It is affecting this page, from Vietnamese on: https://en.wiktionary.org/wiki/o

Thanks very much! Things seem to be working fine again now.

This mechanism has stopped working. See the comment I added to https://phabricator.wikimedia.org/T153900.

Even though things were working well a month ago, the mechanism seems to have stopped working properly. Even though we still have in InitialiseSettings.php:

'wgInterwikiSortingSortPrepend' => [ ...
  'gdwiki' => [ 'ga', 'gv', 'sco', 'cy' ]

gdwiki users are no longer seeing links to ga (Gaeilge) and gv (Gaelg) at the top of the Compact Language Links, but only links to sco (Scots) and cy (Cymraeg), followed by the usual random looking rubbish. I have checked with other gdwiki users and they seem to be seeing the same, regardless of whether they are logged in or logged out. I checked the Norwegian wikis nowiki and nnwiki, and the mechanism seems to be broken for them too. InitialiseSettings.php has:

'wgInterwikiSortingSortPrepend' => [ ...
   'nnwiki' => [ 'no', 'sv', 'da' ],
   'nowiki' => [ 'nn', 'da', 'sv', 'fo', 'is' ],

so the Norwegian Bokmål wiki (no) should crosslink top of the list to the Norwegian Nynorsk wiki (nn) and vice-versa, but this is not now happening at all.

Thanks very much for this. It seems to be working well on gdwiki, and has been received with favourable comment.

Thanks. We discussed it thoroughly and were all agreed on ga,gv,sco,cy, so it is very unlikely that the list will change before 3 January. If after four months we wish for a change in the light of experience, we'll put in a separate request.

Very good. Thanks.

Thanks. I understand better now.

Thanks for the advice!

Thanks for this! I guess now we should have a discussion over on gdwiki, and then submit a request for 'sortPrepend' => [ 'ga' ] or [ 'ga', 'gv' ] or whatever we agree? I am still a bit confused, though, because I had a look at pdcwiki and pflwiki and the languages appearing at the top of the compact language list seemed to be more influenced by 'wgImportSources' than by 'sortPrepend'.

sortPrepend seems ready made for the task. Some wiki communities have already decided what is important for them (https://noc.wikimedia.org/conf/highlight.php?file=InitialiseSettings.php), and it otherwise would become redundant when compact interwiki lists are introduced.

Scottish Gaelic and Irish Gaelic are not so close that Scottish Gaelic speakers are likely to be immediately aware of the possibility of trying the Irish Gaelic wikipedia. Lots of users of the Scottish Gaelic wikipedia will not even be aware that the Irish Gaelic wikipedia exists, that it has a lot of articles on topics likely to be of interest to Scottish Gaelic speakers (and vice-versa), and that with a bit of effort it can be understood - especially with a bit of help from tools such as www.intergaelic.com which are starting to appear. Some languages are so close together that there is a very very high level of mutual understanding: written Norwegian (nb) and written Danish (da) for example, but Scottish Gaelic and Irish Gaelic are not that close, and Manx Gaelic is harder to understand because of the different spelling system.

sortPrepend certainly sounds like the most promising facility mentioned so far. We could use it (after discussion and consensus) to put Irish Gaelic (ga) at the top of the Interwiki links on the Scottish Gaelic (gd) wikipedia. I see now from https://noc.wikimedia.org/conf/highlight.php?file=InitialiseSettings.php that various wikis are already using this facility..

For the Scottish Gaelic (gd) wiki, Irish Gaelic (ga) should certainly be top of the interlanguage list, probably followed by Manx Gaelic (gv). And vice-versa, for the Irish Gaelic wiki, Scottish Gaelic should be top of the Interlanguage list. What should we do to get this implemented? - Start a formal discussion and vote on the wiki, and then put in a formal request once we have consensus?

Everything looks fine. A huge improvement.