app/ contains the browser code that gets bundled into app.[hash].js. It's got all the logic, crypto, and UI. All of it gets used in the browser, and some of it by the server for server side rendering.

The main entrypoint for the browser is main.js and on the server routes.js is imported by /server/routes/pages.js

• pages contains display logic an markup for pages
• routes contains route definitions and logic
• templates contains ui elements smaller than pages