Kasir: indikator loading produk + empty/error state + tombol Coba lagi, refresh retry, login tanpa loading global

lib/main.dart

@@ -191,26 +191,25 @@ class AuthGate extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return Selector<AppState, bool>(
-      selector: (context, state) => state.loading,
-      builder: (context, loading, child) {
-        if (loading) {
+    return Selector<AppState, ({bool loading, bool loggedIn, bool expired})>(
+      selector: (context, state) => (
+        loading: state.loading,
+        loggedIn: state.isLoggedIn,
+        expired: state.sessionExpired,
+      ),
+      builder: (context, a, child) {
+        // Loading global hanya untuk init aplikasi. Proses login dihandle
+        // tombol LoginScreen, status data produk dihandle spinner khusus
+        // Kasir agar layar tidak melepas LoginScreen saat gagal login.
+        if (a.loading) {
           return const Scaffold(
-            body: Center(
-              child: CircularProgressIndicator(color: kAccent),
-            ),
+            body: Center(child: CircularProgressIndicator(color: kAccent)),
           );
         }
-        return Selector<AppState, ({bool loggedIn, bool expired})>(
-          selector: (context, state) =>
-              (loggedIn: state.isLoggedIn, expired: state.sessionExpired),
-          builder: (context, auth, child) {
-            if (auth.loggedIn && !auth.expired) {
-              return const HomePage();
-            }
-            return const LoginScreen();
-          },
-        );
+        if (a.loggedIn && !a.expired) {
+          return const HomePage();
+        }
+        return const LoginScreen();
       },
     );
   }

lib/screens/kasir_screen.dart

@@ -56,6 +56,7 @@ class _KasirScreenState extends State<KasirScreen> {
             p.name.toLowerCase().contains(query) ||
             p.barcode.toLowerCase().contains(query))
         .toList();
+    final isInitialProductsLoading = state.productsLoading && !state.dataReady;
 
     return Column(
       children: [
@@ -283,8 +284,30 @@ class _KasirScreenState extends State<KasirScreen> {
           ),
         ),
         Expanded(
-          child: _isGrid
-              ? GridView.builder(
+          child: isInitialProductsLoading
+              ? const _ProductsLoading()
+              : products.isEmpty
+                  ? state.productsError != null
+                      ? _EmptyState(
+                          icon: Icons.cloud_off_outlined,
+                          title: 'Gagal memuat produk',
+                          subtitle:
+                              'Periksa koneksi lalu coba lagi. Detail: ${state.productsError}',
+                          actionLabel: 'Coba lagi',
+                        )
+                      : _EmptyState(
+                          icon: state.products.isEmpty
+                              ? Icons.inventory_2_outlined
+                              : Icons.search_off,
+                          title: state.products.isEmpty
+                              ? 'Belum ada produk'
+                              : 'Tidak ditemukan',
+                          subtitle: state.products.isEmpty
+                              ? 'Tambahkan produk lewat tab Produk.'
+                              : 'Coba kata kunci lain.',
+                        )
+                  : _isGrid
+                      ? GridView.builder(
                   padding: const EdgeInsets.fromLTRB(12, 4, 12, 12),
                   gridDelegate:
                       const SliverGridDelegateWithFixedCrossAxisCount(
@@ -1762,3 +1785,103 @@ class _QtyButton extends StatelessWidget {
     );
   }
 }
+
+class _EmptyState extends StatelessWidget {
+  final IconData icon;
+  final String title;
+  final String subtitle;
+  final String? actionLabel;
+  const _EmptyState({
+    required this.icon,
+    required this.title,
+    required this.subtitle,
+    this.actionLabel,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Padding(
+        padding: const EdgeInsets.all(32),
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            Icon(icon, size: 56, color: kMuted),
+            const SizedBox(height: 16),
+            Text(
+              title,
+              style: const TextStyle(
+                color: kText,
+                fontSize: 16,
+                fontWeight: FontWeight.w700,
+              ),
+              textAlign: TextAlign.center,
+            ),
+            const SizedBox(height: 8),
+            Text(
+              subtitle,
+              style: const TextStyle(color: kMuted, fontSize: 13),
+              textAlign: TextAlign.center,
+            ),
+            if (actionLabel != null) ...[
+              const SizedBox(height: 16),
+              OutlinedButton.icon(
+                onPressed: () => context.read<AppState>().retryProducts(),
+                icon: const Icon(Icons.refresh),
+                label: Text(actionLabel!),
+              ),
+            ],
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _ProductsLoading extends StatelessWidget {
+  const _ProductsLoading();
+
+  @override
+  Widget build(BuildContext context) {
+    return ListView.separated(
+      padding: const EdgeInsets.fromLTRB(12, 4, 12, 12),
+      itemCount: 6,
+      separatorBuilder: (_, __) => const SizedBox(height: 8),
+      itemBuilder: (context, i) {
+        return Container(
+          height: 72,
+          decoration: BoxDecoration(
+            color: kSurface2,
+            borderRadius: BorderRadius.circular(12),
+            border: Border.all(color: kBorder),
+          ),
+          child: Row(
+            children: [
+              Container(
+                width: 56,
+                height: 56,
+                margin: const EdgeInsets.all(8),
+                decoration: BoxDecoration(
+                  color: kBorder,
+                  borderRadius: BorderRadius.circular(8),
+                ),
+              ),
+              const Expanded(
+                child: Center(
+                  child: SizedBox(
+                    height: 20,
+                    width: 20,
+                    child: CircularProgressIndicator(
+                      strokeWidth: 2,
+                      color: kAccent,
+                    ),
+                  ),
+                ),
+              ),
+            ],
+          ),
+        );
+      },
+    );
+  }
+}

lib/state/app_state.dart

@@ -43,6 +43,8 @@ class AppState extends ChangeNotifier {
     }
   }
 
+  Future<void> retryProducts() => refresh();
+
   // Client dengan service_role key untuk operasi admin (buat/edit/hapus akun kasir).
   // PERINGATAN: key ini bypass RLS — hanya untuk app POS di device terpercaya.
   final SupabaseClient _admin = SupabaseClient(supabaseUrl, supabaseServiceKey);
@@ -69,6 +71,9 @@ class AppState extends ChangeNotifier {
   List<Map<String, dynamic>> kasirAccounts = [];
   bool loading = true;
   String? error;
+  bool dataReady = false;
+  bool productsLoading = false;
+  String? productsError;
 
   static const int _pageSize = 30;
   int _visibleProductCount = _pageSize;
@@ -196,7 +201,12 @@ class AppState extends ChangeNotifier {
     _salesFirstLoad = false;
   }
 
-  Future<void> refresh() async {
+  /// Refresh produk + riwayat dengan retry terbatas untuk kegagalan sementara.
+  /// Nyalakan indikator loading hanya saat data pertama belum siap, supaya
+  /// Kasir bisa menampilkan status memuat/gagal/kosong dengan jelas.
+  /// Nonaktifkan indikator apa pun yang menyebabkan masalah refresh berulang.
+  /// Kirim sinyal hanya pada pemuatan awal; polling latar tidak mengganggu.
+  Future<void> refresh({bool notifyLoading = true, int retries = 1}) async {
     final authOk = await _ensureSessionAndAuth();
     if (!authOk) {
       // Auth mati: jangan lanjut query (pasti 401). Cukup notify agar
@@ -204,9 +214,34 @@ class AppState extends ChangeNotifier {
       notifyListeners();
       return;
     }
-    await _loadProducts();
-    await _loadSales();
-    notifyListeners();
+
+    final showProductsLoading = notifyLoading && !dataReady;
+    if (showProductsLoading) {
+      productsLoading = true;
+      notifyListeners();
+    }
+    try {
+      await _loadProducts();
+      await _loadSales();
+      dataReady = true;
+    } catch (e) {
+      productsError ??= e.toString();
+      if (retries > 0) {
+        // Coba sekali lagi untuk kegagalan sementara (misal koneksi putus).
+        productsError = null;
+        await Future<void>.delayed(const Duration(seconds: 1));
+        await refresh(notifyLoading: notifyLoading, retries: retries - 1);
+        return;
+      }
+      debugPrint('Gagal refresh: $e');
+    } finally {
+      if (showProductsLoading) {
+        productsLoading = false;
+      }
+      if (notifyLoading) {
+        notifyListeners();
+      }
+    }
   }
 
   final OfflineQueueService _offlineQueue = OfflineQueueService();
@@ -313,17 +348,20 @@ class AppState extends ChangeNotifier {
       );
       userId = res.user?.id;
       _sessionExpired = false;
-      await _loadProfile();
-      // Muat produk/riwayat langsung agar user tidak menunggu poll berikut.
-      // Gagal load tak mematikan proses login.
-      try {
-        await refresh();
-      } catch (_) {}
+      dataReady = false;
+      productsLoading = true;
+      productsError = null;
       notifyListeners();
+      await _loadProfile();
+      await refresh();
       return null;
     } on AuthException catch (e) {
+      productsLoading = false;
+      notifyListeners();
       return e.message;
     } catch (e) {
+      productsLoading = false;
+      notifyListeners();
       return e.toString();
     }
   }
@@ -357,6 +395,10 @@ class AppState extends ChangeNotifier {
     _profile = null;
     cart.clear();
     _discount = 0;
+    products = [];
+    dataReady = false;
+    productsLoading = false;
+    productsError = null;
     notifyListeners();
   }