[Feature]: Let the Agents panel clear settled and idle agents

[LordMerc]

Area

apps/web

Problem or use case

On a long-lived thread the Agents panel accumulates every subagent it has ever spawned, and there is no way to hide any of them. Finished agents (completed / failed / cancelled / interrupted) and idle ones stay in the list forever, so the one agent that is actually working ends up buried under history.

This gets worse the more useful a thread is. A thread that has run several workflows can show a dozen-plus dead rows above the single running agent, and scanning for live status turns into a hunt.

Idle is the annoying case specifically. An idle agent is not finished, so it never reads as "done", but it is also not doing anything — it just sits there looking like it might still matter.

Proposed solution

Add a Clear inactive button to the Agents panel footer. It hides every agent in the current thread that is not actively working — both settled and idle. Agents in pending, running, or waiting stay visible.

Nothing is destroyed. The clear is a per-thread timestamp cutoff:

• The footer shows N hidden · Show all while a cutoff is active, so it is always reversible.
• The empty state becomes "No active agents" with the hidden count and a Show all button.
• The cutoff lives in localStorage, keyed per thread.
• Any agent that starts working again reappears on its own, because its updatedAt moves past the cutoff.
• Workflow groups clear atomically — if any member is still working or newer than the cutoff, the whole coordinator/member group stays visible, so you never see a workflow with holes in it.

Explicitly out of scope: this is presentation-only. Clearing does not cancel an agent, delete provider history, or touch orchestration state. No server changes.

Why this matters

Anyone running multi-agent threads for more than a few minutes. The Agents panel's job is to tell you what is happening now, and right now it competes with an unbounded, unfilterable log of what already happened. A one-click way to collapse to "just the live ones" makes the panel usable on exactly the threads where it matters most.

Smallest useful scope

A single Clear inactive button that hides non-working agents for the current thread, with Show all to undo it. Client-side only, no persistence across devices, no per-agent dismissal, no auto-clearing.

Alternatives considered

• Clear only terminal agents. Simpler, but leaves idle agents on screen — which is most of the clutter in practice, so the button would look broken.
• Per-agent dismiss (an × on each row). More precise, but it is a click per agent when the common case is "hide all the dead ones at once".
• Auto-hide after a timeout. Removes control from the user and makes agents vanish while you are reading them.
• Collapsible "Earlier" section. Some grouping already exists; it still leaves everything on screen and does not help when the history is long.
• Reloading the page / switching threads. Doesn't help — the panel rebuilds from the same state.

Risks or tradeoffs

• Idle is treated as clearable, which is a judgment call. An idle agent is resumable, so someone could reasonably argue it should stay. The reappear-on-resume behavior is what makes this safe, and Show all is always there.
• Cutoff state is per browser. Clearing on desktop does not clear on mobile. Acceptable for a view preference.
• The stored map grows one entry per thread you have ever cleared, so it needs a cap (oldest dropped first) to avoid unbounded localStorage growth on long-lived installs.
• Interaction with Agents panel (new in #5219): a resumed subagent stays in Earlier and stops updating - 0.0.32-nightly.20260806.1014 #5529 (resumed subagent stays in Earlier and stops updating). A cutoff based on updatedAt depends on that field advancing on resume; if it does not, a resumed agent could stay hidden. Worth checking these together.

Examples or references

Related: #5529, #5219.

Contribution

I would be open to helping implement this.