Refine trends and debug harness; clean up warnings

Shared/FuelStore.swift

@@ -9,6 +9,9 @@
 
 import Foundation
 import Security
+#if canImport(AppIntents)
+import AppIntents
+#endif
 import SwiftUI
 
 // MARK: - Fuel types
@@ -59,6 +62,18 @@ enum RAGRating: Int, Codable {
 }
 
 enum FuelType: String, Codable, CaseIterable, Identifiable {
+#if canImport(AppIntents)
+    typealias DisplayRepresentation = AppIntents.DisplayRepresentation
+    typealias TypeDisplayRepresentation = AppIntents.TypeDisplayRepresentation
+
+    static var typeDisplayRepresentation: TypeDisplayRepresentation = "Fuel"
+
+    static var caseDisplayRepresentations: [FuelType: DisplayRepresentation] = [
+        .e10: "Unleaded",
+        .e5: "Premium",
+        .diesel: "Diesel",
+    ]
+#endif
     case e10    // Unleaded (E10)
     case e5     // Premium (E5)
     case diesel // B7 diesel
@@ -74,6 +89,10 @@ enum FuelType: String, Codable, CaseIterable, Identifiable {
     }
 }
 
+#if canImport(AppIntents)
+extension FuelType: AppEnum {}
+#endif
+
 /// Display unit for all distances in the app + widget. Internally distances
 /// are always stored/computed in km; conversion happens at the display and
 /// filter boundary so nothing else needs to know the unit.
@@ -516,7 +535,7 @@ struct FuelStore {
             let whole = tenths / 1000
             let major = (tenths % 1000) / 10
             let minor = tenths % 10
-            let main = Text(String(format: "£%d.%02d", whole, major))
+            let amount = Text(String(format: "£%d.%02d", whole, major))
                 .font(base)
                 .foregroundColor(color)
             let sup = Text(String(superscriptDigits[minor]))
@@ -526,7 +545,7 @@ struct FuelStore {
             let perL = Text("/L")
                 .font(.system(size: size * 0.5, weight: .regular).monospaced())
                 .foregroundColor(color.opacity(0.55))
-            return main + sup + perL
+            return Text("\(amount)\(sup)\(perL)")
         }
     }
 
@@ -825,7 +844,7 @@ struct FuelStore {
     // MARK: Low-level keychain helpers
 
     private static func keychainData(service: String) -> Data? {
-        var query: [String: Any] = [
+        let query: [String: Any] = [
             kSecClass as String: kSecClassGenericPassword,
             kSecAttrService as String: service,
             kSecReturnData as String: true,