Preferrably, we should work on styling issues in CSS/LESS first (see T265180) before this task.

I haven't written a sniff for PHPCS but would be interested in contributing anyways, but I'm fine if someone else would want to take over (since I am also a bit busy).

CosmosProfile repository was created by Chris on October 9th (2 days ago) in https://www.mediawiki.org/w/index.php?diff=4161443

Halfway done, now needs migration to MediaWiki\Skin\Cosmos namespace

While we're at this, I'm currently wondering if CosmosNavigation::parseItem() and CosmosToolbar::parseItem() can be removed safely.
T hey don't seem to be used within the Cosmos source code according to Codesearch https://codesearch.wmcloud.org/skins/?q=parseItem&i=nope&files=&repos=Skin:Cosmos

Except MediaWiki.Commenting.FunctionAnnotations.UnrecognizedAnnotation, which can be auto-fixed

• the Generic.Files.LineLength.TooLong will need to be manually fixed, same with the MediaWiki.Commenting.* sniffs
• the SpaceyParenthesis sniffs can be auto-fixed but needs careful review since it will end up fixing at least ~2600+ detected errors
• the rest of the Squiz sniffs are auto-fixable, and can maybe be all done in one patch (depends how many fixes there are, if it's like the SpaceyParenthesis sniffs, then it will need to be split up)
• MediaWiki.ControlStructures.AssignmentInControlStructures.AssignmentInControlStructures needs manually fixing
• MediaWiki.NamingConventions.LowerCamelFunctionsName.FunctionName needs manually fixing

All methods under CosmosSocialProfile had an undeclared visibility, and is fixed in https://gerrit.wikimedia.org/r/c/mediawiki/skins/Cosmos/+/633317.

This should be looked at once PHPCS styling issues are done (T265108) and re-namespacing is done (T265107).

In a follow-up task, we should convert to AutoloadNamespaces as well.

CI issue is fixed. Follow-up patches will be made in the future for consolidating media queries and such.

Thank you Hashar for your explanation (it makes sense), and for the updated patch in integration/config! I don't believe anything else is action-able left in this task, so I'll mark this as resolved.

@MtMNC: Thank you for your recent work on the Refreshed skin with v4 and getting that out of beta, it’s really great work. I don’t really do any MediaWiki-related work anymore, but I appreciate the efforts to update the docs too. Feel free to close this ticket; I’m sure I had more ideas about why I created this ticket, but that was a long time ago.