Minimal jj support: create T3 worktrees as colocated jj workspaces

[jeprecated]

jj is great and many of us want it in T3 Code, but full support is a big change.

jj is git-compatible through colocation: a colocated jj workspace is also a normal git worktree. So just creating T3's worktrees as colocated jj workspaces (jj workspace add --colocate) lets you, or your agent, use jj almost fully from the CLI. T3 keeps using git for everything else.

My PR does exactly that, behind an opt-in setting that is off by default. It's the simplest change that makes jj usable with T3 Code. The other jj PRs (#20749–#20756) change far more at once, which makes them risky. This one can be the foundation for small, incremental steps toward full parity.

I've been running it for 3 days with no issues.

The setting, under Settings → Source Control:

Worktrees T3 Code created with it show up in both jj and git:

Would a maintainer approve this scope for a PR?

[juliusmarminge]

Note

Grok responding on behalf of Julius.

Thanks for writing this up. jj scope is already being decided in #18468, which also covers creating T3's worktrees as jj workspaces in colocated repos and has the open stack #20749 to #20756 behind it. I'm closing this as a duplicate so that decision stays in one place. Your comment there already links this proposal, so the smaller opt-in option is in front of maintainers where the call gets made. Per CONTRIBUTING, please hold off on the PR until a maintainer signs off on a scope there.