The subdomain proxies to the same folder, but the build had the path /feuerwerk/ baked in. On feuerwerk.nockal.com the page loaded its assets, the API and the data URLs from /feuerwerk/... and got 404. The session cookie had Path=/feuerwerk/, so the browser would never have sent it to /api/ there either. - site.ts takes the base path from the folder of the open page: /feuerwerk/ on nockal.com, / on the subdomain. Release links point at the address you are working on. - vite.config.ts builds with a relative base. The copy plugin rewrites the pages to ./dist/assets/ and stops the build if it finds nothing to rewrite. The dev server now runs at http://localhost:5175/. - Auth.php sets the cookie without a Path, so it belongs to the API folder the browser sees. Sign-in and sign-out also clear the old /feuerwerk/ cookie, otherwise it would keep signing in after a logout. Existing sessions stay valid. - README: the new dev server address. Tests: - curl on both addresses: pages, JS, CSS and API 200 - sign-in, session, sign-out on both addresses - e2e 70 against both addresses: 13/13 each, no CSP violation - tsc, lint, prettier clean, site and releases tests 14/14 - PHP tests 7 of 8 files green, videos.test.php fails only because the web-php-fpm container has no ffmpeg Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>