The distinction between "long-running agents" and "long-running responsibilities" is the part that stood out to me. A lot of teams focus on making agents autonomous, but the harder production problem is making their state, decisions, and stopping conditions auditable. We've found that treating external state and acceptance criteria as first-class artifacts makes debugging and governance much easier than relying on conversation history alone. Nice breakdown of why operations, not just model capability, becomes the bottleneck as agent systems mature.