feat: 多功能升级 — 流式逐字渲染、对话缓存、会话组织优化、记忆管理修复、性能仪表盘

- 前端消息流式逐字渲染 (AI-Core ChatStream → SSE → Gateway → WebSocket stream_chunk → fadeInUp + cursorBlink)
- 后端对话缓存 (conversationCache sync.Map, GET /sessions/:id/messages)
- 前端侧边栏历史多轮对话显示
- DevTools 性能监控图标移至首页仪表盘
- DevTools 用户记忆查询/删减功能修复 (补全 DELETE 数据链路)
- 后端和 DevTools 按用户分类组织实时活动会话 (map[userID]map[sessionID]*Client)
- 新增 docs/api-reference/ 路由参考文档
- 新增 docs/message-flow-architecture.md 消息链路架构文档

backend/ai-core/cmd/main.go

@@ -172,7 +172,7 @@ func getEnv(key, fallback string) string {
 	return fallback
 }
 
-// handleChat 处理对话请求
+// handleChat 处理对话请求（SSE 流式响应）
 func handleChat(
 	w http.ResponseWriter,
 	r *http.Request,
@@ -237,36 +237,94 @@ func handleChat(
 		return
 	}
 
-	// 4. 调用LLM
-	llmResp, err := llmAdapter.Chat(ctx, llmMessages)
-	if err != nil {
-		http.Error(w, fmt.Sprintf("LLM调用失败: %v", err), http.StatusInternalServerError)
+	// 4. 设置 SSE 响应头
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Connection", "keep-alive")
+	w.Header().Set("X-Accel-Buffering", "no")
+
+	flusher, ok := w.(http.Flusher)
+	if !ok {
+		http.Error(w, "Streaming not supported", http.StatusInternalServerError)
 		return
 	}
 
-	// 5. 异步提取记忆
-	if memExtractor != nil {
-		go memExtractor.ExtractAndStore(context.Background(), req.UserID, req.SessionID, req.Message, llmResp.Content)
+	// 5. 调用LLM流式接口
+	chunkCh, err := llmAdapter.ChatStream(ctx, llmMessages)
+	if err != nil {
+		// 流式初始化失败，返回 SSE 格式错误
+		errData, _ := json.Marshal(map[string]string{"delta": "", "error": fmt.Sprintf("LLM调用失败: %v", err)})
+		fmt.Fprintf(w, "data: %s\n\n", errData)
+		flusher.Flush()
+		fmt.Fprintf(w, "data: [DONE]\n\n")
+		flusher.Flush()
+		return
 	}
 
-	// 6. 构建响应
-	resp := map[string]interface{}{
-		"text":       llmResp.Content,
+	messageID := fmt.Sprintf("msg-%d", time.Now().UnixNano())
+
+	// 6. 逐 token 推送 SSE
+	var fullContent string
+	var segments []llm.Segment
+	segmenter := llm.NewSegmenter()
+
+	for chunk := range chunkCh {
+		if chunk.Error != nil {
+			log.Printf("[chat] 流式错误: %v", chunk.Error)
+			errData, _ := json.Marshal(map[string]string{"delta": "", "error": chunk.Error.Error()})
+			fmt.Fprintf(w, "data: %s\n\n", errData)
+			flusher.Flush()
+			fmt.Fprintf(w, "data: [DONE]\n\n")
+			flusher.Flush()
+			return
+		}
+
+		if chunk.Done {
+			// 流结束，flush 剩余片段
+			if remaining := segmenter.Flush(); remaining != nil {
+				segments = append(segments, *remaining)
+			}
+			break
+		}
+
+		if chunk.Content != "" {
+			fullContent += chunk.Content
+
+			// 实时断句
+			newSegs := segmenter.Feed(chunk.Content)
+			segments = append(segments, newSegs...)
+
+			deltaData, _ := json.Marshal(map[string]string{
+				"delta":      chunk.Content,
+				"message_id": messageID,
+			})
+			fmt.Fprintf(w, "data: %s\n\n", deltaData)
+			flusher.Flush()
+		}
+	}
+
+	// 7. 发送结束标记（附带元数据）
+	endData, _ := json.Marshal(map[string]interface{}{
+		"message_id": messageID,
 		"mode":       req.Mode,
-		"message_id": fmt.Sprintf("msg-%d", time.Now().UnixNano()),
-	}
+		"segments":   segments,
+		"done":       true,
+	})
+	fmt.Fprintf(w, "data: %s\n\n", endData)
+	flusher.Flush()
+	fmt.Fprintf(w, "data: [DONE]\n\n")
+	flusher.Flush()
 
-	// 语音助手模式断句
-	if req.Mode == "voice_assistant" {
-		resp["segments"] = llm.SplitIntoSegments(llmResp.Content)
+	// 8. 异步提取记忆
+	if memExtractor != nil && fullContent != "" {
+		go memExtractor.ExtractAndStore(context.Background(), req.UserID, req.SessionID, req.Message, fullContent)
 	}
 
 	// Ensure unused variables don't cause compile errors
 	_ = personaLoader
 	_ = memRetriever
 	_ = memExtractor
-w.Header().Set("Content-Type", "application/json")
-json.NewEncoder(w).Encode(resp)
+	_ = messageID
 }
 
 // handleMemorySearch 处理记忆搜索请求
@@ -383,6 +441,40 @@ case http.MethodGet:
 		"total":    len(memories),
 	})
 
+case http.MethodDelete:
+	// 删除单条记忆: DELETE /api/v1/memory?id=xxx
+	memoryID := r.URL.Query().Get("id")
+	if memoryID == "" {
+		http.Error(w, "缺少 id 参数", http.StatusBadRequest)
+		return
+	}
+
+	if memStore == nil {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusServiceUnavailable)
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"error": "记忆系统未就绪",
+		})
+		return
+	}
+
+	ctx := r.Context()
+	if err := memStore.Delete(ctx, memoryID); err != nil {
+		log.Printf("[memory] 删除失败: %v", err)
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusInternalServerError)
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"error": "删除失败",
+		})
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(map[string]interface{}{
+		"status":    "deleted",
+		"memory_id": memoryID,
+	})
+
 case http.MethodPost:
 	// 手动添加记忆
 	var req struct {