Activity sidebar

A unified view of every agent in the workspace.

The activity sidebar is atrium's "what is happening right now" surface. It shows every running agent in the active workspace with status, last event, and quick actions — expanded into cards or collapsed to a strip of status dots.

Toggle it with Cmd+Shift+A.

Layout

The sidebar groups cards by workspace into collapsible sections, each with a count chip and the workspace's icon (custom emoji / lucide / hash color). Workspace order matches the main sidebar; section names truncate at the chevron rather than wrapping. Within each workspace group, rows appear top to bottom in this order:

Live terminal rows — foreground processes currently running in terminal panes, ringed with the adapter accent so they pop while running. Click a row to jump to the pane. Hover for stop (SIGTERM) and close pane actions.
Stopped-process rows — when you stop a foreground process or it crashes, its command stays in the sidebar with a play button to re-run it, a stop/play toggle if it's running again, and a remove-from-sidebar button to hide it without closing the pane. Commands that exit cleanly on their own (clear, ls, a successful build) do not surface — only non-clean exits and user stops.
Pinned cards — agents you marked Later; stay visible even when idle.
Active cards — agents that are working, waiting for input, or were recently stopped.
Dismissed cards — kept in a collapsed region so you can undo a dismissal.

Workspace filtering surfaces a count badge so you can tell at a glance how many cards are hidden by the current filter, and Later / Dismissed flags survive workspace filter changes. Workspaces can also be hidden from the sidebar entirely from the workspace row's context menu.

Status states

Each agent card shows a status badge. States (driven by hook events from the adapter):

idle — waiting for input.
working — processing; a tool call is in flight.
waiting-for-input — blocked on a user prompt.
needs-permission — a tool permission is pending.
stopped — killed by signal or exited.
crashed — unexpected exit.
rate-limited / auth-failed / billing-exceeded — special stop reasons surfaced when the adapter reports them.

The adapter's accent color appears on the card's border so you can tell Claude / Codex / Gemini apart at a glance.

Per-card actions

Click — jump to the agent's pane.
Message — an inline reply field. Cmd+Enter or Ctrl+Enter sends the text to the agent.
Popout — pop the card's pane out into its own room without taking your eyes off the sidebar.
Kebab menu — Dismiss, Later (pin), Close pane, View details.
Undo (on dismissed cards) — restore to active. Resume is also available on dismissed and idle cards directly from the card and the collapsed-sidebar tooltip.
Nudge (on stopped or resume-failed panes) — ask the adapter to pick back up where it left off.

Tooltips on sidebar chrome (the popout, dismiss, and message buttons) appear instantly rather than after a hover delay, so flicking the pointer past each card surfaces the label without breaking flow.

When an agent goes idle, the pane dims to an idle backdrop with a screenshot of its last visible state, a Resume button in the foreground, and the same dismiss/later affordances as the sidebar card. Resuming brings the pane back live without restarting the adapter session.

Working vs. waiting

A card flips from working to waiting-for-input only when the adapter and all of its subagents have nothing in flight. If a primary turn finishes but a spawned subagent is still running, the sidebar keeps the card in working instead of falsely flashing waiting. The same logic drives the dock badge and OS notifications.

Density

Three densities, toggleable per workspace:

Full — status, last event, progress details, tool call summary, permission preview.
Semi — status badge with the last event time.
Compact — just a status dot and the adapter's accent color.

Set under Settings → Activity → Density.

Collapsed mode

Clicking the sidebar's collapse chevron shrinks it to a dot strip. Each dot represents one agent with its status color. The focused pane's dot gets a focus ring so the spatial cue isn't lost when the sidebar is narrow. Hover to preview the full card; click to expand back.

Notifications

OS notifications — a native macOS notification fires for status transitions you care about (for example, working → waiting-for-input). Enable under Settings → Activity → Notifications. Clicking an OS notification jumps directly to the pane that posted it, even when atrium isn't the focused app.
Toasts — in-app popovers for cross-room events. Useful when you are in another room and an agent needs attention.
Dock badge — the app icon shows a count of agents needing input.

Adapter color scheme

Per the current design, the focused pane's card gets an accent wash across the whole card. Unfocused cards share a neutral resting border; per-adapter accent color shows up as a side ring rather than a full card tint.

Workspace sidebar — summary view

The main workspace sidebar has a complementary summary view mode. Where the tree view lists workspaces and their files, the summary view shows one activity micro-card per workspace: the running agents, the pending tasks, the worktree changes diffed against each worktree's fork base.

Right-click any row for the same actions as the tree view (open search, source control, edit, hide, remove).
Worktree strips align under their parent workspace and share a unified hover envelope, so a long worktree list still reads as one block.
Summary diff polling is staggered, so switching rooms doesn't trigger a lag burst from refreshing every card at once.

Workspaces hidden from the activity sidebar via the workspace context menu also drop out of the summary view's roll-up, so noisy or archived projects can be silenced without removing them from the tree.