Time as Integration Constraint: Reconciling Timeless Physics with Proper Time

Many approaches in fundamental physics suggest that time is non-fundamental or eliminable at the level of physical law. This paper argues that such results do not license the conclusion that time is illusory. Instead, time is reconceptualized as a structural constraint arising from the limited capacity of finite systems to integrate changeunder a universal causal bound. Proper time is shown to correspond to integrable change along a worldline rather than to an independently flowing parameter.This framework reconciles timeless physics with temporally structured experience without reintroducing a global time variable.