[Bug]: Agents panel shows a resumed delegated child once per task record, all Working #30911

What happens

After a delegated child thread is stopped and then resumed by t3_thread_send, the Agents panel shows one row per task record for that child, and every row says Working. In my case one child thread had three rows: same title, same model (Codex), same branch, start times within about 45 seconds of each other, each with its own stop button.

Only one run is actually active. t3_thread_list with includeSubagents: true and statuses: [running, …] returns exactly one running child thread.

Sequence

1. The parent calls delegate_task, which creates task A for child thread T.
2. The user accidentally presses stop on T.
3. The parent sends t3_thread_send to T to resume it. Per the tool contract, a send to a finished child starts a fresh task: task B.
4. Later, the parent sends more t3_thread_send messages to the running T. A third task record, task C, appears (a node:delegated-task:<uuid> id). Some later steers return C again.
5. The Agents panel lists A, B and C as Working.

Expected

A superseded task record for the same child thread settles when its run ends or when a newer task takes over the thread. The panel then shows one Working row per running child.

Impact

• Users read the panel as several duplicate agents running and spending tokens.
• Every row's stop button stops the same live child, so cleaning up "duplicates" kills real work.

Environment

macOS; Claude Code parent thread; Codex child thread; observed 2026-11-04.