How to Prepare a Legacy Codebase for AI-Assisted Refactoring

Jumping into a legacy codebase with an AI coding assistant and no preparation produces predictably mixed results. The AI generates plausible-looking refactors that miss critical business logic embedded in unexpected places. You spend more time verifying output than the AI saved you in generation time. And the refactored code, while cleaner-looking, may have subtle behavioral changes that surface in production six weeks later. The difference between this outcome and a productive AI-assisted moder