Hermes threads show idle while its background work and subagents are still running #60

Observed

2026-10-31: "when im using hermes in t3code app, it doesn't show work as ongoing even if subagents are still working. like the ui ux is misleading."

On the checked thread, T3 marked the parent completed (activeRunId: null) while a Hermes-owned background render was still running (process alive, 2,400 frames verified, finalizer waiting).

Triage

• T3 already has the right model. Upstream PR 24610 (merged 10-25, fixes upstream issue 19926) keeps a thread Working while awaited background work runs. Its own text says it is Claude-only: "Other providers return 'unsupported' and keep today's behavior."
• Hermes already has the data on its gateway (process.list, subagent.start, agent.terminal.output). The ACP projection drops it.
• Hermes-side venues are open upstream: Hermes issue 137069 and draft PR 137380 (ACP subagent_update), and 141895.

Acceptance

• An ACP agent that reports background or subagent work keeps the thread in Working (or "Subagents working · N") until it settles. Web, desktop and mobile follow the same rule.
• Failed or interrupted children stay visible.
• Decide the transport (ACP subagent_update vs. T3 consuming the Hermes gateway) with the Hermes PR authors before writing code.