[Bug]: Parent thread leaves Working while its side chat is still running #28659

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/web (also visible in the desktop app)

What happened

A thread appears in the main sidebar list above Working while a side chat inside that thread is still running. Side chats have no separate sidebar row, so the sidebar gives no Working entry for the ongoing work.

In the reported case, the main thread showed "Run interrupted · Stopped by user". Its side chat remained open in the right panel and showed "Waiting on 2 commands" with a Stop button. The parent thread's sidebar row stayed above the Working section.

Steps to reproduce

Based on the reported state:

1. Enable the Working shelf in the sidebar.
2. Open a thread and start a side chat in its right panel.
3. Send work in the side chat that keeps commands running.
4. With the main thread stopped or interrupted, observe its sidebar placement while the side chat is still waiting on commands.

Expected behavior

The parent thread should remain under Working while a side chat is running or waiting on commands, unless there is an actionable request that needs the user's attention. It should return to the main list when that work finishes or needs input.

Actual behavior

The parent thread is outside Working even though its side chat still has commands running. Because the side chat is hidden from thread lists, that running work has no entry under Working.

Impact

Minor bug or occasional failure. The sidebar makes ongoing work look ready for attention and hides it from the Working list.

Version or commit

Installed app version was not provided. Relevant source inspected at 8760d063e903406c8e8f695b0852c0a15fc1e00f. Side chats were introduced in #26901, merged October 31, 2026.

Environment

macOS, T3 Code desktop app. The reported side chat used Opus 5.5 High.

Investigation notes

• isThreadWorking takes the thread's own runtime, run and attention state; it does not inspect side chats.
• partitionSidebarThreads uses that Working classification to place the parent row.
• isListedThreadLineage excludes side chats from thread lists.

These are relevant investigation points, not a confirmed end-to-end root cause. The observed state comes from the user's screenshot; no additional live reproduction was performed while filing this issue.

Workaround

Open the parent thread and inspect the side chat directly.

Filed on the user's behalf by GPT-6 through Pi in T3 Code.