docs: RELEASES.md entry for 8.2.6 (write/index-spine hardening)

Consumer-facing summary of the Pass-1 durability + integrity release: durable
blob-write honesty, single-op history durability (PendingFlushDurabilityError),
degraded-index surfacing, full-footprint clear(), count symmetry, and loud
index-maintenance / aggregation failures. loadBinaryBlob fault-propagation is
held for the native lockstep and deliberately omitted here.

RELEASES.md

@@ -10,6 +10,53 @@ Full auto-generated changelog: `CHANGELOG.md` · Releases: https://github.com/so
 
 ---
 
+## v8.2.6 — 2026-07-13 (write/index-spine hardening — loud errors, never quiet losses)
+
+Durability + integrity hardening across the write and index paths. Every fix converts a place that
+could *silently* lose data, serve a partial result, or acknowledge a write that did not land into a
+loud, observable failure. No breaking API changes; one new exported error.
+
+- **A durable blob write that stored nothing is no longer acknowledged.** The atomic blob write
+  (`saveBinaryBlob`, used for vector/graph index segments and the native index files) uses a unique
+  per-writer temp file, so a rename `ENOENT` can only mean *our* temp vanished before the rename —
+  the bytes never landed. It previously returned success on that path; it now retries once with a
+  fresh temp and, if the temp vanishes again, throws instead of acknowledging a write that persisted
+  nothing. A downstream deployment that mmaps these files no longer finds a "successfully written"
+  blob missing on the next open.
+
+- **Single-op history durability is enforced, not assumed.** The asynchronous group-commit flush
+  that persists single-op generation history previously swallowed a persist failure as a warning
+  while writes kept succeeding and their history piled up, undurable, in memory. It now tolerates a
+  transient blip (retry with capped backoff) and, after repeated failures, **refuses further writes**
+  with the new **`PendingFlushDurabilityError`** rather than promise a durability it cannot deliver.
+  Live canonical data is untouched; the latch self-heals the moment a flush succeeds. Callers needing
+  hard per-write durability should keep using `transact()` (or `flush()` after a single-op).
+
+- **A degraded derived index is surfaced on reads, not served silently.** When a non-fatal index
+  rebuild fails at open, or a write commits via adopt-forward recovery with an incomplete derived
+  index, `find()` and `get()` now emit one loud warning per degraded window (reads still return —
+  canonical is the source of truth), the state folds into `checkHealth()` /
+  `validateIndexConsistency()`, and `repairIndex()` reconciles and clears it.
+
+- **`clear()` removes the full derived footprint.** It previously left raw index blobs, the native
+  id-mapper, and column-index manifests on disk, so a cleared brain could re-read stale native state
+  on reopen. It now wipes them together as a set.
+
+- **Counts stay honest across deletes.** A delete decremented the per-type breakdown but not the
+  scalar total, so the total inflated permanently (and won pagination). Delete now decrements both;
+  the invariant `total === Σ per-type` holds across any interleaving of add / visibility-flip /
+  delete and across a reopen.
+
+- **Index-maintenance and aggregation failures are loud.** A partial LSM/segment load no longer
+  publishes the manifest's full count as if healthy; an HNSW flush that can't persist a node throws
+  (`HnswFlushError`) instead of returning a lying count and dropping the node; a corrupt or missing
+  manifest-listed column segment throws (`ColumnSegmentLoadError`) instead of silently dropping its
+  entities from every query; and aggregation materialization / state-load failures now warn instead
+  of vanishing into an empty catch.
+
+New export: **`PendingFlushDurabilityError`** (with `.cause` and `.failedAttempts`). No other public
+API change. Each fix ships with a dedicated regression test.
+
 ## v8.2.5 — 2026-07-12 (honest response when a transaction rollback can't complete)
 
 Data-integrity fix. When a transaction failed and its rollback then *also* failed to undo a