Why: Stamping the user message with the run id made the live bubble look settled, and the composer stayed on 发送 until the next reconcile.
Evidence: npx tsc -b passed. vitest 75, including hasSettledReply and mergeStartedRun. On a mock server the button became 停止/排队 within 250ms and the reply grew while the run was open.
Impact: Composer, live bubble, and agent tracker only. A stored user message no longer hides the stream. Reopening replays from resumeSeq when the server sends it.
Refs: Dev fix/live-run-visibility
Co-authored-by: Cursor <cursoragent@cursor.com>
