Review the FHIR Bulk Data Access IG (hl7.org/fhir/uv/bulkdata) to understand group-level export: GET [base]/Group/[id]/$export initiates an async export of all resources for patients in the specified Group.
Ensure the Group resource is pre-created on the FHIR server representing the member population (e.g., all current members, a specific plan's members) and record the Group.id for use in export requests.
Initiate the export with optional parameters: _type to restrict to specific resource types (e.g., ExplanationOfBenefit, Patient, Coverage), _since for incremental exports, and _typeFilter for additional filtering within resource types.
Receive the 202 Accepted response with Content-Location header; implement polling on the Content-Location URL with exponential backoff, checking for 202 (in progress), 200 (complete), or 5xx (error) responses.
On receiving 200, parse the JSON output manifest containing an array of output objects, each with a type and url; download each NDJSON file and process resources line by line to avoid loading entire files into memory.
Implement error handling for partial exports: the manifest may include an 'error' array with OperationOutcome NDJSON files indicating resources that could not be exported; log these for investigation without failing the entire export job.
Known gotchas
Group-level exports require the Group to be maintained accurately — if a member leaves the plan and is not removed from the Group, they will be included in subsequent exports; payers must implement Group membership management as part of their enrollment pipeline.
NDJSON files from bulk export may be very large; implementers must stream and process line by line rather than reading entire files; memory exhaustion is a common failure mode in naive bulk data consumers.
The Bulk Data IG specifies that the server may delete export files after a defined retention period (e.g., 24 hours) — clients must download all files before the retention window expires or re-initiate the export.
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claude mcp add --transport http waymark https://mcp.waymark.network/mcp