For a compact spin$$^{c}$$
c
manifold X with boundary $$b_1(\partial X)=0$$
b
1
(
∂
X
)
=
0
, we consider moduli spaces of solutions to the Seiberg–Witten equations in a generalized double Coulomb slice in $$W^{1,2}$$
W
1
,
2
Sobolev regularity. We prove they are Hilbert manifolds, prove denseness and “semi-infinite-dimensionality” properties of the restriction to $$\partial X$$
∂
X
, and establish a gluing theorem. To achieve these, we prove a general regularity theorem and a strong unique continuation principle for Dirac operators, and smoothness of a restriction map to configurations of higher regularity on the interior, all of which are of independent interest.