Prompt once, integrate everywhere: Scaling Expo Brownfield Across 100+ Open-Source Native Apps

You don't always get to start from scratch. Millions of apps in production were built natively, with years of platform-specific decisions, entrenched build systems, and teams that now can’t justify a full app rewrite. So what if adding Expo felt like installing a library instead of migrating to a full new framework? This talk walks through the new features of Expo Brownfield and how we fine-tuned a skill to help automate the full integration process. Over months, we battle-tested it, running it against 100+ open-source native apps across wildly different project structures and build configurations. Come see what broke, what surprised us, and what a repeatable path to React Native adoption really looks like at scale.