In the age of Claude Code and other MCPs, the last thing I want is my commit history to be mutable. I've added instructions to Claude which make a commit before each modification with a summary of the conversation that caused the change. Once I'm happy with the work, I squash the commits and push up. (Which I believe is more or less equivalent to the jj workflow.)
This flow can work with jj also. It would probably be exactly the same. You'd do `jj new` and have Claude set the description and make its changes. When you're ready for the next round, you'd repeat and do `jj new` again for the next revision.
I think jj's mutable revisions are best thought of as automation around `git commit --amend && rebase_everything_after_this_commit`. If you're not using that kind of flow with Claude, you wouldn't use that kind of flow with jj either.