VS code github copilot UI is broken for subagents

- Copilot Chat Extension Version:
Version: 1.135.0 (Universal)
Commit: 08d4889f9ec4a1685d257b9b95de036c8e1ce1e5
Date: 2026-08-25T14:26:52Z
Electron: 42.8.1
ElectronBuildId: 14906494
Chromium: 148.0.7778.280
Node.js: 24.18.1
V8: 14.8.178.38-electron.0
@github/copilot: 1.0.81-0
@github/copilot-sdk: 1.0.11
OS: Darwin arm64 25.5.0

- Feature (e.g. agent/edit/ask mode):
- Selected model (e.g. GPT 4.1, Claude 3.7 Sonnet):
- Logs:

Steps to Reproduce:

1. Subagent delegation (make sure subagents task is long enough, not very small trival task)
2. stay away from vs code come back later (you see something like this, sub agent is running fine, looks like UI issue