Senior Full Stack Software Engineer

About the role You will be the senior engineer across the full stack: backend services, the web application, the React Native mobile application, and the cloud infrastructure beneath them. While a small company, you will coordinate and collaborate with software contractors; your role entails a broad scope, where you make architectural decisions rather than simply implementing them. Research is a genuine part of the role. The engineering practice for this kind of product is not yet settled - how to keep an answer tethered to its source material, how to measure whether a response is faithful to what the expert actually holds, and how to detect it when it is not. You will prototype approaches, run experiments against real expert material, and turn what works into systems that run reliably in production. Key responsibilities Build and operate backend services and APIs, and the data models beneath themDevelop the web application and the React Native and Expo mobile application, including releases to the Apple App Store and Google PlayOwn deployment and infrastructure: CI/CD, infrastructure-as-code, and environmentsMake the architecture decisions - where services divide, how the clients talk to the backend, and what can safely be deferredPrototype retrieval and grounding approaches, and build the evaluations that establish whether they workDesign and integrate a low-latency voice layer that enables users to engage with a mindcast via natural speech, ensuring high-fidelity input and output in productionKeep production healthy through monitoring and performance work, and investigate when something breaksIdentify where the current architecture is limiting and propose the changeAbout you A degree in computer science, software engineering or a related fieldAt least five years of commercial software engineering experience, across the full development lifecycle from requirements through to production supportStrong backend depth: services, APIs, relational data modelling, and migrations you have had to get right the first timeWeb and mobile development experience. React Native and Expo preferred, though native or another cross-platform stack is equally relevantAI-native working: you direct coding agents as a primary way of building, and you design evaluations for systems whose output is not deterministicExperienced in CI/CD pipelines and infrastructure-as-codeClear written English. Most decisions here are written down before they are builtAbout us Polyworld Australia Pty Ltd builds mindcasts: a conversational form of an expert's work, in which every answer traces back to what that expert has actually said, written and argued. It is not a general-purpose chatbot. It is one named person's knowledge and reasoning, available to be questioned directly, at any hour and from anywhere. Benefits Conveniently located office in Bondi Junction. On the Eastern Suburbs line and the bus interchange, a short walk from the beach, and not a CBD commuteFull technical ownership and direct founder collaboration: you own the architecture and product decisions with no inherited roadmaps or top-down mandatesResearch as a real part of the job rather than a side project. The grounding and evaluation problems are genuinely unsolved, and working them out is the workSuperannuation paid in addition to the salary