September 9, 2026 · 7 min read

How to Give Cursor the Right Context From Your Codebase

Cursor already indexes whatever project you have open, so it's easy to assume the context question is solved by default — it knows about your files, so what else is there to think about? Quite a bit, it turns out. Indexing means Cursor can find things in your open workspace when it needs to. It doesn't mean it's always looking at the right slice of that workspace for a given question, and it says nothing at all about code that isn't in your open workspace to begin with.

What automatic indexing actually gets you

Cursor builds a searchable index of your open project so it can pull in relevant snippets as you type or chat, without you having to attach every file by hand. Combined with @codebase and file or folder mentions, this covers a lot of ordinary work well — asking about a function, requesting a change to a component you're looking at, that kind of thing doesn't need any extra setup.

A .cursor/rules file (or the older .cursorrules) adds standing instructions on top of that — conventions, preferred patterns, things you don't want to repeat every session. Useful, but it's general guidance about the project, not context about a specific task.

Where indexing alone isn't enough

Code that isn't in your open workspace. Referencing a shared library from a separate repo, or checking how another project in your organization solved something similar, isn't something the index can help with — it only knows about what's open.
Very large monorepos. Indexing scales reasonably well, but a monorepo with several unrelated services in it means a lot of what gets surfaced for any given question is from a part of the codebase that has nothing to do with what you're working on.
Deliberately broad context. Onboarding Cursor to an unfamiliar part of a large project, or asking an architecture-level question, sometimes calls for handing over a specific, curated set of files rather than trusting the index to surface the right ones on its own.

None of this is a knock on how Cursor indexes — it's just a different problem than "get me the contents of this other repo I need to reference," which the index was never built to solve.

When you need context from somewhere else entirely

This is the case that trips people up most: you're working in Cursor on Project A, and you want it to understand how Project B does something — a shared auth pattern, an API client, a convention you want to match. Project B isn't open, and adding the whole thing as a second workspace just to reference a few files is overkill.

The practical fix is pulling exactly the files you need from Project B into a single block of text — labeled with paths, noise filtered out — and pasting that into your Cursor chat alongside the actual question. That gives Cursor the specific reference material without you restructuring your workspace around it.

Preparing that context without leaving the browser

If the repo you need to reference is on GitHub or GitLab, the repoprep Chrome extension does this from the repo page itself — open the repository you want to reference, run the extension, pick the files that actually matter, and copy out a structured context block ready to paste into Cursor. No cloning it locally just to grab three files, no separate tab juggling a URL-paste tool.

The same filtering applies as everywhere else in repoprep — dependency folders and build output are stripped automatically, so what you copy out is source, not noise. For a local folder instead of a hosted repo, the web app's local workflow does the same job.

The bottom line

Cursor's indexing is genuinely good at what it's for — keeping your open project searchable without manual context management. It just isn't the same tool as "bring in reference material from somewhere else," and treating it like it can do both is where people end up assuming Cursor knows about code it's never actually seen.