A1 is building a proactive AI chat app for everyday users to bring intelligence to conversations, errands, organising and workflows. Unlike traditional chat‑based applications, our product focuses on achieving high reliability for long‑running workflows, persistent context, and real‑world task completion. The system must handle multi‑step reasoning, interact with external tools, and remain reliable despite non‑deterministic model behaviour. We are looking for a Full Stack Engineer – AI Systems to build the product layer that turns these capabilities into usable, production‑grade workflows. This includes designing how agents operate, fail, recover, and deliver consistent value to users.