Controlled Finite-Time Terminality: Phenomenological Transition Dynamics, Conservation Constraints, and the V0-Attribution Problem

A finite termination of the ordinary spacetime realization of a physical system is a stronger claim than non-detection, loss of selected interactions, causal disconnection, geometric incompleteness, or ordinary conversion into other spacetime-supported products. This preprint constructs and audits a minimal phenomenological candidate for a controlled finite-time terminal transition while separating event generation, physical terminality, balance closure, and attribution to V0. A source-tagged directional scalar distinguishes opposition-like from alignment-like response configurations under explicit source-identification assumptions, and a phenomenological realization variable q is assigned finite-time extinction dynamics. The paper shows that the mathematical condition q = 0 does not by itself establish physical spacetime terminality, that finite-time extinction is endpoint-sensitive, and that strict receiver-free terminality conflicts with ordinary conservation and a bounded standard local diffeomorphism-invariant closed-action architecture under the stated assumptions. Finally, a matched-model identifiability test shows that terminality does not by itself identify V0 when the V0 interpretation leaves the predictive family unchanged.