The guide asked for a hostname and served the interface on
`app.${DOMAIN}` with the API on `api.${DOMAIN}` — which is not what
someone with a box in a cupboard sets up, and could not be made to work
by typing an address into a browser. `compose.lan.yml` already solves it
for the dev stack; the same file layers onto the production one, so the
guide now opens with that and keeps the hostname as the other option.
The reference gained the setting behind it. `VITE_API_URL` is a build
argument of the frontend image rather than something the stack reads,
which is worth saying once: empty means the interface addresses the API
relative to whatever origin served it, so one image answers on an
address, a hostname and an ssh tunnel alike, and no CORS list has to be
kept in step.
Verified against the production compose layered with `compose.lan.yml`:
the page, `/api` on the same port, a cross-origin-free login, the flow
websocket upgrading through nginx, and `/docs` still refused there.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>