diff --git a/backend/app/main.py b/backend/app/main.py
index f4c2bbc..7f6276e 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -8,7 +8,7 @@ from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse
 
 from app.core.config import settings
-from app.core.database import init_db, Base
+from app.core.database import init_db, Base, engine
 from app.core.security import verify_token
 from app.api.books import router as books_router
 from app.api.chat import router as chat_router
@@ -25,7 +25,12 @@ from app.models.mcp_server import McpServer
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     await init_db()
-    yield
+    try:
+        yield
+    finally:
+        # 优雅停机：主动销毁连接池，避免 SQLite 后台线程的连接被 GC 丢弃
+        # （表现为 shutdown 时 SAWarning：non-checked-in connection ... dropped）
+        await engine.dispose()
 
 
 app = FastAPI(title="BookMate", version="0.1.0", lifespan=lifespan)