Opus 4.6 1M context window stuck at 200K despite active Max subscription (tengu_hawthorn_window: 200000)

Bug Description

After logout/login cycle, tengu_hawthorn_window GrowthBook feature flag consistently returns 200000 instead of 1000000 for an active Max subscription. The 1M context window is not available despite multiple re-authentication attempts.

Account Details

• Email: tom@summitxdigital.com
• Org UUID: cdf5a381-b7d7-4b02-95f7-3f7b59fdba0e
• Billing type: stripe_subscription
• hasExtraUsageEnabled: true (enabled during troubleshooting)
• hasAvailableSubscription: false / None (never resolves to true)
• subscriptionCreatedAt: 2026-04-01T22:53:04.428895Z
• Claude Code version: 2.1.91
• Platform: macOS (Darwin 24.6.0)
• Model: claude-opus-4-6

Reproduction Steps

1. claude logout
2. rm ~/.claude.json (full credential wipe)
3. claude login → select Max subscription (OAuth)
4. Check ~/.claude.json → tengu_hawthorn_window is 200000, hasAvailableSubscription is false or None

What Was Tried

• Simple logout/login
• Enabling Extra Usage on claude.ai (hasExtraUsageEnabled flipped to true, no effect on window)
• Full credential wipe (rm ~/.claude.json) + fresh login
• Manual patching of ~/.claude.json (server overwrites on next session)

Expected Behavior

• tengu_hawthorn_window should return 1000000 for Max subscription
• hasAvailableSubscription should return true
• /model should show Opus 4.6 with 1M context window

Related Issues

• #35877 — hasAvailableSubscription: false despite active Max subscription
• #40223 — Regression: Opus 1M context shows 'Billed as extra usage' on Max plan
• #39841 — Opus 1M context on Max plan requires extra usage despite docs
• #34143 — Opus 4.6 shows 200K context instead of 1M on Claude Max plan

🤖 Filed via Claude Code on behalf of the account holder.