Legacy Modernization

Modernize legacy systems without rewriting from scratch. Use strangler fig, facade, and strategic refactoring.

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Legacy Modernization

Modernize legacy systems incrementally using strangler fig pattern, facade layers, and strategic refactoring.

Instructions

  1. Assessment: Understand current system behavior, pain points
  2. Strangler Fig: New services alongside old monolith; gradually redirect traffic
  3. Facade Layer: Wrap legacy with modern API without changing internals
  4. Refactoring: Extract modules one at a time to modern stack
  5. Incremental Value: Each phase delivers business value

Anti-Patterns

  • Rewrite Everything: "Let's rebuild it right." Result: 2-3 years, misses market. Guard: Keep old system running while new builds alongside.
  • No Business Alignment: Modernize things users don't care about. Guard: Modernize parts causing business pain first.

Further Reading

  • Monolith to Microservices — specific modernization patterns

sethdford/claude-skills/tree/main/architect/decision-making/skills/legacy-modernization commit 1188b8abfa

Frequently asked questions

npx skillmds@latest add sethdford/legacy-modernization