watchlist sometimes shows 2 entries for 1 page when multiple revdeletes are involved
Open, MediumPublicBUG REPORT
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	Novem_Linguae
	Sep 30 2025, 6:02 AM

Description

Steps to replicate the issue (include links if applicable):

on enwiki, watchlist the page "User talk:Larry Sanger/Nine Theses" today or within the next couple days, before it falls off the watchlist or the recentchanges table
visit https://en.wikipedia.org/w/index.php?hidemyself=1&hidebots=1&hidecategorization=1&hideWikibase=1&limit=1000&days=30&enhanced=1&title=Special%3AWatchlist&urlversion=2&safemode=1&skin=vector
active filters = page edits. remove all other filters
tick "group results by page"

What happens?:

two entries for the same page

What should have happened instead?:

one entry for the same page

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):

still happens with ?safemode=1
happens on multiple skins (tested vector 2010 and timeless)
later I tried visiting the page, which sets all revisions to read. bug still happens
using WikimediaDebug, I did verbose logging. here's some of the log results. I think one is the main request and one is an API query (hopefully).
- https://logstash.wikimedia.org/app/dashboards#/view/x-debug?_g=h@d0ff167&_a=h@e2fe496 <- 6826 events. main request?
- https://logstash.wikimedia.org/app/dashboards#/view/x-debug?_g=h@d0ff167&_a=h@563a035 <- 118 events. API query?
i took one of the SQL queries from logstash (the 4 second one) and plugged it into stat1008. it returned individual rows for everything. makes me wonder if "Group results by page" is done in PHP somewhere rather than in SQL. if so, then the bug is probably in PHP and not SQL

Details

Related Changes in Gerrit:

	Subject	Repo	Branch	Lines +/-
	Fix visual regression from CVE-2025-61646	mediawiki/core	master	+10 -27

Customize query in gerrit

Event Timeline

Novem_Linguae created this task.Sep 30 2025, 6:02 AM

Restricted Application added a project: Moderator-Tools-Team. · View Herald TranscriptSep 30 2025, 6:02 AM

Restricted Application added a subscriber: Aklapper. · View Herald Transcript

Maintenance_bot added a project: MW-Interfaces-Team.Sep 30 2025, 6:31 AM

I noticed an oddity in EnchangedChangesList in recentChangesBlockGroup():

foreach ( $block as $rcObj ) {
			// If all log actions to this page were hidden, then don't
			// give the name of the affected page for this block!
			if ( !static::isDeleted( $rcObj, LogPage::DELETED_ACTION ) ) {
				$namehidden = false;
			}

I don't see if checking that rc_source is actually a log entry. Anyway, it doesn't seem related though.

I can reproduce this on enwiki, but not locally. From the code, the grouping only depends on $rc->getTitle() and rc_timestamp. It's as if makeCacheGroupingKey() returned the wrong string. It's only used for grouping the RC entries and not for the actual title displayed in the links. I can't see how that could happen though.

aaron triaged this task as Medium priority.Oct 1 2025, 3:55 AM

aaron moved this task from Incoming (Needs Triage) to Bugs & Chores on the MW-Interfaces-Team board.

@Novem_Linguae thanks for filing this; we recently addressed a CVE and this is emergent behavior related to that change. We'll get on it!

Thanks. Feel free to add me to the CVE ticket.

Novem_Linguae added a project: Regression.Oct 2 2025, 3:56 AM

MBH subscribed.Oct 4 2025, 12:47 AM

Scardenasmolinar moved this task from To be estimated to Kanban on the Moderator-Tools-Team board.Tue, Oct 14, 4:19 PM

Scardenasmolinar edited projects, added Moderator-Tools-Team (Kanban); removed Moderator-Tools-Team.

Scardenasmolinar moved this task from Ready to Ready (Maintenance) on the Moderator-Tools-Team (Kanban) board.Tue, Oct 14, 4:23 PM

jsn.sherman assigned this task to Dillon.Tue, Oct 14, 4:25 PM

Dillon moved this task from Ready (Maintenance) to In Progress on the Moderator-Tools-Team (Kanban) board.Thu, Oct 23, 3:36 PM

Change #1198596 had a related patch set uploaded (by Dillon; author: Dillon):

[mediawiki/core@master] Fix visual regression from CVE-2025-61646

https://gerrit.wikimedia.org/r/1198596

gerritbot added a project: Patch-For-Review.Fri, Oct 24, 8:00 PM

Dillon moved this task from In Progress to Eng review on the Moderator-Tools-Team (Kanban) board.Fri, Oct 24, 10:13 PM

Test wiki created on Patch demo by KGraessle-WMF using patch(es) linked to this task:
https://a187cc27c1.catalyst.wmcloud.org/w/

Samwalton9-WMF added a project: Essential-Work.Wed, Nov 5, 1:38 PM

watchlist sometimes shows 2 entries for 1 page when multiple revdeletes are involvedOpen, MediumPublicBUG REPORTActions

Description

Details

Event Timeline

watchlist sometimes shows 2 entries for 1 page when multiple revdeletes are involved
Open, MediumPublicBUG REPORT
Actions