Thermal and non-thermal emission from a variable outflow – internal shock framework. Top left: initial distribution of the Lorentz factor in the flow. Top right: thermal (red), non-thermal (blue), and total (black) photon flux in the 8 keV–40 MeV spectral range. Bottom left: thermal (red), non-thermal (blue), and total (black) time-integrated spectra. Bottom right: instant temperature (red) of the photospheric emission and instant peak energy (blue) of the internal shock emission. The dotted and dashed lines correspond to the temperature and peak energy averaged over time intervals of 2 and 4 s, respectively. The adopted flow parameters are Ė_iso = 10⁵³ erg s^-1, ϵ_th = 0.03, σ = 0.1, ℓ = 3 × 10⁶ cm, and θ = 0.1 rad; a redshift z = 1 is assumed.