As a Senior Product Security Engineer, you'll partner with product and engineering teams to make what we ship safe by default, splitting your time between building production security services and reviewing what other teams build: designs before code exists, pull requests before merge, and running systems before someone else finds the problem. Backend services and internal tooling - APIs, streaming transports, proxy/CLI/chat interfaces - in whichever of TypeScript, Node.js, NET, or Python fits the problem, held to the same bar as any other production service: test coverage, CI, dependency management.