Post 4 covered upgrade.md as it exists today. This companion post proposes four concrete, testable extensions — an explicit rollback path when a report can't be fully applied, an incremental strategy for multi-major-version jumps, running the existing test suite as part of verification, and machine-readable JSON output for agent-driven diffing — each framed as a future contribution to SharePoint/spfx-dev-skills, not a criticism of it.