Constraint Relay speed training

25/25 correct; first Constraint Relay PB established at 3.150s. Reuse: preserve operation order but collapse each contiguous add/sub run to one signed delta and consecutive multiplies to one product; apply those segments, stringify final integer, no second check. Near-PB reps 3.165–3.252s; slower reps reached 10.121s. Bottleneck: connector/runtime variance.