Author and run E2E tests on BrowserStack Automate - cloud grid covering 3000+ real device + browser combinations. Covers BROWSERSTACK_USERNAME + ACCESS_KEY auth, hub URL https://hub-cloud.browserstack.com/wd/hub, W3C capabilities + bstack:options (projectName, buildName, sessionName), BrowserStackLocal for testing against localhost / internal environments, parallel session limits, and CI integration. Use for cross-browser regression on real devices + browsers - distinct from running a single test framework locally, and from a matrix runner limited to the browser engines bundled on the local machine.