What do you do when your codebase gets too big? Ember is perfect for “ambitious applications”. But what about really ambitious applications? Apps with hundreds of thousands of lines of code, teams that span countries, and users all over the world? Or apps in high liability environments where regressions from upgrades could cost millions of dollars or even put people in danger? Recent advances in two tools present an opportunity to structure a project that is easy to work in and upgrade, but without the pain points of past solutions. Those tools are Ember Engines, and Yarn workspaces.