Senior AI Agent Infrastructure Engineer - Autonomous agent for an AI workforce platform

We are building an AI workforce platform: autonomous AI "employees" that run operations for small businesses, not chatbots or copilots, but agents that execute real work end to end (answering, quoting, invoicing, reconciling, reporting) under owner-defined policies. We are funded and have a detailed architecture already specced. We need a senior engineer to build the foundational agent runtime and bring our first agent to life: "Sam," an Operations and Finance agent. This is a foundational build. The patterns you establish here become the substrate every future agent runs on, so we are looking for someone who has built production agent systems before, not someone learning on our dime.