refactor: use background only flows

lib/core/services/api_service.dart

@@ -2796,13 +2796,14 @@ class ApiService {
   final Map<String, CancelToken> _streamCancelTokens = {};
   final Map<String, String> _messagePersistentStreamIds = {};
 
-  // Send message with SSE streaming
+  // Send message using the background flow (socket push + polling fallback).
-  // Returns a record with (stream, messageId, sessionId)
+  // Returns a record with (stream, messageId, sessionId, socketSessionId, isBackgroundFlow)
   ({
     Stream<String> stream,
     String messageId,
     String sessionId,
     String? socketSessionId,
+    bool isBackgroundFlow,
   })
   sendMessage({
     required List<Map<String, dynamic>> messages,
@@ -2877,9 +2878,12 @@ class ApiService {
       }
     }
 
-    // Build request data - minimal params for SSE to work
+    final bool hasBackgroundTasksPayload =
-    // OpenWebUI server doesn't support SSE with session_id/id parameters
+        backgroundTasks != null && backgroundTasks.isNotEmpty;
-    final data = {
+
+    // Build request data. Always request streamed responses so the backend can
+    // forward deltas over WebSocket when running in background task mode.
+    final data = <String, dynamic>{
       'stream': true,
       'model': model,
       'messages': processedMessages,
@@ -2893,12 +2897,12 @@ class ApiService {
     // Add feature flags if enabled
     if (enableWebSearch) {
       data['web_search'] = true;
-      _traceApi('Web search enabled in SSE request');
+      _traceApi('Web search enabled in streaming request');
     }
     if (enableImageGeneration) {
       // Mirror web_search behavior for image generation
       data['image_generation'] = true;
-      _traceApi('Image generation enabled in SSE request');
+      _traceApi('Image generation enabled in streaming request');
     }
 
     if (enableWebSearch || enableImageGeneration) {
@@ -2911,14 +2915,6 @@ class ApiService {
       };
     }
 
-    if (backgroundTasks != null && backgroundTasks.isNotEmpty) {
-      data['background_tasks'] = backgroundTasks;
-    }
-
-    if (socketSessionId != null && socketSessionId.isNotEmpty) {
-      data['session_id'] = socketSessionId;
-    }
-
     data['id'] = messageId;
 
     // No default reasoning parameters included; providers handle thinking UIs natively.
@@ -2926,7 +2922,7 @@ class ApiService {
     // Add tool_ids if provided (Open-WebUI expects tool_ids as array of strings)
     if (toolIds != null && toolIds.isNotEmpty) {
       data['tool_ids'] = toolIds;
-      _traceApi('Including tool_ids in SSE request: $toolIds');
+      _traceApi('Including tool_ids in streaming request: $toolIds');
 
       // Hint server to use native function calling when tools are selected
       // This enables provider-native tool execution paths and consistent UI events
@@ -2953,35 +2949,25 @@ class ApiService {
       _traceApi('Including non-image files in request: ${allFiles.length}');
     }
 
-    // Don't add session_id or id - they break SSE streaming!
+    _traceApi('Preparing chat send request (backgroundFlow: true)');
-    // The server falls back to task-based async when these are present
-
-    _traceApi('Starting SSE streaming request');
     _traceApi('Model: $model');
     _traceApi('Message count: ${processedMessages.length}');
 
     // Debug the data being sent
-    _traceApi('SSE request data keys (pre-bg): ${data.keys.toList()}');
+    _traceApi('Request data keys (pre-dispatch): ${data.keys.toList()}');
+    _traceApi('Has background_tasks: ${data.containsKey('background_tasks')}');
+    _traceApi('Has session_id: ${data.containsKey('session_id')}');
+    _traceApi('background_tasks value: ${data['background_tasks']}');
+    _traceApi('session_id value: ${data['session_id']}');
+    _traceApi('id value: ${data['id']}');
+
     _traceApi(
-      'Has background_tasks (pre-bg): ${data.containsKey('background_tasks')}',
+      'Forcing background flow (hasBackgroundTasks: '
+      '$hasBackgroundTasksPayload, tools: ${toolIds?.isNotEmpty == true}, '
+      'webSearch: $enableWebSearch, imageGen: $enableImageGeneration, '
+      'sessionOverride: ${sessionIdOverride != null && sessionIdOverride.isNotEmpty})',
     );
-    _traceApi('Has session_id (pre-bg): ${data.containsKey('session_id')}');
-    _traceApi('background_tasks value (pre-bg): ${data['background_tasks']}');
-    _traceApi('session_id value (pre-bg): ${data['session_id']}');
-    _traceApi('id value (pre-bg): ${data['id']}');
 
-    // Decide whether to use background task flow.
-    // Use background task mode when tools, web_search, image_generation are enabled,
-    // or when an explicit dynamic socket session binding is requested.
-    final bool useBackgroundTasks =
-        (toolIds != null && toolIds.isNotEmpty) ||
-        enableWebSearch ||
-        enableImageGeneration ||
-        (sessionIdOverride != null && sessionIdOverride.isNotEmpty);
-
-    // Use background flow only when required; otherwise prefer SSE even with chat_id.
-    // SSE must not include session_id/id to avoid server falling back to task mode.
-    if (useBackgroundTasks) {
     // Attach identifiers to trigger background task processing on the server
     data['session_id'] = sessionId;
     data['id'] = messageId;
@@ -3001,12 +2987,10 @@ class ApiService {
     _traceApi(
       'Has tool_ids: ${data.containsKey('tool_ids')} -> ${data['tool_ids']}',
     );
-      _traceApi(
+    _traceApi('Has background_tasks: ${data.containsKey('background_tasks')}');
-        'Has background_tasks: ${data.containsKey('background_tasks')}',
-      );
 
     _traceApi('Initiating background tools flow (task-based)');
-      _traceApi('Posting to /api/chat/completions (no SSE)');
+    _traceApi('Posting to /api/chat/completions');
 
     // Fire in background; poll chat for updates and stream deltas to UI
     () async {
@@ -3019,9 +3003,16 @@ class ApiService {
         _traceApi('Background task created: $taskId');
 
         // If no session/socket provided, fall back to polling for updates.
-          if (sessionIdOverride == null || sessionIdOverride.isEmpty) {
+        final pollChatId = (conversationId != null && conversationId.isNotEmpty)
+            ? conversationId
+            : null;
+        final requiresPolling =
+            sessionIdOverride == null || sessionIdOverride.isEmpty;
+
+        if (requiresPolling && pollChatId != null) {
+          final chatId = pollChatId;
           await _pollChatForMessageUpdates(
-              chatId: conversationId!,
+            chatId: chatId,
             messageId: messageId,
             streamController: streamController,
           );
@@ -3036,120 +3027,13 @@ class ApiService {
         if (!streamController.isClosed) streamController.close();
       }
     }();
-    } else {
-      // SSE streaming path for low-latency pure completions (no background tasks)
-      () async {
-        try {
-          // Request SSE stream; avoid session_id/id which break streaming
-          final resp = await _dio.post(
-            '/api/chat/completions',
-            data: data,
-            options: Options(
-              responseType: ResponseType.stream,
-              headers: {'Accept': 'text/event-stream'},
-            ),
-          );
-
-          // Parse SSE lines and forward deltas to the controller
-          final body = resp.data;
-          // Dio returns ResponseBody for stream responseType
-          final stream = (body is ResponseBody) ? body.stream : null;
-          if (stream == null) {
-            // Fallback: if server responded JSON, emit once
-            try {
-              final dataStr = resp.data?.toString() ?? '';
-              if (dataStr.isNotEmpty && !streamController.isClosed) {
-                streamController.add(dataStr);
-              }
-            } catch (_) {}
-            if (!streamController.isClosed) streamController.close();
-            return;
-          }
-
-          String buffer = '';
-          late final StreamSubscription<List<int>> sub;
-          sub = stream.listen(
-            (chunk) {
-              try {
-                buffer += utf8.decode(chunk, allowMalformed: true);
-                // Process complete lines; keep remainder in buffer
-                final parts = buffer.split('\n');
-                buffer = parts.isNotEmpty ? parts.removeLast() : '';
-                for (final raw in parts) {
-                  final line = raw.trim();
-                  if (line.isEmpty) continue;
-                  if (line == 'data: [DONE]') {
-                    try {
-                      if (!streamController.isClosed) streamController.close();
-                    } catch (_) {}
-                    sub.cancel();
-                    return;
-                  }
-                  if (line.startsWith('data:')) {
-                    final payloadStr = line.substring(5).trim();
-                    if (payloadStr.isEmpty) continue;
-                    try {
-                      final Map<String, dynamic> j = jsonDecode(payloadStr);
-                      final choices = j['choices'];
-                      if (choices is List && choices.isNotEmpty) {
-                        final choice = choices.first;
-                        final delta = choice is Map ? choice['delta'] : null;
-                        if (delta is Map) {
-                          final content = delta['content']?.toString() ?? '';
-                          if (content.isNotEmpty &&
-                              !streamController.isClosed) {
-                            streamController.add(content);
-                          }
-                        } else {
-                          final message = (choice is Map)
-                              ? (choice['message']?['content']?.toString() ??
-                                    '')
-                              : '';
-                          if (message.isNotEmpty &&
-                              !streamController.isClosed) {
-                            streamController.add(message);
-                          }
-                        }
-                      } else if (j['content'] is String) {
-                        final content = j['content'] as String;
-                        if (content.isNotEmpty && !streamController.isClosed) {
-                          streamController.add(content);
-                        }
-                      }
-                    } catch (_) {
-                      // Non-JSON payload; forward as-is
-                      if (!streamController.isClosed) {
-                        streamController.add(payloadStr);
-                      }
-                    }
-                  }
-                }
-              } catch (_) {}
-            },
-            onDone: () {
-              try {
-                if (!streamController.isClosed) streamController.close();
-              } catch (_) {}
-            },
-            onError: (_) {
-              try {
-                if (!streamController.isClosed) streamController.close();
-              } catch (_) {}
-            },
-            cancelOnError: true,
-          );
-        } catch (e) {
-          _traceApi('SSE streaming failed: $e');
-          if (!streamController.isClosed) streamController.close();
-        }
-      }();
-    }
 
     return (
       stream: streamController.stream,
       messageId: messageId,
       sessionId: sessionId,
       socketSessionId: socketSessionId,
+      isBackgroundFlow: true,
     );
   }
 

lib/features/chat/providers/chat_providers.dart

@@ -1251,7 +1251,8 @@ Future<void> regenerateMessage(
         isBackgroundToolsFlowPre ||
         isBackgroundWebSearchPre ||
         imageGenerationEnabled;
-    final bool passSocketSession = wantSessionBinding && isBackgroundFlowPre;
+    final bool passSocketSession =
+        wantSessionBinding && (isBackgroundFlowPre || bgTasks.isNotEmpty);
     final response = api!.sendMessage(
       messages: conversationMessages,
       model: selectedModel.id,
@@ -1272,12 +1273,7 @@ Future<void> regenerateMessage(
     final effectiveSessionId =
         response.socketSessionId ?? socketSessionId ?? sessionId;
 
-    // New unified streaming path via helper; bypass old inline socket block
+    final bool isBackgroundFlow = response.isBackgroundFlow;
-    final bool isBackgroundFlow =
-        isBackgroundToolsFlowPre ||
-        isBackgroundWebSearchPre ||
-        imageGenerationEnabled ||
-        wantSessionBinding;
     try {
       ref.read(chatMessagesProvider.notifier).updateLastMessageWithFunction((
         m,
@@ -1782,6 +1778,13 @@ Future<void> _sendMessageInternal(
         (toolServers != null && toolServers.isNotEmpty);
     final bool isBackgroundWebSearchPre = webSearchEnabled;
 
+    final bool shouldBindSession =
+        wantSessionBinding &&
+        (isBackgroundToolsFlowPre ||
+            isBackgroundWebSearchPre ||
+            imageGenerationEnabled ||
+            bgTasks.isNotEmpty);
+
     final response = await api.sendMessage(
       messages: conversationMessages,
       model: selectedModel.id,
@@ -1793,7 +1796,7 @@ Future<void> _sendMessageInternal(
       modelItem: modelItem,
       // Bind to Socket session whenever available so the server can push
       // streaming updates to this client (improves first-turn streaming).
-      sessionIdOverride: wantSessionBinding ? socketSessionId : null,
+      sessionIdOverride: shouldBindSession ? socketSessionId : null,
       socketSessionId: socketSessionId,
       toolServers: toolServers,
       backgroundTasks: bgTasks,
@@ -1806,10 +1809,7 @@ Future<void> _sendMessageInternal(
         response.socketSessionId ?? socketSessionId ?? sessionId;
 
     // Use unified streaming helper for SSE/WebSocket handling
-    final bool isBackgroundFlow =
+    final bool isBackgroundFlow = response.isBackgroundFlow;
-        isBackgroundToolsFlowPre ||
-        isBackgroundWebSearchPre ||
-        wantSessionBinding;
 
     try {
       ref.read(chatMessagesProvider.notifier).updateLastMessageWithFunction((