fix: keep live activity in sync with motion

FuelBoard/ContentView.swift

@@ -32,6 +32,24 @@ struct ContentView: View {
     private var effectiveAlertsRadiusKM: Double {
         FuelStore.effectiveAlertsRadiusKM(followsSearch: alertsFollowsSearch, manualKM: alertsRadius)
     }
+
+    private func installLocationUpdateHook() {
+        locationManager.onLocationUpdate = { [weak monitor] in
+            monitor?.update(stations: stations, favourites: refreshedFavourites,
+                            fuel: alertsFuel, radiusKM: effectiveAlertsRadiusKM)
+            // The Live Activity follows the same wake-ups — this hook
+            // fires on every fix incl. background significant-change
+            // wake-ups, so the Lock Screen pill stays live while driving.
+            updateLiveActivity()
+        }
+    }
+
+    private func ensureBackgroundMotionTrackingIfNeeded() {
+        if alertsEnabled || liveActivityEnabled {
+            locationManager.startBackgroundTracking()
+        }
+    }
+
     @State private var isLoading = false
     @State private var statusMessage = ""
     /// What data is on screen, driving which (if any) status banner shows
@@ -266,20 +284,12 @@ struct ContentView: View {
             if FuelStore.loadHasCompletedOnboarding()
                 || shouldSkipOnboarding {
                 locationManager.startForegroundTracking()
-                // Geofences must follow the user even in the background:
+                // Geofences and the Live Activity must follow the user even in
-                // wire the delegate hook (fires on every fix incl. background
+                // the background: wire the delegate hook (fires on every fix
-                // significant-change wake-ups) to re-register the region
+                // incl. background significant-change wake-ups) so SwiftUI's
-                // window around the new position. SwiftUI onChange alone
+                // foreground-only onChange isn't the only update path.
-                // never runs while suspended, so alerts would otherwise stay
+                installLocationUpdateHook()
-                // frozen around the last foreground fix.
+                ensureBackgroundMotionTrackingIfNeeded()
-                locationManager.onLocationUpdate = { [weak monitor] in
-                    monitor?.update(stations: stations, favourites: refreshedFavourites,
-                                    fuel: alertsFuel, radiusKM: effectiveAlertsRadiusKM)
-                    // The Live Activity follows the same wake-ups — this hook
-                    // fires on every fix incl. background significant-change
-                    // wake-ups, so the Lock Screen pill stays live while driving.
-                    updateLiveActivity()
-                }
                 monitor.update(stations: stations, favourites: refreshedFavourites,
                                fuel: alertsFuel, radiusKM: effectiveAlertsRadiusKM)
                 monitor.setEnabled(alertsEnabled)
@@ -310,6 +320,8 @@ struct ContentView: View {
             // empty on a brand-new install.
             if !showing, FuelStore.loadHasCompletedOnboarding() {
                 locationManager.startForegroundTracking()
+                installLocationUpdateHook()
+                ensureBackgroundMotionTrackingIfNeeded()
                 monitor.update(stations: stations, favourites: refreshedFavourites,
                                fuel: alertsFuel, radiusKM: effectiveAlertsRadiusKM)
                 updateLiveActivity()
@@ -373,9 +385,7 @@ struct ContentView: View {
             monitor.setEnabled(newValue)
             monitor.update(stations: stations, favourites: refreshedFavourites,
                            fuel: alertsFuel, radiusKM: effectiveAlertsRadiusKM)
-            if newValue {
+            ensureBackgroundMotionTrackingIfNeeded()
-                locationManager.startBackgroundTracking()
-            }
         }
         .onChange(of: alertsRadius) { _, newValue in
             FuelStore.saveAlertsRadius(newValue)
@@ -406,6 +416,7 @@ struct ContentView: View {
             // Toggling the Live Activity on starts it with the current best
             // station; toggling off ends any running activity.
             FuelStore.saveLiveActivityEnabled(newValue)
+            ensureBackgroundMotionTrackingIfNeeded()
             updateLiveActivity()
         }
         .onChange(of: liveActivityFuel) { _, newValue in