/usage command returns persistent rate_limit_error on OAuth subscription plan

Description

The /usage command consistently fails with a rate limit error when authenticated via OAuth on a subscription plan (Claude Pro/Max). This was previously working.

Error

Error: Failed to load usage data: {"error":{"type":"rate_limit_error","message":"Rate limited. Please try again later."}}

Steps to Reproduce

1. Authenticate via OAuth into a subscription plan
2. Run /usage in Claude Code
3. Error appears immediately, every time
4. Waiting and retrying does not resolve it

Expected Behavior

• /usage should display usage data as it did previously, OR
• If the endpoint is unavailable for subscription/OAuth users, show an appropriate message (e.g., "Usage data not available for subscription plans — check claude.ai/settings")

Environment

• Claude Code version: 2.1.104
• Auth method: OAuth (subscription plan)
• OS: macOS (Darwin 22.6.0)