Mobile Development Prompts

---
name: cross-platform-3d-app-development-master
description: Act as an expert in building cross-platform applications with advanced 3D design capabilities for both iOS and Android platforms.
---

Act as a Premium App Development Master. You are an expert in creating advanced cross-platform applications with 3D design capabilities for both iOS and Android platforms.

Your task is to develop a comprehensive mobile application that includes:
- Full 3D design for every page, button, and element
- Seamless functionality across both iOS and Android devices
- User-friendly interfaces with interactive 3D components
- End-to-end development from concept to deployment

You will:
- Use state-of-the-art tools and frameworks to ensure compatibility and performance
- Implement cutting-edge 3D design elements that enhance user experience
- Ensure the application meets all quality and performance standards

Rules:
- Maintain a high level of detail and precision in design and coding
- Follow best practices for cross-platform development

Variables:
- both - Target platform (iOS, Android, both)
- high - Level of design complexity
- AppStore - Preferred deployment method

# SwiftUI iOS App taste of a senior iOS developer
- Build new screens in SwiftUI and drop to UIKit only through UIViewRepresentable for gaps. Confidence: 0.85
- Use the Observation framework (@Observable) for view models on iOS 17+, not ObservableObject with @Published. Confidence: 0.85
- Keep views small and composable; extract a subview once a body passes about 50 lines. Confidence: 0.80
- Own state with @State at the lowest view that needs it and pass bindings down instead of global singletons. Confidence: 0.85
- Use Swift Concurrency (async/await, actors, structured tasks) everywhere; no new completion-handler or Combine-based APIs. Confidence: 0.85
- Start async work with the .task modifier so it is cancelled automatically when the view disappears. Confidence: 0.90
- Turn on strict concurrency checking (Swift 6 language mode) and fix Sendable warnings early. Confidence: 0.80
- Drive navigation with NavigationStack and a typed path, routed through a small coordinator or router object. Confidence: 0.80
- Inject dependencies through initializers or the Environment so previews and tests can swap in fakes. Confidence: 0.85
- Split features into local Swift packages managed by Swift Package Manager; avoid CocoaPods for new projects. Confidence: 0.85
- Give every view a #Preview with realistic sample data, including empty, loading and error states. Confidence: 0.85
- Model loading state as an enum (idle, loading, loaded, failed) rather than several booleans. Confidence: 0.90
- Use SwiftData for simple local persistence and Core Data or GRDB when you need fine-grained migrations or performance. Confidence: 0.65
- Support Dynamic Type, Dark Mode and VoiceOver labels from the first commit. Confidence: 0.90
- Use SF Symbols and semantic system colors before adding custom assets. Confidence: 0.80
- Localize with String Catalogs from day one, even for a single-language launch. Confidence: 0.75
- Unit test view models and services with Swift Testing; keep UI tests to a few critical flows. Confidence: 0.80
- Profile with Instruments before optimizing and watch for unnecessary view body recomputation. Confidence: 0.75
- Never block the main thread with networking, decoding or disk I/O. Confidence: 0.95
- Store secrets and tokens in the Keychain, never in UserDefaults or the bundle. Confidence: 0.95
- Ship through Xcode Cloud or fastlane with automatic build numbers and TestFlight for every merge to main. Confidence: 0.75
- Use a structured Logger (os.Logger) with categories instead of print statements. Confidence: 0.85

# Jetpack Compose Android App taste of an Android engineer
- Build new screens entirely in Jetpack Compose and keep Views only behind interop for legacy parts. Confidence: 0.90
- Write the whole app in Kotlin with coroutines and Flow; no new RxJava or Java code. Confidence: 0.90
- Follow unidirectional data flow: the ViewModel exposes one immutable UiState as StateFlow and receives events. Confidence: 0.90
- Collect flows in composables with collectAsStateWithLifecycle, not plain collectAsState. Confidence: 0.85
- Hoist state out of composables so most UI functions are stateless and previewable. Confidence: 0.90
- Pass a Modifier parameter as the first optional argument of every reusable composable. Confidence: 0.85
- Keep side effects in LaunchedEffect, DisposableEffect or the ViewModel, never directly in the composable body. Confidence: 0.90
- Mark UI models immutable and use stable collections so recomposition stays cheap. Confidence: 0.75
- Use Hilt for dependency injection and avoid service locators or global singletons. Confidence: 0.80
- Use the repository pattern with Room for local data and Retrofit or Ktor for the network, offline first where it matters. Confidence: 0.80
- Use type-safe Navigation Compose routes instead of string-built destinations. Confidence: 0.80
- Modularize by feature with a shared core module once the app grows past a handful of screens. Confidence: 0.70
- Manage dependencies with a Gradle version catalog and convention plugins instead of copy-pasted build files. Confidence: 0.85
- Use Material 3 with a custom theme and dynamic color, and never hardcode colors or text sizes in screens. Confidence: 0.85
- Write @Preview functions for every screen state: loading, empty, error, content, dark mode and large font. Confidence: 0.80
- Test ViewModels with Turbine and kotlinx-coroutines-test, and UI with the Compose testing APIs. Confidence: 0.85
- Add contentDescription or semantics to every meaningful image and icon button for TalkBack. Confidence: 0.90
- Use WorkManager for deferrable background work and never keep long tasks alive in a ViewModel. Confidence: 0.85
- Enable R8 with tested keep rules and ship Baseline Profiles for faster startup. Confidence: 0.80
- Run ktlint or detekt and Android Lint in CI and treat new warnings as errors. Confidence: 0.75
- Keep strings in resources from day one so localization never requires a refactor. Confidence: 0.85

# React Native App taste of a cross-platform mobile engineer
- Start new apps with Expo and the prebuild workflow instead of a bare React Native project, and eject only when a native module truly needs it. Confidence: 0.90
- Write everything in TypeScript with strict mode on, including navigation params and native module bindings. Confidence: 0.95
- Use Expo Router for file-based navigation and keep typed routes enabled so broken links fail at compile time. Confidence: 0.80
- Keep server state in TanStack Query and limit global client state to a small Zustand store for session and preferences. Confidence: 0.85
- Never store tokens in AsyncStorage; use expo-secure-store or the Keychain and Keystore for anything sensitive. Confidence: 0.95
- Render long lists with FlashList or a well-tuned FlatList with stable keys, never a ScrollView with map. Confidence: 0.90
- Run animations on the UI thread with Reanimated and gestures with react-native-gesture-handler, not the old Animated API. Confidence: 0.85
- Enable the New Architecture and Hermes by default and treat libraries that block it as tech debt. Confidence: 0.75
- Keep a single theme module for colors, spacing and typography, and support dark mode from the first screen. Confidence: 0.85
- Respect safe areas with react-native-safe-area-context instead of hardcoded padding for notches. Confidence: 0.90
- Put platform-specific code in .ios.tsx and .android.tsx files rather than scattering Platform.OS checks. Confidence: 0.70
- Ship JavaScript fixes through EAS Update with a runtime version policy, and use store releases for native changes. Confidence: 0.80
- Build and sign in CI with EAS Build so no release depends on a single laptop. Confidence: 0.85
- Test components with React Native Testing Library and query by role and text, not by testID first. Confidence: 0.80
- Cover the critical flows end to end with Maestro or Detox on real simulators in CI. Confidence: 0.75
- Add accessibilityLabel and accessibilityRole to every touchable and keep tap targets at least 44 points. Confidence: 0.90
- Handle offline as a normal state: show cached data, queue writes and retry when the connection returns. Confidence: 0.80
- Report crashes and JavaScript errors with Sentry including source maps for every release. Confidence: 0.85
- Optimize images with expo-image and caching instead of the default Image component. Confidence: 0.80
- Profile with the React Native DevTools before guessing at performance fixes. Confidence: 0.70
- Ask for permissions only at the moment a feature needs them, with a short explanation screen first. Confidence: 0.90

# Flutter App taste of a pragmatic cross-platform mobile developer
- Start on the latest stable Flutter with null safety, strict analysis options and the official lints or very_good_analysis enforced in CI. Confidence: 0.90
- Organize code by feature folders, each with its own data, domain and presentation layers, instead of one giant widgets folder. Confidence: 0.85
- Use Riverpod or Bloc for state management and pick one for the whole app instead of mixing several. Confidence: 0.80
- Keep widgets small and composable, extracting a new widget class rather than a helper method that returns widgets. Confidence: 0.85
- Mark widgets and constructors const wherever possible to cut unnecessary rebuilds. Confidence: 0.90
- Keep business logic out of build methods and out of widgets entirely. Confidence: 0.90
- Use go_router for declarative navigation with typed routes and working deep links. Confidence: 0.80
- Model data with immutable classes generated by freezed and json_serializable instead of hand-written copyWith and fromJson. Confidence: 0.80
- Wrap API access in repository classes and return typed results or exceptions, never raw response maps, to the UI. Confidence: 0.85
- Build the theme once with ThemeData and ColorScheme from Material 3, and never hard-code colors or text styles inside widgets. Confidence: 0.85
- Support dark mode, dynamic text scaling and screen readers from the first release. Confidence: 0.85
- Use flutter_localizations with ARB files for every user-facing string from day one. Confidence: 0.80
- Run heavy parsing or image work in an isolate with compute or Isolate.run so the UI thread stays smooth. Confidence: 0.85
- Profile with DevTools in profile mode on a real low-end device before calling a screen fast. Confidence: 0.85
- Use ListView.builder or slivers for long lists and never build hundreds of children eagerly. Confidence: 0.90
- Store tokens with flutter_secure_storage and keep simple settings in shared_preferences. Confidence: 0.90
- Write unit tests for logic, widget tests for screens and a few integration tests for critical flows. Confidence: 0.80
- Use golden tests for design-system widgets that must stay pixel-stable. Confidence: 0.70
- Pin dependency versions, review new packages for maintenance and platform support, and keep the list short. Confidence: 0.80
- Define flavors for development, staging and production with separate app IDs and config. Confidence: 0.85
- Build and ship releases with Fastlane or Codemagic from CI, never from a developer laptop. Confidence: 0.80
- Wire up Crashlytics or Sentry with obfuscated builds and uploaded symbol files. Confidence: 0.80