Agents Love The Web Platform's Backward Compatibility

Without further instructions, an agent writes web code from everything it saw during training: tutorials, framework docs, Stack Overflow answers, blog posts from 2014. The output mixes all of it. Restricting the grounding to normative Web Platform specifications (HTML, DOM, CSS, ECMAScript, ARIA) removes the mix. The Web Platform is unusual as a corpus, because it hardly contradicts itself. A DOM…