Add (E10)/(E5) bracket labels to Unleaded/Premium in picker and descriptions

FuelBoard/StationsView.swift

@@ -47,7 +47,7 @@ struct StationsView: View {
                 Section("Fuel type") {
                     Picker("Fuel type", selection: $selectedFuel) {
                         ForEach(FuelType.allCases) { fuel in
-                            Text(fuel.displayName).tag(fuel)
+                            Text(fuel.shortName).tag(fuel)
                         }
                     }
                     .pickerStyle(.segmented)
@@ -180,7 +180,36 @@ struct StationsView: View {
                 // New fetch or filter switch → back to the first page.
                 visibleCount = pageSize
             }
+            // Native large-title behaviour (Mail-style): the system shows the
+            // large title at rest, scrolls it away and fades the compact
+            // inline title in. No custom toolbar needed — the native mechanism
+            // only renders text, which is exactly what we want here.
             .navigationTitle("FuelBoard")
+            .navigationBarTitleDisplayMode(.large)
+        }
+    }
+}
+
+// MARK: - Fuel-type iconography (app target only — FuelStore.swift is Foundation-only)
+
+extension FuelType {
+    /// Short segment label ("Unleaded (E10)" / "Premium (E5)" / "Diesel") for
+    /// the picker and description.
+    var shortName: String {
+        switch self {
+        case .e10: return "Unleaded (E10)"
+        case .e5: return "Premium (E5)"
+        case .diesel: return "Diesel"
+        }
+    }
+
+    /// Pump-handle colour convention (UK): green = unleaded, blue = premium,
+    /// dark grey = diesel. Used for the fuel-type tab icons and the title icon.
+    var tintColor: Color {
+        switch self {
+        case .e10: return .green
+        case .e5: return .blue
+        case .diesel: return Color(red: 0.35, green: 0.38, blue: 0.42)
         }
     }
 }

Shared/FuelPriceProvider.swift

@@ -84,11 +84,15 @@ private struct RelayResponse: Codable {
         let prices: [String: Double]?
 
         /// Map relay grade keys (E5/E10/DIESEL) to FuelType for ALL fuels the
-        /// station sells — one fetch populates every fuel tab.
+        /// station sells — one fetch populates every fuel tab. Defensive guard:
+        /// any grade outside the 50–500 pence/litre band is dropped, so a relay
+        /// regression (e.g. the band being removed server-side) can't re-poison
+        /// the nationwide cheapest reference with 1.3p / 1589p garbage.
         var allPrices: [FuelType: Double] {
             var result: [FuelType: Double] = [:]
             if let prices {
                 for (grade, value) in prices {
+                    guard (50...500).contains(value) else { continue }
                     switch grade.uppercased() {
                     case "E10": result[.e10] = value
                     case "E5": result[.e5] = value
@@ -98,7 +102,7 @@ private struct RelayResponse: Codable {
                 }
             }
             // Backwards-compat: relay versions without `prices` still send `price`.
-            if result.isEmpty, let price {
+            if result.isEmpty, let price, (50...500).contains(price) {
                 result[.e10] = price
             }
             return result

Shared/FuelStore.swift

@@ -56,8 +56,8 @@ enum FuelType: String, Codable, CaseIterable, Identifiable {
 
     var displayName: String {
         switch self {
-        case .e10: return "E10 Unleaded"
+        case .e10: return "Unleaded (E10)"
-        case .e5: return "E5 Premium"
+        case .e5: return "Premium (E5)"
         case .diesel: return "Diesel"
         }
     }