Use native onScrollGeometryChange (iOS 18) so the compact icon+title bar actually appears on scroll, Mail-style

FuelBoard/StationsView.swift

@@ -30,8 +30,8 @@ struct StationsView: View {
         NavigationStack {
             List {
                 // Large title header (icon + title). Native navigation titles
-                // can't carry an icon, so this is a real row; the scroll
-                // tracker rides on its background so no extra row is created.
+                // can't carry an icon, so this is a real row at the top of the
+                // list; it scrolls away like Mail's large title.
                 HStack(spacing: 10) {
                     Image(systemName: "fuelpump.fill")
                         .font(.system(size: 34))
@@ -44,14 +44,6 @@ struct StationsView: View {
                 .listRowSeparator(.hidden)
                 .listRowInsets(EdgeInsets(top: 0, leading: 16, bottom: 0, trailing: 16))
                 .listRowBackground(Color.clear)
-                .background(
-                    GeometryReader { proxy in
-                        Color.clear.preference(
-                            key: ScrollOffsetKey.self,
-                            value: proxy.frame(in: .named("stationsScroll")).minY
-                        )
-                    }
-                )
 
                 Section {
                     if let location {
@@ -207,10 +199,7 @@ struct StationsView: View {
                 // New fetch or filter switch → back to the first page.
                 visibleCount = pageSize
             }
-            .coordinateSpace(name: "stationsScroll")
-            .onPreferenceChange(ScrollOffsetKey.self) { minY in
-                isScrolled = minY < -60
-            }
+            .modifier(ScrolledTracker(isScrolled: $isScrolled))
             .toolbar {
                 ToolbarItem(placement: .principal) {
                     if isScrolled {
@@ -231,13 +220,26 @@ struct StationsView: View {
 
 // MARK: - Fuel-type iconography (app target only — FuelStore.swift is Foundation-only)
 
-/// Scroll offset preference — the large-title header row reports its position
-/// in the list's coordinate space so we know when it has scrolled under the
-/// nav bar (minY < -60) and can show the compact gas-pump+title bar.
-private struct ScrollOffsetKey: PreferenceKey {
-    static var defaultValue: CGFloat = 0
-    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
-        value = nextValue()
+/// Tracks whether the list has scrolled, using the native scroll-geometry API
+/// (iOS 18+) — the reliable way to know when the large header title has
+/// collapsed. (The old GeometryReader-preference approach didn't fire in List,
+/// which is why the compact bar never appeared.)
+private struct ScrolledTracker: ViewModifier {
+    @Binding var isScrolled: Bool
+
+    func body(content: Content) -> some View {
+        if #available(iOS 18.0, *) {
+            content
+                .onScrollGeometryChange(for: Bool.self) { geometry in
+                    geometry.contentOffset.y > 40
+                } action: { _, scrolled in
+                    withAnimation(.easeInOut(duration: 0.2)) {
+                        isScrolled = scrolled
+                    }
+                }
+        } else {
+            content
+        }
     }
 }