[BUG] Agent Teams: teammates intermittently stop receiving SendMessage after extended polling (default mode, not tmux)

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?

When using Agent Teams in default mode (not tmux), messages sent by the team lead via SendMessage appear to succeed but teammates never receive them — they sit idle as if nothing was sent.

Key detail: this does not happen immediately — teammates initially poll and receive messages correctly. After polling for a while, they get stuck and stop processing new messages. This has been observed multiple times. The polling in question was done using a plain bash sleep loop (e.g. while true; sleep N; do something; done), not the newer CronCreate tool.

The workaround: pressing Esc while viewing a stuck teammate's pane causes the previously-sent message to suddenly come through, and the teammate starts working. Without pressing Escape, the teammate remains idle indefinitely.

This is distinct from #23415 and its duplicates (#25254, #24771, #24108), which all describe the same symptom on the tmux backend. This issue occurs on the default (non-tmux) teammate mode, suggesting the inbox polling problem is not tmux-specific but affects the core message delivery/processing layer.

What Should Happen?

Teammates should continue to receive and process SendMessage messages reliably, even after extended polling periods, without requiring any manual UI interaction.

Steps to Reproduce

1. Start Claude Code (default teammate mode — no tmux configuration)
2. Create a team and spawn teammates
3. Have a teammate run a bash sleep polling loop (e.g. checking an external resource on an interval)
4. Send messages to teammates via SendMessage — initially works fine
5. After the teammate has been polling for a while, send another message
6. Observe the teammate sitting idle, not processing the message
7. Switch to the teammate's view and press Esc
8. The message is now received and the teammate begins working

Note: this is intermittent — it doesn't happen on every message, but specifically after teammates have been actively polling for some time.

Claude Model

Opus

Is this a regression?

I don't know

Claude Code Version

2.1.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Warp

Additional Information

The Escape key likely triggers a UI re-render cycle that causes the teammate to check its inbox. The fact that polling works initially but breaks after extended activity suggests a race condition or a polling interval that stops/stalls after some time — possibly related to context compaction, session state changes, or a timer that gets dropped. The bash sleep loop may be relevant — a long-running Bash tool call could block the teammate's message processing loop.

Related issues (all tmux-specific, closed as duplicates of #23415):

• #25254
• #24771
• #24108