  We report on an analysis of the Vasiliev construction for minimal bosonic
higher-spin master fields with oscillators that are vectors of SO(D-1,2) and
doublets of Sp(2,R). We show that, if the original master field equations are
supplemented with a strong Sp(2,R) projection of the 0-form while letting the
1-form adjust to the resulting Weyl curvatures, the linearized on-shell
constraints exhibit both the proper mass terms and a geometric gauge symmetry
with unconstrained, traceful parameters. We also address some of the subtleties
related to the strong projection and the prospects for obtaining a finite
curvature expansion.
