A Shift lets Owl work on an Account while the machine is in use

• Amends: ADR-0011’s manual override clause

Context

Owl works while the machine is Idle (ADR-0011). That turned out to leave queued work waiting through whole afternoons at a desk, when the machine had room for it and the person at it wanted it done.

ADR-0011 did name a manual override, owl start, but it starts one Run for the Job at the head of the queue and nothing after it. There is no way to say “keep working on this Account for the next two hours”, and the Idle watcher freezes the Runs it started as soon as anyone touches the keyboard.

Decision

A Shift is a bounded period during which Owl starts Runs on one Account whether or not the machine is Idle. At most one Shift is on per Account.

Starting and ending

owl shift start|stop|status. start covers every Account unless given -a/--account, and takes:

A Shift is always time-bound. --until-empty combines with --for rather than replacing it, so a queue of a thousand Jobs does not become a Shift with no end. Without --until-empty, an empty queue leaves the Shift on and waiting for work, and the desktop app says so: queue empty, time left.

Empty means the Account has no pending and no active Jobs. A Job held back by the Ceiling or a cap is pending, and a Run still going may yet put its Job back in the queue, so neither is empty. blocked, exhausted, review, done and cancelled do not count: none runs again without a person.

Starting a Shift on an Account that has one extends it. Its end moves to the later of the two, and nothing else changes. --replace replaces it outright, which is how one is shortened or given other flags.

When a Shift ends, its Runs are let finish. Its end is a limit on starting Runs, not a deadline for them. That holds whether it ran out of time, found its queue empty, or was ended by owl shift stop.

While a Shift is on

• Returning to the machine freezes nothing on that Account, whoever started the Run. A Run the Idle watcher started at 02:00 is covered by a Shift started at 09:00, and a Run a Shift covered is let finish after it ends rather than frozen.
• The Ceiling applies (ADR-0020). A Shift at its Ceiling starts nothing and says until when, and starts work after the reset if it has time left.
• Caps apply (ADR-0021). A Shift permits work; it does not widen it.
• Power is ignored unless --require-power was given.

The one-off verbs

owl start, pause, resume and stop keep acting on Runs, and take no Shift flags:

• owl start starts one Run for the Job at the head of the queue, as before.
• owl pause freezes every Run in flight and holds every Shift until owl resume. A held Shift starts nothing and its clock keeps running. Without the hold, frozen Runs that outlast the grace window end, free their slots, and the Shift starts the next Job in the middle of whatever the pause was for.
• owl stop [account] ends Runs in flight: they carry on for up to the grace window, then are signalled as ADR-0034 describes. --force signals them at once. Shifts are left on, so the next Job starts; --end-shift ends them too.

Persistence

A Shift and the pause hold are stored in the database, the Shift with an absolute end. Both survive a daemon restart. A Shift whose end passed while the daemon was down is over.

Consequences

• A one-hour Shift can keep the machine busy for noticeably longer than an hour, because its Runs finish. owl shift status and the desktop app have to say “Shift ended, 1 Run finishing”, or it looks like the end was ignored.
• owl stop during a Shift stops this work, not work. That is deliberate and needs saying in its help: owl pause and --end-shift are how the machine is given back.
• A pause now outlives its grace window and a restart. A person who pauses and forgets finds nothing done until they resume, which owl status must make obvious.
• ADR-0011’s freeze-on-return now asks whose Account a Run is on before it freezes it.
• Shift schedules, which start Shifts on a timetable, build on this: a Shift is already stored, bounded and started by something other than Idle. They are a separate decision.
• There is no way past the Ceiling. A deliberate, one-off boost is left for its own decision.

Alternatives considered

Stop or freeze Runs at the Shift’s end. An exact end, at the cost of a Run’s tail and a TTL attempt (ADR-0025), or of freezing an Agent the person just watched working. Rejected: the person is present and asked for the work.

Default to until-empty. The natural end of “do my queue”, and unbounded when the queue is long. Rejected for a time bound that is always there.

Replace a Shift already on. The latest command as the latest intent. Kept behind --replace, because a second owl shift start that shortens a Shift is a surprise and one that extends it is not.

Pause freezes Runs only, leaving Shifts alone. Simpler, and a pause then lasts only as long as the grace window.

Shifts held in memory. Simpler, and an upgrade in the middle of an afternoon Shift ends it without a word.

Shift flags on owl start. One verb family for everything, and a one-off start that is suddenly a period of work. Rejected: owl start means one Job.