--worktree flag silently fails on jj (Jujutsu) colocated repos (detached HEAD)

[tom-pang]

Description

claude -w (or claude --worktree) silently fails to create a worktree when the repository has a detached HEAD, which is the default state for all jj (Jujutsu) colocated repositories.

Steps to reproduce

1. Have a jj colocated repo (.jj/ alongside .git/)
2. Run claude -w my-test
3. Claude starts but is not in a worktree - it's in the main repo

Expected behavior

Claude should create a git worktree and start the session inside it.

Root cause

jj colocated repos always present as detached HEAD to git. git worktree add requires the -b <branch> flag when HEAD is detached (to create a new branch for the worktree). Without -b, git worktree add fails.

Manual workaround that works:

git worktree add /tmp/test-worktree -b test-branch
# succeeds on detached HEAD

So the fix is likely to pass -b <generated-branch-name> to git worktree add when HEAD is detached.

Environment

• Claude Code v2.1.50
• macOS (Darwin 24.6.0)
• jj 0.x colocated with git
• --worktree flag introduced in 2.1.49

Notes

jj is growing in popularity and all colocated jj repos have this issue. The failure is silent - no error message, Claude just starts in the main repo instead of a worktree.

[PrayagS]

It could be happening for non-colocated repos as well.

I had the same hunch as you but it doesn't work for me on a git-only repo. Many users are reporting the same: #27044

[wfarr]

It could be happening for non-colocated repos as well.

Non-colocated repos just throw an outright error, unfortunately (even on 2.1.50):

Error: Can only use --worktree in a git repository, but <redacted> is not a git repository

It would be great to not have to use a colocated repo to use this functionality with jj.

[PrayagS]

It could be happening for non-colocated repos as well.

Non-colocated repos just throw an outright error, unfortunately (even on 2.1.50):

Error: Can only use --worktree in a git repository, but <redacted> is not a git repository

It would be great to not have to use a colocated repo to use this functionality with jj.

My bad. By non-colocated I meant git-only. Don't think this error should come if there's a .git directory. At least I didn't face this.

[wfarr]

Ah — this terminology is overloaded as you can have a jj repository with no .git directory at the top-level at all. There's still one under the hood, but it's hidden away. That's the circumstances in which you get this error.

[phanimahesh]

This still fails on 2.1.63 but creating a worktree in tasks and asking claude to create a worktree both work.

1. Plain git repo:
   Works as expected

2. In colocated repos:
   claude -w just hangs indefinitely.

Steps to reproduce:

# In an empty directory, run
jj git init --colocate
claude -w

3. In non-colocated repos:
   fails with the error Can only use --worktree in a git repository, but <repo> is not a git repository.

Steps to reproduce:

#In an empty directory, run
jj git init --no-colocate
claude -w