[BUG] AskUserQuestion tool available to tmux teammates but renders in teammate pane with no leader notification

Preflight: Searched existing issues, single bug report, using latest version.

What's Wrong?

When using --teammate-mode tmux, the AskUserQuestion tool is available to tmux teammates but should not be (or should be forwarded to the team lead).

Tmux teammates are full CLI processes. Their tool resolution goes through the main session path, which only applies the subagent tool filter when an agent definition is present. Since tmux teammates are launched without an agent definition, the filter is skipped entirely and AskUserQuestion remains in the tool set.

When a tmux teammate invokes the tool, the interactive question UI renders in the teammate's own tmux pane. No message or notification is sent to the team lead. If nobody is watching the pane, the teammate blocks indefinitely waiting for input that will never come.

For comparison, in-process teammates correctly have AskUserQuestion stripped from their tool set by the subagent tool filter.

What Should Happen?

Either:

• AskUserQuestion should be filtered out of the tool set for tmux teammates (consistent with in-process mode), OR
• The tool should detect that it's running in a teammate process and forward the question to the team lead via SendMessage (similar to how ExitPlanMode sends a plan_approval_request when called by a teammate with plan_mode_required)

Steps to Reproduce

1. Start Claude Code with --teammate-mode tmux
2. Spawn a teammate via the Task tool
3. Give the teammate a task that causes it to invoke AskUserQuestion
4. Observe the question UI renders in the teammate's tmux pane, not the leader's terminal
5. The leader receives no notification that the teammate is waiting for input

Error Messages/Logs

No error - the teammate silently blocks waiting for user input in its pane.

Is this a regression?

I don't know.

Claude Code Version

2.1.37

Platform

Anthropic API

Operating System

Windows (WSL)

Terminal/Shell

Windows Terminal / WSL

Additional Information

The root cause is in the tool resolution path. The main session's tool resolution has a check: if the agent definition is null, tools are returned unfiltered (skipping the subagent tool filter entirely). Tmux teammates are launched as bare claude processes without an agent definition, so they get the full unfiltered tool set including AskUserQuestion.

The subagent tool filter (which correctly strips AskUserQuestion for in-process teammates) uses an exclusion set that also includes TaskOutput, ExitPlanMode, EnterPlanMode, Task, and TaskStop. It's worth checking whether any of these other tools have similar issues in the tmux teammate path.

ExitPlanMode is an interesting case: it's in the exclusion set for subagents, but separately has teammate-aware logic that sends a plan_approval_request to the team lead when isTeammate() is true. AskUserQuestion has no such teammate-aware path.