Weird delivery of subsequent messages to subsessions

I asked parent session to ask subsessions to get reviews. However, the subsessions didn't get the message but got into multi-chat state with unnamed tabs/multi-chats. I would expect that the same subsessions get the new messages.

repro:

1. create a session and ask it to create subsessions for each to fix a particular issue
2. in the parent session, ask "Ensure those get reviews on architecture and engineering."
3. :bug: subsessions get into multi-chat state with tabs just named "new chat"

Version: 1.131.0-insider (Universal)
Commit: 89f97b7558e686b089c4b8a0294b16c95f1be8d5
Date: 2026-07-27T18:28:30-07:00
Electron: 42.7.0
ElectronBuildId: 14710161
Chromium: 148.0.7778.280
Node.js: 24.18.0
V8: 14.8.178.38-electron.0
OS: Darwin arm64 25.5.0