I’ve got some very strict dev rules, which have so far, all year, Resulted in incredibly productive and valuable work output from anthropic models.
Now that cursor have blocked their old version 2.3 from working anymore, I was forced to upgrade to 3.0
Now it just keeps doing stupid things, and when I ask why it did that, it apologizes to me and says that it knows it shouldn’t have because it’s in my rules, then undoes its mess ups.
This is infuriating! I have to manually check everything doing and then spend hours reminding it to undo all the things it did wrong. This never used to happen on v2.3 !!
What’s the trick to getting it follow your rules? It knows them - it just ignores them!
Hey, I see you already reported a similar issue here: CRITICAL: "Rules" do not survive context compression events. That thread was about rules getting lost after context compression in long sessions. Is this new thread about something different, or the same situation?
A couple quick questions so I can help more accurately:
Are the rules ignored from the very start of a new chat, or only after a long session when context gets compressed?
How are your rules set up exactly, are they .mdc files in .cursor/rules/ with alwaysApply: true, or a .cursorrules file in the project root, or User Rules in settings?
Can you open a new Agent chat, send a message, then click the top-right chat menu and choose Copy Request ID? This helps check on the server whether the rules are making it into the context.
If the issue is that rules just aren’t being picked up at all, that’s a known bug we’re tracking right now. If the rules get “forgotten” after compression, that’s the same situation as your previous thread.
For now, as a workaround, try splitting work into shorter sessions and reference the rules via @ mention in chat if you notice the model starting to ignore them.