Feature request / question: embed cover thumbnail into CBZ file when using `COMIC_INFO` update mode

[yamanobe96]

Hi! First, thank you for komf — it's been very useful for managing large manga libraries.

Current behavior

When updateMode is set to COMIC_INFO, komf successfully writes metadata into the CBZ as ComicInfo.xml. However, when a cover thumbnail is fetched from a provider, it is only uploaded to Komga's internal thumbnail cache via the API (uploadBookThumbnail / uploadSeriesThumbnail). The image bytes are never written into the CBZ file itself.

This means the cover exists only in Komga's database, not in the actual file on disk.

Desired behavior

I'd like an option (e.g. embedCoverInCbz: true) where, in addition to uploading to Komga, the fetched thumbnail is also embedded into the CBZ archive as cover.jpg (or cover.png). This would make the cover truly portable — if the Komga library is scanned fresh, rebuilt, or migrated, the cover survives.

Why this matters for COMIC_INFO mode specifically

The whole point of COMIC_INFO mode seems to be making metadata self-contained in the file rather than only in the server's database. It feels natural to extend that philosophy to cover images as well.

Implementation sketch

Looking at the source, ComicInfoWriter already rewrites the ZIP in-place (creating a temp file and atomically replacing). Adding a writeCoverImage(localPath, image) method alongside writeMetadata() seems straightforward. MetadataUpdater.updateBookMetadata() could then call it when the new flag is set.

Questions

• Is there a reason this was intentionally left out? (e.g. file size concerns, format compatibility, Komga behavior)
• Would you be open to a PR implementing this as an opt-in option?

Thanks!

[ThoughtzThruKeyz]

I think this would help Kavita as well, because similarly to like you said, i believe it only uploads into the cache because when said series is scanned or analyzed, it falls back to the default cover from the metadata.