A low cover is not a defect

cover counts pixels differing from the frame’s own ground by more than a threshold, on any channel. The ground is the scored frame’s most populous luminance band, the estimator the sanity lens uses — not a sampled pixel, which on a cellular world can land on a live cell. The difference is symmetric, so dark-on-light and light-on-dark are measured identically. An ink-remapped look is not penalised by construction, and a low reading is not evidence of one.

What a low cover means is that the frame is sparse, and sparse is often the intent. reaction_coral_bloom reports 0.128, about as low as the shipped set goes, and is healthy — it is the family’s ink-on-paper variant, a pale print whose chaotic-branching regime genuinely covers an eighth of the frame. The number is truthful; what it cannot tell you is “sparse on purpose” from “dead”.

So the column names suspects rather than convicting them. A low cover alongside a dead anim and flat reactivity columns is worth investigating; a low cover on a preset that is deliberately a thin figure on a wide ground is the report working.