Hi @Tangy,
Thank you for your patience! I know there is currently no direct way to get the ‘current user’s username’ in a program rule; however, if it works with you that the social worker will select their username each time they register a new client then the suggestion by @plinnegan in another similar post might help with creating a program rule for your use case:
If not then perhaps you or @elmoujarrade could create a feature request and add your votes, share it with the community so that others will be able to watch/vote too! Please let me know if you need assistance creating the feature request on jira.dhis2.org
Also, please note that the value type username is not fully supported in android yet: docs.dhis2.org android-app value-types: Username
Thanks!