[diego898]

How does this work with a shared remote branch? I know in git when you alter your history you can do a `git push --force-with-lease` as a safer `--force` - do you have to do this frequently with jj "rewriting history" (from a git perspective)?

[gcr]

Jj lets you edit:

- History you haven't pushed yet, or

- Bookmarks that you're tracking (meaning you're actively working on these branches), except "main"

History behind "main" or behind any untracked remote bookmark is immutable by default.

If you want to move "main" or any remote bookmark to a commit that isn't a descendant, you have to use `--allow-backwards`. If you want to edit one of these commits, you can use `--ignore-immutable`. Using either of these options is like a `push -f` in git terminology.

[cube2222]

Yeah, `jj git push` acts as an equivalent (according to my experience and understanding) to `git push --force-with-lease`, always.

You don't have to pass an explicit --force, nor an explicit lease-related argument. As you say, rewriting the commits underlying changes happens frequently, so this would otherwise be pretty annoying.

There's also `jj git push --dry-run` to preview which branches would be updated in what way.

[diego898]

Thanks that makes sense - just feels weird to go from years of “be very careful rewriting history with git, especially at work” to jj rewriting everything all the time - can’t shake the feeling there’s a clash somewhere waiting to happen

[cube2222]

You can customize the immutable commits option to specify which commits you want to be blocked from changing.

By default that’s only the main branch and untracked remote branches. For me that makes sense as I’m generally fine with constantly rewriting my feature branches.

However, if you want it to e.g. block you from rewriting anything that you’ve already pushed to the remote, you can set it to treat anything that’s pushed to the remote as immutable, too, as another commenter described [0].

[0]: https://news.ycombinator.com/item?id=42940329

[gcr]

As long as you don't use `--allow-backward` or `--ignore-immutable`, and as long as everyone sticks to their own feature branches, this shouldn't be possible.

The operation log makes jj quite safe. There's a command to restore the entire working copy + history to an earlier state in case you screw something up. Even this operation log is itself versioned, so you can undo the undo if you screwed the undo up, ad infinitum. :)

[ashenke]

For every feature we usually have two developers working on it, one frontend and one backend, working on the same feature branch. Would Jujitsu cause a problem in this context?

[stouset]

I haven't used this workflow personally, but it should be fine.

`jj git push` does an equivalent to `--force-with-lease`, so if there are remote commits that are later than what your current bookmark points to, it won't overwrite them. You can `jj git fetch`, it'll update your bookmark, and you can choose to put your new commits onto the updated sequence of commits wherever they belong.

[steveklabnik]

Just to be clear, as with git, you don’t have to rebase. It’s just that doing so is nicer in jj. But if rewriting commits on a shared branch becomes onerous, don’t do that!