Gravitational-Wave Propagation in the Aldred Frame: Speed, Luminosity Distance, and the Bounds from GW170817

In Einstein-Cartan gravity torsion is algebraic and confined to matter, and the spin-fluid correction is drho/rho = rho/rho_A with rho_A = 9.72e54 g/cm3. In vacuum the gravitational-wave speed and luminosity distance receive exactly no correction; in matter any propagation shift is bounded by rho/rho_A. The GW170817 path-averaged fraction is 4.30e-83, the largest fraction on any realistic path is 2.05e-40 (neutron-star centre), 24.7 orders below the GW170817 bound of 1e-15; a 1e-15 anomaly would require traversed density 9.72e39 g/cm3. AI-use disclosure: computational and drafting assistance was provided by Dave, an AI system; the author reviewed and takes responsibility for the contents.