Implement the Da Vinci PDex Payer Data Exchange to enable a new payer to request a member's clinical and claims history from a prior payer during the plan-to-plan data exchange workflow

Steps

1. Implement member attribution by matching the new plan's member to the prior payer's member record using the $member-match operation, submitting a Parameters bundle with Coverage and Patient resources
2. Receive the matched member identifier from the $member-match response and store it as the cross-payer patient reference for subsequent data requests
3. Invoke the $everything or $export operation (depending on the PDex implementation guide version) on the matched patient at the prior payer's FHIR endpoint to retrieve all available clinical and claims data
4. Process the returned FHIR Bundle containing ExplanationOfBenefit, Condition, Observation, MedicationDispense, and other clinical resources, mapping them to the new payer's internal data model
5. Implement the PDex MedicationDispense profile to correctly represent dispensed medications received from the prior payer, noting that PDex uses MedicationDispense rather than MedicationRequest for claims-derived medication data