# Stop Thread

Stops the execution in flight on a thread. The request has no body.

When an execution is in flight, the runtime aborts it:

- The run settles as `idle` with reason `aborted_by_user`. The [WebSocket stream](/docs/api-reference/websocket/stream) sends a `thread_status` frame with that status.
- `state.execution.abortSignal` fires in the running tool or hook.
- Each tool call that has no result receives a tool message with the content `Execution stopped by user` and `tool_status` `error`.
- Each message with status `pending` changes to `failed`.
- The thread stores one `system` message with the content `Execution stopped by user`.
- The log stream sends a `stopped_by_user` frame.

The route is idempotent. A request to a thread with no execution in flight returns the same `200` response. That request stores no stop message and sends no `stopped_by_user` frame. The run status stays unchanged.

The thread stays available after a stop. The next message starts a new execution with the history intact.

- threadId (string), required

  The unique thread identifier (UUID)

* status (string), required

  Always `stopped`

- message (string), required

  A fixed description: `Thread execution stopped`

```bash cURL
curl -X POST https://your-worker.workers.dev/api/threads/550e8400-e29b-41d4-a716-446655440000/stop \
  -H "Authorization: Bearer $STANDARD_AGENTS_API_KEY"
```

```typescript JavaScript
const response = await fetch(
  'https://your-worker.workers.dev/api/threads/550e8400-e29b-41d4-a716-446655440000/stop',
  { method: 'POST', headers: { Authorization: `Bearer ${token}` } }
);
const result = await response.json();
```

```typescript Client SDK
import { AgentBuilderClient } from '@standardagents/client';

const client = new AgentBuilderClient(
  'https://your-worker.workers.dev/api',
  (input, init) => {
    const headers = new Headers(init?.headers);
    headers.set('Authorization', `Bearer ${token}`);
    return fetch(input, { ...init, headers });
  },
);
await client.stopExecution('550e8400-e29b-41d4-a716-446655440000');
```

```json 200
{
  "status": "stopped",
  "message": "Thread execution stopped"
}
```

```json 404
{
  "error": {
    "code": "not_found",
    "message": "Thread not found: 550e8400-e29b-41d4-a716-446655440000"
  },
  "requestId": "0b3c1f0e-7f0a-4a55-9c58-2f6f5a0f6f0e"
}
```