refactor: broker SubWorker Workdir tools through parent

crates/tools/src/bash.rs

@@ -118,6 +118,7 @@ impl Tool for BashTool {
                 command: params.command,
                 timeout_secs,
                 output_limit: INLINE_BYTE_BUDGET,
+                cwd: None,
                 spill_dir: Some(self.output_dir.clone()),
                 tool_call_id: Some(call_id.clone()),
             })

crates/workdir/src/http.rs

@@ -68,12 +68,10 @@ pub enum WorkdirSessionOperation {
     CommandCancel(CommandHandle),
 }
 
-/// Wire envelope for an operation and its optional provider-enforced child scope.
+/// Wire envelope for one provider operation.
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct WorkdirSessionOperationRequest {
-    #[serde(default, skip_serializing_if = "Vec::is_empty")]
-    pub delegations: Vec<crate::WorkdirDelegationRequest>,
     pub operation: WorkdirSessionOperation,
 }
 
@@ -289,7 +287,7 @@ mod client {
     use reqwest::{Client, StatusCode, Url};
 
     use super::*;
-    use crate::{Workdir, WorkdirSession, WorkdirSessionHandle};
+    use crate::{Workdir, WorkdirSession};
 
     /// Provides a fresh bearer token for each Runtime request. Backend
     /// implementations can mint short-lived capability tokens without making a
@@ -324,7 +322,6 @@ mod client {
         workdir: Workdir,
         session_id: WorkdirSessionId,
         capabilities: WorkdirSessionCapabilities,
-        delegations: Vec<crate::WorkdirDelegationRequest>,
         closed: AtomicBool,
     }
 
@@ -377,7 +374,6 @@ mod client {
                 workdir: Workdir::new(opened.workdir_id.as_str()),
                 session_id: opened.session_id,
                 capabilities: opened.capabilities,
-                delegations: Vec::new(),
                 closed: AtomicBool::new(false),
             })
         }
@@ -404,10 +400,7 @@ mod client {
                     "operations",
                 ],
             )?;
-            let operation = WorkdirSessionOperationRequest {
-                delegations: self.delegations.clone(),
-                operation,
-            };
+            let operation = WorkdirSessionOperationRequest { operation };
             let response = self
                 .client
                 .post(url)
@@ -436,37 +429,6 @@ mod client {
             self.capabilities
         }
 
-        fn transports_delegation_context(&self) -> bool {
-            true
-        }
-
-        async fn capture_delegation_source(
-            &self,
-            request: &crate::WorkdirDelegationRequest,
-        ) -> Result<WorkdirSessionHandle, WorkdirError> {
-            if self.closed.load(Ordering::Acquire) {
-                return Err(WorkdirError::SessionClosed);
-            }
-            let mut delegations = self.delegations.clone();
-            delegations.push(request.clone());
-            let candidate = Arc::new(Self {
-                client: self.client.clone(),
-                base_url: self.base_url.clone(),
-                authorization: self.authorization.clone(),
-                workdir: self.workdir.clone(),
-                session_id: self.session_id.clone(),
-                capabilities: self.capabilities,
-                delegations,
-                closed: AtomicBool::new(false),
-            });
-            candidate
-                .stat(StatRequest {
-                    path: fs_operation::FsPath::new("").expect("empty Workdir path is valid"),
-                })
-                .await?;
-            Ok(candidate)
-        }
-
         async fn stat(&self, request: StatRequest) -> Result<StatResult, WorkdirError> {
             match self.operate(WorkdirSessionOperation::Stat(request)).await? {
                 WorkdirSessionOperationResult::Stat(result) => Ok(result),

crates/workdir/src/lib.rs

@@ -5,10 +5,10 @@
 //! bound to one Worker. Tools consume sessions; they do not own Workdir
 //! materialization or cleanup.
 
-mod delegation;
 pub mod http;
 mod local;
 mod operation;
+mod scope;
 pub mod workspace;
 
 use std::path::{Path, PathBuf};
@@ -18,11 +18,6 @@ use async_trait::async_trait;
 use serde::{Deserialize, Serialize};
 use tokio::sync::broadcast;
 
-pub use delegation::{
-    AppliedWorkdirDelegation, ReadOnlyWorkdirSession, WorkdirDelegation,
-    WorkdirDelegationPermission, WorkdirDelegationRequest, WorkdirDelegationRule,
-    apply_delegation_chain, delegation_capable_session,
-};
 pub use fs_operation::{
     ContentHash, EditRequest, EditResult, EntryKind, FsPath as WorkdirPath, GlobRequest,
     GlobResult, GrepOutputMode, GrepRequest, GrepResult, ListEntry, ListRequest, ListResult,
@@ -32,6 +27,10 @@ pub use local::{
     LocalWorkdirSession, SymlinkInfo, WorkdirSessionResource, direct_symlink, first_symlink,
 };
 pub use operation::*;
+pub use scope::{
+    ReadOnlyWorkdirSession, WorkdirScopeLease, WorkdirToolBroker, WorkdirToolScope,
+    WorkdirToolScopePermission, WorkdirToolScopeRule,
+};
 
 /// Persistent, opaque identity of one materialized Workdir.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
@@ -148,39 +147,6 @@ pub trait WorkdirSession: std::fmt::Debug + Send + Sync {
     fn workdir(&self) -> &Workdir;
     fn capabilities(&self) -> WorkdirSessionCapabilities;
 
-    fn is_delegation_capable(&self) -> bool {
-        false
-    }
-
-    /// Whether this session transports the delegation chain to another
-    /// provider boundary that will apply logical cwd/path resolution there.
-    fn transports_delegation_context(&self) -> bool {
-        false
-    }
-
-    /// Capture a provider-specific source for a delegated child session.
-    /// Remote providers use this boundary to pin attachment identity without
-    /// exposing transport handles or host paths.
-    async fn capture_delegation_source(
-        &self,
-        _request: &WorkdirDelegationRequest,
-    ) -> Result<WorkdirSessionHandle, WorkdirError> {
-        Err(WorkdirError::Denied(
-            "workdir provider does not support delegated sessions".into(),
-        ))
-    }
-
-    /// Attenuate this session into a revocable child lease. Only sessions
-    /// created with [`delegation_capable_session`] implement this operation.
-    async fn delegate(
-        &self,
-        _request: WorkdirDelegationRequest,
-    ) -> Result<WorkdirDelegation, WorkdirError> {
-        Err(WorkdirError::Denied(
-            "workdir session is not delegation-capable".into(),
-        ))
-    }
-
     async fn stat(&self, request: StatRequest) -> Result<StatResult, WorkdirError>;
     async fn read(&self, request: ReadRequest) -> Result<ReadResult, WorkdirError>;
     async fn write(&self, request: WriteRequest) -> Result<WriteResult, WorkdirError>;

crates/workdir/src/local.rs

@@ -18,7 +18,7 @@ use std::sync::{Arc, Mutex as StdMutex};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 use async_trait::async_trait;
-use manifest::{Permission, Scope, ScopeConfig, ScopeRule, SharedScope};
+use manifest::{Scope, SharedScope};
 use sha2::{Digest, Sha256};
 use tokio::process::Command;
 use tokio::sync::{Mutex, broadcast, watch};
@@ -28,10 +28,8 @@ use crate::{
     CommandEvent, CommandHandle, CommandOutput, CommandOutputRequest, CommandRequest,
     CommandSnapshot, CommandStatus, CommandStream, CommandStreamSlice, EditRequest, EditResult,
     GlobRequest, GlobResult, GrepRequest, GrepResult, ListRequest, ListResult, ReadRequest,
-    ReadResult, StatRequest, StatResult, Workdir, WorkdirDelegationPermission,
-    WorkdirDelegationRequest, WorkdirError, WorkdirPath, WorkdirSession,
-    WorkdirSessionCapabilities, WorkdirSessionCapability, WorkdirSessionHandle, WriteRequest,
-    WriteResult,
+    ReadResult, StatRequest, StatResult, Workdir, WorkdirError, WorkdirPath, WorkdirSession,
+    WorkdirSessionCapabilities, WorkdirSessionCapability, WriteRequest, WriteResult,
 };
 #[cfg(test)]
 use crate::{EntryKind, WriteOutcome};
@@ -558,69 +556,6 @@ impl WorkdirSession for LocalWorkdirSession {
         self.inner.capabilities
     }
 
-    async fn capture_delegation_source(
-        &self,
-        request: &WorkdirDelegationRequest,
-    ) -> Result<WorkdirSessionHandle, WorkdirError> {
-        let host_rules = request
-            .rules
-            .iter()
-            .map(|rule| ScopeRule {
-                target: self.inner.root.join(rule.target.as_str()),
-                permission: match rule.permission {
-                    WorkdirDelegationPermission::Read => Permission::Read,
-                    WorkdirDelegationPermission::Write => Permission::Write,
-                },
-                recursive: rule.recursive,
-            })
-            .collect::<Vec<_>>();
-        for (logical, host) in request.rules.iter().zip(&host_rules) {
-            if logical.permission == WorkdirDelegationPermission::Write {
-                let resolved = Scope::resolved_target(host)
-                    .map_err(|error| WorkdirError::Denied(error.to_string()))?;
-                if resolved != host.target {
-                    return Err(WorkdirError::Denied(format!(
-                        "write delegation target `{}` traverses a symlink",
-                        logical.target
-                    )));
-                }
-            }
-        }
-        let parent_scope = self.inner.scope.snapshot();
-        for rule in &host_rules {
-            if !parent_scope
-                .allows_rule(rule)
-                .map_err(|error| WorkdirError::Denied(error.to_string()))?
-            {
-                return Err(WorkdirError::Denied(format!(
-                    "delegated provider scope `{}` exceeds the parent session",
-                    rule.target.display()
-                )));
-            }
-        }
-        let child_scope = Scope::from_config(&ScopeConfig {
-            allow: host_rules,
-            deny: Vec::new(),
-        })
-        .map_err(|error| WorkdirError::Denied(error.to_string()))?;
-        let child_cwd = self.inner.root.join(request.cwd.as_str());
-        if !child_scope.is_readable(&child_cwd)
-            || !std::fs::metadata(&child_cwd).is_ok_and(|metadata| metadata.is_dir())
-        {
-            return Err(WorkdirError::Denied(format!(
-                "delegated cwd `{}` is not a readable Workdir directory",
-                request.cwd
-            )));
-        }
-        Ok(Arc::new(LocalWorkdirSession::materialized_bound(
-            self.inner.workdir.clone(),
-            self.inner.root.clone(),
-            self.inner.root.clone(),
-            SharedScope::new(child_scope),
-            self.inner.capabilities,
-        )))
-    }
-
     async fn stat(&self, request: StatRequest) -> Result<StatResult, WorkdirError> {
         self.ensure_capability(WorkdirSessionCapability::Read)?;
         let logical = request.path.clone();
@@ -694,9 +629,20 @@ impl WorkdirSession for LocalWorkdirSession {
         {
             return Err(WorkdirError::OutOfScope(spill_dir.to_path_buf()));
         }
+        let cwd = if let Some(logical_cwd) = request.cwd.as_ref() {
+            let cwd = self.resolve(logical_cwd);
+            let scope = self.inner.scope.snapshot();
+            if !scope.is_readable(&cwd)
+                || !std::fs::metadata(&cwd).is_ok_and(|metadata| metadata.is_dir())
+            {
+                return Err(WorkdirError::OutOfScope(cwd));
+            }
+            cwd
+        } else {
+            self.inner.cwd.clone()
+        };
         let id = self.inner.next_command_id.fetch_add(1, Ordering::Relaxed);
         let handle = CommandHandle(format!("command-{id}"));
-        let cwd = self.inner.cwd.clone();
         let (completion_tx, completion) = watch::channel(false);
         let command_id = handle.0.clone();
         let telemetry = self.inner.command_telemetry.clone();
@@ -1516,6 +1462,7 @@ mod tests {
                 command: "sleep 30".to_owned(),
                 timeout_secs: 60,
                 output_limit: 1024,
+                cwd: None,
                 spill_dir: None,
                 tool_call_id: None,
             },
@@ -2043,6 +1990,7 @@ mod tests {
                 command: "pwd && printf provider-command".into(),
                 timeout_secs: 5,
                 output_limit: 4096,
+                cwd: None,
                 spill_dir: None,
                 tool_call_id: None,
             },
@@ -2141,6 +2089,7 @@ mod tests {
                 command: "printf hidden".into(),
                 timeout_secs: 5,
                 output_limit: 1,
+                cwd: None,
                 spill_dir: Some(spill.path().to_path_buf()),
                 tool_call_id: None,
             },
@@ -2178,6 +2127,7 @@ mod tests {
                 command: "i=0; while [ $i -lt 200 ]; do printf 'line-%03d\\n' \"$i\"; i=$((i+1)); done; printf 'FINAL-NEEDLE\\n'".into(),
                 timeout_secs: 5,
                 output_limit: 64,
+                cwd: None,
                 spill_dir: Some(spill.path().to_path_buf()),
                 tool_call_id: None,
             },
@@ -2224,6 +2174,7 @@ mod tests {
                 command: "printf 'aéz'".into(),
                 timeout_secs: 5,
                 output_limit: 1024,
+                cwd: None,
                 spill_dir: None,
                 tool_call_id: None,
             },
@@ -2449,6 +2400,7 @@ mod tests {
                 command: "printf ready; printf warning >&2; sleep 0.2; printf done".into(),
                 timeout_secs: 5,
                 output_limit: 1024,
+                cwd: None,
                 spill_dir: None,
                 tool_call_id: Some("tool-7".into()),
             },
@@ -2553,6 +2505,7 @@ mod tests {
                 command: "sleep 30".into(),
                 timeout_secs: 1,
                 output_limit: 1024,
+                cwd: None,
                 spill_dir: None,
                 tool_call_id: None,
             },
@@ -2623,6 +2576,7 @@ mod tests {
                 command: "sleep 30".into(),
                 timeout_secs: 60,
                 output_limit: 1024,
+                cwd: None,
                 spill_dir: None,
                 tool_call_id: None,
             },

crates/workdir/src/operation.rs

@@ -11,6 +11,10 @@ pub struct CommandRequest {
     pub command: String,
     pub timeout_secs: u64,
     pub output_limit: usize,
+    /// Workdir-relative command directory. Providers validate it against the
+    /// active session before process start.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub cwd: Option<fs_operation::FsPath>,
     /// Provider-local directory where complete output is retained when the
     /// inline result exceeds `output_limit`.
     pub spill_dir: Option<PathBuf>,

crates/workdir/src/workspace.rs

@@ -104,15 +104,5 @@ mod tests {
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct WorkspaceWorkdirSessionOperationRequest {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub expected_session_fence: Option<String>,
-    #[serde(default, skip_serializing_if = "Vec::is_empty")]
-    pub delegations: Vec<crate::WorkdirDelegationRequest>,
     pub operation: crate::http::WorkdirSessionOperation,
 }
-
-#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(deny_unknown_fields)]
-pub struct WorkspaceWorkdirSessionFence {
-    pub value: String,
-}

crates/worker-runtime/src/http_server.rs

@@ -718,8 +718,7 @@ async fn run_workdir_session_operation(
             .ok_or_else(RuntimeHttpWorkdirError::not_found)?;
         record.session.clone()
     };
-    let applied = workdir::apply_delegation_chain(source, request.delegations).await?;
-    let session = applied.scoped_session.as_ref();
+    let session = source.as_ref();
     let operation = request.operation;
 
     let result = match operation {
@@ -2080,8 +2079,8 @@ mod tests {
     use manifest::{Scope, SharedScope};
     use tower::ServiceExt;
     use workdir::{
-        GrepOutputMode, GrepRequest, LocalWorkdirSession, ReadRequest, StatRequest, Workdir,
-        WorkdirPath, WorkdirSessionCapabilities,
+        GrepOutputMode, GrepRequest, LocalWorkdirSession, StatRequest, Workdir, WorkdirPath,
+        WorkdirSessionCapabilities,
     };
 
     #[test]
@@ -2502,16 +2501,6 @@ mod tests {
     async fn workdir_session_operations_enforce_owner_and_close_terminally() {
         let temp = tempfile::tempdir().expect("tempdir");
         std::fs::write(temp.path().join("hello.txt"), "hello").expect("write fixture");
-        #[cfg(unix)]
-        {
-            use std::os::unix::fs::symlink;
-            std::fs::create_dir(temp.path().join("granted")).expect("granted directory");
-            std::fs::write(temp.path().join("granted/visible"), "visible")
-                .expect("visible fixture");
-            std::fs::create_dir(temp.path().join("secret")).expect("secret directory");
-            std::fs::write(temp.path().join("secret/key"), "hidden").expect("secret fixture");
-            symlink("../secret/key", temp.path().join("granted/link")).expect("symlink fixture");
-        }
         let scope = SharedScope::new(Scope::writable(temp.path()).expect("scope"));
         let session: WorkdirSessionHandle = Arc::new(LocalWorkdirSession::materialized_bound(
             Workdir::new("wd-1"),
@@ -2545,7 +2534,6 @@ mod tests {
             expires_at: u64::MAX,
         };
         let operation = WorkdirSessionOperationRequest {
-            delegations: Vec::new(),
             operation: WorkdirSessionOperation::Stat(StatRequest {
                 path: WorkdirPath::new("hello.txt").expect("logical path"),
             }),
@@ -2562,7 +2550,6 @@ mod tests {
         assert!(matches!(result, WorkdirSessionOperationResult::Stat(_)));
 
         let grep = WorkdirSessionOperationRequest {
-            delegations: Vec::new(),
             operation: WorkdirSessionOperation::Grep(GrepRequest {
                 pattern: "hello".into(),
                 path: WorkdirPath::new("hello.txt").unwrap(),
@@ -2585,78 +2572,7 @@ mod tests {
         )
         .await
         .expect("grep direct file through provider operation");
-        match result {
-            WorkdirSessionOperationResult::Grep(result) => {
-                assert_eq!(result.match_count, 1);
-                assert_eq!(result.matched_files, 1);
-                assert!(result.output.starts_with("hello.txt\n"));
-                assert!(result.output.contains("> 1 │ hello"));
-            }
-            other => panic!("unexpected workdir grep result: {other:?}"),
-        }
-
-        #[cfg(unix)]
-        {
-            let delegated_visible = WorkdirSessionOperationRequest {
-                delegations: vec![workdir::WorkdirDelegationRequest {
-                    rules: vec![workdir::WorkdirDelegationRule {
-                        target: WorkdirPath::new("granted").unwrap(),
-                        permission: workdir::WorkdirDelegationPermission::Read,
-                        recursive: true,
-                    }],
-                    cwd: WorkdirPath::new("granted").unwrap(),
-                }],
-                operation: WorkdirSessionOperation::Read(ReadRequest {
-                    path: WorkdirPath::new("visible").unwrap(),
-                    offset: 0,
-                    limit: 20,
-                    max_bytes: 1024,
-                }),
-            };
-            let visible = run_workdir_session_operation(
-                State(state.clone()),
-                Path("session-1".to_string()),
-                Some(Extension(auth.clone())),
-                Ok(Json(delegated_visible)),
-            )
-            .await
-            .expect("non-root delegated cwd should resolve once")
-            .0;
-            assert!(matches!(
-                visible,
-                WorkdirSessionOperationResult::Read(result) if result.bytes == b"visible"
-            ));
-
-            let delegated_read = WorkdirSessionOperationRequest {
-                delegations: vec![workdir::WorkdirDelegationRequest {
-                    rules: vec![workdir::WorkdirDelegationRule {
-                        target: WorkdirPath::new("granted").unwrap(),
-                        permission: workdir::WorkdirDelegationPermission::Read,
-                        recursive: true,
-                    }],
-                    cwd: WorkdirPath::new("granted").unwrap(),
-                }],
-                operation: WorkdirSessionOperation::Read(ReadRequest {
-                    path: WorkdirPath::new("link").unwrap(),
-                    offset: 0,
-                    limit: 20,
-                    max_bytes: 1024,
-                }),
-            };
-            let error = run_workdir_session_operation(
-                State(state.clone()),
-                Path("session-1".to_string()),
-                Some(Extension(auth.clone())),
-                Ok(Json(delegated_read)),
-            )
-            .await
-            .expect_err("provider must reject delegated symlink escape");
-            assert_ne!(error.status, StatusCode::OK);
-            assert_eq!(
-                std::fs::read_to_string(temp.path().join("secret/key")).unwrap(),
-                "hidden"
-            );
-        }
+        assert!(matches!(result, WorkdirSessionOperationResult::Grep(_)));
 
         let wrong_owner = RuntimeAuthContext {
             workspace_id: "workspace-b".to_string(),

crates/worker/src/controller.rs

@@ -514,6 +514,7 @@ impl WorkerController {
             runtime_base.to_path_buf(),
             spawned_registry.clone(),
             Some(method_tx.downgrade()),
+            None,
         )
         .await?;
         if let Some(session) = fs_for_view.as_ref() {
@@ -911,6 +912,7 @@ pub(crate) async fn register_worker_tools<C, St>(
     runtime_base: PathBuf,
     spawned_registry: Arc<SpawnedWorkerRegistry>,
     parent_method_tx: Option<mpsc::WeakSender<Method>>,
+    inherited_workdir_tool_broker: Option<workdir::WorkdirToolBroker>,
 ) -> std::io::Result<Option<workdir::WorkdirSessionHandle>>
 where
     C: LlmClient + Clone + 'static,
@@ -919,21 +921,26 @@ where
     // Worker-immutable snapshots taken before the mutable worker borrow
     // below so the worker borrow doesn't conflict with reads on `worker`.
     let feature_config = worker.manifest().feature.clone();
+    let mut workdir_tool_broker = inherited_workdir_tool_broker;
     if feature_config.manage_workdir.enabled && worker.workdir_session().is_none() {
         let workspace_client = worker.workspace_client_handle();
-        worker.bind_workdir_session(Some(workdir::delegation_capable_session(
+        let broker = workdir::WorkdirToolBroker::new(
             crate::feature::builtin::manage_workdir::WorkspaceAttachedWorkdirSession::handle(
                 workspace_client,
             ),
-        )));
-    }
-    if feature_config.sub_worker.enabled
+        );
+        worker.bind_workdir_session(Some(broker.tool_session()));
+        workdir_tool_broker = Some(broker);
+    } else if workdir_tool_broker.is_none()
         && let Some(existing) = worker.workdir_session().cloned()
-        && !existing.is_delegation_capable()
     {
-        worker.bind_workdir_session(Some(workdir::delegation_capable_session(existing)));
+        let broker = workdir::WorkdirToolBroker::new(existing);
+        worker.bind_workdir_session(Some(broker.tool_session()));
+        workdir_tool_broker = Some(broker);
     }
-    let worker_workdir = worker.workdir_session().cloned();
+    let worker_workdir = workdir_tool_broker
+        .as_ref()
+        .map(workdir::WorkdirToolBroker::tool_session);
     let local_filesystem = worker.local_working_directory().cloned();
     let local_workspace_root = local_filesystem.as_ref().map(|local| local.root.clone());
     let task_feature = worker.task_feature();
@@ -1157,7 +1164,6 @@ where
     }
 
     let host_worker_observation_provider = worker.worker_observation_provider();
-    let source_workdir_session = worker.workdir_session().cloned();
     {
         let workspace_client = worker.workspace_client_handle();
         let engine = worker.engine_mut();
@@ -1199,7 +1205,7 @@ where
                 runtime_base.clone(),
                 bash_output_dir.clone(),
                 spawner_workspace_root,
-                source_workdir_session,
+                workdir_tool_broker,
                 spawned_registry.clone(),
                 spawner_manifest,
                 prompts,

crates/worker/src/feature/builtin/manage_workdir.rs

@@ -12,7 +12,7 @@ use async_trait::async_trait;
 use serde::{Deserialize, Serialize};
 use serde_json::json;
 use workdir::http::{WorkdirSessionOperation, WorkdirSessionOperationResult};
-use workdir::workspace::{WorkspaceWorkdirSessionFence, WorkspaceWorkdirSessionOperationRequest};
+use workdir::workspace::WorkspaceWorkdirSessionOperationRequest;
 use workdir::{
     CommandHandle, CommandOutput, CommandOutputRequest, CommandRequest, CommandStatus, EditRequest,
     EditResult, GlobRequest, GlobResult, GrepRequest, GrepResult, ListRequest, ListResult,
@@ -156,8 +156,6 @@ struct WorkspaceHttpWorkdirBackend {
 pub struct WorkspaceAttachedWorkdirSession {
     client: Arc<dyn WorkspaceClient>,
     workdir: Workdir,
-    expected_session_fence: Option<String>,
-    delegations: Vec<workdir::WorkdirDelegationRequest>,
 }
 
 impl WorkspaceAttachedWorkdirSession {
@@ -165,8 +163,6 @@ impl WorkspaceAttachedWorkdirSession {
         Arc::new(Self {
             client,
             workdir: Workdir::new("workspace-attachment"),
-            expected_session_fence: None,
-            delegations: Vec::new(),
         })
     }
 
@@ -183,16 +179,13 @@ impl WorkspaceAttachedWorkdirSession {
                 "/api/w/{}/workers/self/workdir-session/operations",
                 encode_path_segment(workspace_id)
             ),
-            serde_json::to_string(&WorkspaceWorkdirSessionOperationRequest {
-                expected_session_fence: self.expected_session_fence.clone(),
-                delegations: self.delegations.clone(),
-                operation,
-            })
-            .map_err(|error| {
+            serde_json::to_string(&WorkspaceWorkdirSessionOperationRequest { operation }).map_err(
+                |error| {
                     WorkdirError::Transport(format!(
                         "failed to encode Workspace Workdir operation: {error}"
                     ))
-            })?,
+                },
+            )?,
         );
         let response = self
             .client
@@ -241,59 +234,6 @@ impl WorkdirSession for WorkspaceAttachedWorkdirSession {
         WorkdirSessionCapabilities::ALL
     }
 
-    fn transports_delegation_context(&self) -> bool {
-        true
-    }
-
-    async fn capture_delegation_source(
-        &self,
-        request: &workdir::WorkdirDelegationRequest,
-    ) -> Result<WorkdirSessionHandle, WorkdirError> {
-        let expected_session_fence = if let Some(fence) = &self.expected_session_fence {
-            fence.clone()
-        } else {
-            let workspace_id = self.client.workspace_id().ok_or_else(|| {
-                WorkdirError::Unavailable("Workspace identity is unavailable".to_string())
-            })?;
-            let response = self
-                .client
-                .execute(WorkspaceRequest {
-                    method: WorkspaceRequestMethod::Get,
-                    path: format!(
-                        "/api/w/{}/workers/self/workdir-session/fence",
-                        encode_path_segment(workspace_id)
-                    ),
-                    body: None,
-                })
-                .map_err(|error| {
-                    WorkdirError::Unavailable(format!(
-                        "failed to capture Workdir attachment fence: {error}"
-                    ))
-                })?;
-            let fence: WorkspaceWorkdirSessionFence = serde_json::from_str(&response.body)
-                .map_err(|error| {
-                    WorkdirError::Unavailable(format!(
-                        "invalid Workdir attachment fence response: {error}"
-                    ))
-                })?;
-            fence.value
-        };
-        let mut delegations = self.delegations.clone();
-        delegations.push(request.clone());
-        let candidate = Arc::new(Self {
-            client: self.client.clone(),
-            workdir: self.workdir.clone(),
-            expected_session_fence: Some(expected_session_fence),
-            delegations,
-        });
-        candidate
-            .stat(StatRequest {
-                path: workdir::WorkdirPath::new("").expect("empty Workdir path is valid"),
-            })
-            .await?;
-        Ok(candidate)
-    }
-
     async fn stat(&self, request: StatRequest) -> Result<StatResult, WorkdirError> {
         match self.operate(WorkdirSessionOperation::Stat(request))? {
             WorkdirSessionOperationResult::Stat(result) => Ok(result),
@@ -1155,6 +1095,7 @@ mod tests {
                 command: "true".to_string(),
                 timeout_secs: 120,
                 output_limit: 1024,
+                cwd: None,
                 spill_dir: Some("/worker-local/bash-output".into()),
                 tool_call_id: Some("call-1".to_string()),
             })
@@ -1178,83 +1119,6 @@ mod tests {
         );
     }
 
-    #[tokio::test]
-    async fn delegated_attached_session_carries_captured_fence_on_operations() {
-        let client = Arc::new(RecordingWorkspaceClient::new(vec![
-            response(json!({"value": "attachment-fence"})),
-            response(json!({
-                "operation": "stat",
-                "result": {"path": "", "kind": "directory", "size": 0}
-            })),
-            response(json!({
-                "operation": "stat",
-                "result": {"path": "visible.txt", "kind": "file", "size": 8}
-            })),
-        ]));
-        let parent = workdir::delegation_capable_session(WorkspaceAttachedWorkdirSession::handle(
-            client.clone(),
-        ));
-        let delegation = parent
-            .delegate(workdir::WorkdirDelegationRequest {
-                rules: vec![workdir::WorkdirDelegationRule {
-                    target: workdir::WorkdirPath::new("").unwrap(),
-                    permission: workdir::WorkdirDelegationPermission::Read,
-                    recursive: false,
-                }],
-                cwd: workdir::WorkdirPath::new("").unwrap(),
-            })
-            .await
-            .unwrap();
-        delegation
-            .scoped_session
-            .stat(StatRequest {
-                path: workdir::WorkdirPath::new("visible.txt").unwrap(),
-            })
-            .await
-            .unwrap();
-
-        let requests = client.requests();
-        assert_eq!(requests.len(), 3);
-        assert_eq!(
-            requests[0].path,
-            "/api/w/workspace%2Ftest/workers/self/workdir-session/fence"
-        );
-        let body: serde_json::Value =
-            serde_json::from_str(requests[2].body.as_deref().unwrap()).unwrap();
-        assert_eq!(body["expected_session_fence"], "attachment-fence");
-        assert_eq!(body["operation"]["operation"], "stat");
-        assert_eq!(body["delegations"][0]["rules"][0]["target"], "");
-    }
-
-    #[tokio::test]
-    async fn attached_provider_rejection_happens_before_delegation_is_returned() {
-        let client = Arc::new(RecordingWorkspaceClient::new(vec![
-            response(json!({"value": "attachment-fence"})),
-            response(json!({"error": "provider rejected delegated write target"})),
-        ]));
-        let parent = workdir::delegation_capable_session(WorkspaceAttachedWorkdirSession::handle(
-            client.clone(),
-        ));
-        let result = parent
-            .delegate(workdir::WorkdirDelegationRequest {
-                rules: vec![workdir::WorkdirDelegationRule {
-                    target: workdir::WorkdirPath::new("linked-target").unwrap(),
-                    permission: workdir::WorkdirDelegationPermission::Write,
-                    recursive: true,
-                }],
-                cwd: workdir::WorkdirPath::new("linked-target").unwrap(),
-            })
-            .await;
-
-        assert!(result.is_err(), "provider rejection must fail before lease");
-        let requests = client.requests();
-        assert_eq!(requests.len(), 2);
-        let validation: serde_json::Value =
-            serde_json::from_str(requests[1].body.as_deref().unwrap()).unwrap();
-        assert_eq!(validation["operation"]["operation"], "stat");
-        assert_eq!(validation["delegations"].as_array().unwrap().len(), 1);
-    }
-
     #[tokio::test]
     async fn attached_session_preserves_typed_provider_validation_error() {
         let client = Arc::new(RecordingWorkspaceClient::new(vec![error_response(
@@ -1298,73 +1162,52 @@ mod tests {
     }
 
     #[tokio::test]
-    async fn nested_attached_session_preserves_full_delegation_chain() {
+    async fn scoped_broker_operations_carry_no_child_context() {
         let client = Arc::new(RecordingWorkspaceClient::new(vec![
-            response(json!({"value": "attachment-fence"})),
             response(json!({
                 "operation": "stat",
-                "result": {"path": "", "kind": "directory", "size": 0}
+                "result": {"path": "visible.txt", "kind": "file", "size": 8}
             })),
             response(json!({
                 "operation": "stat",
-                "result": {"path": "nested", "kind": "directory", "size": 0}
-            })),
-            response(json!({
-                "operation": "stat",
-                "result": {"path": "nested/file", "kind": "file", "size": 1}
+                "result": {"path": "visible.txt", "kind": "file", "size": 8}
             })),
         ]));
-        let parent = workdir::delegation_capable_session(WorkspaceAttachedWorkdirSession::handle(
+        let broker = workdir::WorkdirToolBroker::new(WorkspaceAttachedWorkdirSession::handle(
             client.clone(),
         ));
-        let outer = parent
-            .delegate(workdir::WorkdirDelegationRequest {
-                rules: vec![workdir::WorkdirDelegationRule {
+        let scoped = broker
+            .scope(workdir::WorkdirToolScope {
+                rules: vec![workdir::WorkdirToolScopeRule {
                     target: workdir::WorkdirPath::new("").unwrap(),
-                    permission: workdir::WorkdirDelegationPermission::Read,
+                    permission: workdir::WorkdirToolScopePermission::Read,
                     recursive: true,
                 }],
                 cwd: workdir::WorkdirPath::new("").unwrap(),
+                command: false,
             })
             .await
             .unwrap();
-        let nested = outer
-            .scoped_session
-            .delegate(workdir::WorkdirDelegationRequest {
-                rules: vec![workdir::WorkdirDelegationRule {
-                    target: workdir::WorkdirPath::new("nested").unwrap(),
-                    permission: workdir::WorkdirDelegationPermission::Read,
-                    recursive: true,
-                }],
-                cwd: workdir::WorkdirPath::new("nested").unwrap(),
-            })
-            .await
-            .unwrap();
-        nested
-            .scoped_session
+        scoped
             .stat(StatRequest {
-                path: workdir::WorkdirPath::new("file").unwrap(),
+                path: workdir::WorkdirPath::new("visible.txt").unwrap(),
             })
             .await
             .unwrap();
 
         let requests = client.requests();
-        assert_eq!(requests.len(), 4);
-        let outer_validation: serde_json::Value =
-            serde_json::from_str(requests[1].body.as_deref().unwrap()).unwrap();
-        let nested_validation: serde_json::Value =
-            serde_json::from_str(requests[2].body.as_deref().unwrap()).unwrap();
-        assert_eq!(outer_validation["delegations"].as_array().unwrap().len(), 1);
+        assert_eq!(requests.len(), 2);
+        for request in requests {
             assert_eq!(
-            nested_validation["delegations"].as_array().unwrap().len(),
-            2
+                request.path,
+                "/api/w/workspace%2Ftest/workers/self/workdir-session/operations"
             );
             let body: serde_json::Value =
-            serde_json::from_str(requests[3].body.as_deref().unwrap()).unwrap();
-        assert_eq!(body["delegations"].as_array().unwrap().len(), 2);
-        assert_eq!(body["delegations"][0]["rules"][0]["target"], "");
-        assert_eq!(body["delegations"][1]["rules"][0]["target"], "nested");
-        assert_eq!(body["operation"]["request"]["path"], "file");
+                serde_json::from_str(request.body.as_deref().unwrap()).unwrap();
+            assert!(body.get("delegations").is_none());
+            assert!(body.get("child").is_none());
+            assert!(body.get("expected_session_fence").is_none());
+        }
     }
 
     #[test]

crates/worker/src/internal_worker.rs

@@ -709,7 +709,7 @@ pub(crate) fn prepare_internal_worker_from_spec(
         }
 
         Box::pin(prepare_internal_worker_session(
-            worker, store, visibility, None, None,
+            worker, store, visibility, None, None, None,
         ))
         .await
     })
@@ -746,13 +746,16 @@ pub(crate) async fn prepare_internal_worker_session(
     visibility: InternalWorkerVisibility,
     child_registry: Option<Arc<SpawnedWorkerRegistry>>,
     on_turn_end: Option<Arc<dyn Fn(InternalWorkerSessionStatus) + Send + Sync>>,
+    command_event_broker: Option<workdir::WorkdirToolBroker>,
 ) -> Result<InternalWorkerSessionHandle, InternalWorkerSessionError> {
     let (event_tx, _event_rx) = broadcast::channel(256);
     let sink = worker.sink();
     spawn_internal_log_event_bridge(sink.clone(), event_tx.clone());
     let alerter = Alerter::new(event_tx.clone());
     let in_flight = InFlightEvents::new(event_tx.clone());
-    if let Some(session) = worker.workdir_session() {
+    if let Some(broker) = command_event_broker.as_ref() {
+        wire_workdir_command_events(&broker.tool_session(), &in_flight);
+    } else if let Some(session) = worker.workdir_session() {
         wire_workdir_command_events(session, &in_flight);
     }
     let actor_in_flight = in_flight.clone();
@@ -887,6 +890,7 @@ pub(crate) async fn spawn_prepared_internal_worker_session(
         InternalWorkerVisibility::ServicePrivate,
         None,
         on_turn_end,
+        None,
     )
     .await?;
     handle.send(input).await?;

crates/worker/src/spawn/registry.rs

@@ -25,7 +25,7 @@ use session_store::{
 };
 use tokio::sync::broadcast;
 use tracing::warn;
-use workdir::WorkdirDelegation;
+use workdir::WorkdirScopeLease;
 
 use crate::internal_worker::{InternalWorkerSessionHandle, InternalWorkerVisibility};
 use crate::runtime::dir::{RuntimeDir, SpawnedWorkerRecord};
@@ -68,7 +68,7 @@ pub(crate) struct SubWorkerStopSummary {
 pub(crate) struct InternalSpawnedWorkerRecord {
     pub worker_name: String,
     pub scope_delegated: Vec<ScopeRule>,
-    pub workdir_delegation: Arc<WorkdirDelegation>,
+    pub workdir_tool_scope: Arc<WorkdirScopeLease>,
     #[cfg(test)]
     pub installed_tools: Arc<[String]>,
     pub session: InternalWorkerSessionHandle,
@@ -86,7 +86,7 @@ impl InternalSpawnedWorkerRecord {
     pub(crate) fn new(
         worker_name: String,
         scope_delegated: Vec<ScopeRule>,
-        workdir_delegation: WorkdirDelegation,
+        workdir_tool_scope: WorkdirScopeLease,
         #[cfg(test)] installed_tools: Vec<String>,
         session: InternalWorkerSessionHandle,
         change_tracker: Option<tools::Tracker>,
@@ -94,7 +94,7 @@ impl InternalSpawnedWorkerRecord {
         Self {
             worker_name,
             scope_delegated,
-            workdir_delegation: Arc::new(workdir_delegation),
+            workdir_tool_scope: Arc::new(workdir_tool_scope),
             #[cfg(test)]
             installed_tools: installed_tools.into(),
             session,
@@ -690,7 +690,7 @@ impl SpawnedWorkerRegistry {
         if !record.claim_scope_reclaim() {
             return Ok(false);
         }
-        record.workdir_delegation.release();
+        record.workdir_tool_scope.release();
         let result = if let Some(parent_scope) = &self.parent_scope {
             parent_scope
                 .update(|current| current.with_removed_deny_rules(delegated_write_rules(record)))
@@ -966,7 +966,7 @@ mod tests {
             deny: Vec::new(),
         })
         .unwrap();
-        let source = workdir::delegation_capable_session(Arc::new(
+        let source = workdir::WorkdirToolBroker::new(Arc::new(
             workdir::LocalWorkdirSession::materialized_bound(
                 workdir::Workdir::new("registry-test"),
                 root.clone(),
@@ -976,13 +976,14 @@ mod tests {
             ),
         ));
         let delegation = source
-            .delegate(workdir::WorkdirDelegationRequest {
-                rules: vec![workdir::WorkdirDelegationRule {
+            .scope(workdir::WorkdirToolScope {
+                rules: vec![workdir::WorkdirToolScopeRule {
                     target: workdir::WorkdirPath::new("").unwrap(),
-                    permission: workdir::WorkdirDelegationPermission::Read,
+                    permission: workdir::WorkdirToolScopePermission::Read,
                     recursive: true,
                 }],
                 cwd: workdir::WorkdirPath::new("").unwrap(),
+                command: false,
             })
             .await
             .unwrap();

crates/worker/src/spawn/tool.rs

@@ -22,8 +22,7 @@ use manifest::{
 use serde::Deserialize;
 use tokio::sync::mpsc;
 use workdir::{
-    WorkdirDelegationPermission, WorkdirDelegationRequest, WorkdirDelegationRule, WorkdirPath,
-    WorkdirSessionHandle,
+    WorkdirToolBroker, WorkdirToolScope, WorkdirToolScopePermission, WorkdirToolScopeRule,
 };
 
 use crate::PromptCatalogSource;
@@ -64,6 +63,9 @@ struct SubWorkerSpawnInput {
     /// spawner's explicit delegation authority; direct tool scope alone is not
     /// sufficient. Omit `recursive` for normal workspace/worktree delegation; it defaults to true.
     scope: Vec<ScopeRuleInput>,
+    /// Explicitly grant command execution through the parent-owned Workdir tool broker.
+    #[serde(default)]
+    command: bool,
     /// Binds an actual read-only builtin Reviewer child to the current Merge Request candidate.
     /// Review capability material is generated by the trusted spawn layer.
     #[serde(default)]
@@ -267,8 +269,8 @@ pub struct SubWorkerSpawnTool {
     workspace_root: PathBuf,
     /// Directory the spawned SubWorker's tools should use when the LLM did not
     /// override it. Defaults to the spawner's cwd.
-    /// Active provider-backed Workdir session from which child leases are captured.
-    source_workdir_session: Option<WorkdirSessionHandle>,
+    /// Parent-owned broker for scoped Workdir tool execution.
+    workdir_tool_broker: Option<WorkdirToolBroker>,
     /// Parent-owned in-memory registry shared by the five SubWorker tools.
     registry: Arc<SpawnedWorkerRegistry>,
     /// Spawner's resolved Manifest. `profile = "inherit"` derives the
@@ -295,7 +297,7 @@ impl SubWorkerSpawnTool {
         runtime_base: PathBuf,
         bash_output_dir: PathBuf,
         workspace_root: PathBuf,
-        source_workdir_session: Option<WorkdirSessionHandle>,
+        workdir_tool_broker: Option<WorkdirToolBroker>,
         registry: Arc<SpawnedWorkerRegistry>,
         spawner_manifest: WorkerManifest,
         prompt_loader: PromptCatalogSource,
@@ -308,7 +310,7 @@ impl SubWorkerSpawnTool {
             runtime_base,
             bash_output_dir,
             workspace_root,
-            source_workdir_session,
+            workdir_tool_broker,
             registry,
             spawner_manifest,
             prompt_loader,
@@ -341,6 +343,11 @@ fn validate_reviewer_handoff(input: &SubWorkerSpawnInput) -> Result<(), ToolErro
             "Merge Request Reviewer SubWorkers must include writable delegated scope".to_string(),
         ));
     }
+    if !input.command {
+        return Err(ToolError::InvalidArgument(
+            "Merge Request Reviewer SubWorkers require an explicit command grant".to_string(),
+        ));
+    }
     Ok(())
 }
 
@@ -370,7 +377,7 @@ impl Tool for SubWorkerSpawnTool {
             .reserve_internal_name(input.name.clone())
             .map_err(|error| ToolError::InvalidArgument(error.to_string()))?;
 
-        let mut workdir_rules = parse_workdir_scope(&input.scope)?;
+        let workdir_rules = parse_workdir_scope(&input.scope)?;
         let child_bash_output_dir = self.bash_output_dir.join("sub-workers").join(&input.name);
         tokio::fs::create_dir_all(&child_bash_output_dir)
             .await
@@ -380,28 +387,15 @@ impl Tool for SubWorkerSpawnTool {
                     child_bash_output_dir.display()
                 ))
             })?;
-        let source_workdir_session =
-            require_active_workdir_session(self.source_workdir_session.as_ref())?;
-        let transports_delegation_context = source_workdir_session.transports_delegation_context();
-        // Provider-transported sessions resolve every delegation rule in the
-        // receiving Workdir namespace. The Bash spill directory instead belongs
-        // to this Worker host, so forwarding it would widen the request with a
-        // foreign absolute path and fail the provider's existing scope check.
-        if !transports_delegation_context {
-            workdir_rules.push(WorkdirDelegationRule {
-                target: WorkdirPath::new_scoped(child_bash_output_dir.to_string_lossy())
-                    .map_err(|error| ToolError::ExecutionFailed(error.to_string()))?,
-                permission: WorkdirDelegationPermission::Read,
-                recursive: true,
-            });
-        }
-        let delegation_request = workdir_delegation_request(input.cwd.as_deref(), workdir_rules)?;
-        let workdir_delegation = source_workdir_session
-            .delegate(delegation_request)
+        let workdir_tool_broker = require_workdir_tool_broker(self.workdir_tool_broker.as_ref())?;
+        let tool_scope = workdir_tool_scope(input.cwd.as_deref(), workdir_rules, input.command)?;
+        let workdir_scope = workdir_tool_broker
+            .scope(tool_scope)
             .await
             .map_err(|error| {
-                ToolError::InvalidArgument(format!("delegate Workdir session: {error}"))
+                ToolError::InvalidArgument(format!("scope parent-owned Workdir tools: {error}"))
             })?;
+        let child_workdir_tool_broker = workdir_scope.broker();
 
         let spawn_selector =
             parse_spawn_profile_selector(input.profile.as_deref()).map_err(|msg| {
@@ -490,7 +484,6 @@ impl Tool for SubWorkerSpawnTool {
         )
         .await
         .map_err(|error| ToolError::ExecutionFailed(format!("build Internal Worker: {error}")))?;
-        child.bind_workdir_session(Some(workdir_delegation.scoped_session.clone()));
         child
             .add_scope_rules([ScopeRule {
                 target: child_bash_output_dir.clone(),
@@ -510,6 +503,7 @@ impl Tool for SubWorkerSpawnTool {
             self.runtime_base.clone(),
             child_registry.clone(),
             None,
+            Some(child_workdir_tool_broker.clone()),
         )
         .await
         .map_err(|error| {
@@ -552,6 +546,7 @@ impl Tool for SubWorkerSpawnTool {
                 );
                 parent_notifications.notify(message, true);
             })),
+            Some(child_workdir_tool_broker.clone()),
         )
         .await;
         let session = session_result.map_err(|error| {
@@ -621,7 +616,7 @@ impl Tool for SubWorkerSpawnTool {
         let record = crate::spawn::registry::InternalSpawnedWorkerRecord::new(
             input.name.clone(),
             scope_allow,
-            workdir_delegation,
+            workdir_scope,
             #[cfg(test)]
             installed_tools,
             session.clone(),
@@ -674,18 +669,18 @@ fn logical_workdir_path(value: &str, field: &str) -> Result<FsPath, ToolError> {
     })
 }
 
-fn parse_workdir_scope(rules: &[ScopeRuleInput]) -> Result<Vec<WorkdirDelegationRule>, ToolError> {
+fn parse_workdir_scope(rules: &[ScopeRuleInput]) -> Result<Vec<WorkdirToolScopeRule>, ToolError> {
     if rules.is_empty() {
         return Err(ToolError::InvalidArgument("scope must not be empty".into()));
     }
     rules
         .iter()
         .map(|rule| {
-            Ok(WorkdirDelegationRule {
+            Ok(WorkdirToolScopeRule {
                 target: logical_workdir_path(&rule.target, "scope.target")?,
                 permission: match rule.permission {
-                    PermissionInput::Read => WorkdirDelegationPermission::Read,
-                    PermissionInput::Write => WorkdirDelegationPermission::Write,
+                    PermissionInput::Read => WorkdirToolScopePermission::Read,
+                    PermissionInput::Write => WorkdirToolScopePermission::Write,
                 },
                 recursive: rule.recursive,
             })
@@ -693,22 +688,24 @@ fn parse_workdir_scope(rules: &[ScopeRuleInput]) -> Result<Vec<WorkdirDelegation
         .collect()
 }
 
-fn workdir_delegation_request(
+fn workdir_tool_scope(
     cwd: Option<&str>,
-    rules: Vec<WorkdirDelegationRule>,
-) -> Result<WorkdirDelegationRequest, ToolError> {
-    Ok(WorkdirDelegationRequest {
+    rules: Vec<WorkdirToolScopeRule>,
+    command: bool,
+) -> Result<WorkdirToolScope, ToolError> {
+    Ok(WorkdirToolScope {
         rules,
         cwd: logical_workdir_path(cwd.unwrap_or("."), "cwd")?,
+        command,
     })
 }
 
-fn require_active_workdir_session(
-    session: Option<&WorkdirSessionHandle>,
-) -> Result<&WorkdirSessionHandle, ToolError> {
-    session.ok_or_else(|| {
+fn require_workdir_tool_broker(
+    broker: Option<&WorkdirToolBroker>,
+) -> Result<&WorkdirToolBroker, ToolError> {
+    broker.ok_or_else(|| {
         ToolError::InvalidArgument(
-            "SubWorkerSpawn requires an active Workdir session; attach a Workdir before delegating filesystem access"
+            "SubWorkerSpawn requires parent-owned Workdir tools; attach a Workdir before granting filesystem access"
                 .to_string(),
         )
     })
@@ -946,7 +943,7 @@ pub(crate) fn sub_worker_spawn_tool(
     runtime_base: PathBuf,
     bash_output_dir: PathBuf,
     workspace_root: PathBuf,
-    source_workdir_session: Option<WorkdirSessionHandle>,
+    workdir_tool_broker: Option<WorkdirToolBroker>,
     registry: Arc<SpawnedWorkerRegistry>,
     spawner_manifest: WorkerManifest,
     prompts: Arc<ArcSwap<PromptCatalog>>,
@@ -958,7 +955,7 @@ pub(crate) fn sub_worker_spawn_tool(
         runtime_base,
         bash_output_dir,
         workspace_root,
-        source_workdir_session,
+        workdir_tool_broker,
         registry,
         spawner_manifest,
         prompts,
@@ -972,7 +969,7 @@ fn sub_worker_spawn_tool_impl(
     runtime_base: PathBuf,
     bash_output_dir: PathBuf,
     workspace_root: PathBuf,
-    source_workdir_session: Option<WorkdirSessionHandle>,
+    workdir_tool_broker: Option<WorkdirToolBroker>,
     registry: Arc<SpawnedWorkerRegistry>,
     spawner_manifest: WorkerManifest,
     prompts: Arc<ArcSwap<PromptCatalog>>,
@@ -1004,7 +1001,7 @@ fn sub_worker_spawn_tool_impl(
             runtime_base.clone(),
             bash_output_dir.clone(),
             workspace_root.clone(),
-            source_workdir_session.clone(),
+            workdir_tool_broker.clone(),
             registry.clone(),
             spawner_manifest.clone(),
             prompts.load_full().source(),
@@ -1037,12 +1034,12 @@ mod tests {
     };
 
     #[test]
-    fn missing_active_workdir_session_fails_deterministically() {
-        let error = require_active_workdir_session(None).unwrap_err();
+    fn missing_parent_workdir_tool_broker_fails_deterministically() {
+        let error = require_workdir_tool_broker(None).unwrap_err();
         assert!(matches!(
             error,
             ToolError::InvalidArgument(message)
-                if message.contains("requires an active Workdir session")
+                if message.contains("requires parent-owned Workdir tools")
         ));
     }
 
@@ -1079,6 +1076,7 @@ mod tests {
         let valid: SubWorkerSpawnInput = serde_json::from_value(serde_json::json!({
             "name":"reviewer","task":"review","profile":"builtin:reviewer",
             "scope":[{"target":"work","permission":"write"}],
+            "command":true,
             "review":{"ticket_id":"T1"}
         }))
         .unwrap();
@@ -1173,7 +1171,7 @@ enabled = false
         let fail_requests = Arc::new(AtomicBool::new(false));
         let prompt_loader = PromptCatalogSource::builtins_only();
         let (parent_method_tx, mut parent_method_rx) = mpsc::channel(8);
-        let source_workdir_session = workdir::delegation_capable_session(Arc::new(
+        let workdir_tool_broker = workdir::WorkdirToolBroker::new(Arc::new(
             workdir::LocalWorkdirSession::materialized_bound(
                 workdir::Workdir::new("test-workdir"),
                 workspace_root.clone(),
@@ -1189,7 +1187,7 @@ enabled = false
             runtime.path().to_path_buf(),
             bash_output_dir.clone(),
             workspace_root.clone(),
-            Some(source_workdir_session),
+            Some(workdir_tool_broker),
             registry.clone(),
             manifest.clone(),
             prompt_loader,
@@ -1212,7 +1210,8 @@ enabled = false
                 "target": ".",
                 "permission": "write",
                 "recursive": true
-            }]
+            }],
+            "command": true
         });
 
         assert!(spawner_scope.snapshot().is_writable(&workspace_root));
@@ -1247,15 +1246,6 @@ enabled = false
         let record = registry
             .get_internal("reviewer-child")
             .expect("Internal reviewer registry record");
-        let child_bash_output_dir = bash_output_dir.join("sub-workers").join("reviewer-child");
-        record
-            .workdir_delegation
-            .scoped_session
-            .stat(workdir::StatRequest {
-                path: WorkdirPath::new_scoped(child_bash_output_dir.to_string_lossy()).unwrap(),
-            })
-            .await
-            .expect("local child retains read scope for its Bash output directory");
         for required in ["Read", "Write", "Edit", "Glob", "Grep", "Bash"] {
             assert!(
                 record.installed_tools.iter().any(|name| name == required),
@@ -1371,7 +1361,7 @@ enabled = false
             "Stopped terminal child must release its delegated Workdir session"
         );
         assert!(
-            !record.workdir_delegation.is_active(),
+            !record.workdir_tool_scope.is_active(),
             "stopped child must revoke cloned scoped sessions"
         );
         assert!(registry.get_internal("reviewer-child").is_some());
@@ -1426,7 +1416,7 @@ enabled = false
             Arc::new(AvailableWorkspaceClient),
         );
         let remote_client = Arc::new(StrictRemoteWorkdirWorkspaceClient::default());
-        let source_workdir_session = workdir::delegation_capable_session(
+        let workdir_tool_broker = workdir::WorkdirToolBroker::new(
             WorkspaceAttachedWorkdirSession::handle(remote_client.clone()),
         );
         let calls = Arc::new(AtomicUsize::new(0));
@@ -1438,7 +1428,7 @@ enabled = false
             runtime.path().to_path_buf(),
             bash_output_dir.clone(),
             workspace_root.clone(),
-            Some(source_workdir_session),
+            Some(workdir_tool_broker),
             registry.clone(),
             manifest,
             PromptCatalogSource::builtins_only(),
@@ -1478,51 +1468,12 @@ enabled = false
             record.session.wait_until_idle().await,
             crate::internal_worker::InternalWorkerSessionStatus::Idle
         );
+        assert!(record.installed_tools.iter().any(|tool| tool == "Write"));
+        assert!(!record.installed_tools.iter().any(|tool| tool == "Bash"));
         assert_eq!(calls.load(Ordering::SeqCst), 1);
-        assert_eq!(
-            remote_client
-                .foreign_scope_rejections
-                .load(Ordering::SeqCst),
-            0
-        );
-        let child_bash_output_dir = bash_output_dir.join("sub-workers").join("remote-child");
-        assert!(child_bash_output_dir.is_dir());
-        for required in ["Read", "Write", "Edit", "Glob", "Grep", "Bash"] {
         assert!(
-                record.installed_tools.iter().any(|name| name == required),
-                "remote write-scoped child is missing {required}: {:?}",
-                record.installed_tools
-            );
-        }
-
-        let remote_requests = remote_client.requests();
-        let operate_requests = remote_requests
-            .iter()
-            .filter(|request| request.body.is_some())
-            .collect::<Vec<_>>();
-        assert_eq!(
-            operate_requests.len(),
-            1,
-            "remote requests: {remote_requests:?}"
-        );
-        let operation_body: serde_json::Value = serde_json::from_str(
-            operate_requests[0]
-                .body
-                .as_deref()
-                .expect("remote operation body"),
-        )
-        .unwrap();
-        let rules = operation_body["delegations"][0]["rules"]
-            .as_array()
-            .expect("delegation rules");
-        assert_eq!(rules.len(), 1, "remote operation body: {operation_body}");
-        assert_eq!(rules[0]["target"], "");
-        assert!(
-            !operation_body.to_string().contains(
-                child_bash_output_dir
-                    .to_str()
-                    .expect("UTF-8 test output directory")
-            )
+            remote_client.requests().is_empty(),
+            "spawning a child must not open or delegate a provider Workdir session"
         );
     }
 
@@ -1534,6 +1485,7 @@ enabled = false
             .and_then(serde_json::Value::as_object)
             .expect("schema properties");
         assert!(properties.contains_key("cwd"), "schema: {schema}");
+        assert!(properties.contains_key("command"), "schema: {schema}");
         let required = schema
             .get("required")
             .and_then(serde_json::Value::as_array)
@@ -1663,7 +1615,6 @@ enabled = false
     #[derive(Debug, Default)]
     struct StrictRemoteWorkdirWorkspaceClient {
         requests: Mutex<Vec<WorkspaceRequest>>,
-        foreign_scope_rejections: AtomicUsize,
     }
 
     impl StrictRemoteWorkdirWorkspaceClient {
@@ -1695,59 +1646,10 @@ enabled = false
             self.requests
                 .lock()
                 .expect("remote Workdir request lock")
-                .push(request.clone());
-            if request.path.ends_with("/fence") {
-                return Ok(WorkspaceResponse {
-                    status: 200,
-                    body: serde_json::json!({ "value": "remote-fence-1" }).to_string(),
-                });
-            }
-
-            let body: serde_json::Value = serde_json::from_str(
-                request
-                    .body
-                    .as_deref()
-                    .ok_or_else(|| WorkspaceClientError::Request("missing request body".into()))?,
-            )
-            .map_err(|error| WorkspaceClientError::Request(error.to_string()))?;
-            let has_foreign_scope = body
-                .get("delegations")
-                .and_then(serde_json::Value::as_array)
-                .into_iter()
-                .flatten()
-                .flat_map(|delegation| {
-                    delegation
-                        .get("rules")
-                        .and_then(serde_json::Value::as_array)
-                        .into_iter()
-                        .flatten()
-                })
-                .filter_map(|rule| rule.get("target").and_then(serde_json::Value::as_str))
-                .any(|target| Path::new(target).is_absolute());
-            if has_foreign_scope {
-                self.foreign_scope_rejections.fetch_add(1, Ordering::SeqCst);
-                return Ok(WorkspaceResponse {
-                    status: 403,
-                    body: serde_json::json!({
-                        "code": "out_of_scope",
-                        "message": "Worker-host path is outside the remote Workdir namespace"
-                    })
-                    .to_string(),
-                });
-            }
-
-            Ok(WorkspaceResponse {
-                status: 200,
-                body: serde_json::json!({
-                    "operation": "stat",
-                    "result": {
-                        "path": "",
-                        "kind": "directory",
-                        "size": 0
-                    }
-                })
-                .to_string(),
-            })
+                .push(request);
+            Err(WorkspaceClientError::Request(
+                "SubWorker spawn must not call the remote Workdir provider".into(),
+            ))
         }
     }
 

crates/worker/tests/controller_test.rs

@@ -332,6 +332,7 @@ async fn shutdown_closes_bound_workdir_session() {
             command: "sleep 30".to_owned(),
             timeout_secs: 60,
             output_limit: 1024,
+            cwd: None,
             spill_dir: None,
             tool_call_id: None,
         })
@@ -376,6 +377,7 @@ async fn controller_projects_workdir_command_events_and_snapshot_state() {
             command: "printf ready; sleep 0.3; printf done".to_owned(),
             timeout_secs: 5,
             output_limit: 1024,
+            cwd: None,
             spill_dir: None,
             tool_call_id: Some("tool-command-1".into()),
         })
@@ -484,6 +486,7 @@ async fn controller_refreshes_command_snapshot_after_high_output_provider_lag()
                 .to_owned(),
             timeout_secs: 10,
             output_limit: 1024,
+            cwd: None,
             spill_dir: None,
             tool_call_id: Some("tool-high-output".into()),
         })
@@ -560,6 +563,7 @@ async fn controller_startup_failure_closes_bound_workdir_session() {
                 command: "printf unreachable".to_owned(),
                 timeout_secs: 5,
                 output_limit: 1024,
+                cwd: None,
                 spill_dir: None,
                 tool_call_id: None,
             })

crates/workspace-server/src/server.rs

@@ -48,8 +48,7 @@ use workdir::http::{
 };
 use workdir::workspace::{
     MaterializerKind, WorkingDirectoryCleanupTarget, WorkingDirectoryOccupancy,
-    WorkingDirectoryStatusKind, WorkingDirectorySummary, WorkspaceWorkdirSessionFence,
-    WorkspaceWorkdirSessionOperationRequest,
+    WorkingDirectoryStatusKind, WorkingDirectorySummary, WorkspaceWorkdirSessionOperationRequest,
 };
 use workdir::{CommandHandle, WorkdirSessionHandle};
 use worker::feature::builtin::{WorkerObservationSubject, WorkerObservationSubjectRef};
@@ -355,7 +354,6 @@ static EMBEDDED_RUNTIME_REQUEST_IDENTITY: std::sync::LazyLock<
 struct WorkdirCommandSession {
     source: WorkdirSessionHandle,
     provider_handle: CommandHandle,
-    delegations: Vec<workdir::WorkdirDelegationRequest>,
 }
 
 enum RegisteredWorkdirSession {
@@ -398,7 +396,6 @@ impl WorkdirSessionRegistry {
         worker: RuntimeWorkerRef,
         source: WorkdirSessionHandle,
         provider_handle: CommandHandle,
-        delegations: Vec<workdir::WorkdirDelegationRequest>,
     ) -> CommandHandle {
         let external_handle = loop {
             let candidate = CommandHandle(Uuid::now_v7().to_string());
@@ -414,7 +411,6 @@ impl WorkdirSessionRegistry {
             WorkdirCommandSession {
                 source,
                 provider_handle,
-                delegations,
             },
         );
         external_handle
@@ -2586,10 +2582,6 @@ fn build_inner_router(api: WorkspaceApi) -> Router {
             post(scoped_attach_current_worker_workdir)
                 .delete(scoped_detach_current_worker_workdir),
         )
-        .route(
-            "/api/w/{workspace_id}/workers/self/workdir-session/fence",
-            get(scoped_current_worker_workdir_session_fence),
-        )
         .route(
             "/api/w/{workspace_id}/workers/self/workdir-session/operations",
             post(scoped_execute_current_worker_workdir_operation),
@@ -7341,46 +7333,11 @@ async fn scoped_detach_current_worker_workdir(
     }))
 }
 
-async fn scoped_current_worker_workdir_session_fence(
-    State(api): State<WorkspaceApi>,
-    AxumPath(path): AxumPath<ScopedWorkspacePath>,
-    headers: HeaderMap,
-) -> ApiResult<Json<WorkspaceWorkdirSessionFence>> {
-    validate_workspace_scope(&api, &path.workspace_id)?;
-    let worker = current_worker_identity(&api, &path.workspace_id, &headers)?;
-    let session_lock = current_worker_session_lock(&api, &worker);
-    let _session_guard = session_lock.lock().await;
-    let link = current_worker_active_attachment(&api, &worker)?;
-    Ok(Json(WorkspaceWorkdirSessionFence {
-        value: current_worker_workdir_session_fence(&link),
-    }))
-}
-
-fn current_worker_workdir_session_fence(link: &WorkerWorkdirLinkRecord) -> String {
-    format!("v1:{}\0{}", link.workdir_id, link.linked_at)
-}
-
-fn validate_current_worker_workdir_session_fence(
-    link: &WorkerWorkdirLinkRecord,
-    expected: Option<&str>,
-) -> Result<()> {
-    if expected.is_some_and(|expected| expected != current_worker_workdir_session_fence(link)) {
-        Err(Error::WorkdirAttachmentConflict(
-            "delegated Workdir session attachment changed".to_string(),
-        ))
-    } else {
-        Ok(())
-    }
-}
-
 fn validated_current_worker_attachment(
     api: &WorkspaceApi,
     worker: &RuntimeWorkerRef,
-    expected_session_fence: Option<&str>,
 ) -> ApiResult<WorkerWorkdirLinkRecord> {
-    let link = current_worker_active_attachment(api, worker)?;
-    validate_current_worker_workdir_session_fence(&link, expected_session_fence)?;
-    Ok(link)
+    current_worker_active_attachment(api, worker)
 }
 
 #[derive(Debug)]
@@ -7435,23 +7392,13 @@ async fn scoped_execute_current_worker_workdir_operation(
 ) -> std::result::Result<Json<WorkdirSessionOperationResult>, WorkdirOperationApiError> {
     validate_workspace_scope(&api, &path.workspace_id)?;
     let worker = current_worker_identity(&api, &path.workspace_id, &headers)?;
-    let expected_session_fence = request.expected_session_fence;
-    let delegations = request.delegations;
     let result = match request.operation {
         WorkdirSessionOperation::CommandStart(command) => {
             let session_lock = current_worker_session_lock(&api, &worker);
             let _session_guard = session_lock.lock().await;
-            let link = validated_current_worker_attachment(
-                &api,
-                &worker,
-                expected_session_fence.as_deref(),
-            )?;
+            let link = validated_current_worker_attachment(&api, &worker)?;
             let source = open_current_worker_workdir_session_locked(&api, &worker, &link).await?;
-            let applied =
-                apply_current_worker_delegations(&worker, source.clone(), delegations.clone())
-                    .await?;
-            let provider_handle = applied
-                .scoped_session
+            let provider_handle = source
                 .start_command(command)
                 .await
                 .map_err(|error| current_worker_workdir_operation_error(&worker, error))?;
@@ -7470,58 +7417,32 @@ async fn scoped_execute_current_worker_workdir_operation(
                 .workdir_sessions
                 .lock()
                 .expect("Workdir session registry lock poisoned")
-                .register_command(
-                    worker.clone(),
-                    registered_source,
-                    provider_handle,
-                    delegations,
-                );
+                .register_command(worker.clone(), registered_source, provider_handle);
             WorkdirSessionOperationResult::CommandStart(external_handle)
         }
         WorkdirSessionOperation::CommandStatus(external_handle) => {
-            let (session, provider_handle) = current_worker_command_session(
-                &api,
-                &worker,
-                &external_handle,
-                &delegations,
-                expected_session_fence.as_deref(),
-            )
-            .await?;
+            let (session, provider_handle) =
+                current_worker_command_session(&api, &worker, &external_handle)?;
             session
-                .scoped_session
                 .command_status(provider_handle)
                 .await
                 .map(WorkdirSessionOperationResult::CommandStatus)
                 .map_err(|error| current_worker_workdir_operation_error(&worker, error))?
         }
         WorkdirSessionOperation::CommandOutput(mut output) => {
-            let (session, provider_handle) = current_worker_command_session(
-                &api,
-                &worker,
-                &output.handle,
-                &delegations,
-                expected_session_fence.as_deref(),
-            )
-            .await?;
+            let (session, provider_handle) =
+                current_worker_command_session(&api, &worker, &output.handle)?;
             output.handle = provider_handle;
             session
-                .scoped_session
                 .command_output(output)
                 .await
                 .map(WorkdirSessionOperationResult::CommandOutput)
                 .map_err(|error| current_worker_workdir_operation_error(&worker, error))?
         }
         WorkdirSessionOperation::CommandCancel(external_handle) => {
-            let (session, provider_handle) = current_worker_command_session(
-                &api,
-                &worker,
-                &external_handle,
-                &delegations,
-                expected_session_fence.as_deref(),
-            )
-            .await?;
+            let (session, provider_handle) =
+                current_worker_command_session(&api, &worker, &external_handle)?;
             session
-                .scoped_session
                 .cancel_command(provider_handle)
                 .await
                 .map(|()| WorkdirSessionOperationResult::CommandCancel)
@@ -7536,14 +7457,9 @@ async fn scoped_execute_current_worker_workdir_operation(
         | WorkdirSessionOperation::Grep(_)) => {
             let session_lock = current_worker_session_lock(&api, &worker);
             let _session_guard = session_lock.lock().await;
-            let link = validated_current_worker_attachment(
-                &api,
-                &worker,
-                expected_session_fence.as_deref(),
-            )?;
+            let link = validated_current_worker_attachment(&api, &worker)?;
             let source = open_current_worker_workdir_session_locked(&api, &worker, &link).await?;
-            let applied = apply_current_worker_delegations(&worker, source, delegations).await?;
-            execute_workdir_session_operation(&applied.scoped_session, operation)
+            execute_workdir_session_operation(&source, operation)
                 .await
                 .map_err(|error| current_worker_workdir_operation_error(&worker, error))?
         }
@@ -7551,29 +7467,12 @@ async fn scoped_execute_current_worker_workdir_operation(
     Ok(Json(result))
 }
 
-async fn apply_current_worker_delegations(
-    worker: &RuntimeWorkerRef,
-    source: WorkdirSessionHandle,
-    delegations: Vec<workdir::WorkdirDelegationRequest>,
-) -> Result<workdir::AppliedWorkdirDelegation> {
-    workdir::apply_delegation_chain(source, delegations)
-        .await
-        .map_err(|error| Error::RuntimeOperationFailed {
-            runtime_id: worker.runtime_id.clone(),
-            code: "workdir_session_delegation_failed".to_string(),
-            message: error.to_string(),
-        })
-}
-
-async fn current_worker_command_session(
+fn current_worker_command_session(
     api: &WorkspaceApi,
     worker: &RuntimeWorkerRef,
     external_handle: &CommandHandle,
-    delegations: &[workdir::WorkdirDelegationRequest],
-    expected_session_fence: Option<&str>,
-) -> std::result::Result<(workdir::AppliedWorkdirDelegation, CommandHandle), WorkdirOperationApiError>
-{
-    let _link = validated_current_worker_attachment(api, worker, expected_session_fence)?;
+) -> std::result::Result<(WorkdirSessionHandle, CommandHandle), WorkdirOperationApiError> {
+    let _link = validated_current_worker_attachment(api, worker)?;
     let command = api
         .workdir_sessions
         .lock()
@@ -7585,15 +7484,7 @@ async fn current_worker_command_session(
                 workdir::WorkdirError::UnknownCommand(external_handle.0.clone()),
             ))
         })?;
-    if command.delegations != delegations {
-        return Err(Error::WorkdirAttachmentConflict(
-            "command lifecycle delegation differs from CommandStart".to_string(),
-        )
-        .into());
-    }
-    let session =
-        apply_current_worker_delegations(worker, command.source, command.delegations).await?;
-    Ok((session, command.provider_handle))
+    Ok((command.source, command.provider_handle))
 }
 
 fn current_worker_workdir_operation_error(
@@ -16775,6 +16666,7 @@ mod tests {
                 command: "printf ready; sleep 30".to_string(),
                 timeout_secs: 60,
                 output_limit: 4096,
+                cwd: None,
                 spill_dir: None,
                 tool_call_id: Some("tool-call-command-session".to_string()),
             })
@@ -16784,12 +16676,8 @@ mod tests {
         let mut registry = WorkdirSessionRegistry::default();
         registry.insert_attachment(worker.clone(), source.clone());
         let registered_source = registry.remove_attachment(&worker).unwrap();
-        let external_handle = registry.register_command(
-            worker.clone(),
-            registered_source,
-            provider_handle.clone(),
-            Vec::new(),
-        );
+        let external_handle =
+            registry.register_command(worker.clone(), registered_source, provider_handle.clone());
         assert_ne!(external_handle, provider_handle);
 
         let refreshed: WorkdirSessionHandle = Arc::new(workdir::LocalWorkdirSession::new(
@@ -23503,30 +23391,6 @@ mod tests {
         assert_eq!(response.status(), StatusCode::BAD_REQUEST);
     }
 
-    #[test]
-    fn delegated_workdir_session_fence_rejects_reattached_link() {
-        let first = WorkerWorkdirLinkRecord {
-            workspace_id: "workspace-a".to_string(),
-            worker: workdir::workspace::RuntimeWorkerRef::new("runtime-a", "worker-a"),
-            workdir_id: "workdir-a".to_string(),
-            role: "primary".to_string(),
-            linked_at: "2026-01-01T00:00:00Z".to_string(),
-            unlinked_at: None,
-        };
-        let expected = current_worker_workdir_session_fence(&first);
-        assert!(validate_current_worker_workdir_session_fence(&first, None).is_ok());
-        assert!(validate_current_worker_workdir_session_fence(&first, Some(&expected)).is_ok());
-
-        let reattached = WorkerWorkdirLinkRecord {
-            linked_at: "2026-01-01T00:00:01Z".to_string(),
-            ..first
-        };
-        assert!(matches!(
-            validate_current_worker_workdir_session_fence(&reattached, Some(&expected)),
-            Err(Error::WorkdirAttachmentConflict(_))
-        ));
-    }
-
     #[tokio::test]
     async fn backend_workdir_session_proxy_executes_typed_operations() {
         use manifest::Scope;

resources/flows/coder-review.dcdl

@@ -15,7 +15,7 @@
         };
 
         review = {
-            instructions = "Use the current Ticket Merge Request as review authority. Call `ShowMergeRequest` and confirm its source selector resolves to exact committed implementation HEAD, then spawn one actual direct-child SubWorker with profile builtin:reviewer, write scope for Workdir inspection and command validation, and only the Ticket id in the structured review handoff. The trusted spawn layer records `ReviewRequested` with the exact source ref and injects review capability; do not place commit/ref identity, capability material, or a prewritten verdict in model input. The child must commit `ReviewMergeRequest`; prose output and Worker observation are not approval authority. After the structured result for the exact current source ref exists, request a Flow transition.";
+            instructions = "Use the current Ticket Merge Request as review authority. Call `ShowMergeRequest` and confirm its source selector resolves to exact committed implementation HEAD, then spawn one actual direct-child SubWorker with profile builtin:reviewer, write scope plus an explicit command grant for Workdir inspection and command validation, and only the Ticket id in the structured review handoff. The trusted spawn layer records `ReviewRequested` with the exact source ref and injects review capability; do not place commit/ref identity, capability material, or a prewritten verdict in model input. The child must commit `ReviewMergeRequest`; prose output and Worker observation are not approval authority. After the structured result for the exact current source ref exists, request a Flow transition.";
             transitions = {
                 approved = {
                     target = "complete";

resources/prompts/internal/sub_worker_spawn_tool_description.md

@@ -1,8 +1,8 @@
 Spawn a parent-owned Internal SubWorker session to split context for a delegated task. The parent Worker's write scope is reduced by the scope passed here; the Internal SubWorker starts running `task` immediately without creating a Runtime Worker record, OS process, PID, or Unix socket. It remains available for follow-up turns until explicitly stopped or its parent exits.
 
-Optional `cwd`: when provided, the spawned SubWorker's tool default working directory only. It must be an absolute existing directory covered by the child's delegated readable scope, and it does not change workspace/Profile/memory/Ticket roots or grant authority. `name` must be unique among this Worker's direct children.
+Optional `cwd`: when provided, the spawned SubWorker's tool default working directory only. It must be a Workdir-relative existing directory covered by the child's readable scope, and it does not change workspace/Profile/memory/Ticket roots or grant authority. `name` must be unique among this Worker's direct children.
 
-Profile selection: `profile` may be omitted or set to `default` to use the effective child default profile, set to `inherit` to derive reusable child configuration from this Worker, or set to one of the registry selectors below. Raw/path profile selectors are not accepted by SubWorkerSpawn. `scope` is always the only delegated filesystem capability; profile scope is replaced by the explicit SubWorkerSpawn scope.
+Profile selection: `profile` may be omitted or set to `default` to use the effective child default profile, set to `inherit` to derive reusable child configuration from this Worker, or set to one of the registry selectors below. Raw/path profile selectors are not accepted by SubWorkerSpawn. `scope` is the child's only filesystem capability and replaces profile scope. `command` is a separate explicit grant, defaults to false, and is accepted only with a writable scope; writable scope alone does not grant command execution.
 
 Default profile: {{ default_profile }}
 Special selector: inherit — derive reusable model/worker/tool policy from the spawner while replacing worker.name and scope.