Cancel Turn

Cancel the currently executing turn in a session

POST /v1/sessions//cancel

Cancels the currently executing turn in a session. This stops the workflow execution and emits appropriate events.

Path Parameters

session_id · string · required

The ID of the session to cancel. Must be a valid session ID with the session_ prefix.

Request Body

No request body required.

Response

Returns 200 OK on success.

Error Responses

• 400 Bad Request - Session is not currently active (no turn to cancel)
• 404 Not Found - Session does not exist or is not accessible
• 401 Unauthorized - Missing or invalid authentication

Events Emitted

When a turn is successfully cancelled, the following events are emitted in order:

1. turn.cancelled - Emitted immediately when cancel is requested
2. input.message - User message: “User requested to cancel the work.”
3. output.message.completed - Agent message: “Work was cancelled by user.” (emitted by worker when it stops)
4. session.idled - Emitted when the session transitions to idle (emitted by worker)

The user message is emitted immediately by the API, while the agent message and session.idled events are emitted by the worker after it detects the cancellation and stops execution. This ensures the agent message appears after any in-flight events.

Example

curl -X POST https://api.everruns.com/v1/sessions/session_01234567-89ab-cdef-0123-456789abcdef/cancel \
  -H "Authorization: Bearer YOUR_API_KEY"

Use Cases

• Stop a long-running task that’s no longer needed
• Interrupt an agent that’s stuck or taking too long
• Cancel execution before it completes naturally

Notes

• This endpoint only works when the session status is active
• Calling cancel on an idle session returns 400 Bad Request
• The cancellation is graceful: in-flight events are processed before stopping
• After cancellation, the session returns to idle status and can accept new messages