feat: 接入fastapi

app/main.py

@@ -0,0 +1,38 @@
+"""FastAPI 应用入口"""
+
+import asyncio
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+
+from app.api.agent import router
+from app.core.exceptions import register_exception_handlers
+
+
+@asynccontextmanager
+async def lifespan(application: FastAPI):
+    from app.clients.decision import close_decision_engine
+    from app.observability.tracing import flush_tracing
+    from app.processor.graph import build_graph
+    from app.services.agent import AgentService
+
+    application.state.agent_service = AgentService(build_graph())
+    try:
+        yield
+    finally:
+        # 共享客户端只在应用退出时关闭，追踪刷新放到线程避免阻塞事件循环
+        try:
+            await close_decision_engine()
+        finally:
+            await asyncio.to_thread(flush_tracing)
+
+
+def create_app() -> FastAPI:
+    application = FastAPI(title="Screen Agent API", lifespan=lifespan)
+    # 统一处理请求校验、HTTP 错误和未捕获异常
+    register_exception_handlers(application)
+    application.include_router(router)
+    return application
+
+
+app = create_app()