diff --git a/app/api/deps.py b/app/api/deps.py
index 6073df004..9007667af 100644
--- a/app/api/deps.py
+++ b/app/api/deps.py
@@ -5,7 +5,6 @@
 """
 
 from app.api.dependencies.agent import (
-    get_agent_chat_persistence,
     get_agent_chat_service,
     get_message_query_service,
 )
@@ -53,7 +52,6 @@ from app.api.dependencies.workflow import (
 
 # 兼容聚合入口只显式列出既有 FastAPI 依赖，不向插件制造新的动态导出规则。
 __all__ = [
-    "get_agent_chat_persistence",
     "get_agent_chat_service",
     "get_auth_service",
     "get_current_active_manage_user",
diff --git a/app/factory.py b/app/factory.py
index 8c947c741..7db6a5e82 100644
--- a/app/factory.py
+++ b/app/factory.py
@@ -14,7 +14,10 @@ from app.adapters.observability.otel import build_observation_port
 from app.adapters.web.plugin.routes import FastAPIDynamicRouteRegistry
 from app.adapters.web.health import install_health_routes
 from app.application.plugin.routes import configure_plugin_routes
-from app.application.database import DatabaseWorkerOverloadedError
+from app.application.database import (
+    DatabaseWorkerClosedError,
+    DatabaseWorkerOverloadedError,
+)
 from app.adapters.web.security.access import (
     configure_token_codec,
     verify_apikey,
@@ -234,9 +237,9 @@ async def localized_http_exception_handler(
 
 async def database_worker_overloaded_handler(
         request: Request,
-        _exc: DatabaseWorkerOverloadedError,
+        _exc: DatabaseWorkerClosedError | DatabaseWorkerOverloadedError,
 ) -> JSONResponse:
-    """将数据库短事务背压映射为可重试的 503 响应。"""
+    """将数据库 worker 暂不可用映射为可重试的 503 响应。"""
     return await localized_http_exception_handler(
         request,
         HTTPException(
@@ -335,6 +338,10 @@ def create_app() -> FastAPI:
         DatabaseWorkerOverloadedError,
         database_worker_overloaded_handler,
     )
+    _app.add_exception_handler(
+        DatabaseWorkerClosedError,
+        database_worker_overloaded_handler,
+    )
     _app.add_exception_handler(
         RequestValidationError,
         localized_validation_exception_handler,
diff --git a/tests/test_api_response.py b/tests/test_api_response.py
index c4419d92e..65cac63c4 100644
--- a/tests/test_api_response.py
+++ b/tests/test_api_response.py
@@ -23,7 +23,10 @@ from app.factory import (
     localized_unhandled_exception_handler,
     localized_validation_exception_handler,
 )
-from app.application.database import DatabaseWorkerOverloadedError
+from app.application.database import (
+    DatabaseWorkerClosedError,
+    DatabaseWorkerOverloadedError,
+)
 from app.runtime.localization import LocaleHelper
 from app.runtime.config import settings
 from app.schemas.common import JsonData
@@ -67,6 +70,10 @@ def api_app() -> FastAPI:
         DatabaseWorkerOverloadedError,
         database_worker_overloaded_handler,
     )
+    app.add_exception_handler(
+        DatabaseWorkerClosedError,
+        database_worker_overloaded_handler,
+    )
     from fastapi.exceptions import RequestValidationError
 
     app.add_exception_handler(
@@ -125,6 +132,11 @@ def api_app() -> FastAPI:
         """模拟数据库短事务容量耗尽。"""
         raise DatabaseWorkerOverloadedError("worker full")
 
+    @app.get("/database-closed")
+    async def get_database_closed() -> None:
+        """模拟数据库 worker 在关闭态拒绝新任务。"""
+        raise DatabaseWorkerClosedError("worker closed")
+
     @app.get("/native", response_model=None)
     async def get_native_response() -> dict[str, bool]:
         """返回显式旁路的原生 JSON 协议。"""
@@ -219,6 +231,22 @@ async def test_database_worker_overload_is_retryable_service_unavailable(
     }
 
 
+async def test_database_worker_closed_is_retryable_service_unavailable(
+        api_app: FastAPI,
+):
+    """数据库 worker 关闭态应返回 503，而不是落入通用 500。"""
+    async with make_client(api_app) as client:
+        response = await client.get("/database-closed")
+
+    assert response.status_code == 503
+    assert response.headers["retry-after"] == "1"
+    assert response.json() == {
+        "success": False,
+        "message": "服务当前繁忙，请稍后重试",
+        "data": None,
+    }
+
+
 @pytest.mark.parametrize(
     "path",
     [