The invariant speed of light and the absence of proper time along null trajectories are standard results of relativity, yet they continue to generate conceptual tension when light is treated as a dynamical object propagating through time. This paper provides a law-level structural clarification of light within a closure-based admissibility framework, showing that light is best classified not as a time-evolving entity but as the activation of spacetime’s null relational structure under electromagnetic interaction. The analysis distinguishes sharply between null, record-free coherence and timelike, record-bearing dynamics. Proper time is identified with collapse-mediated record formation rather than with null propagation itself, resolving common paradoxes concerning photon “experience,” frame dependence, and temporal flow without modifying any standard physical laws. A central contribution of the paper is the introduction of a new, fully replicable record-sector observable that measures coherence geometry directly from intensity data. This observable operates entirely on recorded data, requires no time-of-flight assumptions, and introduces no new dynamics. It provides a practical protocol for probing null coherence structure using standard image and signal processing tools. The framework is shown to be compatible with special and general relativity, quantum electrodynamics, and standard measurement theory. Rather than proposing new physics, the work clarifies the structural role of light, time, and causality at the level of lawhood, and offers a falsifiable interface between abstract closure principles and empirical data.