Language team has decided to reduce the scope of webfonts feature in ULS. As part of this plan, tofu detection and applying autonym font and other fonts (irrespective of user preference) has to stop and we should deliver fonts only based on user preference.
Please formulate this task in a way that doesn't overlap T135464. My comment focuses on the question: when to apply a webfont corresponding to the current wiki's language?
we should deliver fonts only based on user preference
What do you mean exactly? There are two possible interpretations, which are radically different:
- always default to system font, trust that users with problems will find how to apply the webfont;
- apply the webfont by default in the cases described by https://www.mediawiki.org/wiki/Universal_Language_Selector/FAQ#How_do_you_decide_a_default_font_for_a_language_or_script.3F , trust that bandwidth will not be a problem.
By user preference I mean - the explicit user preference(users choose a font using Display settings panel of ULS) and implicit user preference(for some languages there is a default font)