And there is another XEP for this - invisibility, perhaps these are compatible with each other and could implemented together: http://xmpp.org/extensions/xep-0126.html

And there is another XEP for this - invisibility, perhaps these are compatible with each other and could implemented together: http://xmpp.org/extensions/xep-0126.html

I checked and XEP-0126 Invisibility is only use case of privacy list to get invisibility. Privacy lists are supported by Tigase so XEP-0126 should work.

XEP-0018 is totally different from XEP-0126. It requires changes in presence processing and is NOT compatible with XMPP Core and XMPP IM specification.

OK, I agree XEP-0018 is not a good idea actually. XEP-0126 is supported through privacy lists but for just invisibility it is an overkill as privacy lists come at the performance cost. So using them only, just to have invisibility is not feasible.

Is there any other option, a simple XEP for invisibility?

We could implement support for XEP-0186 Invisible Command which should be easy to implement and there should not be any unnecessary overhead due to this extension.

Ok,this makes sense, let's do the XEP-0186 Invisible Command instead.

Implemented support for XEP-0186