Finite Record Boundaries in Wigner’s Friend Scenarios: Observer-Relative Distinguishability and Quantum Record Availability in Finite Distinction Systems

Wigner’s friend scenarios expose a tension between two descriptions of the same quantum experiment: the friend may stabilize an internal record, while Wigner may treat the larger sealed laboratory by a different state assignment. FDS-Q1 develops a finite-record boundary account of this tension. It does not solve the measurement problem, derive the Born rule, replace decoherence theory, modify unitary quantum mechanics, or claim that consciousness causes collapse. Instead, it treats observers as finite distinction-registers and measurements as stable record formation under finite capacity. The central quantitative object is the boundary-mismatch entropy MF |W = H2(ZF |ZW ), which bounds Wigner’s ability to promote a friend-relative record into a Wigner-accessible operational fact. The core condition is H2(ZF |ZW ) ≤ ϵ, equivalently I2(ZF ;ZW ) ≥ H2(ZF ) − ϵ. Q1 does not infer physical coherence from Wigner’s ignorance: Wigner’s ideal global coherent assignment requires isolation and reversible-control assumptions, whereas Wigner’s operational state is obtained by tracing out inaccessible degrees of freedom. Decoherence and environmental redundancy increase cross-boundary availability; once redundancy, accessibility, and record stability exceed a threshold, finite observers converge on the same branch record. Q1 therefore reframes Wigner-friend tension as a finite record-boundary promotion problem, not as a collapse theory or a probability derivation. The refinement strengthens the physical record criterion with a retention window and error tolerance, recasts boundary promotion as an operational criterion rather than a tautological theorem, sharpens the finite-access reconstruction bound via Fano’s inequality, defines objective availability through environmental fragments, and introduces a record-availability horizon for quantum-device diagnostics.