Desktop App broken on Windows with Bedrock after v2.1.149

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?

Sending bare claude-sonnet-4-6 to Bedrock instead of us.anthropic.claude-sonnet-4-6. Worked before 5/22. VS Code extension unaffected. modelOverrides and model in settings.json have no effect. Windows 10, Bedrock us-east-2.

What Should Happen?

The desktop app should send us.anthropic.claude-sonnet-4-6 to Bedrock (the cross-region inference profile format), not the bare claude-sonnet-4-6. This worked correctly before v2.1.149. The VS Code extension still handles this correctly.

Error Messages/Logs

Steps to Reproduce

Set up Claude Code desktop app on Windows with AWS Bedrock (CLAUDE_CODE_USE_BEDROCK=1, AWS_REGION=us-east-2)
Open the desktop app and start any new session
Send any message
Error immediately: API Error (claude-sonnet-4-6): 400 The provided model identifier is invalid
Note: VS Code extension works fine with identical config. Worked before v2.1.149 (broke 5/22/2026). modelOverrides and model fields in settings.json have no effect.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.148

Claude Code Version

2.1.133 (Claude Code)

Platform

AWS Bedrock

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_