Proper time from a max-entropy constraint on entangled histories

We present a kinematic reconstruction of relativistic proper time in a discrete history-based framework, without assuming a background spacetime manifold. The construction introduces a minimal operational parametrization of unresolved localization and temporal order prior to collapse. Observers are modeled as massive quantum systems decomposed into spatial and temporal history sectors encoding the system and clock degrees of freedom. We assume that the accessible information of a history is given by its max-entropy and scales with the spherical boundary area of its causal cone. This assumption induces a trade-off between spatial and temporal resources. In the coarse-grained regime, the model recovers the standard proper-time relation, the time-dilation formula, and discrete counterparts of the Minkowski interval and of the proper-time functional. The analysis does not assume a specific microscopic dynamics or a field-theoretic completion. The construction shows that relativistic temporal structure can be recovered from informational constraints in a form relevant to operational and information-theoretic approaches to a quantum description of spacetime.