Blimey!
No real help on identification I'm afraid
But I agree, you ought to build it
Looks like if the swing arm deflects up, the top tube/seat tube will be caused to be levered downward...
That is a suspened or pivoting top tube, I grubbed about searching with terms around that and found one or two oddities, eg a Cannondale where the whole rear triangle pivoted about the BB with the shock in the top tube!
But still not as odd as yours
I don't really understand what the aim of this arrangement is!
Quality construction and obviously incredibly rare, probably a one off? But it has an S/N which would suggest it's production :?: