fix: 修复AI重复调用问题，统一消息处理流程

- _process_message 只保存用户消息并通知
- 新增 generate_ai_response action 统一处理AI回复
- 避免重复调用AI和重复发送消息

main.py

@@ -457,6 +457,64 @@ async def handle_matrix_message(action: str, conversation_id: str = None, user_m
             db.close()
         return
     
+    if action == "generate_ai_response":
+        # 生成AI回复并同步
+        db = SessionLocal()
+        try:
+            conv_service = ConversationService(db)
+            conversation = conv_service.get_conversation(conversation_id)
+            
+            if conversation:
+                # 发送"正在输入"状态
+                try:
+                    await matrix_bot.client.room_typing(room_id, typing_state=True)
+                except:
+                    pass
+                
+                # 获取会话历史
+                history = conv_service.get_conversation_history(conversation_id, limit=20)
+                
+                # 调用AI
+                ai_response = await ai_service.chat(history)
+                
+                # 保存AI回复
+                assistant_msg = conv_service.add_message(
+                    conversation_id=conversation.id,
+                    role='assistant',
+                    content=ai_response,
+                    source='matrix'
+                )
+                
+                # 发送到Matrix
+                await matrix_bot.send_message(room_id, ai_response)
+                
+                # 关闭"正在输入"状态
+                try:
+                    await matrix_bot.client.room_typing(room_id, typing_state=False)
+                except:
+                    pass
+                
+                # 同步到网页端WebSocket
+                await manager.send_to_user(MAIN_USER_ID, {
+                    "type": "assistant_message",
+                    "conversation_id": conversation_id,
+                    "message": {
+                        "id": assistant_msg.id,
+                        "role": "assistant",
+                        "content": ai_response,
+                        "source": "matrix",
+                        "created_at": assistant_msg.created_at.isoformat()
+                    }
+                })
+                
+                logger.info(f"Matrix AI回复已发送: {ai_response[:50]}")
+        except Exception as e:
+            logger.error(f"生成AI回复失败: {e}")
+            await matrix_bot.send_message(room_id, f"处理消息时出错: {str(e)}")
+        finally:
+            db.close()
+        return
+    
     if action == "chat":
         db = SessionLocal()
         try: