  We point out that the LDMX (Light Dark Matter eXperiment) detector design,
conceived to search for sub-GeV dark matter, will also have very advantageous
characteristics to pursue electron-nucleus scattering measurements of direct
relevance to the neutrino program at DUNE and elsewhere. These characteristics
include a 4-GeV electron beam, a precision tracker, electromagnetic and
hadronic calorimeters with near 2$\pi$ azimuthal acceptance from the forward
beam axis out to $\sim$40$^\circ$ angle, and low reconstruction energy
threshold. LDMX thus could provide (semi)exclusive cross section measurements,
with detailed information about final-state electrons, pions, protons, and
neutrons. We compare the predictions of two widely used neutrino generators
(GENIE, GiBUU) in the LDMX region of acceptance to illustrate the large
modeling discrepancies in electron-nucleus interactions at DUNE-like
kinematics. We argue that discriminating between these predictions is well
within the capabilities of the LDMX detector.
