feat(permissions): LP4-3 — activation bout-en-bout de la sandbox OS au runtime

Composition root : PortablePtyAdapter::new() injecte désormais default_enforcer()
(Landlock sur Linux / Noop ailleurs) via with_sandbox_enforcer, dans state.rs et
dans LocalHost (remote/mod.rs).

Launch path : LaunchAgent::execute peuple spec.sandbox via le plan pur
compile_sandbox_plan(effective_permissions, SandboxContext{project_root, run_dir}),
en réutilisant l'EffectivePermissions déjà résolu pour la projection advisory LP3.
Invariant produit conservé : eff == None ⇒ plan None ⇒ comportement natif, aucune
projection OS.

Portée : seul le chemin PTY brut est OS-enforcé ; le chemin structuré (Claude/Codex
mode JSON) porte le plan mais ne l'enforce pas encore (lot ultérieur).

Tests : ajout d'un test d'intégration bout-en-bout (pty/mod.rs, sandbox_e2e_tests)
prouvant qu'un enfant spawné sous un plan RW restreint ne peut PAS écrire hors-grant
(écriture bloquée par le kernel) alors que l'écriture dans le grant passe, plus un
test compagnon anti faux-positif (sans plan ⇒ pas de sandbox). Skip propre si le
kernel n'a pas Landlock. domain+infrastructure+application+app-tauri verts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/infrastructure/src/pty/mod.rs

@@ -446,3 +446,178 @@ mod tests {
         assert_eq!(hub.snapshot(), b"abc".to_vec());
     }
 }
+
+/// **End-to-end PTY × Landlock enforcement (lot LP4-3).**
+///
+/// These tests prove the OS sandbox is *really live on the raw PTY path*: a real
+/// [`PortablePtyAdapter`] wired with the Landlock enforcer, a [`SpawnSpec`] whose
+/// `sandbox = Some(plan)`, and a harmless `sh -c` that tries to write **inside** the
+/// granted root (must succeed) and **outside** it (must be blocked by the kernel).
+/// No AI CLI is launched — zero tokens. The whole chain enforcer → spec.sandbox →
+/// `spawn` → `spawn_command_sandboxed` → restricted thread → fork/exec is exercised.
+#[cfg(all(test, target_os = "linux"))]
+mod sandbox_e2e_tests {
+    use super::*;
+    use crate::sandbox::LandlockSandbox;
+    use domain::sandbox::{PathAccess, PathGrant, SandboxPlan, SandboxStatus};
+    use domain::terminal::PtySize;
+    use domain::Posture;
+    use std::path::{Path, PathBuf};
+    use std::time::{Duration, Instant};
+
+    /// A unique temp dir for one test (no external tempfile dep), mirroring the
+    /// helper used by the Landlock adapter tests.
+    fn fresh_dir(tag: &str) -> PathBuf {
+        let nanos = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_nanos();
+        let p = std::env::temp_dir().join(format!("idea-pty-sandbox-{tag}-{nanos}"));
+        std::fs::create_dir_all(&p).unwrap();
+        p
+    }
+
+    /// Probes whether the running kernel actually enforces Landlock, exactly the way
+    /// the launch path would observe it: enforce a tiny RW plan on a throwaway thread
+    /// (the restriction is irreversible, so it must not run on the test thread) and
+    /// report `false` when the adapter returns [`SandboxStatus::Unsupported`]. Lets us
+    /// skip cleanly on CI / old kernels without a Landlock LSM, like the adapter tests.
+    fn landlock_is_enforced() -> bool {
+        let probe = fresh_dir("probe");
+        let plan = SandboxPlan {
+            allowed: vec![PathGrant {
+                abs_root: probe.to_string_lossy().into_owned(),
+                access: PathAccess::RW,
+            }],
+            default_posture: Posture::Ask,
+        };
+        let status = std::thread::spawn(move || LandlockSandbox::new().enforce(&plan))
+            .join()
+            .unwrap()
+            .expect("enforce must not error under an Ask posture");
+        let _ = std::fs::remove_dir_all(&probe);
+        !matches!(status, SandboxStatus::Unsupported)
+    }
+
+    /// Waits (bounded) for `path` to appear, returning whether it showed up in time.
+    fn wait_for(path: &Path, timeout: Duration) -> bool {
+        let deadline = Instant::now() + timeout;
+        while Instant::now() < deadline {
+            if path.exists() {
+                return true;
+            }
+            std::thread::sleep(Duration::from_millis(25));
+        }
+        path.exists()
+    }
+
+    /// THE high-fidelity end-to-end proof. With the enforcer wired and a plan that
+    /// grants RW on `allowed` only, a child `sh` writing to **both** an out-of-grant
+    /// path and the granted path must have its out-of-grant write blocked while the
+    /// in-grant write lands on disk. The script writes the denied target *first*, so
+    /// once the allowed marker exists we know the denied write was already attempted
+    /// (and fenced) — making the assertion deterministic without racing the child.
+    #[tokio::test]
+    async fn pty_spawn_enforces_sandbox_plan_end_to_end() {
+        if !landlock_is_enforced() {
+            eprintln!("skipping pty_spawn_enforces_sandbox_plan_end_to_end: \
+                       Landlock not available/enforced on this kernel");
+            return;
+        }
+
+        let allowed = fresh_dir("allowed");
+        let denied = fresh_dir("denied");
+        let allowed_marker = allowed.join("in.txt");
+        let denied_marker = denied.join("out.txt");
+
+        // RW on `allowed` only ⇒ the write class is handled and fenced to that root;
+        // reads stay globally unrestricted so `sh`/libc still load normally.
+        let plan = SandboxPlan {
+            allowed: vec![PathGrant {
+                abs_root: allowed.to_string_lossy().into_owned(),
+                access: PathAccess::RW,
+            }],
+            default_posture: Posture::Ask,
+        };
+
+        // Denied write FIRST, then the allowed write: the allowed marker appearing is
+        // a happens-after signal that the denied attempt already ran.
+        let script = format!(
+            "echo outside > '{}'; echo inside > '{}'",
+            denied_marker.display(),
+            allowed_marker.display()
+        );
+        let spec = SpawnSpec {
+            command: "sh".to_owned(),
+            args: vec!["-c".to_owned(), script],
+            cwd: domain::project::ProjectPath::new(allowed.to_string_lossy().into_owned())
+                .expect("temp dir is absolute"),
+            env: vec![],
+            context_plan: None,
+            sandbox: Some(plan),
+        };
+
+        let adapter =
+            PortablePtyAdapter::new().with_sandbox_enforcer(crate::sandbox::default_enforcer());
+        let handle = adapter
+            .spawn(spec, PtySize { rows: 24, cols: 80 })
+            .await
+            .expect("sandboxed spawn must succeed (Ask posture never fails closed)");
+
+        // Wait for the in-grant write to land (the child's last action).
+        assert!(
+            wait_for(&allowed_marker, Duration::from_secs(5)),
+            "in-grant write must succeed: {allowed_marker:?} never appeared — \
+             the sandbox may have wrongly fenced the granted root"
+        );
+
+        // THE GUARANTEE: the out-of-grant write was attempted before the marker and
+        // must have been blocked by Landlock, so the file must not exist.
+        assert!(
+            !denied_marker.exists(),
+            "SANDBOX BREACH: out-of-grant write succeeded ({denied_marker:?} exists) — \
+             the Landlock plan was NOT enforced on the PTY child"
+        );
+
+        let _ = adapter.kill(&handle).await;
+        let _ = std::fs::remove_dir_all(&allowed);
+        let _ = std::fs::remove_dir_all(&denied);
+    }
+
+    /// Companion sanity check: with the **same** adapter+enforcer but a [`SpawnSpec`]
+    /// carrying `sandbox = None`, the out-of-grant write must succeed — proving the
+    /// previous test's block comes from the *enforced plan*, not from some ambient PTY
+    /// restriction. (Guards against a false-positive where writes fail for unrelated
+    /// reasons.) `denied` here is just an ordinary writable temp dir.
+    #[tokio::test]
+    async fn pty_spawn_without_plan_does_not_sandbox() {
+        let denied = fresh_dir("noplan");
+        let marker = denied.join("out.txt");
+        let script = format!("echo outside > '{}'", marker.display());
+
+        let spec = SpawnSpec {
+            command: "sh".to_owned(),
+            args: vec!["-c".to_owned(), script],
+            cwd: domain::project::ProjectPath::new(denied.to_string_lossy().into_owned())
+                .expect("temp dir is absolute"),
+            env: vec![],
+            context_plan: None,
+            sandbox: None,
+        };
+
+        let adapter =
+            PortablePtyAdapter::new().with_sandbox_enforcer(crate::sandbox::default_enforcer());
+        let handle = adapter
+            .spawn(spec, PtySize { rows: 24, cols: 80 })
+            .await
+            .expect("plain spawn must succeed");
+
+        assert!(
+            wait_for(&marker, Duration::from_secs(5)),
+            "without a sandbox plan the write must succeed: {marker:?} never appeared"
+        );
+
+        let _ = adapter.kill(&handle).await;
+        let _ = std::fs::remove_dir_all(&denied);
+    }
+}

crates/infrastructure/src/remote/mod.rs

@@ -38,7 +38,9 @@ impl LocalHost {
         Self {
             fs: Arc::new(LocalFileSystem::new()),
             spawner: Arc::new(LocalProcessSpawner::new()),
-            pty: Arc::new(PortablePtyAdapter::new()),
+            pty: Arc::new(
+                PortablePtyAdapter::new().with_sandbox_enforcer(crate::sandbox::default_enforcer()),
+            ),
         }
     }
 }