Streaming lifecycle

AgentsKit owns the lifecycle. AgentsKit Chat renderers expose the same ChatReturn operations without wrapping their semantics:

Operation	AgentsKit method	Default renderer interaction
Cancel	stop()	Stop button; Escape in Ink
Retry	retry()	Retry response; /retry in Ink
Edit	edit(messageId, content)	Edit last message; /edit <content> in Ink
Regenerate	regenerate(messageId?)	Regenerate response; /regenerate in Ink

Cancellation aborts the upstream source. AgentsKit prevents chunks arriving after the abort from mutating canonical state. The framework does not implement another abort flag or stream reducer.

Lineage and reconnect

A v1 server.turn.snapshot may include:

{
  "lineage": {
    "operation": "regenerate",
    "parentTurnId": "turn-previous",
    "sourceMessageId": "message-assistant"
  }
}

Use createSnapshotEvent(...) to project canonical AgentsKit messages plus submit/retry/edit/regenerate lineage. Use createTurnSnapshotCursor(sessionId) when applying snapshots received from a transport. The expected session is fixed before the first delivery; its first valid snapshot initializes reconnect state. Later snapshots must have a greater sequence. Duplicate, stale, malformed, and foreign-session events do nothing.

Snapshots remain complete projections. The cursor chooses the current projection; it never merges messages or interprets adapter chunks.