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tech-leads-club/best-practices

Name: best-practices
Author: tech-leads-club

packages/skills-catalog/skills/(quality)/web-best-practices/SKILL.md

npx skillsauth add tech-leads-club/agent-skills best-practices

Clean

TrivyContainer and dependency vulnerability scanner

Clean

SemgrepStatic code analysis for vulnerabilities

Clean

mcp-scan (Snyk)Model Context Protocol security validation

Skipped

Snyk (dep)Open source security scanning

Skipped

Socket.devSupply chain security analysis

Skipped

VirusTotalMulti-engine malware detection

Skipped

CrowdStrikeAdvanced threat intelligence

Skipped

OSV-ScannerOpen Source Vulnerability database check

Skipped

OWASP Dep-Check

Best practices

Modern web development standards based on Lighthouse best practices audits. Covers security, browser compatibility, and code quality patterns.

Security

HTTPS everywhere

Enforce HTTPS:

<!-- ❌ Mixed content -->
<img src="http://example.com/image.jpg" />
<script src="http://cdn.example.com/script.js"></script>

<!-- ✅ HTTPS only -->
<img src="https://example.com/image.jpg" />
<script src="https://cdn.example.com/script.js"></script>

<!-- ✅ Protocol-relative (will use page's protocol) -->
<img src="//example.com/image.jpg" />

HSTS Header:

Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

Content Security Policy (CSP)

<!-- Basic CSP via meta tag -->
<meta
  http-equiv="Content-Security-Policy"
  content="default-src 'self'; 
               script-src 'self' https://trusted-cdn.com; 
               style-src 'self' 'unsafe-inline';
               img-src 'self' data: https:;
               connect-src 'self' https://api.example.com;"
/>

<!-- Better: HTTP header -->

CSP Header (recommended):

Content-Security-Policy:
  default-src 'self';
  script-src 'self' 'nonce-abc123' https://trusted.com;
  style-src 'self' 'nonce-abc123';
  img-src 'self' data: https:;
  connect-src 'self' https://api.example.com;
  frame-ancestors 'self';
  base-uri 'self';
  form-action 'self';

Using nonces for inline scripts:

<script nonce="abc123">
  // This inline script is allowed
</script>

Security headers

# Prevent clickjacking
X-Frame-Options: DENY

# Prevent MIME type sniffing
X-Content-Type-Options: nosniff

# Enable XSS filter (legacy browsers)
X-XSS-Protection: 1; mode=block

# Control referrer information
Referrer-Policy: strict-origin-when-cross-origin

# Permissions policy (formerly Feature-Policy)
Permissions-Policy: geolocation=(), microphone=(), camera=()

No vulnerable libraries

# Check for vulnerabilities
npm audit
yarn audit

# Auto-fix when possible
npm audit fix

# Check specific package
npm ls lodash

Keep dependencies updated:

// package.json
{
  "scripts": {
    "audit": "npm audit --audit-level=moderate",
    "update": "npm update && npm audit fix"
  }
}

Known vulnerable patterns to avoid:

// ❌ Prototype pollution vulnerable patterns
Object.assign(target, userInput)
_.merge(target, userInput)

// ✅ Safer alternatives
const safeData = JSON.parse(JSON.stringify(userInput))

Input sanitization

// ❌ XSS vulnerable
element.innerHTML = userInput
document.write(userInput)

// ✅ Safe text content
element.textContent = userInput

// ✅ If HTML needed, sanitize
import DOMPurify from 'dompurify'
element.innerHTML = DOMPurify.sanitize(userInput)

Secure cookies

// ❌ Insecure cookie
document.cookie = "session=abc123";

// ✅ Secure cookie (server-side)
Set-Cookie: session=abc123; Secure; HttpOnly; SameSite=Strict; Path=/

Browser compatibility

Doctype declaration

<!-- ❌ Missing or invalid doctype -->
<html lang="en">
  <head>
    <title>Page</title>
  </head>
  <body></body>
</html>

<!-- ✅ HTML5 doctype -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Page</title>
  </head>
  <body></body>
</html>

Character encoding

<!-- ❌ Missing or late charset -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Page</title>
    <meta charset="UTF-8" />
  </head>
  <body></body>
</html>

<!-- ✅ Charset as first element in head -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>Page</title>
  </head>
  <body></body>
</html>

Viewport meta tag

<!-- ❌ Missing viewport -->
<head>
  <title>Page</title>
</head>

<!-- ✅ Responsive viewport -->
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <title>Page</title>
</head>

Feature detection

// ❌ Browser detection (brittle)
if (navigator.userAgent.includes('Chrome')) {
  // Chrome-specific code
}

// ✅ Feature detection
if ('IntersectionObserver' in window) {
  // Use IntersectionObserver
} else {
  // Fallback
}

// ✅ Using @supports in CSS
@supports (display: grid) {
  .container {
    display: grid;
  }
}

@supports not (display: grid) {
  .container {
    display: flex;
  }
}

Polyfills (when needed)

<!-- Load polyfills conditionally -->
<script>
  if (!('fetch' in window)) {
    document.write('<script src="/polyfills/fetch.js"><\/script>')
  }
</script>

<!-- Or use polyfill.io -->
<script src="https://polyfill.io/v3/polyfill.min.js?features=fetch,IntersectionObserver"></script>

Deprecated APIs

Avoid these

// ❌ document.write (blocks parsing)
document.write('<script src="..."></script>');

// ✅ Dynamic script loading
const script = document.createElement('script');
script.src = '...';
document.head.appendChild(script);

// ❌ Synchronous XHR (blocks main thread)
const xhr = new XMLHttpRequest();
xhr.open('GET', url, false); // false = synchronous

// ✅ Async fetch
const response = await fetch(url);

// ❌ Application Cache (deprecated)
<html manifest="cache.manifest">

// ✅ Service Workers
if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('/sw.js');
}

Event listener passive

// ❌ Non-passive touch/wheel (may block scrolling)
element.addEventListener('touchstart', handler)
element.addEventListener('wheel', handler)

// ✅ Passive listeners (allows smooth scrolling)
element.addEventListener('touchstart', handler, { passive: true })
element.addEventListener('wheel', handler, { passive: true })

// ✅ If you need preventDefault, be explicit
element.addEventListener('touchstart', handler, { passive: false })

Console & errors

No console errors

// ❌ Errors in production
console.log('Debug info') // Remove in production
throw new Error('Unhandled') // Catch all errors

// ✅ Proper error handling
try {
  riskyOperation()
} catch (error) {
  // Log to error tracking service
  errorTracker.captureException(error)
  // Show user-friendly message
  showErrorMessage('Something went wrong. Please try again.')
}

Error boundaries (React)

class ErrorBoundary extends React.Component {
  state = { hasError: false }

  static getDerivedStateFromError(error) {
    return { hasError: true }
  }

  componentDidCatch(error, info) {
    errorTracker.captureException(error, { extra: info })
  }

  render() {
    if (this.state.hasError) {
      return <FallbackUI />
    }
    return this.props.children
  }
}

// Usage
;<ErrorBoundary>
  <App />
</ErrorBoundary>

Global error handler

// Catch unhandled errors
window.addEventListener('error', (event) => {
  errorTracker.captureException(event.error)
})

// Catch unhandled promise rejections
window.addEventListener('unhandledrejection', (event) => {
  errorTracker.captureException(event.reason)
})

Source maps

Production configuration

// ❌ Source maps exposed in production
// webpack.config.js
module.exports = {
  devtool: 'source-map', // Exposes source code
}

// ✅ Hidden source maps (uploaded to error tracker)
module.exports = {
  devtool: 'hidden-source-map',
}

// ✅ Or no source maps in production
module.exports = {
  devtool: process.env.NODE_ENV === 'production' ? false : 'source-map',
}

Performance best practices

Avoid blocking patterns

// ❌ Blocking script
<script src="heavy-library.js"></script>

// ✅ Deferred script
<script defer src="heavy-library.js"></script>

// ❌ Blocking CSS import
@import url('other-styles.css');

// ✅ Link tags (parallel loading)
<link rel="stylesheet" href="styles.css">
<link rel="stylesheet" href="other-styles.css">

Efficient event handlers

// ❌ Handler on every element
items.forEach((item) => {
  item.addEventListener('click', handleClick)
})

// ✅ Event delegation
container.addEventListener('click', (e) => {
  if (e.target.matches('.item')) {
    handleClick(e)
  }
})

Memory management

// ❌ Memory leak (never removed)
const handler = () => {
  /* ... */
}
window.addEventListener('resize', handler)

// ✅ Cleanup when done
const handler = () => {
  /* ... */
}
window.addEventListener('resize', handler)

// Later, when component unmounts:
window.removeEventListener('resize', handler)

// ✅ Using AbortController
const controller = new AbortController()
window.addEventListener('resize', handler, { signal: controller.signal })

// Cleanup:
controller.abort()

Code quality

Valid HTML

<!-- ❌ Invalid HTML -->
<div id="header">
  <div id="header">
    <!-- Duplicate ID -->
  </div>

  <ul>
    <div>Item</div>
    <!-- Invalid child -->
  </ul>

  <a href="/"><button>Click</button></a>
  <!-- Invalid nesting -->
</div>

<!-- ✅ Valid HTML -->
<header id="site-header"></header>

<ul>
  <li>Item</li>
</ul>

<a href="/" class="button">Click</a>

Semantic HTML

<!-- ❌ Non-semantic -->
<div class="header">
  <div class="nav">
    <div class="nav-item">Home</div>
  </div>
</div>
<div class="main">
  <div class="article">
    <div class="title">Headline</div>
  </div>
</div>

<!-- ✅ Semantic HTML5 -->
<header>
  <nav>
    <a href="/">Home</a>
  </nav>
</header>
<main>
  <article>
    <h1>Headline</h1>
  </article>
</main>

Image aspect ratios

<!-- ❌ Distorted images -->
<img src="photo.jpg" width="300" height="100" />
<!-- If actual ratio is 4:3, this squishes the image -->

<!-- ✅ Preserve aspect ratio -->
<img src="photo.jpg" width="300" height="225" />
<!-- Actual 4:3 dimensions -->

<!-- ✅ CSS object-fit for flexibility -->
<img src="photo.jpg" style="width: 300px; height: 200px; object-fit: cover;" />

Permissions & privacy

Request permissions properly

// ❌ Request on page load (bad UX, often denied)
navigator.geolocation.getCurrentPosition(success, error)

// ✅ Request in context, after user action
findNearbyButton.addEventListener('click', async () => {
  // Explain why you need it
  if (await showPermissionExplanation()) {
    navigator.geolocation.getCurrentPosition(success, error)
  }
})

Permissions policy

<!-- Restrict powerful features -->
<meta http-equiv="Permissions-Policy" content="geolocation=(), camera=(), microphone=()" />

<!-- Or allow for specific origins -->
<meta http-equiv="Permissions-Policy" content="geolocation=(self 'https://maps.example.com')" />

Audit checklist

Security (critical)

[ ] HTTPS enabled, no mixed content
[ ] No vulnerable dependencies (npm audit)
[ ] CSP headers configured
[ ] Security headers present
[ ] No exposed source maps

Compatibility

[ ] Valid HTML5 doctype
[ ] Charset declared first in head
[ ] Viewport meta tag present
[ ] No deprecated APIs used
[ ] Passive event listeners for scroll/touch

Code quality

[ ] No console errors
[ ] Valid HTML (no duplicate IDs)
[ ] Semantic HTML elements used
[ ] Proper error handling
[ ] Memory cleanup in components

UX

[ ] No intrusive interstitials
[ ] Permission requests in context
[ ] Clear error messages
[ ] Appropriate image aspect ratios

Tools

| Tool | Purpose | | -------------------------------------------------- | -------------------------- | | npm audit | Dependency vulnerabilities | | SecurityHeaders.com | Header analysis | | W3C Validator | HTML validation | | Lighthouse | Best practices audit | | Observatory | Security scan |

References

MDN Web Security
OWASP Top 10
Web Quality Audit

tech-leads-club/best-practices

packages/skills-catalog/skills/(quality)/web-best-practices/SKILL.md

Apply modern web development best practices for security, compatibility, and code quality. Use when asked to "apply best practices", "security audit", "modernize code", "code quality review", or "check for vulnerabilities". Do NOT use for accessibility (use web-accessibility), SEO (use seo), performance (use core-web-vitals), or comprehensive multi-area audits (use web-quality-audit).

4,574 stars

development

Updated Jun 12, 2026

$ install --global

skillsauth

npx skillsauth add tech-leads-club/agent-skills best-practices

Install this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.

Security Scan Results

3 of 9 scanners reported clean

Some scanners were skipped, did not run, or reported a non-clean status. Review each row below.

Scanners Passed

Scanners in report

Clean

TrivyContainer and dependency vulnerability scanner

95%

Clean

SemgrepStatic code analysis for vulnerabilities

95%

Clean

mcp-scan (Snyk)Model Context Protocol security validation

95%

Skipped

Snyk (dep)Open source security scanning

50%

Skipped

Socket.devSupply chain security analysis

50%

Skipped

VirusTotalMulti-engine malware detection

50%

Skipped

CrowdStrikeAdvanced threat intelligence

50%

Skipped

OSV-ScannerOpen Source Vulnerability database check

50%

Skipped

OWASP Dep-Check

50%

Last scanned: Jun 12, 2026, 5:01 AM61.8s1 file scanned

SKILL.md

name:: best-practices
description:: Apply modern web development best practices for security, compatibility, and code quality. Use when asked to "apply best practices", "security audit", "modernize code", "code quality review", or "check for vulnerabilities". Do NOT use for accessibility (use web-accessibility), SEO (use seo), performance (use core-web-vitals), or comprehensive multi-area audits (use web-quality-audit).
license:: MIT
author:: web-quality-skills
version:: 1.0

Best practices

Modern web development standards based on Lighthouse best practices audits. Covers security, browser compatibility, and code quality patterns.

Security

HTTPS everywhere

Enforce HTTPS:

<!-- ❌ Mixed content -->
<img src="http://example.com/image.jpg" />
<script src="http://cdn.example.com/script.js"></script>

<!-- ✅ HTTPS only -->
<img src="https://example.com/image.jpg" />
<script src="https://cdn.example.com/script.js"></script>

<!-- ✅ Protocol-relative (will use page's protocol) -->
<img src="//example.com/image.jpg" />

HSTS Header:

Strict-Transport-Security: max-age=31536000; includeSubDomains; preload

Content Security Policy (CSP)

<!-- Basic CSP via meta tag -->
<meta
  http-equiv="Content-Security-Policy"
  content="default-src 'self'; 
               script-src 'self' https://trusted-cdn.com; 
               style-src 'self' 'unsafe-inline';
               img-src 'self' data: https:;
               connect-src 'self' https://api.example.com;"
/>

<!-- Better: HTTP header -->

CSP Header (recommended):

Content-Security-Policy:
  default-src 'self';
  script-src 'self' 'nonce-abc123' https://trusted.com;
  style-src 'self' 'nonce-abc123';
  img-src 'self' data: https:;
  connect-src 'self' https://api.example.com;
  frame-ancestors 'self';
  base-uri 'self';
  form-action 'self';

Using nonces for inline scripts:

<script nonce="abc123">
  // This inline script is allowed
</script>

Security headers

# Prevent clickjacking
X-Frame-Options: DENY

# Prevent MIME type sniffing
X-Content-Type-Options: nosniff

# Enable XSS filter (legacy browsers)
X-XSS-Protection: 1; mode=block

# Control referrer information
Referrer-Policy: strict-origin-when-cross-origin

# Permissions policy (formerly Feature-Policy)
Permissions-Policy: geolocation=(), microphone=(), camera=()

No vulnerable libraries

# Check for vulnerabilities
npm audit
yarn audit

# Auto-fix when possible
npm audit fix

# Check specific package
npm ls lodash

Keep dependencies updated:

// package.json
{
  "scripts": {
    "audit": "npm audit --audit-level=moderate",
    "update": "npm update && npm audit fix"
  }
}

Known vulnerable patterns to avoid:

// ❌ Prototype pollution vulnerable patterns
Object.assign(target, userInput)
_.merge(target, userInput)

// ✅ Safer alternatives
const safeData = JSON.parse(JSON.stringify(userInput))

Input sanitization

// ❌ XSS vulnerable
element.innerHTML = userInput
document.write(userInput)

// ✅ Safe text content
element.textContent = userInput

// ✅ If HTML needed, sanitize
import DOMPurify from 'dompurify'
element.innerHTML = DOMPurify.sanitize(userInput)

Secure cookies

// ❌ Insecure cookie
document.cookie = "session=abc123";

// ✅ Secure cookie (server-side)
Set-Cookie: session=abc123; Secure; HttpOnly; SameSite=Strict; Path=/

Browser compatibility

Doctype declaration

<!-- ❌ Missing or invalid doctype -->
<html lang="en">
  <head>
    <title>Page</title>
  </head>
  <body></body>
</html>

<!-- ✅ HTML5 doctype -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Page</title>
  </head>
  <body></body>
</html>

Character encoding

<!-- ❌ Missing or late charset -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Page</title>
    <meta charset="UTF-8" />
  </head>
  <body></body>
</html>

<!-- ✅ Charset as first element in head -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>Page</title>
  </head>
  <body></body>
</html>

Viewport meta tag

<!-- ❌ Missing viewport -->
<head>
  <title>Page</title>
</head>

<!-- ✅ Responsive viewport -->
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <title>Page</title>
</head>

Feature detection

// ❌ Browser detection (brittle)
if (navigator.userAgent.includes('Chrome')) {
  // Chrome-specific code
}

// ✅ Feature detection
if ('IntersectionObserver' in window) {
  // Use IntersectionObserver
} else {
  // Fallback
}

// ✅ Using @supports in CSS
@supports (display: grid) {
  .container {
    display: grid;
  }
}

@supports not (display: grid) {
  .container {
    display: flex;
  }
}

Polyfills (when needed)

<!-- Load polyfills conditionally -->
<script>
  if (!('fetch' in window)) {
    document.write('<script src="/polyfills/fetch.js"><\/script>')
  }
</script>

<!-- Or use polyfill.io -->
<script src="https://polyfill.io/v3/polyfill.min.js?features=fetch,IntersectionObserver"></script>

Deprecated APIs

Avoid these

// ❌ document.write (blocks parsing)
document.write('<script src="..."></script>');

// ✅ Dynamic script loading
const script = document.createElement('script');
script.src = '...';
document.head.appendChild(script);

// ❌ Synchronous XHR (blocks main thread)
const xhr = new XMLHttpRequest();
xhr.open('GET', url, false); // false = synchronous

// ✅ Async fetch
const response = await fetch(url);

// ❌ Application Cache (deprecated)
<html manifest="cache.manifest">

// ✅ Service Workers
if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('/sw.js');
}

Event listener passive

// ❌ Non-passive touch/wheel (may block scrolling)
element.addEventListener('touchstart', handler)
element.addEventListener('wheel', handler)

// ✅ Passive listeners (allows smooth scrolling)
element.addEventListener('touchstart', handler, { passive: true })
element.addEventListener('wheel', handler, { passive: true })

// ✅ If you need preventDefault, be explicit
element.addEventListener('touchstart', handler, { passive: false })

Console & errors

No console errors

// ❌ Errors in production
console.log('Debug info') // Remove in production
throw new Error('Unhandled') // Catch all errors

// ✅ Proper error handling
try {
  riskyOperation()
} catch (error) {
  // Log to error tracking service
  errorTracker.captureException(error)
  // Show user-friendly message
  showErrorMessage('Something went wrong. Please try again.')
}

Error boundaries (React)

class ErrorBoundary extends React.Component {
  state = { hasError: false }

  static getDerivedStateFromError(error) {
    return { hasError: true }
  }

  componentDidCatch(error, info) {
    errorTracker.captureException(error, { extra: info })
  }

  render() {
    if (this.state.hasError) {
      return <FallbackUI />
    }
    return this.props.children
  }
}

// Usage
;<ErrorBoundary>
  <App />
</ErrorBoundary>

Global error handler

// Catch unhandled errors
window.addEventListener('error', (event) => {
  errorTracker.captureException(event.error)
})

// Catch unhandled promise rejections
window.addEventListener('unhandledrejection', (event) => {
  errorTracker.captureException(event.reason)
})

Source maps

Production configuration

// ❌ Source maps exposed in production
// webpack.config.js
module.exports = {
  devtool: 'source-map', // Exposes source code
}

// ✅ Hidden source maps (uploaded to error tracker)
module.exports = {
  devtool: 'hidden-source-map',
}

// ✅ Or no source maps in production
module.exports = {
  devtool: process.env.NODE_ENV === 'production' ? false : 'source-map',
}

Performance best practices

Avoid blocking patterns

// ❌ Blocking script
<script src="heavy-library.js"></script>

// ✅ Deferred script
<script defer src="heavy-library.js"></script>

// ❌ Blocking CSS import
@import url('other-styles.css');

// ✅ Link tags (parallel loading)
<link rel="stylesheet" href="styles.css">
<link rel="stylesheet" href="other-styles.css">

Efficient event handlers

// ❌ Handler on every element
items.forEach((item) => {
  item.addEventListener('click', handleClick)
})

// ✅ Event delegation
container.addEventListener('click', (e) => {
  if (e.target.matches('.item')) {
    handleClick(e)
  }
})

Memory management

// ❌ Memory leak (never removed)
const handler = () => {
  /* ... */
}
window.addEventListener('resize', handler)

// ✅ Cleanup when done
const handler = () => {
  /* ... */
}
window.addEventListener('resize', handler)

// Later, when component unmounts:
window.removeEventListener('resize', handler)

// ✅ Using AbortController
const controller = new AbortController()
window.addEventListener('resize', handler, { signal: controller.signal })

// Cleanup:
controller.abort()

Code quality

Valid HTML

<!-- ❌ Invalid HTML -->
<div id="header">
  <div id="header">
    <!-- Duplicate ID -->
  </div>

  <ul>
    <div>Item</div>
    <!-- Invalid child -->
  </ul>

  <a href="/"><button>Click</button></a>
  <!-- Invalid nesting -->
</div>

<!-- ✅ Valid HTML -->
<header id="site-header"></header>

<ul>
  <li>Item</li>
</ul>

<a href="/" class="button">Click</a>

Semantic HTML

<!-- ❌ Non-semantic -->
<div class="header">
  <div class="nav">
    <div class="nav-item">Home</div>
  </div>
</div>
<div class="main">
  <div class="article">
    <div class="title">Headline</div>
  </div>
</div>

<!-- ✅ Semantic HTML5 -->
<header>
  <nav>
    <a href="/">Home</a>
  </nav>
</header>
<main>
  <article>
    <h1>Headline</h1>
  </article>
</main>

Image aspect ratios

<!-- ❌ Distorted images -->
<img src="photo.jpg" width="300" height="100" />
<!-- If actual ratio is 4:3, this squishes the image -->

<!-- ✅ Preserve aspect ratio -->
<img src="photo.jpg" width="300" height="225" />
<!-- Actual 4:3 dimensions -->

<!-- ✅ CSS object-fit for flexibility -->
<img src="photo.jpg" style="width: 300px; height: 200px; object-fit: cover;" />

Permissions & privacy

Request permissions properly

// ❌ Request on page load (bad UX, often denied)
navigator.geolocation.getCurrentPosition(success, error)

// ✅ Request in context, after user action
findNearbyButton.addEventListener('click', async () => {
  // Explain why you need it
  if (await showPermissionExplanation()) {
    navigator.geolocation.getCurrentPosition(success, error)
  }
})

Permissions policy

<!-- Restrict powerful features -->
<meta http-equiv="Permissions-Policy" content="geolocation=(), camera=(), microphone=()" />

<!-- Or allow for specific origins -->
<meta http-equiv="Permissions-Policy" content="geolocation=(self 'https://maps.example.com')" />

Audit checklist

Security (critical)

[ ] HTTPS enabled, no mixed content
[ ] No vulnerable dependencies (npm audit)
[ ] CSP headers configured
[ ] Security headers present
[ ] No exposed source maps

Compatibility

[ ] Valid HTML5 doctype
[ ] Charset declared first in head
[ ] Viewport meta tag present
[ ] No deprecated APIs used
[ ] Passive event listeners for scroll/touch

Code quality

[ ] No console errors
[ ] Valid HTML (no duplicate IDs)
[ ] Semantic HTML elements used
[ ] Proper error handling
[ ] Memory cleanup in components

UX

[ ] No intrusive interstitials
[ ] Permission requests in context
[ ] Clear error messages
[ ] Appropriate image aspect ratios

Tools

References

MDN Web Security
OWASP Top 10
Web Quality Audit

Related Skills

tech-leads-club/pr-review

tools

VerifiedTrustedCommunity

Reviews a GitHub pull request and posts inline comments plus one consolidated summary, adapting to any codebase by discovering the project's own test runner, requirement specs, and architecture conventions before running six specialized review agents in parallel. Stack-agnostic across language and framework; targets GitHub PRs via the gh CLI. Use when the user says "review PR 128", "review this PR", "code review this PR", or "check this pull request". Do NOT use for creating PRs or responding to review comments (use gh-address-comments), or debugging failing CI checks (use gh-fix-ci).

4,903SKILL.mdUpdated Jul 19, 2026

tech-leads-club/pr-review

tech-leads-club/rails-dev

development

VerifiedTrustedCommunity

Opinionated Rails conventions: rich models, concerns, CRUD-everything, state-as-records, minimal dependencies, Minitest with fixtures. Load this skill BEFORE any code-level thinking, not only before editing a file. It is required the moment a task touches Rails code in ANY way: designing or even just discussing a data model, schema, migration, entity, association, field, validation, class, or method name; writing, planning, reviewing, analyzing, testing, debugging, or refactoring; or proposing any model, table, column, route, or code snippet inline in chat. If you are about to name a model or sketch a column you are already in scope, even in an exploratory back-and-forth where no file is written yet. Do not let a "we're just discussing" framing defer it. Do NOT use for non-Rails backends, NestJS, or general architecture (use nestjs-modular-monolith or coding-guidelines).

4,897SKILL.mdUpdated Jul 18, 2026

tech-leads-club/rails-dev

tech-leads-club/tlc-spec-driven

testing

VerifiedTrustedCommunity

Feature planning and implementation with 4 adaptive phases — Specify, Design, Tasks, Execute. Auto-sizes depth by complexity. Creates atomic tasks with verification criteria, atomic git commits, and requirement traceability. Features an independent Verifier (author != verifier, evidence-or-zero), persistent decision log (STATE.md), and test-coverage-matrix-driven tests, plus a self-improving lessons layer that turns verification failures into reusable project-local guidance. Stack-agnostic. Use when (1) Planning features (requirements, design, task breakdown), (2) Implementing with verification and atomic commits, (3) Validating or verifying an implementation against a spec. Triggers on "specify feature", "discuss feature", "design", "tasks", "implement", "validate", "verify work", "UAT", "record decision", "pause work", "resume work". Do NOT use for architecture decomposition analysis (use architecture skills) or technical design docs (use create-technical-design-doc).

4,840SKILL.mdUpdated Apr 27, 2026

tech-leads-club/tlc-spec-driven

tech-leads-club/tlc-generative-engine-optimization

development

VerifiedTrustedCommunity

Generative Engine Optimization (GEO) specialist — the technical, on-page publishing work that makes a given page or site discoverable, understandable, trustworthy, quotable, and fresh for AI answer engines (Google AI Overviews, ChatGPT Search, Bing Copilot, Perplexity). Use when asked to 'optimize this page/site for GEO', 'optimize for AI search / answer engines', 'get my page cited by ChatGPT/Perplexity', 'improve AI visibility/citability', 'write an llms.txt', 'add citation-ready structure or schema for AI answers', 'otimizar para busca com IA', or to audit/create/improve a codebase for generative search. Do NOT use for AI-driven SEO content strategy or programmatic pages at scale (use ai-seo), classic keyword/SERP ranking (use seo), accessibility (use web-accessibility), or multi-area site audits (use web-quality-audit).

4,816SKILL.mdUpdated Jul 5, 2026

tech-leads-club/tlc-generative-engine-optimization

Download

For Claude Desktop. Download once, then upload the file in the app — no terminal needed.

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Install manually

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# Clone the repo
git clone https://github.com/tech-leads-club/agent-skills.git

# Copy into Claude Code skills folder (global)
cp -r agent-skills/packages/skills-catalog/skills/(quality)/web-best-practices ~/.claude/skills/

Claude Code Skills — official skills path docs.

Repository

tech-leads-club/agent-skills

4,574 stars

Compatible with

Claude Code

OpenAI Codex CLI

ChatGPT