In Part 1, I wrote about the thrill of spinning up a greenfield project using Cursor’s Agent Mode (then called AI Composer). With Claude 3.5 Sonnet acting like a sharp junior developer, I was able to scaffold a project from scratch and refine the UI with speed and accuracy.

Since then, I’ve been deep in a much larger, older codebase at Quiltster - a project that’s been around for years - and trying to integrate Cursor into that workflow has been a different kind of challenge.

The good news? Cursor is still an enormous time booster, even in legacy code. It especially shines in areas where there’s a lot of repetitive structure or complexity to track - for example, building Bootstrap-based UIs. It handles class names, nested elements, and verbose markup like a pro. It doesn’t get tired, it doesn’t forget, and it never complains about indentation. 😉

What’s changed, though, is that using Cursor in legacy code takes a little more discipline. In Agent Mode, it can be overzealous - touching files it shouldn’t, or making assumptions that don’t apply to your project. That’s where rules come in.

Using Cursor Effectively in Legacy Projects

Here are some of the techniques I’ve found helpful when adapting Cursor to an older, complex codebase:

Project & User Rules

Cursor’s...