yeah

src/state/bulk-replace/with-critical-replacement.js

@@ -1,6 +1,7 @@
 // @flow
+import invariant from 'tiny-invariant';
 import type { Position } from 'css-box-model';
-import { add, subtract } from '../position';
+import { add, subtract, isEqual } from '../position';
 import getDragImpact from '../get-drag-impact';
 import getHomeImpact from '../get-home-impact';
 import type {
@@ -33,11 +34,23 @@ export default ({
   critical,
   dimensions,
 }: Args): Result => {
-  const oldClientBorderBoxCenter: Position = state.initial.client.borderBoxCenter;
   const draggable: DraggableDimension = dimensions.draggables[critical.draggable.id];
+
+  invariant(isEqual(draggable.client.borderBox.center, state.current.client.borderBoxCenter),
+    `Collected client borderBox center: ${JSON.stringify(draggable.client.borderBox.center)}
+    does not match the previously current client center: ${JSON.stringify(state.current.client.borderBoxCenter)}`
+  );
+
+  invariant(isEqual(draggable.page.borderBox.center, state.current.page.borderBoxCenter),
+    `Collected page borderBox center: ${JSON.stringify(draggable.page.borderBox.center)}
+    does not match the previously current page center: ${JSON.stringify(state.current.page.borderBoxCenter)}`
+  );
+
+  const oldClientBorderBoxCenter: Position = state.initial.client.borderBoxCenter;
   const newClientBorderBoxCenter: Position = draggable.client.borderBox.center;
   // How much the dragging item is shifting
   const centerDiff: Position = subtract(newClientBorderBoxCenter, oldClientBorderBoxCenter);
+  console.warn('CENTER DIFF', centerDiff);
 
   const oldInitialClientSelection: Position = state.initial.client.selection;
   const newInitialClientSelection: Position = add(oldInitialClientSelection, centerDiff);
@@ -80,10 +93,12 @@ export default ({
 
   console.group('critical replacement');
   console.log('NEW START INDEX', critical.draggable.index);
-  console.log('PRE-UPDATE: initial page center', state.initial.page.borderBoxCenter)
-  console.log('PRE-UPDATE: current page center', state.current.page.borderBoxCenter)
+  console.log('PRE-UPDATE: initial page center', state.initial.page.borderBoxCenter);
+  console.log('PRE-UPDATE: current page center', state.current.page.borderBoxCenter);
   console.warn('POST-UPDATE: initial page center', initial.page.borderBoxCenter);
   console.warn('POST-UPDATE: current page center', current.page.borderBoxCenter);
+  // console.log('PRE (generated-1): page center', state.dimensions.draggables['generated-1'].page.borderBox.center)
+  // console.log('POST(generated-1):  page center', dimensions.draggables['generated-1'].page.borderBox.center)
   console.log('home impact', getHomeImpact(critical, dimensions));
 
   const impact: DragImpact = getDragImpact({
@@ -100,7 +115,6 @@ export default ({
   console.log('displaced', impact.movement.displaced.map(entry => entry.draggableId));
   console.groupEnd();
 
-
   // stripping out any animations
   const forcedNoAnimations: DragImpact = {
     ...impact,

src/state/get-drag-impact/in-home-list.js

@@ -33,14 +33,18 @@ export default ({
   previousImpact,
   viewport,
 }: Args): DragImpact => {
+  console.group('in home list');
   const axis: Axis = home.axis;
   // The starting center position
   const originalCenter: Position = draggable.page.borderBox.center;
+  console.log('original page center', originalCenter);
 
   // Where the element actually is now.
   // Need to take into account the change of scroll in the droppable
   const currentCenter: Position = withDroppableScroll(home, pageBorderBoxCenter);
 
+  console.log('current page center', currentCenter);
+
   // not considering margin so that items move based on visible edges
   const isBeyondStartPosition: boolean =
     currentCenter[axis.line] - originalCenter[axis.line] > 0;
@@ -50,6 +54,8 @@ export default ({
   // Amount to move needs to include the margins
   const amount: Position = patch(axis.line, draggable.client.marginBox[axis.size]);
 
+  console.groupEnd();
+
   const displaced: Displacement[] = insideHome
     .filter((child: DraggableDimension): boolean => {
       // do not want to move the item that is dragging

src/view/draggable-dimension-publisher/draggable-dimension-publisher.jsx

@@ -114,6 +114,8 @@ export default class DraggableDimensionPublisher extends Component<Props> {
       // from when the drag started
       const undoWindowScroll: Position = negate(windowScrollDiff);
 
+      console.log('offseting dragging item by', add(undoTransform, undoWindowScroll));
+
       return add(undoTransform, undoWindowScroll);
     })();