Manual:$wgWatchersMaxAge

Recent changes, new pages, watchlist and history: $wgWatchersMaxAge
Page watchers inactive for more than this many seconds are considered inactive. Used mainly by action=info .
Introduced in version:1.26.0 (Gerrit change 193838; git #I10d294a)
Removed in version:Still in use
Allowed values:(positive integer)
Default value:30 * 24 * 3600 (30 days = about one month) (1.41+)
180 * 24 * 3600 (180 days = about six months) (1.26-1.41)

Details

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Counts the number of active watchers of the page that are displayed in action=info and the visitingwatchers field of the info API if $wgShowUpdatedMarker is enabled. Per "active watcher" it counts watchers that have visited that page since the last edit or that have visited the page at least $wgWatchersMaxAge before last edit (as tracked by the wl_notificationtimestamp field).

If the viewer does not have the unwatchedpages user right and either the number of active watchers is not above $wgUnwatchedPageSecret or the number of total watchers is not above $wgUnwatchedPageThreshold , only approximate information is shown.