  We present a series of high-resolution simulations generated with the
moving-mesh code AREPO to model the merger of a $1.1 \, \mathrm{M_\odot}$
carbon-oxygen primary white dwarf with an outer helium layer and a
$0.35\,\mathrm{M_\odot}$ secondary helium white dwarf. Our simulations lead to
detonations that are consistent with the edge-lit scenario, where a helium
detonation is ignited at the base of the helium layer of the primary WD, which
triggers an off-centre carbon detonation. This produces an asymmetric ejecta
pattern and differences in line-of-sight observables (e.g. mean atomic weight).
The ejecta that are flung into space are dominated by $^{56}\mathrm{Ni}$,
$^{4}\mathrm{He}$, $^{28}\mathrm{Si}$, and $^{32}\mathrm{S}$. Our simulations
result in a surviving degenerate companion of mass $0.22-0.25$
$\mathrm{M_\odot}$ moving at $>1\,700$ $\mathrm{km}\,\mathrm{s}^{-1}$,
consistent with the observational findings of hypervelocity WDs. The
secondary's surface layers are enriched by heavy metals, with
$^{56}\mathrm{Ni}$ making up approximately $0.8 \%$ of the remaining mass. We
also analyse the sensitivity of the outcome on simulation parameters, including
the "inspiral time", which defines a period of accelerated angular momentum
loss. We find that the choice of "inspiral time" qualitatively influences the
simulation result, including the survival of the secondary. We argue that the
shorter inspiral cases result in qualitatively and quantitatively similar
outcomes. We also investigate the sensitivity of our results on the primary's
chemical profile by comparing simulations using isothermal, constant
composition models with the same mass and central composition and characterised
by either a bare carbon-oxygen core (no helium) or a carbon-oxygen core
enveloped by a thick helium layer.
