[BUG] When using Foundry, Test connection is trying to connect to /models/chat/completions instead of anthropic/v1/messages

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

<img width="718" height="1077" alt="Image" src="https://github.com/user-attachments/assets/d0058963-15cb-4350-8ed7-a511882800f0" />

Please see attached image. During 3rd Pary Inference setup Claude Desktop is trying to connect to /models/chat/completions instead of anthropic/v1/messages.

The credential helper generates a token that I independently verified works with my Claude deployment in Foundry.

<img width="759" height="301" alt="Image" src="https://github.com/user-attachments/assets/8fc5615e-39bc-48a5-8791-8a69dbf40ab8" />

What Should Happen?

Claude Desktop should connect to /anthropic/v1/messages, not /models/chat/completions

Error Messages/Logs

404 https://<my-foundry-project-name>.ai.azure.com/models/chat/completions
{"error":{"code":"api_not_supported","message":"Requested API is currently not supported","details":"Requested API is currently not supported"}}

Steps to Reproduce

1. Enabled Developer Mode
2. Setup 3rd Party Inference with Azure Foundry option.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude 1.11847.5 (9692f0) 2026-06-09T17:34:27.000Z

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_