Two-dimensional projections, in 20 Mpc thick slices, of the cosmic web identified at z = 1 from different galaxy samples. Top row: the mass-complete TNG100 sample (left) versus a mock sample with HLWAS-Deep photometric and spectroscopic depths (right). Bottom row: the mass-complete TNG50 sample (left) versus mock samples with both HLWAS-Ultra deep photometric depth and 2.5 × HLWAS-Deep spectroscopic depth (middle) and 5 × HLWAS-Deep (right). Filaments, galaxies, and DM overdensity are denoted similar to Figure 1. The planned spectroscopic depths of the HLWAS will only allow partial cosmic web reconstruction; deeper spectroscopy is essential.