Your files stay on this computer. Build a named animation pack without rewriting its sprite image. Native Godot compatibility is still unverified.
One PNG, scale 1, forward looping tags. No rotation, slices, finite repeats or multiple sheets. Try fixtures/pack-a, then the differently arranged pack-b.
fixtures/pack-a
pack-b
Ready for local files.
Blue outline: original canvas. Pink cross: canvas center.
Place the saved JSON beside the unchanged PNG. Keep its filename. See README for loader setup and limits.