Scope cheapest/RAG/TOP to alert trigger radius in app + widget; header shows 'within X km'; falls back to full fetch when radius pool empty

FuelBoard/ContentView.swift

@@ -21,8 +21,20 @@ struct ContentView: View {
     @State private var locationManager = LocationManager()
     @StateObject private var monitor = ProximityMonitor()
 
+    /// Stations within the alert trigger radius of the current location, used
+    /// as the pool for "cheapest" (RAG reference, TOP, sorting). Falls back to
+    /// the full fetch when location is unknown or the radius pool is empty
+    /// (rural areas) so the list is never blank.
+    private var radiusScopedStations: [FuelStation] {
+        guard let location else { return stations }
+        let within = stations.filter {
+            $0.distanceKM(to: location.lat, lng2: location.lng) <= alertsRadius
+        }
+        return within.isEmpty ? stations : within
+    }
+
     private var cheapestPrice: Double? {
-        stations.compactMap { $0.prices[selectedFuel] }.min()
+        radiusScopedStations.compactMap { $0.prices[selectedFuel] }.min()
     }
 
     private var displayedStations: [FuelStation] {
@@ -30,7 +42,7 @@ struct ContentView: View {
     }
 
     private var sortedStations: [FuelStation] {
-        let available = stations.filter { $0.prices[selectedFuel] != nil }
+        let available = radiusScopedStations.filter { $0.prices[selectedFuel] != nil }
         switch sortMode {
         case .closest:
             guard let location else { return available.sorted { $0.prices[selectedFuel]! < $1.prices[selectedFuel]! } }
@@ -73,6 +85,7 @@ struct ContentView: View {
                 stationLimit: $stationLimit,
                 cheapestPrice: cheapestPrice,
                 location: location,
+                radiusKM: alertsRadius,
                 favouriteIDs: favouriteIDs,
                 onToggleFavourite: toggleFavourite
             )