[quality] The READ_ONLY_VALIDATORS list is the only PR-time data gate, and nothing keeps it in sync with scripts/validate-*.mjs

Read tests/validators-smoke.test.mjs and inspect the scripts/validate-*.mjs files; start by running the existing validator smoke test and the full test suite. Add tests/validator-smoke-coverage.test.mjs so the listed validators and read-only validator files match in both directions, then verify the clean suite and the new-validator failure case.

Finding

tests/validators-smoke.test.mjs holds a hand-maintained array of validator
filenames:

const READ_ONLY_VALIDATORS = [
  'validate-metrics.mjs',
  'validate-awards.mjs',
  'validate-architectures.mjs',
  'validate-architecture-assets.mjs',
  'validate-button-contrast.mjs',
];

Nothing keeps that list in sync with scripts/validate-*.mjs, and the list is
far more load-bearing than a unit-test fixture normally is.

It is the only thing that gates data integrity on a pull request.

.github/workflows/ci.yml is the sole pull_request-triggered workflow. Its
steps are npm ci, npm run test:unit, npm run build:production — it never
invokes npm run validate:*. The four data validators run directly only in
deploy-gh-pages.yml (trigger: push to main) and import-architectures.yml
(trigger: schedule). Both are post-merge.

So the validators reach the PR gate exclusively via
validators-smoke.test.mjs, which executes each listed script against the real
repository data.

Verified at 00b44df (node v26.8.1)

Mutating data/awards.json to give the first entry an http:// announcement
URL and running node --test:

✖ validate-awards.mjs passes against current repo data
  stderr: '\n1 error(s) in awards:\n  [error] 2026/sncf: announcementUrl must be https\n'

The unit suite catches it — but only because validate-awards.mjs happens to
appear in that array. A validator added to scripts/ and forgotten in the
array runs on no pull request. Its first failure lands post-merge on the
push-to-main deploy, where it blocks deployment of an already-merged change,
and the author who introduced the break is no longer in the loop.

Why existing gates miss it

• The array is a literal list of strings. Adding scripts/validate-foo.mjs
  leaves all 55 existing tests green.
• docusaurus build does not model the test runner's inputs.
• PR #278 (tests/workflow-scripts.test.mjs, open) asserts that npm run
  targets named in workflows and package.json resolve to defined scripts and
  existing files. It does not read validators-smoke.test.mjs and does not
  model which validators actually execute on a pull request.
• PR #301 (tests/ci-supply-chain.test.mjs, open) covers action pinning and
  token permissions, not step composition.
• PR #225 (tests/tools/coverage-report.mjs, open) changes how coverage is
  reported for fixture-sandbox runs; it does not touch the smoke list.
• No open PR touches tests/validators-smoke.test.mjs.

Recommendation

• Add tests/validator-smoke-coverage.test.mjs, which parses the
  READ_ONLY_VALIDATORS literal out of tests/validators-smoke.test.mjs
  and asserts, in both directions, that it matches the read-only
  scripts/validate-*.mjs files on disk.

"Read-only" is detected from the script source rather than hard-coded, so the
guard does not go stale when a validator gains a write mode.
validate-architecture-assets.mjs has a --fix path and is therefore not
required to be listed, though it is listed today and that stays valid.

Verified: green on a clean checkout (4/4 pass, full suite 59/59), and dropping
a read-only scripts/validate-foo.mjs into the tree fails it with
actual: [ 'validate-foo.mjs' ]. Already prettier --check clean.

This is test-only — no production file changes.

Priority

• Impact: medium
• Effort: low

Filed by quality agent (hold-gated mode)

— hive: agent=quality backend=copilot model=claude-opus-5