What is the problem this feature would solve?

In #5845 I was testing with an outdated version of bun. Although I was creating a project from scratch, it is possible to catch similar compatibility issues among developers of a given repo by using the "engines" field of package.json — in particular, bun could show a compatibility warning (optionally overridable) instead of erroring deep in implementation code.

For those of us testing various versions of bun, this could be particularly useful to avoid head-scratching situations. It's also just generally useful for any project that is using features of bun as they become available, if any of those projects are checked out by multiple developers or on multiple devices.

What is the feature you are proposing to solve the problem?

Support "bun" version ranges in the "engines" field of package.json for both the project and dependencies.

What alternatives have you considered?

Leave things as-is, especially if it's a performance concern?