docs: RELEASES.md entry for 8.1.0 (brain.onChange change feed)

RELEASES.md

@@ -10,6 +10,38 @@ Full auto-generated changelog: `CHANGELOG.md` · Releases: https://github.com/so
 
 ---
 
+## v8.1.0 — 2026-07-10 (`brain.onChange` — the in-process change feed)
+
+New public API: subscribe to every committed mutation with
+`brain.onChange(cb) → unsubscribe`. One event per affected record, for **every**
+canonical write regardless of origin — direct calls, batch methods, `transact()`,
+imports, and Virtual Filesystem writes all funnel through the same commit point the
+feed is emitted from. This is the authoritative in-process signal for live UIs,
+cache invalidation, and realtime sync layers (downstream SDKs can forward it over
+their own transports to make local and remote brains uniform).
+
+Event shape (`BrainyChangeEvent`, exported): `kind` (`entity`/`relation`/`store`),
+`op` (`add`/`update`/`remove`/`relate`/`unrelate`/`updateRelation`/`clear`/`restore`),
+the post-commit `entity` or `relation` view (type + full custom metadata), the
+committed `generation`, and `timestamp`. Notable properties:
+
+- **Post-commit only** — an aborted write (a losing `ifRev` CAS, a rejected
+  transaction) never emits. If you got the event, the write is durable.
+- **Deletes fully described** — `remove`/`unrelate` carry the record's last
+  committed state (from the commit's own history record), not just an id; batch
+  deletes included.
+- **Batches emit per item**; a `transact()` batch's events share its single
+  generation. Entity deletes also emit `unrelate` for each cascaded relationship.
+- **Commit-ordered, asynchronous, isolated** — events arrive in commit order,
+  dispatched in a microtask so a slow listener never delays a write and a throwing
+  listener never affects the write or other listeners. Zero overhead with no
+  subscribers.
+- **`kind: 'store'`** events for `clear()`/`restore()` mean "refetch everything".
+- Fire-and-forget by design; each event's `generation` composes with
+  `asOf()`/`transactionLog()` for catch-up after a gap.
+
+Guide: `docs/guides/reacting-to-changes.md`. No behavior changes for existing code.
+
 ## v8.0.17 — 2026-07-08 (count recovery scans the real layout · ~1,100 lines of dead 7.x machinery removed)
 
 A cleanup of the vestigial 7.x "hnsw sharding" machinery that turned up two real fixes.