Subagent spawned with 'model: opus' fails with '1M context requires extra usage' even when Extra Usage is enabled

[innocarpe]

Bug Report

Summary

When a subagent is defined with model: opus in its frontmatter and gets spawned via the Agent tool, it throws the following error even when Extra Usage is already enabled in the parent session:

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

Environment

• Claude Code CLI
• Plan: Max $200
• Extra Usage: Enabled
• Trigger: Invoking a slash command (e.g. /core:create-pr) that internally spawns an Agent with model: opus

Steps to Reproduce

1. Enable Extra Usage via /extra-usage in a Claude Code session.
2. Define a subagent in .claude/agents/my-agent.md with model: opus in the frontmatter.
3. Invoke a skill or command that spawns that subagent via the Agent tool.
4. Observe the error: API Error: Extra usage is required for 1M context

Expected Behavior

Spawned subagents should inherit the Extra Usage setting from the parent session, or Extra Usage should be applied at the account level regardless of which session (parent or child) makes the API call.

Actual Behavior

Subagents spawned with model: opus fail with the 1M context error even though Extra Usage is enabled in the parent session. The error suggests the child agent session does not inherit the Extra Usage setting.

Workaround

Changing the subagent frontmatter from model: opus to model: sonnet resolves the issue, but this is a degradation in model quality for tasks that benefit from Opus.

Additional Context

This appears to be a session inheritance issue — the Extra Usage flag enabled in the parent session is not being propagated to spawned subagent sessions. This is particularly disruptive for users who rely on agent compositions (skills/commands that orchestrate multiple subagents), as the error surfaces mid-workflow and is not immediately obvious to diagnose.

[github-actions]

Found 3 possible duplicate issues:

1. WebSearch and subagents fail with 'Extra usage required for 1M context' on Max plan #44117
2. [BUG] Skill model: frontmatter triggers 429 "Extra usage required" on 2.1.76 when session uses opus[1m] #34296
3. Max plan: skills with model frontmatter blocked by 1M context extra-usage gate #42082

This issue will be automatically closed as a duplicate in 3 days.

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🤖 Generated with Claude Code

[0xbrainkid]

This is another example of entitlement state not propagating correctly across execution boundaries. The parent session has Extra Usage enabled, but when the subagent is spawned with model: opus, the child behaves as if that entitlement is absent and throws the 1M-context gating error.

From the user perspective, that is especially confusing because there is no obvious separate place to "enable Extra Usage again" for the subagent. The reasonable expectation is that a child agent inherits the effective billing/capacity context of the session that created it, unless the product explicitly says otherwise.

So the real problem is not just the error text. It is broken state propagation across parent → subagent runtime boundaries.

This fits the same broader class as other recent issues:

• usage surfaces disagreeing with runtime gating
• extra-usage state not reflected in warnings
• feature/capacity state changing across invocation paths

If entitlement exists at the parent session level, subagent launches should either inherit it correctly or fail with a much clearer explanation of why the child context is different.

[github-actions]

Closing for now — inactive for too long. Please open a new issue if this is still relevant.