Emptying a room, not inventing one
Furniture removal is the transform where AI editors most often hand back something that is not your property. Asked to clear a room, a model will happily produce a plausible empty room, with a different floor, a different window and different proportions, because plausibility is what it optimises for.
The guard is the mask. Furniture is segmented by concept, the regions combined and grown, and an inpainting model reconstructs only inside them. Everything outside is untouched by construction, and we verify exactly that: structure and colour are measured outside the cleared region, where the answer should be "nothing changed".
That check is not theoretical. An earlier version scored the whole frame and a render that had replaced the entire scene passed, because a full-frame score is dragged down by the legitimate removal and can no longer tell the difference. Scoring outside the mask separates the two cleanly.
When it refuses
Past roughly 45% furniture coverage the model is reconstructing more than it can infer. We measured a room at 65% and got back a bed against a window with none of the original in it. Rather than deliver that, or quietly burn attempts producing more of it, the edit is refused with the reason and nothing is charged.