[arcatek]

Note that we don't recommend using both Yarn and npm: both have different feature sets, heuristics, and implementation details, and as a result your colleagues and you may have slightly different behaviors in development (on top of desync'd dependency trees).

Just like no one would think of letting their developers choose whether they want to bundle their code using either Webpack or Rollup, the package manager should really be enforced at the project level, whether you choose Yarn or npm.

[gavinray]

I understand that there are probably some weird edge cases where this could cause an issue

But I've been doing this for years and so far haven't ran into it

I really don't have the mental energy to fight with people over package managers -- it's just not worth it.

  > your colleagues and you may have slightly different behaviors in development (on top of desync'd dependency trees).

Yarn and NPM both take a "package.json" and install the dependencies so that you can import them though.

If I have "express" in my package.json and do "npm install" or "yarn install" -- the functional outcome is (and always should be) the same

Unless you're using some package-manager specific behavior so that it only works properly or relies on particularities from either yarn/npm/pnpm whatnot, I'm not sure I understand how this could cause problems

But also, you're the lead maintainer of Yarn and I'm just some schmuk who's been on the consuming end for the last many years. I reckon you've got a fair bit more clue here than I do.