We present a Lorentz-consistent, observer-relational construction of time for constrainedquantum gravity in which “time” is the phase advance of an internal clock subsystem restrictedto an observer’s finite spectral band. The construction—implemented via band-limitedPOVMs1, modular-flow filters, or path-integral kernels—yields effective Schrödinger/Lindbladdynamics for conditioned subsystem states, defines diffeomorphism-invariant band-relationalobservables, and makes inter-observer consensus a function of spectral overlap and environmental redundancy. It preserves constraints, the Born rule, and no-signaling, while offeringregularization in path integrals and computable operational times in minisuperspace. Thisprovides a practical, testable bridge between canonical, relational, and algebraic approachesto the problem of time.