feat(client/analytics): GA4 funnel instrumentation + unified home CTA

Add Firebase Analytics (GA4) funnel tracking to client_app:
- AnalyticsService typed wrapper (enum-gated, no PII) + analyticsProvider
- FirebaseAnalyticsObserver on GoRouter (screen_name via nameExtractor)
- user_id = customer UUID, user_type property, set on auth resolve/upgrade
- funnel events: curhat_start, curhat_repeat_start, auth_*, onboarding_usp_view,
  payment_view, payment_method_select, payment_started, pairing_matched/no_bestie
- bottom-sheet events: verif_choice_view/select, bestie_choice_view/select,
  extension_offer_view, chat_extension_requested
- payment_started carries app_instance_id + ga_session_id in the
  /payment-requests body for future server-side stitching (backend ignores)
- curhat_mode_pick screen name disambiguates the chat/call mode picker
  (/payment/method-pick) from the payment-channel picker (/payment/method)
- unify both home CTAs to "Aku Mau Curhat"

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client_app/lib/features/auth/screens/display_name_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/api/api_client_provider.dart';
 import '../../../core/auth/auth_notifier.dart';
 import '../../../core/theme/halo_tokens.dart';
@@ -35,6 +36,9 @@ class _DisplayNameScreenState extends ConsumerState<DisplayNameScreen> {
       final data = next.valueOrNull;
       if (data is AuthAnonymousData && !_routedAfterLogin) {
         _routedAfterLogin = true;
+        // Anonymous identity established — activation step 6.
+        // ignore: discarded_futures
+        ref.read(analyticsProvider).logAuthComplete(AnalyticsUserType.anonymous);
         _proceedAfterLogin();
       }
     });
@@ -82,12 +86,17 @@ class _DisplayNameScreenState extends ConsumerState<DisplayNameScreen> {
       return;
     }
 
+    // ignore: discarded_futures
+    ref.read(analyticsProvider).logVerifChoiceView();
     final choice = await VerifChoiceSheet.show(context);
     if (!mounted || choice == null) {
-      // User dismissed the sheet — let them tap Lanjut again to retry.
+      // User dismissed the sheet — let them tap Lanjut again to retry. No
+      // select event: the view→select gap is the abandonment signal.
       _routedAfterLogin = false;
       return;
     }
+    // ignore: discarded_futures
+    ref.read(analyticsProvider).logVerifChoiceSelect(choice);
     if (!mounted) return;
     await routeForVerifChoice(context, ref, choice);
   }

client_app/lib/features/auth/screens/otp_screen.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/api/api_client_provider.dart';
 import '../../../core/auth/auth_notifier.dart';
 import '../../../core/constants.dart';
@@ -75,6 +76,14 @@ class _OtpScreenState extends ConsumerState<OtpScreen> {
         if (_errorMessage != null && mounted) {
           setState(() => _errorMessage = null);
         }
+        // OTP verify resolved to a real identity — activation/repeat step 6.
+        final data = next.valueOrNull;
+        if (data is AuthAuthenticatedData || data is AuthNeedsDisplayNameData) {
+          // ignore: discarded_futures
+          ref
+              .read(analyticsProvider)
+              .logAuthComplete(AnalyticsUserType.verified);
+        }
       }
     });
 
@@ -152,6 +161,8 @@ class _OtpScreenState extends ConsumerState<OtpScreen> {
     final code = _readCode();
     if (code.length == _kOtpLength && !_autoSubmitted && _otpRequestId != null) {
       _autoSubmitted = true;
+      // ignore: discarded_futures
+      ref.read(analyticsProvider).logAuthOtpSubmit();
       ref.read(authProvider.notifier).verifyOtp(_otpRequestId!, code);
     }
   }

client_app/lib/features/auth/screens/register_screen.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/auth/auth_notifier.dart';
 import '../../../core/constants.dart';
 import '../../../core/theme/halo_tokens.dart';
@@ -222,8 +223,15 @@ class _RegisterScreenState extends ConsumerState<RegisterScreen> {
                         : 'kirim kode',
                 fullWidth: true,
                 onPressed: canSubmit
-                    ? () =>
-                        ref.read(authProvider.notifier).requestOtp(_e164Phone())
+                    ? () {
+                        // ignore: discarded_futures
+                        ref
+                            .read(analyticsProvider)
+                            .logAuthStart(AnalyticsAuthMethod.phone);
+                        ref
+                            .read(authProvider.notifier)
+                            .requestOtp(_e164Phone());
+                      }
                     : null,
               ),
               if (!fromProfile) ...[

client_app/lib/features/chat/screens/bestie_found_screen.dart

@@ -1,9 +1,11 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/chat/active_session_notifier.dart';
 import '../../../core/pairing/pairing_notifier.dart';
 import '../../../core/theme/halo_tokens.dart';
+import '../../payment/state/payment_draft_provider.dart';
 import '../../../core/theme/widgets/widgets.dart';
 
 /// Phase 4 Stage 5 — S9 Match-found screen.
@@ -35,6 +37,15 @@ class _BestieFoundScreenState extends ConsumerState<BestieFoundScreen> {
   @override
   void initState() {
     super.initState();
+    // Funnel step 12 — paired with a mitra. A targeted-mitra draft means the
+    // repeat funnel; otherwise activation. Fire once on view.
+    final isRepeat =
+        ref.read(paymentDraftNotifierProvider).targetedMitraId != null;
+    // ignore: discarded_futures
+    ref.read(analyticsProvider).logPairingMatched(
+          funnel:
+              isRepeat ? AnalyticsFunnel.repeat : AnalyticsFunnel.activation,
+        );
     ref.listenManual<PairingData>(pairingProvider, (prev, next) {
       if (!mounted) return;
       if (next is PairingActiveData) {

client_app/lib/features/chat/screens/chat_screen.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/chat/active_session_notifier.dart';
 import '../../../core/chat/chat_notifier.dart';
 import '../../../core/chat/session_closure_notifier.dart';
@@ -512,6 +513,8 @@ class _TimerBanner extends ConsumerWidget {
       return _BannerKind.none;
     }));
     void onExtend() {
+      // ignore: discarded_futures
+      ref.read(analyticsProvider).logExtensionOfferView(sessionId: sessionId);
       PricingBottomSheet.showForExtension(
         context,
         sessionId: sessionId,

client_app/lib/features/chat/screens/no_bestie_screen.dart

@@ -1,7 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/pairing/pairing_notifier.dart';
+import '../../payment/state/payment_draft_provider.dart';
 
 /// Terminal failed-pairing screen.
 ///
@@ -13,11 +15,30 @@ import '../../../core/pairing/pairing_notifier.dart';
 /// Single CTA "Kembali ke beranda" resets the pairing notifier and routes
 /// home. PopScope falls back to home for deep-link entry per project memory
 /// rule "Deep-link pop fallback".
-class NoBestieScreen extends ConsumerWidget {
+class NoBestieScreen extends ConsumerStatefulWidget {
   const NoBestieScreen({super.key});
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<NoBestieScreen> createState() => _NoBestieScreenState();
+}
+
+class _NoBestieScreenState extends ConsumerState<NoBestieScreen> {
+  @override
+  void initState() {
+    super.initState();
+    // Funnel drop-off marker — pairing failed. A targeted-mitra draft means
+    // the repeat funnel; otherwise activation. Fire once on view.
+    final isRepeat =
+        ref.read(paymentDraftNotifierProvider).targetedMitraId != null;
+    // ignore: discarded_futures
+    ref.read(analyticsProvider).logPairingNoBestie(
+          funnel:
+              isRepeat ? AnalyticsFunnel.repeat : AnalyticsFunnel.activation,
+        );
+  }
+
+  @override
+  Widget build(BuildContext context) {
     return PopScope(
       canPop: true,
       onPopInvokedWithResult: (didPop, _) {

client_app/lib/features/chat/widgets/pricing_bottom_sheet.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/chat/chat_opening_provider.dart';
 import '../../../core/chat/session_closure_notifier.dart';
 import '../../../core/constants.dart';
@@ -85,6 +86,10 @@ class _PricingBottomSheetState extends ConsumerState<PricingBottomSheet> {
   }
 
   void _onConfirm(PriceTier tier) {
+    // ignore: discarded_futures
+    ref.read(analyticsProvider).logChatExtensionRequested(
+          sessionId: widget.extensionSessionId,
+        );
     Navigator.of(context).pop();
     ref.read(sessionClosureProvider.notifier).requestExtension(
           widget.extensionSessionId,

client_app/lib/features/home/home_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../core/analytics/analytics_service.dart';
 import '../../core/auth/auth_notifier.dart';
 import '../../core/auth/onboarding_intent_provider.dart';
 import '../../core/availability/mitra_availability_notifier.dart';
@@ -81,6 +82,11 @@ class _HomeScreenState extends ConsumerState<HomeScreen> with WidgetsBindingObse
   /// CTA path for SHomeReturning. Returning users get the bestie-choice sheet
   /// when they have prior history, otherwise jump to the new-payment shell.
   Future<void> _onCurhatBestieBaruPressed(BuildContext context) async {
+    // Returning user starting a fresh curhat (repeat funnel). The
+    // bestie_reselect sub-event fires later from the history list if they pick
+    // a known bestie; this marks the top of the repeat funnel.
+    // ignore: discarded_futures
+    ref.read(analyticsProvider).logCurhatRepeatStart();
     bool hasHistory;
     try {
       hasHistory = await ref.read(bestieHistoryHasItemsProvider.future);
@@ -89,6 +95,8 @@ class _HomeScreenState extends ConsumerState<HomeScreen> with WidgetsBindingObse
     }
     if (!context.mounted) return;
     if (hasHistory) {
+      // ignore: discarded_futures
+      ref.read(analyticsProvider).logBestieChoiceView();
       await BestieChoiceSheet.show(context);
       return;
     }
@@ -101,6 +109,9 @@ class _HomeScreenState extends ConsumerState<HomeScreen> with WidgetsBindingObse
   /// (the call-sign check); display_name_screen kicks off `loginAnonymous`
   /// and pushes into the verif-choice sheet.
   void _onAkuMauCurhatPressed(BuildContext context) {
+    // Top of the activation funnel — fresh user tapping the primary CTA.
+    // ignore: discarded_futures
+    ref.read(analyticsProvider).logCurhatStart(entryPoint: 'home_primary');
     context.push('/auth/display-name');
   }
 
@@ -172,7 +183,7 @@ class _SHome1stView extends ConsumerWidget {
               const _GreetingSubtitle(),
               const SizedBox(height: 32),
               _PrimaryCTA(
-                label: 'aku mau curhat',
+                label: 'Aku Mau Curhat',
                 enabled: mitraAvailable,
                 onPressed: onCTA,
               ),
@@ -395,7 +406,7 @@ class _SHomeReturningView extends ConsumerWidget {
         activeSessionAsync.when(
           loading: () => const Center(child: CircularProgressIndicator()),
           error: (_, __) => _PrimaryCTA(
-            label: 'curhat sama bestie baru',
+            label: 'Aku Mau Curhat',
             enabled: mitraAvailable,
             onPressed: onCTA,
           ),
@@ -415,7 +426,7 @@ class _SHomeReturningView extends ConsumerWidget {
               );
             }
             return _PrimaryCTA(
-              label: 'curhat sama bestie baru',
+              label: 'Aku Mau Curhat',
               enabled: mitraAvailable,
               onPressed: onCTA,
             );

client_app/lib/features/home/screens/bestie_history_list_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/constants.dart';
 import '../../../core/theme/halo_tokens.dart';
 import '../../../core/theme/widgets/widgets.dart';
@@ -132,6 +133,13 @@ class BestieHistoryListScreen extends ConsumerWidget {
                       return;
                     }
                     if (item.mitraId == null) return;
+                    // Repeat funnel: user re-selected a known bestie. mitra_ref
+                    // is opaque (hashed) — never the raw mitra id, per the
+                    // no-PII / opaque-mitra-identity rule.
+                    // ignore: discarded_futures
+                    ref.read(analyticsProvider).logBestieReselect(
+                          mitraRef: item.mitraId!.hashCode.toString(),
+                        );
                     // Stamp the targeted mitra onto the payment draft; the
                     // multi-screen payment flow (entry → method → waiting →
                     // notif-gate → searching) reads it back to fire the

client_app/lib/features/home/widgets/bestie_choice_sheet.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/theme/halo_tokens.dart';
 import '../../../core/theme/widgets/widgets.dart';
 import '../../payment/state/payment_draft_provider.dart';
@@ -52,6 +53,8 @@ class BestieChoiceSheet extends ConsumerWidget {
           subtitle: 'lanjut cerita ke bestie yang pernah dengerin kamu.',
           icon: Icons.favorite_outline,
           onTap: () {
+            // ignore: discarded_futures
+            ref.read(analyticsProvider).logBestieChoiceSelect(knownBestie: true);
             Navigator.of(context).pop();
             context.push('/bestie/history');
           },
@@ -62,6 +65,8 @@ class BestieChoiceSheet extends ConsumerWidget {
           subtitle: 'cari bestie baru yang siap dengerin sekarang.',
           icon: Icons.auto_awesome_outlined,
           onTap: () {
+            // ignore: discarded_futures
+            ref.read(analyticsProvider).logBestieChoiceSelect(knownBestie: false);
             // explicit reset — this branch is blast-only, clear any stale targeted mitra
             ref.read(paymentDraftNotifierProvider.notifier).reset();
             Navigator.of(context).pop();

client_app/lib/features/onboarding/screens/usp_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/theme/halo_tokens.dart';
 import '../../../core/theme/widgets/widgets.dart';
 import '../usp_seen_provider.dart';
@@ -11,11 +12,30 @@ import '../usp_seen_provider.dart';
 ///
 /// `verified` ➞ USP → OTP (`/auth/register`).
 /// `anonymous` ➞ USP → `/payment/method-pick`.
-class UspScreen extends ConsumerWidget {
+class UspScreen extends ConsumerStatefulWidget {
   final bool verified;
 
   const UspScreen({super.key, required this.verified});
 
+  @override
+  ConsumerState<UspScreen> createState() => _UspScreenState();
+}
+
+class _UspScreenState extends ConsumerState<UspScreen> {
+  @override
+  void initState() {
+    super.initState();
+    // Activation funnel step 7 — fire on view (not teardown). One-shot:
+    // initState runs once per screen instance.
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (!mounted) return;
+      // ignore: discarded_futures
+      ref
+          .read(analyticsProvider)
+          .logOnboardingUspView(verified: widget.verified);
+    });
+  }
+
   static const _cards = [
     _UspCard(
       icon: Icons.bolt_outlined,
@@ -40,7 +60,7 @@ class UspScreen extends ConsumerWidget {
   ];
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
         title: const Padding(
@@ -94,7 +114,7 @@ class UspScreen extends ConsumerWidget {
               HaloButton(
                 label: 'aku ngerti, lanjut',
                 fullWidth: true,
-                onPressed: () => _onContinue(context, ref),
+                onPressed: () => _onContinue(context),
               ),
             ],
           ),
@@ -103,12 +123,12 @@ class UspScreen extends ConsumerWidget {
     );
   }
 
-  Future<void> _onContinue(BuildContext context, WidgetRef ref) async {
+  Future<void> _onContinue(BuildContext context) async {
     // Persist the local + server flag before leaving — next time the user
     // hits VerifChoice, this screen is skipped.
     await ref.read(uspSeenProvider.notifier).markSeen();
     if (!context.mounted) return;
-    if (verified) {
+    if (widget.verified) {
       context.push('/auth/register');
     } else {
       context.push('/payment/method-pick');

client_app/lib/features/payment/screens/payment_entry_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/auth/onboarding_intent_provider.dart';
 import '../../../core/chat/chat_opening_provider.dart';
 import '../../../core/theme/halo_tokens.dart';
@@ -38,6 +39,18 @@ class _PaymentEntryScreenState extends ConsumerState<PaymentEntryScreen> {
       // inherit a stale onboarding intent.
       ref.read(onboardingIntentProvider.notifier).state =
           OnboardingIntent.recover;
+
+      // Funnel step 8 — payment entry. A targeted mitra (set just before this
+      // screen by the bestie-history list) marks the repeat funnel; otherwise
+      // it's activation. resetExceptTarget() above preserves that flag.
+      final isRepeat =
+          ref.read(paymentDraftNotifierProvider).targetedMitraId != null;
+      // ignore: discarded_futures
+      ref.read(analyticsProvider).logPaymentView(
+            funnel:
+                isRepeat ? AnalyticsFunnel.repeat : AnalyticsFunnel.activation,
+            isRepeat: isRepeat,
+          );
     });
   }
 

client_app/lib/features/payment/screens/payment_method_screen.dart

@@ -2,6 +2,7 @@ import 'package:dio/dio.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
+import '../../../core/analytics/analytics_service.dart';
 import '../../../core/api/api_client_provider.dart';
 import '../../../core/constants.dart';
 import '../../../core/theme/halo_tokens.dart';
@@ -53,7 +54,21 @@ class _PaymentMethodScreenState extends ConsumerState<PaymentMethodScreen> {
       _error = null;
     });
     final api = ref.read(apiClientProvider);
+    final analytics = ref.read(analyticsProvider);
     try {
+      // ⭐ Capture GA4 stitching identifiers BEFORE the POST so the backend can
+      // store them in product_metadata and replay them in the server-fired
+      // payment_confirmed (Measurement Protocol). The backend currently
+      // ignores unknown body fields — intentional; we send now, stitch later.
+      final appInstanceId = await analytics.appInstanceId();
+      final gaSessionId = await analytics.sessionId();
+      if (!mounted) return;
+
+      final analyticsIds = <String, dynamic>{
+        if (appInstanceId != null) 'app_instance_id': appInstanceId,
+        if (gaSessionId != null) 'ga_session_id': gaSessionId,
+      };
+
       final body = <String, dynamic>{
         'mode': draft.mode.value,
         'duration_minutes': draft.durationMinutes,
@@ -61,11 +76,27 @@ class _PaymentMethodScreenState extends ConsumerState<PaymentMethodScreen> {
         'is_first_session_discount': draft.isFirstSessionDiscount,
         'method': _selectedCode,
         if (draft.targetedMitraId != null) 'targeted_mitra_id': draft.targetedMitraId,
+        if (analyticsIds.isNotEmpty) 'analytics': analyticsIds,
       };
       final response = await api.post('/api/client/payment-requests/', data: body);
       final data = response['data'] as Map<String, dynamic>;
       final paymentId = data['id'] as String;
       ref.read(paymentDraftNotifierProvider.notifier).setPaymentId(paymentId);
+
+      // ⭐ payment_started fires AFTER the id is known. A targeted mitra means
+      // the returning/repeat funnel; otherwise activation.
+      final isRepeat = draft.targetedMitraId != null;
+      // ignore: discarded_futures
+      analytics.logPaymentStarted(
+        paymentRequestId: paymentId,
+        amount: draft.priceIDR!,
+        method: _selectedCode!,
+        funnel: isRepeat ? AnalyticsFunnel.repeat : AnalyticsFunnel.activation,
+        isRepeat: isRepeat,
+        productType: draft.mode.value,
+        durationMinutes: draft.durationMinutes!,
+      );
+
       if (!mounted) return;
       context.push('/payment/waiting/$paymentId');
     } on DioException catch (e) {
@@ -216,10 +247,20 @@ class _PaymentMethodScreenState extends ConsumerState<PaymentMethodScreen> {
                           _expandedGroupIds.remove(g.id);
                         }
                       }),
-                      onSelect: (code) => setState(() {
-                        _selectedCode = code;
-                        _error = null;
-                      }),
+                      onSelect: (code) {
+                        // Funnel step 9 — method chosen. Fire once per pick
+                        // (not on every rebuild).
+                        if (code != _selectedCode) {
+                          // ignore: discarded_futures
+                          ref
+                              .read(analyticsProvider)
+                              .logPaymentMethodSelect(method: code);
+                        }
+                        setState(() {
+                          _selectedCode = code;
+                          _error = null;
+                        });
+                      },
                     );
                   }).toList(),
                 );

client_app/lib/features/payment/state/payment_draft_provider.g.dart

@@ -7,7 +7,7 @@ part of 'payment_draft_provider.dart';
 // **************************************************************************
 
 String _$paymentDraftNotifierHash() =>
-    r'1c81b22f25f525cd290f54618bee0b69de792998';
+    r'e489a593f5e1cc2794d13566a9cf960bb89e45c6';
 
 /// See also [PaymentDraftNotifier].
 @ProviderFor(PaymentDraftNotifier)