We obsess — rightly — over bundle size, performance, code coverage, and anything else we can quantify. But what if I told you that the number one predictor of a project's sustainability is the one thing we're *not* measuring? In this talk, we'll take a look at what the academic literature can tell us about writing maintainable, bug-free code, and see how a new generation of compiler-frameworks like Svelte can apply those lessons to help us build rich, reliable applications.