React vendoring and react-server layer boundaries. Use when editing entry-base.ts, $$compiled.internal.d.ts, compiled/react* packages, or taskfile.js copy_vendor_react. Covers the entry-base.ts boundary (all react-server-dom-webpack/* imports must go through it), vendored React channels, type declarations, Turbopack remap to react-server-dom-turbopack, ComponentMod access patterns, and ESLint suppression for guarded requires.