PR Break

Convert one large PR into a stack of small ones. Never lose functionality, break review continuity, or ship a half-finished state on any intermediate branch.

Read PR ──► Read context ──► Identify seams ──► Plan stack
                                                  │
                                          (≤5 children, ordered)
                                                  │
                                                  ▼
                                       Validate invariants
                                                  │
                                                  ▼
                                         Present for approval
                                                  │
                                                  ▼
                                          Execute (per-child wk-pr)