Sonnet 4.6 1M context unavailable on Max x20 plan — v2.1.87 [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?

Environment

• Claude Code version: 2.1.87
• Plan: Claude Max x20 ($200/month)
• OS: Linux

Steps to reproduce

1. Run /model claude-sonnet-4-6[1m]

Expected behavior
Sonnet 4.6 with 1M context should be available on Max x20 plan per the GA announcement
(March 13, 2026).

Actual behavior
> Sonnet 4.6 with 1M context is not available for your account.

Notes

• Opus 4.6 with 1M context works correctly
• Version is already past the v2.1.75 fix — this appears to be account-level, not

version-level

• Related: #34773, #26428

What Should Happen?

que funcione

Error Messages/Logs

/model claude-sonnet-4-6[1m]
  ⎿  Sonnet 4.6 with 1M context is not available for your account. Learn more:
     https://code.claude.com/docs/en/model-config#extended-context-with-1m

Steps to Reproduce

/model sonnet y me sale solo 200k de token y cuando activo el de 1 millon forzado me da error de no disponible en mi cuenta

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.87 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_