This type of feature that was implemented a few months ago by Signal has an important ephemerality value: it does not depend on the message exclusion timer locally.
There are specific use cases for this feature, for example:
User “A” wants to send a sensitive photo to “B”, but instead of having the manual (and bureaucratic) work of going to the settings and setting a time for the local deletion of the message, he can choose to delete the message as soon as it is viewed from the “B” side.
Technically, it is more of an interface implementation, as the file data will be locally, but will no longer be visible in the chat. Therefore, it is a way to address sensitive content being exchanged in the chat.
At the risk of zombie-posting; I’m surprised this feature request did not receive more of a response. Of course, this is not a hard security feature, since it requires cooperation of the receiving device, but often, users do not mistrust their chat partners to such a degree, but just want to indicate “you may only see this photo once”.
I assume this could be implemented to a degree using webxdc apps, but I believe this would lead to awkward UX and less trust in the feature.
As such I would love for view-once photos to be added as a feature. Preferrably with an option to protect view-once photos from being screen-captured, just as there currently is an option to prevent the whole app from being captured
