  We derive the soft effective action in $(d+2)$-dimensional abelian gauge
theories from the on-shell action obeying Neumann boundary conditions at
timelike and null infinity and Dirichlet boundary conditions at spatial
infinity. This allows us to identify the on-shell degrees of freedom on the
boundary with the soft modes living on the celestial sphere. Following the work
of Donnelly and Wall, this suggests that we can interpret soft modes as
entanglement edge modes on the celestial sphere and study entanglement
properties of soft modes in abelian gauge theories.
