synchronize-tab-scrolling

React and Next.js performance optimization guidelines from Vercel Engineering. This skill should be used when writing, reviewing, or refactoring React/Next.js code to ensure optimal performance patterns. Triggers on tasks involving React components, Next.js pages, data fetching, bundle optimization, or performance improvements.

Internationalize JavaScript apps with i18next. Use when adding translations, handling plurals, loading locale files dynamically, or i18n for React/Vue/Node.

Perform thorough code reviews with actionable, prioritized feedback. Use when a user asks to review code, check code quality, find bugs, review a pull request, audit code for issues, or get feedback on implementation. Covers correctness, security, performance, readability, and best practices across languages.

Scan code for security vulnerabilities, misconfigurations, and exposed secrets. Use when a user asks to audit security, find vulnerabilities, check for OWASP issues, scan for secrets, review dependencies for CVEs, detect SQL injection, find XSS vulnerabilities, or harden an application. Covers OWASP Top 10, dependency auditing, secrets detection, and generates fix recommendations with severity ratings.

ESLint is the standard linting tool for JavaScript and TypeScript projects. It statically analyzes your code to find problems, enforce coding conventions, and catch bugs before they reach production. ESLint 9 introduced the flat config format, replacing the legacy `.eslintrc` system with a simpler, more composable `eslint.config.js` file. With a rich plugin ecosystem covering React, TypeScript, accessibility, and import ordering, ESLint is the backbone of code quality in modern web development.

Build cross-browser extensions with WXT — the modern framework for Chrome, Firefox, Safari, and Edge extensions. Use when someone asks to "build a browser extension", "Chrome extension with React", "WXT framework", "cross- browser extension", "manifest v3 extension", "build Firefox extension", or "browser extension with TypeScript". Covers content scripts, background workers, popup/options pages, storage, messaging, and publishing.

Audit web pages and components for WCAG 2.2 accessibility compliance. Use when a user asks to check accessibility, find a11y issues, audit for WCAG compliance, fix screen reader problems, check color contrast, ensure keyboard navigation works, or prepare for accessibility regulations like the European Accessibility Act or ADA.

Write and maintain end-to-end tests with Playwright. Use when someone asks to "add e2e tests", "test my web app", "set up Playwright", "write browser tests", "test login flow", "visual regression testing", "test across browsers", or "automate UI testing". Covers test setup, page objects, authentication, API mocking, visual comparisons, and CI integration.

Test UI components the way users interact with them using Testing Library — query by role, text, and label instead of implementation details. Use when someone asks to "test React components", "Testing Library", "user-centric testing", "test accessibility", "test without implementation details", or "render and query components in tests". Covers React Testing Library, queries, user events, async testing, and accessibility assertions.

Assists with configuring and using Vite as a frontend build tool for modern web applications. Use when setting up dev servers, optimizing production builds, configuring plugins, migrating from Webpack or CRA, or building component libraries. Trigger words: vite, build tool, HMR, hot module replacement, vite config, rollup, bundling.

Assists with unit and integration testing using Vitest, a Vite-native test runner. Use when writing tests, configuring mocks, setting up coverage, or migrating from Jest. Trigger words: vitest, unit testing, test runner, vi.fn, vi.mock, test coverage, jest replacement.

Expert guidance for integrating and building applications with shadcn/ui components, including component discovery, installation, customization, and best practices.

Build UIs with Tailwind CSS — utility classes, responsive design, dark mode, custom configuration, component patterns, animations, plugins, and design system setup. Use when tasks involve styling web applications, configuring design tokens, building responsive layouts, or migrating from other CSS approaches.