Expo

The Expo team has released Exact, a cross-platform UI framework that runs the same code natively on web, macOS, iOS, and Linux, and is explicitly designed for AI coding agents to build, run, observe, and test apps. In a demo, Claude Code built a todo app and passed tests on all three platforms in about 57 minutes, with 26 KB of code versus React's 81 KB and roughly 99 ms edit latency.