AI Phone - Senior Agent Runtime Engineer

About We are reimagining the phone. AI phones need to be proactive, intuitive, intelligent and low cost. This is a mission critical for rest of the world to adopt intelligence. There are over 5 billion people using everyday applications such as email, messaging, notes, tasks, and calendars, yet most are not AI-native. Our mission is to build proactive applications and devices that bring intelligence into daily conversations, coordination and workflows, with minimal prompting. Focus: Building the actual execution infrastructure for AI agents. Responsibilities Implement agent runtime and orchestration components. Build tool-calling and execution interfaces. Support multi-step and long-running task execution. Manage task state, execution history and asynchronous workflows. Implement error handling, retries and recovery mechanisms. Integrate multiple model providers. Build observability and tracing for agent execution. Optimize latency, reliability and inference costs. Work with context and memory components to provide relevant information to agents. Requirements Strong backend engineering experience. Experience with distributed systems and asynchronous workflows. Experience integrating LLMs into production applications. Strong API and service architecture knowledge. Experience with queues, state management and observability. Good understanding of tool calling and structured outputs. Nice to have Production agent framework or custom agent runtime experience. Experience with Temporal or similar workflow orchestration systems. Experience with model routing and inference optimization. Experience with AI evaluation and tracing.