[BUG] CLAUDE_CODE_SUBAGENT_MODEL Inheritance Issue

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?

When the main session is configured to a local model via ANTHROPIC_API_KEY routing, CLAUDE_CODE_SUBAGENT_MODEL set to the local model name, claude-code-guide/named subagents still fail with claude-haiku-4-5-20251001 not found, while subagent_type: "fork" correctly inherits the local model

What Should Happen?

The subagent should inherit the model the main session is using. The parameter is set for inheritance but it still defaults to Haiku

Error Messages/Logs

Agent "Claude Code hooks guide" failed: Agent terminated early due to an API error: There's an issue with the selected model
(claude-haiku-4-5-20251001). It may not exist or you may not have access to it. Run /model to pick a different model. (error type
model_not_found, HTTP 404, model sent to the API: claude-haiku-4-5-20251001)

Steps to Reproduce

Issue a prompt that will call a subagent while the model is set to a local model. The subagent will fail saying it has an API Error with the selected model (Claude-haiku-4-5-20251001.

Claude Model

Other

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.263

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_