URMC: A Formal Model of Resilience, Temporal Buffering, and Local Irreversibility in Digital Payment Systems

This preprint introduces the first comprehensive structural framework explaining why digital payment systems can fail for individuals even when they appear fully operational at the macro level. Using the Universal Regularized Cascade Metric (URMC) and the newly formalized Dependency Structure Theorem, the analysis reveals how coupled digital dependencies, temporal recovery gaps, and local irreversibility zones create hidden failure modes that directly impact access to food, mobility, and shelter. The work provides a mathematically grounded model of resilience, temporal buffering, and cascade amplification, offering a new lens for evaluating digital‑only payment architectures. It identifies structural vulnerabilities invisible to traditional uptime metrics and demonstrates why physical cash functions as a distinct fail‑safe layer under stress conditions. This extended analysis is designed for researchers, regulators, civil preparedness authorities, and infrastructure planners seeking a rigorous, system‑level understanding of digital fragility and human‑scale access risk.