Quantum-to-Classical Transition as a Witness-Indexed Cross-Scale Process

The quantum-to-classical transition is often operationally identified through one preferred indicator, such as coherence loss, classical record formation or measurement stability. This paper develops a different reconstruction test: classicality is treated as a witness-indexed, observer-explicit and recoverability-sensitive cross-scale transition rather than as a single hard boundary inserted by assumption. Starting from a fine description X, a candidate effective state Γ and a future observable family Y, we define a predictive-retention ratio η_pred=I(Γ;Y)/I(X;Y) and residual ε_cl=I(X;Y|Γ). We distinguish raw relation count from record-forming capacity K_rec^(δ), introduce relation-to-record efficiency κ_R, define a transition spectrum T_C={t_W} across a declared witness family and its width ΔT_C=max_W t_W−min_W t_W, and require observer counterfactuals so that conditioning or readout cannot manufacture a physical transition. An observer-conditioned recoverability diagnostic separates information destroyed, information dispersed into wider system–environment relations and information inaccessible to a restricted observer. The resulting classicality vector is deliberately non-compensatory unless a physical model proves otherwise. The construction is a falsifiable physical-regression architecture, not a derivation of quantum mechanics from Ω₀/A2, and it makes explicit the calculations and counterexamples required before any stronger claim is admissible.