latent health·Software Engineer·Onsite - System Design / Architecture
Apr 2026
System design round at Latent Health for a software engineering role. The whole session was basically one big deep-dive into designing a preauthorization middleware that sits between EHR systems and insurance payers. Dense, healthcare-specific, and a lot more to cover than I expected in a single round.
- Design a middleware system that sits between EHR providers and insurance payers to handle healthcare preauthorization requests end to end.
- What does the data model look like for this system? Walk through the core entities and their relationships.
- How would you design the API layer, specifically handling the difference between provider-facing and payer-facing interfaces, and how do you deal with retries safely?
- Walk through the state machine for a preauthorization case from submission to resolution.
- How do you handle translation between FHIR, HL7, and X12 formats in this system?
- What are the key non-functional requirements for this system and how do you design for them?
- How would you make this system reliable in the face of downstream failures, including handling retries, failed messages, and data consistency?
“This was the core prompt and it basically ate the whole session.”