Notes for potentially moving some mediawiki system messages into wikimediamessages

Problem: We currently have hundreds of local variants of some important tool-links. Each of these have to be individually created, translated, and then maintained. E.g. A single message has 18 translations at mediawikiwiki, and 5 translations at metawiki alone. This creates many gaps or problems, across most Wikimedia wikis.

Goal: To minimize translation requirements and maintenance efforts, and to get the links to the best tools into the hands of all editors in all Wikimedia wikis. E.g. To get things like "pageviews" tool and "centralauth" links, more clearly into a place where editors/readers can find them, especially at smaller wikis, in all interface-languages at each wiki.

Solution?: We think we should be putting all the best tool links into Extension:WikimediaMessages, translating them at translatewiki, and encouraging standardization. But perhaps there are other better options to consider, in the short-term or in the longer-term?

Scope
There are only a few specific messages, but they're duplicated en-masse.

E.g.
 * mw:MediaWiki:Sp-contributions-footer
 * c:MediaWiki:Sp-contributions-footer
 * d:MediaWiki:Sp-contributions-footer
 * m:MediaWiki:Sp-contributions-footer
 * en:MediaWiki:Sp-contributions-footer
 * ur:MediaWiki:Sp-contributions-footer
 * etc, at all ~900 wikis (except the ones where they're missing completely)

Likely messages to look at:
 * MediaWiki:Sp-contributions-footer
 * MediaWiki:Sp-contributions-footer-anon
 * MediaWiki:Histlegend
 * MediaWiki:Pageinfo-footer
 * MediaWiki:Recentchangestext
 * w:MediaWiki:Linkshere

Problem details
The individual sections/links at various wikis are frequently:
 * broken/outdated
 * missing
 * in an inconsistent order
 * in an inconsistent location
 * using inconsistent labels
 * in a language we can't read.


 * Examples:
 * Inconsistent labels
 * E.g. "accounts (SUL)" vs "CentralAuth" vs "accounts" vs "SUL" vs "Global Account"
 * Inconsistent order
 * E.g. "1 2 3 4" vs "3 1 4 2"
 * Inconsistent location or inconsistent page.
 * E.g. Some wikis put useful links in the "Page information" (e.g.) via m:MediaWiki:Pageinfo-footer vs others put them in the "History" page (e.g.) via m:MediaWiki:Histlegend
 * Outdated or missing local translations (and mass-duplication problem if they do exist)
 * E.g. try looking at this usercontribs page with language set to Dutch versus language set to French
 * E.g. all these footer links are broken example link due to

Detailed notes about specific MediaWiki: messages

 * /Sp-contributions-footer
 * /Histlegend and Pageinfo-footer
 * User:Trizek (WMF)/New filters for Recent Changes/Recentchangestext

Rough plan ideas
At minimum, it would be good to have the research and recommendations. At best, we can fix all the things everywhere!

Suggested actions:
 * 1) Compile even more details on what the average setup is
 * 2) Investigate what the possible options are (pros/cons to each)
 * 3) Get community input/feedback
 * 4) Iterate some recommendations
 * 5) Make a formal recommendation for a standard Wikimedia-message set
 * 6) Update the default and propagate it.
 * 7) help the smaller wikis to update themselves (i.e. recommend deleting any local overrides)
 * 8) gently encourage the large wikis to update, either by using the new default, or by adjusting their local overrides to be closer matches

Possible technical solutions

 * Extension:WikimediaMessages (likely the best option?)
 * Global Templates (possible alternative? but more complicated in many ways, technically and socially)
 * Requests for comment/Shadow namespaces
 * Wikimedia Developer Summit/2017/Cross-wiki templates, translatable, reusable, manageable

See also, previous attempt at describing this in T67446