[BUG] Sonnet 4.6 stuck on usage limit (Opus works fine)

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?

When using the Code feature in the Claude Desktop App, switching to Sonnet 4.6 immediately prompts a "usage limit reached" error, which persists even after waiting for more than 12 hours. However, switching to Opus or other models works completely fine. This seems to be a 1M context compaction bug rather than an actual account usage limit issue.

Steps to reproduce

1. Open Claude Desktop App.
2. Use the Code feature.
3. Select Sonnet 4.6 model.
4. Observe the persistent usage limit error.
5. Switch to Opus and see it work normally.

<img width="1395" height="686" alt="Image" src="https://github.com/user-attachments/assets/8806da6c-c9af-43b6-8829-af215e1f2246" />

What Should Happen?

Sonnet 4.6 should process requests normally without showing usage limit errors, just like Opus does.

Error Messages/Logs

API Error: Usage credits required for 1M context · turn on usage credits at claude.ai/settings/usage, or use --model to switch to standard context

Steps to Reproduce

1. Open Claude Desktop App.
2. Use the Code feature.
3. Select Sonnet 4.6 model.
4. Observe the persistent usage limit error.
5. Switch to Opus and see it work normally.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

latest

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_