The AI Engineer builds production agents end-to-end on an AI-native retail decisioning platform - prompt design, tool definitions, multi-step workflows on the agent runtime (LangGraph, CrewAI, or chosen framework), evaluation harnesses (golden sets, regression gates, multi-step replay), human-in-the-loop gate integration, and per-agent cost optimisation. Build agents on the platform's agent runtime - prompt design, tool definitions, multi-step workflows, error handling - and ship them with eval harness, human-in-the-loop gate config, observability instrumentation, cost meter, and runbook.