 Open cover criterion for a local sheaf topos

Equivalently every open cover of $X$ contains $X$ as a member, so the top element of its open-set lattice is supercompact in the frame sense. Necessity follows from preservation of coproducts and epimorphisms by global sections. Conversely the union of all proper opens misses a point $x$, and the stalk functor there equals global sections. Its right adjoint is a skyscraper sheaf of sets. Empty spaces fail; a T1 space satisfies the condition exactly when it is a singleton.