... encoding every assertion as rigid script logic, we can let an agent read a test case, drive the browser, inspect the page, collect evidence, and judge whether the user-facing expectation is satisfied. The script becomes the harness: it controls safety, browser access, reporting, credentials, screenshots, setup, and repeatability. The agent handles the parts that require interpretation. This article describes a practical design for that kind of harness, based on lessons from building one around a remote headed browser provided ... ... wrong thing, whether a modal blocked the page, or whether the UI looks correct but the script failed for the wrong reason. This is where remote-browser.dev becomes valuable. It gives the harness a remote headed browser that can be controlled