JJ has the concept of "immutable changesets" -- if it sees a commit is referenced from a branch that it's not tracking, it assumes it ought not rebase that commit. Changesets on branches that look like the main branch are immutable too. And you can edit the revset that JJ considers immutable if you need it to be different from the default.
The net effect is that I can change "my" branches as I wish, but I can't change stuff that's been merged or other folks' branches unless I disable the safety features (either using `--ignore-immutable` or tracking the branch).
JJ also makes it really easy to push a single changeset as a branch, which means as you evolve that single commit you can keep the remote updated with your current work really easily. And it's got a specific `jj evolog` command to see how a specific changeset has evolved over time.
The net effect is that I can change "my" branches as I wish, but I can't change stuff that's been merged or other folks' branches unless I disable the safety features (either using `--ignore-immutable` or tracking the branch).
JJ also makes it really easy to push a single changeset as a branch, which means as you evolve that single commit you can keep the remote updated with your current work really easily. And it's got a specific `jj evolog` command to see how a specific changeset has evolved over time.