[BUG] Explore subagent inherits parent model (opus) instead of using Haiku as documented

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

According to the official documentation at https://code.claude.com/docs/en/sub-agents#explore, the Explore subagent should use the Haiku model by default for fast, low-latency code exploration. However, when running in plan mode with opusplan model, the Explore subagent incorrectly inherits the parent agent's model (opus) instead of using Haiku.

This appears to be a discrepancy between the documented behavior and the actual implementation.

What Should Happen?

The Explore subagent should use the Haiku model, as documented:

Explore: Haiku - Fast, low-latency exploration for searching and exploring codebases

This is consistent with the documented behavior where specific subagent types have fixed model assignments for optimal performance.

Error Messages/Logs

Steps to Reproduce

1. Set the model to opusplan:

``
/model opusplan
``

1. Enter plan mode (or any mode that uses subagents)

1. Launch an Explore subagent using the Agent tool:

``typescript
Agent({
description: "Explore codebase",
prompt: "Explore the web search implementation in this codebase",
subagent_type: "Explore"
})
``

1. Observe the model used by the Explore subagent in the output

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.63

Platform

Other

Operating System

macOS

Terminal/Shell

Other

Additional Information

_No response_