UI & Localization

app/api/generate/scene-content/route.ts

@@ -69,7 +69,10 @@ export async function POST(req: NextRequest) {
     // Ensure outline has language from stageInfo (fallback for older outlines)
     const outline: SceneOutline = {
       ...rawOutline,
-      language: rawOutline.language || (stageInfo?.language as 'zh-CN' | 'en-US') || 'zh-CN',
+      language:
+        rawOutline.language ||
+        (stageInfo?.language as import('@/lib/types/generation').CourseLanguage) ||
+        'zh-CN',
     };
 
     // ── Model resolution from request headers ──

app/page.tsx

@@ -58,7 +58,7 @@ const RECENT_OPEN_STORAGE_KEY = 'recentClassroomsOpen';
 interface FormState {
   pdfFile: File | null;
   requirement: string;
-  language: 'zh-CN' | 'en-US';
+  language: import('@/lib/types/generation').CourseLanguage;
   webSearch: boolean;
 }
 
@@ -101,10 +101,22 @@ function HomePage() {
       const savedLanguage = localStorage.getItem(LANGUAGE_STORAGE_KEY);
       const updates: Partial<FormState> = {};
       if (savedWebSearch === 'true') updates.webSearch = true;
-      if (savedLanguage === 'zh-CN' || savedLanguage === 'en-US') {
+      if (
+        savedLanguage === 'zh-CN' ||
+        savedLanguage === 'en-US' ||
+        savedLanguage === 'ja-JP' ||
+        savedLanguage === 'ru-RU'
+      ) {
         updates.language = savedLanguage;
       } else {
-        const detected = navigator.language?.startsWith('zh') ? 'zh-CN' : 'en-US';
+        const lang = navigator.language;
+        const detected = lang?.startsWith('zh')
+          ? 'zh-CN'
+          : lang?.startsWith('ja')
+            ? 'ja-JP'
+            : lang?.startsWith('ru')
+              ? 'ru-RU'
+              : 'en-US';
         updates.language = detected;
       }
       if (Object.keys(updates).length > 0) {

components/agent/agent-bar.tsx

@@ -83,7 +83,14 @@ function AgentVoicePill({
       const courseLanguage =
         (typeof localStorage !== 'undefined' && localStorage.getItem('generationLanguage')) ||
         'zh-CN';
-      const previewText = courseLanguage === 'en-US' ? 'Welcome to AI Classroom' : '欢迎来到AI课堂';
+      const previewText =
+        courseLanguage === 'en-US'
+          ? 'Welcome to AI Classroom'
+          : courseLanguage === 'ja-JP'
+            ? 'AIクラスルームへようこそ'
+            : courseLanguage === 'ru-RU'
+              ? 'Добро пожаловать в AI-класс'
+              : '欢迎来到AI课堂';
 
       if (providerId === 'browser-native-tts') {
         const { promise, cancel } = playBrowserTTSPreview({ text: previewText, voice: voiceId });
@@ -308,7 +315,14 @@ function TeacherVoicePill({
       const courseLanguage =
         (typeof localStorage !== 'undefined' && localStorage.getItem('generationLanguage')) ||
         'zh-CN';
-      const previewText = courseLanguage === 'en-US' ? 'Welcome to AI Classroom' : '欢迎来到AI课堂';
+      const previewText =
+        courseLanguage === 'en-US'
+          ? 'Welcome to AI Classroom'
+          : courseLanguage === 'ja-JP'
+            ? 'AIクラスルームへようこそ'
+            : courseLanguage === 'ru-RU'
+              ? 'Добро пожаловать в AI-класс'
+              : '欢迎来到AI课堂';
 
       if (providerId === 'browser-native-tts') {
         const { promise, cancel } = playBrowserTTSPreview({ text: previewText, voice: voiceId });

components/generation/generation-toolbar.tsx

@@ -28,8 +28,8 @@ const MAX_PDF_SIZE_BYTES = MAX_PDF_SIZE_MB * 1024 * 1024;
 
 // ─── Types ───────────────────────────────────────────────────
 export interface GenerationToolbarProps {
-  language: 'zh-CN' | 'en-US';
-  onLanguageChange: (lang: 'zh-CN' | 'en-US') => void;
+  language: import('@/lib/types/generation').CourseLanguage;
+  onLanguageChange: (lang: import('@/lib/types/generation').CourseLanguage) => void;
   webSearch: boolean;
   onWebSearchChange: (v: boolean) => void;
   onSettingsOpen: (section?: SettingsSection) => void;
@@ -361,11 +361,28 @@ export function GenerationToolbar({
       <Tooltip>
         <TooltipTrigger asChild>
           <button
-            onClick={() => onLanguageChange(language === 'zh-CN' ? 'en-US' : 'zh-CN')}
+            onClick={() => {
+              const langs: import('@/lib/types/generation').CourseLanguage[] = [
+                'zh-CN',
+                'en-US',
+                'ja-JP',
+                'ru-RU',
+              ];
+              const idx = langs.indexOf(language);
+              onLanguageChange(langs[(idx + 1) % langs.length]);
+            }}
             className={pillMuted}
           >
             <Globe className="size-3.5" />
-            <span>{language === 'zh-CN' ? '中文' : 'EN'}</span>
+            <span>
+              {language === 'zh-CN'
+                ? '中文'
+                : language === 'en-US'
+                  ? 'EN'
+                  : language === 'ja-JP'
+                    ? 'JA'
+                    : 'RU'}
+            </span>
           </button>
         </TooltipTrigger>
         <TooltipContent>{t('toolbar.languageHint')}</TooltipContent>

lib/generation/scene-generator.ts

@@ -470,7 +470,7 @@ async function generateSlideContent(
   const lang = outline.language || 'zh-CN';
 
   // Build assigned images description for the prompt
-  let assignedImagesText = '无可用图片，禁止插入任何 image 元素';
+  let assignedImagesText = 'No images available. Do NOT insert any image elements.';
   let visionImages: Array<{ id: string; src: string }> | undefined;
 
   if (assignedImages && assignedImages.length > 0) {
@@ -521,7 +521,10 @@ async function generateSlideContent(
 
     if (mediaParts.length > 0) {
       const mediaText = mediaParts.join('\n\n');
-      if (assignedImagesText.includes('禁止插入') || assignedImagesText.includes('No images')) {
+      if (
+        assignedImagesText.includes('Do NOT insert') ||
+        assignedImagesText.includes('No images')
+      ) {
         assignedImagesText = mediaText;
       } else {
         assignedImagesText += `\n\n${mediaText}`;
@@ -735,7 +738,7 @@ function normalizeQuizAnswer(question: Record<string, unknown>): string[] | unde
 async function generateInteractiveContent(
   outline: SceneOutline,
   aiCall: AICallFn,
-  language: 'zh-CN' | 'en-US' = 'zh-CN',
+  language: import('@/lib/types/generation').CourseLanguage = 'zh-CN',
 ): Promise<GeneratedInteractiveContent | null> {
   const config = outline.interactiveConfig!;
 

lib/i18n/locales.ts

@@ -17,4 +17,5 @@ export const supportedLocales = [
   { code: 'zh-CN', label: '简体中文', shortLabel: 'CN' },
   { code: 'en-US', label: 'English', shortLabel: 'EN' },
   { code: 'ja-JP', label: '日本語', shortLabel: 'JA' },
+  { code: 'ru-RU', label: 'Русский', shortLabel: 'RU' },
 ] as const satisfies readonly LocaleEntry[];