Apple’s new on-device Foundation Models are amazing… until they aren’t. After months of building prototypes, breaking prototypes, and discovering things Apple definitely forgot to mention, I’ve collected the patterns that actually work - and the traps developers fall into again and again. In this fast, practical session, we’ll look at how real apps use Foundation Models for summaries, planning, personalization, and Vision+FM magic. I’ll share the engineering tricks Apple never tells us, plus live demos (including a few “please don’t crash on stage” moments) showing both the impressive and the unintentionally hilarious sides of on-device AI. You’ll leave with concrete patterns, guardrail-friendly prompts, performance tips, and a clear sense of what you can safely ship - and what you absolutely shouldn’t trust a small on-device model to do.