Stream maps: The left, middle, and right panels respectively present the face-on maps of radial velocity (top row) and surface density (bottom row) in VELA 7 at z = 1.5, corresponding to all cold gas, streams identified via the metallicity-based method, and streams identified via the streamline-based method. To aid visual recognition of streams, the maps in the left panels are shown over an expanded area of 3R_d × 3R_d. However, the actual classification of cold gas into streams and non-streams is confined to the galactic disk, defined as a cylinder with radius R_d and height H_d, as shown in the middle and right panels. Red dashed circles denote the radial extent of this disk. In the left panels, two distinct inflowing cold gas groups are apparent (blue in the v_r,2D map indicates inward motion), entering within R_d either from the top or the bottom-right and subsequently spiraling counter-clockwise toward the galactic center. The metallicity- and streamline-based classifications select somewhat different portions of these inflowing groups as streams. The areas enclosed by the orange ellipses (labeled a, b, and c) correspond to the main regions of disagreement between the two classification methods; these discrepancies are discussed further in Sect. 5.3.