feat(frontend): add multi-language support (en, zh-Hans, zh-Hant, ja)

frontend/l10n.yaml

@@ -0,0 +1,3 @@
+arb-dir: lib/l10n
+template-arb-file: app_en.arb
+output-localization-file: app_localizations.dart

frontend/lib/l10n/app_en.arb

@@ -0,0 +1,70 @@
+{
+  "@@locale": "en",
+  "settings": "Settings",
+  "networkConfiguration": "Network Configuration",
+  "backendServerUrl": "Backend Server URL",
+  "saveNetworkSettings": "Save Network Settings",
+  "serverUrlUpdated": "Server URL Updated",
+  "themeCustomization": "Theme Customization",
+  "appearanceMode": "Appearance Mode",
+  "system": "System",
+  "light": "Light",
+  "dark": "Dark",
+  "accentColor": "Accent Color",
+  "explore": "Explore",
+  "livePreviewThumbnails": "Live Preview Thumbnails",
+  "livePreviewThumbnailsDesc": "Show cached snapshot covers for live rooms when available.",
+  "security": "Security",
+  "oldPassword": "Old Password",
+  "newPassword": "New Password",
+  "changePassword": "Change Password",
+  "logout": "Logout",
+  "confirmLogout": "Confirm Logout",
+  "confirmLogoutDesc": "Are you sure you want to log out now?",
+  "cancel": "Cancel",
+  "language": "Language",
+  "selectLanguage": "Select Language",
+  "english": "English",
+  "simplifiedChinese": "简体中文",
+  "traditionalChinese": "繁體中文",
+  "japanese": "日本語",
+  "console": "Console",
+  "failedToLoadRooms": "Failed to load rooms",
+  "goLive": "Go Live",
+  "noActiveRooms": "No active rooms. Be the first!",
+  "hostId": "Host ID",
+  "username": "Username",
+  "password": "Password",
+  "fillAllFields": "Please fill in all fields",
+  "networkError": "Network Error: Could not connect to server",
+  "loginFailed": "Login Failed",
+  "login": "LOGIN",
+  "dontHaveAccount": "Don't have an account? Create one",
+  "createAccount": "Create Account",
+  "joinHightube": "Join Hightube",
+  "desiredUsername": "Desired Username",
+  "register": "REGISTER",
+  "alreadyHaveAccount": "Already have an account? Login here",
+  "accountCreated": "Account created! Please login.",
+  "playbackResolution": "Playback Resolution",
+  "availableNow": "Available now",
+  "waitingForTranscoding": "Waiting for backend transcoding output",
+  "sendMessage": "Send a message...",
+  "liveChat": "Live Chat",
+  "refresh": "Refresh",
+  "volume": "Volume",
+  "danmakuOn": "Danmaku On",
+  "danmakuOff": "Danmaku Off",
+  "fullscreen": "Fullscreen",
+  "exitFullscreen": "Exit Fullscreen",
+  "resolution": "Resolution",
+  "playbackOptionsDesc": "Select an available transcoded stream.",
+  "sourceOnlyDesc": "Only the source stream is available right now.",
+  "myStreamConsole": "My Stream Console",
+  "noRoomInfo": "No room info found.",
+  "roomTitle": "Room Title",
+  "rtmpServerUrl": "RTMP Server URL",
+  "streamKey": "Stream Key (Keep Secret!)",
+  "copiedToClipboard": "Copied to clipboard",
+  "failedToFetchRoomInfo": "Failed to fetch room info"
+}

frontend/lib/l10n/app_ja.arb

@@ -0,0 +1,70 @@
+{
+  "@@locale": "ja",
+  "settings": "設定",
+  "networkConfiguration": "ネットワーク設定",
+  "backendServerUrl": "バックエンドサーバーURL",
+  "saveNetworkSettings": "ネットワーク設定を保存",
+  "serverUrlUpdated": "サーバーURLが更新されました",
+  "themeCustomization": "テーマのカスタマイズ",
+  "appearanceMode": "外観モード",
+  "system": "システム",
+  "light": "ライト",
+  "dark": "ダーク",
+  "accentColor": "アクセントカラー",
+  "explore": "探索",
+  "livePreviewThumbnails": "ライブプレビューサムネイル",
+  "livePreviewThumbnailsDesc": "利用可能な場合、ライブルームのキャッシュされたスナップショットカバーを表示します。",
+  "security": "セキュリティ",
+  "oldPassword": "現在のパスワード",
+  "newPassword": "新しいパスワード",
+  "changePassword": "パスワードを変更",
+  "logout": "ログアウト",
+  "confirmLogout": "ログアウトの確認",
+  "confirmLogoutDesc": "今すぐログアウトしてもよろしいですか？",
+  "cancel": "キャンセル",
+  "language": "言語",
+  "selectLanguage": "言語を選択",
+  "english": "English",
+  "simplifiedChinese": "简体中文",
+  "traditionalChinese": "繁體中文",
+  "japanese": "日本語",
+  "console": "コンソール",
+  "failedToLoadRooms": "ルームの読み込みに失敗しました",
+  "goLive": "ライブ配信を開始",
+  "noActiveRooms": "配信中のルームはありません。最初の配信者になりましょう！",
+  "hostId": "配信者 ID",
+  "username": "ユーザー名",
+  "password": "パスワード",
+  "fillAllFields": "すべての項目を入力してください",
+  "networkError": "ネットワークエラー：サーバーに接続できませんでした",
+  "loginFailed": "ログインに失敗しました",
+  "login": "ログイン",
+  "dontHaveAccount": "アカウントをお持ちでないですか？新規登録",
+  "createAccount": "アカウント作成",
+  "joinHightube": "Hightube に参加",
+  "desiredUsername": "ユーザー名",
+  "register": "登録",
+  "alreadyHaveAccount": "既にアカウントをお持ちですか？ログイン",
+  "accountCreated": "アカウントが作成されました！ログインしてください。",
+  "playbackResolution": "再生解像度",
+  "availableNow": "利用可能",
+  "waitingForTranscoding": "バックエンドのトランスコード出力を待機中",
+  "sendMessage": "メッセージを送信...",
+  "liveChat": "ライブチャット",
+  "refresh": "更新",
+  "volume": "音量",
+  "danmakuOn": "弾幕オン",
+  "danmakuOff": "弾幕オフ",
+  "fullscreen": "全画面",
+  "exitFullscreen": "全画面終了",
+  "resolution": "解像度",
+  "playbackOptionsDesc": "利用可能なトランスコード済みストリームを選択します。",
+  "sourceOnlyDesc": "現在、ソースストリームのみが利用可能です。",
+  "myStreamConsole": "配信コンソール",
+  "noRoomInfo": "ルーム情報が見つかりません。",
+  "roomTitle": "ルームタイトル",
+  "rtmpServerUrl": "RTMP サーバー URL",
+  "streamKey": "ストリームキー (秘密にしてください!)",
+  "copiedToClipboard": "クリップボードにコピーしました",
+  "failedToFetchRoomInfo": "ルーム情報の取得に失敗しました"
+}

frontend/lib/l10n/app_localizations.dart

@@ -0,0 +1,553 @@
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:intl/intl.dart' as intl;
+
+import 'app_localizations_en.dart';
+import 'app_localizations_ja.dart';
+import 'app_localizations_zh.dart';
+
+// ignore_for_file: type=lint
+
+/// Callers can lookup localized strings with an instance of AppLocalizations
+/// returned by `AppLocalizations.of(context)`.
+///
+/// Applications need to include `AppLocalizations.delegate()` in their app's
+/// `localizationDelegates` list, and the locales they support in the app's
+/// `supportedLocales` list. For example:
+///
+/// ```dart
+/// import 'l10n/app_localizations.dart';
+///
+/// return MaterialApp(
+///   localizationsDelegates: AppLocalizations.localizationsDelegates,
+///   supportedLocales: AppLocalizations.supportedLocales,
+///   home: MyApplicationHome(),
+/// );
+/// ```
+///
+/// ## Update pubspec.yaml
+///
+/// Please make sure to update your pubspec.yaml to include the following
+/// packages:
+///
+/// ```yaml
+/// dependencies:
+///   # Internationalization support.
+///   flutter_localizations:
+///     sdk: flutter
+///   intl: any # Use the pinned version from flutter_localizations
+///
+///   # Rest of dependencies
+/// ```
+///
+/// ## iOS Applications
+///
+/// iOS applications define key application metadata, including supported
+/// locales, in an Info.plist file that is built into the application bundle.
+/// To configure the locales supported by your app, you’ll need to edit this
+/// file.
+///
+/// First, open your project’s ios/Runner.xcworkspace Xcode workspace file.
+/// Then, in the Project Navigator, open the Info.plist file under the Runner
+/// project’s Runner folder.
+///
+/// Next, select the Information Property List item, select Add Item from the
+/// Editor menu, then select Localizations from the pop-up menu.
+///
+/// Select and expand the newly-created Localizations item then, for each
+/// locale your application supports, add a new item and select the locale
+/// you wish to add from the pop-up menu in the Value field. This list should
+/// be consistent with the languages listed in the AppLocalizations.supportedLocales
+/// property.
+abstract class AppLocalizations {
+  AppLocalizations(String locale)
+    : localeName = intl.Intl.canonicalizedLocale(locale.toString());
+
+  final String localeName;
+
+  static AppLocalizations? of(BuildContext context) {
+    return Localizations.of<AppLocalizations>(context, AppLocalizations);
+  }
+
+  static const LocalizationsDelegate<AppLocalizations> delegate =
+      _AppLocalizationsDelegate();
+
+  /// A list of this localizations delegate along with the default localizations
+  /// delegates.
+  ///
+  /// Returns a list of localizations delegates containing this delegate along with
+  /// GlobalMaterialLocalizations.delegate, GlobalCupertinoLocalizations.delegate,
+  /// and GlobalWidgetsLocalizations.delegate.
+  ///
+  /// Additional delegates can be added by appending to this list in
+  /// MaterialApp. This list does not have to be used at all if a custom list
+  /// of delegates is preferred or required.
+  static const List<LocalizationsDelegate<dynamic>> localizationsDelegates =
+      <LocalizationsDelegate<dynamic>>[
+        delegate,
+        GlobalMaterialLocalizations.delegate,
+        GlobalCupertinoLocalizations.delegate,
+        GlobalWidgetsLocalizations.delegate,
+      ];
+
+  /// A list of this localizations delegate's supported locales.
+  static const List<Locale> supportedLocales = <Locale>[
+    Locale('en'),
+    Locale('ja'),
+    Locale('zh'),
+    Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant'),
+  ];
+
+  /// No description provided for @settings.
+  ///
+  /// In en, this message translates to:
+  /// **'Settings'**
+  String get settings;
+
+  /// No description provided for @networkConfiguration.
+  ///
+  /// In en, this message translates to:
+  /// **'Network Configuration'**
+  String get networkConfiguration;
+
+  /// No description provided for @backendServerUrl.
+  ///
+  /// In en, this message translates to:
+  /// **'Backend Server URL'**
+  String get backendServerUrl;
+
+  /// No description provided for @saveNetworkSettings.
+  ///
+  /// In en, this message translates to:
+  /// **'Save Network Settings'**
+  String get saveNetworkSettings;
+
+  /// No description provided for @serverUrlUpdated.
+  ///
+  /// In en, this message translates to:
+  /// **'Server URL Updated'**
+  String get serverUrlUpdated;
+
+  /// No description provided for @themeCustomization.
+  ///
+  /// In en, this message translates to:
+  /// **'Theme Customization'**
+  String get themeCustomization;
+
+  /// No description provided for @appearanceMode.
+  ///
+  /// In en, this message translates to:
+  /// **'Appearance Mode'**
+  String get appearanceMode;
+
+  /// No description provided for @system.
+  ///
+  /// In en, this message translates to:
+  /// **'System'**
+  String get system;
+
+  /// No description provided for @light.
+  ///
+  /// In en, this message translates to:
+  /// **'Light'**
+  String get light;
+
+  /// No description provided for @dark.
+  ///
+  /// In en, this message translates to:
+  /// **'Dark'**
+  String get dark;
+
+  /// No description provided for @accentColor.
+  ///
+  /// In en, this message translates to:
+  /// **'Accent Color'**
+  String get accentColor;
+
+  /// No description provided for @explore.
+  ///
+  /// In en, this message translates to:
+  /// **'Explore'**
+  String get explore;
+
+  /// No description provided for @livePreviewThumbnails.
+  ///
+  /// In en, this message translates to:
+  /// **'Live Preview Thumbnails'**
+  String get livePreviewThumbnails;
+
+  /// No description provided for @livePreviewThumbnailsDesc.
+  ///
+  /// In en, this message translates to:
+  /// **'Show cached snapshot covers for live rooms when available.'**
+  String get livePreviewThumbnailsDesc;
+
+  /// No description provided for @security.
+  ///
+  /// In en, this message translates to:
+  /// **'Security'**
+  String get security;
+
+  /// No description provided for @oldPassword.
+  ///
+  /// In en, this message translates to:
+  /// **'Old Password'**
+  String get oldPassword;
+
+  /// No description provided for @newPassword.
+  ///
+  /// In en, this message translates to:
+  /// **'New Password'**
+  String get newPassword;
+
+  /// No description provided for @changePassword.
+  ///
+  /// In en, this message translates to:
+  /// **'Change Password'**
+  String get changePassword;
+
+  /// No description provided for @logout.
+  ///
+  /// In en, this message translates to:
+  /// **'Logout'**
+  String get logout;
+
+  /// No description provided for @confirmLogout.
+  ///
+  /// In en, this message translates to:
+  /// **'Confirm Logout'**
+  String get confirmLogout;
+
+  /// No description provided for @confirmLogoutDesc.
+  ///
+  /// In en, this message translates to:
+  /// **'Are you sure you want to log out now?'**
+  String get confirmLogoutDesc;
+
+  /// No description provided for @cancel.
+  ///
+  /// In en, this message translates to:
+  /// **'Cancel'**
+  String get cancel;
+
+  /// No description provided for @language.
+  ///
+  /// In en, this message translates to:
+  /// **'Language'**
+  String get language;
+
+  /// No description provided for @selectLanguage.
+  ///
+  /// In en, this message translates to:
+  /// **'Select Language'**
+  String get selectLanguage;
+
+  /// No description provided for @english.
+  ///
+  /// In en, this message translates to:
+  /// **'English'**
+  String get english;
+
+  /// No description provided for @simplifiedChinese.
+  ///
+  /// In en, this message translates to:
+  /// **'简体中文'**
+  String get simplifiedChinese;
+
+  /// No description provided for @traditionalChinese.
+  ///
+  /// In en, this message translates to:
+  /// **'繁體中文'**
+  String get traditionalChinese;
+
+  /// No description provided for @japanese.
+  ///
+  /// In en, this message translates to:
+  /// **'日本語'**
+  String get japanese;
+
+  /// No description provided for @console.
+  ///
+  /// In en, this message translates to:
+  /// **'Console'**
+  String get console;
+
+  /// No description provided for @failedToLoadRooms.
+  ///
+  /// In en, this message translates to:
+  /// **'Failed to load rooms'**
+  String get failedToLoadRooms;
+
+  /// No description provided for @goLive.
+  ///
+  /// In en, this message translates to:
+  /// **'Go Live'**
+  String get goLive;
+
+  /// No description provided for @noActiveRooms.
+  ///
+  /// In en, this message translates to:
+  /// **'No active rooms. Be the first!'**
+  String get noActiveRooms;
+
+  /// No description provided for @hostId.
+  ///
+  /// In en, this message translates to:
+  /// **'Host ID'**
+  String get hostId;
+
+  /// No description provided for @username.
+  ///
+  /// In en, this message translates to:
+  /// **'Username'**
+  String get username;
+
+  /// No description provided for @password.
+  ///
+  /// In en, this message translates to:
+  /// **'Password'**
+  String get password;
+
+  /// No description provided for @fillAllFields.
+  ///
+  /// In en, this message translates to:
+  /// **'Please fill in all fields'**
+  String get fillAllFields;
+
+  /// No description provided for @networkError.
+  ///
+  /// In en, this message translates to:
+  /// **'Network Error: Could not connect to server'**
+  String get networkError;
+
+  /// No description provided for @loginFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'Login Failed'**
+  String get loginFailed;
+
+  /// No description provided for @login.
+  ///
+  /// In en, this message translates to:
+  /// **'LOGIN'**
+  String get login;
+
+  /// No description provided for @dontHaveAccount.
+  ///
+  /// In en, this message translates to:
+  /// **'Don\'t have an account? Create one'**
+  String get dontHaveAccount;
+
+  /// No description provided for @createAccount.
+  ///
+  /// In en, this message translates to:
+  /// **'Create Account'**
+  String get createAccount;
+
+  /// No description provided for @joinHightube.
+  ///
+  /// In en, this message translates to:
+  /// **'Join Hightube'**
+  String get joinHightube;
+
+  /// No description provided for @desiredUsername.
+  ///
+  /// In en, this message translates to:
+  /// **'Desired Username'**
+  String get desiredUsername;
+
+  /// No description provided for @register.
+  ///
+  /// In en, this message translates to:
+  /// **'REGISTER'**
+  String get register;
+
+  /// No description provided for @alreadyHaveAccount.
+  ///
+  /// In en, this message translates to:
+  /// **'Already have an account? Login here'**
+  String get alreadyHaveAccount;
+
+  /// No description provided for @accountCreated.
+  ///
+  /// In en, this message translates to:
+  /// **'Account created! Please login.'**
+  String get accountCreated;
+
+  /// No description provided for @playbackResolution.
+  ///
+  /// In en, this message translates to:
+  /// **'Playback Resolution'**
+  String get playbackResolution;
+
+  /// No description provided for @availableNow.
+  ///
+  /// In en, this message translates to:
+  /// **'Available now'**
+  String get availableNow;
+
+  /// No description provided for @waitingForTranscoding.
+  ///
+  /// In en, this message translates to:
+  /// **'Waiting for backend transcoding output'**
+  String get waitingForTranscoding;
+
+  /// No description provided for @sendMessage.
+  ///
+  /// In en, this message translates to:
+  /// **'Send a message...'**
+  String get sendMessage;
+
+  /// No description provided for @liveChat.
+  ///
+  /// In en, this message translates to:
+  /// **'Live Chat'**
+  String get liveChat;
+
+  /// No description provided for @refresh.
+  ///
+  /// In en, this message translates to:
+  /// **'Refresh'**
+  String get refresh;
+
+  /// No description provided for @volume.
+  ///
+  /// In en, this message translates to:
+  /// **'Volume'**
+  String get volume;
+
+  /// No description provided for @danmakuOn.
+  ///
+  /// In en, this message translates to:
+  /// **'Danmaku On'**
+  String get danmakuOn;
+
+  /// No description provided for @danmakuOff.
+  ///
+  /// In en, this message translates to:
+  /// **'Danmaku Off'**
+  String get danmakuOff;
+
+  /// No description provided for @fullscreen.
+  ///
+  /// In en, this message translates to:
+  /// **'Fullscreen'**
+  String get fullscreen;
+
+  /// No description provided for @exitFullscreen.
+  ///
+  /// In en, this message translates to:
+  /// **'Exit Fullscreen'**
+  String get exitFullscreen;
+
+  /// No description provided for @resolution.
+  ///
+  /// In en, this message translates to:
+  /// **'Resolution'**
+  String get resolution;
+
+  /// No description provided for @playbackOptionsDesc.
+  ///
+  /// In en, this message translates to:
+  /// **'Select an available transcoded stream.'**
+  String get playbackOptionsDesc;
+
+  /// No description provided for @sourceOnlyDesc.
+  ///
+  /// In en, this message translates to:
+  /// **'Only the source stream is available right now.'**
+  String get sourceOnlyDesc;
+
+  /// No description provided for @myStreamConsole.
+  ///
+  /// In en, this message translates to:
+  /// **'My Stream Console'**
+  String get myStreamConsole;
+
+  /// No description provided for @noRoomInfo.
+  ///
+  /// In en, this message translates to:
+  /// **'No room info found.'**
+  String get noRoomInfo;
+
+  /// No description provided for @roomTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Room Title'**
+  String get roomTitle;
+
+  /// No description provided for @rtmpServerUrl.
+  ///
+  /// In en, this message translates to:
+  /// **'RTMP Server URL'**
+  String get rtmpServerUrl;
+
+  /// No description provided for @streamKey.
+  ///
+  /// In en, this message translates to:
+  /// **'Stream Key (Keep Secret!)'**
+  String get streamKey;
+
+  /// No description provided for @copiedToClipboard.
+  ///
+  /// In en, this message translates to:
+  /// **'Copied to clipboard'**
+  String get copiedToClipboard;
+
+  /// No description provided for @failedToFetchRoomInfo.
+  ///
+  /// In en, this message translates to:
+  /// **'Failed to fetch room info'**
+  String get failedToFetchRoomInfo;
+}
+
+class _AppLocalizationsDelegate
+    extends LocalizationsDelegate<AppLocalizations> {
+  const _AppLocalizationsDelegate();
+
+  @override
+  Future<AppLocalizations> load(Locale locale) {
+    return SynchronousFuture<AppLocalizations>(lookupAppLocalizations(locale));
+  }
+
+  @override
+  bool isSupported(Locale locale) =>
+      <String>['en', 'ja', 'zh'].contains(locale.languageCode);
+
+  @override
+  bool shouldReload(_AppLocalizationsDelegate old) => false;
+}
+
+AppLocalizations lookupAppLocalizations(Locale locale) {
+  // Lookup logic when language+script codes are specified.
+  switch (locale.languageCode) {
+    case 'zh':
+      {
+        switch (locale.scriptCode) {
+          case 'Hant':
+            return AppLocalizationsZhHant();
+        }
+        break;
+      }
+  }
+
+  // Lookup logic when only language code is specified.
+  switch (locale.languageCode) {
+    case 'en':
+      return AppLocalizationsEn();
+    case 'ja':
+      return AppLocalizationsJa();
+    case 'zh':
+      return AppLocalizationsZh();
+  }
+
+  throw FlutterError(
+    'AppLocalizations.delegate failed to load unsupported locale "$locale". This is likely '
+    'an issue with the localizations generation tool. Please file an issue '
+    'on GitHub with a reproducible sample app and the gen-l10n configuration '
+    'that was used.',
+  );
+}

frontend/lib/l10n/app_localizations_en.dart

@@ -0,0 +1,212 @@
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'app_localizations.dart';
+
+// ignore_for_file: type=lint
+
+/// The translations for English (`en`).
+class AppLocalizationsEn extends AppLocalizations {
+  AppLocalizationsEn([String locale = 'en']) : super(locale);
+
+  @override
+  String get settings => 'Settings';
+
+  @override
+  String get networkConfiguration => 'Network Configuration';
+
+  @override
+  String get backendServerUrl => 'Backend Server URL';
+
+  @override
+  String get saveNetworkSettings => 'Save Network Settings';
+
+  @override
+  String get serverUrlUpdated => 'Server URL Updated';
+
+  @override
+  String get themeCustomization => 'Theme Customization';
+
+  @override
+  String get appearanceMode => 'Appearance Mode';
+
+  @override
+  String get system => 'System';
+
+  @override
+  String get light => 'Light';
+
+  @override
+  String get dark => 'Dark';
+
+  @override
+  String get accentColor => 'Accent Color';
+
+  @override
+  String get explore => 'Explore';
+
+  @override
+  String get livePreviewThumbnails => 'Live Preview Thumbnails';
+
+  @override
+  String get livePreviewThumbnailsDesc =>
+      'Show cached snapshot covers for live rooms when available.';
+
+  @override
+  String get security => 'Security';
+
+  @override
+  String get oldPassword => 'Old Password';
+
+  @override
+  String get newPassword => 'New Password';
+
+  @override
+  String get changePassword => 'Change Password';
+
+  @override
+  String get logout => 'Logout';
+
+  @override
+  String get confirmLogout => 'Confirm Logout';
+
+  @override
+  String get confirmLogoutDesc => 'Are you sure you want to log out now?';
+
+  @override
+  String get cancel => 'Cancel';
+
+  @override
+  String get language => 'Language';
+
+  @override
+  String get selectLanguage => 'Select Language';
+
+  @override
+  String get english => 'English';
+
+  @override
+  String get simplifiedChinese => '简体中文';
+
+  @override
+  String get traditionalChinese => '繁體中文';
+
+  @override
+  String get japanese => '日本語';
+
+  @override
+  String get console => 'Console';
+
+  @override
+  String get failedToLoadRooms => 'Failed to load rooms';
+
+  @override
+  String get goLive => 'Go Live';
+
+  @override
+  String get noActiveRooms => 'No active rooms. Be the first!';
+
+  @override
+  String get hostId => 'Host ID';
+
+  @override
+  String get username => 'Username';
+
+  @override
+  String get password => 'Password';
+
+  @override
+  String get fillAllFields => 'Please fill in all fields';
+
+  @override
+  String get networkError => 'Network Error: Could not connect to server';
+
+  @override
+  String get loginFailed => 'Login Failed';
+
+  @override
+  String get login => 'LOGIN';
+
+  @override
+  String get dontHaveAccount => 'Don\'t have an account? Create one';
+
+  @override
+  String get createAccount => 'Create Account';
+
+  @override
+  String get joinHightube => 'Join Hightube';
+
+  @override
+  String get desiredUsername => 'Desired Username';
+
+  @override
+  String get register => 'REGISTER';
+
+  @override
+  String get alreadyHaveAccount => 'Already have an account? Login here';
+
+  @override
+  String get accountCreated => 'Account created! Please login.';
+
+  @override
+  String get playbackResolution => 'Playback Resolution';
+
+  @override
+  String get availableNow => 'Available now';
+
+  @override
+  String get waitingForTranscoding => 'Waiting for backend transcoding output';
+
+  @override
+  String get sendMessage => 'Send a message...';
+
+  @override
+  String get liveChat => 'Live Chat';
+
+  @override
+  String get refresh => 'Refresh';
+
+  @override
+  String get volume => 'Volume';
+
+  @override
+  String get danmakuOn => 'Danmaku On';
+
+  @override
+  String get danmakuOff => 'Danmaku Off';
+
+  @override
+  String get fullscreen => 'Fullscreen';
+
+  @override
+  String get exitFullscreen => 'Exit Fullscreen';
+
+  @override
+  String get resolution => 'Resolution';
+
+  @override
+  String get playbackOptionsDesc => 'Select an available transcoded stream.';
+
+  @override
+  String get sourceOnlyDesc => 'Only the source stream is available right now.';
+
+  @override
+  String get myStreamConsole => 'My Stream Console';
+
+  @override
+  String get noRoomInfo => 'No room info found.';
+
+  @override
+  String get roomTitle => 'Room Title';
+
+  @override
+  String get rtmpServerUrl => 'RTMP Server URL';
+
+  @override
+  String get streamKey => 'Stream Key (Keep Secret!)';
+
+  @override
+  String get copiedToClipboard => 'Copied to clipboard';
+
+  @override
+  String get failedToFetchRoomInfo => 'Failed to fetch room info';
+}

frontend/lib/l10n/app_localizations_ja.dart

@@ -0,0 +1,212 @@
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'app_localizations.dart';
+
+// ignore_for_file: type=lint
+
+/// The translations for Japanese (`ja`).
+class AppLocalizationsJa extends AppLocalizations {
+  AppLocalizationsJa([String locale = 'ja']) : super(locale);
+
+  @override
+  String get settings => '設定';
+
+  @override
+  String get networkConfiguration => 'ネットワーク設定';
+
+  @override
+  String get backendServerUrl => 'バックエンドサーバーURL';
+
+  @override
+  String get saveNetworkSettings => 'ネットワーク設定を保存';
+
+  @override
+  String get serverUrlUpdated => 'サーバーURLが更新されました';
+
+  @override
+  String get themeCustomization => 'テーマのカスタマイズ';
+
+  @override
+  String get appearanceMode => '外観モード';
+
+  @override
+  String get system => 'システム';
+
+  @override
+  String get light => 'ライト';
+
+  @override
+  String get dark => 'ダーク';
+
+  @override
+  String get accentColor => 'アクセントカラー';
+
+  @override
+  String get explore => '探索';
+
+  @override
+  String get livePreviewThumbnails => 'ライブプレビューサムネイル';
+
+  @override
+  String get livePreviewThumbnailsDesc =>
+      '利用可能な場合、ライブルームのキャッシュされたスナップショットカバーを表示します。';
+
+  @override
+  String get security => 'セキュリティ';
+
+  @override
+  String get oldPassword => '現在のパスワード';
+
+  @override
+  String get newPassword => '新しいパスワード';
+
+  @override
+  String get changePassword => 'パスワードを変更';
+
+  @override
+  String get logout => 'ログアウト';
+
+  @override
+  String get confirmLogout => 'ログアウトの確認';
+
+  @override
+  String get confirmLogoutDesc => '今すぐログアウトしてもよろしいですか？';
+
+  @override
+  String get cancel => 'キャンセル';
+
+  @override
+  String get language => '言語';
+
+  @override
+  String get selectLanguage => '言語を選択';
+
+  @override
+  String get english => 'English';
+
+  @override
+  String get simplifiedChinese => '简体中文';
+
+  @override
+  String get traditionalChinese => '繁體中文';
+
+  @override
+  String get japanese => '日本語';
+
+  @override
+  String get console => 'コンソール';
+
+  @override
+  String get failedToLoadRooms => 'ルームの読み込みに失敗しました';
+
+  @override
+  String get goLive => 'ライブ配信を開始';
+
+  @override
+  String get noActiveRooms => '配信中のルームはありません。最初の配信者になりましょう！';
+
+  @override
+  String get hostId => '配信者 ID';
+
+  @override
+  String get username => 'ユーザー名';
+
+  @override
+  String get password => 'パスワード';
+
+  @override
+  String get fillAllFields => 'すべての項目を入力してください';
+
+  @override
+  String get networkError => 'ネットワークエラー：サーバーに接続できませんでした';
+
+  @override
+  String get loginFailed => 'ログインに失敗しました';
+
+  @override
+  String get login => 'ログイン';
+
+  @override
+  String get dontHaveAccount => 'アカウントをお持ちでないですか？新規登録';
+
+  @override
+  String get createAccount => 'アカウント作成';
+
+  @override
+  String get joinHightube => 'Hightube に参加';
+
+  @override
+  String get desiredUsername => 'ユーザー名';
+
+  @override
+  String get register => '登録';
+
+  @override
+  String get alreadyHaveAccount => '既にアカウントをお持ちですか？ログイン';
+
+  @override
+  String get accountCreated => 'アカウントが作成されました！ログインしてください。';
+
+  @override
+  String get playbackResolution => '再生解像度';
+
+  @override
+  String get availableNow => '利用可能';
+
+  @override
+  String get waitingForTranscoding => 'バックエンドのトランスコード出力を待機中';
+
+  @override
+  String get sendMessage => 'メッセージを送信...';
+
+  @override
+  String get liveChat => 'ライブチャット';
+
+  @override
+  String get refresh => '更新';
+
+  @override
+  String get volume => '音量';
+
+  @override
+  String get danmakuOn => '弾幕オン';
+
+  @override
+  String get danmakuOff => '弾幕オフ';
+
+  @override
+  String get fullscreen => '全画面';
+
+  @override
+  String get exitFullscreen => '全画面終了';
+
+  @override
+  String get resolution => '解像度';
+
+  @override
+  String get playbackOptionsDesc => '利用可能なトランスコード済みストリームを選択します。';
+
+  @override
+  String get sourceOnlyDesc => '現在、ソースストリームのみが利用可能です。';
+
+  @override
+  String get myStreamConsole => '配信コンソール';
+
+  @override
+  String get noRoomInfo => 'ルーム情報が見つかりません。';
+
+  @override
+  String get roomTitle => 'ルームタイトル';
+
+  @override
+  String get rtmpServerUrl => 'RTMP サーバー URL';
+
+  @override
+  String get streamKey => 'ストリームキー (秘密にしてください!)';
+
+  @override
+  String get copiedToClipboard => 'クリップボードにコピーしました';
+
+  @override
+  String get failedToFetchRoomInfo => 'ルーム情報の取得に失敗しました';
+}

frontend/lib/l10n/app_localizations_zh.dart

@@ -0,0 +1,417 @@
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'app_localizations.dart';
+
+// ignore_for_file: type=lint
+
+/// The translations for Chinese (`zh`).
+class AppLocalizationsZh extends AppLocalizations {
+  AppLocalizationsZh([String locale = 'zh']) : super(locale);
+
+  @override
+  String get settings => '设置';
+
+  @override
+  String get networkConfiguration => '网络配置';
+
+  @override
+  String get backendServerUrl => '后端服务器地址';
+
+  @override
+  String get saveNetworkSettings => '保存网络设置';
+
+  @override
+  String get serverUrlUpdated => '服务器地址已更新';
+
+  @override
+  String get themeCustomization => '主题自定义';
+
+  @override
+  String get appearanceMode => '外观模式';
+
+  @override
+  String get system => '系统';
+
+  @override
+  String get light => '浅色';
+
+  @override
+  String get dark => '深色';
+
+  @override
+  String get accentColor => '强调色';
+
+  @override
+  String get explore => '探索';
+
+  @override
+  String get livePreviewThumbnails => '直播预览图';
+
+  @override
+  String get livePreviewThumbnailsDesc => '在可用时显示直播房间的缓存快照封面。';
+
+  @override
+  String get security => '安全';
+
+  @override
+  String get oldPassword => '旧密码';
+
+  @override
+  String get newPassword => '新密码';
+
+  @override
+  String get changePassword => '修改密码';
+
+  @override
+  String get logout => '退出登录';
+
+  @override
+  String get confirmLogout => '确认退出';
+
+  @override
+  String get confirmLogoutDesc => '您确定现在要退出登录吗？';
+
+  @override
+  String get cancel => '取消';
+
+  @override
+  String get language => '语言';
+
+  @override
+  String get selectLanguage => '选择语言';
+
+  @override
+  String get english => 'English';
+
+  @override
+  String get simplifiedChinese => '简体中文';
+
+  @override
+  String get traditionalChinese => '繁體中文';
+
+  @override
+  String get japanese => '日本語';
+
+  @override
+  String get console => '控制台';
+
+  @override
+  String get failedToLoadRooms => '加载房间失败';
+
+  @override
+  String get goLive => '开始直播';
+
+  @override
+  String get noActiveRooms => '暂无直播房间。快来开播吧！';
+
+  @override
+  String get hostId => '主播 ID';
+
+  @override
+  String get username => '用户名';
+
+  @override
+  String get password => '密码';
+
+  @override
+  String get fillAllFields => '请填写所有字段';
+
+  @override
+  String get networkError => '网络错误：无法连接到服务器';
+
+  @override
+  String get loginFailed => '登录失败';
+
+  @override
+  String get login => '登录';
+
+  @override
+  String get dontHaveAccount => '没有账号？立即注册';
+
+  @override
+  String get createAccount => '创建账号';
+
+  @override
+  String get joinHightube => '加入 Hightube';
+
+  @override
+  String get desiredUsername => '用户名';
+
+  @override
+  String get register => '注册';
+
+  @override
+  String get alreadyHaveAccount => '已有账号？立即登录';
+
+  @override
+  String get accountCreated => '账号创建成功！请登录。';
+
+  @override
+  String get playbackResolution => '播放分辨率';
+
+  @override
+  String get availableNow => '当前可用';
+
+  @override
+  String get waitingForTranscoding => '正在等待后端转码输出';
+
+  @override
+  String get sendMessage => '发送消息...';
+
+  @override
+  String get liveChat => '实时聊天';
+
+  @override
+  String get refresh => '刷新';
+
+  @override
+  String get volume => '音量';
+
+  @override
+  String get danmakuOn => '弹幕开启';
+
+  @override
+  String get danmakuOff => '弹幕关闭';
+
+  @override
+  String get fullscreen => '全屏';
+
+  @override
+  String get exitFullscreen => '退出全屏';
+
+  @override
+  String get resolution => '分辨率';
+
+  @override
+  String get playbackOptionsDesc => '选择可用的转码流。';
+
+  @override
+  String get sourceOnlyDesc => '目前仅源流可用。';
+
+  @override
+  String get myStreamConsole => '我的直播控制台';
+
+  @override
+  String get noRoomInfo => '未找到房间信息。';
+
+  @override
+  String get roomTitle => '房间标题';
+
+  @override
+  String get rtmpServerUrl => 'RTMP 服务器地址';
+
+  @override
+  String get streamKey => '推流码 (请务必保密!)';
+
+  @override
+  String get copiedToClipboard => '已复制到剪贴板';
+
+  @override
+  String get failedToFetchRoomInfo => '获取房间信息失败';
+}
+
+/// The translations for Chinese, using the Han script (`zh_Hant`).
+class AppLocalizationsZhHant extends AppLocalizationsZh {
+  AppLocalizationsZhHant() : super('zh_Hant');
+
+  @override
+  String get settings => '設定';
+
+  @override
+  String get networkConfiguration => '網路設定';
+
+  @override
+  String get backendServerUrl => '後端伺服器地址';
+
+  @override
+  String get saveNetworkSettings => '儲存網路設定';
+
+  @override
+  String get serverUrlUpdated => '伺服器地址已更新';
+
+  @override
+  String get themeCustomization => '主題自訂';
+
+  @override
+  String get appearanceMode => '外觀模式';
+
+  @override
+  String get system => '系統';
+
+  @override
+  String get light => '淺色';
+
+  @override
+  String get dark => '深色';
+
+  @override
+  String get accentColor => '強調色';
+
+  @override
+  String get explore => '探索';
+
+  @override
+  String get livePreviewThumbnails => '直播預覽圖';
+
+  @override
+  String get livePreviewThumbnailsDesc => '在可用時顯示直播房間的快取快照封面。';
+
+  @override
+  String get security => '安全';
+
+  @override
+  String get oldPassword => '舊密碼';
+
+  @override
+  String get newPassword => '新密碼';
+
+  @override
+  String get changePassword => '修改密碼';
+
+  @override
+  String get logout => '登出';
+
+  @override
+  String get confirmLogout => '確認登出';
+
+  @override
+  String get confirmLogoutDesc => '您確定現在要登出嗎？';
+
+  @override
+  String get cancel => '取消';
+
+  @override
+  String get language => '語言';
+
+  @override
+  String get selectLanguage => '選擇語言';
+
+  @override
+  String get english => 'English';
+
+  @override
+  String get simplifiedChinese => '简体中文';
+
+  @override
+  String get traditionalChinese => '繁體中文';
+
+  @override
+  String get japanese => '日本語';
+
+  @override
+  String get console => '控制台';
+
+  @override
+  String get failedToLoadRooms => '載入房間失敗';
+
+  @override
+  String get goLive => '開始直播';
+
+  @override
+  String get noActiveRooms => '暫無直播房間。快來開播吧！';
+
+  @override
+  String get hostId => '主播 ID';
+
+  @override
+  String get username => '用戶名';
+
+  @override
+  String get password => '密碼';
+
+  @override
+  String get fillAllFields => '請填寫所有欄位';
+
+  @override
+  String get networkError => '網路錯誤：無法連接到伺服器';
+
+  @override
+  String get loginFailed => '登錄失敗';
+
+  @override
+  String get login => '登錄';
+
+  @override
+  String get dontHaveAccount => '沒有帳號？立即註冊';
+
+  @override
+  String get createAccount => '建立帳號';
+
+  @override
+  String get joinHightube => '加入 Hightube';
+
+  @override
+  String get desiredUsername => '用戶名';
+
+  @override
+  String get register => '註冊';
+
+  @override
+  String get alreadyHaveAccount => '已有帳號？立即登錄';
+
+  @override
+  String get accountCreated => '帳號建立成功！請登錄。';
+
+  @override
+  String get playbackResolution => '播放解析度';
+
+  @override
+  String get availableNow => '目前可用';
+
+  @override
+  String get waitingForTranscoding => '正在等待後端轉碼輸出';
+
+  @override
+  String get sendMessage => '發送訊息...';
+
+  @override
+  String get liveChat => '即時聊天';
+
+  @override
+  String get refresh => '重新整理';
+
+  @override
+  String get volume => '音量';
+
+  @override
+  String get danmakuOn => '彈幕開啟';
+
+  @override
+  String get danmakuOff => '彈幕關閉';
+
+  @override
+  String get fullscreen => '全屏';
+
+  @override
+  String get exitFullscreen => '退出全屏';
+
+  @override
+  String get resolution => '解析度';
+
+  @override
+  String get playbackOptionsDesc => '選擇可用的轉碼流。';
+
+  @override
+  String get sourceOnlyDesc => '目前僅源流可用。';
+
+  @override
+  String get myStreamConsole => '我的直播控制台';
+
+  @override
+  String get noRoomInfo => '未找到房間資訊。';
+
+  @override
+  String get roomTitle => '房間標題';
+
+  @override
+  String get rtmpServerUrl => 'RTMP 伺服器地址';
+
+  @override
+  String get streamKey => '推流碼 (請務必保密!)';
+
+  @override
+  String get copiedToClipboard => '已複製到剪貼板';
+
+  @override
+  String get failedToFetchRoomInfo => '獲取房間資訊失敗';
+}

frontend/lib/l10n/app_zh.arb

@@ -0,0 +1,70 @@
+{
+  "@@locale": "zh",
+  "settings": "设置",
+  "networkConfiguration": "网络配置",
+  "backendServerUrl": "后端服务器地址",
+  "saveNetworkSettings": "保存网络设置",
+  "serverUrlUpdated": "服务器地址已更新",
+  "themeCustomization": "主题自定义",
+  "appearanceMode": "外观模式",
+  "system": "系统",
+  "light": "浅色",
+  "dark": "深色",
+  "accentColor": "强调色",
+  "explore": "探索",
+  "livePreviewThumbnails": "直播预览图",
+  "livePreviewThumbnailsDesc": "在可用时显示直播房间的缓存快照封面。",
+  "security": "安全",
+  "oldPassword": "旧密码",
+  "newPassword": "新密码",
+  "changePassword": "修改密码",
+  "logout": "退出登录",
+  "confirmLogout": "确认退出",
+  "confirmLogoutDesc": "您确定现在要退出登录吗？",
+  "cancel": "取消",
+  "language": "语言",
+  "selectLanguage": "选择语言",
+  "english": "English",
+  "simplifiedChinese": "简体中文",
+  "traditionalChinese": "繁體中文",
+  "japanese": "日本語",
+  "console": "控制台",
+  "failedToLoadRooms": "加载房间失败",
+  "goLive": "开始直播",
+  "noActiveRooms": "暂无直播房间。快来开播吧！",
+  "hostId": "主播 ID",
+  "username": "用户名",
+  "password": "密码",
+  "fillAllFields": "请填写所有字段",
+  "networkError": "网络错误：无法连接到服务器",
+  "loginFailed": "登录失败",
+  "login": "登录",
+  "dontHaveAccount": "没有账号？立即注册",
+  "createAccount": "创建账号",
+  "joinHightube": "加入 Hightube",
+  "desiredUsername": "用户名",
+  "register": "注册",
+  "alreadyHaveAccount": "已有账号？立即登录",
+  "accountCreated": "账号创建成功！请登录。",
+  "playbackResolution": "播放分辨率",
+  "availableNow": "当前可用",
+  "waitingForTranscoding": "正在等待后端转码输出",
+  "sendMessage": "发送消息...",
+  "liveChat": "实时聊天",
+  "refresh": "刷新",
+  "volume": "音量",
+  "danmakuOn": "弹幕开启",
+  "danmakuOff": "弹幕关闭",
+  "fullscreen": "全屏",
+  "exitFullscreen": "退出全屏",
+  "resolution": "分辨率",
+  "playbackOptionsDesc": "选择可用的转码流。",
+  "sourceOnlyDesc": "目前仅源流可用。",
+  "myStreamConsole": "我的直播控制台",
+  "noRoomInfo": "未找到房间信息。",
+  "roomTitle": "房间标题",
+  "rtmpServerUrl": "RTMP 服务器地址",
+  "streamKey": "推流码 (请务必保密!)",
+  "copiedToClipboard": "已复制到剪贴板",
+  "failedToFetchRoomInfo": "获取房间信息失败"
+}

frontend/lib/l10n/app_zh_Hant.arb

@@ -0,0 +1,70 @@
+{
+  "@@locale": "zh_Hant",
+  "settings": "設定",
+  "networkConfiguration": "網路設定",
+  "backendServerUrl": "後端伺服器地址",
+  "saveNetworkSettings": "儲存網路設定",
+  "serverUrlUpdated": "伺服器地址已更新",
+  "themeCustomization": "主題自訂",
+  "appearanceMode": "外觀模式",
+  "system": "系統",
+  "light": "淺色",
+  "dark": "深色",
+  "accentColor": "強調色",
+  "explore": "探索",
+  "livePreviewThumbnails": "直播預覽圖",
+  "livePreviewThumbnailsDesc": "在可用時顯示直播房間的快取快照封面。",
+  "security": "安全",
+  "oldPassword": "舊密碼",
+  "newPassword": "新密碼",
+  "changePassword": "修改密碼",
+  "logout": "登出",
+  "confirmLogout": "確認登出",
+  "confirmLogoutDesc": "您確定現在要登出嗎？",
+  "cancel": "取消",
+  "language": "語言",
+  "selectLanguage": "選擇語言",
+  "english": "English",
+  "simplifiedChinese": "简体中文",
+  "traditionalChinese": "繁體中文",
+  "japanese": "日本語",
+  "console": "控制台",
+  "failedToLoadRooms": "載入房間失敗",
+  "goLive": "開始直播",
+  "noActiveRooms": "暫無直播房間。快來開播吧！",
+  "hostId": "主播 ID",
+  "username": "用戶名",
+  "password": "密碼",
+  "fillAllFields": "請填寫所有欄位",
+  "networkError": "網路錯誤：無法連接到伺服器",
+  "loginFailed": "登錄失敗",
+  "login": "登錄",
+  "dontHaveAccount": "沒有帳號？立即註冊",
+  "createAccount": "建立帳號",
+  "joinHightube": "加入 Hightube",
+  "desiredUsername": "用戶名",
+  "register": "註冊",
+  "alreadyHaveAccount": "已有帳號？立即登錄",
+  "accountCreated": "帳號建立成功！請登錄。",
+  "playbackResolution": "播放解析度",
+  "availableNow": "目前可用",
+  "waitingForTranscoding": "正在等待後端轉碼輸出",
+  "sendMessage": "發送訊息...",
+  "liveChat": "即時聊天",
+  "refresh": "重新整理",
+  "volume": "音量",
+  "danmakuOn": "彈幕開啟",
+  "danmakuOff": "彈幕關閉",
+  "fullscreen": "全屏",
+  "exitFullscreen": "退出全屏",
+  "resolution": "解析度",
+  "playbackOptionsDesc": "選擇可用的轉碼流。",
+  "sourceOnlyDesc": "目前僅源流可用。",
+  "myStreamConsole": "我的直播控制台",
+  "noRoomInfo": "未找到房間資訊。",
+  "roomTitle": "房間標題",
+  "rtmpServerUrl": "RTMP 伺服器地址",
+  "streamKey": "推流碼 (請務必保密!)",
+  "copiedToClipboard": "已複製到剪貼板",
+  "failedToFetchRoomInfo": "獲取房間資訊失敗"
+}

frontend/lib/main.dart

@@ -1,10 +1,12 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:provider/provider.dart';
 import 'package:fvp/fvp.dart' as fvp;
 import 'providers/auth_provider.dart';
 import 'providers/settings_provider.dart';
 import 'pages/home_page.dart';
 import 'pages/login_page.dart';
+import 'l10n/app_localizations.dart';
 
 void main() {
   fvp.registerWith();
@@ -30,6 +32,14 @@ class HightubeApp extends StatelessWidget {
 
     return MaterialApp(
       title: 'Hightube',
+      localizationsDelegates: const [
+        AppLocalizations.delegate,
+        GlobalMaterialLocalizations.delegate,
+        GlobalWidgetsLocalizations.delegate,
+        GlobalCupertinoLocalizations.delegate,
+      ],
+      supportedLocales: AppLocalizations.supportedLocales,
+      locale: settings.locale,
       theme: ThemeData(
         useMaterial3: true,
         colorScheme: ColorScheme.fromSeed(

frontend/lib/pages/home_page.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
+import '../l10n/app_localizations.dart';
 import '../providers/auth_provider.dart';
 import '../providers/settings_provider.dart';
 import '../services/api_service.dart';
@@ -22,6 +23,7 @@ class _HomePageState extends State<HomePage> {
   @override
   Widget build(BuildContext context) {
     bool isWide = MediaQuery.of(context).size.width > 600;
+    final l10n = AppLocalizations.of(context)!;
 
     final List<Widget> pages = [
       _ExploreView(onGoLive: () => setState(() => _selectedIndex = 1)),
@@ -38,18 +40,18 @@ class _HomePageState extends State<HomePage> {
               onDestinationSelected: (int index) =>
                   setState(() => _selectedIndex = index),
               labelType: NavigationRailLabelType.all,
-              destinations: const [
+              destinations: [
                 NavigationRailDestination(
-                  icon: Icon(Icons.explore),
+                  icon: const Icon(Icons.explore),
-                  label: Text('Explore'),
+                  label: Text(l10n.explore),
                 ),
                 NavigationRailDestination(
-                  icon: Icon(Icons.videocam),
+                  icon: const Icon(Icons.videocam),
-                  label: Text('Console'),
+                  label: Text(l10n.console),
                 ),
                 NavigationRailDestination(
-                  icon: Icon(Icons.settings),
+                  icon: const Icon(Icons.settings),
-                  label: Text('Settings'),
+                  label: Text(l10n.settings),
                 ),
               ],
             ),
@@ -61,18 +63,18 @@ class _HomePageState extends State<HomePage> {
               selectedIndex: _selectedIndex,
               onDestinationSelected: (int index) =>
                   setState(() => _selectedIndex = index),
-              destinations: const [
+              destinations: [
                 NavigationDestination(
-                  icon: Icon(Icons.explore),
+                  icon: const Icon(Icons.explore),
-                  label: 'Explore',
+                  label: l10n.explore,
                 ),
                 NavigationDestination(
-                  icon: Icon(Icons.videocam),
+                  icon: const Icon(Icons.videocam),
-                  label: 'Console',
+                  label: l10n.console,
                 ),
                 NavigationDestination(
-                  icon: Icon(Icons.settings),
+                  icon: const Icon(Icons.settings),
-                  label: 'Settings',
+                  label: l10n.settings,
                 ),
               ],
             )
@@ -131,9 +133,10 @@ class _ExploreViewState extends State<_ExploreView> {
       }
     } catch (e) {
       if (!isAuto && mounted) {
+        final l10n = AppLocalizations.of(context);
         ScaffoldMessenger.of(
           context,
-        ).showSnackBar(SnackBar(content: Text("Failed to load rooms")));
+        ).showSnackBar(SnackBar(content: Text(l10n?.failedToLoadRooms ?? "Failed to load rooms")));
       }
     } finally {
       if (!isAuto && mounted) setState(() => _isLoading = false);
@@ -141,20 +144,21 @@ class _ExploreViewState extends State<_ExploreView> {
   }
 
   Future<void> _confirmLogout() async {
+    final l10n = AppLocalizations.of(context)!;
     final confirmed = await showDialog<bool>(
       context: context,
       builder: (context) {
         return AlertDialog(
-          title: const Text('Confirm Logout'),
+          title: Text(l10n.confirmLogout),
-          content: const Text('Are you sure you want to log out now?'),
+          content: Text(l10n.confirmLogoutDesc),
           actions: [
             TextButton(
               onPressed: () => Navigator.pop(context, false),
-              child: const Text('Cancel'),
+              child: Text(l10n.cancel),
             ),
             FilledButton(
               onPressed: () => Navigator.pop(context, true),
-              child: const Text('Logout'),
+              child: Text(l10n.logout),
             ),
           ],
         );
@@ -169,44 +173,45 @@ class _ExploreViewState extends State<_ExploreView> {
   @override
   Widget build(BuildContext context) {
     final settings = context.watch<SettingsProvider>();
+    final l10n = AppLocalizations.of(context)!;
 
     return Scaffold(
       appBar: AppBar(
-        title: Text("Explore", style: TextStyle(fontWeight: FontWeight.bold)),
+        title: Text(l10n.explore, style: const TextStyle(fontWeight: FontWeight.bold)),
         actions: [
           IconButton(
-            icon: Icon(Icons.refresh),
+            icon: const Icon(Icons.refresh),
             onPressed: () => _refreshRooms(),
           ),
-          IconButton(icon: Icon(Icons.logout), onPressed: _confirmLogout),
+          IconButton(icon: const Icon(Icons.logout), onPressed: _confirmLogout),
         ],
       ),
       floatingActionButton: FloatingActionButton.extended(
         onPressed: widget.onGoLive,
-        label: Text("Go Live"),
+        label: Text(l10n.goLive),
-        icon: Icon(Icons.videocam),
+        icon: const Icon(Icons.videocam),
       ),
       body: RefreshIndicator(
         onRefresh: _refreshRooms,
         child: _isLoading && _activeRooms.isEmpty
-            ? Center(child: CircularProgressIndicator())
+            ? const Center(child: CircularProgressIndicator())
             : _activeRooms.isEmpty
             ? ListView(
                 children: [
                   Padding(
-                    padding: EdgeInsets.only(top: 100),
+                    padding: const EdgeInsets.only(top: 100),
                     child: Column(
                       mainAxisAlignment: MainAxisAlignment.center,
                       children: [
-                        Icon(
+                        const Icon(
                           Icons.live_tv_outlined,
                           size: 80,
                           color: Colors.grey,
                         ),
-                        SizedBox(height: 16),
+                        const SizedBox(height: 16),
                         Text(
-                          "No active rooms. Be the first!",
+                          l10n.noActiveRooms,
-                          style: TextStyle(color: Colors.grey, fontSize: 16),
+                          style: const TextStyle(color: Colors.grey, fontSize: 16),
                         ),
                       ],
                     ),
@@ -214,8 +219,8 @@ class _ExploreViewState extends State<_ExploreView> {
                 ],
               )
             : GridView.builder(
-                padding: EdgeInsets.all(12),
+                padding: const EdgeInsets.all(12),
-                gridDelegate: SliverGridDelegateWithMaxCrossAxisExtent(
+                gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(
                   maxCrossAxisExtent: 400,
                   childAspectRatio: 1.2,
                   crossAxisSpacing: 12,
@@ -224,14 +229,14 @@ class _ExploreViewState extends State<_ExploreView> {
                 itemCount: _activeRooms.length,
                 itemBuilder: (context, index) {
                   final room = _activeRooms[index];
-                  return _buildRoomCard(room, settings);
+                  return _buildRoomCard(room, settings, l10n);
                 },
               ),
       ),
     );
   }
 
-  Widget _buildRoomCard(dynamic room, SettingsProvider settings) {
+  Widget _buildRoomCard(dynamic room, SettingsProvider settings, AppLocalizations l10n) {
     final roomId = room['room_id'].toString();
     return Card(
       elevation: 4,
@@ -294,12 +299,12 @@ class _ExploreViewState extends State<_ExploreView> {
                     top: 8,
                     left: 8,
                     child: Container(
-                      padding: EdgeInsets.symmetric(horizontal: 8, vertical: 4),
+                      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
                       decoration: BoxDecoration(
                         color: Colors.red,
                         borderRadius: BorderRadius.circular(4),
                       ),
-                      child: Row(
+                      child: const Row(
                         children: [
                           Icon(Icons.circle, size: 8, color: Colors.white),
                           SizedBox(width: 4),
@@ -331,7 +336,7 @@ class _ExploreViewState extends State<_ExploreView> {
                       radius: 16,
                       child: Text(room['user_id'].toString().substring(0, 1)),
                     ),
-                    SizedBox(width: 12),
+                    const SizedBox(width: 12),
                     Expanded(
                       child: Column(
                         mainAxisAlignment: MainAxisAlignment.center,
@@ -341,14 +346,14 @@ class _ExploreViewState extends State<_ExploreView> {
                             room['title'],
                             maxLines: 1,
                             overflow: TextOverflow.ellipsis,
-                            style: TextStyle(
+                            style: const TextStyle(
                               fontWeight: FontWeight.bold,
                               fontSize: 14,
                             ),
                           ),
                           Text(
-                            "Host ID: ${room['user_id']}",
+                            "${l10n.hostId}: ${room['user_id']}",
-                            style: TextStyle(fontSize: 12, color: Colors.grey),
+                            style: const TextStyle(fontSize: 12, color: Colors.grey),
                           ),
                         ],
                       ),

frontend/lib/pages/login_page.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
+import '../l10n/app_localizations.dart';
 import '../providers/auth_provider.dart';
 import '../providers/settings_provider.dart';
 import '../services/api_service.dart';
@@ -29,10 +30,11 @@ class _LoginPageState extends State<LoginPage> {
   }
 
   void _handleLogin() async {
+    final l10n = AppLocalizations.of(context)!;
     if (_usernameController.text.isEmpty || _passwordController.text.isEmpty) {
       ScaffoldMessenger.of(
         context,
-      ).showSnackBar(SnackBar(content: Text("Please fill in all fields")));
+      ).showSnackBar(SnackBar(content: Text(l10n.fillAllFields)));
       return;
     }
 
@@ -53,7 +55,7 @@ class _LoginPageState extends State<LoginPage> {
         if (!mounted) {
           return;
         }
-        final error = jsonDecode(response.body)['error'] ?? "Login Failed";
+        final error = jsonDecode(response.body)['error'] ?? l10n.loginFailed;
         ScaffoldMessenger.of(
           context,
         ).showSnackBar(SnackBar(content: Text(error)));
@@ -63,7 +65,7 @@ class _LoginPageState extends State<LoginPage> {
         return;
       }
       ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text("Network Error: Could not connect to server")),
+        SnackBar(content: Text(l10n.networkError)),
       );
     } finally {
       if (mounted) setState(() => _isLoading = false);
@@ -72,11 +74,13 @@ class _LoginPageState extends State<LoginPage> {
 
   @override
   Widget build(BuildContext context) {
+    final l10n = AppLocalizations.of(context)!;
+
     return Scaffold(
       appBar: AppBar(
         actions: [
           IconButton(
-            icon: Icon(Icons.settings),
+            icon: const Icon(Icons.settings),
             onPressed: () => Navigator.push(
               context,
               MaterialPageRoute(builder: (_) => const SettingsPage()),
@@ -88,7 +92,7 @@ class _LoginPageState extends State<LoginPage> {
         child: SingleChildScrollView(
           padding: const EdgeInsets.symmetric(horizontal: 32.0),
           child: ConstrainedBox(
-            constraints: BoxConstraints(maxWidth: 400),
+            constraints: const BoxConstraints(maxWidth: 400),
             child: Column(
               mainAxisAlignment: MainAxisAlignment.center,
               children: [
@@ -98,7 +102,7 @@ class _LoginPageState extends State<LoginPage> {
                   size: 80,
                   color: Theme.of(context).colorScheme.primary,
                 ),
-                SizedBox(height: 16),
+                const SizedBox(height: 16),
                 Text(
                   "HIGHTUBE",
                   style: TextStyle(
@@ -108,11 +112,11 @@ class _LoginPageState extends State<LoginPage> {
                     color: Theme.of(context).colorScheme.primary,
                   ),
                 ),
-                Text(
+                const Text(
                   "Open Source Live Platform",
                   style: TextStyle(color: Colors.grey),
                 ),
-                SizedBox(height: 48),
+                const SizedBox(height: 48),
 
                 // Fields
                 TextField(
@@ -120,14 +124,14 @@ class _LoginPageState extends State<LoginPage> {
                   textInputAction: TextInputAction.next,
                   onSubmitted: (_) => _passwordFocusNode.requestFocus(),
                   decoration: InputDecoration(
-                    labelText: "Username",
+                    labelText: l10n.username,
-                    prefixIcon: Icon(Icons.person),
+                    prefixIcon: const Icon(Icons.person),
                     border: OutlineInputBorder(
                       borderRadius: BorderRadius.circular(12),
                     ),
                   ),
                 ),
-                SizedBox(height: 16),
+                const SizedBox(height: 16),
                 TextField(
                   controller: _passwordController,
                   focusNode: _passwordFocusNode,
@@ -139,14 +143,14 @@ class _LoginPageState extends State<LoginPage> {
                     }
                   },
                   decoration: InputDecoration(
-                    labelText: "Password",
+                    labelText: l10n.password,
-                    prefixIcon: Icon(Icons.lock),
+                    prefixIcon: const Icon(Icons.lock),
                     border: OutlineInputBorder(
                       borderRadius: BorderRadius.circular(12),
                     ),
                   ),
                 ),
-                SizedBox(height: 32),
+                const SizedBox(height: 32),
 
                 // Login Button
                 SizedBox(
@@ -160,14 +164,14 @@ class _LoginPageState extends State<LoginPage> {
                       ),
                     ),
                     child: _isLoading
-                        ? CircularProgressIndicator()
+                        ? const CircularProgressIndicator()
                         : Text(
-                            "LOGIN",
+                            l10n.login,
-                            style: TextStyle(fontWeight: FontWeight.bold),
+                            style: const TextStyle(fontWeight: FontWeight.bold),
                           ),
                   ),
                 ),
-                SizedBox(height: 16),
+                const SizedBox(height: 16),
 
                 // Register Link
                 TextButton(
@@ -175,7 +179,7 @@ class _LoginPageState extends State<LoginPage> {
                     context,
                     MaterialPageRoute(builder: (_) => RegisterPage()),
                   ),
-                  child: Text("Don't have an account? Create one"),
+                  child: Text(l10n.dontHaveAccount),
                 ),
               ],
             ),

frontend/lib/pages/my_stream_page.dart

@@ -2,6 +2,7 @@ import 'dart:convert';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 import 'package:flutter/services.dart';
+import '../l10n/app_localizations.dart';
 import '../providers/auth_provider.dart';
 import '../providers/settings_provider.dart';
 import '../services/api_service.dart';
@@ -42,9 +43,10 @@ class _MyStreamPageState extends State<MyStreamPage> {
       if (!mounted) {
         return;
       }
+      final l10n = AppLocalizations.of(context);
       ScaffoldMessenger.of(
         context,
-      ).showSnackBar(SnackBar(content: Text("Failed to fetch room info")));
+      ).showSnackBar(SnackBar(content: Text(l10n?.failedToFetchRoomInfo ?? "Failed to fetch room info")));
     } finally {
       if (mounted) {
         setState(() => _isLoading = false);
@@ -55,46 +57,47 @@ class _MyStreamPageState extends State<MyStreamPage> {
   @override
   Widget build(BuildContext context) {
     final settings = context.watch<SettingsProvider>();
+    final l10n = AppLocalizations.of(context)!;
 
     return Scaffold(
-      appBar: AppBar(title: Text("My Stream Console")),
+      appBar: AppBar(title: Text(l10n.myStreamConsole)),
       body: _isLoading
-          ? Center(child: CircularProgressIndicator())
+          ? const Center(child: CircularProgressIndicator())
           : _roomInfo == null
-          ? Center(child: Text("No room info found."))
+          ? Center(child: Text(l10n.noRoomInfo))
           : SingleChildScrollView(
-              padding: EdgeInsets.all(20),
+              padding: const EdgeInsets.all(20),
               child: Column(
                 crossAxisAlignment: CrossAxisAlignment.start,
                 children: [
                   _buildInfoCard(
-                    title: "Room Title",
+                    title: l10n.roomTitle,
                     value: _roomInfo!['title'],
                     icon: Icons.edit,
                     onTap: () {
                       // TODO: Implement title update API later
                       ScaffoldMessenger.of(context).showSnackBar(
-                        SnackBar(content: Text("Title editing coming soon!")),
+                        const SnackBar(content: Text("Title editing coming soon!")),
                       );
                     },
                   ),
-                  SizedBox(height: 20),
+                  const SizedBox(height: 20),
                   _buildInfoCard(
-                    title: "RTMP Server URL",
+                    title: l10n.rtmpServerUrl,
                     value: settings.rtmpUrl,
                     icon: Icons.copy,
                     onTap: () {
                       Clipboard.setData(ClipboardData(text: settings.rtmpUrl));
                       ScaffoldMessenger.of(context).showSnackBar(
                         SnackBar(
-                          content: Text("Server URL copied to clipboard"),
+                          content: Text(l10n.copiedToClipboard),
                         ),
                       );
                     },
                   ),
-                  SizedBox(height: 20),
+                  const SizedBox(height: 20),
                   _buildInfoCard(
-                    title: "Stream Key (Keep Secret!)",
+                    title: l10n.streamKey,
                     value: _roomInfo!['stream_key'],
                     icon: Icons.copy,
                     isSecret: true,
@@ -104,18 +107,18 @@ class _MyStreamPageState extends State<MyStreamPage> {
                       );
                       ScaffoldMessenger.of(context).showSnackBar(
                         SnackBar(
-                          content: Text("Stream Key copied to clipboard"),
+                          content: Text(l10n.copiedToClipboard),
                         ),
                       );
                     },
                   ),
-                  SizedBox(height: 24),
+                  const SizedBox(height: 24),
                   AndroidQuickStreamPanel(
                     rtmpBaseUrl: settings.rtmpUrl,
                     streamKey: _roomInfo!['stream_key'],
                   ),
-                  SizedBox(height: 30),
+                  const SizedBox(height: 30),
-                  Center(
+                  const Center(
                     child: Column(
                       children: [
                         Icon(Icons.info_outline, color: Colors.grey),
@@ -143,10 +146,10 @@ class _MyStreamPageState extends State<MyStreamPage> {
   }) {
     return Card(
       child: ListTile(
-        title: Text(title, style: TextStyle(fontSize: 12, color: Colors.grey)),
+        title: Text(title, style: const TextStyle(fontSize: 12, color: Colors.grey)),
         subtitle: Text(
           isSecret ? "••••••••••••••••" : value,
-          style: TextStyle(fontWeight: FontWeight.bold, fontSize: 16),
+          style: const TextStyle(fontWeight: FontWeight.bold, fontSize: 16),
         ),
         trailing: IconButton(icon: Icon(icon), onPressed: onTap),
       ),

frontend/lib/pages/player_page.dart

@@ -7,6 +7,7 @@ import 'package:flutter/services.dart';
 import 'package:provider/provider.dart';
 import 'package:video_player/video_player.dart';
 
+import '../l10n/app_localizations.dart';
 import '../providers/auth_provider.dart';
 import '../providers/settings_provider.dart';
 import '../services/api_service.dart';
@@ -271,6 +272,7 @@ class _PlayerPageState extends State<PlayerPage> {
 
   Future<void> _openVolumeSheet() async {
     _showControls();
+    final l10n = AppLocalizations.of(context)!;
     await showModalBottomSheet<void>(
       context: context,
       builder: (context) {
@@ -284,7 +286,7 @@ class _PlayerPageState extends State<PlayerPage> {
                   crossAxisAlignment: CrossAxisAlignment.start,
                   children: [
                     Text(
-                      'Volume',
+                      l10n.volume,
                       style: Theme.of(context).textTheme.titleMedium,
                     ),
                     const SizedBox(height: 12),
@@ -353,6 +355,7 @@ class _PlayerPageState extends State<PlayerPage> {
     if (!mounted) {
       return;
     }
+    final l10n = AppLocalizations.of(context)!;
 
     final nextResolution = await showModalBottomSheet<String>(
       context: context,
@@ -364,11 +367,11 @@ class _PlayerPageState extends State<PlayerPage> {
             mainAxisSize: MainAxisSize.min,
             children: [
               ListTile(
-                title: Text('Playback Resolution'),
+                title: Text(l10n.playbackResolution),
                 subtitle: Text(
                   available.length > 1
-                      ? 'Select an available transcoded stream.'
+                      ? l10n.playbackOptionsDesc
-                      : 'Only the source stream is available right now.',
+                      : l10n.sourceOnlyDesc,
                 ),
               ),
               ...options.map((option) {
@@ -382,8 +385,8 @@ class _PlayerPageState extends State<PlayerPage> {
                   ),
                   title: Text(option),
                   subtitle: enabled
-                      ? const Text('Available now')
+                      ? Text(l10n.availableNow)
-                      : const Text('Waiting for backend transcoding output'),
+                      : Text(l10n.waitingForTranscoding),
                   onTap: enabled ? () => Navigator.pop(context, option) : null,
                 );
               }),
@@ -590,6 +593,7 @@ class _PlayerPageState extends State<PlayerPage> {
   }
 
   Widget _buildPlaybackControls() {
+    final l10n = AppLocalizations.of(context)!;
     return IgnorePointer(
       ignoring: !_controlsVisible,
       child: AnimatedOpacity(
@@ -620,7 +624,7 @@ class _PlayerPageState extends State<PlayerPage> {
                 children: [
                   _buildControlButton(
                     icon: Icons.refresh,
-                    label: "Refresh",
+                    label: l10n.refresh,
                     onPressed: _refreshPlayer,
                   ),
                   _buildControlButton(
@@ -629,19 +633,19 @@ class _PlayerPageState extends State<PlayerPage> {
                         : _volume < 0.5
                         ? Icons.volume_down
                         : Icons.volume_up,
-                    label: "Volume",
+                    label: l10n.volume,
                     onPressed: _openVolumeSheet,
                   ),
                   _buildControlButton(
                     icon: _showDanmaku ? Icons.subtitles : Icons.subtitles_off,
-                    label: _showDanmaku ? "Danmaku On" : "Danmaku Off",
+                    label: _showDanmaku ? l10n.danmakuOn : l10n.danmakuOff,
                     onPressed: _toggleDanmaku,
                   ),
                   _buildControlButton(
                     icon: _isFullscreen
                         ? Icons.fullscreen_exit
                         : Icons.fullscreen,
-                    label: _isFullscreen ? "Exit Fullscreen" : "Fullscreen",
+                    label: _isFullscreen ? l10n.exitFullscreen : l10n.fullscreen,
                     onPressed: _toggleFullscreen,
                   ),
                   _buildControlButton(
@@ -679,23 +683,24 @@ class _PlayerPageState extends State<PlayerPage> {
 
   // 抽离聊天区域组件
   Widget _buildChatSection() {
+    final l10n = AppLocalizations.of(context)!;
     return Column(
       children: [
         Container(
-          padding: EdgeInsets.symmetric(horizontal: 16, vertical: 12),
+          padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
           color: Theme.of(context).colorScheme.surfaceContainerHighest,
           child: Row(
             children: [
-              Icon(Icons.chat_bubble_outline, size: 16),
+              const Icon(Icons.chat_bubble_outline, size: 16),
-              SizedBox(width: 8),
+              const SizedBox(width: 8),
-              Text("Live Chat", style: TextStyle(fontWeight: FontWeight.bold)),
+              Text(l10n.liveChat, style: const TextStyle(fontWeight: FontWeight.bold)),
             ],
           ),
         ),
         Expanded(
           child: ListView.builder(
             reverse: true,
-            padding: EdgeInsets.all(8),
+            padding: const EdgeInsets.all(8),
             itemCount: _messages.length,
             itemBuilder: (context, index) {
               final m = _messages[index];
@@ -703,7 +708,7 @@ class _PlayerPageState extends State<PlayerPage> {
             },
           ),
         ),
-        Divider(height: 1),
+        const Divider(height: 1),
         Padding(
           padding: const EdgeInsets.all(8.0),
           child: Row(
@@ -712,11 +717,11 @@ class _PlayerPageState extends State<PlayerPage> {
                 child: TextField(
                   controller: _msgController,
                   decoration: InputDecoration(
-                    hintText: "Send a message...",
+                    hintText: l10n.sendMessage,
                     border: OutlineInputBorder(
                       borderRadius: BorderRadius.circular(20),
                     ),
-                    contentPadding: EdgeInsets.symmetric(
+                    contentPadding: const EdgeInsets.symmetric(
                       horizontal: 16,
                       vertical: 8,
                     ),

frontend/lib/pages/register_page.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
+import '../l10n/app_localizations.dart';
 import '../providers/settings_provider.dart';
 import '../services/api_service.dart';
 
@@ -15,8 +16,9 @@ class _RegisterPageState extends State<RegisterPage> {
   bool _isLoading = false;
 
   void _handleRegister() async {
+    final l10n = AppLocalizations.of(context)!;
     if (_usernameController.text.isEmpty || _passwordController.text.isEmpty) {
-      ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text("Please fill in all fields")));
+      ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(l10n.fillAllFields)));
       return;
     }
 
@@ -27,14 +29,14 @@ class _RegisterPageState extends State<RegisterPage> {
     try {
       final response = await api.register(_usernameController.text, _passwordController.text);
       if (response.statusCode == 201) {
-        ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text("Account created! Please login.")));
+        ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(l10n.accountCreated)));
         Navigator.pop(context);
       } else {
         final error = jsonDecode(response.body)['error'] ?? "Registration Failed";
         ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(error)));
       }
     } catch (e) {
-      ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text("Network Error")));
+      ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(l10n.networkError)));
     } finally {
       if (mounted) setState(() => _isLoading = false);
     }
@@ -42,42 +44,43 @@ class _RegisterPageState extends State<RegisterPage> {
 
   @override
   Widget build(BuildContext context) {
+    final l10n = AppLocalizations.of(context)!;
     return Scaffold(
-      appBar: AppBar(title: Text("Create Account")),
+      appBar: AppBar(title: Text(l10n.createAccount)),
       body: Center(
         child: SingleChildScrollView(
           padding: const EdgeInsets.symmetric(horizontal: 32.0),
           child: ConstrainedBox(
-            constraints: BoxConstraints(maxWidth: 400),
+            constraints: const BoxConstraints(maxWidth: 400),
             child: Column(
               mainAxisAlignment: MainAxisAlignment.center,
               children: [
                 Icon(Icons.person_add_outlined, size: 64, color: Theme.of(context).colorScheme.primary),
-                SizedBox(height: 24),
+                const SizedBox(height: 24),
                 Text(
-                  "Join Hightube",
+                  l10n.joinHightube,
                   style: Theme.of(context).textTheme.headlineMedium?.copyWith(fontWeight: FontWeight.bold),
                 ),
-                SizedBox(height: 48),
+                const SizedBox(height: 48),
                 TextField(
                   controller: _usernameController,
                   decoration: InputDecoration(
-                    labelText: "Desired Username",
+                    labelText: l10n.desiredUsername,
-                    prefixIcon: Icon(Icons.person),
+                    prefixIcon: const Icon(Icons.person),
                     border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
                   ),
                 ),
-                SizedBox(height: 16),
+                const SizedBox(height: 16),
                 TextField(
                   controller: _passwordController,
                   obscureText: true,
                   decoration: InputDecoration(
-                    labelText: "Password",
+                    labelText: l10n.password,
-                    prefixIcon: Icon(Icons.lock),
+                    prefixIcon: const Icon(Icons.lock),
                     border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
                   ),
                 ),
-                SizedBox(height: 32),
+                const SizedBox(height: 32),
                 SizedBox(
                   width: double.infinity,
                   height: 50,
@@ -86,13 +89,13 @@ class _RegisterPageState extends State<RegisterPage> {
                     style: ElevatedButton.styleFrom(
                       shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
                     ),
-                    child: _isLoading ? CircularProgressIndicator() : Text("REGISTER", style: TextStyle(fontWeight: FontWeight.bold)),
+                    child: _isLoading ? const CircularProgressIndicator() : Text(l10n.register, style: const TextStyle(fontWeight: FontWeight.bold)),
                   ),
                 ),
-                SizedBox(height: 16),
+                const SizedBox(height: 16),
                 TextButton(
                   onPressed: () => Navigator.pop(context),
-                  child: Text("Already have an account? Login here"),
+                  child: Text(l10n.alreadyHaveAccount),
                 ),
               ],
             ),

frontend/lib/pages/settings_page.dart

@@ -2,6 +2,7 @@ import 'dart:convert';
 
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
+import '../l10n/app_localizations.dart';
 
 import '../providers/auth_provider.dart';
 import '../providers/settings_provider.dart';
@@ -88,21 +89,21 @@ class _SettingsPageState extends State<SettingsPage> {
     }
   }
 
-  Future<void> _confirmLogout(AuthProvider auth) async {
+  Future<void> _confirmLogout(AuthProvider auth, AppLocalizations l10n) async {
     final confirmed = await showDialog<bool>(
       context: context,
       builder: (context) {
         return AlertDialog(
-          title: const Text("Confirm Logout"),
+          title: Text(l10n.confirmLogout),
-          content: const Text("Are you sure you want to log out now?"),
+          content: Text(l10n.confirmLogoutDesc),
           actions: [
             TextButton(
               onPressed: () => Navigator.pop(context, false),
-              child: const Text("Cancel"),
+              child: Text(l10n.cancel),
             ),
             FilledButton(
               onPressed: () => Navigator.pop(context, true),
-              child: const Text("Logout"),
+              child: Text(l10n.logout),
             ),
           ],
         );
@@ -119,10 +120,11 @@ class _SettingsPageState extends State<SettingsPage> {
     final auth = context.watch<AuthProvider>();
     final settings = context.watch<SettingsProvider>();
     final isAuthenticated = auth.isAuthenticated;
+    final l10n = AppLocalizations.of(context)!;
 
     return Scaffold(
       appBar: AppBar(
-        title: Text("Settings", style: TextStyle(fontWeight: FontWeight.bold)),
+        title: Text(l10n.settings, style: TextStyle(fontWeight: FontWeight.bold)),
         centerTitle: true,
       ),
       body: SingleChildScrollView(
@@ -134,12 +136,58 @@ class _SettingsPageState extends State<SettingsPage> {
               _buildProfileSection(auth),
               const SizedBox(height: 32),
             ],
-            _buildSectionTitle("Network Configuration"),
+            
+            _buildSectionTitle(l10n.language),
+            const SizedBox(height: 16),
+            DropdownButtonFormField<Locale?>(
+              initialValue: settings.locale == null 
+                  ? null 
+                  : AppLocalizations.supportedLocales.cast<Locale?>().firstWhere(
+                      (l) => l?.languageCode == settings.locale?.languageCode && 
+                             l?.scriptCode == settings.locale?.scriptCode,
+                      orElse: () => null,
+                    ),
+              decoration: InputDecoration(
+                labelText: l10n.selectLanguage,
+                prefixIcon: const Icon(Icons.language),
+                border: OutlineInputBorder(
+                  borderRadius: BorderRadius.circular(12),
+                ),
+              ),
+              items: [
+                DropdownMenuItem(
+                  value: null,
+                  child: Text(l10n.system),
+                ),
+                DropdownMenuItem(
+                  value: const Locale('en'),
+                  child: Text(l10n.english),
+                ),
+                DropdownMenuItem(
+                  value: const Locale('zh'),
+                  child: Text(l10n.simplifiedChinese),
+                ),
+                DropdownMenuItem(
+                  value: const Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hant'),
+                  child: Text(l10n.traditionalChinese),
+                ),
+                DropdownMenuItem(
+                  value: const Locale('ja'),
+                  child: Text(l10n.japanese),
+                ),
+              ],
+              onChanged: (Locale? newLocale) {
+                settings.setLocale(newLocale);
+              },
+            ),
+            const SizedBox(height: 32),
+
+            _buildSectionTitle(l10n.networkConfiguration),
             const SizedBox(height: 16),
             TextField(
               controller: _urlController,
               decoration: InputDecoration(
-                labelText: "Backend Server URL",
+                labelText: l10n.backendServerUrl,
                 hintText: "http://127.0.0.1:8080",
                 prefixIcon: Icon(Icons.lan),
                 border: OutlineInputBorder(
@@ -157,13 +205,13 @@ class _SettingsPageState extends State<SettingsPage> {
                   );
                   ScaffoldMessenger.of(context).showSnackBar(
                     SnackBar(
-                      content: Text("Server URL Updated"),
+                      content: Text(l10n.serverUrlUpdated),
                       behavior: SnackBarBehavior.floating,
                     ),
                   );
                 },
                 icon: Icon(Icons.save),
-                label: Text("Save Network Settings"),
+                label: Text(l10n.saveNetworkSettings),
                 style: ElevatedButton.styleFrom(
                   backgroundColor: Theme.of(
                     context,
@@ -179,28 +227,28 @@ class _SettingsPageState extends State<SettingsPage> {
             ),
             const SizedBox(height: 32),
 
-            _buildSectionTitle("Theme Customization"),
+            _buildSectionTitle(l10n.themeCustomization),
             const SizedBox(height: 16),
             Text(
-              "Appearance Mode",
+              l10n.appearanceMode,
               style: Theme.of(context).textTheme.labelLarge,
             ),
             const SizedBox(height: 12),
             SegmentedButton<ThemeMode>(
-              segments: const [
+              segments: [
                 ButtonSegment<ThemeMode>(
                   value: ThemeMode.system,
-                  label: Text("System"),
+                  label: Text(l10n.system),
                   icon: Icon(Icons.brightness_auto),
                 ),
                 ButtonSegment<ThemeMode>(
                   value: ThemeMode.light,
-                  label: Text("Light"),
+                  label: Text(l10n.light),
                   icon: Icon(Icons.light_mode),
                 ),
                 ButtonSegment<ThemeMode>(
                   value: ThemeMode.dark,
-                  label: Text("Dark"),
+                  label: Text(l10n.dark),
                   icon: Icon(Icons.dark_mode),
                 ),
               ],
@@ -210,7 +258,7 @@ class _SettingsPageState extends State<SettingsPage> {
               },
             ),
             const SizedBox(height: 20),
-            Text("Accent Color", style: Theme.of(context).textTheme.labelLarge),
+            Text(l10n.accentColor, style: Theme.of(context).textTheme.labelLarge),
             const SizedBox(height: 12),
             Wrap(
               spacing: 12,
@@ -248,26 +296,26 @@ class _SettingsPageState extends State<SettingsPage> {
               }).toList(),
             ),
             const SizedBox(height: 32),
-            _buildSectionTitle("Explore"),
+            _buildSectionTitle(l10n.explore),
             const SizedBox(height: 8),
             SwitchListTile.adaptive(
               contentPadding: EdgeInsets.zero,
-              title: const Text("Live Preview Thumbnails"),
+              title: Text(l10n.livePreviewThumbnails),
-              subtitle: const Text(
+              subtitle: Text(
-                "Show cached snapshot covers for live rooms when available.",
+                l10n.livePreviewThumbnailsDesc,
               ),
               value: settings.livePreviewThumbnailsEnabled,
               onChanged: settings.setLivePreviewThumbnailsEnabled,
             ),
             if (isAuthenticated) ...[
               const SizedBox(height: 32),
-              _buildSectionTitle("Security"),
+              _buildSectionTitle(l10n.security),
               const SizedBox(height: 16),
               TextField(
                 controller: _oldPasswordController,
                 obscureText: true,
                 decoration: InputDecoration(
-                  labelText: "Old Password",
+                  labelText: l10n.oldPassword,
                   prefixIcon: const Icon(Icons.lock_outline),
                   border: OutlineInputBorder(
                     borderRadius: BorderRadius.circular(12),
@@ -279,7 +327,7 @@ class _SettingsPageState extends State<SettingsPage> {
                 controller: _newPasswordController,
                 obscureText: true,
                 decoration: InputDecoration(
-                  labelText: "New Password",
+                  labelText: l10n.newPassword,
                   prefixIcon: const Icon(Icons.lock_reset),
                   border: OutlineInputBorder(
                     borderRadius: BorderRadius.circular(12),
@@ -292,7 +340,7 @@ class _SettingsPageState extends State<SettingsPage> {
                 child: OutlinedButton.icon(
                   onPressed: _handleChangePassword,
                   icon: const Icon(Icons.update),
-                  label: const Text("Change Password"),
+                  label: Text(l10n.changePassword),
                   style: OutlinedButton.styleFrom(
                     shape: RoundedRectangleBorder(
                       borderRadius: BorderRadius.circular(12),
@@ -304,9 +352,9 @@ class _SettingsPageState extends State<SettingsPage> {
               SizedBox(
                 width: double.infinity,
                 child: FilledButton.tonalIcon(
-                  onPressed: () => _confirmLogout(auth),
+                  onPressed: () => _confirmLogout(auth, l10n),
                   icon: const Icon(Icons.logout),
-                  label: const Text("Logout"),
+                  label: Text(l10n.logout),
                   style: FilledButton.styleFrom(
                     foregroundColor: Colors.redAccent,
                     padding: const EdgeInsets.symmetric(vertical: 14),

frontend/lib/providers/settings_provider.dart

@@ -13,11 +13,13 @@ class SettingsProvider with ChangeNotifier {
   Color _themeColor = Colors.blue;
   ThemeMode _themeMode = ThemeMode.system;
   bool _livePreviewThumbnailsEnabled = false;
+  Locale? _locale;
 
   String get baseUrl => _baseUrl;
   Color get themeColor => _themeColor;
   ThemeMode get themeMode => _themeMode;
   bool get livePreviewThumbnailsEnabled => _livePreviewThumbnailsEnabled;
+  Locale? get locale => _locale;
 
   SettingsProvider() {
     _loadSettings();
@@ -36,6 +38,41 @@ class SettingsProvider with ChangeNotifier {
     }
     _livePreviewThumbnailsEnabled =
         prefs.getBool('livePreviewThumbnailsEnabled') ?? false;
+    
+    final languageCode = prefs.getString('languageCode');
+    final scriptCode = prefs.getString('scriptCode');
+    final countryCode = prefs.getString('countryCode');
+    if (languageCode != null) {
+      _locale = Locale.fromSubtags(
+        languageCode: languageCode,
+        scriptCode: scriptCode,
+        countryCode: countryCode,
+      );
+    }
+    
+    notifyListeners();
+  }
+
+  void setLocale(Locale? newLocale) async {
+    _locale = newLocale;
+    final prefs = await SharedPreferences.getInstance();
+    if (newLocale == null) {
+      await prefs.remove('languageCode');
+      await prefs.remove('scriptCode');
+      await prefs.remove('countryCode');
+    } else {
+      await prefs.setString('languageCode', newLocale.languageCode);
+      if (newLocale.scriptCode != null) {
+        await prefs.setString('scriptCode', newLocale.scriptCode!);
+      } else {
+        await prefs.remove('scriptCode');
+      }
+      if (newLocale.countryCode != null) {
+        await prefs.setString('countryCode', newLocale.countryCode!);
+      } else {
+        await prefs.remove('countryCode');
+      }
+    }
     notifyListeners();
   }
 

frontend/lib/widgets/android_quick_stream_panel.dart

@@ -58,6 +58,13 @@ class _AndroidQuickStreamPanelState extends State<AndroidQuickStreamPanel> {
   }
 
   Future<void> _initialize() async {
+    if (kIsWeb || defaultTargetPlatform != TargetPlatform.android) {
+      setState(() {
+        _isPreparing = false;
+        _statusMessage = 'Quick stream is only supported on Android.';
+      });
+      return;
+    }
     if (!mounted) {
       return;
     }

frontend/pubspec.lock

@@ -150,6 +150,11 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
+  flutter_localizations:
+    dependency: "direct main"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -216,6 +221,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.8.0"
+  intl:
+    dependency: "direct main"
+    description:
+      name: intl
+      sha256: "3df61194eb431efc39c4ceba583b95633a403f46c9fd341e550ce0bfa50e9aa5"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.20.2"
   json_annotation:
     dependency: transitive
     description:

frontend/pubspec.yaml

@@ -42,6 +42,9 @@ dependencies:
   web_socket_channel: ^3.0.3
   permission_handler: ^12.0.1
   rtmp_streaming: ^1.0.5
+  intl: ^0.20.2
+  flutter_localizations:
+    sdk: flutter
 
 dev_dependencies:
   flutter_test:
@@ -75,6 +78,7 @@ flutter_launcher_icons:
 
 # The following section is specific to Flutter packages.
 flutter:
+  generate: true
 
   # The following line ensures that the Material Icons font is
   # included with your application, so that you can use the icons in