The schedule — Airwave

How a channel's filter/ordering recipe becomes a materialized, deterministic timeline — the initial windowed build, generate/extend, and the jobs that grow and heal it.

A channel's filter/ordering is only the recipe; the schedule is the materialized timeline the guide and players actually read — rows in ScheduleItem, each a program (or bumper) with a start time and duration.

On create, Airwave builds a windowed initial schedule inline (channels.create → generateChannelSchedule with windowSeconds = INITIAL_WINDOW_SECONDS, ~12h) so the channel is watchable immediately instead of waiting for a job — but capped, so a huge pool doesn't lay a 300-day pass up front. A build capped mid-pass records a resume cursor so later extensions continue from that exact item rather than replaying the top of the pool. If the inline build fails, the channel is simply left for the backfill job to pick up.

Generate schedule (on the channel page → Schedule card, channels.generateSchedule) does a full rebuild from now: at least one complete pass of the pool (every item scheduled), looping whole passes — each reshuffled for a Shuffle channel — until it covers a ~7-day floor. This replaces the timeline, so use it after you change the filter, ordering, or strategy. Extend (channels.extendSchedule) is the non-disruptive counterpart: it appends a fresh block at the tail and leaves what's on now untouched.

Growing and healing the schedule over time is handled by background jobs — see Background jobs:

Job	Cadence	Role
Schedule Backfill (`schedule-backfill`)	every 10 min	Builds the initial schedule for enabled channels that have none (in batches). Picks up freshly created/auto-generated channels.
Schedule Refresh (`schedule-refresh`)	hourly	For each enabled channel, appends at the tail only when the timeline is running low (`extendChannelSchedule`, ~2-day threshold). Continues mid-pass from the stored cursor.
Bumper Sync (`schedule-bumper-sync`)	every 10 min	Reconciles a schedule with the current bumper settings when the channel's mode/rev falls behind. Also kicked immediately when you save a channel's bumper mode.

Because the build is deterministic and seed-driven, all of these reproduce a consistent lineup: a rebuild, an extension, and a repair all lay the same items in the same order for a given seed.