take only building layers to the thumbnail

packages/viewer/src/systems/level/level-system.tsx

@@ -1,62 +1,14 @@
-import { type CeilingNode, type LevelNode, sceneRegistry, useScene, type WallNode } from '@pascal-app/core'
+import { type LevelNode, sceneRegistry, useScene } from '@pascal-app/core'
 import { useFrame } from '@react-three/fiber'
 import { lerp } from 'three/src/math/MathUtils.js'
 import useViewer from '../../store/use-viewer'
+import { getLevelHeight } from './level-utils'
 
-const DEFAULT_LEVEL_HEIGHT = 2.5
 const EXPLODED_GAP = 5
 
-// Cache: levelId → computed height. Invalidated by nodes reference change.
-// Zustand produces a new `nodes` object on every mutation, so reference equality
-// is a zero-cost way to detect stale data without any subscription overhead.
-const heightCache = new Map<string, number>()
-let lastNodesRef: object | null = null
-
-function getLevelHeight(
-  levelId: string,
-  nodes: ReturnType<typeof useScene.getState>['nodes'],
-): number {
-  if (heightCache.has(levelId)) return heightCache.get(levelId)!
-
-  const level = nodes[levelId as LevelNode['id']] as LevelNode | undefined
-  if (!level) return DEFAULT_LEVEL_HEIGHT
-
-  let maxTop = 0
-
-  for (const childId of level.children) {
-    const child = nodes[childId as keyof typeof nodes]
-    if (!child) continue
-    if (child.type === 'ceiling') {
-      // ceiling.height is the interior face Y in level-local space
-      const ch = (child as CeilingNode).height ?? DEFAULT_LEVEL_HEIGHT
-      if (ch > maxTop) maxTop = ch
-    } 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.
-      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
-    }
-  }
-
-  const height = maxTop > 0 ? maxTop : DEFAULT_LEVEL_HEIGHT
-  heightCache.set(levelId, height)
-  return height
-}
-
 export const LevelSystem = () => {
   useFrame((_, delta) => {
     const nodes = useScene.getState().nodes
-
-    // Clear cache when nodes reference changes (any node was mutated)
-    if (nodes !== lastNodesRef) {
-      heightCache.clear()
-      lastNodesRef = nodes
-    }
-
     const levelMode = useViewer.getState().levelMode
     const selectedLevel = useViewer.getState().selection.levelId