# AI_Implementation.md

## How This App Was Architected & Built

This project was developed following strict senior-level iOS engineering standards, with guidance from an AI assistant (Grok) acting as a Senior iOS Engineer specializing in SwiftUI and modern Apple frameworks.

### Guiding Principles (from AGENTS.md)
- **Protocol-Oriented Programming (POP) first**: All shared capabilities defined via protocols before concrete types
- **MVVM-lite**: Views are "dumb" — all logic lives in `@Observable` view models
- **No third-party dependencies**: Pure Apple frameworks only (SwiftUI, AVFoundation, StoreKit 2, CoreImage)
- **No magic numbers**: All dimensions, opacities, durations from centralized `Design` constants
- **Full accessibility**: Dynamic Type, VoiceOver labels/hints/traits/announcements
- **Modern Swift & SwiftUI**: Swift 6 concurrency, `@MainActor`, `foregroundStyle`, `clipShape(.rect)`, `NavigationStack`
- **Testable & reusable design**: Protocols enable mocking and future SPM package extraction

### Architecture Overview

Shared/
├── DesignConstants.swift             → Semantic design tokens (spacing, radii, sizes, etc.)
├── Color+Extensions.swift            → Ring light color presets
├── Protocols/
│   ├── RingLightConfigurable.swift   → Border, color, brightness, mirror, smoothing
│   ├── CaptureControlling.swift      → Timer, grid, zoom, capture mode
│   └── PremiumManaging.swift         → Subscription state & purchase handling
└── Premium/
└── PremiumManager.swift          → Native StoreKit 2 implementation
Features/
├── Camera/                           → Main UI, preview, capture logic
├── Settings/                         → Configuration screens
└── Paywall/                          → Pro subscription flow


### Key Implementation Decisions

1. **Ring Light Effect**
   - Achieved by coloring the safe area background and leaving a centered rectangular window for camera preview
   - Border width controlled via user setting
   - Gradient support added for directional "portrait lighting"

2. **Camera System**
   - `AVCaptureSession` with front camera default
   - `UIViewRepresentable` wrapper for preview with pinch-to-zoom
   - Video data output delegate for future real-time filters (skin smoothing placeholder)

3. **Capture Enhancements**
   - Timer with async countdown and accessibility announcements
   - Volume button observation via KVO on `AVAudioSession.outputVolume`
   - Flash burst: temporarily sets brightness to 1.0 on capture

4. **Freemium Model**
   - Built with pure StoreKit 2 (no RevenueCat)
   - `PremiumManaging` protocol enables easy testing/mocking
   - Clean paywall with benefit list and native purchase flow

5. **Reusability Focus**
   - All shared logic extracted to protocols
   - Ready for future extraction into SPM packages:
     - `SelfieCameraKit`
     - `SelfieRingLightKit`
     - `SelfiePremiumKit`

### Development Process
- Iterative feature additions guided by competitive analysis of top App Store selfie apps
- Each new capability (timer, boomerang, gradient, subscriptions) added with protocol-first design
- Strict adherence to no magic numbers, full accessibility, and clean separation
- Final structure optimized for maintainability and future library extraction

This app demonstrates production-quality SwiftUI architecture while delivering a delightful, competitive user experience.