fix: parse raw public translation responses in banner

The public translations endpoint returns the raw strings dictionary, but
the banner expected a wrapped { strings } response and therefore fell back
to English for Thai translations.

Update fetchTranslations() to accept the raw public API shape while keeping
compatibility with wrapped responses. Make default_language optional in the
banner SiteConfig type so old/mocked configs still typecheck.

apps/banner/src/__tests__/i18n.test.ts

@@ -106,9 +106,9 @@ describe('i18n', () => {
         json: () => Promise.resolve(mockTranslations),
       }));
 
-      const result = await fetchTranslations('https://cdn.example.com', 'fr');
+      const result = await fetchTranslations('https://api.example.com', 'site-123', 'fr');
 
-      expect(fetch).toHaveBeenCalledWith('https://cdn.example.com/translations-fr.json');
+      expect(fetch).toHaveBeenCalledWith('https://api.example.com/api/v1/translations/site-123/fr');
       expect(result).toEqual(mockTranslations);
 
       vi.unstubAllGlobals();
@@ -117,7 +117,7 @@ describe('i18n', () => {
     it('should return null on 404', async () => {
       vi.stubGlobal('fetch', vi.fn().mockResolvedValue({ ok: false, status: 404 }));
 
-      const result = await fetchTranslations('https://cdn.example.com', 'zz');
+      const result = await fetchTranslations('https://api.example.com', 'site-123', 'zz');
       expect(result).toBeNull();
 
       vi.unstubAllGlobals();
@@ -126,7 +126,7 @@ describe('i18n', () => {
     it('should return null on network error', async () => {
       vi.stubGlobal('fetch', vi.fn().mockRejectedValue(new Error('Network error')));
 
-      const result = await fetchTranslations('https://cdn.example.com', 'fr');
+      const result = await fetchTranslations('https://api.example.com', 'site-123', 'fr');
       expect(result).toBeNull();
 
       vi.unstubAllGlobals();
@@ -140,7 +140,23 @@ describe('i18n', () => {
       expect(t.acceptAll).toBe(DEFAULT_TRANSLATIONS.acceptAll);
     });
 
-    it('should merge remote translations over defaults', async () => {
+    it('should merge raw public API translations over defaults', async () => {
+      vi.stubGlobal('fetch', vi.fn().mockResolvedValue({
+        ok: true,
+        json: () => Promise.resolve({ title: 'เราใช้คุกกี้', acceptAll: 'ยอมรับทั้งหมด' }),
+      }));
+
+      const t = await loadTranslations('https://api.example.com', 'site-123', 'th');
+
+      expect(t.title).toBe('เราใช้คุกกี้');
+      expect(t.acceptAll).toBe('ยอมรับทั้งหมด');
+      // Missing keys should fall back to English
+      expect(t.rejectAll).toBe(DEFAULT_TRANSLATIONS.rejectAll);
+
+      vi.unstubAllGlobals();
+    });
+
+    it('should also accept legacy wrapped translation responses', async () => {
       vi.stubGlobal('fetch', vi.fn().mockResolvedValue({
         ok: true,
         json: () => Promise.resolve({ strings: { title: 'Wir verwenden Cookies', acceptAll: 'Alle akzeptieren' } }),
@@ -150,8 +166,6 @@ describe('i18n', () => {
 
       expect(t.title).toBe('Wir verwenden Cookies');
       expect(t.acceptAll).toBe('Alle akzeptieren');
-      // Missing keys should fall back to English
-      expect(t.rejectAll).toBe(DEFAULT_TRANSLATIONS.rejectAll);
 
       vi.unstubAllGlobals();
     });

apps/banner/src/i18n.ts

@@ -95,9 +95,10 @@ export async function fetchTranslations(
   try {
     const resp = await fetch(`${apiBase}/api/v1/translations/${siteId}/${locale}`);
     if (!resp.ok) return null;
-    // API returns { strings: { ... } }
+    // Public API returns the raw strings dict. Accept a wrapped `{ strings }`
-    const data = (await resp.json()) as { strings?: Partial<TranslationStrings> };
+    // shape too for backwards compatibility with older mocks/clients.
-    return data.strings ?? null;
+    const data = await resp.json() as Partial<TranslationStrings> | { strings?: Partial<TranslationStrings> };
+    return 'strings' in data && data.strings ? data.strings : data as Partial<TranslationStrings>;
   } catch {
     return null;
   }

apps/banner/src/types.ts

@@ -80,7 +80,7 @@ export interface SiteConfig {
   gcm_default: Record<string, 'granted' | 'denied'> | null;
   shopify_privacy_enabled: boolean;
   banner_config: BannerConfig | null;
-  default_language: string | null;
+  default_language?: string | null;
   privacy_policy_url: string | null;
   terms_url: string | null;
   consent_expiry_days: number;