Install `packageManager` (replace corepack)

[styfle]

Since corepack is being phased out starting in node@25, it would be great if fnm could manage both the node version and the package manager (for example pnpm) in order to replace corepack.

Ideally both package.json#packageManager as well as package.json#devEngines.packageManger should be read by fnm.

[SukkaW]

corepack is not going away anyway. Probably just let fnm install corepack automatically?

[ljharb]

No, but it's no longer part of node, so it doesn't really make sense for a node version manager to interact with it or to install it.

[SukkaW]

No, but it's no longer part of node, so it doesn't really make sense for a node version manager to interact with it or to install it.

If so, it also makes no sense for a node version manager to interact with package managers or install them as well. Neither pnpm nor yarn is a part of Node.js in the very first place.

[ljharb]

Yes, that's also correct - but this isn't isn't about those.

[rose-bouchayer]

I do understand that the current scope of this project is only to manage Node.js version but sadly I had to migrate from fnm to proto in order to handle all my JavaScript stack versions (Node.js + pnpm).

It would be a great addition to fnm to make it easily manage the whole stack, from engine to package manager.

[zanminkian]

Ideally both package.json#packageManager as well as package.json#devEngines.packageManger should be read by fnm.

If I were the maintainer of fnm, I will make fnm to only support package.json#devEngines field and drop support for engines and packageManager fields. It consults both package.json#devEngines.runtime and package.json#devEngines.packageManager. When user enter into a project, fnm auto switch the node and npm(pnpm or yarn) shims to currect versions.