jj version check - upper limit
Given that jj is still not 1.0 we must expect breaking changes. For example, jj 0.33.0 has changed semantics of jj undo.
If a version of lazyjj encounters a version of jj that is more recent than it was tested with, this could cause issues. Therefore I propose a warning at launch of lazyjj if the jj version is too high. The fix is usually to upgrade lazyjj.
I don't see real help for users. If the program is broken, I think it's obvious that you need to update it, or report, that it's broken. Also, what if lazyjj doesn't really have a new version? What if lazyjj will work fine? Then warning will be just annoying
Instead of a warning at launch, it could be shown as output from lazyjj --version.
This would help troubleshooting, and not annoy if everything works.