{
  "mode": "built-in",
  "prompt": "Use case: game-asset. Asset type: transparent sprite atlas for a retro 2.5D casino billiards minigame. Create exactly sixteen separate billiard ball sprites in a clean 4 by 4 equally spaced grid, orthographic straight overhead view, identical radius and center anchor, no perspective. Row 1: white cue ball, solid yellow, solid blue, solid red. Row 2: solid purple, solid orange, solid green, solid burgundy. Row 3: solid black eight ball, yellow stripe on white ball, blue stripe on white ball, red stripe on white ball. Row 4: purple stripe on white ball, orange stripe on white ball, green stripe on white ball, burgundy stripe on white ball. Every colored object ball has a small blank ivory circular number badge centered on top; NO numerals or lettering (engine adds correct digits). Each stripe goes horizontally through center with white caps above and below. Crisp polished shaded pixel art, recognizable high contrast colors, highlight upper left, subtle shading lower right, sharp round contours. Ball-only, no cast shadow outside the ball, no debris, no labels, no cloth, no decoration. Transparent background. Consistent sprite size occupying 65 percent of each grid cell with wide transparent gutters. Square atlas."
}