  The possibility to reanalyse data taken by the HERA experiments offers the
chance to study modern QCD jet and event-shape observables in deep-inelastic
scattering. To address this, we compute resummed and matched predictions for
the 1-jettiness distribution in neutral current DIS with and without grooming
the hadronic final state using the soft-drop technique. Our theoretical
predictions also account for non-perturbative corrections from hadronisation
through parton-to-hadron level transfer matrices extracted from dedicated Monte
Carlo simulations with Sherpa. To estimate parameter uncertainties in
particular for the beam-fragmentation modelling we derive a family of replica
tunes to data from the HERA experiments. While NNLO QCD normalisation
corrections to the NLO+NLL' prediction are numerically small, hadronisation
corrections turn out to be quite sizeable. However, soft-drop grooming
significantly reduces the impact of non-perturbative contributions. We
supplement our study with hadron-level predictions from Sherpa based on the
matching of NLO QCD matrix elements with the parton shower. Good agreement
between the predictions from the two calculational methods is observed.
