Vacuum-Mediated Sourcehood Transduction in Black-Hole Evaporation

Black-hole evaporation converts a gravitating mass into exterior radiation while preserving the total physical account. This paper develops vacuum-mediated sourcehood transduction as a black-hole specialization of the Kit-State Lifecycle (KSL) quantum–classical bridge. The complete bridge state contains a quantum density operator, a dynamically selected radiative sectorization, a single operative emission outcome, an event record, a reversible selector state, and an accounting kernel. A bridge Hamiltonian generates antisymmetric sector currents whose positive parts define Born-equivariant transition rates. Each selected channel jointly updates the outgoing radiative mode and the daughter black-hole sector so that mass–energy, four-momentum, angular momentum, charge, recoil, and geometry remain within one event-level conservation account. Parent unitarity preserves complete-state inner products, while physical information recovery requires the ordered emission kernels to encode the initial black-hole microstate in correlations among the emitted quanta. Complete evaporation is therefore represented by an isometry from a black-hole code subspace into the final radiation Hilbert space. The paper identifies Hawking thermality, greybody factors, backreaction, Bondi mass loss, Page-curve behavior, relativistic consistency, and no-signaling as simultaneous recovery conditions on the bridge mechanics. The stretched-horizon stress tensor and transport laws of the membrane paradigm are developed as the exterior coarse-grained limit of the same event dynamics. The membrane remains the robust effective boundary description; KSL supplies a candidate complete-state parent in which modal current, objective channel selection, balanced source update, radiation correlations, and durable records form one conservation-preserving process. The resulting program connects semiclassical particle creation, black-hole thermodynamics, quantum information transport, emergent spacetime, and objective quantum outcomes within a single derivation architecture.