How Stripe, Shopify, and Airbnb Build AI Harnesses

TL;DR There is no single model of harness engineering. OpenAI builds repository-centered harnesses, Anthropic focuses on agent cognitive continuity, while companies like Stripe, Shopify, and Airbnb develop vertical harnesses built around compliance, context, and action verification. Harness engineering is becoming a domain-specific discipline, shaped by the type of risk each company needs to control. Why There Is No Single Harness: Stripe, Shopify, Airbnb, and the Industrial Fragmentation of Age