  We consider the Klein-Gordon equation on asymptotically anti-de Sitter
spacetimes subject to Neumann or Robin (or Dirichlet) boundary conditions, and
prove propagation of singularities along generalized broken bicharacteristics.
The result is formulated in terms of conormal regularity relative to a twisted
Sobolev space. We use this to show the uniqueness, modulo regularising terms,
of parametrices with prescribed b-wavefront set. Furthermore, in the context of
quantum fields, we show a similar result for two-point functions satisfying a
holographic Hadamard condition on the b-wavefront set.
