Model performance across different redshift (a) and signal-to-noise ratio in the r-band (S/Nr) intervals (b). In each panel, the solid blue line represents spectral classification accuracy, while the dashed yellow line indicates the standard deviation (σ) of gas-phase metallicity predictions (∆ = Z_pred - Z_true). Error bars in each interval denote the standard deviation of the prediction error, and black circles indicate the median standard deviation within each bin.