Onboarding: prompts fire on forward-leave of their page, not arrival

b634c06 fired on page arrival, so swiping stacked Location + Notifications
before a screen was read. Now each permission fires only when the user
ADVANCES PAST its page (swipe forward or Continue) — the screen has been
read by then. Forward-only (swiping back never fires), idempotent
(already-determined → status refresh), so replay and auto-advance stay
clean. Continue buttons are now pure navigation; denied paths unchanged.

FuelBoard/OnboardingView.swift

@@ -54,15 +54,17 @@ struct OnboardingView: View {
         .onChange(of: prompter.notificationsGranted) { _, granted in
             if granted, page == 2 { page = 3 }
         }
-        // Fire the permission the moment its page comes into view — swiping
+        // Fire each permission when the user LEAVES its page by advancing
-        // must trigger the prompt exactly like tapping Continue does. Both
+        // forward (swipe or Continue) — by then the screen has been read.
-        // request methods are idempotent: an already-determined permission
+        // Never on arrival: a fast swipe can't stack prompts before a page
-        // just refreshes the status (no duplicate system alert), so this is
+        // is seen. Forward-only: swiping back never fires. Idempotent —
-        // safe for replay and for the auto-advance path.
+        // an already-determined permission just refreshes, so the
-        .onChange(of: page) { _, newPage in
+        // auto-advance path and replays stay clean (no duplicate alerts).
-            if newPage == 1 {
+        .onChange(of: page) { oldPage, newPage in
+            guard newPage > oldPage else { return }
+            if oldPage == 1 {
                 prompter.requestLocation()
-            } else if newPage == 2 {
+            } else if oldPage == 2 {
                 prompter.requestNotifications()
             }
         }
@@ -246,12 +248,10 @@ struct OnboardingView: View {
             ) {
                 if prompter.locationDenied {
                     openSettings()
-                } else if !prompter.locationGranted {
-                    // Safety net — the prompt already fired when this page
-                    // came into view (see onChange(of: page)); re-requesting
-                    // is a no-op unless the status is still undetermined.
-                    prompter.requestLocation()
                 } else {
+                    // The prompt fires on LEAVING this page (onChange(of:
+                    // page), forward advance only) — the description is on
+                    // screen until the user moves on.
                     page = 2
                 }
             }
@@ -259,13 +259,8 @@ struct OnboardingView: View {
             primaryButton(
                 prompter.notificationsDenied ? "Continue without alerts" : (prompter.notificationsGranted ? "Continue" : "Allow Notifications")
             ) {
-                if prompter.notificationsDenied {
+                // Prompt fires on leaving this page (same rule as Location).
                 page = 3
-                } else if !prompter.notificationsGranted {
-                    prompter.requestNotifications()
-                } else {
-                    page = 3
-                }
             }
         case 3:
             // No permission on this page — prices need none. Straight on.