The path from a source to an answer
Did the agent open a source that contains the expected fact?
Exact-document retrieval from the indexed collections fell from 40% to 14%: the clearest regression in the study.
A miss here means: the search never surfaced the right source. Many teams instrument only this point.
Baseline → final version. Each number has its own denominator, so they do not chain: 01 counts exact documents from the indexed collections, 02 counts facts, 03 counts excerpts the research agent had read, 04 counts questions. 02 and 03 cover reference-document evidence.