> For the complete documentation index, see [llms.txt](https://docs.codemate.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.codemate.ai/c0/quickstart.md).

# Quickstart

### 1. Install C0

Open the Extensions view (`Cmd+Shift+X` on Mac, `Ctrl+Shift+X` on Windows/Linux) and search for   **C0**.

***

### 2. Sign in

On first launch, C0 will prompt you to sign in. Click **Sign in with C0** and complete authentication in your browser. Once signed in, you'll be returned to your IDE automatically.

***

### 3. Open a project and let C0 index it

Open any project folder in your IDE. C0 will detect it and begin indexing your codebase automatically.

You'll see a status indicator in the C0 panel:

* **Indexing:** C0 is reading your files and building its knowledge base
* **Ready:** indexing is complete; C0 now understands your codebase

For small projects, indexing takes under a minute. For larger codebases, it may take a few minutes on the first run. After that, C0 only re-indexes files that have changed, so subsequent updates are nearly instant.

> **Note:** You can start using C0 before indexing finishes. Results will improve as indexing progresses.

***

### 4. Try your first workflow

Once indexing completes, try one of these to see C0 in action:

**Ask a question about your code:**

Open the C0 chat panel and type:

```
@<Select your Knowledgebase> How does authentication work in this project?
```

C0 will read the relevant files, trace the flow, and give you a clear explanation grounded in your actual codebase not a generic answer.

**Debug an error:**

Switch to **Debug mode** in the C0 panel, paste an error message or stack trace, and hit enter:

```
TypeError: Cannot read properties of undefined (reading 'userId')
  at AuthMiddleware.verify (src/middleware/auth.js:34)
```

C0 will locate the source of the problem, explain why it's happening, and offer a fix.

**Generate tests for a file:**

Switch to **Generate tests** mode, select a file or function, and run it. C0 will produce a full test suite matched to your project's existing test framework and conventions.