diff --git a/.changeset/31045-locale-switcher-table-labels.md b/.changeset/31045-locale-switcher-table-labels.md
new file mode 100644
index 00000000000..914bd1c65f0
--- /dev/null
+++ b/.changeset/31045-locale-switcher-table-labels.md
@@ -0,0 +1,16 @@
+---
+'@object-ui/app-shell': patch
+---
+
+Clause-②: no
+Metadata-protocol: none
+
+The Console language menu now names the built-in languages from the platform
+locale table (`PLATFORM_LOCALES` in `@objectstack/spec/system`): each entry
+shows its row's `label`, such as `简体中文`, `繁體中文` and
+`Português (Brasil)`. The menu used to keep its own list of names, keyed by
+the retired `zh` and `pt` codes, so those three languages were named by the
+runtime's `Intl.DisplayNames` instead, which varies by browser and ICU version
+and shows the bare code where `Intl.DisplayNames` is missing. A code that is
+not on the table, such as an app-shipped `th`, is still named by
+`Intl.DisplayNames`. The set of languages the menu offers is unchanged.
diff --git a/ui/packages/app-shell/src/layout/LocaleSwitcher.tsx b/ui/packages/app-shell/src/layout/LocaleSwitcher.tsx
index 0464c1cbfbd..dfc655647be 100644
--- a/ui/packages/app-shell/src/layout/LocaleSwitcher.tsx
+++ b/ui/packages/app-shell/src/layout/LocaleSwitcher.tsx
@@ -7,10 +7,11 @@
  * The menu is not a list of its own (objectui#4039): it renders whatever the
  * i18n provider says is offerable — the app's own locale list ∩ what the
  * renderer can resolve. This file owns only the *labels*, because the native
- * names of the built-in packs are the one piece of that no API supplies:
+ * names are the one piece of that no API response supplies:
  * `GET /api/v1/i18n/locales` returns descriptors whose `label` is the code
  * echoed back (`toLocaleDescriptors` in @objectstack/spec), so a server label
- * would put `th` in the menu where `ไทย` belongs.
+ * would put `th` in the menu where `ไทย` belongs. The built-in packs are named
+ * from the platform locale table instead, every other code by the runtime.
  *
  * It is also not a device-local setting any more (objectui#10059). A switch made
  * while signed in writes `sys_user.locale` — the column the profile page's
@@ -28,45 +29,39 @@ import {
   DropdownMenuTrigger,
 } from '@object-ui/components';
 import { useObjectTranslation } from '@object-ui/i18n';
+import { PLATFORM_LOCALES } from '@objectstack/spec/system';
 import { confirmUnsavedLeave } from '../chrome/unsavedEdits.js';
 import { useLanguageSelection } from '../hooks/useUserLocale.js';
 
 /**
- * Native display names for the built-in language packs.
+ * Native display names for the built-in language packs, read from the
+ * platform locale table (`PLATFORM_LOCALES` in `@objectstack/spec/system`):
+ * each row's `label` is the language's own name for itself, the name a
+ * language menu shows. The table is the one list of platform languages, so
+ * there is no second, hand-kept list of names here. Indexed by the row's
+ * canonical `tag` (`en`, `zh-Hans`, `pt-BR`, …).
  *
- * Kept by hand rather than derived from `Intl.DisplayNames`: these are the
- * names the console has always shown, they are stable across ICU versions and
- * runtimes, and several read better than the CLDR rendering. Any code *not*
- * in here — an app-shipped locale like `th` or `pt-BR` — is named by
- * `Intl.DisplayNames` instead. A `Map` rather than an object literal so a code
- * like `constructor` cannot pick a label off `Object.prototype`.
+ * A `Map` rather than an object literal so a code like `constructor` cannot
+ * pick a label off `Object.prototype`.
  */
-const BUILT_IN_LABELS = new Map<string, string>([
-  ['en', 'English'],
-  ['zh', '中文'],
-  ['ja', '日本語'],
-  ['ko', '한국어'],
-  ['de', 'Deutsch'],
-  ['fr', 'Français'],
-  ['es', 'Español'],
-  ['pt', 'Português'],
-  ['ru', 'Русский'],
-  ['ar', 'العربية'],
-]);
+const BUILT_IN_LABEL_BY_TAG: ReadonlyMap<string, string> = new Map(
+  PLATFORM_LOCALES.map((row): [string, string] => [row.tag, row.label]),
+);
 
 /**
  * Name a locale in its own language.
  *
- * Built-in names win where they exist; everything else goes through
- * `Intl.DisplayNames` in the locale itself, so a menu of app locales reads the
- * way the built-in ten always have (native, not translated into the current
- * UI language). Every failure degrades to the bare code, which is still a
- * selectable, honest entry: `Intl.DisplayNames` is absent on old runtimes,
- * throws `RangeError` on a malformed tag, and returns the input unchanged for
- * a tag it has no name for.
+ * A platform locale table tag is named by its row's `label`, which is the
+ * same on every runtime and ICU version. Any other code (an app-shipped
+ * locale like `th`) goes through `Intl.DisplayNames` in the locale itself, so
+ * a menu of app locales reads the way the built-in ones do (native, not
+ * translated into the current UI language). Every failure degrades to the
+ * bare code, which is still a selectable, honest entry: `Intl.DisplayNames`
+ * is absent on old runtimes, throws `RangeError` on a malformed tag, and
+ * returns the input unchanged for a tag it has no name for.
  */
 export function localeLabel(code: string): string {
-  const builtIn = BUILT_IN_LABELS.get(code);
+  const builtIn = BUILT_IN_LABEL_BY_TAG.get(code);
   if (builtIn) return builtIn;
   try {
     const name = new Intl.DisplayNames([code], { type: 'language' }).of(code);
diff --git a/ui/packages/app-shell/src/layout/__tests__/LocaleSwitcher.appLocales.test.tsx b/ui/packages/app-shell/src/layout/__tests__/LocaleSwitcher.appLocales.test.tsx
index 0bb5bdc1dce..e214e4e11d6 100644
--- a/ui/packages/app-shell/src/layout/__tests__/LocaleSwitcher.appLocales.test.tsx
+++ b/ui/packages/app-shell/src/layout/__tests__/LocaleSwitcher.appLocales.test.tsx
@@ -37,13 +37,13 @@ vi.mock('lucide-react', async (importOriginal) => ({
   Globe: () => <span />,
 }));
 
-import { PLATFORM_LOCALE_TAGS } from '@objectstack/spec/system';
+import { PLATFORM_LOCALES, PLATFORM_LOCALE_TAGS } from '@objectstack/spec/system';
 import { LocaleSwitcher, localeLabel } from '../LocaleSwitcher';
 
 /**
- * The eight built-in native names an app shipping only `en`+`zh` must NOT show:
- * every platform locale table language but English and Chinese, named as the
- * menu names them (`pt-BR` by `Intl.DisplayNames`, objectstack#30511).
+ * The eight built-in native names an app shipping only `en`+`zh-Hans` must NOT
+ * show: every platform locale table language but English and Chinese, named as
+ * the menu names them (from the table's own labels).
  */
 const PHANTOM_LABELS = PLATFORM_LOCALE_TAGS
   .filter((tag) => tag !== 'en' && !tag.startsWith('zh-'))
@@ -75,12 +75,12 @@ beforeEach(() => {
 
 describe('LocaleSwitcher — menu composed from the app locale list', () => {
   it('offers an app-shipped locale outside the built-in ten, named by Intl.DisplayNames', async () => {
-    mountConsole({ locales: async () => ['en', 'zh', 'th'] });
+    mountConsole({ locales: async () => ['en', 'zh-Hans', 'th'] });
 
-    // `th` has no built-in pack and no hand-written label; CLDR names it.
+    // `th` has no built-in pack and no platform locale table row; CLDR names it.
     await waitFor(() => expect(screen.getByText('ไทย')).toBeInTheDocument());
     expect(screen.getByText('English')).toBeInTheDocument();
-    expect(screen.getByText('中文')).toBeInTheDocument();
+    expect(screen.getByText('简体中文')).toBeInTheDocument();
   });
 
   it('offers an app-shipped locale supplied through config.resources', async () => {
@@ -106,10 +106,10 @@ describe('LocaleSwitcher — menu composed from the app locale list', () => {
   });
 
   it('shows ONLY what the app ships — the phantom eight are gone', async () => {
-    mountConsole({ locales: async () => ['en', 'zh'] });
+    mountConsole({ locales: async () => ['en', 'zh-Hans'] });
 
     await waitFor(() => expect(screen.getByText('English')).toBeInTheDocument());
-    expect(screen.getByText('中文')).toBeInTheDocument();
+    expect(screen.getByText('简体中文')).toBeInTheDocument();
     for (const phantom of PHANTOM_LABELS) {
       expect(screen.queryByText(phantom)).not.toBeInTheDocument();
     }
@@ -154,7 +154,7 @@ describe('LocaleSwitcher — menu composed from the app locale list', () => {
     expect(container.firstChild).toBeNull();
     expect(screen.queryByText('English')).not.toBeInTheDocument();
 
-    answer(['en', 'zh']);
+    answer(['en', 'zh-Hans']);
 
     await waitFor(() => expect(screen.getByText('English')).toBeInTheDocument());
     expect(screen.queryByText('日本語')).not.toBeInTheDocument();
@@ -175,3 +175,40 @@ describe('LocaleSwitcher — menu composed from the app locale list', () => {
     }
   });
 });
+
+describe('localeLabel — the built-in packs are named by the platform locale table', () => {
+  it('names every table tag with its row label', () => {
+    for (const row of PLATFORM_LOCALES) {
+      expect(localeLabel(row.tag), row.tag).toBe(row.label);
+    }
+  });
+
+  it('names every table tag with its row label on a runtime without Intl.DisplayNames', () => {
+    // The table label must not be whatever the runtime's CLDR happens to say:
+    // with the runtime naming nothing, every row still reads its own label.
+    const displayNames = Intl.DisplayNames;
+    Object.defineProperty(Intl, 'DisplayNames', {
+      configurable: true,
+      writable: true,
+      value: undefined,
+    });
+    try {
+      for (const row of PLATFORM_LOCALES) {
+        expect(localeLabel(row.tag), row.tag).toBe(row.label);
+      }
+      // An app-shipped code still degrades to the bare code, not a crash.
+      expect(localeLabel('th')).toBe('th');
+    } finally {
+      Object.defineProperty(Intl, 'DisplayNames', {
+        configurable: true,
+        writable: true,
+        value: displayNames,
+      });
+    }
+  });
+
+  it('cannot read a label off Object.prototype', () => {
+    expect(localeLabel('constructor')).toBe('constructor');
+    expect(localeLabel('__proto__')).toBe('__proto__');
+  });
+});