One fullstack .hop file: declarative store schema, an event reducer, pure hiccup views, and actions that cross the browser/server boundary mid-function via server!() and cast. Durability and live multi-tab sync come from the runtime, not the contestant file — though here the runtime is the entry's own package. Passing the suite required real runtime work: dom.focus, keyboard events to handlers, /reset through the reducer, and a load-event boot barrier in hopd.