Zero-Sum node reconfiguration in a discrete spacetime substrate

The physical origin of late-time cosmic acceleration remains uncertain, motivating investigation of whether a discrete spacetime substrate can reproduce vacuum-like expansion without introducing an explicit cosmological constant. In this work, a phenomenological finite-capacity node model was developed to examine the cosmological consequences of an energy-conserving (zero-sum) discrete substrate and to evaluate its consistency with established cosmological constraints. Alternative dissipative and radiative variants were considered as consistency checks but were found to be incompatible with vacuum-like expansion or existing observational limits. Within the zero-sum framework, local compensation implies a robust k4-suppressed infrared correction to the primordial spectrum, while the broader blue-scar form was retained as a phenomenological template for small-scale observational testing. Representative realizations of this template were benchmarked against published 21-cm constraints on small-scale primordial power, yielding preliminary bounds on the observationally permissible blue-scar amplitude and turnover scale. Although the framework does not constitute a microscopic derivation of dark energy, the results demonstrate that an energy-conserving discrete-spacetime hypothesis can remain compatible with current cosmological observations while providing a constrained, testable phenomenological signature for future observational studies.