Use Current Attributes for: Current.locale

[veganstraightedge]

Now that we use the current person's locale all over the place, it'd be nice to standardize how we do it. And do it in a unified place

This feels like a place where we should use CurrentAttributes (added in Rails 5.2).

They're thread locale globals.
https://api.rubyonrails.org/classes/ActiveSupport/CurrentAttributes.html

It would be swell if we could get/set Current.locale from anywhere in the app.