[BUG] /fast toggle reports "extra usage credits exhausted" on Pro Max with plenty of plan quota remaining

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?

Toggling /fast in Claude Code immediately disables itself with the message:
> Fast mode disabled · extra usage credits exhausted

What Should Happen?

/fast should work within the Pro Max plan allocation.
It appears to check the "extra usage" credit balance ($0.00) instead of the plan quota, even though plan usage is only
12% session / 27% weekly.

Error Messages/Logs

Steps to Reproduce

1. Have a Pro Max subscription with available plan quota (e.g., 12% session, 27% weekly used)
2. Have "Extra usage" balance at $0.00 with auto-reload off
3. Open Claude Code CLI (v2.1.87, Windows 11)
4. Type /fast to enable fast mode
5. Observe message: "Fast mode disabled · extra usage credits exhausted"

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

v2.1.87

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_