Divide the current branch into a stack of smaller branches. User input: $ARGUMENTS.

Modes

• gt split --by-commit (-c) — split along existing commit boundaries. Each commit becomes its own branch. Only useful on a multi-commit branch.
• gt split --by-file "<pathspec>" (-f) — peel off files matching the pathspec onto a new branch. Repeat -f for multiple patterns: gt split -f "*.json" -f "*.yaml".
• gt split --by-hunk (-h) — interactive git add --patch-style hunk selection.

Steps

1. Run gt ls and git log --oneline <trunk>.. so the user sees what's on the branch today.
2. Decide the mode:
   • Multiple commits already, clean per-commit grouping → --by-commit.
   • Mixed files, easy to separate by path → --by-file.
   • Same files but distinct concerns → --by-hunk.
3. Run gt split <mode>.
4. Preserve the original branch name on one of the pieces if it already has a PR — GitHub PR branch names are immutable. Tell the user when this matters; Graphite usually prompts.
5. After the split, run gt ls and consider gt submit --stack to open PRs for the new branches.

Notes

• After splitting, the auto-restack runs for everything above the split point. Resolve conflicts the usual way.
• If the user wants the opposite (combine branches), use /graphite:fold (into parent) or /graphite:squash (commits within one branch).