Identity
A stable package ID lets a later export safely replace the installed version.
Main chassis
PNG is recommended. Its natural pixel size becomes the fixed window size and is checked again by the app during import.
Main regions
Later regions draw and hit-test above earlier ones.
Docked panels
Playlist, library, or equaliser surfaces can attach to any chassis edge.
Export
The package contains skin.json and every uploaded image. Invalid geometry or missing resources block export.