Two representative synthetic-impact cases illustrating how visibility does—or does not—translate into discovery. Panel (a) demonstrates all three loss mechanisms. Segments with no blue points represent pointing loss; blue points without red crosses indicate magnitude or trailing loss; and isolated red-cross detections that never form tracklets represent linking loss. Panel (b) shows a case where all conditions align, enabling full linkage and discovery. Together, these two examples encapsulate the essential survey failure modes that govern LSST’s impactor completeness.