Reviewing your own code a few weeks after writing it is a particular kind of experience. The decisions that felt obvious at the time now look questionable. The "temporary" shortcuts are still there. And some things you were sure were correct turn out to have bugs that you can trace directly to an assumption you made at 2am.

A few months ago I started a serious code review of Leverage, a NestJS Online Judge platform that had been running in production for years. No tests. No linter enforcement. No formal review process. Just code that had grown organically, feature by feature, under deadline pressure.

I came out of it with 29 documented issues. Some were minor style things. Six of them were the kind of bugs that make you stare at the screen for a moment and think "how has this been running?"