Check a foundation
Pick one of the six study faces, choose how the photo is framed, and optionally list a foundation bottle you already own. The engine then checks the framing, checks your shelf first, ranks the fixture catalog by colour distance, and prints a receipt: BUY, SHADE-RISK, NO, or CAN'T TELL, with its working shown.
Live check
Judges with the event passcode can run the same check on a real photo below. It makes one live Skin Tone call, spends real units under server-side caps, and prints a receipt labelled LIVE from the same engine, ranked against the licensed shade catalog (The Pudding foundation shades dataset, 2018 swatches, MIT License). A BUY receipt also renders a labelled try-on preview of the winning shade for 1 extra unit; the preview never affects the verdict.