fix: 兼容 Web 同源部署地址

frontend/lib/providers/settings_provider.dart

@@ -3,11 +3,16 @@ import 'package:flutter/foundation.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 class SettingsProvider with ChangeNotifier {
-  // Use 10.0.2.2 for Android emulator to access host's localhost
-  static String get _defaultUrl =>
-      (defaultTargetPlatform == TargetPlatform.android && !kIsWeb)
-      ? "http://10.0.2.2:8080"
-      : "http://localhost:8080";
+  // On web: use empty string so API calls use same origin (works behind any proxy)
+  // On Android emulator: 10.0.2.2 maps to host localhost
+  // On other platforms: localhost
+  static String get _defaultUrl {
+    if (kIsWeb) return "";
+    if (defaultTargetPlatform == TargetPlatform.android) {
+      return "http://10.0.2.2:8080";
+    }
+    return "http://localhost:8080";
+  }
 
   String _baseUrl = _defaultUrl;
   Color _themeColor = Colors.blue;
@@ -38,7 +43,7 @@ class SettingsProvider with ChangeNotifier {
     }
     _livePreviewThumbnailsEnabled =
         prefs.getBool('livePreviewThumbnailsEnabled') ?? false;
-    
+
     final languageCode = prefs.getString('languageCode');
     final scriptCode = prefs.getString('scriptCode');
     final countryCode = prefs.getString('countryCode');
@@ -49,7 +54,7 @@ class SettingsProvider with ChangeNotifier {
         countryCode: countryCode,
       );
     }
-    
+
     notifyListeners();
   }
 
@@ -106,8 +111,18 @@ class SettingsProvider with ChangeNotifier {
 
   // Also provide the RTMP URL based on the same hostname
   String get rtmpUrl {
-    final uri = Uri.parse(_baseUrl);
-    return "rtmp://${uri.host}:1935/live";
+    final host = _baseUrl.isEmpty ? _effectiveHost : Uri.parse(_baseUrl).host;
+    return "rtmp://$host:1935/live";
+  }
+
+  // Fallback hostname when baseUrl is empty (web same-origin mode)
+  String get _effectiveHost {
+    if (kIsWeb) {
+      final host = Uri.base.host;
+      if (host.isNotEmpty) return host;
+      return 'localhost';
+    }
+    return 'localhost';
   }
 
   String playbackUrl(String roomId, {String? quality}) {

frontend/lib/services/chat_service.dart

@@ -45,7 +45,7 @@ class ChatService {
   Stream<ChatMessage> get messages => _messageController.stream;
 
   void connect(String baseUrl, String roomId, String username) {
-    final wsUri = Uri.parse(baseUrl).replace(
+    final wsUri = _webSocketUri(baseUrl).replace(
       scheme: 'ws',
       path: '/api/ws/room/$roomId',
       queryParameters: {'username': username},
@@ -83,6 +83,21 @@ class ChatService {
     }
   }
 
+  Uri _webSocketUri(String baseUrl) {
+    if (baseUrl.isEmpty) {
+      if (kIsWeb) {
+        return Uri.base.replace(
+          scheme: Uri.base.scheme == 'https' ? 'wss' : 'ws',
+        );
+      }
+      return Uri.parse('http://localhost:8080');
+    }
+
+    final uri = Uri.parse(baseUrl);
+    final scheme = uri.scheme == 'https' ? 'wss' : 'ws';
+    return uri.replace(scheme: scheme);
+  }
+
   void dispose() {
     _channel?.sink.close();
     _messageController.close();