CLI requires extra-usage billing for fast Opus 4.6, but desktop app runs it on Max plan

Summary

The desktop Claude app lets a Claude Max subscriber pick Opus 4.6 Max Fast and use it on their included Max usage. The Claude Code terminal CLI on the same OAuth account refuses with a message that fast mode requires extra-usage (pay-per-token) billing to be enabled.

This is a parity gap between clients, not a billing or auth issue.

Environment

• CLI version: 2.1.123 (latest on npm at time of report)
• Install method: Homebrew (/opt/homebrew/bin/claude)
• Auth: OAuth (ANTHROPIC_API_KEY is unset, verified)
• Plan: Claude Max — oauthAccount.organizationRateLimitTier: 'default_claude_max_20x'
• Org: personal org, user is admin
• Cached entitlement state in ~/.claude.json:
• oauthAccount.hasExtraUsageEnabled: false
• cachedExtraUsageDisabledReason: 'org_level_disabled'

Repro

1. Subscribe to Claude Max.
2. Open the Claude desktop app — pick Opus 4.6 Max Fast from the model list. It runs on included Max usage. ✅
3. Open Claude Code in the terminal, authed via the same Claude.ai OAuth account.
4. Run /model — only Opus 4.7, Sonnet, Haiku appear. No Opus 4.6 / fast option.
5. Run /fast — message says fast mode requires extra-usage billing. ❌

Expected

The CLI should honor the same Max-tier fast Opus 4.6 entitlement that the desktop app honors for the same OAuth account. Either:

• Surface "Opus 4.6 Max Fast" in /model for Max subscribers, or
• Allow /fast to toggle on without extra-usage billing when the account is on a Max plan.

Actual

/fast is gated on hasExtraUsageEnabled regardless of Max-tier entitlement. Forces Max users to choose between (a) using desktop, (b) enabling pay-per-token billing they don't want, or (c) not using fast Opus 4.6.

Notes

• Public docs at https://code.claude.com/docs/en/fast-mode currently say fast mode is "available via extra usage only and not included in the subscription rate limits" — but this contradicts the actual desktop-app behavior for Max subscribers, so the docs likely also need updating once the CLI catches up.