Jujutsu (jj)

Git-compatible version control system (jj-vcs/jj, CLI jj, Apache-2.0). It uses Git repositories as its

Jujutsu (jj)

Git-compatible version control system (jj-vcs/jj, CLI jj, Apache-2.0). It uses Git repositories as its storage layer but has its own model: the working copy is a commit, every operation is logged and undoable, conflicts are stored in commits, and descendants rebase automatically. Source summary: Jujutsu (jj).

Facts

Kind	Rust CLI VCS; Git backend via gitoxide. Only the Git backend is production-ready.
Version used here	0.46.0 (jj --version, Homebrew, 2026-10-20). Captured README news stops at 0.24 (Dec 2024).
Repo / docs	github.com/jj-vcs/jj; docs at docs.jj-vcs.dev/latest (and /prerelease for main)
Maturity	Experimental, pre-1.0; on-disk format may change. No Git submodule support.
Help	jj help <cmd>, jj help -k <keyword>

Git-to-jj mental model

Git	jj
index / staging area, git stash	working-copy commit (auto-amended)
branch	bookmark (stored outside Git); changes can stay anonymous
git reflog	operation log (jj undo, revert an older operation)
git rebase --update-refs + git rerere	automatic descendant rebase with propagated conflict resolutions
interrupted rebase / merge state	conflicts recorded in commits, resolved later
git blame	jj file annotate (since 0.24)

Local setup

• Installed at /opt/homebrew/bin/jj, 0.46.0 (2026-10-20).
• ~/dotfiles is a colocated repo: .jj/ sits next to .git/ (colocated since 2026-07-02), so plain Git keeps working in that checkout.
• Config stowed from the dotfiles jj package: ~/dotfiles/jj/.config/jj/config.toml sets the user identity and ui.diff-editor = ["nvim", "-c", "DiffEditor $left $right $output"] with diff-instructions = false, so jj split / jj diffedit open Neovim instead of jj’s built-in editor. hunk.nvim provides the DiffEditor command. See Dotfiles Layout for the Agent Harnesses.
• Decision (2026-10-20): jj is human-only, used in the main ~/dotfiles checkout for history editing. Agents use Git only (Worktree Isolation), and Claude’s settings deny Bash(jj ...). Reason: agent-review, ac-run, floor-guard, session-band and the rtk/safety hooks are all git-specific.

Gotchas

1. In a colocated repo jj detaches Git HEAD at @-, so ac-run’s branch check and starship’s branch segment break until you run git switch.
2. By default auto-track snapshots every untracked file (the same as git add -A). The config sets snapshot.auto-track = "none()".
3. Every jj command writes, even jj st, which snapshots and imports Git refs. jj is unsafe in read-only or plan-mode agents.
4. Rewriting a branch that another Git worktree has checked out leaves that worktree stale.
5. jj workspaces are not Git worktrees, so the harness cannot see them.

Workflows

• Rewrite Pi commits instead of reverting them.
• jj rebase -b X -d main@origin instead of merging main into the branch.
• Quick tweak: jj new main plus a bookmark.
• Safety net: jj op log / jj op restore.

Linked pages

• Dotfiles Layout for the Agent Harnesses
• Worktree Isolation