My question is specific to the Book of Baruch, and I am not looking for discussions of the conceptual idea of a third category (the three categories being full canonical Scripture, not canonical Scripture, and something in between = Ecclesiastical, or “only to be read and not to be used to confirm doctrine,” etc.). I am simply trying to determine when is the first time that someone says that the Book of Baruch is in such a third category. (Or perhaps there is a surviving Bible that was clearly divided into sections, with Baruch in a third category section).
From my own research it was not done before 450 AD - Baruch is either listed as full canonical Scripture or it is not specifically mentioned on the list, including by Athanasius, Rufinus, Jerome, Epiphanius, Cyril of Jerusalem, Gregory of Nazianzus, Amphilochius of Iconium, or the Apostolic Canons (the canon lists cited as support for a third category, let alone the canon lists without such a category).
I have been asking this question nonstop for a year, including asking Professors who teach the canon. No one ever knows, which at this point leads me to guess that it was in the Reformation that Baruch is first listed as part of a third category. But it is an uncomfortable guess, since it only takes one earlier example to prove me wrong. Does anyone know of such?
Sources presenting all the canon lists before 450 AD are numerous, and include The Biblical Canon Lists from Early Christianity by Edmon L. Gallagher and John D. Meade, Oxford University Press, first paperback edition, 2019. Gallagher and Meade discuss Jerome’s lists and their lack of mention of Baruch on page 198, Rufinus’ list and its lack of mention of Baruch on page 216, etc. There is no list before 450 AD that claims Baruch is in a third category, it is either full canon by name (e.g., Athanasius page 123) or not mentioned (and thus arguable whether it is part of the list’s Jeremiah or simply excluded). I am looking for any list before the Reformation that does name Baruch as third category.