Team agent --model ignores ANTHROPIC_DEFAULT_*_MODEL and CLAUDE_CODE_SUBAGENT_MODEL env vars

Description

When spawning team agents via the Agent tool, the agent process receives a hardcoded --model claude-opus-4-7 CLI argument that overrides all environment-based model configuration.

Steps to reproduce

1. Configure Claude Code with a non-default API backend:

{
  "env": {
    "ANTHROPIC_BASE_URL": "https://api.deepseek.com/anthropic",
    "ANTHROPIC_MODEL": "deepseek-v4-pro[1m]",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "deepseek-v4-pro",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "deepseek-v4-pro",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "deepseek-v4-flash",
    "CLAUDE_CODE_SUBAGENT_MODEL": "deepseek-v4-pro"
  }
}

1. Create a team and spawn a general-purpose agent:

TeamCreate → Agent(subagent_type="general-purpose", team_name="test")

1. Inspect the spawned agent process:

ps e -p <agent_pid> | tr ' ' '\n' | grep -E "model|ANTHROPIC"

Actual behavior

Agent process is launched with:

--model claude-opus-4-7

Despite env vars being correctly set in the agent process environment:

CLAUDE_CODE_SUBAGENT_MODEL=deepseek-v4-pro
ANTHROPIC_DEFAULT_OPUS_MODEL=deepseek-v4-pro
ANTHROPIC_MODEL=deepseek-v4-pro[1m]

The --model flag takes precedence over env vars. This causes the agent to send requests with model name claude-opus-4-7 to a non-Anthropic backend that doesn't recognize it, which triggers an error in the Ink rendering layer and crashes the agent's TUI. The agent process stays alive as a zombie but is unresponsive.

Expected behavior

Team agent spawn should:

• Respect CLAUDE_CODE_SUBAGENT_MODEL env var for model selection, OR
• Resolve the agent definition's model (claude-opus-4-7) through ANTHROPIC_DEFAULT_OPUS_MODEL mapping before passing --model, OR
• At minimum not pass --model at all, letting the env vars take effect

Environment

• Claude Code version: 2.1.119
• OS: macOS 15.x (Darwin 25.3.0)
• Backend: DeepSeek API (Anthropic-compatible endpoint)
• The model resolution works correctly for the main session — only team agents are affected.