Visual demonstration of the complete physical framework described in Sect. 2. Panel (a): Face-on projected column density map of the HI surface density in the low-mass dwarf galaxy at t ∼ 500 Myr in the MBH4_full simulation (see Table 2). Panel (b): Zoom-in on a recently active star-forming region where SNII explosions have injected energy into the surrounding gas, pushing it in all directions shaping a ‘bubble’ in the ISM. Star particles formed during the simulation are indicated and colour-coded according to their stellar age (normalised between 0 and 100 Myr, where blue represents the youngest and red the oldest stellar populations, respectively). Panels (c)–(d): Further zoom-in on a group of young star particles from panel b. By displaying face-on projected column density maps of the HII and H₂ surface densities, side-by-side, we can distinguish the molecular cloud from which the star particles were born from (panel d), and how the ISR (modelled using radiative transfer on the fly) from individually sampled O and B stars propagates and ionises the surrounding gas (panel c). Panel (e): Zoom-in on the region close to the central MBH. Panel (f): Further zoom-in on the MBH and its accretion radius r_acc (dashed black circle), with a slice (aligned in the z direction with the MBH) through the gas displaying its Voronoi structure. At this scale, individual gas cells can be seen inside the accretion region (r < r_acc), highlighting the refinement strategy outlined in Sect. 2.4.2.