026: A restored box enrols once it answers

Status: accepted, 1 October 2026. Partly supersedes 025: when a restored box that did not answer enrols.

Context

Under 025 a restored box enrols only if, at the restore, its guest runs and its command transport answers. A box restored stopped, or whose guest did not answer, kept enrolment off. bb-box could not tell it from a box whose machine was removed in BB, which must stay removed. So the thread could not use it as a machine, and if BB still had its machine, the box’s release did not remove it.

When the sweep releases the guest of an ended thread whose record was lost, nothing removes that box’s machine either. bb-box made it with the box ID as the key, but BB 0.44 gives a plugin no way to find a machine by its key:

• a machine does not show its key, and hosts.list and hosts.get cannot look one up by it
• hosts.experimental_create with the key makes a new machine when BB has none, as after someone removed it

Decision

• The sweep marks each record it restores with restoredAt, the time of the restore. The mark stays until the box starts enrolling.
• A marked box enrols with its box ID as the key when bb-box starts it, or when a sweep finds it ready and its command transport answering. The sweep then clears the error the restore gave a guest that did not answer. The enrolment is timed from then, and the log says “after bb-box found the restored box answering”.
• Only the mark lets a box enrol other than after its acquire. A box whose machine was removed in BB has enrolment off and no mark, so it stays off.
• While enrol-boxes is off, the sweep does not check marked boxes.
• When the sweep releases a guest of an ended thread whose record was lost, the box’s machine stays in BB until BB can find a machine by its key (request 6). Such guests follow only lost plugin storage, which upgrades no longer cause (019).

Consequences

• A restored box whose kind can enrol becomes a BB machine again once it runs and answers, and its release then removes the machine.
• A restored box released before it enrols again leaves its machine in BB, if BB still has it.
• box_status says when a box is waiting to enrol again after a restore.
• A machine that was removed in BB is made again only for a box restored after the removal, as under 025.