  Topological duality defects arise as codimension one generalized symmetry
operators in quantum field theories (QFTs) with a duality symmetry. Recent
investigations have shown that in the case of 4D $\mathcal{N} = 4$ Super
Yang-Mills (SYM) theory, an appropriate choice of (complexified) gauge coupling
and global form of the gauge group can lead to a rather rich fusion algebra for
the associated defects, leading to examples of non-invertible symmetries. In
this work we present a top down construction of these duality defects which
generalizes to QFTs with lower supersymmetry, where other 0-form symmetries are
often present. We realize the QFTs of interest via D3-branes probing $X$ a
Calabi-Yau threefold cone with an isolated singularity at the tip of the cone.
The IIB duality group descends to dualities of the 4D worldvolume theory.
Non-trivial codimension one topological interfaces arise from configurations of
7-branes "at infinity" which implement a suitable $SL(2, \mathbb{Z})$
transformation when they are crossed. Reduction on the boundary topology
$\partial X$ results in a 5D symmetry TFT. Different realizations of duality
defects, such as the gauging of 1-form symmetries with certain mixed anomalies
and half-space gauging constructions, simply amount to distinct choices of
where to place the branch cuts in the 5D bulk.
