[BUG] Claude Compaction Completely Broken for Opus

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?

Compaction no longer functions for Opus. Every conversation, on every first compaction, the compaction fails.

What Should Happen?

Compaction should work and compact.

Error Messages/Logs

Generic compaction failed message.

Steps to Reproduce

Start a conversation with Opus, without hooks or anything, and then talk until compaction.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Latest

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_