caixa, crate::dep::DepList::Dev).is_empty());
        assert_eq!(
            deps_of_via_const_fn(&caixa, crate::dep::DepList::Prod),
            caixa.deps()
        );
        assert_eq!(
            deps_of_via_const_fn(&caixa, crate::dep::DepList::Dev),
            caixa.deps_dev()
        );
        // Populated arms: each list carries its own entry, and the
        // wrapper / direct dispatches agree byte-for-byte on the
        // slice-view under both non-empty arms.
        let prod_dep = Dep {
            nome: "caixa-teia".to_string(),
            versao: "^0.1".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        let dev_dep = Dep {
            nome: "tatara-check".to_string(),
            versao: "*".to_string(),
            fonte: None,
            opcional: false,
            caracteristicas: Vec::new(),
        };
        caixa
            .push_dep(crate::dep::DepList::Prod, prod_dep)
            .expect("push into :deps succeeds");
        caixa
            .push_dep(crate::dep::DepList::Dev, dev_dep)
            .expect("push into :deps-dev succeeds");
        assert_eq!(
            deps_of_via_const_fn(&caixa, crate::dep::DepList::Prod),
            caixa.deps()
        );
        assert_eq!(
            deps_of_via_const_fn(&caixa, crate::dep::DepList::Dev),
            caixa.deps_dev()
        );
        assert_eq!(
            deps_of_via_const_fn(&caixa, crate::dep::DepList::Prod)[0].nome(),
            "caixa-teia"
        );
        assert_eq!(
            deps_of_via_const_fn(&caixa, crate::dep::DepList::Dev)[0].nome(),
            "tatara-check"
        );
    }

    #[test]
    fn validate_deps_iterates_through_dep_list_all_via_deps_of() {
        // Composition pin: the [`Caixa::validate_deps`] parse-time gate
        // must route its per-list [`crate::render::insert_first_seen`]
        // dedup walk through [`Caixa::deps_of`] + [`crate::dep::DepList::ALL`]
        // rather than the pre-lift open-coded two-block iteration over
        // `self.deps()` + `self.deps_dev()`. A regression that dropped
        // one arm (e.g. hand-inlining `self.deps()` alone) would silently
        // stop refusing within-list dups on the sibling arm; a
        // regression that flipped the arm-to-list-key mapping
        // (`Dev => DEP_AUTHOR_KEY_DEPS`) would silently mislabel the
        // diagnostic surface. Both drifts surface here through a paired
        // duplicate-name refusal per arm plus an offending-list-key
        // check on the emitted [`DepError::DuplicateNome`] carrier.
        for &list in crate::dep::DepList::ALL {
            let src = Caixa::template("host");
            let mut caixa = Caixa::from_lisp(&src).expect("template parses");
            let dup = Dep {
                nome: "twin".to_string(),
                versao: "^0.1".to_string(),
                fonte: None,
                opcional: false,
                caracteristicas: Vec::new(),
            };
            match list {
                crate::dep::DepList::Prod => {
                    caixa.deps.push(dup.clone());
                    caixa.deps.push(dup);
                }
                crate::dep::DepList::Dev => {
                    caixa.deps_dev.push(dup.clone());
                    caixa.deps_dev.push(dup);
                }
            }
            let err = caixa
                .validate_deps()
                .expect_err("within-list duplicate :nome must refuse");
            assert_eq!(
                err,
                DepError::DuplicateNome {
                    nome: "twin".to_string(),
                    list: list.as_str(),
                },
                "validate_deps on {list} arm must emit \
                 DepError::DuplicateNome carrying the arm's own \
                 as_str() diagnostic — the arm-to-list-key mapping \
                 flowed through DepList::ALL + Caixa::deps_of"
            );
        }
    }

    #[test]
    fn caixa_licenca_default_pins_canonical_mit_byte() {
        // Bridge-arm pin: [`CAIXA_LICENCA_DEFAULT`] resolves to the
        // canonical SPDX-`"MIT"` byte today, the same license expression
        // every peer substrate-side consumer of the author-omitted
        // `:licenca` slot ([`caixa-helm`]'s `build_readme` fallback arm at
        // `caixa-helm/src/lib.rs`, the future M4
        // `mesh.pleme.io/v1alpha1/Aplicacao` CR materializer's per-CR
        // `Chart.yaml annotations["artifacthub.io/license"]` emitter this
        // crate's [`Caixa::validate_licenca`] docstring roadmap already
        // names as the second consumer) fills into its per-consumer
        // README/annotation emit site. Pin the literal here (peer with the
        // [`crate::version::DEFAULT_PUBLISH_TAG_PREFIX`] /
        // [`crate::version::DEFAULT_GIT_REMOTE`] /
        // [`crate::version::DEFAULT_PLEME_GIT_ORG`] canonical-literal pins
        // on the sibling lifted-constant surfaces) so a future
        // substrate-side license-fallback rebrand surfaces here as a
        // coordinated edit-point: the sibling caixa-helm
        // `build_readme_license_line_routes_through_lifted_caixa_licenca_default`
        // pinning test already pins the equality at the renderer-emit
        // axis; this pin closes the second coordinate of the pair by
        // anchoring the lifted constant's current byte to the canonical
        // CAIXA-SDLC §I license scaffold's documented shape.
        assert_eq!(CAIXA_LICENCA_DEFAULT, "MIT");
    }

    // ── Caixa::validate_upgrade_from — compound per-Caixa entry gate on ──
    // ── the M2 `:upgrade-from` slot: folds the three top-level        ──
    // ── `crate::upgrade` validators (per-entry + cross-entry           ──
    // ── duplicate-`:from`, cross-slot `:from < :versao` precedence,   ──
    // ── cross-slot `:state-change` ↔ `:on-state-change` composition)  ──
    // ── onto one substrate primitive. Byte-for-byte equivalent to the ──
    // ── pre-fold three-block cascade at                               ──
    // ── `crate::layout::StandardLayout::verify` under the same        ──
    // ── canonical dispatch order.                                     ──

    #[test]
    fn validate_upgrade_from_folds_per_entry_arm_matches_gate() {
        // Fail-before-pass-after per-arm equivalence pin on the
        // per-entry + cross-entry axis: a fixture whose `:upgrade-from`
        // carries a per-entry-invalid `:from` (git-tag shape `"v0.1.0"`,
        // which `semver::Version::parse` rejects) surfaces the same
        // [`crate::UpgradeError`] through the compound gate
        // [`Caixa::validate_upgrade_from`] and the standalone per-entry
        // gate [`crate::upgrade::validate_upgrade_from`] on the same
        // [`Caixa::upgrade_from`] slice. Pins the fold — a silent
        // regression that de-folded the per-entry arm would surface here
        // as a mismatch between the two dispatches. Sibling in shape to
        // the peer per-slot-≡-standalone equivalence pins the
        // [`crate::AplicacaoSpec::validate_contratos`] /
        // [`crate::MeshPolicy::validate`] /
        // [`crate::SupervisorSpec::validate_children`] compound gates
        // each carry on their axes.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.upgrade_from = vec![crate::UpgradeFromEntry {
            from: "v0.1.0".into(),
            instructions: vec![crate::UpgradeInstruction::Restart],
        }];
        let via_method = c.validate_upgrade_from().unwrap_err();
        let via_standalone = crate::upgrade::validate_upgrade_from(c.upgrade_from()).unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_upgrade_from must surface the per-entry \
             axis's diagnostic byte-equal to the standalone \
             `crate::upgrade::validate_upgrade_from` on the same \
             upgrade_from() slice"
        );
        assert!(
            matches!(
                via_method,
                crate::UpgradeError::FromInvalid { ref from, .. } if from == "v0.1.0"
            ),
            "expected FromInvalid on the git-tag-shape `:from`, got {via_method:?}"
        );
    }

    #[test]
    fn validate_upgrade_from_folds_versao_arm_matches_gate() {
        // Per-arm equivalence pin on the cross-slot `:from ↔ :versao`
        // precedence axis: a fixture with a well-formed `:from` (so the
        // per-entry arm passes) whose parsed semver is >= the caixa's
        // `:versao` under SemVer-2 precedence surfaces the same
        // [`crate::UpgradeError::FromNotBeforeVersao`] through both the
        // compound gate and the standalone
        // [`crate::upgrade::validate_upgrade_from_against_versao`] gate
        // keyed off the same `(upgrade_from, versao)` pair. Pins the
        // fold's second arm — reaching this arm through the compound
        // gate requires the per-entry arm to pass first, which itself
        // pins the per-arm cross-arm ordering.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.versao = "0.1.0".into();
        c.upgrade_from = vec![crate::UpgradeFromEntry {
            from: "0.2.0".into(),
            instructions: vec![crate::UpgradeInstruction::Restart],
        }];
        let via_method = c.validate_upgrade_from().unwrap_err();
        let via_standalone =
            crate::upgrade::validate_upgrade_from_against_versao(c.upgrade_from(), c.versao())
                .unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_upgrade_from must surface the \
             `:from >= :versao` diagnostic byte-equal to the standalone \
             `crate::upgrade::validate_upgrade_from_against_versao` on \
             the same (upgrade_from, versao) pair"
        );
        assert!(
            matches!(
                via_method,
                crate::UpgradeError::FromNotBeforeVersao { ref from, ref versao }
                    if from == "0.2.0" && versao == "0.1.0"
            ),
            "expected FromNotBeforeVersao carrying the offending pair, got {via_method:?}"
        );
    }

    #[test]
    fn validate_upgrade_from_folds_behavior_arm_matches_gate() {
        // Per-arm equivalence pin on the cross-slot `:state-change ↔
        // :on-state-change` composition axis: a fixture with a
        // well-formed `:from` strictly less than `:versao` (so the
        // per-entry and versao arms both pass) whose `:instructions`
        // list carries a `(:state-change …)` instruction with no
        // `:behavior :on-state-change` callback declared surfaces the
        // same [`crate::UpgradeError::StateChangeWithoutOnStateChangeCallback`]
        // through both the compound gate and the standalone
        // [`crate::upgrade::validate_upgrade_from_against_behavior`]
        // gate keyed off the same `(upgrade_from, behavior)` pair.
        // Reaching this arm through the compound gate requires both
        // prior arms to pass first — the ordering pin below pins the
        // per-arm dispatch order explicitly.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.versao = "0.2.0".into();
        c.behavior = None;
        c.upgrade_from = vec![crate::UpgradeFromEntry {
            from: "0.1.0".into(),
            instructions: vec![
                crate::UpgradeInstruction::LoadModule {
                    module: "demo".into(),
                },
                crate::UpgradeInstruction::StateChange {
                    script: std::path::PathBuf::from("lib/m.lisp"),
                },
                crate::UpgradeInstruction::SoftPurge {
                    module: "demo-old".into(),
                },
            ],
        }];
        let via_method = c.validate_upgrade_from().unwrap_err();
        let via_standalone =
            crate::upgrade::validate_upgrade_from_against_behavior(c.upgrade_from(), c.behavior())
                .unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_upgrade_from must surface the \
             `:state-change` ↔ `:on-state-change` composition \
             diagnostic byte-equal to the standalone \
             `crate::upgrade::validate_upgrade_from_against_behavior` \
             on the same (upgrade_from, behavior) pair"
        );
        assert!(
            matches!(
                via_method,
                crate::UpgradeError::StateChangeWithoutOnStateChangeCallback {
                    ref from,
                    ref script,
                } if from == "0.1.0" && script == &std::path::PathBuf::from("lib/m.lisp")
            ),
            "expected StateChangeWithoutOnStateChangeCallback carrying \
             the offending (from, script) pair, got {via_method:?}"
        );
    }

    #[test]
    fn validate_upgrade_from_per_entry_arm_fires_before_versao_arm() {
        // Cross-arm ordering pin between the first two arms of the
        // fold: a fixture carrying BOTH a per-entry-invalid `:from`
        // (`"v0.0.5"` — git-tag shape rejected by
        // [`crate::upgrade::validate_upgrade_from`]) AND a would-be
        // versao-precedence violation on a second entry (`"0.2.0" >=
        // :versao "0.1.0"`) surfaces the per-entry diagnostic first
        // through the compound gate. Sanity assertion: the second
        // entry alone under the same `:versao` trips the versao arm
        // on its own via the standalone
        // [`crate::upgrade::validate_upgrade_from_against_versao`], so
        // the per-entry-first surfacing is a real ordering property,
        // not a case where the versao arm silently accepts the
        // fixture. Pins the pre-fold layout wire-up's canonical
        // dispatch order (per-entry → versao → behavior) as a
        // property of the substrate primitive rather than a
        // convention of the layout call site.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.versao = "0.1.0".into();
        c.upgrade_from = vec![
            crate::UpgradeFromEntry {
                from: "v0.0.5".into(),
                instructions: vec![crate::UpgradeInstruction::Restart],
            },
            crate::UpgradeFromEntry {
                from: "0.2.0".into(),
                instructions: vec![crate::UpgradeInstruction::Restart],
            },
        ];
        let err = c.validate_upgrade_from().unwrap_err();
        assert!(
            matches!(
                err,
                crate::UpgradeError::FromInvalid { ref from, .. } if from == "v0.0.5"
            ),
            "per-entry arm must fire before versao arm — expected \
             FromInvalid on `v0.0.5`, got {err:?}"
        );
        // Sanity: the versao-violating second entry alone under the
        // same `:versao` trips the versao arm on its own — proves the
        // per-entry-first surfacing above is a real ordering property.
        let sanity = crate::upgrade::validate_upgrade_from_against_versao(
            &[crate::UpgradeFromEntry {
                from: "0.2.0".into(),
                instructions: vec![crate::UpgradeInstruction::Restart],
            }],
            "0.1.0",
        )
        .unwrap_err();
        assert!(
            matches!(sanity, crate::UpgradeError::FromNotBeforeVersao { .. }),
            "sanity: the versao-violating fixture alone must trip the \
             versao arm — got {sanity:?}"
        );
    }

    #[test]
    fn validate_upgrade_from_versao_arm_fires_before_behavior_arm() {
        // Cross-arm ordering pin between the second and third arms of
        // the fold: a fixture carrying BOTH a versao-precedence
        // violation (`:from "0.2.0" >= :versao "0.1.0"`) AND a
        // would-be missing-callback violation (a `(:state-change …)`
        // instruction with no `:behavior :on-state-change`) surfaces
        // the versao diagnostic first through the compound gate.
        // Sanity assertion: the missing-callback fixture alone (with
        // the versao-precedence violation removed by bumping
        // `:versao` past `:from`) trips the behavior arm on its own
        // via the standalone
        // [`crate::upgrade::validate_upgrade_from_against_behavior`],
        // so the versao-first surfacing is a real ordering property,
        // not a case where the behavior arm silently accepts the
        // fixture.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.versao = "0.1.0".into();
        c.behavior = None;
        c.upgrade_from = vec![crate::UpgradeFromEntry {
            from: "0.2.0".into(),
            instructions: vec![
                crate::UpgradeInstruction::LoadModule {
                    module: "demo".into(),
                },
                crate::UpgradeInstruction::StateChange {
                    script: std::path::PathBuf::from("lib/m.lisp"),
                },
            ],
        }];
        let err = c.validate_upgrade_from().unwrap_err();
        assert!(
            matches!(
                err,
                crate::UpgradeError::FromNotBeforeVersao { ref from, .. } if from == "0.2.0"
            ),
            "versao arm must fire before behavior arm — expected \
             FromNotBeforeVersao on `0.2.0`, got {err:?}"
        );
        // Sanity: the same instructions under a `:versao` that
        // accepts the `:from` (so the versao arm passes) trips the
        // behavior arm — proves the versao-first surfacing above is a
        // real ordering property.
        let sanity = crate::upgrade::validate_upgrade_from_against_behavior(
            &[crate::UpgradeFromEntry {
                from: "0.2.0".into(),
                instructions: vec![
                    crate::UpgradeInstruction::LoadModule {
                        module: "demo".into(),
                    },
                    crate::UpgradeInstruction::StateChange {
                        script: std::path::PathBuf::from("lib/m.lisp"),
                    },
                ],
            }],
            None,
        )
        .unwrap_err();
        assert!(
            matches!(
                sanity,
                crate::UpgradeError::StateChangeWithoutOnStateChangeCallback { .. }
            ),
            "sanity: the missing-callback fixture alone must trip the \
             behavior arm — got {sanity:?}"
        );
    }

    #[test]
    fn validate_upgrade_from_accepts_clean_fixture() {
        // Positive control: a well-formed `:upgrade-from` (single entry
        // with `:from` strictly less than `:versao`, no
        // `:state-change` instruction so the behavior arm is vacuous)
        // passes the compound gate cleanly. A future tightening of any
        // one arm's accepted set surfaces here as a test failure
        // first. Mirrors the peer `validate_versao_accepts_canonical_forms`
        // positive-control posture on the sibling per-Caixa gate.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.versao = "0.2.0".into();
        c.upgrade_from = vec![crate::UpgradeFromEntry {
            from: "0.1.0".into(),
            instructions: vec![crate::UpgradeInstruction::Restart],
        }];
        c.validate_upgrade_from()
            .expect("clean fixture must pass the compound `:upgrade-from` gate");
    }

    #[test]
    fn validate_upgrade_from_accepts_empty_upgrade_from() {
        // Positive control on the empty-list arm: a caixa without any
        // `:upgrade-from` block (the default `Vec::new()`
        // `#[serde(default)]` folds an omitted slot onto) passes the
        // compound gate cleanly regardless of `:versao` or `:behavior`
        // — each of the three standalone validators is vacuous on the
        // empty entry list. Pins the identity element of the fold on
        // the empty-slot side.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        assert!(
            c.upgrade_from().is_empty(),
            "template caixa must carry an empty :upgrade-from — got {:?}",
            c.upgrade_from()
        );
        c.validate_upgrade_from()
            .expect("empty :upgrade-from must pass the compound gate cleanly");
    }

    // ── Caixa::validate_limits — compound per-Caixa entry gate on   ──
    // ── the M2 `:limits` slot: folds the                            ──
    // ── [`crate::LimitsSpec::validate`] four-axis cascade on the    ──
    // ── present-slot arm and the `Option::None` identity element on ──
    // ── the absent-slot arm onto one substrate primitive.           ──
    // ── Byte-for-byte equivalent to the pre-fold                    ──
    // ── `if let Some(l) = caixa.limits() { l.validate() }`          ──
    // ── unwrap-and-dispatch pattern at                              ──
    // ── `crate::layout::StandardLayout::verify` (`layout.rs`).      ──

    #[test]
    fn validate_limits_folds_arm_matches_gate() {
        // Fail-before-pass-after per-arm equivalence pin on the
        // present-slot arm: a fixture whose `:limits` carries a
        // zero-floor-violating `:fuel` (`Some(0)`, which
        // [`crate::LimitsSpec::validate`] rejects through
        // [`crate::LimitsError::FuelZero`]) surfaces the same
        // [`crate::LimitsError`] byte-equal through both the compound
        // gate [`Caixa::validate_limits`] and the standalone
        // [`crate::LimitsSpec::validate`] gate on the same `LimitsSpec`
        // value. Pins the fold — a silent regression that de-folded
        // the present-slot arm would surface here as a mismatch
        // between the two dispatches. Sibling in shape to the peer
        // per-arm equivalence pins the
        // [`crate::AplicacaoSpec::validate_contratos`] /
        // [`crate::MeshPolicy::validate`] /
        // [`crate::SupervisorSpec::validate_children`] /
        // [`Caixa::validate_upgrade_from`] compound gates each carry
        // on their axes.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        let l = crate::LimitsSpec {
            memory: None,
            fuel: Some(0),
            wall_clock: None,
            cpu: None,
        };
        c.limits = Some(l);
        let via_method = c.validate_limits().unwrap_err();
        let via_standalone = l.validate().unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_limits must surface the present-slot \
             arm's diagnostic byte-equal to the standalone \
             `LimitsSpec::validate` on the same `LimitsSpec` value"
        );
        assert!(
            matches!(via_method, crate::LimitsError::FuelZero),
            "expected FuelZero on the zero-floor-violating `:fuel`, \
             got {via_method:?}"
        );
    }

    #[test]
    fn validate_limits_accepts_none() {
        // Positive control on the absent-slot arm (the fold's identity
        // element): a caixa without any `:limits` block (the
        // canonical "no bound declared — engine-default applies"
        // author shape [`crate::LimitsSpec::is_empty`]'s per-axis
        // `None` cascade reads, and the shape the [`Caixa::template`]
        // scaffold emits by construction) passes the compound gate
        // cleanly, regardless of any per-axis defect a subsequent
        // `Some(_)` binding would surface. Pins the identity element
        // of the fold on the absent-slot side, matching the peer
        // `validate_upgrade_from_accepts_empty_upgrade_from` positive-
        // control posture on the sibling M2 slot.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        assert!(
            c.limits().is_none(),
            "template caixa must carry an absent :limits — got {:?}",
            c.limits()
        );
        c.validate_limits()
            .expect("absent :limits must pass the compound gate cleanly");
    }

    #[test]
    fn validate_limits_accepts_clean_fixture() {
        // Positive control on the present-slot arm: a caixa whose
        // `:limits` is `Some(LimitsSpec::default())` (all four axes
        // `None` — every axis absent under the outer `Some(_)`
        // binding, so every present-slot arm on
        // [`crate::LimitsSpec::validate`] is vacuous) passes the
        // compound gate cleanly. A future tightening of any one axis
        // that surfaces a diagnostic on the all-`None` `LimitsSpec`
        // would land here as a test failure first. Pins the
        // present-slot arm's accept-shape on the canonical
        // "declared-but-empty" author fixture the
        // `limits_round_trip_via_json` peer already round-trips
        // (`caixa-core/src/manifest.rs:6971`).
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.limits = Some(crate::LimitsSpec::default());
        c.validate_limits()
            .expect("Some(LimitsSpec::default()) must pass the compound gate cleanly");
    }

    // ── Caixa::validate_behavior — compound per-Caixa entry gate on ──
    // ── the M2 `:behavior` slot's pure value-shape surface: folds   ──
    // ── the [`crate::BehaviorSpec::validate`] six-slot cascade on   ──
    // ── the present-slot arm and the `Option::None` identity        ──
    // ── element on the absent-slot arm onto one substrate primitive.──
    // ── Byte-for-byte equivalent to the pre-fold                    ──
    // ── `if let Some(b) = caixa.behavior() { b.validate() }`        ──
    // ── unwrap-and-dispatch pattern at                              ──
    // ── `crate::layout::StandardLayout::verify` (`layout.rs`). The  ──
    // ── on-disk callback-path existence walk stays open-coded at    ──
    // ── the layout altitude because it needs the                    ──
    // ── [`crate::layout::LayoutInvariants::exists`] filesystem       ──
    // ── oracle the pure typed-shape surface has no reference to —   ──
    // ── mirror of the peer M2 `:upgrade-from` per-instruction       ──
    // ── script-path existence probe that stayed at the layout       ──
    // ── altitude after the [`Caixa::validate_upgrade_from`] lift    ──
    // ── (d6801df) for the same reason.                              ──

    #[test]
    fn validate_behavior_folds_arm_matches_gate() {
        // Fail-before-pass-after per-arm equivalence pin on the
        // present-slot arm: a fixture whose `:behavior` carries an
        // absolute-path `:on-init` (`"/etc/passwd"`, which
        // [`crate::BehaviorSpec::validate`] rejects through
        // [`crate::BehaviorError::AbsolutePath`]) surfaces the same
        // [`crate::BehaviorError`] byte-equal through both the
        // compound gate [`Caixa::validate_behavior`] and the standalone
        // [`crate::BehaviorSpec::validate`] gate on the same
        // `BehaviorSpec` value. Pins the fold — a silent regression
        // that de-folded the present-slot arm would surface here as a
        // mismatch between the two dispatches. Sibling in shape to the
        // peer per-arm equivalence pins the
        // [`Caixa::validate_limits`] (baa4688),
        // [`Caixa::validate_upgrade_from`] (d6801df),
        // [`crate::MeshPolicy::validate`],
        // [`crate::AplicacaoSpec::validate_contratos`], and
        // [`crate::SupervisorSpec::validate_children`] compound gates
        // each carry on their axes.
        use crate::BehaviorSpec;
        use std::path::PathBuf;
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        let b = BehaviorSpec {
            on_init: Some(PathBuf::from("/etc/passwd")),
            ..Default::default()
        };
        c.behavior = Some(b.clone());
        let via_method = c.validate_behavior().unwrap_err();
        let via_standalone = b.validate().unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_behavior must surface the present-slot \
             arm's diagnostic byte-equal to the standalone \
             `BehaviorSpec::validate` on the same `BehaviorSpec` value"
        );
        assert!(
            matches!(via_method, crate::BehaviorError::AbsolutePath { .. }),
            "expected AbsolutePath on the absolute `:on-init` path, \
             got {via_method:?}"
        );
    }

    #[test]
    fn validate_behavior_accepts_none() {
        // Positive control on the absent-slot arm (the fold's identity
        // element): a caixa without any `:behavior` block (the
        // canonical "no callback declared — the runtime falls back to
        // the wasm-engine's default per arm" author shape
        // [`crate::BehaviorSpec::is_empty`]'s per-slot `None` cascade
        // reads, and the shape the [`Caixa::template`] scaffold emits
        // by construction) passes the compound gate cleanly,
        // regardless of any per-slot defect a subsequent `Some(_)`
        // binding would surface. Pins the identity element of the fold
        // on the absent-slot side, matching the peer
        // `validate_limits_accepts_none` (baa4688) and
        // `validate_upgrade_from_accepts_empty_upgrade_from` (d6801df)
        // positive-control postures on the sibling M2 slots.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        assert!(
            c.behavior().is_none(),
            "template caixa must carry an absent :behavior — got {:?}",
            c.behavior()
        );
        c.validate_behavior()
            .expect("absent :behavior must pass the compound gate cleanly");
    }

    #[test]
    fn validate_behavior_accepts_clean_fixture() {
        // Positive control on the present-slot arm: a caixa whose
        // `:behavior` is `Some(BehaviorSpec::default())` (all six
        // slots `None` — every slot absent under the outer `Some(_)`
        // binding, so every present-slot arm on
        // [`crate::BehaviorSpec::validate`] is vacuous) passes the
        // compound gate cleanly. A future tightening of any one arm
        // that surfaces a diagnostic on the all-`None` `BehaviorSpec`
        // would land here as a test failure first. Pins the
        // present-slot arm's accept-shape on the canonical
        // "declared-but-empty" author fixture the sibling
        // `empty_behavior_round_trip` peer already round-trips
        // (`caixa-core/src/behavior.rs` tests). Mirror of the peer
        // `validate_limits_accepts_clean_fixture` (baa4688)
        // positive-control posture on the sibling M2 `:limits` slot.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.behavior = Some(crate::BehaviorSpec::default());
        c.validate_behavior()
            .expect("Some(BehaviorSpec::default()) must pass the compound gate cleanly");
    }

    // ── Caixa::validate_deps — compound per-Caixa entry gate on the ──
    // ── dep-graph axis: folds the two standalone validators         ──
    // ── (per-entry + within-list duplicate walk that this method    ──
    // ── opened on, cross-slot self-edge via                         ──
    // ── `crate::dep::validate_no_self_dep`) onto one substrate      ──
    // ── primitive. Byte-for-byte equivalent to the pre-fold         ──
    // ── two-block cascade at                                        ──
    // ── `crate::layout::StandardLayout::verify` under the same      ──
    // ── canonical dispatch order (per-entry → self-edge).           ──

    #[test]
    fn validate_deps_folds_per_entry_arm_matches_gate() {
        // Fail-before-pass-after per-arm equivalence pin on the
        // per-entry + within-list duplicate axis: a fixture whose
        // `:deps` carries a per-entry-invalid `:versao` (`"^bad"`,
        // which [`crate::parse_requirement`] rejects) surfaces the
        // same [`crate::DepError`] through the compound gate
        // [`Caixa::validate_deps`] and the standalone per-entry walk
        // ([`Dep::validate`]) on the offending entry. Pins the
        // fold — a silent regression that de-folded the per-entry arm
        // would surface here as a mismatch between the two
        // dispatches. Sibling in shape to the peer
        // `validate_upgrade_from_folds_per_entry_arm_matches_gate`
        // per-arm equivalence pin (d6801df) on the M2
        // `:upgrade-from` compound gate's per-entry arm, extended
        // here onto the universal-axis `:deps` compound gate's
        // per-entry arm.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep::simple("d", "^bad")];
        let via_method = c.validate_deps().unwrap_err();
        let via_standalone = c.deps()[0].validate().unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_deps must surface the per-entry arm's \
             diagnostic byte-equal to the standalone \
             `Dep::validate` on the same offending entry",
        );
        assert!(
            matches!(
                via_method,
                DepError::VersaoInvalid { ref nome, .. } if nome == "d"
            ),
            "expected VersaoInvalid on the malformed :versao, got {via_method:?}",
        );
    }

    #[test]
    fn validate_deps_folds_self_edge_arm_matches_gate() {
        // Per-arm equivalence pin on the cross-slot self-edge axis:
        // a fixture whose `:deps` lists the caixa's own `:nome`
        // (a self-dep, which
        // [`crate::dep::validate_no_self_dep`] rejects as a
        // structurally-invalid one-node cycle in the lacre closure's
        // dep-graph) surfaces the same [`crate::DepError::DepIsSelf`]
        // through both the compound gate and the standalone
        // [`crate::dep::validate_no_self_dep`] gate keyed off the
        // same `(deps, deps_dev, nome)` triple. Pins the fold's
        // second arm — reaching this arm through the compound gate
        // requires the per-entry + within-list duplicate walk to
        // pass first, which itself pins one cross-arm ordering step.
        // Sibling in shape to the peer
        // `validate_upgrade_from_folds_versao_arm_matches_gate` /
        // `_folds_behavior_arm_matches_gate` cross-slot equivalence
        // pins (d6801df) on the M2 `:upgrade-from` compound gate's
        // cross-slot arms.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep::simple("demo", "^0.1")];
        let via_method = c.validate_deps().unwrap_err();
        let via_standalone =
            crate::dep::validate_no_self_dep(c.deps(), c.deps_dev(), c.nome()).unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_deps must surface the cross-slot \
             self-edge diagnostic byte-equal to the standalone \
             `crate::dep::validate_no_self_dep` on the same \
             (deps, deps_dev, nome) triple",
        );
        assert!(
            matches!(
                via_method,
                DepError::DepIsSelf { ref nome, list }
                    if nome == "demo" && list == crate::render::DEP_AUTHOR_KEY_DEPS
            ),
            "expected DepIsSelf carrying (nome=\"demo\", list=\":deps\"), got {via_method:?}",
        );
    }

    #[test]
    fn validate_deps_per_entry_arm_fires_before_self_edge_arm() {
        // Cross-arm ordering pin between the two arms of the fold:
        // a fixture carrying BOTH a per-entry-invalid `:versao`
        // (`"^bad"` — [`crate::parse_requirement`] rejects the
        // requirement grammar) on a non-self-dep entry AND a
        // would-be self-edge violation on a second entry (the
        // caixa's own `:nome` "demo") surfaces the per-entry
        // diagnostic first through the compound gate. Sanity
        // assertion: the second entry alone under the same parent
        // `:nome` trips the self-edge arm on its own via the
        // standalone [`crate::dep::validate_no_self_dep`], so the
        // per-entry-first surfacing is a real ordering property,
        // not a case where the self-edge arm silently accepts the
        // fixture. Pins the pre-fold layout wire-up's canonical
        // dispatch order (per-entry + within-list duplicate →
        // self-edge) as a property of the substrate primitive
        // rather than a convention of the layout call site. Sibling
        // in shape to
        // `validate_upgrade_from_per_entry_arm_fires_before_versao_arm`
        // (d6801df) on the M2 `:upgrade-from` compound gate's
        // per-arm ordering property.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![
            Dep::simple("orquestra", "^bad"),
            Dep::simple("demo", "^0.1"),
        ];
        let err = c.validate_deps().unwrap_err();
        assert!(
            matches!(
                err,
                DepError::VersaoInvalid { ref nome, .. } if nome == "orquestra"
            ),
            "per-entry arm must fire before self-edge arm — expected \
             VersaoInvalid on \"orquestra\", got {err:?}",
        );
        // Sanity: the self-referential entry alone under the same
        // parent `:nome` trips the self-edge arm on its own — proves
        // the per-entry-first surfacing above is a real ordering
        // property, not a case where the self-edge arm silently
        // accepts the fixture.
        let sanity = crate::dep::validate_no_self_dep(&[Dep::simple("demo", "^0.1")], &[], "demo")
            .unwrap_err();
        assert!(
            matches!(sanity, DepError::DepIsSelf { ref nome, .. } if nome == "demo"),
            "sanity: the self-referential entry alone must trip the \
             self-edge arm — got {sanity:?}",
        );
    }

    #[test]
    fn validate_deps_accepts_clean_fixture() {
        // Positive control: a well-formed dep-graph (one `:deps`
        // entry naming a non-self DNS-1123 nome + Cargo-shaped
        // requirement, one `:deps-dev` entry on a distinct non-self
        // nome) passes the compound gate cleanly. A future
        // tightening of either arm's accepted set surfaces here as
        // a test failure first. Mirrors the peer
        // `validate_upgrade_from_accepts_clean_fixture` positive-
        // control posture on the sibling per-Caixa compound gate.
        let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        c.deps = vec![Dep::simple("caixa-teia", "^0.1")];
        c.deps_dev = vec![Dep::simple("caixa-lint", "^0.2")];
        c.validate_deps()
            .expect("clean fixture must pass the compound `:deps` gate");
    }

    #[test]
    fn validate_deps_accepts_empty_deps_lists() {
        // Positive control on the empty-list arm: a caixa without
        // any `:deps` or `:deps-dev` entries (the default
        // `Vec::new()` `#[serde(default)]` folds an omitted slot
        // onto) passes the compound gate cleanly regardless of
        // `:nome` — both the per-entry walk and the self-edge walk
        // are vacuous on the empty entry list. Pins the identity
        // element of the fold on the empty-slot side, peer with the
        // `validate_upgrade_from_accepts_empty_upgrade_from` empty-
        // arm positive control (d6801df) on the sibling
        // `:upgrade-from` compound gate.
        let c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
        assert!(
            c.deps().is_empty(),
            "template caixa must carry an empty :deps — got {:?}",
            c.deps(),
        );
        assert!(
            c.deps_dev().is_empty(),
            "template caixa must carry an empty :deps-dev — got {:?}",
            c.deps_dev(),
        );
        c.validate_deps()
            .expect("empty :deps / :deps-dev must pass the compound gate cleanly");
    }

    // ── Caixa::validate_aplicacao_shape — compound per-Caixa gate ────────

    /// Build a minimal well-formed Aplicacao fixture on top of the
    /// canonical template. Every arm of the compound gate then patches
    /// exactly one axis away from clean so its per-arm diagnostic
    /// surfaces without collateral noise from a peer slot.
    fn aplicacao_fixture(nome: &str) -> Caixa {
        use crate::aplicacao::{Membro, Placement, PlacementStrategy};
        let mut c = Caixa::from_lisp(&Caixa::template(nome)).unwrap();
        c.kind = CaixaKind::Aplicacao;
        c.bibliotecas = vec![];
        c.membros = vec![
            Membro {
                caixa: "checkout".into(),
                versao: "^0.1".into(),
            },
            Membro {
                caixa: "cart".into(),
                versao: "^0.1".into(),
            },
        ];
        // `:placement` defaults to `Replicated` with an empty
        // `:clusters` list which
        // [`crate::AplicacaoSpec::validate_placement`] refuses; every
        // per-strategy variant needs at least one named cluster (per
        // MESH-COMPOSITION §II.1). Pin a single-cluster `SingleNode`
        // placement so the typed-shape cascade passes cleanly and the
        // per-arm fixtures below can each patch exactly one axis.
        c.placement = Some(Placement {
            estrategia: PlacementStrategy::SingleNode,
            clusters: vec!["rio".into()],
            shard_key: None,
            affinity: None,
        });
        c
    }

    #[test]
    fn validate_aplicacao_shape_folds_view_arm_matches_gate() {
        // Fail-before-pass-after per-arm equivalence pin on the
        // typed-shape cascade arm: a fixture whose typed
        // [`crate::AplicacaoSpec`] view fails
        // [`crate::AplicacaoSpec::validate`] (here — empty `:membros`,
        // which [`crate::AplicacaoSpec::validate_membros`] rejects as
        // [`crate::AplicacaoError::NoMembros`] at the first per-slot
        // gate) surfaces the same [`crate::AplicacaoError`] diagnostic
        // through both the compound gate
        // [`Caixa::validate_aplicacao_shape`] and the standalone
        // [`crate::AplicacaoSpec::validate`] on the same folded view.
        // Pins the fold — a silent regression that de-folded the
        // typed-shape arm would surface here as a mismatch between the
        // two dispatches. Sibling in shape to the peer
        // `validate_deps_folds_per_entry_arm_matches_gate` (b5dd55e) /
        // `validate_upgrade_from_folds_per_entry_arm_matches_gate`
        // (d6801df) per-arm equivalence pins on the sibling per-slot
        // compound gates.
        let mut c = aplicacao_fixture("demo");
        c.membros = vec![];
        let via_method = c.validate_aplicacao_shape().unwrap_err();
        let via_standalone = c.aplicacao_view().unwrap().validate().unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_aplicacao_shape must surface the typed-\
             shape arm's diagnostic byte-equal to the standalone \
             `AplicacaoSpec::validate` on the same folded view",
        );
        assert!(
            matches!(via_method, crate::AplicacaoError::NoMembros),
            "expected NoMembros on the empty :membros, got {via_method:?}",
        );
    }

    #[test]
    fn validate_aplicacao_shape_folds_self_membership_arm_matches_gate() {
        // Per-arm equivalence pin on the cross-slot self-edge axis: a
        // fixture whose `:membros` names the Aplicacao's own `:nome`
        // (which [`crate::aplicacao::validate_no_self_membership`]
        // rejects as [`crate::AplicacaoError::MembroIsSelfAplicacao`],
        // a one-node lacre-closure recursion in the Aplicacao's
        // mesh-graph) surfaces the same
        // [`crate::AplicacaoError::MembroIsSelfAplicacao`] through both
        // the compound gate and the standalone
        // [`crate::aplicacao::validate_no_self_membership`] keyed off
        // the same `(membros, nome)` pair. Pins the fold's second arm
        // — reaching this arm through the compound gate requires the
        // typed-shape cascade to pass first, which itself pins one
        // cross-arm ordering step. Sibling in shape to the peer
        // `validate_deps_folds_self_edge_arm_matches_gate` (b5dd55e)
        // cross-slot equivalence pin on the sibling per-slot compound
        // gate.
        use crate::aplicacao::Membro;
        let mut c = aplicacao_fixture("demo");
        c.membros = vec![Membro {
            caixa: "demo".into(),
            versao: "^0.1".into(),
        }];
        let via_method = c.validate_aplicacao_shape().unwrap_err();
        let via_standalone =
            crate::aplicacao::validate_no_self_membership(c.membros(), c.nome()).unwrap_err();
        assert_eq!(
            via_method, via_standalone,
            "Caixa::validate_aplicacao_shape must surface the cross-\
             slot self-edge diagnostic byte-equal to the standalone \
             `aplicacao::validate_no_self_membership` on the same \
             (membros, nome) pair",
        );
        assert!(
            matches!(
                via_method,
                crate::AplicacaoError::MembroIsSelfAplicacao { ref caixa } if caixa == "demo"
            ),
            "expected MembroIsSelfAplicacao carrying (caixa=\"demo\"), \
             got {via_method:?}",
        );
    }

    #[test]
    fn validate_aplicacao_shape_view_arm_fires_before_self_membership_arm() {
        // Cross-arm ordering pin between the two arms of the fold: a
        // fixture carrying BOTH a typed-shape violation (a `:contratos`
        // edge whose `:para` is not a declared member — rejected by
        // [`crate::AplicacaoSpec::validate_contratos`] as
        // [`crate::AplicacaoError::ContratoMemberMissing`]) AND a
        // would-be self-edge violation (a `:membros` entry naming the
        // caixa's own `:nome`) surfaces the typed-shape diagnostic
        // first through the compound gate. Sanity assertion: the
        // self-referential `:membros` entry alone under the same
        // parent `:nome` trips the self-edge arm on its own via the
        // standalone [`crate::aplicacao::validate_no_self_membership`],
        // so the typed-shape-first surfacing is a real ordering
        // property, not a case where the self-edge arm silently
        // accepts the fixture. Pins the pre-fold layout wire-up's
        // canonical dispatch order (typed-shape cascade → cross-slot
        // self-edge) as a property of the substrate primitive rather
        // than a convention of the layout call site. Sibling in shape
        // to `validate_deps_per_entry_arm_fires_before_self_edge_arm`
        // (b5dd55e) on the sibling per-slot compound gate's per-arm
        // ordering property.
        use crate::aplicacao::{Membro, WitContract};
        let mut c = aplicacao_fixture("demo");
        c.membros = vec![Membro {
            caixa: "demo".into(),
            versao: "^0.1".into(),
        }];
        c.contratos = vec![WitContract {
            de: "demo".into(),
            para: "orphan".into(),
            wit: "wasi:http/proxy".into(),
            endpoint: Some("/x".into()),
            subject: None,
            slot: None,
        }];
        let err = c.validate_aplicacao_shape().unwrap_err();
        assert!(
            matches!(
                err,
                crate::AplicacaoError::ContratoMemberMissing { ref caixa }
                    if caixa == "orphan"
            ),
            "typed-shape arm must fire before self-edge arm — expected \
             ContratoMemberMissing on \"orphan\", got {err:?}",
        );
        // Sanity: the self-referential `:membros` entry alone under
        // the same parent `:nome` trips the self-edge arm on its own
        // — proves the typed-shape-first surfacing above is a real
        // ordering property, not a case where the self-edge arm
        // silently accepts the fixture.
        let sanity = crate::aplicacao::validate_no_self_membership(
            &[Membro {
                caixa: "demo".into(),
                versao: "^0.1".into(),
            }],
            "demo",
        )
        .unwrap_err();
        assert!(
            matches!(
                sanity,
                crate::AplicacaoError::MembroIsSelfAplicacao { ref caixa }
                    if caixa == "demo"
            ),
            "sanity: the self-referential :membros entry alone must \
             trip the self-edge arm — got {sanity:?}",
        );
    }

    #[test]
    fn validate_aplicacao_shape_accepts_non_aplicacao_kind() {
        // Positive control on the identity-element arm: every non-
        // Aplicacao kind passes the compound gate trivially — the
        // paired [`Caixa::aplicacao_view`] accessor returns `None`
        // off the Aplicacao arm (by construction, keyed on
        // `caixa.kind().is_aplicacao()`), so the fold short-circuits
        // to `Ok(())` without touching the mesh slots. Pins the
        // identity element on every non-Aplicacao kind — a future
        // refactor that made the mesh-slot cascade fire on the wrong
        // kind (say, on a `Servico` whose mesh slots happen to be
        // populated in a mis-authored manifest, which the peer
        // [`crate::LayoutError::MeshSlotsOnNonAplicacao`] kind-
        // coherence gate would refuse upstream anyway) surfaces here
        // as a test failure first. Peer with the
        // `validate_limits_accepts_none` / `validate_behavior_accepts_none`
        // identity-element pins on the sibling M2 `Option`-shaped
        // per-Caixa compound gates.
        for kind in [
            CaixaKind::Biblioteca,
            CaixaKind::Binario,
            CaixaKind::Servico,
            CaixaKind::Supervisor,
            CaixaKind::Acao,
        ] {
            let mut c = Caixa::from_lisp(&Caixa::template("demo")).unwrap();
            c.kind = kind;
            assert!(
                c.aplicacao_view().is_none(),
                "aplicacao_view must return None off the Aplicacao arm \
                 for kind {kind:?}",
            );
            c.validate_aplicacao_shape().expect(
                "non-Aplicacao kinds must pass the compound gate as the fold's identity element",
            );
        }
    }

    #[test]
    fn validate_aplicacao_shape_accepts_clean_fixture() {
        // Positive control: a well-formed Aplicacao (two DNS-1123
        // members with valid semver constraints, no `:contratos` /
        // `:entrada` / `:placement` / `:politicas` set — every
        // per-slot gate accepts the vacuous / omitted arm) passes the
        // compound gate cleanly. A future tightening of either arm's
        // accepted set surfaces here as a test failure first. Mirrors
        // the peer `validate_deps_accepts_clean_fixture` (b5dd55e) /
        // `validate_upgrade_from_accepts_clean_fixture` (d6801df)
        // positive-control postures on the sibling per-Caixa
        // compound gates.
        let c = aplicacao_fixture("demo");
        c.validate_aplicacao_shape()
            .expect("clean Aplicacao fixture must pass the compound gate");
    }
}