James Gilmore enhanced patient-provider interoperability in the CDCgov/prime-reportstream repository by developing robust HL7 PD1 segment mapping features. He implemented bidirectional FHIR-to-HL7 and HL7-to-FHIR data transformations, focusing on accurate mapping of PD1.4 fields to Practitioner references and supporting patient-primary-provider flows. Using YAML for configuration and leveraging deep knowledge of HL7 and FHIR standards, James refactored the generalPractitioner mapping logic to flexibly support both organization and practitioner references based on PD1.3 and PD1.4 data. This work improved data consistency and attribution, addressing complex interoperability requirements and laying groundwork for more flexible provider mapping in healthcare data exchange.