Splits the two hostnames across one deployment. No files move: the Next app still
serves every route on both hosts, and the middleware decides per host which paths it
owns and 301s the rest. /login and /signup stay on www - all 82 marketing CTAs point
at /signup, which carries a hard canonical to www plus ad traffic.
src/lib/hosts.ts is the single source of truth for the boundary (APP_PATH_PREFIXES,
isAppPath, wwwUrl, appUrl, urlForPath). The middleware and every absolute-URL builder
read from it so they cannot drift apart.
- Split the overloaded NEXT_PUBLIC_APP_URL into a www and an app origin. It previously
fed both public URLs and in-app URLs, so any single value was wrong somewhere. Most
important: QRCodeCard encodes this origin into the QR code the user downloads and
prints, so it must stay on www.
- Route Stripe return URLs, email links and OAuth redirects per path rather than
against one origin, so /dashboard lands on app and /pricing on www.
- Cross the host boundary once, after a successful login: the router cannot push across
origins, so that jump needs a full load. The user arrives signed in because the
session cookie is scoped to COOKIE_DOMAIN.
- Keep the app host out of search indexes: X-Robots-Tag on every response plus a
Disallow-all robots.txt via rewrite, and /sitemap.xml redirects to www.
- Point the TikTok callback fallback at www explicitly. It used to read
NEXT_PUBLIC_APP_URL, whose meaning changed here, and only the apex domain is
verified with TikTok.
Host splitting is inert while both origins are equal, so development is unaffected.
Verified: tsc clean, production build succeeds including the Edge middleware bundle,
and the path-to-host mapping is unit-checked (prefix traps like /created and
/settings-guide stay on www, query strings do not break matching).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
