I recently switched to Claude Code, I much prefer it (I end up less in cycles of Cursor getting stuck on problems). Before I used Cursor for some months.

> My understanding is that a rule should essentially do the same as if it is put in the prompt directly. Is there a solution to that?

Yes from my understanding Cursor Rule files are essentially an invisible prefix to every prompt. I had some issues in the past with Cursor not picking up rule files until I restarted it (some glitch, probably gone by now.). So put something simple like a "version" or for your rules file and ask it what version of the rules are we following for this conversation just to validate that the process is working.

For Cursor with larger projects I use a set of larger rule files that always apply. Recently I worked with Spotify's Backstage for example and I had it index online documentation on architecture, build instructions, design, development of certain components, project layout. Easily 500+ lines worth of markdown. I tell Cursor where to look, i.e. online documentation of the libraries you use, reference implementations if you have any, good code examples and why they are good, and then it writes its own rule files - I don't write them manually anymore. That has been working really well for me. If you have a common technology stack you or way of working you can also try throwing in some examples from https://github.com/PatrickJS/awesome-cursorrules

For a codebase containing both good and bad code; maybe you can point it to a past change where code was refactored from bad to good, so it can write out what why you prefer which style and how to manage the migration from bad to good. That said; the tools are not perfect. Even with rules the bad output still can happen but larger rule files describing what you'd like to do and what to avoid makes the chance significantly smaller and the tool more pleasant to work with. I recently switched to Claude Code because Cursor tended to get "stuck" on the same problem which I don't really experience with Claude Code but YMMV.