docs(tooling): record the fifth casing-gate recognizer, and who owns a runtime-limbed chain

scripts/check-dispatcher-error-vocabulary.mjs

@@ -89,7 +89,14 @@
  * is WHICH gate reports it. `check:error-code-casing` owns the lowercase
  * sweep, and every pattern it has needs a QUOTED lowercase literal beside
  * the token `code` — `code: 'x'`, `.code = 'x'`, `code === 'x'`,
- * `code?: 'x' | 'y'`. In those positions (`objlit`, `assign`) the
+ * `code?: 'x' | 'y'`, and [#10760] `code: parsed?.code || 'x'` /
+ * `.code = e?.code ?? 'x'` — the OUR-DEFAULT slot of a `||`/`??`
+ * fallback chain, that gate's `fallback` pattern. It still captures only
+ * a string literal, and a literal in our source is by construction the
+ * default WE author. That fifth one is a position this gate has NO shape
+ * for rather than one it hands over: an intervening expression leaves
+ * `objlit` and `assign` with no quote to match.
+ * In those positions (`objlit`, `assign`) the
  * delegation is real: that gate reads the same characters and carries the
  * D6/D6b/D6c discrimination — field-addressed catalogs, persisted audit
  * columns, diagnostics payloads, Zod's own issue codes — that decides which
@@ -126,6 +133,22 @@
  * Reduction is ALL-OR-NOTHING — a chain with one runtime limb reduces to
  * nothing rather than to its literal half, since half an expression's
  * values is a finding that is wrong in both directions at once.
+ * [#10762] WHO owns a runtime-limbed chain then depends on WHERE it sits,
+ * and the two answers differ — measured against both gates' recognizers,
+ * not inferred from either one's prose. At the STAMP SITE
+ * (`{ code: parsed?.code || 'lit' }`, `err.code = e?.code ?? 'lit'`) no
+ * reduction is involved at all: `objlit`/`assign` need the quote
+ * immediately, so this gate never had a shape there — and since #10760
+ * `check:error-code-casing`'s `fallback` pattern reads that literal, so
+ * the shape is DELEGATED, not dropped. That is the position the two live
+ * SSO codes in `register-sso-provider.ts` shipped through. In a LOCAL'S
+ * INITIALIZER (`const code = parsed?.code || 'lit'; err.code = code`) it
+ * is neither: the ALL-OR-NOTHING rule above declines it here, and that
+ * gate's `fallback` pattern anchors on `code:`/`code?:`/`.code =`, so a
+ * `const code =` is out of ITS reach too. That one is still owned by
+ * NOBODY — deliberately on this side, filed as #10897 for the other.
+ * Stated so the next reader does not re-derive the hole and close it in
+ * the wrong gate.
  * - A constant this gate cannot resolve is REPORTED as unresolved, never
  * dropped: a deriver that goes quietly blind is the same failure one layer
  * down. [#9223] A constant imported from a WORKSPACE package is resolved
@@ -801,7 +824,11 @@ export function deriveSites({ registered, files, readFile, packageDirs = new Map
  *
  * `check:error-code-casing` owns the lowercase sweep, and every pattern it
  * has requires a QUOTED lowercase literal sitting next to the token `code`:
- * `code: 'x'`, `.code = 'x'`, `code === 'x'`, `code?: 'x' | 'y'`. Where this
+ * `code: 'x'`, `.code = 'x'`, `code === 'x'`, `code?: 'x' | 'y'`, and
+ * [#10760] `code: parsed?.code || 'x'` / `.code = e?.code ?? 'x'`, the
+ * OUR-DEFAULT slot of a `||`/`??` fallback chain (that gate's `fallback`
+ * pattern; it still captures only a literal, which in our source is the
+ * default we author). Where this
  * gate finds a lowercase code in one of those same positions — `objlit`,
  * `assign` — the delegation is real: that gate sees the identical text, and
  * it carries the D6/D6b/D6c discrimination (field-addressed catalogs,