Describe the bug
When making an Agent request using Claude Opus 4.5 I have been getting the same error message all day:

Sorry, an error occurred while generating a response. Details: unhandled status from server: 400 {"error": {"message": "messages.1.content.0.thinking: each thinking block must contain thinking","code":"invalid_request_body"}} Request ID: xxx

Versions

• Copilot for Xcode: 0.46.0
• Xcode: 26.2.0
• macOS: 26.2

Steps to reproduce

1. Select Claude Opus 4.5 as model
2. Select Agent mode
3. Enter prompt
4. Error is returned

Screenshots
Image

Logs
github-copilot-for-xcode.log

Additional context
Attempted the following to try and resolve:

• Signing out then back in
• Cleaning DerivedData/Copilot cache
• Restarting device
• Uninstalling / Reinstalling Copilot