pub const WEB_URL_ENV: &str = "MAGI_WEB_URL";Expand description
Environment variable naming the base URL of the web UI, for {url}.
A run cannot discover this by itself: magi web is a different process,
usually started by hand and often on a different machine on the tailnet, and
the address it settled on (Tailscale IP, port, or the fallback it warned
about) exists only in that process. So the operator names it once, in the
environment magi serve runs in - magi web --open prints exactly the
string to use on stdout. Unset means {url} expands to nothing rather than
to a guess: a notification carrying a link to an address nothing is
listening on is worse than one carrying no link at all.