统一 Repository 方案：添加 db 基类和子图模型 + 通讯录 API 支持真实数据库

backend/app/backend.py

@@ -23,6 +23,8 @@ from .agent_subgraphs.common.human_review import (
     ReviewStatus,
     HumanReview
 )
+from .agent_subgraphs.contact.api_client import ContactAPIClient
+from .db.init_db import init_subgraph_tables
 from .logger import info, error
 
 @asynccontextmanager
@@ -32,6 +34,9 @@ async def lifespan(app: FastAPI):
     async with AsyncPostgresSaver.from_conn_string(DB_URI) as checkpointer:
         await checkpointer.setup()
         
+        # 1.5 初始化子图表
+        await init_subgraph_tables(checkpointer.conn)
+        
         # 2. 构建 AI Agent 服务
         agent_service = AIAgentService(checkpointer)
         await agent_service.initialize()
@@ -39,6 +44,9 @@ async def lifespan(app: FastAPI):
         # 3. 创建历史查询服务
         history_service = ThreadHistoryService(checkpointer)
         
+        # 3.5 创建子图 API 客户端（真实数据库模式）
+        contact_api = ContactAPIClient(checkpointer.conn)
+        
         # 4. 创建审核管理器
         review_manager = ReviewManager(InMemoryReviewStore())
         
@@ -46,6 +54,7 @@ async def lifespan(app: FastAPI):
         app.state.agent_service = agent_service
         app.state.history_service = history_service
         app.state.review_manager = review_manager
+        app.state.contact_api = contact_api
         
         # 应用运行中...
         yield