refactor: reorganize startup persistence boundaries

tests/test_db_plugin_message_agent_queries.py

@@ -352,13 +352,10 @@ def test_agenttask_get_for_user_enforces_ownership(db):
     assert AgentTask.get_for_user(db.session, task_id, user_id="bob") is None
 
 
-def test_agenttask_model_queries_keep_no_session_plugin_abi(db, monkeypatch):
-    """旧插件省略 Session 时仍可按原关键字参数查询 Agent 任务。"""
+def test_agenttask_model_queries_keep_no_session_plugin_abi(db):
+    """旧插件省略 Session 时仍由统一 legacy 装饰器按原参数查询。"""
     task_id = AgentTask.add_task(db.session, **_task("legacy", user_id="legacy-user"))
-    monkeypatch.setattr(
-        "app.db.models.agenttask.run_legacy_sync_query",
-        lambda operation: operation(db.session),
-    )
+    db.session.commit()
 
     assert AgentTask.get_for_user(
         task_id=task_id,