Keep the planner thin to scale multi-agent AI

Home Depot cut delivery failure rates from 5.3% to ~2.8% in Chicago using a purpose-built agentic system — and it's protecting 1.5 million at-risk deliveries a year across weather, geospatial, and customer preference signals. Home Depot CIO Angie Brown breaks down exactly how the sixth-largest U.S. e-commerce operation ($25B+ in online sales, 2,300+ stores) built its production AI stack from the ground up. The architecture is a layered agent hierarchy: a thin client planner routes to domain agents (selling, post-purchase, delivery), which hand off to fine-grained sub-agents by category — pain