jj (Jujutsu) Version Control

jj is a Git-compatible VCS with a different mental model. Most LLMs are trained primarily on git, so this skill provides the correct jj approach.

Critical differences from git

1. Working copy is always a commit - Every file change automatically amends the current working copy commit. There is no staging area, no git add.

2. Change ID vs Commit ID - Every commit has two identifiers:

   • Change ID (e.g., kntqzsqt): Stable across rewrites, use this in commands
   • Commit ID (e.g., d7439b06): Changes when commit is modified (like git's SHA)

3. No staging area - Files are automatically tracked. Use .gitignore (jj uses git's ignore format) and jj file untrack <path> to untrack.

4. Commits are mutable - You can freely rewrite any commit. Rewriting pushed commits requires force push (jj git push handles this automatically with lease protection). Conflicts don't block operations - they're stored in the commit.

5. Bookmarks, not branches - jj uses "bookmarks" instead of git branches. They map 1:1 to git branches when pushing/fetching.

6. Colocated repos - When .jj and .git coexist, every jj command auto-syncs with git. Git stays in detached HEAD state. Tools like gh CLI work normally.