khive_runtime/

engine_config.rs

//! TOML-based embedding engine configuration for khive.
//!
//! Loads `.khive/config.toml` (or `--config` / `KHIVE_CONFIG`) and exposes an
//! `[[engines]]` array for arbitrary-N embedding engine registration. Falls back
//! to `KHIVE_EMBEDDING_MODEL` env vars when no config file is present.

use std::collections::{BTreeMap, BTreeSet};
use std::path::{Path, PathBuf};

use khive_types::{namespace::Namespace, SubstrateKind};
use serde::{Deserialize, Serialize};
use thiserror::Error;

use crate::{
    config::{parse_embedding_model_alias, BackendId},
    presentation::OutputFormat,
};

// ---- Error type ----

/// Errors produced while loading or validating a `KhiveConfig`.
#[derive(Debug, Error)]
pub enum ConfigError {
    #[error("mount configuration: {reason}")]
    InvalidMountConfig { reason: String },

    #[error("config file I/O: {0}")]
    Io(#[from] std::io::Error),

    #[error("config TOML parse error in {path}: {source}")]
    Parse {
        path: PathBuf,
        #[source]
        source: toml::de::Error,
    },

    #[error("exactly one engine must be marked `default = true`; found {found}")]
    DefaultCount { found: usize },

    #[error("duplicate engine name: {name:?}")]
    DuplicateName { name: String },

    #[error(
        "engine {name:?}: model {model:?} is not a recognized lattice_embed::EmbeddingModel name"
    )]
    UnknownModel { name: String, model: String },

    #[error("engine {name:?}: fusion_weight must be > 0, got {value}")]
    InvalidFusionWeight { name: String, value: f64 },

    #[error("actor.id {id:?} is not a valid namespace: {reason}")]
    InvalidActorId { id: String, reason: String },

    #[error("[actor].mailbox_readers: {reason}")]
    InvalidMailboxReaders { reason: String },

    #[error("[gate].granted_actors entry {id:?} is not a valid actor id: {reason}")]
    InvalidGrantedActorId { id: String, reason: String },
    #[error("[gate].deny_writes_for is invalid: {reason}")]
    InvalidWriteDenyPatterns { reason: String },

    #[error("duplicate backend name: {name:?}")]
    DuplicateBackendName { name: String },

    #[error("invalid backend name {name:?}: {reason}")]
    InvalidBackendName { name: String, reason: String },

    #[error("backend {name:?}: `served_kinds` must not be empty when declared")]
    EmptyBackendServedKinds { name: String },

    #[error(
        "backend configuration leaves searchable substrate kinds {kinds:?} unserved; \
         defined backends: {defined}"
    )]
    MissingBackendSearchKinds {
        kinds: Vec<SubstrateKind>,
        defined: String,
    },

    #[error(
        "[packs.{pack}].backend = {backend:?} references an unknown backend; \
         defined backends: {defined}"
    )]
    UnknownPackBackend {
        pack: String,
        backend: String,
        defined: String,
    },

    #[error(
        "[[backends]] entry {name:?}: field `{field}` is not yet supported; \
         remove it from the config or wait for a future release that implements it"
    )]
    UnsupportedBackendField { name: String, field: &'static str },

    #[error(
        "top-level `db = {value:?}` is not a supported config-file key; \
         use `--db` / `KHIVE_DB` to select a single-file database, or \
         `[[backends]].path` to declare storage backend topology"
    )]
    UnsupportedTopLevelDb { value: String },

    #[error("[[git_write.allowed]] entry {repo:?}: {reason}")]
    InvalidGitWriteEntry { repo: String, reason: String },

    #[error("[git_write] {key}: {reason}")]
    InvalidGitWriteConfig { key: String, reason: String },

    #[error("[exec] {key}: {reason}")]
    InvalidExecConfig { key: String, reason: String },

    #[error("{entry}: {reason}")]
    InvalidTelemetryConfig { entry: String, reason: String },

    #[error("[web] {key}: {reason}")]
    InvalidWebConfig { key: String, reason: String },

    #[error(
        "[runtime] blob_hydration_bytes must be between {min} and {max} bytes inclusive; got {value}"
    )]
    InvalidBlobHydrationBytes { value: u64, min: u64, max: u64 },

    #[error("the explicitly selected config file does not exist: {path}")]
    ExplicitConfigMissing { path: PathBuf },

    /// Retained for source compatibility with callers that matched the
    /// fail-loud behavior of older builds. Supported `[gate]` sections no
    /// longer produce this error.
    #[error("[gate] configuration is not supported by this build")]
    UnsupportedGateSection,

    #[error(
        "[display] timezone {timezone:?} is not a recognized IANA zone name (e.g. \"America/New_York\", \"UTC\")"
    )]
    InvalidDisplayTimezone { timezone: String },

    /// Loader-context wrapper attaching the config file the error came from.
    ///
    /// Added as a wrapping variant, rather than reshaping the existing
    /// variants, so every existing constructor, field access, and the
    /// `From<std::io::Error>` conversion survive unchanged. The enum is not
    /// `#[non_exhaustive]`, so an exhaustive `match` on `ConfigError` must
    /// still add an arm for this variant — either matching `InFile` and
    /// recursing into `source`, or a wildcard. `Parse` already carries its
    /// path and is never wrapped.
    #[error("{source} (config file: {})", path.display())]
    InFile {
        path: PathBuf,
        #[source]
        source: Box<ConfigError>,
    },
}

impl ConfigError {
    /// Attach the loading config file's path unless the error already names
    /// one (`Parse`, `ExplicitConfigMissing`) or is already wrapped.
    fn in_file(self, path: &Path) -> Self {
        match self {
            already @ (ConfigError::Parse { .. }
            | ConfigError::ExplicitConfigMissing { .. }
            | ConfigError::InFile { .. }) => already,
            other => ConfigError::InFile {
                path: path.to_path_buf(),
                source: Box::new(other),
            },
        }
    }
}

// ---- Config structs ----

/// Configuration for a single embedding engine.
#[derive(Debug, Clone, Deserialize)]
pub struct EngineConfig {
    /// Logical name used to reference this engine in logs and fusion.
    pub name: String,

    /// Lattice-embed model name (e.g. `"all-minilm-l6-v2"`).
    ///
    /// Must be parseable via `lattice_embed::EmbeddingModel::from_str` (or a
    /// recognised short alias handled by `parse_embedding_model_alias`).
    pub model: String,

    /// When `true`, this engine's model becomes the primary (`RuntimeConfig::embedding_model`).
    /// Exactly one engine in the list must set this. If absent, defaults to `false`.
    #[serde(default)]
    pub default: bool,

    /// RRF fusion weight for weighted multi-engine fusion.
    ///
    /// Only meaningful when multiple engines are loaded. Must be `> 0` when
    /// present. `None` means the engine participates in fusion with equal weight
    /// to other engines that also lack a `fusion_weight`.
    ///
    /// For RRF: `fusion_weight` provides per-engine relative importance during
    /// weighted RRF; it does NOT apply to rank-based unweighted RRF (the weights
    /// are injected into `FusionStrategy::Weighted` only).
    pub fusion_weight: Option<f64>,

    /// Expected output dimensionality (optional sanity check).
    ///
    /// Not used at runtime — dimensions are authoritative from
    /// `EmbeddingModel::dimensions()`. Present so operators can document the
    /// expected shape alongside the model name.
    pub dims: Option<u32>,
}

/// Actor configuration — the default namespace / identity for this khive instance.
///
/// Corresponds to the `[actor]` TOML section. `id` is used as the
/// `default_namespace` for gate/attribution policy input. OSS dispatch pins
/// writes to the shared `local` namespace regardless of this value (ADR-007
/// Rev 4 Rule 0); cloud deployments derive the namespace from an authenticated
/// `NamespaceToken` instead.
///
/// ```toml
/// [actor]
/// id = "lambda:leo"                          # attribution identity (required)
/// display_name = "example actor"   # human label (optional)
/// visible_namespaces = ["lambda:khive", "local"]  # widens default read scope (ADR-007 Rev 4 Rule 3b)
/// ```
///
/// `visible_namespaces` is consumed by OSS dispatch to widen the DEFAULT
/// multi-record read scope to `['local'] ∪ visible_namespaces` (ADR-007 Rev 4
/// Rule 3b). Writes remain pinned to `'local'`. An explicit `namespace=` request
/// param is a precise single-namespace escape and is not widened. A cloud gate
/// may also consult this list as policy input at its own layer.
///
/// The table is closed. Both keys above are authorization input, so a misspelled
/// key fails startup instead of silently applying its default, and a `[gate]` key
/// written here is reported rather than discarded.
#[derive(Debug, Clone, Deserialize, Default)]
#[serde(deny_unknown_fields)]
pub struct ActorConfig {
    /// Namespace identifier used as the default actor for all operations.
    ///
    /// Must be a valid `Namespace` string (e.g. `"local"`, `"lambda:khive"`).
    /// Defaults to `"local"` when absent — backward-compatible with pre-actor
    /// deployments.
    #[serde(default)]
    pub id: Option<String>,

    /// Optional human-readable label for this actor. Not used by the runtime;
    /// surfaced in introspection and log output only.
    #[serde(default)]
    pub display_name: Option<String>,

    /// Exact actor labels permitted to inspect this explicit actor's mailbox.
    ///
    /// A nonempty list requires an explicit non-local `id`. Labels are bounded
    /// to 255 bytes, nonblank, and contain no control characters; `local` is
    /// forbidden. At most 256 entries are accepted before deduplication. This
    /// is trusted serving-host policy, never inferred from environment identity
    /// or supplied by a request. Changes take effect in a new server epoch.
    #[serde(default)]
    pub mailbox_readers: Vec<String>,

    /// Additional namespaces that widen the DEFAULT multi-record read scope
    /// to `['local'] ∪ visible_namespaces` (ADR-007 Rev 4 Rule 3b). Each string
    /// must be a valid `Namespace`. Writes remain pinned to `'local'`. An
    /// explicit `namespace=` request param is a precise escape and is not widened
    /// by this list. A cloud gate may also consult it as policy input.
    #[serde(default)]
    pub visible_namespaces: Option<Vec<String>>,

    /// Namespaces this actor's comm.send/reply may deliver messages INTO
    /// (outbound, sender-side). Empty by default — cross-namespace delivery
    /// denied unless explicitly declared. The comm handler uses an ordinary
    /// `NamespaceToken` (minted via `with_namespace`) in an append-only manner;
    /// the token itself is NOT type-enforced write-only. The recipient-side
    /// `allowed_inbound_namespaces` (bilateral mutual opt-in) is reserved for
    /// a future cloud-path authorization ADR (not yet written).
    ///
    /// Each entry must be a valid `Namespace` string; validated at
    /// config-load time. An empty list preserves the prior deny-all behavior
    /// for any actor that does not add this field.
    #[serde(default)]
    pub allowed_outbound_namespaces: Vec<String>,
}

/// Built-in caller-enrollment policy configured by `[gate]`.
///
/// The table is intentionally closed: misspelled or future keys fail startup
/// instead of being silently ignored at an authorization boundary. Presence
/// installs [`khive_gate::CallerEnrollmentGate`]; absence preserves the gate
/// already supplied in the base [`crate::RuntimeConfig`].
#[derive(Debug, Clone, Deserialize, Default, PartialEq, Eq)]
#[serde(deny_unknown_fields)]
pub struct GateSectionConfig {
    /// Exact resolved actor ids permitted to dispatch requests.
    #[serde(default)]
    pub granted_actors: Vec<String>,

    /// Whether the implicit anonymous/local caller is admitted.
    #[serde(default)]
    pub grant_unattributed: bool,

    /// Whole actor-ID patterns denying all but explicitly reviewed reads.
    /// Case-sensitive; only `*` is a wildcard. Does not enroll a caller.
    #[serde(default)]
    pub deny_writes_for: Vec<String>,
}

// ---- Per-pack backend config (ADR-028) ----

/// Storage backend kind.
#[derive(Debug, Clone, Deserialize, Default, PartialEq, Eq)]
#[serde(rename_all = "lowercase")]
pub enum BackendKind {
    /// SQLite file-backed database (default).
    #[default]
    Sqlite,
    /// In-memory database — for testing only; state is lost on restart.
    Memory,
}

/// Configuration for a named storage backend.
///
/// Corresponds to a `[[backends]]` entry in `khive.toml`.
/// When no `[[backends]]` section is present, a single implicit `main` backend
/// is synthesised from the existing `--db` / `KHIVE_DB` / default-path resolution.
/// All packs fall back to `main` when their name is absent from `[packs]`.
/// `cache_mb` and `journal_mode` are parsed but rejected during validation
/// because per-backend tuning is not implemented.
///
/// ```toml
/// [[backends]]
/// name = "main"
/// kind = "sqlite"
/// path = "~/.khive/khive.db"
/// read_only = false
/// ```
#[derive(Debug, Clone, Deserialize)]
pub struct BackendConfig {
    /// Unique backend name. Referenced by `[packs.<name>].backend`.
    pub name: String,
    /// Storage backend kind. Defaults to `sqlite`.
    #[serde(default)]
    pub kind: BackendKind,
    /// Filesystem path for `sqlite` kind. Tilde is expanded to `$HOME`.
    /// `None` for `memory` kind (path is ignored when present).
    pub path: Option<std::path::PathBuf>,
    /// SQLite page-cache size in MiB. Parsed but rejected as unsupported.
    pub cache_mb: Option<u32>,
    /// SQLite journal mode (e.g. `"wal"`). Parsed but rejected as unsupported.
    pub journal_mode: Option<String>,
    /// Substrate kinds this backend serves.
    ///
    /// Omission preserves conservative fan-out to this backend. An explicit
    /// declaration is closed over [`SubstrateKind`] and must not be empty.
    /// The backend set must cover both `note` and `entity` search.
    #[serde(default)]
    pub served_kinds: Option<BTreeSet<SubstrateKind>>,
    /// Open the backend read-only. Defaults to `false`.
    #[serde(default)]
    pub read_only: bool,
}

/// Per-pack backend assignment.
///
/// Corresponds to a `[packs.<pack-name>]` entry in `khive.toml`.
/// Packs whose name is absent from `[packs]` fall back to the `main` backend.
///
/// ```toml
/// [packs.knowledge]
/// backend = "knowledge"
///
/// [packs.comm]
/// backend = "comm"
/// no_embed = true
/// ```
#[derive(Debug, Clone, Deserialize)]
pub struct PackConfig {
    /// Backend name this pack is assigned to. Must match a `[[backends]].name`,
    /// or `main` when no backends are declared.
    pub backend: String,
    /// Disable vector embedding for this pack's runtime: rows it writes get
    /// FTS and metadata only, no `vec_*` rows and no ANN participation. The
    /// opt-out covers pack-owned writes on the pack's own backend; it does
    /// NOT cover `core()`-routed concept writes, which embed with the MAIN
    /// runtime's embedders (the boot path wires them in via
    /// `with_core_embedders_from`) so the shared graph stays uniformly
    /// searchable. Fits packs whose own rows are structural rather than
    /// retrieval targets (e.g. comm). Effective in multi-backend boot, where
    /// each pack gets its own runtime. Defaults to `false`.
    #[serde(default)]
    pub no_embed: bool,
}

// ---- Blob store config (ADR-111 Amendment 2) ----

/// `[storage.blob]` section: a closed `backend = "fs" | "s3"` selector.
///
/// Internally tagged on `backend` with `deny_unknown_fields`: an unknown
/// top-level key, a field that belongs to the other backend variant (e.g.
/// `bucket` under `backend = "fs"`), or an S3 credential field (never
/// accepted in TOML -- ADR-111 Amendment 2 reads credentials from the
/// process environment only) are all rejected at config-load time by the
/// same mechanism, since each variant only declares its own fields.
///
/// ```toml
/// [storage.blob]
/// backend = "fs"
/// root = "/var/lib/khive/blobs"
/// floor_bytes = 100000000000
/// ```
///
/// ```toml
/// [storage.blob]
/// backend = "s3"
/// bucket = "khive-blobs"
/// region = "us-east-1"
/// endpoint = "https://objects.example.invalid"
/// prefix = "blobs"
/// ```
#[derive(Debug, Clone, Deserialize)]
#[serde(tag = "backend", rename_all = "lowercase", deny_unknown_fields)]
pub enum BlobConfig {
    /// Filesystem-backed blob storage (`FsBlobStore`). Root resolution is
    /// unchanged from khive#292: `KHIVE_BLOB_ROOT` env var, then this
    /// `root`, then `<db_dir>/blobs`.
    Fs {
        #[serde(default)]
        root: Option<String>,
        #[serde(default)]
        floor_bytes: Option<u64>,
    },
    /// S3-compatible blob storage (`S3BlobStore`). `KHIVE_BLOB_ROOT` has no
    /// effect for this backend. Credentials always come from
    /// `AWS_ACCESS_KEY_ID`/`AWS_SECRET_ACCESS_KEY`/`AWS_SESSION_TOKEN` in the
    /// process environment, never from this section.
    S3 {
        bucket: String,
        region: String,
        #[serde(default)]
        endpoint: Option<String>,
        #[serde(default)]
        prefix: Option<String>,
        #[serde(default)]
        allow_http: Option<bool>,
    },
}

/// `[storage]` section in `khive.toml`. Holds storage-layer config not
/// already covered by `[[backends]]` (ADR-028).
#[derive(Debug, Clone, Deserialize, Default)]
pub struct StorageSectionConfig {
    /// Blob store backend selector (ADR-111 Amendment 2). Absent means
    /// `FsBlobStore` at the existing root-resolution precedence, unchanged
    /// from khive#292 -- existing configurations keep behaving exactly as
    /// they did before this section existed.
    #[serde(default)]
    pub blob: Option<BlobConfig>,
}

/// `[brain]` read policy resolved by the serving process.
#[derive(Debug, Clone, Deserialize, Serialize, Default)]
#[serde(deny_unknown_fields)]
pub struct BrainSectionConfig {
    /// Actor ids permitted to request fleet-wide `brain.event_counts` reads.
    #[serde(default)]
    pub fleet_readers: Vec<String>,
}

// ---- git-write policy (ADR-108 Amendment) ----

/// One `[[git_write.allowed]]` entry: a repo this operator has declared
/// trusted for khive-mediated git writes, plus the branches on it a write
/// verb (`git.commit`/`git.branch`/`git.update_ref`/`git.push`) may target.
///
/// ```toml
/// [[git_write.allowed]]
/// repo = "/abs/path/repo"
/// branches = ["feat/*", "fix/*"]
/// ```
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct GitWriteEntryConfig {
    /// Absolute local path to the allowlisted repository.
    pub repo: String,
    /// Non-empty list of exact branch names or single-`*`-wildcard globs
    /// this repo entry permits writes against.
    pub branches: Vec<String>,
}

/// `[git_write]` section — the closed repo/branch allowlist consulted by
/// `khive-pack-git`'s write verbs at the handler level (ADR-108 Amendment),
/// independent of Gate policy. Absent or empty `allowed` is the fail-closed
/// default: the write verbs report themselves unavailable rather than
/// defaulting open.
///
/// ```toml
/// [[git_write.allowed]]
/// repo = "/abs/path/repo"
/// branches = ["feat/*", "fix/*"]
/// ```
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct GitWriteSectionConfig {
    /// Absolute git executable override; absent preserves PATH resolution.
    #[serde(default)]
    pub program: Option<PathBuf>,
    #[serde(default)]
    pub allowed: Vec<GitWriteEntryConfig>,
    #[serde(default)]
    pub actors: BTreeMap<String, GitWriteActorConfig>,
    #[serde(default)]
    pub repositories: BTreeMap<String, GitWriteRepositoryConfig>,
    #[serde(default = "default_git_credential_resolver")]
    pub credential_resolver: Vec<String>,
    #[serde(default)]
    pub contract_faults: bool,
    #[serde(default)]
    pub fault: Option<String>,
}

#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub struct GitWriteRepositoryConfig {
    /// HTTPS platform remote, or an absolute path / file:/// URL with an empty slug.
    pub remote: String,
    /// owner/name for HTTPS; empty explicitly opts into credential-free local pushes.
    pub slug: String,
    pub visibility: String,
    /// Merge dispatch refusals for this repository (ADR-182 Amendment 7):
    /// `opener` refuses a `git.pr_merge` dispatched by the account or actor
    /// that opened the pull request; `last_pusher` refuses one dispatched by
    /// the login on the newest push receipt for `expected_head`. Empty (the
    /// default) refuses neither.
    #[serde(default)]
    pub merge_refusals: Vec<String>,
}

impl GitWriteRepositoryConfig {
    pub const MERGE_REFUSALS: [&'static str; 2] = ["opener", "last_pusher"];

    /// Whether this repository row lists the named merge refusal.
    pub fn refuses_merge_by(&self, entry: &str) -> bool {
        self.merge_refusals.iter().any(|listed| listed == entry)
    }
}

#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq)]
#[serde(deny_unknown_fields)]
pub struct GitWriteActorConfig {
    pub name: String,
    pub email: String,
    pub credential_ref: String,
    pub platform_identity: String,
}

fn default_git_credential_resolver() -> Vec<String> {
    [
        "/usr/bin/security",
        "find-generic-password",
        "-w",
        "-s",
        "{ref}",
    ]
    .into_iter()
    .map(str::to_string)
    .collect()
}

impl Default for GitWriteSectionConfig {
    fn default() -> Self {
        Self {
            program: None,
            allowed: Vec::new(),
            actors: BTreeMap::new(),
            repositories: BTreeMap::new(),
            credential_resolver: default_git_credential_resolver(),
            contract_faults: false,
            fault: None,
        }
    }
}

impl GitWriteSectionConfig {
    pub fn git_program(&self) -> &Path {
        self.program.as_deref().unwrap_or_else(|| Path::new("git"))
    }

    pub fn validate_dev_loop(&self) -> Result<(), ConfigError> {
        let invalid = |key: &str, reason: &str| ConfigError::InvalidGitWriteConfig {
            key: key.to_string(),
            reason: reason.to_string(),
        };
        if let Some(program) = &self.program {
            if !program.is_absolute() {
                return Err(invalid("git_write.program", "must be absolute"));
            }
            let metadata = std::fs::metadata(program).map_err(|error| {
                if error.kind() == std::io::ErrorKind::NotFound {
                    invalid("git_write.program", "does not exist")
                } else {
                    invalid("git_write.program", &format!("is not executable: {error}"))
                }
            })?;
            #[cfg(unix)]
            let executable = {
                use std::os::unix::fs::PermissionsExt;
                metadata.permissions().mode() & 0o111 != 0
            };
            #[cfg(windows)]
            let executable = program
                .extension()
                .and_then(|extension| extension.to_str())
                .is_some_and(|extension| {
                    extension.eq_ignore_ascii_case("exe") || extension.eq_ignore_ascii_case("com")
                });
            #[cfg(not(any(unix, windows)))]
            let executable = false;
            if !metadata.is_file() || !executable {
                return Err(invalid("git_write.program", "is not executable"));
            }
        }
        if self.contract_faults && !cfg!(feature = "contract-faults") {
            tracing::error!(
                target: "khive.boot",
                "[git_write] contract_faults requires the test-only contract-faults build feature"
            );
            return Err(invalid(
                "contract_faults",
                "requires the test-only contract-faults build feature",
            ));
        }
        if let Some(fault) = &self.fault {
            if !self.contract_faults {
                return Err(invalid("fault", "requires contract_faults = true"));
            }
            let valid = fault.split_once(':').is_some_and(|(verb, point)| {
                matches!(verb, "git.push" | "git.pr_merge")
                    && matches!(
                        point,
                        "reply-lost-after-effect" | "audit-fails-after-effect"
                    )
            });
            if !valid {
                return Err(invalid("fault", "unsupported contract fault selector"));
            }
        }
        for (path, repository) in &self.repositories {
            let key = format!("repositories.{path}.merge_refusals");
            let mut seen: Vec<&str> = Vec::new();
            for entry in &repository.merge_refusals {
                if !GitWriteRepositoryConfig::MERGE_REFUSALS.contains(&entry.as_str()) {
                    return Err(invalid(&key, "entries must be opener or last_pusher"));
                }
                if seen.contains(&entry.as_str()) {
                    return Err(invalid(&key, "entries must not repeat"));
                }
                seen.push(entry);
            }
        }
        // The default keychain program is Unix-only. Legacy configurations with
        // no actor mappings cannot invoke it, so they remain loadable elsewhere.
        if !cfg!(unix)
            && self.actors.is_empty()
            && self.credential_resolver == default_git_credential_resolver()
        {
            return Ok(());
        }
        let argv = &self.credential_resolver;
        let Some(program) = argv.first() else {
            return Err(invalid("credential_resolver", "argv must not be empty"));
        };
        let program_path = Path::new(program);
        if !program_path.is_absolute() {
            return Err(invalid(
                "credential_resolver",
                "argv[0] must be an absolute path",
            ));
        }
        let program_name = program_path
            .file_name()
            .and_then(|name| name.to_str())
            .unwrap_or_default()
            .to_ascii_lowercase();
        if matches!(
            program_name.trim_end_matches(".exe"),
            "sh" | "bash"
                | "dash"
                | "zsh"
                | "ksh"
                | "fish"
                | "csh"
                | "tcsh"
                | "cmd"
                | "powershell"
                | "pwsh"
                | "env"
        ) {
            return Err(invalid(
                "credential_resolver",
                "shell or env launcher is not allowed",
            ));
        }
        if argv.iter().any(|arg| arg.chars().any(char::is_control)) {
            return Err(invalid(
                "credential_resolver",
                "argv must not contain control characters",
            ));
        }
        if program.contains(['{', '}'])
            || argv[1..]
                .iter()
                .any(|arg| arg != "{ref}" && arg.contains(['{', '}']))
        {
            return Err(invalid(
                "credential_resolver",
                "{ref} must be a complete argument and is the only allowed template",
            ));
        }
        if !argv[1..].iter().any(|arg| arg == "{ref}") {
            return Err(invalid(
                "credential_resolver",
                "argv must contain a {ref} argument",
            ));
        }
        for (actor, identity) in &self.actors {
            if actor.trim().is_empty() || actor.chars().any(char::is_control) {
                return Err(invalid(
                    "actors",
                    "actor labels must be nonempty and contain no control characters",
                ));
            }
            for (field, value) in [
                ("name", &identity.name),
                ("email", &identity.email),
                ("credential_ref", &identity.credential_ref),
                ("platform_identity", &identity.platform_identity),
            ] {
                if value.trim().is_empty() || value.chars().any(char::is_control) {
                    return Err(invalid(
                        &format!("actors.{actor}.{field}"),
                        "must be nonempty and contain no control characters",
                    ));
                }
            }
            if identity.name.contains(['<', '>']) || identity.email.contains(['<', '>']) {
                return Err(invalid(
                    &format!("actors.{actor}"),
                    "name and email must not contain Git identity delimiters",
                ));
            }
        }
        Ok(())
    }
}

// ---- exec sandbox (ADR-181) ----

/// `[exec.limits]`: per-run resource limits applied to the sandboxed child
/// and inherited by its descendants (`setrlimit` before exec).
#[derive(Debug, Clone, Deserialize, Default)]
pub struct ExecLimitsConfig {
    #[serde(default)]
    pub cpu_seconds: Option<u64>,
    #[serde(default)]
    pub address_space: Option<u64>,
    #[serde(default)]
    pub file_size: Option<u64>,
    #[serde(default)]
    pub nproc: Option<u64>,
}

/// `[exec]` section (ADR-181): where runs materialize, what they may read,
/// which caller environment keys pass through, which executable paths the
/// `never` list matches, and the output caps, wall-clock defaults and resource
/// limits. `never` matches paths, not a program's capabilities (ADR-181 A9).
///
/// ```toml
/// [exec]
/// root = "/var/lib/khive/exec"
/// read_roots = ["/opt/toolchains/python3.11"]
/// env = ["SOURCE_DATE_EPOCH"]
/// # The never list matches resolved executable paths, not renamed copies.
/// never = ["/usr/bin/curl"]
/// max_output_bytes = 1048576
/// timeout_default_s = 30
/// timeout_max_s = 600
/// keep = false
///
/// [exec.limits]
/// cpu_seconds = 60
/// file_size = 104857600
/// ```
#[derive(Debug, Clone, Deserialize, Default)]
pub struct ExecSectionConfig {
    #[serde(default)]
    pub root: Option<String>,
    #[serde(default)]
    pub read_roots: Vec<String>,
    #[serde(default)]
    pub env: Vec<String>,
    #[serde(default)]
    pub never: Vec<String>,
    #[serde(default)]
    pub max_output_bytes: Option<u64>,
    #[serde(default)]
    pub timeout_default_s: Option<f64>,
    #[serde(default)]
    pub timeout_max_s: Option<f64>,
    #[serde(default)]
    pub keep: bool,
    #[serde(default)]
    pub limits: ExecLimitsConfig,
}

// ---- web fetch/search policy (ADR-175 Amendment 1, carried into ADR-191 D3) ----

/// One `[[web.allowlist]]` entry: an exclusive host the operator has opted
/// into reachability for `web.fetch`/`web.search`. Presence of ANY entry
/// makes the allowlist exclusive (ADR-175 A1.2.3); absence leaves the public
/// internet reachable subject to the other egress rules. Matched by exact,
/// normalized (lowercase, trailing-dot-stripped) host equality only — no
/// suffix wildcarding, unlike `[[web.credentials]].hosts` (A1.2.6).
#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub struct WebAllowlistEntry {
    pub host: String,
}

/// One `[[web.credentials]]` entry: a named secret, read from the process
/// environment at request time (never accepted as a verb argument), bound to
/// the set of hosts it may be presented to. Each `hosts` entry is either an
/// exact IP-literal address (matched exactly, never as a suffix) or a
/// hostname suffix (`example.com` matches `example.com` and any
/// `*.example.com` at a DNS label boundary) — ADR-175 A1.2.6.
#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub struct WebCredentialConfig {
    /// Name the caller passes as `web.fetch`'s `credential` argument.
    pub name: String,
    /// Process environment variable holding the secret value.
    pub env_var: String,
    /// Non-empty set of hosts (exact IP literals or hostname suffixes) this
    /// credential may be presented to.
    pub hosts: Vec<String>,
}

/// One canned result inside a `kind = "fixture"` `[[web.search_providers]]`
/// entry — deterministic, non-networked search results (demos, offline
/// corpora, and the fixture arm of `web.search`'s own test suite).
#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub struct WebFixtureResult {
    pub title: String,
    pub url: String,
    pub snippet: String,
}

/// One `[[web.search_providers]]` entry (ADR-175 A1.3). The provider is
/// operator configuration; `web.search`'s `provider` argument only selects
/// among entries declared here by `name`. Closed, tagged on `kind`.
#[derive(Debug, Clone, Deserialize, Serialize)]
#[serde(tag = "kind", rename_all = "lowercase", deny_unknown_fields)]
pub enum WebSearchProviderConfig {
    /// Deterministic canned results — no outbound request.
    Fixture {
        name: String,
        #[serde(default)]
        default: bool,
        results: Vec<WebFixtureResult>,
    },
    /// A real HTTP GET search backend. `url_template` must contain the
    /// literal substring `{query}`, replaced with the percent-encoded query
    /// at request time; `{limit}` is replaced with the effective limit when
    /// present. The response body is JSON: an array of `{title, url,
    /// snippet}` objects. `api_key_env`, when set, is a process environment
    /// variable sent as `Authorization: Bearer <value>`.
    Http {
        name: String,
        #[serde(default)]
        default: bool,
        url_template: String,
        #[serde(default)]
        api_key_env: Option<String>,
        /// Hosts (exact IP literals or hostname suffixes) `api_key_env`'s
        /// value may be presented to, modeled on
        /// `[[web.credentials]].hosts`. Required non-empty whenever
        /// `api_key_env` is set (`validate` enforces this) — an unscoped key
        /// would ride along to whatever host `url_template` resolves to,
        /// which defeats the point of scoping it at all.
        #[serde(default)]
        hosts: Vec<String>,
    },
}

impl WebSearchProviderConfig {
    pub fn name(&self) -> &str {
        match self {
            WebSearchProviderConfig::Fixture { name, .. } => name,
            WebSearchProviderConfig::Http { name, .. } => name,
        }
    }

    pub fn is_default(&self) -> bool {
        match self {
            WebSearchProviderConfig::Fixture { default, .. } => *default,
            WebSearchProviderConfig::Http { default, .. } => *default,
        }
    }
}

/// `[web]` section (ADR-175 Amendment 1, ADR-191 D3): operator policy for
/// `web.fetch` and `web.search` — ceilings, the address allowlist, credential
/// host-set bindings, and configured search providers.
///
/// No generic per-pack settings map exists in this file today (`PackConfig`
/// carries only `backend`/`no_embed`, both storage-routing concerns) so this
/// follows the established precedent for a pack needing rich operator policy:
/// a dedicated top-level section threaded through `RuntimeConfig`, the same
/// shape as `[exec]` and `[git_write]`.
///
/// ```toml
/// [web]
/// timeout_default_s = 30
/// timeout_max_s = 120
/// max_bytes_default = 5242880
/// max_bytes_max = 52428800
/// search_limit_default = 10
/// search_limit_max = 50
///
/// [[web.allowlist]]
/// host = "example.com"
///
/// [[web.credentials]]
/// name = "example-token"
/// env_var = "EXAMPLE_API_TOKEN"
/// hosts = ["example.com"]
///
/// [[web.search_providers]]
/// kind = "fixture"
/// name = "demo"
/// default = true
/// results = [{ title = "Example", url = "https://example.com", snippet = "..." }]
/// ```
#[derive(Debug, Clone, Deserialize, Serialize, Default)]
#[serde(deny_unknown_fields)]
pub struct WebSectionConfig {
    #[serde(default)]
    pub timeout_default_s: Option<u64>,
    #[serde(default)]
    pub timeout_max_s: Option<u64>,
    #[serde(default)]
    pub max_bytes_default: Option<u64>,
    #[serde(default)]
    pub max_bytes_max: Option<u64>,
    #[serde(default)]
    pub search_limit_default: Option<u32>,
    #[serde(default)]
    pub search_limit_max: Option<u32>,
    #[serde(default)]
    pub allowlist: Vec<WebAllowlistEntry>,
    #[serde(default)]
    pub credentials: Vec<WebCredentialConfig>,
    #[serde(default)]
    pub search_providers: Vec<WebSearchProviderConfig>,
    /// Directories `web.ingest`'s disk mode may read from, modeled on
    /// `[exec] read_roots`. Absent or empty fails closed: disk ingest is
    /// refused entirely until the operator names at least one root.
    #[serde(default)]
    pub read_roots: Vec<String>,
}

/// Effective operator bounds shared by file validation and programmatic web dispatch.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct WebCeilings {
    pub timeout_default_s: u64,
    pub timeout_max_s: u64,
    pub max_bytes_default: u64,
    pub max_bytes_max: u64,
    pub search_limit_default: u32,
    pub search_limit_max: u32,
}

impl Default for WebCeilings {
    fn default() -> Self {
        Self {
            timeout_default_s: 30,
            timeout_max_s: 120,
            max_bytes_default: 5 * 1024 * 1024,
            max_bytes_max: 50 * 1024 * 1024,
            search_limit_default: 10,
            search_limit_max: 50,
        }
    }
}

impl WebSectionConfig {
    pub fn resolved_ceilings(&self) -> Result<WebCeilings, ConfigError> {
        let defaults = WebCeilings::default();
        let bounds = WebCeilings {
            timeout_default_s: self.timeout_default_s.unwrap_or(defaults.timeout_default_s),
            timeout_max_s: self.timeout_max_s.unwrap_or(defaults.timeout_max_s),
            max_bytes_default: self.max_bytes_default.unwrap_or(defaults.max_bytes_default),
            max_bytes_max: self.max_bytes_max.unwrap_or(defaults.max_bytes_max),
            search_limit_default: self
                .search_limit_default
                .unwrap_or(defaults.search_limit_default),
            search_limit_max: self.search_limit_max.unwrap_or(defaults.search_limit_max),
        };
        for (key, default, maximum, maximum_key) in [
            (
                "timeout_default_s",
                bounds.timeout_default_s,
                bounds.timeout_max_s,
                "timeout_max_s",
            ),
            (
                "max_bytes_default",
                bounds.max_bytes_default,
                bounds.max_bytes_max,
                "max_bytes_max",
            ),
            (
                "search_limit_default",
                u64::from(bounds.search_limit_default),
                u64::from(bounds.search_limit_max),
                "search_limit_max",
            ),
        ] {
            if default == 0 || default > maximum {
                return Err(ConfigError::InvalidWebConfig {
                    key: key.into(),
                    reason: format!(
                        "resolved default must be positive and not exceed {maximum_key}={maximum}"
                    ),
                });
            }
        }
        if std::time::Instant::now()
            .checked_add(std::time::Duration::from_secs(bounds.timeout_max_s))
            .is_none()
        {
            return Err(ConfigError::InvalidWebConfig {
                key: "timeout_max_s".into(),
                reason: "cannot be represented as a request deadline".into(),
            });
        }
        Ok(bounds)
    }

    pub fn validate(&self) -> Result<(), ConfigError> {
        self.resolved_ceilings()?;
        let invalid = |key: &str, reason: &str| ConfigError::InvalidWebConfig {
            key: key.to_string(),
            reason: reason.to_string(),
        };
        let mut seen_hosts = std::collections::HashSet::new();
        for entry in &self.allowlist {
            let normalized = entry.host.trim().trim_end_matches('.').to_ascii_lowercase();
            if normalized.is_empty() {
                return Err(invalid("allowlist.host", "must not be empty"));
            }
            if !seen_hosts.insert(normalized) {
                return Err(invalid("allowlist.host", "duplicate host entry"));
            }
        }
        let mut seen_credentials = std::collections::HashSet::new();
        for credential in &self.credentials {
            if credential.name.trim().is_empty() {
                return Err(invalid("credentials.name", "must not be empty"));
            }
            if !seen_credentials.insert(credential.name.clone()) {
                return Err(invalid("credentials.name", "duplicate credential name"));
            }
            if credential.env_var.trim().is_empty() {
                return Err(invalid("credentials.env_var", "must not be empty"));
            }
            if credential.hosts.is_empty() {
                return Err(invalid(
                    "credentials.hosts",
                    "must name at least one host or suffix",
                ));
            }
        }
        let mut seen_providers = std::collections::HashSet::new();
        let mut default_count = 0;
        for provider in &self.search_providers {
            let name = provider.name();
            if name.trim().is_empty() {
                return Err(invalid("search_providers.name", "must not be empty"));
            }
            if !seen_providers.insert(name.to_string()) {
                return Err(invalid("search_providers.name", "duplicate provider name"));
            }
            if provider.is_default() {
                default_count += 1;
            }
            if let WebSearchProviderConfig::Http {
                url_template,
                api_key_env,
                hosts,
                ..
            } = provider
            {
                if !url_template.contains("{query}") {
                    return Err(invalid(
                        "search_providers.url_template",
                        "must contain the literal substring {query}",
                    ));
                }
                if api_key_env.is_some() && hosts.is_empty() {
                    return Err(invalid(
                        "search_providers.hosts",
                        "an api_key_env-bearing provider must name at least one host or suffix",
                    ));
                }
            }
        }
        if default_count > 1 {
            return Err(invalid(
                "search_providers",
                "at most one provider may set default = true",
            ));
        }
        Ok(())
    }
}

/// Top-level khive configuration loaded from `khive.toml` or `config.toml`.
///
/// Sections consumed today:
/// - `[[engines]]`: embedding engine declarations
/// - `[actor]`: default namespace / identity (OSS actor model)
/// - `[gate]`: built-in caller enrollment
/// - `[runtime]`: runtime knobs (pack selection, brain profile, output format)
/// - `[brain]`: actor read policy
/// - `[telemetry]`: stream and channel carrier policy
/// - `[[backends]]`: storage backend declarations (ADR-028)
/// - `[packs.<name>]`: per-pack backend assignments (ADR-028)
/// - `[display]`: rendering timezone (ADR-169)
///
/// Unknown top-level keys are silently ignored by serde for forward
/// compatibility. The `[actor]`, `[gate]`, `[brain]`, and `[telemetry]` tables are closed
/// with `deny_unknown_fields` so a misspelled policy key always fails startup.
#[derive(Debug, Clone, Deserialize, Default)]
pub struct KhiveConfig {
    #[serde(default)]
    pub mounts: Vec<crate::mount_config::MountConfig>,

    /// Typed only so a top-level `db` key can be rejected loudly by
    /// [`KhiveConfig::validate`] instead of being silently ignored as an
    /// unknown key. Not a supported config-file storage selector: single-file
    /// database selection is `--db`/`KHIVE_DB`, and storage topology is
    /// `[[backends]].path`.
    #[serde(default)]
    pub db: Option<String>,

    /// Embedding engine declarations.
    #[serde(default)]
    pub engines: Vec<EngineConfig>,

    /// Default actor identity for this khive instance.
    ///
    /// When present, `actor.id` feeds configuration identity and gate/attribution
    /// policy input.  A non-`'local'` `actor.id` is folded into the default READ
    /// visible-set at config load (ADR-007 Rev 4 Rule 3b) — it widens what default
    /// multi-record reads return, but never routes writes or sets `default_namespace`.
    /// Cloud model derives actor identity from an authenticated token.
    #[serde(default)]
    pub actor: ActorConfig,

    /// Optional caller-enrollment policy. A present, even empty, table is an
    /// explicit fail-closed policy; an absent table preserves the runtime's
    /// existing gate.
    #[serde(default)]
    pub gate: Option<GateSectionConfig>,

    /// Runtime knobs: namespace overrides, brain profile, etc.
    #[serde(default)]
    pub runtime: RuntimeSectionConfig,

    /// Named storage backends (ADR-028).
    ///
    /// When absent or empty, a single implicit `main` backend is used and all
    /// packs share it — identical to pre-ADR-028 behavior.
    #[serde(default)]
    pub backends: Vec<BackendConfig>,

    /// Per-pack backend assignments (ADR-028).
    ///
    /// Maps pack name to backend name. Packs absent from this map fall back to
    /// the `main` backend. Validated at load time: every referenced backend name
    /// must appear in `backends`.
    #[serde(default)]
    pub packs: std::collections::HashMap<String, PackConfig>,

    /// Actor read policy. An absent or empty list grants no fleet-wide reads.
    #[serde(default)]
    pub brain: BrainSectionConfig,

    /// Git-write policy allowlist (ADR-108 Amendment). Absent or empty
    /// `allowed` fails closed — `khive-pack-git`'s write verbs are
    /// unavailable until this section is populated.
    #[serde(default)]
    pub git_write: GitWriteSectionConfig,

    /// Storage-layer config not covered by `[[backends]]` (ADR-111
    /// Amendment 2: `[storage.blob]`'s `fs`/`s3` selector).
    #[serde(default)]
    pub storage: StorageSectionConfig,

    /// Exec sandbox section (ADR-181). Absent means no runs: the exec pack
    /// refuses every `exec.run` until `[exec] read_roots` names a toolchain.
    #[serde(default)]
    pub exec: ExecSectionConfig,

    /// Stream and channel carrier policy. Unclassified kinds default to ephemeral.
    #[serde(default)]
    pub telemetry: crate::telemetry_config::TelemetryConfig,

    /// Rendering timezone configuration (ADR-169). Absent `timezone` resolves
    /// to the host's local zone at [`RuntimeConfig`](crate::RuntimeConfig)
    /// construction time.
    #[serde(default)]
    pub display: DisplaySectionConfig,

    /// `web.fetch`/`web.search` operator policy (ADR-175 Amendment 1).
    /// Absent is the fail-closed default for search (no provider configured)
    /// and the permissive-subject-to-address-rules default for fetch (no
    /// allowlist configured).
    #[serde(default)]
    pub web: WebSectionConfig,
}

/// `[runtime]` section in `khive.toml`.
///
/// Carries runtime knobs resolved during process construction. Most mirror a
/// CLI flag / environment tier; field documentation calls out exceptions.
/// All fields are optional and preserve their already-resolved base value when
/// absent.
#[derive(Debug, Clone, Deserialize, Default)]
pub struct RuntimeSectionConfig {
    /// Packs to load when neither `--pack` nor `KHIVE_PACKS` selects them.
    /// An absent or empty list preserves the built-in production default.
    #[serde(default)]
    pub packs: Option<Vec<String>>,

    /// Brain profile ID to use for `memory.feedback` / `knowledge.feedback`
    /// and recall-time score boosting (ADR-035 §Brain profile configuration).
    ///
    /// Mirrors `--brain-profile` / `KHIVE_BRAIN_PROFILE`. When absent, the
    /// namespace-bound profile (via `brain.resolve`) is tried, then the
    /// global tuning prior is used as the final fallback.
    #[serde(default)]
    pub brain_profile: Option<String>,

    /// Default output serialization format (ADR-078).
    ///
    /// Mirrors `--output-format` / `KHIVE_OUTPUT_FORMAT`. Precedence (highest to lowest):
    /// per-request `format` field → `KHIVE_OUTPUT_FORMAT` → this field → builtin `json`.
    ///
    /// Accepted values: `"json"` (default), `"auto"`, `"table"`.
    #[serde(default)]
    pub default_output_format: Option<OutputFormat>,

    /// Aggregate process-local admission budget for digest-verified blob
    /// hydration (ADR-160 D3), in raw bytes.
    ///
    /// This knob has no environment-variable counterpart. When absent, the
    /// resolved runtime keeps its built-in 256 MiB default (or a value supplied
    /// directly through `RuntimeConfig`).
    #[serde(default)]
    pub blob_hydration_bytes: Option<u64>,
}

/// `[display]` section in `khive.toml` — the timezone khive anchors date-only
/// input to (ADR-169 Implementation step 1).
///
/// ```toml
/// [display]
/// timezone = "America/New_York"
/// ```
#[derive(Debug, Clone, Deserialize, Default)]
pub struct DisplaySectionConfig {
    /// IANA zone name (e.g. `"America/New_York"`, `"Asia/Tokyo"`, `"UTC"`).
    /// Validated at load time against `chrono_tz::Tz`'s zone table — an
    /// unrecognized name is a startup error, not a silent fallback. Absent →
    /// the host's local zone, resolved once via `iana-time-zone` and falling
    /// back to UTC when the host zone cannot be determined.
    #[serde(default)]
    pub timezone: Option<String>,
}

impl KhiveConfig {
    /// Load and validate a `KhiveConfig` from an explicit path.
    ///
    /// Search order:
    /// 1. `path` argument (explicit override — e.g. from `--config` / `KHIVE_CONFIG`)
    /// 2. `./.khive/config.toml` (project-local config, relative to the MCP server cwd)
    ///
    /// The project-local default collocates config with the `khive-test.db` that already
    /// lives under `.khive/` in each project directory. `~/.khive/config.toml` is searched
    /// by [`KhiveConfig::load_with_home_fallback`] when the project-local file is absent.
    ///
    /// If the resolved file does **not exist**, returns `Ok(None)`.
    /// A missing config is not an error — callers fall back to the env-var path.
    ///
    /// If the file exists but cannot be parsed, returns a `ConfigError`.
    /// After parsing, `validate()` runs and any logical errors are returned.
    pub fn load(path: Option<&Path>) -> Result<Option<Self>, ConfigError> {
        let resolved = match path {
            Some(p) => p.to_path_buf(),
            None => PathBuf::from(".khive/config.toml"),
        };

        if !resolved.exists() {
            return Ok(None);
        }

        // Diagnostics name the canonical path so an error is actionable from
        // any cwd; resolution keeps using `resolved` as given.
        let diagnostic_path = std::fs::canonicalize(&resolved).unwrap_or_else(|_| resolved.clone());
        let raw = std::fs::read_to_string(&resolved)
            .map_err(|source| ConfigError::from(source).in_file(&diagnostic_path))?;
        let cfg: KhiveConfig = toml::from_str(&raw).map_err(|source| ConfigError::Parse {
            path: diagnostic_path.clone(),
            source,
        })?;
        cfg.validate()
            .map_err(|error| error.in_file(&diagnostic_path))?;
        Ok(Some(cfg))
    }

    /// Load config with the full resolution order:
    ///
    /// 1. Explicit `path` (from `--config` / `KHIVE_CONFIG`)
    /// 2. `./khive.toml` (project-local, project root)
    /// 3. `<db-dir>/config.toml` (project-local, anchored to the resolved database's
    ///    own directory — see `project_config_anchor_dir`)
    /// 4. `~/.khive/config.toml` (user-global)
    ///
    /// Returns the first file found, or `Ok(None)` when none exist.
    /// Parse errors are propagated immediately — a malformed config is always
    /// an error regardless of which tier it came from.
    ///
    /// The explicit tier (1) is stricter than the discovery tiers: a `path`
    /// that names a file which does not exist returns
    /// [`ConfigError::ExplicitConfigMissing`] instead of falling through to
    /// tiers 2-4 — an operator-selected config that is missing is the same
    /// class of mistake as one that is malformed, and silently discovering a
    /// different file would boot against a config the operator did not select
    /// (ADR-035).
    ///
    /// `db_path` should be the same database path the caller is about to open
    /// (or has already resolved). Passing it makes tier 3 resolve identically
    /// for any two processes that target the same database, regardless of
    /// their process working directory — this is what lets a thin client and
    /// a warm daemon serving the same database agree on one config file. Pass
    /// `None` when no database path is known yet; tier 3 then falls back to
    /// the process cwd, matching the pre-existing behavior.
    pub fn load_with_home_fallback(
        path: Option<&Path>,
        db_path: Option<&Path>,
    ) -> Result<Option<Self>, ConfigError> {
        Ok(Self::load_with_home_fallback_and_source(path, db_path)?.map(|(config, _)| config))
    }

    /// Load config with the full resolution order and retain the exact file
    /// that supplied it.
    ///
    /// This is the diagnostic-preserving form of
    /// [`KhiveConfig::load_with_home_fallback`]. Runtime callers that need to
    /// tell an operator which selected file must be edited should use this
    /// method instead of reconstructing the discovery order independently.
    pub fn load_with_home_fallback_and_source(
        path: Option<&Path>,
        db_path: Option<&Path>,
    ) -> Result<Option<(Self, PathBuf)>, ConfigError> {
        // Tier 1: explicit path (highest priority). An explicit selection
        // naming a MISSING file fails loud here — once, at the loader, for
        // every entry point — instead of silently falling through to the
        // discovery tiers: a mistyped path would otherwise boot against a
        // config the operator did not select (ADR-035: an entry point must
        // not document an explicit tier while silently falling back to
        // discovery). Tiers 2-4 keep their tolerant contract.
        if let Some(p) = path {
            if !p.exists() {
                return Err(ConfigError::ExplicitConfigMissing {
                    path: p.to_path_buf(),
                });
            }
            return Ok(Self::load(Some(p))?.map(|config| (config, Self::diagnostic_config_path(p))));
        }

        // Tiers 2-4: search project root, db-anchored hidden dir, user-global.
        let project_root = std::env::current_dir().unwrap_or_else(|_| PathBuf::from("."));
        let home_root = std::env::var_os("HOME").map(PathBuf::from);
        Self::load_with_roots_and_source(&project_root, home_root.as_deref(), db_path)
    }

    /// Testable inner search: tiers 2-4, given explicit roots instead of
    /// reading `cwd` and `HOME` from process state.
    ///
    /// - Tier 2: `<project_root>/khive.toml` (still cwd-anchored — unchanged)
    /// - Tier 3: `<db_dir>/config.toml`, anchored to `db_path` rather than
    ///   `project_root` (see `project_config_anchor_dir`); falls back to
    ///   `<project_root>/.khive/config.toml` when `db_path` is `None`
    /// - Tier 4: `<home_root>/.khive/config.toml` (skipped when `None`)
    #[cfg(test)]
    pub(crate) fn load_with_roots(
        project_root: &Path,
        home_root: Option<&Path>,
        db_path: Option<&Path>,
    ) -> Result<Option<Self>, ConfigError> {
        Ok(
            Self::load_with_roots_and_source(project_root, home_root, db_path)?
                .map(|(config, _)| config),
        )
    }

    fn load_with_roots_and_source(
        project_root: &Path,
        home_root: Option<&Path>,
        db_path: Option<&Path>,
    ) -> Result<Option<(Self, PathBuf)>, ConfigError> {
        // Tier 2: project root khive.toml.
        let tier2 = project_root.join("khive.toml");
        if tier2.exists() {
            return Ok(Self::load(Some(&tier2))?
                .map(|config| (config, Self::diagnostic_config_path(&tier2))));
        }

        // Tier 3: project-local hidden dir, anchored to the resolved database's
        // own directory instead of the process cwd.
        let tier3 = Self::project_config_anchor_dir(db_path, project_root).join("config.toml");
        if tier3.exists() {
            return Ok(Self::load(Some(&tier3))?
                .map(|config| (config, Self::diagnostic_config_path(&tier3))));
        }

        // Tier 4: user-global ~/.khive/config.toml.
        if let Some(home) = home_root {
            let tier4 = home.join(".khive/config.toml");
            if tier4.exists() {
                return Ok(Self::load(Some(&tier4))?
                    .map(|config| (config, Self::diagnostic_config_path(&tier4))));
            }
        }

        Ok(None)
    }

    fn diagnostic_config_path(path: &Path) -> PathBuf {
        std::fs::canonicalize(path).unwrap_or_else(|_| path.to_path_buf())
    }

    /// Resolve the directory searched for the tier-3 project-local config file.
    ///
    /// Anchored to the directory containing the resolved database file, not the
    /// process cwd: two processes at different working directories that open the
    /// same database agree on this directory, which is what keeps their
    /// `config_id` fingerprints in sync (a client and a warm daemon serving the
    /// same database must resolve identical config so the daemon accepts the
    /// client's forwarded requests instead of rejecting them on a config
    /// mismatch).
    ///
    /// `db_path` is canonicalized first so symlinks/relative components collapse
    /// to the same absolute directory regardless of caller cwd. The database file
    /// may not exist yet (first run before anything has been written) — in that
    /// case canonicalization fails and the path is absolutized against
    /// `project_root` instead (or used as-is if already absolute); this must
    /// never panic, it is the expected cold-start case.
    ///
    /// If `db_dir` (the resolved database's parent directory) is itself named
    /// `.khive`, the config lives directly inside it (`<db_dir>/config.toml`) —
    /// this is the common case where the database is `<root>/.khive/khive.db`.
    /// Otherwise the config lives in a `.khive` subdirectory of `db_dir`.
    ///
    /// `db_path == None` (e.g. an in-memory database, or no database path known
    /// yet) falls back to `<project_root>/.khive`, preserving the pre-existing
    /// cwd-anchored behavior for callers with no database to anchor on.
    fn project_config_anchor_dir(db_path: Option<&Path>, project_root: &Path) -> PathBuf {
        let Some(db_path) = db_path else {
            return project_root.join(".khive");
        };

        let absolute = std::fs::canonicalize(db_path).unwrap_or_else(|_| {
            if db_path.is_absolute() {
                db_path.to_path_buf()
            } else {
                project_root.join(db_path)
            }
        });

        let db_dir = absolute.parent().map(Path::to_path_buf).unwrap_or(absolute);

        if db_dir.file_name().is_some_and(|name| name == ".khive") {
            db_dir
        } else {
            db_dir.join(".khive")
        }
    }

    /// Validate the parsed config for logical consistency.
    ///
    /// Checks:
    /// - Exactly one engine has `default = true` (when the list is non-empty).
    /// - Engine names are unique.
    /// - Every engine model is recognized by the runtime's alias parser.
    /// - `fusion_weight`, when present, is `> 0`.
    pub fn validate(&self) -> Result<(), ConfigError> {
        crate::mount_config::validate_mounts(&self.mounts)?;
        self.git_write.validate_dev_loop()?;
        self.telemetry.validate()?;
        self.web.validate()?;

        // Reject a top-level `db` key loudly instead of letting serde's
        // forward-compatible unknown-key tolerance silently swallow it: a
        // config author expecting `db=` to select the database would
        // otherwise get silent divergence from `--db`/`KHIVE_DB`.
        if let Some(value) = self.db.as_deref() {
            if !value.is_empty() {
                return Err(ConfigError::UnsupportedTopLevelDb {
                    value: value.to_string(),
                });
            }
        }

        // ADR-181 resource limits: macOS returns EINVAL for RLIMIT_AS and
        // RLIMIT_DATA, and RLIMIT_NPROC counts every process of the uid, so
        // neither can bound one run. Refuse loudly instead of pretending.
        if cfg!(target_os = "macos") {
            if self.exec.limits.address_space.is_some() {
                return Err(ConfigError::InvalidExecConfig {
                    key: "limits.address_space".to_string(),
                    reason: "unsupported_on_platform: macOS does not enforce an address-space rlimit per process".to_string(),
                });
            }
            if self.exec.limits.nproc.is_some() {
                return Err(ConfigError::InvalidExecConfig {
                    key: "limits.nproc".to_string(),
                    reason: "unsupported_on_platform: RLIMIT_NPROC counts every process of the uid, not one run".to_string(),
                });
            }
        }
        if let (Some(d), Some(m)) = (self.exec.timeout_default_s, self.exec.timeout_max_s) {
            if d > m {
                return Err(ConfigError::InvalidExecConfig {
                    key: "timeout_default_s".to_string(),
                    reason: format!("default {d} exceeds timeout_max_s {m}"),
                });
            }
        }

        if let Some(value) = self.runtime.blob_hydration_bytes {
            let min = khive_storage::MAX_BLOB_WHOLE_BYTES;
            let max = tokio::sync::Semaphore::MAX_PERMITS as u64;
            if value < min || value > max {
                return Err(ConfigError::InvalidBlobHydrationBytes { value, min, max });
            }
        }

        // Validate actor.id when present — an invalid namespace is a startup error,
        // not a silent fallback.
        if let Some(id) = self.actor.id.as_deref() {
            if id.is_empty() {
                return Err(ConfigError::InvalidActorId {
                    id: id.to_string(),
                    reason: "actor.id must not be empty; remove the key or provide a value"
                        .to_string(),
                });
            }
            Namespace::parse(id).map_err(|e| ConfigError::InvalidActorId {
                id: id.to_string(),
                reason: e.to_string(),
            })?;
        }

        self.actor
            .mailbox_gate(std::sync::Arc::new(khive_gate::AllowAllGate))
            .map_err(|error| ConfigError::InvalidMailboxReaders {
                reason: error.to_string(),
            })?;

        if let Some(ref vis) = self.actor.visible_namespaces {
            for ns_str in vis {
                if ns_str.is_empty() {
                    return Err(ConfigError::InvalidActorId {
                        id: ns_str.clone(),
                        reason: "visible_namespaces entries must not be empty".to_string(),
                    });
                }
                Namespace::parse(ns_str).map_err(|e| ConfigError::InvalidActorId {
                    id: ns_str.clone(),
                    reason: format!("invalid visible namespace: {e}"),
                })?;
            }
        }

        if let Some(gate) = &self.gate {
            khive_gate::CallerEnrollmentGate::validate_write_denials(&gate.deny_writes_for)
                .map_err(|error| ConfigError::InvalidWriteDenyPatterns {
                    reason: error.to_string(),
                })?;
            for id in &gate.granted_actors {
                if id.is_empty() {
                    return Err(ConfigError::InvalidGrantedActorId {
                        id: id.clone(),
                        reason: "actor ids must not be empty".to_string(),
                    });
                }
                Namespace::parse(id).map_err(|error| ConfigError::InvalidGrantedActorId {
                    id: id.clone(),
                    reason: error.to_string(),
                })?;
            }
        }

        // Validate actor.allowed_outbound_namespaces (fail-closed at startup on malformed entry).
        for ns_str in &self.actor.allowed_outbound_namespaces {
            if ns_str.is_empty() {
                return Err(ConfigError::InvalidActorId {
                    id: ns_str.clone(),
                    reason: "allowed_outbound_namespaces entries must not be empty".to_string(),
                });
            }
            Namespace::parse(ns_str).map_err(|e| ConfigError::InvalidActorId {
                id: ns_str.clone(),
                reason: format!("invalid allowed_outbound_namespaces entry: {e}"),
            })?;
        }

        // Backend names must be unique.
        if !self.backends.is_empty() {
            let mut seen_backends = std::collections::HashSet::new();
            for backend in &self.backends {
                BackendId::parse(&backend.name).map_err(|error| {
                    ConfigError::InvalidBackendName {
                        name: backend.name.clone(),
                        reason: error.to_string(),
                    }
                })?;
                if backend
                    .served_kinds
                    .as_ref()
                    .is_some_and(BTreeSet::is_empty)
                {
                    return Err(ConfigError::EmptyBackendServedKinds {
                        name: backend.name.clone(),
                    });
                }
                if !seen_backends.insert(backend.name.clone()) {
                    return Err(ConfigError::DuplicateBackendName {
                        name: backend.name.clone(),
                    });
                }

                // Reject fields that are parsed but not yet implemented: silently
                // accepting them would let misconfiguration slip past startup.
                if backend.cache_mb.is_some() {
                    return Err(ConfigError::UnsupportedBackendField {
                        name: backend.name.clone(),
                        field: "cache_mb",
                    });
                }
                if backend.journal_mode.is_some() {
                    return Err(ConfigError::UnsupportedBackendField {
                        name: backend.name.clone(),
                        field: "journal_mode",
                    });
                }
            }
        }

        let defined: Vec<&str> = if self.backends.is_empty() {
            vec![BackendId::MAIN]
        } else {
            self.backends.iter().map(|b| b.name.as_str()).collect()
        };
        for (pack_name, pack_cfg) in &self.packs {
            if !defined.contains(&pack_cfg.backend.as_str()) {
                return Err(ConfigError::UnknownPackBackend {
                    pack: pack_name.clone(),
                    backend: pack_cfg.backend.clone(),
                    defined: defined.join(", "),
                });
            }
        }

        if !self.backends.is_empty() {
            let missing: Vec<_> = [SubstrateKind::Note, SubstrateKind::Entity]
                .into_iter()
                .filter(|kind| {
                    !self.backends.iter().any(|backend| {
                        backend
                            .served_kinds
                            .as_ref()
                            .is_none_or(|served| served.contains(kind))
                    })
                })
                .collect();
            if !missing.is_empty() {
                return Err(ConfigError::MissingBackendSearchKinds {
                    kinds: missing,
                    defined: defined.join(", "),
                });
            }
        }

        // Validate [display] timezone (ADR-169): an unrecognized IANA zone
        // name is a startup error, not a silent fallback to the host zone.
        if let Some(tz) = self.display.timezone.as_deref() {
            if tz.trim().is_empty() || tz.parse::<chrono_tz::Tz>().is_err() {
                return Err(ConfigError::InvalidDisplayTimezone {
                    timezone: tz.to_string(),
                });
            }
        }

        // Validate [[git_write.allowed]] entries (ADR-108 Amendment): each
        // repo must be a non-empty absolute path, and each entry must carry
        // at least one branch pattern — an entry with an empty `branches`
        // list would silently allowlist a repo for no branch at all, which
        // reads as "configured" while behaving identically to "not
        // allowlisted"; reject it loudly instead of leaving that trap.
        for entry in &self.git_write.allowed {
            if entry.repo.trim().is_empty() {
                return Err(ConfigError::InvalidGitWriteEntry {
                    repo: entry.repo.clone(),
                    reason: "repo must not be empty".to_string(),
                });
            }
            if !Path::new(&entry.repo).is_absolute() {
                return Err(ConfigError::InvalidGitWriteEntry {
                    repo: entry.repo.clone(),
                    reason: "repo must be an absolute path".to_string(),
                });
            }
            if entry.branches.is_empty() {
                return Err(ConfigError::InvalidGitWriteEntry {
                    repo: entry.repo.clone(),
                    reason: "branches must not be empty".to_string(),
                });
            }
            if entry.branches.iter().any(|b| b.trim().is_empty()) {
                return Err(ConfigError::InvalidGitWriteEntry {
                    repo: entry.repo.clone(),
                    reason: "branches entries must not be empty".to_string(),
                });
            }
            // ADR-108 specifies exact name or a SINGLE-star wildcard per
            // branch pattern -- a pattern with two or more `*` (e.g. `**`,
            // `rel-*-*-final`) is a wider grammar than the ADR authorizes
            // and must be rejected at config load, not silently accepted.
            if let Some(bad) = entry.branches.iter().find(|b| b.matches('*').count() > 1) {
                return Err(ConfigError::InvalidGitWriteEntry {
                    repo: entry.repo.clone(),
                    reason: format!(
                        "branch pattern {bad:?} must contain at most one '*' wildcard (ADR-108)"
                    ),
                });
            }
        }

        if self.engines.is_empty() {
            return Ok(());
        }

        let mut seen_names = std::collections::HashSet::new();
        for engine in &self.engines {
            if !seen_names.insert(engine.name.clone()) {
                return Err(ConfigError::DuplicateName {
                    name: engine.name.clone(),
                });
            }
            if parse_embedding_model_alias(&engine.model).is_none() {
                return Err(ConfigError::UnknownModel {
                    name: engine.name.clone(),
                    model: engine.model.clone(),
                });
            }
        }

        let default_count = self.engines.iter().filter(|e| e.default).count();
        if default_count != 1 {
            return Err(ConfigError::DefaultCount {
                found: default_count,
            });
        }

        // Reject non-finite fusion_weight explicitly: NaN doesn't satisfy `w <= 0.0`
        // and +inf is unbounded, so neither is caught by the range check alone.
        for engine in &self.engines {
            if let Some(w) = engine.fusion_weight {
                if !w.is_finite() || w <= 0.0 {
                    return Err(ConfigError::InvalidFusionWeight {
                        name: engine.name.clone(),
                        value: w,
                    });
                }
            }
        }

        Ok(())
    }

    /// Return the engine flagged `default = true`, or `None` if the list is empty.
    pub fn default_engine(&self) -> Option<&EngineConfig> {
        self.engines.iter().find(|e| e.default)
    }
}

// ---- Env-var fallback ----

/// Build an in-memory `KhiveConfig` from the legacy env-var path.
///
/// Used when no config file is present. Emits `tracing::info!` directing
/// operators to migrate to `~/.khive/config.toml`.
///
/// The primary model (`KHIVE_EMBEDDING_MODEL`) becomes the `default = true`
/// engine; additional models become non-default secondary engines. When only
/// `KHIVE_ADDITIONAL_EMBEDDING_MODELS` is set, the built-in default model is
/// synthesized as the primary — the additional list is additive, never a
/// replacement for the primary (khive#1221; matches `RuntimeConfig::default()`,
/// which resolves an unset `KHIVE_EMBEDDING_MODEL` to the built-in default).
pub fn config_from_env() -> KhiveConfig {
    let primary_model = std::env::var("KHIVE_EMBEDDING_MODEL")
        .ok()
        .filter(|s| !s.trim().is_empty());
    let additional_raw = std::env::var("KHIVE_ADDITIONAL_EMBEDDING_MODELS")
        .ok()
        .unwrap_or_default();
    let additional: Vec<String> = crate::runtime::parse_pack_list(&additional_raw)
        .into_iter()
        .filter(|s| !s.is_empty())
        .collect();

    if primary_model.is_none() && additional.is_empty() {
        return KhiveConfig::default();
    }

    tracing::info!(
        "using env-var embedding config; consider migrating to .khive/config.toml in your project root"
    );

    config_from_env_parts(primary_model, additional)
}

/// Pure core of [`config_from_env`], separated so the engine-list derivation
/// is testable without mutating process-global environment variables.
fn config_from_env_parts(primary_model: Option<String>, additional: Vec<String>) -> KhiveConfig {
    let mut engines = Vec::new();

    let primary =
        primary_model.unwrap_or_else(|| lattice_embed::EmbeddingModel::AllMiniLmL6V2.to_string());
    engines.push(EngineConfig {
        name: "default".to_string(),
        model: primary.clone(),
        default: true,
        fusion_weight: None,
        dims: None,
    });

    for (i, model) in additional.into_iter().enumerate() {
        // The additional list restating the primary is a no-op, not a second engine.
        if model.eq_ignore_ascii_case(&primary) {
            continue;
        }
        engines.push(EngineConfig {
            name: format!("engine-{}", i + 1),
            model,
            default: false,
            fusion_weight: None,
            dims: None,
        });
    }

    KhiveConfig {
        engines,
        ..KhiveConfig::default()
    }
}

// ---- Tests ----

// Kept inline (not tests/): exercises private ConfigError variants not part
// of the public API.
#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn web_partial_ceiling_config_rejects_incoherent_effective_bounds_at_load() {
        let dir = tempfile::tempdir().unwrap();
        for (default_key, max_key, default, maximum) in [
            ("timeout_default_s", "timeout_max_s", 30_u64, 120_u64),
            (
                "max_bytes_default",
                "max_bytes_max",
                5 * 1024 * 1024,
                50 * 1024 * 1024,
            ),
            ("search_limit_default", "search_limit_max", 10, 50),
        ] {
            for invalid in [
                format!("{max_key}=1"),
                format!("{max_key}=0"),
                format!("{default_key}=0"),
                format!("{default_key}={}", maximum + 1),
                format!("{default_key}=2\n{max_key}=1"),
            ] {
                let path = write_toml(&dir, &format!("[web]\n{invalid}\n"));
                let error = KhiveConfig::load(Some(&path)).unwrap_err();
                assert!(
                    error.to_string().contains(default_key),
                    "{invalid}: {error}"
                );
            }
            for valid in [
                String::new(),
                format!("{max_key}={default}"),
                format!("{default_key}={maximum}"),
                format!("{default_key}=1\n{max_key}=1"),
            ] {
                let path = write_toml(&dir, &format!("[web]\n{valid}\n"));
                let config = KhiveConfig::load(Some(&path)).unwrap().unwrap();
                config.web.validate().unwrap();
            }
        }
    }

    #[test]
    fn web_ceiling_programmatic_validation_rejects_unrepresentable_deadlines() {
        let config = WebSectionConfig {
            timeout_max_s: Some(u64::MAX),
            ..Default::default()
        };
        assert!(
            matches!(config.resolved_ceilings(), Err(ConfigError::InvalidWebConfig { key, .. }) if key == "timeout_max_s")
        );
        assert!(config.validate().is_err());
        let config = WebSectionConfig {
            max_bytes_max: Some(1),
            ..Default::default()
        };
        assert!(config.resolved_ceilings().is_err());
    }

    fn write_toml(dir: &tempfile::TempDir, content: &str) -> PathBuf {
        let path = dir.path().join("config.toml");
        std::fs::write(&path, content).unwrap();
        path
    }

    fn in_memory_runtime_config() -> crate::RuntimeConfig {
        crate::RuntimeConfig {
            db_path: None,
            ..crate::RuntimeConfig::no_embeddings()
        }
    }

    /// Load errors must name the config file they came from (#1892): the
    /// validation and I/O errors gain the loader's `InFile` context, while
    /// `Parse` keeps carrying its own path. The message suffix is the
    /// user-facing contract.
    #[test]
    fn load_errors_name_the_config_file() {
        let dir = tempfile::tempdir().unwrap();

        let gate = write_toml(&dir, "[gate]\nmode = \"x\"\n");
        let err = KhiveConfig::load(Some(&gate)).expect_err("unknown gate key must fail");
        assert!(
            err.to_string().contains(&gate.display().to_string()),
            "gate error must name the file, got: {err}"
        );

        let invalid = write_toml(
            &dir,
            "[[engines]]\nname = \"a\"\nmodel = \"all-minilm-l6-v2\"\n",
        );
        let err = KhiveConfig::load(Some(&invalid)).expect_err("validation must fail");
        assert!(
            err.to_string().contains("(config file: "),
            "validation error must name the file, got: {err}"
        );

        let parse = write_toml(&dir, "not = = toml");
        let err = KhiveConfig::load(Some(&parse)).expect_err("parse must fail");
        assert!(
            err.to_string().contains("config.toml"),
            "parse error must name the file, got: {err}"
        );
        assert!(
            matches!(err, ConfigError::Parse { .. }),
            "parse errors keep their own variant unwrapped, got: {err:?}"
        );
    }

    /// Unwrap the loader's `InFile` context (asserting it names a real path)
    /// so variant-shape assertions test the underlying error.
    fn config_error_root(err: &ConfigError) -> &ConfigError {
        match err {
            ConfigError::InFile { path, source } => {
                assert!(
                    !path.as_os_str().is_empty(),
                    "InFile must carry the config path"
                );
                source
            }
            other => other,
        }
    }

    // khive#1221: with no primary set, the additional list must ADD to the
    // built-in default primary, never replace it.
    #[test]
    fn env_additional_only_keeps_builtin_primary() {
        let cfg = super::config_from_env_parts(
            None,
            vec!["paraphrase-multilingual-minilm-l12-v2".to_string()],
        );
        assert_eq!(cfg.engines.len(), 2);
        let default_engine = cfg.default_engine().expect("a default engine");
        assert_eq!(default_engine.model, "all-minilm-l6-v2");
        assert!(
            cfg.engines
                .iter()
                .any(|e| !e.default && e.model == "paraphrase-multilingual-minilm-l12-v2"),
            "additional model must be a non-default secondary engine"
        );
    }

    #[test]
    fn env_explicit_primary_stays_primary() {
        let cfg = super::config_from_env_parts(
            Some("paraphrase-multilingual-minilm-l12-v2".to_string()),
            vec![],
        );
        assert_eq!(cfg.engines.len(), 1);
        assert_eq!(
            cfg.default_engine().expect("default").model,
            "paraphrase-multilingual-minilm-l12-v2"
        );
    }

    #[test]
    fn env_additional_restating_primary_is_deduped() {
        let cfg = super::config_from_env_parts(None, vec!["all-minilm-l6-v2".to_string()]);
        assert_eq!(cfg.engines.len(), 1);
        assert!(cfg.engines[0].default);
    }

    #[test]
    fn test_load_minimal_config() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "x"
model = "all-minilm-l6-v2"
default = true
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("load should succeed")
            .expect("file should be found");
        assert_eq!(cfg.engines.len(), 1);
        assert_eq!(cfg.engines[0].name, "x");
        assert_eq!(cfg.engines[0].model, "all-minilm-l6-v2");
        assert!(cfg.engines[0].default);
    }

    #[test]
    fn test_unknown_engine_model_rejected_before_conversion() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            "[[engines]]\nname = \"primary\"\nmodel = \"not-a-model\"\ndefault = true\n",
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("unknown primary model must fail");
        assert!(
            matches!(
                config_error_root(&err),
                ConfigError::UnknownModel { name, model }
                    if name == "primary" && model == "not-a-model"
            ),
            "expected UnknownModel for the primary engine, got {err:?}"
        );

        let config: KhiveConfig = toml::from_str(
            "[[engines]]\nname = \"primary\"\nmodel = \"all-minilm-l6-v2\"\ndefault = true\n\n[[engines]]\nname = \"secondary\"\nmodel = \"not-a-model\"\n",
        )
        .unwrap();
        assert!(matches!(
            config.validate(),
            Err(ConfigError::UnknownModel { name, model })
                if name == "secondary" && model == "not-a-model"
        ));
    }

    #[test]
    fn test_recognized_engine_model_validates_and_converts() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            "[[engines]]\nname = \"primary\"\nmodel = \"all-minilm-l6-v2\"\ndefault = true\n",
        );
        let config = KhiveConfig::load(Some(&path)).unwrap().unwrap();
        config.validate().unwrap();
        let runtime = crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
        assert_eq!(
            runtime.embedding_model,
            Some(lattice_embed::EmbeddingModel::AllMiniLmL6V2)
        );
    }

    #[test]
    fn test_default_engine_required_when_engines_present() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "a"
model = "all-minilm-l6-v2"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("should fail with no default flagged");
        assert!(
            matches!(
                config_error_root(&err),
                ConfigError::DefaultCount { found: 0 }
            ),
            "expected DefaultCount {{ found: 0 }}, got {err:?}"
        );
    }

    #[test]
    fn test_multiple_default_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "a"
model = "all-minilm-l6-v2"
default = true

[[engines]]
name = "b"
model = "paraphrase-multilingual-minilm-l12-v2"
default = true
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("should fail with two defaults");
        assert!(
            matches!(
                config_error_root(&err),
                ConfigError::DefaultCount { found: 2 }
            ),
            "expected DefaultCount {{ found: 2 }}, got {err:?}"
        );
    }

    #[test]
    fn test_fusion_weight_validation() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "a"
model = "all-minilm-l6-v2"
default = true
fusion_weight = -0.5
"#,
        );
        let err =
            KhiveConfig::load(Some(&path)).expect_err("should fail with negative fusion_weight");
        assert!(
            matches!(
                config_error_root(&err),
                ConfigError::InvalidFusionWeight { .. }
            ),
            "expected InvalidFusionWeight, got {err:?}"
        );

        let path2 = write_toml(
            &dir,
            r#"
[[engines]]
name = "a"
model = "all-minilm-l6-v2"
default = true
fusion_weight = 0.0
"#,
        );
        let err2 =
            KhiveConfig::load(Some(&path2)).expect_err("should fail with zero fusion_weight");
        assert!(
            matches!(
                config_error_root(&err2),
                ConfigError::InvalidFusionWeight { .. }
            ),
            "expected InvalidFusionWeight, got {err2:?}"
        );
    }

    #[test]
    fn test_env_var_fallback() {
        let dir = tempfile::tempdir().unwrap();
        let absent = dir.path().join("missing.toml");

        let loaded = KhiveConfig::load(Some(&absent)).unwrap();
        assert!(loaded.is_none());

        // Can't safely set env vars in a parallel test suite, so exercise the
        // direct construction path instead.
        let primary = "all-minilm-l6-v2".to_string();
        let additional = vec!["paraphrase-multilingual-minilm-l12-v2".to_string()];

        let mut engines = vec![EngineConfig {
            name: "default".to_string(),
            model: primary,
            default: true,
            fusion_weight: None,
            dims: None,
        }];
        for (i, model) in additional.into_iter().enumerate() {
            engines.push(EngineConfig {
                name: format!("engine-{}", i + 1),
                model,
                default: false,
                fusion_weight: None,
                dims: None,
            });
        }
        let cfg = KhiveConfig {
            engines,
            ..KhiveConfig::default()
        };
        cfg.validate().expect("env-derived config should be valid");
        assert_eq!(cfg.engines.len(), 2);
        assert!(cfg.default_engine().is_some());
        assert_eq!(cfg.default_engine().unwrap().name, "default");
    }

    #[test]
    fn test_file_overrides_env() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "file-engine"
model = "all-minilm-l6-v2"
default = true
"#,
        );

        // KhiveConfig::load returns the file config regardless of env vars;
        // warning-on-conflict is the caller's responsibility.
        let cfg = KhiveConfig::load(Some(&path))
            .expect("load should succeed")
            .expect("file should be present");
        assert_eq!(cfg.engines[0].name, "file-engine");
    }

    #[test]
    fn test_duplicate_engine_names_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "shared"
model = "all-minilm-l6-v2"
default = true

[[engines]]
name = "shared"
model = "paraphrase-multilingual-minilm-l12-v2"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("should fail with duplicate name");
        assert!(
            matches!(config_error_root(&err), ConfigError::DuplicateName { .. }),
            "expected DuplicateName, got {err:?}"
        );
    }

    #[test]
    fn test_empty_config_is_valid() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "# no engines\n");
        let cfg = KhiveConfig::load(Some(&path))
            .expect("load should succeed")
            .expect("file should be found");
        assert!(cfg.engines.is_empty());
        cfg.validate().expect("empty config should be valid");
    }

    #[test]
    fn runtime_blob_hydration_budget_parses_and_resolves_before_engine_early_return() {
        use crate::runtime::runtime_config_from_khive_config;
        use crate::RuntimeConfig;

        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[runtime]
blob_hydration_bytes = 134217728
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("load should succeed")
            .expect("file should be found");

        assert_eq!(cfg.runtime.blob_hydration_bytes, Some(134_217_728));
        let resolved = runtime_config_from_khive_config(&cfg, RuntimeConfig::default());
        assert_eq!(resolved.blob_hydration_bytes, 134_217_728);
    }

    #[test]
    fn runtime_blob_hydration_budget_below_one_whole_blob_is_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let value = khive_storage::MAX_BLOB_WHOLE_BYTES - 1;
        let path = write_toml(
            &dir,
            &format!("[runtime]\nblob_hydration_bytes = {value}\n"),
        );

        let err = KhiveConfig::load(Some(&path)).expect_err("undersized budget must fail closed");
        assert!(
            matches!(
                config_error_root(&err),
                ConfigError::InvalidBlobHydrationBytes {
                    value: actual,
                    min,
                    ..
                } if *actual == value && *min == khive_storage::MAX_BLOB_WHOLE_BYTES
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn runtime_blob_hydration_budget_accepts_the_inclusive_portable_minimum() {
        let dir = tempfile::tempdir().unwrap();
        let value = khive_storage::MAX_BLOB_WHOLE_BYTES;
        let path = write_toml(
            &dir,
            &format!("[runtime]\nblob_hydration_bytes = {value}\n"),
        );

        let cfg = KhiveConfig::load(Some(&path))
            .expect("the inclusive minimum must be valid")
            .expect("config should exist");
        assert_eq!(cfg.runtime.blob_hydration_bytes, Some(value));
    }

    #[test]
    fn runtime_blob_hydration_budget_above_semaphore_capacity_is_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let max = tokio::sync::Semaphore::MAX_PERMITS as u64;
        let value = max
            .checked_add(1)
            .expect("tokio maximum fits below u64::MAX");
        let path = write_toml(
            &dir,
            &format!("[runtime]\nblob_hydration_bytes = {value}\n"),
        );

        let err = KhiveConfig::load(Some(&path)).expect_err("oversized budget must fail closed");
        assert!(
            matches!(
                config_error_root(&err),
                ConfigError::InvalidBlobHydrationBytes {
                    value: actual,
                    max: actual_max,
                    ..
                } if *actual == value && *actual_max == max
            ),
            "got {err:?}"
        );
    }

    #[test]
    fn test_multi_engine_positive_fusion_weight() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "primary"
model = "all-minilm-l6-v2"
default = true
fusion_weight = 0.7

[[engines]]
name = "secondary"
model = "paraphrase-multilingual-minilm-l12-v2"
fusion_weight = 0.3
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("load should succeed")
            .expect("file should be found");
        assert_eq!(cfg.engines.len(), 2);
        assert_eq!(cfg.engines[0].fusion_weight, Some(0.7));
        assert_eq!(cfg.engines[1].fusion_weight, Some(0.3));
    }

    #[test]
    fn test_actor_id_parsed() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[actor]
id = "lambda:khive"
display_name = "example actor"
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("load should succeed")
            .expect("file should be found");
        assert_eq!(cfg.actor.id.as_deref(), Some("lambda:khive"));
        assert_eq!(cfg.actor.display_name.as_deref(), Some("example actor"));
        assert!(cfg.engines.is_empty());
    }

    #[test]
    fn gate_mailbox_reader_config_loads_exact_labels_and_rejects_bad_policy() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            "[actor]\nid = \"lambda:owner\"\nmailbox_readers = [\"lambda:helper\", \"助手/审阅者\", \"lambda:helper\"]\n",
        );
        let config = KhiveConfig::load(Some(&path)).unwrap().unwrap();
        assert_eq!(
            config.actor.mailbox_readers,
            ["lambda:helper", "助手/审阅者", "lambda:helper"]
        );

        for (owner, readers) in [
            (None, vec!["reader".to_string()]),
            (Some("local"), vec!["reader".to_string()]),
            (Some("lambda:owner"), vec!["local".to_string()]),
            (Some("lambda:owner"), vec![String::new()]),
            (Some("lambda:owner"), vec![" \t".to_string()]),
            (Some("lambda:owner"), vec!["bad\nactor".to_string()]),
            (Some("lambda:owner"), vec!["x".repeat(256)]),
            (Some("lambda:owner"), vec!["reader".to_string(); 257]),
        ] {
            let config = KhiveConfig {
                actor: ActorConfig {
                    id: owner.map(str::to_string),
                    mailbox_readers: readers,
                    ..Default::default()
                },
                ..Default::default()
            };
            assert!(matches!(
                config.validate(),
                Err(ConfigError::InvalidMailboxReaders { .. })
            ));
        }
        for source in [
            "[actor]\nmailbox_readers = [\"reader\"]\n",
            "[actor]\nid = \"local\"\nmailbox_readers = [\"reader\"]\n",
            "[actor]\nid = \"lambda:owner\"\nmailbox_readers = [\"\"]\n",
            "[actor]\nid = \"lambda:owner\"\nmailbox_readers = \"reader\"\n",
        ] {
            let path = write_toml(&dir, source);
            assert!(KhiveConfig::load(Some(&path)).is_err());
        }
        let boundary = KhiveConfig {
            actor: ActorConfig {
                id: Some("lambda:owner".into()),
                mailbox_readers: vec!["x".repeat(255); 256],
                ..Default::default()
            },
            ..Default::default()
        };
        boundary.validate().unwrap();
        KhiveConfig::default().validate().unwrap();
    }

    #[test]
    fn test_actor_and_engines_together() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[actor]
id = "lambda:test"

[[engines]]
name = "default"
model = "all-minilm-l6-v2"
default = true
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("load should succeed")
            .expect("file should be found");
        assert_eq!(cfg.actor.id.as_deref(), Some("lambda:test"));
        assert_eq!(cfg.engines.len(), 1);
    }

    #[test]
    fn test_actor_absent_defaults_to_none() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "x"
model = "all-minilm-l6-v2"
default = true
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("load should succeed")
            .expect("file should be found");
        assert!(
            cfg.actor.id.is_none(),
            "actor.id must be None when [actor] section is absent"
        );
    }

    #[test]
    fn test_load_with_home_fallback_no_files() {
        let project_dir = tempfile::tempdir().unwrap();
        let home_dir = tempfile::tempdir().unwrap();
        let result = KhiveConfig::load_with_roots(project_dir.path(), Some(home_dir.path()), None);
        assert!(
            result.expect("no error expected").is_none(),
            "should return None when no config files exist in the given roots"
        );
    }

    #[test]
    fn home_gate_config_loads_while_explicit_empty_config_is_hermetic() {
        let project_dir = tempfile::tempdir().unwrap();
        let home_dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(home_dir.path().join(".khive")).unwrap();
        std::fs::write(
            home_dir.path().join(".khive/config.toml"),
            "[gate]\ngranted_actors = [\"lambda:enrolled\"]\ndeny_writes_for = [\"*:duty\"]\n",
        )
        .unwrap();

        let loaded = KhiveConfig::load_with_roots(project_dir.path(), Some(home_dir.path()), None)
            .expect("supported home gate policy loads")
            .expect("home config exists");
        let gate = loaded.gate.expect("gate table");
        assert_eq!(gate.granted_actors, vec!["lambda:enrolled"]);
        assert_eq!(gate.deny_writes_for, vec!["*:duty"]);

        let empty = project_dir.path().join("empty-khive-config.toml");
        std::fs::write(&empty, "").unwrap();
        let isolated = KhiveConfig::load_with_home_fallback(Some(&empty), None)
            .expect("an explicit empty fixture must isolate config discovery")
            .expect("the explicit config exists");
        assert!(isolated.engines.is_empty());
        assert!(isolated.actor.id.is_none());
        assert!(isolated.gate.is_none());
    }

    #[test]
    fn test_load_with_home_fallback_explicit_path() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[actor]
id = "lambda:explicit"
"#,
        );
        let cfg = KhiveConfig::load_with_home_fallback(Some(&path), None)
            .expect("no error expected")
            .expect("file found");
        assert_eq!(cfg.actor.id.as_deref(), Some("lambda:explicit"));
    }

    #[test]
    fn load_with_home_fallback_and_source_names_selected_file() {
        let project_dir = tempfile::tempdir().unwrap();
        let home_dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(home_dir.path().join(".khive")).unwrap();
        let selected = home_dir.path().join(".khive/config.toml");
        std::fs::write(&selected, "[actor]\nid = \"lambda:home\"\n").unwrap();

        let (config, source) = KhiveConfig::load_with_roots_and_source(
            project_dir.path(),
            Some(home_dir.path()),
            None,
        )
        .expect("load should succeed")
        .expect("home fallback should be selected");

        assert_eq!(config.actor.id.as_deref(), Some("lambda:home"));
        assert_eq!(
            source,
            std::fs::canonicalize(selected).expect("canonical selected config path")
        );
    }

    #[test]
    fn test_invalid_actor_id_rejected_at_load() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[actor]
id = "bad namespace"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("should fail with invalid actor.id");
        assert!(
            matches!(config_error_root(&err), ConfigError::InvalidActorId { .. }),
            "expected InvalidActorId, got {err:?}"
        );
    }

    #[test]
    fn test_empty_actor_id_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[actor]
id = ""
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("empty actor.id should be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::InvalidActorId { .. }),
            "expected InvalidActorId for empty string, got {err:?}"
        );
    }

    #[test]
    fn test_malformed_actor_id_lambda_colon_only() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[actor]
id = "lambda:"
"#,
        );
        let err =
            KhiveConfig::load(Some(&path)).expect_err("lambda: with no slug should be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::InvalidActorId { .. }),
            "expected InvalidActorId for 'lambda:', got {err:?}"
        );
    }

    // actor.id must not become default_namespace: writes stay pinned to `local`
    // even though a non-local actor.id widens the default read visible-set.
    #[test]
    fn test_runtime_config_actor_id_does_not_override_namespace() {
        use crate::runtime::runtime_config_from_khive_config;
        use crate::RuntimeConfig;
        use khive_types::namespace::Namespace;

        let cfg = KhiveConfig {
            engines: vec![],
            actor: ActorConfig {
                id: Some("lambda:test-actor".to_string()),
                display_name: None,
                ..Default::default()
            },
            ..KhiveConfig::default()
        };
        cfg.validate().expect("valid config");

        let base = RuntimeConfig::default();
        let result = runtime_config_from_khive_config(&cfg, base);
        assert_eq!(
            result.default_namespace,
            Namespace::local(),
            "actor.id must NOT become default_namespace (ADR-007 Rev 4 Rule 0); \
             writes stay pinned to local"
        );
        // actor.id must also appear in visible_namespaces: the load-bearing
        // side effect that widens default reads to {local} ∪ {actor namespace}.
        assert!(
            result
                .visible_namespaces
                .contains(&Namespace::parse("lambda:test-actor").unwrap()),
            "actor.id must be folded into visible_namespaces (ADR-007 Rev 4 Rule 3b fold-in); \
             got: {:?}",
            result.visible_namespaces
        );
    }

    #[test]
    fn test_runtime_config_no_actor_preserves_base() {
        use crate::runtime::runtime_config_from_khive_config;
        use crate::RuntimeConfig;
        use khive_types::namespace::Namespace;

        let cfg = KhiveConfig {
            engines: vec![],
            actor: ActorConfig {
                id: None,
                display_name: None,
                ..Default::default()
            },
            ..KhiveConfig::default()
        };
        cfg.validate().expect("valid config");

        let base_ns = Namespace::parse("lambda:base").unwrap();
        let base = RuntimeConfig {
            default_namespace: base_ns.clone(),
            ..RuntimeConfig::default()
        };
        let result = runtime_config_from_khive_config(&cfg, base);
        assert_eq!(
            result.default_namespace, base_ns,
            "no actor.id must leave base namespace unchanged"
        );
    }

    #[test]
    fn test_load_with_home_fallback_project_root_over_hidden() {
        let dir = tempfile::tempdir().unwrap();

        // Write .khive/config.toml (tier 3).
        std::fs::create_dir_all(dir.path().join(".khive")).unwrap();
        std::fs::write(
            dir.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:hidden\"\n",
        )
        .unwrap();

        // Write khive.toml (tier 2) — should win.
        std::fs::write(
            dir.path().join("khive.toml"),
            "[actor]\nid = \"lambda:project-root\"\n",
        )
        .unwrap();

        let cfg = KhiveConfig::load_with_roots(dir.path(), None, None)
            .expect("no error expected")
            .expect("file should be found");
        assert_eq!(
            cfg.actor.id.as_deref(),
            Some("lambda:project-root"),
            "khive.toml (tier 2) must win over .khive/config.toml (tier 3)"
        );
    }

    #[test]
    fn test_load_with_home_fallback_hidden_over_absent_root() {
        let dir = tempfile::tempdir().unwrap();

        std::fs::create_dir_all(dir.path().join(".khive")).unwrap();
        std::fs::write(
            dir.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:hidden-config\"\n",
        )
        .unwrap();
        // No khive.toml.

        let cfg = KhiveConfig::load_with_roots(dir.path(), None, None)
            .expect("no error expected")
            .expect("file should be found");
        assert_eq!(
            cfg.actor.id.as_deref(),
            Some("lambda:hidden-config"),
            ".khive/config.toml (tier 3) must be found when khive.toml is absent"
        );
    }

    #[test]
    fn test_load_with_roots_home_tier_found() {
        let project_dir = tempfile::tempdir().unwrap();
        let home_dir = tempfile::tempdir().unwrap();

        std::fs::create_dir_all(home_dir.path().join(".khive")).unwrap();
        std::fs::write(
            home_dir.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:user-global\"\n",
        )
        .unwrap();
        // No project-level files.

        let cfg = KhiveConfig::load_with_roots(project_dir.path(), Some(home_dir.path()), None)
            .expect("no error expected")
            .expect("file should be found");
        assert_eq!(
            cfg.actor.id.as_deref(),
            Some("lambda:user-global"),
            "~/.khive/config.toml (tier 4) must be found when project files absent"
        );
    }

    #[test]
    fn test_load_with_roots_project_wins_over_home() {
        let project_dir = tempfile::tempdir().unwrap();
        let home_dir = tempfile::tempdir().unwrap();

        // Home has a config.
        std::fs::create_dir_all(home_dir.path().join(".khive")).unwrap();
        std::fs::write(
            home_dir.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:user-global\"\n",
        )
        .unwrap();

        // Project also has a config — should win.
        std::fs::create_dir_all(project_dir.path().join(".khive")).unwrap();
        std::fs::write(
            project_dir.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:project-wins\"\n",
        )
        .unwrap();

        let cfg = KhiveConfig::load_with_roots(project_dir.path(), Some(home_dir.path()), None)
            .expect("no error expected")
            .expect("file should be found");
        assert_eq!(
            cfg.actor.id.as_deref(),
            Some("lambda:project-wins"),
            "project .khive/config.toml (tier 3) must win over ~/.khive/config.toml (tier 4)"
        );
    }

    // ── tier-3 db-dir anchor tests (config discovery canonicalization) ─────

    // Two different process working directories, targeting the same database,
    // must resolve the identical tier-3 config file. Each cwd also carries its
    // own decoy `.khive/config.toml` so the test fails loudly (mismatched
    // actor ids) if the resolver ever falls back to the old cwd anchor instead
    // of the db-dir anchor.
    #[test]
    fn test_load_with_roots_same_db_different_cwd_resolves_identical_config() {
        let cwd_a = tempfile::tempdir().unwrap();
        let cwd_b = tempfile::tempdir().unwrap();

        // Decoy cwd-anchored configs — must NOT be picked up once anchoring
        // moves to the db directory.
        std::fs::create_dir_all(cwd_a.path().join(".khive")).unwrap();
        std::fs::write(
            cwd_a.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:wrong-cwd-a\"\n",
        )
        .unwrap();
        std::fs::create_dir_all(cwd_b.path().join(".khive")).unwrap();
        std::fs::write(
            cwd_b.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:wrong-cwd-b\"\n",
        )
        .unwrap();

        // The database and its co-located config live under a THIRD root,
        // distinct from either simulated cwd.
        let db_root = tempfile::tempdir().unwrap();
        let khive_dir = db_root.path().join(".khive");
        std::fs::create_dir_all(&khive_dir).unwrap();
        let db_path = khive_dir.join("khive.db");
        std::fs::write(&db_path, b"").unwrap(); // must exist for canonicalize to succeed
        std::fs::write(
            khive_dir.join("config.toml"),
            "[actor]\nid = \"lambda:db-anchored\"\n",
        )
        .unwrap();

        let cfg_a = KhiveConfig::load_with_roots(cwd_a.path(), None, Some(&db_path))
            .expect("no error expected")
            .expect("db-anchored config must be found from cwd A");
        let cfg_b = KhiveConfig::load_with_roots(cwd_b.path(), None, Some(&db_path))
            .expect("no error expected")
            .expect("db-anchored config must be found from cwd B");

        assert_eq!(
            cfg_a.actor.id.as_deref(),
            Some("lambda:db-anchored"),
            "cwd A must resolve the db-anchored config, not its own decoy"
        );
        assert_eq!(
            cfg_b.actor.id.as_deref(),
            Some("lambda:db-anchored"),
            "cwd B must resolve the db-anchored config, not its own decoy"
        );
        assert_eq!(
            cfg_a.actor.id, cfg_b.actor.id,
            "two processes at different cwds targeting the same db must resolve \
             identical config, killing config_id drift between client and daemon"
        );
    }

    // Explicit `--config`/`KHIVE_CONFIG` (tier 1) must still win over the new
    // db-dir anchor (tier 3) — precedence is preserved, only the tier-3 anchor
    // moved.
    #[test]
    fn test_load_with_home_fallback_explicit_config_wins_over_db_anchor() {
        let explicit_dir = tempfile::tempdir().unwrap();
        let explicit_path = write_toml(&explicit_dir, "[actor]\nid = \"lambda:explicit-wins\"\n");

        let db_root = tempfile::tempdir().unwrap();
        let khive_dir = db_root.path().join(".khive");
        std::fs::create_dir_all(&khive_dir).unwrap();
        let db_path = khive_dir.join("khive.db");
        std::fs::write(&db_path, b"").unwrap();
        std::fs::write(
            khive_dir.join("config.toml"),
            "[actor]\nid = \"lambda:db-anchor-loses\"\n",
        )
        .unwrap();

        let cfg = KhiveConfig::load_with_home_fallback(Some(&explicit_path), Some(&db_path))
            .expect("no error expected")
            .expect("explicit path must be found");
        assert_eq!(
            cfg.actor.id.as_deref(),
            Some("lambda:explicit-wins"),
            "explicit --config/KHIVE_CONFIG must win over the db-dir anchor"
        );
    }

    // Tier 4 (`~/.khive/config.toml`) must still be reached when the db-anchored
    // tier-3 directory has no `config.toml` alongside it.
    #[test]
    fn test_load_with_roots_home_fallback_reached_when_db_anchor_has_no_config() {
        let cwd = tempfile::tempdir().unwrap();
        let home_dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(home_dir.path().join(".khive")).unwrap();
        std::fs::write(
            home_dir.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:home-fallback\"\n",
        )
        .unwrap();

        // A real db directory that exists but has no co-located config.toml.
        let db_root = tempfile::tempdir().unwrap();
        let khive_dir = db_root.path().join(".khive");
        std::fs::create_dir_all(&khive_dir).unwrap();
        let db_path = khive_dir.join("khive.db");
        std::fs::write(&db_path, b"").unwrap();

        let cfg = KhiveConfig::load_with_roots(cwd.path(), Some(home_dir.path()), Some(&db_path))
            .expect("no error expected")
            .expect("home-tier config must be found");
        assert_eq!(
            cfg.actor.id.as_deref(),
            Some("lambda:home-fallback"),
            "tier 4 (~/.khive/config.toml) must still be reached when the db-anchored \
             tier-3 directory has no config.toml"
        );
    }

    // Cold start: the database file does not exist yet (first run). Anchor
    // resolution must not panic and must fall through the remaining tiers.
    #[test]
    fn test_load_with_roots_nonexistent_db_path_does_not_panic_and_falls_through() {
        let cwd = tempfile::tempdir().unwrap();
        let home_dir = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(home_dir.path().join(".khive")).unwrap();
        std::fs::write(
            home_dir.path().join(".khive/config.toml"),
            "[actor]\nid = \"lambda:home-cold-start\"\n",
        )
        .unwrap();

        // Absolute path under a directory tree that was never created.
        let nonexistent_db = cwd.path().join("never-created/.khive/khive.db");

        let cfg =
            KhiveConfig::load_with_roots(cwd.path(), Some(home_dir.path()), Some(&nonexistent_db))
                .expect("cold-start db path must not error or panic")
                .expect("home-tier config must still be found");
        assert_eq!(
            cfg.actor.id.as_deref(),
            Some("lambda:home-cold-start"),
            "a nonexistent db path (cold start) must fall through to tier 4, not panic"
        );
    }

    // Cold start with a *relative* nonexistent db path exercises the
    // cwd-join fallback branch specifically (as opposed to the
    // already-absolute fallback branch above). Must not panic; no config
    // exists anywhere so the result is `Ok(None)`.
    #[test]
    fn test_load_with_roots_relative_nonexistent_db_path_does_not_panic() {
        let cwd = tempfile::tempdir().unwrap();
        let relative_db = PathBuf::from("never-created/.khive/khive.db");

        let result = KhiveConfig::load_with_roots(cwd.path(), None, Some(&relative_db));
        assert!(
            result.is_ok(),
            "relative cold-start db path must not error or panic: {result:?}"
        );
        assert!(
            result.unwrap().is_none(),
            "no config exists anywhere in this test; result must be None"
        );
    }

    // ── ADR-028 backend / pack config tests ─────────────────────────────────

    #[test]
    fn test_no_backends_section_is_valid() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[engines]]
name = "default"
model = "all-minilm-l6-v2"
default = true
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert!(cfg.backends.is_empty());
        assert!(cfg.packs.is_empty());
    }

    #[test]
    fn test_single_sqlite_backend_parses() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "knowledge"
kind = "sqlite"
path = "/tmp/knowledge.db"
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert_eq!(cfg.backends.len(), 1);
        let b = &cfg.backends[0];
        assert_eq!(b.name, "knowledge");
        assert!(matches!(b.kind, BackendKind::Sqlite));
        assert_eq!(
            b.path.as_ref().and_then(|p| p.to_str()),
            Some("/tmp/knowledge.db")
        );
    }

    #[test]
    fn test_memory_backend_parses() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "ephemeral"
kind = "memory"
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert_eq!(cfg.backends.len(), 1);
        assert!(matches!(cfg.backends[0].kind, BackendKind::Memory));
    }

    #[test]
    fn test_pack_backend_assignment_parses() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "knowledge"
kind = "memory"

[packs.knowledge]
backend = "knowledge"
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert_eq!(cfg.packs.len(), 1);
        let pc = cfg.packs.get("knowledge").expect("knowledge pack present");
        assert_eq!(pc.backend, "knowledge");
    }

    #[test]
    fn test_duplicate_backend_name_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "dup"
kind = "memory"

[[backends]]
name = "dup"
kind = "memory"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("should fail with duplicate name");
        assert!(
            matches!(config_error_root(&err), ConfigError::DuplicateBackendName { ref name } if name == "dup"),
            "expected DuplicateBackendName {{ name: \"dup\" }}, got {err:?}"
        );
    }

    #[test]
    fn test_empty_backend_name_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = ""
kind = "memory"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("empty backend name must fail");
        assert!(
            matches!(config_error_root(&err), ConfigError::InvalidBackendName { ref name, .. } if name.is_empty()),
            "expected InvalidBackendName for the empty name, got {err:?}"
        );
    }

    #[test]
    fn test_backend_served_kinds_absent_and_declared() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "legacy"
kind = "memory"

[[backends]]
name = "notes"
kind = "memory"
served_kinds = ["note", "event"]
"#,
        );
        let config = KhiveConfig::load(Some(&path))
            .expect("valid served-kind declarations")
            .expect("config file found");

        assert!(config.backends[0].served_kinds.is_none());
        assert_eq!(
            config.backends[1].served_kinds,
            Some(BTreeSet::from([SubstrateKind::Note, SubstrateKind::Event]))
        );
    }

    #[test]
    fn test_empty_backend_served_kinds_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "main"
kind = "memory"
served_kinds = []
"#,
        );
        let error = KhiveConfig::load(Some(&path))
            .expect_err("an explicit empty served-kind declaration must fail closed");

        assert!(matches!(
            config_error_root(&error),
            ConfigError::EmptyBackendServedKinds { name } if name == "main"
        ));
    }

    #[test]
    fn test_unknown_backend_served_kind_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "main"
kind = "memory"
served_kinds = ["asset"]
"#,
        );
        let error = KhiveConfig::load(Some(&path))
            .expect_err("served-kind declarations use a closed vocabulary");

        assert!(matches!(
            config_error_root(&error),
            ConfigError::Parse { .. }
        ));
        assert!(error.to_string().contains("unknown variant `asset`"));
    }

    #[test]
    fn test_pack_referencing_undefined_backend_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "knowledge"
kind = "memory"

[packs.kg]
backend = "nonexistent"
"#,
        );
        let err =
            KhiveConfig::load(Some(&path)).expect_err("should fail with unknown backend reference");
        assert!(
            matches!(config_error_root(&err), ConfigError::UnknownPackBackend { ref pack, ref backend, .. }
                if pack == "kg" && backend == "nonexistent"),
            "expected UnknownPackBackend for kg→nonexistent, got {err:?}"
        );
    }

    #[test]
    fn test_pack_config_without_backends_section_is_allowed() {
        let dir = tempfile::tempdir().unwrap();
        // Explicit pack routes may name the implicit main backend.
        let path = write_toml(
            &dir,
            r#"
[packs.kg]
backend = "main"
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error expected")
            .expect("file found");
        assert_eq!(cfg.backends.len(), 0);
        assert_eq!(cfg.packs.len(), 1);
    }

    #[test]
    fn test_implicit_main_rejects_unknown_pack_backend() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "[packs.comm]\nbackend = 'does-not-exist'\n");
        let error = KhiveConfig::load(Some(&path)).expect_err("unknown route must fail");
        assert!(matches!(
            config_error_root(&error),
            ConfigError::UnknownPackBackend { pack, backend, defined }
                if pack == "comm" && backend == "does-not-exist" && defined == "main"
        ));
    }

    #[test]
    fn test_backend_search_coverage_rejects_missing_substrates() {
        for (served, missing) in [
            ("'note'", vec![SubstrateKind::Entity]),
            ("'entity'", vec![SubstrateKind::Note]),
            ("'event'", vec![SubstrateKind::Note, SubstrateKind::Entity]),
        ] {
            let dir = tempfile::tempdir().unwrap();
            let path = write_toml(
                &dir,
                &format!(
                    "[[backends]]\nname = 'main'\nkind = 'memory'\nserved_kinds = [{served}]\n"
                ),
            );
            let error = KhiveConfig::load(Some(&path)).expect_err("incomplete coverage");
            assert!(
                matches!(
                    config_error_root(&error),
                    ConfigError::MissingBackendSearchKinds { kinds, defined }
                        if kinds == &missing && defined == "main"
                ),
                "unexpected coverage error: {error}"
            );
        }
    }

    #[test]
    fn test_backend_search_coverage_allows_split_substrates_and_event_only_secondary() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "main"
kind = "memory"
served_kinds = ["entity"]

[[backends]]
name = "notes"
kind = "memory"
served_kinds = ["note"]

[[backends]]
name = "events"
kind = "memory"
served_kinds = ["event"]
"#,
        );
        KhiveConfig::load(Some(&path)).expect("search coverage is the union of backends");
    }

    #[test]
    fn test_backend_cache_mb_rejected_at_validate() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "main"
kind = "memory"
cache_mb = 128
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("cache_mb must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::UnsupportedBackendField { ref name, field: "cache_mb" } if name == "main"),
            "expected UnsupportedBackendField {{ name: \"main\", field: \"cache_mb\" }}, got {err:?}"
        );
    }

    #[test]
    fn test_backend_journal_mode_rejected_at_validate() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[backends]]
name = "main"
kind = "memory"
journal_mode = "wal"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("journal_mode must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::UnsupportedBackendField { ref name, field: "journal_mode" } if name == "main"),
            "expected UnsupportedBackendField {{ name: \"main\", field: \"journal_mode\" }}, got {err:?}"
        );
    }

    // A top-level `db` key must be rejected loudly instead of silently
    // ignored as an unknown key by serde's forward-compatible default.
    #[test]
    fn test_top_level_db_rejected_at_validate() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
db = "/tmp/scratch/demo.db"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("top-level db must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::UnsupportedTopLevelDb { ref value } if value == "/tmp/scratch/demo.db"),
            "expected UnsupportedTopLevelDb {{ value: \"/tmp/scratch/demo.db\" }}, got {err:?}"
        );
    }

    #[test]
    fn gate_caller_enrollment_config_loads_for_runtime_enforcement() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[gate]
granted_actors = ["lambda:enrolled"]
grant_unattributed = false
"#,
        );

        let config = KhiveConfig::load(Some(&path))
            .expect("the supported caller-enrollment policy must parse")
            .expect("config exists");
        let gate = config.gate.expect("gate section");
        assert_eq!(gate.granted_actors, vec!["lambda:enrolled"]);
        assert!(!gate.grant_unattributed);
    }

    #[test]
    fn unknown_actor_key_fails_to_load() {
        let dir = tempfile::tempdir().unwrap();

        // Control first, in the same test: the identical table carrying only
        // supported keys must load, so the refusal below is attributable to the
        // unknown key rather than to the fixture.
        let supported = write_toml(
            &dir,
            r#"
[actor]
id = "lambda:example"
visible_namespaces = ["lambda:other"]
"#,
        );
        KhiveConfig::load(Some(&supported))
            .expect("a config using only supported [actor] keys must parse")
            .expect("config exists");

        // A `[gate]` key written one table too high. Silently discarding it
        // leaves anonymous admission at whatever it already was while the file
        // on disk says otherwise, so it has to fail startup.
        let misplaced = write_toml(
            &dir,
            r#"
[actor]
id = "lambda:example"
grant_unattributed = false
"#,
        );
        let err = KhiveConfig::load(Some(&misplaced))
            .expect_err("a [gate] key written under [actor] must fail startup");
        assert!(
            err.to_string().contains("grant_unattributed"),
            "the refusal must name the offending key, got: {err}"
        );
    }

    #[test]
    fn caller_enrollment_policy_is_enforced_at_authorization() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[actor]
id = "lambda:enrolled"

[gate]
granted_actors = ["lambda:enrolled"]
grant_unattributed = false
"#,
        );
        let mut config = KhiveConfig::load(Some(&path))
            .expect("load")
            .expect("config exists");
        let allowed = crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
        let runtime = crate::KhiveRuntime::new(allowed).expect("runtime");
        runtime
            .authorize(Namespace::local())
            .expect("listed actor is admitted");

        config.actor.id = Some("lambda:other".to_string());
        let denied = crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
        let runtime = crate::KhiveRuntime::new(denied).expect("runtime");
        assert!(matches!(
            runtime.authorize(Namespace::local()),
            Err(crate::RuntimeError::PermissionDenied { ref verb, ref reason, .. })
                if verb == "authorize" && reason == "actor is not enrolled"
        ));
    }

    #[test]
    fn grant_unattributed_controls_anonymous_authorization() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "[gate]\ngrant_unattributed = false\n");
        let mut config = KhiveConfig::load(Some(&path))
            .expect("load")
            .expect("config exists");
        let denied = crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
        let runtime = crate::KhiveRuntime::new(denied).expect("runtime");
        assert!(matches!(
            runtime.authorize(Namespace::local()),
            Err(crate::RuntimeError::PermissionDenied { ref reason, .. })
                if reason == "unattributed caller is not enrolled"
        ));

        config.gate.as_mut().expect("gate").grant_unattributed = true;
        let allowed = crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
        crate::KhiveRuntime::new(allowed)
            .expect("runtime")
            .authorize(Namespace::local())
            .expect("anonymous caller is explicitly admitted");
    }

    #[test]
    fn empty_gate_table_is_explicit_deny_all_policy() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "[gate]\n");
        let config = KhiveConfig::load(Some(&path))
            .expect("empty gate table parses")
            .expect("config exists");
        assert_eq!(config.gate, Some(GateSectionConfig::default()));
        let runtime_config =
            crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
        let runtime = crate::KhiveRuntime::new(runtime_config).expect("runtime");
        assert!(matches!(
            runtime.authorize(Namespace::local()),
            Err(crate::RuntimeError::PermissionDenied { .. })
        ));
    }

    #[test]
    fn unknown_gate_key_fails_startup() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "[gate]\ngranted_actor = [\"lambda:typo\"]\n");
        let err = KhiveConfig::load(Some(&path)).expect_err("unknown gate key must fail");
        assert!(matches!(err, ConfigError::Parse { .. }));
        assert!(err.to_string().contains("unknown field"), "{err}");
    }

    #[test]
    fn write_denials_survive_both_runtime_config_paths() {
        let dir = tempfile::tempdir().unwrap();
        for engines in [
            "",
            "\n[[engines]]\nname = 'main'\nmodel = 'all-minilm-l6-v2'\ndefault = true\n",
        ] {
            let path = write_toml(&dir, &format!(
                "[actor]\nid='seat:duty'\n[gate]\ngranted_actors=['seat:duty','seat:writer']\ndeny_writes_for=['*:duty']\n{engines}"
            ));
            let config = KhiveConfig::load(Some(&path)).unwrap().unwrap();
            let runtime =
                crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
            for (actor, verb, allowed) in [
                ("seat:duty", "list", true),
                ("seat:duty", "create", false),
                ("seat:writer", "create", true),
                ("unlisted", "list", false),
            ] {
                let req = crate::GateRequest::new(
                    crate::ActorRef::new("actor", actor),
                    Namespace::local(),
                    verb,
                    serde_json::Value::Null,
                );
                assert_eq!(
                    runtime.gate.check(&req).unwrap().is_allow(),
                    allowed,
                    "{actor} {verb}"
                );
            }
        }
    }

    #[test]
    fn invalid_write_denials_fail_config_load_and_direct_config_fails_closed() {
        let dir = tempfile::tempdir().unwrap();
        for value in [
            "['']".to_string(),
            "['   ']".into(),
            format!("['{}']", "é".repeat(129)),
            format!("[{}]", vec!["'*'"; 257].join(",")),
        ] {
            let path = write_toml(&dir, &format!("[gate]\ndeny_writes_for={value}\n"));
            let error = KhiveConfig::load(Some(&path)).unwrap_err();
            assert!(
                matches!(
                    config_error_root(&error),
                    ConfigError::InvalidWriteDenyPatterns { .. }
                ),
                "{error}"
            );
        }
        for field in ["deny_write_for=['*']", "deny_writes_for=[17]"] {
            let path = write_toml(&dir, &format!("[gate]\n{field}\n"));
            assert!(KhiveConfig::load(Some(&path)).is_err());
        }
        let path = write_toml(
            &dir,
            "[gate]\ngranted_actors=['writer']\ndeny_writes_for=['用户@*/[?]']\n",
        );
        let mut config = KhiveConfig::load(Some(&path)).unwrap().unwrap();
        config.gate.as_mut().unwrap().deny_writes_for = vec![String::new()];
        let runtime = crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
        let req = crate::GateRequest::new(
            crate::ActorRef::new("actor", "writer"),
            Namespace::local(),
            "list",
            serde_json::Value::Null,
        );
        assert!(matches!(
            runtime.gate.check(&req),
            Err(crate::GateError::Policy(_))
        ));
    }

    #[test]
    fn absent_gate_preserves_the_programmatic_gate() {
        let mut base = in_memory_runtime_config();
        base.gate = std::sync::Arc::new(crate::CallerEnrollmentGate::new(vec![], false));
        let configured =
            crate::runtime_config_from_khive_config(&KhiveConfig::default(), base.clone());
        assert!(std::sync::Arc::ptr_eq(&base.gate, &configured.gate));
    }

    #[test]
    fn invalid_granted_actor_fails_startup() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "[gate]\ngranted_actors = [\"not valid\"]\n");
        let err = KhiveConfig::load(Some(&path)).expect_err("invalid actor id must fail");
        assert!(matches!(
            config_error_root(&err),
            ConfigError::InvalidGrantedActorId { id, .. } if id == "not valid"
        ));
    }

    #[test]
    fn unrelated_unknown_top_level_sections_remain_forward_compatible() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "[future_feature]\nenabled = true\n");
        KhiveConfig::load(Some(&path))
            .expect("unrelated future config stays forward compatible")
            .expect("config exists");
    }

    #[test]
    fn brain_fleet_readers_default_to_empty() {
        assert!(KhiveConfig::default().brain.fleet_readers.is_empty());
        assert!(in_memory_runtime_config().brain.fleet_readers.is_empty());

        let dir = tempfile::tempdir().unwrap();
        for engines in [
            "",
            "[[engines]]\nname = \"primary\"\nmodel = \"all-minilm-l6-v2\"\ndefault = true\n",
        ] {
            for brain in ["", "[brain]\n", "[brain]\nfleet_readers = []\n"] {
                let path = write_toml(&dir, &format!("{engines}\n{brain}"));
                let config = KhiveConfig::load(Some(&path))
                    .expect("load")
                    .expect("config exists");
                assert!(config.brain.fleet_readers.is_empty());

                let mut base = in_memory_runtime_config();
                base.brain.fleet_readers = vec!["lambda:previous".to_string()];
                let resolved = crate::runtime_config_from_khive_config(&config, base);
                assert!(resolved.brain.fleet_readers.is_empty());
            }
        }
    }

    #[test]
    fn brain_fleet_readers_parse_and_resolve_with_or_without_engines() {
        let dir = tempfile::tempdir().unwrap();
        for engines in [
            "",
            "[[engines]]\nname = \"primary\"\nmodel = \"all-minilm-l6-v2\"\ndefault = true\n",
        ] {
            let path = write_toml(
                &dir,
                &format!(
                    "{engines}\n[brain]\nfleet_readers = [\"lambda:reader\", \"lambda:auditor\"]\n"
                ),
            );
            let config = KhiveConfig::load(Some(&path))
                .expect("load")
                .expect("config exists");
            assert_eq!(
                config.brain.fleet_readers,
                vec!["lambda:reader", "lambda:auditor"]
            );

            let mut base = in_memory_runtime_config();
            base.brain.fleet_readers = vec!["lambda:previous".to_string()];
            let resolved = crate::runtime_config_from_khive_config(&config, base);
            assert_eq!(
                resolved.brain.fleet_readers,
                vec!["lambda:reader", "lambda:auditor"]
            );
        }
    }

    #[test]
    fn unknown_brain_key_fails_startup() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "[brain]\nfleet_reader = [\"lambda:reader\"]\n");
        let err = KhiveConfig::load(Some(&path)).expect_err("unknown brain key must fail");
        assert!(matches!(err, ConfigError::Parse { .. }));
        assert!(err.to_string().contains("unknown field"), "{err}");
    }

    #[test]
    fn telemetry_missing_default_stays_absent_with_or_without_engines() {
        use crate::{TelemetryCarrier, TelemetryConfig};

        assert_eq!(KhiveConfig::default().telemetry, TelemetryConfig::default());
        assert_eq!(
            in_memory_runtime_config().telemetry,
            TelemetryConfig::default()
        );
        let dir = tempfile::tempdir().unwrap();
        for engines in [
            "",
            "[[engines]]\nname = \"primary\"\nmodel = \"all-minilm-l6-v2\"\ndefault = true\n",
        ] {
            for telemetry in ["", "[telemetry]\n"] {
                let path = write_toml(&dir, &format!("{engines}\n{telemetry}"));
                let config = KhiveConfig::load(Some(&path)).unwrap().unwrap();
                let mut base = in_memory_runtime_config();
                base.telemetry.stream = "previous".to_string();
                base.telemetry.default_carrier = Some(TelemetryCarrier::Durable);
                let resolved = crate::runtime_config_from_khive_config(&config, base);
                assert_eq!(resolved.telemetry, TelemetryConfig::default());
                assert_eq!(resolved.telemetry.stream, "telemetry");
                assert_eq!(resolved.telemetry.default_carrier, None);
                let error = resolved
                    .telemetry
                    .validate_activation()
                    .expect_err("activating telemetry requires the declared default");
                assert!(error.to_string().contains("telemetry.default_carrier"));
            }
        }
    }

    #[test]
    fn telemetry_table_loads_and_resolves_with_or_without_engines() {
        use crate::{TelemetryCarrier, TelemetryFailurePosture};

        let dir = tempfile::tempdir().unwrap();
        for engines in [
            "",
            "[[engines]]\nname = \"primary\"\nmodel = \"all-minilm-l6-v2\"\ndefault = true\n",
        ] {
            let path = write_toml(
                &dir,
                &format!(
                    r#"{engines}
[telemetry]
stream = "operations"
default_carrier = "durable"
[[telemetry.channels]]
kinds = ["run.started", "run.completed"]
carrier = "durable"
failure_posture = "gap"
[[telemetry.channels]]
kinds = ["turn.delta", "*.heartbeat"]
carrier = "ephemeral"
failure_posture = "stop"
"#
                ),
            );
            let config = KhiveConfig::load(Some(&path)).unwrap().unwrap();
            assert_eq!(config.telemetry.channels.len(), 2);
            let resolved =
                crate::runtime_config_from_khive_config(&config, in_memory_runtime_config());
            assert_eq!(resolved.telemetry, config.telemetry);
            assert_eq!(resolved.telemetry.stream, "operations");
            for kind in ["run.started", "run.completed"] {
                let policy = resolved.telemetry.policy_for_kind(kind).unwrap();
                assert_eq!(policy.carrier, TelemetryCarrier::Durable);
                assert_eq!(policy.failure_posture, TelemetryFailurePosture::Gap);
            }
            for kind in ["turn.delta", "run.heartbeat", "turn.child.heartbeat"] {
                let policy = resolved.telemetry.policy_for_kind(kind).unwrap();
                assert_eq!(policy.carrier, TelemetryCarrier::Ephemeral);
                assert_eq!(policy.failure_posture, TelemetryFailurePosture::Stop);
            }
            for kind in [
                "unclassified",
                "heartbeat",
                "run.notheartbeat",
                "run.heartbeat.extra",
            ] {
                let policy = resolved.telemetry.policy_for_kind(kind).unwrap();
                assert_eq!(policy.carrier, TelemetryCarrier::Durable);
                assert_eq!(policy.failure_posture, TelemetryFailurePosture::Stop);
            }
        }
    }

    #[test]
    fn telemetry_invalid_policy_values_name_the_channel() {
        let dir = tempfile::tempdir().unwrap();
        for (carrier, posture, field, value) in [
            ("disk", "stop", "carrier", "disk"),
            ("Durable", "stop", "carrier", "Durable"),
            ("durable", "ignore", "failure_posture", "ignore"),
            ("durable", "Stop", "failure_posture", "Stop"),
        ] {
            let path = write_toml(
                &dir,
                &format!(
                    r#"[[telemetry.channels]]
kinds = ["first"]
carrier = "ephemeral"
failure_posture = "gap"
[[telemetry.channels]]
kinds = ["second"]
carrier = "{carrier}"
failure_posture = "{posture}"
"#
                ),
            );
            let error = KhiveConfig::load(Some(&path)).expect_err("invalid policy must refuse");
            let message = error.to_string();
            for expected in ["telemetry.channels[1]", field, value] {
                assert!(message.contains(expected), "{message}");
            }
        }
        let path = write_toml(&dir, "[telemetry]\ndefault_carrier = \"disk\"\n");
        let error = KhiveConfig::load(Some(&path)).expect_err("unknown fallback must refuse");
        assert!(
            error.to_string().contains("telemetry.default_carrier"),
            "{error}"
        );
    }

    #[test]
    fn telemetry_overlapping_channels_name_both_entries() {
        let dir = tempfile::tempdir().unwrap();
        for (first, second) in [
            ("run.started", "run.started"),
            ("run.heartbeat", "*.heartbeat"),
            ("*.heartbeat", "run.heartbeat"),
            ("*.heartbeat", "*.heartbeat"),
            ("*.heartbeat", "*.child.heartbeat"),
            ("*.child.heartbeat", "*.heartbeat"),
        ] {
            let path = write_toml(
                &dir,
                &format!(
                    r#"[[telemetry.channels]]
kinds = ["{first}"]
carrier = "ephemeral"
failure_posture = "gap"
[[telemetry.channels]]
kinds = ["{second}"]
carrier = "durable"
failure_posture = "stop"
"#
                ),
            );
            let error = KhiveConfig::load(Some(&path)).expect_err("overlap must refuse");
            let message = error.to_string();
            for expected in [
                "telemetry.channels[1]",
                "telemetry.channels[0]",
                first,
                second,
            ] {
                assert!(message.contains(expected), "{message}");
            }
        }
    }

    #[test]
    fn telemetry_empty_and_invalid_kind_patterns_name_the_channel() {
        let dir = tempfile::tempdir().unwrap();
        for kinds in [
            "[]",
            "[\"\"]",
            "[\" \"]",
            "[\"two names\"]",
            "[\"*\"]",
            "[\"run.*\"]",
            "[\"*.\"]",
            "[\"**.heartbeat\"]",
            "[\"*.heart*beat\"]",
        ] {
            let path = write_toml(
                &dir,
                &format!(
                    r#"[[telemetry.channels]]
kinds = ["first"]
carrier = "ephemeral"
failure_posture = "gap"
[[telemetry.channels]]
kinds = {kinds}
carrier = "durable"
failure_posture = "stop"
"#
                ),
            );
            let error = KhiveConfig::load(Some(&path)).expect_err("invalid kinds must refuse");
            assert!(
                error.to_string().contains("telemetry.channels[1]"),
                "{error}"
            );
        }
    }

    #[test]
    fn telemetry_tables_reject_unknown_keys() {
        let dir = tempfile::tempdir().unwrap();
        for content in [
            "[telemetry]\ndefault_carrrier = \"durable\"\n",
            "[telemetry.ring]\ncapacity = 4096\n",
            "[[telemetry.channels]]\nkinds = [\"run\"]\ncarrier = \"durable\"\nfailure_posture = \"stop\"\ncarrrier = \"ephemeral\"\n",
        ] {
            let path = write_toml(&dir, content);
            let error = KhiveConfig::load(Some(&path)).expect_err("unknown key must refuse");
            assert!(error.to_string().contains("unknown field"), "{error}");
        }
    }

    // ── [git_write] section (ADR-108 Amendment) ─────────────────────────────

    // No [git_write] section at all -> empty allowlist, valid config.
    #[test]
    fn test_no_git_write_section_is_valid_and_empty() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "# no git_write section\n");
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert!(cfg.git_write.allowed.is_empty());
    }

    fn write_git_program_config(dir: &tempfile::TempDir, program: &Path) -> PathBuf {
        let program = toml::Value::String(program.to_str().unwrap().to_string());
        write_toml(dir, &format!("[git_write]\nprogram = {program}\n"))
    }

    #[test]
    fn git_program_absent_preserves_path_default() {
        let dir = tempfile::tempdir().unwrap();
        for content in ["# no git_write section\n", "[git_write]\n"] {
            let path = write_toml(&dir, content);
            let cfg = KhiveConfig::load(Some(&path)).unwrap().unwrap();
            assert!(cfg.git_write.program.is_none());
            assert_eq!(cfg.git_write.git_program(), Path::new("git"));
        }
        assert!(GitWriteSectionConfig::default().program.is_none());
        assert_eq!(
            GitWriteSectionConfig::default().git_program(),
            Path::new("git")
        );
    }

    #[cfg(any(unix, windows))]
    #[test]
    fn git_program_absolute_executable_loads() {
        let dir = tempfile::tempdir().unwrap();
        let program = std::env::current_exe().unwrap();
        let path = write_git_program_config(&dir, &program);
        let cfg = KhiveConfig::load(Some(&path)).unwrap().unwrap();
        assert_eq!(cfg.git_write.program.as_deref(), Some(program.as_path()));
        assert_eq!(cfg.git_write.git_program(), program);
    }

    #[test]
    fn git_program_relative_path_is_rejected_at_load() {
        let dir = tempfile::tempdir().unwrap();
        for program in ["git", "relative/git"] {
            let path = write_git_program_config(&dir, Path::new(program));
            let error = KhiveConfig::load(Some(&path)).expect_err("relative program must fail");
            assert!(
                matches!(config_error_root(&error), ConfigError::InvalidGitWriteConfig { key, reason }
                    if key == "git_write.program" && reason == "must be absolute"),
                "unexpected error: {error}"
            );
            assert!(error.to_string().contains("git_write.program"));
        }
    }

    #[test]
    fn git_program_missing_file_is_rejected_at_load() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_git_program_config(&dir, &dir.path().join("missing-git"));
        let error = KhiveConfig::load(Some(&path)).expect_err("missing program must fail");
        assert!(
            matches!(config_error_root(&error), ConfigError::InvalidGitWriteConfig { key, reason }
                if key == "git_write.program" && reason == "does not exist"),
            "unexpected error: {error}"
        );
        assert!(error.to_string().contains("git_write.program"));
    }

    #[test]
    fn git_program_nonexecutable_file_is_rejected_at_load() {
        let dir = tempfile::tempdir().unwrap();
        let program = dir.path().join("git.txt");
        std::fs::write(&program, "not executable\n").unwrap();
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            std::fs::set_permissions(&program, std::fs::Permissions::from_mode(0o600)).unwrap();
        }
        let path = write_git_program_config(&dir, &program);
        let error = KhiveConfig::load(Some(&path)).expect_err("nonexecutable program must fail");
        assert!(
            matches!(config_error_root(&error), ConfigError::InvalidGitWriteConfig { key, reason }
                if key == "git_write.program" && reason == "is not executable"),
            "unexpected error: {error}"
        );
        assert!(error.to_string().contains("git_write.program"));
    }

    #[test]
    fn git_program_directory_is_rejected_at_load() {
        let dir = tempfile::tempdir().unwrap();
        let program = dir.path().join("git.exe");
        std::fs::create_dir(&program).unwrap();
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            std::fs::set_permissions(&program, std::fs::Permissions::from_mode(0o755)).unwrap();
        }
        let path = write_git_program_config(&dir, &program);
        let error = KhiveConfig::load(Some(&path)).expect_err("directory program must fail");
        assert!(
            matches!(config_error_root(&error), ConfigError::InvalidGitWriteConfig { key, reason }
                if key == "git_write.program" && reason == "is not executable"),
            "unexpected error: {error}"
        );
        assert!(error.to_string().contains("git_write.program"));
    }

    // A well-formed [[git_write.allowed]] entry parses correctly.
    #[test]
    fn test_git_write_entry_parses() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[git_write.allowed]]
repo = "/abs/path/repo"
branches = ["feat/*", "fix/*"]
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert_eq!(cfg.git_write.allowed.len(), 1);
        assert_eq!(cfg.git_write.allowed[0].repo, "/abs/path/repo");
        assert_eq!(
            cfg.git_write.allowed[0].branches,
            vec!["feat/*".to_string(), "fix/*".to_string()]
        );
    }

    // A relative repo path is rejected at validate() time.
    #[test]
    fn test_git_write_relative_repo_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[git_write.allowed]]
repo = "relative/path"
branches = ["main"]
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("relative repo must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::InvalidGitWriteEntry { ref repo, .. } if repo == "relative/path"),
            "expected InvalidGitWriteEntry, got {err:?}"
        );
    }

    // ADR-108: a branch pattern with more than one `*` is rejected at
    // validate() time -- the ADR authorizes exact-name or single-wildcard
    // patterns only.
    #[test]
    fn test_git_write_multi_star_branch_pattern_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[git_write.allowed]]
repo = "/abs/path"
branches = ["**"]
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("** must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::InvalidGitWriteEntry { ref repo, .. } if repo == "/abs/path"),
            "expected InvalidGitWriteEntry, got {err:?}"
        );

        let dir2 = tempfile::tempdir().unwrap();
        let path2 = write_toml(
            &dir2,
            r#"
[[git_write.allowed]]
repo = "/abs/path"
branches = ["rel-*-*-final"]
"#,
        );
        let err2 = KhiveConfig::load(Some(&path2)).expect_err("rel-*-*-final must be rejected");
        assert!(
            matches!(
                config_error_root(&err2),
                ConfigError::InvalidGitWriteEntry { .. }
            ),
            "expected InvalidGitWriteEntry, got {err2:?}"
        );
    }

    // Single-wildcard patterns remain accepted.
    #[test]
    fn test_git_write_single_star_branch_pattern_accepted() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[git_write.allowed]]
repo = "/abs/path"
branches = ["a*b", "main"]
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert_eq!(cfg.git_write.allowed[0].branches, vec!["a*b", "main"]);
    }

    // An entry with an empty branches list is rejected at validate() time --
    // it would otherwise silently allowlist a repo for no branch at all.
    #[test]
    fn test_git_write_empty_branches_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[[git_write.allowed]]
repo = "/abs/path"
branches = []
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("empty branches must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::InvalidGitWriteEntry { ref repo, .. } if repo == "/abs/path"),
            "expected InvalidGitWriteEntry, got {err:?}"
        );
    }

    #[test]
    fn git_actor_mapping_and_resolver_defaults_parse_without_resolution() {
        let cfg: KhiveConfig = toml::from_str(
            r#"
[git_write.actors."lambda:example"]
name = "Example"
email = "example@example.invalid"
credential_ref = "example-reference"
platform_identity = "example-login"
"#,
        )
        .unwrap();
        if cfg!(unix) {
            cfg.validate().unwrap();
        } else {
            assert!(cfg.validate().is_err());
        }
        let identity = &cfg.git_write.actors["lambda:example"];
        assert_eq!(identity.name, "Example");
        assert_eq!(identity.credential_ref, "example-reference");
        assert_eq!(
            cfg.git_write.credential_resolver,
            GitWriteSectionConfig::default().credential_resolver
        );
    }

    #[test]
    fn git_resolver_accepts_only_absolute_argv_with_ref_template() {
        for argv in [
            vec![],
            vec!["relative-resolver", "{ref}"],
            vec!["/bin/sh", "-c", "{ref}"],
            vec!["/usr/bin/env", "sh", "{ref}"],
            vec!["/absolute/resolver", "{token}"],
            vec!["/absolute/resolver", "--service={ref}"],
            vec!["/absolute/resolver"],
            vec!["/absolute/resolver", "{ref}", "bad\0arg"],
        ] {
            let config = GitWriteSectionConfig {
                credential_resolver: argv.into_iter().map(str::to_string).collect(),
                ..Default::default()
            };
            assert!(matches!(
                config.validate_dev_loop(),
                Err(ConfigError::InvalidGitWriteConfig { key, .. }) if key == "credential_resolver"
            ));
        }
        let config = GitWriteSectionConfig {
            credential_resolver: vec![
                std::env::temp_dir()
                    .join("not-installed-yet/resolver")
                    .to_string_lossy()
                    .into_owned(),
                "--reference".to_string(),
                "{ref}".to_string(),
            ],
            ..Default::default()
        };
        config.validate_dev_loop().unwrap();
    }

    #[test]
    fn git_actor_mapping_rejects_invalid_identity_and_unknown_fields() {
        let actor = GitWriteActorConfig {
            name: "Example".to_string(),
            email: "example@example.invalid".to_string(),
            credential_ref: "example-reference".to_string(),
            platform_identity: "example-login".to_string(),
        };
        for field in ["name", "email", "credential_ref", "platform_identity"] {
            let mut invalid = actor.clone();
            match field {
                "name" => invalid.name.clear(),
                "email" => invalid.email = "bad\nemail".to_string(),
                "credential_ref" => invalid.credential_ref.clear(),
                "platform_identity" => invalid.platform_identity.clear(),
                _ => unreachable!(),
            }
            let config = GitWriteSectionConfig {
                actors: BTreeMap::from([("example".to_string(), invalid)]),
                ..Default::default()
            };
            assert!(config.validate_dev_loop().is_err());
        }
        assert!(toml::from_str::<GitWriteActorConfig>(
            r#"name = "Example"
email = "example@example.invalid"
credential_ref = "reference"
platform_identity = "login"
credential = "not-an-accepted-field""#
        )
        .is_err());
    }

    #[test]
    fn git_repository_merge_refusals_accept_only_the_two_named_entries() {
        let row = |refusals: &[&str]| GitWriteSectionConfig {
            repositories: BTreeMap::from([(
                "/repo".to_string(),
                GitWriteRepositoryConfig {
                    remote: "https://github.com/example/repo".to_string(),
                    slug: "example/repo".to_string(),
                    visibility: "private".to_string(),
                    merge_refusals: refusals.iter().map(|entry| entry.to_string()).collect(),
                },
            )]),
            ..Default::default()
        };
        for refusals in [
            &[][..],
            &["opener"][..],
            &["last_pusher"][..],
            &["opener", "last_pusher"][..],
        ] {
            row(refusals).validate_dev_loop().unwrap();
        }
        for refusals in [
            &["author"][..],
            &["Opener"][..],
            &["opener", "opener"][..],
            &["last_pusher", "opener", "last_pusher"][..],
        ] {
            assert!(matches!(
                row(refusals).validate_dev_loop(),
                Err(ConfigError::InvalidGitWriteConfig { key, .. })
                    if key == "repositories./repo.merge_refusals"
            ));
        }
        let parsed: GitWriteRepositoryConfig = toml::from_str(
            r#"remote = "https://github.com/example/repo"
slug = "example/repo"
visibility = "private""#,
        )
        .unwrap();
        assert!(parsed.merge_refusals.is_empty());
        assert!(toml::from_str::<GitWriteRepositoryConfig>(
            r#"remote = "https://github.com/example/repo"
slug = "example/repo"
visibility = "private"
merge_refusal = ["opener"]"#
        )
        .is_err());
    }

    #[test]
    fn git_contract_faults_are_feature_gated_before_empty_engines_return() {
        let cfg = KhiveConfig {
            git_write: GitWriteSectionConfig {
                contract_faults: true,
                ..Default::default()
            },
            ..Default::default()
        };
        if cfg!(feature = "contract-faults") {
            cfg.validate().unwrap();
        } else {
            let error = cfg.validate().unwrap_err();
            assert!(matches!(error, ConfigError::InvalidGitWriteConfig { .. }));
            assert!(error.to_string().contains("contract-faults"));
        }
    }

    #[test]
    fn git_unmapped_legacy_default_remains_valid_on_every_platform() {
        GitWriteSectionConfig::default()
            .validate_dev_loop()
            .unwrap();
        let config = GitWriteSectionConfig {
            credential_resolver: vec!["relative-resolver".to_string(), "{ref}".to_string()],
            ..Default::default()
        };
        assert!(config.validate_dev_loop().is_err());
    }

    #[test]
    fn git_fault_selectors_require_opt_in() {
        let config = GitWriteSectionConfig {
            fault: Some("git.push:reply-lost-after-effect".to_string()),
            ..Default::default()
        };
        assert!(matches!(
            config.validate_dev_loop(),
            Err(ConfigError::InvalidGitWriteConfig { key, .. }) if key == "fault"
        ));
    }

    // ── [storage.blob] section (ADR-111 Amendment 2) ─────────────────────────

    // No [storage] section at all -> fs default, existing configurations
    // keep behaving exactly as they did before this section existed.
    #[test]
    fn test_no_storage_section_defaults_to_fs() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "# no storage section\n");
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert!(cfg.storage.blob.is_none());
    }

    #[test]
    fn test_storage_blob_fs_selection_parses() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[storage.blob]
backend = "fs"
root = "/var/lib/khive/blobs"
floor_bytes = 100000000000
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        match cfg.storage.blob {
            Some(BlobConfig::Fs { root, floor_bytes }) => {
                assert_eq!(root.as_deref(), Some("/var/lib/khive/blobs"));
                assert_eq!(floor_bytes, Some(100_000_000_000));
            }
            other => panic!("expected BlobConfig::Fs, got {other:?}"),
        }
    }

    #[test]
    fn test_storage_blob_s3_selection_parses() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[storage.blob]
backend = "s3"
bucket = "khive-blobs"
region = "us-east-1"
endpoint = "https://objects.example.invalid"
prefix = "blobs"
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        match cfg.storage.blob {
            Some(BlobConfig::S3 {
                bucket,
                region,
                endpoint,
                prefix,
                allow_http,
            }) => {
                assert_eq!(bucket, "khive-blobs");
                assert_eq!(region, "us-east-1");
                assert_eq!(endpoint.as_deref(), Some("https://objects.example.invalid"));
                assert_eq!(prefix.as_deref(), Some("blobs"));
                assert_eq!(allow_http, None);
            }
            other => panic!("expected BlobConfig::S3, got {other:?}"),
        }
    }

    // An unknown field under [storage.blob] must be a startup error, not
    // silently ignored -- unlike the rest of KhiveConfig, this section is
    // strict (deny_unknown_fields).
    #[test]
    fn test_storage_blob_unknown_field_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[storage.blob]
backend = "fs"
made_up_field = "x"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("unknown field must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::Parse { .. }),
            "got {err:?}"
        );
    }

    // An s3-only field (bucket) under backend = "fs" must be rejected: the
    // internally tagged enum's Fs variant doesn't declare it, so it is an
    // unknown field for that variant.
    #[test]
    fn test_storage_blob_other_backend_field_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[storage.blob]
backend = "fs"
bucket = "khive-blobs"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("s3 field under fs must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::Parse { .. }),
            "got {err:?}"
        );
    }

    // Credentials are never accepted in TOML (ADR-111 Amendment 2): an
    // access-key field under backend = "s3" is unknown to that variant and
    // must be rejected, the same way an other-backend field is.
    #[test]
    fn test_storage_blob_credential_field_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[storage.blob]
backend = "s3"
bucket = "khive-blobs"
region = "us-east-1"
access_key_id = "AKIAEXAMPLE"
"#,
        );
        let err = KhiveConfig::load(Some(&path))
            .expect_err("a credential field in TOML must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::Parse { .. }),
            "got {err:?}"
        );
    }

    // An unrecognized backend value is rejected by the internally tagged
    // enum's own tag matching, same mechanism as an unknown field.
    #[test]
    fn test_storage_blob_unknown_backend_value_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[storage.blob]
backend = "gcs"
"#,
        );
        let err = KhiveConfig::load(Some(&path)).expect_err("unknown backend must be rejected");
        assert!(
            matches!(config_error_root(&err), ConfigError::Parse { .. }),
            "got {err:?}"
        );
    }

    // ── [display] section (ADR-169) ──────────────────────────────────────────

    // No [display] section at all -> None, resolved to the host zone downstream.
    #[test]
    fn test_no_display_section_defaults_to_none() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(&dir, "# no display section\n");
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert!(cfg.display.timezone.is_none());
    }

    #[test]
    fn test_display_timezone_valid_iana_name_parses() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[display]
timezone = "America/New_York"
"#,
        );
        let cfg = KhiveConfig::load(Some(&path))
            .expect("no error")
            .expect("file found");
        assert_eq!(cfg.display.timezone.as_deref(), Some("America/New_York"));
    }

    #[test]
    fn test_display_timezone_unrecognized_name_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[display]
timezone = "Mars/Olympus_Mons"
"#,
        );
        let err = KhiveConfig::load(Some(&path))
            .expect_err("an unrecognized IANA zone name must fail at load, not silently fall back");
        assert!(
            matches!(config_error_root(&err), ConfigError::InvalidDisplayTimezone { ref timezone } if timezone == "Mars/Olympus_Mons"),
            "expected InvalidDisplayTimezone, got {err:?}"
        );
    }

    #[test]
    fn test_display_timezone_empty_string_rejected() {
        let dir = tempfile::tempdir().unwrap();
        let path = write_toml(
            &dir,
            r#"
[display]
timezone = ""
"#,
        );
        let err =
            KhiveConfig::load(Some(&path)).expect_err("an empty timezone string must be rejected");
        assert!(
            matches!(
                config_error_root(&err),
                ConfigError::InvalidDisplayTimezone { .. }
            ),
            "expected InvalidDisplayTimezone, got {err:?}"
        );
    }
    include!("engine_config_backend_batch_tests.rs");
}