Bug: /usage shows 'only available for subscription plans' on Max account

Description

The /usage slash command displays a message saying it is "only available for subscription plans" even though the account is on a Max subscription.

Steps to Reproduce

1. Log in to Claude Code with a Max subscription account
2. Confirm auth: claude auth status returns "subscriptionType": "max"
3. Run /usage in a Claude Code session
4. Dialog shows "only available for subscription plans" then dismisses

Expected Behavior

/usage should display usage statistics for the Max account.

Actual Behavior

Dialog briefly appears with "only available for subscription plans" message and dismisses.

Environment

• Claude Code version: CLI (latest)
• Auth method: claude.ai (first party)
• Subscription type: max
• Platform: macOS (Darwin 25.2.0)
• Model: Claude Opus 4.6 (1M context)

Auth Status Output

{
  "loggedIn": true,
  "authMethod": "claude.ai",
  "apiProvider": "firstParty",
  "email": "redacted",
  "orgId": "redacted",
  "subscriptionType": "max"
}