docs(objectql): name the row whose value actually survives the divergence blind spot

The new module's "What is NOT covered" paragraph said the residue applies "the
first row's value to every matched row", and the residue pin's own title said
"row 1's value". Both are contradicted by the assertions directly beneath them:
per-row rewrites accumulate onto ONE payload in dispatch order, so the LAST
assignment to a key is what the single SET clause carries. The pins already
measure it — `bulk-write-per-row-hooks.test.ts`'s D3 case reads
`['stamped-2','stamped-2']`, and the residue pin reads `low` on the row whose
own dispatch derived `high`.

Prose only; no behaviour, no assertion and no exported symbol changes. The
ruling's verbatim quotation is untouched — the correction is stated beside it,
naming what the ruling said and what the engine does, because a docblock that
names the wrong row sends the next author hunting for a per-row seam that does
not exist.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0112hMx9hjJ9BgB28X97DS68

Author: claude

packages/objectql/src/multi-update-hook-key-divergence.test.ts

@@ -333,7 +333,7 @@ describe('[#14099] a row-invariant rewrite is never refused, however its values
  * ──────────────────────────────────────────────────────────────────────────── */
 
 describe('[#14099] same key + per-row VALUES still passes — D3’s declared cost', () => {
-  it('a per-row derived value is NOT refused, and row 1’s value reaches every row', async () => {
+  it('a per-row derived value is NOT refused, and the LAST dispatch’s value reaches every row', async () => {
     // ⚠️ This is the ruling's named blind spot, pinned so it cannot change by
     // accident in either direction. It is filed as its own finding with a
     // measured instance; ⛔ it is NOT widened into this card, and ⛔ the fix is

packages/objectql/src/multi-update-hook-key-divergence.ts

@@ -60,11 +60,20 @@
  * ## What is NOT covered, named rather than hidden
  *
  * A hook that writes the SAME key on every row but with per-row VALUES (a
- * per-row derived priority, say) passes this test and still applies the first
- * row's value to every matched row. That is D3's cost by design; the ruling
- * carries it openly and points at the prescription below as the exit. This
- * module does not widen to cover it, and a future author reaching for a value
- * comparison to close it must re-read the two measurements above first.
+ * per-row derived priority, say) passes this test and still applies ONE row's
+ * value to every matched row. The ruling's own sentence says "the first row's
+ * value"; the engine's MEASURED behaviour is the LAST dispatch's, because the
+ * per-row rewrites accumulate onto one payload in dispatch order and the last
+ * assignment to a key is what the single `SET` clause carries. Pinned in both
+ * suites — `bulk-write-per-row-hooks.test.ts`'s D3 case reads
+ * `['stamped-2','stamped-2']`, and this module's own residue pin reads `low`
+ * on the row whose own dispatch derived `high`. Which row wins changes nothing
+ * about the ruling's verdict; it is corrected here because a docblock naming
+ * the wrong row sends the next author hunting for a per-row seam that does not
+ * exist. That is D3's cost by design; the ruling carries it openly and points
+ * at the prescription below as the exit. This module does not widen to cover
+ * it, and a future author reaching for a value comparison to close it must
+ * re-read the two measurements above first.
  *
  * ## Divergence is `union` minus `intersection`
  *