Stellar locus and morphological classification in LW NIRCam filters. The black stars show the 95th percentile effective radius posterior (r_eff, 95%) vs. magnitude for reference stars, with the best-fit stellar locus (gray dashed line). We classify galaxies as point sources (green hashed area) if they fall below the +4σ_resid offset of this relation (r_rsv; green line). The gray circles show all RUBIES sources with robust z_spec > 3.1, red hexagons highlight spectroscopic LRDs (Section 4.2), and black circles mark non-LRD sources with dominant point-sources (Section 3.3.1), plotted in the LW filter that traces the rest-5500 Å flux.