fix(database): decouple worker errors from application

app/application/database.py

@@ -18,14 +18,6 @@ DatabaseProbe = Callable[[], Optional[str]]
 T = TypeVar("T")
 
 
-class DatabaseWorkerClosedError(RuntimeError):
-    """数据库执行器尚未启动或已经停止。"""
-
-
-class DatabaseWorkerOverloadedError(RuntimeError):
-    """数据库执行器的运行与排队容量已经用尽。"""
-
-
 class AsyncDatabaseExecutor(Protocol):
     """让异步业务调用同步短事务而不阻塞事件循环。"""
 

app/application/messaging/chat.py

@@ -10,10 +10,12 @@ from weakref import WeakValueDictionary
 
 from app.application.database import (
     AsyncDatabaseExecutor,
+)
+from app.schemas.agent import AgentChatSessionDetail, AgentChatSessionSummary
+from app.schemas.exception import (
     DatabaseWorkerClosedError,
     DatabaseWorkerOverloadedError,
 )
-from app.schemas.agent import AgentChatSessionDetail, AgentChatSessionSummary
 from app.runtime.observability import record_metric
 
 

app/application/plugin/install.py

@@ -7,7 +7,7 @@ from collections.abc import Awaitable, Callable
 from dataclasses import dataclass, field
 from typing import Any, Optional
 
-from app.application.database import DatabaseWorkerOverloadedError
+from app.schemas.exception import DatabaseWorkerOverloadedError
 from app.application.plugin.lifecycle import plugin_lifecycle
 from app.runtime.log import logger