Desktop: Main thread hangs 2s+ on dock tile update — 11.4K events, 199 users

[beastoin]

Problem

The desktop app UI freezes for 2+ seconds when the macOS dock tile is updated. This is the second most common Sentry issue:

• OMI-DESKTOP-Y + 5 related clusters
• 11,400+ events across 199+ users
• Stack trace: WindowDockTileInvalidator.updateDockTile -> NSDockTile display -> CoreDockUpdateWindow -> mach_msg2_trap

The main thread blocks on a synchronous mach message to the Dock server.

Root Cause Analysis

Traced through CrispManager.swift and SidebarView.swift:

1. CrispManager polling triggers cascading view invalidation

CrispManager.swift line 63: A Timer.scheduledTimer fires every 120 seconds on the main thread, calling pollForMessages(). When the API returns results, @Published unreadCount is incremented (line 112).

2. SidebarView observes CrispManager

SidebarView.swift line 83: @ObservedObject private var crispManager = CrispManager.shared. Every unreadCount change invalidates the entire SidebarView — a core structural component containing navigation items, status displays, device connection widgets, and update indicators.

3. View invalidation cascades to dock tile update

When SidebarView re-evaluates, the window content changes, macOS detects the update, and triggers WindowDockTileInvalidator.updateDockTile(). This calls NSDockTile.display() which sends a synchronous mach_msg to the Dock server. If the Dock server is busy, the main thread blocks for 2+ seconds.

4. No debouncing

unreadCount is incremented per-message in a loop (line 112: unreadCount += 1 inside for msg in messages). Multiple increments trigger multiple view invalidations in rapid succession. No debouncing or batching.

5. Polling regardless of app state

The 120-second timer fires regardless of whether:

• User has the app focused
• Window is visible
• New messages actually exist

Proposed Fix

1. Batch unreadCount updates — set final count once after processing all messages, not per-message increment
2. Debounce view updates — use Combine .debounce(for: 0.5) on the publisher or move to explicit notification rather than @published
3. Move dock tile update off main thread — dispatch NSDockTile.display() asynchronously or use NSApp.dockTile.badgeLabel (lighter weight)
4. Pause polling when app is backgrounded — only poll when NSApp.isActive
5. Decouple SidebarView from CrispManager — SidebarView doesn't need to observe all CrispManager state, only the badge count. Use a derived lightweight binding instead of @ObservedObject on the entire manager

Key Files

• desktop/Desktop/Sources/MainWindow/CrispManager.swift — lines 42-68 (timer), 95-112 (unread update)
• desktop/Desktop/Sources/MainWindow/SidebarView.swift — line 83 (@ObservedObject)
• desktop/Desktop/Sources/MainWindow/DesktopHomeView.swift — SidebarView embedding
• desktop/Desktop/Sources/MainWindow/HelpPage.swift — lines 8-11 (isViewingHelp toggle)

by AI for @beastoin