Implement Da Vinci CRD (Coverage Requirements Discovery) hooks to surface prior auth and documentation requirements at point of care

Steps

1. Register your CDS Hooks service endpoint in the EHR's CDS Hooks discovery document; implement at minimum the 'order-sign' hook and optionally 'order-select', 'encounter-start', and 'appointment-book' hooks as defined in the CRD IG
2. When the EHR fires a hook, receive the JSON CDS Hooks request: extract the context (draftOrders Bundle, patient ID, encounter ID) and the prefetch data (Coverage, Patient, Encounter resources) from the request body
3. Query the payer's CRD service (or proxy your own service to it) using the coverage and order details; the payer CRD service evaluates rules and returns CDS Cards
4. Return CDS Hooks response cards: an 'information' card for documentation requirements, a 'warning' card for items requiring prior auth with a SMART app launch link for the DTR flow, or an 'critical' card if the service is not covered
5. If a prior auth is required, include a 'suggestion' action that adds a Task resource to the EHR referencing the authorization requirement, and a 'link' to the DTR SMART app for questionnaire prefill
6. Log all hook invocations and responses for audit; CRD responses must be returned within a latency threshold acceptable to the EHR (typically under 5 seconds) or the EHR will timeout and ignore the cards