Hunk edit buffer

The hunk edit buffer lives at .jj/badjuju/hunk-edit.jujutsu. It's opened from inside a squash window when you want to tweak the contents of a single hunk before squashing it into the destination commit.

When you'd use it

You're in a commit-to-commit squash (see Manipulating Commits). You've picked a hunk to move from the source commit into the destination, but a couple of lines in that hunk don't actually belong in the destination. Rather than splitting the hunk by hand or moving the whole thing and re-editing afterward, you edit it once, at selection time.

How it works

1. From the squash window, place the cursor on a hunk header.

2. Press e (Emacs) or invoke the Edit hunk code action.

3. Bad Juju opens hunk-edit.jujutsu populated with the hunk's contents:

   JJ: Editing hunk in <file>
   JJ: Lines beginning with '-' are deletions and cannot be edited.
   JJ: Edit '+' (added) and ' ' (context) lines; save to apply.
   <file path>
   @@ -<old_start>,<old_len> +<new_start>,<new_len> @@
    context line
   -deleted line
   +added line
    context line
   

4. Edit the + (additions) and (context) lines. - (deletion) lines are read-only — editing them has no effect.

5. Save. Bad Juju:

   • Recomputes the @@ header (the line lengths after your edits).
   • Runs jj squash --interactive --tool badjuju to apply the edited hunk to the source commit.
   • Refreshes the squash window so you can continue picking hunks.

Status messages

The buffer's first action after save is to print a terminal status line:

Constraints

• Only one hunk-edit buffer at a time. The path is .jj/badjuju/hunk-edit.jujutsu — a single shared location. If you open a hunk-edit for a second hunk, it replaces the first.
• The buffer is only meaningful when the parent squash window is still alive. Closing the squash window invalidates the edit.
• JJ:-prefixed lines and the @@ header are advisory metadata. Don't edit them — Bad Juju regenerates them on save based on your edits to the body.

Key bindings

The buffer behaves like a normal editor file — save semantics drive the apply step, not a dedicated keybinding.