Task tool model parameter ignored when spawning teammates with team_name

Bug: model parameter ignored when spawning team members via Task tool

Description

When using the Task tool with both model and team_name parameters to spawn a teammate into a swarm team, the model parameter is silently ignored. All team members inherit the parent agent's model regardless of what model value is specified. The model parameter works correctly for standalone Task calls (without team_name).

Reproduction Steps

1. Start a session on claude-opus-4-6 (or any model)
2. Create a team:

``
TeamCreate with team_name: "test-team"
``

1. Spawn a standalone agent (no team) with model: "haiku":

``
Task tool:
subagent_type: "general-purpose"
model: "haiku"
prompt: "Report your model name and model ID."
`
**Result:** Agent correctly reports as Claude Haiku 4.5 (claude-haiku-4-5-20251001`) ✅

1. Spawn a team member with model: "haiku":

``
Task tool:
subagent_type: "general-purpose"
model: "haiku"
name: "junior-dev-1"
team_name: "test-team"
prompt: "Report your model name and model ID in your first message to the team lead."
`
**Result:** Agent reports as Claude Opus 4.6 (claude-opus-4-6`) — inherits parent model ❌

Expected Behavior

Team members spawned with model: "haiku" should run on the haiku model, just like standalone agents do.

Actual Behavior

The model parameter is silently ignored when team_name is provided. All team members run on the parent agent's model. No error or warning is surfaced.

Impact

This breaks the cost-tiering strategy for swarm teams, where expensive models (opus) are meant for design/review roles and cheap models (haiku) handle bulk implementation work. Without working model selection, all team members run at the highest cost tier, making swarm teams significantly more expensive than intended.

Environment

• Claude Code CLI
• Parent model: claude-opus-4-6
• Date observed: 2026-02-10
• Tested with model: "haiku" on team-spawned agents (confirmed with 2 separate agents)