When a theme is uploaded to themes.innioasis.app, we fill in blank placeholders for newer Y1 and Y2 features the package did not include — so your player does not fall back to stock OS icons for those slots.
Firmware adds home and settings icons over time (for example eBook, calendar, calculator, File Manager, and the Rockbox launcher switch). Older themes often omit those keys. Without a placeholder, the device may show its own default artwork in that slot, which breaks the look of the theme.
After you submit a theme, ingest and housekeeping automatically add any missing keys and point them at a blank placeholder image. You do not have to change your package for this default behaviour — it is applied for you.
backfill.png
By default we use a fully transparent transparent.png so the slot stays empty instead of
showing a stock icon. If you prefer a single generic icon everywhere those auto-placeholders would go,
add a file named backfill.png to the theme folder (and to each variant folder that has its
own config.json).
backfill.png is present, new and transparent placeholders use that file instead.config.json are never overwritten.Upload as usual; backfill runs as part of the gallery pipeline.