[BUG] CLAUDE_CODE_DISABLE_1M_CONTEXT ignored in 2.1.156

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 typically work with one million context window disabled, and I noticed that s my agents were not auto compacting afaik nothing has changed with my setup, just the claude code version.

<img width="517" height="359" alt="Image" src="https://github.com/user-attachments/assets/56dae9a2-b8ea-4803-86f5-3b2492a67038" />

What Should Happen?

It should compact at the default % of 200k tokens

Error Messages/Logs

Steps to Reproduce

on mac os export CLAUDE_CODE_DISABLE_1M_CONTEXT=1

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.155 (presumably)

Claude Code Version

2.1.156

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

_No response_