NOTE: Please see T357580 for any actions your community may need to take as part of this change
As part of the splitting of the Vector skins (T291098), here was a product requirement to minimize impact on communities.
To fulfil this the new modern Vector skin:
* loads both MediaWiki:Vector.(css,js) and MediaWiki:Vector-2022.(css,js)
* loads both User:<username>/vector.(css,js) and User:<username>/vector-2022.(css,js)
At some point, when we're ready we'll want to change this behaviour using the following plan:
# Plan
[x] A configuration flag will be added to Vector to disable the site styles/scripts behaviour. Communities can request to disable it, when they are ready. When enabled Vector 2022 will not load either JS or CSS. This is a good opportunity for communities to do some housekeeping, e.g. moving styles to TemplateStyles and scripts to gadgets.
[x] A #user-notice will be sent out to communities. Users using modern Vector will be instructed to delete/blank their user vector.(js|css) in preparation for the change.
[x] We will drop support for new wikis going forward. When wikis switch skins from legacy Vector to Vector 2022 users will need to copy any relevant code from vector.js and vector.css to vector-2022.js and vector-2022.css. Site admins will need to copy important code from MedaWiki:Vector.css/js to MediaWiki:Vector-2022.css/js
[x] We will drop support for Wikibooks and Wikivoyage
[] We will drop support for Wikiversity and Wikiquotes
[] We will drop support for Wiktionary and Wikinews
[] We will drop support for Wikipedias
[] We'll remove the Vector user module behaviour when we feel like sufficient time has elapsed sending another user notice to notify users that during the week if they've not done anything and they are using the Vector 2022 skin their user style/scripts will stop working.