diff --git a/packages/editor/src/components/tools/item/use-placement-coordinator.tsx b/packages/editor/src/components/tools/item/use-placement-coordinator.tsx
index cdc502f2..83ddcfad 100644
--- a/packages/editor/src/components/tools/item/use-placement-coordinator.tsx
+++ b/packages/editor/src/components/tools/item/use-placement-coordinator.tsx
@@ -610,10 +610,10 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     }
 
     // Floor grab-offset: the item tracks the grabbed point instead of snapping
-    // its origin under the cursor. `floorStrategy.move` snaps on the WORLD grid
-    // (`event.position`) on its default path and only reads `event.localPosition`
-    // under Alt (free place), so both frames must carry the offset; the world
-    // point is derived from the corrected local one so the two stay consistent.
+    // its origin under the cursor. The offset is computed in building-local space
+    // (`event.localPosition`), but `floorStrategy.move` snaps on the WORLD grid
+    // (`event.position`), so the corrected local point is re-projected to a
+    // corrected world point and both frames carry the offset to stay consistent.
     const applyFloorGrabOffset = (event: GridEvent): GridEvent => {
       if (relativeFloorStart === null) return event
       const rawX = event.localPosition[0]