Each patch event is an assertion. The stream is an append-only log. The final object is a materialized view. This is how databases have always worked — objects are views over fact logs, not the other way around. The log is primary; the object is derived. Treating the complete JSON response as the primary artifact and the stream as a delivery mechanism has it exactly backwards. The stream is the source of truth. The object is a convenience snapshot for consumers who do not need real-time access to facts.
(The fundamental unit of LLM output is a fact, not an object · Agent traces are first-class artifact of software development)