## Problem To Solve The current logging in the ETL engine is insufficient for debugging and operational visibility. Inconsistent or missing log output makes it harder to diagnose issues, especially in production where you can't attach a debugger and need to rely on what the system tells you. ## Proposed Solution Add structured, leveled logging throughout the ETL engine with consistent formatting, contextual metadata (such as message IDs, entity types, and processing stages), and appropriate verbosity levels for production use. Logs should be useful without being noisy.