This was brought up by @ljharb during one of our conversations and I'm putting up this RRFC in order to collect early comments and see if anyone can expand upon it and submit a proper RFC in the future.

Essentially the idea here is that it would be nice for the cli to have a more robust or advanced support to saving peer deps ranges from the cli rather than manually handling the package.json file.

npm install [email protected] --save-peer
# would yield a "react": "16.0 || 16.2" in package.json as result

# in a diff package.json containing react as a dep with a range: `~16.0 || ~16.1`
npm install react@~16.5 —save-peer # appends the new range
# would yield a "react": "~16.0 || ~16.1 || ~16.5" in package.json as result

# in that same package.json now forces a diff version
npm install react@~16.5 —save-peer -f # forces semver range
# would  yield a "react": "react": "~16.5" as a result

This type of support can be handy within a workspaces/monorepo setup allowing users to easily manage ranges for peer deps of multiple packages at once.

/cc @npm/cli-team