The relation between gravity and quantum coherence remains an open problem at the foundations of physics. While several models predict gravity-induced loss of quantum coherence, most rely on mass-dependent mechanisms or stochastic modifications of quantum dynamics, leading to negligible effects for massless particles such as photons. In this work, we propose a minimal and experimentally falsifiable mechanism in which decoherence arises from irreversible interaction events occurring at a rate influenced by gravitational potential differences. The model introduces no collapse postulate and preserves unitary evolution between events. We derive an effective Lindblad-type evolution in which gravitational potential gradients induce visibility loss independently of gravitational phase shifts. A key prediction is that quantum interference of photons exhibits a measurable reduction in visibility proportional to gravitational potential difference and interaction time. We propose concrete experimental tests using existing photon interferometry and satellite–ground quantum communication platforms. The model is decisively falsifiable: the absence of such visibility degradation beyond standard phase effects would rule it out.