Legacy Modernizer

This one walks you through incremental legacy modernization using strangler fig and branch by abstraction patterns. It starts with dependency mapping and risk assessment, then builds characterization tests before you touch production code, and finally implements facades with feature flags to gradually shift traffic. The validation checkpoints at each step (like confirming 80%+ test coverage before refactoring, or proving stability at 100% traffic for a full release cycle) are solid guardrails against the big bang rewrites that usually sink these projects. The Python examples for facades and feature flags are simple but practical. Best when you need to modernize a legacy system without the luxury of downtime or the budget to rewrite everything at once.