refactor: add configuration dependency ratchet

tests/test_agent_system_settings_tools.py

@@ -16,6 +16,21 @@ from app.schemas.types import SystemConfigKey
 
 
 class TestAgentSystemSettingsTools(unittest.TestCase):
+    def test_query_system_settings_accepts_injected_reader(self):
+        """Agent 配置工具通过窄端口读取授权字段，无需自行构造数据库 Oper。"""
+        reader = MagicMock()
+        reader.get.return_value = [{"name": "qb", "enabled": True}]
+        tool = QuerySystemSettingsTool(
+            session_id="session-injected",
+            user_id="10001",
+            system_config=reader,
+        )
+
+        payload = json.loads(asyncio.run(tool.run(setting_key="Downloaders")))
+
+        self.assertTrue(payload["success"])
+        reader.get.assert_called_once_with(SystemConfigKey.Downloaders)
+
     def test_query_system_settings_returns_exact_systemconfig_value(self):
         tool = QuerySystemSettingsTool(session_id="session-1", user_id="10001")