A blob could vanish after a 200 three ways: a record naming a collected blob was stored anyway and its image 404'd forever, a re-upload of a held blob did not restart its grace so the next sweep took it, and the collector unlinked bytes outside the lock an upload holds. The write is refused now, a re-upload of an unreferenced blob restarts the clock, and collection and upload of one CID exclude each other. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Change-Id: Id88af69bd7ebd55e8fa1f8be7c02bc88cce04c43