jaobrown/demo

/demo - PR Demo Video Generator

Generate screen recordings with AI narration to demonstrate your PR changes.

How to Execute /demo

Follow these steps in order. You (Claude) generate the test and narration directly - no templates needed.

Step 1: Check Prerequisites

npx tsx lib/cli.ts check-prereqs

Returns JSON with status for:

• devServer: Whether the dev server is responding
• ffmpeg: Whether ffmpeg is installed (needed for video composition)
• elevenLabsKey: Whether ELEVEN_LABS_API_KEY is set (optional, for narration)

If devServer is false, ask the user to start their dev server first.

Step 2: Analyze the Diff

npx tsx lib/cli.ts analyze-diff --staged

Or for specific commits:

npx tsx lib/cli.ts analyze-diff --commits=HEAD~3..HEAD

Returns JSON with:

• uiRelevant: Whether changes affect UI
• suggestedRoute: Route to navigate to
• changedComponents: Component names that changed
• suggestedActions: What to demonstrate

If uiRelevant is false, inform the user and stop.

Step 3: Discover Playwright Setup (For Monorepos)

For monorepos or projects with non-root Playwright configs:

Glob("**/playwright.config.ts")

Note the paths for Step 5.

Step 4: Generate Playwright Test (YOU WRITE THIS)

Based on the analysis, write a Playwright test that demonstrates the UI changes.

Use vanilla Playwright only - import from @playwright/test, not custom fixtures.

Save to temp/demo-recording.spec.ts:

import { test } from "@playwright/test";

test("demo: updated modal copy", async ({ page }) => {
  await page.goto("http://localhost:3000/home");
  await page.waitForLoadState("networkidle");
  await page.waitForTimeout(1500);

  await page.click('[data-testid="add-repo-button"]');
  await page.waitForTimeout(800);

  await page.waitForSelector('[role="dialog"]');
  await page.waitForTimeout(3000); // Let viewers see the changes
});

Guidelines:

• Navigate to the affected route
• Include realistic timing with page.waitForTimeout() (1-3 seconds between actions)
• Use robust selectors: data-testid > ARIA roles > text content

Step 5: Generate Narration Script (YOU WRITE THIS)

Write natural narration as a JSON array. Save to temp/narration-script.json:

[
  { "text": "This pull request updates the copy in our add repository modal.", "startTimeMs": 0 },
  { "text": "Let me show you - I'll click the add button here.", "startTimeMs": 2500 },
  { "text": "And here's the modal with our updated messaging.", "startTimeMs": 5500 }
]

Guidelines:

• Brief intro explaining the PR changes
• Commentary synced to test actions
• Conversational tone
• ~150 words per minute for timing

Step 6: Run the Recording

npx tsx lib/cli.ts cleanup
npx tsx lib/cli.ts record temp/demo-recording.spec.ts

For monorepos, pass discovered config:

npx tsx lib/cli.ts record temp/demo-recording.spec.ts --config=apps/web/playwright.config.ts --test-dir=apps/web/tests

Look for videoPath in the JSON output under --- RESULT ---.

Step 7: Generate Narration Audio (Optional)

If ELEVEN_LABS_API_KEY is set:

npx tsx lib/cli.ts narrate temp/narration-script.json

Look for audioPath in the JSON output.

Step 8: Composite Final Video

npx tsx lib/cli.ts composite <video-path> [audio-path]

Example:

npx tsx lib/cli.ts composite temp/test-results/video.webm temp/narration.mp3

Or without audio:

npx tsx lib/cli.ts composite temp/test-results/video.webm

Look for outputPath - this is the final MP4 in output/.

---

Configuration

Edit config.json in the skill directory:

{
  "baseUrl": "http://localhost:3000",
  "voiceId": "21m00Tcm4TlvDq8ikWAM",
  "videoDimensions": { "width": 1280, "height": 720 },
  "outputDir": "output",
  "tempDir": "temp",
  "recordingTimeout": 60000
}

ElevenLabs Voice IDs

• 21m00Tcm4TlvDq8ikWAM - Rachel (default, conversational)
• EXAVITQu4vr4xnSDxMaL - Bella (warm, friendly)
• ErXwobaYiN019PkySvjV - Antoni (professional)

---

Troubleshooting

"Dev server not responding"

Start your dev server: pnpm dev or npm run dev

"ffmpeg not found"

• macOS: brew install ffmpeg
• Linux: sudo apt install ffmpeg
• Windows: choco install ffmpeg

"ElevenLabs API error"

Check your API key: echo $ELEVEN_LABS_API_KEY Video will work without it (just no narration).

Video file not found

Check temp/playwright-output.log for errors.

---

MCP Server (Advanced)

For tighter Claude integration, an MCP server is available with typed tools:

pnpm run mcp-server

Tools: demo_check_prerequisites, demo_analyze_changes, demo_discover_test_environment, demo_save_test_file, demo_save_narration_script, demo_record_video, demo_generate_audio, demo_composite_final_video, demo_cleanup

Configure in your MCP settings to use these instead of CLI commands.