The first legacy refactor I owned was a 14,000 line PHP file that handled checkout for an ecommerce site I had been hired to maintain. The original author had left two years before. The variable names were a mix of Hungarian notation, abbreviations, and what I can only describe as personal grudges. There were comments that referenced bugs that no longer existed and tickets in a tracker that had been decommissioned. I asked the team where to start. They said "do not." That was the strategy. That advice was correct in 2018. In 2026 it is not. Refactoring legacy code used to be the kind of project that took a senior engineer three months and ended in a failed migration. Now the same work takes weeks, and the failure rate is dramatically lower. Claude Code is the difference. Not because it does the refactor for me, but because it does the research that used to make refactoring legacy code intractable.…