[BUG] Opus (default) model selected, but haiku shows up to work

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?

<img width="1898" height="835" alt="Image" src="https://github.com/user-attachments/assets/78d920be-52af-4ead-9eba-607f25214ee5" />

screenshot says it all. Opus (default) is selected at all time, but haiku is the one there doing the work, and admits so.

<img width="1421" height="141" alt="Image" src="https://github.com/user-attachments/assets/95af027f-b7d0-45b5-a259-5654565aeb4c" />

What Should Happen?

opus should be the model doing the work. if asked which model it is, it should say it is opus.

Error Messages/Logs

Steps to Reproduce

in CLAUDE.md add something like this:

AT THE END OF EVERY MESSAGE:

Model: [your-model-identifier]
State: [current EXECUTION_STATE]
Violations: [none | list violations]

it will show up eventually. difference in quality is also evident

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.34

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_