Subscription usage stops when 'additional usage' is disabled, despite remaining quota (OAuth)

Description

When using Claude Code connected via OAuth, the session stops responding if "additional usage" (추가 사용량) is disabled — even though subscription quota is still remaining.

Running /cost inside Claude Code returns:

You are currently using your subscription to power your Claude Code usage

This contradicts the behavior, since disabling additional usage immediately halts the session.

Environment

• Auth method: OAuth
• Model: Claude Opus 4.6 (1M context)
• Platform: macOS (darwin-arm64)
• Claude Code version: latest stable

Steps to Reproduce

1. Connect Claude Code via OAuth with an active subscription (quota remaining)
2. Start a session using Opus 4.6 (1M context)
3. Disable "additional usage" in account settings
4. Session stops mid-response
5. Re-enable "additional usage" → session resumes
6. /cost still shows "subscription" is being used

Expected Behavior

If subscription quota is remaining, the session should continue without requiring "additional usage" to be enabled.

Actual Behavior

Session halts immediately when additional usage is disabled, suggesting that Opus 1M context sessions may be silently classified as additional/overuse even when subscription quota appears available.

Contact

Please reply to: songkangki@gmail.com