User:Tisane/Wikilinks implementing detection and indication of page existence on a remote wiki

It is proposed that a Mediawiki extension be developed to, whenever a page is displayed that has wikilinks:
 * Refer to a local list of names of all pages that exist on a specific remote wiki (i.e. Wikipedia) and:
 * Turn links red if the page exists on neither the local nor the remote wiki;
 * Turn links blue if the page exists on the local wiki but not the remote wiki; and
 * Turn links green if the page exists on the remote  wiki.

If you click on a red link, it prompts you to create a new page on the local wiki. If you click on a blue link, it takes you to the page on the local wiki. If you click on a green link, it takes you to the page on the remote wiki. The syntax will need to allow for an override of the normal behavior that gives the remote wiki article precedence if a page exists on both the local wiki and the remote wiki. I was thinking that a "local:" prefix or a tag or something might suffice.

Ideally, a centralized list (stored as a mySQL database) should be generated and kept current on one website (with mirrors in case it fails). All of the other wikis should obtain their initial page list and differential updates from that  website, rather than from Wikipedia, so that Wikipedia doesn't have to  be the object of constant querying. The centralized list of pages that exist on Wikipedia will be generated by a script collecting all the page names from AllPages, 500 pages at a time (or 5,000 at a time, if bot access is obtained), using the API. The list will be created and updated using NewPages and the deletion log.

The reason for this change is to help sites like Libertarian Wiki, which have a lot of articles (e.g. anarcho-capitalism) that really don't need to exist as (usually outdated) content forks on the local wiki. It would be better if they just linked to Wikipedia. But, the problem with interwiki links as we know them today is that they have no existence detection. This proposal seeks to solve that.