[BUG]

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?

On the Max plan, resuming a large Cowork session fails immediately. The session
runs on claude-sonnet-4-6 and the transcript (~2.95 MB) exceeds the 200K standard
window, so the runtime escalates to 1M context. Because the session is on Sonnet,
this requires usage credits even on Max (per the model-config docs, only Sonnet 1M
requires credits on Max; Opus 1M is included). The session should have been routed
to opus[1m], which is covered by the subscription. CLAUDE_CODE_DISABLE_1M_CONTEXT=1
has no effect because the session genuinely cannot fit in 200K.

What Should Happen?

On Max, an oversized session should be served by opus[1m] (included with the
subscription) or otherwise not be gated behind usage credits. Cowork should not
silently route it to sonnet[1m], which requires credits on Max.

Error Messages/Logs

Steps to Reproduce

1. Max plan, Claude desktop app, Cowork
2. Resume a large session (transcript well over 200K tokens)
3. Send any prompt — error appears immediately

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.9659.2 (390d6c) 2026-05-28T21:50:01.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_