DAG runner idle timeout kills tasks during an in-progress SDK reconnect #59

Description

sdk/dag-task-runner (and the copied skill at .cursor/skills/dag-task-runner) wraps run.stream() with withTimeout(..., streamIdleTimeoutMs). The default idle window is 5 minutes. If no stream event arrives in that window, the task is marked ERROR as a stalled model.

Headless @cursor/sdk local runs keep enableAgentRetries: true by default. When the transport stalls, the SDK retries internally and emits nothing on the public stream. The runner cannot tell model silence from that reconnect, so it cancels a live retry and the canvas shows a dead task.

The same guard exists in both copies of run_dag.ts:

https://github.com/cursor/cookbook/blob/main/sdk/dag-task-runner/src/run_dag.ts#L363-L375

const timeoutForNext = Math.min(deadline - Date.now(), streamIdleTimeoutMs);
if (timeoutForNext <= 0) {
  throw new TimeoutError(`Task ${task.id} exceeded deadline of ${formatMs(taskTimeoutMs)}`);
}
const next = await withTimeout(
  iterator.next(),
  timeoutForNext,
  streamWaitTimeoutMessage({
    taskId: task.id,
    timeoutMs: timeoutForNext,
    streamIdleTimeoutMs,
  }),
);

Expected

While the SDK is reconnecting, the idle clock should pause. Idle should fire only on real model silence.

Suggested fix

Subscribe to a reconnect/retry signal (onConnectionStateChange / RETRYING) and skip the idle timer while reconnecting. Until @cursor/sdk forwards that hook, wire the runner to the helper in sdk/reconnect-signal (or an equivalent) so transport retries are not logged as task failures.

Related

• Export a public reconnect/retry signal on the TypeScript SDK #57