As we cannot use CSS container queries in RSS/Atom feeds, we need to use inline styles. But we need to then choose what version of the layout we serve to the user. One might read the RSS on mobile, and would prefer a once-column view, another might prefer a desktop view.

This task is about adding an ability to define separate RSS/ATOM feeds with the same content, but different inline styles applied.

In application config (https://hub.sealcode.org/diffusion/PLAY/browse/master/src/back/app.ts$55) you could add an rss_variants key that takes an array of modifiers, some of those might be exclusive to each other. The first one of the exclusive pair is the default one:

[["light", "dark"], ["mobile", "desktop"]]

The above would create four variants of the RSS: light+mobile, light+desktop, dark+mobile, dark+desktop.

The variant is passed as a query param to the RSS feed URL and taken into consideration when generating the inline styles for the HTML of each entry.