# Feature Implementation Examples - Real-World Scenarios

> **8 industry-specific examples showing how to use the feature-implementer skill**
>
> Each example includes complete IMPLEMENTATION_PLAN.md specifications, expected output, and implementation notes.

---

## Table of Contents

1. [E-Commerce: Product Catalog](#1-e-commerce-product-catalog)
2. [Healthcare: Patient Records (HIPAA)](#2-healthcare-patient-records-hipaa)
3. [FinTech: Transaction History (PCI-DSS)](#3-fintech-transaction-history-pci-dss)
4. [Social Media: User Feed](#4-social-media-user-feed)
5. [Education: Course Management](#5-education-course-management)
6. [Real Estate: Property Listings](#6-real-estate-property-listings)
7. [Food Delivery: Order Tracking](#7-food-delivery-order-tracking)
8. [Enterprise SaaS: Team Management](#8-enterprise-saas-team-management)

---

## 1. E-Commerce: Product Catalog

### Scenario

Building a product browsing and search feature for an e-commerce app. Users need to:
- Browse products by category
- Search products by name/description
- Filter by price range, brand, ratings
- View product details
- Add to cart

### IMPLEMENTATION_PLAN.md Specification

```markdown
### Feature 3: Product Catalog
**Priority:** HIGH
**Estimated Time:** 8-10 hours
**Dependencies:** None

**Requirements:**
- Browse products by category (Electronics, Clothing, Home, etc.)
- Search products by name/description (fuzzy search)
- Filter products by:
  - Price range ($0-$50, $50-$100, $100+)
  - Brand (Apple, Samsung, Nike, etc.)
  - Average rating (4+ stars, 3+ stars)
- Sort by: Price (low to high, high to low), Rating, Newest
- Pagination (20 products per page)
- View product details (images, description, reviews)
- Add to cart

**User Stories:**
- As a user, I can browse products by category
- As a user, I can search for products by name
- As a user, I can filter products by price and brand
- As a user, I can view detailed product information
- As a user, I can add products to my shopping cart

**Acceptance Criteria:**
- [ ] Product list loads in under 2 seconds
- [ ] Search returns relevant results
- [ ] Filters work independently and in combination
- [ ] Product images load progressively
- [ ] Cart badge updates immediately
- [ ] Offline: Show cached products

**Data Models:**
```dart
class Product {
  final String id;
  final String name;
  final String description;
  final double price;
  final String currency;
  final String brand;
  final List<String> imageUrls;
  final double averageRating;
  final int reviewCount;
  final int stockQuantity;
  final String category;
  final DateTime createdAt;
}

class ProductFilter {
  final String? category;
  final double? minPrice;
  final double? maxPrice;
  final String? brand;
  final double? minRating;
  final ProductSortBy sortBy;
}

enum ProductSortBy {
  priceLowToHigh,
  priceHighToLow,
  rating,
  newest,
}

class PaginatedProducts {
  final List<Product> products;
  final int page;
  final int totalPages;
  final bool hasMore;
}
```

**API Endpoints:**
- GET /api/products?page=1&limit=20&category=electronics
- GET /api/products/search?q=iphone&page=1
- GET /api/products/{id}
- GET /api/categories

**UI Screens:**
- ProductListScreen (grid/list view)
- ProductDetailScreen
- ProductSearchScreen
- FilterBottomSheet

**Technical Details:**
- Image caching: cached_network_image package
- Search debouncing: 500ms delay
- Infinite scroll pagination
- Skeleton loaders while loading
- Error retry with exponential backoff
```

### Usage

```bash
@claude use skill automation/feature-implementer

# Input:
Feature name: Product Catalog
Test coverage target: 75
Generate integration tests: yes
```

### Expected Output

```
✅ Feature "Product Catalog" implemented successfully!

📊 Summary:
- Files Created: 28
  - Domain: 9 files (entities, use cases, repositories)
  - Data: 10 files (models, data sources, repositories)
  - Presentation: 9 files (BLoC, screens, widgets)
- Test Coverage: 77.3%
- Implementation Time: 7 minutes

📁 Key Files:
Domain:
  - lib/features/products/domain/entities/product.dart
  - lib/features/products/domain/entities/product_filter.dart
  - lib/features/products/domain/usecases/get_products.dart
  - lib/features/products/domain/usecases/search_products.dart
  - lib/features/products/domain/usecases/get_product_details.dart

Presentation:
  - lib/features/products/presentation/pages/product_list_screen.dart
  - lib/features/products/presentation/pages/product_detail_screen.dart
  - lib/features/products/presentation/widgets/product_card.dart
  - lib/features/products/presentation/widgets/filter_bottom_sheet.dart

✨ Special Features Generated:
- Infinite scroll pagination with loading indicators
- Image caching and progressive loading
- Search debouncing (500ms)
- Skeleton loaders for better UX
- Offline mode with cached products
```

### Implementation Notes

**Pagination Handling:**

```dart
// Generated BLoC handles infinite scroll
class ProductBloc extends Bloc<ProductEvent, ProductState> {
  int _currentPage = 1;
  final List<Product> _allProducts = [];

  Future<void> _onLoadProducts(LoadProductsEvent event, Emitter emit) async {
    if (event.isRefresh) {
      _currentPage = 1;
      _allProducts.clear();
      emit(ProductLoading());
    } else {
      emit(ProductLoadingMore(products: _allProducts));
    }

    final result = await getProducts(GetProductsParams(
      page: _currentPage,
      filter: event.filter,
    ));

    result.fold(
      (failure) => emit(ProductError(message: failure.message)),
      (paginatedProducts) {
        _allProducts.addAll(paginatedProducts.products);
        _currentPage++;
        emit(ProductLoaded(
          products: _allProducts,
          hasMore: paginatedProducts.hasMore,
        ));
      },
    );
  }
}

// In UI
ListView.builder(
  controller: _scrollController,
  itemCount: products.length + (hasMore ? 1 : 0),
  itemBuilder: (context, index) {
    if (index == products.length) {
      // Load more indicator
      return CircularProgressIndicator();
    }
    return ProductCard(product: products[index]);
  },
);

_scrollController.addListener(() {
  if (_scrollController.position.pixels ==
      _scrollController.position.maxScrollExtent) {
    // Reached bottom, load more
    context.read<ProductBloc>().add(LoadProductsEvent(isRefresh: false));
  }
});
```

**Search Debouncing:**

```dart
// Generated search widget includes debouncing
class ProductSearchDelegate extends SearchDelegate<Product?> {
  Timer? _debounce;

  @override
  Widget buildResults(BuildContext context) {
    return BlocBuilder<ProductBloc, ProductState>(
      builder: (context, state) {
        if (_debounce?.isActive ?? false) _debounce!.cancel();
        _debounce = Timer(Duration(milliseconds: 500), () {
          // Trigger search after 500ms of no typing
          context.read<ProductBloc>().add(SearchProductsEvent(query));
        });

        if (state is ProductLoading) {
          return Center(child: CircularProgressIndicator());
        } else if (state is ProductLoaded) {
          return ListView.builder(
            itemCount: state.products.length,
            itemBuilder: (context, index) {
              return ProductCard(product: state.products[index]);
            },
          );
        }
        return SizedBox.shrink();
      },
    );
  }
}
```

---

## 2. Healthcare: Patient Records (HIPAA)

### Scenario

Building a patient records management feature for a healthcare app. Must comply with HIPAA regulations:
- View patient demographics and medical history
- Encrypted storage of PHI (Protected Health Information)
- Audit logging for all PHI access
- Session timeout after 15 minutes
- Role-based access control

### IMPLEMENTATION_PLAN.md Specification

```markdown
### Feature 4: Patient Records
**Priority:** CRITICAL
**Estimated Time:** 12-16 hours
**Compliance:** HIPAA
**Dependencies:** Authentication with role-based access

**Requirements:**
- View patient demographics (name, DOB, address, insurance)
- View medical history (diagnoses, medications, allergies)
- View visit notes (doctor notes, vitals, prescriptions)
- Encrypt all PHI at rest (AES-256-GCM)
- Audit log all PHI access (who, when, what)
- Auto-logout after 15 minutes of inactivity
- Role-based access:
  - Doctor: Full access (read/write)
  - Nurse: Limited access (read vitals, update vitals)
  - Admin: Demographics only (no medical data)

**User Stories:**
- As a doctor, I can view complete patient records
- As a nurse, I can view and update patient vitals
- As an admin, I can view patient demographics for billing
- As a compliance officer, I can review PHI access logs

**Acceptance Criteria:**
- [ ] All PHI encrypted with AES-256-GCM
- [ ] Audit log created for every PHI access
- [ ] Session timeout after 15 minutes inactivity
- [ ] Role-based access enforced at API level
- [ ] PHI never logged to console or crash reports
- [ ] Offline mode disabled (PHI must stay on server)

**Security Requirements (HIPAA):**
- Encryption at rest: AES-256-GCM for all PHI
- Encryption in transit: TLS 1.2+ (HTTPS only)
- Access control: Role-based with MFA
- Audit logging: Track all create/read/update/delete of PHI
- Session management: 15-minute timeout, secure logout
- Data minimization: Only fetch necessary fields
- No PHI in logs: Redact sensitive data in error messages

**Data Models:**
```dart
class Patient {
  final String id;
  final String mrn; // Medical Record Number
  final String firstName;
  final String lastName;
  final DateTime dateOfBirth;
  final String gender;
  final String? photoUrl;

  // PHI - encrypted
  final String address;
  final String phone;
  final String? email;
  final String? ssn; // Last 4 digits only
  final InsuranceInfo? insurance;
}

class MedicalHistory {
  final String patientId;
  final List<Diagnosis> diagnoses;
  final List<Medication> medications;
  final List<Allergy> allergies;
  final List<Immunization> immunizations;
}

class VisitNote {
  final String id;
  final String patientId;
  final DateTime visitDate;
  final String chiefComplaint;
  final Vitals vitals;
  final String doctorNotes;
  final List<Prescription> prescriptions;
  final String doctorId;
}

class AuditLog {
  final String id;
  final String userId;
  final String action; // VIEW_PATIENT, UPDATE_VITALS, etc.
  final String resourceType; // Patient, MedicalHistory, VisitNote
  final String resourceId;
  final DateTime timestamp;
  final String ipAddress;
  final String deviceId;
}
```

**API Endpoints:**
- GET /api/patients/{id}
- GET /api/patients/{id}/medical-history
- GET /api/patients/{id}/visits
- POST /api/patients/{id}/visits
- GET /api/audit-logs?patient_id={id}

**UI Screens:**
- PatientListScreen
- PatientDetailScreen (demographics + medical summary)
- MedicalHistoryScreen (detailed history)
- VisitNoteScreen (individual visit)
- CreateVisitScreen (doctor only)

**Technical Details:**
- Encryption: encrypt package with AES-256-GCM
- Audit logging: Background sync every 5 minutes
- Session timeout: Reset on user interaction
- Role check: Middleware on every API call
- PHI redaction: Custom logger that redacts sensitive fields
```

### Usage

```bash
@claude use skill automation/feature-implementer

# Input:
Feature name: Patient Records
Test coverage target: 90
Generate integration tests: yes
```

### Expected Output

```
✅ Feature "Patient Records" implemented successfully!

📊 Summary:
- Files Created: 35
- Test Coverage: 91.2%
- Security Validated: Yes (HIPAA compliant)
- Implementation Time: 12 minutes

🔒 HIPAA Compliance Checks:
✅ PHI Encryption:
  - All sensitive fields encrypted with AES-256-GCM
  - Encryption keys stored in FlutterSecureStorage
  - Key rotation every 90 days (scheduled)

✅ Audit Logging:
  - AuditLog entity created
  - All PHI access logged (user, action, timestamp, IP)
  - Audit logs synced to server every 5 minutes
  - Audit logs retained for 7 years (per HIPAA)

✅ Session Management:
  - 15-minute inactivity timeout implemented
  - SessionManager monitors user interactions
  - Auto-logout on timeout with clear PHI from memory

✅ Access Control:
  - Role-based permissions enforced in repository
  - API calls include role header
  - Unauthorized access throws AuthFailure

✅ Data Minimization:
  - Only requested fields fetched from API
  - SSN stored as last 4 digits only
  - Full SSN NEVER sent to app

✅ No PHI in Logs:
  - Custom logger redacts sensitive fields
  - PHI excluded from crash reports (Sentry integration)
  - Console logs disabled in production

📝 Additional Files Created:
  - lib/core/security/phi_encryptor.dart
  - lib/core/security/audit_logger.dart
  - lib/core/security/session_manager.dart
  - lib/core/logging/phi_redactor.dart
```

### Implementation Notes

**PHI Encryption:**

```dart
// Generated PHI encryptor
class PhiEncryptor {
  final FlutterSecureStorage storage;
  final Encrypter encrypter;

  Future<String> encrypt(String plaintext) async {
    final key = await _getEncryptionKey();
    final iv = IV.fromSecureRandom(16);
    final encrypted = encrypter.encrypt(plaintext, iv: iv);
    return '${iv.base64}:${encrypted.base64}';
  }

  Future<String> decrypt(String ciphertext) async {
    final parts = ciphertext.split(':');
    final iv = IV.fromBase64(parts[0]);
    final encrypted = Encrypted.fromBase64(parts[1]);
    final key = await _getEncryptionKey();
    return encrypter.decrypt(encrypted, iv: iv);
  }

  Future<Key> _getEncryptionKey() async {
    var keyString = await storage.read(key: 'phi_encryption_key');
    if (keyString == null) {
      // Generate new key
      final key = Key.fromSecureRandom(32); // AES-256
      await storage.write(key: 'phi_encryption_key', value: key.base64);
      keyString = key.base64;
    }
    return Key.fromBase64(keyString);
  }
}

// Usage in model
class PatientModel extends Patient {
  @override
  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'first_name': firstName,
      'last_name': lastName,
      // PHI fields encrypted before storage
      'address': phiEncryptor.encrypt(address),
      'phone': phiEncryptor.encrypt(phone),
      'ssn_last4': ssn, // Only last 4 digits
    };
  }
}
```

**Audit Logging:**

```dart
// Generated audit logger
class AuditLogger {
  final AuditLogRepository repository;

  Future<void> log(AuditEvent event) async {
    final auditLog = AuditLog(
      id: Uuid().v4(),
      userId: event.userId,
      action: event.action,
      resourceType: event.resourceType,
      resourceId: event.resourceId,
      timestamp: DateTime.now(),
      ipAddress: await NetworkInfo.getIpAddress(),
      deviceId: await DeviceInfo.getDeviceId(),
    );

    // Save locally first (guaranteed)
    await repository.saveLocal(auditLog);

    // Sync to server (background)
    _syncQueue.add(auditLog);
  }
}

// Usage in use case
class GetPatientDetails implements UseCase<Patient, GetPatientParams> {
  @override
  Future<Either<Failure, Patient>> call(GetPatientParams params) async {
    final result = await repository.getPatient(params.patientId);

    // Log PHI access
    result.fold(
      (_) => null,
      (patient) async {
        await auditLogger.log(AuditEvent(
          userId: params.currentUserId,
          action: 'VIEW_PATIENT',
          resourceType: 'Patient',
          resourceId: patient.id,
        ));
      },
    );

    return result;
  }
}
```

**Session Timeout:**

```dart
// Generated session manager
class SessionManager {
  Timer? _timeout;
  final Duration inactivityLimit = Duration(minutes: 15);
  final VoidCallback onTimeout;

  SessionManager({required this.onTimeout});

  void resetTimeout() {
    _timeout?.cancel();
    _timeout = Timer(inactivityLimit, () {
      // Clear PHI from memory
      _clearSensitiveData();

      // Logout user
      onTimeout();
    });
  }

  void _clearSensitiveData() {
    // Clear cached patient data
    // Clear PHI from BLoC states
    // Clear encryption keys from memory
  }
}

// In main.dart
void main() {
  final sessionManager = SessionManager(
    onTimeout: () {
      // Logout user
      navigator.pushReplacementNamed('/session-expired');
    },
  );

  // Reset timeout on user interaction
  runApp(
    GestureDetector(
      onTap: () => sessionManager.resetTimeout(),
      onPanDown: (_) => sessionManager.resetTimeout(),
      child: MyApp(),
    ),
  );
}
```

---

## 3. FinTech: Transaction History (PCI-DSS)

### Scenario

Building a transaction history and payment feature for a fintech app. Must comply with PCI-DSS:
- View transaction history
- Process payments via Stripe (tokenization)
- Display saved payment methods (last 4 digits only)
- Refund transactions
- NEVER store full credit card numbers

### IMPLEMENTATION_PLAN.md Specification

```markdown
### Feature 6: Transaction History
**Priority:** HIGH
**Estimated Time:** 10-14 hours
**Compliance:** PCI-DSS Level 1
**Dependencies:** Authentication, Stripe SDK

**Requirements:**
- View transaction history (paginated, filterable)
- Filter by:
  - Date range (last 7 days, 30 days, custom)
  - Transaction type (payment, refund, deposit)
  - Status (pending, completed, failed)
  - Amount range ($0-$100, $100+)
- Export transactions to CSV
- View transaction details (merchant, amount, date, payment method)
- Initiate refunds (admin only)
- Download receipts (PDF)

**User Stories:**
- As a user, I can view my complete transaction history
- As a user, I can filter transactions by date and type
- As a user, I can download transaction receipts
- As a user, I can export transactions to CSV for taxes
- As an admin, I can initiate refunds for failed transactions

**Acceptance Criteria:**
- [ ] Transaction list loads in under 2 seconds
- [ ] Filters work independently and combined
- [ ] Export includes all filtered transactions
- [ ] Receipts match transaction data exactly
- [ ] Refunds process in under 10 seconds
- [ ] No full credit card numbers stored or displayed

**Security Requirements (PCI-DSS):**
- NEVER store full credit card numbers
- Display only last 4 digits of card
- Use Stripe tokenization for payments
- HTTPS only for all API calls
- Payment data goes directly to Stripe (not through your backend)
- No card data in logs or crash reports
- Validate CVV on frontend only (never send to backend)
- Implement 3D Secure for high-value transactions

**Data Models:**
```dart
class Transaction {
  final String id;
  final String userId;
  final TransactionType type;
  final double amount;
  final String currency;
  final TransactionStatus status;
  final String? merchantName;
  final String? merchantLogo;
  final DateTime createdAt;
  final PaymentMethodInfo? paymentMethod;
  final String? receiptUrl;
  final String? refundId; // If transaction was refunded
}

enum TransactionType {
  payment,
  refund,
  deposit,
  withdrawal,
}

enum TransactionStatus {
  pending,
  completed,
  failed,
  refunded,
}

class PaymentMethodInfo {
  final String brand; // visa, mastercard, amex
  final String last4; // Last 4 digits only
  final int expiryMonth;
  final int expiryYear;
}

class TransactionFilter {
  final DateTime? startDate;
  final DateTime? endDate;
  final TransactionType? type;
  final TransactionStatus? status;
  final double? minAmount;
  final double? maxAmount;
}
```

**API Endpoints:**
- GET /api/transactions?page=1&limit=20
- GET /api/transactions/{id}
- POST /api/transactions/export (CSV)
- GET /api/transactions/{id}/receipt (PDF download)
- POST /api/transactions/{id}/refund (admin only)

**UI Screens:**
- TransactionListScreen (with filters)
- TransactionDetailScreen
- RefundConfirmationDialog (admin only)
- ExportOptionsBottomSheet

**Technical Details:**
- Stripe SDK: flutter_stripe package
- PDF generation: pdf package
- CSV export: csv package
- Date range picker: Custom widget
- Infinite scroll pagination
- Pull-to-refresh
```

### Usage

```bash
@claude use skill automation/feature-implementer

# Input:
Feature name: Transaction History
Test coverage target: 85
Generate integration tests: yes
```

### Expected Output

```
✅ Feature "Transaction History" implemented successfully!

📊 Summary:
- Files Created: 32
- Test Coverage: 87.4%
- Security Validated: Yes (PCI-DSS compliant)
- Implementation Time: 10 minutes

🔒 PCI-DSS Compliance Checks:
✅ Card Data Protection:
  - Full card numbers NEVER stored
  - Only last 4 digits displayed
  - CVV validated on frontend only (never sent to backend)
  - Payment data sent directly to Stripe

✅ Tokenization:
  - Stripe tokenization implemented
  - Card details tokenized before transmission
  - Tokens used for subsequent charges

✅ Secure Transmission:
  - HTTPS enforced for all API calls
  - TLS 1.2+ required
  - Certificate pinning enabled

✅ Access Control:
  - Refund operations restricted to admin role
  - Transaction access limited to transaction owner
  - Audit logging for all refund operations

✅ Logging Restrictions:
  - Card data excluded from all logs
  - Sensitive fields redacted in error messages
  - Crash reports sanitized

📝 Stripe Integration:
  - PaymentIntent flow implemented
  - 3D Secure support added
  - Webhook handling for payment status updates
```

### Implementation Notes

**Stripe Payment Intent Flow:**

```dart
// Generated payment service
class PaymentService {
  final StripeService stripe;
  final PaymentRepository repository;

  Future<Either<Failure, Transaction>> processPayment({
    required int amount,
    required String currency,
    required String paymentMethodId,
  }) async {
    try {
      // 1. Create payment intent on backend
      final paymentIntentResult = await repository.createPaymentIntent(
        amount: amount,
        currency: currency,
      );

      if (paymentIntentResult.isLeft()) {
        return paymentIntentResult.fold(
          (failure) => Left(failure),
          (_) => throw UnimplementedError(),
        );
      }

      final paymentIntent = paymentIntentResult.fold(
        (_) => throw UnimplementedError(),
        (intent) => intent,
      );

      // 2. Confirm payment with Stripe (client-side)
      // Card details go directly to Stripe, NOT your backend
      final confirmedIntent = await Stripe.instance.confirmPayment(
        paymentIntentClientSecret: paymentIntent.clientSecret,
        data: PaymentMethodParams.cardFromMethodId(
          paymentMethodData: PaymentMethodDataCardFromMethod(
            paymentMethodId: paymentMethodId,
          ),
        ),
      );

      // 3. Verify payment status on backend
      final transaction = await repository.verifyPayment(
        paymentIntentId: confirmedIntent!.id,
      );

      return transaction;
    } on StripeException catch (e) {
      return Left(PaymentFailure(message: e.error.message ?? 'Payment failed'));
    }
  }
}
```

**CSV Export:**

```dart
// Generated export service
class TransactionExportService {
  Future<Either<Failure, File>> exportToCsv({
    required List<Transaction> transactions,
    required String filePath,
  }) async {
    try {
      final csv = ListToCsvConverter().convert([
        // Headers
        ['Date', 'Type', 'Merchant', 'Amount', 'Status', 'Payment Method'],
        // Rows
        ...transactions.map((t) => [
          DateFormat('yyyy-MM-dd HH:mm').format(t.createdAt),
          t.type.name.toUpperCase(),
          t.merchantName ?? 'N/A',
          '\$${t.amount.toStringAsFixed(2)}',
          t.status.name.toUpperCase(),
          t.paymentMethod != null
              ? '${t.paymentMethod!.brand.toUpperCase()} •••• ${t.paymentMethod!.last4}'
              : 'N/A',
        ]),
      ]);

      final file = File(filePath);
      await file.writeAsString(csv);

      return Right(file);
    } catch (e) {
      return Left(CacheFailure(message: 'Failed to export CSV: $e'));
    }
  }
}
```

**PDF Receipt Generation:**

```dart
// Generated receipt service
class ReceiptService {
  final pdf.Document document = pdf.Document();

  Future<Either<Failure, File>> generateReceipt({
    required Transaction transaction,
    required String filePath,
  }) async {
    try {
      document.addPage(
        pdf.Page(
          build: (context) {
            return pdf.Column(
              crossAxisAlignment: pdf.CrossAxisAlignment.start,
              children: [
                pdf.Text('RECEIPT', style: pdf.TextStyle(fontSize: 24, fontWeight: pdf.FontWeight.bold)),
                pdf.SizedBox(height: 20),
                pdf.Text('Transaction ID: ${transaction.id}'),
                pdf.Text('Date: ${DateFormat('MMMM dd, yyyy').format(transaction.createdAt)}'),
                pdf.SizedBox(height: 20),
                pdf.Divider(),
                pdf.SizedBox(height: 20),
                pdf.Row(
                  mainAxisAlignment: pdf.MainAxisAlignment.spaceBetween,
                  children: [
                    pdf.Text('Merchant:'),
                    pdf.Text(transaction.merchantName ?? 'N/A'),
                  ],
                ),
                pdf.Row(
                  mainAxisAlignment: pdf.MainAxisAlignment.spaceBetween,
                  children: [
                    pdf.Text('Amount:'),
                    pdf.Text('\$${transaction.amount.toStringAsFixed(2)}', style: pdf.TextStyle(fontWeight: pdf.FontWeight.bold)),
                  ],
                ),
                if (transaction.paymentMethod != null)
                  pdf.Row(
                    mainAxisAlignment: pdf.MainAxisAlignment.spaceBetween,
                    children: [
                      pdf.Text('Payment Method:'),
                      pdf.Text('${transaction.paymentMethod!.brand.toUpperCase()} •••• ${transaction.paymentMethod!.last4}'),
                    ],
                  ),
              ],
            );
          },
        ),
      );

      final file = File(filePath);
      await file.writeAsBytes(await document.save());

      return Right(file);
    } catch (e) {
      return Left(CacheFailure(message: 'Failed to generate receipt: $e'));
    }
  }
}
```

---

## 4. Social Media: User Feed

### Scenario

Building a social media feed feature with posts, likes, comments, and real-time updates.

### IMPLEMENTATION_PLAN.md Specification

```markdown
### Feature 7: User Feed
**Priority:** HIGH
**Estimated Time:** 10-12 hours
**Dependencies:** Authentication

**Requirements:**
- View personalized feed (posts from followed users)
- Infinite scroll pagination
- Like/unlike posts
- Comment on posts
- Share posts
- Real-time updates for new posts
- Pull-to-refresh
- Image/video posts
- Offline: View cached posts

**User Stories:**
- As a user, I can see posts from people I follow
- As a user, I can like and comment on posts
- As a user, I can share posts to my followers
- As a user, I see new posts in real-time

**Data Models:**
```dart
class Post {
  final String id;
  final String authorId;
  final String authorName;
  final String? authorPhotoUrl;
  final String content;
  final List<String>? mediaUrls;
  final MediaType mediaType;
  final int likeCount;
  final int commentCount;
  final int shareCount;
  final bool isLikedByCurrentUser;
  final DateTime createdAt;
}

enum MediaType { text, image, video }

class Comment {
  final String id;
  final String postId;
  final String authorId;
  final String authorName;
  final String content;
  final DateTime createdAt;
}
```

**API Endpoints:**
- GET /api/feed?page=1&limit=20
- POST /api/posts/{id}/like
- DELETE /api/posts/{id}/like
- POST /api/posts/{id}/comments
- GET /api/posts/{id}/comments?page=1
- WebSocket: wss://api.example.com/feed (real-time updates)
```

### Expected Output

```
✅ Feature "User Feed" implemented successfully!

📊 Summary:
- Files Created: 30
- Test Coverage: 79.1%
- Real-time updates: Yes (WebSocket)

✨ Special Features:
- Infinite scroll with optimistic updates
- Real-time feed updates via WebSocket
- Offline mode with cached posts
- Image caching and lazy loading
- Like/comment animations
```

---

## 5. Education: Course Management

### Scenario

Building a course management feature for an e-learning platform.

### IMPLEMENTATION_PLAN.md Specification

```markdown
### Feature 8: Course Management
**Priority:** MEDIUM
**Estimated Time:** 8-10 hours

**Requirements:**
- Browse available courses by category
- View course details (syllabus, instructor, ratings)
- Enroll in courses
- Track course progress (% complete)
- View course materials (videos, PDFs, quizzes)
- Submit assignments
- View grades

**Data Models:**
```dart
class Course {
  final String id;
  final String title;
  final String description;
  final String instructorName;
  final String? thumbnailUrl;
  final double rating;
  final int studentCount;
  final int lessonCount;
  final Duration estimatedDuration;
  final CourseCategory category;
  final bool isEnrolled;
}

class CourseProgress {
  final String courseId;
  final int completedLessons;
  final int totalLessons;
  final double progressPercentage;
  final DateTime? lastAccessedAt;
}

class Lesson {
  final String id;
  final String courseId;
  final String title;
  final LessonType type;
  final String contentUrl;
  final Duration duration;
  final bool isCompleted;
}
```

**API Endpoints:**
- GET /api/courses?category=programming
- POST /api/courses/{id}/enroll
- GET /api/courses/{id}/progress
- POST /api/lessons/{id}/complete
```

---

## 6. Real Estate: Property Listings

### Scenario

Building a property listing feature for a real estate app.

### IMPLEMENTATION_PLAN.md Specification

```markdown
### Feature 9: Property Listings
**Priority:** HIGH
**Estimated Time:** 10-12 hours

**Requirements:**
- Browse properties (for sale/rent)
- Search by location, price, bedrooms, etc.
- View property details (photos, description, amenities)
- Map view of properties
- Schedule property tours
- Save favorite properties
- Filter by: Price, bedrooms, bathrooms, square footage, property type

**Data Models:**
```dart
class Property {
  final String id;
  final PropertyType type;
  final PropertyStatus status;
  final double price;
  final String address;
  final LatLng coordinates;
  final int bedrooms;
  final int bathrooms;
  final double squareFeet;
  final List<String> photoUrls;
  final List<String> amenities;
  final String description;
  final String agentId;
}

class PropertyTour {
  final String id;
  final String propertyId;
  final DateTime scheduledAt;
  final TourType type; // in-person, virtual
  final TourStatus status;
}
```

**API Endpoints:**
- GET /api/properties?lat=37.7749&lon=-122.4194&radius=10
- GET /api/properties/{id}
- POST /api/properties/{id}/tours
- POST /api/properties/{id}/favorite
```

---

## 7. Food Delivery: Order Tracking

### Scenario

Building an order tracking feature for a food delivery app.

### IMPLEMENTATION_PLAN.md Specification

```markdown
### Feature 10: Order Tracking
**Priority:** HIGH
**Estimated Time:** 12-14 hours

**Requirements:**
- View order status (preparing, en route, delivered)
- Real-time driver location on map
- Estimated delivery time
- Contact driver
- Order history
- Rate completed orders
- Reorder from history

**Data Models:**
```dart
class Order {
  final String id;
  final String restaurantId;
  final String restaurantName;
  final List<OrderItem> items;
  final double subtotal;
  final double deliveryFee;
  final double tax;
  final double total;
  final OrderStatus status;
  final DateTime createdAt;
  final DateTime? estimatedDeliveryAt;
  final DriverInfo? driver;
}

class DriverInfo {
  final String id;
  final String name;
  final String? photoUrl;
  final String phoneNumber;
  final LatLng? currentLocation;
  final String vehicleType;
}

class OrderItem {
  final String id;
  final String name;
  final int quantity;
  final double price;
  final List<String>? customizations;
}
```

**API Endpoints:**
- GET /api/orders/{id}
- WebSocket: wss://api.example.com/orders/{id}/track
- GET /api/orders/history?page=1
- POST /api/orders/{id}/reorder
```

---

## 8. Enterprise SaaS: Team Management

### Scenario

Building a team management feature for an enterprise SaaS platform.

### IMPLEMENTATION_PLAN.md Specification

```markdown
### Feature 11: Team Management
**Priority:** HIGH
**Estimated Time:** 12-16 hours
**Compliance:** SOC2 (audit logging)

**Requirements:**
- View team members
- Invite new members (via email)
- Manage roles and permissions
- Deactivate/reactivate members
- View team activity logs
- Bulk operations (invite multiple, change roles)

**Data Models:**
```dart
class TeamMember {
  final String id;
  final String email;
  final String? name;
  final String? photoUrl;
  final TeamRole role;
  final MemberStatus status;
  final DateTime joinedAt;
  final DateTime? lastActiveAt;
}

enum TeamRole {
  owner,      // Full access
  admin,      // Manage members, settings
  member,     // Standard access
  viewer,     // Read-only
}

class TeamInvitation {
  final String id;
  final String email;
  final TeamRole role;
  final InvitationStatus status;
  final DateTime sentAt;
  final DateTime? acceptedAt;
  final DateTime expiresAt;
}

class ActivityLog {
  final String id;
  final String userId;
  final String action;
  final Map<String, dynamic> metadata;
  final DateTime timestamp;
}
```

**API Endpoints:**
- GET /api/teams/{id}/members
- POST /api/teams/{id}/invitations
- PUT /api/teams/{id}/members/{userId}/role
- DELETE /api/teams/{id}/members/{userId}
- GET /api/teams/{id}/activity-logs?page=1
```

### Expected Output

```
✅ Feature "Team Management" implemented successfully!

📊 Summary:
- Files Created: 33
- Test Coverage: 88.6%
- Compliance: SOC2 (audit logging)

🔒 SOC2 Compliance:
✅ Audit Logging:
  - All team operations logged
  - Immutable audit trail
  - 7-year retention

✅ Access Control:
  - Role-based permissions
  - Principle of least privilege
  - Owner approval for critical actions
```

---

## Summary of Examples

| Example | Industry | Complexity | Key Features | Compliance |
|---------|----------|------------|--------------|------------|
| Product Catalog | E-Commerce | Medium | Pagination, Search, Filters | - |
| Patient Records | Healthcare | High | Encryption, Audit Logging | HIPAA |
| Transaction History | FinTech | High | Tokenization, Export, Receipts | PCI-DSS |
| User Feed | Social Media | Medium | Real-time, WebSocket, Offline | - |
| Course Management | Education | Medium | Progress Tracking, Materials | - |
| Property Listings | Real Estate | Medium | Map View, Tours, Favorites | - |
| Order Tracking | Food Delivery | Medium | Real-time, Map, Driver Location | - |
| Team Management | Enterprise SaaS | High | Roles, Invitations, Activity Logs | SOC2 |

**Key Takeaways:**

1. **Compliance features automatically generated** when specified in IMPLEMENTATION_PLAN.md
2. **Real-time features** (WebSocket) supported out of the box
3. **Pagination, filtering, search** patterns consistent across all examples
4. **Security best practices** enforced (encryption, audit logging, role-based access)
5. **Test coverage** consistently 75%+ for all features
6. **Implementation time** averages 7-12 minutes per feature

---

**Last Updated:** 2025-10-24
**Version:** 1.0.0