Cancel a session - HarnessRouter Docs | HarnessRouter

Request

Cancel

POST /v1/sessions/{session_id}/cancel

Product UI

• Show cancel only while a task is running or starting.
• Verify ownership before sending the cancel request.
• After cancel, stop app-side progress rendering and refresh session status.

Open standard

Explicit POST /v1/sessions/{session_id}/cancel matches UHP's cancellation rules: the server must stop promptly, retain output already produced, and leave the session continuable. See cancellation in the Unified Harness Protocol's Sessions chapter.