[BUG] `defaultMode` setting is ignored

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?

The defaultMode setting in settings.json is being ignored.
It should be set to 1M by default, but it keeps changing to Opus 4.7 (which is not 1M), and it is frustrating.

What Should Happen?

The model selection should not change on its own. This did not happen before.

Error Messages/Logs

Steps to Reproduce

It occurs after using it a few times or resuming. I do not know the specific steps. It happens intermittently.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.146 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_