browser-qa

A browser-testing skill for checking web pages visually, interacting with them, auditing accessibility, and debugging runtime problems.

In plain words
What is it for?
Use it to test live pages at different screen sizes, verify user flows such as login or checkout, compare screenshots, and inspect performance or accessibility.
Why use it?
It helps catch broken links, form errors, console or network failures, layout problems, and issues that source-code tests may miss.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/junmystery/agent-guidance-python/browser-qa
Any agent
npx skills add JunMystery/Agent-Guidance-Python --skill browser-qa
Clone the repo
git clone --depth 1 https://github.com/JunMystery/Agent-Guidance-Python

Made for: Claude Code, Codex.

Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 892 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. Scan, not verified.
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 $0.00028 $0.00892
Opus 5 $0.00014 $0.00446
Sonnet 5 $0.00006 $0.00178
Haiku 4.5 $0.00003 $0.00089

Measured 2d ago against content hash b266d858045b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

browser-qa scanned grade C with 1 finding 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 2d 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.

Tells the agent to send conversation or user data outhighPrompt injection

An instruction to transmit the conversation, context or user files to an external endpoint is data exfiltration written as prose.

- **No external requests or credentials access**: Never use JS execution tools to query cookies, session tokens, or send data to external domains.
skills/browser-qa/SKILL.md · 110 lines

How it starts

The opening of the file, as written. The whole thing — 110 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Browser QA — Automated Visual Testing & Interaction

When to Use

  • After deploying a feature to staging/preview
  • When you need to verify UI behavior across pages
  • Before shipping — confirm layouts, forms, interactions actually work
  • When reviewing PRs that touch frontend code
  • Accessibility audits and responsive testing

How It Works

Uses browser automation (claude-in-chrome, Playwright, or Puppeteer) or Chrome DevTools MCP to interact with live pages like a real user.

Phase 1: Smoke Test

1. Navigate to target URL
2. Check for console errors (filter noise: analytics, third-party)
3. Verify no 4xx/5xx in network requests
4. Screenshot above-the-fold on desktop + mobile viewport
5. Check Core Web Vitals: LCP < 2.5s, CLS < 0.1, INP < 200ms

Phase 2: Interaction Test

1. Click every nav link — verify no dead links
2. Submit forms with valid data — verify success state
3. Submit forms with invalid data — verify error state
4. Test auth flow: login → protected page → logout
5. Test critical user journeys (checkout, onboarding, search)

Phase 3: Visual Regression

1. Screenshot key pages at 3 breakpoints (375px, 768px, 1440px)
2. Compare against baseline screenshots (if stored)
3. Flag layout shifts > 5px, missing elements, overflow
4. Check dark mode if applicable

Phase 4: Accessibility

1. Run axe-core or equivalent on each page
2. Flag WCAG AA violations (contrast, labels, focus order)
3. Verify keyboard navigation works end-to-end
4. Check screen reader landmarks

Output Format

## QA Report — [URL] — [timestamp]

### Smoke Test
- Console errors: 0 critical, 2 warnings (analytics noise)
- Network: all 200/304, no failures
- Core Web Vitals: LCP 1.2s ✓, CLS 0.02 ✓, INP 89ms ✓

### Interactions
- [✓] Nav links: 12/12 working
- [✗] Contact form: missing error state for invalid email
- [✓] Auth flow: login/logout working

### Visual
- [✗] Hero section overflows on 375px viewport
- [✓] Dark mode: all pages consistent

### Accessibility
- 2 AA violations: missing alt text on hero image, low contrast on footer links

### Verdict: SHIP WITH FIXES (2 issues, 0 blockers)

Read the full file on GitHub · 110 lines

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. 2d ago First seen · 110 lines · 28 tokens per session scan C b266d858045b

Subscribe to this mod's changes

browser-qa is a skill published in the GitHub repository JunMystery/Agent-Guidance-Python (2 stars, last pushed 1mo ago), licensed MIT. It adds 28 tokens to every session and 892 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C with 1 finding (tells the agent to send conversation or user data out). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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