[BUG] Why I can not use Sonnet even I have enough quota?!

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 ONLY used 30% of the quota of Sonnet, but I can use it!

<img width="1519" height="553" alt="Image" src="https://github.com/user-attachments/assets/21b4e032-718b-4406-b3d6-b184e617e494" />

What Should Happen?

Even I reached the Opus 4.8 limitation, but I CAN use Sonnet 4.6, RIGHT? I ONLY used 30% of its quota!

<img width="1539" height="539" alt="Image" src="https://github.com/user-attachments/assets/4551b684-2290-4cc0-825a-67d9b944aa7b" />

<img width="280" height="196" alt="Image" src="https://github.com/user-attachments/assets/a5b4558b-78f5-44a2-8824-55ea985427fe" />

Error Messages/Logs

❯ /compact
  ⎿  Error: Error during compaction: API Error: Usage credits required for 1M context · run /usage-credits to turn them on, or /model to switch to standard context

❯ /ecc:strategic-compact
API Error: Usage credits required for 1M context · run /usage-credits to turn them on, or /model to switch to standard context

✻ Crunched for 1s · 1 shell still running
                                                          100% context used
────────────────────────────────────────────────────────────────────────────
❯
────────────────────────────────────────────────────────────────────────────
  [Sonnet 4.6] [100%]

Steps to Reproduce

1. Use opus 4.8, when getting limitations, then:
2. Use /model switch to Sonnet or start a new session Claude Code( exit and restart Claude code), then /model switch to Sonnet 4.6.
3. When talking to Claude Code, I encountered You've hit your weekly limit!:

❯ /model
⎿ Set model to Sonnet 4.6 and saved as your default for new sessions

You've hit your weekly limit · 
/upgrade to increase your usage limit.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.159

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_