[BUG] Context auto-compacted with 6% context remaining

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?

I was making exchanges with claude.code in a terminal window in Rider 2025.2.3 and after a simple request, with context remaining at 6%, claude.code auto compacted. This was when using Opus 4.6 (200k context length)

<img width="1852" height="456" alt="Image" src="https://github.com/user-attachments/assets/b9fda514-d474-46eb-bfe3-ae46f5a31c9d" />

What Should Happen?

claude.code should have waited until context % was at 0% before auto-compaction

Error Messages/Logs

Steps to Reproduce

I was running the claude.code terminal in Rider, and it just auto-compacted a conversation unexpectedly

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

4.6

Claude Code Version

2.1.50 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_