  We review and extend some recent results concerning the analysis of spacetime
singularities in four-dimensional higher spin gravity, summarizing how the
coupling of the gravitational field to massless higher spins may provide
resolution mechanisms. We elucidate such mechanisms at the level of curvature
singularities and degenerate metrics in exact as well as linearized solutions
to Vasiliev's equations. As a preamble, we review the underlying higher-spin
algebra and its metaplectic group extensions, after which we detail various
gauge functions encoding the $AdS_4$ vacuum and the non-rotating
Banados--Gomberoff--Martinez (BGM) metric, the four-dimensional lift of the
spinless BTZ black hole, in different coordinate patches related by transition
functions. We then revisit how, within the unfolded formalism, it is natural
extend the BGM black hole through its causal singularity. Finally, we compare
the metric-like and unfolded descriptions of scalar fluctuations over the
(extended) BGM background, showing how the latter description maps
singularities to well-defined metaplectic group elements providing regular
values for the Weyl zero-form master field, which thus admits continuation over
the full extended BGM spacetime.
