The subagent just hung on “thinking”

Describe the Bug

The subagent simply hung on “thinking” while it was running. It was also impossible to open it from the chat — I had to ask Composer to find it in a new chat and write me a link to it.

Steps to Reproduce

I don’t know. This is the first time I’ve seen something like this.

Screenshots / Screen Recordings

Operating System

Windows 10/11

Version Information

Version: 3.17.9 (system setup)
VS Code Extension API: 1.128.0
Commit: 9f18743c4ed6673eff64d0506c3339098164d110
Date: 2026-08-20T21:42:39.820Z
Layout: IDE
Build Type: Stable
Release Track: Nightly
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.291
OS: Windows_NT x64 10.0.22631

For AI issues: which model did you use?

Agent: Kimi K3 Max
Subagent: Grok 4.6 XHigh

For AI issues: add Request ID with privacy disabled

Agent: 07b76955-207f-4866-931b-0c8cc0f5cdf1
Subagent: 4b6316b5-fc90-4ae9-b7f1-e2374d357378
Privacy on

Does this stop you from using Cursor

Yes - Cursor is unusable

Hey @Artemonim, thanks for the detailed report — the request IDs were really helpful. I’ve flagged this to the team.

From what we can see, your subagent actually kept working in the background the whole time; the display just stopped updating, which is what we’re looking into.

If it happens again, reloading the window (Ctrl+Shift+P → “Reload Window”) should resync the chat so you can see the subagent’s real progress.

It doesn’t help in 43350e5f-1788-43ec-9e01-08d09410584f:

  1. A window popped up
  2. It warned me that I had two active agents
  3. I confirmed “Reload”
  4. For a moment, an error message about a lost connection appeared in the chat with a “Resume” button, and the agents went into a restart.
  5. After the restart, the main agent is simply stopped, while the subagent is still “Stopped” and cannot be opened from the chat.

+1 on this. This has happened for a month now, very frustrating not knowing what the heck the subagents are doing on the background.

Hey @Artemonim, quick update from our side. We kept an eye on your account after your last report, and since the evening of Aug 24 your sessions have been running clean, including the subagent-heavy ones.

Can you confirm if things are working better on your end now?

That particular bug hasn’t been encountered.