Final round is sometimes not shown in STV election results
Closed, InvalidPublicBUG REPORT
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Authored By

	dom_walden
	Jun 26 2025, 2:06 PM

Description

What is the problem?

Further to our work on T291821. In some STV elections, we appear to be electing candidates even though they have not reached the quota. This is because we are missing a final round where the quota is recalculated and the remaining candidate(s) exceed it.

Steps to reproduce

After the change is made we should expect to be able to re-tally the above elections and see the final round.

Environment

Wiki(s): https://vote.wikimedia.beta.wmflabs.org SecurePoll 3.0.0 (9ca747c) 07:26, 26 June 2025.

Screenshots

before:

Screen Shot 2025-05-21 at 09.39.51.png (868×710 px, 100 KB)

after: (notice how candidate A is declared elected on 509 votes despite the quota being 669)

Screen Shot 2025-05-21 at 09.40.02.png (541×690 px, 59 KB)

Details

Related Changes in Gerrit:

	Subject	Repo	Branch	Lines +/-
	WIP: Show elected and eliminated candidates in final round	mediawiki/extensions/SecurePoll	master	+34 -30

Customize query in gerrit

Related Objects

Mentioned In: T291821: SecurePoll: Once a candidate is declared elected, make sure they remain elected [M]
Mentioned Here: rESPO9ca747cd6018: Localisation updates from https://translatewiki.net.
T291821: SecurePoll: Once a candidate is declared elected, make sure they remain elected [M]

Event Timeline

dom_walden created this task.Jun 26 2025, 2:06 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptJun 26 2025, 2:06 PM

Amdrel changed the task status from Open to In Progress.Jun 26 2025, 6:08 PM

Amdrel claimed this task.

It looks like this bug was introduced when we added short circuit logic at the beginning of the round that checks if all remaining hopefuls are eligible to be elected or eliminated with the current remaining seat count. This change was introduced to workaround the infinite loop bug if I recall correctly (http://phabricator.wikimedia.org/T291821). If I move that logic to the end of the round (and update the local round object) instead then we get an elected message as well. There is the problem though that the quota doesn't align with the new elected winner, which looks suspect. Is this fine? If not, would it be fine if we also added a note that says, "Candidate 'A' elected to fill remaining seats"? The same could also apply where we eliminate remaining hopefuls once we reach the seat limit.

Screenshot 2025-06-26 at 1.54.22 PM.png (1×1 px, 193 KB)

Novem_Linguae attached a referenced file: F60339073: Screen Shot 2025-05-21 at 09.40.02.png. (Show Details)Jun 26 2025, 9:06 PM

Novem_Linguae attached a referenced file: F60339068: Screen Shot 2025-05-21 at 09.39.51.png. (Show Details)

Change #1164309 had a related patch set uploaded (by Amdrel; author: Amdrel):

[mediawiki/extensions/SecurePoll@master] WIP: Show elected and eliminated candidates in final round

https://gerrit.wikimedia.org/r/1164309

gerritbot added a project: Patch-For-Review.Jun 26 2025, 9:09 PM

Amdrel moved this task from Backlog to Actively working on the MediaWiki-extensions-SecurePoll board.Jun 26 2025, 9:43 PM

dom_walden mentioned this in T291821: SecurePoll: Once a candidate is declared elected, make sure they remain elected [M].Jun 27 2025, 9:15 AM

Change #1164309 abandoned by STran:

[mediawiki/extensions/SecurePoll@master] WIP: Show elected and eliminated candidates in final round

Reason:

implementation this modifies was reverted