While Wikimedia Foundation projects requesting prioritization and resources should have their concepts publicly available (T118231), and while drafting concepts publicly should be the default recommendation, there might be situations where starting to work on a concept privately will bring some advantages.
In this task we aim to define when private drafting is useful and what are the criteria that would define the appropriate time to go public.
https://www.mediawiki.org/wiki/User:Keegan_(WMF)/PDP/Private_planning