Senior Full Stack Engineer - Agent Experience

Sydney · Full-time · On-site/hybrid

SuperNinja is an AI workforce that plans, writes code, runs research and ships real work for customers. You would own the surface where people meet that agent — the thread, the workspace, the moment a task becomes a deliverable. It is the highest-visibility slice of the product and it changes weekly.

What you'll do

• Own end-to-end slices of the agent experience — UI, API and the backend services behind them, not just the frontend of someone else's endpoint.

• Ship agent-facing features into production continuously and stay on them: reliability, latency, incidents, observability.

• Turn ambiguous product bets into working software in days, then decide from usage data whether to double down or delete it.

• Work directly with our AI and science engineers on how tools, context and streaming behave in the product.

What we're looking for

• 5+ years building and operating full-stack products in production.

• Strong TypeScript/React (we run Next.js) and genuine backend depth in Python (FastAPI) — you can design a schema and debug a slow query, not only call an API.

• Product instinct: you argue about the shape of the feature, not only the ticket.

• Comfort with high change rates and incomplete specs. Agentic products do not hold still.

Stack: Next.js/React/TypeScript, Python/FastAPI, Postgres/Supabase, AWS (CDK, CloudFront, ECS, Lambda, Cognito), containerised agent sandboxes.