How we stopped debugging agent failures after the fact and started preventing them upfront The Problem You're running an LLM agent pipeline in production. Something goes wrong. You open the logs. You see what the agent returned. You see that it failed. But you have no idea what the state of the system was before it happened — what data went in, whether preconditions were valid, which policy was silently violated three steps earlier. Logging tells you what occurred. It doesn't tell you what was allowed to occur. This is the gap we kept hitting. Every team we talked to running agents in production has some version of this problem. Most solve it with ad-hoc assertions, careful logging, and hope. We wanted something systematic. So we built DEED. The Wrong Mental Model When something breaks in a traditional service, you look at the request that came in and the response that went out. The failure boundary is clear. LLM agent pipelines don't work like that. Each step transforms a shared state object.…