Max plan: skills with model frontmatter blocked by 1M context extra-usage gate

Preflight

• [x] I have searched for existing issues
• [x] This is a single bug report
• [x] I am using the latest version

What's Wrong?

On a Max plan ($200/month), running slash commands (skills) that specify a model in their YAML frontmatter (e.g., model: sonnet) triggers the error:

API Error: Extra usage is required for 1M context · run /extra-usage to enable, or /model to switch to standard context

The error suggests switching to "standard context," but the /model picker has no standard context option — only Default (Opus 4.6 1M), Sonnet, and Haiku.

The main session runs Opus 4.6 with 1M context without issues. The error only occurs when a skill launches a subagent on a different model (Sonnet). Enabling /extra-usage is not an acceptable workaround because it opens pay-as-you-go billing that should not be necessary on Max.

What Should Happen?

Skills with model: sonnet in their frontmatter should launch subagents on Sonnet 4.6 without requiring extra usage. Per the official 1M context GA announcement (March 2026), both Opus 4.6 and Sonnet 4.6 with 1M context are included at standard pricing on Max, Team, and Enterprise plans. The billing gate should not block this.

If the subagent does not need 1M context, there should be a way to specify standard context per subagent (e.g., a frontmatter field like extended_context: false). Currently no such option exists.

Steps to Reproduce

1. Be on a Max plan ($200/month)
2. Set main session model to Opus 4.6 (1M context) via /model — this works fine
3. Create a skill file in .claude/commands/ with the following frontmatter:

``yaml
---
model: sonnet
---
``
[any skill content]

1. Run the skill via /skill-name
2. Error appears: "API Error: Extra usage is required for 1M context"
3. The /model picker shows no "standard context" option to switch to
4. The only suggested fix is /extra-usage, which enables pay-as-you-go billing

Is this a regression?

Unknown

Claude Code Version

2.1.89

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code

Claude Model

Other

Error Messages/Logs

API Error: Extra usage is required for 1M context · run /extra-usage to enable, or /model to switch to standard context

Last Working Version

_No response_

Additional Information

• Max plan subscriber, confirmed via /status
• Main session on Opus 4.6 (1M context) works without issues
• Error only triggers when skill frontmatter specifies a different model (e.g., model: sonnet)
• Per the March 2026 announcement, Sonnet 4.6 with 1M context is included on Max at standard pricing ($3/$15 per Mtok) — no extra usage should be required
• The /model picker offers no "standard context" option, making the error message's suggestion impossible to follow
• There is no frontmatter field to control context window size per subagent
• Workaround: removing model frontmatter makes skills run inline on the parent model, but this defeats the purpose of allocating cheaper models to routine tasks