A request is the build's record under the id its outcome will carry, in state asked; the outcome takes its place and keeps the request beside it, so assign, the pending assignments and the planner read the builds bucket alone. The bucket removes no key, so a request past thirty days is not listed instead of deleted. The move folds build_request into the same records (one kind, builds, counted against both tables) and marks the requests never handed over to be asked again once: claimed before it is asked and settled after, so a crash loses the ask rather than making it twice. Also tests the chain buckets' options on a real bus, the assignments' mirror options included.
Once chain_moved records the kind, RecordBuild and every build read go through the chain (reuse key and published added); before that the tables are read as before. The serving controller copies the rows at its start, holding the lease: idempotent per key, rows counted against keys, the largest value measured, a refusal (urgent condition, nothing switched) on a count that differs or a value over the bus's largest, and a re-read when the table took a row meanwhile. ForTest attaches the chain in memory with builds moved; ForTestBefore leaves it unmoved. Build requests, gates and the other kinds are still in their tables.
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