Hedera — the Hashgraph consensus node
As technical lead of the consensus team, I work on the core of the Hedera network — how nodes gossip events to one another and reach agreement, the implementation of the Hashgraph consensus algorithm itself. It’s the part of the system where correctness and resilience matter most, and the kind of problem I do my best work on. I’m a CODEOWNER of core areas of the codebase.
One example from that work is Otter, a JUnit-based test framework I designed and led the development of. The consensus nodes had been covered by a framework that was overengineered, slow, and unreliable: tests ran once a night, the morning’s failures usually turned out to be the brittle environment rather than real bugs, and some scenarios couldn’t be tested at all. Starting from little more than “we need something better,” I created the vision and design for a framework that stands up a local network of consensus nodes and deliberately injects the network failures and edge cases that are otherwise nearly impossible to reproduce. I shaped the API to be powerful but simple and built some of the hardest parts myself, while leading the team to a shared understanding so they could carry it forward. Today the tests run on every pull request with automated reporting and no manual work — the suite is stable, trusted, and growing, and it has surfaced bugs that were previously untestable.
Open source, as part of the Hiero consensus node: github.com/hiero-ledger/hiero-consensus-node