Clarify fuel savings comparison labels

Shared/FuelSavings.swift

@@ -143,6 +143,13 @@ enum FuelSavingsFormat {
             : "\(distanceText) extra return travel"
     }
 
+    /// Compact comparison copy kept outside the coloured verdict capsule.
+    /// "Nearest" refers to the existing shortest-journey baseline selection;
+    /// it does not claim a straight-line comparison.
+    static func comparisonLabel(status: FuelSavingsStatus) -> String {
+        status == .baseline ? "your baseline" : "vs nearest station"
+    }
+
     /// VoiceOver form of `extraTravelLabel`. The abbreviation and the unit suffix
     /// are spoken as words ("Approximately 6.4 miles extra return travel") because
     /// synthesizers render "Approx." and "mi" inconsistently.

Shared/FuelStore.swift

@@ -183,13 +183,13 @@ enum DistanceUnit: String, Codable, CaseIterable, Identifiable {
     /// shown in this unit, rounded to a whole number for picker labels:
     /// 5 miles -> "5" (miles unit) or "8" (km unit).
     func displayMiles(_ miles: Int) -> Int {
-        Int(fromKM(Double(miles) * 1.60934).rounded())
+        Int(fromKM(Double(miles) * FuelSavingsCalculator.kilometresPerMile).rounded())
     }
 
     /// Convert a value expressed in this unit to km.
     func toKM(_ value: Double) -> Double {
         switch self {
-        case .miles: return value * 1.60934
+        case .miles: return value * FuelSavingsCalculator.kilometresPerMile
         case .kilometers: return value
         }
     }
@@ -197,7 +197,7 @@ enum DistanceUnit: String, Codable, CaseIterable, Identifiable {
     /// Convert a km value to this unit.
     func fromKM(_ km: Double) -> Double {
         switch self {
-        case .miles: return km * 0.621371
+        case .miles: return km / FuelSavingsCalculator.kilometresPerMile
         case .kilometers: return km
         }
     }
@@ -979,7 +979,7 @@ struct FuelStore {
 
     /// "Follow search" caps the geofence at 8 miles so a 10/15-mile Stations
     /// search never creates huge region-monitoring circles.
-    static let alertFollowCapKM: Double = 8 * 1.60934
+    static let alertFollowCapKM: Double = 8 * FuelSavingsCalculator.kilometresPerMile
 
     /// The effective alert radius: the manual radius, or — when alerts follow
     /// the Stations-tab search — that distance (miles, converted via the
@@ -1618,10 +1618,22 @@ struct FuelStore {
         // what the rows show.
         if accurateDistancesEnabled,
            accurateDistancesReady(userLat: userLat, userLng: userLng),
-           let meters = roadDistanceMeters(for: station, userLat: userLat, userLng: userLng) {
-            return StationDistanceDisplay(km: meters / 1000.0, isApproximate: false)
+           let entry = roadDistanceEntry(for: station, userLat: userLat, userLng: userLng) {
+            let returnKM = (entry.meters + (entry.returnMeters ?? entry.meters)) / 1000.0
+            return StationDistanceDisplay(
+                km: entry.meters / 1000.0,
+                isApproximate: false,
+                returnKM: returnKM,
+                returnIsApproximate: entry.returnMeters == nil
+            )
         }
-        return StationDistanceDisplay(km: station.distanceKM(to: userLat, lng2: userLng), isApproximate: true)
+        let km = station.distanceKM(to: userLat, lng2: userLng)
+        return StationDistanceDisplay(
+            km: km,
+            isApproximate: true,
+            returnKM: km * 2,
+            returnIsApproximate: true
+        )
     }
 
     /// Radius test on the SAME distance the UI shows. Filtering straight-line
@@ -1710,35 +1722,50 @@ struct RoadDistanceDiagnostics: Equatable {
 /// road distance or the straight-line fallback. The confidence travels WITH the
 /// value, so a label can never claim a confidence the figure doesn't have.
 struct StationDistanceDisplay: Equatable {
-    let km: Double
-    let isApproximate: Bool
+let km: Double
+let isApproximate: Bool
+let returnKM: Double
+let returnIsApproximate: Bool
 
-    /// Row/sheet label: a straight-line fallback is marked "Approx." so a figure
-    /// that is NOT a routed road distance can never be read as one, and a cached
-    /// road distance stays a bare figure. It updates by itself once routing lands,
-    /// because `FuelStore.stationDistanceDisplay` re-reads the cache every call.
-    func label(unit: DistanceUnit) -> String {
-        let text = unit.format(km)
-        return isApproximate ? "Approx. \(text)" : text
-    }
+init(km: Double,
+     isApproximate: Bool,
+     returnKM: Double? = nil,
+     returnIsApproximate: Bool? = nil) {
+    self.km = km
+    self.isApproximate = isApproximate
+    self.returnKM = returnKM ?? km * 2
+    self.returnIsApproximate = returnIsApproximate ?? isApproximate
+}
 
-    /// Row/sheet label that keeps the one-way station distance primary, then
-    /// adds the out-and-back distance in brackets. This matches Best Value's
-    /// "extra return travel" basis without changing the actual distance model.
-    func labelWithReturn(unit: DistanceUnit) -> String {
-        "\(label(unit: unit)) (\(unit.format(km * 2)) return)"
-    }
+/// Row/sheet label: a straight-line fallback is marked "Approx." so a figure
+/// that is NOT a routed road distance can never be read as one, and a cached
+/// road distance stays a bare figure. It updates by itself once routing lands,
+/// because `FuelStore.stationDistanceDisplay` re-reads the cache every call.
+func label(unit: DistanceUnit) -> String {
+    let text = unit.format(km)
+    return isApproximate ? "Approx. \(text)" : text
+}
 
-    /// VoiceOver form of `label(unit:)`.
-    func spokenLabel(unit: DistanceUnit) -> String {
-        let text = unit.spoken(km)
-        return isApproximate ? "Approximately \(text)" : text
-    }
+/// Row/sheet label that keeps the one-way station distance primary, then
+/// adds the independently measured or estimated out-and-back distance.
+func labelWithReturn(unit: DistanceUnit) -> String {
+    let returnText = unit.format(returnKM)
+    let returnLabel = returnIsApproximate ? "Approx. \(returnText)" : returnText
+    return "\(label(unit: unit)) (\(returnLabel) return)"
+}
 
-    /// VoiceOver form of `labelWithReturn(unit:)`.
-    func spokenLabelWithReturn(unit: DistanceUnit) -> String {
-        "\(spokenLabel(unit: unit)), \(unit.spoken(km * 2)) return"
-    }
+/// VoiceOver form of `label(unit:)`.
+func spokenLabel(unit: DistanceUnit) -> String {
+    let text = unit.spoken(km)
+    return isApproximate ? "Approximately \(text)" : text
+}
+
+/// VoiceOver form of `labelWithReturn(unit:)`.
+func spokenLabelWithReturn(unit: DistanceUnit) -> String {
+    let returnText = unit.spoken(returnKM)
+    let returnLabel = returnIsApproximate ? "Approximately \(returnText)" : returnText
+    return "\(spokenLabel(unit: unit)), \(returnLabel) return"
+}
 }
 
 /// Cached Apple-Maps road distances for nearby stations (see

Shared/SiriCheapestLookup.swift

@@ -21,7 +21,7 @@ enum SiriCheapestLookup {
         lng: Double,
         withinMiles: Double
     ) -> FuelStation? {
-        let radiusKM = withinMiles * 1.60934
+        let radiusKM = withinMiles * FuelSavingsCalculator.kilometresPerMile
         // Same radius rule as the app list: the distance the answer would SHOW
         // (cached road route where there is one).
         return stations