Legacy Modernization Skill

Every system becomes legacy. The question isn't whether to modernize — it's how to do it without breaking everything. This skill covers the patterns that let you replace legacy systems incrementally, safely, and in production.

When to Activate

• Planning a rewrite or major architectural migration
• A module is too risky to change without breaking things
• Legacy code lacks tests and has accumulated years of hidden behavior
• Choosing between "big bang rewrite" and incremental migration
• Designing a migration from a monolith to services, or from legacy framework to modern one

The Core Problem with Big Bang Rewrites