Has anyone managed to get Copilot working using the new ACP integration in Xcode 26.6 and Xcode 27 beta?
I have tried setting it up using the path to the copilot binary as instructed and the flags --acp --stdio but Xcode just displays a "Your request couldn't be completed" error: JSON-RPC global stream failed: The operation couldn’t be completed. (IDEIntelligenceProtocol.JSONRPCElement.Error error 1.)
I am running the latest version of copilot cli and it works in many other IDEs.
Also get the same thing on Xcode 26.6 RC and Xcode 27 trying to use GitHub Copilot CLI.
JSON-RPC request with ID JSONRPCID(rawValue: "8848B1CB-E942-47A8-B53E-36E5E40735CB", intValue: nil) failed to produce a response.
We have been testing with Copilot 1.0.47 and been able to validate it by configuring it as follows:
Executable path: /path/to/copilot
Interpreter: <leave blank>
Arguments:
--acp
<no other arguments necessary>
As long as you have authenticated with the agent outside Xcode, it should immediately begin working. Let us know if you are still struggling for any reason.
Thanks!
I had the same issue. copilot-cli is too strict, expecting a version ID that Xcode doesn't send. It was possible to create a workaround in python that acts as a frontend to fill in the protocolVersion details and act as a bridge:
I can confirm that --acp with no extra args worked, obviating the need for the python frontend :)