Your AI Agent ID Is Not a Version

Yesterday, backend-reviewer inspected pull requests with one model, read only the repository and public documentation, and stopped for human approval before proposing any change. Today it has exactly the same name. The model has changed, the system instructions have been rewritten, incident history is now available as a context source, memory persists between tasks, and database migration changes no longer require approval before they are proposed. The dashboard still shows the same team member. The engineer responsible for quality and risk is looking at a different agent. The identifier stayed. The behavior moved. That distinction is what NexFlow , an open specification for AI developer teams, is trying to make visible. The project does not currently provide a production runtime, a production CLI, or model-provider integrations. Its present job is narrower and, in my view, more important: give teams a language for reviewing agent changes before anything executes. A name answers the wrong question Agent names are useful to people. They distinguish a code reviewer from a documentation writer and establish a long-lived role inside the team. A name says very little about the configuration that produced a particular result. A model change can affect code quality, cost, latency, and the way uncertainty is handled. New instructions alter the order of analysis and the criteria for an acceptable answer. An additional source expands both available knowledge and the exposure surface. Memory carries the consequences of one task into another. A new permission changes more than output style: it changes what an error can damage. For audit purposes, “Which agent did the work?” is therefore incomplete. A second question matters just as much: which version of that agent's definition was active? In draft RFC-0004 , NexFlow separates stable agent identity from a versioned agent definition. Identity contains the role, description, and long-lived responsibility. The definition captures