LLM-as-judge with human-agreement calibration; statistical rigor - paired comparison, confidence intervals, repeated sampling, pass^k; held-out and time-rolling eval splits with overfitting alarms; cascaded scoring and cross-family judge panels to make evaluation affordable at scale. Tools-as-APIs, connectors, skill / tool search for large inventories, and skill-library governance - description conflicts, trigger evals, cross-skill mis-fire matrices, and on-demand loading instead of dumping every definition into context.