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

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();
   }