Brownfield to Greenfield Diff Engine

Structured analysis that answers: "If I were starting from scratch today, knowing what I know now, what would I do differently?" This is NOT a mandate to rewrite. It is a decision-support tool that extracts what the system does, separates that from how it does it, proposes a modern alternative, and lets the user compare both side-by-side before deciding.

The user always decides. This skill recommends, never mandates.

When to Use

• Inherited a codebase and need to understand what's intentional vs accidental
• Considering a major migration or modernisation effort and need to scope the work
• Tech debt has accumulated and you need a structured way to prioritise what to address
• Evaluating whether to refactor incrementally or start fresh
• Preparing a business case for architectural investment (need cost/risk data)

When NOT to Use