Time evolution of abundances of C, S, CS, SiS, and SiC, shown in black, blue, magenta, red, and yellow, respectively. Panels a and b illustrate simulations with high- and low-metallicity values, respectively, using the default network of chemical reactions. Panels c and d represent high- and low-metallicity models, respectively, incorporating the newly computed chemical reactions in this work (see Table 2). The interval indicated by the arrows, between 10³–10⁵ yr, signifies an early stage of relative stabilisation in the SiS abundance (see Sect 4.1).