fix(copilot): address round-2 PR review and fix tool loading on stop

Backend:
- Add _validate_and_get_session() call to cancel endpoint (404 for
  invalid sessions, consistent with other endpoints)
- Reduce polling max_wait from 10s to 5s (stay below reverse-proxy
  read timeouts)
- Return cancelled=True with reason="cancel_published_not_confirmed"
  on timeout (cancel event IS published, just not yet confirmed)

Frontend:
- Mark in-progress tool parts as output-error on stop so spinners
  clear immediately instead of spinning forever
- Toast on cancel API failure (network error / 5xx)

autogpt_platform/backend/backend/api/features/chat/routes.py

@@ -334,8 +334,10 @@ async def cancel_session_task(
 
     Publishes a cancel event to the executor via RabbitMQ FANOUT, then
     polls Redis until the task status flips from ``running`` or a timeout
-    (10 s) is reached.  Returns only after the cancellation is confirmed.
+    (5 s) is reached.  Returns only after the cancellation is confirmed.
     """
+    await _validate_and_get_session(session_id, user_id)
+
     active_task, _ = await stream_registry.get_active_task_for_session(
         session_id, user_id
     )
@@ -350,8 +352,9 @@ async def cancel_session_task(
     )
 
     # Poll until the executor confirms the task is no longer running.
+    # Keep max_wait below typical reverse-proxy read timeouts.
     poll_interval = 0.5
-    max_wait = 10.0
+    max_wait = 5.0
     waited = 0.0
     while waited < max_wait:
         await asyncio.sleep(poll_interval)
@@ -365,9 +368,11 @@ async def cancel_session_task(
             return CancelTaskResponse(cancelled=True, task_id=task_id)
 
     logger.warning(
-        f"[CANCEL] Task ...{task_id[-8:]} still running after {max_wait}s"
+        f"[CANCEL] Task ...{task_id[-8:]} not confirmed after {max_wait}s"
+    )
+    return CancelTaskResponse(
+        cancelled=True, task_id=task_id, reason="cancel_published_not_confirmed"
     )
-    return CancelTaskResponse(cancelled=False, task_id=task_id, reason="timeout")
 
 
 @router.post(

autogpt_platform/frontend/src/app/(platform)/copilot/useCopilotPage.ts

@@ -114,16 +114,23 @@ export function useCopilotPage() {
   // the cancel API to actually stop the executor and wait for confirmation.
   const stop = useCallback(async () => {
     sdkStop();
+
+    // Mark any in-progress tool parts as errored so spinners stop.
+    setMessages((prev) =>
+      prev.map((msg) => ({
+        ...msg,
+        parts: msg.parts.map((part) =>
+          "state" in part &&
+          (part.state === "input-streaming" || part.state === "input-available")
+            ? { ...part, state: "output-error" as const, errorText: "Cancelled" }
+            : part,
+        ),
+      })),
+    );
+
     if (!sessionId) return;
     try {
-      const res = await postV2CancelSessionTask(sessionId);
-      if (res.status === 200 && !res.data.cancelled) {
-        toast({
-          title: "Could not stop the task",
-          description: "The task may still be running in the background.",
-          variant: "destructive",
-        });
-      }
+      await postV2CancelSessionTask(sessionId);
     } catch {
       toast({
         title: "Could not stop the task",
@@ -131,7 +138,7 @@ export function useCopilotPage() {
         variant: "destructive",
       });
     }
-  }, [sdkStop, sessionId]);
+  }, [sdkStop, sessionId, setMessages]);
 
   // Abort the stream if the backend doesn't start sending data within 12s.
   const stopRef = useRef(stop);

autogpt_platform/frontend/src/app/api/openapi.json

@@ -1267,7 +1267,7 @@
       "post": {
         "tags": ["v2", "chat", "chat"],
         "summary": "Cancel Session Task",
-        "description": "Cancel the active streaming task for a session.\n\nPublishes a cancel event to the executor via RabbitMQ FANOUT, then\npolls Redis until the task status flips from ``running`` or a timeout\n(10 s) is reached.  Returns only after the cancellation is confirmed.",
+        "description": "Cancel the active streaming task for a session.\n\nPublishes a cancel event to the executor via RabbitMQ FANOUT, then\npolls Redis until the task status flips from ``running`` or a timeout\n(5 s) is reached.  Returns only after the cancellation is confirmed.",
         "operationId": "postV2CancelSessionTask",
         "security": [{ "HTTPBearerJWT": [] }],
         "parameters": [