So what are the obvious things to do when working with legacy code? Two strategies stand out: Testageddon and micromanagement.

Testageddon is when you ask Claude to generate comprehensive tests for a module or component. Before you make any changes to legacy code, having a good test suite gives you confidence that you haven't broken anything. Tell Claude to analyze a module and create unit tests, integration tests, edge case tests - the whole works.

Micromanagement is about breaking tasks down into very small steps. Instead of saying "fix this bug," you might say "first, find all the places where this function is called," then "read those files," then "identify which call site is causing the issue," and finally "fix it." By being very explicit about each step, you maintain control and can verify Claude's understanding before it makes changes.

Both approaches help manage the complexity of working with code you didn't write. Test first, then proceed carefully in small steps.