BPT diagnostic diagram (Baldwin et al. 1981) showing the narrow emission line ratios F_{[N II]λ6584}/F_Hα and F_{[O III]λ5007}/F_Hβ for the four regions (coloured data). Our quoted F_[N II]/F_Hα ratios use the [N II] λ 6584 upper limits with F_Hα, min, giving an upper limit on the ratio. The Kewley et al. (2001), Kauffmann et al. (2003), and Scholtz et al. (2025) demarcation curves distinguish the regions where photoionisation is dominated by galaxies (lower left) and AGNs (upper right), as determined for low-z objects. The underlying grey histogram shows local sources from the SDSS (Abazajian et al. 2009). The grey points show a sample of 3.5 < z < 10 AGN and quasar host galaxies measured with JWST (Übler et al. 2023; Marshall et al. 2023; Harikane et al. 2023; Maiolino et al. 2024; Decarli et al. 2024; Scholtz et al. 2025; Bertola et al. 2025, using the combined narrow and outflow fluxes for sources that were kinematically decoupled into two components to compare to our single-component line fits).