前端修改

app/backend.py

@@ -5,14 +5,17 @@ FastAPI 后端 - 支持动态模型切换，使用 PostgreSQL 持久化记忆
 
 import os
 import uuid
+import json
 from contextlib import asynccontextmanager
 
 from dotenv import load_dotenv
-from fastapi import FastAPI, HTTPException, WebSocket, WebSocketDisconnect, Depends, Request
+from fastapi import FastAPI, HTTPException, WebSocket, WebSocketDisconnect, Depends, Request, Query
 from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import StreamingResponse
 from pydantic import BaseModel
 from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver
 from app.agent import AIAgentService
+from app.history import ThreadHistoryService
 from app.logger import debug, info, warning, error
 
 # 加载 .env 文件
@@ -37,13 +40,17 @@ async def lifespan(app: FastAPI):
         agent_service = AIAgentService(checkpointer)
         await agent_service.initialize()
         
-        # 3. 将服务实例存入 app.state
+        # 3. 创建历史查询服务
+        history_service = ThreadHistoryService(checkpointer)
+        
+        # 4. 将服务实例存入 app.state
         app.state.agent_service = agent_service
+        app.state.history_service = history_service
         
         # 应用运行中...
         yield
         
-        # 4. 关闭时自动清理数据库连接（async with 负责）
+        # 5. 关闭时自动清理数据库连接（async with 负责）
         info("🛑 应用关闭，数据库连接池已释放")
 
 
@@ -90,6 +97,11 @@ def get_agent_service(request: Request) -> AIAgentService:
     return request.app.state.agent_service
 
 
+def get_history_service(request: Request) -> ThreadHistoryService:
+    """从 app.state 中获取全局 ThreadHistoryService 实例"""
+    return request.app.state.history_service
+
+
 # ========== HTTP 端点 ==========
 @app.post("/chat", response_model=ChatResponse)
 async def chat_endpoint(
@@ -124,6 +136,75 @@ async def chat_endpoint(
     )
 
 
+# ========== 历史查询接口 ==========
+@app.get("/threads")
+async def list_threads(
+    user_id: str = Query("default_user", description="用户 ID"),
+    limit: int = Query(50, ge=1, le=200, description="返回数量限制"),
+    history_service: ThreadHistoryService = Depends(get_history_service)
+):
+    """获取当前用户的对话历史列表"""
+    threads = await history_service.get_user_threads(user_id, limit)
+    return {"threads": threads}
+
+
+@app.get("/thread/{thread_id}/messages")
+async def get_thread_messages(
+    thread_id: str,
+    user_id: str = Query("default_user", description="用户 ID"),
+    history_service: ThreadHistoryService = Depends(get_history_service)
+):
+    """获取指定线程的完整消息历史"""
+    messages = await history_service.get_thread_messages(thread_id)
+    return {"messages": messages}
+
+
+@app.get("/thread/{thread_id}/summary")
+async def get_thread_summary(
+    thread_id: str,
+    user_id: str = Query("default_user", description="用户 ID"),
+    history_service: ThreadHistoryService = Depends(get_history_service)
+):
+    """获取指定线程的摘要信息"""
+    summary = await history_service.get_thread_summary(thread_id)
+    return summary
+
+
+# ========== 流式对话接口 ==========
+@app.post("/chat/stream")
+async def chat_stream_endpoint(
+    request: ChatRequest,
+    agent_service: AIAgentService = Depends(get_agent_service)
+):
+    """流式对话接口（SSE）"""
+    if not request.message:
+        raise HTTPException(status_code=400, detail="message required")
+
+    thread_id = request.thread_id or str(uuid.uuid4())
+    
+    async def event_generator():
+        try:
+            async for chunk in agent_service.process_message_stream(
+                request.message, thread_id, request.model, request.user_id
+            ):
+                yield f"data: {json.dumps(chunk, ensure_ascii=False)}\n\n"
+            yield "data: [DONE]\n\n"
+        except Exception as e:
+            error(f"流式响应异常: {e}")
+            yield f"data: {json.dumps({'type': 'error', 'message': str(e)}, ensure_ascii=False)}\n\n"
+            yield "data: [DONE]\n\n"
+    
+    return StreamingResponse(
+        event_generator(),
+        media_type="text/event-stream",
+        headers={
+            "Cache-Control": "no-cache",
+            "Connection": "keep-alive",
+            "X-Accel-Buffering": "no",  # 禁用 Nginx 缓冲
+        }
+    )
+
+
 # ========== WebSocket 端点（可选） ==========
 @app.websocket("/ws")
 async def websocket_endpoint(