felixge/jj-split

jj split via tmux

Split a commit into N commits by running jj split -m "<message>" repeatedly (N-1 times), using tmux to drive the builtin TUI diff editor for file selection.

Steps

1. Find the existing bash pane in the current tmux session: tmux list-panes -t <session> -F "#{pane_index} #{pane_current_command}"
2. For each split, send: tmux send-keys -t <session>:<window>.<pane> 'jj split -m "<message>"' Enter
3. Wait for the TUI to appear, then capture: tmux capture-pane -t <target> -p
4. Navigate with j/k, select files with Space, confirm with c
5. After the last split, describe the remaining commit: jj describe -m "<message>"

TUI keybindings

• j/k — navigate down/up between files
• Space — toggle selection on focused item
• c — confirm and finish split
• h/l — collapse/expand file to see hunks

Key details

• -m sets the description for the selected (first) commit, so vim never opens.
• The remaining commit keeps the original description (usually empty).
• All files start unselected — select only what goes into the first commit.
• Always sleep between send-keys and capture-pane to let the TUI render.
• Format all commit messages (-m and jj describe) using the conventional-commits skill.

Related Skills

• jj — Full jj command reference (split, describe, squash, etc.)
• conventional-commits — Commit message format for -m flags and jj describe