docs: RELEASES.md entry for 8.4.0 (generation fact log + family stamp)

RELEASES.md

@@ -10,6 +10,41 @@ Full auto-generated changelog: `CHANGELOG.md` · Releases: https://github.com/so
 
 ---
 
+## v8.4.0 — 2026-07-15 (the generation fact log — a sequential, self-verifying commit stream)
+
+A minor release, fully backward-compatible (all additions; no behavior change for existing APIs).
+This is infrastructure: it changes nothing about how you query today, and lays the substrate that
+makes index heals and incremental catch-up sequential-read problems instead of directory walks.
+
+- **Every committed write now also appends a "fact" — an after-image commit record.** Alongside the
+  existing before-image history, each committed generation (single-op and `transact()` alike) appends
+  what each touched entity/relationship *became* — or a body-less tombstone for a removal — to an
+  append-only, checksummed segment log under `_generations/facts/`. Crash-safe by construction: a
+  torn tail is detected and ignored; on open the log is reconciled to committed truth, so an absent
+  generation always means "never committed." `transact()` facts are durable when `transact()`
+  returns; single-op facts ride the same group-commit flush as their history.
+
+- **New: `brain.scanFacts()`** — stream committed facts in commit order, in batches, with heal-grade
+  telemetry (total scope up front; per-batch generation range, byte size, and segment; a summary
+  cross-check at the end; loud abort on any gap — never a silent skip). **`brain.factSegmentPaths()`**
+  hands zero-copy consumers the immutable sealed segment files directly. New exported types:
+  `CommitFact`, `FactOp`, `FactScanBatch`, `FactScanHandle`. Facts accumulate from the first write
+  after upgrading — pre-existing history is not retroactively converted (enumeration remains the
+  fallback for old data).
+
+- **New: the entity-tree family stamp.** At every flush/close, brainy stamps which committed
+  generation the canonical entity files reflect plus the rollup invariants (entity/relationship
+  counts) that verify the tree whole. At open, coherence is a comparison — a genuine divergence is
+  loud and names the failing invariant; `repairIndex()` recounts from canonical and re-stamps. New
+  exports: `readFamilyStamp`, `verifyFamilyStamp`, `ENTITY_TREE_STAMP_PATH`, `FamilyStamp` types.
+
+- **Storage adapters** gain optional binary raw-byte primitives (`appendRawBytes`, `readRawBytes`,
+  `writeRawBytes`, `rawByteSize`) — feature-detected; the filesystem and memory adapters implement
+  them; an adapter without them simply hosts no fact log. The fact-log namespace is registered as a
+  protected family: no sweeper or GC can delete under it.
+
+No API breaks. 24 new tests; the full commit-path regression suite is green.
+
 ## v8.3.3 — 2026-07-15 (rename moves the containment edge — no ghost in the old directory)
 
 One production-reported fix plus a repair path, completing the delete/move hygiene arc (8.3.1 fixed