That’s it. That’s the genius algorithm. It’s a JSON file that precisely defines the size and position of these avatars.
This probably isn’t generated programmatically – it’s likely a designer somewhere at Apple, meticulously moving circles around on a canvas, nudging them pixel by pixel until they strike the right visual balance. The file is filled with truly hideous numbers that have no place in a design system — 23.5, 7.5, -6 — but it all works.
We even wrote a test app that parses this JSON file, just so we could confirm our suspicions.