[BUG] Model selection reverts to "Sonnet 4" on every restart despite settings.json

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?

Model selection reverts to "Sonnet 4" on every restart despite settings.json

What Should Happen?

Claude should start with default model

Error Messages/Logs

Steps to Reproduce

• Claude Code version: 2.1.69
• OS: Windows 10 + WSL2 (Ubuntu)
• Steps to reproduce:

a. Start Claude Code — launches with Sonnet 4
b. Use /model to select Sonnet 4.6
c. Exit and restart — reverts to Sonnet 4 again

• settings.json gets "model": "sonnet" written back on exit, which resolves to Sonnet 4 instead of Sonnet 4.6
• Workaround: Using alias claude='claude --model claude-sonnet-4-6' in .bashrc

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.69

Platform

Other

Operating System

Windows

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

_No response_