I believe you are using https://github.com/github/copilot-cli or potentially this https://github.com/github/copilot-language-server-release#ag... via the Agent Client Protocol https://github.com/agentclientprotocol/agent-client-protocol which means you are indeed using Copilot's harness

ACP is just a standard that bridges harnesses easily into IDEs, Text Editors, or whatever consumes it (I wrote a TUI that consumes them)

The registry for all the agents (tool harnesses) is here https://github.com/agentclientprotocol/registry if you ever are curious to what Zed or IntelliJ are really hooking into

Ah OK, so the ACP connector ensures tool calls work with Zed, and communicates the available tools and their results to the harness, and then the harness mainly provides a system prompt and the API calls?