ProdDash Viewer 1.0.0: a Mac app that only shows ProdDash, with a tab per installation

A new Apple-silicon app in viewer/macos (Swift, no dependencies, ~1 MB): one
window showing a ProdDash dashboard in WebKit, and nothing else. It runs no
server; it points at any ProdDash on the network.

- Connections (name + address) in Settings; the add/edit sheet asks
  /api/modules whether ProdDash answers as you type. No port means 24500.
- Two or more connections bring a slim tab bar of their names. In a window
  it floats over the dashboard and comes out while the pointer is on the
  title bar; it is not part of the title bar, because anything there makes
  WebKit push the page down. In full screen it is a titlebar accessory that
  comes down with the menu bar, and it flashes up after each switch.
  ⌃Tab / ⌃⇧Tab and ⌘1–9 switch from the keyboard.
- Full screen, reopening in full screen if it quit there; window size and
  the selected tab are kept too. The dashboard's own full-screen button
  works as well.
- Menus: View (Back, Forward, Reload Page, Enter Full Screen), Settings,
  Edit (copy/paste in the page's text fields), Window, Help (a guide that
  ships in the app).
- Every installation keeps its own live web view. One that can't be
  reached says why and retries at 2, 4, 8, then every 15 s; a redirect off
  the installation is reported, not handed to the browser. JS alert,
  confirm and prompt show as sheets; links to other sites open in the
  browser.
- General settings: open at login (SMAppService), keep the display awake
  while a dashboard is on screen (default on).

build.sh signs with the Developer ID when one is installed and makes a
notarised DMG with --notarize, as the launcher's does. It needs Xcode: with
only the command line tools the macOS 27 SDK can't expand SwiftUI's @State.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

viewer/macos/Sources/ViewerSettings.swift

@@ -0,0 +1,61 @@
+import Foundation
+import ServiceManagement
+
+/// The viewer's own preferences. The connections themselves are in
+/// ConnectionStore.
+final class ViewerSettings: ObservableObject {
+
+    static let shared = ViewerSettings()
+    private let defaults = UserDefaults.standard
+
+    /// Keep the display on while a dashboard is on screen — a booth display
+    /// that dims halfway through a service is the failure this is here for.
+    @Published var keepDisplayAwake: Bool {
+        didSet { defaults.set(keepDisplayAwake, forKey: "keepDisplayAwake") }
+    }
+
+    private init() {
+        defaults.register(defaults: ["keepDisplayAwake": true])
+        keepDisplayAwake = defaults.bool(forKey: "keepDisplayAwake")
+    }
+
+    /// The window was in full screen when the viewer last quit, so it opens in
+    /// full screen again — a booth Mac that restarts comes back as it was left.
+    var reopenInFullScreen: Bool {
+        get { defaults.bool(forKey: "reopenInFullScreen") }
+        set { defaults.set(newValue, forKey: "reopenInFullScreen") }
+    }
+
+    /// The tab that was showing, so the viewer reopens on it.
+    var selectedConnection: UUID? {
+        get { defaults.string(forKey: "selectedConnection").flatMap(UUID.init(uuidString:)) }
+        set { defaults.set(newValue?.uuidString, forKey: "selectedConnection") }
+    }
+}
+
+/// "Open at login", through the macOS 13 login-item API. The operator may
+/// still have to approve it in System Settings — hence `needsApproval`, which
+/// Settings shows rather than failing silently.
+enum LoginItem {
+
+    static var isEnabled: Bool { SMAppService.mainApp.status == .enabled }
+    static var needsApproval: Bool { SMAppService.mainApp.status == .requiresApproval }
+
+    /// Nil when it worked; otherwise what went wrong, for Settings to show.
+    static func set(_ enabled: Bool) -> String? {
+        do {
+            if enabled {
+                if SMAppService.mainApp.status != .enabled { try SMAppService.mainApp.register() }
+            } else {
+                if SMAppService.mainApp.status != .notRegistered { try SMAppService.mainApp.unregister() }
+            }
+            return nil
+        } catch {
+            return error.localizedDescription
+        }
+    }
+
+    static func openSystemSettings() {
+        SMAppService.openSystemSettingsLoginItems()
+    }
+}