Observations of SN 2024ggi (points) compared with hydrodynamical models (lines). Left panel: Bolometric LC. The inset shows density profiles of the models with no CSM (black), with a steady wind (yellow), and with an accelerated wind (blue). Right panel: Photospheric velocity evolution. The shaded grey area marks the approximate time frame during which the emission is dominated mainly by CSM interaction, i.e. times t ≲ Cd = 26 d. The uncertainty on the velocities is taken as ≈ − 500 km s⁻¹, and this takes the resolution of the spectra and the error in the measurements into account.