You still need the HTML served somewhere - running a HTTP server on domain socket is a reasonable way of serving the that if it's at all dynamic, and since you'

You still need the HTML served somewhere - running a HTTP server on domain socket is a reasonable way of serving the that if it's at all dynamic, and since you've already got the socket open why not reuse it and do websocket over it too? Once the socket has transitioned, there's no overhead.