  We study Landau-Zener dynamics in a double quantum dot filled with two
electrons, where the spin states can become correlated with charge states and
the level velocity can be tuned in a time-dependent fashion. We show that a
correct interpretation of experimental data is only possible when finite-time
effects are taken into account. In addition, our formalism allows the study of
partial adiabatic dynamics in the presence of phonon-mediated hyperfine
relaxation and charge-noise-induced dephasing. Our findings demonstrate that
charge noise severely impacts the visibility of
Landau-Zener-St\"uckelberg-Majorana interference fringes. This indicates that
charge coherence must be treated on an equal footing with spin coherence.
