refactor(receipt-import): streamline category tree loading and enhance error handling

Co-authored-by: Copilot <copilot@github.com>

flutter/lib/features/admin/data/admin_repository.dart

@@ -234,14 +234,12 @@ class AdminRepository {
 
   // ── Kategorier ─────────────────────────────────────────────────────────────
 
-  Future<List<AdminCategoryNode>> listCategoryTree() async {
-    final token = await _token();
-    final data = await guardedApiCall(
-      _ref,
-      () => _apiClient.getJson(CategoryApiPaths.tree, token: token),
-    );
-    return _parseList(data, AdminCategoryNode.fromJson);
-  }
+  Future<List<AdminCategoryNode>> listCategoryTree() =>
+      _getList(
+        CategoryApiPaths.tree,
+        AdminCategoryNode.fromJson,
+        requiresAuth: false,
+      );
 
   // ── AI-modeller ────────────────────────────────────────────────────────────
 

flutter/lib/features/import/presentation/edit_dialog.dart

@@ -17,7 +17,7 @@ class EditDialog extends StatefulWidget {
   final ItemEdit current;
   final List<ProductOption> products;
   final List<AdminCategoryNode> categoryTree;
-  final Future<ProductOption?> Function(String name, int categoryId)? onCreate;
+  final Future<ProductOption?> Function(String name, int? categoryId)? onCreate;
   final ImportProductEntryMode? initialEntryMode;
 
   const EditDialog({
@@ -212,10 +212,6 @@ class _EditDialogState extends State<EditDialog> {
         showGlobalErrorDialog(context, 'Ange ett produktnamn först.');
         return;
       }
-      if (_newCategoryId == null) {
-        showGlobalErrorDialog(context, 'Välj kategori innan du skapar produkten.');
-        return;
-      }
       if (widget.onCreate == null) {
         showGlobalErrorDialog(context, 'Produktskapande är inte tillgängligt i den här vyn.');
         return;
@@ -223,7 +219,7 @@ class _EditDialogState extends State<EditDialog> {
 
       setState(() => _isCreatingProduct = true);
       try {
-        final newProduct = await widget.onCreate!(trimmedName, _newCategoryId!);
+        final newProduct = await widget.onCreate!(trimmedName, _newCategoryId);
         if (newProduct == null || !mounted) {
           if (mounted) {
             showGlobalErrorDialog(context, 'Kunde inte skapa produkten. Försök igen.');

flutter/lib/features/import/presentation/receipt_import_tab.dart

@@ -38,6 +38,10 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
   bool _isLoading = false;
   bool _isSaving = false;
   PlatformFile? _pickedFile;
+  bool _categoryLoadFailed = false;
+  bool _globalProductsLoadFailed = false;
+  bool _privateProductsLoadFailed = false;
+  bool _authLoadFailed = false;
 
   // Session-state lyfts till provider — överlever tabbyte
   ReceiptImportSession? get _session => ref.read(receiptImportSessionProvider);
@@ -72,60 +76,135 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
         ?.categoryId;
   }
 
+  List<dynamic> _extractItems(dynamic data) {
+    if (data is List<dynamic>) return data;
+    if (data is Map<String, dynamic>) {
+      return (data['items'] as List<dynamic>?) ?? const [];
+    }
+    return const [];
+  }
+
   Future<void> _loadProducts() async {
+    final api = ref.read(apiClientProvider);
+    final adminRepo = ref.read(adminRepositoryProvider);
+
+    List<AdminCategoryNode> categoryTree = _categoryTree;
+    List<dynamic> globalList = const [];
+    List<dynamic> mineList = const [];
+    var categoryFailed = false;
+    var globalFailed = false;
+    var privateFailed = false;
+    var authFailed = false;
+
+    try {
+      categoryTree = await adminRepo.listCategoryTree();
+    } catch (e, st) {
+      categoryFailed = true;
+      debugPrint('ReceiptImportTab._loadProducts categoryTree failed: $e');
+      debugPrintStack(stackTrace: st);
+    }
+
     try {
       final token = await ref.read(authStateProvider.future);
-      final api = ref.read(apiClientProvider);
-      final adminRepo = ref.read(adminRepositoryProvider);
-      final results = await Future.wait([
-        api.getJson(ProductApiPaths.list, token: token),
-        api.getJson(ProductApiPaths.mine, token: token),
-      ]);
 
-      List<AdminCategoryNode> categoryTree = _categoryTree;
       try {
-        categoryTree = await adminRepo.listCategoryTree();
+        final globalData = await api.getJson(ProductApiPaths.list, token: token);
+        globalList = _extractItems(globalData);
       } catch (e, st) {
-        debugPrint('ReceiptImportTab._loadProducts categoryTree failed: $e');
+        globalFailed = true;
+        debugPrint('ReceiptImportTab._loadProducts global products failed: $e');
         debugPrintStack(stackTrace: st);
       }
 
-      final globalData = results[0];
-      final mineData = results[1];
-      final globalList = globalData is List
-          ? globalData
-          : ((globalData as Map<String, dynamic>?)?['items'] as List? ?? []);
-      final mineList = mineData is List
-          ? mineData
-          : ((mineData as Map<String, dynamic>?)?['items'] as List? ?? []);
-      if (mounted) {
-        final mergedProducts = [
-          ...globalList
-              .cast<Map<String, dynamic>>()
-              .map((e) => (id: e['id'] as int, name: (e['canonicalName'] ?? e['name']) as String, categoryId: (e['categoryId'] as num?)?.toInt())),
-          ...mineList
-              .cast<Map<String, dynamic>>()
-              .map((e) => (id: e['id'] as int, name: (e['canonicalName'] ?? e['name']) as String, categoryId: (e['categoryId'] as num?)?.toInt())),
-        ];
-        final dedupedById = <int, ProductOption>{
-          for (final product in mergedProducts) product.id: product,
-        };
-
-        setState(() {
-          _products = dedupedById.values.toList();
-          _categoryTree = categoryTree;
-          _lookup = CategoryLookup.fromTree(categoryTree);
-        });
+      try {
+        final mineData = await api.getJson(ProductApiPaths.mine, token: token);
+        mineList = _extractItems(mineData);
+      } catch (e, st) {
+        privateFailed = true;
+        debugPrint('ReceiptImportTab._loadProducts private products failed: $e');
+        debugPrintStack(stackTrace: st);
       }
     } catch (e, st) {
-      debugPrint('ReceiptImportTab._loadProducts failed: $e');
+      authFailed = true;
+      debugPrint('ReceiptImportTab._loadProducts auth/token failed: $e');
       debugPrintStack(stackTrace: st);
-      if (mounted) {
-        ScaffoldMessenger.of(context).showSnackBar(
-          const SnackBar(content: Text('Kunde inte ladda produktlistan. Försök igen.')),
-        );
-      }
     }
+
+    if (!mounted) return;
+
+    final mergedProducts = [
+      ...globalList
+          .cast<Map<String, dynamic>>()
+          .map((e) => (id: e['id'] as int, name: (e['canonicalName'] ?? e['name']) as String, categoryId: (e['categoryId'] as num?)?.toInt())),
+      ...mineList
+          .cast<Map<String, dynamic>>()
+          .map((e) => (id: e['id'] as int, name: (e['canonicalName'] ?? e['name']) as String, categoryId: (e['categoryId'] as num?)?.toInt())),
+    ];
+    final dedupedById = <int, ProductOption>{
+      for (final product in mergedProducts) product.id: product,
+    };
+
+    setState(() {
+      _products = dedupedById.values.toList();
+      _categoryTree = categoryTree;
+      _lookup = CategoryLookup.fromTree(categoryTree);
+      _categoryLoadFailed = categoryFailed;
+      _globalProductsLoadFailed = globalFailed;
+      _privateProductsLoadFailed = privateFailed;
+      _authLoadFailed = authFailed;
+    });
+
+    if (_products.isEmpty && _categoryTree.isEmpty) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('Kunde inte ladda produkter eller kategorier. Försök igen.')),
+      );
+    }
+  }
+
+  bool get _hasLoadDiagnostics =>
+      _categoryLoadFailed ||
+      _globalProductsLoadFailed ||
+      _privateProductsLoadFailed ||
+      _authLoadFailed;
+
+  Widget _buildLoadDiagnosticsBanner(ThemeData theme) {
+    final issues = <String>[
+      if (_authLoadFailed) 'auth/token',
+      if (_categoryLoadFailed) 'categories',
+      if (_globalProductsLoadFailed) 'products:list',
+      if (_privateProductsLoadFailed) 'products:mine',
+    ];
+
+    return Container(
+      width: double.infinity,
+      padding: const EdgeInsets.all(12),
+      decoration: BoxDecoration(
+        color: Colors.amber.shade50,
+        border: Border.all(color: Colors.amber.shade300),
+        borderRadius: BorderRadius.circular(10),
+      ),
+      child: Row(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Icon(Icons.warning_amber_rounded, color: Colors.amber.shade800, size: 18),
+          const SizedBox(width: 8),
+          Expanded(
+            child: Text(
+              'Diagnostik (tillfällig): Problem vid laddning av ${issues.join(', ')}. '
+              'Vissa funktioner kan vara begränsade.',
+              style: theme.textTheme.bodySmall?.copyWith(
+                color: Colors.amber.shade900,
+              ),
+            ),
+          ),
+          const SizedBox(width: 8),
+          TextButton(
+            onPressed: _loadProducts,
+            child: const Text('Försök igen'),
+          ),
+        ],
+      ),
+    );
   }
 
   Future<void> _loadInventory() async {
@@ -228,16 +307,26 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
     int index, {
     ImportProductEntryMode? initialEntryMode,
   }) async {
+    final needsCategoryTree = initialEntryMode != ImportProductEntryMode.create;
     if (_categoryTree.isEmpty) {
       await _loadProducts();
       if (!mounted) return;
-      if (_categoryTree.isEmpty) {
+      if (_categoryTree.isEmpty && needsCategoryTree) {
         showGlobalErrorDialog(
           context,
           'Inga kategorier kunde laddas. Prova att uppdatera kategorier i Admin > Databas och försök igen.',
         );
         return;
       }
+      if (_categoryTree.isEmpty && !needsCategoryTree) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(
+            content: Text(
+              'Kategorier kunde inte laddas just nu. Du kan fortfarande skapa produkt utan kategori.',
+            ),
+          ),
+        );
+      }
     }
 
     final item = _items![index];
@@ -282,7 +371,7 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
             ProductApiPaths.createPrivate,
             body: {
               'name': name.trim(),
-              'categoryId': categoryId,
+              if (categoryId != null) 'categoryId': categoryId,
             },
             token: token,
           );
@@ -302,7 +391,7 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
             throw Exception('API-svar saknar produktnamn.');
           }
 
-          final returnedCategoryId = raw['categoryId'] is num
+            final int? returnedCategoryId = raw['categoryId'] is num
               ? (raw['categoryId'] as num).toInt()
               : categoryId;
 
@@ -524,6 +613,10 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
             icon: const Icon(Icons.receipt_long_outlined),
             label: const Text('Importera kvitto'),
           ),
+          if (_hasLoadDiagnostics) ...[
+            const SizedBox(height: 12),
+            _buildLoadDiagnosticsBanner(theme),
+          ],
           // ── Resultatlista ──────────────────────────────────────────────
           if (items != null) ...[
             const SizedBox(height: 24),