h2·Software Engineer·Onsite - System Design / Architecture
Apr 2026
System design round at h2 for a software engineer role. The whole thing was basically one massive open-ended question about building an annotation workflow engine from scratch, and they let you use Claude which was a nice surprise but also kind of made me second-guess how much I was actually being evaluated on.
- Design an annotation workflow engine that supports dual-review pipelines, conflict adjudication, revision loops, and a full analytics layer. Walk through the data model, state machine, APIs, assignment strategies, and how you'd handle scale and extensibility.
- How would you handle idempotency in the annotation submission API, especially with retries and concurrent annotators?
- How would you design the system to support new pipeline shapes beyond dual-review, say a three-way review or a single-pass pipeline?
- Walk through the pluggable assignment strategies. How would round-robin, skill-based, and load-balancing differ in implementation, and how do you swap between them?
- What metrics would you expose in the analytics layer, and how would you compute per-annotator agreement rates at scale?
“This is a beast of a question.”