Make certain (closed) tickets only accessible to agents? Hide from users?

We currently use Zammad web UI only internally, i.e. customers can only access it via email.
Next year we want to open the web UI to our customers, but we want a “fresh start” for them, i.e. they must not be able to see the old tickets. Is it possible to hide specific tickets from non-agent users, even if they are the customer of the ticket?

Zammad does allow you to set articles in question to “internal” - however, if you set everything to internal the ticket will still be shown and accessible to the customer:

So no, Zammad doesn’t allow you to hide tickets.
You could workaround it in overviews by using a date clause - however, if your customer uses the quick search of Zammad he will still find older tickets.