refactor(tracking): tighten sf_tracking package

- Lazy-init sfTracking to avoid touching Firebase at import time
- DRY SfTrackingRepository with a single _broadcast helper
- Drop empty DashboardTracking, fix double step_completed in device_setup
- Move yearsBetween to packages/utils
- Add 5 unit tests for SfTrackingRepository
- Strip noisy comments from mixins and view models

modules/legacy/modules/customer_service/lib/src/presentation/state/contact_view_model.dart

@@ -126,7 +126,7 @@ class ContactViewModel extends Notifier<ContactViewState> {
     unawaited(
       _tracking.legacySupportContactInitiated(
         channel: 'email',
-        country: country,
+        country: country.isEmpty ? 'unknown' : country,
       ),
     );
 

modules/legacy/modules/device_management/lib/src/features/volume_control/presentation/state/volume_control_view_model.dart

@@ -53,9 +53,6 @@ class VolumeControlViewModel extends Notifier<VolumeControlViewState> {
     final device = state.device;
     if (device == null) return;
 
-    // Capture which volume types actually changed compared to the device's
-    // previous settings, so we only emit analytics for the ones the user
-    // actually moved.
     final previous = device.settings.volume;
     final mediaChanged = previous.media != state.media;
     final ringtoneChanged = previous.ringtone != state.ringtone;

modules/legacy/modules/legacy_auth/lib/src/features/device_setup/presentation/state/device_setup_view_model.dart

@@ -10,6 +10,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:sf_localizations/sf_localizations.dart';
 import 'package:sf_tracking/sf_tracking.dart';
+import 'package:utils/utils.dart';
 
 final legacyDeviceSetupViewModelProvider =
     NotifierProvider<LegacyDeviceSetupViewModel, LegacyDeviceSetupViewState>(
@@ -28,10 +29,7 @@ class LegacyDeviceSetupViewModel extends Notifier<LegacyDeviceSetupViewState> {
   late final TextEditingController watchCodeController;
   late final TextEditingController activationKeyController;
 
-  /// When the user entered the current step. Used to compute how long they
-  /// spent on each step and fire `step_completed` with a `duration_seconds`
-  /// param — super useful for marketing/UX to see where users get stuck.
-  DateTime _currentStepEnteredAt = DateTime.now();
+  DateTime? _currentStepEnteredAt;
 
   @override
   LegacyDeviceSetupViewState build() {
@@ -48,10 +46,10 @@ class LegacyDeviceSetupViewModel extends Notifier<LegacyDeviceSetupViewState> {
     return initial;
   }
 
-  /// Emits a `step_completed` event for the step the user is LEAVING and
-  /// resets the step timer so the next step starts fresh.
   void _completeCurrentStep(String stepName) {
-    final duration = DateTime.now().difference(_currentStepEnteredAt).inSeconds;
+    final enteredAt = _currentStepEnteredAt;
+    if (enteredAt == null) return;
+    final duration = DateTime.now().difference(enteredAt).inSeconds;
     unawaited(
       _tracking.legacyDeviceSetupStepCompleted(
         step: stepName,
@@ -104,8 +102,6 @@ class LegacyDeviceSetupViewModel extends Notifier<LegacyDeviceSetupViewState> {
           state = state.copyWith(errorMessage: I18n.errorScanWatchRequired);
           return;
         }
-        // Distinguish QR vs manual code entry: if watchCode is populated and
-        // watchQr is empty, the user typed it manually.
         if (state.watchCode.isNotEmpty && state.watchQr.isEmpty) {
           unawaited(_tracking.legacyDeviceSetupManualCodeEntered());
         }
@@ -158,8 +154,6 @@ class LegacyDeviceSetupViewModel extends Notifier<LegacyDeviceSetupViewState> {
 
   void onWatchQrScanned(String qr) {
     unawaited(_tracking.legacyDeviceSetupQrScanned());
-    // The QR scan jumps directly from scan_watch to profile, so complete
-    // the scan_watch step with its timer too.
     _completeCurrentStep('scan_watch');
     state = state.copyWith(watchQr: qr, step: LegacyAddKidStep.profile);
   }
@@ -201,20 +195,11 @@ class LegacyDeviceSetupViewModel extends Notifier<LegacyDeviceSetupViewState> {
 
       if (!ref.mounted) return false;
 
-      final now = DateTime.now();
-      final ageYears =
-          now.year -
-          birth.year -
-          ((now.month < birth.month ||
-                  (now.month == birth.month && now.day < birth.day))
-              ? 1
-              : 0);
-
       unawaited(
         _tracking.legacyDeviceSetupCompleted(
           childGender: genrer,
           relationType: relationType,
-          childAgeYears: ageYears,
+          childAgeYears: yearsBetween(birth, DateTime.now()),
         ),
       );
 

modules/legacy/modules/location/lib/src/features/location/presentation/state/location_map_view_model.dart

@@ -16,9 +16,6 @@ final locationMapViewModelProvider =
 class LocationMapViewModel extends Notifier<LocationMapViewState> {
   late final SfTrackingRepository _tracking;
 
-  /// Debounce timer for map zoom tracking. We do NOT want to fire an event
-  /// for every zoom delta during a pinch gesture; we wait until the user
-  /// stops zooming for a brief moment and then log the final zoom level.
   Timer? _zoomDebounce;
   static const Duration _zoomDebounceDelay = Duration(seconds: 1);
 
@@ -29,8 +26,6 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
     return const LocationMapViewState();
   }
 
-  // ─── Layer toggles ─────────────────────────────────────────────────────
-
   void toggleGeofences() {
     final newVisible = !state.showGeofences;
     unawaited(_tracking.legacyLocationMapGeofencesToggled(newVisible));
@@ -43,29 +38,18 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
     state = state.copyWith(showFrequentPlaces: newVisible);
   }
 
-  // ─── Place creation funnel ────────────────────────────────────────────
-
   void startPlacing(PlacingMode mode) {
     unawaited(_tracking.legacyLocationPlaceCreationStarted(_modeName(mode)));
     state = state.copyWith(placingMode: mode);
   }
 
   void cancelPlacing() {
-    // Infer mode + step from current state BEFORE we reset it so we can
-    // send meaningful funnel drop-off data to analytics.
-    final wasPicking = state.placingMode != PlacingMode.none;
-    final wasAdjustingRadius = state.adjustingRadius;
-
-    if (wasPicking || wasAdjustingRadius) {
-      final mode = wasPicking
-          ? _modeName(state.placingMode)
-          // Only geofences reach the radius-adjust step.
-          : 'geofence';
-      final atStep = wasPicking ? 'picking_point' : 'adjusting_radius';
+    final cancellation = _inferCancellationContext();
+    if (cancellation != null) {
       unawaited(
         _tracking.legacyLocationPlaceCreationCancelled(
-          mode: mode,
-          atStep: atStep,
+          mode: cancellation.mode,
+          atStep: cancellation.atStep,
         ),
       );
     }
@@ -77,6 +61,16 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
     );
   }
 
+  _CancellationContext? _inferCancellationContext() {
+    final isPicking = state.placingMode != PlacingMode.none;
+    final isAdjustingRadius = state.adjustingRadius;
+    if (!isPicking && !isAdjustingRadius) return null;
+
+    final mode = isPicking ? _modeName(state.placingMode) : 'geofence';
+    final atStep = isPicking ? 'picking_point' : 'adjusting_radius';
+    return _CancellationContext(mode: mode, atStep: atStep);
+  }
+
   void confirmGeofencePlacement(LatLng center) {
     unawaited(_tracking.legacyLocationPointConfirmed('geofence'));
     state = state.copyWith(
@@ -93,8 +87,6 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
   }
 
   void updatePreviewRadius(double radius) {
-    // Intentionally NOT tracked: this fires on every slider tick. The final
-    // radius is captured in [confirmRadius] once the user settles.
     state = state.copyWith(previewRadius: radius);
   }
 
@@ -113,8 +105,6 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
     state = state.copyWith(previewPoint: null);
   }
 
-  // ─── Exploration / selection ──────────────────────────────────────────
-
   void selectGeofence(GeofenceEntity geofence) {
     unawaited(_tracking.legacyLocationGeofenceSelected());
     state = state.copyWith(
@@ -168,8 +158,6 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
     state = state.copyWith(selectedHistoryPosition: null);
   }
 
-  // ─── Live tracking ────────────────────────────────────────────────────
-
   void toggleFollowing() {
     final newFollowing = !state.isFollowing;
     unawaited(_tracking.legacyLocationFollowingToggled(newFollowing));
@@ -177,16 +165,12 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
   }
 
   void stopFollowing() {
-    // Called automatically when the user pans the map manually. We track
-    // this as a "following disabled" event for consistency with toggle.
     if (state.isFollowing) {
       unawaited(_tracking.legacyLocationFollowingToggled(false));
     }
     state = state.copyWith(isFollowing: false);
   }
 
-  // ─── UI chrome ────────────────────────────────────────────────────────
-
   void toggleActionsExpanded() {
     final newExpanded = !state.actionsExpanded;
     unawaited(_tracking.legacyLocationMapActionsExpanded(newExpanded));
@@ -201,22 +185,14 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
     state = state.copyWith(frequencyExpanded: false);
   }
 
-  // ─── Map zoom (debounced) ─────────────────────────────────────────────
-
   void updateMapZoom(double zoom) {
     state = state.copyWith(mapZoom: zoom);
-
-    // Debounce: cancel any pending fire and schedule a new one. If the user
-    // keeps zooming, the timer keeps resetting and we only fire once the
-    // zoom settles for [_zoomDebounceDelay].
     _zoomDebounce?.cancel();
     _zoomDebounce = Timer(_zoomDebounceDelay, () {
       unawaited(_tracking.legacyLocationMapZoomed(zoom));
     });
   }
 
-  // ─── Helpers ──────────────────────────────────────────────────────────
-
   String _modeName(PlacingMode mode) {
     switch (mode) {
       case PlacingMode.geofence:
@@ -228,3 +204,9 @@ class LocationMapViewModel extends Notifier<LocationMapViewState> {
     }
   }
 }
+
+class _CancellationContext {
+  const _CancellationContext({required this.mode, required this.atStep});
+  final String mode;
+  final String atStep;
+}