Most end-to-end test suites drive a real browser and click through an app like a user. They check whether a page renders and whether elements appear. But they don't check whether the numbers on those elements are correct. A data-pipeline bug that shows Malaysia's population as 3.4 million instead of the real 34 million slips past every selector test in the suite. The element still exists. A number still renders. The page still looks right. But the bug ships and sits there until a human notices. I work as a full-stack engineer. Writing end-to-end (E2E) tests with Playwright and unit tests with Jest is part of my day job. I also use Playwright MCP , the bridge between AI assistants like Claude and a running browser, when I need to generate first-draft test code or debug a flow. None of that tooling closes the maintenance tax on selector-based suites. Every E2E suite I keep alive at work accumulates data-testid selectors, waitForSelector calls, and tests that break because someone renamed a button.…