The DQNConfig construction in trainer.rs hardcoded weight_decay to 1e-4, ignoring the hyperopt-tuned value in DQNHyperparameters. This meant PSO optimization of weight_decay (search space index 17, range [1e-5, 1e-3]) had no effect on actual training runs. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>