0 to a hundred, real quick

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?

Master chat compacted to 0%
Switched to Opus ultracode, ran something big - hit 40% of context window
Switched back to Haiku, asked a simple question
Auto-compaction triggered and exploded to 100%

What Should Happen?

context window shouldn't fill on a simple question and max out on compact

Error Messages/Logs

Steps to Reproduce

Master chat compacted to 0%
Switched to Opus ultracode, ran something big
Switched back to Haiku, asked a simple question
Auto-compaction triggered and exploded to 100%

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.24012.9 (03c61d) 2026-07-24T04:59:17.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

this is not the first time a window has exploed in context just the most absurd one. it was a master chat, i was compacting as i went, spinning off agents to work on projects.