Deploy, celebrate, ship → quiet catastrophe. Months pass, model silently degrades. Validation was 95%, production is 60%. The culprit: the world changed, data drifted. Today covers SageMaker Model Monitor — detecting data/model drift without labels — and automating retrain on alarm.
Deployed model relies on learned patterns. Real-world distribution shifts:
Ground truth (actual labels) arrives late or not at all. So monitor input distribution as proxy alarm.