[BUG] Xcode 26.6 and newer do not work with Xcode built in Claude code agent.

[Charlie-Louis]

Describe the bug

When using Xcode 26.6 or newer the EXO server is not compatible anymore, queries from Xcode return:

API Error: 422 {"detail":[{"type":"literal_error","loc":["body","messages",1,"role"],"msg":"Input should be 'user' or 'assistant'","input":"system","ctx":{"expected":"'user' or 'assistant'"}}]}

To Reproduce

Xcode 26.5 works fine, so config is OK
Same machine or other machine with,
Xcode 26.6 with same server fail.

Other servers like oMLX work fine with Xcode 26.6

• macOS Version: 26.5
• EXO Version: 1.0.71