diff --git a/.ai/manifests/governance.json b/.ai/manifests/governance.json
index b3be0261e..9e941f411 100644
--- a/.ai/manifests/governance.json
+++ b/.ai/manifests/governance.json
@@ -174,7 +174,7 @@
       "file": "rules/19-logging-observability-and-redaction.md"
     },
     {
-      "bytes": 4264,
+      "bytes": 4914,
       "file": "rules/20-i18n-and-user-facing-messages.md"
     },
     {
diff --git a/.ai/manifests/hashes.json b/.ai/manifests/hashes.json
index 67626ec79..1e4f01c8f 100644
--- a/.ai/manifests/hashes.json
+++ b/.ai/manifests/hashes.json
@@ -8,7 +8,7 @@
     ".ai/manifests/environment-variables.json": "33602cbe",
     ".ai/manifests/event-graph.json": "c1cd05bc",
     ".ai/manifests/frontend-routes.json": "a52b7ece",
-    ".ai/manifests/governance.json": "e4492ebd",
+    ".ai/manifests/governance.json": "1160e343",
     ".ai/manifests/i18n.json": "3befb756",
     ".ai/manifests/nginx-routes.json": "53c65be1",
     ".ai/manifests/packages.json": "cc928a4a",
@@ -18,7 +18,7 @@
     ".ai/manifests/rabbitmq-events.json": "bcaeb411",
     ".ai/manifests/repository.json": "047d93d0",
     ".ai/manifests/services.json": "9c92d2c4",
-    ".ai/manifests/tests.json": "4044f562",
+    ".ai/manifests/tests.json": "6eb2e2ae",
     ".ai/manifests/workspace-dependency-graph.json": "80e5438b",
     ".ai/manifests/workspaces.json": "b5133e99",
     ".ai/packs/README.md": "2e64753b",
diff --git a/.ai/manifests/tests.json b/.ai/manifests/tests.json
index 4c1217b64..71b854786 100644
--- a/.ai/manifests/tests.json
+++ b/.ai/manifests/tests.json
@@ -58,7 +58,7 @@
     },
     "claw-frontend": {
       "runner": "vitest",
-      "testFiles": 410
+      "testFiles": 411
     },
     "claw-health-service": {
       "runner": "jest",
@@ -102,5 +102,5 @@
     }
   },
   "generated": true,
-  "total": 1122
+  "total": 1123
 }
diff --git a/apps/claw-frontend/src/constants/__tests__/learn-content-locale-completeness.test.ts b/apps/claw-frontend/src/constants/__tests__/learn-content-locale-completeness.test.ts
new file mode 100644
index 000000000..371abc154
--- /dev/null
+++ b/apps/claw-frontend/src/constants/__tests__/learn-content-locale-completeness.test.ts
@@ -0,0 +1,110 @@
+import { describe, expect, it } from 'vitest';
+
+import { LEARN_CONTENT_BY_LOCALE } from '@/constants/learn-content.constants';
+import { Locale } from '@/enums/locale.enum';
+
+/**
+ * Flattens a `LearnDictionary` into `path -> string` pairs, the same shape
+ * the i18n completeness tests use (see `chinese-completeness.test.ts`,
+ * `translations.test.ts`). Arrays (e.g. `seo.keywords`) flatten by index,
+ * which is exactly what parity needs: a locale with two keywords instead of
+ * three shows up as a missing key, not a silently shorter array.
+ */
+function flatten(value: unknown, prefix = '', result: Record<string, string> = {}): Record<string, string> {
+  if (typeof value === 'string') {
+    result[prefix] = value;
+    return result;
+  }
+  if (typeof value !== 'object' || value === null) {
+    return result;
+  }
+  for (const [key, child] of Object.entries(value)) {
+    flatten(child, prefix === '' ? key : `${prefix}.${key}`, result);
+  }
+  return result;
+}
+
+function placeholders(value: string): string[] {
+  return [...value.matchAll(/\{[^{}]+\}/gu)].map((match) => match[0]).sort();
+}
+
+/**
+ * Section anchor ids (`sections.<n>.id`) are deliberately identical across
+ * every locale — "Stable across locales so a translated page keeps its deep
+ * links" (`LearnSection` in `types/learn.types.ts`). They are structural,
+ * not prose, so they are excluded from the "did anyone actually translate
+ * this" check below, the same way a `data-testid` would be.
+ */
+function isStructuralKey(key: string): boolean {
+  return key.endsWith('.id');
+}
+
+/**
+ * Values that are correctly identical across every locale: proper nouns,
+ * acronyms, product/model names, and other technical terms nobody
+ * translates. Anything NOT on this list that matches English exactly is
+ * either an untranslated string or a coincidence rare enough to be worth a
+ * second look — see `chinese-completeness.test.ts` for the same pattern
+ * against the general UI dictionary.
+ */
+const LEGITIMATE_UNCHANGED_VALUES = new Set<string>([
+  'ClawAI',
+  'RAG',
+  'GPU',
+  'CPU',
+  'API',
+  'LLM',
+  'PDF',
+  'URL',
+  'GitHub',
+  'Ollama',
+  'llama.cpp',
+  'Ollama vs llama.cpp',
+  // French "orchestration" is spelled identically to English (it is in fact
+  // the older of the two — the word entered English FROM French). Not a
+  // missed translation: fr correctly translates the same English word to
+  // "Orchestrazione"/"Orchestrierung" is what it/de do, which is a different
+  // language having a different native form, not evidence fr is wrong.
+  'Orchestration',
+  // "Routing" is a standard, widely-used loanword in German and Italian
+  // technical writing (as common as "Router" itself) — this repo's own de/it
+  // copy elsewhere also keeps other loanwords (e.g. "GPU") rather than
+  // coining an unfamiliar native term. Flagged here for visibility: if a
+  // native speaker prefers a translated term, remove this line and fix the
+  // two eyebrow values it currently allows through.
+  'Routing',
+  // SEO keyword arrays intentionally keep the English query term a non-English
+  // searcher would actually type — "best of N" is ML/statistics jargon, not
+  // prose, and translating it would target a search query nobody makes.
+  'best of N',
+]);
+
+const english = flatten(LEARN_CONTENT_BY_LOCALE[Locale.EN]);
+const nonEnglishLocales = Object.values(Locale).filter((locale) => locale !== Locale.EN);
+
+describe('/learn content locale completeness', () => {
+  it.each(nonEnglishLocales)('%s defines every English key with no missing sections/faq/keywords', (locale) => {
+    const localized = flatten(LEARN_CONTENT_BY_LOCALE[locale]);
+    expect(Object.keys(localized).sort()).toEqual(Object.keys(english).sort());
+  });
+
+  it.each(nonEnglishLocales)('%s preserves every interpolation placeholder', (locale) => {
+    const localized = flatten(LEARN_CONTENT_BY_LOCALE[locale]);
+    for (const key of Object.keys(english)) {
+      expect(placeholders(localized[key] ?? ''), key).toEqual(placeholders(english[key] ?? ''));
+    }
+  });
+
+  it.each(nonEnglishLocales)(
+    '%s has no untranslated English fallback outside the approved technical terms',
+    (locale) => {
+      const localized = flatten(LEARN_CONTENT_BY_LOCALE[locale]);
+      const unexpectedlyUnchanged = Object.keys(english)
+        .filter((key) => !isStructuralKey(key))
+        .filter((key) => localized[key] === english[key])
+        .filter((key) => !LEGITIMATE_UNCHANGED_VALUES.has(english[key] ?? ''));
+
+      expect(unexpectedlyUnchanged).toEqual([]);
+    },
+  );
+});
diff --git a/docs/features/ai-native-engineering-os/inventory.snapshot.json b/docs/features/ai-native-engineering-os/inventory.snapshot.json
index 23319c4e9..4cae7a7b1 100644
--- a/docs/features/ai-native-engineering-os/inventory.snapshot.json
+++ b/docs/features/ai-native-engineering-os/inventory.snapshot.json
@@ -7378,7 +7378,7 @@
           "file": "rules/19-logging-observability-and-redaction.md"
         },
         {
-          "bytes": 4264,
+          "bytes": 4914,
           "file": "rules/20-i18n-and-user-facing-messages.md"
         },
         {
@@ -9516,7 +9516,7 @@
       },
       "claw-frontend": {
         "runner": "vitest",
-        "testFiles": 410
+        "testFiles": 411
       },
       "claw-health-service": {
         "runner": "jest",
@@ -10276,7 +10276,7 @@
     "serviceCount": 18,
     "sharedPackageCount": 6,
     "staleClaimCount": 0,
-    "totalTestFiles": 1122,
+    "totalTestFiles": 1123,
     "workspaceCount": 25
   }
 }
diff --git a/rules/20-i18n-and-user-facing-messages.md b/rules/20-i18n-and-user-facing-messages.md
index 99a4d4388..91d454442 100644
--- a/rules/20-i18n-and-user-facing-messages.md
+++ b/rules/20-i18n-and-user-facing-messages.md
@@ -70,6 +70,15 @@ imply a coverage that was not there.
   `western-locales-translation-regression.test.ts`** — catch English left
   untranslated, with an explicit allow-list of approved technical terms.
 - **`supported-locales.test.ts`** — every `Locale` member has a dictionary.
+- **`constants/__tests__/learn-content-locale-completeness.test.ts`** (2026-09-01) —
+  the four tests above all assert against `lib/i18n/locales/*`, the UI-chrome
+  dictionary; none of them touch `constants/learn-content/*.constants.ts`, the
+  `/learn` article prose. This test covers that separately-maintained content
+  cluster for all 13 locales: key/section/FAQ parity, placeholder parity, and
+  the same untranslated-English-fallback check with its own allow-list. Any
+  other long-form content cluster added the same way (see
+  `public-comparison-content/`) needs the same treatment — it will not be
+  caught by the UI-dictionary tests either.
 - **TS config** — an `i18n.types.ts` mismatch fails `npm run typecheck`.
 - **Review checklist** — visual spot-check of one non-EN locale.