The mirror refresh re-ingested inside its row lock, and that ingest's commit let go of the lock
before the replace: a remove made then was undone and the list read as synced. Push, re-pull and a
delete touched items before the list row, a deadlock beside the playlist-first route edits. A push
now re-plans from the items under the lock and derives dirty after its YouTube writes.
lock_playlists moves to the sync package. Tests pin both ids of a move's lock and the claim's
own connection.
peter
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