I work on SpriteShip. I checked the free browser export with a synthetic 12×4 PNG split into three 4×4 frames: asymmetric edge pixels, partial transparency, and one entirely blank frame. With individual trimming and durations of 80/160/240 ms, reconstructing the exported atlas frames using the JSON offsets reproduced all three original RGBA frames exactly; the blank stayed at index 2 and the durations were retained. This was a browser PNG/ZIP roundtrip check, not an engine-import test. No failure found in that case. A small documented loader example showing how to apply the offsets to the original canvas would be useful alongside the general atlas schema.