It would be really neat if we could specify:

: package.json |> npm install --omit=dev --no-package-lock |> node_modules/

And for Tup to then automatically rerun npm any time the package.json file changes.

I would imagine that any non-generated files present in node_modules/ in that case would trigger an error, as it would have to be a generated folder. Also, other rules writing to node_modules/ or a subdirectory thereof would likely also have to trigger an error.

Just sharing as a random idea. npm is not a particularly useful usecase; perhaps there is some way that tar could be a useful folder-generating command, but.. hm, maybe someone else will come with a better usecase in mind? 😅