I audited 20 public .cursorrules files. Here's what most of them get wrong.

I went through 20 public .cursorrules files on GitHub to see what developers are actually writing. Most of them are reasonable. A few patterns kept showing up that consistently cause problems. The problems Rules that describe intent instead of behavior The most common issue. Things like: Write clean, maintainable code. Follow best practices. Use modern patterns. These tell Cursor nothing. "Clean" and "best practices" are subjective. Cursor has to guess what you mean, and it guesses based on training data from millions of repos, not your codebase. Rules need to be specific enough that a reasonable developer could check compliance. "All components go in src/components/" is checkable. "Write clean code" is not. Rules that only cover the happy path A lot of .cursorrules files define conventions for new code but say nothing about how to handle existing code. Then Cursor adds a new helper function in a style that contradicts everything already in the file. Add a section explicitly about cons