[BUG] Auto compact doesn't work with Opus 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?

Auto compact doesn't trigger I needed to manually compact and model continuously says that it is context window is about to be full. That doesn't help at all. Especially remote sessions. All other models on the latest claude code does work. Opus 5 refuses the do the work neither compacts nor does the backlogged tasks because of this problem.

What Should Happen?

Auto compacts the convo.

Error Messages/Logs

Steps to Reproduce

1. Use enough Opus 5 with latest claude code to get around ~900K CW threshold.
2. It start to complain about reaching the end and refuses picking up tasks.
3. Neither auto compacts nor does the queued work.

Claude Model

_No response_

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.222 (Claude Code)

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_