fix: guard mount-safe Workdir cleanup and current-condition recovery

Cargo.lock

@@ -6574,6 +6574,7 @@ dependencies = [
  "flow",
  "fs4",
  "futures",
+ "libc",
  "manifest",
  "protocol",
  "reqwest",

crates/worker-runtime/Cargo.toml

@@ -31,6 +31,7 @@ decodal.workspace = true
 flow = { path = "../flow" }
 fs4 = { workspace = true, optional = true }
 manifest.workspace = true
+libc.workspace = true
 protocol.workspace = true
 runtime-api.workspace = true
 serde = { workspace = true, features = ["derive"] }

crates/worker-runtime/src/http_server.rs

@@ -2486,6 +2486,8 @@ fn status_for_runtime_error(error: &RuntimeError) -> StatusCode {
             if matches!(
                 diagnostic.code.as_str(),
                 "repository_ref_provider_unavailable"
+                    | "working_directory_cleanup_mount_check_unavailable"
+                    | "working_directory_cleanup_storage_unavailable"
                     | "repository_ref_provider_timeout"
                     | "repository_access_provider_unavailable"
             ) =>
@@ -2504,6 +2506,23 @@ fn status_for_runtime_error(error: &RuntimeError) -> StatusCode {
         {
             StatusCode::FORBIDDEN
         }
+        RuntimeError::WorkingDirectory(diagnostic)
+            if matches!(
+                diagnostic.code.as_str(),
+                "working_directory_cleanup_mount_present"
+                    | "working_directory_cleanup_resource_busy"
+                    | "working_directory_cleanup_ownership_unknown"
+                    | "working_directory_cleanup_changes_present"
+                    | "working_directory_cleanup_changes_unknown"
+            ) =>
+        {
+            StatusCode::CONFLICT
+        }
+        RuntimeError::WorkingDirectory(diagnostic)
+            if diagnostic.code == "working_directory_cleanup_permission_denied" =>
+        {
+            StatusCode::FORBIDDEN
+        }
         RuntimeError::WorkingDirectory(diagnostic)
             if diagnostic.code == "repository_ref_not_found" =>
         {
@@ -4322,6 +4341,37 @@ mod tests {
         assert!(!error.to_string().contains('/'));
     }
 
+    #[tokio::test]
+    async fn cleanup_cause_codes_survive_http_error_serialization() {
+        let cases = [
+            ("mount_present", StatusCode::CONFLICT),
+            ("mount_check_unavailable", StatusCode::SERVICE_UNAVAILABLE),
+            ("permission_denied", StatusCode::FORBIDDEN),
+            ("resource_busy", StatusCode::CONFLICT),
+            ("storage_unavailable", StatusCode::SERVICE_UNAVAILABLE),
+            ("ownership_unknown", StatusCode::CONFLICT),
+            ("changes_present", StatusCode::CONFLICT),
+            ("changes_unknown", StatusCode::CONFLICT),
+        ];
+        for (cause, status) in cases {
+            let code = format!("working_directory_cleanup_{cause}");
+            let diagnostic = crate::working_directory::WorkingDirectoryDiagnostic::rejected(
+                &code,
+                "Resolve the current blocker and retry removal.",
+            );
+            let response =
+                RuntimeHttpRestError::runtime(RuntimeError::WorkingDirectory(diagnostic))
+                    .into_response();
+            assert_eq!(response.status(), status);
+            let body = axum::body::to_bytes(response.into_body(), 2048)
+                .await
+                .unwrap();
+            let json: serde_json::Value = serde_json::from_slice(&body).unwrap();
+            assert_eq!(json["error"]["code"], code, "{json}");
+            assert!(json["error"]["message"].as_str().unwrap().contains("retry"));
+        }
+    }
+
     #[test]
     fn workdir_runtime_errors_preserve_diagnostic_code() {
         let cases = [

crates/worker-runtime/src/runtime.rs

@@ -819,7 +819,13 @@ impl Runtime {
         &self,
         working_directory_id: &str,
     ) -> Result<CatalogWorkingDirectoryStatus, RuntimeError> {
-        let backend = {
+        // Hold occupancy authority through the side effect, preventing an
+        // attachment from entering between the check and physical removal.
+        // This synchronous provider call must not reenter Runtime. The Git
+        // materializer does filesystem/Git work only. The global guard also
+        // delays unrelated state operations during hashing/unlink; releasing it
+        // would require equivalent per-workdir exclusion on ALL attachment paths,
+        // not just moving the occupied check before the provider call.
         let state = self.lock()?;
         state.ensure_running()?;
         if let Some(worker_id) = state.worker_id_for_workdir(working_directory_id) {
@@ -827,15 +833,16 @@ impl Runtime {
                 "working directory {working_directory_id} is assigned to worker {worker_id}"
             )));
         }
-            state.execution_backend.clone().ok_or_else(|| {
+        let backend = state.execution_backend.clone().ok_or_else(|| {
             RuntimeError::ExecutionBackendUnavailable {
                 message: "working directory cleanup requires an execution backend".to_string(),
             }
-            })?
+        })?;
-        };
+        let result = backend
-        backend
             .cleanup_working_directory(working_directory_id)
-            .map_err(RuntimeError::from)
+            .map_err(RuntimeError::from);
+        drop(state);
+        result
     }
 
     fn annotate_working_directory_statuses(
@@ -7665,6 +7672,7 @@ mod tests {
         repository_accesses: Mutex<Vec<WorkingDirectoryRepositoryAccessRequest>>,
         repository_access_available: AtomicBool,
         working_directory_requests: Mutex<Vec<WorkingDirectoryRequest>>,
+        cleanup_occupancy_probe: Mutex<Option<Arc<Mutex<RuntimeState>>>>,
         preserve_submission_acknowledgement_id: AtomicBool,
         #[cfg(feature = "ws-server")]
         snapshots: Mutex<BTreeMap<WorkerId, protocol::Event>>,
@@ -7705,6 +7713,22 @@ mod tests {
     }
 
     impl WorkerExecutionBackend for TestExecutionBackend {
+        fn cleanup_working_directory(
+            &self,
+            _id: &str,
+        ) -> Result<CatalogWorkingDirectoryStatus, WorkingDirectoryDiagnostic> {
+            if let Some(state) = self.cleanup_occupancy_probe.lock().unwrap().as_ref() {
+                assert!(
+                    matches!(state.try_lock(), Err(std::sync::TryLockError::WouldBlock)),
+                    "occupancy must remain exclusive during physical cleanup"
+                );
+            }
+            Err(WorkingDirectoryDiagnostic::rejected(
+                "working_directory_cleanup_resource_busy",
+                "Retry removal after releasing the resource",
+            ))
+        }
+
         fn backend_id(&self) -> &str {
             "test-execution-backend"
         }
@@ -8043,6 +8067,22 @@ mod tests {
             .block_on(subscription.recv())
     }
 
+    #[test]
+    fn workdir_removal_keeps_occupancy_exclusive_during_provider_side_effect() {
+        let (runtime, backend) = runtime_and_backend();
+        *backend.cleanup_occupancy_probe.lock().unwrap() = Some(runtime.inner.clone());
+        let error = runtime
+            .cleanup_working_directory("workdir-test")
+            .unwrap_err();
+        assert!(
+            matches!(error, RuntimeError::WorkingDirectory(ref diagnostic)
+            if diagnostic.code == "working_directory_cleanup_resource_busy")
+        );
+        // The lock is released on failure, permitting normal attachment/retry.
+        assert!(runtime.inner.try_lock().is_ok());
+        *backend.cleanup_occupancy_probe.lock().unwrap() = None;
+    }
+
     #[test]
     fn unknown_typed_intent_is_rejected_before_backend_dispatch() {
         let (runtime, backend) = runtime_and_backend();

crates/worker-runtime/src/worker_backend.rs

@@ -19,7 +19,6 @@ use crate::catalog::{
     CreateWorkerRequest, ProfileSourceArchiveSource, RepositoryRefObservation,
     RepositoryRefObservationRequest, WorkingDirectoryAttachmentStatus,
     WorkingDirectoryRepositoryAccessRequest, WorkingDirectoryRequest, WorkingDirectoryStatus,
-    WorkingDirectoryStatusKind,
 };
 use crate::config_bundle::{ConfigBundle, workspace_config_etag};
 #[cfg(feature = "ws-server")]
@@ -3773,28 +3772,24 @@ where
                     )
                 })?;
             for previous in &request.previous_workdir_attachments {
-                let current = materializer
+                let relative_cwd = request
-                    .working_directory_status(
+                    .request
+                    .workdir_attachments
+                    .iter()
+                    .find(|claim| claim.alias == previous.alias)
+                    .and_then(|claim| claim.relative_cwd.as_deref());
+                // Recovery attachments remain CleanupPending across restart.
+                // Validate current bindability/identity, not the old state name.
+                // Preflight is read-only; actual restore binds again below.
+                materializer.preflight_bind_working_directory(
                     &previous.working_directory.summary.working_directory_id,
-                    )
+                    relative_cwd,
-                    .map_err(|message| {
+                ).map_err(|message| {
                     WorkerExecutionResult::rejected(
                         WorkerExecutionOperation::Restore,
-                            format!(
+                        format!("Persisted Worker Workdir attachment `{}` is unavailable: {message}", previous.alias),
-                                "Persisted Worker Workdir attachment `{}` is unavailable: {message}",
-                                previous.alias
-                            ),
                     )
                 })?;
-                if current.summary.status != WorkingDirectoryStatusKind::Active {
-                    return Err(WorkerExecutionResult::rejected(
-                        WorkerExecutionOperation::Restore,
-                        format!(
-                            "Persisted Worker Workdir attachment `{}` is not active",
-                            previous.alias
-                        ),
-                    ));
-                }
             }
         }
         if request.previous_workdir_attachments.is_empty()
@@ -4637,7 +4632,7 @@ mod tests {
         ConfigBundleRef, CreateWorkerRequest, LogicalWorkdirAttachment, MaterializerKind,
         ProfileSelector, RepositorySelector, WorkingDirectoryAttachmentClaim,
         WorkingDirectoryAttachmentRequest, WorkingDirectoryRepository, WorkingDirectoryRequest,
-        WorkspaceApiRef,
+        WorkingDirectoryStatusKind, WorkspaceApiRef,
     };
     use crate::execution::WorkerExecutionContext;
     use crate::identity::WorkerId;
@@ -8919,6 +8914,160 @@ mod tests {
         );
     }
 
+    #[cfg(target_os = "linux")]
+    fn pending_owner_restore_fixture() -> (
+        tempfile::TempDir,
+        WorkerRuntimeExecutionBackend<MockFactory>,
+        WorkerExecutionRestoreRequest,
+        PathBuf,
+        Arc<Mutex<Vec<PathBuf>>>,
+    ) {
+        use crate::working_directory::{WorkingDirectoryMaterializer, fail_workdir_cleanup_once};
+        let root = tempfile::tempdir().unwrap();
+        let repo = create_clean_repo();
+        let workdirs = root.path().join("workdirs");
+        let materializer = RuntimeGitMaterializer::new(&workdirs);
+        let binding = materializer
+            .create(&working_directory_request(repo.path()))
+            .unwrap();
+        let id = binding.working_directory.id.clone();
+        fail_workdir_cleanup_once(&materializer, &id);
+        // The cleanup owner has legitimately reattached to preserve these changes.
+        fs::write(binding.root.join("README.md"), "owner recovery in progress").unwrap();
+        let observed = Arc::new(Mutex::new(Vec::new()));
+        let factory = || MockFactory {
+            client: MockClient::new(simple_text_events()),
+            runtime_base: root.path().join("runtime"),
+            cwd: root.path().to_path_buf(),
+            store_dir: root.path().join("sessions"),
+            worker_metadata_dir: root.path().join("workers"),
+            observed_cwds: observed.clone(),
+            observed_workspace_clients: Arc::new(Mutex::new(Vec::new())),
+        };
+        let backend = Arc::new(
+            WorkerRuntimeExecutionBackend::new(factory())
+                .unwrap()
+                .with_working_directory_materializer(materializer),
+        );
+        let runtime =
+            EmbeddedRuntime::with_execution_backend(RuntimeOptions::default(), backend.clone())
+                .unwrap();
+        runtime.store_config_bundle(test_bundle()).unwrap();
+        let mut request = create_request("cleanup-owner");
+        request.workdir_attachments = vec![WorkingDirectoryAttachmentClaim {
+            alias: WorkdirAttachmentAlias::new("checkout").unwrap(),
+            working_directory_id: id,
+            relative_cwd: None,
+            capabilities: WorkdirSessionCapabilities::ALL,
+        }];
+        let detail = runtime.create_worker(request.clone()).unwrap();
+        runtime.stop_worker(&detail.worker_ref, None).unwrap();
+        let restore = WorkerExecutionRestoreRequest {
+            operation_id: crate::execution::WorkerLifecycleOperationId::new(),
+            worker_ref: detail.worker_ref.clone(),
+            request,
+            workspace_scope: None,
+            context: test_execution_context(detail.worker_ref),
+            previous_workdir_attachments: detail.workdir_attachments,
+            logical_workdir_attachments: Vec::new(),
+            workdir_attachments: BTreeMap::new(),
+            config_bundle: None,
+        };
+        drop(runtime);
+        drop(backend);
+        // A fresh backend/materializer loads the durable pending identity evidence.
+        let restarted = WorkerRuntimeExecutionBackend::new(factory())
+            .unwrap()
+            .with_working_directory_materializer(RuntimeGitMaterializer::new(&workdirs));
+        (root, restarted, restore, binding.root, observed)
+    }
+
+    #[cfg(target_os = "linux")]
+    #[test]
+    fn cleanup_pending_owner_restores_after_restart_with_validated_dirty_checkout() {
+        let (root, backend, request, checkout, observed) = pending_owner_restore_fixture();
+        let before = persisted_files(&root.path().join("workdirs"));
+        backend.preflight_restore(&request).unwrap();
+        assert_eq!(
+            persisted_files(&root.path().join("workdirs")),
+            before,
+            "preflight must not rewrite removal or Git authority"
+        );
+        let restored = match backend.restore_worker(request.clone()) {
+            WorkerExecutionSpawnResult::Connected {
+                workdir_attachments,
+                ..
+            } => workdir_attachments,
+            other => panic!("cleanup-owner restore failed: {other:?}"),
+        };
+        assert_eq!(restored.len(), 1);
+        assert_eq!(
+            restored[0].working_directory.summary.status,
+            WorkingDirectoryStatusKind::CleanupPending
+        );
+        assert_eq!(
+            restored[0].working_directory.summary.cleanliness.as_deref(),
+            Some("dirty")
+        );
+        assert_eq!(
+            observed.lock().unwrap().as_slice(),
+            &[checkout.clone(), checkout.clone()]
+        );
+        assert_eq!(
+            fs::read_to_string(checkout.join("README.md")).unwrap(),
+            "owner recovery in progress"
+        );
+        assert!(backend.stop_worker(&request.worker_ref).is_accepted());
+    }
+
+    #[cfg(target_os = "linux")]
+    #[test]
+    fn cleanup_pending_owner_restore_rejects_incomplete_replaced_and_raced_checkouts() {
+        for damage in ["missing_git", "replacement", "missing_after_preflight"] {
+            let (root, backend, request, checkout, observed) = pending_owner_restore_fixture();
+            if damage == "missing_after_preflight" {
+                backend.preflight_restore(&request).unwrap();
+            }
+            if damage == "replacement" {
+                fs::rename(&checkout, root.path().join("original-checkout")).unwrap();
+                fs::create_dir(&checkout).unwrap();
+                fs::create_dir(checkout.join(".git")).unwrap();
+            } else {
+                fs::remove_dir_all(checkout.join(".git")).unwrap();
+            }
+            let before = persisted_files(root.path());
+            let error = backend.preflight_restore(&request).unwrap_err();
+            assert_eq!(
+                error.outcome,
+                crate::execution::WorkerExecutionOutcome::Rejected,
+                "{damage}"
+            );
+            assert!(
+                error
+                    .message_or_default()
+                    .contains("working_directory_cleanup_"),
+                "{error:?}"
+            );
+            assert!(
+                matches!(
+                    backend.restore_worker(request),
+                    WorkerExecutionSpawnResult::Rejected(_)
+                ),
+                "{damage}"
+            );
+            assert_eq!(
+                observed.lock().unwrap().len(),
+                1,
+                "must not start a Controller on invalid checkout: {damage}"
+            );
+            assert_eq!(
+                persisted_files(root.path()),
+                before,
+                "must preserve damaged/replaced checkout: {damage}"
+            );
+        }
+    }
+
     #[test]
     fn worker_spawn_receives_materialized_workspace_cwd_instead_of_source_repo() {
         let client = MockClient::new(simple_text_events());

crates/worker-runtime/src/working_directory.rs

@@ -22,6 +22,11 @@ use std::thread::JoinHandle;
 use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 use workdir::WorkdirSessionResource;
 
+mod cleanup;
+
+#[cfg(all(test, target_os = "linux"))]
+pub(crate) use cleanup::tests::fail_once as fail_workdir_cleanup_once;
+
 const CHECKOUT_DIR: &str = "checkout";
 const MATERIALIZATION_RECORD: &str = "materialization.json";
 const REPOSITORY_ACCESS_DIR: &str = ".repository-access";
@@ -127,7 +132,11 @@ impl WorkingDirectoryBinding {
             working_directory.status = WorkingDirectoryStatusKind::Corrupted;
         }
         let mut summary = working_directory.status_summary();
-        summary.cleanliness = if summary.status == WorkingDirectoryStatusKind::Active {
+        summary.cleanliness = if matches!(
+            summary.status,
+            WorkingDirectoryStatusKind::Active | WorkingDirectoryStatusKind::CleanupPending
+        ) && binding_paths_are_available(self)
+        {
             let (current_selector, current_ref, current_tree) = binding_current_revision(self);
             summary.current_selector = current_selector;
             summary.current_ref = current_ref;
@@ -201,6 +210,24 @@ pub trait WorkingDirectoryMaterializer: Send + Sync + 'static {
         relative_cwd: Option<&str>,
     ) -> Result<WorkingDirectoryBinding, WorkingDirectoryDiagnostic>;
 
+    /// Read-only bind validation: do not consume Repository credentials or open
+    /// session resources during restore preflight. Providers must opt in with
+    /// current usable-checkout validation to support non-active attachments.
+    fn preflight_bind_working_directory(
+        &self,
+        working_directory_id: &str,
+        _relative_cwd: Option<&str>,
+    ) -> Result<(), WorkingDirectoryDiagnostic> {
+        let current = self.working_directory_status(working_directory_id)?;
+        if current.summary.status != WorkingDirectoryStatusKind::Active {
+            return Err(WorkingDirectoryDiagnostic::new(
+                "working_directory_not_active",
+                "Persisted Workdir is not active and its provider cannot validate recovery binding",
+            ));
+        }
+        Ok(())
+    }
+
     fn list_working_directories(
         &self,
     ) -> Result<Vec<WorkingDirectoryStatus>, WorkingDirectoryDiagnostic>;
@@ -627,6 +654,29 @@ impl RuntimeGitMaterializer {
         })
     }
 
+    fn checked_binding(
+        &self,
+        working_directory_id: &str,
+        relative_cwd: Option<&str>,
+    ) -> Result<WorkingDirectoryBinding, WorkingDirectoryDiagnostic> {
+        validate_working_directory_id(working_directory_id)?;
+        let binding = self.read_binding(working_directory_id)?;
+        if !matches!(
+            binding.working_directory.status,
+            WorkingDirectoryStatusKind::Active | WorkingDirectoryStatusKind::CleanupPending
+        ) {
+            return Err(WorkingDirectoryDiagnostic::new(
+                "working_directory_not_active",
+                "working directory working_directory is not active",
+            ));
+        }
+        if binding.working_directory.status == WorkingDirectoryStatusKind::CleanupPending {
+            cleanup::validate_recovery_binding(self, working_directory_id, &binding)?;
+        }
+        let cwd = validate_relative_cwd(binding.root(), relative_cwd)?;
+        Ok(WorkingDirectoryBinding { cwd, ..binding })
+    }
+
     fn read_binding(
         &self,
         working_directory_id: &str,
@@ -1137,17 +1187,17 @@ impl WorkingDirectoryMaterializer for RuntimeGitMaterializer {
         working_directory_id: &str,
         relative_cwd: Option<&str>,
     ) -> Result<WorkingDirectoryBinding, WorkingDirectoryDiagnostic> {
-        validate_working_directory_id(working_directory_id)?;
+        let binding = self.checked_binding(working_directory_id, relative_cwd)?;
-        let binding = self.read_binding(working_directory_id)?;
+        self.bind_repository_access(working_directory_id, binding)
-        if binding.working_directory.status != WorkingDirectoryStatusKind::Active {
-            return Err(WorkingDirectoryDiagnostic::new(
-                "working_directory_not_active",
-                "working directory working_directory is not active",
-            ));
     }
-        let binding = self.bind_repository_access(working_directory_id, binding)?;
+
-        let cwd = validate_relative_cwd(binding.root(), relative_cwd)?;
+    fn preflight_bind_working_directory(
-        Ok(WorkingDirectoryBinding { cwd, ..binding })
+        &self,
+        working_directory_id: &str,
+        relative_cwd: Option<&str>,
+    ) -> Result<(), WorkingDirectoryDiagnostic> {
+        self.checked_binding(working_directory_id, relative_cwd)
+            .map(|_| ())
     }
 
     fn list_working_directories(
@@ -1178,6 +1228,10 @@ impl WorkingDirectoryMaterializer for RuntimeGitMaterializer {
             {
                 continue;
             }
+            if let Some(status) = cleanup::remaining_status(self, &working_directory_id) {
+                statuses.push(status);
+                continue;
+            }
             match self.read_binding(&working_directory_id) {
                 Ok(binding) => statuses.push(binding.status()),
                 Err(_) => statuses.push(self.corrupted_status(&working_directory_id)),
@@ -1197,12 +1251,25 @@ impl WorkingDirectoryMaterializer for RuntimeGitMaterializer {
     ) -> Result<WorkingDirectoryStatus, WorkingDirectoryDiagnostic> {
         validate_working_directory_id(working_directory_id)?;
         let working_directory_root = self.working_directory_root(working_directory_id);
-        if !working_directory_root.exists() {
+        match fs::symlink_metadata(&working_directory_root) {
+            Ok(_) => {}
+            Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
                 return Err(WorkingDirectoryDiagnostic::new(
                     "working_directory_not_found",
-                "working directory working_directory was not found",
+                    "Runtime working directory was not found",
                 ));
             }
+            Err(error) => {
+                return Err(cleanup::os_failure(
+                    working_directory_id,
+                    "lookup_cleanup_root",
+                    error,
+                ));
+            }
+        }
+        if let Some(status) = cleanup::remaining_status(self, working_directory_id) {
+            return Ok(status);
+        }
         match self.read_binding(working_directory_id) {
             Ok(binding) => Ok(binding.status()),
             Err(_) => Ok(self.corrupted_status(working_directory_id)),
@@ -1214,80 +1281,13 @@ impl WorkingDirectoryMaterializer for RuntimeGitMaterializer {
         working_directory_id: &str,
     ) -> Result<WorkingDirectoryStatus, WorkingDirectoryDiagnostic> {
         validate_working_directory_id(working_directory_id)?;
-        let status = self.working_directory_status(working_directory_id)?;
+        cleanup::remove(self, working_directory_id)
-        if status.summary.status == WorkingDirectoryStatusKind::Corrupted {
-            let working_directory_root = self.working_directory_root(working_directory_id);
-            if working_directory_root.exists() {
-                fs::remove_dir_all(&working_directory_root).map_err(|_| {
-                    WorkingDirectoryDiagnostic::new(
-                        "working_directory_corrupted_cleanup_failed",
-                        "failed to remove corrupted working directory; backend-private path details were omitted",
-                    )
-                })?;
-            }
-            let mut summary = status.summary;
-            summary.status = WorkingDirectoryStatusKind::NotFound;
-            return Ok(WorkingDirectoryStatus { summary });
-        }
-        let binding = self.read_binding(working_directory_id)?;
-        self.cleanup(&binding)?;
-        let mut summary = binding.working_directory.status_summary();
-        summary.status = WorkingDirectoryStatusKind::NotFound;
-        summary.cleanliness = Some("unknown".to_string());
-        if binding.working_directory_root.exists() {
-            fs::remove_dir_all(&binding.working_directory_root).map_err(|_| {
-                WorkingDirectoryDiagnostic::new(
-                    "working_directory_record_cleanup_failed",
-                    "failed to remove working directory record; backend-private path details were omitted",
-                )
-            })?;
-        }
-        Ok(WorkingDirectoryStatus { summary })
     }
 
     fn cleanup(&self, binding: &WorkingDirectoryBinding) -> Result<(), WorkingDirectoryDiagnostic> {
-        let mut working_directory = binding.working_directory.clone();
+        // Reload current authority rather than trusting a stale in-memory binding.
-        let working_directory_root = binding.working_directory_root.canonicalize().map_err(|_| {
+        self.cleanup_working_directory(&binding.working_directory.id)
-            WorkingDirectoryDiagnostic::new(
+            .map(|_| ())
-                "working_directory_cleanup_target_invalid",
-                "working directory working directory root is unavailable; backend-private path details were omitted",
-            )
-        })?;
-        let root = binding.root.canonicalize().map_err(|_| {
-            WorkingDirectoryDiagnostic::new(
-                "working_directory_cleanup_target_invalid",
-                "working directory root is unavailable; backend-private path details were omitted",
-            )
-        })?;
-        if !root.starts_with(&working_directory_root) {
-            return Err(WorkingDirectoryDiagnostic::new(
-                "working_directory_cleanup_escape_rejected",
-                "working directory cleanup target is outside the working directory root",
-            ));
-        }
-        let remove_result = fs::remove_dir_all(&working_directory_root).map_err(|_| {
-            WorkingDirectoryDiagnostic::new(
-                "working_directory_cleanup_failed",
-                "failed to remove working directory; backend-private path details were omitted",
-            )
-        });
-        if remove_result.is_err() {
-            working_directory.status = WorkingDirectoryStatusKind::CleanupPending;
-            let updated = WorkingDirectoryBinding {
-                working_directory,
-                root: binding.root.clone(),
-                cwd: binding.cwd.clone(),
-                working_directory_root: binding.working_directory_root.clone(),
-                command_environment: BTreeMap::new(),
-                session_resources: Vec::new(),
-            };
-            let _ = self.write_record(&updated);
-        } else {
-            let _ = self
-                .repository_access
-                .remove_pending(&binding.working_directory.id);
-        }
-        remove_result
     }
 }
 
@@ -2826,6 +2826,7 @@ where
     I: IntoIterator<Item = &'a str>,
 {
     let output = Command::new("git")
+        .env("GIT_OPTIONAL_LOCKS", "0")
         .arg("-C")
         .arg(repository_path)
         .args(args)
@@ -3094,7 +3095,7 @@ mod tests {
         assert!(scheduler_inner.upgrade().is_none());
     }
 
-    fn git(path: &Path, args: &[&str]) {
+    pub(super) fn git(path: &Path, args: &[&str]) {
         let status = Command::new("git")
             .arg("-C")
             .arg(path)
@@ -3104,7 +3105,7 @@ mod tests {
         assert!(status.success(), "git {:?} failed", args);
     }
 
-    fn create_clean_repo() -> tempfile::TempDir {
+    pub(super) fn create_clean_repo() -> tempfile::TempDir {
         let dir = tempfile::tempdir().unwrap();
         git(dir.path(), &["init"]);
         git(
@@ -3118,7 +3119,7 @@ mod tests {
         dir
     }
 
-    fn request(repo: &Path) -> WorkingDirectoryRequest {
+    pub(super) fn request(repo: &Path) -> WorkingDirectoryRequest {
         WorkingDirectoryRequest {
             repository: WorkingDirectoryRepository {
                 id: "repo-main".to_string(),
@@ -3678,6 +3679,8 @@ mod tests {
             .evidence
             .host_trust_revision = Some(1);
         materializer.write_record(&ssh_backed_binding).unwrap();
+        #[cfg(target_os = "linux")]
+        fail_workdir_cleanup_once(&materializer, &id);
         let mut session_materialization = initial_materialization.clone();
         let session_delivery_expiry = repository_access_now_epoch_seconds() + 1;
         session_materialization
@@ -3691,6 +3694,17 @@ mod tests {
                 materialization: session_materialization,
             })
             .unwrap();
+        // Restore preflight must validate without consuming this one-shot SSH
+        // delivery or creating agent/session resources needed by actual bind.
+        let record_before =
+            fs::read(runtime_root.path().join(&id).join(MATERIALIZATION_RECORD)).unwrap();
+        materializer
+            .preflight_bind_working_directory(&id, None)
+            .unwrap();
+        assert_eq!(
+            fs::read(runtime_root.path().join(&id).join(MATERIALIZATION_RECORD)).unwrap(),
+            record_before
+        );
         assert_eq!(materializer.list_working_directories().unwrap().len(), 1);
         assert_eq!(
             fs::read_dir(runtime_root.path().join(".repository-agents"))
@@ -3916,6 +3930,22 @@ mod tests {
             restored.bind_working_directory(&id, None).unwrap_err().code,
             "working_directory_remote_repository_access_required"
         );
+        #[cfg(target_os = "linux")]
+        {
+            // Real SSH reauthorization updated access evidence repeatedly, but
+            // did not replace this clean materialization or require manual recovery.
+            assert_eq!(
+                restored
+                    .working_directory_status(&id)
+                    .unwrap()
+                    .summary
+                    .cleanliness
+                    .as_deref(),
+                Some("clean")
+            );
+            restored.cleanup_working_directory(&id).unwrap();
+            assert!(!restored.working_directory_root(&id).exists());
+        }
     }
 
     #[test]
@@ -4393,7 +4423,7 @@ mod tests {
     }
 
     #[test]
-    fn corrupted_working_directory_record_can_be_removed() {
+    fn corrupted_working_directory_without_removal_authority_is_retained() {
         let runtime_root = tempfile::tempdir().unwrap();
         let materializer = RuntimeGitMaterializer::new(runtime_root.path());
         let working_directory_id = "workdir-corrupted";
@@ -4406,11 +4436,11 @@ mod tests {
             .unwrap();
         assert_eq!(status.summary.status, WorkingDirectoryStatusKind::Corrupted);
 
-        let removed = materializer
+        let error = materializer
             .cleanup_working_directory(working_directory_id)
-            .unwrap();
+            .unwrap_err();
-        assert_eq!(removed.summary.status, WorkingDirectoryStatusKind::NotFound);
+        assert_eq!(error.code, "working_directory_cleanup_ownership_unknown");
-        assert!(!root.exists());
+        assert!(root.exists());
     }
 
     #[test]

docs/development/workdir-removal.md

@@ -44,6 +44,21 @@ removal commits registry deletion only after Runtime confirms physical deletion
 or authoritative not-found. An unknown result leaves the registry in place so
 retry can reconcile the provider's current state.
 
+## Runtime safety boundary
+
+The Runtime keeps removal content/identity evidence outside the tree being
+removed. This is a factual witness for partial deletion, not a new recovery
+state or cleanup stage. Surviving files are rechecked against it; an intact,
+currently clean checkout can renew obsolete evidence without discarding newly
+ignored/untracked content. Do not edit this witness manually.
+
+Mount-safe removal currently requires Linux `openat2` and `/proc` inspection.
+Unavailable inspection fails closed with `mount_check_unavailable`; there is no
+fallback to recursive deletion across an unchecked filesystem boundary.
+Removal retains the Runtime occupancy mutex through its filesystem effect.
+Unrelated Runtime state operations can therefore wait during hashing/unlink;
+releasing it would require equivalent exclusion on all attachment paths.
+
 ## Diagnostics
 
 Public responses expose a bounded cause category and safe guidance, not arbitrary