update agent

agent/app/core/service_manager.py

@@ -25,6 +25,11 @@ class ServiceManager:
     def reset_failed(self, service_name: str) -> None:
         self.command_runner.run(["systemctl", "reset-failed", service_name])
 
+    def assert_service_active(self, service_name: str) -> None:
+        result = self.command_runner.run(["systemctl", "is-active", service_name])
+        if result.stdout.strip() != "active":
+            raise RuntimeError(f"Service is not active: {service_name}")
+
     def get_service_status(self, service_name: str) -> dict[str, object]:
         active = self._query(["systemctl", "is-active", service_name]) == "active"
         enabled = self._query(["systemctl", "is-enabled", service_name]) == "enabled"