Max plan: sonnet[1m] requires extra usage but opus[1m] is included - inconsistent

Description

On a Max plan (personal account, not organization), opus[1m] works perfectly but sonnet[1m] returns:

Sonnet 4.6 with 1M context is not available for your account.
Learn more: https://code.claude.com/docs/en/model-config#extended-context-with-1m

Why this doesn't make sense

Opus is the larger, more expensive model. Sonnet is the smaller, cheaper one. If Max includes opus[1m], it's counterintuitive that sonnet[1m] (a less expensive model) requires extra usage/additional payment.

From a user perspective, this feels like an oversight rather than an intentional pricing decision.

Steps to reproduce

1. Have a Max plan (personal account)
2. Run /model opus[1m] → works fine
3. Run /model sonnet[1m] → error above

Expected behavior

If opus[1m] is included in Max, sonnet[1m] should also be included (or at least there should be a clear explanation of why the cheaper model costs extra).

Environment

• Claude Code CLI
• Max plan (personal)
• macOS