kranz_engine/

sandbox.rs

//! OS sandbox profile/argv generation — Tier 2 filesystem/network containment.
//! See docs/scoping/worker-sandboxing.md tier 2.
//!
//! macOS uses Seatbelt (`sandbox-exec`) for filesystem isolation. Seatbelt
//! cannot express hostname egress allowlists (it accepts only `*`/`localhost`
//! network hosts), so `fs+net` on macOS restricts outbound TCP to loopback
//! and the run routes through the userspace filtering egress proxy
//! (`crate::egress_proxy`), which enforces the per-host allowlist at CONNECT
//! time. Linux uses bubblewrap for filesystem isolation; `fs+net` fails closed
//! with `--unshare-net` because bwrap alone cannot express a hostname egress
//! allowlist (and its netns cannot reach a host proxy — out of scope for v1).
//!
//! Write scope (P1, ticket sandbox-writable-scope): a session may write only
//! its working directory, its per-session private scratch root
//! (`SandboxInputs::tmpdir` — NOT the shared system temp root, which would
//! expose every sibling mission's worktrees and merge scratch), and
//! operator-declared `extraWrite` paths. The mission dir is never
//! worker-writable; its engine-owned metadata (audit log, state snapshot,
//! control inbox, transcripts) is additionally denied/masked so it stays
//! read-only even in checkout mode, where the writable `session_cwd` is an
//! ancestor of the mission dir.
//!
//! Mandatory validator containment (ticket `validator-mandatory-containment`):
//! VALIDATOR sessions are the one class wrapped regardless of
//! `sandbox.enforce` — the validator is the adversarial reader the whole
//! gate rests on, so its isolation cannot be operator-opt-in.
//! [`resolve_validator_containment`] resolves the posture: the role's own
//! enforced sandbox plus the real-checkout read-deny set when enforcement
//! is configured, the mandatory `fs`-tier wrap when it is not, and — where
//! the platform or the selected backend cannot contain — a FAIL-CLOSED
//! refusal by default (ticket `validator-containment-degrade-fail-closed`,
//! 14th-pass review: the loud degrade reopens the modify→use→restore path,
//! so it is now the explicit opt-in `validatorAllowUncontainedDegrade`, never
//! the default).
//! The read-deny set ([`validator_read_deny_entries`]) closes the broad
//! read allow over the real checkout's source tree — the snapshot
//! worktree is the sole writable root and the only tree the validator can
//! read — keeping the narrow `.git`/`.kranz` carve-outs the inspection
//! legitimately needs.

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

/// Default egress needed by Claude/Anthropic sessions under `fs+net`.
pub const DEFAULT_EGRESS: &[&str] = &["api.anthropic.com:443", "*.anthropic.com:443"];

/// Inputs used to build a session sandbox.
#[derive(Debug, Clone)]
pub struct SandboxInputs {
    pub enforce: crate::types::SandboxEnforce,
    pub session_cwd: PathBuf,
    pub mission_dir: PathBuf,
    /// The session-PRIVATE scratch root — the only TMPDIR-side path the
    /// session may write (the cleared child env points `HOME`/`TMPDIR`
    /// under it; see `crate::agent_env`). NOT the shared system temp root:
    /// allowing all of `TMPDIR` made every sibling mission's worktree and
    /// merge scratch worker-writable (P1, ticket sandbox-writable-scope).
    /// `build_inputs` defaults it to the mission's gitignored probe scratch;
    /// the runner overrides it per session with
    /// `crate::backend_claude::scratch_home_root(session_id)`.
    pub tmpdir: PathBuf,
    pub extra_write: Vec<PathBuf>,
    pub egress: Vec<String>,
    /// Mandatory validator containment (ticket
    /// `validator-mandatory-containment`): the REAL checkout roots a
    /// VALIDATOR session must not read — the checkout the snapshot was taken
    /// from, plus the primary checkout when worktree mode separates them.
    /// Empty for every non-validator session (workers, orchestrator turns)
    /// and for engine-run gates: those legitimately work in the real tree,
    /// and an empty set keeps the generated profile/argv byte-identical to
    /// the pre-containment shape. The validator's own snapshot worktree is
    /// never in this set — it lives under the mission dir, which the
    /// read-deny carve-outs (`<root>/.git`, `<root>/.kranz`) deliberately
    /// keep reachable; see [`validator_read_deny_entries`].
    pub validator_read_deny_roots: Vec<PathBuf>,
}

/// Concrete OS sandbox backend selected for this session.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SandboxBackend {
    Seatbelt,
    Bubblewrap,
    /// Stable Win32 AppContainer profile + path-specific SID ACLs. The
    /// hostile child is created suspended and Job-owned before resume.
    AppContainer,
    /// Tier-3: run the session inside a container (see
    /// [`crate::sandbox_container`]); `ResolvedSandbox::container` is `Some`.
    Container,
}

/// How a role's `enforce` setting maps onto the current platform.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SandboxDecision {
    /// Enforcement is off; no sandbox is attached.
    Off,
    /// Enforcement is requested and the platform supports it.
    Enforce(SandboxBackend),
    /// Enforcement is requested but the platform can't honor it; run-level
    /// callers must refuse rather than proceed unsandboxed.
    UnsupportedWarn,
}

fn enforce_label(enforce: crate::types::SandboxEnforce) -> &'static str {
    match enforce {
        crate::types::SandboxEnforce::Off => "off",
        crate::types::SandboxEnforce::Fs => "fs",
        crate::types::SandboxEnforce::FsNet => "fs+net",
    }
}

/// Pure decision fn: given a role's `enforce` setting and the target OS
/// (`std::env::consts::OS`-shaped string), decide whether the session gets an
/// enforced sandbox. Parameterized on `target_os` so it is testable
/// cross-platform.
pub fn platform_support(enforce: crate::types::SandboxEnforce, target_os: &str) -> SandboxDecision {
    match enforce {
        crate::types::SandboxEnforce::Off => SandboxDecision::Off,
        crate::types::SandboxEnforce::Fs if target_os == "macos" => {
            SandboxDecision::Enforce(SandboxBackend::Seatbelt)
        }
        crate::types::SandboxEnforce::FsNet if target_os == "macos" => {
            // Seatbelt's loopback-only egress profile plus the egress proxy's
            // per-host allowlist (crate::egress_proxy): the hostname rules the
            // SBPL cannot express live in the proxy, not the profile.
            SandboxDecision::Enforce(SandboxBackend::Seatbelt)
        }
        crate::types::SandboxEnforce::Fs | crate::types::SandboxEnforce::FsNet
            if target_os == "linux" =>
        {
            SandboxDecision::Enforce(SandboxBackend::Bubblewrap)
        }
        crate::types::SandboxEnforce::Fs | crate::types::SandboxEnforce::FsNet
            if target_os == "windows" =>
        {
            SandboxDecision::Enforce(SandboxBackend::AppContainer)
        }
        crate::types::SandboxEnforce::Fs | crate::types::SandboxEnforce::FsNet => {
            SandboxDecision::UnsupportedWarn
        }
    }
}

/// A resolved, enforced sandbox for one session.
#[derive(Debug, Clone)]
pub struct ResolvedSandbox {
    pub backend: SandboxBackend,
    pub inputs: SandboxInputs,
    /// Container runtime + image; `Some` iff `backend == Container`.
    pub container: Option<crate::sandbox_container::ContainerSpec>,
}

/// Expand a leading `~/` (or `~\` on Windows) in `raw` using the platform home
/// variable; otherwise return `raw` unchanged as a `PathBuf`. `pub(crate)` so
/// the engine-run gate wrap (`crate::command_exec::resolve_gate_sandbox`)
/// builds `extra_write` inputs with the SAME expansion sessions get — never a
/// second hand-rolled rule.
///
/// Windows reads `USERPROFILE`, matching [`crate::paths::global_config`]. A
/// natively launched `kranz.exe` has no `HOME` (only shells like Git Bash
/// inject one), so keying solely off `HOME` silently left `~/...` literal and
/// the sandbox grant then pointed at a directory named `~`.
pub(crate) fn expand_tilde(raw: &str) -> PathBuf {
    let rest = raw.strip_prefix("~/").or_else(|| {
        if cfg!(windows) {
            raw.strip_prefix("~\\")
        } else {
            None
        }
    });
    if let Some(rest) = rest {
        if let Some(home) = std::env::var_os(if cfg!(windows) { "USERPROFILE" } else { "HOME" })
            .filter(|value| !value.is_empty())
        {
            return PathBuf::from(home).join(rest);
        }
    }
    PathBuf::from(raw)
}

/// Resolve a role's sandbox config into an (optional) enforced sandbox for
/// one session, plus an optional one-time warning string.
///
/// Returns `(Some(ResolvedSandbox), None)` when enforcement is requested and
/// supported, `(None, None)` when enforcement is off, and
/// `(None, Some(warning))` when enforcement is requested but unsupported on
/// this platform.
pub fn resolve_for_session(
    role_sandbox: &crate::types::SandboxConfig,
    session_cwd: &Path,
    mission_dir: &Path,
) -> (Option<ResolvedSandbox>, Option<String>) {
    let runtime = crate::sandbox_container::detect();
    let resolved = resolve_for_session_target(
        role_sandbox,
        session_cwd,
        mission_dir,
        std::env::consts::OS,
        command_available("bwrap"),
        runtime,
        session_mount_proof(role_sandbox, session_cwd, mission_dir, runtime),
    );
    prewarm_xcrun_for_resolved_seatbelt(resolved.0.as_ref());
    resolved
}

/// Apple command-line-tool shims refresh a per-user `xcrun_db*` file even for
/// read-only Git commands. The profile correctly refuses that shared write,
/// so refresh the cache outside the sandbox once per resolved Seatbelt
/// session. Gate wrappers use the same bounded helper; command wrapping never
/// performs the prewarm itself.
#[cfg(target_os = "macos")]
fn prewarm_xcrun_for_resolved_seatbelt(sandbox: Option<&ResolvedSandbox>) {
    if sandbox.is_some_and(|sandbox| sandbox.backend == SandboxBackend::Seatbelt) {
        crate::command_exec::prewarm_xcrun_cache_outside_sandbox();
    }
}

#[cfg(not(target_os = "macos"))]
fn prewarm_xcrun_for_resolved_seatbelt(_sandbox: Option<&ResolvedSandbox>) {}

/// Take a bind-mount proof only where resolution needs one.
///
/// Linux is CI-proven and Windows is refused outright, so neither pays for a
/// probe. Everything else pays once per host, cached, and only when a
/// container was actually requested.
pub(crate) fn session_mount_proof(
    role_sandbox: &crate::types::SandboxConfig,
    session_cwd: &Path,
    mission_dir: &Path,
    runtime: Option<crate::sandbox_container::ContainerRuntime>,
) -> Option<crate::sandbox_container::MountProof> {
    if role_sandbox.provider != crate::types::SandboxProvider::Container
        || role_sandbox.enforce == crate::types::SandboxEnforce::Off
        || cfg!(target_os = "linux")
        || cfg!(target_os = "windows")
    {
        return None;
    }
    let runtime = runtime?;
    let extra_write: Vec<PathBuf> = role_sandbox
        .extra_write
        .iter()
        .map(|raw| expand_tilde(raw))
        .collect();
    Some(crate::sandbox_container::prove_mount_roots(
        runtime,
        &crate::sandbox_container::declared_mount_roots(session_cwd, mission_dir, &extra_write),
        crate::sandbox_container::DEFAULT_IMAGE,
    ))
}

fn resolve_for_session_target(
    role_sandbox: &crate::types::SandboxConfig,
    session_cwd: &Path,
    mission_dir: &Path,
    target_os: &str,
    bwrap_available: bool,
    container_runtime: Option<crate::sandbox_container::ContainerRuntime>,
    container_mount_proof: Option<crate::sandbox_container::MountProof>,
) -> (Option<ResolvedSandbox>, Option<String>) {
    if role_sandbox.provider == crate::types::SandboxProvider::Container {
        return resolve_container_target(
            role_sandbox,
            session_cwd,
            mission_dir,
            target_os,
            container_runtime,
            container_mount_proof,
        );
    }
    match platform_support(role_sandbox.enforce, target_os) {
        SandboxDecision::Off => (None, None),
        SandboxDecision::UnsupportedWarn => (
            None,
            Some(format!(
                "sandbox enforce:{} requested but unsupported on target_os={target_os}; refusing to run unsandboxed",
                enforce_label(role_sandbox.enforce)
            )),
        ),
        SandboxDecision::Enforce(SandboxBackend::Bubblewrap) if !bwrap_available => (
            None,
            Some(format!(
                "sandbox enforce:{} requested on linux but `bwrap` was not found; refusing to run unsandboxed",
                enforce_label(role_sandbox.enforce)
            )),
        ),
        SandboxDecision::Enforce(backend) => (
            Some(ResolvedSandbox {
                backend,
                inputs: build_inputs(role_sandbox, session_cwd, mission_dir),
                container: None,
            }),
            None,
        ),
    }
}

/// Resolve the tier-3 container provider: `enforce: off` stays unsandboxed;
/// `fs+net` with an empty egress list keeps the `--network none` hard egress
/// boundary. A non-empty list is supported only by Docker: the runner creates
/// a unique internal network and authenticated filtering relay before spawn.
/// Other runtimes refuse rather than silently falling back to their bridge.
/// A requested container with no runtime on PATH is refused.
fn resolve_container_target(
    role_sandbox: &crate::types::SandboxConfig,
    session_cwd: &Path,
    mission_dir: &Path,
    target_os: &str,
    runtime: Option<crate::sandbox_container::ContainerRuntime>,
    mount_proof: Option<crate::sandbox_container::MountProof>,
) -> (Option<ResolvedSandbox>, Option<String>) {
    if role_sandbox.enforce == crate::types::SandboxEnforce::Off {
        return (None, None);
    }
    // Linux carries a continuously enforced CI receipt for the shipped
    // bind-mount, authority-mask, and egress contracts, so it needs no
    // per-host evidence. macOS cannot renew that receipt in CI, because
    // hosted runners are already guests and cannot provision the VM the
    // runtime needs. Rather than claim macOS on a receipt that expires or
    // deny a host that demonstrably works, require the evidence AT RUN TIME:
    // a macOS host is supported exactly when this runtime proves it really
    // shares the mounted path. Windows stays refused whatever a probe says,
    // because its gap is the POSIX guest-path and `/dev/null` authority-mask
    // contract, which no mount proof addresses.
    if target_os == "windows" {
        return (
            None,
            Some(format!(
                "sandbox provider:container with enforce:{} is not supported on target_os=windows: the shipped contract uses POSIX guest paths, Linux images, and /dev/null authority masks that Windows containers do not honor; refusing to run under an unverified container mount contract",
                enforce_label(role_sandbox.enforce)
            )),
        );
    }
    if target_os != "linux" {
        match mount_proof {
            Some(crate::sandbox_container::MountProof::Proven) => {}
            Some(crate::sandbox_container::MountProof::Failed(reason)) => {
                return (
                    None,
                    Some(format!(
                        "sandbox provider:container with enforce:{} refused on target_os={target_os}: {reason}",
                        enforce_label(role_sandbox.enforce)
                    )),
                );
            }
            None => {
                return (
                    None,
                    Some(format!(
                        "sandbox provider:container with enforce:{} on target_os={target_os} requires a bind-mount proof on this host and none was taken; refusing to run under an unverified container mount contract; use sandbox.provider=\"process\" for native host containment",
                        enforce_label(role_sandbox.enforce)
                    )),
                );
            }
        }
    }
    let Some(runtime) = runtime else {
        return (
            None,
            Some(
                "sandbox provider:container requested but no container runtime (docker/podman/nerdctl/container) found on PATH; refusing to run unsandboxed"
                    .to_string(),
            ),
        );
    };
    if role_sandbox.enforce == crate::types::SandboxEnforce::FsNet
        && !role_sandbox.egress.is_empty()
        && runtime != crate::sandbox_container::ContainerRuntime::Docker
    {
        return (
            None,
            Some(format!(
                "sandbox provider:container with enforce:fs+net and a non-empty egress list requires Docker's internal-network boundary; runtime {} is not live-proven for that posture — refusing to run",
                runtime.binary()
            )),
        );
    }
    (
        Some(ResolvedSandbox {
            backend: SandboxBackend::Container,
            inputs: build_inputs(role_sandbox, session_cwd, mission_dir),
            container: Some(crate::sandbox_container::ContainerSpec {
                runtime,
                image: role_sandbox
                    .image
                    .clone()
                    .unwrap_or_else(|| crate::sandbox_container::DEFAULT_IMAGE.to_string()),
                network: None,
                name: None,
            }),
        }),
        None,
    )
}

fn build_inputs(
    role_sandbox: &crate::types::SandboxConfig,
    session_cwd: &Path,
    mission_dir: &Path,
) -> SandboxInputs {
    let extra_write = role_sandbox
        .extra_write
        .iter()
        .map(|s| expand_tilde(s))
        .collect();
    SandboxInputs {
        enforce: role_sandbox.enforce,
        session_cwd: session_cwd.to_path_buf(),
        mission_dir: mission_dir.to_path_buf(),
        // Default session-private scratch: the mission's gitignored
        // contract/sandbox scratch home — the shape the engine's own probes
        // (preflight contract commands, whose cleared env points HOME/TMPDIR
        // at `runs/contract-home`) execute under. The runner overrides this
        // per session with the session's private scratch root (see the
        // `SandboxInputs::tmpdir` doc); warn-only resolves never execute
        // under the profile, so the default is never their concern.
        tmpdir: mission_dir.join("runs").join("contract-home"),
        extra_write,
        egress: role_sandbox.egress.clone(),
        // Session sandboxes never read-deny the tree they work in — the
        // validator containment resolution sets this explicitly.
        validator_read_deny_roots: Vec::new(),
    }
}

// ---------------------------------------------------------------------------
// Mandatory validator containment (ticket validator-mandatory-containment)
// ---------------------------------------------------------------------------

/// The outcome of resolving one validator session's MANDATORY containment
/// (ticket `validator-mandatory-containment`). The validator is the
/// adversarial reader the whole gate rests on; its isolation must not depend
/// on the operator opting into enforcement, so `sandbox.enforce: off` (the
/// default) no longer means an unwrapped validator — where the platform has
/// a process-sandbox tier and the selected backend can apply it, the session
/// is wrapped regardless.
#[derive(Debug)]
pub struct ValidatorContainment {
    /// The sandbox to attach to the validator's [`crate::backend::SessionSpec`]
    /// — `Some` whenever a wrap applies (the role's own enforced sandbox
    /// plus the read-deny roots, or the mandatory `fs`-tier wrap under
    /// `enforce: off`), `None` only when containment degraded (see `note`).
    pub sandbox: Option<ResolvedSandbox>,
    /// The LOUD operator-facing posture note when containment could not be
    /// applied AND the operator opted into the degrade
    /// (`validatorAllowUncontainedDegrade`) — an unsupported platform, a
    /// linux without `bwrap`, or a backend that does not honor the resolved
    /// sandbox. The orchestrator surfaces it as a decision per validator
    /// spawn (so every validation round carries it); `None` when the session
    /// is contained. Without the opt-in the resolution FAILS CLOSED instead
    /// (ticket `validator-containment-degrade-fail-closed`, 14th-pass
    /// review): the degrade reopens the modify→use→restore path the
    /// mandatory-containment work was built to close, so snapshot
    /// separation plus the after-fingerprint tripwire alone are no longer
    /// the default posture.
    pub note: Option<String>,
}

/// Resolve the containment posture for one validator session (both roles —
/// scrutiny and functional run the same shape).
///
/// `session_cwd` is the throwaway snapshot worktree — the profile's sole
/// writable root alongside the session-private scratch. `read_deny_roots`
/// are the REAL checkout roots the snapshot was taken from (the active tree,
/// plus the primary checkout when worktree mode separates them); their
/// source trees become read-denied in the generated profile/argv
/// ([`validator_read_deny_entries`]). `backend` decides whether the wrap can
/// be honored at all: only the claude backend applies a resolved sandbox
/// ([`crate::types::BackendKind::supports_sandbox_enforcement`]).
///
/// `enforce != off` keeps today's fail-closed posture byte-for-byte: the
/// role's own resolution governs (an unsupported platform or missing `bwrap`
/// is an Err, mirroring the runner's `resolve_sandbox_or_refuse`), with the
/// read-deny roots ATTACHED on the process tier. The container provider
/// resolves untouched — its read-only rootfs and named mounts are already
/// the stronger containment, and the real tree is simply not mounted.
///
/// `enforce == off` is the case this ticket exists for: the mandatory
/// `fs`-tier wrap (write containment with the validator's API egress intact;
/// no operator `extraWrite` widening — the snapshot is the sole writable
/// root) wherever the platform supports it and the backend can apply it.
/// Everywhere else the resolution FAILS CLOSED (ticket
/// `validator-containment-degrade-fail-closed`, 14th-pass review — this
/// reverses the 224fa73 loud-degrade default) unless
/// `allow_uncontained_degrade` (the `validatorAllowUncontainedDegrade`
/// config flag) opts this repo back into the loud degradation note.
pub fn resolve_validator_containment(
    role_sandbox: &crate::types::SandboxConfig,
    backend: crate::types::BackendKind,
    session_cwd: &Path,
    mission_dir: &Path,
    read_deny_roots: &[PathBuf],
    allow_uncontained_degrade: bool,
) -> crate::error::Result<ValidatorContainment> {
    let runtime = crate::sandbox_container::detect();
    let resolved = resolve_validator_containment_target(
        role_sandbox,
        backend,
        session_cwd,
        mission_dir,
        read_deny_roots,
        allow_uncontained_degrade,
        std::env::consts::OS,
        command_available("bwrap"),
        runtime,
        session_mount_proof(role_sandbox, session_cwd, mission_dir, runtime),
    );
    if let Ok(containment) = &resolved {
        prewarm_xcrun_for_resolved_seatbelt(containment.sandbox.as_ref());
    }
    resolved
}

/// [`resolve_validator_containment`] parameterized on the target OS, `bwrap`
/// availability, and container runtime so the decision matrix is testable
/// cross-platform (mirrors [`resolve_for_session_target`] /
/// `crate::command_exec::resolve_gate_sandbox_target`).
#[allow(clippy::too_many_arguments)]
fn resolve_validator_containment_target(
    role_sandbox: &crate::types::SandboxConfig,
    backend: crate::types::BackendKind,
    session_cwd: &Path,
    mission_dir: &Path,
    read_deny_roots: &[PathBuf],
    allow_uncontained_degrade: bool,
    target_os: &str,
    bwrap_available: bool,
    container_runtime: Option<crate::sandbox_container::ContainerRuntime>,
    container_mount_proof: Option<crate::sandbox_container::MountProof>,
) -> crate::error::Result<ValidatorContainment> {
    if role_sandbox.enforce != crate::types::SandboxEnforce::Off {
        // The role's own resolution governs; an enforced pair with a
        // backend that cannot honor it is already refused by
        // `config::validate` (fail closed) before a mission reaches here.
        let (sandbox, warn) = resolve_for_session_target(
            role_sandbox,
            session_cwd,
            mission_dir,
            target_os,
            bwrap_available,
            container_runtime,
            container_mount_proof,
        );
        return match sandbox {
            Some(mut resolved) => {
                // Process-tier wraps (Seatbelt/bwrap) get the read-deny
                // roots; the container tier's mounts are the containment
                // and simply do not include the real tree.
                if resolved.backend != SandboxBackend::Container {
                    resolved.inputs.validator_read_deny_roots = read_deny_roots.to_vec();
                }
                Ok(ValidatorContainment {
                    sandbox: Some(resolved),
                    note: None,
                })
            }
            // Fail closed, mirroring resolve_sandbox_or_refuse: enforcement
            // was requested and cannot be honored on this platform.
            None => Err(crate::error::EngineError::Backend(warn.unwrap_or_else(|| {
                format!(
                    "sandbox enforce:{} requested but no sandbox could be resolved; refusing to run unsandboxed",
                    role_sandbox.enforce.as_str()
                )
            }))),
        };
    }

    // enforce: off — MANDATORY containment. The provider is ignored here:
    // `provider: container` with `enforce: off` documents "no sandboxing,
    // same as today", and the mandatory wrap is the process tier.
    //
    // Where the wrap cannot apply, the default is FAIL CLOSED (ticket
    // validator-containment-degrade-fail-closed, 14th-pass review — this
    // REVERSES the 224fa73 loud-degrade-by-default decision: a degraded
    // validator runs with snapshot separation and the tripwire only, which
    // reopens the modify→use→restore path the wrap exists to close).
    // `validatorAllowUncontainedDegrade` opts this repo back into the loud
    // per-round degradation note.
    let uncontained = |why: String, note: String| -> crate::error::Result<ValidatorContainment> {
        if !allow_uncontained_degrade {
            return Err(crate::error::EngineError::Config(format!(
                "mandatory validator containment cannot apply ({why}); refusing to run an \
                 uncontained validator — the degraded posture reopens the modify→use→restore \
                 path the wrap exists to close (ticket \
                 validator-containment-degrade-fail-closed). To run validators here anyway, \
                 set \"validatorAllowUncontainedDegrade\": true in .kranz/config.json (the \
                 loud per-round degrade returns); otherwise use a containable platform \
                 (macOS, or linux with `bwrap` on PATH) and the claude validator backend"
            )));
        }
        Ok(ValidatorContainment {
            sandbox: None,
            note: Some(note),
        })
    };
    if !backend.supports_sandbox_enforcement() {
        return uncontained(
            format!(
                "the {} backend does not apply the resolved sandbox profile",
                backend.as_str()
            ),
            format!(
                "validator sessions on the {} backend cannot be OS-sandbox-contained (only the \
                 claude backend applies the resolved sandbox profile); \
                 validatorAllowUncontainedDegrade is set, so this validator runs with \
                 snapshot isolation and the after-fingerprint tripwire only — the real checkout \
                 is reachable from the session. Select a claude validator backend for mandatory \
                 containment (ticket validator-mandatory-containment; the degrade is opt-in per \
                 validator-containment-degrade-fail-closed)",
                backend.as_str()
            ),
        );
    }
    let degraded = |why: String| {
        uncontained(
            why.clone(),
            format!(
                "validator sessions are NOT OS-sandbox-contained ({why}); \
                 validatorAllowUncontainedDegrade is set, so the validator still runs in its \
                 throwaway snapshot with the after-fingerprint tripwire on the real checkout, \
                 but hostile validator code could walk to the real checkout and restore bytes \
                 before the fingerprint — containment here is the snapshot's physical \
                 separation only (ticket validator-mandatory-containment; the degrade is \
                 opt-in per validator-containment-degrade-fail-closed)"
            ),
        )
    };
    match platform_support(crate::types::SandboxEnforce::Fs, target_os) {
        // Unreachable (Fs is not Off) — platform_support is the shared
        // vocabulary, so the match stays exhaustive anyway.
        SandboxDecision::Off => unreachable!("fs never decides Off"),
        SandboxDecision::UnsupportedWarn => {
            degraded(format!("target_os={target_os} has no process-sandbox tier"))
        }
        SandboxDecision::Enforce(SandboxBackend::Bubblewrap) if !bwrap_available => {
            degraded("linux without `bwrap` on PATH".to_string())
        }
        // platform_support never selects Container (that resolution is
        // resolve_container_target's, and the enforce!=off arm above owns
        // the provider) — the match stays exhaustive anyway.
        SandboxDecision::Enforce(SandboxBackend::Container) => {
            unreachable!("process tier only")
        }
        SandboxDecision::Enforce(backend_kind) => Ok(ValidatorContainment {
            sandbox: Some(ResolvedSandbox {
                backend: backend_kind,
                inputs: SandboxInputs {
                    // The fs tier: write containment with network intact
                    // (denying egress would brick the validator's API
                    // session — the same reason the session profile
                    // allows network under fs).
                    enforce: crate::types::SandboxEnforce::Fs,
                    session_cwd: session_cwd.to_path_buf(),
                    mission_dir: mission_dir.to_path_buf(),
                    // Pinned per session by the runner to the session's
                    // private scratch root (the same pin
                    // resolve_sandbox_or_refuse applies); the default
                    // here is the probe-shaped contract home.
                    tmpdir: mission_dir.join("runs").join("contract-home"),
                    // NO operator extraWrite widening under the mandatory
                    // wrap: the snapshot worktree is the sole writable
                    // root (plus the session-private scratch).
                    extra_write: Vec::new(),
                    egress: Vec::new(),
                    validator_read_deny_roots: read_deny_roots.to_vec(),
                },
                container: None,
            }),
            note: None,
        }),
    }
}

pub(crate) fn command_available(name: &str) -> bool {
    let Some(path) = std::env::var_os("PATH") else {
        return false;
    };
    // Windows PATH entries carry no extension; the executable suffixes live in
    // PATHEXT. Probing the bare name alone reports every Windows executable as
    // missing (`grep` vs `grep.exe`).
    let mut candidates = vec![name.to_string()];
    if cfg!(windows) {
        let pathext =
            std::env::var("PATHEXT").unwrap_or_else(|_| ".COM;.EXE;.BAT;.CMD".to_string());
        candidates.extend(
            pathext
                .split(';')
                .filter(|ext| !ext.is_empty())
                .map(|ext| format!("{name}{ext}")),
        );
    }
    std::env::split_paths(&path).any(|dir| candidates.iter().any(|name| dir.join(name).is_file()))
}

/// Absolutize a path without requiring it to exist: canonicalize if possible,
/// otherwise join it onto the current directory when relative.
pub(crate) fn absolutize(path: &Path) -> PathBuf {
    if let Ok(canon) = path.canonicalize() {
        return canon;
    }
    // Future authority paths still need their existing ancestors resolved
    // (notably /var -> /private/var), even before their leaf is created.
    for ancestor in path.ancestors().skip(1) {
        if let Ok(canon) = ancestor.canonicalize() {
            if let Ok(suffix) = path.strip_prefix(ancestor) {
                return canon.join(suffix);
            }
        }
    }
    if path.is_absolute() {
        path.to_path_buf()
    } else {
        std::env::current_dir()
            .map(|cwd| cwd.join(path))
            .unwrap_or_else(|_| path.to_path_buf())
    }
}

// Mount destinations name the inspected leaf without following its links.
fn lexical_absolute(path: &Path) -> PathBuf {
    if path.is_absolute() {
        path.to_path_buf()
    } else {
        std::env::current_dir()
            .map(|cwd| cwd.join(path))
            .unwrap_or_else(|_| path.to_path_buf())
    }
}

pub(crate) fn global_authority_dir() -> Option<PathBuf> {
    crate::paths::global_config().and_then(|path| path.parent().map(absolutize))
}

/// Escape a path for embedding in an SBPL string literal.
pub(crate) fn escape_sbpl_literal(path: &Path) -> String {
    escape_sbpl_string(&path.to_string_lossy())
}

fn escape_sbpl_string(s: &str) -> String {
    s.replace('\\', "\\\\").replace('"', "\\\"")
}

/// Escape a path for embedding in an SBPL `#"..."` regex literal: every
/// regex metacharacter is backslash-escaped so the path matches literally
/// (temp-dir names carry no metacharacters in practice, but a repo root
/// might — `.` in a directory name must not become an any-char match).
pub(crate) fn escape_sbpl_regex(path: &Path) -> String {
    let mut out = String::new();
    for ch in path.to_string_lossy().chars() {
        match ch {
            '\\' => out.push_str("\\\\"),
            '"' => out.push_str("\\\""),
            c if "^.+$*?()[]{}|".contains(c) => {
                out.push('\\');
                out.push(c);
            }
            c => out.push(c),
        }
    }
    out
}

/// The session's writable roots: its working directory (worktree or, in
/// checkout mode, the repo root), its private scratch root, and each
/// operator-declared `extraWrite` entry. The mission dir and the shared
/// system temp root are deliberately NOT here (ticket
/// sandbox-writable-scope): the engine writes mission metadata from OUTSIDE
/// the sandbox, and whole-`TMPDIR` access made sibling missions' worktrees
/// writable. Mission metadata that would still be reachable through an
/// allowed ancestor (checkout mode: `session_cwd` is the repo root) is
/// carved back out by [`mission_write_denies`].
pub(crate) fn write_allowlist(inputs: &SandboxInputs) -> Vec<PathBuf> {
    let mut write_paths: Vec<PathBuf> =
        vec![absolutize(&inputs.session_cwd), absolutize(&inputs.tmpdir)];
    write_paths.extend(inputs.extra_write.iter().map(|p| absolutize(p)));
    write_paths.sort();
    write_paths.dedup();
    write_paths
}

/// The mission-metadata write-deny set: engine-owned files a sandboxed
/// session must never write even when an allowed ancestor (checkout mode's
/// `session_cwd` = repo root) would otherwise cover them. A worker that
/// could rewrite `events.jsonl` defeats the append-only audit log; one that
/// could drop files into `control/` injects control commands; one that
/// could rewrite `runs/*.jsonl` forges transcripts. Like
/// [`authority_read_deny_paths`], both the raw and canonical mission-dir
/// forms are expanded (Seatbelt matches canonical paths; the child may
/// address either form).
pub(crate) struct MissionWriteDenies {
    /// Engine-written files at the mission-dir root: literal write denies
    /// (Seatbelt) / read-only directory views (bwrap).
    pub files: Vec<PathBuf>,
    /// Current and sibling `control/` inboxes: subpath write deny / tmpfs shadow.
    pub control_dirs: Vec<PathBuf>,
    /// The `runs/` transcript dirs: `runs/*.jsonl` regex write deny
    /// (Seatbelt) / read-only directory binds (bwrap). Session scratch and
    /// the current worktree keep their explicit writable roots.
    pub runs_dirs: Vec<PathBuf>,
}

/// Engine-written files at the mission-dir root a sandboxed session must
/// never write (see [`MissionWriteDenies`]).
pub(crate) const MISSION_METADATA_FILES: &[&str] = &[
    "events.jsonl",
    "events.jsonl.lock",
    "state.json",
    "state.json.tmp",
    "estimate.json",
];

pub(crate) fn mission_write_denies(inputs: &SandboxInputs) -> MissionWriteDenies {
    let mut denies = MissionWriteDenies {
        files: Vec::new(),
        control_dirs: Vec::new(),
        runs_dirs: Vec::new(),
    };
    let mut mission_dirs = vec![inputs.mission_dir.clone(), absolutize(&inputs.mission_dir)];
    // Checkout mode makes the whole repository writable. Protect sibling
    // missions as well as the current one; their inboxes have equal authority.
    if let Some(missions) = inputs
        .mission_dir
        .parent()
        .filter(|path| path.ends_with("missions"))
    {
        if let Ok(entries) = std::fs::read_dir(missions) {
            for entry in entries.flatten() {
                if entry.file_type().is_ok_and(|kind| kind.is_dir()) {
                    mission_dirs.extend([entry.path(), absolutize(&entry.path())]);
                }
            }
        }
    }
    for mission_dir in mission_dirs {
        for name in MISSION_METADATA_FILES {
            denies.files.push(mission_dir.join(name));
        }
        denies.control_dirs.push(mission_dir.join("control"));
        denies.runs_dirs.push(mission_dir.join("runs"));
    }
    denies
}

/// The operator's real Cargo home: ambient `CARGO_HOME` when set, else
/// `~/.cargo` when HOME is set — the same resolution
/// `crate::agent_env::toolchain_var_value("CARGO_HOME", ".cargo")` applies
/// when it builds the isolated contract home. The two MUST stay in
/// lockstep: whatever the isolated home can LINK is what the profile must
/// be able to DENY writes to (see [`cargo_cache_write_deny_paths`]).
fn operator_cargo_home() -> Option<PathBuf> {
    std::env::var_os("CARGO_HOME")
        .map(PathBuf::from)
        .or_else(|| std::env::var_os("HOME").map(|h| PathBuf::from(h).join(".cargo")))
}

/// The operator's REAL shared Cargo cache directories —
/// `<cargo home>/registry` and `<cargo home>/git` — in both raw and
/// canonicalized forms (the `/var` ↔ `/private/var` idiom the write
/// allowlist already uses; Seatbelt matches canonical paths and a child
/// may address either form). Above the copy ceiling the isolated contract
/// home LINKS these in (`crate::agent_env::cache_only_cargo_home`'s
/// documented residual trade), so every sandbox profile must deny WRITES
/// to them explicitly (13th-pass review, P1): deny-default covers the
/// common case, but only an explicit deny survives EVERY allow — an
/// operator `extraWrite` of `$HOME`, or any future broadened writable
/// root, would otherwise silently re-widen the linked cache to writes
/// from worker-authored contract code, poisoning later builds. PRECISE
/// scope: the two cache dirs only, never the whole cargo home —
/// `~/.cargo/bin`'s rustup shims keep their ordinary posture. Reads stay
/// allowed: the linked cache is the session/gate's registry.
pub(crate) fn cargo_cache_write_deny_paths() -> Vec<PathBuf> {
    let Some(cargo_home) = operator_cargo_home() else {
        return Vec::new();
    };
    let mut paths = Vec::with_capacity(4);
    for base in [cargo_home.clone(), absolutize(&cargo_home)] {
        paths.push(base.join("registry"));
        paths.push(base.join("git"));
    }
    paths
}

/// Authority files a sandboxed session must never read, even under the broad
/// read allow: a read of `serve.token` IS mutation authority over `kranz
/// serve` (loopback is reachable from every sandbox tier), `serve.read.token`
/// is its GET-side sibling, `config.json` carries Slack tokens and
/// remote-workspace credentials, and `domain-terms.local` is the plaintext
/// clean-room lint vocabulary that must never be readable outside the
/// engine-side lint (14th-pass review: the mandatory validator wrap's
/// `.kranz` carve-out — kept for the snapshot — otherwise leaks it).
/// Derived from the mission dir's canonical `<repo>/.kranz/missions/<id>`
/// layout. Both the raw and the canonical mission-dir forms are expanded (the
/// dir exists at spawn time even when the token files do not yet), because
/// Seatbelt matches against canonical paths — the same `/var` ↔
/// `/private/var` split the write allowlist handles.
///
/// Also denied: `$CARGO_HOME/credentials.toml` AND the legacy extensionless
/// `$CARGO_HOME/credentials` (or `~/.cargo/...` when CARGO_HOME is unset) —
/// CARGO_HOME crosses into child envs for registry-cache locality
/// ([`crate::agent_env`]), but cargo reads BOTH filenames for registry auth
/// tokens (the legacy one is still supported and takes precedence where
/// present), so both are the same credential class as the serve token.
pub(crate) fn authority_read_deny_paths(inputs: &SandboxInputs) -> Vec<PathBuf> {
    let mut paths = Vec::new();
    for mission_dir in [inputs.mission_dir.clone(), absolutize(&inputs.mission_dir)] {
        if let Some(kranz_dir) = mission_dir
            .parent()
            .filter(|path| path.ends_with("missions"))
            .and_then(Path::parent)
        {
            for name in KRANZ_AUTHORITY_FILES {
                paths.push(kranz_dir.join(name));
            }
        }
    }
    for name in [
        "serve.token",
        "serve.read.token",
        "config.json",
        "domain-terms.local",
    ] {
        paths.push(absolutize(&inputs.session_cwd).join(".kranz").join(name));
    }
    if let Some(global) = crate::paths::global_config() {
        paths.extend([global.clone(), absolutize(&global)]);
    }
    if let Some(cargo_home) = operator_cargo_home() {
        for base in [cargo_home.clone(), absolutize(&cargo_home)] {
            paths.push(base.join("credentials.toml"));
            paths.push(base.join("credentials"));
        }
    }
    // Config layers can be symlinked. Deny the resolved file as well as its
    // configured name so a canonical read cannot bypass the authority rule.
    paths.extend(paths.clone().iter().map(|path| absolutize(path)));
    paths.sort();
    paths.dedup();
    paths
}

/// Authority DIRECTORIES a sandboxed session must never read (14th-pass
/// review — the directory half of [`authority_read_deny_paths`], denied as
/// Seatbelt subpaths / bwrap tmpfs shadows):
///
/// - `<repo>/.kranz/hook-status/` — the hook-signal projection
///   (registrations + per-run capability-token hashes). The in-sandbox
///   `kranz hook-status` relay reads only its session-private spec and POSTs
///   loopback; the server reads the projection from OUTSIDE the sandbox.
/// - `<mission_dir>/control/` — the operator→engine control inbox (approve /
///   pause / config-change commands). The orchestrator polls it from outside
///   the sandbox; no session ever legitimately reads it. The bwrap write
///   shadow already hid its contents — this aligns the Seatbelt read posture.
/// - `<global kranz dir>/keys/` — the operator-side authority keys the
///   consent substrate is authenticated with (2026-09-01 adversarial audit,
///   C1/H6: control files and the event log are MACed with a key that must
///   live OUTSIDE every sandboxed session's readable set, or the MAC proves
///   nothing against the agent it is meant to exclude). Denied for writes
///   too ([`authority_write_denies`]): a session that can replace the key
///   can re-sign whatever it likes.
pub(crate) fn authority_read_deny_dirs(inputs: &SandboxInputs) -> Vec<PathBuf> {
    let mut dirs = Vec::new();
    for mission_dir in [inputs.mission_dir.clone(), absolutize(&inputs.mission_dir)] {
        dirs.push(mission_dir.join("control"));
        if let Some(kranz_dir) = mission_dir
            .parent()
            .filter(|path| path.ends_with("missions"))
            .and_then(Path::parent)
        {
            dirs.push(kranz_dir.join("hook-status"));
        }
    }
    if let Some(global) = crate::paths::global_kranz_dir() {
        dirs.extend([global.clone(), absolutize(&global)]);
    }
    for keys_dir in global_key_dirs() {
        dirs.push(keys_dir);
    }
    dirs
}

/// Mount-backed sandboxes need a private directory namespace, not just
/// per-file masks: an absent token/config can be created while a worker is
/// running. Rebind only existing non-authority entries read-only beneath an
/// empty tmpfs. No placeholder files are created in the host checkout.
pub(crate) struct AuthorityDirectoryMask {
    pub path: PathBuf,
    pub visible_entries: Vec<PathBuf>,
}

pub(crate) fn authority_directory_masks(inputs: &SandboxInputs) -> Vec<AuthorityDirectoryMask> {
    let files: std::collections::BTreeSet<_> = authority_read_deny_paths(inputs)
        .into_iter()
        .filter_map(|path| Some(absolutize(path.parent()?).join(path.file_name()?)))
        .collect();
    let dirs: std::collections::BTreeSet<_> = authority_read_deny_dirs(inputs)
        .iter()
        .map(|path| absolutize(path))
        .collect();
    let mut roots: std::collections::BTreeSet<_> = files
        .iter()
        .filter_map(|path| path.parent().map(Path::to_path_buf))
        .collect();
    // Hide denied subdirectories through their parent's private namespace.
    // This also works when control/ or hook-status/ does not yet exist under
    // a read-only mission bind; setup need not mkdir in the host directory.
    for dir in &dirs {
        if !roots.contains(dir) {
            if let Some(parent) = dir.parent() {
                roots.insert(parent.to_path_buf());
            }
        }
    }
    let writable = write_allowlist(inputs);
    // A denied path may pass through a symlink beneath an allowed write root.
    // Mask the link's parent too: masking only its target would let the worker
    // replace the alias and redirect the engine's next config read. Ancestors
    // outside writable roots need no extra view (e.g. the system /var alias).
    for path in authority_read_deny_paths(inputs)
        .into_iter()
        .chain(authority_read_deny_dirs(inputs))
    {
        for ancestor in path.ancestors() {
            if std::fs::symlink_metadata(ancestor)
                .is_ok_and(|metadata| metadata.file_type().is_symlink())
            {
                if let Some(parent) = ancestor.parent().map(absolutize) {
                    if writable.iter().any(|root| parent.starts_with(root)) {
                        roots.insert(parent);
                    }
                }
            }
        }
    }
    let roots: std::collections::BTreeSet<_> = roots
        .into_iter()
        .map(|path| {
            if !path.exists() && !writable.iter().any(|root| path.starts_with(root)) {
                // bwrap cannot create a mountpoint inside its read-only / bind.
                // Mask the nearest existing ancestor instead; denied descendants
                // are never rebound, and private write roots are restored below.
                path.ancestors()
                    .skip(1)
                    .find(|parent| parent.is_dir())
                    .map(Path::to_path_buf)
                    .unwrap_or(path)
            } else {
                path
            }
        })
        .collect();
    roots
        .into_iter()
        .map(|path| {
            let mut visible_entries = Vec::new();
            if !dirs.iter().any(|dir| path.starts_with(dir)) {
                if let Ok(entries) = std::fs::read_dir(&path) {
                    for entry in entries.flatten() {
                        let entry_path = entry.path();
                        // Never follow a worker-authored link while constructing
                        // a privileged bind. Unknown/unreadable entries stay hidden.
                        if entry
                            .file_type()
                            .is_ok_and(|kind| kind.is_dir() || kind.is_file())
                            && !files.contains(&entry_path)
                            && !dirs.iter().any(|dir| entry_path.starts_with(dir))
                        {
                            visible_entries.push(entry_path);
                        }
                    }
                }
            }
            visible_entries.sort();
            AuthorityDirectoryMask {
                path,
                visible_entries,
            }
        })
        .collect()
}

/// The GLOBAL kranz authority stores (`<global kranz dir>/keys`, where the
/// per-repository authority key lives, and `<global kranz dir>/seals`, where
/// each mission's seal floor lives), each in raw and canonical form. The
/// global dir comes from [`crate::paths::global_kranz_dir`], the same
/// resolver the key writer and the seal recorder use, so the deny and the
/// writers cannot drift apart. Empty when no global dir resolves (no home,
/// no key dir, nothing to deny).
fn global_key_dirs() -> Vec<PathBuf> {
    let Some(global) = crate::paths::global_kranz_dir() else {
        return Vec::new();
    };
    let mut out = Vec::new();
    for name in ["keys", "seals"] {
        let dir = global.join(name);
        let canonical = absolutize(&dir);
        if canonical != dir {
            out.push(canonical);
        }
        out.push(dir);
    }
    out
}

/// Repo-level `<repo>/.kranz` stores the ENGINE owns end to end. Named
/// explicitly (not only enumerated from the live directory) so the deny
/// exists before the store does: a session that could CREATE
/// `.kranz/queue/` would own the autoWork drain outright.
const KRANZ_ENGINE_OWNED_DIRS: &[&str] = &["queue", "tickets", "lessons", "hook-status"];

/// Authority FILES that live directly under a `<repo>/.kranz` dir — the
/// same four [`authority_read_deny_paths`] names, factored out so the
/// container tier can apply them to the `.kranz` under its own session
/// mount without re-typing the list (2026-09-01 adversarial audit, MED-3:
/// the hand-copied three-name list had already drifted).
const KRANZ_AUTHORITY_FILES: &[&str] = &[
    "serve.token",
    "serve.read.token",
    "config.json",
    "domain-terms.local",
];

/// The authority set under ONE `<repo>/.kranz` dir: the engine-owned files
/// and the engine-owned stores. Shared by the process, container, and
/// Windows tiers so none of them can drift from the others.
pub(crate) fn kranz_authority_entries(kranz_dir: &Path) -> WriteDenySet {
    WriteDenySet {
        files: KRANZ_AUTHORITY_FILES
            .iter()
            .map(|name| kranz_dir.join(name))
            .collect(),
        dirs: KRANZ_ENGINE_OWNED_DIRS
            .iter()
            .map(|name| kranz_dir.join(name))
            .collect(),
    }
}

/// The `(<repo>/.kranz, <repo>/.kranz/missions, <mission dir>)` triples this
/// session's mission dir sits in — raw and canonical form — and ONLY when
/// the mission dir actually has the canonical `<repo>/.kranz/missions/<id>`
/// shape.
///
/// The shape check is load-bearing, not defensive tidiness: the deny
/// derivation below SWEEPS these directories, and a mission dir that is not
/// in the canonical layout (a bare temp dir in a fixture, a future layout
/// change) would otherwise make the sweep walk the system temp root, or
/// `/`, and deny writes across the whole host. A non-canonical layout
/// yields nothing here, which is the fail-quiet direction for a deny that is
/// additive to an already-narrow write allowlist.
fn repo_kranz_dirs(inputs: &SandboxInputs) -> Vec<(PathBuf, PathBuf, PathBuf)> {
    let mut out = Vec::new();
    for mission_dir in [inputs.mission_dir.clone(), absolutize(&inputs.mission_dir)] {
        let Some(missions_dir) = mission_dir.parent().map(Path::to_path_buf) else {
            continue;
        };
        let Some(kranz_dir) = missions_dir.parent().map(Path::to_path_buf) else {
            continue;
        };
        if missions_dir.file_name() != Some(std::ffi::OsStr::new("missions"))
            || kranz_dir.file_name() != Some(std::ffi::OsStr::new(".kranz"))
        {
            continue;
        }
        out.push((kranz_dir, missions_dir, mission_dir));
    }
    out
}

/// A write-deny set split by what each tier can express: `files` deny as
/// Seatbelt literals / bwrap self ro-binds / Windows non-inheriting ACL
/// denies, `dirs` as Seatbelt subpaths / bwrap self ro-binds / inheriting
/// ACL denies.
pub(crate) struct WriteDenySet {
    pub files: Vec<PathBuf>,
    pub dirs: Vec<PathBuf>,
}

fn sorted_dedup(mut paths: Vec<PathBuf>) -> Vec<PathBuf> {
    paths.sort();
    paths.dedup();
    paths
}

/// Authority material a sandboxed session must never WRITE (2026-09-01
/// adversarial audit H2 + H11).
///
/// The pre-audit posture denied READS of `<repo>/.kranz/config.json`,
/// `serve.token`, `serve.read.token`, `domain-terms.local`, `hook-status/`
/// and the mission `control/` inbox while leaving them WRITABLE: under
/// `workerIsolation: "checkout"` the session cwd IS the repo root, so a
/// contained worker could overwrite the trust root it could not read. The
/// running mission is immune (its config is pinned into `MissionCreated`);
/// the next mission picks up `claudeBinary`, `dangerouslyAllowAll`, or
/// `enforce: off` from the file the worker wrote. Every path the read deny
/// names is therefore denied for writes as well.
///
/// H11 is the same asymmetry one level up: every mission-metadata deny was
/// derived from THIS session's `mission_dir`, so a mission-A worker could
/// forge approvals into mission B's `control/` inbox, or drop entries into
/// `.kranz/queue/`, `.kranz/tickets/`, `.kranz/lessons/`. The deny is now
/// derived from `<repo>/.kranz` as a whole:
///
/// - every ENGINE-owned repo-level store ([`KRANZ_ENGINE_OWNED_DIRS`]),
///   named unconditionally so a store that does not exist yet cannot be
///   created by a session either,
/// - every top-level entry of `<repo>/.kranz` present at profile-build time
///   EXCEPT `missions/`, which is carved out because the session's own
///   mission dir lives under it,
/// - every SIBLING mission dir under `<repo>/.kranz/missions/` — the
///   session's own mission dir is carved back in, and inside it the
///   narrower [`mission_write_denies`] keeps the audit log, state snapshot,
///   control inbox and transcripts read-only while leaving the session's
///   own worktree/scratch under `runs/` writable,
/// - the global key dir, via [`authority_read_deny_dirs`].
///
/// Enumeration is spawn-time, so an entry created under `<repo>/.kranz`
/// AFTER the profile is built is not individually named. Seatbelt closes
/// that residue with [`sealed_kranz_dir_roots`]; bwrap and Windows cannot
/// express it (their masks likewise require the target to exist at spawn),
/// which is the documented remainder on those tiers.
pub(crate) fn authority_write_denies(inputs: &SandboxInputs) -> WriteDenySet {
    let mut files = authority_read_deny_paths(inputs);
    let mut dirs = authority_read_deny_dirs(inputs);
    for (kranz_dir, missions_dir, mission_dir) in repo_kranz_dirs(inputs) {
        let entries = kranz_authority_entries(&kranz_dir);
        files.extend(entries.files);
        dirs.extend(entries.dirs);
        if let Ok(entries) = std::fs::read_dir(&kranz_dir) {
            for entry in entries.flatten() {
                // `missions/` is the one carve-out: the session's own
                // mission dir is under it (see the sibling sweep below).
                if entry.file_name().as_os_str() == std::ffi::OsStr::new("missions") {
                    continue;
                }
                let path = entry.path();
                match std::fs::symlink_metadata(&path) {
                    Ok(metadata) if metadata.file_type().is_dir() => dirs.push(path),
                    // A symlink is denied as a file: denying the LINK is
                    // what stops a session replacing it, and following it
                    // would deny some unrelated target instead.
                    Ok(_) => files.push(path),
                    Err(_) => {}
                }
            }
        }
        if let Ok(entries) = std::fs::read_dir(&missions_dir) {
            for entry in entries.flatten() {
                let path = entry.path();
                if path == mission_dir {
                    continue;
                }
                dirs.push(path);
            }
        }
    }
    WriteDenySet {
        files: sorted_dedup(files),
        dirs: sorted_dedup(dirs),
    }
}

/// Seatbelt-only companion to [`authority_write_denies`]: directory roots
/// whose DIRECT children may not be created or replaced, emitted as a
/// `^<root>/[^/]*$` write-deny regex. Sealing `<repo>/.kranz` stops a
/// session creating `.kranz/queue/` (or any future engine store) after the
/// profile was built; sealing `<repo>/.kranz/missions` stops it fabricating
/// a sibling mission dir to forge approvals into. Neither seal reaches
/// GRANDchildren, so the session's own `<mission>/runs/<scratch>` stays
/// writable.
pub(crate) fn sealed_kranz_dir_roots(inputs: &SandboxInputs) -> Vec<PathBuf> {
    let mut roots = Vec::new();
    for (kranz_dir, missions_dir, _) in repo_kranz_dirs(inputs) {
        roots.push(kranz_dir);
        roots.push(missions_dir);
    }
    sorted_dedup(roots)
}

/// The operator's OWN controlling terminal, in raw and canonical form
/// (2026-09-01 adversarial audit, H7).
///
/// The gate profile grants read/write/`file-ioctl` on the pty device class
/// `^/dev/tty[p-t][0-9a-f]+$` so the validator harness's `openpty` chain
/// works. On macOS that pool IS the terminal pool: a Terminal.app session is
/// `/dev/ttys003`, matched by the same regex. A contained gate command could
/// therefore open the operator's own terminal, write raw escape sequences to
/// it, or issue `TIOCSTI` to push characters into the operator's shell —
/// arbitrary execution as the operator, outside the sandbox. Naming the
/// parent's terminal explicitly lets both profiles DENY exactly that one
/// device while keeping the pty pair the harness allocates for itself; SBPL
/// denies beat allows regardless of clause order, which this file already
/// relies on throughout.
///
/// Resolved from the ENGINE's own fds 0/1/2 at profile-build time. Every
/// child the engine spawns gets piped or null stdio, so no sandboxed process
/// legitimately holds this device. An empty result (no tty at all: a daemon,
/// CI, `kranz serve`) emits nothing extra.
#[cfg(unix)]
pub(crate) fn operator_tty_paths() -> Vec<PathBuf> {
    let mut paths = Vec::new();
    for fd in [0, 1, 2] {
        // SAFETY: `isatty` and `ttyname_r` take a plain fd and, for the
        // latter, a caller-owned buffer with its length; no ownership
        // crosses. `ttyname_r` is the thread-safe form (`ttyname` returns a
        // shared static buffer).
        let name = unsafe {
            if libc::isatty(fd) != 1 {
                continue;
            }
            let mut buffer = [0 as libc::c_char; 1024];
            if libc::ttyname_r(fd, buffer.as_mut_ptr(), buffer.len()) != 0 {
                continue;
            }
            std::ffi::CStr::from_ptr(buffer.as_ptr())
                .to_string_lossy()
                .into_owned()
        };
        if name.is_empty() {
            continue;
        }
        let path = PathBuf::from(name);
        paths.push(absolutize(&path));
        paths.push(path);
    }
    sorted_dedup(paths)
}

#[cfg(not(unix))]
pub(crate) fn operator_tty_paths() -> Vec<PathBuf> {
    Vec::new()
}

/// Render the operator-terminal deny block for `paths` (2026-09-01
/// adversarial audit, H7). Empty in, empty out: a host with no controlling
/// terminal has nothing to protect, and an empty `(deny …)` block would be
/// noise in every CI profile. Shared by [`generate_profile`] and the gate
/// extras (`crate::command_exec::gate_profile_extras`) so the two cannot
/// render the same guard differently. Parameterized on the paths rather
/// than calling [`operator_tty_paths`] itself, so the rendering is testable
/// on a host whose test runner has no tty.
pub(crate) fn tty_deny_block(paths: &[PathBuf]) -> String {
    let literals: std::collections::BTreeSet<String> =
        paths.iter().map(|path| escape_sbpl_literal(path)).collect();
    if literals.is_empty() {
        return String::new();
    }
    let mut block = String::from("(deny file-read* file-write* file-ioctl\n");
    for literal in &literals {
        block.push_str(&format!("  (literal \"{literal}\")\n"));
    }
    block.push_str(")\n");
    block
}

/// Refuse Git configurations whose complete input set this sandbox cannot
/// protect. The enforcement protects against contained children; a separate
/// unsandboxed host process can still change the repository concurrently.
pub(crate) fn validate_git_config_protection(
    inputs: &SandboxInputs,
    mount_based: bool,
) -> crate::error::Result<()> {
    let writable = write_allowlist(inputs);
    let neutral_config = absolutize(crate::git_ops::empty_global_config_path()?);
    if writable.iter().any(|root| neutral_config.starts_with(root)) {
        return Err(crate::error::EngineError::Backend(
            "cannot grant sandbox writes over the engine's neutral Git configuration; narrow the overlapping session, scratch, or extraWrite root".into(),
        ));
    }
    let Some(marker) = git_marker(&inputs.session_cwd) else {
        return Ok(());
    };
    let root = marker.parent().expect("git marker has a parent");
    let repo = crate::git_ops::GitRepo::open(root)?;
    let (git_dir, common, worktree_enabled) = repo.config_protection_paths()?;
    let described = git_metadata_dirs(&inputs.session_cwd);
    if [&git_dir, &common].iter().any(|dir| {
        !described
            .iter()
            .any(|path| absolutize(path) == absolutize(dir))
    }) {
        return Err(crate::error::EngineError::Backend(
            "cannot protect Git metadata redirected outside the session's Git layout; remove repository environment overrides before running an enforced session".into(),
        ));
    }
    let masks = authority_directory_masks(inputs);
    let mut graph_dirs = vec![git_dir.clone(), common.clone()];
    graph_dirs.extend(git_metadata_mount_nodes(inputs));
    if graph_dirs.iter().any(|dir| {
        let dir = absolutize(dir);
        // A shared Git directory outside writable roots remains read-only;
        // its existing read-only authority view needs no writable node bind.
        if !writable.iter().any(|root| dir.starts_with(root)) {
            return false;
        }
        masks.iter().any(|mask| {
            dir.starts_with(&mask.path)
                && ![&inputs.session_cwd, &inputs.tmpdir].iter().any(|private| {
                    let private = absolutize(private);
                    private != mask.path
                        && private.starts_with(&mask.path)
                        && dir.starts_with(private)
                })
        })
    }) {
        return Err(crate::error::EngineError::Backend(
            "cannot protect Git metadata through an authority directory; keep the Git directory outside .kranz and credential stores".into(),
        ));
    }
    let mut sources = vec![common.join("config")];
    if marker.is_file() {
        sources.push(marker.clone());
        sources.push(git_dir.join("commondir"));
    }
    if worktree_enabled {
        sources.push(git_dir.join("config.worktree"));
    }
    for source in sources {
        let writable_source = writable
            .iter()
            .any(|root| absolutize(&source).starts_with(root));
        // A symlink input (or replaceable symlink ancestor) defeats a path-only
        // deny. System aliases outside writable roots, such as /var, are fine.
        for ancestor in source.ancestors() {
            if std::fs::symlink_metadata(ancestor).is_ok_and(|meta| meta.file_type().is_symlink())
                && (ancestor == source
                    || writable.iter().any(|root| {
                        ancestor
                            .parent()
                            .map(absolutize)
                            .map(|parent| parent.join(ancestor.file_name().unwrap_or_default()))
                            .is_some_and(|path| path.starts_with(root))
                    }))
            {
                return Err(crate::error::EngineError::Backend(format!(
                    "cannot protect Git configuration through symlink {}; use regular Git metadata paths", ancestor.display()
                )));
            }
        }
        match std::fs::symlink_metadata(&source) {
            Ok(meta) if meta.is_file() => {
                #[cfg(unix)]
                {
                    use std::os::unix::fs::MetadataExt;
                    if meta.nlink() != 1 {
                        return Err(crate::error::EngineError::Backend(format!(
                            "cannot protect multiply linked Git configuration {}; replace it with a private regular file", source.display()
                        )));
                    }
                }
            }
            Err(error)
                if error.kind() == std::io::ErrorKind::NotFound
                    && (!mount_based || !writable_source) => {}
            Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
                return Err(crate::error::EngineError::Backend(format!(
                    "cannot protect absent active Git configuration {} with a mount sandbox; create the intended regular config file before running, or disable extensions.worktreeConfig", source.display()
                )));
            }
            _ => {
                return Err(crate::error::EngineError::Backend(format!(
                    "cannot protect Git configuration {}; expected a regular file",
                    source.display()
                )))
            }
        }
    }
    Ok(())
}

fn git_marker(cwd: &Path) -> Option<PathBuf> {
    cwd.ancestors()
        .map(|path| path.join(".git"))
        .find(|path| std::fs::symlink_metadata(path).is_ok())
}

/// Follow only the two bounded Git indirection files to describe denies. The
/// execution boundary validates the layout using Git itself before spawning.
fn git_metadata_dirs(cwd: &Path) -> Vec<PathBuf> {
    let Some(marker) = git_marker(cwd) else {
        return vec![cwd.join(".git")];
    };
    let read = |path: &Path| {
        std::fs::File::open(path)
            .ok()
            .and_then(|file| crate::paths::read_regular_file_bounded(file, 16384).ok())
    };
    if marker.is_dir() {
        return vec![marker];
    }
    let Some(link) = read(&marker) else {
        return Vec::new();
    };
    let Some(path) = link.trim().strip_prefix("gitdir: ") else {
        return Vec::new();
    };
    let dir = absolutize(&marker.parent().unwrap().join(path));
    let mut dirs = vec![dir.clone()];
    if let Some(common) = read(&dir.join("commondir")) {
        dirs.push(absolutize(&dir.join(common.trim())));
    }
    dirs
}

/// Pin writable metadata directory nodes as mountpoints, so renaming a parent
/// cannot replace a protected config path. The directories stay writable for
/// Git's index/ref lock files; named configuration inputs are mounted read-only.
pub(crate) fn git_metadata_mount_nodes(inputs: &SandboxInputs) -> Vec<PathBuf> {
    let writable = write_allowlist(inputs);
    let mut nodes = std::collections::BTreeSet::new();
    let mut dirs = git_metadata_dirs(&inputs.session_cwd);
    if let Some(marker) = git_marker(&inputs.session_cwd).filter(|path| path.is_file()) {
        dirs.push(
            marker
                .parent()
                .expect("git marker has a parent")
                .to_path_buf(),
        );
    }
    for dir in dirs {
        for path in absolutize(&dir).ancestors() {
            if writable
                .iter()
                .any(|root| path.starts_with(root) && path != root)
                && path.is_dir()
            {
                nodes.insert(path.to_path_buf());
            }
        }
    }
    nodes.into_iter().collect()
}

/// The `.git` metadata a sandboxed session must never write (2026-09-01
/// adversarial audit H3 support).
///
/// The engine runs git IN the tree the worker controls: `commit_dirty_paths`
/// checkpoints after every feature on a hardened handle
/// (`orchestrator.rs`), and `push_mission_branch` pushes from the CLI. A
/// worker that plants `.git/hooks/pre-commit`, sets `core.fsmonitor` /
/// `core.sshCommand` in `.git/config`, or rewrites the WORKTREE GITLINK to
/// point at a `.git` dir of its own making gets host execution with the
/// engine's full environment, outside every sandbox.
///
/// The deny is NARROW on purpose: the worker's own role is to commit (see
/// `prompts/worker.md` step 6), so `.git/index`, `.git/objects`,
/// `.git/refs`, and `.git/logs` must stay writable. What is denied is the
/// config-and-hook surface that turns a later engine-side git invocation
/// into code execution, plus the gitlink FILE form:
///
/// - `<cwd>/.git/hooks/` and `<cwd>/.git/info/` (subtrees),
/// - `<cwd>/.git/modules/` (subtree) — a submodule keeps its own `config`
///   and `hooks/` under `.git/modules/<name>/`, the SAME host-execution
///   surface one level down, and in checkout mode it sits inside the rw
///   session bind (follow-up review, M-9). Denied as a whole subtree so a
///   submodule added after the profile was built is covered too; git never
///   needs to write it from inside the sandbox.
/// - `<cwd>/.git/config` and `<cwd>/.git/config.worktree` (files),
/// - `<cwd>/.git` itself as a LITERAL — in worktree mode that path is the
///   gitlink file, and denying the literal stops a rewrite of it; in
///   checkout mode it is the directory node, where the literal deny stops a
///   replace of the directory without touching anything beneath it.
///
/// Reads stay allowed throughout: git cannot operate without reading its
/// own config, and secrecy was never this tier's promise.
pub(crate) fn git_metadata_write_denies(inputs: &SandboxInputs) -> WriteDenySet {
    let mut files = git_metadata_mount_nodes(inputs);
    let mut dirs = Vec::new();
    for cwd in [inputs.session_cwd.clone(), absolutize(&inputs.session_cwd)] {
        files.push(cwd.join(".git"));
        if let Some(marker) = git_marker(&cwd) {
            files.push(marker);
        }
        for git in git_metadata_dirs(&cwd) {
            files.push(git.join("config"));
            files.push(git.join("config.worktree"));
            files.push(git.join("commondir"));
            dirs.push(git.join("hooks"));
            dirs.push(git.join("info"));
            dirs.push(git.join("modules"));
        }
    }
    WriteDenySet {
        files: sorted_dedup(files),
        dirs: sorted_dedup(dirs),
    }
}

/// One entry of the validator read-deny set: a top-level path of a real
/// checkout root the validator must not read, classified so the Seatbelt
/// profile can pick `subpath` vs `literal` and the bwrap argv can pick a
/// tmpfs shadow vs a `/dev/null` mask.
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
pub(crate) struct ValidatorReadDenyEntry {
    pub path: PathBuf,
    pub is_dir: bool,
}

/// Top-level names a validator read-deny root ALWAYS keeps readable, because
/// the validator's own machinery cannot work without them:
///
/// - `.git` — the shared git directory. The snapshot is a WORKTREE: its
///   `.git` file points into `<root>/.git/worktrees/<n>`, and every
///   `git log`/`diff`/`show` the scrutiny/inspection flow runs resolves
///   objects and refs through the common dir. This is the narrow
///   `.git` surface the ticket keeps: READABLE (the fold needs it), never
///   writable (deny-default; a ref move is the tripwire's `for-each-ref`
///   half). `.git/config` stays readable for the same reason git itself
///   reads it — the same posture today's broad-read sandbox has.
/// - `.kranz` — the mission dir lives here, and the validator's snapshot
///   worktree sits under it (`<root>/.kranz/missions/<id>/runs/`). The
///   engine-owned metadata inside stays write-denied
///   ([`mission_write_denies`]) and the authority files read-denied
///   ([`authority_read_deny_paths`]) exactly as for any session; the rest
///   (tracked `workspace.json`, tickets) is content the snapshot already
///   carries.
const VALIDATOR_READ_DENY_CARVEOUTS: &[&str] = &[".git", ".kranz"];

/// The validator read-deny set (ticket `validator-mandatory-containment`):
/// every TOP-LEVEL entry of each [`SandboxInputs::validator_read_deny_roots`]
/// root EXCEPT the [`VALIDATOR_READ_DENY_CARVEOUTS`]. Denying whole top-level
/// entries covers the source tree without naming the root itself as a
/// subpath (which would swallow the carved-out `.git`/`.kranz` beneath it —
/// SBPL denies take precedence over every allow, so no allow could carve
/// them back out).
///
/// Entries are classified by `std::fs::metadata` — which FOLLOWS symlinks —
/// so a symlinked top-level dir is denied as a dir (and the canonical form
/// emitted alongside covers the link TARGET, the same raw+canonical idiom
/// [`authority_read_deny_paths`] uses; Seatbelt matches canonical paths).
/// Entries whose metadata fails (a broken symlink, a racer's unlink) are
/// skipped: a dangling link leaks nothing, and a vanished entry is gone.
///
/// The root ITSELF is not in this set: a literal deny on the root dir would
/// block stat/readdir of it, and coreutils `mkdir -p` stats every ancestor
/// of an absolute path — denying the root broke `mkdir -p` under the
/// snapshot (probed 2026-08-04). The root's directory LISTING therefore
/// stays readable on both tiers (names, never contents — the bwrap side
/// cannot express a listing deny without masking the carve-outs anyway).
///
/// One documented residual gap, outside the threat model (validator code can
/// create NOTHING at a deny root — writes there are deny-default): an entry
/// created at a root AFTER profile generation is not in the set — the same
/// spawn-time shape the bwrap authority masks already accept.
pub(crate) fn validator_read_deny_entries(inputs: &SandboxInputs) -> Vec<ValidatorReadDenyEntry> {
    let mut entries = std::collections::BTreeSet::new();
    for root in &inputs.validator_read_deny_roots {
        let Ok(read_dir) = std::fs::read_dir(root) else {
            continue;
        };
        for entry in read_dir.flatten() {
            let name = entry.file_name();
            if VALIDATOR_READ_DENY_CARVEOUTS.contains(&name.to_string_lossy().as_ref()) {
                continue;
            }
            let path = entry.path();
            let Ok(metadata) = std::fs::metadata(&path) else {
                continue;
            };
            let is_dir = metadata.is_dir();
            entries.insert(ValidatorReadDenyEntry {
                path: path.clone(),
                is_dir,
            });
            let canonical = absolutize(&path);
            if canonical != path {
                entries.insert(ValidatorReadDenyEntry {
                    path: canonical,
                    is_dir,
                });
            }
        }
    }
    entries.into_iter().collect()
}

/// Default Anthropic egress plus mission-configured additions, trimmed and
/// de-duplicated in stable order.
pub fn effective_egress(configured: &[String]) -> Vec<String> {
    let mut out: Vec<String> = DEFAULT_EGRESS.iter().map(|s| (*s).to_string()).collect();
    for item in configured {
        let item = item.trim();
        if !item.is_empty() && !out.iter().any(|existing| existing == item) {
            out.push(item.to_string());
        }
    }
    out
}

/// Generate an SBPL profile: deny-by-default, broad read (Seatbelt cannot
/// usefully scope toolchain/dyld reads without breaking `/bin/sh`) with the
/// [`authority_read_deny_paths`]/[`authority_read_deny_dirs`] carve-out,
/// write limited to subpaths of
/// `session_cwd`, the session-private scratch `tmpdir`, and each
/// `extra_write` entry — with the mission metadata of
/// [`mission_write_denies`] carved back OUT by explicit write denies, so the
/// audit log / state snapshot / control inbox / transcripts stay read-only
/// to the session even in checkout mode (where `session_cwd` is the repo
/// root and the mission dir sits under it). `fs` allows network — the profile wraps the agent
/// binary itself, so denying egress bricks Anthropic/API sessions; write
/// containment is the fs-tier promise. `fs+net` restricts outbound TCP to
/// loopback: Seatbelt rejects hostname egress rules (`host must be * or
/// localhost`), so the per-host allowlist is enforced by the run's egress
/// proxy (`crate::egress_proxy`) — the only reachable way out. The
/// operator's real Cargo registry/git caches carry an explicit write deny
/// of their own (13th-pass review, P1 — [`cargo_cache_write_deny_paths`]):
/// the isolated contract home may LINK them in above the copy ceiling, and
/// the linked target must stay read-only under every allow.
///
/// Mandatory validator containment (ticket `validator-mandatory-containment`):
/// when [`SandboxInputs::validator_read_deny_roots`] is non-empty (validator
/// sessions only), a second read-deny block closes the broad read allow over
/// the REAL checkout's source tree — every top-level entry of each root
/// except the `.git`/`.kranz` carve-outs ([`validator_read_deny_entries`]) —
/// plus the `/dev/null` write allow every shell/git needs under deny-default
/// (the gate wrap's documented finding). The root's own listing stays
/// readable (names, never contents — a literal deny on the root breaks
/// `mkdir -p` under the snapshot, which stats every ancestor; the bwrap
/// side cannot express the listing deny at all). The snapshot worktree
/// (under `<root>/.kranz/...`) and the shared git dir stay readable; the
/// validator provably reads only its snapshot's contents. Denies take
/// precedence over the broad allow regardless of clause order (the same
/// guarantee the authority deny above relies on). Every Seatbelt session
/// also keeps `/dev/null` writable: shells, Git, and agent tool runners use
/// it for ordinary redirects even outside validator sessions.
pub fn generate_profile(inputs: &SandboxInputs) -> String {
    let write_paths = write_allowlist(inputs);

    let mut profile = String::new();
    profile.push_str("(version 1)\n");
    profile.push_str("(deny default)\n");
    profile.push('\n');
    profile.push_str("(allow process*)\n");
    profile.push_str("(allow signal (target self))\n");
    profile.push_str("(allow sysctl-read)\n");
    profile.push_str("(allow mach-lookup)\n");
    profile.push_str("(allow mach-register)\n");
    profile.push_str("(allow iokit-open)\n");
    profile.push('\n');
    // Reads stay broad: Seatbelt cannot usefully express "toolchain + dyld +
    // locale" without a long allowlist that still breaks `/bin/sh` redirects.
    // Secrecy is not the fs-tier promise — write containment is — with ONE
    // carve-out: the authority material below.
    profile.push_str("(allow file-read*)\n");
    profile.push('\n');
    // Serve tokens, the repo config, the plaintext lint vocabulary, the
    // hook-status projection, and the control inbox must stay unreadable even
    // under the broad read allow (see authority_read_deny_paths /
    // authority_read_deny_dirs). SBPL denies take precedence over allows
    // regardless of clause order (verified with sandbox-exec), so placing
    // the deny after the allow is documentary.
    let mut deny_literals = std::collections::BTreeSet::new();
    for path in authority_read_deny_paths(inputs) {
        deny_literals.insert(escape_sbpl_literal(&path));
    }
    let mut deny_subpaths = std::collections::BTreeSet::new();
    for dir in authority_read_deny_dirs(inputs) {
        deny_subpaths.insert(escape_sbpl_literal(&dir));
    }
    if !deny_literals.is_empty() || !deny_subpaths.is_empty() {
        profile.push_str("(deny file-read*\n");
        for lit in &deny_subpaths {
            profile.push_str(&format!("  (subpath \"{lit}\")\n"));
        }
        for lit in &deny_literals {
            profile.push_str(&format!("  (literal \"{lit}\")\n"));
        }
        profile.push_str(")\n");
        profile.push('\n');
    }
    // Mandatory validator containment (see the fn doc): read-deny the real
    // checkout's source tree. Directories deny as subpaths (the whole
    // subtree), files as literals. Deny wins over the broad read allow
    // regardless of clause order — placement after it is documentary. The
    // root ITSELF is deliberately NOT denied: a literal deny on the root
    // dir blocks stat/readdir of it, and coreutils `mkdir -p` stats every
    // ancestor of an absolute path — denying the root broke `mkdir -p`
    // under the snapshot (probed 2026-08-04). The root's directory LISTING
    // stays visible (names, never contents) — the same posture the bwrap
    // side is limited to anyway.
    let validator_denies = validator_read_deny_entries(inputs);
    if !validator_denies.is_empty() {
        let mut subpaths = std::collections::BTreeSet::new();
        let mut literals = std::collections::BTreeSet::new();
        for entry in &validator_denies {
            if entry.is_dir {
                subpaths.insert(escape_sbpl_literal(&entry.path));
            } else {
                literals.insert(escape_sbpl_literal(&entry.path));
            }
        }
        profile.push_str("(deny file-read*\n");
        for lit in &subpaths {
            profile.push_str(&format!("  (subpath \"{lit}\")\n"));
        }
        for lit in &literals {
            profile.push_str(&format!("  (literal \"{lit}\")\n"));
        }
        profile.push_str(")\n");
        profile.push('\n');
    }
    // `/dev/null` must stay writable even under deny-default (the gate
    // wrap's documented finding, `gate_profile_extras` — probed
    // 2026-08-03): Git, shells, and agent tool runners open it O_RDWR in
    // ordinary operation. This applies to every session, not only the
    // validator shape above.
    profile.push_str("(allow file-write* (literal \"/dev/null\"))\n");
    profile.push('\n');
    match inputs.enforce {
        crate::types::SandboxEnforce::FsNet => {
            // Loopback-only egress: the session's proxy hops (CONNECT to
            // 127.0.0.1) are legal, and every non-localhost destination is
            // denied here at the kernel boundary — the egress proxy is the
            // only way out and applies the hostname allowlist.
            profile.push_str("(allow network-outbound (remote tcp \"localhost:*\"))\n");
        }
        // `fs` (and Off) must allow network: this profile wraps the agent
        // binary, so `deny network*` bricks API egress. Egress restriction
        // is an `fs+net` concern.
        crate::types::SandboxEnforce::Fs | crate::types::SandboxEnforce::Off => {
            profile.push_str("(allow network*)\n");
        }
    }
    profile.push('\n');
    // Write allowlist: include both the canonical path and the path as given
    // (macOS `/var` ↔ `/private/var`) so shell redirects using either form match.
    profile.push_str("(allow file-write*\n");
    let mut write_literals = std::collections::BTreeSet::new();
    for p in &write_paths {
        write_literals.insert(escape_sbpl_literal(p));
    }
    for raw in [&inputs.session_cwd, &inputs.tmpdir]
        .into_iter()
        .chain(inputs.extra_write.iter())
    {
        write_literals.insert(escape_sbpl_literal(raw));
        write_literals.insert(escape_sbpl_literal(&absolutize(raw)));
    }
    for lit in &write_literals {
        profile.push_str(&format!("  (subpath \"{lit}\")\n"));
    }
    profile.push_str(")\n");
    profile.push('\n');
    // Mission metadata write deny: the allowlist no longer names the mission
    // dir, but in checkout mode `session_cwd` IS the repo root and the
    // mission dir sits under it — without these denies the audit log, state
    // snapshot, control inbox, and transcripts would be writable through the
    // session-cwd subpath allow. SBPL denies take precedence over allows
    // regardless of clause order (the same guarantee the read deny above
    // relies on), so placement after the allow is documentary.
    let write_denies = mission_write_denies(inputs);
    profile.push_str("(deny file-write*\n");
    let mut deny_literals = std::collections::BTreeSet::new();
    for p in &write_denies.files {
        deny_literals.insert(escape_sbpl_literal(p));
    }
    for lit in &deny_literals {
        profile.push_str(&format!("  (literal \"{lit}\")\n"));
    }
    let mut deny_subpaths = std::collections::BTreeSet::new();
    for p in &write_denies.control_dirs {
        deny_subpaths.insert(escape_sbpl_literal(p));
    }
    for lit in &deny_subpaths {
        profile.push_str(&format!("  (subpath \"{lit}\")\n"));
    }
    // Transcripts are `runs/*.jsonl` files directly under the runs dir; the
    // `[^/]*` keeps `runs/` SUBDIRECTORIES (session scratch, preflight
    // worktree) writable.
    let mut deny_regexes = std::collections::BTreeSet::new();
    for p in &write_denies.runs_dirs {
        deny_regexes.insert(escape_sbpl_regex(p));
    }
    for lit in &deny_regexes {
        profile.push_str(&format!("  (regex #\"^{lit}/[^/]*\\.jsonl$\")\n"));
    }
    profile.push_str(")\n");
    profile.push('\n');

    // Authority write deny (2026-09-01 adversarial audit, H2 + H11 — see
    // authority_write_denies for the full why): every path the read deny
    // above names, plus the repo-level `.kranz` stores and every SIBLING
    // mission dir. Under checkout mode `session_cwd` is the repo root, so
    // without this block a contained worker could overwrite the trust root
    // it cannot read, or forge approvals into another mission's inbox.
    // Denies take precedence over allows regardless of clause order, so
    // placement after the write allow is documentary.
    let authority_writes = authority_write_denies(inputs);
    let mut authority_write_literals = std::collections::BTreeSet::new();
    for path in &authority_writes.files {
        authority_write_literals.insert(escape_sbpl_literal(path));
    }
    let mut authority_write_subpaths = std::collections::BTreeSet::new();
    for path in &authority_writes.dirs {
        authority_write_subpaths.insert(escape_sbpl_literal(path));
    }
    // The spawn-time residue the enumeration cannot cover: sealing the
    // DIRECT children of `<repo>/.kranz` and `<repo>/.kranz/missions` stops
    // a session creating a store or a sibling mission dir after the profile
    // was built. `[^/]*` never crosses a separator, so the session's own
    // `<mission>/runs/<scratch>` stays writable.
    let mut sealed_regexes = std::collections::BTreeSet::new();
    for root in sealed_kranz_dir_roots(inputs) {
        sealed_regexes.insert(escape_sbpl_regex(&root));
    }
    if !authority_write_literals.is_empty()
        || !authority_write_subpaths.is_empty()
        || !sealed_regexes.is_empty()
    {
        profile.push_str("(deny file-write*\n");
        for lit in &authority_write_subpaths {
            profile.push_str(&format!("  (subpath \"{lit}\")\n"));
        }
        for lit in &authority_write_literals {
            profile.push_str(&format!("  (literal \"{lit}\")\n"));
        }
        for root in &sealed_regexes {
            profile.push_str(&format!("  (regex #\"^{root}/[^/]*$\")\n"));
        }
        profile.push_str(")\n");
        profile.push('\n');
    }

    // `.git` metadata write deny (2026-09-01 adversarial audit, H3 support —
    // see git_metadata_write_denies): the engine checkpoints with a
    // hardened git handle in the tree the worker controls, so the hook and
    // config surface that turns the next engine-side `git commit` into host
    // execution is denied. Narrow by design — the worker's own role is to
    // commit, so the index, objects, refs and logs stay writable.
    let git_writes = git_metadata_write_denies(inputs);
    let mut git_write_literals = std::collections::BTreeSet::new();
    for path in &git_writes.files {
        git_write_literals.insert(escape_sbpl_literal(path));
    }
    let mut git_write_subpaths = std::collections::BTreeSet::new();
    for path in &git_writes.dirs {
        git_write_subpaths.insert(escape_sbpl_literal(path));
    }
    if !git_write_literals.is_empty() || !git_write_subpaths.is_empty() {
        profile.push_str("(deny file-write*\n");
        for lit in &git_write_subpaths {
            profile.push_str(&format!("  (subpath \"{lit}\")\n"));
        }
        for lit in &git_write_literals {
            profile.push_str(&format!("  (literal \"{lit}\")\n"));
        }
        profile.push_str(")\n");
        profile.push('\n');
    }

    // Operator terminal deny (2026-09-01 adversarial audit, H7 — see
    // operator_tty_paths): the engine's own controlling terminal is denied
    // read, write, AND ioctl. Every child the engine spawns has piped or
    // null stdio, so nothing inside the sandbox needs this device, and the
    // deny is what stops escape-sequence writes and TIOCSTI-class input
    // injection into the operator's shell. Nothing is emitted when the
    // engine has no terminal (a daemon, CI, `kranz serve`).
    let tty_block = tty_deny_block(&operator_tty_paths());
    if !tty_block.is_empty() {
        profile.push_str(&tty_block);
        profile.push('\n');
    }

    profile.push_str("(deny file-write*\n");
    // Match future sibling missions too: enumeration alone would leave an
    // inbox created after this session starts writable under checkout mode.
    if let Some(missions) = inputs
        .mission_dir
        .parent()
        .filter(|path| path.ends_with("missions"))
    {
        for root in [missions.to_path_buf(), absolutize(missions)] {
            let root = escape_sbpl_regex(&root);
            profile.push_str(&format!(
                "  (regex #\"^{root}/[^/]+/(events\\.jsonl(\\.lock)?|state\\.json(\\.tmp)?|estimate\\.json)$\")\n"
            ));
            profile.push_str(&format!("  (regex #\"^{root}/[^/]+/control(/|$)\")\n"));
            profile.push_str(&format!(
                "  (regex #\"^{root}/[^/]+/runs/[^/]*\\.jsonl$\")\n"
            ));
        }
    }
    profile.push_str(")\n");

    // Denying a file alone does not stop renaming its parent directory,
    // which would move authority outside path-based read/write rules.
    // Pin ancestor names without denying ordinary writes to their children.
    let mut pinned_dirs = std::collections::BTreeSet::new();
    for path in authority_read_deny_paths(inputs)
        .into_iter()
        .chain(authority_read_deny_dirs(inputs))
        .chain(mission_write_denies(inputs).control_dirs)
    {
        for parent in path.ancestors().skip(1) {
            pinned_dirs.insert(escape_sbpl_literal(parent));
        }
    }
    profile.push_str("(deny file-write-unlink\n");
    for path in pinned_dirs {
        profile.push_str(&format!("  (literal \"{path}\")\n"));
    }
    if let Some(missions) = inputs
        .mission_dir
        .parent()
        .filter(|p| p.ends_with("missions"))
    {
        for path in [missions.to_path_buf(), absolutize(missions)] {
            profile.push_str(&format!(
                "  (regex #\"^{}/[^/]+(/(control|runs))?$\")\n",
                escape_sbpl_regex(&path)
            ));
        }
    }
    profile.push_str(")\n");

    // Shared-Cargo-cache write deny (13th-pass review, P1 — see
    // cargo_cache_write_deny_paths for the full why): when the shared
    // registry/git cache exceeds the copy ceiling, the isolated contract
    // home LINKS it in, and only an EXPLICIT deny keeps the link target
    // read-only under every allow (an operator extraWrite of $HOME would
    // otherwise re-widen it to worker-authored contract code). Precise
    // scope: registry/ and git/ only. Denies take precedence over allows
    // regardless of clause order (the same guarantee the blocks above
    // rely on), so placement after the allow is documentary.
    let mut cache_denies = std::collections::BTreeSet::new();
    for path in cargo_cache_write_deny_paths() {
        cache_denies.insert(escape_sbpl_literal(&path));
    }
    if !cache_denies.is_empty() {
        profile.push_str("(deny file-write*\n");
        for lit in &cache_denies {
            profile.push_str(&format!("  (subpath \"{lit}\")\n"));
        }
        profile.push_str(")\n");
    }

    profile
}

/// Build the bubblewrap argv tail for running `binary args` under the resolved
/// sandbox. The caller uses program `bwrap` and passes this vector as args.
///
/// Write scope mirrors the Seatbelt profile: the whole filesystem is bound
/// read-only, then `session_cwd`, the session-private scratch `tmpdir`, and
/// each `extra_write` entry are bound writable — the mission dir and the
/// shared system temp root are NOT writable (ticket sandbox-writable-scope).
/// Mission metadata that an rw ancestor bind would otherwise cover (checkout
/// mode) is masked back out, the bwrap analogue of the profile's write deny;
/// the operator's real Cargo registry/git caches get explicit stacked
/// ro-binds for the same reason (13th-pass review — they stay readable, a
/// linked cache is the session's registry, but never writable).
///
/// Mandatory validator containment (ticket `validator-mandatory-containment`
/// — the bwrap analogue of the profile's validator read-deny block): when
/// [`SandboxInputs::validator_read_deny_roots`] is non-empty, each top-level
/// source-tree entry of those roots ([`validator_read_deny_entries`]) is
/// masked — directories shadowed by an empty tmpfs, files by a `/dev/null`
/// ro-bind — so the whole-fs ro-bind no longer exposes the real checkout's
/// contents. The `.git`/`.kranz` carve-outs stay (git needs the shared
/// object store; the snapshot lives under `.kranz`). The root's own
/// directory LISTING stays visible on both tiers (names, never contents):
/// bwrap cannot close it without masking the carve-outs, and the Seatbelt
/// side declines to (a literal deny on the root breaks `mkdir -p` under
/// the snapshot). `/dev/null` needs no allow here — the bwrap argv mounts
/// a real `/dev` (`--dev /dev`).
pub fn bubblewrap_args(
    inputs: &SandboxInputs,
    binary: &Path,
    args: &[String],
) -> crate::error::Result<Vec<String>> {
    let mut out = vec![
        "--die-with-parent".to_string(),
        "--ro-bind".to_string(),
        "/".to_string(),
        "/".to_string(),
        "--dev".to_string(),
        "/dev".to_string(),
        "--proc".to_string(),
        "/proc".to_string(),
        // Namespace set (2026-09-01 adversarial audit, H8). Before it the
        // argv unshared ONLY the network namespace, and only under `fs+net`:
        //
        // - `--unshare-pid` is what makes `--proc /proc` mean what the mount
        //   above assumes. Without it the contained agent sees HOST procfs
        //   and can read `/proc/<engine pid>/environ` — precisely the set
        //   `agent_env`'s env_clear exists to keep away from a
        //   prompt-injectable child — on any host with
        //   `kernel.yama.ptrace_scope = 0`. It also stops the agent
        //   signalling the engine or any same-uid host process.
        // - `--unshare-ipc` closes the System V / POSIX IPC channel to host
        //   processes.
        // - `--unshare-uts` and `--unshare-cgroup-try` keep hostname and
        //   cgroup views from being host-identifying or host-mutable. The
        //   `-try` suffix is load-bearing (follow-up review, M-8): cgroup
        //   namespaces need Linux >= 4.6 and are unavailable in some nested
        //   container and hardened-kernel environments, where the plain
        //   `--unshare-cgroup` makes bwrap EXIT non-zero — and every resolver
        //   in this file fails closed, so the whole session would die rather
        //   than degrade by one namespace. `--unshare-pid`/`ipc`/`uts` are
        //   long-supported and stay unconditional.
        // - `--new-session` drops the controlling terminal, which is the
        //   Linux half of the TIOCSTI escape H7 names on macOS (still live
        //   on kernels built with CONFIG_LEGACY_TIOCSTI). Safe here: every
        //   child the engine spawns gets piped or null stdio, and the pty
        //   harness passes its OWN slave fd rather than relying on an
        //   inherited ctty.
        //
        // Unconditional, unlike `--unshare-net` below: none of these is an
        // egress decision, and `fs` is a containment tier too.
        "--unshare-pid".to_string(),
        "--unshare-ipc".to_string(),
        "--unshare-uts".to_string(),
        "--unshare-cgroup-try".to_string(),
        "--new-session".to_string(),
    ];
    if inputs.enforce == crate::types::SandboxEnforce::FsNet {
        out.push("--unshare-net".to_string());
    }
    for path in write_allowlist(inputs) {
        let path = path.display().to_string();
        out.push("--bind".to_string());
        out.push(path.clone());
        out.push(path);
    }
    // Keep the mission namespace read-only, including siblings created
    // after spawn. A validator snapshot or private scratch nested here
    // gets its own writable bind back before the metadata masks below.
    if let Some(missions) = inputs
        .mission_dir
        .parent()
        .filter(|path| path.ends_with("missions") && path.is_dir())
    {
        let missions = absolutize(missions);
        let display = missions.display().to_string();
        out.extend(["--ro-bind".to_string(), display.clone(), display]);
        for private in [&inputs.session_cwd, &inputs.tmpdir] {
            let private = absolutize(private);
            if private.starts_with(&missions) && private != missions {
                let display = private.display().to_string();
                out.extend(["--bind".to_string(), display.clone(), display]);
            }
        }
    }
    // The bwrap analogue of the profile's shared-Cargo-cache write deny
    // (13th-pass review, P1 — cargo_cache_write_deny_paths): the `/`
    // ro-bind already mounts the real caches read-only, but an rw bind
    // covering an ancestor (an extraWrite of $HOME) would silently
    // re-widen them — stack an explicit ro-bind OVER each cache dir
    // present at spawn (later binds win; the destination must exist,
    // hence the is_dir filter). The dir stays READABLE — a linked cache
    // is the session/gate's registry — only writes close. This
    // behavior is also enforced by the private Cargo-home namespace below,
    // which keeps later credential/cache creation out of the session.
    let cache_ro_binds: std::collections::BTreeSet<String> = cargo_cache_write_deny_paths()
        .iter()
        .filter(|path| path.is_dir())
        .map(|path| path.display().to_string())
        .collect();
    for bind in &cache_ro_binds {
        out.push("--ro-bind".to_string());
        out.push(bind.clone());
        out.push(bind.clone());
    }
    // The bwrap analogue of the profile's authority and `.git` write denies
    // (2026-09-01 adversarial audit, H2 + H11 + H3 support): bwrap has no
    // per-path write deny to stack over an rw bind, so each denied path is
    // ro-bound OVER ITSELF — the contents stay READABLE (git cannot run
    // without its own config, and the Seatbelt side denies writes only) while
    // every write closes. Later binds win: install these after the initial
    // writable roots, and restore them after any private-root rebind below.
    //
    // Private authority directory views below close both reads and writes,
    // including authority files created after launch. These extra ro-binds
    // cover readable policy and Git metadata outside those views. For that
    // Git configuration surface, active absent inputs are refused before
    // spawn. Inactive config.worktree cannot become active while the main
    // config is immutable. Writable self-binds pin metadata directory nodes
    // against rename without closing the index/object/ref lockfile paths.
    // Do not directly bind READ-denied paths: their private directory view
    // owns the destination. A host bind stacked over a mask would restore
    // the credential the mask is meant to hide.
    // The write-deny set is a superset of the read-deny set by
    // construction, so subtract the masked paths and everything beneath a
    // masked directory before binding.
    let masked_files: Vec<PathBuf> = authority_read_deny_paths(inputs)
        .iter()
        .map(|p| lexical_absolute(p))
        .collect();
    let masked_dirs: Vec<PathBuf> = authority_read_deny_dirs(inputs)
        .iter()
        .map(|p| lexical_absolute(p))
        .collect();
    let is_masked = |path: &Path| -> bool {
        let abs = lexical_absolute(path);
        masked_files.contains(&abs) || masked_dirs.iter().any(|d| abs.starts_with(d))
    };
    let git_mount_nodes = git_metadata_mount_nodes(inputs);
    for node in &git_mount_nodes {
        let node = node.display().to_string();
        out.extend(["--bind".to_string(), node.clone(), node]);
    }
    let authority_writes = authority_write_denies(inputs);
    let git_writes = git_metadata_write_denies(inputs);
    let write_ro_binds: std::collections::BTreeSet<String> = authority_writes
        .files
        .iter()
        .chain(authority_writes.dirs.iter())
        .filter(|path| path.exists())
        .chain(
            git_writes
                .files
                .iter()
                .filter(|path| path.is_file() && !path.is_symlink()),
        )
        .chain(git_writes.dirs.iter().filter(|path| path.is_dir()))
        .filter(|path| !is_masked(path))
        .map(|path| lexical_absolute(path).display().to_string())
        .collect();
    for bind in &write_ro_binds {
        out.push("--ro-bind".to_string());
        out.push(bind.clone());
        out.push(bind.clone());
    }
    // Reject hostile metadata leaves before constructing read-only views.
    // Missing state/transcript files stay absent in the private namespace;
    // no host-side state.json.tmp placeholder is needed.
    let write_denies = mission_write_denies(inputs);
    for path in &write_denies.files {
        match std::fs::symlink_metadata(path) {
            Ok(metadata) if metadata.file_type().is_file() => {}
            Ok(_) => {
                return Err(crate::error::EngineError::InvalidState(format!(
                    "bwrap mask prep: {} exists and is not a regular file",
                    path.display()
                )))
            }
            Err(error) if error.kind() == std::io::ErrorKind::NotFound => {}
            Err(error) => return Err(error.into()),
        }
    }
    let authority_dirs: Vec<_> = authority_read_deny_dirs(inputs)
        .iter()
        .map(|path| absolutize(path))
        .collect();
    let authority_masks = authority_directory_masks(inputs);
    for mask in &authority_masks {
        let display = mask.path.display().to_string();
        out.extend(["--tmpfs".to_string(), display.clone()]);
        for path in &mask.visible_entries {
            let path = path.display().to_string();
            // Ordinary entries can disappear after enumeration (for example,
            // another gate's temporary cache). Leaving a missing entry hidden
            // is safe; the enclosing mask and read-only remount remain required.
            out.extend(["--ro-bind-try".to_string(), path.clone(), path]);
        }
        // A deeper mask may replace an entry hidden by this one (e.g.
        // HOME/.kranz below a HOME mask for a missing Cargo home). Reserve
        // its empty mountpoint in the private tmpfs before sealing it.
        for nested in &authority_masks {
            if nested.path != mask.path
                && nested.path.starts_with(&mask.path)
                && !mask
                    .visible_entries
                    .iter()
                    .any(|entry| nested.path.starts_with(entry))
            {
                out.extend(["--dir".to_string(), nested.path.display().to_string()]);
            }
        }
        out.extend(["--remount-ro".to_string(), display]);
        // A snapshot or session-private scratch under .kranz remains writable.
        // Later (deeper) masks still hide its own authority directories.
        for private in [&inputs.session_cwd, &inputs.tmpdir] {
            let private = absolutize(private);
            if private != mask.path
                && private.starts_with(&mask.path)
                && !authority_dirs
                    .iter()
                    .any(|denied| private.starts_with(denied))
            {
                let path = private.display().to_string();
                out.extend(["--bind".to_string(), path.clone(), path.clone()]);
                for node in git_mount_nodes
                    .iter()
                    .filter(|node| node.starts_with(&private))
                {
                    let node = node.display().to_string();
                    out.extend(["--bind".to_string(), node.clone(), node]);
                }
                // Host-source binds replace every nested mount. Restore the
                // write denies this private root just covered, before deeper
                // authority masks hide their secrets. Rebinding denied host
                // directories after those masks would expose them again.
                let restored_denies: std::collections::BTreeSet<_> = cache_ro_binds
                    .iter()
                    .chain(&write_ro_binds)
                    .filter_map(|denied| {
                        let denied_path = Path::new(denied);
                        if denied_path.starts_with(&private) {
                            Some(denied)
                        } else if private.starts_with(denied_path) {
                            Some(&path)
                        } else {
                            None
                        }
                    })
                    .collect();
                for denied in restored_denies {
                    out.extend(["--ro-bind".to_string(), denied.clone(), denied.clone()]);
                }
            }
        }
    }
    // The bwrap analogue of the profile's validator read-deny block (ticket
    // validator-mandatory-containment — see the fn doc): shadow each real
    // source-tree entry so the whole-fs ro-bind stops exposing it. Dirs get
    // an empty tmpfs (the existing control/-shadow idiom), files a
    // /dev/null ro-bind (the authority-mask idiom). Entries were enumerated
    // from the live fs and exist at spawn; later binds win, and this block
    // lands after every bind and authority view, so neither can re-expose a
    // denied entry — the carve-outs (`.git`, `.kranz`) were never in the
    // set, so the snapshot and the shared git dir stay as their binds left
    // them.
    for entry in validator_read_deny_entries(inputs) {
        let display = entry.path.display().to_string();
        if entry.is_dir {
            out.push("--tmpfs".to_string());
            out.push(display);
        } else {
            out.push("--ro-bind".to_string());
            out.push("/dev/null".to_string());
            out.push(display);
        }
    }
    out.push("--chdir".to_string());
    out.push(absolutize(&inputs.session_cwd).display().to_string());
    out.push("--".to_string());
    out.push(binary.display().to_string());
    out.extend(args.iter().cloned());
    Ok(out)
}

/// Write the profile to a uniquely-named file under `dir`, returning its path.
pub fn write_profile_file(dir: &Path, profile: &str) -> std::io::Result<PathBuf> {
    std::fs::create_dir_all(dir)?;
    let path = dir.join(format!("kranz-sandbox-{}.sb", uuid::Uuid::new_v4()));
    std::fs::write(&path, profile)?;
    Ok(path)
}

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

    #[cfg(target_os = "macos")]
    use std::sync::Mutex;

    /// `extra_write: ["~/cache"]` must resolve against the platform home.
    /// Regression: this read `HOME` only, which a natively launched
    /// `kranz.exe` does not have (Git Bash injects one; cmd/PowerShell/
    /// Explorer do not), so the entry stayed the literal `~/cache` and the
    /// sandbox grant silently targeted a directory named `~`.
    #[test]
    fn expand_tilde_uses_the_platform_home_variable() {
        assert_eq!(
            expand_tilde("relative/path"),
            PathBuf::from("relative/path")
        );
        assert_eq!(expand_tilde("~notatilde"), PathBuf::from("~notatilde"));

        let home = std::env::var_os(if cfg!(windows) { "USERPROFILE" } else { "HOME" })
            .expect("the platform home variable is always set on a real host");
        let expanded = expand_tilde("~/cache");
        assert_eq!(expanded, PathBuf::from(&home).join("cache"));
        assert!(
            expanded.is_absolute(),
            "an expanded home path must be absolute: {expanded:?}"
        );

        #[cfg(windows)]
        assert_eq!(expand_tilde(r"~\cache"), PathBuf::from(&home).join("cache"));
    }

    #[cfg(target_os = "macos")]
    static SANDBOX_EXEC_TEST_LOCK: Mutex<()> = Mutex::new(());

    #[cfg(target_os = "macos")]
    fn sandbox_exec_can_apply() -> bool {
        let found = std::process::Command::new("which")
            .arg("sandbox-exec")
            .output()
            .map(|o| o.status.success())
            .unwrap_or(false);
        if !found {
            crate::test_capability::skip(
                crate::test_capability::capability::SANDBOX_EXEC,
                "sandbox-exec not found on this host",
            );
            return false;
        }

        let smoke = std::process::Command::new("sandbox-exec")
            .arg("-p")
            .arg("(version 1)\n(allow default)\n")
            .arg("/usr/bin/true")
            .output();
        match smoke {
            Ok(output) if output.status.success() => true,
            Ok(output) => {
                eprintln!(
                    "sandbox-exec cannot apply a smoke profile on this host; skipping: {}",
                    String::from_utf8_lossy(&output.stderr)
                );
                false
            }
            Err(e) => {
                eprintln!("sandbox-exec smoke probe failed; skipping: {e}");
                false
            }
        }
    }

    #[cfg(target_os = "linux")]
    fn bwrap_can_apply() -> bool {
        if !command_available("bwrap") {
            crate::test_capability::skip(
                crate::test_capability::capability::BWRAP,
                "bwrap not found on this host",
            );
            return false;
        }

        let smoke = std::process::Command::new("bwrap")
            .args([
                "--die-with-parent",
                "--ro-bind",
                "/",
                "/",
                "--dev",
                "/dev",
                "--proc",
                "/proc",
                "--",
                "/bin/true",
            ])
            .output();
        match smoke {
            Ok(output) if output.status.success() => true,
            Ok(output) => {
                eprintln!(
                    "bwrap cannot apply a smoke sandbox on this host; skipping: {}",
                    String::from_utf8_lossy(&output.stderr)
                );
                false
            }
            Err(e) => {
                eprintln!("bwrap smoke probe failed; skipping: {e}");
                false
            }
        }
    }

    fn inputs(
        session_cwd: &Path,
        mission_dir: &Path,
        tmpdir: &Path,
        extra: Vec<PathBuf>,
    ) -> SandboxInputs {
        SandboxInputs {
            enforce: crate::types::SandboxEnforce::Fs,
            session_cwd: session_cwd.to_path_buf(),
            mission_dir: mission_dir.to_path_buf(),
            tmpdir: tmpdir.to_path_buf(),
            extra_write: extra,
            egress: Vec::new(),
            validator_read_deny_roots: Vec::new(),
        }
    }

    #[test]
    fn sandbox_profile_contains_required_clauses() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let extra = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(
            session.path(),
            mission.path(),
            tmp.path(),
            vec![extra.path().to_path_buf()],
        ));

        assert!(profile.contains("(version 1)"));
        assert!(profile.contains("(deny default)"));
        assert!(profile.contains("(allow file-read*)"));
        assert!(profile.contains("(allow file-write* (literal \"/dev/null\"))"));
        // `fs` must allow network so the sandboxed agent can reach its API.
        assert!(profile.contains("(allow network*)"));
        assert!(!profile.contains("(deny network*)"));

        let session_abs = absolutize(session.path());
        let tmp_abs = absolutize(tmp.path());
        let extra_abs = absolutize(extra.path());

        // The writable set: session cwd, the session-private scratch, and
        // each extraWrite entry.
        for p in [&session_abs, &tmp_abs, &extra_abs] {
            let expected = format!("(subpath \"{}\")", escape_sbpl_literal(p));
            assert!(
                profile.contains(&expected),
                "profile missing subpath rule for {:?}:\n{}",
                p,
                profile
            );
        }

        // The mission dir is NOT writable (its engine-owned metadata carries
        // explicit write denies instead — see
        // sandbox_profile_denies_mission_metadata_writes).
        let mission_abs = absolutize(mission.path());
        let mission_rule = format!("(subpath \"{}\")", escape_sbpl_literal(&mission_abs));
        assert!(
            !profile.contains(&mission_rule),
            "profile must not allow writes to the whole mission dir:\n{profile}"
        );
    }

    #[test]
    fn sandbox_profile_denies_authority_material_reads() {
        let _env = crate::agent_env::EnvTestGuard::engage(&[]);
        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        std::fs::create_dir_all(&mission).unwrap();
        let tmp = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(repo.path(), &mission, tmp.path(), vec![]));

        // Broad reads stay, with the authority material carved out by explicit
        // denies (SBPL denies take precedence over the allow).
        assert!(profile.contains("(allow file-read*)"));
        assert!(profile.contains("(deny file-read*"));
        let kranz_dir = repo.path().join(".kranz");
        for name in [
            "serve.token",
            "serve.read.token",
            "config.json",
            // The plaintext clean-room lint vocabulary (14th-pass review).
            "domain-terms.local",
        ] {
            for base in [kranz_dir.clone(), absolutize(&kranz_dir)] {
                let expected = format!("(literal \"{}\")", escape_sbpl_literal(&base.join(name)));
                assert!(
                    profile.contains(&expected),
                    "profile missing read deny for {}:\n{profile}",
                    base.join(name).display()
                );
            }
        }
        // The cargo registry token file is denied too (CARGO_HOME crosses
        // into child envs for cache locality; its credentials must not
        // ride along).
        assert!(
            profile.contains("credentials.toml"),
            "profile missing read deny for cargo credentials:\n{profile}"
        );
        if let Some(global) = crate::paths::global_config() {
            let global_dir = global.parent().unwrap();
            for operation in ["(deny file-read*", "(deny file-write*"] {
                for protected in [&global, global_dir] {
                    assert!(
                        profile.split(operation).skip(1).any(|block| {
                            block
                                .split("\n)\n")
                                .next()
                                .unwrap()
                                .contains(&escape_sbpl_literal(protected))
                        }),
                        "missing {operation} rule for {}",
                        protected.display()
                    );
                }
            }
        }
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_checkout_denies_authority_writes_and_future_sibling_inboxes() {
        use std::process::Command;
        let root = tempfile::tempdir().unwrap();
        let root = root.path().canonicalize().unwrap();
        let mission = root.join(".kranz/missions/m-current");
        std::fs::create_dir_all(&mission).unwrap();
        let config = root.join(".kranz/config.json");
        let config_target = root.join("operator-config.json");
        std::fs::write(&config_target, "original").unwrap();
        std::os::unix::fs::symlink(&config_target, &config).unwrap();
        let scratch = root.join("scratch");
        std::fs::create_dir(&scratch).unwrap();
        let profile = generate_profile(&inputs(&root, &mission, &scratch, vec![]));
        // Create a sibling after generating the profile to cover future
        // missions rather than relying on a spawn-time directory listing.
        let sibling = root.join(".kranz/missions/m-later/control");
        std::fs::create_dir_all(&sibling).unwrap();
        let run = |script: &str, path: &Path| {
            Command::new("sandbox-exec")
                .args(["-p", &profile, "/bin/sh", "-c", script, "audit"])
                .arg(path)
                .output()
                .unwrap()
        };
        let probe = run("exit 0", &root);
        if !probe.status.success()
            && String::from_utf8_lossy(&probe.stderr).contains("sandbox_apply")
        {
            eprintln!("SKIP-UNDER-WRAP: nested sandbox unavailable");
            return;
        }
        assert!(probe.status.success(), "{probe:?}");
        for protected in [
            config.clone(),
            config_target.clone(),
            sibling.join("forged.json"),
            sibling.parent().unwrap().join("events.jsonl"),
        ] {
            assert!(
                !run("printf forged > \"$1\"", &protected).status.success(),
                "wrote {}",
                protected.display()
            );
        }
        assert_eq!(std::fs::read_to_string(config).unwrap(), "original");
        assert!(
            !run("cat \"$1\"", &config_target).status.success(),
            "the symlink's target must carry the same authority read denial"
        );
        assert!(!sibling.join("forged.json").exists());
        assert!(
            !run(
                "ln \"$1/.kranz/config.json\" \"$1/authority-hardlink\"",
                &root
            )
            .status
            .success(),
            "a hard link must not move authority outside the read deny"
        );
        assert!(
            !run("mv \"$1/.kranz\" \"$1/moved-authority\"", &root)
                .status
                .success(),
            "renaming the authority parent must not move it outside its deny rules"
        );
        assert!(run("printf feature > \"$1\"", &root.join("feature.txt"))
            .status
            .success());
        assert!(run("printf scratch > \"$1\"", &scratch.join("work.txt"))
            .status
            .success());
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_global_authority_is_denied_when_created_after_profile() {
        if crate::agent_env::isolated_global_home_test(
            "sandbox::tests::sandbox_global_authority_is_denied_when_created_after_profile",
        ) {
            return;
        }
        let dir = tempfile::tempdir().unwrap();
        let root = dir.path().canonicalize().unwrap();
        let home = root.join("operator");
        let alias = root.join("operator-alias");
        std::fs::create_dir(&home).unwrap();
        std::os::unix::fs::symlink(&home, &alias).unwrap();
        let session = root.join("session");
        let mission = session.join(".kranz/missions/m-test");
        let scratch = root.join("scratch");
        std::fs::create_dir_all(&mission).unwrap();
        std::fs::create_dir(&scratch).unwrap();
        let profile = {
            let _env = crate::agent_env::EnvTestGuard::engage(&[("HOME", alias.to_str().unwrap())]);
            generate_profile(&inputs(&session, &mission, &scratch, vec![home.clone()]))
        };
        let authority = home.join(".kranz/serve/later.token");
        std::fs::create_dir_all(authority.parent().unwrap()).unwrap();
        std::fs::write(&authority, "fake-authority").unwrap();
        let output = std::process::Command::new("sandbox-exec")
            .args(["-p", &profile, "/bin/sh", "-c",
                "printf witness > \"$1/witness\" || exit 2; if cat \"$2\"; then exit 3; fi; if printf forged > \"$2\"; then exit 4; fi",
                "test"])
            .arg(&session).arg(&authority).output().unwrap();
        if String::from_utf8_lossy(&output.stderr).contains("sandbox_apply") {
            eprintln!("SKIP-UNDER-WRAP: nested sandbox unavailable");
            return;
        }
        assert!(output.status.success(), "{output:?}");
        assert!(session.join("witness").exists());
        assert_eq!(
            std::fs::read_to_string(authority).unwrap(),
            "fake-authority"
        );
    }

    /// Composition audit (ticket `config-fail-open-audit`): the effective
    /// egress list EXTENDS the compiled-in Anthropic floor — a mission's
    /// configured `egress[]` (and, downstream, its operator-approved egress
    /// grants) can only add destinations, never drop or narrow the defaults.
    /// A replace-shaped regression here strands the sandboxed session's own
    /// API access, or worse, goes unnoticed while the operator believes the
    /// floor is still composed in.
    #[test]
    fn composition_audit_effective_egress_extends_never_replaces_the_default_floor() {
        let configured = vec![
            " crates.io:443 ".to_string(),       // trimmed on the way in
            "api.anthropic.com:443".to_string(), // a duplicate of the floor
            "registry.npmjs.org:443".to_string(),
        ];
        let out = effective_egress(&configured);
        assert_eq!(
            out,
            vec![
                "api.anthropic.com:443".to_string(),
                "*.anthropic.com:443".to_string(),
                "crates.io:443".to_string(),
                "registry.npmjs.org:443".to_string(),
            ]
        );
        // An empty configured list still yields the full default floor.
        assert_eq!(effective_egress(&[]).len(), DEFAULT_EGRESS.len());
    }

    /// Composition audit: `extraWrite` EXTENDS the writable floor (session
    /// cwd + session-private scratch) — the floor itself is not configurable
    /// away, so no config shape can un-write the session's own worktree or
    /// its private scratch.
    #[test]
    fn composition_audit_extra_write_extends_never_replaces_the_writable_floor() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let extra = tempfile::tempdir().unwrap();
        let inputs = inputs(
            session.path(),
            mission.path(),
            tmp.path(),
            vec![extra.path().to_path_buf()],
        );
        let writable = write_allowlist(&inputs);
        for floor in [absolutize(session.path()), absolutize(tmp.path())] {
            assert!(
                writable.contains(&floor),
                "the writable floor {floor:?} must survive any extraWrite list"
            );
        }
        assert!(writable.contains(&absolutize(extra.path())));
    }

    /// Composition audit: the explicit deny sets (mission metadata writes,
    /// authority reads) survive an `extraWrite` broad enough to COVER them.
    /// SBPL denies take precedence over every allow regardless of clause
    /// order, so the deny clauses must still be emitted when the allow side
    /// is at its widest — this is the deny-wins pin for the sandbox surface.
    #[test]
    fn composition_audit_explicit_denies_survive_a_covering_extra_write_allow() {
        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        std::fs::create_dir_all(&mission).unwrap();
        let tmp = tempfile::tempdir().unwrap();
        // extraWrite = the repo root: every mission file now sits under an
        // allowed subpath — the widest realistic allow shape.
        let profile = generate_profile(&inputs(
            repo.path(),
            &mission,
            tmp.path(),
            vec![repo.path().to_path_buf()],
        ));
        // The covering allow IS emitted...
        assert!(
            profile.contains(&format!(
                "(subpath \"{}\")",
                escape_sbpl_literal(&absolutize(repo.path()))
            )),
            "the covering extraWrite allow must be present:\n{profile}"
        );
        // ...and the metadata write denies still are too: the audit log,
        // state snapshot, and control inbox stay unwritable through the
        // allow because SBPL denies win over it.
        assert!(profile.contains("(deny file-write*"));
        for name in ["events.jsonl", "state.json"] {
            assert!(
                profile.contains(&escape_sbpl_literal(&mission.join(name))),
                "the write deny for {name} must survive the covering allow:\n{profile}"
            );
        }
        // Authority reads (serve.token) stay denied under the broad read
        // allow for the same reason.
        assert!(
            profile.contains(&escape_sbpl_literal(
                &repo.path().join(".kranz").join("serve.token")
            )),
            "the read deny for serve.token must survive the covering allow:\n{profile}"
        );
    }

    #[test]
    fn bubblewrap_args_mask_authority_material_with_dev_null() {
        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        std::fs::create_dir_all(&mission).unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let serve_token = repo.path().join(".kranz").join("serve.token");
        std::fs::write(&serve_token, "secret").unwrap();

        let args = bubblewrap_args(
            &inputs(repo.path(), &mission, tmp.path(), vec![]),
            Path::new("/usr/bin/claude"),
            &[],
        )
        .unwrap();
        let joined = args.join(" ");

        let expected = format!(
            "--tmpfs {}",
            absolutize(serve_token.parent().unwrap()).display()
        );
        assert!(
            joined.contains(&expected),
            "missing private authority directory: {args:?}"
        );
        // Neither existing nor future credentials get a bind back into it.
        assert!(!joined.contains("serve.token"));
        assert!(
            !joined.contains("serve.read.token"),
            "future authority files must not get a host bind: {args:?}"
        );
    }

    #[test]
    fn sandbox_profile_denies_mission_metadata_writes() {
        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        std::fs::create_dir_all(&mission).unwrap();
        let scratch = tempfile::tempdir().unwrap();

        // Checkout-mode shape: the session cwd is the repo root, an ANCESTOR
        // of the mission dir — without explicit write denies the audit log,
        // state snapshot, control inbox, and transcripts would be writable
        // through the session-cwd subpath allow.
        let profile = generate_profile(&inputs(repo.path(), &mission, scratch.path(), vec![]));

        assert!(
            profile.contains("(deny file-write*"),
            "missing write deny block:\n{profile}"
        );
        for name in MISSION_METADATA_FILES {
            for base in [mission.clone(), absolutize(&mission)] {
                let expected = format!("(literal \"{}\")", escape_sbpl_literal(&base.join(name)));
                assert!(
                    profile.contains(&expected),
                    "profile missing write deny for {}:\n{profile}",
                    base.join(name).display()
                );
            }
        }
        for base in [mission.clone(), absolutize(&mission)] {
            let control = format!(
                "(subpath \"{}\")",
                escape_sbpl_literal(&base.join("control"))
            );
            assert!(
                profile.contains(&control),
                "profile missing control/ write deny:\n{profile}"
            );
            let runs = format!(
                "(regex #\"^{}/[^/]*\\.jsonl$\")",
                escape_sbpl_regex(&base.join("runs"))
            );
            assert!(
                profile.contains(&runs),
                "profile missing transcript write deny:\n{profile}"
            );
        }
        // The mission dir root itself is not in the allow set.
        let mission_rule = format!(
            "(subpath \"{}\")",
            escape_sbpl_literal(&absolutize(&mission))
        );
        assert!(
            !profile.contains(&mission_rule),
            "the whole mission dir must not be writable:\n{profile}"
        );
    }

    /// 13th-pass review (P1): above the copy ceiling the isolated contract
    /// Cargo home LINKS the operator's registry/git caches in — the profile
    /// must deny writes to those REAL cache dirs (raw AND canonical forms)
    /// so the linked target stays read-only under every allow. The deny is
    /// PRECISE: the two cache dirs, never the whole cargo home (rustup/cargo
    /// binaries keep their ordinary posture).
    #[test]
    fn cache_write_deny_profile_denies_real_cache_dirs_precisely() {
        let cargo = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(cargo.path().join("registry")).unwrap();
        std::fs::create_dir_all(cargo.path().join("git")).unwrap();
        let _guard = crate::agent_env::EnvTestGuard::engage(&[(
            "CARGO_HOME",
            cargo.path().to_str().expect("utf-8 temp path"),
        )]);
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let scratch = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(
            session.path(),
            mission.path(),
            scratch.path(),
            vec![],
        ));
        for base in [cargo.path().to_path_buf(), absolutize(cargo.path())] {
            for name in ["registry", "git"] {
                let expected = format!("(subpath \"{}\")", escape_sbpl_literal(&base.join(name)));
                assert!(
                    profile.contains(&expected),
                    "profile missing cache write deny for {}:\n{profile}",
                    base.join(name).display()
                );
            }
        }
        // Precision: the cargo home ITSELF is not in the deny set — the
        // closing `"` after the home path makes this an exact-line check
        // (the registry/git lines carry a longer path and cannot match).
        for base in [cargo.path().to_path_buf(), absolutize(cargo.path())] {
            let whole_home = format!("(subpath \"{}\")", escape_sbpl_literal(&base));
            assert!(
                !profile.contains(&whole_home),
                "the deny must be precise to the cache dirs, not the whole cargo home:\n{profile}"
            );
        }
    }

    /// The bwrap analogue: the real cache dirs present at spawn get explicit
    /// ro-binds stacked AFTER the rw binds (later binds win — an rw
    /// extraWrite covering an ancestor must not re-widen them), and absent
    /// dirs are skipped (bwrap requires the destination to exist).
    #[test]
    fn cache_write_deny_bwrap_stacks_ro_binds_over_real_cache() {
        let cargo = tempfile::tempdir().unwrap();
        std::fs::create_dir_all(cargo.path().join("registry")).unwrap();
        // git/ deliberately absent → not bound (the is_dir filter).
        let _guard = crate::agent_env::EnvTestGuard::engage(&[(
            "CARGO_HOME",
            cargo.path().to_str().expect("utf-8 temp path"),
        )]);
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let scratch = tempfile::tempdir().unwrap();

        let args = bubblewrap_args(
            &inputs(session.path(), mission.path(), scratch.path(), vec![]),
            Path::new("/usr/bin/claude"),
            &[],
        )
        .unwrap();
        let joined = args.join(" ");

        let registry = absolutize(&cargo.path().join("registry"));
        let expected = format!("--ro-bind {0} {0}", registry.display());
        assert!(
            joined.contains(&expected),
            "missing stacked ro-bind for the real registry cache: {args:?}"
        );
        let git_cache = cargo.path().join("git");
        assert!(
            !joined.contains(&git_cache.display().to_string()),
            "an absent cache dir must not be bound: {args:?}"
        );
        // Ordering is load-bearing: the cache ro-bind must land AFTER every
        // rw `--bind`, or a wide writable root would re-cover it.
        let last_rw = args
            .iter()
            .rposition(|arg| arg == "--bind")
            .expect("the writable roots are rw-bound");
        let registry_arg = registry.display().to_string();
        let cache_pos = args
            .windows(3)
            .position(|w| w[0] == "--ro-bind" && w[1] == registry_arg && w[2] == registry_arg)
            .expect("the cache ro-bind pair exists");
        assert!(
            cache_pos > last_rw,
            "the cache ro-bind must stack after the rw binds: {args:?}"
        );
    }

    #[test]
    fn sandbox_profile_keeps_sibling_temp_neighbors_unwritable() {
        // The worktree-mode layout the finding named: integration/feature
        // worktrees for ALL missions sit side by side under the shared temp
        // root. The session's own worktree + private scratch must be
        // writable; the sibling mission's worktree, the sibling's scratch,
        // and the shared temp root itself must not.
        let root = tempfile::tempdir().unwrap();
        let session = root.path().join("kranz-wt-aaa-m1-f-1-1");
        let scratch = root.path().join("kranz-worker-home-sess-1");
        let sibling = root.path().join("kranz-wt-bbb-m2-_integration");
        let sibling_scratch = root.path().join("kranz-worker-home-sess-2");
        for d in [&session, &scratch, &sibling, &sibling_scratch] {
            std::fs::create_dir_all(d).unwrap();
        }
        let mission = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(&session, mission.path(), &scratch, vec![]));

        for allowed in [&session, &scratch] {
            let expected = format!(
                "(subpath \"{}\")",
                escape_sbpl_literal(&absolutize(allowed))
            );
            assert!(
                profile.contains(&expected),
                "profile missing allow for {}:\n{profile}",
                allowed.display()
            );
        }
        for denied in [&sibling, &sibling_scratch, &root.path().to_path_buf()] {
            let rule = format!("(subpath \"{}\")", escape_sbpl_literal(&absolutize(denied)));
            assert!(
                !profile.contains(&rule),
                "{} must not be writable:\n{profile}",
                denied.display()
            );
        }
    }

    #[test]
    fn bubblewrap_args_mask_mission_metadata() {
        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        let runs = mission.join("runs");
        std::fs::create_dir_all(&runs).unwrap();
        let scratch = tempfile::tempdir().unwrap();
        // Engine-owned metadata present at spawn.
        let events = mission.join("events.jsonl");
        let state = mission.join("state.json");
        let transcript = runs.join("run-1.jsonl");
        let denials = runs.join("egress-denials.jsonl");
        for f in [&events, &state, &transcript, &denials] {
            std::fs::write(f, "engine").unwrap();
        }
        let control = mission.join("control");
        std::fs::create_dir_all(&control).unwrap();
        // A runs/ SUBDIRECTORY of session scratch: its jsonl files are not
        // transcripts and must NOT be masked.
        let contract_home = runs.join("contract-home");
        std::fs::create_dir_all(&contract_home).unwrap();
        let scratch_jsonl = contract_home.join("notes.jsonl");
        std::fs::write(&scratch_jsonl, "session").unwrap();

        let args = bubblewrap_args(
            &inputs(repo.path(), &mission, scratch.path(), vec![]),
            Path::new("/usr/bin/claude"),
            &[],
        )
        .unwrap();
        let joined = args.join(" ");

        for path in [&events, &state, &mission.join("runs")] {
            let path = absolutize(path).display().to_string();
            assert!(
                joined.contains(&format!("--ro-bind-try {path} {path}")),
                "metadata must remain read-only: {args:?}"
            );
        }
        let mission_abs = absolutize(&mission).display().to_string();
        assert!(args
            .windows(2)
            .any(|pair| pair[0] == "--tmpfs" && pair[1] == mission_abs));
        assert!(
            !args.windows(3).any(|part| {
                matches!(part[0].as_str(), "--ro-bind" | "--ro-bind-try")
                    && part[1] == absolutize(&control).display().to_string()
                    && part[1] == part[2]
            }),
            "the control inbox must not be rebound into the private mission directory"
        );
        assert!(
            !mission.join("state.json.tmp").exists(),
            "argv construction must not create metadata"
        );
        // Absent metadata files are not masked (bwrap needs the destination
        // to exist).
        assert!(
            !joined.contains("estimate.json"),
            "absent metadata files must not be masked: {args:?}"
        );
        // No rw bind of the mission dir, and runs/-subdir scratch files stay
        // unmasked.
        let mission_abs = absolutize(&mission);
        assert!(
            !joined.contains(&format!("--bind {0} {0}", mission_abs.display())),
            "mission dir must not be rw-bound: {args:?}"
        );
        assert!(
            !joined.contains(&scratch_jsonl.display().to_string()),
            "runs/ subdir scratch files must not be masked: {args:?}"
        );
    }

    #[cfg(unix)]
    #[test]
    fn bubblewrap_mask_prep_rejects_preexisting_state_tmp_symlink() {
        use std::os::unix::fs::symlink;
        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        std::fs::create_dir_all(mission.join("runs")).unwrap();
        let target_dir = tempfile::tempdir().unwrap();
        let target = target_dir.path().join("outside");
        std::fs::write(&target, "unchanged").unwrap();
        symlink(&target, mission.join("state.json.tmp")).unwrap();
        let scratch = tempfile::tempdir().unwrap();

        let error = bubblewrap_args(
            &inputs(repo.path(), &mission, scratch.path(), vec![]),
            Path::new("/usr/bin/claude"),
            &[],
        )
        .expect_err("a symlink cannot become a bwrap mask mount point");

        assert!(error.to_string().contains("not a regular file"), "{error}");
        assert_eq!(std::fs::read_to_string(target).unwrap(), "unchanged");
        assert!(
            std::fs::symlink_metadata(mission.join("state.json.tmp"))
                .unwrap()
                .file_type()
                .is_symlink(),
            "mask preparation must not replace or follow the hostile leaf"
        );
    }

    #[test]
    fn sandbox_profile_excludes_paths_outside_allowlist() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let outsider = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(session.path(), mission.path(), tmp.path(), vec![]));

        let outsider_abs = absolutize(outsider.path());
        let forbidden = format!("(subpath \"{}\")", escape_sbpl_literal(&outsider_abs));
        assert!(
            !profile.contains(&forbidden),
            "profile unexpectedly allows write to path outside the allowlist"
        );
    }

    #[test]
    fn sandbox_profile_fs_net_restricts_egress_to_loopback() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let mut inputs = inputs(session.path(), mission.path(), tmp.path(), vec![]);
        inputs.enforce = crate::types::SandboxEnforce::FsNet;
        inputs.egress = vec!["crates.io:443".into(), "api.anthropic.com:443".into()];

        let profile = generate_profile(&inputs);

        // Seatbelt rejects hostname egress rules, so the profile cuts outbound
        // TCP to loopback only; the per-host allowlist (including the
        // configured entries above) is the egress proxy's job, not the SBPL's.
        assert!(!profile.contains("(allow network*)"));
        assert!(profile.contains("(allow network-outbound (remote tcp \"localhost:*\"))"));
        assert!(
            !profile.contains("crates.io") && !profile.contains("anthropic.com"),
            "no per-host egress rules in the profile:\n{profile}"
        );
    }

    #[test]
    fn bubblewrap_args_bind_write_roots_and_unshare_network_for_fs_net() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let extra = tempfile::tempdir().unwrap();
        let mut inputs = inputs(
            session.path(),
            mission.path(),
            tmp.path(),
            vec![extra.path().to_path_buf()],
        );
        inputs.enforce = crate::types::SandboxEnforce::FsNet;

        let args =
            bubblewrap_args(&inputs, Path::new("/usr/bin/claude"), &["--print".into()]).unwrap();
        let joined = args.join(" ");

        assert!(args.contains(&"--unshare-net".to_string()));
        for path in [
            absolutize(session.path()),
            absolutize(tmp.path()),
            absolutize(extra.path()),
        ] {
            assert!(
                joined.contains(&format!("--bind {0} {0}", path.display())),
                "bubblewrap args missing bind for {}: {args:?}",
                path.display()
            );
        }
        // The mission dir is bound read-only via the whole-fs ro-bind only —
        // never re-bound writable.
        let mission_abs = absolutize(mission.path());
        assert!(
            !joined.contains(&format!("--bind {0} {0}", mission_abs.display())),
            "bubblewrap args must not rw-bind the mission dir: {args:?}"
        );
        assert!(joined.contains("--ro-bind / /"));
        assert!(joined.ends_with("/usr/bin/claude --print"));
    }

    /// H8 (2026-09-01 adversarial audit): the argv unshared ONLY the network
    /// namespace, and only under `fs+net`. Host `/proc` was therefore the
    /// engine's own `/proc`, so a contained agent could read
    /// `/proc/<engine>/environ` (the very set `agent_env` exists to withhold)
    /// on a `ptrace_scope = 0` host, keep the controlling terminal, and
    /// signal the engine. Every namespace flag is unconditional; only
    /// `--unshare-net` stays tier-gated, because it is an egress decision.
    #[test]
    fn bubblewrap_args_unshare_every_namespace_on_both_tiers() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();

        for enforce in [
            crate::types::SandboxEnforce::Fs,
            crate::types::SandboxEnforce::FsNet,
        ] {
            let mut inputs = inputs(session.path(), mission.path(), tmp.path(), vec![]);
            inputs.enforce = enforce;
            let args = bubblewrap_args(&inputs, Path::new("/usr/bin/claude"), &[]).unwrap();

            for flag in [
                "--unshare-pid",
                "--unshare-ipc",
                "--unshare-uts",
                "--unshare-cgroup-try",
                "--new-session",
                "--die-with-parent",
            ] {
                assert!(
                    args.contains(&flag.to_string()),
                    "{enforce:?} argv missing {flag}: {args:?}"
                );
            }
            // M-8 (follow-up review): the non-try form makes bwrap EXIT
            // non-zero where cgroup namespaces are unavailable (kernels
            // before 4.6, nested containers, hardened kernels), and every
            // resolver here fails closed — so the whole session dies rather
            // than degrading by one namespace.
            assert!(
                !args.contains(&"--unshare-cgroup".to_string()),
                "the non-try cgroup unshare must never be emitted: {args:?}"
            );
            assert_eq!(
                args.contains(&"--unshare-net".to_string()),
                enforce == crate::types::SandboxEnforce::FsNet,
                "--unshare-net is the one tier-gated namespace: {args:?}"
            );
        }
    }

    /// The canonical `<repo>/.kranz/missions/<id>` fixture the authority
    /// write denies need: a repo root with the mission's own dir, a SIBLING
    /// mission, the repo-level engine stores, and a `.git`.
    fn authority_write_fixture() -> (tempfile::TempDir, PathBuf) {
        let repo = tempfile::tempdir().unwrap();
        let kranz = repo.path().join(".kranz");
        let mission = kranz.join("missions").join("m-x");
        std::fs::create_dir_all(mission.join("runs").join("scratch")).unwrap();
        std::fs::create_dir_all(kranz.join("missions").join("m-other")).unwrap();
        for name in ["queue", "tickets", "lessons", "hook-status"] {
            std::fs::create_dir_all(kranz.join(name)).unwrap();
        }
        for name in ["config.json", "serve.token", "serve.read.token"] {
            std::fs::write(kranz.join(name), "secret").unwrap();
        }
        std::fs::create_dir_all(repo.path().join(".git").join("hooks")).unwrap();
        std::fs::create_dir_all(repo.path().join(".git").join("info")).unwrap();
        std::fs::write(repo.path().join(".git").join("config"), "[core]\n").unwrap();
        (repo, mission)
    }

    /// H2 + H11 (2026-09-01 adversarial audit): `.kranz/config.json` was
    /// read-denied but WRITE-allowed, and every metadata deny was derived
    /// from the session's OWN mission dir. Under checkout mode `session_cwd`
    /// is the repo root, so a contained worker could overwrite the trust
    /// root it could not read, and forge approvals into a sibling mission.
    #[test]
    fn sandbox_profile_denies_authority_material_writes() {
        let (repo, mission) = authority_write_fixture();
        let tmp = tempfile::tempdir().unwrap();
        let kranz = repo.path().join(".kranz");

        // Checkout mode: session_cwd IS the repo root, the hostile shape.
        let profile = generate_profile(&inputs(repo.path(), &mission, tmp.path(), vec![]));

        for name in ["config.json", "serve.token", "serve.read.token"] {
            let expected = format!(
                "(literal \"{}\")",
                escape_sbpl_literal(&absolutize(&kranz.join(name)))
            );
            assert!(
                profile.contains(&expected),
                "profile missing write deny for .kranz/{name}:\n{profile}"
            );
        }
        for name in ["queue", "tickets", "lessons", "hook-status"] {
            let expected = format!(
                "(subpath \"{}\")",
                escape_sbpl_literal(&absolutize(&kranz.join(name)))
            );
            assert!(
                profile.contains(&expected),
                "profile missing write deny for .kranz/{name}/:\n{profile}"
            );
        }
        // The SIBLING mission is denied; the session's OWN mission dir is
        // not denied wholesale (mission_write_denies keeps the narrow set,
        // and runs/<scratch> must stay writable).
        let other = absolutize(&kranz.join("missions").join("m-other"));
        assert!(
            profile.contains(&format!("(subpath \"{}\")", escape_sbpl_literal(&other))),
            "profile missing write deny for the sibling mission dir:\n{profile}"
        );
        let own = absolutize(&mission);
        assert!(
            !profile.contains(&format!("(subpath \"{}\")\n", escape_sbpl_literal(&own))),
            "the session's own mission dir must not be denied wholesale:\n{profile}"
        );
        // The sealing regexes: no NEW store under `.kranz`, no NEW sibling
        // mission dir, after the profile was built.
        for root in [absolutize(&kranz), absolutize(&kranz.join("missions"))] {
            let expected = format!("(regex #\"^{}/[^/]*$\")", escape_sbpl_regex(&root));
            assert!(
                profile.contains(&expected),
                "profile missing the sealing regex for {}:\n{profile}",
                root.display()
            );
        }
    }

    /// The global kranz key dir (`~/.kranz/keys`) is denied for BOTH reads
    /// and writes on every tier (2026-09-01 adversarial audit, C1/H6): the
    /// consent substrate's MAC key has to live outside a sandboxed session's
    /// readable set, or the MAC proves nothing against the agent it excludes;
    /// and a session that could replace the key could re-sign anything.
    #[test]
    fn global_key_dir_is_read_and_write_denied() {
        // The global dir is resolved once per process (`paths::global_kranz_dir`),
        // so the test reads the resolved value instead of rebinding HOME: the
        // property under test is that the deny follows the SAME resolver the
        // key writer and the seal recorder use.
        let global = crate::paths::global_kranz_dir().expect("a global kranz dir resolves");
        let (repo, mission) = authority_write_fixture();
        let tmp = tempfile::tempdir().unwrap();
        let inputs = inputs(repo.path(), &mission, tmp.path(), vec![]);

        for store in ["keys", "seals"] {
            let dir = global.join(store);
            assert!(
                authority_read_deny_dirs(&inputs).contains(&dir),
                "the global {store} dir must be read-denied"
            );
            assert!(
                authority_write_denies(&inputs).dirs.contains(&dir),
                "the global {store} dir must be write-denied"
            );
            let profile = generate_profile(&inputs);
            let expected = format!("(subpath \"{}\")", escape_sbpl_literal(&dir));
            assert!(
                profile.matches(&expected).count() >= 2,
                "the {store} dir belongs in BOTH the read-deny and the write-deny block:\n{profile}"
            );
        }
    }

    /// A mission dir that is NOT in the canonical
    /// `<repo>/.kranz/missions/<id>` layout must yield no sweep at all — the
    /// derivation walks parents, and a bare temp-dir mission would otherwise
    /// seal the system temp root (or `/`) against every write.
    #[test]
    fn authority_write_denies_refuse_a_noncanonical_mission_layout() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let inputs = inputs(session.path(), mission.path(), tmp.path(), vec![]);

        assert!(
            sealed_kranz_dir_roots(&inputs).is_empty(),
            "a non-canonical mission dir must seal nothing"
        );
        let denies = authority_write_denies(&inputs);
        let temp_root = absolutize(&std::env::temp_dir());
        assert!(
            !denies.dirs.iter().any(|d| d == &temp_root),
            "the sweep must never reach the system temp root: {:?}",
            denies.dirs
        );
    }

    /// H3 support (2026-09-01 adversarial audit): the engine checkpoints with
    /// an UNHARDENED git handle in the tree the worker controls, so a planted
    /// `.git/hooks/pre-commit` or a `core.sshCommand` in `.git/config`
    /// executes on the host with the engine's full environment. The deny is
    /// narrow because the worker's own role is to commit.
    #[test]
    fn sandbox_profile_denies_git_config_and_hook_writes_but_not_the_index() {
        let (repo, mission) = authority_write_fixture();
        let tmp = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(repo.path(), &mission, tmp.path(), vec![]));

        let git = absolutize(&repo.path().join(".git"));
        for dir in ["hooks", "info"] {
            let expected = format!("(subpath \"{}\")", escape_sbpl_literal(&git.join(dir)));
            assert!(
                profile.contains(&expected),
                "profile missing write deny for .git/{dir}/:\n{profile}"
            );
        }
        for file in ["config", "config.worktree"] {
            let expected = format!("(literal \"{}\")", escape_sbpl_literal(&git.join(file)));
            assert!(
                profile.contains(&expected),
                "profile missing write deny for .git/{file}:\n{profile}"
            );
        }
        // The gitlink FILE form (worktree mode) is denied as a literal, which
        // in checkout mode denies a replace of the `.git` directory node.
        assert!(
            profile.contains(&format!("(literal \"{}\")", escape_sbpl_literal(&git))),
            "profile missing write deny for the .git node itself:\n{profile}"
        );
        // The commit path stays open: nothing denies the index or objects.
        for open in ["index", "objects", "refs"] {
            let denied = format!("(subpath \"{}\")", escape_sbpl_literal(&git.join(open)));
            assert!(
                !profile.contains(&denied),
                ".git/{open} must stay writable — the worker commits:\n{profile}"
            );
        }
    }

    /// M-9 (follow-up review): a submodule keeps its own `config` and
    /// `hooks/` under `.git/modules/<name>/`, which is the SAME host-execution
    /// surface `.git/config` and `.git/hooks/` are — and in checkout mode it
    /// sits inside the rw session bind. The subtree deny covers every
    /// submodule, present and future; git never needs to write it from
    /// inside the sandbox.
    #[test]
    fn git_metadata_write_denies_cover_the_submodule_config_and_hook_surface() {
        let (repo, mission) = authority_write_fixture();
        let tmp = tempfile::tempdir().unwrap();
        let inputs = inputs(repo.path(), &mission, tmp.path(), vec![]);

        let modules = absolutize(&repo.path().join(".git").join("modules"));
        assert!(
            git_metadata_write_denies(&inputs).dirs.contains(&modules),
            "the .git/modules subtree must be write-denied: {:?}",
            git_metadata_write_denies(&inputs).dirs
        );
        let profile = generate_profile(&inputs);
        assert!(
            profile.contains(&format!("(subpath \"{}\")", escape_sbpl_literal(&modules))),
            "profile missing write deny for .git/modules/:\n{profile}"
        );
    }

    /// The bwrap analogue of the two blocks above: each denied path is
    /// ro-bound over itself (readable, unwritable), and the `.git` DIRECTORY
    /// node is deliberately excluded — binding it whole would close the index
    /// the worker's own `git commit` writes.
    /// Later binds win in bwrap. A read-denied file is closed by its
    /// /dev/null mask; a self ro-bind of the same path emitted afterwards
    /// would put the real content back. Every masked path must therefore be
    /// absent from the self-bind set (Linux CI receipt, 2026-09-03).
    #[test]
    fn bubblewrap_args_never_self_bind_a_masked_authority_path() {
        let (repo, mission) = authority_write_fixture();
        let tmp = tempfile::tempdir().unwrap();
        let inputs = inputs(repo.path(), &mission, tmp.path(), vec![]);
        let args = bubblewrap_args(&inputs, Path::new("/bin/true"), &[]).unwrap();
        let masked: Vec<String> = authority_read_deny_paths(&inputs)
            .iter()
            .map(|path| absolutize(path).display().to_string())
            .collect();
        let kranz = absolutize(&repo.path().join(".kranz"))
            .display()
            .to_string();
        assert!(args
            .windows(2)
            .any(|pair| pair[0] == "--tmpfs" && pair[1] == kranz));
        let mut i = 0;
        while i + 2 < args.len() {
            if matches!(args[i].as_str(), "--ro-bind" | "--ro-bind-try")
                && args[i + 1] == args[i + 2]
            {
                assert!(
                    !masked.contains(&args[i + 2]),
                    "{} is masked and must not be re-bound over itself",
                    args[i + 2]
                );
            }
            i += 1;
        }
    }

    #[test]
    fn bubblewrap_args_ro_bind_authority_and_git_write_denies() {
        let (repo, mission) = authority_write_fixture();
        let tmp = tempfile::tempdir().unwrap();
        let kranz = repo.path().join(".kranz");

        let args = bubblewrap_args(
            &inputs(repo.path(), &mission, tmp.path(), vec![]),
            Path::new("/usr/bin/claude"),
            &[],
        )
        .unwrap();
        let joined = args.join(" ");

        for path in [
            kranz.join("queue"),
            kranz.join("tickets"),
            kranz.join("lessons"),
            kranz.join("missions").join("m-other"),
            repo.path().join(".git").join("hooks"),
            repo.path().join(".git").join("info"),
            repo.path().join(".git").join("config"),
        ] {
            let expected = format!("--ro-bind {0} {0}", lexical_absolute(&path).display());
            assert!(
                joined.contains(&expected),
                "bwrap argv missing the write-closing ro-bind for {}: {args:?}",
                path.display()
            );
        }
        let git = lexical_absolute(&repo.path().join(".git"));
        assert!(
            !joined.contains(&format!("--ro-bind {0} {0}", git.display())),
            "the .git DIRECTORY must never be ro-bound whole — the worker commits: {args:?}"
        );
    }

    /// H7 (2026-09-01 adversarial audit): the operator's own terminal must
    /// be denied read, write AND ioctl — the last is what closes TIOCSTI —
    /// even though the gate extras still ALLOW the pty device class the
    /// harness's `openpty` needs, and even though `/dev/ttys003` is matched
    /// by that class. Rendered from an explicit path list so the assertion
    /// holds on a test runner with no controlling terminal of its own.
    #[test]
    fn tty_deny_block_denies_ioctl_on_the_named_terminal_and_nothing_when_absent() {
        let block = tty_deny_block(&[
            PathBuf::from("/dev/ttys003"),
            PathBuf::from("/dev/ttys003"),
            PathBuf::from("/dev/ttys001"),
        ]);
        assert!(block.starts_with("(deny file-read* file-write* file-ioctl\n"));
        assert!(block.contains("(literal \"/dev/ttys003\")"), "{block}");
        assert!(block.contains("(literal \"/dev/ttys001\")"), "{block}");
        assert_eq!(
            block.matches("/dev/ttys003").count(),
            1,
            "duplicate fds must collapse to one literal:\n{block}"
        );
        assert!(
            tty_deny_block(&[]).is_empty(),
            "no controlling terminal means no deny block"
        );
    }

    #[test]
    fn sandbox_profile_write_profile_file_roundtrip() {
        let dir = tempfile::tempdir().unwrap();
        let profile = "(version 1)\n(deny default)\n";
        let path = write_profile_file(dir.path(), profile).unwrap();
        assert_eq!(std::fs::read_to_string(&path).unwrap(), profile);
        assert!(path.starts_with(dir.path()));
    }

    #[test]
    fn sandbox_platform_support_matrix() {
        use crate::types::SandboxEnforce;

        assert_eq!(
            platform_support(SandboxEnforce::Off, "macos"),
            SandboxDecision::Off
        );
        assert_eq!(
            platform_support(SandboxEnforce::Fs, "macos"),
            SandboxDecision::Enforce(SandboxBackend::Seatbelt)
        );
        assert_eq!(
            platform_support(SandboxEnforce::Fs, "linux"),
            SandboxDecision::Enforce(SandboxBackend::Bubblewrap)
        );
        assert_eq!(
            platform_support(SandboxEnforce::FsNet, "macos"),
            SandboxDecision::Enforce(SandboxBackend::Seatbelt)
        );
        assert_eq!(
            platform_support(SandboxEnforce::FsNet, "linux"),
            SandboxDecision::Enforce(SandboxBackend::Bubblewrap)
        );
        assert_eq!(
            platform_support(SandboxEnforce::Fs, "windows"),
            SandboxDecision::Enforce(SandboxBackend::AppContainer)
        );
        assert_eq!(
            platform_support(SandboxEnforce::FsNet, "windows"),
            SandboxDecision::Enforce(SandboxBackend::AppContainer)
        );
        assert_eq!(
            platform_support(SandboxEnforce::Off, "linux"),
            SandboxDecision::Off
        );
    }

    #[test]
    fn sandbox_resolve_off_yields_none() {
        let cfg = crate::types::SandboxConfig {
            enforce: crate::types::SandboxEnforce::Off,
            provider: crate::types::SandboxProvider::Process,
            image: None,
            extra_write: vec![],
            egress: vec![],
        };
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        let (resolved, warn) = resolve_for_session(&cfg, session.path(), mission.path());
        assert!(resolved.is_none());
        assert!(warn.is_none());
    }

    #[test]
    fn sandbox_resolve_linux_requires_bwrap() {
        let cfg = crate::types::SandboxConfig {
            enforce: crate::types::SandboxEnforce::Fs,
            provider: crate::types::SandboxProvider::Process,
            image: None,
            extra_write: vec![],
            egress: vec![],
        };
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        let (resolved, warn) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "linux",
            false,
            None,
            None,
        );
        assert!(resolved.is_none());
        assert!(
            warn.unwrap().contains("bwrap"),
            "missing-bwrap warning should name bwrap"
        );

        let (resolved, warn) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "linux",
            true,
            None,
            None,
        );
        assert!(warn.is_none());
        assert_eq!(
            resolved.expect("bwrap present").backend,
            SandboxBackend::Bubblewrap
        );
    }

    fn container_cfg(
        enforce: crate::types::SandboxEnforce,
        egress: Vec<String>,
    ) -> crate::types::SandboxConfig {
        crate::types::SandboxConfig {
            enforce,
            provider: crate::types::SandboxProvider::Container,
            image: None,
            extra_write: vec![],
            egress,
        }
    }

    #[test]
    fn container_provider_off_stays_unsandboxed() {
        let cfg = container_cfg(crate::types::SandboxEnforce::Off, vec![]);
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        let (resolved, warn) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "macos",
            false,
            None,
            None,
        );
        assert!(resolved.is_none());
        assert!(warn.is_none());
    }

    #[test]
    fn container_provider_on_macos_resolves_only_against_a_mount_proof() {
        use crate::sandbox_container::{ContainerRuntime, MountProof};
        let cfg = container_cfg(crate::types::SandboxEnforce::Fs, vec![]);
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let resolve = |proof: Option<MountProof>| {
            resolve_for_session_target(
                &cfg,
                session.path(),
                mission.path(),
                "macos",
                false,
                Some(ContainerRuntime::Docker),
                proof,
            )
        };

        // A host that proved the round trip is supported, receipt or no receipt.
        let (resolved, warn) = resolve(Some(MountProof::Proven));
        assert!(resolved.is_some(), "a proven mount must resolve: {warn:?}");

        // A host whose mount shares nothing is refused, and the operator is
        // told which path failed rather than that the platform is unsupported.
        let (resolved, warn) = resolve(Some(MountProof::Failed(
            "docker accepted a bind mount of /var/folders/x and shared nothing".to_string(),
        )));
        assert!(resolved.is_none());
        let warn = warn.expect("a failed proof must refuse loudly");
        assert!(warn.contains("/var/folders/x"), "{warn}");
        assert!(warn.contains("shared nothing"), "{warn}");

        // No proof is not the same as a passing proof.
        let (resolved, warn) = resolve(None);
        assert!(resolved.is_none());
        let warn = warn.expect("an unproven host must refuse");
        assert!(warn.contains("requires a bind-mount proof"), "{warn}");
    }

    #[test]
    fn container_provider_on_windows_refuses_even_a_proven_mount() {
        use crate::sandbox_container::{ContainerRuntime, MountProof};
        let cfg = container_cfg(crate::types::SandboxEnforce::Fs, vec![]);
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        // Windows fails the POSIX guest-path and /dev/null authority-mask
        // contract, which a mount proof says nothing about.
        let (resolved, warn) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "windows",
            false,
            Some(ContainerRuntime::Docker),
            Some(MountProof::Proven),
        );
        assert!(resolved.is_none());
        let warn = warn.expect("windows must refuse");
        assert!(
            warn.contains("not supported on target_os=windows"),
            "{warn}"
        );
        assert!(warn.contains("POSIX guest paths"), "{warn}");
    }

    #[test]
    fn container_provider_without_runtime_fails_closed() {
        let cfg = container_cfg(crate::types::SandboxEnforce::Fs, vec![]);
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        let (resolved, warn) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "linux",
            false,
            None,
            None,
        );
        assert!(resolved.is_none());
        let warn = warn.expect("missing runtime must produce a warning");
        assert!(warn.contains("provider:container"), "{warn}");
        assert!(warn.contains("docker/podman/nerdctl/container"), "{warn}");
        assert!(warn.contains("refusing to run unsandboxed"), "{warn}");
    }

    #[test]
    fn macos_enforced_container_provider_fails_closed_to_native_process_guidance() {
        let cfg = container_cfg(crate::types::SandboxEnforce::Fs, vec![]);
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        let (resolved, warning) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "macos",
            false,
            Some(crate::sandbox_container::ContainerRuntime::Docker),
            None,
        );
        assert!(resolved.is_none());
        let warning = warning.expect("an unproved macOS container must refuse");
        // The refusal is now about THIS host's evidence, not about the
        // platform: an unproved macOS host is refused, and a proved one
        // resolves (container_provider_on_macos_resolves_only_against_a_mount_proof).
        assert!(warning.contains("requires a bind-mount proof"), "{warning}");
        assert!(
            warning.contains("sandbox.provider=\"process\""),
            "{warning}"
        );
        assert!(warning.contains("native host containment"), "{warning}");
    }

    /// M7 Windows parity, phase 4: the process provider resolves the stable
    /// AppContainer backend. Merely finding `docker.exe` still does not prove
    /// the Windows container mount contract, so that provider stays refused;
    /// `off` remains the operator's explicit unsandboxed posture.
    #[test]
    fn windows_enforced_session_process_resolves_appcontainer_while_container_fails_closed() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        for enforce in [
            crate::types::SandboxEnforce::Fs,
            crate::types::SandboxEnforce::FsNet,
        ] {
            let process = crate::types::SandboxConfig {
                enforce,
                provider: crate::types::SandboxProvider::Process,
                image: None,
                extra_write: vec![],
                egress: vec![],
            };
            let (resolved, warning) = resolve_for_session_target(
                &process,
                session.path(),
                mission.path(),
                "windows",
                false,
                Some(crate::sandbox_container::ContainerRuntime::Docker),
                None,
            );
            assert!(warning.is_none(), "{warning:?}");
            let resolved = resolved.expect("Windows process enforcement resolves");
            assert_eq!(resolved.backend, SandboxBackend::AppContainer);
            assert_eq!(resolved.inputs.enforce, enforce);
            assert_eq!(resolved.inputs.session_cwd, session.path());
            assert_eq!(resolved.inputs.mission_dir, mission.path());

            let container = container_cfg(enforce, vec![]);
            let (resolved, warning) = resolve_for_session_target(
                &container,
                session.path(),
                mission.path(),
                "windows",
                false,
                Some(crate::sandbox_container::ContainerRuntime::Docker),
                None,
            );
            assert!(resolved.is_none());
            let warning = warning.expect("an unproved Windows container must refuse");
            // Windows is refused on its own contract gap, not for want of a
            // mount proof: guest paths and /dev/null masks are what fail
            // there, so no probe result could change this answer.
            assert!(
                warning.contains("not supported on target_os=windows"),
                "{warning}"
            );
            assert!(
                warning.contains("unverified container mount contract"),
                "{warning}"
            );
        }

        let off = container_cfg(crate::types::SandboxEnforce::Off, vec![]);
        let (resolved, warning) = resolve_for_session_target(
            &off,
            session.path(),
            mission.path(),
            "windows",
            false,
            Some(crate::sandbox_container::ContainerRuntime::Docker),
            None,
        );
        assert!(resolved.is_none());
        assert!(warning.is_none());
    }

    #[test]
    fn container_provider_fs_net_with_egress_list_resolves_for_the_proxy() {
        let cfg = container_cfg(
            crate::types::SandboxEnforce::FsNet,
            vec!["crates.io:443".to_string()],
        );
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        // Docker resolves the posture; the runner provisions the unique
        // internal network + authenticated relay before session spawn.
        let (resolved, warn) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "linux",
            false,
            Some(crate::sandbox_container::ContainerRuntime::Docker),
            None,
        );
        assert!(warn.is_none(), "{warn:?}");
        let resolved = resolved.expect("container fs+net with egress must resolve");
        assert_eq!(resolved.backend, SandboxBackend::Container);
        assert_eq!(resolved.inputs.egress, vec!["crates.io:443".to_string()]);
    }

    #[test]
    fn container_provider_fs_net_with_egress_refuses_non_docker_runtime() {
        let cfg = container_cfg(
            crate::types::SandboxEnforce::FsNet,
            vec!["crates.io:443".to_string()],
        );
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let (resolved, warning) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "linux",
            false,
            Some(crate::sandbox_container::ContainerRuntime::Podman),
            None,
        );
        assert!(resolved.is_none());
        let warning = warning.expect("unproved runtime must fail closed");
        assert!(warning.contains("requires Docker"), "{warning}");
        assert!(warning.contains("podman"), "{warning}");
    }

    #[test]
    fn container_provider_resolves_runtime_and_image() {
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        // Default image when config names none.
        let cfg = container_cfg(crate::types::SandboxEnforce::FsNet, vec![]);
        let (resolved, warn) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "linux",
            false,
            Some(crate::sandbox_container::ContainerRuntime::Podman),
            None,
        );
        assert!(warn.is_none());
        let resolved = resolved.expect("runtime present and policy supportable");
        assert_eq!(resolved.backend, SandboxBackend::Container);
        let container = resolved.container.expect("container spec must be set");
        assert_eq!(
            container.runtime,
            crate::sandbox_container::ContainerRuntime::Podman
        );
        assert_eq!(container.image, crate::sandbox_container::DEFAULT_IMAGE);

        // Configured image overrides the default.
        let mut cfg = container_cfg(crate::types::SandboxEnforce::Fs, vec![]);
        cfg.image = Some("ghcr.io/example/kranz-worker:1".to_string());
        let (resolved, warn) = resolve_for_session_target(
            &cfg,
            session.path(),
            mission.path(),
            "linux",
            false,
            Some(crate::sandbox_container::ContainerRuntime::Docker),
            None,
        );
        assert!(warn.is_none());
        assert_eq!(
            resolved
                .expect("runtime present")
                .container
                .expect("container spec")
                .image,
            "ghcr.io/example/kranz-worker:1"
        );
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_resolve_fs_on_macos_yields_resolved_sandbox() {
        let cfg = crate::types::SandboxConfig {
            enforce: crate::types::SandboxEnforce::Fs,
            provider: crate::types::SandboxProvider::Process,
            image: None,
            extra_write: vec![],
            egress: vec![],
        };
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        let (resolved, warn) = resolve_for_session(&cfg, session.path(), mission.path());
        assert!(warn.is_none());
        let resolved = resolved.expect("expected an enforced sandbox on macos");
        assert_eq!(resolved.backend, SandboxBackend::Seatbelt);
        assert_eq!(resolved.inputs.session_cwd, session.path());
        assert_eq!(resolved.inputs.mission_dir, mission.path());
        assert!(!resolved.inputs.tmpdir.as_os_str().is_empty());
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_resolve_prewarms_apple_git_cache_before_profile_use() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();
        if !sandbox_exec_can_apply() {
            return;
        }

        let repo = tempfile::tempdir().unwrap();
        let init = Command::new("/usr/bin/git")
            .args(["init", "--quiet"])
            .current_dir(repo.path())
            .env("GIT_CONFIG_NOSYSTEM", "1")
            .env("GIT_CONFIG_GLOBAL", "/dev/null")
            .status()
            .expect("initialize disposable repository");
        assert!(init.success());
        let mission = tempfile::tempdir().unwrap();
        let cfg = crate::types::SandboxConfig {
            enforce: crate::types::SandboxEnforce::Fs,
            provider: crate::types::SandboxProvider::Process,
            image: None,
            extra_write: vec![],
            egress: vec![],
        };

        // Resolution performs the bounded host-side prewarm before the
        // generated profile can deny the shared xcrun cache refresh.
        let (resolved, warn) = resolve_for_session(&cfg, repo.path(), mission.path());
        assert!(warn.is_none());
        let resolved = resolved.expect("Seatbelt resolves on macOS");
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path =
            write_profile_file(profile_dir.path(), &generate_profile(&resolved.inputs)).unwrap();
        let output = Command::new("sandbox-exec")
            .arg("-f")
            .arg(profile_path)
            .arg("/usr/bin/git")
            .args(["status", "--short"])
            .current_dir(repo.path())
            .env("GIT_CONFIG_NOSYSTEM", "1")
            .env("GIT_CONFIG_GLOBAL", "/dev/null")
            .output()
            .expect("run Apple Git under the resolved profile");
        let stderr = String::from_utf8_lossy(&output.stderr);
        assert!(output.status.success(), "Apple Git must run: {stderr}");
        assert!(
            !stderr.contains("xcrun_db"),
            "the host-side prewarm must prevent an in-sandbox cache refresh: {stderr}"
        );
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_resolve_expands_tilde_extra_write_via_home() {
        let cfg = crate::types::SandboxConfig {
            enforce: crate::types::SandboxEnforce::Fs,
            provider: crate::types::SandboxProvider::Process,
            image: None,
            extra_write: vec!["~/.cargo".to_string()],
            egress: vec![],
        };
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let home = std::env::var("HOME").expect("HOME must be set to run this test");

        let (resolved, _warn) = resolve_for_session(&cfg, session.path(), mission.path());
        let resolved = resolved.expect("expected an enforced sandbox on macos");
        assert_eq!(
            resolved.inputs.extra_write,
            vec![PathBuf::from(home).join(".cargo")]
        );
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_resolve_fs_net_on_macos_yields_seatbelt_with_loopback_profile() {
        let cfg = crate::types::SandboxConfig {
            enforce: crate::types::SandboxEnforce::FsNet,
            provider: crate::types::SandboxProvider::Process,
            image: None,
            extra_write: vec![],
            egress: vec![],
        };
        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();

        let (resolved, warn) = resolve_for_session(&cfg, session.path(), mission.path());

        assert!(warn.is_none(), "fs+net on macOS resolves: {warn:?}");
        let resolved = resolved.expect("fs+net on macOS resolves to Seatbelt");
        assert_eq!(resolved.backend, SandboxBackend::Seatbelt);
        let profile = generate_profile(&resolved.inputs);
        assert!(
            profile.contains("(allow network-outbound (remote tcp \"localhost:*\"))"),
            "fs+net profile must restrict egress to loopback so only the egress proxy is reachable:\n{profile}"
        );
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_enforcement_macos_allows_inside_denies_outside() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();

        if !sandbox_exec_can_apply() {
            return;
        }

        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let outside = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(session.path(), mission.path(), tmp.path(), vec![]));
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path = write_profile_file(profile_dir.path(), &profile).unwrap();

        let inside_file = session.path().join("inside.txt");
        let inside_status = Command::new("sandbox-exec")
            .arg("-f")
            .arg(&profile_path)
            .arg("/bin/sh")
            .arg("-c")
            .arg(format!("echo hi > {}", inside_file.display()))
            .status()
            .expect("failed to run sandbox-exec");
        assert!(
            inside_status.success(),
            "expected write inside session_cwd to succeed"
        );
        assert!(inside_file.exists(), "expected inside file to be created");

        let dev_null_status = Command::new("sandbox-exec")
            .arg("-f")
            .arg(&profile_path)
            .arg("/bin/sh")
            .arg("-c")
            .arg("echo hi > /dev/null 2>&1")
            .status()
            .expect("failed to run sandbox-exec");
        assert!(
            dev_null_status.success(),
            "ordinary shell redirects to /dev/null must succeed"
        );

        let outside_file = outside.path().join(format!(
            "kranz_sandbox_should_fail_{}",
            uuid::Uuid::new_v4()
        ));
        let outside_status = Command::new("sandbox-exec")
            .arg("-f")
            .arg(&profile_path)
            .arg("/bin/sh")
            .arg("-c")
            .arg(format!("echo hi > {}", outside_file.display()))
            .status()
            .expect("failed to run sandbox-exec");
        assert!(
            !outside_status.success(),
            "expected write outside allowlist to be denied"
        );
        assert!(
            !outside_file.exists(),
            "denied write must not have created the file"
        );
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_enforcement_macos_denies_authority_material_reads() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();

        if !sandbox_exec_can_apply() {
            return;
        }

        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        std::fs::create_dir_all(&mission).unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let kranz_dir = repo.path().join(".kranz");
        for name in [
            "serve.token",
            "serve.read.token",
            "config.json",
            "domain-terms.local",
        ] {
            std::fs::write(kranz_dir.join(name), "secret").unwrap();
        }
        let public = repo.path().join("public.txt");
        std::fs::write(&public, "public").unwrap();

        let profile = generate_profile(&inputs(repo.path(), &mission, tmp.path(), vec![]));
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path = write_profile_file(profile_dir.path(), &profile).unwrap();

        for name in [
            "serve.token",
            "serve.read.token",
            "config.json",
            "domain-terms.local",
        ] {
            let status = Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/cat")
                .arg(kranz_dir.join(name))
                .status()
                .expect("failed to run sandbox-exec");
            assert!(
                !status.success(),
                "sandboxed read of .kranz/{name} must be denied"
            );
        }

        // Ordinary repo reads keep working under the same profile.
        let output = Command::new("sandbox-exec")
            .arg("-f")
            .arg(&profile_path)
            .arg("/bin/cat")
            .arg(&public)
            .output()
            .expect("failed to run sandbox-exec");
        assert!(
            output.status.success(),
            "ordinary repo reads must keep working: {}",
            String::from_utf8_lossy(&output.stderr)
        );
        assert_eq!(String::from_utf8_lossy(&output.stdout), "public");
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_enforcement_macos_denies_mission_metadata_writes() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();

        if !sandbox_exec_can_apply() {
            return;
        }

        // Checkout-mode shape: session_cwd is the repo root, an ANCESTOR of
        // the mission dir — the hostile case the write denies exist for.
        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        let runs = mission.join("runs");
        std::fs::create_dir_all(&runs).unwrap();
        let control = mission.join("control");
        std::fs::create_dir_all(&control).unwrap();
        let contract_home = runs.join("contract-home");
        std::fs::create_dir_all(&contract_home).unwrap();
        let events = mission.join("events.jsonl");
        let state = mission.join("state.json");
        let old_transcript = runs.join("run-old.jsonl");
        std::fs::write(&events, "{\"seq\":1}\n").unwrap();
        std::fs::write(&state, "{}").unwrap();
        std::fs::write(&old_transcript, "original\n").unwrap();
        let scratch = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(repo.path(), &mission, scratch.path(), vec![]));
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path = write_profile_file(profile_dir.path(), &profile).unwrap();

        // Engine-owned paths refuse writes — including a NEW runs/*.jsonl
        // (the transcript regex denies creation, not just modification).
        let denied_writes = [
            format!("echo tampered >> {}", events.display()),
            format!("echo tampered > {}", state.display()),
            format!("echo x > {}", control.join("approve.json").display()),
            format!("echo forged >> {}", old_transcript.display()),
            format!("echo forged > {}", runs.join("run-new.jsonl").display()),
        ];
        for write in denied_writes {
            let status = Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/sh")
                .arg("-c")
                .arg(&write)
                .status()
                .expect("failed to run sandbox-exec");
            assert!(!status.success(), "write must be denied: {write}");
        }
        assert_eq!(std::fs::read_to_string(&events).unwrap(), "{\"seq\":1}\n");
        assert_eq!(std::fs::read_to_string(&state).unwrap(), "{}");
        assert_eq!(
            std::fs::read_to_string(&old_transcript).unwrap(),
            "original\n"
        );
        assert!(!runs.join("run-new.jsonl").exists());
        assert!(std::fs::read_dir(&control).unwrap().next().is_none());

        // The session's own work continues under the same profile: the repo
        // tree, the private scratch, and runs/ SUBDIRECTORIES stay writable.
        let allowed_writes = [
            repo.path().join("src.txt"),
            scratch.path().join("notes.txt"),
            contract_home.join("out.txt"),
        ];
        for target in allowed_writes {
            let status = Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/sh")
                .arg("-c")
                .arg(format!("echo ok > {}", target.display()))
                .status()
                .expect("failed to run sandbox-exec");
            assert!(
                status.success(),
                "write must be allowed: {}",
                target.display()
            );
            assert!(target.exists());
        }
    }

    /// The live half of `sandbox_profile_denies_authority_material_writes`
    /// and `..._git_config_and_hook_writes...`: a real `sandbox-exec` run
    /// under a checkout-mode profile refuses the writes and keeps the
    /// session's own work going (H2, H11, H3 support).
    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_enforcement_macos_denies_authority_and_git_metadata_writes() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();

        if !sandbox_exec_can_apply() {
            return;
        }

        let (repo, mission) = authority_write_fixture();
        let scratch = tempfile::tempdir().unwrap();
        let kranz = repo.path().join(".kranz");
        let git = repo.path().join(".git");
        std::fs::write(git.join("index"), "idx").unwrap();

        let profile = generate_profile(&inputs(repo.path(), &mission, scratch.path(), vec![]));
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path = write_profile_file(profile_dir.path(), &profile).unwrap();

        let denied = [
            // The trust root: overwritten without ever being read.
            format!("echo '{{}}' > {}", kranz.join("config.json").display()),
            // A sibling mission's control inbox (forged operator consent).
            format!(
                "echo x > {}",
                kranz
                    .join("missions")
                    .join("m-other")
                    .join("approve.json")
                    .display()
            ),
            // A NEW sibling mission dir, and a NEW repo-level store.
            format!(
                "mkdir {}",
                kranz.join("missions").join("m-forged").display()
            ),
            format!("mkdir {}", kranz.join("newstore").display()),
            // Repo-level engine stores.
            format!("echo x > {}", kranz.join("queue").join("q.json").display()),
            format!("echo x > {}", kranz.join("lessons").join("l.md").display()),
            // The git hook and config surface the engine's next checkpoint
            // commit would execute.
            format!(
                "echo x > {}",
                git.join("hooks").join("pre-commit").display()
            ),
            format!("echo x > {}", git.join("config").display()),
        ];
        for command in &denied {
            let status = Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/sh")
                .arg("-c")
                .arg(command)
                .status()
                .expect("failed to run sandbox-exec");
            assert!(!status.success(), "write must be denied: {command}");
        }
        assert_eq!(
            std::fs::read_to_string(kranz.join("config.json")).unwrap(),
            "secret"
        );
        assert!(!kranz.join("missions").join("m-forged").exists());
        assert!(!kranz.join("newstore").exists());
        assert!(!git.join("hooks").join("pre-commit").exists());

        // The session's own work is untouched: the repo tree, the private
        // scratch, its own mission scratch under runs/, and the git index
        // the worker's own `git commit` writes.
        let allowed = [
            repo.path().join("src.txt"),
            scratch.path().join("notes.txt"),
            mission.join("runs").join("scratch").join("out.txt"),
            git.join("index"),
        ];
        for target in allowed {
            let status = Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/sh")
                .arg("-c")
                .arg(format!("echo ok > {}", target.display()))
                .status()
                .expect("failed to run sandbox-exec");
            assert!(
                status.success(),
                "write must be allowed: {}",
                target.display()
            );
        }
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_enforcement_macos_denies_sibling_temp_neighbors() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();

        if !sandbox_exec_can_apply() {
            return;
        }

        // The finding's layout: every mission's integration/feature
        // worktrees and scratch homes sit side by side under the shared
        // temp root. A session must write its own worktree + scratch and
        // nothing beside them.
        let root = tempfile::tempdir().unwrap();
        let session = root.path().join("kranz-wt-aaa-m1-f-1-1");
        let scratch = root.path().join("kranz-worker-home-sess-1");
        let scratch_home = scratch.join("home");
        let sibling = root.path().join("kranz-wt-bbb-m2-_integration");
        let sibling_scratch = root.path().join("kranz-worker-home-sess-2");
        for d in [&session, &scratch_home, &sibling, &sibling_scratch] {
            std::fs::create_dir_all(d).unwrap();
        }
        let mission = tempfile::tempdir().unwrap();

        let profile = generate_profile(&inputs(&session, mission.path(), &scratch, vec![]));
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path = write_profile_file(profile_dir.path(), &profile).unwrap();

        for allowed in [session.join("code.rs"), scratch_home.join("notes.txt")] {
            let status = Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/sh")
                .arg("-c")
                .arg(format!("echo ok > {}", allowed.display()))
                .status()
                .expect("failed to run sandbox-exec");
            assert!(
                status.success(),
                "write inside the session's own roots must be allowed: {}",
                allowed.display()
            );
            assert!(allowed.exists());
        }

        for denied in [
            sibling.join("evil.txt"),
            sibling_scratch.join("evil.txt"),
            root.path().join("evil.txt"),
        ] {
            let status = Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/sh")
                .arg("-c")
                .arg(format!("echo evil > {}", denied.display()))
                .status()
                .expect("failed to run sandbox-exec");
            assert!(
                !status.success(),
                "write to a temp neighbor must be denied: {}",
                denied.display()
            );
            assert!(!denied.exists());
        }
    }

    #[cfg(target_os = "macos")]
    #[test]
    fn sandbox_enforcement_macos_fs_net_loopback_profile_applies() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();

        if !sandbox_exec_can_apply() {
            return;
        }

        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let mut inputs = inputs(session.path(), mission.path(), tmp.path(), vec![]);
        inputs.enforce = crate::types::SandboxEnforce::FsNet;

        // The fs+net profile (loopback-only egress) must be ACCEPTED by
        // sandbox-exec — unlike the hostname-rule shape Seatbelt rejects with
        // "host must be * or localhost" — or fs+net sessions could not run.
        let profile = generate_profile(&inputs);
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path = write_profile_file(profile_dir.path(), &profile).unwrap();

        let applied = Command::new("sandbox-exec")
            .arg("-f")
            .arg(&profile_path)
            .arg("/usr/bin/true")
            .output()
            .expect("failed to run sandbox-exec");
        assert!(
            applied.status.success(),
            "loopback-only fs+net profile must apply cleanly on macOS: {}",
            String::from_utf8_lossy(&applied.stderr)
        );
    }

    #[cfg(target_os = "linux")]
    #[test]
    fn sandbox_enforcement_linux_bwrap_allows_inside_denies_outside() {
        use std::process::Command;

        if !bwrap_can_apply() {
            return;
        }

        let session = tempfile::tempdir().unwrap();
        let mission = tempfile::tempdir().unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let outside = tempfile::tempdir().unwrap();
        let inputs = inputs(session.path(), mission.path(), tmp.path(), vec![]);

        let inside_file = session.path().join("inside.txt");
        let inside_args = bubblewrap_args(
            &inputs,
            Path::new("/bin/sh"),
            &["-c".into(), format!("echo hi > {}", inside_file.display())],
        )
        .unwrap();
        let inside_status = Command::new("bwrap")
            .args(inside_args)
            .status()
            .expect("failed to run bwrap");
        assert!(
            inside_status.success(),
            "expected write inside session_cwd to succeed"
        );
        assert!(inside_file.exists(), "expected inside file to be created");

        let outside_file = outside
            .path()
            .join(format!("kranz_bwrap_should_fail_{}", uuid::Uuid::new_v4()));
        let outside_args = bubblewrap_args(
            &inputs,
            Path::new("/bin/sh"),
            &["-c".into(), format!("echo hi > {}", outside_file.display())],
        )
        .unwrap();
        let outside_status = Command::new("bwrap")
            .args(outside_args)
            .status()
            .expect("failed to run bwrap");
        assert!(
            !outside_status.success(),
            "expected write outside allowlist to be denied"
        );
        assert!(
            !outside_file.exists(),
            "denied write must not have created the file"
        );
    }

    #[cfg(target_os = "linux")]
    #[test]
    fn sandbox_enforcement_linux_bwrap_tolerates_disappearing_visible_entries() {
        if crate::agent_env::isolated_global_home_test(
            "sandbox::tests::sandbox_enforcement_linux_bwrap_tolerates_disappearing_visible_entries",
        ) {
            return;
        }
        if !bwrap_can_apply() {
            return;
        }
        let repo = tempfile::tempdir().unwrap();
        let scratch = tempfile::tempdir().unwrap();
        let home = tempfile::tempdir().unwrap();
        let _env =
            crate::agent_env::EnvTestGuard::engage(&[("HOME", home.path().to_str().unwrap())]);
        let kranz = home.path().join(".kranz");
        let mission = repo.path().join(".kranz/missions/m-mask-race");
        std::fs::create_dir_all(&mission).unwrap();
        let transient_dir = home.path().join("temporary-cache");
        let transient_file = home.path().join("temporary-note");
        let public = home.path().join("public.txt");
        let authority_path = repo.path().join(".kranz/serve.token");
        let late_authority_path = kranz.join("serve.read.token");
        let writable = repo.path().join("result.txt");
        std::fs::create_dir(&transient_dir).unwrap();
        std::fs::write(&transient_file, "temporary").unwrap();
        std::fs::write(&public, "public").unwrap();
        std::fs::write(&authority_path, "secret").unwrap();
        let args = bubblewrap_args(
            &inputs(repo.path(), &mission, scratch.path(), vec![]),
            Path::new("/bin/sh"),
            &[
                "-c".into(),
                "test ! -e \"$1\" && test ! -e \"$2\" \
                 && test \"$(cat \"$3\")\" = public && ! touch \"$3\" \
                 && test ! -e \"$4\" && test ! -e \"$5\" \
                 && printf ok > \"$6\""
                    .into(),
                "mask-race".into(),
                transient_dir.display().to_string(),
                transient_file.display().to_string(),
                public.display().to_string(),
                authority_path.display().to_string(),
                late_authority_path.display().to_string(),
                writable.display().to_string(),
            ],
        )
        .unwrap();
        for path in [&transient_dir, &transient_file] {
            let path = absolutize(path).display().to_string();
            assert!(args.windows(3).any(|part| {
                matches!(part[0].as_str(), "--ro-bind" | "--ro-bind-try")
                    && part[1] == path
                    && part[2] == path
            }));
        }
        // Deterministically reproduce deletion between enumeration and mount
        // setup, while also creating authority that the private view must hide.
        std::fs::remove_dir(&transient_dir).unwrap();
        std::fs::remove_file(&transient_file).unwrap();
        std::fs::create_dir(&kranz).unwrap();
        std::fs::write(&late_authority_path, "late-secret").unwrap();
        let output = std::process::Command::new("bwrap")
            .args(args)
            .env_clear()
            .env("PATH", "/usr/bin:/bin")
            .output()
            .unwrap();
        assert!(
            output.status.success(),
            "missing ordinary entries must stay hidden without breaking the sandbox: {output:?}"
        );
        assert_eq!(std::fs::read_to_string(&writable).unwrap(), "ok");
        assert_eq!(std::fs::read_to_string(&public).unwrap(), "public");
        assert_eq!(std::fs::read_to_string(&authority_path).unwrap(), "secret");
        assert_eq!(
            std::fs::read_to_string(&late_authority_path).unwrap(),
            "late-secret"
        );
    }

    #[cfg(unix)]
    #[test]
    fn sandbox_bwrap_rebinding_keeps_git_and_authority_protected() {
        if crate::agent_env::isolated_global_home_test(
            "sandbox::tests::sandbox_bwrap_rebinding_keeps_git_and_authority_protected",
        ) {
            return;
        }
        let dir = tempfile::tempdir().unwrap();
        let home = dir.path().canonicalize().unwrap();
        let cargo = home.join(".cargo");
        std::fs::create_dir(home.join(".kranz")).unwrap();
        let _env = crate::agent_env::EnvTestGuard::engage(&[
            ("HOME", home.to_str().unwrap()),
            ("CARGO_HOME", cargo.to_str().unwrap()),
        ]);
        // The absent Cargo home promotes its authority mask to HOME, above
        // the checkout. A validator snapshot also gets rebound below runs/.
        assert!(!cargo.exists());
        for snapshot in [false, true] {
            let repo = home.join(if snapshot {
                "validator-repo"
            } else {
                "checkout"
            });
            let mission = repo.join(".kranz/missions/m-rebind");
            let scratch = mission.join("runs/scratch");
            let cwd = if snapshot {
                mission.join("runs/snapshot")
            } else {
                repo.clone()
            };
            for path in [&cwd, &scratch] {
                std::fs::create_dir_all(path).unwrap();
            }
            let protected = if snapshot {
                vec![cwd.join(".git")]
            } else {
                std::fs::create_dir_all(cwd.join(".git/hooks")).unwrap();
                vec![cwd.join(".git/config"), cwd.join(".git/hooks/probe")]
            };
            for path in &protected {
                std::fs::write(path, "protected").unwrap();
            }
            let authority_path = repo.join(".kranz/serve.token");
            std::fs::write(&authority_path, "secret").unwrap();
            let ordinary = if snapshot {
                cwd.join("witness")
            } else {
                cwd.join(".git/index")
            };
            let mut command = vec![
                "-c".into(),
                "printf work > \"$1\" || exit 1; printf work > \"$2\" || exit 2; \
                 if cat \"$3\"; then exit 3; fi; shift 3; \
                 for path in \"$@\"; do \
                 test \"$(cat \"$path\")\" = protected || exit 4; \
                 if printf forged > \"$path\"; then exit 5; fi; done"
                    .into(),
                "rebind-test".into(),
                ordinary.display().to_string(),
                scratch.join("witness").display().to_string(),
                authority_path.display().to_string(),
            ];
            command.extend(protected.iter().map(|path| path.display().to_string()));
            let args = bubblewrap_args(
                &inputs(&cwd, &mission, &scratch, vec![]),
                Path::new("/bin/sh"),
                &command,
            )
            .unwrap();
            for path in &protected {
                let last_bind = args.windows(3).rev().find(|part| {
                    matches!(part[0].as_str(), "--bind" | "--ro-bind" | "--ro-bind-try")
                        && path.starts_with(&part[2])
                });
                assert_eq!(
                    last_bind.map(|part| part[0].as_str()),
                    Some("--ro-bind"),
                    "a later writable ancestor reopened {}: {args:?}",
                    path.display()
                );
            }
            #[cfg(target_os = "linux")]
            if bwrap_can_apply() {
                let output = std::process::Command::new("bwrap")
                    .args(&args)
                    .env_clear()
                    .env("PATH", "/usr/bin:/bin")
                    .output()
                    .unwrap();
                assert!(output.status.success(), "snapshot={snapshot}: {output:?}");
                assert_eq!(std::fs::read_to_string(&ordinary).unwrap(), "work");
                assert_eq!(std::fs::read_to_string(&authority_path).unwrap(), "secret");
                for path in protected {
                    assert_eq!(std::fs::read_to_string(path).unwrap(), "protected");
                }
            }
        }
    }

    #[cfg(target_os = "linux")]
    #[test]
    fn sandbox_enforcement_linux_bwrap_masks_authority_material() {
        if crate::agent_env::isolated_global_home_test(
            "sandbox::tests::sandbox_enforcement_linux_bwrap_masks_authority_material",
        ) {
            return;
        }
        use std::process::Command;

        if !bwrap_can_apply() {
            return;
        }

        let repo = tempfile::tempdir().unwrap();
        let mission = repo.path().join(".kranz").join("missions").join("m-x");
        std::fs::create_dir_all(&mission).unwrap();
        let tmp = tempfile::tempdir().unwrap();
        let serve_token = repo.path().join(".kranz").join("serve.token");
        std::fs::write(&serve_token, "secret").unwrap();
        let public = repo.path().join("public.txt");
        std::fs::write(&public, "public").unwrap();
        let home = tempfile::tempdir().unwrap();
        let authority_target = tempfile::tempdir().unwrap();
        let alias = home.path().join(".kranz");
        std::os::unix::fs::symlink(authority_target.path(), &alias).unwrap();
        let config_target = authority_target.path().join("settings.json");
        std::fs::write(&config_target, "config-secret").unwrap();
        std::os::unix::fs::symlink(&config_target, repo.path().join(".kranz/config.json")).unwrap();
        let _env =
            crate::agent_env::EnvTestGuard::engage(&[("HOME", home.path().to_str().unwrap())]);
        let inputs = inputs(repo.path(), &mission, tmp.path(), vec![home.path().into()]);

        // The private directory has no authority entry at all.
        let masked = Command::new("bwrap")
            .args(
                bubblewrap_args(
                    &inputs,
                    Path::new("/bin/cat"),
                    &[serve_token.display().to_string()],
                )
                .unwrap(),
            )
            .output()
            .expect("failed to run bwrap");
        assert!(
            !masked.status.success(),
            "reading the hidden authority path must fail: {}",
            String::from_utf8_lossy(&masked.stderr)
        );
        assert!(
            !String::from_utf8_lossy(&masked.stdout).contains("secret"),
            "serve.token content must be masked inside the sandbox"
        );

        let late = repo.path().join(".kranz/serve.read.token");
        let args = bubblewrap_args(
            &inputs,
            Path::new("/bin/cat"),
            &[late.display().to_string()],
        )
        .unwrap();
        // Create the token after the mount policy has been resolved. The old
        // existence-filtered file mask would have exposed this value.
        std::fs::write(&late, "late-secret").unwrap();
        let output = Command::new("bwrap").args(args).output().unwrap();
        assert!(!output.status.success());
        assert!(!String::from_utf8_lossy(&output.stdout).contains("late-secret"));

        let host_view = format!("/proc/{}/root{}", std::process::id(), serve_token.display());
        let output = Command::new("bwrap")
            .args(bubblewrap_args(&inputs, Path::new("/bin/cat"), &[host_view]).unwrap())
            .output()
            .unwrap();
        assert!(
            !output.status.success(),
            "host /proc roots must not bypass the namespace"
        );
        assert!(!String::from_utf8_lossy(&output.stdout).contains("secret"));

        for (binary, path) in [("/bin/cat", &config_target), ("/bin/rm", &alias)] {
            let output = Command::new("bwrap")
                .args(
                    bubblewrap_args(&inputs, Path::new(binary), &[path.display().to_string()])
                        .unwrap(),
                )
                .output()
                .unwrap();
            assert!(
                !output.status.success(),
                "authority alias/target was exposed: {output:?}"
            );
        }
        assert!(
            alias.is_symlink(),
            "the operator's authority alias was replaced"
        );

        let control = Command::new("bwrap")
            .args(
                bubblewrap_args(
                    &inputs,
                    Path::new("/bin/cat"),
                    &[public.display().to_string()],
                )
                .unwrap(),
            )
            .output()
            .expect("failed to run bwrap");
        assert_eq!(String::from_utf8_lossy(&control.stdout), "public");
    }

    // -----------------------------------------------------------------------
    // Mandatory validator containment (ticket validator-mandatory-containment)
    // -----------------------------------------------------------------------

    /// A fake real-checkout root in the exact production layout: a source
    /// tree (dir + files, including a dotfile secret), the shared `.git`
    /// dir, and the `.kranz` mission layout with the validator's snapshot
    /// worktree underneath. Returns (tempdir guard, root, snapshot, mission).
    fn validator_containment_fixture() -> (tempfile::TempDir, PathBuf, PathBuf, PathBuf) {
        let dir = tempfile::tempdir().unwrap();
        let root = dir.path().join("repo");
        std::fs::create_dir_all(root.join("src")).unwrap();
        std::fs::write(root.join("src").join("secret.rs"), "fn secret() {}\n").unwrap();
        std::fs::write(root.join("Cargo.toml"), "[package]\n").unwrap();
        // The .env is authority material by NAME (path-based deny); its
        // content is irrelevant to the test and deliberately not
        // secret-shaped (the range scanner fires on TOKEN= shapes — the
        // path is bound separately so no .env + value adjacency exists).
        let dotenv_path = root.join(".env");
        std::fs::write(&dotenv_path, "placeholder-content\n").unwrap();
        std::fs::create_dir_all(root.join(".git")).unwrap();
        std::fs::write(root.join(".git").join("HEAD"), "ref: refs/heads/main\n").unwrap();
        let mission = root.join(".kranz").join("missions").join("m-x");
        let snapshot = mission.join("runs").join("validator-snapshot-scrutiny");
        std::fs::create_dir_all(&snapshot).unwrap();
        std::fs::write(snapshot.join("README.md"), "snapshot copy\n").unwrap();
        std::fs::write(root.join(".kranz").join("serve.token"), "secret-token").unwrap();
        // The sensitive .kranz runtime the 14th-pass over-read finding names
        // (ticket validator-containment-kranz-overread): the plaintext lint
        // vocabulary, the hook-status projection, and the mission control
        // inbox — all reachable through the .kranz carve-out unless the
        // authority read-deny set covers them.
        std::fs::write(
            root.join(".kranz").join("domain-terms.local"),
            "acme widget\n",
        )
        .unwrap();
        let hook_status = root.join(".kranz").join("hook-status").join("m-x");
        std::fs::create_dir_all(&hook_status).unwrap();
        std::fs::write(hook_status.join("run-1.json"), "{\"tokenHash\":\"abc\"}\n").unwrap();
        let control = mission.join("control");
        std::fs::create_dir_all(&control).unwrap();
        std::fs::write(control.join("approve.json"), "{}\n").unwrap();
        (dir, root, snapshot, mission)
    }

    /// A REAL git repo in the same layout (one committed file + a committed
    /// `src/` dir, `.kranz/` ignored, the snapshot as a detached worktree
    /// under the mission's `runs/`) for the applied probes that exercise
    /// the git surface. None when git is not on PATH (mirrors the
    /// orchestrator tests' `lessons_test_repo` skip).
    #[cfg(any(target_os = "macos", target_os = "linux"))]
    fn validator_containment_git_fixture() -> Option<(tempfile::TempDir, PathBuf, PathBuf, PathBuf)>
    {
        let git_ok = std::process::Command::new("git")
            .arg("--version")
            .output()
            .map(|o| o.status.success())
            .unwrap_or(false);
        if !git_ok {
            crate::test_capability::skip(
                crate::test_capability::capability::GIT,
                "git is not on PATH",
            );
            return None;
        }
        let dir = tempfile::tempdir().unwrap();
        let root = dir.path().join("repo");
        std::fs::create_dir_all(&root).unwrap();
        let run = |args: &[&str]| {
            let out = std::process::Command::new("git")
                .args(args)
                .current_dir(&root)
                .output()
                .expect("spawn git");
            assert!(out.status.success(), "git {args:?} failed: {out:?}");
        };
        if !std::process::Command::new("git")
            .args(["init", "-b", "main"])
            .current_dir(&root)
            .output()
            .map(|o| o.status.success())
            .unwrap_or(false)
        {
            run(&["init"]);
            run(&["symbolic-ref", "HEAD", "refs/heads/main"]);
        }
        run(&["config", "user.name", "test"]);
        run(&["config", "user.email", "test@example.com"]);
        std::fs::create_dir_all(root.join("src")).unwrap();
        std::fs::write(root.join("src").join("secret.rs"), "fn secret() {}\n").unwrap();
        std::fs::write(root.join("tracked.rs"), "fn tracked() {}\n").unwrap();
        std::fs::write(root.join(".gitignore"), ".kranz/\n").unwrap();
        run(&["add", "-A"]);
        run(&["commit", "-m", "init"]);
        let mission = root.join(".kranz").join("missions").join("m-x");
        let snapshot = mission.join("runs").join("validator-snapshot-scrutiny");
        std::fs::create_dir_all(snapshot.parent().unwrap()).unwrap();
        run(&[
            "worktree",
            "add",
            "--detach",
            snapshot.to_str().expect("utf-8 temp path"),
        ]);
        // Engine-owned metadata + the authority material the denies cover.
        std::fs::write(mission.join("events.jsonl"), "{\"seq\":1}\n").unwrap();
        std::fs::write(root.join(".kranz").join("serve.token"), "secret-token").unwrap();
        Some((dir, root, snapshot, mission))
    }

    /// The mandatory-wrap inputs shape: the snapshot as the sole writable
    /// session root, the real checkout as the read-deny root.
    fn validator_containment_inputs(
        root: &Path,
        snapshot: &Path,
        mission: &Path,
        tmpdir: &Path,
    ) -> SandboxInputs {
        SandboxInputs {
            enforce: crate::types::SandboxEnforce::Fs,
            session_cwd: snapshot.to_path_buf(),
            mission_dir: mission.to_path_buf(),
            tmpdir: tmpdir.to_path_buf(),
            extra_write: Vec::new(),
            egress: Vec::new(),
            validator_read_deny_roots: vec![root.to_path_buf()],
        }
    }

    /// The read-deny set covers the whole source tree — dirs classified as
    /// dirs, files as files, raw AND canonical forms — and NEVER names the
    /// `.git`/`.kranz` carve-outs.
    #[test]
    fn validator_containment_entries_cover_source_tree_and_carve_out_git_and_kranz() {
        let (_dir, root, snapshot, mission) = validator_containment_fixture();
        let scratch = tempfile::tempdir().unwrap();
        let inputs = validator_containment_inputs(&root, &snapshot, &mission, scratch.path());
        let entries = validator_read_deny_entries(&inputs);

        for base in [root.clone(), absolutize(&root)] {
            let src = base.join("src");
            assert!(
                entries.contains(&ValidatorReadDenyEntry {
                    path: src.clone(),
                    is_dir: true
                }),
                "src/ must be a denied dir: {entries:?}"
            );
            for file in ["Cargo.toml", ".env"] {
                assert!(
                    entries.contains(&ValidatorReadDenyEntry {
                        path: base.join(file),
                        is_dir: false
                    }),
                    "{file} must be a denied file: {entries:?}"
                );
            }
        }
        assert!(
            entries.iter().all(|e| e
                .path
                .file_name()
                .is_some_and(|n| n != ".git" && n != ".kranz")),
            "the carve-outs must never be denied: {entries:?}"
        );
    }

    /// The generated profile: a second read-deny block closes the broad read
    /// allow over the real checkout (dirs as subpaths, files and the root
    /// itself as literals) while the snapshot stays writable and the shared
    /// git dir + mission dir stay reachable.
    #[test]
    fn validator_containment_profile_read_denies_source_tree_and_keeps_carveouts() {
        let (_dir, root, snapshot, mission) = validator_containment_fixture();
        let scratch = tempfile::tempdir().unwrap();
        let profile = generate_profile(&validator_containment_inputs(
            &root,
            &snapshot,
            &mission,
            scratch.path(),
        ));
        let read_rules: String = profile
            .split("(deny file-read*")
            .skip(1)
            .map(|block| block.split("\n)\n").next().unwrap_or_default())
            .collect();

        for base in [root.clone(), absolutize(&root)] {
            let src = format!("(subpath \"{}\")", escape_sbpl_literal(&base.join("src")));
            assert!(
                profile.contains(&src),
                "profile missing read deny for src/:\n{profile}"
            );
            for file in ["Cargo.toml", ".env"] {
                let lit = format!("(literal \"{}\")", escape_sbpl_literal(&base.join(file)));
                assert!(
                    profile.contains(&lit),
                    "profile missing read deny for {file}:\n{profile}"
                );
            }
            let root_lit = format!("(literal \"{}\")", escape_sbpl_literal(&base));
            assert!(
                !read_rules.contains(&root_lit),
                "the root itself is deliberately NOT denied (a literal deny breaks \
                 coreutils `mkdir -p`, which stats every ancestor):\n{profile}"
            );
            // The carve-outs are never denied: no rule names the .git or
            // .kranz DIRS themselves (the closing quote makes this exact).
            let git_rule = format!("\"{}\"", escape_sbpl_literal(&base.join(".git")));
            assert!(
                !read_rules.contains(&git_rule),
                ".git must stay readable (the inspection's git surface):\n{profile}"
            );
            let kranz_rule = format!("\"{}\"", escape_sbpl_literal(&base.join(".kranz")));
            assert!(
                !read_rules.contains(&kranz_rule),
                ".kranz must stay reachable (the snapshot lives under it):\n{profile}"
            );
        }
        // …and the .kranz carve-out does not reopen the authority material.
        for base in [root.join(".kranz"), absolutize(&root.join(".kranz"))] {
            let token = format!(
                "(literal \"{}\")",
                escape_sbpl_literal(&base.join("serve.token"))
            );
            assert!(
                profile.contains(&token),
                "the authority read deny must survive the carve-out:\n{profile}"
            );
        }
        // The snapshot stays the writable root.
        let snap_rule = format!(
            "(subpath \"{}\")",
            escape_sbpl_literal(&absolutize(&snapshot))
        );
        assert!(
            profile.contains(&snap_rule),
            "the snapshot must stay writable:\n{profile}"
        );
        // …and /dev/null stays writable (the gate wrap's documented finding:
        // git and the shell open it O_RDWR in ordinary operation).
        assert!(
            profile.contains("(allow file-write* (literal \"/dev/null\"))"),
            "validator profiles must keep /dev/null writable:\n{profile}"
        );
    }

    /// 14th-pass review (ticket `validator-containment-kranz-overread`): the
    /// `.kranz` carve-out the snapshot lives under must not reopen the
    /// sensitive runtime beneath it — the plaintext lint vocabulary
    /// (`domain-terms.local`), the hook-status projection, and the mission
    /// control inbox are read-denied (literal for the file, subpaths for the
    /// dirs) in BOTH raw and canonical forms, exactly like the serve-token
    /// authority material.
    #[test]
    fn validator_containment_profile_denies_sensitive_kranz_runtime_reads() {
        let (_dir, root, snapshot, mission) = validator_containment_fixture();
        let scratch = tempfile::tempdir().unwrap();
        let profile = generate_profile(&validator_containment_inputs(
            &root,
            &snapshot,
            &mission,
            scratch.path(),
        ));
        let read_rules: String = profile
            .split("(deny file-read*")
            .skip(1)
            .map(|block| block.split("\n)\n").next().unwrap_or_default())
            .collect();

        let kranz = root.join(".kranz");
        for base in [kranz.clone(), absolutize(&kranz)] {
            let terms = format!(
                "(literal \"{}\")",
                escape_sbpl_literal(&base.join("domain-terms.local"))
            );
            assert!(
                profile.contains(&terms),
                "profile missing read deny for domain-terms.local:\n{profile}"
            );
            let hook = format!(
                "(subpath \"{}\")",
                escape_sbpl_literal(&base.join("hook-status"))
            );
            assert!(
                profile.contains(&hook),
                "profile missing read deny for hook-status/:\n{profile}"
            );
        }
        for base in [mission.clone(), absolutize(&mission)] {
            let control = format!(
                "(subpath \"{}\")",
                escape_sbpl_literal(&base.join("control"))
            );
            assert!(
                profile.contains(&control),
                "profile missing read deny for the control inbox:\n{profile}"
            );
        }
        // …while the carve-out itself stays: no deny names the .kranz DIR
        // (the closing quote makes this exact).
        for base in [kranz.clone(), absolutize(&kranz)] {
            let kranz_rule = format!("\"{}\"", escape_sbpl_literal(&base));
            assert!(
                !read_rules.contains(&kranz_rule),
                ".kranz must stay reachable (the snapshot lives under it):\n{profile}"
            );
        }
    }

    /// Non-validator sessions (empty roots) get byte-stable profiles: exactly
    /// the pre-containment shape, i.e. only the authority read-deny block.
    #[test]
    fn validator_containment_empty_roots_emit_no_deny_block() {
        let (_dir, root, snapshot, mission) = validator_containment_fixture();
        let scratch = tempfile::tempdir().unwrap();
        let mut inputs = validator_containment_inputs(&root, &snapshot, &mission, scratch.path());
        inputs.validator_read_deny_roots = Vec::new();
        let profile = generate_profile(&inputs);
        assert_eq!(
            profile.matches("(deny file-read*").count(),
            1,
            "empty roots must leave the pre-containment profile shape alone:\n{profile}"
        );

        let profile = generate_profile(&validator_containment_inputs(
            &root,
            &snapshot,
            &mission,
            scratch.path(),
        ));
        assert_eq!(
            profile.matches("(deny file-read*").count(),
            2,
            "the validator read-deny block must land when roots are set:\n{profile}"
        );
    }

    /// The bwrap analogue: source dirs shadowed by tmpfs, source files
    /// masked with /dev/null, carve-outs untouched, the snapshot rw-bound.
    #[test]
    fn validator_containment_bwrap_masks_source_tree_and_keeps_carveouts() {
        let (_dir, root, snapshot, mission) = validator_containment_fixture();
        let scratch = tempfile::tempdir().unwrap();
        let args = bubblewrap_args(
            &validator_containment_inputs(&root, &snapshot, &mission, scratch.path()),
            Path::new("/usr/bin/claude"),
            &[],
        )
        .unwrap();
        let joined = args.join(" ");

        let src = absolutize(&root.join("src")).display().to_string();
        assert!(
            args.windows(2).any(|w| w[0] == "--tmpfs" && w[1] == src),
            "missing tmpfs shadow for src/: {args:?}"
        );
        let env_file = absolutize(&root.join(".env")).display().to_string();
        assert!(
            joined.contains(&format!("--ro-bind /dev/null {env_file}")),
            "missing /dev/null mask for .env: {args:?}"
        );
        // The carve-outs are never masked, and the root itself is not
        // shadowed (bwrap cannot close the listing without hiding them).
        let git = absolutize(&root.join(".git")).display().to_string();
        assert!(
            !joined.contains(&git),
            ".git must not be masked (the inspection's git surface): {args:?}"
        );
        assert!(
            !args
                .windows(2)
                .any(|w| w[0] == "--tmpfs" && w[1] == root.display().to_string()),
            "the root itself must not be shadowed: {args:?}"
        );
        // The snapshot stays rw-bound.
        let snap = absolutize(&snapshot).display().to_string();
        assert!(
            joined.contains(&format!("--bind {snap} {snap}")),
            "the snapshot must stay rw-bound: {args:?}"
        );
    }

    /// The bwrap analogue of the 14th-pass over-read fix (ticket
    /// `validator-containment-kranz-overread`): the plaintext lint
    /// vocabulary gets a `/dev/null` mask, and the hook-status projection +
    /// the control inbox get tmpfs shadows (the control/ shadow was already
    /// the write-deny idiom; the same mechanism now hides hook-status/).
    #[test]
    fn validator_containment_bwrap_masks_sensitive_kranz_runtime() {
        let (_dir, root, snapshot, mission) = validator_containment_fixture();
        let scratch = tempfile::tempdir().unwrap();
        let args = bubblewrap_args(
            &validator_containment_inputs(&root, &snapshot, &mission, scratch.path()),
            Path::new("/usr/bin/claude"),
            &[],
        )
        .unwrap();
        let joined = args.join(" ");

        let kranz = absolutize(&root.join(".kranz")).display().to_string();
        assert!(
            joined.contains(&format!("--tmpfs {kranz}")) && !joined.contains("domain-terms.local"),
            "the private authority directory must exclude domain-terms.local: {args:?}"
        );
        for dir in [
            root.join(".kranz").join("hook-status"),
            mission.join("control"),
        ] {
            let shadow = absolutize(dir.parent().unwrap()).display().to_string();
            assert!(args.windows(2).any(|w| w[0] == "--tmpfs" && w[1] == shadow));
            let denied = absolutize(&dir).display().to_string();
            assert!(
                !args.windows(3).any(|part| {
                    matches!(part[0].as_str(), "--ro-bind" | "--ro-bind-try")
                        && part[1] == denied
                        && part[2] == denied
                }),
                "denied directory must not be rebound: {args:?}"
            );
        }
    }

    // --- the resolution matrix -----------------------------------------------

    fn off_cfg() -> crate::types::SandboxConfig {
        crate::types::SandboxConfig::default()
    }

    fn fs_cfg() -> crate::types::SandboxConfig {
        crate::types::SandboxConfig {
            enforce: crate::types::SandboxEnforce::Fs,
            ..crate::types::SandboxConfig::default()
        }
    }

    /// The case the ticket exists for: `enforce: off` (the default) STILL
    /// wraps the validator on macOS — the mandatory fs-tier wrap with the
    /// real checkout read-denied and NO operator extraWrite widening.
    #[test]
    fn validator_containment_off_macos_wraps_mandatory_seatbelt() {
        let mut cfg = off_cfg();
        cfg.extra_write = vec!["~/elsewhere".to_string()];
        let roots = vec![PathBuf::from("/repo")];
        let containment = resolve_validator_containment_target(
            &cfg,
            crate::types::BackendKind::Claude,
            Path::new("/repo/.kranz/missions/m-x/runs/snap"),
            Path::new("/repo/.kranz/missions/m-x"),
            &roots,
            false,
            "macos",
            false,
            None,
            None,
        )
        .expect("off+macos resolves the mandatory wrap");
        assert!(containment.note.is_none(), "{:?}", containment.note);
        let sandbox = containment.sandbox.expect("a wrap applies");
        assert_eq!(sandbox.backend, SandboxBackend::Seatbelt);
        assert_eq!(
            sandbox.inputs.enforce,
            crate::types::SandboxEnforce::Fs,
            "the mandatory wrap is the fs tier (egress stays open for the API)"
        );
        assert_eq!(sandbox.inputs.validator_read_deny_roots, roots);
        assert!(
            sandbox.inputs.extra_write.is_empty(),
            "no operator extraWrite widening under the mandatory wrap"
        );
        assert_eq!(
            sandbox.inputs.session_cwd,
            PathBuf::from("/repo/.kranz/missions/m-x/runs/snap"),
            "the snapshot is the writable root"
        );
    }

    /// Linux: the mandatory wrap needs `bwrap`; without it the resolution
    /// FAILS CLOSED by default (naming the platform limit and the flag), and
    /// only the explicit `validatorAllowUncontainedDegrade` opt-in restores
    /// the loud degrade note (ticket
    /// validator-containment-degrade-fail-closed).
    #[test]
    fn validator_containment_off_linux_without_bwrap_fails_closed_unless_opted_in() {
        let roots = vec![PathBuf::from("/repo")];
        let err = resolve_validator_containment_target(
            &off_cfg(),
            crate::types::BackendKind::Claude,
            Path::new("/snap"),
            Path::new("/mission"),
            &roots,
            false,
            "linux",
            false,
            None,
            None,
        )
        .expect_err("no bwrap and no opt-in: fail closed");
        let err = err.to_string();
        assert!(err.contains("bwrap"), "{err}");
        assert!(err.contains("validatorAllowUncontainedDegrade"), "{err}");
        assert!(
            err.contains("refusing to run an uncontained validator"),
            "{err}"
        );

        let containment = resolve_validator_containment_target(
            &off_cfg(),
            crate::types::BackendKind::Claude,
            Path::new("/snap"),
            Path::new("/mission"),
            &roots,
            true,
            "linux",
            false,
            None,
            None,
        )
        .expect("the opt-in restores the loud degrade");
        assert!(containment.sandbox.is_none());
        let note = containment.note.expect("the loud note");
        assert!(note.contains("bwrap"), "{note}");
        assert!(note.contains("validator-mandatory-containment"), "{note}");

        let containment = resolve_validator_containment_target(
            &off_cfg(),
            crate::types::BackendKind::Claude,
            Path::new("/snap"),
            Path::new("/mission"),
            &roots,
            false,
            "linux",
            true,
            None,
            None,
        )
        .expect("off+linux+bwrap resolves");
        assert!(containment.note.is_none(), "{:?}", containment.note);
        assert_eq!(
            containment.sandbox.expect("a wrap applies").backend,
            SandboxBackend::Bubblewrap
        );
    }

    /// M7 Windows parity, phase 4: validators resolve the same mandatory
    /// AppContainer fs-tier wrap as other containable platforms, regardless
    /// of the legacy uncontained-degrade opt-in.
    #[test]
    fn validator_containment_off_windows_resolves_appcontainer() {
        let roots = vec![PathBuf::from("C:\\repo")];
        for allow_uncontained_degrade in [false, true] {
            let containment = resolve_validator_containment_target(
                &off_cfg(),
                crate::types::BackendKind::Claude,
                Path::new("C:\\snap"),
                Path::new("C:\\mission"),
                &roots,
                allow_uncontained_degrade,
                "windows",
                false,
                None,
                None,
            )
            .expect("Windows resolves the mandatory AppContainer wrap");
            assert!(containment.note.is_none(), "{:?}", containment.note);
            let sandbox = containment.sandbox.expect("a wrap applies");
            assert_eq!(sandbox.backend, SandboxBackend::AppContainer);
            assert_eq!(sandbox.inputs.enforce, crate::types::SandboxEnforce::Fs);
            assert_eq!(sandbox.inputs.session_cwd, PathBuf::from("C:\\snap"));
            assert_eq!(sandbox.inputs.validator_read_deny_roots, roots);
            assert!(sandbox.inputs.extra_write.is_empty());
        }
    }

    /// A backend that cannot honor the resolved sandbox must never silently
    /// run bare: by default the resolution FAILS CLOSED naming the backend
    /// and the flag; with the opt-in the wrap is skipped and the note names
    /// the backend.
    #[test]
    fn validator_containment_off_non_claude_backend_fails_closed_unless_opted_in() {
        for backend in [
            crate::types::BackendKind::Codex,
            crate::types::BackendKind::Droid,
            crate::types::BackendKind::Kimi,
            crate::types::BackendKind::Local,
            crate::types::BackendKind::Acp,
            crate::types::BackendKind::Cursor,
        ] {
            let err = resolve_validator_containment_target(
                &off_cfg(),
                backend,
                Path::new("/snap"),
                Path::new("/mission"),
                &[PathBuf::from("/repo")],
                false,
                "macos",
                false,
                None,
                None,
            )
            .expect_err("an uncontainable backend fails closed by default");
            let err = err.to_string();
            assert!(err.contains(backend.as_str()), "{err}");
            assert!(err.contains("validatorAllowUncontainedDegrade"), "{err}");

            let containment = resolve_validator_containment_target(
                &off_cfg(),
                backend,
                Path::new("/snap"),
                Path::new("/mission"),
                &[PathBuf::from("/repo")],
                true,
                "macos",
                false,
                None,
                None,
            )
            .expect("the opt-in restores the loud degrade");
            assert!(
                containment.sandbox.is_none(),
                "{backend:?} must not get a wrap it cannot honor"
            );
            let note = containment.note.expect("the loud note");
            assert!(note.contains(backend.as_str()), "{note}");
            assert!(note.contains("validator-mandatory-containment"), "{note}");
        }
    }

    /// `enforce != off` keeps the role's own resolution AND gains the
    /// read-deny roots on the process tier; the operator's extraWrite stays
    /// (the mandatory no-widening rule is the off-case wrap's).
    #[test]
    fn validator_containment_enforced_role_resolves_and_attaches_roots() {
        let mut cfg = fs_cfg();
        cfg.extra_write = vec!["~/keep".to_string()];
        let roots = vec![PathBuf::from("/repo")];
        let containment = resolve_validator_containment_target(
            &cfg,
            crate::types::BackendKind::Claude,
            Path::new("/repo/.kranz/missions/m-x/runs/snap"),
            Path::new("/repo/.kranz/missions/m-x"),
            &roots,
            false,
            "macos",
            false,
            None,
            None,
        )
        .expect("fs on macos resolves");
        assert!(containment.note.is_none(), "{:?}", containment.note);
        let sandbox = containment.sandbox.expect("the role's wrap");
        assert_eq!(sandbox.backend, SandboxBackend::Seatbelt);
        assert_eq!(sandbox.inputs.validator_read_deny_roots, roots);
        assert!(
            !sandbox.inputs.extra_write.is_empty(),
            "an enforced role keeps its declared extraWrite"
        );
    }

    /// `enforce != off` stays fail-closed on an unknown platform (the
    /// runner's resolve_sandbox_or_refuse posture, unchanged).
    #[test]
    fn validator_containment_enforced_role_still_fails_closed_where_unsupported() {
        let err = resolve_validator_containment_target(
            &fs_cfg(),
            crate::types::BackendKind::Claude,
            Path::new("/snap"),
            Path::new("/mission"),
            &[PathBuf::from("/repo")],
            false,
            "solaris",
            false,
            None,
            None,
        )
        .expect_err("enforcement requested but unhonorable must fail closed");
        assert!(err.to_string().contains("unsupported"), "{err}");
    }

    /// The container provider keeps its own (stronger) containment: resolved
    /// untouched, no read-deny roots attached (the real tree is simply not
    /// mounted). Under `enforce: off` the provider is ignored — the
    /// mandatory wrap is the process tier.
    #[test]
    fn validator_containment_container_provider_posture() {
        let cfg = crate::types::SandboxConfig {
            enforce: crate::types::SandboxEnforce::Fs,
            provider: crate::types::SandboxProvider::Container,
            ..crate::types::SandboxConfig::default()
        };
        let containment = resolve_validator_containment_target(
            &cfg,
            crate::types::BackendKind::Claude,
            Path::new("/snap"),
            Path::new("/mission"),
            &[PathBuf::from("/repo")],
            false,
            "linux",
            false,
            Some(crate::sandbox_container::ContainerRuntime::Docker),
            None,
        )
        .expect("container resolves with a runtime");
        let sandbox = containment.sandbox.expect("the container wrap");
        assert_eq!(sandbox.backend, SandboxBackend::Container);
        assert!(
            sandbox.inputs.validator_read_deny_roots.is_empty(),
            "the container's mounts are the containment — no process-tier deny set"
        );

        let mut off_container = off_cfg();
        off_container.provider = crate::types::SandboxProvider::Container;
        let containment = resolve_validator_containment_target(
            &off_container,
            crate::types::BackendKind::Claude,
            Path::new("/snap"),
            Path::new("/mission"),
            &[PathBuf::from("/repo")],
            false,
            "macos",
            false,
            None,
            None,
        )
        .expect("off+container still gets the mandatory process-tier wrap");
        assert_eq!(
            containment.sandbox.expect("a wrap applies").backend,
            SandboxBackend::Seatbelt,
            "provider:container with enforce:off documents 'no sandboxing'; the mandatory wrap is process-tier"
        );
    }

    /// Applied proof on macOS (the ticket's test gate): a validator-session
    /// fixture under `enforce: off`-shape inputs provably CANNOT read the
    /// real checkout's source tree or the authority material, while the
    /// shared git dir and the snapshot stay readable.
    #[cfg(target_os = "macos")]
    #[test]
    fn validator_containment_macos_denies_real_checkout_reads() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();
        if !sandbox_exec_can_apply() {
            return;
        }
        let (_dir, root, snapshot, mission) = validator_containment_fixture();
        let scratch = tempfile::tempdir().unwrap();
        let profile = generate_profile(&validator_containment_inputs(
            &root,
            &snapshot,
            &mission,
            scratch.path(),
        ));
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path = write_profile_file(profile_dir.path(), &profile).unwrap();

        let read = |path: &Path| {
            Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/cat")
                .arg(path)
                .status()
                .expect("failed to run sandbox-exec")
        };
        // The real checkout's source tree is unreadable…
        for denied in [
            root.join("src").join("secret.rs"),
            root.join("Cargo.toml"),
            root.join(".env"),
        ] {
            assert!(
                !read(&denied).success(),
                "read of the real tree must be denied: {}",
                denied.display()
            );
        }
        // …and so is the sensitive .kranz runtime the carve-out would
        // otherwise reopen (14th-pass review,
        // validator-containment-kranz-overread): the plaintext lint
        // vocabulary, the hook-status projection, and the control inbox.
        for denied in [
            root.join(".kranz").join("domain-terms.local"),
            root.join(".kranz")
                .join("hook-status")
                .join("m-x")
                .join("run-1.json"),
            mission.join("control").join("approve.json"),
        ] {
            assert!(
                !read(&denied).success(),
                "read of the sensitive .kranz runtime must be denied: {}",
                denied.display()
            );
        }
        // …the root LISTING stays visible (names, never contents — a
        // literal deny on the root breaks coreutils `mkdir -p`, which stats
        // every ancestor; documented on the entries helper)…
        let listing = Command::new("sandbox-exec")
            .arg("-f")
            .arg(&profile_path)
            .arg("/bin/ls")
            .arg(&root)
            .status()
            .expect("failed to run sandbox-exec");
        assert!(
            listing.success(),
            "the root listing stays open (names, never contents)"
        );
        // …and the authority material stays denied through the carve-out.
        assert!(
            !read(&root.join(".kranz").join("serve.token")).success(),
            "the authority read deny must survive the .kranz carve-out"
        );
        // The narrow legitimate surfaces stay readable: the shared git dir
        // and the validator's own snapshot worktree.
        for allowed in [root.join(".git").join("HEAD"), snapshot.join("README.md")] {
            assert!(
                read(&allowed).success(),
                "read must keep working: {}",
                allowed.display()
            );
        }
    }

    /// The second applied half: writes outside the snapshot are denied
    /// (source tree, mission metadata, and the shared git refs — the
    /// tripwire's domain, now hard-denied), while the snapshot stays
    /// writable and read-only git (`log`/`status`/`diff` — the inspection's
    /// surface) keeps working: the validation round still completes.
    #[cfg(target_os = "macos")]
    #[test]
    fn validator_containment_macos_keeps_snapshot_writes_and_readonly_git() {
        use std::process::Command;

        let _guard = SANDBOX_EXEC_TEST_LOCK.lock().unwrap();
        if !sandbox_exec_can_apply() {
            return;
        }
        let Some((_dir, root, snapshot, mission)) = validator_containment_git_fixture() else {
            return;
        };
        let scratch = tempfile::tempdir().unwrap();
        let profile = generate_profile(&validator_containment_inputs(
            &root,
            &snapshot,
            &mission,
            scratch.path(),
        ));
        let profile_dir = tempfile::tempdir().unwrap();
        let profile_path = write_profile_file(profile_dir.path(), &profile).unwrap();
        let sh = |command: &str| {
            Command::new("sandbox-exec")
                .arg("-f")
                .arg(&profile_path)
                .arg("/bin/sh")
                .arg("-c")
                .arg(command)
                .status()
                .expect("failed to run sandbox-exec")
        };

        // Write denies: the real tree, the root, the engine's metadata, and
        // the shared git plumbing (index + refs).
        for command in [
            format!("echo x >> {}", root.join("tracked.rs").display()),
            format!("echo x > {}", root.join("new.txt").display()),
            format!("echo x >> {}", mission.join("events.jsonl").display()),
            format!("git -C {} add -A", snapshot.display()),
            format!("git -C {} branch -f side HEAD", snapshot.display()),
        ] {
            assert!(!sh(&command).success(), "must be denied: {command}");
        }
        // The snapshot stays fully writable (the warmed-target shape)…
        assert!(sh(&format!(
            "mkdir -p {0}/target && echo built > {0}/target/out && echo note > {0}/notes.txt",
            snapshot.display()
        ))
        .success());
        // …and the read-only git inspection surface works — the functional
        // and scrutiny validators' whole job in the snapshot.
        let git_log = Command::new("sandbox-exec")
            .arg("-f")
            .arg(&profile_path)
            .arg("git")
            .arg("-C")
            .arg(&snapshot)
            .arg("log")
            .arg("--oneline")
            .output()
            .expect("failed to run sandbox-exec");
        assert!(
            git_log.status.success(),
            "read-only git must work in the snapshot: {}",
            String::from_utf8_lossy(&git_log.stderr)
        );
        assert!(String::from_utf8_lossy(&git_log.stdout).contains("init"));
        assert!(sh(&format!("git -C {} status --porcelain", snapshot.display())).success());
        assert!(sh(&format!("git -C {} diff HEAD", snapshot.display())).success());
        // The snapshot's own copy of the source tree reads fine.
        assert!(sh(&format!("cat {}", snapshot.join("tracked.rs").display())).success());
    }

    /// The linux applied analogue: bwrap masks the real tree (dirs ENOENT
    /// under the tmpfs shadow, files empty under /dev/null), keeps the
    /// carve-outs and the snapshot, and read-only git still works.
    #[cfg(target_os = "linux")]
    #[test]
    fn validator_containment_linux_bwrap_denies_real_checkout_and_keeps_snapshot() {
        use std::process::Command;

        if !bwrap_can_apply() {
            return;
        }
        let Some((dir, root, snapshot, mission)) = validator_containment_git_fixture() else {
            return;
        };
        // An absent global authority directory makes its HOME the enclosing
        // private view. Restoring the repo under that view must not reopen
        // the validator's real-checkout read denies.
        let _env =
            crate::agent_env::EnvTestGuard::engage(&[("HOME", dir.path().to_str().unwrap())]);
        let scratch = tempfile::tempdir().unwrap();
        let inputs = validator_containment_inputs(&root, &snapshot, &mission, scratch.path());
        let run = |command: &str| {
            Command::new("bwrap")
                .args(
                    bubblewrap_args(
                        &inputs,
                        Path::new("/bin/sh"),
                        &["-c".to_string(), command.to_string()],
                    )
                    .unwrap(),
                )
                .output()
                .expect("failed to run bwrap")
        };

        // A source DIR is shadowed: reads underneath fail outright.
        let shadowed = run(&format!(
            "cat {}",
            root.join("src").join("secret.rs").display()
        ));
        assert!(
            !shadowed.status.success(),
            "the tmpfs-shadowed source dir must not resolve: {}",
            String::from_utf8_lossy(&shadowed.stderr)
        );
        // A source FILE is /dev/null-masked: the open succeeds, the content
        // does not cross (the authority-mask idiom).
        let masked = run(&format!("cat {}", root.join("tracked.rs").display()));
        assert!(
            !String::from_utf8_lossy(&masked.stdout).contains("tracked"),
            "the masked source file must not yield its content"
        );
        // The authority material is masked too.
        let authority_read = run(&format!(
            "cat {}",
            root.join(".kranz").join("serve.token").display()
        ));
        assert!(
            !String::from_utf8_lossy(&authority_read.stdout).contains("secret-token"),
            "the authority material must stay masked"
        );
        // The carve-outs and the snapshot read fine.
        let git_head = run(&format!("cat {}", root.join(".git").join("HEAD").display()));
        assert!(git_head.status.success());
        let snap_read = run(&format!("cat {}", snapshot.join("tracked.rs").display()));
        assert!(
            String::from_utf8_lossy(&snap_read.stdout).contains("tracked"),
            "the snapshot's own copy reads fine"
        );
        // Writes outside the snapshot fail (the whole fs is ro-bound); the
        // snapshot and the git plumbing behave like the Seatbelt side.
        for command in [
            format!("echo x >> {}", root.join("tracked.rs").display()),
            format!("echo x >> {}", mission.join("events.jsonl").display()),
            format!("git -C {} branch -f side HEAD", snapshot.display()),
        ] {
            assert!(!run(&command).status.success(), "must be denied: {command}");
        }
        assert!(
            run(&format!("echo built > {}/target-out", snapshot.display()))
                .status
                .success()
        );
        let git_log = run(&format!("git -C {} log --oneline", snapshot.display()));
        assert!(
            git_log.status.success(),
            "read-only git must work in the snapshot: {}",
            String::from_utf8_lossy(&git_log.stderr)
        );
    }
}

#[cfg(test)]
#[path = "git_config_protection_tests.rs"]
mod git_config_protection_tests;