add price policy

PROVIDER_FIX_SUMMARY.md

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+# Provider Fix Summary
+
+## ✅ Problem Fixed
+
+The `price_documents_provider.dart` was using the wrong Riverpod pattern.
+
+## ❌ Before (Incorrect - NotifierProvider Pattern)
+
+```dart
+@riverpod
+class PriceDocuments extends _$PriceDocuments {
+  @override
+  List<PriceDocument> build() {
+    return _mockDocuments;
+  }
+}
+```
+
+**Issue**: This pattern is for stateful providers that need methods to mutate state. For simple data providers that just return a value, this is overkill and causes unnecessary complexity.
+
+## ✅ After (Correct - Functional Provider Pattern)
+
+```dart
+@riverpod
+List<PriceDocument> priceDocuments(PriceDocumentsRef ref) {
+  return _mockDocuments;
+}
+
+@riverpod
+List<PriceDocument> filteredPriceDocuments(
+  FilteredPriceDocumentsRef ref,
+  DocumentCategory category,
+) {
+  final allDocs = ref.watch(priceDocumentsProvider);
+  return allDocs.where((doc) => doc.category == category).toList();
+}
+```
+
+**Benefits**:
+- ✅ Simpler and more readable
+- ✅ Matches pattern used by other simple providers in the project
+- ✅ No need for extending base classes
+- ✅ Perfect for read-only data
+- ✅ Supports family modifiers for filtered data
+
+## 📋 When to Use Each Pattern
+
+### Use Functional Providers (@riverpod function)
+**When you have:**
+- ✅ Read-only data
+- ✅ Computed/derived state
+- ✅ Simple transformations
+- ✅ No state mutations needed
+
+**Examples in project:**
+- `gifts_provider.dart` - Returns list of gifts
+- `selected_category_provider.dart` - Returns current category
+- `search_query_provider.dart` - Returns search text
+- **`price_documents_provider.dart`** - Returns list of documents ✅
+
+### Use Class-Based Notifiers (@riverpod class)
+**When you need:**
+- ✅ Mutable state with methods
+- ✅ State that changes over time
+- ✅ Methods to update/modify state
+- ✅ Complex state management logic
+
+**Examples in project:**
+- `cart_provider.dart` - Has `addItem()`, `removeItem()`, `updateQuantity()`
+- `favorites_provider.dart` - Has `toggleFavorite()`, `addFavorite()`
+- `loyalty_points_provider.dart` - Has `deductPoints()`, `addPoints()`
+
+## 🎯 Key Takeaway
+
+For the Price Policy feature, since we're just displaying a static list of documents with filtering, the **functional provider pattern** is the correct choice. No state mutations are needed, so we don't need the class-based notifier pattern.
+
+## 📁 Files Changed
+
+1. `lib/features/price_policy/presentation/providers/price_documents_provider.dart`
+2. `lib/features/price_policy/presentation/providers/price_documents_provider.g.dart`
+
+## ✅ Result
+
+The provider now works correctly and follows the project's conventions for simple data providers!