[houko]

Summary

Library cards, the hero and each film's cover.jpg showed a frame ffmpeg grabbed from the downloaded video, even though the site had already given the video a cover (it was used on the processing card and then replaced once the download finished). Posters now come from the video itself:

1. A film from a site: the picture the site gives it (job.Thumbnail, already saved in library.json). It is fetched once into the posters cache, which the processing card's thumbnail already uses, so a film that just finished downloading usually needs no new request.
2. A local video: the cover art its file carries (an MP4/MKV attached picture), read with ffmpeg -map 0:v -map -0:V -c copy (new media.EmbeddedCover).
3. Fallback: only a video with neither keeps the cover.jpg it already has, or has a frame grabbed as before. This covers a site that no longer serves the picture (for example TikTok's signed thumbnail URLs expire) or a machine that is offline.

cover.jpg is rewritten whenever its bytes differ from the video's own cover, so existing libraries swap their grabbed frames for the site's picture on the next load. The rewrite is idempotent and needs no new field in library.json. Non-JPEG pictures (YouTube's WebP thumbnails, PNG cover art) are re-encoded as JPEG so cover.jpg stays a JPEG. That needs the golang.org/x/image/webp decoder, which apps/kando already had as an indirect dependency through MyGo; go.mod only moves it to the direct block, at the same version v0.47.0.

Screenshots

The hero of the screenshot fixture, before (a frame grabbed from the video) and after (the site's picture; the fixture stands in for the site with its generic scene at 1920 px, so the difference is visible offline):

Test plan

• CGO_ENABLED=0 go test ./packages/core/... ./packages/media/... ./apps/kando/... passes
• go tool mygo vet . in apps/kando is clean
• New tests:
  • TestEmbeddedCover (real ffmpeg): cover art comes back byte for byte, and a video without cover art has none
  • TestPosterIsTheSitesCover: a grabbed cover.jpg is replaced by the site's PNG, saved as JPEG; the picture is fetched once and kept in the cache; finding it again does not rewrite cover.jpg
  • TestPosterKeepsItsCoverWhenTheSiteHasNone: a failed fetch leaves cover.jpg untouched
  • TestPosterOfALocalVideoIsItsCoverArt
  • TestCoverJPEG: WebP becomes JPEG, JPEG stays as is, and an HTML error page is rejected
• KANDO_SCREENSHOTS=… go test -run TestScreenshotsLibrary renders the new library-site-cover scene
• Not checked in the running app against a real download.