Stability domains for the co-orbital candidates of the TOI-178 system. Panel a: as a function of the mass of the two co-orbitals, fixing m₃ = 2.5 × 10⁻⁵m₀. Panel b: as a function of the mass of the two coorbitals μ and the inner planet m₃. Dotted lines represent the intersection of the planes of initial conditions (panels a and b). The colour code is the same as Fig. 2. Panel a shows black dots to represent orbits that are stable over 10¹⁰ orbital periods; see Sect. 2.2 for more details. The numbers displayed in panel a are the value of p for the disruptive Ψ = pν + g resonances.