Classical Simulation of Two-Layer Quantum Circuits via Output-Dependent Cubic Structure

Informal methods preprint giving an original-source construction for estimating one output probability of specified two-layer Boolean cubic-phase circuits. Output-dependent sector restriction and established equatorial norm estimation yield a 2^k readout factor with explicit discovery promises and complete finite-bit costs. Growing families and matched comparisons retain the larger small-k sampling constant and certificate-specific limits. Includes internal mathematical and executable checks, with AI assistance; not peer reviewed or Lean certified.