EnterPlanMode triggers 'Auto mode is unavailable for your plan' on Max plan

Description

When using /plan or the EnterPlanMode tool inside an interactive session, the error "Auto mode is unavailable for your plan" is displayed. This happens despite being on the Max plan.

Environment

• Claude Code version: 2.1.92
• Plan: Max (subscriptionType: "max")
• Platform: macOS (Darwin 25.4.0)
• Auth method: claude.ai (OAuth)

Steps to Reproduce

1. Start a Claude Code interactive session: claude
2. Ask Claude to enter plan mode, or type /plan
3. Error appears: "Auto mode is unavailable for your plan"

Expected Behavior

Plan mode should work on the Max plan.

Notes

• --permission-mode auto works correctly in --print mode
• The error suggests plan mode internally checks auto mode eligibility, and that check incorrectly rejects the Max plan
• claude auth status confirms subscriptionType: "max"