Export Nextcloud public API to your application
In your application directory:
composer require --dev altahrim/nextcloud-psalm-plugin
vendor/bin/psalm --init
vendor/bin/psalm-plugin enable altahrim/nextcloud-psalm-plugin
Force specific Nextcloud version:
<pluginClass class="Psalm\NextcloudPsalmPlugin\PluginEntry">
<nextcloudVersion>28</nextcloudVersion>
</pluginClass>
Otherwise, version is detected from appinfo/info.xml