A feature store exists because the same feature gets computed twice — once in a batch job for training and once in a service for scoring — and the two definitions drift apart. This page shows one feature breaking, in eight lines, and the join that stops it. One feature, two definitions The feature is avg_order_value_30d . It appears in a fraud model. The training set is built in the warehouse: -- training pipeline, run nightly over history SELECT o . order_id ,...