Wikipedia:Deferred changes/Implementation

Editing of a page where a revision was recently actively deferred due to it being tagged as a redirect to a nonexistent page from mediawiki core.

The page details the proposed technical implementation of deferred changes.

A hook is added to the updateTags function of the ChangeTags class in core, and FlaggedRevs checks the added tags. If any of the added tags is meant to indicate a problem, flagged revisions is enabled on the page and the latest edit prior to the latest user is marked as reviewed. The page appears at Special:ProblemChanges and the edits can be reviewed. If one of the tag is listed as needing 'active' deferral (at MediaWiki:Flaggedrevs-tags-list-defer-active), then the stable version is displayed to readers by default and the page is listed at Special:PendingChanges along with edits to pending changes protected pages.

A deferred page is recorded in the database with a "defer" level, and whenever an edit to a page with "defer" level is reviewed, the config is reset. So this implements the "defer until reviewed" concept. No change in the db schema is needed. By relying on the already well integrated change tag functionality, this can be easily used from a variety of sources. All AbuseFilter tags are considered to indicate a problem for example, so will always prompt a passive deferral. Problem tags can be selectively prevented from triggering a deferral if listed in MediaWiki:Flaggedrevs-tags-list-defer-exempt.

A rough FlaggedRevs patch is available at https://gerrit.wikimedia.org/r/#/c/218104/. This requires unmerged commits to mediawiki core, available as a single commit at https://gerrit.wikimedia.org/r/#/c/218104/. An abusefilter patch is available at https://gerrit.wikimedia.org/r/#/c/218106/.