Every background thought has a transcript, and the transcript has a URL

The parent session spawned three background subagents an hour ago: one reading the codebase, one checking the vendor docs, one "researching pricing." Two are back. The third is still going.

GET /api/v1/agent/sessions/{id}/tasks asks for the session's task snapshot; it arrives on the stream as event.tasks_snapshot. Task three, running, 47 minutes. GET .../tasks/{tid}/transcript and the transcript comes through as event.task_transcript. It has hit the same paywall nineteen times.

POST .../tasks/{tid}/cancel. The other two results stand; the parent keeps its turn. Background tasks outlive session.cancel and can't be restarted, so the transcript is the whole record of what that thought did with its hour.

Supervision used to mean reading the parent's summary of its children. Now you read the children.