Why this exists
Every healthcare platform I've touched paid the FHIR tax twice — once at serialization, once at validation — and never actually let FHIR structure the domain. Constellation starts from Zod-expressed FHIR and lets that shape the code.
What it does
Three products share a FHIR-native core: ARIA (electronic health records), ORBIT (practice management), MERIDIAN (pharmacy). Each runs as independent Fastify services over a shared domain package, composed via pnpm workspaces.
What I learned
Modeling FHIR in Zod is worth every keystroke — runtime validation, TypeScript types, and JSON Schema generation all fall out of the same source of truth. The hard part was not the schemas; it was agreeing on which parts of FHIR were actually load-bearing for each product.