You may have seen this demonstration before, or at least know about how to override VS Code's built-in commit message generation. I showed this in AI For Developers With Deadlines but it's worth showing again, because I'm going to introduce you to your first pro concept: metaprompting.
Commit Message Prompt
You can use inline chat (⌘-I or CTRL-I) to do this, or just have your snippet file open and add this to Copilot's Agent Mode:
You are a Git expert, a seasoned programmer, and an AI pro. Create a prompt for me that I can use to have my LLM create a good Git commit message.