Sprite sheet authoring

Sprite pack items support optional animation metadata. See also the Authoring spec.

Pack editor (current)

• Sprite uploads use the same queue letterbox as overlays (256×256 preview → 1024×1024 stored).
• There is no metadata form in the UI yet — static sheets work; animated sheets need API metadata.

Sprite metadata JSON

Post as spriteMetadata on upload when kind=sprite:

{
  "layout": "horizontal",
  "frameWidth": 128,
  "frameHeight": 128,
  "frames": 8,
  "fps": 8,
  "loop": true
}

• layout: horizontal or grid (required)
• frameWidth, frameHeight: integers 8–4096 (required)
• Optional: frames (1–1024), cols/rows (1–512), fps (0–60), loop

Art guidelines

• Square master sheet when possible; same safe-zone rules as overlays.
• Frame dimensions must divide the sheet layout evenly.
• PNG with transparency; under 20MB.