The semi-total point graph T₂(G) of a graph G is obtained by taking V(G) ∪ E(G) as its vertex set, where two vertices are adjacent if they are adjacent in G, or if one represents a vertex of G and the other an incident edge. In this paper, we investigate the split domination integrity SDI(G), defined asSDI(G)=min{|D|+m(G−D):D⊆V(G)},where D is a split dominating set and m(G − D) is the order of a maximum component of G − D. We derive sharp bounds and structural constraints for SDI(T₂(G)) and compute its exact values for the Cartesian product of semi-total point graphs of several families of graphs. The results generalize and extend previous work on domination parameters of semi-total point graphs by introducing the vulnerability parameter SDI to this class of graphs.