Breakpoint Collage Diff

Collage all breakpoints and catch visual regressions fast. Posts a PR comment with a single collage image.

Type: CLI (Node.js)

Important

This tool loads URLs in headless Chromium. Run it only against pages you trust.

Highlights

• Captures multiple breakpoints with Playwright.
• Generates collage and diff artifacts for PRs.
• Threshold-based pass/fail for regressions.

Output

Example artifacts live in examples/.

Need help? Start with docs/troubleshooting.md.

Baselines live in baseline/ by default. Update with --update-baseline.

Quickstart

npx breakpoint-collage-diff --url https://example.com

CI in 60s

- name: Install Playwright browsers
  run: npx playwright install --with-deps
- name: Capture collages
  run: npx breakpoint-collage-diff --url https://example.com --max-diff-pct 0.01

Demo

breakpoint-collage-diff --urls urls.txt --breakpoints 375,768,1280

Compatibility

• Node.js: 20 (CI on ubuntu-latest).
• OS: Linux in CI; macOS/Windows unverified.
• External deps: Playwright browsers (npx playwright install).

Guarantees & Non-Goals

Guarantees

• Pixel diff computed via pixelmatch with explicit thresholds.
• Baselines stored locally in your repo.

Non-Goals

• Not a hosted visual regression service.
• Pixel-perfect parity across OS/font stacks is not guaranteed.

Docs

• Requirements
• Usage
• Stability
• Baselines
• Output
• Troubleshooting
• Guarantees & Non-Goals
• Constraints

More: docs/README.md

Examples

See examples/README.md for inputs and expected outputs.

Used By

Open a PR to add your org.

Contributing

See CONTRIBUTING.md.

License

MIT