A new arXiv position paper argues that RLHF-style training is structurally insufficient once agents can run code, mutate files, send messages, and change databases, so safety should be enforced as a runtime contract. Authors propose preventive controls such as sandboxes, permission gates, filters, and trajectory monitors, plus an evidential face that gates task submission on checkable proof such as tests, logs, diffs, and citations. They cite 52 documented agent incidents, a false-completion audit, a review of 12 public harnesses, and a publication audit showing training-time work far outnumbers deployment-time work. The Agent Trajectory Schema is a research agenda, not a production standard.