[BUG] Claude Desktop 3P - Foundry config with Interactive Sign-in uses wrong url

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?

When setting up the third-party inference inside Claude Desktop and using Foundry with Interactive sign-in you can fill in the fields:

• Credential Kind
• Azure AI Foundry Resource Name
• Entra ID Tenant ID
• Entra ID Client ID

After testing and succesfully logging in through the browser you get a 404 error.
But the issue of the 404 error is that it constructs the url wrong.

The error is:
Inference — Azure AI Foundry rejected model "claude-sonnet-4-5" (HTTP 404)
404 https://<resource-name>.services.ai.azure.com/models/chat/completions

So the url is lacking /anthropic

What Should Happen?

The url should construct as: https://<resource-name>.services.ai.azure.com/anthropic/models/chat/completions

Error Messages/Logs

Inference — Azure AI Foundry rejected model "claude-sonnet-4-5" (HTTP 404)

404 https://<resourcename>.services.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

see above

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.159

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_