Implement SMART App Launch v2 EHR launch flow including fhirContext extraction for multi-resource launch context
domain: hl7.org · 6 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Receive the EHR launch by detecting the launch and iss query parameters when the EHR redirects to the app's launch URL
Fetch the SMART configuration from [iss]/.well-known/smart-configuration to obtain authorization_endpoint and token_endpoint
Redirect the user to authorization_endpoint with response_type=code, client_id, redirect_uri, scope including launch and any resource scopes, state (random nonce), and the launch parameter value from step 1
Receive the authorization code at the redirect_uri; exchange it for tokens via POST to token_endpoint with grant_type=authorization_code, code, redirect_uri, and client credentials
Inspect the token response for patient, encounter, and fhirContext fields; fhirContext is a JSON array of objects each with a reference field pointing to a FHIR resource the EHR considers in context
Resolve the fhirContext references via the FHIR server using the access token to retrieve the full resources needed to initialize the app's UI
Known gotchas
fhirContext is a SMART v2 addition not present in v1 token responses; apps must check for its presence rather than assuming it exists
The launch parameter value is opaque and EHR-specific; do not parse or decode it — pass it unchanged to the authorization endpoint
The state parameter must be validated on redirect return to prevent CSRF attacks; reject any authorization response where the returned state does not match the sent value
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