Aggregator for the Scala side of the engine. Four layers, strictly ordered: interceptor-api - Spark-agnostic SPI. No concrete Catalyst types. interceptor-dispatch - ServiceLoader-based runtime shim selection. interceptor-runtime - SparkSessionExtensions + Rule[LogicalPlan]. interceptor-spark-* - One implementation per Spark/Scala combination. interceptor-bundle-* - Shaded fat jar consumed by the Python wheel. Module order below is the dependency ...