The viewer hands a video or audio file to the browser untouched — container, codec and
all — and the browser plays what it can; when it can't, the viewer says so and offers the
download. What the server adds is the part a player needs: /api/files/read now goes
through http.ServeContent for a real file of known size, so Range requests (seeking) and
HEAD work, and a download can resume. The root backend's helper takes an offset for that,
and a Seeker opens the backend once, at the range asked for, instead of streaming from
the top. Audio files are a preview kind too: their cover art is the thumbnail.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
