releaseHandedBack: a drain retry of a failed hand-back release that succeeds is not written back to the run record, so the run's last reservation entry stays reservation_release_failed (saying the reservation lapses with its lease) although it was released, and any later releaseHandedBack over the run, finding no reservation_released entry, pushes the release again: idempotent, but it costs a fetch.

releaseHandedBack: a drain retry of a failed hand-back release that succeeds is not written back to the run record, so the run's last reservation entry stays reservation_release_failed (saying the reservation lapses with its lease) although it was released, and any later releaseHandedBack over the run, finding no reservation_released entry, pushes the release again: idempotent, but it costs a fetch.

Grounds

• pursued: after the drain's retry releases the reservation, the run's last reservation entry is reservation_released and a further releaseHandedBack makes no claim call (TestADrainRetryThatReleasesIsLoggedOnTheRun); a run record still ending in reservation_release_failed after a successful retry, or a second claim push, would show it wrong.