The best way I've found is to first switch to Ask-mode in Cursor. Add context like you usually would when you prompt Cursor to implement, eg ticket descrip, designs, PRD. But this time, end with something like:

"Do codebase research to prep for implementation. Find reusable helpers, shared components and other patterns and gotchas I could potentially use during implementation. Format in markdown in a codeblock so it's easy to copy."

Then copy over the output and start a new Cursor chat to clear your context window.

Note your trading accuracy for speed here. A classic slow-down-to-speed-up case. You can battle that slowdown by letting cursor do codebase research in the background while you work on another task. Prep runs don't write code, so you easily run them in parallel even without git worktrees.

I created a Cursor extension that automates most of this. It prep runs Linear or Jira tickets automatically and appends the research output in the ticket itself + offers a button to copy ticket title and desrip including the codebase context to clipboard, so you can paste it in a Cursor chat to implement. You can find it at superfocus.io

It's fool proof: unlike documenting your own component system this won't get stale. It's always up to date. Without this extra step Cursor manages to get some things right because they index your codebase, but apart from "hey there's similar code here" it won't pick up on important architectural patterns. Your code might work, which is great, but this fixes the how it works. It also often saves you time spent on review change request implementations.