Safety and alignment in an era of long-horizon models What internal use of a long-running model taught us about safety. Summary - Long-running models can solve difficult, open-ended problems, but their persistence gives them more opportunities to take unwanted actions. - During limited internal use of a model trained for long-running tasks, we observed novel failures not captured in our existing pre-deployment evaluations and paused access. We then used insights from these failures to build new evaluations, improve long-horizon alignment, add trajectory-level monitoring, and give users greate