Authors and remediates Playwright E2E tests across Chromium, Firefox, WebKit - `npm init playwright@latest` scaffolding, `playwright.config.ts` browser projects, accessibility-first locators (`getByRole`/`getByLabelText`) to replace brittle CSS selectors, web-first assertions to eliminate `waitForTimeout` flakiness, Page Object pattern, trace viewer debugging, sharded parallel execution with merged HTML reporting, and GitHub Actions CI integration. Use for new test authoring, flakiness remediation, and CI setup; for reviewing codegen output specifically, use a dedicated codegen-review pass.