Sources/UI/Alerts/AlertsView.swift

@@ -4,8 +4,9 @@ import SwiftUI
 
 /// Sidebar tab showing currently breached thresholds and the in-app
 /// alert history log maintained by `AlertEngine`.
+@MainActor
 public struct AlertsView: View {
-    @State private var engine = AlertEngine.shared
+    @ObservedObject private var engine = AlertEngine.shared
 
     public init() {}
 

Sources/UI/ContentView.swift

@@ -1,5 +1,6 @@
 import SwiftUI
 
+@MainActor
 public struct ContentView: View {
     @StateObject private var store = SystemTelemetryStore.shared
     @State private var selectedTab: String? = "Dashboard"
@@ -1220,6 +1221,7 @@ public struct ContentView: View {
 }
 
 // MARK: - Process Detail Inspector Sheet
+@MainActor
 struct ProcessDetailSheet: View {
     let inspector: MMProcessDetailInspector
     let pid: Int32

Sources/UI/MenuBar/QuickGlancePopoverView.swift

@@ -1,7 +1,8 @@
 import SwiftUI
 
+@MainActor
 public struct QuickGlancePopoverView: View {
-    var store: SystemTelemetryStore
+    @ObservedObject var store: SystemTelemetryStore
     
     public init(store: SystemTelemetryStore) {
         self.store = store

Sources/UI/Settings/AlertsSettingsView.swift

@@ -5,6 +5,7 @@ import UserNotifications
 
 /// Preferences UI for threshold alert rules. Bound directly to
 /// `AlertEngine.shared.configuration`, which auto-persists to `UserDefaults`.
+@MainActor
 public struct AlertsSettingsView: View {
     @ObservedObject private var engine = AlertEngine.shared
     @State private var authorizationStatus: UNAuthorizationStatus = .notDetermined

Tests/MMMenuBarTests.swift

@@ -2,6 +2,7 @@ import XCTest
 import SwiftUI
 @testable import MacMonitor
 
+@MainActor
 final class MMMenuBarTests: XCTestCase {
     
     func testMenuBarStatusViewInitialization() {