How to Sync Design Tokens Between React and Flutter (Without Losing Your Mind)

Style Dictionary's Flutter support has been broken for years. I built tokensync — a CLI that generates CSS and Flutter ThemeData from one tokens.json file, then verifies they match numerically. Your designer just updated the brand color. You open your CSS file. Update --color-brand-500. Then you open your Flutter file. Update AppTheme._lightColors.primary. Then you grep for anywhere else it might appear. Then you do the same for dark mode. Then you hope you got them all. Three weeks later a designer screenshots both apps side by side. The web button is #5C6BC0. The mobile button is #5B6BC0. Off by one digit. Nobody noticed. It shipped. If you maintain both a React web app and a Flutter mobile app, this is a design token sync problem — and it costs teams 6–20 hours every time tokens change. Why existing design token tools don't solve this Style Dictionary is the industry standard for design token transformation. It's genuinely great for CSS. But its Flutter support produces flat key-val