[dzaima]

Working copy handling differences is certainly an aspect of jj, but, at least for me personally (esp. given me having grown up with git), it's probably my least favorite difference from git. And yet I've moved most of my personal things from git to jj (albeit with a bunch of custom scripts to make the working copy stuff more git-y).

A significant other thing jj does is introduce change IDs (i.e. a (randomly-generated) ID that stays stable even as a commit is amended), with which it should be easier to track changed commits across forks/rebases/edits/pulls/fetches, though I've yet to use jj for collaborative projects to see how much that pans out.

Generally jj makes rebasing things, and generally editing history so much more easy than git, so force-pushes messing with branches is much nicer to "fix" however needed. Being able to leave commits in a conflicted state and resolving only when actually needed also should help.

[paradox460]

One of the quiet bit of genius is that JJ change ids use a different set of characters for base16. Instead of 0-9A-F they use k-z

[sfink]

Technically, it's z-k (z=0, k=15). It makes for a nice root change ID: zzzzzzzz. Less choking than kkkkkkkk.

The relevance, btw, is that you can use git commit IDs in place of change IDs anywhere and they won't conflict; jj knows which you mean by the character set. (They could still conflict with bookmark names, sadly. But I haven't heard of that being an issue in practice.)

[dzaima]

Bookmarks take precedence over change ID prefixes. And indeed if you add a bookmark "xyz" and a change had a unique prefix "xyz", the change's unique prefix will grow by one. (the unique prefixes can already grow or shrink semi-arbitrarily so this doesn't "break" anything more)