production Java services and RESTful APIs (Spring Boot or similar), designed for integration by multiple consuming systems and documented to OpenAPI • Design and implement MongoDB document models, aggregation pipelines, indexing and sharding strategies, and integrate them cleanly into Java service layers rather than through a leaky abstraction • Build data pipelines … streaming ingest, transformation frameworks, checkpointed batch extract workers, and MongoDB sink configuration and tuning at terabyte scale • Implement access control, encryption and audit within the application and data layer, including enforcement inside the MongoDB query path, rather than bolted on around it • Write the tests: unit, integration, golden-record fixtures ...