React Compiler

The packages with React views (UI, Charts, Terminal, Agent views and Editor views) ship a dist built with the React Compiler, so their components and hooks memoize themselves. The compiled code imports react/compiler-runtime, which comes with React 19.

Reading the sources

The source condition serves uncompiled TypeScript, which has no hand-written useMemo or useCallback. Without the compiler the views still work, but redraw whenever their parent does.

To keep the memoization, run babel-plugin-react-compiler with target: '19' over these sources, in Vite through reactCompilerPreset of @vitejs/plugin-react. If your bundler setup skips node_modules, include the src of these packages. A production build without the source condition uses the compiled dist.

What stays uncompiled

A function that starts with 'use no memo' stays uncompiled, in dist too. So does one the compiler cannot prove safe.