diff --git a/apps/editor/components/build-tab.tsx b/apps/editor/components/build-tab.tsx
index 48552e55d..175f3c8ab 100644
--- a/apps/editor/components/build-tab.tsx
+++ b/apps/editor/components/build-tab.tsx
@@ -26,6 +26,7 @@ type BuildToolKind =
   | 'door'
   | 'window'
   | 'column'
+  | 'shelf'
   | 'spawn'
 
 type BuildType = {
@@ -51,6 +52,7 @@ const BUILD_TYPES: BuildType[] = [
   { id: 'door', label: 'Door', iconSrc: '/icons/door.png', kind: 'door' },
   { id: 'window', label: 'Window', iconSrc: '/icons/window.png', kind: 'window' },
   { id: 'column', label: 'Column', iconSrc: '/icons/column.png', kind: 'column' },
+  { id: 'shelf', label: 'Shelf', iconSrc: '/icons/shelf.png', kind: 'shelf' },
   { id: 'spawn', label: 'Spawn Point', iconSrc: '/icons/site.png', kind: 'spawn' },
   { id: 'painting', label: 'Painting', iconSrc: '/icons/paint.png', mode: 'material-paint' },
 ]
diff --git a/packages/core/src/registry/types.ts b/packages/core/src/registry/types.ts
index b498bd9fd..cc8a792ee 100644
--- a/packages/core/src/registry/types.ts
+++ b/packages/core/src/registry/types.ts
@@ -675,6 +675,20 @@ export type NodeDefinition<S extends ZodObject<any>> = {
    * work (animations, named-mesh material poking).
    */
   geometry?: (node: z.infer<S>, ctx: GeometryContext) => Object3D
+  /**
+   * Optional cache key over the geometry-relevant inputs of `node`. When
+   * set, `<GeometrySystem>` skips the rebuild (dispose + re-create the
+   * group's children) if the key is unchanged since the last build for
+   * this node — even though the node was marked dirty. Use for kinds whose
+   * geometry depends *only* on their own fields (not on `children`,
+   * `position`, neighbours, or `ctx`): a hosted child reparenting onto a
+   * shelf, say, dirties the shelf but doesn't change its boards, so without
+   * this the boards needlessly remount and any pointer hover churns
+   * (enter/leave) as the meshes are swapped. Must NOT be set for kinds with
+   * neighbour-dependent geometry (e.g. wall/fence miters via `ctx`), whose
+   * inputs aren't captured by the node alone.
+   */
+  geometryKey?: (node: z.infer<S>) => string
   /**
    * Level-batch precompute hook. Called by `<GeometrySystem>` once per
    * level per frame, **before** the per-node `def.geometry` calls in
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 3b90fb6e4..8df958c78 100644
--- a/packages/editor/src/components/tools/item/use-placement-coordinator.tsx
+++ b/packages/editor/src/components/tools/item/use-placement-coordinator.tsx
@@ -18,15 +18,19 @@ import {
 } from '@pascal-app/core'
 import { useViewer } from '@pascal-app/viewer'
 import { Html } from '@react-three/drei'
-import { useFrame } from '@react-three/fiber'
+import { useFrame, useThree } from '@react-three/fiber'
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import {
+  Box3,
   Euler,
   type Group,
   type LineSegments,
+  Matrix4,
   type Mesh,
+  type Object3D,
   PlaneGeometry,
   Quaternion,
+  Ray,
   Vector3,
 } from 'three'
 import { distance, smoothstep, uv, vec2 } from 'three/tsl'
@@ -196,8 +200,24 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
   // the lerp on this flag keeps 3D placement smooth without hijacking
   // 2D drags that share the same draft.
   const has3DPointerDrivenMoveRef = useRef(false)
+  // The draft mesh's raycast is disabled while placing so the cursor ray
+  // passes through it to the surface beneath (grid / item / shelf). Without
+  // this, the ray hits the moving draft first and the surface strategy keeps
+  // re-deriving the host point from the draft's own (just-moved) geometry —
+  // on a multi-row shelf this oscillates the chosen row, jittering the item.
+  // Mirrors MoveRegistryNodeTool. Reconciled per-frame (the draft mesh can be
+  // recreated mid-session) and restored on unmount.
+  const raycastDisabledMeshRef = useRef<Object3D | null>(null)
+  const restoreRaycastsRef = useRef<Array<() => void>>([])
+  const raycastDisabledChildrenRef = useRef(new WeakSet<Object3D>())
   const [dimensionBounds, setDimensionBounds] = useState<PreviewBounds | null>(null)
 
+  // Live camera ref — the shelf-stickiness test reconstructs the cursor world
+  // ray (camera → grid hit) to check it still points at the shelf volume.
+  const camera = useThree((s) => s.camera)
+  const cameraRef = useRef(camera)
+  cameraRef.current = camera
+
   // Store config callbacks in refs to avoid re-running effect when they change
   const configRef = useRef(config)
   configRef.current = config
@@ -487,6 +507,50 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
 
     let previousGridPos: [number, number, number] | null = null
 
+    // Scratch objects reused by the stickiness test (runs per grid:move).
+    const stickyRay = new Ray()
+    const stickyBox = new Box3()
+    const stickyMat = new Matrix4()
+    const stickyCamPos = new Vector3()
+
+    // True while the cursor ray still points at the active shelf's volume.
+    // Used to keep an item hosted on a shelf "sticky": from an angled camera
+    // the cursor ray slips off the shelf's thin boards / through its gaps and
+    // lands on the floor *behind* the shelf, which would otherwise thrash the
+    // placement between the shelf row and the floor on every micro-move. We
+    // reconstruct the world ray (camera → grid hit point) and test it against
+    // the shelf's bounding box — so a ray that passes *through* the shelf but
+    // lands behind it still counts as "on the shelf". Only a ray that misses
+    // the shelf box entirely means the user genuinely moved off it. A simple
+    // footprint test on the floor hit point can't distinguish those.
+    const cursorRayIntersectsActiveShelf = (gridWorldPoint: [number, number, number]): boolean => {
+      const shelfId = placementState.current.shelfId
+      if (!shelfId) return false
+      const shelfMesh = sceneRegistry.nodes.get(shelfId as AnyNodeId)
+      const shelfNode = useScene.getState().nodes[shelfId as AnyNodeId] as
+        | { width?: number; depth?: number; height?: number }
+        | undefined
+      if (!(shelfMesh && shelfNode?.width && shelfNode?.depth && shelfNode?.height)) return false
+
+      cameraRef.current.getWorldPosition(stickyCamPos)
+      stickyRay.origin.copy(stickyCamPos)
+      stickyRay.direction
+        .set(
+          gridWorldPoint[0] - stickyCamPos.x,
+          gridWorldPoint[1] - stickyCamPos.y,
+          gridWorldPoint[2] - stickyCamPos.z,
+        )
+        .normalize()
+
+      // Into shelf-local space, then test the shelf's local AABB (origin at the
+      // base: y ∈ [0, height]) with a small margin.
+      stickyRay.applyMatrix4(stickyMat.copy(shelfMesh.matrixWorld).invert())
+      const m = 0.08
+      stickyBox.min.set(-shelfNode.width / 2 - m, -m, -shelfNode.depth / 2 - m)
+      stickyBox.max.set(shelfNode.width / 2 + m, shelfNode.height + m, shelfNode.depth / 2 + m)
+      return stickyRay.intersectsBox(stickyBox)
+    }
+
     const onGridMove = (event: GridEvent) => {
       // Lazy draft creation: if no draft yet (e.g. level wasn't ready during init), create now
       if (draftNode.current === null && asset.attachTo === undefined) {
@@ -494,6 +558,17 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
       }
 
       has3DPointerDrivenMoveRef.current = true
+
+      // Shelf stickiness: while hosting on a shelf, ignore floor events while
+      // the cursor ray still points at the shelf volume (the ray merely slipped
+      // off a board / through a gap and hit the floor behind). Detach to the
+      // floor only once the ray misses the shelf entirely — without this the
+      // item oscillates between the shelf row and the floor on every micro-move.
+      if (placementState.current.surface === 'shelf-surface') {
+        if (cursorRayIntersectsActiveShelf(event.position)) return
+        detachItemSurfaceToFloor(event as unknown as ItemEvent)
+      }
+
       lastRawPos.current.set(event.localPosition[0], event.localPosition[1], event.localPosition[2])
       if (!cursorGroupRef.current) return
       const result = floorStrategy.move(getContext(), event)
@@ -774,7 +849,11 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
       const wz = Math.round(buildingLocalPoint.z * 2) / 2
       const floorPos: [number, number, number] = [wx, 0, wz]
 
-      Object.assign(placementState.current, { surface: 'floor', surfaceItemId: null })
+      Object.assign(placementState.current, {
+        surface: 'floor',
+        surfaceItemId: null,
+        shelfId: null,
+      })
       gridPosition.current.set(wx, 0, wz)
       if (cursorGroupRef.current) {
         cursorGroupRef.current.position.set(wx, 0, wz)
@@ -1212,11 +1291,14 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     const onShelfLeave = (event: ShelfEvent) => {
       if (placementState.current.surface !== 'shelf-surface') return
       if (event.node.id !== placementState.current.shelfId) return
+      // Intentionally do NOT detach to the floor here. `shelf:leave` fires
+      // constantly while hosting because the cursor ray slips off the shelf's
+      // thin boards and through its gaps — detaching on each of those would
+      // thrash the item between the shelf row and the floor. The grid handler
+      // owns the real shelf→floor transition (see `isOverActiveShelfFootprint`
+      // in `onGridMove`): it detaches only once the cursor is clearly off the
+      // shelf footprint, which is the genuine "left the shelf" signal.
       event.stopPropagation()
-      // Drop back to floor — same pattern as item-leave but without the
-      // detachItemSurfaceToFloor (no scaled rotation hand-off to deal
-      // with since the shelf rotation already composed cleanly).
-      Object.assign(placementState.current, { surface: 'floor', shelfId: null })
     }
 
     const onShelfClick = (event: ShelfEvent) => {
@@ -1496,9 +1578,51 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     useScene.getState().updateNode(draft.id as AnyNodeId, { parentId: viewerLevelId })
   }, [viewerLevelId, draftNode, asset])
 
+  // Disable raycasting on the live draft mesh (and restore it when the draft
+  // changes or goes away) so the cursor ray passes through the item being
+  // moved and lands on the surface beneath it.
+  const reconcileDraftRaycast = useCallback((mesh: Object3D | null) => {
+    if (raycastDisabledMeshRef.current !== mesh) {
+      // New draft root (or cleared): restore the prior mesh and reset tracking.
+      for (const restore of restoreRaycastsRef.current) restore()
+      restoreRaycastsRef.current = []
+      raycastDisabledChildrenRef.current = new WeakSet()
+      raycastDisabledMeshRef.current = mesh
+    }
+    if (!mesh) return
+    // Disable any descendant not handled yet. Item drafts are GLB models whose
+    // child meshes mount asynchronously (Suspense), so a one-shot traverse
+    // misses them — those late children keep intercepting the ray and corrupt
+    // the shelf-row hit the moment the item moves onto a row. Re-walking each
+    // frame is cheap: the WeakSet makes it idempotent, so only new children pay.
+    mesh.traverse((child) => {
+      if (raycastDisabledChildrenRef.current.has(child)) return
+      raycastDisabledChildrenRef.current.add(child)
+      const original = child.raycast
+      child.raycast = () => {}
+      restoreRaycastsRef.current.push(() => {
+        child.raycast = original
+      })
+    })
+  }, [])
+
+  // Restore the draft mesh's raycast when the coordinator unmounts (tool change).
+  useEffect(() => () => reconcileDraftRaycast(null), [reconcileDraftRaycast])
+
   useFrame((_, delta) => {
-    if (!asset) return
-    if (!draftNode.current) return
+    if (!asset) {
+      reconcileDraftRaycast(null)
+      return
+    }
+    if (!draftNode.current) {
+      reconcileDraftRaycast(null)
+      return
+    }
+    const mesh = sceneRegistry.nodes.get(draftNode.current.id) ?? null
+    reconcileDraftRaycast(mesh)
+    // mitt listeners outlive the cursor group's mount; bail if it's gone
+    // (mount/teardown race, #323). Placed after reconcileDraftRaycast so the
+    // draft's raycast is still restored during that window.
     if (!cursorGroupRef.current) return
     // The mesh-position lerp below only makes sense once this coordinator
     // owns the move via a 3D pointer event. Skip until then so that
@@ -1506,7 +1630,6 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
     // writing scene.position directly) aren't fought by useFrame pulling
     // the mesh back to its pre-move location.
     if (!has3DPointerDrivenMoveRef.current) return
-    const mesh = sceneRegistry.nodes.get(draftNode.current.id)
     if (!mesh) return
 
     // Hide wall/ceiling-attached items when between surfaces (only cursor visible)
diff --git a/packages/mcp/examples/coordinate-conventions-demo.json b/packages/mcp/examples/coordinate-conventions-demo.json
index e4026897a..af2de3a9a 100644
--- a/packages/mcp/examples/coordinate-conventions-demo.json
+++ b/packages/mcp/examples/coordinate-conventions-demo.json
@@ -6,24 +6,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          18,
-          0
-        ],
-        [
-          24,
-          0
-        ],
-        [
-          24,
-          4
-        ],
-        [
-          18,
-          4
-        ]
-      ],
+      "polygon": [[18, 0], [24, 0], [24, 4], [18, 4]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -37,24 +20,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          18,
-          10
-        ],
-        [
-          23.195999999999998,
-          13
-        ],
-        [
-          21.196,
-          16.464
-        ],
-        [
-          16,
-          13.464
-        ]
-      ],
+      "polygon": [[18, 10], [23.195999999999998, 13], [21.196, 16.464], [16, 13.464]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -68,24 +34,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          -0.3,
-          -0.3
-        ],
-        [
-          0.3,
-          -0.3
-        ],
-        [
-          0.3,
-          0.3
-        ],
-        [
-          -0.3,
-          0.3
-        ]
-      ],
+      "polygon": [[-0.3, -0.3], [0.3, -0.3], [0.3, 0.3], [-0.3, 0.3]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -100,29 +49,10 @@
       "object": "node",
       "polygon": {
         "type": "polygon",
-        "points": [
-          [
-            -6,
-            -12
-          ],
-          [
-            44,
-            -12
-          ],
-          [
-            44,
-            40
-          ],
-          [
-            -6,
-            40
-          ]
-        ]
+        "points": [[-6, -12], [44, -12], [44, 40], [-6, 40]]
       },
       "visible": true,
-      "children": [
-        "building_conv_demo"
-      ],
+      "children": ["building_conv_demo"],
       "metadata": {},
       "parentId": null
     },
@@ -214,24 +144,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          -2.5,
-          -0.06
-        ],
-        [
-          0,
-          -0.06
-        ],
-        [
-          0,
-          0.06
-        ],
-        [
-          -2.5,
-          0.06
-        ]
-      ],
+      "polygon": [[-2.5, -0.06], [0, -0.06], [0, 0.06], [-2.5, 0.06]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -245,24 +158,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          -0.06,
-          -2.5
-        ],
-        [
-          0.06,
-          -2.5
-        ],
-        [
-          0.06,
-          0
-        ],
-        [
-          -0.06,
-          0
-        ]
-      ],
+      "polygon": [[-0.06, -2.5], [0.06, -2.5], [0.06, 0], [-0.06, 0]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -276,24 +172,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          0,
-          -0.06
-        ],
-        [
-          12,
-          -0.06
-        ],
-        [
-          12,
-          0.06
-        ],
-        [
-          0,
-          0.06
-        ]
-      ],
+      "polygon": [[0, -0.06], [12, -0.06], [12, 0.06], [0, 0.06]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -307,20 +186,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          12,
-          -0.4
-        ],
-        [
-          12.9,
-          0
-        ],
-        [
-          12,
-          0.4
-        ]
-      ],
+      "polygon": [[12, -0.4], [12.9, 0], [12, 0.4]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -334,24 +200,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          -0.06,
-          0
-        ],
-        [
-          0.06,
-          0
-        ],
-        [
-          0.06,
-          12
-        ],
-        [
-          -0.06,
-          12
-        ]
-      ],
+      "polygon": [[-0.06, 0], [0.06, 0], [0.06, 12], [-0.06, 12]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -365,20 +214,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          -0.4,
-          12
-        ],
-        [
-          0.4,
-          12
-        ],
-        [
-          0,
-          12.9
-        ]
-      ],
+      "polygon": [[-0.4, 12], [0.4, 12], [0, 12.9]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -392,24 +228,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          20.7,
-          1.3
-        ],
-        [
-          21.3,
-          1.3
-        ],
-        [
-          21.3,
-          1.9000000000000001
-        ],
-        [
-          20.7,
-          1.9000000000000001
-        ]
-      ],
+      "polygon": [[20.7, 1.3], [21.3, 1.3], [21.3, 1.9000000000000001], [20.7, 1.9000000000000001]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -421,22 +240,10 @@
       "color": "#f0f0f0",
       "object": "node",
       "polygon": [
-        [
-          13.299999999999999,
-          -1.3
-        ],
-        [
-          13.9,
-          -1.3
-        ],
-        [
-          13.9,
-          -0.7
-        ],
-        [
-          13.299999999999999,
-          -0.7
-        ]
+        [13.299999999999999, -1.3],
+        [13.9, -1.3],
+        [13.9, -0.7],
+        [13.299999999999999, -0.7]
       ],
       "visible": true,
       "metadata": {},
@@ -449,22 +256,10 @@
       "color": "#f0f0f0",
       "object": "node",
       "polygon": [
-        [
-          -1.3,
-          13.299999999999999
-        ],
-        [
-          -0.7,
-          13.299999999999999
-        ],
-        [
-          -0.7,
-          13.9
-        ],
-        [
-          -1.3,
-          13.9
-        ]
+        [-1.3, 13.299999999999999],
+        [-0.7, 13.299999999999999],
+        [-0.7, 13.9],
+        [-1.3, 13.9]
       ],
       "visible": true,
       "metadata": {},
@@ -476,24 +271,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          1.2,
-          1.2
-        ],
-        [
-          1.8,
-          1.2
-        ],
-        [
-          1.8,
-          1.8
-        ],
-        [
-          1.2,
-          1.8
-        ]
-      ],
+      "polygon": [[1.2, 1.2], [1.8, 1.2], [1.8, 1.8], [1.2, 1.8]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -504,24 +282,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          2.7,
-          32.7
-        ],
-        [
-          3.3,
-          32.7
-        ],
-        [
-          3.3,
-          33.3
-        ],
-        [
-          2.7,
-          33.3
-        ]
-      ],
+      "polygon": [[2.7, 32.7], [3.3, 32.7], [3.3, 33.3], [2.7, 33.3]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -532,24 +293,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          2.7,
-          33.5
-        ],
-        [
-          3.3,
-          33.5
-        ],
-        [
-          3.3,
-          34.099999999999994
-        ],
-        [
-          2.7,
-          34.099999999999994
-        ]
-      ],
+      "polygon": [[2.7, 33.5], [3.3, 33.5], [3.3, 34.099999999999994], [2.7, 34.099999999999994]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -560,24 +304,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          2.7,
-          34.300000000000004
-        ],
-        [
-          3.3,
-          34.300000000000004
-        ],
-        [
-          3.3,
-          34.9
-        ],
-        [
-          2.7,
-          34.9
-        ]
-      ],
+      "polygon": [[2.7, 34.300000000000004], [3.3, 34.300000000000004], [3.3, 34.9], [2.7, 34.9]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -588,24 +315,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          2.7,
-          35.1
-        ],
-        [
-          3.3,
-          35.1
-        ],
-        [
-          3.3,
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       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          -2.3,
-          0.7
-        ],
-        [
-          -1.7,
-          0.7
-        ],
-        [
-          -1.7,
-          1.3
-        ],
-        [
-          -2.3,
-          1.3
-        ]
-      ],
+      "polygon": [[-2.3, 0.7], [-1.7, 0.7], [-1.7, 1.3], [-2.3, 1.3]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -1634,24 +744,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          0.7,
-          -2.3
-        ],
-        [
-          1.3,
-          -2.3
-        ],
-        [
-          1.3,
-          -1.7
-        ],
-        [
-          0.7,
-          -1.7
-        ]
-      ],
+      "polygon": [[0.7, -2.3], [1.3, -2.3], [1.3, -1.7], [0.7, -1.7]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -1663,22 +756,10 @@
       "color": "#f0f0f0",
       "object": "node",
       "polygon": [
-        [
-          33.7,
-          27.3
-        ],
-        [
-          34.3,
-          27.3
-        ],
-        [
-          34.3,
-          27.900000000000002
-        ],
-        [
-          33.7,
-          27.900000000000002
-        ]
+        [33.7, 27.3],
+        [34.3, 27.3],
+        [34.3, 27.900000000000002],
+        [33.7, 27.900000000000002]
       ],
       "visible": true,
       "metadata": {},
@@ -1691,22 +772,10 @@
       "color": "#f0f0f0",
       "object": "node",
       "polygon": [
-        [
-          33.7,
-          28.099999999999998
-        ],
-        [
-          34.3,
-          28.099999999999998
-        ],
-        [
-          34.3,
-          28.7
-        ],
-        [
-          33.7,
-          28.7
-        ]
+        [33.7, 28.099999999999998],
+        [34.3, 28.099999999999998],
+        [34.3, 28.7],
+        [33.7, 28.7]
       ],
       "visible": true,
       "metadata": {},
@@ -1718,24 +787,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          33.7,
-          28.9
-        ],
-        [
-          34.3,
-          28.9
-        ],
-        [
-          34.3,
-          29.5
-        ],
-        [
-          33.7,
-          29.5
-        ]
-      ],
+      "polygon": [[33.7, 28.9], [34.3, 28.9], [34.3, 29.5], [33.7, 29.5]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -1746,24 +798,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          33.7,
-          29.7
-        ],
-        [
-          34.3,
-          29.7
-        ],
-        [
-          34.3,
-          30.3
-        ],
-        [
-          33.7,
-          30.3
-        ]
-      ],
+      "polygon": [[33.7, 29.7], [34.3, 29.7], [34.3, 30.3], [33.7, 30.3]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -1774,24 +809,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          33.7,
-          30.5
-        ],
-        [
-          34.3,
-          30.5
-        ],
-        [
-          34.3,
-          31.1
-        ],
-        [
-          33.7,
-          31.1
-        ]
-      ],
+      "polygon": [[33.7, 30.5], [34.3, 30.5], [34.3, 31.1], [33.7, 31.1]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -1802,24 +820,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          22.7,
-          20.7
-        ],
-        [
-          23.3,
-          20.7
-        ],
-        [
-          23.3,
-          21.3
-        ],
-        [
-          22.7,
-          21.3
-        ]
-      ],
+      "polygon": [[22.7, 20.7], [23.3, 20.7], [23.3, 21.3], [22.7, 21.3]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -1830,24 +831,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          22.7,
-          19.9
-        ],
-        [
-          23.3,
-          19.9
-        ],
-        [
-          23.3,
-          20.5
-        ],
-        [
-          22.7,
-          20.5
-        ]
-      ],
+      "polygon": [[22.7, 19.9], [23.3, 19.9], [23.3, 20.5], [22.7, 20.5]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -1858,24 +842,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          0.1,
-          21.95
-        ],
-        [
-          1.9,
-          21.95
-        ],
-        [
-          1.9,
-          22.05
-        ],
-        [
-          0.1,
-          22.05
-        ]
-      ],
+      "polygon": [[0.1, 21.95], [1.9, 21.95], [1.9, 22.05], [0.1, 22.05]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -1889,24 +856,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          -0.05,
-          22.1
-        ],
-        [
-          0.05,
-          22.1
-        ],
-        [
-          0.05,
-          23.9
-        ],
-        [
-          -0.05,
-          23.9
-        ]
-      ],
+      "polygon": [[-0.05, 22.1], [0.05, 22.1], [0.05, 23.9], [-0.05, 23.9]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -1920,24 +870,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          22.1,
-          21.95
-        ],
-        [
-          23.9,
-          21.95
-        ],
-        [
-          23.9,
-          22.05
-        ],
-        [
-          22.1,
-          22.05
-        ]
-      ],
+      "polygon": [[22.1, 21.95], [23.9, 21.95], [23.9, 22.05], [22.1, 22.05]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -1951,24 +884,7 @@
       "type": "slab",
       "holes": [],
       "object": "node",
-      "polygon": [
-        [
-          21.95,
-          22.1
-        ],
-        [
-          22.05,
-          22.1
-        ],
-        [
-          22.05,
-          23.9
-        ],
-        [
-          21.95,
-          23.9
-        ]
-      ],
+      "polygon": [[21.95, 22.1], [22.05, 22.1], [22.05, 23.9], [21.95, 23.9]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo",
@@ -1982,24 +898,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          21.7,
-          16.7
-        ],
-        [
-          22.3,
-          16.7
-        ],
-        [
-          22.3,
-          17.3
-        ],
-        [
-          21.7,
-          17.3
-        ]
-      ],
+      "polygon": [[21.7, 16.7], [22.3, 16.7], [22.3, 17.3], [21.7, 17.3]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -2010,24 +909,7 @@
       "type": "zone",
       "color": "#f0f0f0",
       "object": "node",
-      "polygon": [
-        [
-          21.7,
-          17.5
-        ],
-        [
-          22.3,
-          17.5
-        ],
-        [
-          22.3,
-          18.1
-        ],
-        [
-          21.7,
-          18.1
-        ]
-      ],
+      "polygon": [[21.7, 17.5], [22.3, 17.5], [22.3, 18.1], [21.7, 18.1]],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
@@ -2039,22 +921,10 @@
       "color": "#f0f0f0",
       "object": "node",
       "polygon": [
-        [
-          21.7,
-          18.3
-        ],
-        [
-          22.3,
-          18.3
-        ],
-        [
-          22.3,
-          18.900000000000002
-        ],
-        [
-          21.7,
-          18.900000000000002
-        ]
+        [21.7, 18.3],
+        [22.3, 18.3],
+        [22.3, 18.900000000000002],
+        [21.7, 18.900000000000002]
       ],
       "visible": true,
       "metadata": {},
@@ -2067,22 +937,10 @@
       "color": "#f0f0f0",
       "object": "node",
       "polygon": [
-        [
-          11.7,
-          27.3
-        ],
-        [
-          12.3,
-          27.3
-        ],
-        [
-          12.3,
-          27.900000000000002
-        ],
-        [
-          11.7,
-          27.900000000000002
-        ]
+        [11.7, 27.3],
+        [12.3, 27.3],
+        [12.3, 27.900000000000002],
+        [11.7, 27.900000000000002]
       ],
       "visible": true,
       "metadata": {},
@@ -2095,30 +953,16 @@
       "color": "#f0f0f0",
       "object": "node",
       "polygon": [
-        [
-          11.7,
-          28.099999999999998
-        ],
-        [
-          12.3,
-          28.099999999999998
-        ],
-        [
-          12.3,
-          28.7
-        ],
-        [
-          11.7,
-          28.7
-        ]
+        [11.7, 28.099999999999998],
+        [12.3, 28.099999999999998],
+        [12.3, 28.7],
+        [11.7, 28.7]
       ],
       "visible": true,
       "metadata": {},
       "parentId": "level_conv_demo"
     }
   },
-  "rootNodeIds": [
-    "site_conv_demo"
-  ],
+  "rootNodeIds": ["site_conv_demo"],
   "collections": {}
-}
\ No newline at end of file
+}
diff --git a/packages/nodes/src/shelf/definition.ts b/packages/nodes/src/shelf/definition.ts
index 0bc2e4699..b30967b53 100644
--- a/packages/nodes/src/shelf/definition.ts
+++ b/packages/nodes/src/shelf/definition.ts
@@ -185,6 +185,27 @@ export const shelfDefinition: NodeDefinition<typeof ShelfNode> = {
   // system.tsx, no inline floor-plan SVG — see
   // `wiki/architecture/node-definitions.md`.
   geometry: buildShelfGeometry,
+  // Boards/posts/back depend only on these fields — never on hosted
+  // `children`. Lets <GeometrySystem> skip the dispose+rebuild (and the
+  // pointer enter/leave churn it causes) when an item reparents onto a row.
+  geometryKey: (n) => {
+    const s = n as ShelfNodeType
+    return JSON.stringify([
+      s.style,
+      s.width,
+      s.depth,
+      s.thickness,
+      s.height,
+      s.rows,
+      s.columns,
+      s.withBack,
+      s.withSides,
+      s.withBottom,
+      s.bracketStyle,
+      s.material,
+      s.materialPreset,
+    ])
+  },
   floorplan: buildShelfFloorplan,
   // 2D move handler — Path 1 in `FloorplanRegistryMoveOverlay`. Without
   // this the overlay falls through to Path 2 which stomps the SVG
diff --git a/packages/nodes/src/window/move-tool.tsx b/packages/nodes/src/window/move-tool.tsx
index bbb0504ec..fa9918ba3 100644
--- a/packages/nodes/src/window/move-tool.tsx
+++ b/packages/nodes/src/window/move-tool.tsx
@@ -70,12 +70,17 @@ const MoveWindowTool: React.FC<{ node: WindowNode }> = ({ node: movingWindowNode
       metadata: movingWindowNode.metadata,
     }
 
-    // Mark the moving window as transient so it doesn't intercept wall raycasts while repositioning.
-    // Without this, duplicates can block `wall:*` events which breaks the cursor box and can cause
-    // rapid enter/leave churn (triggering expensive wall CSG rebuilds).
-    useScene.getState().updateNode(movingWindowNode.id, {
-      metadata: { ...meta, isTransient: true },
-    })
+    // In move mode (existing window) mark it transient so its mesh skips the live wall CSG
+    // rebuild while repositioning — the editor requests a final rebuild on commit. For a new
+    // placement (preset/duplicate) we must NOT mark it transient: WindowSystem only rebuilds
+    // the host wall's cutout for non-transient windows, so a transient draft shows no live
+    // preview on the wall and can't be placed consecutively without leaving/re-entering. This
+    // mirrors MoveDoorTool.
+    if (!isNew) {
+      useScene.getState().updateNode(movingWindowNode.id, {
+        metadata: { ...meta, isTransient: true },
+      })
+    }
 
     let currentWallId: string | null = movingWindowNode.parentId
 
diff --git a/packages/viewer/src/systems/geometry/geometry-system.tsx b/packages/viewer/src/systems/geometry/geometry-system.tsx
index 05e50652f..3e6ddaf3e 100644
--- a/packages/viewer/src/systems/geometry/geometry-system.tsx
+++ b/packages/viewer/src/systems/geometry/geometry-system.tsx
@@ -11,7 +11,7 @@ import {
   useScene,
 } from '@pascal-app/core'
 import { useFrame } from '@react-three/fiber'
-import { useEffect } from 'react'
+import { useEffect, useRef } from 'react'
 import { FrontSide, type Group, type Material, type Mesh } from 'three'
 import {
   type ColorPreset,
@@ -58,6 +58,11 @@ export const GeometrySystem = () => {
   const textures = useViewer((s) => s.textures)
   const colorPreset = useViewer((s) => s.colorPreset)
   const sceneTheme = useViewer((s) => s.sceneTheme)
+  // Per-node cache of the last-built geometry key (for kinds that declare
+  // `def.geometryKey`). Lets us skip a dispose+rebuild when a node is dirty
+  // but its geometry inputs are unchanged — e.g. an item reparenting onto a
+  // shelf dirties the shelf without altering its boards.
+  const builtGeometryKeyRef = useRef<Map<string, string>>(new Map())
 
   useEffect(() => {
     const nodes = useScene.getState().nodes
@@ -146,6 +151,20 @@ export const GeometrySystem = () => {
       // now smooths drags through this single line.
       const effectiveNode = getEffectiveNode(node)
 
+      // Skip the rebuild when the geometry inputs are unchanged (kinds that
+      // opt in via `def.geometryKey`). Fold in the global rendering inputs so
+      // a theme / shading change — which re-dirties every geometry node — is
+      // never skipped. This kills the board remount + pointer enter/leave
+      // churn when an item reparents onto a shelf.
+      if (def.geometryKey) {
+        const builtKey = `${shading}|${textures}|${colorPreset}|${sceneTheme}|${def.geometryKey(effectiveNode)}`
+        if (builtGeometryKeyRef.current.get(id) === builtKey) {
+          clearDirty(id as AnyNodeId)
+          continue
+        }
+        builtGeometryKeyRef.current.set(id, builtKey)
+      }
+
       const parentId = (node.parentId ?? null) as AnyNodeId | null
       const key: BatchKey = `${node.type}::${parentId ?? ''}`
       const levelData = levelDataByBatch.get(key)
diff --git a/packages/viewer/src/systems/wall/wall-system.tsx b/packages/viewer/src/systems/wall/wall-system.tsx
index de20be1e3..912f885cb 100644
--- a/packages/viewer/src/systems/wall/wall-system.tsx
+++ b/packages/viewer/src/systems/wall/wall-system.tsx
@@ -18,6 +18,7 @@ import {
   sceneRegistry,
   spatialGridManager,
   useLiveNodeOverrides,
+  useLiveTransforms,
   useScene,
   type WallMiterData,
   type WallNode,
@@ -492,9 +493,18 @@ function updateWallGeometry(wallId: string, miterData: WallMiterData) {
   const childrenNodes = childrenIds
     .map((childId) => nodes[childId])
     .filter((n): n is AnyNode => n !== undefined)
-    .map((child) =>
-      child.type === 'door' || child.type === 'window' ? getEffectiveNode(child) : child,
-    )
+    .map((child) => {
+      if (child.type !== 'door' && child.type !== 'window') return child
+      // `getEffectiveNode` folds in resize overrides (width/height arrows).
+      // Position moves publish to `useLiveTransforms` instead, so fold that
+      // in too — otherwise shaped openings (arch/rounded/`opening`), whose
+      // cutout brush is rebuilt from `node.position`, lag the live move
+      // (rectangular cutouts already track via the live mesh matrixWorld).
+      const effective = getEffectiveNode(child)
+      const live = useLiveTransforms.getState().get(child.id)
+      if (!live?.position) return effective
+      return { ...effective, position: live.position }
+    })
 
   const newGeo = generateExtrudedWall(node, childrenNodes, miterData, slabElevation)