Every static task and runtime task instance begins as pending. Runtime events move tasks through a constrained lifecycle.

Status meanings

Status Meaning
pending The runtime has not accepted the task start
active The task started and has not terminated
completed The task reached its end and completion effects succeeded
failed A start or completion operation failed
skipped The when condition was false at the scheduled start
blocked A dependency, requirement, invariant, timing rule, performer, or reservation prevented the start
interrupted An active task's while condition failed
cancelled A declared runtime cancellation rule cancelled pending work

completed, failed, skipped, blocked, interrupted, and cancelled are terminal states.

Allowed transitions

The runtime permits these transitions:

  • pending to active, failed, skipped, blocked, or cancelled;
  • active to completed, failed, or interrupted.

An invalid transition reports task.lifecycle.transition.invalid.

Failure propagation

A failed start Change prevents activation. A failed completion Change produces failed, not completed.

Dependencies require completed predecessor work. If a dependency cannot satisfy the scheduled start, the dependent task becomes blocked.

An active task interruption releases its reservations and restores its temporary effects. Tasks can use authored continuation relationships after interruption.

Finite horizons

A horizon can leave future tasks pending and crossing tasks active. Those statuses do not indicate a runtime failure.

See requested horizons before interpreting status in a partial run.