jj

name	jj
description	Correct patterns for using jj (jujutsu) version control. Load this when you need to create revisions, move between changes, or perform any jj operation. Complements the commit skill (which handles commit-time concerns like message generation and rule reflection).

jj Patterns

Core Model

No staging area. Every change in the working copy is already part of the current revision (@).

jj new finalizes the current working copy and opens a fresh empty one on top.

Anti-Pattern: Empty Commits

Never run jj new followed immediately by jj commit. That produces an empty commit — jj new tucks changes into the revision below, then opens a new empty @.

Situation	Command
Changes exist, commit them	jj commit -m "..."
No changes yet, start new work	jj new -m "..."
Just committed, start next step	jj new (no -m)

Before Running Commands

jj log -r '@ | @-' --limit 2
jj diff --stat

• Changes visible → in @. jj commit finalizes them.
• @ empty → jj commit does nothing. Use jj new or start working.

Common Operations

jj log --limit 5                    # view current revision
jj undo                             # undo last operation

# Squash
jj squash                           # @ into @-
jj squash -r <rev>                  # specific rev into parent
jj squash --from <rev>              # move rev's changes into @
jj squash --from <rev> --use-destination-message  # skip editor
jj squash --from <rev> -m "msg"     # new description inline

# Squash a range into one
jj edit <base-revision>
jj squash --from <rev-1>
jj squash --from <rev-2>
jj describe -m "feat(scope): combined"
jj abandon <empty-descendants>

# Edit previous revision
jj edit <revision-id>               # changes go there
jj edit @-                          # back to tip

Relationship to Other Skills

• commit — reflection, rules, message generation. Use when user says "commit".
• jj (this skill) — mechanics of jj operations.
• tdd-plan — calls jj new at step start, jj commit at step end.