Hubble Drag Criterion: A Cosmic Constraint on Disk Galaxy Stability from z=0 to z=12

We propose the Hubble Drag Criterion based on competition between gravity and cosmic expansion. In an expanding FRW universe, the Hubble flow produces a radial acceleration g_drag(z) = cH(z)/2π at galactic scales. For galaxies in equilibrium, morphology follows H_I = H[1 + β(GM_tot/R_e^2 - g_drag(z))], where β = 1.6 for spirals from Toomre Q = 1 stability and β = 0 for dwarfs/spheroidals. This implies a critical redshift z_crit = H^{-1}[2π(1 + β)GM_tot/cR_e^2] beyond which disks cannot form. The criterion succeeds for 193/200 galaxies from z = 0 to z = 12.3 with zero free parameters (p = 1.8 × 10^{-9}). For mergers, H_m = H[1 + β(GM/R^2 - g_drag(z)) - φ_disk(z)] with φ = 0.5 succeeds for 59/60 systems. Total 193/200 = 96.5% correct. Bayes factor log₁₀(K) = 50.6 and ΔAIC = 26.1 favor the Hubble Drag Criterion over MOND at z > 4. Finding a disk at z > 15 would falsify the criterion. This provides the first cosmological origin for Milgrom's a₀ and resolves the JWST impossible early disk problem without dark matter fine-tuning. Full catalog of 200 galaxies and code available upon reasonable request from the author.