[Okkef]

I worked with JJ for half a year, and it was great. However, I've since decided to go back to GIT because of compatibility with existing workflows and AI tools.

Pre-commit hooks are not possible [yet?], which is a minor inconvenience. Worse, workspaces/worktrees use a different mechanism. This causes like Claude Desktop (which uses worktrees) to break. Also Claude and other agents are always confused about JJ and fall back to git too often.

[Yeroc]

Seeing similar comments across different articles and technologies and it makes me wonder how much AI is going to hold back the adoption of new technologies going forward.

[j1elo]

I find it a bit ridiculous to see that people or whole teams don't want to use JJ (or any tool, for that matter) because in essence they hired a "support intern" (read: AI assistant) who doesn't know or want to use it.

[surajrmal]

Even breaking changes in a library can cause massive pain. AI constantly wants to the use the old pattern it was trained on. Up until a few months ago it would always prefer using the 2021 edition of rust rather than 2024 for instance. Overall though I don't think this is insurmountable, but it definitely adds an impediment which will overall motivate people to do things non optimally for the foreseeable future. Luckily, not everyone is bound by AI today. I just write my own commits messages instead of letting the AI do it. jj is popular enough that I'm sure it'll learn how to use it in the next year (especially Gemini because Google is using jj internally and would probably train it on it as a result)

[stouset]

Claude Code has zero issue using jj, for what it’s worth.

[ithkuil]

Innovation budget is a finite resource

[hippo22]

I agree it will hold back new technologies, but, at the same time, I'm not sure what the value add of new technologies will be going forward. Often, as is the case with git vs. jj, the value add of a new technology is mostly ergonomic. As AI becomes more ingrained in the development flow, engineers won't engage with the underlying tech directly, and so ergonomic benefits will be diminished. New technologies that emerge will need to provide benefits to AI-agents, not to engineers. Should such a technology emerge, agent developers will likely adopt it.

For this reason, programming languages, at least how we understand them today, have reached a terminal state. I could easily make a new language now, especially with the help of Claude Code et al, but there would never be any reason for any other engineer to use it.

[steveklabnik]

Pre commit hooks are complicated because jj just has a fundamentally different lifecycle than git does.

Tools that integrate with git specifically can be tough though, yeah. Some do Just Work, and some very much do not.

I’ve found a “we use jj not git for this project” in Claude.md makes falling back to git rare, but I also tend to incorporate version control into slash commands or skills directly rather than let Claude decide what to do.

[rtaylorgarlock]

I also prefer to manage version management myself directly, even with llm-gen'd CICD elements, so preferring jj hasn't been nearly as costly for me specifically :D

[zamalek]

Yeah, in an ideal world we'd have "save hooks" but that would probably be much too computationally expensive in some cases.

[olup]

My team is asking the same. We are using jj with great success but tools like auto claude are designed around git and git worktrees. It's a shame - at least with git backend we can sort of make things work together.

[dwattttt]

I wonder if you could replace the git commands exposed to an agent.

A 'commit' 'happens' when you leave a change in jj, i.e. by moving to a new or existing change; that's when you'd run pre-commit hooks.

[steveklabnik]

The problem with this is that at the limit, this means "run the precommit on every save of a file," which is not really usually how people think of precommit hooks.

[KingMob]

I agree about hooks and workspaces, but I'm surprised your Claude is having issues with jj itself. jj is definitely in the training data now, so it might be a matter of guiding it with CLAUDE.md.

[Okkef]

It usually works, but sometimes it'll try to use git instead of jj at random and needs a reminder. As JJ is not completely stable it tries some old commandline versions as well. This improved after I put in some lines in my agents file, but still it's much better at complex changes with git than jj.