PR Splitter

Preserve the original PR as source material, build smaller reviewable PRs intentionally, and track drift locally as review feedback changes the stack.

Required workflow

1. Snapshot before touching history

   • Check git status.
   • Create an immutable local reference to the original branch: git branch backup/original-large-pr.
   • Do not delete or rewrite the original branch until the split is complete.

2. Inventory the original PR

   • Inspect git diff --stat <base>...HEAD, git diff --name-only <base>...HEAD, and git log --oneline <base>..HEAD.
   • Classify changes by review unit: prep/refactor, API/type changes, behavior, tests, docs, cleanup, generated/lock files.

3. Create a local scratchpad

   • Write split notes to an uncommitted local file, preferably .notes/pr-split.md.
   • Ensure .notes/ is ignored or leave it untracked. Do not commit scratchpad notes unless the user explicitly asks.
   • Track: original branch, base branch, planned PRs, files/hunks extracted, verification per PR, remaining original diff, and intentional drift from review feedback.

4. Choose the split shape

   • Use stacked PRs when later work depends on earlier work.
   • Use parallel PRs only when changes are truly independent.
   • Use foundation + parallel follow-ups when one shared prep change unlocks independent work.

5. Extract changes safely

   • Prefer fresh branches from the correct base plus selective restore over rewriting messy history.
   • Use path-level extraction for clean file ownership: git checkout backup/original-large-pr -- path/to/file.
   • Use hunk-level extraction for mixed files: git restore -p --source backup/original-large-pr -- path/to/file.
   • Keep each PR independently buildable and reviewable.