An improved lower bound for error-detecting locating-dominating sets in the square grid

Every DET:LD set in the infinite square grid, in the one-false-negative detector model, has lower graph-ball density at least 168/295 at every center. The comparison uses the updated literature interval [12/23,7/12]. The exact minimum remains open. The detector-report condition is checked against the combinatorial criterion. An integer discharging certificate is verified over all 2^25 local patterns, and the analytic argument handles arbitrary plane configurations.