Is it really necessary to use transpilePackages for internal packages?

[FelHa]

Summary

In the official documentation regarding internal packages, it states that you need to transpile them in the next.config.js: transpilePackages: ['math-helpers'] (sharing-code).

Also, in the current starter examples (npx create-turbo@latest), @repo/ui is transpiled in the next apps.

However, all next apps work even without transpiling internal packages.

Do you have to transpile internal packages in the next.config? If yes, why? Or is it not necessary? If not, why is it done in both the documentation and the examples?

Ideally, I would like to bundle internal packages in the regular build/dev step without transpiling them in advance.

Additional information

I used npm as a package manager. I would expect, that internal packages are just resolved via symlinks and bundled into the apps.

[anthonyshew]

Answer about Next.js is here: #7058 (comment)