Persistence

The library does not ship a store. Restore first, then create the query. dispose() completes snapshots$ after the current source notification. It does not flush external storage, and it does not delete consumer-owned data.

Ordering writes is optional RxJS. An async function passed to subscribe does not order writes: the next notification can arrive before that function’s promise settles. Write errors, and writes still running after dispose, belong to that consumer stream.

import { concatMap } from 'rxjs';

const restored = await readSnapshot(key);
const query = client.query({
  key,
  initialSnapshot: restored,
  queryFn: ({ signal }) => load(signal),
});

query.snapshots$.pipe(concatMap((snapshot) => writeSnapshot(key, snapshot))).subscribe({
  error: reportWriteFailure,
});

initialSnapshot is replayed on snapshots$ with its original receivedAt. The next accepted success replaces both the data and the timestamp, even when the payload is equal.

state(), state$, and snapshots$ copy the envelope and { data, receivedAt }. They do not clone data. A Date, a Map, or any other payload value is the same reference the source returned. Treat it as read-only.

There is no combined-query type. Combine views in your code:

import { combineLatest } from 'rxjs';

combineLatest([
  prices.select((state) => state.snapshot?.data),
  fx.select((state) => state.snapshot?.data),
]).subscribe(renderPair);