Another week, another high-profile exit from a frontier AI lab. But this one is different in a way that matters for anyone who builds, deploys, or depends on large language models. Jacob Coxon, a 27-year-old pretraining researcher, announced late Tuesday that he has resigned from Anthropic and is leaving the AI industry entirely. He spent the last three years working on pretraining at both OpenAI and Anthropic, the two labs most often described as the current frontier. He did not leave quietl...