fix(core): preserve legacy site children during scene healing (#544)

packages/core/src/store/use-scene-site-child-migration.test.ts

@@ -0,0 +1,75 @@
+import { beforeEach, describe, expect, test } from 'bun:test'
+import type { AnyNode } from '../schema'
+import useScene from './use-scene'
+
+describe('legacy site child migration', () => {
+  beforeEach(() => {
+    useScene.setState({
+      nodes: {},
+      rootNodeIds: [],
+      dirtyNodes: new Set(),
+      collections: {},
+    } as never)
+    useScene.temporal.getState().clear()
+  })
+
+  test('keeps a flat building subtree referenced by an embedded site child', () => {
+    const embeddedBuilding = {
+      object: 'node',
+      id: 'building_legacy',
+      type: 'building',
+      parentId: null,
+      visible: true,
+      metadata: {},
+      children: ['level_legacy'],
+      position: [0, 0, 0],
+      rotation: [0, 0, 0],
+    }
+
+    useScene.getState().setScene(
+      {
+        site_legacy: {
+          object: 'node',
+          id: 'site_legacy',
+          type: 'site',
+          parentId: null,
+          visible: true,
+          metadata: {},
+          children: [embeddedBuilding],
+        },
+        building_legacy: embeddedBuilding,
+        level_legacy: {
+          object: 'node',
+          id: 'level_legacy',
+          type: 'level',
+          parentId: null,
+          visible: true,
+          metadata: {},
+          children: ['wall_legacy'],
+          level: 0,
+        },
+        wall_legacy: {
+          object: 'node',
+          id: 'wall_legacy',
+          type: 'wall',
+          parentId: 'level_legacy',
+          visible: true,
+          metadata: {},
+          children: [],
+          start: [0, 0],
+          end: [4, 0],
+        },
+      } as unknown as Record<string, AnyNode>,
+      ['site_legacy'] as never,
+    )
+
+    const nodes = useScene.getState().nodes
+    expect(Object.keys(nodes).sort()).toEqual([
+      'building_legacy',
+      'level_legacy',
+      'site_legacy',
+      'wall_legacy',
+    ])
+    expect((nodes.site_legacy as { children: string[] }).children).toEqual(['building_legacy'])
+  })
+})

packages/core/src/utils/heal-scene-graph.test.ts

@@ -17,6 +17,28 @@ describe('healSceneNodes', () => {
     expect((nodes.wall_a as { children: string[] }).children).toEqual(['item_x'])
   })
 
+  test('preserves legacy embedded site children for the scene migration', () => {
+    const building = {
+      id: 'building_legacy',
+      type: 'building',
+      parentId: null,
+      children: ['level_legacy'],
+    }
+    const { nodes, strippedChildRefs } = healSceneNodes({
+      site_legacy: {
+        id: 'site_legacy',
+        type: 'site',
+        parentId: null,
+        children: [building, null],
+      },
+      building_legacy: building,
+      level_legacy: { id: 'level_legacy', type: 'level', parentId: null, children: [] },
+    })
+
+    expect(strippedChildRefs).toBe(1)
+    expect((nodes.site_legacy as { children: unknown[] }).children).toEqual([building])
+  })
+
   test('drops childless zero-length walls and removes their parent reference', () => {
     const { nodes, droppedWallIds } = healSceneNodes({
       level_0: { id: 'level_0', type: 'level', children: ['wall_zero', 'wall_real'] },

packages/core/src/utils/heal-scene-graph.ts

@@ -23,7 +23,7 @@ export interface HealSceneResult {
   nodes: Record<string, unknown>
   /** Ids of zero-length walls that were dropped. */
   droppedWallIds: string[]
-  /** Count of non-string (e.g. null) entries removed from `children` arrays. */
+  /** Count of invalid non-string (e.g. null) entries removed from `children` arrays. */
   strippedChildRefs: number
   /**
    * Count of child references removed because the child's `parentId` points at
@@ -74,26 +74,43 @@ export function healSceneNodes(input: Record<string, unknown>): HealSceneResult
   let strippedChildRefs = 0
   let strippedStaleChildRefs = 0
 
-  // Pass 2: clean `children` arrays — drop non-string entries (the `[null]`
-  // bug), references to walls we just removed, same-array duplicates, and
-  // stale references whose child's `parentId` names a different parent.
+  // Pass 2: clean `children` arrays — drop invalid non-string entries (the
+  // `[null]` bug), references to walls we just removed, same-array duplicates,
+  // and stale references whose child's `parentId` names a different parent.
+  // Legacy sites embedded full child objects; keep those for migrateNodes to
+  // flatten after healing instead of disconnecting the entire building.
   const nodes: Record<string, unknown> = {}
   for (const [id, node] of Object.entries(kept)) {
     const children = (node as { children?: unknown })?.children
     if (Array.isArray(children)) {
       const seen = new Set<string>()
-      const cleaned = children.filter((c): c is string => {
-        if (typeof c !== 'string' || dropped.has(c)) {
+      const cleaned = children.filter((child) => {
+        const embeddedSiteChildId =
+          (node as { type?: unknown }).type === 'site' &&
+          child &&
+          typeof child === 'object' &&
+          typeof (child as { id?: unknown }).id === 'string'
+            ? (child as { id: string }).id
+            : null
+        if (embeddedSiteChildId) {
+          if (seen.has(embeddedSiteChildId)) {
+            strippedStaleChildRefs++
+            return false
+          }
+          seen.add(embeddedSiteChildId)
+          return true
+        }
+        if (typeof child !== 'string' || dropped.has(child)) {
           strippedChildRefs++
           return false
         }
-        if (seen.has(c)) {
+        if (seen.has(child)) {
           strippedStaleChildRefs++
           return false
         }
-        seen.add(c)
-        const child = kept[c] as { parentId?: unknown } | undefined
-        if (child && typeof child.parentId === 'string' && child.parentId !== id) {
+        seen.add(child)
+        const childNode = kept[child] as { parentId?: unknown } | undefined
+        if (childNode && typeof childNode.parentId === 'string' && childNode.parentId !== id) {
           strippedStaleChildRefs++
           return false
         }