Three things make an app
An installable site needs a manifest that names it, a service worker that keeps pages on the device, and a page to show when a page is not there. In loam nobody builds or maintains them — the engine derives all three from what the site already says about itself.
Made from what the site says
/manifest.json comes from the organisation's name, the site icon and the theme colours. Change the name or the icon on the site and the app follows. The manifest and the worker have no theme layer: one wrong line in either breaks the install on every device, so they are the engine's. What a site shapes is the data they are made from.
What the device keeps
/sw.js keeps what a visitor opened and, once a day, walks the sitemap to keep the rest — the sitemap is already the list of what exists, so there is nothing to maintain here either. Pages come from the network first and fall back to the copy; versioned assets stay until they change; forms are never touched. With a connection, the live page always wins.
Offline and install pages
/offline renders when everything else is gone; /install explains per browser how to add the site to a home screen. A theme can take over either page with a file of the same name. The site pushes no install prompt — the browser knows when someone returns often enough to want one.
For the visitor
Installing is a property of the device: no account, nothing about the person sent anywhere, undone by removing the icon. A site on the home screen that opens without a loading bar and works in a tunnel — without a store, a review, a second codebase or an update cycle. For the owner it is one less thing that exists.