capture-pr-visuals

Capture screenshots and GIFs of the running application for PR visual documentation. Reads chalk.json for dev server and route info, falls back to auto-discovery if chalk docs don't exist. Uses Playwright via npx.

Workflow

Step 1: Read Project Context

Read .chalk/chalk.json to get:

• dev.command — how to start the dev server
• dev.port — what port it runs on
• dev.url — the full URL
• routes[] — what pages to capture
• project.framework — for framework-specific handling (e.g., Electron)

Fallback: No chalk.json

If chalk.json doesn't exist or is missing key fields, auto-discover:

1. Read package.json — detect framework from dependencies:

   • next → Next.js (port 3000, file-based routing)
   • vite / @vitejs/plugin-react → Vite SPA (port 5173)
   • react-scripts → CRA (port 3000)
   • nuxt → Nuxt (port 3000)
   • @angular/core → Angular (port 4200)
   • svelte / @sveltejs/kit → SvelteKit (port 5173)
   • electron / electron-vite → Electron (renderer on separate port)
   • vue → Vue (port 5173 or 8080)

2. Detect routes — scan based on framework:

   • File-based routing: glob app/**/page.{tsx,jsx,ts,js} or pages/**/*.{tsx,jsx,vue}
   • React Router: grep for <Route or createBrowserRouter in src/
   • Vue Router: grep for path: in router configs
   • Query-param routing (Electron): grep for searchParams.get
   • Fallback: scan src/pages/, src/views/, src/app/, src/routes/

3. Confirm with user — show auto-detected URL and routes, let them correct before proceeding.

If auto-discovery also fails, ask the user for the dev URL and routes. Suggest running /setup-chalk for future use.

Step 2: Analyze PR Changes

git diff main..HEAD --name-only
git diff main..HEAD --stat

Map changed files to affected routes using chalk.json routes[].src or the architecture docs. For example:

• Changes in src/pages/dashboard/ → /dashboard route
• Changes in src/components/Header.tsx → all pages (shared component)

If the user provided specific routes as arguments, use those instead.

If no route mapping is possible (backend-only changes), inform the user and ask which pages to capture.

Step 3: Ensure Dev Server is Running

curl -s -o /dev/null -w "%{http_code}" http://localhost:<PORT> 2>/dev/null

If not running:

• Start the dev server in the background using dev.command from chalk.json
• Wait for it to be ready (poll until HTTP response)
• For Electron apps: the renderer is served on a separate port during dev — detect from config or output

Note the PID if starting the server so it can be stopped later.

Step 4: Ensure Playwright is Available

npx playwright install chromium 2>/dev/null || echo "Playwright install failed"

Check for ffmpeg (needed for GIF generation):

which ffmpeg 2>/dev/null

If ffmpeg is missing, warn: "ffmpeg not found — screenshots only (no GIFs). Install with brew install ffmpeg for GIF support."

Step 5: Clean Old Artifacts and Capture New Ones

First, clean any previous screenshots to ensure a fresh capture:

rm -rf .github/pr-screenshots/ 2>/dev/null
mkdir -p .github/pr-screenshots/

Then create a temporary capture script at .chalk/local/capture-script.ts:

import { chromium } from 'playwright';
import { mkdirSync } from 'fs';
import { join } from 'path';

const BASE_URL = '<DETECTED_URL>';
const ROUTES: { path: string; name: string }[] = [
  // Populated from chalk.json routes or Step 2 analysis
];
const OUTPUT_DIR = '.github/pr-screenshots';
const VIDEO_DIR = join(OUTPUT_DIR, 'videos');

(async () => {
  mkdirSync(OUTPUT_DIR, { recursive: true });
  mkdirSync(VIDEO_DIR, { recursive: true });

  const browser = await chromium.launch({ headless: true });

  for (const route of ROUTES) {
    const context = await browser.newContext({
      viewport: { width: 1280, height: 800 },
      recordVideo: { dir: VIDEO_DIR, size: { width: 1280, height: 800 } },
    });

    const page = await context.newPage();

    try {
      await page.goto(`${BASE_URL}${route.path}`, {
        waitUntil: 'networkidle',
        timeout: 15000,
      });

      await page.screenshot({
        path: join(OUTPUT_DIR, `${route.name}.png`),
        fullPage: true,
      });

      // Brief interaction for video
      await page.evaluate(() => window.scrollTo({ top: document.body.scrollHeight, behavior: 'smooth' }));
      await page.waitForTimeout(1500);
      await page.evaluate(() => window.scrollTo({ top: 0, behavior: 'smooth' }));
      await page.waitForTimeout(1500);

    } catch (err) {
      console.error(`Failed to capture ${route.name}: ${err}`);
    }

    await page.close();
    await context.close();
  }

  await browser.close();
  console.log('Capture complete.');
})();

Adapt the script based on the project:

• Set BASE_URL from chalk.json dev.url or detected URL
• Populate ROUTES from chalk.json or Step 2 analysis
• For Electron query-param routing, use paths like ?home=true
• Add project-specific interactions if relevant

Execute:

npx tsx .chalk/local/capture-script.ts

Step 6: Convert Videos to GIFs

If ffmpeg is available:

for f in .github/pr-screenshots/videos/*.webm; do
  name=$(basename "$f" .webm)
  ffmpeg -y -i "$f" -vf "fps=10,scale=1280:-1:flags=lanczos" -loop 0 ".github/pr-screenshots/${name}.gif" 2>/dev/null
done

Clean up videos:

rm -rf .github/pr-screenshots/videos

Step 7: Commit Artifacts

Commit the new visual artifacts:

git add .github/pr-screenshots/
git commit -m "chore: add PR visual artifacts"

Step 8: Output

Print markdown references for the PR body:

## Visual Preview

### <Page Name>
![<page-name> screenshot](/.github/pr-screenshots/<page-name>.png)
![<page-name> interaction](/.github/pr-screenshots/<page-name>.gif)

Suggest: "Visual artifacts committed. Run /create-pr to create the PR with embedded screenshots."

Step 9: Cleanup

• Delete the temporary capture script: rm -f .chalk/local/capture-script.ts
• If the dev server was started by this skill, ask the user if they want to stop it

Rules

• NEVER modify package.json or install permanent dependencies
• Always use npx for Playwright and tsx
• Clean previous screenshots before capturing new ones
• If capture fails for a route, log a warning but continue with other routes
• The capture script is ephemeral — delete it after execution
• Screenshots go in .github/pr-screenshots/ (committed to the branch)
• For auth-gated pages, warn the user those pages may need manual screenshots

Electron App Handling

If chalk.json has project.framework: "electron" or package.json has electron as a dependency:

• The renderer is served on a separate port during dev (auto-assigned by Vite)
• Check the dev server output or config for the renderer URL
• Use that renderer URL as BASE_URL (not the Electron window)
• Electron query-param routing (e.g., ?home=true, ?canvas) should be used as route paths