[BUG] Opus 4.6 with 1M context is not available on Max 5x plan

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: 2.1.76 (latest)
• OS: Windows 11 Home
• Plan: Claude Max 5x

Description

When running /model Opus[1M] in Claude Code, the following error is returned:

Opus 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

Expected Behavior

The 1M extended context for Opus 4.6 should be available on the Max 5x plan, as documented.

Steps to Reproduce

1. Subscribe to Claude Max 5x plan
2. Update Claude Code to the latest version (2.1.76)
3. Run /model Opus[1M]
4. Observe the error message

Additional Context

The default Opus 4.6 model works fine. Only the 1M context variant is unavailable.

What Should Happen?

/model Opus[1M] should successfully switch to Opus 4.6 with 1M extended context on the Max 5x plan.

Error Messages/Logs

Opus 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

1. Subscribe to Claude Max 5x plan
2. Install/update Claude Code to version 2.1.76 (latest)
3. Run /model Opus[1M] in Claude Code
4. Error message appears: "Opus 4.6 with 1M context is not available for your account."

Note: The default /model command works fine and Opus 4.6 (without 1M) is available.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.76

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Cursor

Additional Information

_No response_