UI Design & Testing Skills

Run API integration tests against the running backend, verify endpoints return expected responses and status codes. Use after deploying a preview or starting the dev server.

Use this skill to create typed test data builders with mimicry-js and Faker for any TypeScript interface or type. Invoke whenever the user asks to generate mock data, create test fixtures, build factory functions, produce seed data, or construct fake objects for unit tests, Storybook stories, or E2E scenarios. Also use when migrating from test-data-bot or Fishery to mimicry-js, or when the user mentions builders, factories, or typed mock/fake/test/seed data generation — even if they describe the task indirectly (e.g. "I need realistic invoices for testing" or "generate sample users for my stories").

Use this skill to create or refactor React + TypeScript + Tailwind CSS + CVA components following design system conventions. It provides the canonical file structure, per-component styles pattern, types, context, store, barrel exports, and Storybook story templates that are specific to this codebase. Invoke whenever the user wants to build a new UI component, add CVA variants or sub-components, set up component context or store, create barrel exports, write component stories, or restructure an existing component directory — even for tasks that seem straightforward like "create a Button" or "add a variant", because the skill ensures correct file placement and naming conventions.

Use when implementing structured error handling in backend or frontend code. Triggers for: try-catch patterns, custom exception classes, global error handlers, error logging, user-friendly error messages, or API error responses. NOT for: business logic validation (use domain exceptions) or unrelated error types.

Build with Firestore NoSQL database - real-time sync, offline support, and scalable document storage. Use when: creating collections, querying documents, setting up security rules, handling real-time listeners, or troubleshooting permission-denied, quota exceeded, invalid query, or offline persistence errors. Prevents 10 documented errors.

Translates Figma designs into production-ready code with 1:1 visual fidelity. Use when implementing UI from Figma files, when user mentions "implement design", "generate code", "implement component", "build Figma design", provides Figma URLs, or asks to build components matching Figma specs. Requires Figma MCP server connection.

React 19 patterns and React Compiler optimization guidance. Understand when to use manual memoization vs letting the compiler optimize, and leverage new hooks like useActionState and useFormStatus.

Generate or update a project's README.md plus a ready-to-paste GitHub repository description and topics list, following the Szum-Tech documentation standard. Auto-detects project type (web app, mobile app, npm package, CLI tool, monorepo, Claude plugin) by analyzing package.json, configs, and folder structure, then confirms with the user before generating. Use whenever the user asks to "create README", "update README", "document repository", "generate project docs", "GitHub description", "GitHub topics", or invokes /repository-documentation.

Use when the user asks about "Server Actions", "form handling in Next.js", "mutations", "useFormState", "useFormStatus", "revalidatePath", "revalidateTag", or needs guidance on data mutations and form submissions in Next.js App Router.

Continuously tests and improves Claude Code skills using A/B experimentation and Auto Research ML loop. Provides quantitative metrics on skill effectiveness and automatically approves only changes that improve outcomes.

Guide for writing effective log messages using wide events / canonical log lines. Use when writing logging code, adding instrumentation, improving observability, or reviewing log statements. Teaches high-cardinality, high-dimensionality structured logging that enables debugging.

Comprehensive reference for building UI with @szum-tech/design-system — a React component library built on Tailwind CSS 4+ and Radix UI. Use this skill whenever working in a project that imports from @szum-tech/design-system, when building or reviewing UI components, when choosing colors, typography, or layout styles, when deciding which component to use, or when creating new components following this design system's patterns. Covers the full color palette (OKLCH semantic tokens), all typography utility classes, every available component with its variants and props, animation classes, icon imports, and the CVA-based styling system. Always use this skill when the user asks about design tokens, Tailwind classes, or component APIs in the context of this library.

Type-safe environment variable validation with @t3-oss/env-nextjs and Zod. Build-time validation ensures all required env vars are present and correctly typed.

Tailwind CSS v4 patterns with CSS-first configuration, @theme directive, design system integration, and utility-first styling for Next.js applications.

Cookie-based toast notification system for Next.js. Use when user asks to "show toast", "toast notification", "user feedback after action", "toast after redirect", "success message", "error message after form submit", "setToastCookie", "notify user", "flash message", "toast from server action", "show notification after redirect", "display toast after delete".

Generates and runs automated browser tests using Playwright CLI and the accessibility tree (DOM snapshot). Faster and cheaper than screenshot-based approaches. Uses semantic locators, real DOM structure, and optional Firecrawl for bot-protected pages.

Search YouTube videos by query, topic, channel, or other criteria and return links with short descriptions. Uses yt-dlp CLI (free, no API key needed). Use this skill when the user wants to find, search, or discover YouTube videos on any topic, list videos from a channel or playlist, or get video metadata like title, duration, and view count. Includes quality filtering to surface valuable content and filter out noise.

Wyszukuje dane nieruchomości po polskim numerze księgi wieczystej (KW) — adres, działki/lokal, właścicieli, prawa, roszczenia, ograniczenia i hipoteki. Używaj gdy użytkownik poda numer w formacie XX1X/XXXXXXXX/X (np. WA1M/00123456/7) lub prosi o "sprawdź księgę wieczystą", "dane z KW", "znajdź adres/właściciela/hipoteki po KW". Łączy browser automation na portalu EKW (ekw.ms.gov.pl, wymaga ręcznego rozwiązania CAPTCHA) z REST API ULDK GUGiK do wzbogacenia o geometrię działki i współrzędne.