The router

Why the storage defaults and the theme are what they are. The contract — the signature, the errors, the routes and the one-process-one-policy rule — is in router.md.

Why both TTLs default to one hour

Both default to one hour because what the library manages on its own is meant to be ephemeral: an upload nobody claimed and a download link nobody kept. And they are two settings, not one, so a space can hold its uploads for a week and still hand out downloads that live an hour.

Why the theme is pure CSS

The attribute goes in the initial markup; JavaScript does not add it after load, so the theme is resolved before the first paint and there is no flicker in any of the three cases: system is resolved by widgets.css with prefers-color-scheme, in pure CSS, and the other two arrive already decided.

A WebFunction carries no theme of its own, because it compiles its HTML once, without knowing which router it will end up in. That is why the theme belongs to the space and two themes need two routers.

Today the theme is set by whoever mounts the space. Letting the user choose it, and remembering that choice, will come in a future version: that is why there is no visible selector yet, no localStorage, no cookies, and no theme-switching JavaScript.