Chess: a status poll that landed between the claim and the match id write
deleted the claim, so the waiting player searched forever while the other
sat alone. A claim in progress is now left alone for 3 minutes, dequeue
reports it, a failed match insert releases it, and a waiting player's
status poll claims an older waiting row. Domino gets the same status-side
match. Raced 4/4 (chess) and 3/3 (domino) with simultaneous queue calls.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>