compatibility-testing

compatibility-testing is a skill for Claude Code from summarybotng/summarybot-ng. It costs 36 tokens per session (1,482 once invoked), scanned A, original, MIT.

A testing approach for checking that software behaves consistently across browsers, operating systems, devices, and screen sizes. It includes desktop and mobile layouts and visual comparisons.

In plain words
What is it for?
Use it to define a browser and device matrix, check responsive breakpoints, compare screenshots, and validate important user flows before release.
Why use it?
It helps find browser-specific, platform-specific, and responsive-layout problems that may only appear in the environments used by real customers.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

Good fit Use it to define a browser and device matrix, check responsive breakpoints, compare screenshots, and validate important user flows before release.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/summarybotng/summarybot-ng/compatibility-testing
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add summarybotng/summarybot-ng --skill compatibility-testing
Clone the repo
git clone --depth 1 https://github.com/summarybotng/summarybot-ng

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for compatibility-testing

README.md
[![agentmods](https://agentmods.dev/badge/skills/summarybotng/summarybot-ng/compatibility-testing/github.svg)](https://agentmods.dev/skills/summarybotng/summarybot-ng/compatibility-testing)
Your own site
<a href="https://agentmods.dev/skills/summarybotng/summarybot-ng/compatibility-testing"><img src="https://agentmods.dev/badge/skills/summarybotng/summarybot-ng/compatibility-testing/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for compatibility-testing

Your own site · 80×15
<a href="https://agentmods.dev/skills/summarybotng/summarybot-ng/compatibility-testing"><img src="https://agentmods.dev/badge/skills/summarybotng/summarybot-ng/compatibility-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,482 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00036 $0.01482
Opus 5.5 $0.00014 $0.00593
Sonnet 5.5 $0.00007 $0.00296
Haiku 4.5 $0.00004 $0.00148

Measured 1mo ago against content hash 68ff9da26904, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

compatibility-testing scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/compatibility-testing/SKILL.md · 210 lines

How it starts

The opening of the file, as written. The whole thing — 210 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Compatibility Testing

<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

Browser Matrix

Browser Versions Priority
Chrome Latest, N-1 High
Firefox Latest, N-1 High
Safari Latest, N-1 High
Edge Latest Medium
Mobile Safari iOS latest High
Mobile Chrome Android latest High

Screen Breakpoints

Category Width Range
Mobile 320px - 480px
Tablet 481px - 768px
Desktop 769px - 1920px+

Responsive Design Testing

import { test, expect } from '@playwright/test';

const devices = [
  { name: 'iPhone 12', width: 390, height: 844 },
  { name: 'iPad', width: 768, height: 1024 },
  { name: 'Desktop', width: 1920, height: 1080 }
];

for (const device of devices) {
  test(`layout on ${device.name}`, async ({ page }) => {
    await page.setViewportSize({
      width: device.width,
      height: device.height
    });

    await page.goto('https://example.com');

    const nav = await page.locator('nav');
    if (device.width < 768) {
      // Mobile: hamburger menu
      expect(await nav.locator('.hamburger')).toBeVisible();
    } else {
      // Desktop: full menu
      expect(await nav.locator('.menu-items')).toBeVisible();
    }
  });
}

Read the full file on GitHub · 210 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 210 lines · 36 tokens per session scan A 68ff9da26904

Subscribe to this mod's changes

compatibility-testing is a skill published in the GitHub repository summarybotng/summarybot-ng (2 stars, last pushed 4mo ago), licensed MIT. It adds 36 tokens to every session and 1,482 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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