diff --git a/apps/editor/components/tools/item/move-tool.tsx b/apps/editor/components/tools/item/move-tool.tsx
index 7d73c926..c3cc7c38 100644
--- a/apps/editor/components/tools/item/move-tool.tsx
+++ b/apps/editor/components/tools/item/move-tool.tsx
@@ -34,13 +34,15 @@ function MoveItemContent({ movingNode }: { movingNode: ItemNode }) {
     draftNode,
     // Duplicates start fresh in floor mode; wall/ceiling draft is created lazily by ensureDraft
     initialState: isNew ? { surface: 'floor', wallId: null, ceilingId: null, surfaceItemId: null } : getInitialState(movingNode),
+    // Preserve the original item's scale so Y-position calculations use the correct height
+    defaultScale: isNew ? movingNode.scale : undefined,
     initDraft: (gridPosition) => {
       if (isNew) {
         // Duplicate: use the same create() path as ItemTool so ghost rendering works correctly.
         // Floor items get a draft immediately; wall/ceiling items are created lazily on surface entry.
         gridPosition.copy(new Vector3(...movingNode.position))
         if (!movingNode.asset.attachTo) {
-          draftNode.create(gridPosition, movingNode.asset, movingNode.rotation)
+          draftNode.create(gridPosition, movingNode.asset, movingNode.rotation, movingNode.scale)
         }
       } else {
         draftNode.adopt(movingNode)
diff --git a/apps/editor/components/tools/item/placement-strategies.ts b/apps/editor/components/tools/item/placement-strategies.ts
index 08b782ef..69daf861 100644
--- a/apps/editor/components/tools/item/placement-strategies.ts
+++ b/apps/editor/components/tools/item/placement-strategies.ts
@@ -9,7 +9,7 @@ import type {
   WallEvent,
   WallNode,
 } from '@pascal-app/core'
-import { sceneRegistry, useScene } from '@pascal-app/core'
+import { getScaledDimensions, sceneRegistry, useScene } from '@pascal-app/core'
 import { Vector3 } from 'three'
 import type {
   CommitResult,
@@ -43,7 +43,7 @@ export const floorStrategy = {
   move(ctx: PlacementContext, event: GridEvent): PlacementResult | null {
     if (ctx.state.surface !== 'floor') return null
 
-    const dims = ctx.asset.dimensions ?? DEFAULT_DIMENSIONS
+    const dims = ctx.draftItem ? getScaledDimensions(ctx.draftItem) : (ctx.asset.dimensions ?? DEFAULT_DIMENSIONS)
     const [dimX, , dimZ] = dims
     const x = snapToGrid(event.position[0], dimX)
     const z = snapToGrid(event.position[2], dimZ)
@@ -70,7 +70,7 @@ export const floorStrategy = {
     const valid = validators.canPlaceOnFloor(
       ctx.levelId,
       pos,
-      ctx.draftItem.asset.dimensions,
+      getScaledDimensions(ctx.draftItem),
       [0, 0, 0],
       [ctx.draftItem.id],
     ).valid
@@ -128,7 +128,7 @@ export const wallStrategy = {
       event.node.id,
       x,
       y,
-      ctx.asset.dimensions ?? DEFAULT_DIMENSIONS,
+      ctx.draftItem ? getScaledDimensions(ctx.draftItem) : (ctx.asset.dimensions ?? DEFAULT_DIMENSIONS),
       attachTo,
       side,
       [],
@@ -179,7 +179,7 @@ export const wallStrategy = {
       event.node.id,
       snappedX,
       snappedY,
-      ctx.draftItem.asset.dimensions,
+      getScaledDimensions(ctx.draftItem),
       ctx.draftItem.asset.attachTo as 'wall' | 'wall-side',
       side,
       [ctx.draftItem.id],
@@ -219,7 +219,7 @@ export const wallStrategy = {
       ctx.state.wallId as WallNode['id'],
       ctx.gridPosition.x,
       ctx.gridPosition.y,
-      ctx.draftItem.asset.dimensions,
+      getScaledDimensions(ctx.draftItem),
       ctx.draftItem.asset.attachTo as 'wall' | 'wall-side',
       ctx.draftItem.side,
       [ctx.draftItem.id],
@@ -281,7 +281,7 @@ export const ceilingStrategy = {
     const ceilingLevelId = resolveLevelId(event.node, nodes)
     if (ctx.levelId !== ceilingLevelId) return null
 
-    const dims = ctx.asset.dimensions ?? DEFAULT_DIMENSIONS
+    const dims = ctx.draftItem ? getScaledDimensions(ctx.draftItem) : (ctx.asset.dimensions ?? DEFAULT_DIMENSIONS)
     const [dimX, , dimZ] = dims
     const itemHeight = dims[1]
 
@@ -308,7 +308,7 @@ export const ceilingStrategy = {
     if (ctx.state.surface !== 'ceiling') return null
     if (!ctx.draftItem) return null
 
-    const dims = ctx.asset.dimensions ?? DEFAULT_DIMENSIONS
+    const dims = getScaledDimensions(ctx.draftItem)
     const [dimX, , dimZ] = dims
     const itemHeight = dims[1]
 
@@ -341,7 +341,7 @@ export const ceilingStrategy = {
     const valid = validators.canPlaceOnCeiling(
       ctx.state.ceilingId as CeilingNode['id'],
       pos,
-      ctx.draftItem.asset.dimensions,
+      getScaledDimensions(ctx.draftItem),
       ctx.draftItem.rotation,
       [ctx.draftItem.id],
     ).valid
@@ -399,8 +399,8 @@ export const itemSurfaceStrategy = {
     if (!surfaceItem.asset.surface) return null
 
     // Size check: our footprint must fit on surface item's footprint
-    const ourDims = ctx.asset.dimensions ?? DEFAULT_DIMENSIONS
-    const surfDims = surfaceItem.asset.dimensions
+    const ourDims = ctx.draftItem ? getScaledDimensions(ctx.draftItem) : (ctx.asset.dimensions ?? DEFAULT_DIMENSIONS)
+    const surfDims = getScaledDimensions(surfaceItem)
     if (ourDims[0] > surfDims[0] || ourDims[2] > surfDims[2]) return null
 
     const surfaceMesh = sceneRegistry.nodes.get(surfaceItem.id)
@@ -411,7 +411,7 @@ export const itemSurfaceStrategy = {
 
     const x = snapToGrid(localPos.x, ourDims[0])
     const z = snapToGrid(localPos.z, ourDims[2])
-    const y = surfaceItem.asset.surface.height
+    const y = surfaceItem.asset.surface.height * surfaceItem.scale[1]
 
     const worldSnapped = surfaceMesh.localToWorld(new Vector3(x, y, z))
 
@@ -439,13 +439,13 @@ export const itemSurfaceStrategy = {
     const surfaceMesh = sceneRegistry.nodes.get(ctx.state.surfaceItemId)
     if (!surfaceMesh) return null
 
-    const ourDims = ctx.asset.dimensions ?? DEFAULT_DIMENSIONS
+    const ourDims = getScaledDimensions(ctx.draftItem)
     const worldPos = new Vector3(event.position[0], event.position[1], event.position[2])
     const localPos = surfaceMesh.worldToLocal(worldPos)
 
     const x = snapToGrid(localPos.x, ourDims[0])
     const z = snapToGrid(localPos.z, ourDims[2])
-    const y = surfaceItem.asset.surface.height
+    const y = surfaceItem.asset.surface.height * surfaceItem.scale[1]
 
     const worldSnapped = surfaceMesh.localToWorld(new Vector3(x, y, z))
 
@@ -501,7 +501,7 @@ export function checkCanPlace(ctx: PlacementContext, validators: SpatialValidato
     return validators.canPlaceOnCeiling(
       ctx.state.ceilingId as CeilingNode['id'],
       [ctx.gridPosition.x, ctx.gridPosition.y, ctx.gridPosition.z],
-      ctx.draftItem.asset.dimensions,
+      getScaledDimensions(ctx.draftItem),
       ctx.draftItem.rotation,
       [ctx.draftItem.id],
     ).valid
@@ -514,7 +514,7 @@ export function checkCanPlace(ctx: PlacementContext, validators: SpatialValidato
       ctx.state.wallId as WallNode['id'],
       ctx.gridPosition.x,
       ctx.gridPosition.y,
-      ctx.draftItem.asset.dimensions,
+      getScaledDimensions(ctx.draftItem),
       attachTo,
       ctx.draftItem.side,
       [ctx.draftItem.id],
@@ -525,7 +525,7 @@ export function checkCanPlace(ctx: PlacementContext, validators: SpatialValidato
   return validators.canPlaceOnFloor(
     ctx.levelId,
     [ctx.gridPosition.x, 0, ctx.gridPosition.z],
-    ctx.draftItem.asset.dimensions,
+    getScaledDimensions(ctx.draftItem),
     [0, 0, 0],
     [ctx.draftItem.id],
   ).valid
diff --git a/apps/editor/components/tools/item/use-draft-node.ts b/apps/editor/components/tools/item/use-draft-node.ts
index 07213229..4d52a944 100644
--- a/apps/editor/components/tools/item/use-draft-node.ts
+++ b/apps/editor/components/tools/item/use-draft-node.ts
@@ -18,7 +18,7 @@ export interface DraftNodeHandle {
   /** Whether the current draft was adopted (move mode) vs created (create mode) */
   readonly isAdopted: boolean
   /** Create a new draft item at the given position. Returns the created node or null. */
-  create: (gridPosition: Vector3, asset: AssetInput, rotation?: [number, number, number]) => ItemNode | null
+  create: (gridPosition: Vector3, asset: AssetInput, rotation?: [number, number, number], scale?: [number, number, number]) => ItemNode | null
   /** Take ownership of an existing scene node as the draft (for move mode). */
   adopt: (node: ItemNode) => void
   /** Commit the current draft. Create mode: delete+recreate. Move mode: update in place. */
@@ -40,13 +40,14 @@ export function useDraftNode(): DraftNodeHandle {
   const adoptedRef = useRef(false)
   const originalStateRef = useRef<OriginalState | null>(null)
 
-  const create = useCallback((gridPosition: Vector3, asset: AssetInput, rotation?: [number, number, number]): ItemNode | null => {
+  const create = useCallback((gridPosition: Vector3, asset: AssetInput, rotation?: [number, number, number], scale?: [number, number, number]): ItemNode | null => {
     const currentLevelId = useViewer.getState().selection.levelId
     if (!currentLevelId) return null
 
     const node = ItemNode.parse({
       position: [gridPosition.x, gridPosition.y, gridPosition.z],
       rotation: rotation ?? [0, 0, 0],
+      scale: scale ?? [1, 1, 1],
       name: asset.name,
       asset,
       parentId: currentLevelId,
diff --git a/apps/editor/components/tools/item/use-placement-coordinator.tsx b/apps/editor/components/tools/item/use-placement-coordinator.tsx
index 7f22a1ee..dcd151e9 100644
--- a/apps/editor/components/tools/item/use-placement-coordinator.tsx
+++ b/apps/editor/components/tools/item/use-placement-coordinator.tsx
@@ -3,6 +3,7 @@ import {
   type AnyNodeId,
   type CeilingEvent,
   emitter,
+  getScaledDimensions,
   type GridEvent,
   type ItemEvent,
   resolveLevelId,
@@ -65,6 +66,8 @@ export interface PlacementCoordinatorConfig {
   onCommitted: () => boolean
   onCancel?: () => void
   initialState?: PlacementState
+  /** Scale to use when lazily creating a draft (e.g. for wall/ceiling duplicates). Defaults to [1,1,1]. */
+  defaultScale?: [number, number, number]
 }
 
 export function usePlacementCoordinator(config: PlacementCoordinatorConfig): React.ReactNode {
@@ -139,7 +142,7 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
       cursorGroupRef.current.position.set(...result.cursorPosition)
       cursorGroupRef.current.rotation.y = result.cursorRotationY
 
-      draftNode.create(gridPosition.current, asset, [0, result.cursorRotationY, 0])
+      draftNode.create(gridPosition.current, asset, [0, result.cursorRotationY, 0], configRef.current.defaultScale)
 
       const draft = draftNode.current
       if (draft) {
@@ -646,7 +649,8 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
 
     // ---- Bounding box geometry ----
 
-    const dims = asset.dimensions ?? DEFAULT_DIMENSIONS
+    const draft = draftNode.current
+    const dims = draft ? getScaledDimensions(draft) : (asset.dimensions ?? DEFAULT_DIMENSIONS)
     const boxGeometry = new BoxGeometry(dims[0], dims[1], dims[2])
     boxGeometry.translate(0, dims[1] / 2, 0)
     const edgesGeometry = new EdgesGeometry(boxGeometry)
@@ -731,7 +735,7 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
         const slabElevation = spatialGridManager.getSlabElevationForItem(
           levelId,
           [gridPosition.current.x, gridPosition.current.y, gridPosition.current.z],
-          asset.dimensions ?? DEFAULT_DIMENSIONS,
+          getScaledDimensions(draftNode.current),
           draftNode.current.rotation,
         )
         mesh.position.y = slabElevation
@@ -743,7 +747,8 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     }
   })
 
-  const dims = config.asset.dimensions ?? DEFAULT_DIMENSIONS
+  const initialDraft = draftNode.current
+  const dims = initialDraft ? getScaledDimensions(initialDraft) : (config.asset.dimensions ?? DEFAULT_DIMENSIONS)
   const initialBoxGeometry = new BoxGeometry(dims[0], dims[1], dims[2])
   initialBoxGeometry.translate(0, dims[1] / 2, 0)
 
diff --git a/apps/editor/components/tools/window/move-window-tool.tsx b/apps/editor/components/tools/window/move-window-tool.tsx
index be2d343f..63bccc95 100644
--- a/apps/editor/components/tools/window/move-window-tool.tsx
+++ b/apps/editor/components/tools/window/move-window-tool.tsx
@@ -2,6 +2,7 @@ import {
   type AnyNodeId,
   emitter,
   sceneRegistry,
+  spatialGridManager,
   useScene,
   type WallEvent,
   WindowNode,
@@ -78,10 +79,17 @@ export const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWin
       if (wallId) useScene.getState().dirtyNodes.add(wallId as AnyNodeId)
     }
 
+    const getLevelId = () => useViewer.getState().selection.levelId
     const getLevelYOffset = () => {
-      const id = useViewer.getState().selection.levelId
+      const id = getLevelId()
       return id ? (sceneRegistry.nodes.get(id as AnyNodeId)?.position.y ?? 0) : 0
     }
+    const getSlabElevation = (wallEvent: WallEvent) =>
+      spatialGridManager.getSlabElevationForWall(
+        wallEvent.node.parentId ?? '',
+        wallEvent.node.start,
+        wallEvent.node.end,
+      )
 
     const hideCursor = () => {
       if (cursorGroupRef.current) cursorGroupRef.current.visible = false
@@ -102,6 +110,8 @@ export const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWin
 
     const onWallEnter = (event: WallEvent) => {
       if (!isValidWallSideFace(event.normal)) return
+      // Only interact with walls on the current level
+      if (event.node.parentId !== getLevelId()) return
 
       const side = getSideFromNormal(event.normal)
       const itemRotation = calculateItemRotation(event.normal)
@@ -134,12 +144,18 @@ export const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWin
         movingWindowNode.id,
       )
 
-      updateCursor(wallLocalToWorld(event.node, clampedX, clampedY, getLevelYOffset()), cursorRotation, valid)
+      updateCursor(
+        wallLocalToWorld(event.node, clampedX, clampedY, getLevelYOffset(), getSlabElevation(event)),
+        cursorRotation,
+        valid,
+      )
       event.stopPropagation()
     }
 
     const onWallMove = (event: WallEvent) => {
       if (!isValidWallSideFace(event.normal)) return
+      // Only interact with walls on the current level
+      if (event.node.parentId !== getLevelId()) return
 
       const side = getSideFromNormal(event.normal)
       const itemRotation = calculateItemRotation(event.normal)
@@ -172,12 +188,18 @@ export const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWin
         movingWindowNode.id,
       )
 
-      updateCursor(wallLocalToWorld(event.node, clampedX, clampedY, getLevelYOffset()), cursorRotation, valid)
+      updateCursor(
+        wallLocalToWorld(event.node, clampedX, clampedY, getLevelYOffset(), getSlabElevation(event)),
+        cursorRotation,
+        valid,
+      )
       event.stopPropagation()
     }
 
     const onWallClick = (event: WallEvent) => {
       if (!isValidWallSideFace(event.normal)) return
+      // Only interact with walls on the current level
+      if (event.node.parentId !== getLevelId()) return
 
       const side = getSideFromNormal(event.normal)
       const itemRotation = calculateItemRotation(event.normal)
diff --git a/apps/editor/components/tools/window/window-math.ts b/apps/editor/components/tools/window/window-math.ts
index 5419dfd4..69882cad 100644
--- a/apps/editor/components/tools/window/window-math.ts
+++ b/apps/editor/components/tools/window/window-math.ts
@@ -1,16 +1,18 @@
-import { type AnyNodeId, type ItemNode, useScene, type WallNode, type WindowNode } from '@pascal-app/core'
+import { getScaledDimensions, type AnyNodeId, type ItemNode, useScene, type WallNode, type WindowNode } from '@pascal-app/core'
 
 /**
- * Converts wall-local (X along wall, Y = height above level floor) to world XYZ.
+ * Converts wall-local (X along wall, Y = height above wall base) to world XYZ.
  * Wall XZ uses level-local coordinates (levels only offset in Y, not XZ).
- * Pass levelYOffset (the level group's current world Y) so the cursor lands at the
- * correct world height when the cursor group is at the scene root.
+ * Pass levelYOffset (the level group's current world Y) and slabElevation (the
+ * wall mesh's Y within the level group) so the cursor lands at the correct world
+ * height — matching how WallSystem positions the wall mesh at slabElevation.
  */
 export function wallLocalToWorld(
   wallNode: WallNode,
   localX: number,
   localY: number,
   levelYOffset = 0,
+  slabElevation = 0,
 ): [number, number, number] {
   const wallAngle = Math.atan2(
     wallNode.end[1] - wallNode.start[1],
@@ -18,7 +20,7 @@ export function wallLocalToWorld(
   )
   return [
     wallNode.start[0] + localX * Math.cos(wallAngle),
-    localY + levelYOffset,
+    slabElevation + localY + levelYOffset,
     wallNode.start[1] + localX * Math.sin(wallAngle),
   ]
 }
@@ -77,7 +79,7 @@ export function hasWallChildOverlap(
     if (child.type === 'item') {
       const item = child as ItemNode
       if (item.asset.attachTo !== 'wall' && item.asset.attachTo !== 'wall-side') continue
-      const [w, h] = item.asset.dimensions
+      const [w, h] = getScaledDimensions(item)
       childLeft = item.position[0] - w / 2
       childRight = item.position[0] + w / 2
       childBottom = item.position[1]       // items store bottom Y
diff --git a/apps/editor/components/tools/window/window-tool.tsx b/apps/editor/components/tools/window/window-tool.tsx
index 3d275456..419deea8 100644
--- a/apps/editor/components/tools/window/window-tool.tsx
+++ b/apps/editor/components/tools/window/window-tool.tsx
@@ -2,6 +2,7 @@ import {
   type AnyNodeId,
   emitter,
   sceneRegistry,
+  spatialGridManager,
   useScene,
   type WallEvent,
   WindowNode,
@@ -44,6 +45,12 @@ export const WindowTool: React.FC = () => {
       const id = getLevelId()
       return id ? (sceneRegistry.nodes.get(id as AnyNodeId)?.position.y ?? 0) : 0
     }
+    const getSlabElevation = (wallEvent: WallEvent) =>
+      spatialGridManager.getSlabElevationForWall(
+        wallEvent.node.parentId ?? '',
+        wallEvent.node.start,
+        wallEvent.node.end,
+      )
 
     const markWallDirty = (wallId: string) => {
       useScene.getState().dirtyNodes.add(wallId as AnyNodeId)
@@ -79,6 +86,8 @@ export const WindowTool: React.FC = () => {
       if (!isValidWallSideFace(event.normal)) return
       const levelId = getLevelId()
       if (!levelId) return
+      // Only interact with walls on the current level
+      if (event.node.parentId !== levelId) return
 
       destroyDraft()
 
@@ -108,12 +117,18 @@ export const WindowTool: React.FC = () => {
 
       const valid = !hasWallChildOverlap(event.node.id, clampedX, clampedY, width, height, node.id)
 
-      updateCursor(wallLocalToWorld(event.node, clampedX, clampedY, getLevelYOffset()), cursorRotation, valid)
+      updateCursor(
+        wallLocalToWorld(event.node, clampedX, clampedY, getLevelYOffset(), getSlabElevation(event)),
+        cursorRotation,
+        valid,
+      )
       event.stopPropagation()
     }
 
     const onWallMove = (event: WallEvent) => {
       if (!isValidWallSideFace(event.normal)) return
+      // Only interact with walls on the current level
+      if (event.node.parentId !== getLevelId()) return
 
       const side = getSideFromNormal(event.normal)
       const itemRotation = calculateItemRotation(event.normal)
@@ -142,13 +157,19 @@ export const WindowTool: React.FC = () => {
         draftRef.current?.id,
       )
 
-      updateCursor(wallLocalToWorld(event.node, clampedX, clampedY, getLevelYOffset()), cursorRotation, valid)
+      updateCursor(
+        wallLocalToWorld(event.node, clampedX, clampedY, getLevelYOffset(), getSlabElevation(event)),
+        cursorRotation,
+        valid,
+      )
       event.stopPropagation()
     }
 
     const onWallClick = (event: WallEvent) => {
       if (!draftRef.current) return
       if (!isValidWallSideFace(event.normal)) return
+      // Only interact with walls on the current level
+      if (event.node.parentId !== getLevelId()) return
 
       const side = getSideFromNormal(event.normal)
       const itemRotation = calculateItemRotation(event.normal)
diff --git a/apps/editor/components/ui/panels/item-panel.tsx b/apps/editor/components/ui/panels/item-panel.tsx
index 655fc19d..c3c2d87e 100644
--- a/apps/editor/components/ui/panels/item-panel.tsx
+++ b/apps/editor/components/ui/panels/item-panel.tsx
@@ -1,10 +1,10 @@
 'use client'
 
-import { type AnyNode, ItemNode, useScene } from '@pascal-app/core'
+import { getScaledDimensions, type AnyNode, ItemNode, useScene } from '@pascal-app/core'
 import { useViewer } from '@pascal-app/viewer'
-import { Copy, Move, Trash2, X } from 'lucide-react'
+import { Copy, Link, Link2Off, Move, Trash2, X } from 'lucide-react'
 import Image from 'next/image'
-import { useCallback } from 'react'
+import { useCallback, useState } from 'react'
 import useEditor from '@/store/use-editor'
 import { NumberInput } from '@/components/ui/primitives/number-input'
 import { sfxEmitter } from '@/lib/sfx-bus'
@@ -23,6 +23,8 @@ export function ItemPanel() {
     ? (nodes[selectedId as AnyNode['id']] as ItemNode | undefined)
     : undefined
 
+  const [uniformScale, setUniformScale] = useState(true)
+
   const handleUpdate = useCallback(
     (updates: Partial<ItemNode>) => {
       if (!selectedId || !node) return
@@ -188,13 +190,75 @@ export function ItemPanel() {
             </div>
           </div>
 
-          {/* Dimensions (read-only) */}
+          {/* Scale */}
+          <div className="space-y-2">
+            <div className="flex items-center justify-between">
+              <label className="font-medium text-muted-foreground text-xs uppercase tracking-wide">
+                Scale
+              </label>
+              <button
+                type="button"
+                className="rounded p-1 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground cursor-pointer"
+                onClick={() => setUniformScale((v) => !v)}
+                title={uniformScale ? 'Unlock axes' : 'Lock axes'}
+              >
+                {uniformScale ? <Link className="h-3.5 w-3.5" /> : <Link2Off className="h-3.5 w-3.5" />}
+              </button>
+            </div>
+            {uniformScale ? (
+              <NumberInput
+                label="XYZ"
+                value={Math.round(node.scale[0] * 100) / 100}
+                onChange={(value) => {
+                  const v = Math.max(0.01, value)
+                  handleUpdate({ scale: [v, v, v] })
+                }}
+                precision={2}
+                step={0.1}
+              />
+            ) : (
+              <div className="grid grid-cols-3 gap-2">
+                <NumberInput
+                  label="X"
+                  value={Math.round(node.scale[0] * 100) / 100}
+                  onChange={(value) => {
+                    handleUpdate({ scale: [Math.max(0.01, value), node.scale[1], node.scale[2]] })
+                  }}
+                  precision={2}
+                  step={0.1}
+                />
+                <NumberInput
+                  label="Y"
+                  value={Math.round(node.scale[1] * 100) / 100}
+                  onChange={(value) => {
+                    handleUpdate({ scale: [node.scale[0], Math.max(0.01, value), node.scale[2]] })
+                  }}
+                  precision={2}
+                  step={0.1}
+                />
+                <NumberInput
+                  label="Z"
+                  value={Math.round(node.scale[2] * 100) / 100}
+                  onChange={(value) => {
+                    handleUpdate({ scale: [node.scale[0], node.scale[1], Math.max(0.01, value)] })
+                  }}
+                  precision={2}
+                  step={0.1}
+                />
+              </div>
+            )}
+          </div>
+
+          {/* Dimensions (effective, read-only) */}
           <div className="space-y-2">
             <label className="font-medium text-muted-foreground text-xs uppercase tracking-wide">
               Dimensions
             </label>
             <div className="rounded border border-border bg-muted/50 px-3 py-2 text-sm">
-              {node.asset.dimensions[0]}m × {node.asset.dimensions[1]}m × {node.asset.dimensions[2]}m
+              {(() => {
+                const [w, h, d] = getScaledDimensions(node)
+                return `${Math.round(w * 100) / 100}m × ${Math.round(h * 100) / 100}m × ${Math.round(d * 100) / 100}m`
+              })()}
             </div>
           </div>
         </div>
diff --git a/packages/core/src/hooks/spatial-grid/spatial-grid-manager.ts b/packages/core/src/hooks/spatial-grid/spatial-grid-manager.ts
index 8138efe9..ebd5e6a9 100644
--- a/packages/core/src/hooks/spatial-grid/spatial-grid-manager.ts
+++ b/packages/core/src/hooks/spatial-grid/spatial-grid-manager.ts
@@ -1,3 +1,4 @@
+import { getScaledDimensions } from '../../schema'
 import type { AnyNode, CeilingNode, ItemNode, SlabNode, WallNode } from '../../schema'
 import { SpatialGrid } from './spatial-grid'
 import { WallSpatialGrid } from './wall-spatial-grid'
@@ -183,11 +184,24 @@ export function wallOverlapsPolygon(
   end: [number, number],
   polygon: Array<[number, number]>,
 ): boolean {
-  const startInside = pointInPolygon(start[0], start[1], polygon)
-  const endInside = pointInPolygon(end[0], end[1], polygon)
+  const dx = end[0] - start[0]
+  const dz = end[1] - start[1]
+  const len = Math.sqrt(dx * dx + dz * dz)
 
-  // At least one endpoint strictly inside the polygon
-  if (startInside || endInside) return true
+  // Nudge endpoint test points a tiny step inward along the wall direction before
+  // testing containment. pointInPolygon (ray casting) produces false positives for
+  // points exactly on polygon vertices or edges — specifically the minimum-z corner
+  // of an axis-aligned polygon returns "inside" because the ray hits the opposite
+  // vertical edge exactly at its base. Nudging by 1e-6 m avoids this: a wall that
+  // merely starts at a slab corner and extends outward will have its nudged point
+  // clearly outside, while a wall that genuinely starts inside stays inside.
+  if (len > 1e-10) {
+    const step = Math.min(1e-6, len * 0.01)
+    const nx = (dx / len) * step
+    const nz = (dz / len) * step
+    if (pointInPolygon(start[0] + nx, start[1] + nz, polygon)) return true
+    if (pointInPolygon(end[0] - nx, end[1] - nz, polygon)) return true
+  }
 
   // Check if midpoint is inside (catches walls crossing through)
   const midX = (start[0] + end[0]) / 2
@@ -278,7 +292,7 @@ export class SpatialGridManager {
         if (wallId && this.walls.has(wallId)) {
           const wallLength = this.getWallLength(wallId)
           if (wallLength > 0) {
-            const [width, height] = item.asset.dimensions
+            const [width, height] = getScaledDimensions(item)
             const halfW = width / wallLength / 2
             // Calculate t from local X position (position[0] is distance along wall)
             const t = item.position[0] / wallLength
@@ -299,7 +313,7 @@ export class SpatialGridManager {
         // Ceiling item - use parentId as the ceiling ID
         const ceilingId = item.parentId
         if (ceilingId && this.ceilings.has(ceilingId)) {
-          this.getCeilingGrid(ceilingId).insert(item.id, item.position, item.asset.dimensions, item.rotation)
+          this.getCeilingGrid(ceilingId).insert(item.id, item.position, getScaledDimensions(item), item.rotation)
           this.itemCeilingMap.set(item.id, ceilingId)
         }
       } else if (!item.asset.attachTo) {
@@ -307,7 +321,7 @@ export class SpatialGridManager {
         this.getFloorGrid(levelId).insert(
           item.id,
           item.position,
-          item.asset.dimensions,
+          getScaledDimensions(item),
           item.rotation,
         )
       }
@@ -331,7 +345,7 @@ export class SpatialGridManager {
         if (wallId && this.walls.has(wallId)) {
           const wallLength = this.getWallLength(wallId)
           if (wallLength > 0) {
-            const [width, height] = item.asset.dimensions
+            const [width, height] = getScaledDimensions(item)
             const halfW = width / wallLength / 2
             // Calculate t from local X position (position[0] is distance along wall)
             const t = item.position[0] / wallLength
@@ -358,14 +372,14 @@ export class SpatialGridManager {
         // Insert into new ceiling grid
         const ceilingId = item.parentId
         if (ceilingId && this.ceilings.has(ceilingId)) {
-          this.getCeilingGrid(ceilingId).insert(item.id, item.position, item.asset.dimensions, item.rotation)
+          this.getCeilingGrid(ceilingId).insert(item.id, item.position, getScaledDimensions(item), item.rotation)
           this.itemCeilingMap.set(item.id, ceilingId)
         }
       } else if (!item.asset.attachTo) {
         this.getFloorGrid(levelId).update(
           item.id,
           item.position,
-          item.asset.dimensions,
+          getScaledDimensions(item),
           item.rotation,
         )
       }
diff --git a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
index d978403a..9566159e 100644
--- a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
+++ b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
@@ -1,4 +1,4 @@
-import type { AnyNode, AnyNodeId, ItemNode, SlabNode, WallNode } from '../../schema'
+import { getScaledDimensions, type AnyNode, type AnyNodeId, type ItemNode, type SlabNode, type WallNode } from '../../schema'
 import useScene from '../../store/use-scene'
 import { itemOverlapsPolygon, spatialGridManager, wallOverlapsPolygon } from './spatial-grid-manager'
 
@@ -73,11 +73,16 @@ export function initSpatialGridSync() {
         if (
           !arraysEqual(node.position, prev.position) ||
           !arraysEqual(node.rotation, prev.rotation) ||
+          !arraysEqual(node.scale, prev.scale) ||
           node.parentId !== prev.parentId ||
           node.side !== prev.side
         ) {
           const levelId = resolveLevelId(node, state.nodes)
           spatialGridManager.handleNodeUpdated(node, levelId)
+          // Scale changes affect footprint size — mark dirty so slab elevation recalculates
+          if (!arraysEqual(node.scale, prev.scale)) {
+            markDirty(node.id)
+          }
         }
       } else if (node.type === 'slab' && prev.type === 'slab') {
         if (node.polygon !== prev.polygon || node.elevation !== prev.elevation) {
@@ -114,7 +119,7 @@ function markNodesOverlappingSlab(
       // Only floor items are affected by slabs
       if (item.asset.attachTo) continue
       if (resolveLevelId(node, nodes) !== slabLevelId) continue
-      if (itemOverlapsPolygon(item.position, item.asset.dimensions, item.rotation, slab.polygon, 0.01)) {
+      if (itemOverlapsPolygon(item.position, getScaledDimensions(item), item.rotation, slab.polygon, 0.01)) {
         markDirty(node.id)
       }
     } else if (node.type === 'wall') {
diff --git a/packages/core/src/schema/index.ts b/packages/core/src/schema/index.ts
index 934e89e1..84b4b5d0 100644
--- a/packages/core/src/schema/index.ts
+++ b/packages/core/src/schema/index.ts
@@ -3,7 +3,7 @@ export { BaseNode, generateId, Material, nodeType, objectId } from './base'
 // Camera
 export { CameraSchema } from './camera'
 export type { AssetInput } from './nodes/item'
-export { ItemNode } from './nodes/item'
+export { getScaledDimensions, ItemNode } from './nodes/item'
 export { LevelNode } from './nodes/level'
 // Nodes
 export { SiteNode } from './nodes/site'
diff --git a/packages/core/src/schema/nodes/item.ts b/packages/core/src/schema/nodes/item.ts
index 949b2a91..bda8f4c5 100644
--- a/packages/core/src/schema/nodes/item.ts
+++ b/packages/core/src/schema/nodes/item.ts
@@ -30,6 +30,7 @@ export const ItemNode = BaseNode.extend({
   type: nodeType('item'),
   position: z.tuple([z.number(), z.number(), z.number()]).default([0, 0, 0]),
   rotation: z.tuple([z.number(), z.number(), z.number()]).default([0, 0, 0]),
+  scale: z.tuple([z.number(), z.number(), z.number()]).default([1, 1, 1]),
   side: z.enum(['front', 'back']).optional(),
   children: z.array(objectId('item')).default([]),
 
@@ -53,3 +54,13 @@ export const ItemNode = BaseNode.extend({
 `)
 
 export type ItemNode = z.infer<typeof ItemNode>
+
+/**
+ * Returns the effective world-space dimensions of an item after applying its scale.
+ * Use this everywhere item.asset.dimensions is used for spatial calculations.
+ */
+export function getScaledDimensions(item: ItemNode): [number, number, number] {
+  const [w, h, d] = item.asset.dimensions
+  const [sx, sy, sz] = item.scale
+  return [w * sx, h * sy, d * sz]
+}
diff --git a/packages/core/src/store/use-scene.ts b/packages/core/src/store/use-scene.ts
index d1db3812..3a970b79 100644
--- a/packages/core/src/store/use-scene.ts
+++ b/packages/core/src/store/use-scene.ts
@@ -68,13 +68,21 @@ const useScene: UseSceneStore = create<SceneState>()(
         },
 
         setScene: (nodes, rootNodeIds) => {
+          // Backward compat: add default scale to item nodes loaded from external sources
+          // (pascal_local_projects, Supabase) saved before scale was added to ItemNode
+          const patchedNodes = { ...nodes }
+          for (const [id, node] of Object.entries(patchedNodes)) {
+            if (node.type === 'item' && !('scale' in node)) {
+              patchedNodes[id as AnyNodeId] = { ...(node as object), scale: [1, 1, 1] } as AnyNode
+            }
+          }
           set({
-            nodes,
+            nodes: patchedNodes,
             rootNodeIds,
             dirtyNodes: new Set<AnyNodeId>(),
           })
           // Mark all nodes as dirty to trigger re-validation
-          Object.values(nodes).forEach((node) => {
+          Object.values(patchedNodes).forEach((node) => {
             get().markDirty(node.id)
           })
         },
@@ -146,6 +154,7 @@ const useScene: UseSceneStore = create<SceneState>()(
     ),
     {
       name: 'editor-storage',
+      version: 1,
       partialize: (state) => ({
         nodes: Object.fromEntries(
           Object.entries(state.nodes).filter(([_, node]) => {
@@ -157,6 +166,19 @@ const useScene: UseSceneStore = create<SceneState>()(
         ),
         rootNodeIds: state.rootNodeIds,
       }),
+      merge: (persistedState, currentState) => {
+        console.log('merge calling...', persistedState, currentState)
+        const persisted = persistedState as Partial<SceneState>
+        // Backward compat: add default scale to item nodes saved before scale was added
+        if (persisted.nodes) {
+          for (const [id, node] of Object.entries(persisted.nodes)) {
+            if (node.type === 'item' && !('scale' in node)) {
+              persisted.nodes[id as AnyNodeId] = { ...(node as object), scale: [1, 1, 1] } as AnyNode
+            }
+          }
+        }
+        return { ...currentState, ...persisted }
+      },
       onRehydrateStorage: (state) => {
         console.log('hydrating...')
 
diff --git a/packages/core/src/systems/item/item-system.tsx b/packages/core/src/systems/item/item-system.tsx
index 5a70bacc..b2876c29 100644
--- a/packages/core/src/systems/item/item-system.tsx
+++ b/packages/core/src/systems/item/item-system.tsx
@@ -3,7 +3,7 @@ import type * as THREE from 'three'
 import { sceneRegistry } from '../../hooks/scene-registry/scene-registry'
 import { spatialGridManager } from '../../hooks/spatial-grid/spatial-grid-manager'
 import { resolveLevelId } from '../../hooks/spatial-grid/spatial-grid-sync'
-import type { AnyNodeId, ItemNode, WallNode } from '../../schema'
+import { getScaledDimensions, type AnyNodeId, type ItemNode, type WallNode } from '../../schema'
 import useScene from '../../store/use-scene'
 
 // ============================================================================
@@ -43,7 +43,7 @@ export const ItemSystem = () => {
           const slabElevation = spatialGridManager.getSlabElevationForItem(
             levelId,
             item.position,
-            item.asset.dimensions,
+            getScaledDimensions(item),
             item.rotation,
           )
           mesh.position.y = slabElevation + item.position[1]
@@ -51,7 +51,7 @@ export const ItemSystem = () => {
       }
 
       clearDirty(id as AnyNodeId)
-    })
+    }, 2)
   })
 
   return null
diff --git a/packages/core/src/systems/slab/slab-system.tsx b/packages/core/src/systems/slab/slab-system.tsx
index 29a2c8b6..29aae139 100644
--- a/packages/core/src/systems/slab/slab-system.tsx
+++ b/packages/core/src/systems/slab/slab-system.tsx
@@ -29,7 +29,7 @@ export const SlabSystem = () => {
       }
       // If mesh not found, keep it dirty for next frame
     })
-  })
+  }, 1)
 
   return null
 }
diff --git a/packages/core/src/systems/wall/wall-system.tsx b/packages/core/src/systems/wall/wall-system.tsx
index 13589518..e741519a 100644
--- a/packages/core/src/systems/wall/wall-system.tsx
+++ b/packages/core/src/systems/wall/wall-system.tsx
@@ -1,7 +1,7 @@
 import { useFrame } from '@react-three/fiber'
 import * as THREE from 'three'
-import { computeBoundsTree } from 'three-mesh-bvh'
 import { Brush, Evaluator, SUBTRACTION } from 'three-bvh-csg'
+import { computeBoundsTree } from 'three-mesh-bvh'
 import { sceneRegistry } from '../../hooks/scene-registry/scene-registry'
 import { spatialGridManager } from '../../hooks/spatial-grid/spatial-grid-manager'
 import { resolveLevelId } from '../../hooks/spatial-grid/spatial-grid-sync'
@@ -22,7 +22,7 @@ const csgEvaluator = new Evaluator()
 // WALL SYSTEM
 // ============================================================================
 
-let useFrameNb = 0;
+let useFrameNb = 0
 export const WallSystem = () => {
   const dirtyNodes = useScene((state) => state.dirtyNodes)
   const clearDirty = useScene((state) => state.clearDirty)
@@ -35,7 +35,7 @@ export const WallSystem = () => {
     // Collect dirty walls and their levels
     const dirtyWallsByLevel = new Map<string, Set<string>>()
 
-    useFrameNb += 1;    
+    useFrameNb += 1
     dirtyNodes.forEach((id) => {
       const node = nodes[id]
       if (!node || node.type !== 'wall') return
@@ -75,7 +75,7 @@ export const WallSystem = () => {
         }
       }
     }
-  })
+  }, 4)
 
   return null
 }
@@ -108,7 +108,6 @@ function updateWallGeometry(wallId: string, miterData: WallMiterData) {
   const node = nodes[wallId as WallNode['id']]
   if (!node || node.type !== 'wall') return
 
-
   const mesh = sceneRegistry.nodes.get(wallId) as THREE.Mesh
   if (!mesh) return
 
diff --git a/packages/core/src/systems/window/window-system.tsx b/packages/core/src/systems/window/window-system.tsx
index 57180af5..c533dd2b 100644
--- a/packages/core/src/systems/window/window-system.tsx
+++ b/packages/core/src/systems/window/window-system.tsx
@@ -50,7 +50,7 @@ export const WindowSystem = () => {
         useScene.getState().dirtyNodes.add((node as WindowNode).parentId as AnyNodeId)
       }
     })
-  })
+  }, 3)
 
   return null
 }
diff --git a/packages/viewer/src/components/renderers/item/item-renderer.tsx b/packages/viewer/src/components/renderers/item/item-renderer.tsx
index 7b3156da..60f6a731 100644
--- a/packages/viewer/src/components/renderers/item/item-renderer.tsx
+++ b/packages/viewer/src/components/renderers/item/item-renderer.tsx
@@ -73,6 +73,9 @@ const PreviewModel = ({ node }: { node: ItemNode }) => {
   )
 }
 
+const multiplyScales = (a: [number, number, number], b: [number, number, number]): [number, number, number] => 
+  [a[0] * b[0], a[1] * b[1], a[2] * b[2]]
+
 const ModelRenderer = ({ node }: { node: ItemNode }) => {
   const { scene, nodes } = useGLTF(resolveCdnUrl(node.asset.src) || '')
 
@@ -115,7 +118,7 @@ const ModelRenderer = ({ node }: { node: ItemNode }) => {
   return (
     <Clone
       object={scene}
-      scale={node.asset.scale}
+      scale={multiplyScales(node.asset.scale, node.scale)}
       position={node.asset.offset}
       rotation={node.asset.rotation}
       {...handlers}
diff --git a/packages/viewer/src/systems/level/level-system.tsx b/packages/viewer/src/systems/level/level-system.tsx
index dcc047a8..f6a9bfd3 100644
--- a/packages/viewer/src/systems/level/level-system.tsx
+++ b/packages/viewer/src/systems/level/level-system.tsx
@@ -33,7 +33,10 @@ function getLevelHeight(
     } else if (child.type === 'wall') {
       // Wall mesh is pushed up to slabElevation by WallSystem.
       // mesh.position.y + wall.height gives the actual top Y in level-local space.
-      const meshY = sceneRegistry.nodes.get(childId as any)?.position.y ?? 0
+      let meshY = sceneRegistry.nodes.get(childId as any)?.position.y ?? 0
+      if (meshY < 0) {
+        meshY = 0 // Guard against invalid negative Y which could cause incorrect height calculation (e.g. from sunken slabs)
+      }
       const top = meshY + ((child as WallNode).height ?? DEFAULT_LEVEL_HEIGHT)
       if (top > maxTop) maxTop = top
     }
@@ -78,11 +81,11 @@ export const LevelSystem = () => {
       const explodedExtra = levelMode === 'exploded' ? index * EXPLODED_GAP : 0
       const targetY = baseY + explodedExtra
 
-      obj.position.y = lerp(obj.position.y, targetY, delta * 3)
+      obj.position.y = lerp(obj.position.y, targetY, delta * 12) // Smoothly animate to new Y position
       obj.visible = levelMode !== 'solo' || level?.id === selectedLevel || !selectedLevel
 
       cumulativeY += getLevelHeight(levelId, nodes)
     }
-  })
+  }, 5) // Using a lower priority so it runs after transforms from other systems have settled
   return null
 }