Abstract

We place delayed random access in a complete finite causal network with explicit system ports, classical controls, and record outputs. We prove that scheduled ancestors upper-bound the support of backwards-propagated observables and hence unconditioned operational influence. This bound is not an equality, a statement about conditional correlations, or a certificate of quantum environmental memory. A decoder-relevant storage cut is defined using the complete joint accessible state, including correlated ancillary resources. Freshness of the late query is imposed separately from its absence from the encoding causal past. The cut yields the classical encoding–decoding factorization, from which the established sharp two-state success bound $3/4$ is independently proved. The standard one-qubit value $1/2+1/(2\sqrt{2})$ is realized by sequential local gates and destructive Enter readout. Explicit finite implementations distinguish retained storage from peak ancillary cost. Depolarizing storage gives an exact retention threshold, and parameter perturbations give a quantitative score allowance. Failures remain in the attempted-run law with neutral scores. Complete-law robustness and conditional concentration yield fixed-sample and anytime exclusion certificates. An already quantum carrier requires a different classical-environment null: a Markovian qubit already wins the present task, and a persistent classical register can produce a carrier-only causal-break witness. Finite-capacity bounds and causal-access checking specifications complete the construction. The contribution is the causal-cut and complete-process assembly, not discovery of the random-access benchmark, derivation of the Born rule, physical spacetime reconstruction, or environmental quantum-memory certification.