Kinematic moment-1 (line-of-sight velocity) maps at the end of the simulation, with moment-1 from the initial condition subtracted, as in Fig. 2. In contrast to the plots in Fig. 2, we fix the disk inclination to 0^◦ (face-on) and plot (from left to right) the maps corresponding to the J = 2 − 1 transitions of the ¹²CO , ¹³CO , and C¹⁸O isotopologues, which respectively trace the upper, intermediate, and midplane layers of the disk. In C¹⁸O, the two-armed signature of the shadow-driven spiral is virtually absent, but for the standard planet-driven case the inner Lindlbad spirals remain visible.