If you're touching React vendoring in Next.js or working around the react-server layer boundary, you need this. Next.js doesn't pull React from node_modules for App Router. It vendors stable and experimental builds into packages/next/src/compiled/ during build. The tricky part is entry-base.ts: it's the only file compiled in the react-server layer, so all Flight server API imports must route through it or you'll hit "react-server condition must be enabled" errors in production (dev mode hides this). The skill covers the webpack aliasing setup, type declarations in $$compiled.internal.d.ts, and the boundary rules that will save you from runtime failures.
npx skills add https://github.com/vercel/next.js --skill react-vendoring