0781 — A declined claim backs off in the pool, and live instances keep their poll rate

Context

[0779] picked rung 2: a tick that made no progress backs off toward ten times poll_rate. Built, it needed the pass to say “idle” through the tick runner’s seam, and every shape of that report was wrong: a bare bool that three passes had to fake, a disable knob for the schedule producer, a named error with a code and a docs page for a non-fault, or a flag the pass sets on its runner. The seam was wrong because the question was.

Two things were called idle. A live instance with nothing to do, such as a cursor advancer whose committed did not move, costs a statement or two a tick and honors a cadence its row declares. A manager whose reconcile re-claims rows another process holds costs a claim per row per tick and was 480 of the 814 losing claims a second in the 160-stream cell. Only the second is the problem, and the codebase already has its shape: a declined manager-row claim waits out RunnerConfig.RetryDelay, and every retry in the library climbs a common.RetryPolicy.

Decision

• The instance tick runner and every pass keep their shape; a live instance ticks at its row’s poll_rate, idle or not.
• The manager’s pool remembers each row whose claim was declined, with its decline streak and when the next attempt is due, and diff skips the row until then. A start clears the streak; a row gone from the table takes its streak with it.
• The delay is ManagerConfig.ClaimRetry, a common.RetryPolicy with base 1 s and cap 30 s, jittered by the manager’s JitterFraction. The cap bounds a takeover after a holder stops, so it stays near InstanceTTL; the base re-claims a row released mid-rolling-restart within a second or two.
• Supersedes [0779]‘s rung-2 clause; its other decisions stand.

Consequences

• A manager beside rows it cannot claim costs one declined read per row per 30 s instead of per second; its chain listing and two sweeps still run every second.
• A row’s holder that crashes is replaced within InstanceTTL plus up to 30 s, the same bound the manager row already had.
• Rejected: an idle report from the pass, in any of the four shapes above; a poll-rate backoff for live instances.