feat(desktop): pop out agent activity into a window

[tellaho]

Category: new-feature
User Impact: Users can keep an agent’s live activity visible in a separate desktop window while continuing to work in Buzz.

Problem: Agent activity is useful while work is in progress, but the in-app panel competes with the channel and disappears as users navigate. Making every activity entry point open a new window would be disruptive, so the existing in-app flow needs to remain the default.

Solution: Add an explicit Pop-out window action to the activity feed settings and the in-progress chip’s context menu. The companion window reuses Buzz’s authenticated app runtime and live data connections, while normal activity clicks continue to open the in-app panel.

File changes

desktop/src-tauri/capabilities/default.json
Allows the dedicated activity webview to use the existing desktop capabilities it needs.

desktop/src-tauri/src/agent_activity_window.rs
Creates or focuses a stable channel-and-agent-scoped native window using an encoded Buzz route.

desktop/src-tauri/src/lib.rs
Registers the activity-window command with the Tauri application.

desktop/src-tauri/tests/csp.rs
Keeps capability coverage aligned with the new companion-window label.

desktop/src/app/AppHuddleShell.tsx
Treats activity windows as passive companion surfaces rather than rendering unrelated huddle chrome.

desktop/src/app/AppShell.tsx
Removes primary-window rails, overlays, notifications, shortcuts, and deep-link ownership from companion windows.

desktop/src/app/AppShellChannelSurface.tsx
Lets the activity window render as an unframed focused surface.

desktop/src/app/BuzzThemeSurfaces.tsx
Generalizes the unframed surface description from huddle-only to companion windows.

desktop/src/app/companionWindow.ts
Centralizes native window-label classification for activity and huddle companions.

desktop/src/app/companionWindow.test.mjs
Pins companion-window label classification and primary-window exclusion.

desktop/src/features/agents/lib/agentActivityWindow.ts
Detects the activity companion and keeps its native title synchronized with agent and channel context.

desktop/src/features/agents/lib/agentActivityWindow.test.mjs
Covers concise activity-window title formatting.

desktop/src/features/agents/useOpenAgentActivity.ts
Preserves the established in-app panel/navigation behavior for ordinary activity entry points.

desktop/src/features/channels/ui/AgentSessionThreadPanel.tsx
Adds Pop-out window to activity settings and adapts panel controls for a dedicated window.

desktop/src/features/channels/ui/BotActivityBar.tsx
Adds the in-progress chip context menu while retaining the normal click-to-open-in-app flow.

desktop/src/features/channels/ui/ChannelComposerActivityAccessory.tsx
Passes the explicit pop-out action into the composer activity chip.

desktop/src/features/channels/ui/ChannelPane.tsx
Connects channel and thread activity chips to the external-window action.

desktop/src/features/channels/ui/ChannelPane.types.ts
Defines the separate in-app and external activity handlers.

desktop/src/features/channels/ui/ChannelScreen.tsx
Recognizes dedicated activity-window layout and wires both activity destinations.

desktop/src/features/channels/ui/useOpenAgentActivityActions.ts
Owns the distinct in-app and native-window opening behavior outside the oversized channel screen.

desktop/src/features/channels/ui/ChannelScreenLoadingFallback.tsx
Suppresses the normal channel header while the focused activity window loads.

desktop/src/main.tsx
Disables onboarding overlays in companion windows.

desktop/src/shared/api/agentActivityWindow.ts
Provides the typed frontend command for opening an activity window.

desktop/src/shared/layout/AuxiliaryPanelHeader.tsx
Allows focused panels to omit the in-app close action without changing other header behavior.

desktop/src/shared/layout/auxiliaryPanelContext.test.mjs
Covers explicit close-action suppression.

desktop/src/testing/e2eBridge.ts
Keeps browser E2E on the in-app fallback because it cannot create a native Tauri webview.

desktop/tests/e2e/channels.spec.ts
Covers both Pop-out window entry points while confirming normal activity clicks remain in app.

Reproduction steps

1. Run the desktop app and open a channel where an agent is actively working.
2. Click the in-progress chip below the composer and confirm the activity feed opens in Buzz’s existing side panel.
3. Right-click the in-progress chip and choose Pop-out window; confirm a separate window opens for that agent and channel.
4. Open the in-app activity feed, open its settings menu, and choose Pop-out window; confirm it focuses the same scoped window rather than creating duplicates.
5. Navigate elsewhere in the main app and confirm the pop-out keeps receiving live activity.
6. Stop the agent and confirm archived activity and settings remain available in the pop-out.

Screenshots / demos

Native companion-window capture is pending; the draft is open for implementation review first.