feat(i18n): add zh-CN locale

apps/frontend/src/renderer/stores/settings-store.ts

@@ -295,6 +295,18 @@ export const useSettingsStore = create<SettingsState>((set) => ({
   }
 }));
 
+/**
+ * Migrate legacy language codes to current BCP 47 tags.
+ */
+function migrateLanguageCode(settings: AppSettings): AppSettings {
+  const language = settings.language as string | undefined;
+  if (language === 'zh') {
+    return { ...settings, language: 'zh-CN' };
+  }
+
+  return settings;
+}
+
 /**
  * Check if settings need migration for onboardingCompleted flag.
  * Existing users (with tokens or projects configured) should have
@@ -333,15 +345,20 @@ export async function loadSettings(): Promise<void> {
   try {
     const result = await window.electronAPI.getSettings();
     if (result.success && result.data) {
-      // Apply migration for onboardingCompleted flag
-      const migratedSettings = migrateOnboardingCompleted(result.data);
+      // Apply migrations
+      const migratedSettings = migrateLanguageCode(migrateOnboardingCompleted(result.data));
       store.setSettings(migratedSettings);
 
-      // If migration changed the settings, persist them
+      // If migrations changed the settings, persist them
+      const updates: Partial<AppSettings> = {};
       if (migratedSettings.onboardingCompleted !== result.data.onboardingCompleted) {
-        await window.electronAPI.saveSettings({
-          onboardingCompleted: migratedSettings.onboardingCompleted
-        });
+        updates.onboardingCompleted = migratedSettings.onboardingCompleted;
+      }
+      if (migratedSettings.language !== result.data.language) {
+        updates.language = migratedSettings.language;
+      }
+      if (Object.keys(updates).length > 0) {
+        await window.electronAPI.saveSettings(updates);
       }
 
       // Only mark settings as loaded on SUCCESS

apps/frontend/src/shared/constants/i18n.ts

@@ -3,11 +3,12 @@
  * Available languages and display labels
  */
 
-export type SupportedLanguage = 'en' | 'fr';
+export type SupportedLanguage = 'en' | 'fr' | 'zh-CN';
 
 export const AVAILABLE_LANGUAGES = [
   { value: 'en' as const, label: 'English', nativeLabel: 'English' },
-  { value: 'fr' as const, label: 'French', nativeLabel: 'Français' }
+  { value: 'fr' as const, label: 'French', nativeLabel: 'Français' },
+  { value: 'zh-CN' as const, label: 'Chinese (Simplified)', nativeLabel: '简体中文' }
 ] as const;
 
 export const DEFAULT_LANGUAGE: SupportedLanguage = 'en';

apps/frontend/src/shared/i18n/index.ts

@@ -27,6 +27,19 @@ import frTaskReview from './locales/fr/taskReview.json';
 import frTerminal from './locales/fr/terminal.json';
 import frErrors from './locales/fr/errors.json';
 
+// Import Chinese (Simplified) translation resources
+import zhCnCommon from './locales/zh-CN/common.json';
+import zhCnNavigation from './locales/zh-CN/navigation.json';
+import zhCnSettings from './locales/zh-CN/settings.json';
+import zhCnTasks from './locales/zh-CN/tasks.json';
+import zhCnWelcome from './locales/zh-CN/welcome.json';
+import zhCnOnboarding from './locales/zh-CN/onboarding.json';
+import zhCnDialogs from './locales/zh-CN/dialogs.json';
+import zhCnGitlab from './locales/zh-CN/gitlab.json';
+import zhCnTaskReview from './locales/zh-CN/taskReview.json';
+import zhCnTerminal from './locales/zh-CN/terminal.json';
+import zhCnErrors from './locales/zh-CN/errors.json';
+
 export const defaultNS = 'common';
 
 export const resources = {
@@ -55,6 +68,19 @@ export const resources = {
     taskReview: frTaskReview,
     terminal: frTerminal,
     errors: frErrors
+  },
+  'zh-CN': {
+    common: zhCnCommon,
+    navigation: zhCnNavigation,
+    settings: zhCnSettings,
+    tasks: zhCnTasks,
+    welcome: zhCnWelcome,
+    onboarding: zhCnOnboarding,
+    dialogs: zhCnDialogs,
+    gitlab: zhCnGitlab,
+    taskReview: zhCnTaskReview,
+    terminal: zhCnTerminal,
+    errors: zhCnErrors
   }
 } as const;