Claude to Figma: keeping AI-generated UI bound to your design system
On one build I found 127 places bound to a raw colour instead of a named role. Every single one had passed visual review. They all surfaced the moment someone asked for dark mode. That number is the whole argument. Not because 127 is large, but because none of them looked wrong. A value that was typed in and a value that came from the system are visually identical. The difference only exists in what happens next. The failure isn't that the agent breaks the rules It's that it extends them. Give an agent a design system and ask it to build. When it reaches something the system covers, it uses the system — genuinely, reliably. When it reaches something the system doesn't cover, it does not stop and ask. It invents. And what it invents is a name that sounds exactly like one of yours, sitting right next to the real ones, reading as though someone chose it on purpose. That's why this is so hard to catch by eye. A fabricated token isn't a glaring error. It's a plausible one. Six months later nobody can tell you whether it was a deliberate exception or a hallucination, and by then five components depend on it. Readable is not the same as closed Making a library available to an agent gets you components it will reuse. It does not get you a closed set. A closed set means: these values exist, everything else does not, and anything outside them fails loudly rather than passing quietly. The distinction sounds pedantic and it decides everything. A readable system produces output that mostly matches. A closed system produces output you can audit. Which is the real test I'd apply to any AI design setup: not how much of your system it covers, but what happens to the things it doesn't cover. If those slip through silently, coverage is irrelevant — you've just made the drift harder to spot. Layers, and not reaching past them Tokens have layers for a reason. Base values underneath — the raw material. Named roles on top — what a value is for. And the product interface binds to the role,