I suspect the answer is "it's complicated". For example, you can specify a package version string as `git://...` and it will grab the package from a git repository. It's possible that this uses a JS-native Git implementation, but it's also possible that it uses a locally-installed Git binary, which could in turn use MSCAPI, especially if it's configured to use an external SSH provider.

That's a good point. I'm not too familiar with npm code but it seems that they are indeed using git from the CLI instead using it via a library: https://github.com/npm/cli/blob/ba7f1466436cc22e27f8a14dede3...