Watchlist wishlist

Watchlist wishlist
 * Per Requesting a user-centred rethink of how watchlists work

Objective and rationale

 * To write: What are watchlists meant to achieve? How are they meant to be used? How does this vary by type of user?

Top-level plan

 * To write: What are the major ways in which the nature of watchlists should shift and change, and why (with reference to the above)?

Specific changes

 * To write: For each proposed change, does it have a brief description, link to a page or bug describing how it would work, a quick evaluation of their technical complexity and dependencies, and a justification for its relative priority (given the top-level plan)?

Overview
The main requests identified so far are
 * cross-wiki watchlists (supporting interwiki collaboration)
 * public or shared watchlists (supporting intrawiki collaboration)
 * improved management of the watchlist (adding, removing, searching, processing - supporting efficiency of watchlist system)
 * including grouping or tagging items
 * including adding items temporarily (with temporarily watched items automatically removed after specific time or event)
 * including adding/removing categories (handling of additions/removals from category, not just edits to category page)
 * including automatically adding/removing subpages of a watched page
 * including watching a user's contributions
 * including annotating individual watchlist items

Bug list
List of major watchlist-related feature requests
 * Ability to watch lists of pages, e.g. all sub-pages of a page
 * Improve selection of items on [[Special:Watchlist/edit (invert selection of/(un)select all/select redirects/select inexistent pages)]]
 * Modernize watchlist editor (EditWatchlist) for AJAXy interactivity
 * On Special:Watchlist, allow to hide non-bolded ("unread") entries
 * Wildcard or Regex support for Watchlists
 * Cross-wiki watchlists
 * Special:Watchlist should show other languages (provide quick links to Watchlist on other projects)
 * Common watchlists (shared/public)
 * Public and private watchlists, shared watchlists
 * Review and deploy CollaborativeWatchlist extension
 * clearing one's watchlist CLOSED, RESOLVED
 * Special:Watchlist enhancement - allow return of removed items to list
 * Watchlist doesn't show earlier normal edits when hiding bot edits, own edits or minor edits
 * Watch edits which add or remove pages from a category
 * Ability to watch all articles in a category
 * Watch pages for a few days only (add an expiry time)
 * Group similar pages in watchlist (aka multiple watchlists)
 * Watchlist "Grouping"
 * Related notes at Extension:WatchGroup
 * Add comments field to watchlist items
 * Auto-refresh on watchlist
 * Obtain a list of edits to watched pages since last visit
 * Distinguish links to redirect pages on Special:Watchlist CLOSED, DECLINED
 * Special:Watchlist should link to nonredirected pages CLOSED, RESOLVED
 * Ability to watch section levels of pages
 * Remind me of this article in X days
 * Provide a 'user-watchlist' that lists all recent contributions of a set of users -(Extension:UsersWatchlist)
 * Add a direct unwatch link to entries on Special:Watchlist
 * Set "Add pages I edit to my watchlist" and "Add pages I create to my watchlist" to true by default on Wikimedia wikis (only for new users)
 * Set "E-mail me when a page or file on my watchlist is changed" (enotifwatchlistpages) to true by default for new users