Internally released data that estimates the number of Unique Devices hitting each of our domains, using the Last Access cookie. This is a major release, and it's available in the wmf database in hive, in the last_access_uniques_daily table.
Fixed handling of uri-encoded page titles in the pageview API
External Store - In progress. Will soon enable External Store on Beta Cluster as a pre-requisite for this. If you want to look/give feedback on the Beta change, see https://phabricator.wikimedia.org/T95871
Waiting on Design Research availability for user testing of Single Edit Tab integration
Updates:
Single Edit Tab went to Hungarian Wikipedia yesterday; now waiting on user feedback.
Some improvements to OOUI; note the breaking change for wmf.15+ (no known issues in gerrit master code).
Last week we said we'd update on assessing the performance impact of OOUI on all read pages; this is not firm yet, but appears to be a trivial additional cost.
Check your ResourceLoaderModule subclasses and your 'ResourceLoaderGetConfigVars' hook functions to make sure you're not using $wgUser or $wgLang (or their equivalents via RequestContext). You'll generally want to use the user and language from the ResourceLoaderContext or use the 'MakeGlobalVariablesScript' hook instead. Remember that Message objects will use $wgLang by default.
Check your parser hooks to make sure you're using $parserOptions->getUser() or $parser->getTargetLanguage() instead of $wgUser or $wgLang (or their equivalents via RequestContext), respectively. Otherwise you're liable to blow things up if your hook gets used in a message somewhere.
Timo says he'll send an announcement of some sort once details are settled.