Module schedule 

Schedules: runs started on a cron expression or a fixed interval.

A schedule is itself a Fusee workflow (type SCHEDULE_TYPE, ID fusee.schedule/<name>) built on durable timers, so there is no separate scheduler and schedules survive crashes like any workflow. Each run it starts has the workflow ID <name>@<scheduled time> (UTC, RFC 3339) and attaches to a run that already has that ID, so one scheduled time never fires twice, not even after a crash or a backfill over the same range.

• Overlap rules: skip a time while the previous run is still running, buffer-one (run it when the previous one finishes; at most one waits), allow-all, or cancel-other (cancel the running one, then start).
• Jitter: each start is delayed by a recorded random amount below jitter_ms.
• Catch-up: after downtime, missed times within catchup_window_ms still start (subject to the overlap rule); older ones are skipped.
• Pause and resume; backfill(from, to) starts every scheduled time in a past range; trigger starts one now.

The schedule workflow continues as new every 50 actions, so its journal stays small however long it runs.

Structs

Cron

A parsed five-field cron expression.

FiredSpan

An exact arithmetic progression. Regular schedules retain one span even after millions of firings. Irregular firings can add further spans.

ScheduleSpec

When a schedule fires and what it starts.

ScheduleState

A schedule’s state; also its input after continuing as new.

Enums

Command

A command sent to a schedule on CONTROL.

Overlap

What to do with a scheduled time while the previous run still runs.

Constants

CONTROL

The signal schedules take commands on.

SCHEDULE_TYPE

The built-in workflow type that runs schedules.

Functions

format_time

2026-11-09T02:00:00Z, with milliseconds when the time has them (2026-11-09T02:00:00.250Z).

is_builtin

The built-in workflow types: schedules, debounce and batch coordinators. Journal sampling (fusee export --sample) leaves them out.

register_builtins

Registers the built-in workflows.

run_id

The workflow ID of the run a schedule starts for scheduled time ms.

schedule_id

The workflow ID of a schedule.