Whatever it is, if you like the way it rides, and it fits, then it's worth refurbing/restoring.

+1 the 26.6mm seat post likely points to a Cro-moly plain gauge seat tube. But weigh the frame, perhaps only the seat tube is plain gauge due the tall size. Tall frames tend to use a thicker seat tube for stiffness. If the frame is light, the rest of the main tubes may be DB.
Also, make sure it's 26.6mm, and not pinched down to that size. 26.8mm has been sizing for some Columbus SP and Tange Champion #2 seat tubed frames.

Are the Exage Motion components original to the bike? That would make it around 1988-1990 production. By that time, did Atala farm out production to Asia like Bianchi?
But the dropouts tend to make this a European production. A Raleigh?

I say 'unclunker' it with a new finish, and nicer components, and slap Non-Fixie decals on it. Looks to have fast geometry.