How to configure static IPv6 with luci

Is there a way to use the web interface to configure a static IP address? I see the default ULA IP in the interface overview. If I remove the prefix from Global options, it disappears from the interface on the overview. Fair enough.
But there is no obvious way to add an IPv6 address. I can add another IPv4 address easily enough.
If I edit /etc/config/network I can add an IPv6 address to the interface, and then it's editable in Luci. Am I missing something here?