use-jujutsu

name	use-jujutsu
description	Comprehensive skill for Jujutsu (jj) VCS operations. Use this when the user needs to manage version control, translate Git commands to jj, query repository history with revsets, or resolve conflicts in a jj-managed repository.

Jujutsu (jj) VCS Command & Workflow Guide

Jujutsu is a Git-compatible VCS that uses a "working-copy-as-a-commit" model. There is no "index" or "staging area."

1. Core Concepts for the Agent

• The Working Copy (@): Your current changes are always part of a commit. You don't "stage" files; you simply edit them and then "describe" the change or create a "new" one.
• Change IDs vs. Commit IDs: Use Change IDs (shorter, stable) for most commands. Use Commit IDs only when specifically needed for low-level Git interop.
• Operations: Every command creates an "operation" in a log. Use jj op log and jj undo to navigate your own command history.

2. Orientation & Visibility (Critical)

Unlike Git, where you usually know which branch you are on, jj workflows often involve many "anonymous" changes.

• The Map: Always use jj log (or jj log -r "nodes()" for a dense view) to see where you are in the changeset graph.
• Your Location: Look for the @ symbol in the log output. This indicates the current working-copy commit.
• Inspect a Revision: Use jj show <revision> to see the description and diff of a specific change without switching to it.
• State Check: Use jj st frequently. It summarizes the current Change ID, its parent, and any modified files.
• No Pager: When running these as an Agent, always append --no-pager to ensure the full context is captured in the interaction logs.

3. Common Git to Jujutsu Translation

Git Command	Jujutsu Equivalent	Notes
git status	jj st	Shows current change ID and modified files.
git add	(N/A)	Files are tracked automatically once created.
git commit -m "msg"	jj describe -m "msg"	Adds a message to the current open change.
git commit --amend	jj describe -m "new msg"	Just re-describe the current change.
git checkout -b branch	jj bookmark create <name>	"Bookmarks" are the equivalent of branches.
git checkout <branch>	jj edit <bookmark>	Moves the working copy to that bookmark.
git log	jj log	Shows a functional graph of changes.
git show <commit>	jj show <revision>	Inspects description and diff of a revision.
git diff	jj diff	Shows changes in the working copy.
git push	jj git push	Explicitly pushes bookmarks to Git remotes.
git reset --hard	jj abandon	Discards the current change and its edits.

4. Bookmarks (Branches)

Bookmarks are pointers to specific revisions. Unlike Git branches, they do not move automatically unless you are at the "tip" of one.

• Create: jj bookmark create <name> -r <revision>
• Move: jj bookmark set <name> -r <revision>
• Delete: jj bookmark delete <name>
• List: jj bookmark list
• Remote Tracking: jj git push --bookmark <name> or jj git fetch.

5. Working with Stacked Changes

Jujutsu encourages "stacking" small, logical changes. Navigating these requires understanding the difference between moving the working copy and moving the edit focus.

• Move Up (Toward head): jj next --edit

  Note: Use --edit to move the actual working copy to the child. Without it, jj tries to create a new empty commit as a child of the descendant, which fails if the current working copy isn't empty.

• Move Down (Toward root): jj prev --edit

• Edit Specific Revision: jj edit <revision> (equivalent to checking out a specific commit in Git).

• Create New Child: jj new (creates a fresh, empty working copy on top of @).

• Rebase Stack: jj rebase -s <bottom_of_stack> -d <new_parent>.

• View Stack: jj log -r "ancestors(@) & ~ancestors(main)".

6. Advanced History & Revsets

Revsets are the "query language" of jj. Use -r to specify them.

Essential Selectors

• mine(): Changes authored by the current user.
• empty(): Changes with no file modifications.
• conflicts(): Changes containing merge conflicts.
• root(): The virtual empty base of the repo.
• heads(selection): The latest changes in a set.
• bookmarks(): All changes associated with a bookmark.

Powerful Revset Examples

• jj log -r "mine() & ~empty()": Show my non-empty changes.
• jj log -r "description(regex:'fix')": Search messages for "fix".
• jj log -r "ancestors(@, 5)": Show the last 5 ancestors of the current work.
• jj diff -r @--..@: Show the diff of the grandparent to the current change.

7. Operational Commands

• Create New Work: jj new (creates a new change on top of the current one).
• Merge Changes: jj new revision1 revision2 (creates a merge commit).
• Squash/Amend: jj squash (moves changes from @ into its parent @-).
• Splitting: jj split (interactive tool to break one change into two).

8. Conflict Management

• jj allows commits to exist in a "conflicted" state.
• Conflict markers look like <<<<<<<, =======, and >>>>>>>.
• To resolve: Edit the file to remove markers and keep desired code, then jj describe or just continue working.

9. Constraints & Safety

• No Git Commands: Never run git commands inside a .jj repo.
• Pager Handling: Always use --no-pager for Agent-initiated commands.
• Snapshotting: jj snapshots the working copy on every command.

10. Troubleshooting

• Divergence: If a change ID exists in two versions, use jj rebase or jj abandon.
• Push Failure: jj git fetch first, then jj rebase your work onto the remote bookmark.
• "Working copy must not have children": You likely tried jj next without --edit. If you want to move your focus to the next revision in the stack, use jj next --edit.