At Attio, one TypeScript codebase powers everything from our powerful UI to our flexible data integrations. In this talk, I’ll show how we embrace radical pessimism — always assuming things will go wrong — as a guiding principle for building resilient systems. Using functional programming concepts, we handle errors and loading states across the stack in a type-safe, ergonomic way. You’ll learn how pessimistic thinking in programing can lead to safer, more consistent code — and take home practical patterns you can use immediately.