Store

JourneyStore (src/core/store.ts) holds the latest immutable snapshot and distributes it. It has two jobs:

1. Hold the latest snapshot and notify selector listeners when their selected value changes.
2. Deliver named lifecycle payloads (stepEnter, stepLeave, statusChange, contextChange, navigationBlocked, error) to listeners for that event.

The store never derives state itself. Snapshots are rebuilt by the runtime; the store only publishes them.

Notification

subscribe(listener) registers a plain per-commit callback. Publishing replaces the snapshot and calls every listener; a publish whose snapshot is reference-equal to the current one is skipped entirely, because structural sharing upstream returns the previous object verbatim when nothing changed.

The store holds no selectors and no equality functions. Deriving a slice and suppressing unchanged values is a rendering concern, and it needs to know which renders committed — so it lives in the framework binding (useSelector in @rxova/journey-react), not here.

Listener isolation

Listener failures are caught per listener, so one subscriber cannot interrupt the runtime, the publish loop, or other subscribers. A throwing listener is reported and the loop continues.

Isolation is unconditional. What you can configure is where the report goes: the onListenerError creation option receives the thrown value. Without it, the store reports through console.error. If the configured reporter itself throws, the store falls back to the default console.error report — a broken reporter can never re-enter the runtime.

const machine = createLinearJourney(definition, {
  onListenerError: (error) => errorTracker.capture(error)
});

Disposal

Disposing the machine drops every selector and event subscription. Later subscribe* calls return a no-op unsubscribe.

Where to next

• Runtime
• Machine surface
• Lifecycle and events