litskills

Universal coding standards for implementation, code quality, testing, and refactoring. Covers anti-patterns, type safety, debugging, Red-Green-Refactor development, test design, code duplication (Rule of Three), decision frameworks, and impact analysis. Use when implementing features, reviewing code quality, fixing bugs, or refactoring.

Enforce unidirectional flow: state → UI (selectors) → actions → updates. Prevent direct store access from components, use granular selectors, implement reselect for complex filtering/sorting/aggregation. Use when designing component data flow or optimizing re-renders.

Implement error handling: try-catch at boundaries, typed errors with instanceof checks, error state in store, error boundaries for components, exponential backoff retry with jitter, Sentry monitoring in production, user-friendly error messages. Use when implementing API calls, form submissions, or component error boundaries.

Implement state management: Zustand slices pattern, manual immutable updates with spread operators, middleware stack (devtools, subscribeWithSelector), Immer decision matrix (4+ spreads → use Immer), transient updates for 10+ updates/sec. Use when implementing stores or managing complex state.

Frontend technical design rules including environment variables, architecture design, data flow, Nx workspace conventions, and build/testing commands.

Enforce type safety: Zod runtime validation at boundaries, type guards for discriminated unions, avoid any/unknown, validate before asserting. Optimize Zod with .pick()/.partial() on hot paths. Use when implementing API integrations, form handling, or state management with strict typing.

React/TypeScript frontend development rules including type safety, component design, state management, and error handling.

Frontend testing rules with Jest, React Testing Library, and MSW. Includes coverage requirements, test design principles, and quality criteria.

Build LangGraph agents: StateGraph with Annotation.Root, multi-tier orchestration (main/sub-agents), node patterns (pure/async/injectable), routers (intent/mode/error-aware/confidence), error-resilient nodes, streaming with async generators, batch processing, LLM fallbacks. Use when designing or implementing AI agents.

Manage LangGraph state: Annotation.Root with custom reducers (concatenate arrays, keep latest, deduplicate by ID, merge objects, conditional logic). Prefer flat state, use discriminated unions for variants. Validate with Zod guards. Version state for migrations. Use when building LangGraph agents.