Adding domain expertise

1. Adding domain expertise

In the last video, you learned how to guide Copilot using chat variables and progressive prompting.

2. What are chat participants?

But what if you want more focused help from a domain expert? That's where chat participants come in. They're built-in AI experts you can tag using @, directly in the Copilot chat.

3. Using different chat variables

Let's say you need help with a command-line task. You could type: @terminal how do I activate a virtual environment? Copilot will respond like a shell expert, explaining the command and suggesting the best approach based on your setup. You can also ask questions about your editor using the @vscode chat participant. For example: @vscode how do I change my Visual Studio Code colors? Copilot will guide you to the correct settings. Want to check pull requests in the current repository without leaving your editor? Just type: @github show me the closed PRs in the repo Copilot will pull that information directly from your GitHub account. Or maybe you're wondering how a feature is implemented across your application. You can ask: @workspace how is authentication handled in this app? Copilot will scan your workspace to provide you with an answer.

4. Chat participants provide domain expertise

As you can see, chat participants

5. Chat participants provide domain expertise

help Copilot respond more accurately to domain-specific questions and complement the context you provide.

6. Participants vs. chat variables

So, when should you use participants vs. chat variables?

7. Participants vs. chat variables

Use chat variables when you want to guide Copilot's focus—like pointing to a file, change, or code block.

8. Participants vs. chat variables

Use chat participants when you want to bring in expertise—like someone who knows how to handle terminal output or review pull requests.

9. Using variables and participants together

But you don't have to choose between variables and participants—you can use both in the same prompt! For example, you can use: @workspace how do these changes affect routing? #changes, to ask a project-aware expert to review your recent edits.

10. Using variables and participants together

Or, @terminal explain the error from the command #terminalLastCommand, to get help diagnosing a failed shell command with the exact context.

11. Combining domain knowledge and context

Combining chat participants and chat variables gives Copilot the right expert and the right context,

12. Combining domain knowledge and context

leading to smarter, more relevant responses.

13. Let's practice!

Now, let's put your knowledge to the test!

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