Sharing a topic using FB messenger works fine. I think only custom home page causes such problem. I've not tried categories page yet.

I modified html link on my custom home page. from <a href="/app/">App</a> to <a href="javascript:window.location.href=window.location.href + 'app/'">App</a> Pros: no change to NodeBB source, so that I can update NodeBB as new release comes. Cons: The link URL is ugly and can not be copied for quote. Ref: Difference between window.location.href=window.location.href and window.location.reload()

I now use /api/me to get auth info.

Thank you. I'll try to make my own plugin for it.