[BUG] Sub-Agent execution using LiteLLM configuration

Environment

• Platform (select one):
• [ ] Anthropic API
• [X] AWS Bedrock
• [ ] Google Vertex AI
• [x] Other: LiteLLM
• Claude CLI version: 1.0.64
• Operating System: macOS 15.5
• Terminal: IntelliJ IDEA Terminal

Bug Description

I got an API response error when trying to use a sub-agent for a specialized task, and using the LiteLLM proxy configuration with the AWS Bedrock model ID.

Steps to Reproduce

<img width="1896" height="859" alt="Image" src="https://github.com/user-attachments/assets/6652cc58-8522-4448-9cb9-d8739c45fc6a" />

<img width="1657" height="271" alt="Image" src="https://github.com/user-attachments/assets/ea4cb2d1-2b61-4152-815e-e51d81bb483b" />

Additional Context

Env configuration

# CLAUDE CODE DEFAULT CONFIG
export ANTHROPIC_BASE_URL=<LiteLLM PROXY>
export ANTHROPIC_AUTH_TOKEN=<API_KEY>
export ANTHROPIC_MODEL=bedrock/<MODEL>
export CLAUDE_BASH_MAINTAIN_PROJECT_WORKING_DIR=1

Claude code works smoothly. I wanted to try this new feature, but it does not work for me.