Simulated long-GRB light curves for two central engine mechanisms: NDAF and BZ. The NDAF model exhibits a steep decay, whereas the BZ model shows a more gradual one. Colours represent variations in initial parameters – (a) black hole spin, (b) accretion rate, (c) accretion disc mass, and (d) black hole mass – illustrated by the colour bars. For each parameter set, the top left panel shows the evolution of the accretion rate over time; the top right panel shows the evolution of the spin parameter; the bottom left panel shows the luminosity evolution, where the NDAF model is plotted as red dashed lines (typical slope −4.5) and the BZ model as blue dashed lines (typical slope −1.5); and the bottom right panel compares the two mechanisms after alignment.