Audited Laptop-Scale 512^3 Quantum-State Simulation: A REPA-Governed Solver Stack Beyond the Cluster-Only Assumption

This paper reports an audited solver-evidence package for laptop-scale quantum-state simulation. The flagship result is a $512^3$ internal-state complex simulation executed through a oneAPI CPU three-dimensional split-step lane on an HP Victus 16-class laptop with an Intel Core i7-14650HX processor and approximately 32 GB RAM. Run-local manifests identify the run as complex split-step evolution with oneAPI backend, double precision, ten configured time steps, nine evolved split-step diagnostic rows, zero norm drift from unity, and two-dimensional slice-plane persistence. The $512^3$ result is not a PARDISO scaling claim and not a Crank--Nicolson GMRES/multigrid claim. Separately, the Crank--Nicolson Hermitian lane is validated through controlled conservation tests and through a custom GMRES/multigrid solver compared against a PARDISO direct-solve reference oracle at three-dimensional calibration scale. The work is deliberately verification-first: dimensions, routes, manifests, hashes, SecureLogger-style provenance, and failure boundaries determine which claims are public-manuscript eligible. The conclusion is narrow and uncomfortable: for this constrained class of audited split-step internal-state simulation, the cluster-only assumption is no longer safe.