Full Linear Homomesy Spaces for Rowmotion on Rooted Forests

For every finite rooted forest with minimal roots, we compute the full spaces of linear order-ideal and antichain statistics that have zero average on every rowmotion orbit. The algorithm retains the orbit through the empty ideal and two affine hulls, each represented by at most n+1 vectors, instead of enumerating the orbits. A deletion lemma for Cartesian products yields scalar recursions for both zero-mesy dimensions and an exact rational basis algorithm using O(n^4) field operations, apart from integer gcd/lcm operations. The two full homomesy dimensions agree; the zero-mesy dimensions can differ by one. A known acyclic-toggle theorem transfers the ideal-indicator result to Coxeter toggle actions.