A testing guide for the Band web application that starts its development server, opens pages in a browser, and captures screenshots.

Use it for browser tests, visual checks, screenshots, layout verification, and visual regression checks.

It helps find broken layouts or visual problems by checking the running application at the actual port and recording what users see.

How band-app/band configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to band-app/band. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/band-app/band/main/.claude/skills/web-test/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/band-app/band

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/band-app/band/web-test/github.svg)](https://agentmods.dev/skills/band-app/band/web-test)

Your own site

<a href="https://agentmods.dev/skills/band-app/band/web-test"><img src="https://agentmods.dev/badge/skills/band-app/band/web-test/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/skills/band-app/band/web-test"><img src="https://agentmods.dev/badge/skills/band-app/band/web-test.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 77 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 885 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	$0.00077	$0.00885
Opus 5.5	$0.00031	$0.00354
Sonnet 5.5	$0.00015	$0.00177
Haiku 4.5	$0.00008	$0.00089

Measured 25d ago against content hash f7e1c3934544, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

web-test 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 25d 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.

allowed-tools: Bash(pnpm dev:web*), Bash(lsof *), Bash(kill *), Bash(npx agent-browser *), Bash(agent-browser *), Bash(curl *), Read

.claude/skills/web-test/SKILL.md · 112 lines

How it starts

The opening of the file, as written. The whole thing — 112 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Web App Testing with Screenshots

Test the Band web application by starting the dev server and using agent-browser to navigate pages and capture screenshots.

Steps

1. Start the dev server and detect the port

Run from the repo root (/Users/amirilovic/Repos/band). Do NOT kill any existing server — Vite will automatically pick another port if 3456 is occupied.

pnpm dev:web &

IMPORTANT: Read the Vite startup output and parse the actual port from the Local: line, e.g.:

  Local:   http://localhost:3456/

or if 3456 was busy:

  Local:   http://localhost:3457/

Use whatever port Vite reports for all subsequent steps. Do NOT hardcode 3456.

Wait for the server to be ready by polling the detected port:

for i in $(seq 1 30); do
  curl -sf http://localhost:<PORT> > /dev/null 2>&1 && break
  sleep 1
done

If it does not respond after 30 seconds, report an error and stop.

2. Navigate and take screenshots

Use agent-browser to open pages and capture screenshots. Always wait for the page to fully load before taking a screenshot.

Use the port detected in step 1 for all URLs.

Desktop viewport (default 1280x720):

agent-browser open http://localhost:<PORT> && agent-browser wait --load networkidle && agent-browser screenshot desktop-dashboard.png

Mobile viewport (375x812):

agent-browser set viewport 375 812
agent-browser open http://localhost:<PORT> && agent-browser wait --load networkidle && agent-browser screenshot mobile-dashboard.png

Key routes to test

Adjust based on what the user asks. Common routes:

Route	Description
`/`	Dashboard — repo list
`/chat/<worktreeId>`	Worktree chat view
`/tasks`	Tasks page
`/cronjobs`	Cronjobs page

To find valid worktree IDs for the chat route, first snapshot the dashboard and look for repo links.

3. Interactive testing

If the user asks to test interactions (clicking, filling forms), use the standard agent-browser workflow:

Read the full file on GitHub · 112 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.

25d ago Changed f7e1c3934544
2mo ago First seen · 112 lines · 77 tokens per session scan A 1cbb811a2e24

Subscribe to this mod's changes

web-test is a skill published in the GitHub repository band-app/band (5 stars, last pushed today), licensed MIT. It adds 77 tokens to every session and 885 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 E2E testing Testing

browse

Drive a real browser through Aside: open a page, read it, click through a flow, take screenshots, check console errors. (gstack).

garrytan/gstack · 32 tokens

cua-driver

Use Cua Driver for desktop or browser tasks that are awkward or unavailable through Bash/APIs, or when the user explicitly wants GUI interaction: app testing, visual bug reproduction, form filling, calendar entry, screenshots, and demo recording. Also covers Cua setup; not OpenAI Codex Computer Use or web research.

davidondrej/skills · 68 tokens

create-verification-skill

Create a repo-local verification skill and exhaustive feature map for driving a real app through its UI, CLI, or API. Use for "create a verification skill", "make a verify skill for this repo", or "document how agents can verify this app".

get-bb/bb · 57 tokens

webapp-testing

Toolkit for interacting with and testing local web applications using Playwright. Supports verifying frontend functionality, debugging UI behavior, capturing browser screenshots, and viewing browser logs.

anthropics/skills · 35 tokens

browser-qa

A browser-based quality check for deployed web pages and user flows. It uses browser automation to test rendering, navigation, forms, interactions, responsive behaviour, and accessibility-related issues.

hashgraph-online/awesome-codex-plugins · 58 tokens

test-electron-app

Drive the real running PostHog Electron app (live tRPC, workspace-server, real data) over CDP with agent-browser. Connect to the running app on port 9222, test desktop changes against a local Django stack, snapshot the accessibility tree, inspect network requests, and screenshot only when explicitly asked. Use when…

PostHog/posthog-foss · 112 tokens

band: Skill for Claude Code