android-development
Android development guidelines for Kotlin with clean architecture, MVI pattern, Material Design, and best practices for building robust mobile applications
What this skill does
# Android Development Best Practices ## General Kotlin Guidelines ### Basic Principles - Use English for all code and documentation - Always declare variable and function types explicitly - Avoid the `any` type; create necessary custom types - Eliminate blank lines within function bodies ### Naming Standards - **PascalCase**: Classes, interfaces, enums - **camelCase**: Variables, functions, methods - **underscores_case**: Files and directories - **UPPERCASE**: Environment variables, constants - Avoid magic numbers; define constants instead - Functions should start with action verbs - Boolean variables use prefixes: `isLoading`, `hasError`, `canDelete` ### Function Design - Keep functions under 20 instructions with single responsibility - Use verb-based naming - Prefix boolean returns with `is`, `has`, or `can` - Prefix void returns with `execute`, `save`, `send` - Combat nesting through early returns, utility extraction, and higher-order functions - Use default parameters instead of null checks - Consolidate parameters into objects (RO-RO pattern) ### Data and Classes - Employ data classes for data structures - Encapsulate primitives in composite types; validate internally - Favor immutability; use `val` for unchanging values - Follow SOLID principles; prefer composition over inheritance - Keep classes under 200 instructions, 10 public methods, 10 properties ### Exception Handling - Reserve exceptions for unexpected errors - Catch exceptions only to fix anticipated issues or add context - Create custom exception types for domain errors ## Android Architecture ### Clean Architecture - Implement clean architecture with clear layer separation - Use repository pattern for data persistence and caching - Keep business logic in Use Cases or Interactors - Separate concerns between UI, domain, and data layers ### Project Structure ``` app/ ├── data/ # Data sources, repositories, models ├── domain/ # Use cases, domain models, interfaces ├── presentation/ # UI components, ViewModels, state └── di/ # Dependency injection modules ``` ### MVI Pattern - Deploy MVI pattern for state and event management - ViewModels manage UI state as a single immutable state object - UI components observe state and render accordingly - Handle user intents/events through a single entry point - Keep side effects predictable and traceable ## UI Development ### Navigation - Use Navigation Component for fragment and activity routing - Define navigation graph for app flow - Handle deep links through Navigation Component - Implement safe args for type-safe navigation arguments ### Main Activity Structure - MainActivity manages primary navigation - Use BottomNavigationView for main destinations (Home, Profile, Settings, etc.) - Handle navigation state properly across configuration changes ### View Binding and State - Use ViewBinding for type-safe view access - Use Flow or LiveData for UI state management - Observe state changes in lifecycle-aware manner - Handle loading, error, and success states consistently ### UI Framework Preferences - Prefer XML layouts and Fragments over Jetpack Compose (unless Compose is specifically required) - Use ConstraintLayout for complex layouts - Apply Material 3 design guidelines - Follow responsive design practices for different screen sizes ## Authentication Flow Structure authentication screens properly: 1. Splash Screen - Initial app launch 2. Login Screen - User authentication 3. Register Screen - New user registration 4. Forgot Password Screen - Password recovery 5. Verify Email Screen - Email verification ## Testing ### Unit Testing - Follow Arrange-Act-Assert conventions - Test ViewModels, Use Cases, and Repositories - Use test doubles for dependencies - Achieve good coverage of business logic ### UI Testing - Implement widget testing for UI components - Write integration tests for API modules - Test navigation flows - Use Espresso for instrumented tests ## Best Practices ### Lifecycle Management - Handle lifecycle events properly - Avoid memory leaks from improper lifecycle handling - Use lifecycle-aware components ### Background Processing - Use Coroutines for async operations - Handle cancellation properly - Use WorkManager for deferrable background work ### Dependency Injection - Use Hilt or Dagger for dependency injection - Scope dependencies appropriately - Keep DI configuration organized ### Performance - Avoid work on the main thread - Optimize RecyclerView with DiffUtil - Use lazy loading for heavy resources - Profile and optimize memory usage
Related in Design
contribute
IncludedLocal-only OSS contribution command center. Auto-refreshes the user's in-flight PR and issue state on invoke so conversations start with full context — no need to brief Claude on what's in flight. Helps the user find issues to contribute to on GitHub, builds per-repo dossiers of what each upstream expects (CLA, DCO, branch convention, AI policy, draft-first, review bots, issue templates), runs deterministic gates before any external action so AI-assisted contributions don't reach maintainers as slop. State is markdown-only: candidate files at ~/.contribute-system/candidates/, repo dossiers at ~/.contribute-system/research/, append-only event log at ~/.contribute-system/log.jsonl. No database, no cloud calls. Use when the user asks about their PRs / issues / contributions, wants to find new work to take on, claim an issue, build/refresh a repo's dossier, or draft a Design Issue or PR. Trigger with "/contribute", "what's my PR status", "find a contribution", "claim issue X", "draft a Design Issue for Y", "refresh dossier for Z".
architectural-analysis
IncludedUser-triggered deep architectural analysis of a codebase or scoped subtree across eight modes — information architecture, data flow, integration points, UI surfaces, interaction patterns, data model, control flow, and failure modes. This skill should be used when the user asks to "diagram this codebase," "map the architecture," "show the data flow," "give me an ERD," "trace control flow," "find the integration points," "verify the layout pattern," "audit the UX architecture," or any similar request whose primary deliverable is mermaid diagrams plus cited reports under docs/architecture/. Dispatches haiku/sonnet sub-agents in parallel for per-mode exploration, then verifies every citation mechanically before any node lands in a diagram. Not for one-off prose explanations of code (use code-explanation) or for high-level system design from scratch (use system-design).
mcp
IncludedModel Context Protocol (MCP) server development and tool management. Languages: Python, TypeScript. Capabilities: build MCP servers, integrate external APIs, discover/execute MCP tools, manage multi-server configs, design agent-centric tools. Actions: create, build, integrate, discover, execute, configure MCP servers/tools. Keywords: MCP, Model Context Protocol, MCP server, MCP tool, stdio transport, SSE transport, tool discovery, resource provider, prompt template, external API integration, Gemini CLI MCP, Claude MCP, agent tools, tool execution, server config. Use when: building MCP servers, integrating external APIs as MCP tools, discovering available MCP tools, executing MCP capabilities, configuring multi-server setups, designing tools for AI agents.
react-native-skia
IncludedDesign, build, debug, and optimise high-polish animated graphics in React Native or Expo using @shopify/react-native-skia, Reanimated, and Gesture Handler. Use when the user wants canvas-driven UI, shaders, paths, rich text, image filters, sprite fields, Skottie, video frames, snapshots, web CanvasKit setup, or performance tuning for custom motion-heavy elements such as loaders, hero art, cards, charts, progress indicators, particle systems, or gesture-driven surfaces. Also use when the user asks for fluid, glow, glass, blob, parallax, 60fps/120fps, or GPU-friendly animated effects in React Native, even if they do not explicitly say "Skia". Do not use for ordinary form/layout work with standard views.
plaid
IncludedProduct Led AI Development — guides founders from idea to launched product. Six capabilities: Idea (discover a product idea), Validate (pressure-test the idea against fatal flaws, problem reality, competition, and 2-week MVP feasibility), Plan (vision intake + document generation), Design (translate image references into a design.md spec), Launch (go-to-market strategy), and Build (roadmap execution). Use when someone says "PLAID", "plaid idea", "help me find an idea", "product idea", "idea from my business", "idea from my expertise", "plaid validate", "validate my idea", "pressure-test", "is this idea good", "find fatal flaws", "validate the problem", "plan a product", "define my vision", "generate a PRD", "product strategy", "plaid design", "design from image", "translate image to design", "create design.md", "extract design tokens", "plaid launch", "go-to-market", "launch plan", "GTM strategy", "launch playbook", "plaid build", "build the app", "start building", or "execute the roadmap".
nextjs-framer-motion-animations
IncludedAdds production-safe Motion for React or Framer Motion animations to Next.js apps, including reveal, hover and tap micro-interactions, whileInView, stagger, AnimatePresence, layout and layoutId transitions, reorder, scroll-linked UI, and lightweight route-content transitions. Use when the user asks to add, refactor, or debug Motion or Framer Motion in App Router or Pages Router codebases, especially around server/client boundaries, reduced motion, LazyMotion, bundle size, hydration, or route transitions. Avoid for GSAP-style timelines, WebGL or 3D scenes, heavy scroll storytelling, or CSS-only effects unless Motion is explicitly requested.