[BUG] `opusplan` mode does uses Opus 4.1 instead of Opus 4.5

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?

When using opusplan mode (set via ~/.claude/settings.json) the Plan phase makes use of Opus 4.1, not the latest Opus 4.5.

What Should Happen?

opusplan should automatically make use of the latest available models in each phase (sonnet 4.5 for execution and opus 4.5 for planning as of posting).

Error Messages/Logs

Steps to Reproduce

1. Set opusplan (in settings.json)
2. Open Claude
3. (Optional) Set a status line to see which model is being used
4. Engage plan mode

Model will be set to Opus 4.1

Claude Model

Other

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.55

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

<img width="1078" height="300" alt="Image" src="https://github.com/user-attachments/assets/ce76c153-f212-48d3-ac1d-5352d780ec85" />