One unit of scheduled work a workflow declares, in AshWorkflow's own terms.

This is the vocabulary a scheduler implementation is handed. It deliberately says nothing about Oban: no trigger, no worker, no cron. An automatic step and a timeout both reduce to the same shape — run this action on the records that match, at or after this instant — and the two fields that differ are what let opposite scheduling strategies both be correct.

match and deadline are the same fact, twice

match is an Ash expression selecting records eligible now. A scheduler that discovers work by asking the data layer uses this, and needs nothing else. It is the whole reason a polling implementation does not have to understand timeouts.

deadline is the rule for computing the exact instant a given record becomes eligible. A scheduler that registers deadlines ahead of time uses this, and can arm a timer to the microsecond.

It has two shapes, because a timeout declares its deadline in two ways. %{field: :state_entered_at, fire_after: {3, :days}} means the instant is that field plus that duration, which is fire_after in the DSL. A fire_after of nil means the field holds the instant itself and no arithmetic applies, which is fire_at in the DSL. AshWorkflow.Scheduler.due_at/2 resolves both to a DateTime, so an implementation that only arms timers never has to match on the shape.

A step has no deadline — it is eligible as soon as a record occupies it. A timeout has both, and they agree: match is true exactly when deadline has passed.

step and timeout name where the work came from. An implementation that derives durable module or job names from them must keep deriving them the same way, since a change orphans whatever is already enqueued.

Identity

name is stable across compilations and unique within a resource, so a scheduler may use it as a durable key — a job's unique constraint, a row in its own table, a registry entry. Renaming a step or timeout changes it, which is the same breaking change it already is for the generated action names.

retry

retry is the failure policy for this work: how many attempts and how long between them. It is always present, defaulting to %AshWorkflow.Entities.Retry{}, one attempt and no retry, so a scheduler implementation can read work.retry.max_attempts without a nil check.

until

Only set for an every that bounds itself. match already folds the bound in — checked against state_entered_at, not against deadline's own field — so an implementation that reads match needs nothing else. until is exposed on Work for one that wants to filter ahead of a full match evaluation, the way AshWorkflow.Scheduler.Precise.Timeline's recovery sweep does.