diff --git a/src/apps/officer-web/lib/I18nBridge.tsx b/src/apps/officer-web/lib/I18nBridge.tsx
index 7c82d4be..b9f5f7a6 100644
--- a/src/apps/officer-web/lib/I18nBridge.tsx
+++ b/src/apps/officer-web/lib/I18nBridge.tsx
@@ -1,31 +1,11 @@
 import { useEffect } from 'react';
 import type { ReactNode } from 'react';
-import type { TranslationMap } from 'i18n';
+
 import { I18nProvider, localeDirection } from 'i18n';
 import { setNameRevision } from 'workspaces/react';
-import { panelCatalogs } from 'officerdev';
-import { uiCatalogs } from '@/components/locales';
 import { useSettings } from 'state/useSettings';
 import { FALLBACK_LOCALE, SHIPPED_LOCALES } from './locales';
-import appEnGB from '../locales/en-GB.json';
-import appPtPT from '../locales/pt-PT.json';
-
-const appCatalogs: TranslationMap = { 'en-GB': appEnGB, 'pt-PT': appPtPT };
-
-/**
- * Deep-merges the three per-workspace catalogs (D6) into one map per shipped locale — `app.*` from
- * officer-web, `panel.*` from officerdev's panel apps, `ui.*` from shared components.
- */
-const translations: TranslationMap = Object.fromEntries(
-  SHIPPED_LOCALES.map(({ code }) => [
-    code,
-    {
-      app: appCatalogs[code] ?? {},
-      panel: panelCatalogs[code] ?? {},
-      ui: uiCatalogs[code] ?? {},
-    },
-  ]),
-);
+import { catalogues as translations } from './catalogues';
 
 type I18nBridgeProps = {
   children: ReactNode;
diff --git a/src/apps/officer-web/lib/catalogues.test.ts b/src/apps/officer-web/lib/catalogues.test.ts
new file mode 100644
index 00000000..f3735193
--- /dev/null
+++ b/src/apps/officer-web/lib/catalogues.test.ts
@@ -0,0 +1,51 @@
+import { describe, expect, test } from 'bun:test';
+import { catalogues } from './catalogues';
+import { FALLBACK_LOCALE, SHIPPED_LOCALES } from './locales';
+
+/**
+ * A locale is only shipped if it is actually LOADED.
+ *
+ * This exists because es-ES, de-DE and fr-FR shipped dead. Every one of their 1,129 keys was translated and
+ * in parity, all three were in `SHIPPED_LOCALES` so the picker offered them, and choosing one rendered the
+ * entire UI in raw keys — because none of the three catalogue files had been given the `import`.
+ *
+ * The parity tests could not have caught it and never will: they compare JSON files to each other, and an
+ * unimported file is as parity-correct as an imported one. The gap was between "the translation exists" and
+ * "the app can reach it", and nothing was asking that question.
+ *
+ * Adding a locale touches four files. This is the one that knows whether all four happened.
+ */
+describe('every shipped locale is reachable', () => {
+  const NAMESPACES = ['app', 'panel', 'ui'] as const;
+
+  test('SHIPPED_LOCALES is not empty and contains the fallback', () => {
+    expect(SHIPPED_LOCALES.length).toBeGreaterThan(0);
+    expect(SHIPPED_LOCALES.map((l) => l.code)).toContain(FALLBACK_LOCALE);
+  });
+
+  for (const { code } of SHIPPED_LOCALES) {
+    describe(code, () => {
+      test('has a catalogue at all', () => {
+        expect(catalogues[code]).toBeDefined();
+      });
+
+      for (const ns of NAMESPACES) {
+        // Non-empty, not merely present. The failure being pinned produced `{}` for all three, which is
+        // exactly what `?? {}` yields for a locale nobody imported — present, and useless.
+        test(`${ns}.* is populated`, () => {
+          const catalogue = (catalogues[code] as Record<string, object> | undefined)?.[ns];
+          expect(catalogue).toBeDefined();
+          expect(Object.keys(catalogue ?? {}).length).toBeGreaterThan(0);
+        });
+      }
+
+      // Parity against the fallback is tested per-workspace already; this is the cheaper cross-check that
+      // the MERGED catalogue is the same size, which catches a namespace wired to the wrong locale's file.
+      test('is the same size as the fallback', () => {
+        const count = (o: unknown): number =>
+          typeof o === 'object' && o !== null ? Object.values(o).reduce<number>((n, v) => n + count(v), 0) : 1;
+        expect(count(catalogues[code])).toBe(count(catalogues[FALLBACK_LOCALE]));
+      });
+    });
+  }
+});
diff --git a/src/apps/officer-web/lib/catalogues.ts b/src/apps/officer-web/lib/catalogues.ts
new file mode 100644
index 00000000..3af2629c
--- /dev/null
+++ b/src/apps/officer-web/lib/catalogues.ts
@@ -0,0 +1,47 @@
+import type { TranslationMap } from 'i18n';
+import { panelCatalogs } from 'officerdev';
+import { uiCatalogs } from '@/components/locales';
+import { SHIPPED_LOCALES } from './locales';
+import appDeDE from '../locales/de-DE.json';
+import appEnGB from '../locales/en-GB.json';
+import appEsES from '../locales/es-ES.json';
+import appFrFR from '../locales/fr-FR.json';
+import appPtPT from '../locales/pt-PT.json';
+
+/**
+ * The three per-workspace catalogues, merged into one map per shipped locale (D6): `app.*` from
+ * officer-web, `panel.*` from officerdev's panel apps, `ui.*` from shared components.
+ *
+ * ── Why this is a separate file from `I18nBridge` ──
+ *
+ * So it can be tested without mounting React, and it is tested because of a real failure. es-ES, de-DE and
+ * fr-FR shipped translated, in perfect key parity, listed in the picker — and completely dead. All three
+ * `import` lists still named only en-GB and pt-PT, so `catalogues[code]` was three empty objects and the
+ * whole UI rendered untranslated in three of five languages.
+ *
+ * Nothing caught it. The parity tests compare the JSON FILES against each other and every file was correct;
+ * a locale that is never imported is invisible to them by construction. `SHIPPED_LOCALES` is what the picker
+ * reads, and it had been updated. Adding a locale was four edits in four files with no single place that
+ * knew all four had happened.
+ *
+ * `catalogues.test.ts` is now that place: it asserts every shipped locale actually resolves to a populated
+ * catalogue in all three namespaces.
+ */
+const appCatalogs: TranslationMap = {
+  'en-GB': appEnGB,
+  'pt-PT': appPtPT,
+  'es-ES': appEsES,
+  'de-DE': appDeDE,
+  'fr-FR': appFrFR,
+};
+
+export const catalogues: TranslationMap = Object.fromEntries(
+  SHIPPED_LOCALES.map(({ code }) => [
+    code,
+    {
+      app: appCatalogs[code] ?? {},
+      panel: panelCatalogs[code] ?? {},
+      ui: uiCatalogs[code] ?? {},
+    },
+  ]),
+);
diff --git a/src/workspaces/components/locales/index.ts b/src/workspaces/components/locales/index.ts
index d8f20679..aa400b8d 100644
--- a/src/workspaces/components/locales/index.ts
+++ b/src/workspaces/components/locales/index.ts
@@ -1,8 +1,17 @@
 import type { TranslationMap } from 'i18n';
+import deDE from './de-DE.json';
 import enGB from './en-GB.json';
+import esES from './es-ES.json';
+import frFR from './fr-FR.json';
 import ptPT from './pt-PT.json';
 
 /** Shared components' own catalog, per locale — merged into the app-wide map by `I18nBridge` under `ui.*`. */
-export const uiCatalogs: TranslationMap = { 'en-GB': enGB, 'pt-PT': ptPT };
+export const uiCatalogs: TranslationMap = {
+  'en-GB': enGB,
+  'pt-PT': ptPT,
+  'es-ES': esES,
+  'de-DE': deDE,
+  'fr-FR': frFR,
+};
 
 export { useTranslation } from './useTranslation';
diff --git a/src/workspaces/officerdev/src/locales/index.ts b/src/workspaces/officerdev/src/locales/index.ts
index cbea9026..e8652db7 100644
--- a/src/workspaces/officerdev/src/locales/index.ts
+++ b/src/workspaces/officerdev/src/locales/index.ts
@@ -1,9 +1,18 @@
 import type { TranslationMap } from 'i18n';
+import deDE from './de-DE.json';
 import enGB from './en-GB.json';
+import esES from './es-ES.json';
+import frFR from './fr-FR.json';
 import ptPT from './pt-PT.json';
 
 /** Panel apps' own catalog, per locale — merged into the app-wide map by `I18nBridge` under `panel.*`. */
-export const panelCatalogs: TranslationMap = { 'en-GB': enGB, 'pt-PT': ptPT };
+export const panelCatalogs: TranslationMap = {
+  'en-GB': enGB,
+  'pt-PT': ptPT,
+  'es-ES': esES,
+  'de-DE': deDE,
+  'fr-FR': frFR,
+};
 
 export { useTranslation } from './useTranslation';
 export type { PanelTranslationKey } from './useTranslation';