mccurdyc/screenshot

Screenshot Skill

Take a screenshot of a locally running web application.

Workflow

1. Ask if the local dev environment is already running.

   • If yes, ask for the URL (default: http://localhost:3000).
   • If no, ask the user how to start it, then run the provided command and wait for the server to be ready before proceeding.

2. Install Playwright and Chromium to a temp directory.

   npm install --prefix /tmp/pw playwright
   npx --prefix /tmp/pw playwright install chromium
   

3. Take the screenshot with a Node.js script using the Playwright API.

   Write a script (e.g., /tmp/pw/screenshot.mjs):

   import { chromium } from '/tmp/pw/node_modules/playwright/index.mjs';
   
   const url = process.argv[2] || 'http://localhost:3000';
   const outputPath = process.argv[3] || 'screenshot.png';
   
   const browser = await chromium.launch();
   const page = await browser.newPage({ viewport: { width: 1600, height: 900 } });
   await page.goto(url, { waitUntil: 'networkidle' });
   await page.waitForTimeout(8000); // extra wait for JS-heavy apps (dashboards, SPAs)
   await page.screenshot({ path: outputPath, fullPage: true });
   await browser.close();
   

   Run it:

   node /tmp/pw/screenshot.mjs "<URL>" screenshot.png
   

   Adjust wait time and viewport as needed:

   • For simple apps, reduce waitForTimeout to 2000–3000ms.
   • For dashboards (Grafana, etc.), keep 8000ms or more so panels finish fetching data and rendering.
   • If the user requests a specific viewport, change the width/height.
   • If the user wants a specific element, use page.locator('selector').screenshot() instead of full-page.

4. Show the screenshot to the user using the read tool on the resulting PNG file so they can verify it.

5. Ask if the user wants the screenshot added as a comment on the current pull request.

   • If yes, determine the current PR number:

     gh pr view --json number -q .number
     

   • Commit the screenshot to the branch and push, then comment with an image reference:

     git add screenshot.png
     git commit --no-gpg-sign -m "docs: add screenshot"
     git push
     gh pr comment <number> --body "## Screenshot\n\n![screenshot](screenshot.png)"
     

   • Alternatively, if the user prefers not to commit the file to the repo, upload it externally and reference the URL in the comment.

Notes

• Use Chromium, not Firefox. The Playwright Firefox build has compatibility issues with JS-heavy apps (e.g., Grafana fails to load application files).
• Use the programmatic API, not the Playwright CLI. The API gives control over viewport, wait conditions, selectors, and timeouts.
• Always use waitUntil: 'networkidle' plus an additional timeout for apps that render asynchronously after initial load.
• Install to /tmp/pw to avoid polluting the project directory.
• Clean up screenshot files after they are uploaded unless the user says otherwise.