Where are .po translations supposed to go? I have .po file with translation and I have it in modulename/translation/xy.po

When I installed profile in XY language the file was not loaded.
I did a little digging and found that \FileTranslation::getTranslationFilesPattern looks for drupal-8.xy.po pattern so I renamed the file, reinstalled my profile but the language still was not picked up. The interface translation was downloaded just fine though. If I manually import the file it works. So it looks to me like the directory for translations has changed maybe?



I have checked the installer and it looks like Drupal only looks into the site's files/translations directory. So how are modules supposed to ship with translations?



So it looks like the translations ARE being imported just fine(entries are present in the locales_source table), but for some reason not everything is displayed translated.



Ok, so I came to a conclusion that my translation file is not imported at all. The reason for incomplete translation is because it comes from downloaded Drupal localization and not my file. I am looking at installer and there is nothing that would suggest po files discovery mechanism in any way, only the drupal core(or any po file) in the files/translations directory(which is where the drupal translation is downloaded into).
Be sure the directory sites/default is writable, so that during installation the translation files can be copied to the translations directory at sites/default/files/translations