no-referrer downgraded the Origin header to the literal "null" on same-origin non-GET requests (per the WHATWG Fetch "Append a request Origin header" algorithm), which the /api/* csrfOriginCheck then rejected with 403 "bad origin" — silently breaking QR login, cookie save, and every other WebUI POST/PUT/DELETE/PATCH (playback, bot management, user admin). /api/session/* was unaffected because it mounts before the CSRF gate, which is why WebUI login still worked.
same-origin keeps the real Origin on same-origin requests (CSRF passes) while still sending no Referer cross-origin, so B站/NetEase/QQ CDN cover thumbnails keep loading. Adds referrer-policy.test.ts pinning the policy and a csrf.test.ts case for the Origin: "null" rejection.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Bilibili's CDN (i*.hdslb.com) returns 403 with `x-error-info:
RefererWhite` for image requests whose Referer is not on their
whitelist. `CoverArt.vue` already sets `referrerpolicy="no-referrer"`
on its `<img>` tag, BUT the `.cover-shadow` div renders the same URL
as a CSS `background-image`, which ignores the img attribute and uses
the document default policy (`strict-origin-when-cross-origin` in
modern Firefox/Chrome) — that sends `Referer: http://localhost:3000/`
and triggers the block.
Setting `<meta name="referrer" content="no-referrer">` in index.html
applies no-referrer site-wide: covers <img> tags, CSS background-image
fetches, and anywhere else CDNs check referer. Doesn't affect our
/api/* CSRF middleware because that uses Origin (still sent by the
browser), not Referer.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
