[BUG] Team agent in tmux mode: sub-agents don't inherit the team lead's model, defaults to opus-4-6

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?

CC version 2.1.39
We use bedrock. Config is setup using ~/.claude/settings.json

I use iterm2 with tmux -CC

When i ask claude code to use team agent and spin up sub agents (in tmux mode), it successfully spawns the agents and opens the iterm2 panes, but the sub agents keep getting 400 error because they are trying to use claude-opus-4-6 model, even though the teamlead agent is using our bedrock model configuration.

I expect the subagents to inherit parent's model.

the in-process mode of agent teams does not exhibit the same behavior and team agents works fine in that mode.

What Should Happen?

sub agents should inherit parent's model

Error Messages/Logs

Steps to Reproduce

open iterm2.
run command: tmux -CC

setup claude code env in settings.json to use bedrock, and use team agents:

"env": {
"ANTHROPIC_MODEL": ".../us.anthropic.claude-opus-4-6-v1",
"ANTHROPIC_DEFAULT_HAIKU_MODEL": "XXXX",
"ANTHROPIC_SMALL_FAST_MODEL": "XXXX",
"AWS_REGION": "us-west-2",
"CLAUDE_CODE_USE_BEDROCK": "1",
"CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS": "1",
"AWS_PROFILE": "ai"
},

run claude.

ask CC to spawn an agent team with 2 subagents and give them a task.

The sub agent panes will open in iterm2 panes but will keep throwing errors when trying to use opus-4-6 (because our org has restricted it and we only use bedrock).

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.39

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_