Source Poverty and Canonical Admissibility in Fibered Descent Systems

Three independently discovered collapse phenomena — in monadic model theory, categorical semantics, and topos theory — share a common fibered descent structure. In each case, target content is constrained to a canonically determined admissible region computed from a source, and collapse occurs when the source is informationally trivial. We identify two modes of canonical admissibility: a reflective fixed-point mode (available when round-trip transport exists) and a descent-equalizer mode (availa