GCFT CDN-162: The Coupling Knows Its Scale — A κ_c Scaling Audit from Magellanic Survival Bounds

CDN-162 formalizes the LMC-orbit collapse found in CDN-161 into a quantitative bound on the GCFT coherence coupling. Sweeping κ_c through the CDN-161 matched stripping machinery at ρ_crit = 10⁴ M☉/kpc³ yields two thresholds for the Magellanic system: leading-arm destruction at |κ_c| ≈ 2×10⁴ and stream non-existence at 5.8×10⁴ kpc² Gyr⁻¹ (at ρ_crit = 10³ the orbit never samples active territory and no bound exists below 2×10⁵). The raw MW–M31 constant (0.5×10⁵) violates the morphology bound — its second kill after Venus (CDN-141) — while the system-scaled convention κ_c = −½·G·M_tot/v_typ (0.79×10⁴ at the LMC scale) passes every bound from Venus to Andromeda and reproduces CDN-139's MW–M31 value exactly. In closed form the law reads a_coh = ½·g_N·(v_r/v_typ)·f(ρ): the coherence response is bounded by half the Newtonian field. The ½ factor is flagged as a standing derivation target from the Ξ kinetic structure. The sweep also sharpens the CDN-161 tension: at ρ_crit = 10⁴, every |κ_c| ≥ 10³ suppresses the stream T/L ratio, leaving no parameter refuge in the upper screening window. Sweep script, results JSON, and figure included. By Nicky Hacquier (Aporion Dynamics) — part of the General Coherence Field Theory research chain, Project Aporion; follows CDN-161 (DOI 10.5281/zenodo.20618694).