Since some unknown version (Debian 11 satisfies this requirements) both QEMU and remote-viewer support spice protocol over Unix Domain socket.

So, it seems to be good idea to use it for vws. Or at least support optionally. Using socket inside VM directory solves problem with limited TCP port count which now causes us to use first free port and make VE URI Dependdent from start order.

Syntax

QEMU: -spice unix,addr=relative.path,disable ticketing

remote-viewer: spice+unix:///absolute/path