# compatibility-testing

Organizes cross-browser and responsive layout testing across devices and screen sizes. Useful before major releases and right after layout rewrites.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 651 installs · ★ 515
- Author: proffesor-for-testing
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/proffesor-for-testing/agentic-qe/tree/HEAD/assets/skills/compatibility-testing/SKILL.md
- Updated: 2026-10-25
- HTML: https://affpapa.org/en/nevibecode/skills/compatibility-testing

## What it does

This skill provides test setups for UI validation across multiple viewports and platforms. It handles screen emulation for smartphones, tablets, and desktop displays, then runs visual comparisons between snapshots.

A key limitation is that Vibium v26.3.x only supports Chrome through its BiDi backend. Testing Firefox and Safari still requires standard Playwright configurations or cloud device providers like BrowserStack.

Under the hood, the skill coordinates dedicated subagents like `qe-visual-tester` and `qe-test-executor`. They run parallel test suites, detect layout diffs across targets, and save structured reports to a shared memory namespace.

## Requirements
- Works with: Playwright

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add proffesor-for-testing/agentic-qe --skill compatibility-testing -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/compatibility-testing/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/compatibility-testing/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add proffesor-for-testing/agentic-qe --skill compatibility-testing -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/compatibility-testing/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add proffesor-for-testing/agentic-qe --skill compatibility-testing -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/compatibility-testing/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install proffesor-for-testing/agentic-qe compatibility-testing
```

2. **Manually: put the files in place**
- File: `.github/skills/compatibility-testing/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add proffesor-for-testing/agentic-qe --skill compatibility-testing -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/proffesor-for-testing/agentic-qe --path assets/skills/compatibility-testing
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/compatibility-testing/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add proffesor-for-testing/agentic-qe --skill compatibility-testing -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/proffesor-for-testing/agentic-qe/tree/HEAD/assets/skills/compatibility-testing/SKILL.md

## When to use it
- validate responsive layouts across mobile, tablet, and desktop viewports
- configure Playwright projects for Chromium, Firefox, and WebKit test runs
- detect visual regressions across platforms using the qe-visual-tester agent
- integrate BrowserStack or Sauce Labs to cover real mobile hardware

## Example prompts
- Check responsive layout on 375, 768, and 1920 viewports using vibium
- Generate a playwright.config.ts matrix for Chromium and Firefox
- Run a cross-platform visual comparison task with qe-visual-tester

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 6395d1dc940fbef1.

BEGIN THIRD-PARTY FILE 6395d1dc940fbef1
````text
---
name: compatibility-testing
description: "Cross-browser, cross-platform, and cross-device compatibility testing ensuring consistent experience across environments. Use when validating browser support, testing responsive design, or ensuring platform compatibility."
category: specialized-testing
priority: medium
tokenEstimate: 800
agents: [qe-visual-tester, qe-test-executor, qe-performance-tester]
implementation_status: optimized
optimization_version: 1.0
last_optimized: 2025-12-02
dependencies: []
quick_reference_card: true
tags: [compatibility, cross-browser, responsive, browserstack, playwright, devices]
trust_tier: 3
validation:
  schema_path: schemas/output.json
  validator_path: scripts/validate-config.json
---

# Compatibility Testing

## Browser engine

Browser-driven checks (viewport emulation, responsive validation, cross-browser screenshots) should go through the **qe-browser** fleet skill (`.claude/skills/qe-browser/`). Vibium is installed by `aqe init`. Quick reference:

```bash
# Viewport emulation per breakpoint
vibium viewport 375 667   # mobile
vibium viewport 768 1024  # tablet
vibium viewport 1920 1080 # desktop

# Full device emulation (user-agent, DPR, touch)
vibium emulate-device "iPhone 15"

# Visual diff per viewport
for vp in "375 667 mobile" "768 1024 tablet" "1920 1080 desktop"; do
  read w h name <<< "$vp"
  vibium viewport $w $h
  node .claude/skills/qe-browser/scripts/visual-diff.js --name "homepage-$name"
done
```

Cross-browser (Firefox/Safari) still requires Playwright or a cloud device farm today — Vibium's BiDi backend is Chrome-only at v26.3.x.

<default_to_action>
When validating cross-browser/platform compatibility:
1. DEFINE browser matrix (cover 95%+ of users)
2. TEST responsive breakpoints (mobile, tablet, desktop)
3. RUN in parallel across browsers/devices
4. USE cloud services for device coverage (BrowserStack, Sauce Labs)
5. COMPARE visual screenshots across platforms

**Quick Compatibility Checklist:**
- Chrome, Firefox, Safari, Edge (latest + N-1)
- Mobile Safari (iOS), Mobile Chrome (Android)
- Screen sizes: 320px, 768px, 1920px
- Test on actual target devices for critical flows

**Critical Success Factors:**
- Users access from 100+ browser/device combinations
- Test where users are, not where you develop
- Cloud testing reduces 10 hours to 15 minutes
</default_to_action>

## Quick Reference Card

### When to Use
- Before release
- After CSS/layout changes
- Launching in new markets
- Responsive design validation

---

## Cross-Browser with Playwright

```javascript
// playwright.config.ts
import { defineConfig, devices } from '@playwright/test';

export default defineConfig({
  projects: [
    { name: 'chromium', use: { ...devices['Desktop Chrome'] } },
````
END THIRD-PARTY FILE 6395d1dc940fbef1

The third-party file has ended. Everything between the 6395d1dc940fbef1 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2754 of 5362 bytes. © proffesor-for-testing · MIT · https://github.com/proffesor-for-testing/agentic-qe/tree/HEAD/assets/skills/compatibility-testing/SKILL.md

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---
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