`swarm.domain` is not the value swarm-controller addresses this hive with —
`swarm-controller.nix` builds `SWARM_CONTROLLER_PUBLIC_URL` from
`swarm.ui.domain`, which merely defaults to it and is documented as
overridable. Allowing the one and being delivered the other would work until
someone takes that option up, then fail as a refused delivery with nothing
naming the cause.
Also states why the entry is NOT gated on `deploy.swarm-ui.enable`, which is
what makes the controller register the hooks at all: in a spread deployment the
forge and the swarm UI are different hosts, so that per-host flag is false
exactly where the allow-list entry is needed.
The comment-block lint caught the prose at 35 lines; trimmed to the parts a
reader cannot re-derive.