Playwright is Microsoft's browser testing framework — it launches real browsers and clicks through your app like a user would. Install it with `npm init playwright@latest` and it scaffolds everything: test files, config, and a VS Code extension for debugging.

Focus on the paths that make you money: sign up, checkout, and core features. Use Playwright's codegen (`npx playwright codegen`) — it records your clicks and generates test code automatically. Start with 5-10 tests covering your most important flows.

Add Playwright to your GitHub Actions workflow so tests run on every pull request. If a test fails, the PR can't merge. Playwright generates HTML reports with screenshots and video recordings of failures — makes debugging easy.

Playwright can take screenshots and compare them against baselines. If a CSS change accidentally breaks your layout, the test catches it. Run `npx playwright test --update-snapshots` to update baselines when you intentionally change designs.

Use Playwright's built-in HTML reporter to track test pass rates over time. Aim for 100% pass rate (flaky tests are worse than no tests — fix or delete them). Gradually expand coverage as you build new features.