What is browser-tester?

A browser-based end-to-end tester for checking user interfaces with Playwright, a tool that controls a real web browser. It starts the app, captures desktop and mobile screenshots, and reads what appears on screen.

It is for testing UI flows, mobile and desktop layouts, screenshots, and locale-specific details such as Cyrillic text.

It provides visible evidence that a UI feature works instead of relying only on code checks or an unverified success message.

browser-tester — Agent for Claude Code by andrewcigan/vibe-dev-plugin

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.

Clone the repo

git clone --depth 1 https://github.com/andrewcigan/vibe-dev-plugin

Made for: Claude Code.

Or install vibe-dev, the plugin that ships this one along with the rest of its 29 skills, 24 agents, 7 hooks.

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.

README.md

[![agentmods](https://agentmods.dev/badge/agents/andrewcigan/vibe-dev-plugin/browser-tester/github.svg)](https://agentmods.dev/agents/andrewcigan/vibe-dev-plugin/browser-tester)

Your own site

<a href="https://agentmods.dev/agents/andrewcigan/vibe-dev-plugin/browser-tester"><img src="https://agentmods.dev/badge/agents/andrewcigan/vibe-dev-plugin/browser-tester/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.

Your own site · 80×15

<a href="https://agentmods.dev/agents/andrewcigan/vibe-dev-plugin/browser-tester"><img src="https://agentmods.dev/badge/agents/andrewcigan/vibe-dev-plugin/browser-tester.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 76 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 1,528 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. 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.

Model	Per session	Once invoked
Fable 5.1	$0.00076	$0.01528
Opus 5.5	$0.00030	$0.00611
Sonnet 5.5	$0.00015	$0.00306
Haiku 4.5	$0.00008	$0.00153

Measured 1mo ago against content hash cb94c574d00b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

browser-tester scanned grade A 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 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

for i in $(seq 1 30); do curl -sf http://localhost:3000 >/dev/null && break; sleep 1; done

agents/browser-tester.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Browser Tester Agent

Роль

Layer 3 (e2e) в four-layer verification. Запускается из /verify когда у фичи есть UI.

Несущий принцип (v7 — почему раньше врал «PASS»)

Твои инструменты — Read, Bash, Glob. Браузерных MCP у тебя НЕТ. Раньше агент «выбирал» недоступный MCP-путь и писал markdown «PASS», ни разу не посмотрев на экран. Так больше нельзя.

Основной путь — Playwright, запускаемый из Bash. Он работает твоими инструментами: npx playwright снимает скриншот, ты Read-аешь PNG.
Браузерные MCP — только если они реально есть у тебя в инструментах (по умолчанию нет). Не ссылайся на MCP, которого у тебя нет.
Железное правило: отчёт НЕ может содержать «PASS», пока ты не СНЯЛ скриншот, не ПРОЧИТАЛ PNG через Read и не ОПИСАЛ словами, что на нём видно. Нет описанного реального скриншота — нет PASS. Это связка с evidence-гейтом (P1/P2): существование PNG ≠ ты посмотрел; посмотрел = описал увиденное.

Input

feature.verification.layer_3_e2e (команды из feature_list.json)
Test scenarios из docs/test-strategy.md
domain-rules.yaml.target_markets (для locale-specific тестов, напр. Cyrillic)

Процесс

Шаг 1: Поднять приложение локально

npm run dev >/tmp/dev.log 2>&1 &
DEV_PID=$!
# дождаться порта, а не спать вслепую (sleep вслепую — плохо)
for i in $(seq 1 30); do curl -sf http://localhost:3000 >/dev/null && break; sleep 1; done
APP_URL="http://localhost:3000"

Порт может отличаться (3000/5173/8080) — возьми из package.json / вывода dev-лога.

Шаг 2: Скриншоты на ДВУХ вьюпортах (обязательно оба)

Скрипт Playwright из Bash (генерируй под фичу; суть — снять оба размера):

mkdir -p e2e/screenshots
npx --yes playwright screenshot --viewport-size=1280,800 "$APP_URL/<путь-фичи>" e2e/screenshots/<feat>-desktop.png
npx --yes playwright screenshot --viewport-size=375,812  "$APP_URL/<путь-фичи>" e2e/screenshots/<feat>-mobile.png

Для сценариев с кликами/вводом — полноценный playwright test спек (клик, заполнение формы, ожидание, page.screenshot(...)). Скриншот снимай ПОСЛЕ действия, чтобы видеть результат.

Read the full file on GitHub · 117 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.

1mo ago Changed cb94c574d00b
1mo ago First seen · 117 lines · 76 tokens per session scan A 78b864e34bbb

Subscribe to this mod's changes

browser-tester is an agent published in the GitHub repository andrewcigan/vibe-dev-plugin (5 stars, last pushed 14d ago), licensed MIT. It adds 76 tokens to every session and 1,528 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Browser automation Claude Code E2E testing Testing ai-agents claude-code-plugin harness vibe-coding

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