diff --git a/tests/validator-smoke-coverage.test.mjs b/tests/validator-smoke-coverage.test.mjs
new file mode 100644
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+++ b/tests/validator-smoke-coverage.test.mjs
@@ -0,0 +1,95 @@
+// Guards the contract between the read-only validators on disk
+// (scripts/validate-*.mjs) and the hand-maintained READ_ONLY_VALIDATORS list
+// in tests/validators-smoke.test.mjs.
+//
+// That list is load-bearing well beyond the unit suite. The only
+// pull_request-triggered workflow, .github/workflows/ci.yml, runs
+// `npm run test:unit` and `npm run build:production` — it never invokes
+// `npm run validate:*` directly. The four data validators reach the PR gate
+// solely because validators-smoke.test.mjs executes them against the real
+// repository data. A validator that is added to scripts/ but forgotten in
+// that array therefore never runs on any pull request; its first failure
+// surfaces post-merge, on the push-to-main deploy, where it blocks the
+// deployment of an already-merged change.
+//
+// Nothing else in the suite models that relationship: the array is a literal
+// list of strings, so adding scripts/validate-foo.mjs leaves every existing
+// test green.
+import assert from 'node:assert/strict';
+import { existsSync, readFileSync, readdirSync } from 'node:fs';
+import { join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import test from 'node:test';
+
+const repoRoot = fileURLToPath(new URL('..', import.meta.url));
+const scriptsDir = join(repoRoot, 'scripts');
+const smokeTestPath = join(repoRoot, 'tests', 'validators-smoke.test.mjs');
+
+const smokeSource = readFileSync(smokeTestPath, 'utf8');
+
+// Reads the READ_ONLY_VALIDATORS array literal out of the smoke test. Parsing
+// the source keeps this check honest: importing the module would execute the
+// validators a second time and would not expose the list.
+function smokeListedValidators() {
+  const match = smokeSource.match(
+    /READ_ONLY_VALIDATORS\s*=\s*\[([\s\S]*?)\]\s*;/,
+  );
+  assert.ok(
+    match,
+    'could not locate the READ_ONLY_VALIDATORS array in tests/validators-smoke.test.mjs',
+  );
+  return [...match[1].matchAll(/['"]([^'"]+)['"]/g)].map(([, name]) => name);
+}
+
+// Validators are read-only unless they clone a repository, call a network API
+// or write into the working tree. The smoke test deliberately excludes such
+// scripts, so the exclusion has to be detectable from the source rather than
+// hard-coded here, or this test would go stale the moment one changes.
+function isReadOnly(scriptName) {
+  const source = readFileSync(join(scriptsDir, scriptName), 'utf8');
+  return !/\b(?:fetch|writeFileSync|mkdirSync|rmSync|cpSync|execFileSync|spawnSync)\s*\(/.test(
+    source,
+  );
+}
+
+const validatorScripts = readdirSync(scriptsDir)
+  .filter((name) => /^validate-.*\.mjs$/.test(name))
+  .sort();
+
+test('the repository still ships read-only validate-*.mjs scripts', () => {
+  assert.ok(
+    validatorScripts.length > 0,
+    'no scripts/validate-*.mjs found; this guard would pass vacuously',
+  );
+});
+
+test('every read-only validator is listed in READ_ONLY_VALIDATORS', () => {
+  const listed = new Set(smokeListedValidators());
+  const unguarded = validatorScripts
+    .filter((name) => isReadOnly(name))
+    .filter((name) => !listed.has(name));
+  assert.deepEqual(
+    unguarded,
+    [],
+    'validators that never run on a pull request: add them to READ_ONLY_VALIDATORS in tests/validators-smoke.test.mjs',
+  );
+});
+
+test('every entry in READ_ONLY_VALIDATORS exists on disk', () => {
+  const missing = smokeListedValidators().filter(
+    (name) => !existsSync(join(scriptsDir, name)),
+  );
+  assert.deepEqual(
+    missing,
+    [],
+    'READ_ONLY_VALIDATORS names scripts that are not in scripts/',
+  );
+});
+
+test('READ_ONLY_VALIDATORS lists each validator exactly once', () => {
+  const listed = smokeListedValidators();
+  const duplicates = listed.filter(
+    (name, index) => listed.indexOf(name) !== index,
+  );
+  assert.deepEqual(duplicates, [], 'duplicate entries in READ_ONLY_VALIDATORS');
+});