Agent Teams: Support per-teammate model configuration

Feature Request

Problem

When using Agent Teams (CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS), there is no way to specify different models for individual teammates. All teammates unconditionally inherit the team lead's model (e.g., Opus), regardless of any configuration attempt.

What I've Tried

| Method | Result |
|--------|--------|
| Agent file frontmatter model: sonnet | ❌ Ignored in Teams (works for standalone sub-agents) |
| Natural language "Use Sonnet for each teammate" | ❌ Ignored |
| Full model ID claude-sonnet-4-6 in frontmatter | ❌ Ignored |
| Environment variable CLAUDE_CODE_SUBAGENT_MODEL=sonnet via Bash export | ❌ Not passed to Agent Teams process |
| Environment variable in ~/.claude/settings.json env | ❌ Works for standalone sub-agents, ignored in Agent Teams |

Expected Behavior

Ability to specify per-teammate models in Agent Teams, similar to how standalone sub-agents support the model field in .claude/agents/*.md frontmatter.

Use Case

Running a mixed-model team for cost optimization:

• Opus for complex roles (tech-lead, PM) requiring deep reasoning
• Sonnet for execution-heavy roles (frontend-dev, backend-dev, infra, QA, designer)

This would significantly reduce API costs while maintaining quality where it matters most.

Suggested Solutions (any of these would work)

1. Add a model parameter to the Agent tool when spawning teammates
2. Respect the model frontmatter in custom agent files (.claude/agents/*.md) when used in Teams
3. Add a Teams-specific environment variable (e.g., CLAUDE_CODE_AGENT_TEAMS_DEFAULT_MODEL)

Environment

• Claude Code version: latest
• Feature flag: CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1
• OS: macOS