fix(subagent): check requires_tools after all run mounts append

Author: TheGreatAxios

src/subagent/run-requires-tools.test.ts

@@ -109,6 +109,44 @@ describe("runSubAgent requires_tools mount echo", () => {
     expect((error as Error).message).not.toContain("stale_snapshot");
   }, 15_000);
 
+  test("stamped manage_tasks survives the echo under a narrow allowlist", async () => {
+    const cwd = await tmpCwd();
+    const error = await withFailingInference(async (baseURL) => {
+      try {
+        await runSubAgent({
+          ...baseParams(cwd, baseURL),
+          capabilities: { mode: "allow", tools: ["read_file"] },
+          requiresTools: ["manage_tasks"],
+        });
+      } catch (err) {
+        return err;
+      }
+      throw new Error("runSubAgent did not throw");
+    });
+
+    expect(error).toBeInstanceOf(Error);
+    expect((error as Error).message).not.toContain("stale_snapshot");
+  }, 15_000);
+
+  test("stamped update_plan alias survives the echo under a narrow allowlist", async () => {
+    const cwd = await tmpCwd();
+    const error = await withFailingInference(async (baseURL) => {
+      try {
+        await runSubAgent({
+          ...baseParams(cwd, baseURL),
+          capabilities: { mode: "allow", tools: ["read_file"] },
+          requiresTools: ["update_plan"],
+        });
+      } catch (err) {
+        return err;
+      }
+      throw new Error("runSubAgent did not throw");
+    });
+
+    expect(error).toBeInstanceOf(Error);
+    expect((error as Error).message).not.toContain("stale_snapshot");
+  }, 15_000);
+
   test("absent requiresTools leaves the mount path unchanged", async () => {
     const cwd = await tmpCwd();
     const error = await withFailingInference(async (baseURL) => {

src/subagent/run.ts

@@ -772,29 +772,6 @@ async function runSubAgentInner(
     if (params.capabilities !== undefined) {
       tools = applyCapabilityFilter(tools, params.capabilities);
     }
-    // CL-9476 mount echo: dispatch verified requires_tools pre-spawn, but the
-    // filter or mount may have shifted since — a stamped tool missing here is
-    // a stale snapshot, a setup_error that never retries (non-continuable).
-    // Dispatch-side rejection is the normal path; this throw never fires for
-    // a dispatch that passed preflight against the same mount.
-    if (params.requiresTools !== undefined && params.requiresTools.length > 0) {
-      const mountedNames = tools.map((tool) => tool.definition.name);
-      const mountedCheck = checkMountedRequiresTools(
-        params.requiresTools,
-        mountedNames,
-      );
-      if (!mountedCheck.ok) {
-        throw new Error(
-          formatCapabilityUnavailable(
-            {
-              code: "stale_snapshot",
-              tool: mountedCheck.missing[0] ?? "unknown",
-            },
-            params.directorId ?? params.description,
-          ),
-        );
-      }
-    }
     backgroundCollectMounted = tools.some(
       (tool) => tool.definition.name === "shell_collect",
     );
@@ -1022,6 +999,31 @@ async function runSubAgentInner(
       ];
     }
 
+    // CL-9476 mount echo: dispatch verified requires_tools pre-spawn, but the
+    // filter or mount may have shifted since — a stamped tool missing here is
+    // a stale snapshot, a setup_error that never retries (non-continuable).
+    // Dispatch-side rejection is the normal path. This check runs after ALL
+    // mounts (manage_tasks, leaf submit_result/ask_director, fleet verbs), so
+    // a dispatch that passed preflight against the same mount never throws.
+    if (params.requiresTools !== undefined && params.requiresTools.length > 0) {
+      const mountedNames = tools.map((tool) => tool.definition.name);
+      const mountedCheck = checkMountedRequiresTools(
+        params.requiresTools,
+        mountedNames,
+      );
+      if (!mountedCheck.ok) {
+        throw new Error(
+          formatCapabilityUnavailable(
+            {
+              code: "stale_snapshot",
+              tool: mountedCheck.missing[0] ?? "unknown",
+            },
+            params.directorId ?? params.description,
+          ),
+        );
+      }
+    }
+
     tools = wrapAgentToolsWithResultTruncation(tools, {
       getBlobWriter: () => childBlobWriter,
       getContextDir: () => childContextDir,