Non-Functional Requirements

Performance

Response Time Requirements:

• NFR1: App cold start completes within 3 seconds on mobile, 2 seconds on web
• NFR2: Screen transitions complete within 300ms
• NFR3: API responses return within 2 seconds under normal load
• NFR4: Image assets load within 1 second
• NFR5: Search results display within 1 second of query submission
• NFR6: Cart operations (add, update, remove) complete within 500ms

Capacity Requirements:

• NFR7: System supports 1,000 concurrent users without performance degradation
• NFR8: System processes up to 100 orders per minute during peak times
• NFR9: Database queries complete within 100ms for standard operations

App Size:

• NFR10: Mobile app package size remains under 50MB
• NFR11: Web bundle size (gzipped) remains under 2MB

Security

Authentication & Authorization:

• NFR12: All authentication uses industry-standard protocols (OAuth 2.0, JWT)
• NFR13: Sessions expire after 30 days of inactivity
• NFR14: Failed login attempts are rate-limited (5 attempts per 15 minutes)
• NFR15: Biometric authentication available on supported devices

Data Protection:

• NFR16: All data transmitted over HTTPS/TLS 1.2+
• NFR17: Payment card data never stored locally (PCI-DSS compliance)
• NFR18: Sensitive data encrypted at rest in database
• NFR19: Personal data handling complies with Australian Privacy Principles

Access Control:

• NFR20: Role-based access control for admin, vendor, and support roles
• NFR21: API endpoints require valid authentication tokens
• NFR22: Admin actions logged for audit trail

Scalability

User Growth:

• NFR23: Architecture supports 10x user growth without re-architecture
• NFR24: Database design supports horizontal scaling
• NFR25: API design supports load balancing across multiple servers

Peak Load Handling:

• NFR26: System handles 3x normal traffic during promotional events
• NFR27: Graceful degradation when approaching capacity limits
• NFR28: Queue-based processing for non-critical operations

Reliability

Availability:

• NFR29: System availability target of 99.5% during business hours
• NFR30: Planned maintenance windows outside peak ordering hours (11am-2pm, 5pm-9pm)
• NFR31: Order submission succeeds within 3 retry attempts

Data Integrity:

• NFR32: Order data is durable once submission confirmed
• NFR33: Payment transactions are atomic (all-or-nothing)
• NFR34: Subscription schedules maintained accurately across time zones

Recovery:

• NFR35: System recovers from failures within 15 minutes
• NFR36: No data loss for confirmed orders during system failures
• NFR37: Offline-queued actions sync when connectivity restored

Accessibility

WCAG 2.1 AA Compliance:

• NFR38: All interactive elements have accessible labels
• NFR39: Color contrast ratio meets 4.5:1 minimum
• NFR40: Touch targets minimum 48x48dp on mobile
• NFR41: Screen reader compatibility (TalkBack, VoiceOver)
• NFR42: Keyboard navigation supported for web application

Inclusive Design:

• NFR43: Text resizing supported up to 200% without loss of function
• NFR44: No content relies solely on color to convey information
• NFR45: Form errors clearly identified with text, not just color

Integration

External Services:

• NFR46: Payment gateway integration with 99.9% availability
• NFR47: Google Maps integration for address and location services
• NFR48: Firebase services (Auth, FCM, Analytics) properly configured
• NFR49: Push notification delivery within 30 seconds of trigger

API Reliability:

• NFR50: External API failures handled gracefully with user-friendly messages
• NFR51: Circuit breaker pattern for failing external services
• NFR52: Retry logic with exponential backoff for transient failures

Maintainability (This Initiative)

Code Quality:

• NFR53: Code passes Flutter analyzer with zero errors
• NFR54: Test coverage exceeds 80% for critical paths
• NFR55: Build succeeds on first attempt 95% of the time

Documentation:

• NFR56: Developer setup documented with <1 hour to productive
• NFR57: API documentation covers all endpoints
• NFR58: Architecture decisions documented in docs/

Monitoring:

• NFR59: Application errors logged and accessible for debugging
• NFR60: Build and test results visible to development team