[BUG] Developer Mode - Third-Party API config page shows "Couldn't load configuration"

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?

Environment:

• OS: Windows 11
• Claude Desktop version: 1.12603.1 (3df4fd), 2026-06-11T16:57:36.000Z

Description:
After enabling Developer Mode via Help → Troubleshooting → Enable Developer Mode, navigating to Developer → Configure Third-Party Inference shows the error "Couldn't load configuration". The configuration page fails to load and is completely unusable.

What Should Happen?

The configuration page should load normally and allow users to enter a third-party API base URL and API key.

Error Messages/Logs

Couldn't load configuration

Steps to Reproduce

1. Open Claude Desktop
2. Click Help → Troubleshooting → Enable Developer Mode
3. Restart Claude
4. Click Developer → Configure Third-Party Inference
5. Page displays "Couldn't load configuration" error

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.12603.1 (3df4fd), 2026-06-11T16:57:36.000Z

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_