[BUG] Opus 5 usage is counted against the weekly Fable limit (Max 5x, advisor off)

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'm on the Max (5x) plan and use Claude Code with Opus 5 as the main model (effort: max). The advisor is turned off. Even so, my weekly Fable limit keeps getting used up. In my understanding the Fable limit should not be touched.

What Should Happen?

Usage from Opus 5 sessions should only count toward the all-models limit. The weekly Fable meter should only go up when a Fable model actually runs (as the main model, advisor or subagent). If Claude Code calls Fable in the background for any reason, that should be visible in /usage.

Error Messages/Logs

Steps to Reproduce

1. Use Claude Code on a Max (5x) subscription.
2. Set the main model to Opus 5 with /model and turn the advisor off (/advisor off).
3. Work normally with Opus 5 (in my case one long session with about 835k of 1M tokens of context, effort: max).
4. Open the plan usage panel or run /usage.
5. The "Weekly · Fable" meter has gone up even though no Fable model was used.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.251 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

PowerShell

Additional Information

_No response_