  Artificial microswimmers, or "microbots" have the potential to revolutionise
non-invasive medicine and microfluidics. Microbots that are powered by
self-phoretic mechanisms, such as Janus particles, often harness a solute fuel
in their environment. Traditionally, self-phoretic particles are point-like,
but slender phoretic rods have become an increasingly prevalent design. While
there has been substantial interest in creating efficient asymptotic theories
for slender phoretic rods, hitherto such theories have been restricted to
straight rods with axisymmetric patterning. However, modern manufacturing
methods will soon allow fabrication of slender phoretic filaments with complex
three-dimensional shape. In this paper, we develop a slender body theory for
the solute of self-diffusiophoretic filaments of arbitrary three-dimensional
shape and patterning. We demonstrate analytically that, unlike other slender
body theories, first-order azimuthal variations arising from curvature and
confinement can have a leading order contribution to the swimming kinematics.
