The Node.js team removed `--experimental-transform-types` from Node.js v26. This makes native, full TypeScript support impossible.

https://github.com/nodejs/typescript/issues/51#issuecomment-...

Node's built-in Typescript support is just for type stripping. That works for a massive amount of TypeScript syntax, but not all of it. It also doesn't bother actually checking the types, just removing them so it runs. You also lose things like tsconfig.

This looks to support both the built-in stripping as well as actual TypeScript.

It says "injects polyfills as needed for APIs like `Worker`, `Temporal`, etc"