Retrieve clinical notes via DocumentReference and fetch CDA or PDF attachments

Steps

1. Search for clinical notes: GET [base]/DocumentReference?patient=[id]&status=current&type=[LOINC-doc-type-code]; common LOINC document type codes include 34133-9 (Continuity of Care Document) and 11506-3 (Progress note).
2. Extract content[].attachment.url for each document; this may be a direct URL to retrieve the binary content or a reference to a Binary resource.
3. Retrieve the binary: if attachment.url is a relative or absolute FHIR URL, perform GET [url] with the same bearer token; the response is the raw document (PDF bytes or CDA XML).
4. Check attachment.contentType: 'application/pdf' for PDFs, 'text/xml' or 'application/xml' for CDA documents, 'text/plain' for plain text notes.
5. For CDA documents, parse the XML to extract the structured body or narrative text; the ClinicalDocument/component/structuredBody path contains coded section content.
6. Inspect context.encounter to link the note to its associated Encounter resource and context.period for the note's relevant date range.