fix: keep stuck detector active by default

packages/engine/src/__tests__/stuck-task-detector.test.ts

@@ -718,21 +718,52 @@ describe("StuckTaskDetector", () => {
       vi.useRealTimers();
     });
 
-    it("does nothing when timeout is disabled", async () => {
+    it("falls back to workflow step timeout when stuck timeout is unset", async () => {
       store = createMockStore({
-        getSettings: vi.fn().mockResolvedValue({ taskStuckTimeoutMs: undefined }),
+        getSettings: vi.fn().mockResolvedValue({
+          taskStuckTimeoutMs: undefined,
+          workflowStepTimeoutMs: 60_000,
+        }),
       });
-      const customDetector = new StuckTaskDetector(store);
+      const onStuck = vi.fn();
+      const customDetector = new StuckTaskDetector(store, { onStuck });
       const session = createMockSession();
 
       customDetector.trackTask("FN-001", session);
 
       vi.useFakeTimers({ shouldAdvanceTime: true });
-      vi.advanceTimersByTime(61000);
+      vi.advanceTimersByTime(61_000);
 
       await customDetector.checkNow();
 
-      expect(store.moveTask).not.toHaveBeenCalled();
+      expect(onStuck).toHaveBeenCalledWith(
+        expect.objectContaining({ taskId: "FN-001", reason: "inactivity" }),
+      );
+      expect(session.dispose).toHaveBeenCalled();
+
+      vi.useRealTimers();
+    });
+
+    it("does nothing when both stuck and workflow timeouts are disabled", async () => {
+      store = createMockStore({
+        getSettings: vi.fn().mockResolvedValue({
+          taskStuckTimeoutMs: undefined,
+          workflowStepTimeoutMs: undefined,
+        }),
+      });
+      const onStuck = vi.fn();
+      const customDetector = new StuckTaskDetector(store, { onStuck });
+      const session = createMockSession();
+
+      customDetector.trackTask("FN-001", session);
+
+      vi.useFakeTimers({ shouldAdvanceTime: true });
+      vi.advanceTimersByTime(61_000);
+
+      await customDetector.checkNow();
+
+      expect(onStuck).not.toHaveBeenCalled();
+      expect(session.dispose).not.toHaveBeenCalled();
 
       vi.useRealTimers();
     });

packages/engine/src/stuck-task-detector.ts

@@ -11,7 +11,9 @@
  * - `recordProgress(taskId)` — step transitions (in-progress, done, skipped); resets counters
  *
  * The detector polls at a configurable interval and compares timestamps against
- * `taskStuckTimeoutMs` from settings.
+ * `taskStuckTimeoutMs` from settings. When that explicit override is unset, the
+ * detector falls back to `workflowStepTimeoutMs` so in-flight tool calls cannot
+ * leave an in-progress task unmonitored by default.
  */
 
 import type { TaskStore, Settings } from "@fusion/core";
@@ -470,8 +472,8 @@ export class StuckTaskDetector {
     // Defensive fallback for pause windows where lifecycle hooks haven't run yet.
     if (settings.globalPause || settings.enginePaused) return;
 
-    const timeoutMs = settings.taskStuckTimeoutMs;
-    if (!timeoutMs || timeoutMs <= 0) return; // Disabled
+    const timeoutMs = settings.taskStuckTimeoutMs ?? settings.workflowStepTimeoutMs;
+    if (!timeoutMs || timeoutMs <= 0) return; // Disabled only when both stuck and workflow timeouts are unset/disabled
 
     const stuckTasks: string[] = [];