Merged as a reduced diff, and worth recording why.
The two-arm `ALWAYS_PROTECTED` read this PR proposed had already landed in #12605 while this branch was open — the tip carries `coveredByAlwaysProtected()` with both arms and the new error wording. I ran the gate on the current tip to be sure: `PASS — all security tier annotations match routeGuard.ts`. Merging the whole branch would have reintroduced the same logic under a different comment.
What was genuinely missing, and is what merged:
- **`tests/unit/openapi-security-tiers-gate.test.ts`** — executes the real gate and asserts exit 0 with no "NOT covered" line. #12605 fixed the defect but left no guard, so the LOCAL_ONLY-arm bug (#12350) could reappear on the ALWAYS_PROTECTED arm exactly as it did the first time. 1/1 green.
- **The parse guard** — `ALWAYS_PROTECTED_PATTERNS.length === 0` now fails the constant-parse check with its own count in the message. Without it, a regex array that stops parsing degrades into "every pattern-covered route is an annotation mismatch" instead of saying so.
A note for the record: my first read of this PR was wrong. I ran the gate in the main checkout, which was 11 commits behind `origin/release/v3.8.51`, saw the pre-#12605 failure, and classified this as fixing a live red. It was not — the checkout was stale. Corrected before anything was merged.
ec4f951e39