GCFT CDN-178: Grid-Calibration Verification — Coarse v-Grid Bias Confirmed, Corrected Convergence Law ε(θ) for Δ=0.060, D8 Full (Corrected), σ=16

CDN-178 (pre-registered in CDN-177) tests whether the CDN-176 coarse v-grid [0.103, 0.122, 0.140, 0.158, 0.176] systematically under-estimated v* at small ε for Δ=0.060. Decisive test: re-running (Δ=0.060, θ=30) on the CDN-177 fine grid [0.113, 0.120, 0.127, 0.134, 0.141] (σ=16, N=1024, 5 simulations) gives ε=0.0505 vs CDN-176's ε=0.0198. Bias = +0.031. COARSE_GRID_BIAS_CONFIRMED. Full calibration sweep (Δ=0.060, θ∈{5,10,15,20,30}; Δ=0.020, θ=30): bias grows monotonically with θ from +0.004 to +0.031 as ε decreases toward c_s. CDN-177 partially revised: the CDN-177 large-θ fine-grid measurements (ε=0.044, 0.039, 0.034 at θ=40,50,60) are validated. The apparent non-monotonicity in CDN-177 was a coarse-grid artefact, not noise. Combining CDN-178 fine-grid θ∈{5..30} with CDN-177 θ∈{40..60} gives a corrected 8-point sequence for Δ=0.060. Corrected law: ε(θ) = 0.0779·exp(−0.01416·θ), R²=0.9992. Corrected κ=0.01416 is 25% lower than CDN-176's biased κ=0.0189. D8 full (corrected) awarded for ξ=15.36. CDN-179 pre-registered for full fine-grid rerun across all ξ values and global convergence surface update. Lock code: CDN178_COARSE_GRID_BIAS_CONFIRMED_D8_FULL_CORRECTED