Introducing Harmonia: Read, Write, Think for OMOP Concept Mapping
Concept mapping is the single largest line item in any OMOP CDM ingestion budget. Published estimates put it at 40–60% of total ETL effort per source system — measured in clinician-weeks, not engineer-hours. Today we landed the architectural piece that's been missing from Parthenon's vocabulary stack since the beginning: Harmonia, an automated decision layer that sits between Hecate (read) and Ariadne (write) and does the cognitive work that's been falling on humans.
The name is deliberate. In Greek mythology, Harmonia is the goddess of agreement, accord, and fitting together — daughter of Aphrodite and Ares, born of love and conflict. That's what concept mapping is: bringing disparate source vocabularies (an ICD-10 code from one EHR, an NDC string from another, a hospital's local lab nomenclature) into harmony with a single canonical OMOP standard. Every approved mapping is a small act of harmony. Until today, Parthenon could show candidates and record decisions but couldn't reach harmony on its own.
This post walks through what we built, why it's an improvement over the existing Hecate + Ariadne pair, and the four real bugs we hit getting a benchmark to actually run.