From bc63f7e53db619382b318ec73ba698c295692f7a Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 14:25:31 -0400
Subject: [PATCH 01/11] Scope undo invalidation to changed geometry and cleared
 previews

---
 .../spatial-grid/spatial-grid-sync.test.ts    | 132 ++++++++-
 .../hooks/spatial-grid/spatial-grid-sync.ts   |  98 +++++--
 .../src/store/history-invalidation.test.ts    | 223 +++++++++++++++
 .../core/src/store/history-invalidation.ts    |  70 +++++
 packages/core/src/store/use-scene.ts          |  52 ++--
 packages/editor/src/lib/history.test.ts       | 265 ++++++++++++++++++
 packages/editor/src/lib/history.ts            |  26 +-
 wiki/architecture/systems.md                  |  23 ++
 8 files changed, 834 insertions(+), 55 deletions(-)
 create mode 100644 packages/core/src/store/history-invalidation.test.ts
 create mode 100644 packages/core/src/store/history-invalidation.ts

diff --git a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
index d96ee2f36e..0241aa3779 100644
--- a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
+++ b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
@@ -4,7 +4,7 @@ import { encodeTerrainField } from '../../lib/terrain-codec'
 import { applyHeightPatch, createTerrainField, flattenPatch } from '../../lib/terrain-field'
 import { nodeRegistry, registerNode } from '../../registry'
 import type { AnyNodeDefinition } from '../../registry/types'
-import type { AnyNode, AnyNodeId } from '../../schema'
+import { type AnyNode, type AnyNodeId, ItemNode, LevelNode, SlabNode, WallNode } from '../../schema'
 import useLiveTerrain from '../../store/use-live-terrain'
 import useScene, { clearSceneHistory } from '../../store/use-scene'
 import { spatialGridManager } from './spatial-grid-manager'
@@ -565,3 +565,133 @@ describe('spatial-grid sync dirty rules (terrain support)', () => {
     expect(marked).toEqual(['wall_ground', 'wall_fill', 'slab_fill', 'column_a'])
   })
 })
+
+describe('temporal writes update slab support dependencies', () => {
+  let stop = () => {}
+  let restore = () => {}
+  beforeEach(() => {
+    restore = nodeRegistry._snapshot()
+    nodeRegistry._register({
+      kind: 'item',
+      schemaVersion: 1,
+      schema: ItemNode,
+      capabilities: {
+        floorPlaced: { footprint: () => ({ dimensions: [0.2, 1, 0.2], rotation: [0, 0, 0] }) },
+      },
+    } as never)
+    spatialGridManager.clear()
+  })
+  afterEach(() => {
+    stop()
+    restore()
+    spatialGridManager.clear()
+    clearSceneHistory()
+  })
+
+  test('undo/redo of wall thickness re-elevates an unchanged item on the former rendered slab band', async () => {
+    const level = LevelNode.parse({ id: 'level_band_history' })
+    const wall = WallNode.parse({
+      id: 'wall_band_history',
+      parentId: level.id,
+      start: [4, 0],
+      end: [4, 4],
+      thickness: 0.8,
+    })
+    const slab = SlabNode.parse({
+      parentId: level.id,
+      polygon: SQUARE,
+      elevation: 0.4,
+      thickness: 0.4,
+    })
+    const item = ItemNode.parse({
+      parentId: level.id,
+      position: [4.45, 0, 2],
+      asset: {
+        id: 'test',
+        name: 'test',
+        category: 'test',
+        thumbnail: '',
+        src: '/test.glb',
+        dimensions: [0.2, 1, 0.2],
+      },
+    })
+    const remote = { ...item, id: 'item_remote_band', position: [20, 0, 20] } as AnyNode
+    useScene.setState({
+      nodes: nodesFor(level, wall, slab, item, remote),
+      dirtyNodes: new Set(),
+      readOnly: false,
+    })
+    clearSceneHistory()
+    stop = initSpatialGridSync()
+    const elevation = () =>
+      spatialGridManager.getSlabSupportForItem(level.id, item.position, [0.2, 1, 0.2], [0, 0, 0])
+        .elevation
+    expect(elevation()).toBeCloseTo(0.4)
+    useScene.setState({
+      nodes: { ...useScene.getState().nodes, [wall.id]: { ...wall, thickness: 0.1 } },
+    })
+    expect(elevation()).toBe(0)
+    expect(useScene.getState().dirtyNodes.has(item.id)).toBe(true)
+    for (const [jump, expected] of [
+      [useScene.temporal.getState().undo, 0.4],
+      [useScene.temporal.getState().redo, 0],
+    ] as const) {
+      useScene.getState().dirtyNodes.clear()
+      jump()
+      // The support subscription runs on the write, before the temporal microtask.
+      expect(useScene.getState().dirtyNodes.has(item.id)).toBe(true)
+      expect(elevation()).toBeCloseTo(expected)
+      await Promise.resolve()
+      expect(useScene.getState().nodes[item.id]).toBe(item)
+      expect(useScene.getState().nodes[slab.id]).toBe(slab)
+      expect(useScene.getState().dirtyNodes.has(remote.id)).toBe(false)
+    }
+  })
+
+  test('slab elevation and level height subscribers fire during real temporal restoration', async () => {
+    const level = LevelNode.parse({
+      id: 'level_vertical_history',
+      children: ['wall_vertical_history'],
+    })
+    const wall = WallNode.parse({
+      id: 'wall_vertical_history',
+      parentId: level.id,
+      start: [0, 0],
+      end: [4, 0],
+    })
+    const slab = SlabNode.parse({
+      parentId: level.id,
+      polygon: SQUARE,
+      elevation: 1,
+      thickness: 0.1,
+    })
+    const item = ItemNode.parse({
+      parentId: level.id,
+      position: [2, 0, 2],
+      asset: { id: 'test', name: 'test', category: 'test', thumbnail: '', src: '/test.glb' },
+    })
+    useScene.setState({
+      nodes: nodesFor(level, wall, slab, item),
+      dirtyNodes: new Set(),
+      readOnly: false,
+    })
+    clearSceneHistory()
+    stop = initSpatialGridSync()
+    useScene.setState({
+      nodes: {
+        ...useScene.getState().nodes,
+        [slab.id]: { ...slab, elevation: 2 },
+        [level.id]: { ...level, height: 4 },
+      },
+    })
+    useScene.getState().dirtyNodes.clear()
+    useScene.temporal.getState().undo()
+    expect(useScene.getState().dirtyNodes.has(item.id)).toBe(true)
+    expect(useScene.getState().dirtyNodes.has(wall.id)).toBe(true)
+    expect(
+      spatialGridManager.getSlabSupportForItem(level.id, item.position, [0.2, 1, 0.2], [0, 0, 0])
+        .elevation,
+    ).toBe(1)
+    await Promise.resolve()
+  })
+})
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 d05d0d68e4..9b8d35329a 100644
--- a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
+++ b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
@@ -111,6 +111,33 @@ export function initSpatialGridSync(): () => void {
 
   // Subscribe to all changes
   const unsubscribeScene = store.subscribe((state, prevState) => {
+    if (state.nodes === prevState.nodes) return
+    const changedSlabContextLevels = new Set<string>()
+    for (const id of new Set([...Object.keys(prevState.nodes), ...Object.keys(state.nodes)])) {
+      const previous = prevState.nodes[id as AnyNodeId]
+      const next = state.nodes[id as AnyNodeId]
+      if (previous === next) continue
+      const wallChanged =
+        (previous?.type === 'wall' || next?.type === 'wall') &&
+        (previous?.type !== 'wall' ||
+          next?.type !== 'wall' ||
+          previous.parentId !== next.parentId ||
+          previous.start !== next.start ||
+          previous.end !== next.end ||
+          previous.thickness !== next.thickness ||
+          previous.curveOffset !== next.curveOffset)
+      const slabChanged =
+        (previous?.type === 'slab' || next?.type === 'slab') &&
+        (previous?.type !== 'slab' ||
+          next?.type !== 'slab' ||
+          previous.parentId !== next.parentId ||
+          previous.polygon !== next.polygon ||
+          previous.elevation !== next.elevation)
+      if (!(wallChanged || slabChanged)) continue
+      if (previous) changedSlabContextLevels.add(resolveLevelId(previous, prevState.nodes))
+      if (next) changedSlabContextLevels.add(resolveLevelId(next, state.nodes))
+    }
+
     // Detect added nodes
     for (const [id, node] of Object.entries(state.nodes)) {
       if (!prevState.nodes[id as AnyNode['id']]) {
@@ -140,7 +167,7 @@ export function initSpatialGridSync(): () => void {
 
         // When a slab is removed, mark items/walls that were on it dirty (using current state)
         if (node.type === 'slab') {
-          markNodesOverlappingSlab(node as SlabNode, state.nodes, markDirty)
+          markNodesOverlappingSlab(node as SlabNode, state.nodes, markDirty, prevState.nodes)
           markCoveringDependentsBelow(levelId, state.nodes, markDirty)
         }
 
@@ -183,7 +210,13 @@ export function initSpatialGridSync(): () => void {
           const levelId = resolveLevelId(node, state.nodes)
           spatialGridManager.handleNodeUpdated(node, levelId)
         }
-        markSlabChangeDependents(prev as SlabNode, node as SlabNode, state.nodes, markDirty)
+        markSlabChangeDependents(
+          prev as SlabNode,
+          node as SlabNode,
+          state.nodes,
+          markDirty,
+          prevState.nodes,
+        )
       } else if (node.type === 'level' && prev.type === 'level') {
         if (node.height !== prev.height) {
           markLevelHeightDependents(node as LevelNode, state.nodes, markDirty)
@@ -210,6 +243,31 @@ export function initSpatialGridSync(): () => void {
         }
       }
     }
+
+    // Unchanged slabs can lose an adopted wall band or a sibling seam. Their
+    // stored polygons cannot identify objects standing on the former boundary.
+    for (const slab of Object.values(state.nodes)) {
+      if (slab.type !== 'slab') continue
+      const previous = prevState.nodes[slab.id]
+      if (previous?.type !== 'slab') continue
+      if (
+        slab.parentId !== previous.parentId ||
+        slab.polygon !== previous.polygon ||
+        slab.elevation !== previous.elevation ||
+        slab.holes !== previous.holes
+      )
+        continue
+      if (!changedSlabContextLevels.has(resolveLevelId(slab, state.nodes))) continue
+      const beforePolygon = renderableSlabPolygon(previous, prevState.nodes)
+      const afterPolygon = renderableSlabPolygon(slab, state.nodes)
+      if (
+        beforePolygon.length === afterPolygon.length &&
+        beforePolygon.every((point, i) => arraysEqual(point, afterPolygon[i]!))
+      )
+        continue
+      markNodesOverlappingSlab(previous, state.nodes, markDirty, prevState.nodes)
+      markNodesOverlappingSlab(slab, state.nodes, markDirty)
+    }
   })
 
   // Live terrain is deliberately not written into `useScene` per dab: doing so
@@ -282,14 +340,16 @@ export function markSlabChangeDependents(
   next: SlabNode,
   nodes: Record<string, AnyNode>,
   markDirty: (id: AnyNodeId) => void,
+  previousNodes = nodes,
 ) {
   const supportChanged =
+    next.parentId !== previous.parentId ||
     next.polygon !== previous.polygon ||
     next.elevation !== previous.elevation ||
     next.holes !== previous.holes
 
   if (supportChanged) {
-    markNodesOverlappingSlab(previous, nodes, markDirty)
+    markNodesOverlappingSlab(previous, nodes, markDirty, previousNodes)
     markNodesOverlappingSlab(next, nodes, markDirty)
   }
   if (next.elevation !== previous.elevation) {
@@ -396,22 +456,8 @@ export function markCoveringDependentsBelow(
   }
 }
 
-/**
- * Mark all floor items and walls that may be affected by a slab change as dirty.
- */
-function markNodesOverlappingSlab(
-  slab: SlabNode,
-  nodes: Record<string, AnyNode>,
-  markDirty: (id: AnyNodeId) => void,
-) {
-  if (slab.polygon.length < 3) return
+function renderableSlabPolygon(slab: SlabNode, nodes: Record<string, AnyNode>) {
   const slabLevelId = resolveLevelId(slab, nodes)
-
-  // Walls AND floor-placed nodes follow the slab's RENDERED footprint
-  // (band-adopted edges reach the wall's outer face), so the dirty gate
-  // must test the same polygon the support queries re-evaluate — a stored
-  // polygon that stops short of the wall body would otherwise never
-  // re-elevate nodes sitting over the adopted band.
   const levelWalls: WallNode[] = []
   const siblingSlabs: SlabNode[] = []
   for (const node of Object.values(nodes)) {
@@ -425,7 +471,21 @@ function markNodesOverlappingSlab(
       siblingSlabs.push(node as SlabNode)
     }
   }
-  const renderedPolygon = getRenderableSlabPolygon(slab, { walls: levelWalls, siblingSlabs })
+  return getRenderableSlabPolygon(slab, { walls: levelWalls, siblingSlabs })
+}
+
+/**
+ * Mark all floor items and walls that may be affected by a slab change as dirty.
+ */
+function markNodesOverlappingSlab(
+  slab: SlabNode,
+  nodes: Record<string, AnyNode>,
+  markDirty: (id: AnyNodeId) => void,
+  contextNodes = nodes,
+) {
+  if (slab.polygon.length < 3) return
+  const slabLevelId = resolveLevelId(slab, contextNodes)
+  const renderedPolygon = renderableSlabPolygon(slab, contextNodes)
 
   for (const node of Object.values(nodes)) {
     if (node.type === 'wall') {
diff --git a/packages/core/src/store/history-invalidation.test.ts b/packages/core/src/store/history-invalidation.test.ts
new file mode 100644
index 0000000000..576b7669e0
--- /dev/null
+++ b/packages/core/src/store/history-invalidation.test.ts
@@ -0,0 +1,223 @@
+import { describe, expect, test } from 'bun:test'
+import {
+  type AnyNode,
+  CeilingNode,
+  DoorNode,
+  ItemNode,
+  LevelNode,
+  SlabNode,
+  WallNode,
+  WindowNode,
+} from '../schema'
+import { getHistoryDirtyNodeIds } from './history-invalidation'
+
+const level = LevelNode.parse({ id: 'level_history' })
+const wall = WallNode.parse({ id: 'wall_changed', parentId: level.id, start: [0, 0], end: [4, 0] })
+const remote = WallNode.parse({
+  id: 'wall_remote',
+  parentId: level.id,
+  start: [20, 0],
+  end: [24, 0],
+})
+const nodes = (...entries: AnyNode[]) => Object.fromEntries(entries.map((node) => [node.id, node]))
+const ids = (before: Record<string, AnyNode>, after: Record<string, AnyNode>) =>
+  [...getHistoryDirtyNodeIds(before, after)].sort()
+const asset = { id: 'test', name: 'test', category: 'test', thumbnail: '', src: '/test.glb' }
+
+describe('history dependency closure', () => {
+  test.each([
+    'corner',
+    'tee',
+    'reverse tee',
+    'curve',
+  ])('wall body move disconnects and restores a %s in both directions, only on its level', (junction) => {
+    const changed = junction === 'curve' ? { ...wall, curveOffset: 1 } : wall
+    const adjacent = WallNode.parse({
+      id: 'wall_adjacent',
+      parentId: level.id,
+      start:
+        junction === 'corner'
+          ? [4, 0]
+          : junction === 'tee'
+            ? [2, 0]
+            : junction === 'curve'
+              ? [4, 0]
+              : [4, -2],
+      end: junction === 'reverse tee' ? [4, 2] : [2, -3],
+    })
+    const otherLevel = { ...adjacent, id: 'wall_other_level', parentId: 'level_other' } as WallNode
+    const before = nodes(level, changed, adjacent, remote, otherLevel)
+    const after = {
+      ...before,
+      [changed.id]: { ...changed, start: [8, 8], end: [12, 8] } as WallNode,
+    }
+    expect(ids(before, after)).toEqual([level.id, adjacent.id, changed.id].sort())
+    expect(ids(after, before)).toEqual(ids(before, after))
+  })
+
+  test('endpoint move includes former and new neighbours without following a junction transitively', () => {
+    const old = WallNode.parse({ id: 'wall_old', parentId: level.id, start: [4, 0], end: [4, 4] })
+    const next = WallNode.parse({ id: 'wall_next', parentId: level.id, start: [6, 0], end: [6, 4] })
+    const beyond = WallNode.parse({
+      id: 'wall_beyond',
+      parentId: level.id,
+      start: [6, 4],
+      end: [8, 4],
+    })
+    const before = nodes(level, wall, old, next, beyond, remote)
+    const after = { ...before, [wall.id]: { ...wall, end: [6, 0] } as WallNode }
+    expect(ids(before, after)).toEqual([level.id, wall.id, old.id, next.id].sort())
+  })
+
+  test.each([
+    { thickness: 0.4 },
+    { height: 4 },
+    { curveOffset: 0.8 },
+  ])('host shape change %j includes opening proxies and wall-side items', (patch) => {
+    const door = DoorNode.parse({ parentId: wall.id })
+    const window = WindowNode.parse({ parentId: wall.id })
+    const item = ItemNode.parse({ parentId: wall.id, asset: { ...asset, attachTo: 'wall-side' } })
+    const other = DoorNode.parse({ parentId: remote.id })
+    const before = nodes(level, wall, remote, door, window, item, other)
+    const after = { ...before, [wall.id]: { ...wall, ...patch } }
+    expect(ids(before, after)).toEqual([level.id, wall.id, door.id, window.id, item.id].sort())
+    expect(ids(after, before)).toEqual(ids(before, after))
+  })
+
+  test.each([
+    DoorNode,
+    WindowNode,
+  ])('opening add/remove/move/resize/reparent marks surviving hosts', (schema) => {
+    const opening = schema.parse({ parentId: wall.id })
+    const before = nodes(level, wall, remote, opening)
+    for (const patch of [{ position: [1, 1, 0] }, { width: 2 }, { parentId: remote.id }]) {
+      const after = { ...before, [opening.id]: { ...opening, ...patch } as AnyNode }
+      expect(ids(before, after)).toEqual(
+        [opening.id, wall.id, ...('parentId' in patch ? [remote.id] : [])].sort(),
+      )
+    }
+    const absent = nodes(level, wall, remote)
+    expect(ids(absent, before)).toEqual([opening.id, wall.id].sort())
+    expect(ids(before, absent)).toEqual([wall.id])
+  })
+
+  test.each([
+    'floor',
+    'wall host',
+    'elevated slab',
+  ])('item move on %s marks the item and parent, preserving its asset', (support) => {
+    const item = ItemNode.parse({
+      parentId: support === 'wall host' ? wall.id : level.id,
+      supportSlabId: support === 'elevated slab' ? 'slab_deck' : undefined,
+      asset,
+    })
+    const before = nodes(level, wall, remote, item)
+    const moved = { ...item, position: [3, 0, 2], rotation: [0, 1, 0] } as AnyNode
+    const after = { ...before, [item.id]: moved }
+    expect(ids(before, after)).toEqual([item.id, item.parentId!].sort())
+    expect((moved as ItemNode).asset).toBe(item.asset)
+  })
+
+  test.each([
+    SlabNode,
+    CeilingNode,
+  ])('surface polygon/holes/elevation marks the surface; subscribers own support dependencies', (schema) => {
+    const surface = schema.parse({
+      parentId: level.id,
+      polygon: [
+        [0, 0],
+        [4, 0],
+        [4, 4],
+        [0, 4],
+      ],
+    })
+    const before = nodes(level, wall, remote, surface)
+    for (const patch of [
+      {
+        polygon: [
+          [0, 0],
+          [8, 0],
+          [8, 4],
+          [0, 4],
+        ],
+      },
+      schema === SlabNode ? { elevation: 1 } : { height: 4 },
+      {
+        holes: [
+          [
+            [1, 1],
+            [2, 1],
+            [2, 2],
+          ],
+        ],
+      },
+    ]) {
+      expect(ids(before, { ...before, [surface.id]: { ...surface, ...patch } as AnyNode })).toEqual(
+        [surface.id, level.id].sort(),
+      )
+    }
+  })
+
+  test('level height leaves descendant invalidation to the spatial subscription', () => {
+    const before = nodes(level, wall, remote)
+    expect(ids(before, { ...before, [level.id]: { ...level, height: 4 } })).toEqual([level.id])
+  })
+
+  test('subtree delete/restore filters missing ids and preserves the deletion sibling rule', () => {
+    const door = DoorNode.parse({ parentId: wall.id })
+    const full = nodes(
+      { ...level, children: [wall.id, remote.id] },
+      { ...wall, children: [door.id] },
+      remote,
+      door,
+    )
+    const removed = nodes({ ...level, children: [remote.id] }, remote)
+    expect(ids(full, removed)).toEqual([level.id, remote.id].sort())
+    expect(ids(removed, full)).toEqual([level.id, wall.id, door.id].sort())
+    expect(ids(full, full)).toEqual([])
+  })
+  test('wall reparent includes neighbours on the old and new levels', () => {
+    const upper = LevelNode.parse({ id: 'level_upper_history' })
+    const old = WallNode.parse({
+      id: 'wall_old_level',
+      parentId: level.id,
+      start: [4, 0],
+      end: [4, 4],
+    })
+    const next = { ...old, id: 'wall_new_level', parentId: upper.id } as WallNode
+    const before = nodes(level, upper, wall, old, next, remote)
+    const after = { ...before, [wall.id]: { ...wall, parentId: upper.id } }
+    expect(ids(before, after)).toEqual([level.id, upper.id, wall.id, old.id, next.id].sort())
+  })
+
+  test('thickness rebuilds a joined corner and T junction without dirtying a disconnected wall', () => {
+    const corner = WallNode.parse({
+      id: 'wall_corner',
+      parentId: level.id,
+      start: [4, 0],
+      end: [4, 4],
+    })
+    const tee = WallNode.parse({ id: 'wall_tee', parentId: level.id, start: [2, 0], end: [2, -4] })
+    const before = nodes(level, wall, corner, tee, remote)
+    expect(ids(before, { ...before, [wall.id]: { ...wall, thickness: 0.5 } })).toEqual(
+      [level.id, wall.id, corner.id, tee.id].sort(),
+    )
+  })
+
+  test('same-count subtree replacement restores original identities and excludes deleted ids', () => {
+    const door = DoorNode.parse({ parentId: wall.id })
+    const replacement = DoorNode.parse({ parentId: remote.id })
+    const before = nodes(level, { ...wall, children: [door.id] }, remote, door)
+    const after = nodes(
+      level,
+      { ...wall, children: [] },
+      { ...remote, children: [replacement.id] },
+      replacement,
+    )
+    const dirty = getHistoryDirtyNodeIds(after, before)
+    expect(dirty.has(door.id)).toBe(true)
+    expect(dirty.has(replacement.id)).toBe(false)
+    expect(dirty.has(wall.id)).toBe(true)
+    expect(dirty.has(remote.id)).toBe(true)
+  })
+})
diff --git a/packages/core/src/store/history-invalidation.ts b/packages/core/src/store/history-invalidation.ts
new file mode 100644
index 0000000000..f70a98e9d1
--- /dev/null
+++ b/packages/core/src/store/history-invalidation.ts
@@ -0,0 +1,70 @@
+import type { AnyNode, AnyNodeId, WallNode } from '../schema'
+import { getAdjacentWallIds } from '../systems/wall/wall-mitering'
+
+export function getHistoryDirtyNodeIds(
+  before: Record<string, AnyNode>,
+  after: Record<string, AnyNode>,
+): Set<AnyNodeId> {
+  const dirty = new Set<AnyNodeId>()
+  const changedWalls = new Set<string>()
+  const changedHosts = new Set<string>()
+  const add = (id: string | null | undefined) => {
+    if (id && after[id]) dirty.add(id as AnyNodeId)
+  }
+
+  for (const id of new Set([...Object.keys(before), ...Object.keys(after)])) {
+    const previous = before[id]
+    const next = after[id]
+    if (previous === next) continue
+    add(id)
+    add(previous?.parentId)
+    add(next?.parentId)
+
+    if (previous?.type === 'wall' || next?.type === 'wall') {
+      changedWalls.add(id)
+      if (
+        previous?.type !== 'wall' ||
+        next?.type !== 'wall' ||
+        previous.thickness !== next.thickness ||
+        previous.height !== next.height ||
+        previous.curveOffset !== next.curveOffset
+      ) {
+        changedHosts.add(id)
+      }
+    }
+
+    if (previous && !next && previous.parentId) {
+      const parent = after[previous.parentId]
+      // Preserve deletion's sibling refresh for merged geometry consumers.
+      if (parent && 'children' in parent && Array.isArray(parent.children)) {
+        for (const childId of parent.children) add(childId)
+      }
+    }
+  }
+
+  if (changedWalls.size === 0) return dirty
+
+  for (const nodes of [before, after]) {
+    const wallsByLevel = new Map<string | null, WallNode[]>()
+    for (const node of Object.values(nodes)) {
+      if (node.type === 'wall') {
+        const walls = wallsByLevel.get(node.parentId) ?? []
+        walls.push(node)
+        wallsByLevel.set(node.parentId, walls)
+      }
+      if (
+        node.parentId &&
+        changedHosts.has(node.parentId) &&
+        (node.type === 'door' || node.type === 'window' || node.type === 'item')
+      ) {
+        add(node.id)
+      }
+    }
+    // Former junctions must rebuild too; the viewer only sees the restored layout.
+    for (const walls of wallsByLevel.values()) {
+      const changed = new Set(walls.filter((wall) => changedWalls.has(wall.id)).map((w) => w.id))
+      for (const id of getAdjacentWallIds(walls, changed)) add(id)
+    }
+  }
+  return dirty
+}
diff --git a/packages/core/src/store/use-scene.ts b/packages/core/src/store/use-scene.ts
index 1f92432ade..052fea9061 100644
--- a/packages/core/src/store/use-scene.ts
+++ b/packages/core/src/store/use-scene.ts
@@ -52,6 +52,7 @@ import {
   type SceneCommitOrigin,
   type SceneSnapshot,
 } from './history-control'
+import { getHistoryDirtyNodeIds } from './history-invalidation'
 import useLiveNodeOverrides from './use-live-node-overrides'
 import useLiveTransforms from './use-live-transforms'
 
@@ -2138,10 +2139,9 @@ export function applySceneSnapshot(
   return true
 }
 
-// Track previous temporal state lengths and node snapshot for diffing
+// Track previous temporal state lengths for identifying history jumps
 let prevPastLength = 0
 let prevFutureLength = 0
-let prevNodesSnapshot: Record<AnyNodeId, AnyNode> | null = null
 
 export function clearSceneHistory() {
   resetSceneHistoryPauseDepth()
@@ -2154,11 +2154,17 @@ export function clearSceneHistory() {
   useScene.temporal.getState().clear()
   prevPastLength = 0
   prevFutureLength = 0
-  prevNodesSnapshot = null
 }
 
 // Subscribe to the temporal store (Undo/Redo events)
-useScene.temporal.subscribe((state) => {
+useScene.temporal.subscribe((state, previousState) => {
+  // Zundo mutates its source stack before writing the scene. Reconciliation's
+  // pause/resume notifications must not advance our pre-jump stack lengths.
+  if (
+    state.pastStates === previousState.pastStates &&
+    state.futureStates === previousState.futureStates
+  )
+    return
   const currentPastLength = state.pastStates.length
   const currentFutureLength = state.futureStates.length
 
@@ -2168,8 +2174,13 @@ useScene.temporal.subscribe((state) => {
   const didRedo = currentPastLength > prevPastLength && currentFutureLength < prevFutureLength
 
   if (didUndo || didRedo) {
-    // Capture the previous snapshot before RAF fires
-    const snapshotBefore = prevNodesSnapshot
+    // Capture both layouts before another synchronous jump can replace them.
+    // The state pushed onto the opposite stack includes history-paused derived
+    // writes (such as stair rise), unlike a snapshot saved at the last edit.
+    const snapshotBefore = didUndo
+      ? state.futureStates[prevFutureLength]?.nodes
+      : state.pastStates[prevPastLength]?.nodes
+    const snapshotAfter = useScene.getState().nodes
 
     // Defer to a microtask so the scene store has settled before we diff,
     // but still mark walls/items dirty before the next paint.
@@ -2178,31 +2189,7 @@ useScene.temporal.subscribe((state) => {
       const { markDirty } = useScene.getState()
 
       if (snapshotBefore) {
-        // Diff: only mark nodes that actually changed
-        for (const [id, node] of Object.entries(currentNodes) as [AnyNodeId, AnyNode][]) {
-          if (snapshotBefore[id] !== node) {
-            markDirty(id)
-            // Also mark parent so merged geometries update
-            if (node.parentId) markDirty(node.parentId as AnyNodeId)
-          }
-        }
-        // Nodes that were deleted (exist in prev but not current)
-        for (const [id, node] of Object.entries(snapshotBefore) as [AnyNodeId, AnyNode][]) {
-          if (!currentNodes[id]) {
-            const parentId = node.parentId as AnyNodeId | undefined
-            if (parentId) {
-              markDirty(parentId)
-              // Mark sibling nodes dirty so they can update their geometry
-              // (e.g. adjacent walls need to recalculate miter/junction geometry)
-              const parent = currentNodes[parentId]
-              if (parent && 'children' in parent && Array.isArray(parent.children)) {
-                for (const childId of parent.children) {
-                  markDirty(childId as AnyNodeId)
-                }
-              }
-            }
-          }
-        }
+        for (const id of getHistoryDirtyNodeIds(snapshotBefore, snapshotAfter)) markDirty(id)
       } else {
         // No snapshot to diff against — fall back to marking all
         for (const node of Object.values(currentNodes)) {
@@ -2220,8 +2207,7 @@ useScene.temporal.subscribe((state) => {
     })
   }
 
-  // Update tracked lengths and snapshot
+  // Update tracked lengths
   prevPastLength = currentPastLength
   prevFutureLength = currentFutureLength
-  prevNodesSnapshot = useScene.getState().nodes
 })
diff --git a/packages/editor/src/lib/history.test.ts b/packages/editor/src/lib/history.test.ts
index f356459afb..b9f5b2dbab 100644
--- a/packages/editor/src/lib/history.test.ts
+++ b/packages/editor/src/lib/history.test.ts
@@ -1,4 +1,6 @@
 import { afterEach, beforeEach, describe, expect, mock, test } from 'bun:test'
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs'
+import { join, resolve } from 'node:path'
 import {
   type AnyNode,
   type AnyNodeId,
@@ -192,3 +194,266 @@ describe('editor history controller', () => {
     expect(observed).toEqual(['collaborative', 'collaborative', 'standalone'])
   })
 })
+
+function runSourceHistoryTest(body: string) {
+  const cache = join(import.meta.dir, '.turbo')
+  mkdirSync(cache, { recursive: true })
+  const directory = mkdtempSync(join(cache, 'history-'))
+  const probe = join(directory, 'probe.ts')
+  try {
+    writeFileSync(
+      probe,
+      `
+      import assert from 'node:assert/strict'
+      import { mock } from 'bun:test'
+      globalThis.requestAnimationFrame = callback => { callback(0); return 0 }
+      globalThis.cancelAnimationFrame = () => {}
+      const core = await import(${JSON.stringify(resolve(import.meta.dir, '../../..', 'core/src/index.ts'))})
+      mock.module('@pascal-app/core', () => core)
+      const { useScene: scene, clearSceneHistory, useLiveTransforms: transforms, useLiveNodeOverrides: overrides } = core
+      const { runUndo, runRedo, installHistoryCommandDelegate } = await import(${JSON.stringify(resolve(import.meta.dir, 'history.ts'))})
+      const level = core.LevelNode.parse({ id: 'level_history_source' })
+      const wall = core.WallNode.parse({ id: 'wall_history_source', parentId: level.id, start: [0,0], end: [4,0] })
+      const remote = core.WallNode.parse({ id: 'wall_remote_source', parentId: level.id, start: [20,0], end: [24,0] })
+      const opening = core.DoorNode.parse({ id: 'door_history_source', parentId: wall.id, wallId: wall.id })
+      const slab = core.SlabNode.parse({ id: 'slab_history_source', parentId: level.id, polygon: [[0,0],[4,0],[4,4],[0,4]] })
+      const baseline = Object.fromEntries([level, { ...wall, children: [opening.id] }, remote, opening, slab].map(node => [node.id, node]))
+      scene.setState({ nodes: baseline, dirtyNodes: new Set(), readOnly: false, materials: {}, collections: {}, rootNodeIds: [level.id] })
+      clearSceneHistory()
+      const flush = async () => { await Promise.resolve(); await Promise.resolve() }
+      const clean = () => scene.getState().dirtyNodes.clear()
+      const dirty = id => scene.getState().dirtyNodes.has(id)
+      const edit = (id, patch) => scene.getState().updateNode(id, patch)
+      ${body}
+    `,
+    )
+    const result = Bun.spawnSync([process.execPath, probe], { stdout: 'pipe', stderr: 'pipe' })
+    expect({ code: result.exitCode, stderr: result.stderr.toString() }).toEqual({
+      code: 0,
+      stderr: '',
+    })
+  } finally {
+    rmSync(directory, { recursive: true, force: true })
+  }
+}
+
+describe('standalone history source invalidation', () => {
+  test('actual undo/redo keeps unchanged nodes clean and restores exact wall data on repeated jumps', () => {
+    runSourceHistoryTest(`
+      edit(wall.id, { start: [0,2], end: [4,2] })
+      const moved = scene.getState().nodes
+      for (let i = 0; i < 3; i++) {
+        clean(); runUndo(); await flush()
+        assert.equal(scene.getState().nodes[wall.id], baseline[wall.id])
+        assert(dirty(wall.id)); assert(!dirty(remote.id)); assert(!dirty(slab.id))
+        clean(); runRedo(); await flush()
+        assert.equal(scene.getState().nodes[wall.id], moved[wall.id])
+        assert(dirty(wall.id)); assert(!dirty(remote.id)); assert(!dirty(slab.id))
+      }
+    `)
+  })
+
+  test('unchanged transform/override targets and hosted parents restore after clear, including stair holes', () => {
+    runSourceHistoryTest(`
+      edit(level.id, { name: 'Changed' })
+      transforms.getState().set(remote.id, { position: [1,0,0], rotation: 0 })
+      overrides.getState().set(opening.id, { width: 2 })
+      const controller = core.createSurfaceOpeningPreviewController()
+      controller.apply([{ id: slab.id, data: { holes: [[[1,1],[2,1],[2,2]]] } }])
+      clean(); runUndo(); await flush()
+      for (const id of [remote.id, opening.id, wall.id, slab.id]) assert(dirty(id), id)
+      assert.equal(scene.getState().nodes[remote.id], baseline[remote.id])
+      assert.equal(transforms.getState().transforms.size, 0)
+      assert.equal(overrides.getState().overrides.size, 0)
+      controller.clear()
+    `)
+  })
+
+  test('opening reparent dirties old and new walls on undo and redo', () => {
+    runSourceHistoryTest(`
+      edit(opening.id, { parentId: remote.id, wallId: remote.id })
+      for (const jump of [runUndo, runRedo]) {
+        clean(); jump(); await flush()
+        for (const id of [wall.id, remote.id, opening.id]) assert(dirty(id), id)
+      }
+    `)
+  })
+
+  test('delete/restore of a subtree leaves no deleted dirty ids or live entries', () => {
+    runSourceHistoryTest(`
+      scene.getState().deleteNode(wall.id)
+      clean(); runUndo(); await flush()
+      assert.equal(scene.getState().nodes[opening.id], baseline[opening.id])
+      assert(dirty(wall.id)); assert(dirty(opening.id))
+      transforms.getState().set(opening.id, { position: [1,0,0], rotation: 0 })
+      scene.getState().markDirty(opening.id)
+      runRedo(); await flush()
+      assert(!scene.getState().nodes[wall.id]); assert(!scene.getState().nodes[opening.id])
+      assert(!dirty(wall.id)); assert(!dirty(opening.id))
+      assert.equal(transforms.getState().transforms.size, 0)
+    `)
+  })
+
+  test('synchronous jumps preserve intermediate wall layouts until their microtasks flush', () => {
+    runSourceHistoryTest(`
+      edit(wall.id, { start: [16,0], end: [20,0] })
+      runUndo(); await flush(); clean()
+      runRedo(); runUndo(); await flush()
+      assert(dirty(remote.id))
+      assert.equal(scene.getState().nodes[wall.id], baseline[wall.id])
+    `)
+  })
+
+  test('empty commands and collaborative delegates retain ownership of live previews and dirtiness', () => {
+    runSourceHistoryTest(`
+      transforms.getState().set(remote.id, { position: [1,0,0], rotation: 0 })
+      overrides.getState().set(opening.id, { width: 2 })
+      clean()
+      assert.equal(runUndo().kind, 'empty'); assert.equal(runRedo().kind, 'empty')
+      edit(wall.id, { thickness: 0.4 }); clean()
+      const changed = scene.getState().nodes
+      let undo = 0, redo = 0
+      const stop = installHistoryCommandDelegate({
+        getState: () => ({ canUndo: true, canRedo: true, mode: 'collaborative', status: 'ready' }),
+        subscribe: () => () => {},
+        undo: () => { undo++; return { kind: 'applied', persistence: 'queued' } },
+        redo: () => { redo++; return { kind: 'empty' } },
+      })
+      runUndo(); runRedo(); await flush(); stop()
+      assert.equal(undo, 1); assert.equal(redo, 1)
+      assert.equal(scene.getState().nodes, changed)
+      assert.equal(scene.getState().dirtyNodes.size, 0)
+      assert.equal(transforms.getState().transforms.size, 1)
+      assert.equal(overrides.getState().overrides.size, 1)
+    `)
+  })
+  test('one-wall undo releases only its openings and neighbour openings from the real batch store', () => {
+    runSourceHistoryTest(`
+      const { Group, Mesh, MeshBasicMaterial, BoxGeometry } = await import('three')
+      const viewer = await import('@pascal-app/viewer')
+      const { captureChangedNodes, runBatchFrame, resetNodeBatchState } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../nodes/src/shared/node-batch/system.tsx'))})
+      const root = new Group()
+      core.sceneRegistry.nodes.set(level.id, root)
+      core.sceneRegistry.byType.level.add(level.id)
+      const material = new MeshBasicMaterial()
+      const meshes = []
+      const walls = [wall, { ...wall, id: 'wall_neighbor', start: [4,0], end: [4,4] }, remote, { ...remote, id: 'wall_far', start: [30,0], end: [34,0] }]
+      const nodes = { [level.id]: level }
+      walls.forEach((host, i) => {
+        const door = core.DoorNode.parse({ id: 'door_batch_' + i, parentId: host.id })
+        nodes[host.id] = { ...host, children: [door.id] }
+        nodes[door.id] = door
+        const mesh = new Mesh(new BoxGeometry(), material)
+        meshes.push(mesh); root.add(mesh)
+        core.sceneRegistry.nodes.set(door.id, mesh)
+        core.sceneRegistry.byType.door.add(door.id)
+      })
+      scene.setState({ nodes }); clearSceneHistory()
+      edit(wall.id, { start: [0,2], end: [4,2] }); clean()
+      viewer.useViewer.setState({ externalSelectedIds: [], previewSelectedIds: [], hoveredId: null, selection: { ...viewer.useViewer.getState().selection, selectedIds: [], levelId: null } })
+      let now = 0
+      performance.now = () => now
+      const wake = { current: null }
+      const frame = () => runBatchFrame(() => {}, wake)
+      frame(); now += 181; frame()
+      assert(meshes.every(mesh => !mesh.layers.isEnabled(viewer.SCENE_LAYER)))
+      const batch = root.children.find(child => child.name === 'item-batch')
+      assert.equal(batch.instanceCount, 4)
+      runUndo(); await flush()
+      captureChangedNodes(); clean(); frame()
+      assert.deepEqual(meshes.map(mesh => mesh.layers.isEnabled(viewer.SCENE_LAYER)), [true, true, false, false])
+      assert.equal(batch.instanceCount, 2)
+      now += 181; frame()
+      assert.equal(batch.instanceCount, 4)
+      assert(meshes.every(mesh => !mesh.layers.isEnabled(viewer.SCENE_LAYER)))
+      resetNodeBatchState(); if (wake.current) clearTimeout(wake.current)
+    `)
+  })
+
+  test('mounted slab and space subscriptions run on temporal writes without swallowing the wall diff', () => {
+    runSourceHistoryTest(`
+      const react = await import('react')
+      const effects = []
+      mock.module('react', () => ({ ...react, useEffect: effect => effects.push(effect) }))
+      const { default: SlabSystems } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../nodes/src/slab/system.tsx'))})
+      SlabSystems()
+      const stopSlabs = effects[0]()
+      let publications = 0
+      const editor = { spaces: {}, setSpaces: spaces => { editor.spaces = spaces; publications++ } }
+      const stopSpaces = core.initSpaceDetectionSync(scene, { getState: () => editor })
+      edit(wall.id, { start: [0,2], end: [4,2] })
+      clean(); const previousPublications = publications
+      runUndo()
+      assert(dirty(slab.id))
+      assert(publications > previousPublications)
+      await flush()
+      assert(dirty(wall.id))
+      assert(!dirty(remote.id))
+      stopSpaces(); stopSlabs()
+    `)
+  })
+
+  test('stair preview cleanup captures holes republished during the first clear', () => {
+    runSourceHistoryTest(`
+      edit(level.id, { name: 'Changed' })
+      transforms.getState().set(wall.id, { position: [1,0,0], rotation: 0 })
+      let published = false
+      const stop = overrides.subscribe(state => {
+        if (published || state.overrides.size || !transforms.getState().transforms.size) return
+        published = true
+        overrides.getState().set(slab.id, { holes: [[[1,1],[2,1],[2,2]]] })
+      })
+      clean(); runUndo(); await flush(); stop()
+      assert(published)
+      assert.equal(overrides.getState().overrides.size, 0)
+      assert(dirty(slab.id))
+    `)
+  })
+  test('the wall geometry harness restores positions, normals, UVs and opening cutouts after undo', () => {
+    runSourceHistoryTest(`
+      const { Mesh } = await import('three')
+      const { generateExtrudedWall } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../viewer/src/systems/wall/wall-system.tsx'))})
+      core.sceneRegistry.nodes.set(wall.id, new Mesh())
+      const geometry = () => {
+        const nodes = scene.getState().nodes
+        const currentWall = nodes[wall.id]
+        const children = currentWall.children.map(id => nodes[id]).filter(Boolean)
+        const mesh = generateExtrudedWall(currentWall, children, core.calculateLevelMiters([currentWall]))
+        const result = Object.fromEntries(['position', 'normal', 'uv'].map(name => [name, Array.from(mesh.getAttribute(name).array)]))
+        mesh.dispose(); return result
+      }
+      const canonical = geometry()
+      for (const [id, patch] of [
+        [wall.id, { thickness: 0.4 }], [wall.id, { end: [7,2] }],
+        [wall.id, { curveOffset: 0.7 }], [opening.id, { position: [2,1,0], width: 1.5 }],
+      ]) {
+        edit(id, patch)
+        assert.notDeepEqual(geometry(), canonical)
+        clean(); runUndo(); await flush()
+        assert(dirty(wall.id))
+        assert.deepEqual(geometry(), canonical)
+      }
+    `)
+  })
+
+  test('the mounted stair subscription restores derived flight heights after a temporal level write', () => {
+    runSourceHistoryTest(`
+      const react = await import('react')
+      const effects = []
+      mock.module('react', () => ({ ...react, useEffect: effect => effects.push(effect), useRef: current => ({ current }) }))
+      const segment = core.StairSegmentNode.parse({ id: 'sseg_history', parentId: 'stair_history', height: 2.5 })
+      const stair = core.StairNode.parse({ id: 'stair_history', parentId: level.id, children: [segment.id] })
+      scene.setState({ nodes: { ...baseline, [level.id]: { ...level, height: 2.5, children: [stair.id] }, [stair.id]: stair, [segment.id]: segment } })
+      const { StairOpeningSystem } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../core/src/systems/stair/stair-opening-system.tsx'))})
+      StairOpeningSystem()
+      const stop = effects[0]()
+      await flush(); clearSceneHistory()
+      edit(level.id, { height: 4 }); await flush()
+      assert.equal(scene.getState().nodes[segment.id].height, 4)
+      clean(); runUndo(); await flush()
+      assert.equal(scene.getState().nodes[segment.id].height, 2.5)
+      assert(dirty(segment.id)); assert(!dirty(remote.id))
+      stop()
+    `)
+  })
+})
diff --git a/packages/editor/src/lib/history.ts b/packages/editor/src/lib/history.ts
index 846d0f8410..58b682986d 100644
--- a/packages/editor/src/lib/history.ts
+++ b/packages/editor/src/lib/history.ts
@@ -1,4 +1,10 @@
-import { emitter, useLiveNodeOverrides, useLiveTransforms, useScene } from '@pascal-app/core'
+import {
+  type AnyNodeId,
+  emitter,
+  useLiveNodeOverrides,
+  useLiveTransforms,
+  useScene,
+} from '@pascal-app/core'
 import { markPerfAction } from '@pascal-app/viewer'
 import useInteractionScope from '../store/use-interaction-scope'
 import { registeredDraftingConfig } from './interaction/registered-drafting'
@@ -65,12 +71,28 @@ function notifyHistoryCommandListeners() {
 }
 
 function refreshSceneAfterHistoryJump() {
+  const previewIds = new Set([
+    ...useLiveTransforms.getState().transforms.keys(),
+    ...useLiveNodeOverrides.getState().overrides.keys(),
+  ])
   useLiveNodeOverrides.getState().clearAll()
   useLiveTransforms.getState().clearAll()
+  // Clearing overrides can republish stair holes while a live transform still
+  // exists. Capture that final publication before clearing it too.
+  const remainingOverrides = useLiveNodeOverrides.getState().overrides
+  if (remainingOverrides.size > 0) {
+    for (const id of remainingOverrides.keys()) previewIds.add(id)
+    useLiveNodeOverrides.getState().clearAll()
+  }
 
   const state = useScene.getState()
-  for (const node of Object.values(state.nodes)) {
+  for (const id of previewIds) {
+    const node = state.nodes[id as AnyNodeId]
+    if (!node) continue
     state.markDirty(node.id)
+    if (node.parentId && state.nodes[node.parentId as AnyNodeId]) {
+      state.markDirty(node.parentId as AnyNodeId)
+    }
   }
 }
 
diff --git a/wiki/architecture/systems.md b/wiki/architecture/systems.md
index 155994669e..267b5ab73a 100644
--- a/wiki/architecture/systems.md
+++ b/wiki/architecture/systems.md
@@ -105,6 +105,29 @@ Any optimization that scopes reconciliation to a subset of nodes or rooms must b
 equivalence with a full level scan. Representative create, update, delete, cascade, split, merge,
 and corridor-enclosure edits must produce the same spaces and surfaces as full reconciliation.
 
+## Undo and redo invalidation
+
+Standalone history jumps clear live transforms and node overrides, including surface-hole
+previews. Only surviving preview targets and their parents receive restoration marks from the
+editor. Empty commands preserve previews, and collaborative delegates own their own refresh.
+
+Core diffs the before/after node snapshots in a microtask before paint. It marks changed nodes,
+old and new parents, wall neighbours in both layouts (scoped to the wall's level), and hosted
+doors/windows/items when wall thickness, height or curvature changes. Deletion retains its
+conservative surviving-sibling refresh and removes marks for missing IDs. Both layouts are
+captured per jump; reconciliation's history pause/resume notifications cannot replace them.
+The cold-start fallback without a previous snapshot remains conservative.
+
+Temporal restoration writes to the scene store, so existing subscriptions still own spatial
+index updates, slab context tracking, space detection, stair rise/openings, elevator openings,
+and level-height dependents. Spatial sync also checks before/after rendered slab boundaries:
+wall bands and sibling seams can change support even when the slab's stored polygon is unchanged.
+Support invalidation uses both layouts so objects on a former boundary re-elevate.
+
+There is no routine whole-scene history refresh or batch reset. The existing priority-1 batch
+snapshot releases affected sources (including dirty walls' openings); untouched members stay
+batched, and affected members rejoin through the normal settle window.
+
 ## Adding a New System
 
 1. Decide the scope:

From 116ade6d789d001e06b19ca450c636983437f1c6 Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 14:26:08 -0400
Subject: [PATCH 02/11] Reset editor state before randomized store tests

---
 packages/editor/src/store/tool-mode.test.ts             | 3 ++-
 packages/editor/src/store/use-interaction-scope.test.ts | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/packages/editor/src/store/tool-mode.test.ts b/packages/editor/src/store/tool-mode.test.ts
index abe47f87be..e21dc120ef 100644
--- a/packages/editor/src/store/tool-mode.test.ts
+++ b/packages/editor/src/store/tool-mode.test.ts
@@ -1,4 +1,4 @@
-import { afterEach, describe, expect, test } from 'bun:test'
+import { afterEach, beforeEach, describe, expect, test } from 'bun:test'
 import useEditor, { normalizePersistedEditorUiState } from './use-editor'
 
 function resetToolMode() {
@@ -8,6 +8,7 @@ function resetToolMode() {
   useEditor.getState().setActivePaintMaterial(null)
 }
 
+beforeEach(resetToolMode)
 afterEach(resetToolMode)
 
 describe('ToolMode transition', () => {
diff --git a/packages/editor/src/store/use-interaction-scope.test.ts b/packages/editor/src/store/use-interaction-scope.test.ts
index 073aa2699e..62686cd617 100644
--- a/packages/editor/src/store/use-interaction-scope.test.ts
+++ b/packages/editor/src/store/use-interaction-scope.test.ts
@@ -1,4 +1,4 @@
-import { afterEach, describe, expect, test } from 'bun:test'
+import { afterEach, beforeEach, describe, expect, test } from 'bun:test'
 import type { AnyNode } from '@pascal-app/core'
 import {
   type ActiveInteractionScope,
@@ -21,6 +21,7 @@ const mockNode = (id: string, type: string): AnyNode => ({ id, type }) as unknow
 function reset() {
   useInteractionScope.getState().end()
 }
+beforeEach(reset)
 afterEach(reset)
 
 describe('use-interaction-scope state machine', () => {

From 2eb0a81520d567411c64bdb6875d76fc03f496b1 Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 14:55:32 -0400
Subject: [PATCH 03/11] Resolve history probe mocks from each consuming package

---
 packages/editor/src/lib/history.test.ts | 41 ++++++++++++++++++++-----
 1 file changed, 33 insertions(+), 8 deletions(-)

diff --git a/packages/editor/src/lib/history.test.ts b/packages/editor/src/lib/history.test.ts
index b9f5b2dbab..816608ee3b 100644
--- a/packages/editor/src/lib/history.test.ts
+++ b/packages/editor/src/lib/history.test.ts
@@ -206,10 +206,35 @@ function runSourceHistoryTest(body: string) {
       `
       import assert from 'node:assert/strict'
       import { mock } from 'bun:test'
+      import { fileURLToPath, pathToFileURL } from 'node:url'
+      const consumers = [
+        ${JSON.stringify(resolve(import.meta.dir, 'history.ts'))},
+        ${JSON.stringify(resolve(import.meta.dir, '../../../core/src/index.ts'))},
+        ${JSON.stringify(resolve(import.meta.dir, '../../../viewer/src/systems/wall/wall-system.tsx'))},
+        ${JSON.stringify(resolve(import.meta.dir, '../../../nodes/src/shared/node-batch/system.tsx'))},
+      ]
+      const sharedPaths = new Map(
+        ['@pascal-app/core', '@pascal-app/viewer', 'react', 'three', '@react-three/fiber'].map(specifier => [
+          specifier,
+          [...new Set(consumers.map(consumer => fileURLToPath(import.meta.resolve(specifier, pathToFileURL(consumer).href))))],
+        ]),
+      )
+      function mockShared(specifier, factory) {
+        for (const path of sharedPaths.get(specifier)) mock.module(path, factory)
+      }
+      async function importShared(specifier) {
+        const module = await import(sharedPaths.get(specifier)[0])
+        mockShared(specifier, () => module)
+        return module
+      }
+      await importShared('react')
+      await importShared('three')
+      await importShared('@react-three/fiber')
       globalThis.requestAnimationFrame = callback => { callback(0); return 0 }
       globalThis.cancelAnimationFrame = () => {}
       const core = await import(${JSON.stringify(resolve(import.meta.dir, '../../..', 'core/src/index.ts'))})
-      mock.module('@pascal-app/core', () => core)
+      mockShared('@pascal-app/core', () => core)
+      await importShared('@pascal-app/viewer')
       const { useScene: scene, clearSceneHistory, useLiveTransforms: transforms, useLiveNodeOverrides: overrides } = core
       const { runUndo, runRedo, installHistoryCommandDelegate } = await import(${JSON.stringify(resolve(import.meta.dir, 'history.ts'))})
       const level = core.LevelNode.parse({ id: 'level_history_source' })
@@ -329,8 +354,8 @@ describe('standalone history source invalidation', () => {
   })
   test('one-wall undo releases only its openings and neighbour openings from the real batch store', () => {
     runSourceHistoryTest(`
-      const { Group, Mesh, MeshBasicMaterial, BoxGeometry } = await import('three')
-      const viewer = await import('@pascal-app/viewer')
+      const { Group, Mesh, MeshBasicMaterial, BoxGeometry } = await importShared('three')
+      const viewer = await importShared('@pascal-app/viewer')
       const { captureChangedNodes, runBatchFrame, resetNodeBatchState } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../nodes/src/shared/node-batch/system.tsx'))})
       const root = new Group()
       core.sceneRegistry.nodes.set(level.id, root)
@@ -372,9 +397,9 @@ describe('standalone history source invalidation', () => {
 
   test('mounted slab and space subscriptions run on temporal writes without swallowing the wall diff', () => {
     runSourceHistoryTest(`
-      const react = await import('react')
+      const react = await importShared('react')
       const effects = []
-      mock.module('react', () => ({ ...react, useEffect: effect => effects.push(effect) }))
+      mockShared('react', () => ({ ...react, useEffect: effect => effects.push(effect) }))
       const { default: SlabSystems } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../nodes/src/slab/system.tsx'))})
       SlabSystems()
       const stopSlabs = effects[0]()
@@ -411,7 +436,7 @@ describe('standalone history source invalidation', () => {
   })
   test('the wall geometry harness restores positions, normals, UVs and opening cutouts after undo', () => {
     runSourceHistoryTest(`
-      const { Mesh } = await import('three')
+      const { Mesh } = await importShared('three')
       const { generateExtrudedWall } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../viewer/src/systems/wall/wall-system.tsx'))})
       core.sceneRegistry.nodes.set(wall.id, new Mesh())
       const geometry = () => {
@@ -438,9 +463,9 @@ describe('standalone history source invalidation', () => {
 
   test('the mounted stair subscription restores derived flight heights after a temporal level write', () => {
     runSourceHistoryTest(`
-      const react = await import('react')
+      const react = await importShared('react')
       const effects = []
-      mock.module('react', () => ({ ...react, useEffect: effect => effects.push(effect), useRef: current => ({ current }) }))
+      mockShared('react', () => ({ ...react, useEffect: effect => effects.push(effect), useRef: current => ({ current }) }))
       const segment = core.StairSegmentNode.parse({ id: 'sseg_history', parentId: 'stair_history', height: 2.5 })
       const stair = core.StairNode.parse({ id: 'stair_history', parentId: level.id, children: [segment.id] })
       scene.setState({ nodes: { ...baseline, [level.id]: { ...level, height: 2.5, children: [stair.id] }, [stair.id]: stair, [segment.id]: segment } })

From 2010986bfe45dbb08b4d13a24e5401894684bacc Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 14:57:50 -0400
Subject: [PATCH 04/11] Restore discarded preview dependency closures on undo
 and redo

---
 packages/core/src/index.ts              |   1 +
 packages/editor/src/lib/history.test.ts | 291 ++++++++----------------
 packages/editor/src/lib/history.ts      |  36 ++-
 wiki/architecture/systems.md            |  10 +-
 4 files changed, 138 insertions(+), 200 deletions(-)

diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index 1d250404a9..83ee9bc6bf 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -311,6 +311,7 @@ export {
   type SceneSnapshot,
   subscribeSceneCommits,
 } from './store/history-control'
+export { getHistoryDirtyNodeIds } from './store/history-invalidation'
 export {
   type ControlValue,
   type DoorAnimationState,
diff --git a/packages/editor/src/lib/history.test.ts b/packages/editor/src/lib/history.test.ts
index 816608ee3b..cd5d28971a 100644
--- a/packages/editor/src/lib/history.test.ts
+++ b/packages/editor/src/lib/history.test.ts
@@ -1,199 +1,6 @@
-import { afterEach, beforeEach, describe, expect, mock, test } from 'bun:test'
+import { describe, expect, test } from 'bun:test'
 import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs'
 import { join, resolve } from 'node:path'
-import {
-  type AnyNode,
-  type AnyNodeId,
-  BuildingNode,
-  clearSceneHistory,
-  emitter,
-  LevelNode,
-  nodeRegistry,
-  useScene,
-} from '@pascal-app/core'
-import useInteractionScope from '../store/use-interaction-scope'
-import {
-  getHistoryCommandState,
-  installHistoryCommandDelegate,
-  runRedo,
-  runUndo,
-  shouldCancelDraftOnHistoryJump,
-  subscribeHistoryCommandState,
-} from './history'
-
-type RafFn = (cb: (time: number) => void) => number
-;(globalThis as unknown as { requestAnimationFrame?: RafFn }).requestAnimationFrame ??= (cb) => {
-  cb(0)
-  return 0
-}
-;(globalThis as unknown as { cancelAnimationFrame?: (id: number) => void }).cancelAnimationFrame ??=
-  () => {}
-
-const BUILDING_ID = 'building_history_controller' as AnyNodeId
-const LEVEL_ID = 'level_history_controller' as AnyNodeId
-let disposeController = () => {}
-let restoreRegistry = () => {}
-
-function levelNumber(): number {
-  return (useScene.getState().nodes[LEVEL_ID] as { level: number }).level
-}
-
-describe('editor history controller', () => {
-  beforeEach(() => {
-    disposeController()
-    disposeController = () => {}
-    restoreRegistry()
-    restoreRegistry = nodeRegistry._snapshot()
-    useInteractionScope.getState().end()
-    const level = LevelNode.parse({
-      id: LEVEL_ID,
-      parentId: BUILDING_ID,
-      children: [],
-      level: 0,
-    })
-    const building = BuildingNode.parse({
-      id: BUILDING_ID,
-      parentId: null,
-      children: [LEVEL_ID],
-    })
-    useScene.setState({
-      nodes: { [BUILDING_ID]: building, [LEVEL_ID]: level },
-      rootNodeIds: [BUILDING_ID],
-      dirtyNodes: new Set<AnyNodeId>(),
-      collections: {},
-      materials: {},
-      readOnly: false,
-    } as never)
-    clearSceneHistory()
-    useScene.getState().updateNode(LEVEL_ID, { level: 1 } as Partial<AnyNode>)
-  })
-
-  afterEach(() => {
-    disposeController()
-    disposeController = () => {}
-    restoreRegistry()
-    restoreRegistry = () => {}
-    useInteractionScope.getState().end()
-  })
-
-  test('cancels history jumps only when the drafted kind opts in', () => {
-    const onCancel = mock(() => {})
-    emitter.on('tool:cancel', onCancel)
-    try {
-      useInteractionScope.getState().begin({ kind: 'drafting', tool: 'plain-draft' })
-      expect(shouldCancelDraftOnHistoryJump()).toBe(false)
-
-      nodeRegistry._register({
-        kind: 'registered-draft',
-        schemaVersion: 1,
-        drafting: { cancelOnHistoryJump: true },
-      } as never)
-      useInteractionScope.getState().begin({ kind: 'drafting', tool: 'registered-draft' })
-      expect(shouldCancelDraftOnHistoryJump()).toBe(true)
-
-      runUndo()
-      expect(onCancel).toHaveBeenCalledTimes(1)
-    } finally {
-      emitter.off('tool:cancel', onCancel)
-    }
-  })
-
-  test('delegates undo and redo while a host delegate is installed', () => {
-    const undo = mock(() => ({ kind: 'applied', persistence: 'queued' }) as const)
-    const redo = mock(() => ({ kind: 'empty' }) as const)
-    disposeController = installHistoryCommandDelegate({
-      getState: () => ({
-        canRedo: false,
-        canUndo: true,
-        mode: 'collaborative',
-        status: 'syncing',
-      }),
-      redo,
-      subscribe: () => () => {},
-      undo,
-    })
-
-    expect(runUndo()).toEqual({ kind: 'applied', persistence: 'queued' })
-    expect(runRedo()).toEqual({ kind: 'empty' })
-    expect(getHistoryCommandState()).toEqual({
-      canRedo: false,
-      canUndo: true,
-      mode: 'collaborative',
-      status: 'syncing',
-    })
-
-    expect(undo).toHaveBeenCalledTimes(1)
-    expect(redo).toHaveBeenCalledTimes(1)
-    expect(levelNumber()).toBe(1)
-    expect(useScene.temporal.getState().pastStates).toHaveLength(1)
-  })
-
-  test('falls back to standalone Zundo undo and redo when no controller is installed', () => {
-    expect(runUndo()).toEqual({ kind: 'applied', persistence: 'local' })
-    expect(levelNumber()).toBe(0)
-    expect(useScene.temporal.getState().futureStates).toHaveLength(1)
-
-    expect(runRedo()).toEqual({ kind: 'applied', persistence: 'local' })
-    expect(levelNumber()).toBe(1)
-    expect(useScene.temporal.getState().pastStates).toHaveLength(1)
-  })
-
-  test('an older cleanup cannot uninstall a newer controller', () => {
-    const firstUndo = mock(() => {})
-    const delegate = (undo: () => void) => ({
-      getState: () => ({
-        canRedo: false,
-        canUndo: true,
-        mode: 'collaborative' as const,
-        status: 'ready' as const,
-      }),
-      redo: () => ({ kind: 'empty' as const }),
-      subscribe: () => () => {},
-      undo: () => {
-        undo()
-        return { kind: 'applied' as const, persistence: 'queued' as const }
-      },
-    })
-    const stopFirst = installHistoryCommandDelegate(delegate(firstUndo))
-    const secondUndo = mock(() => {})
-    disposeController = installHistoryCommandDelegate(delegate(secondUndo))
-
-    stopFirst()
-    runUndo()
-
-    expect(firstUndo).toHaveBeenCalledTimes(0)
-    expect(secondUndo).toHaveBeenCalledTimes(1)
-  })
-
-  test('publishes delegate state changes and restores standalone availability on teardown', () => {
-    const listeners = new Set<() => void>()
-    const observed: string[] = []
-    const unsubscribe = subscribeHistoryCommandState(() => {
-      observed.push(getHistoryCommandState().mode)
-    })
-    disposeController = installHistoryCommandDelegate({
-      getState: () => ({
-        canRedo: false,
-        canUndo: true,
-        mode: 'collaborative',
-        status: 'offline',
-      }),
-      redo: () => ({ kind: 'empty' }),
-      subscribe: (listener) => {
-        listeners.add(listener)
-        return () => listeners.delete(listener)
-      },
-      undo: () => ({ kind: 'applied', persistence: 'queued' }),
-    })
-
-    for (const listener of listeners) listener()
-    disposeController()
-    disposeController = () => {}
-    unsubscribe()
-
-    expect(observed).toEqual(['collaborative', 'collaborative', 'standalone'])
-  })
-})
 
 function runSourceHistoryTest(body: string) {
   const cache = join(import.meta.dir, '.turbo')
@@ -236,7 +43,8 @@ function runSourceHistoryTest(body: string) {
       mockShared('@pascal-app/core', () => core)
       await importShared('@pascal-app/viewer')
       const { useScene: scene, clearSceneHistory, useLiveTransforms: transforms, useLiveNodeOverrides: overrides } = core
-      const { runUndo, runRedo, installHistoryCommandDelegate } = await import(${JSON.stringify(resolve(import.meta.dir, 'history.ts'))})
+      const { runUndo, runRedo, installHistoryCommandDelegate, getHistoryCommandState, shouldCancelDraftOnHistoryJump, subscribeHistoryCommandState } = await import(${JSON.stringify(resolve(import.meta.dir, 'history.ts'))})
+      const { default: useInteractionScope } = await import(${JSON.stringify(resolve(import.meta.dir, '../store/use-interaction-scope.ts'))})
       const level = core.LevelNode.parse({ id: 'level_history_source' })
       const wall = core.WallNode.parse({ id: 'wall_history_source', parentId: level.id, start: [0,0], end: [4,0] })
       const remote = core.WallNode.parse({ id: 'wall_remote_source', parentId: level.id, start: [20,0], end: [24,0] })
@@ -294,6 +102,51 @@ describe('standalone history source invalidation', () => {
     `)
   })
 
+  test.each([
+    true,
+    false,
+  ])('discarded preview neighbours rebuild after undo/redo (joined: %s)', (joined) => {
+    runSourceHistoryTest(`
+      const react = await importShared('react')
+      mockShared('react', () => ({ ...react, useEffect: () => {} }))
+      const frames = []
+      const fiber = await importShared('@react-three/fiber')
+      mockShared('@react-three/fiber', () => ({ ...fiber, useFrame: frame => frames.push(frame) }))
+      const selector = store => Object.assign(fn => fn(store.getState()), store)
+      mockShared('@pascal-app/core', () => ({ ...core, useScene: selector(scene), useLiveNodeOverrides: selector(overrides) }))
+      const { Mesh } = await importShared('three')
+      const { WallSystem, getPendingWallRebuildCount } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../viewer/src/systems/wall/wall-system.tsx'))})
+      const neighbor = { ...remote, start: [8,0], end: [8,4] }
+      scene.setState({ nodes: { ...baseline, [level.id]: { ...level, children: [wall.id, neighbor.id] }, [neighbor.id]: neighbor } })
+      clearSceneHistory()
+      const a = new Mesh(), b = new Mesh()
+      core.sceneRegistry.nodes.set(wall.id, a)
+      core.sceneRegistry.nodes.set(neighbor.id, b)
+      let now = 0
+      performance.now = () => now
+      WallSystem()
+      const frame = () => { now += 100; frames[0]() }
+      scene.getState().markDirty(wall.id); scene.getState().markDirty(neighbor.id)
+      frame(); frame(); clean()
+      const canonical = Array.from(b.geometry.getAttribute('position').array)
+      edit(level.id, { name: 'Unrelated edit' })
+      for (const jump of [runUndo, runRedo]) {
+        overrides.getState().set(wall.id, { start: [4,0], end: [${joined ? 8 : 6},0] })
+        scene.getState().markDirty(wall.id)
+        frame(); frame()
+        assert.equal(getPendingWallRebuildCount(), 0)
+        const preview = Array.from(b.geometry.getAttribute('position').array)
+        ${joined ? 'assert.notDeepEqual(preview, canonical)' : 'assert.deepEqual(preview, canonical)'}
+        clean(); jump(); await flush()
+        assert(dirty(wall.id))
+        assert.equal(dirty(neighbor.id), ${joined})
+        assert.equal(overrides.getState().overrides.size, 0)
+        frame(); frame()
+        assert.deepEqual(Array.from(b.geometry.getAttribute('position').array), canonical)
+      }
+    `)
+  })
+
   test('opening reparent dirties old and new walls on undo and redo', () => {
     runSourceHistoryTest(`
       edit(opening.id, { parentId: remote.id, wallId: remote.id })
@@ -482,3 +335,51 @@ describe('standalone history source invalidation', () => {
     `)
   })
 })
+
+describe('editor history controller', () => {
+  test('draft cancellation follows the registered kind', () => {
+    runSourceHistoryTest(`
+      let cancelled = 0
+      core.emitter.on('tool:cancel', () => cancelled++)
+      useInteractionScope.getState().begin({ kind: 'drafting', tool: 'plain-draft' })
+      assert.equal(shouldCancelDraftOnHistoryJump(), false)
+      core.nodeRegistry._register({ kind: 'registered-draft', schemaVersion: 1, drafting: { cancelOnHistoryJump: true } })
+      useInteractionScope.getState().begin({ kind: 'drafting', tool: 'registered-draft' })
+      assert.equal(shouldCancelDraftOnHistoryJump(), true)
+      edit(level.id, { level: 1 }); runUndo()
+      assert.equal(cancelled, 1)
+    `)
+  })
+
+  test('delegates publish availability and an older cleanup cannot uninstall the current delegate', () => {
+    runSourceHistoryTest(`
+      edit(level.id, { level: 1 })
+      const observed = []
+      const unsubscribe = subscribeHistoryCommandState(() => observed.push(getHistoryCommandState().mode))
+      const listeners = new Set()
+      let firstCalls = 0, secondCalls = 0
+      const delegate = undo => ({
+        getState: () => ({ canRedo: false, canUndo: true, mode: 'collaborative', status: 'syncing' }),
+        redo: () => ({ kind: 'empty' }),
+        subscribe: listener => { listeners.add(listener); return () => listeners.delete(listener) },
+        undo,
+      })
+      const stopFirst = installHistoryCommandDelegate(delegate(() => { firstCalls++; return { kind: 'empty' } }))
+      const stopSecond = installHistoryCommandDelegate(delegate(() => { secondCalls++; return { kind: 'applied', persistence: 'queued' } }))
+      stopFirst()
+      assert.deepEqual(runUndo(), { kind: 'applied', persistence: 'queued' })
+      assert.deepEqual(runRedo(), { kind: 'empty' })
+      assert.equal(firstCalls, 0); assert.equal(secondCalls, 1)
+      assert.equal(scene.getState().nodes[level.id].level, 1)
+      assert.equal(scene.temporal.getState().pastStates.length, 1)
+      assert.deepEqual(getHistoryCommandState(), { canRedo: false, canUndo: true, mode: 'collaborative', status: 'syncing' })
+      for (const listener of listeners) listener()
+      stopSecond(); unsubscribe()
+      assert.deepEqual(observed, ['collaborative', 'collaborative', 'collaborative', 'standalone'])
+      assert.deepEqual(runUndo(), { kind: 'applied', persistence: 'local' })
+      assert.equal(scene.getState().nodes[level.id].level, 0)
+      assert.deepEqual(runRedo(), { kind: 'applied', persistence: 'local' })
+      assert.equal(scene.getState().nodes[level.id].level, 1)
+    `)
+  })
+})
diff --git a/packages/editor/src/lib/history.ts b/packages/editor/src/lib/history.ts
index 58b682986d..d14108888d 100644
--- a/packages/editor/src/lib/history.ts
+++ b/packages/editor/src/lib/history.ts
@@ -1,6 +1,8 @@
 import {
+  type AnyNode,
   type AnyNodeId,
   emitter,
+  getHistoryDirtyNodeIds,
   useLiveNodeOverrides,
   useLiveTransforms,
   useScene,
@@ -70,11 +72,30 @@ function notifyHistoryCommandListeners() {
   for (const listener of [...historyCommandListeners]) listener()
 }
 
-function refreshSceneAfterHistoryJump() {
+function capturePreviewLayout() {
+  const overrides = useLiveNodeOverrides.getState().overrides
+  if (overrides.size === 0) return null
+  const nodes = { ...useScene.getState().nodes }
+  for (const [id, values] of overrides) {
+    const node = nodes[id as AnyNodeId]
+    if (node) nodes[node.id] = { ...node, ...values } as AnyNode
+  }
+  return nodes
+}
+
+function refreshSceneAfterHistoryJump(previewLayout: Record<string, AnyNode> | null) {
+  const target = useScene.getState().nodes
+  const previewDirty = previewLayout
+    ? getHistoryDirtyNodeIds(previewLayout, target)
+    : new Set<AnyNodeId>()
   const previewIds = new Set([
     ...useLiveTransforms.getState().transforms.keys(),
     ...useLiveNodeOverrides.getState().overrides.keys(),
   ])
+  const currentPreviewLayout = capturePreviewLayout()
+  if (currentPreviewLayout) {
+    for (const id of getHistoryDirtyNodeIds(currentPreviewLayout, target)) previewDirty.add(id)
+  }
   useLiveNodeOverrides.getState().clearAll()
   useLiveTransforms.getState().clearAll()
   // Clearing overrides can republish stair holes while a live transform still
@@ -82,10 +103,17 @@ function refreshSceneAfterHistoryJump() {
   const remainingOverrides = useLiveNodeOverrides.getState().overrides
   if (remainingOverrides.size > 0) {
     for (const id of remainingOverrides.keys()) previewIds.add(id)
+    const remainingLayout = capturePreviewLayout()
+    if (remainingLayout) {
+      for (const id of getHistoryDirtyNodeIds(remainingLayout, target)) previewDirty.add(id)
+    }
     useLiveNodeOverrides.getState().clearAll()
   }
 
   const state = useScene.getState()
+  for (const id of previewDirty) {
+    if (state.nodes[id]) state.markDirty(id)
+  }
   for (const id of previewIds) {
     const node = state.nodes[id as AnyNodeId]
     if (!node) continue
@@ -112,8 +140,9 @@ export function runUndo(): HistoryCommandResult {
   }
   if (useScene.temporal.getState().pastStates.length === 0) return { kind: 'empty' }
   markPerfAction('undo')
+  const previewLayout = capturePreviewLayout()
   useScene.temporal.getState().undo()
-  refreshSceneAfterHistoryJump()
+  refreshSceneAfterHistoryJump(previewLayout)
   return { kind: 'applied', persistence: 'local' }
 }
 
@@ -126,8 +155,9 @@ export function runRedo(): HistoryCommandResult {
   }
   if (useScene.temporal.getState().futureStates.length === 0) return { kind: 'empty' }
   markPerfAction('redo')
+  const previewLayout = capturePreviewLayout()
   useScene.temporal.getState().redo()
-  refreshSceneAfterHistoryJump()
+  refreshSceneAfterHistoryJump(previewLayout)
   return { kind: 'applied', persistence: 'local' }
 }
 
diff --git a/wiki/architecture/systems.md b/wiki/architecture/systems.md
index 267b5ab73a..ca060e345a 100644
--- a/wiki/architecture/systems.md
+++ b/wiki/architecture/systems.md
@@ -108,8 +108,14 @@ and corridor-enclosure edits must produce the same spaces and surfaces as full r
 ## Undo and redo invalidation
 
 Standalone history jumps clear live transforms and node overrides, including surface-hole
-previews. Only surviving preview targets and their parents receive restoration marks from the
-editor. Empty commands preserve previews, and collaborative delegates own their own refresh.
+previews. Before a jump, the editor captures the effective layout by merging live overrides
+onto committed nodes. Before clearing previews it runs the same pure dependency closure used
+for committed history snapshots, with that effective layout as `before` and the committed
+target as `after`: wall neighbours in either layout and hosted children on host dimension
+changes must rebuild even when only the discarded preview connected them. Overrides published
+during restoration/cleanup also contribute their closure before being cleared. Surviving live
+transform targets and their parents receive restoration marks too. Empty commands preserve
+previews, and collaborative delegates own their own refresh.
 
 Core diffs the before/after node snapshots in a microtask before paint. It marks changed nodes,
 old and new parents, wall neighbours in both layouts (scoped to the wall's level), and hosted

From e7b215ba594f87a878650e32129cb2c84478757d Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 15:02:32 -0400
Subject: [PATCH 05/11] Limit rendered slab invalidation to changed boundary
 bands

---
 .../spatial-grid/spatial-grid-sync.test.ts    |  37 +++++-
 .../hooks/spatial-grid/spatial-grid-sync.ts   | 121 ++++++++++++++----
 .../core/src/store/history-invalidation.ts    |  22 +++-
 wiki/architecture/systems.md                  |   6 +-
 4 files changed, 152 insertions(+), 34 deletions(-)

diff --git a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
index 0241aa3779..e25865cadd 100644
--- a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
+++ b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
@@ -616,8 +616,31 @@ describe('temporal writes update slab support dependencies', () => {
       },
     })
     const remote = { ...item, id: 'item_remote_band', position: [20, 0, 20] } as AnyNode
+    const interior = { ...item, id: 'item_interior_band', position: [2, 0, 2] } as AnyNode
+    const interiorWall = WallNode.parse({
+      id: 'wall_interior_band',
+      parentId: level.id,
+      start: [1, 1],
+      end: [2, 1],
+    })
+    const upper = LevelNode.parse({ id: 'level_other_band', level: 1 })
+    const upperItem = { ...item, id: 'item_upper_band', parentId: upper.id } as AnyNode
+    const upperWall = { ...wall, id: 'wall_upper_band', parentId: upper.id } as AnyNode
+    const upperSlab = { ...slab, id: 'slab_upper_band', parentId: upper.id } as AnyNode
     useScene.setState({
-      nodes: nodesFor(level, wall, slab, item, remote),
+      nodes: nodesFor(
+        level,
+        wall,
+        slab,
+        item,
+        remote,
+        interior,
+        interiorWall,
+        upper,
+        upperItem,
+        upperWall,
+        upperSlab,
+      ),
       dirtyNodes: new Set(),
       readOnly: false,
     })
@@ -644,7 +667,17 @@ describe('temporal writes update slab support dependencies', () => {
       await Promise.resolve()
       expect(useScene.getState().nodes[item.id]).toBe(item)
       expect(useScene.getState().nodes[slab.id]).toBe(slab)
-      expect(useScene.getState().dirtyNodes.has(remote.id)).toBe(false)
+      for (const unaffected of [
+        remote,
+        interior,
+        interiorWall,
+        upper,
+        upperItem,
+        upperWall,
+        upperSlab,
+      ]) {
+        expect(useScene.getState().dirtyNodes.has(unaffected.id)).toBe(false)
+      }
     }
   })
 
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 9b8d35329a..edeeaf224c 100644
--- a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
+++ b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
@@ -1,3 +1,4 @@
+import { subtractPolygonsFromPolygon } from '../../lib/polygon-union'
 import { getRenderableSlabPolygon } from '../../lib/slab-polygon'
 import { isLevelAtSiteDatum, isLevelBaseConsumer } from '../../lib/terrain-support'
 import { nodeRegistry } from '../../registry'
@@ -113,10 +114,10 @@ export function initSpatialGridSync(): () => void {
   const unsubscribeScene = store.subscribe((state, prevState) => {
     if (state.nodes === prevState.nodes) return
     const changedSlabContextLevels = new Set<string>()
-    for (const id of new Set([...Object.keys(prevState.nodes), ...Object.keys(state.nodes)])) {
+    const checkSlabContext = (id: string) => {
       const previous = prevState.nodes[id as AnyNodeId]
       const next = state.nodes[id as AnyNodeId]
-      if (previous === next) continue
+      if (previous === next) return
       const wallChanged =
         (previous?.type === 'wall' || next?.type === 'wall') &&
         (previous?.type !== 'wall' ||
@@ -133,11 +134,16 @@ export function initSpatialGridSync(): () => void {
           previous.parentId !== next.parentId ||
           previous.polygon !== next.polygon ||
           previous.elevation !== next.elevation)
-      if (!(wallChanged || slabChanged)) continue
+      if (!(wallChanged || slabChanged)) return
       if (previous) changedSlabContextLevels.add(resolveLevelId(previous, prevState.nodes))
       if (next) changedSlabContextLevels.add(resolveLevelId(next, state.nodes))
     }
 
+    for (const id in prevState.nodes) checkSlabContext(id)
+    for (const id in state.nodes) {
+      if (!prevState.nodes[id as AnyNodeId]) checkSlabContext(id)
+    }
+
     // Detect added nodes
     for (const [id, node] of Object.entries(state.nodes)) {
       if (!prevState.nodes[id as AnyNode['id']]) {
@@ -246,27 +252,43 @@ export function initSpatialGridSync(): () => void {
 
     // Unchanged slabs can lose an adopted wall band or a sibling seam. Their
     // stored polygons cannot identify objects standing on the former boundary.
-    for (const slab of Object.values(state.nodes)) {
-      if (slab.type !== 'slab') continue
-      const previous = prevState.nodes[slab.id]
-      if (previous?.type !== 'slab') continue
-      if (
-        slab.parentId !== previous.parentId ||
-        slab.polygon !== previous.polygon ||
-        slab.elevation !== previous.elevation ||
-        slab.holes !== previous.holes
-      )
-        continue
-      if (!changedSlabContextLevels.has(resolveLevelId(slab, state.nodes))) continue
-      const beforePolygon = renderableSlabPolygon(previous, prevState.nodes)
-      const afterPolygon = renderableSlabPolygon(slab, state.nodes)
-      if (
-        beforePolygon.length === afterPolygon.length &&
-        beforePolygon.every((point, i) => arraysEqual(point, afterPolygon[i]!))
-      )
-        continue
-      markNodesOverlappingSlab(previous, state.nodes, markDirty, prevState.nodes)
-      markNodesOverlappingSlab(slab, state.nodes, markDirty)
+    if (changedSlabContextLevels.size === 0) return
+    const beforeContext = slabBoundaryContext(prevState.nodes, changedSlabContextLevels)
+    const afterContext = slabBoundaryContext(state.nodes, changedSlabContextLevels)
+    for (const context of afterContext.values()) {
+      for (const slab of context.slabs) {
+        const previous = prevState.nodes[slab.id]
+        if (previous?.type !== 'slab') continue
+        if (
+          slab.parentId !== previous.parentId ||
+          slab.polygon !== previous.polygon ||
+          slab.elevation !== previous.elevation ||
+          slab.holes !== previous.holes
+        )
+          continue
+        const previousContext = beforeContext.get(resolveLevelId(previous, prevState.nodes))!
+        const beforePolygon = cachedSlabPolygon(previous, previousContext)
+        const afterPolygon = cachedSlabPolygon(slab, context)
+        if (
+          beforePolygon.length === afterPolygon.length &&
+          beforePolygon.every((point, i) => arraysEqual(point, afterPolygon[i]!))
+        )
+          continue
+        // Support only changed in the gained/lost bands, not across the slab interior.
+        const changedBands = [
+          ...subtractPolygonsFromPolygon(beforePolygon, [afterPolygon]),
+          ...subtractPolygonsFromPolygon(afterPolygon, [beforePolygon]),
+        ]
+        for (const polygon of changedBands) {
+          markNodesOverlappingPolygon(
+            resolveLevelId(slab, state.nodes),
+            polygon,
+            state.nodes,
+            markDirty,
+            context.consumers,
+          )
+        }
+      }
     }
   })
 
@@ -487,7 +509,17 @@ function markNodesOverlappingSlab(
   const slabLevelId = resolveLevelId(slab, contextNodes)
   const renderedPolygon = renderableSlabPolygon(slab, contextNodes)
 
-  for (const node of Object.values(nodes)) {
+  markNodesOverlappingPolygon(slabLevelId, renderedPolygon, nodes, markDirty)
+}
+
+function markNodesOverlappingPolygon(
+  slabLevelId: string,
+  renderedPolygon: [number, number][],
+  nodes: Record<string, AnyNode>,
+  markDirty: (id: AnyNodeId) => void,
+  candidates: Iterable<AnyNode> = Object.values(nodes),
+) {
+  for (const node of candidates) {
     if (node.type === 'wall') {
       const wall = node as WallNode
       if (resolveLevelId(node, nodes) !== slabLevelId) continue
@@ -537,3 +569,42 @@ function markNodesOverlappingSlab(
     }
   }
 }
+
+type SlabBoundaryContext = {
+  walls: WallNode[]
+  slabs: SlabNode[]
+  consumers: AnyNode[]
+  polygons: Map<string, [number, number][]>
+}
+
+function slabBoundaryContext(nodes: Record<string, AnyNode>, levels: Set<string>) {
+  const contexts = new Map<string, SlabBoundaryContext>()
+  for (const id in nodes) {
+    const node = nodes[id]!
+    const floorPlaced = nodeRegistry.get(node.type)?.capabilities?.floorPlaced
+    if (node.type !== 'wall' && node.type !== 'slab' && !floorPlaced) continue
+    const levelId = resolveLevelId(node, nodes)
+    if (!levels.has(levelId)) continue
+    let context = contexts.get(levelId)
+    if (!context) {
+      context = { walls: [], slabs: [], consumers: [], polygons: new Map() }
+      contexts.set(levelId, context)
+    }
+    if (node.type === 'wall') context.walls.push(node)
+    if (node.type === 'slab') context.slabs.push(node)
+    if (node.type === 'wall' || floorPlaced) context.consumers.push(node)
+  }
+  return contexts
+}
+
+function cachedSlabPolygon(slab: SlabNode, context: SlabBoundaryContext) {
+  let polygon = context.polygons.get(slab.id)
+  if (!polygon) {
+    polygon = getRenderableSlabPolygon(slab, {
+      walls: context.walls,
+      siblingSlabs: context.slabs.filter((sibling) => sibling.id !== slab.id),
+    })
+    context.polygons.set(slab.id, polygon)
+  }
+  return polygon
+}
diff --git a/packages/core/src/store/history-invalidation.ts b/packages/core/src/store/history-invalidation.ts
index f70a98e9d1..5e20d6051e 100644
--- a/packages/core/src/store/history-invalidation.ts
+++ b/packages/core/src/store/history-invalidation.ts
@@ -12,10 +12,10 @@ export function getHistoryDirtyNodeIds(
     if (id && after[id]) dirty.add(id as AnyNodeId)
   }
 
-  for (const id of new Set([...Object.keys(before), ...Object.keys(after)])) {
+  const visitChange = (id: string) => {
     const previous = before[id]
     const next = after[id]
-    if (previous === next) continue
+    if (previous === next) return
     add(id)
     add(previous?.parentId)
     add(next?.parentId)
@@ -42,15 +42,25 @@ export function getHistoryDirtyNodeIds(
     }
   }
 
+  for (const id in before) visitChange(id)
+  for (const id in after) {
+    if (!before[id]) visitChange(id)
+  }
+
   if (changedWalls.size === 0) return dirty
 
   for (const nodes of [before, after]) {
     const wallsByLevel = new Map<string | null, WallNode[]>()
-    for (const node of Object.values(nodes)) {
+    for (const id of changedWalls) {
+      const wall = nodes[id]
+      if (wall?.type === 'wall' && !wallsByLevel.has(wall.parentId)) {
+        wallsByLevel.set(wall.parentId, [])
+      }
+    }
+    for (const id in nodes) {
+      const node = nodes[id]!
       if (node.type === 'wall') {
-        const walls = wallsByLevel.get(node.parentId) ?? []
-        walls.push(node)
-        wallsByLevel.set(node.parentId, walls)
+        wallsByLevel.get(node.parentId)?.push(node)
       }
       if (
         node.parentId &&
diff --git a/wiki/architecture/systems.md b/wiki/architecture/systems.md
index ca060e345a..9e9483a510 100644
--- a/wiki/architecture/systems.md
+++ b/wiki/architecture/systems.md
@@ -128,7 +128,11 @@ Temporal restoration writes to the scene store, so existing subscriptions still
 index updates, slab context tracking, space detection, stair rise/openings, elevator openings,
 and level-height dependents. Spatial sync also checks before/after rendered slab boundaries:
 wall bands and sibling seams can change support even when the slab's stored polygon is unchanged.
-Support invalidation uses both layouts so objects on a former boundary re-elevate.
+Support invalidation tests the gained/lost rendered bands in both layouts, so objects on a
+former boundary re-elevate while consumers in the unchanged interior stay clean. Each pass
+groups affected-level walls, slabs and consumers once and caches each slab's rendered polygon
+once per layout. Discovering changes still scans the snapshots; it does not scan the scene
+again for each candidate slab.
 
 There is no routine whole-scene history refresh or batch reset. The existing priority-1 batch
 snapshot releases affected sources (including dirty walls' openings); untouched members stay

From 44fa3df918283a2a6c738ec8267b732f275b6eeb Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 15:02:32 -0400
Subject: [PATCH 06/11] Cover history support transfers and scoped endpoint
 rebuilds

---
 packages/editor/src/lib/history.test.ts | 149 ++++++++++++++++++++++++
 1 file changed, 149 insertions(+)

diff --git a/packages/editor/src/lib/history.test.ts b/packages/editor/src/lib/history.test.ts
index cd5d28971a..8aa4c77b1a 100644
--- a/packages/editor/src/lib/history.test.ts
+++ b/packages/editor/src/lib/history.test.ts
@@ -248,6 +248,155 @@ describe('standalone history source invalidation', () => {
     `)
   })
 
+  test('endpoint undo/redo releases exactly both endpoint neighbours and their hosted children', () => {
+    runSourceHistoryTest(`
+      const { Group, Mesh, MeshBasicMaterial, BoxGeometry } = await importShared('three')
+      const viewer = await importShared('@pascal-app/viewer')
+      const { captureChangedNodes, runBatchFrame, resetNodeBatchState } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../nodes/src/shared/node-batch/system.tsx'))})
+      const root = new Group()
+      core.sceneRegistry.nodes.set(level.id, root)
+      core.sceneRegistry.byType.level.add(level.id)
+      const material = new MeshBasicMaterial()
+      const meshes = []
+      const walls = [wall, { ...wall, id: 'wall_start', start: [0,0], end: [0,4] }, { ...wall, id: 'wall_old', start: [4,0], end: [4,4] }, { ...wall, id: 'wall_new', start: [6,0], end: [6,4] }, { ...wall, id: 'wall_beyond', start: [6,4], end: [8,4] }, remote]
+      const nodes = { [level.id]: level }
+      walls.forEach((host, i) => {
+        const door = core.DoorNode.parse({ id: 'door_batch_' + i, parentId: host.id })
+        nodes[host.id] = { ...host, children: [door.id] }
+        nodes[door.id] = door
+        const mesh = new Mesh(new BoxGeometry(), material)
+        meshes.push(mesh); root.add(mesh)
+        core.sceneRegistry.nodes.set(door.id, mesh)
+        core.sceneRegistry.byType.door.add(door.id)
+      })
+      scene.setState({ nodes }); clearSceneHistory()
+      edit(wall.id, { end: [6,0] }); clean()
+      viewer.useViewer.setState({ externalSelectedIds: [], previewSelectedIds: [], hoveredId: null, selection: { ...viewer.useViewer.getState().selection, selectedIds: [], levelId: null } })
+      let now = 0
+      performance.now = () => now
+      const wake = { current: null }
+      const frame = () => runBatchFrame(() => {}, wake)
+      frame(); now += 181; frame()
+      assert(meshes.every(mesh => !mesh.layers.isEnabled(viewer.SCENE_LAYER)))
+      const batch = root.children.find(child => child.name === 'item-batch')
+      assert.equal(batch.instanceCount, 6)
+      for (const jump of [runUndo, runRedo]) {
+      clean(); jump(); await flush()
+      assert.deepEqual([...scene.getState().dirtyNodes].sort(), [level.id, ...walls.slice(0,4).map(node => node.id)].sort())
+      captureChangedNodes(); clean(); frame()
+      assert.deepEqual(meshes.map(mesh => mesh.layers.isEnabled(viewer.SCENE_LAYER)), [true, true, true, true, false, false])
+      assert.equal(batch.instanceCount, 2)
+      now += 181; frame()
+      assert.equal(batch.instanceCount, 6)
+      assert(meshes.every(mesh => !mesh.layers.isEnabled(viewer.SCENE_LAYER)))
+      }
+      resetNodeBatchState(); if (wake.current) clearTimeout(wake.current)
+    `)
+  })
+
+  test('all four item supports transfer through undo and redo without touching unrelated hosts', () => {
+    runSourceHistoryTest(`
+      const ceiling = core.CeilingNode.parse({ id: 'ceiling_transfer', parentId: level.id, polygon: slab.polygon })
+      const deck = { ...slab, elevation: 1 }
+      const asset = { id: 'transfer', name: 'transfer', category: 'test', thumbnail: '', src: '/test.glb' }
+      const supports = [
+        { parentId: level.id, supportSlabId: core.GROUND_SUPPORT_ID, asset },
+        { parentId: wall.id, supportSlabId: undefined, asset: { ...asset, attachTo: 'wall-side' } },
+        { parentId: ceiling.id, supportSlabId: undefined, asset: { ...asset, attachTo: 'ceiling' } },
+        { parentId: level.id, supportSlabId: deck.id, asset },
+      ]
+      for (let from = 0; from < supports.length; from++) {
+        for (let to = from + 1; to < supports.length; to++) {
+          const item = core.ItemNode.parse({ id: 'item_transfer', ...supports[from] })
+          scene.setState({ nodes: { ...baseline, [ceiling.id]: ceiling, [deck.id]: deck, [item.id]: item } })
+          clearSceneHistory()
+          edit(item.id, { ...supports[to], position: [2,0,2] })
+          const moved = scene.getState().nodes[item.id]
+          for (const [jump, expected] of [[runUndo, item], [runRedo, moved]]) {
+            clean(); jump(); await flush()
+            assert.equal(scene.getState().nodes[item.id], expected)
+            assert.deepEqual([...scene.getState().dirtyNodes].sort(), [...new Set([item.id, level.id, supports[from].parentId, supports[to].parentId])].sort())
+            assert(!dirty(remote.id)); assert(!dirty(deck.id))
+          }
+        }
+      }
+    `)
+  })
+
+  test('undo and redo re-mark hosted opening proxies and wall-side offsets for real frame rebuilds', () => {
+    runSourceHistoryTest(`
+      const react = await importShared('react')
+      mockShared('react', () => ({ ...react, useEffect: () => {}, useRef: current => ({ current }) }))
+      const frames = []
+      const fiber = await importShared('@react-three/fiber')
+      mockShared('@react-three/fiber', () => ({ ...fiber, useFrame: frame => frames.push(frame) }))
+      const selector = store => Object.assign(fn => fn(store.getState()), store)
+      mockShared('@pascal-app/core', () => ({ ...core, useScene: selector(scene), useLiveNodeOverrides: selector(overrides) }))
+      const viewer = await importShared('@pascal-app/viewer')
+      mock.module(${JSON.stringify(resolve(import.meta.dir, '../../../viewer/src/store/use-viewer.ts'))}, () => ({ default: selector(viewer.useViewer) }))
+      const { Mesh } = await importShared('three')
+      const { DoorSystem } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../viewer/src/systems/door/door-system.tsx'))})
+      const { WindowSystem } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../viewer/src/systems/window/window-system.tsx'))})
+      const { ItemSystem } = await import(${JSON.stringify(resolve(import.meta.dir, '../../../viewer/src/systems/item/item-system.tsx'))})
+      const window = core.WindowNode.parse({ id: 'window_thickness', parentId: wall.id })
+      const item = core.ItemNode.parse({ id: 'item_thickness', parentId: wall.id, side: 'front', asset: { id: 'test', name: 'test', category: 'test', thumbnail: '', src: '/test.glb', attachTo: 'wall-side' } })
+      const children = [opening, window, item]
+      scene.setState({ nodes: { ...baseline, [wall.id]: { ...wall, children: children.map(node => node.id) }, [window.id]: window, [item.id]: item } })
+      const meshes = children.map(node => { const mesh = new Mesh(); mesh.userData.itemModelSettled = true; core.sceneRegistry.nodes.set(node.id, mesh); return mesh })
+      clearSceneHistory()
+      DoorSystem(); WindowSystem(); ItemSystem()
+      const frame = () => frames.forEach(frame => frame())
+      const depths = () => meshes.slice(0, 2).map(mesh => mesh.getObjectByName('cutout').geometry.parameters.depth)
+      const check = thickness => {
+        assert.deepEqual(depths(), [thickness + 0.08, thickness + 0.08])
+        assert.equal(meshes[2].position.z, thickness / 2)
+      }
+      children.forEach(node => scene.getState().markDirty(node.id)); frame(); check(core.getWallThickness(wall))
+      edit(wall.id, { thickness: 0.6 })
+      children.forEach(node => scene.getState().markDirty(node.id)); frame(); check(0.6)
+      for (const [jump, thickness] of [[runUndo, core.getWallThickness(wall)], [runRedo, 0.6]]) {
+        clean(); jump(); await flush()
+        children.forEach(node => assert(dirty(node.id), node.id))
+        assert(!dirty(remote.id)); assert(!dirty(slab.id))
+        frame(); check(thickness)
+        children.forEach(node => assert(!dirty(node.id), node.id))
+      }
+    `)
+  })
+
+  test('undo removes a reconciliation-created side-effect wall and its auto surfaces in one step', () => {
+    runSourceHistoryTest(`
+      const upper = core.LevelNode.parse({ id: 'level_unrelated_side_effect', level: 1 })
+      const walls = [wall, { ...wall, id: 'wall_east', start: [4,0], end: [4,4] }, { ...wall, id: 'wall_north', start: [4,4], end: [0,4] }]
+      const closing = core.WallNode.parse({ id: 'wall_closing', parentId: level.id, start: [0,4], end: [0,0] })
+      const sideEffect = core.WallNode.parse({ id: 'wall_derived', parentId: level.id, start: [4,4], end: [6,4] })
+      scene.setState({ nodes: Object.fromEntries([{ ...level, children: walls.map(node => node.id) }, upper, { ...remote, parentId: upper.id }, ...walls].map(node => [node.id, node])) })
+      const editor = { spaces: {}, setSpaces: spaces => { editor.spaces = spaces } }
+      let created = false
+      const stop = core.initSpaceDetectionSync(scene, { getState: () => editor }, {
+        onTopologyReconcile: () => {
+          if (created) return
+          created = true
+          scene.getState().createNode(sideEffect, level.id)
+        },
+      })
+      clearSceneHistory()
+      scene.getState().createNode(closing, level.id)
+      await flush()
+      assert(created); assert(scene.getState().nodes[sideEffect.id])
+      const surfaces = Object.values(scene.getState().nodes).filter(node => node.type === 'slab' || node.type === 'ceiling')
+      assert(surfaces.length > 0)
+      assert.equal(scene.temporal.getState().pastStates.length, 1)
+      clean(); runUndo(); await flush()
+      for (const node of [closing, sideEffect, ...surfaces]) {
+        assert(!scene.getState().nodes[node.id], node.id)
+        assert(!dirty(node.id), node.id)
+      }
+      assert(dirty('wall_north')); assert(!dirty(remote.id))
+      stop()
+    `)
+  })
+
   test('mounted slab and space subscriptions run on temporal writes without swallowing the wall diff', () => {
     runSourceHistoryTest(`
       const react = await importShared('react')

From db466c05aa9c007c776208a00d48e6f6fec18c8e Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 15:06:54 -0400
Subject: [PATCH 07/11] Pin endpoint history closure with spatial sync mounted

---
 packages/editor/src/lib/history.test.ts | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/packages/editor/src/lib/history.test.ts b/packages/editor/src/lib/history.test.ts
index 8aa4c77b1a..65768e5141 100644
--- a/packages/editor/src/lib/history.test.ts
+++ b/packages/editor/src/lib/history.test.ts
@@ -258,8 +258,8 @@ describe('standalone history source invalidation', () => {
       core.sceneRegistry.byType.level.add(level.id)
       const material = new MeshBasicMaterial()
       const meshes = []
-      const walls = [wall, { ...wall, id: 'wall_start', start: [0,0], end: [0,4] }, { ...wall, id: 'wall_old', start: [4,0], end: [4,4] }, { ...wall, id: 'wall_new', start: [6,0], end: [6,4] }, { ...wall, id: 'wall_beyond', start: [6,4], end: [8,4] }, remote]
-      const nodes = { [level.id]: level }
+      const walls = [wall, { ...wall, id: 'wall_start', start: [0,0], end: [0,4] }, { ...wall, id: 'wall_old', start: [4,0], end: [4,4] }, { ...wall, id: 'wall_new', start: [6,1], end: [6,4] }, { ...wall, id: 'wall_beyond', start: [6,4], end: [8,4] }, remote, { ...wall, id: 'wall_interior', start: [1,1], end: [2,1] }]
+      const nodes = { [level.id]: level, [slab.id]: slab }
       walls.forEach((host, i) => {
         const door = core.DoorNode.parse({ id: 'door_batch_' + i, parentId: host.id })
         nodes[host.id] = { ...host, children: [door.id] }
@@ -270,7 +270,8 @@ describe('standalone history source invalidation', () => {
         core.sceneRegistry.byType.door.add(door.id)
       })
       scene.setState({ nodes }); clearSceneHistory()
-      edit(wall.id, { end: [6,0] }); clean()
+      const stopSpatial = core.initSpatialGridSync()
+      edit(wall.id, { end: [6,1] }); clean()
       viewer.useViewer.setState({ externalSelectedIds: [], previewSelectedIds: [], hoveredId: null, selection: { ...viewer.useViewer.getState().selection, selectedIds: [], levelId: null } })
       let now = 0
       performance.now = () => now
@@ -279,18 +280,18 @@ describe('standalone history source invalidation', () => {
       frame(); now += 181; frame()
       assert(meshes.every(mesh => !mesh.layers.isEnabled(viewer.SCENE_LAYER)))
       const batch = root.children.find(child => child.name === 'item-batch')
-      assert.equal(batch.instanceCount, 6)
+      assert.equal(batch.instanceCount, 7)
       for (const jump of [runUndo, runRedo]) {
       clean(); jump(); await flush()
       assert.deepEqual([...scene.getState().dirtyNodes].sort(), [level.id, ...walls.slice(0,4).map(node => node.id)].sort())
       captureChangedNodes(); clean(); frame()
-      assert.deepEqual(meshes.map(mesh => mesh.layers.isEnabled(viewer.SCENE_LAYER)), [true, true, true, true, false, false])
-      assert.equal(batch.instanceCount, 2)
+      assert.deepEqual(meshes.map(mesh => mesh.layers.isEnabled(viewer.SCENE_LAYER)), [true, true, true, true, false, false, false])
+      assert.equal(batch.instanceCount, 3)
       now += 181; frame()
-      assert.equal(batch.instanceCount, 6)
+      assert.equal(batch.instanceCount, 7)
       assert(meshes.every(mesh => !mesh.layers.isEnabled(viewer.SCENE_LAYER)))
       }
-      resetNodeBatchState(); if (wake.current) clearTimeout(wake.current)
+      stopSpatial(); core.spatialGridManager.clear(); resetNodeBatchState(); if (wake.current) clearTimeout(wake.current)
     `)
   })
 

From 35b29f642197b23a22990f6b082c8b7dd4ecb456 Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 15:07:32 -0400
Subject: [PATCH 08/11] Run package tests against core source without
 rebuilding dist

---
 bunfig.toml                                    |  2 ++
 .../src/store/use-scene-dirty-tracking.test.ts |  7 ++++---
 .../shared/node-batch/source-systems.test.ts   |  3 ++-
 scripts/test-preload.ts                        | 18 ++++++++++++++++++
 4 files changed, 26 insertions(+), 4 deletions(-)
 create mode 100644 bunfig.toml
 create mode 100644 scripts/test-preload.ts

diff --git a/bunfig.toml b/bunfig.toml
new file mode 100644
index 0000000000..10e82fcb12
--- /dev/null
+++ b/bunfig.toml
@@ -0,0 +1,2 @@
+[test]
+preload = ["./scripts/test-preload.ts"]
diff --git a/packages/core/src/store/use-scene-dirty-tracking.test.ts b/packages/core/src/store/use-scene-dirty-tracking.test.ts
index e26444711c..caf7f15b7d 100644
--- a/packages/core/src/store/use-scene-dirty-tracking.test.ts
+++ b/packages/core/src/store/use-scene-dirty-tracking.test.ts
@@ -39,10 +39,11 @@ describe('dirty tracking', () => {
   beforeEach(() => {
     if (!nodeRegistry.has(untrackedDef.kind)) nodeRegistry._register(untrackedDef)
     if (!nodeRegistry.has(trackedDef.kind)) nodeRegistry._register(trackedDef)
-    // Clear rather than replace the dirty set: the store's own instance is the
-    // guarded one, and the raw-add tests below exercise that guard.
-    useScene.getState().dirtyNodes.clear()
+    // Other source tests can replace the set; raw-add tests need the store's guard.
+    const dirtyNodes = useScene.getInitialState().dirtyNodes
+    dirtyNodes.clear()
     useScene.setState({
+      dirtyNodes,
       nodes: {
         [UNTRACKED]: makeNode(UNTRACKED, 'test-untracked'),
         [TRACKED]: makeNode(TRACKED, 'test-tracked'),
diff --git a/packages/nodes/src/shared/node-batch/source-systems.test.ts b/packages/nodes/src/shared/node-batch/source-systems.test.ts
index c6d7d69ac8..05ff02cc7e 100644
--- a/packages/nodes/src/shared/node-batch/source-systems.test.ts
+++ b/packages/nodes/src/shared/node-batch/source-systems.test.ts
@@ -25,6 +25,7 @@ function runSourceTest(body: string) {
     // Share the viewer's instance across every resolved path before loading consumers.
     const consumers = [
       ${sourcePath('packages/viewer/src/lib/materials.ts')},
+      ${sourcePath('packages/core/src/index.ts')},
       ${sourcePath('packages/nodes/src/shared/node-batch/system.tsx')},
       ${sourcePath('packages/editor/src/components/editor/selection-manager.tsx')},
     ]
@@ -38,7 +39,7 @@ function runSourceTest(body: string) {
       for (const path of sharedPaths.get(specifier)) mock.module(path, factory)
     }
     async function importShared(specifier) {
-      const module = await import(sharedPaths.get(specifier)[0])
+      const module = await import(specifier === '@pascal-app/core' ? ${sourcePath('packages/core/src/index.ts')} : sharedPaths.get(specifier)[0])
       mockShared(specifier, () => module)
       return module
     }
diff --git a/scripts/test-preload.ts b/scripts/test-preload.ts
new file mode 100644
index 0000000000..4dfd6f6c69
--- /dev/null
+++ b/scripts/test-preload.ts
@@ -0,0 +1,18 @@
+import { mock } from 'bun:test'
+import { resolve } from 'node:path'
+import { fileURLToPath, pathToFileURL } from 'node:url'
+import * as core from '../packages/core/src/index'
+
+// Source consumers need the current core API even when package dists are stale.
+const root = resolve(import.meta.dir, '..')
+const paths = new Set(
+  ['core', 'viewer', 'nodes', 'editor'].map((name) =>
+    fileURLToPath(
+      import.meta.resolve(
+        '@pascal-app/core',
+        pathToFileURL(resolve(root, `packages/${name}/src/index.ts`)).href,
+      ),
+    ),
+  ),
+)
+for (const path of paths) mock.module(path, () => core)

From 14218f4aa23c4e4a27cb87bcdea21153f3a779ef Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 15:30:44 -0400
Subject: [PATCH 09/11] test: drop the repo-wide core source preload

---
 bunfig.toml                                    |  2 --
 .../shared/node-batch/source-systems.test.ts   |  3 +--
 scripts/test-preload.ts                        | 18 ------------------
 3 files changed, 1 insertion(+), 22 deletions(-)
 delete mode 100644 bunfig.toml
 delete mode 100644 scripts/test-preload.ts

diff --git a/bunfig.toml b/bunfig.toml
deleted file mode 100644
index 10e82fcb12..0000000000
--- a/bunfig.toml
+++ /dev/null
@@ -1,2 +0,0 @@
-[test]
-preload = ["./scripts/test-preload.ts"]
diff --git a/packages/nodes/src/shared/node-batch/source-systems.test.ts b/packages/nodes/src/shared/node-batch/source-systems.test.ts
index 05ff02cc7e..c6d7d69ac8 100644
--- a/packages/nodes/src/shared/node-batch/source-systems.test.ts
+++ b/packages/nodes/src/shared/node-batch/source-systems.test.ts
@@ -25,7 +25,6 @@ function runSourceTest(body: string) {
     // Share the viewer's instance across every resolved path before loading consumers.
     const consumers = [
       ${sourcePath('packages/viewer/src/lib/materials.ts')},
-      ${sourcePath('packages/core/src/index.ts')},
       ${sourcePath('packages/nodes/src/shared/node-batch/system.tsx')},
       ${sourcePath('packages/editor/src/components/editor/selection-manager.tsx')},
     ]
@@ -39,7 +38,7 @@ function runSourceTest(body: string) {
       for (const path of sharedPaths.get(specifier)) mock.module(path, factory)
     }
     async function importShared(specifier) {
-      const module = await import(specifier === '@pascal-app/core' ? ${sourcePath('packages/core/src/index.ts')} : sharedPaths.get(specifier)[0])
+      const module = await import(sharedPaths.get(specifier)[0])
       mockShared(specifier, () => module)
       return module
     }
diff --git a/scripts/test-preload.ts b/scripts/test-preload.ts
deleted file mode 100644
index 4dfd6f6c69..0000000000
--- a/scripts/test-preload.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-import { mock } from 'bun:test'
-import { resolve } from 'node:path'
-import { fileURLToPath, pathToFileURL } from 'node:url'
-import * as core from '../packages/core/src/index'
-
-// Source consumers need the current core API even when package dists are stale.
-const root = resolve(import.meta.dir, '..')
-const paths = new Set(
-  ['core', 'viewer', 'nodes', 'editor'].map((name) =>
-    fileURLToPath(
-      import.meta.resolve(
-        '@pascal-app/core',
-        pathToFileURL(resolve(root, `packages/${name}/src/index.ts`)).href,
-      ),
-    ),
-  ),
-)
-for (const path of paths) mock.module(path, () => core)

From aa9c58ad31ddc5449873397ce46b880a72f7eb1a Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 15:45:48 -0400
Subject: [PATCH 10/11] test: verify consecutive undo and redo invalidation

Zundo 2.3.0 appends the just-left snapshot to both destination stacks, so the existing pre-jump length indices are correct. Cover three adjacency-changing moves and each undo/redo with cleared marks and flushed microtasks.
---
 .../src/store/history-invalidation.test.ts    | 65 ++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/packages/core/src/store/history-invalidation.test.ts b/packages/core/src/store/history-invalidation.test.ts
index 576b7669e0..101cc04795 100644
--- a/packages/core/src/store/history-invalidation.test.ts
+++ b/packages/core/src/store/history-invalidation.test.ts
@@ -1,4 +1,5 @@
-import { describe, expect, test } from 'bun:test'
+import { afterEach, beforeEach, describe, expect, test } from 'bun:test'
+import { nodeRegistry } from '../registry'
 import {
   type AnyNode,
   CeilingNode,
@@ -10,6 +11,7 @@ import {
   WindowNode,
 } from '../schema'
 import { getHistoryDirtyNodeIds } from './history-invalidation'
+import useScene, { clearSceneHistory } from './use-scene'
 
 const level = LevelNode.parse({ id: 'level_history' })
 const wall = WallNode.parse({ id: 'wall_changed', parentId: level.id, start: [0, 0], end: [4, 0] })
@@ -221,3 +223,64 @@ describe('history dependency closure', () => {
     expect(dirty.has(remote.id)).toBe(true)
   })
 })
+
+describe('consecutive temporal wall moves', () => {
+  let restore = () => {}
+
+  beforeEach(() => {
+    restore = nodeRegistry._snapshot()
+    nodeRegistry._reset()
+    clearSceneHistory()
+  })
+
+  afterEach(() => {
+    clearSceneHistory()
+    restore()
+  })
+
+  test('three undos and redos mark exactly the neighbours in each pre/post-jump layout', async () => {
+    const neighbours = [0, 10, 20, 30].map((x, index) =>
+      WallNode.parse({
+        id: `wall_neighbour_${index}`,
+        parentId: level.id,
+        start: [x + 4, 0],
+        end: [x + 4, 4],
+      }),
+    )
+    const layouts = [0, 10, 20, 30].map(
+      (x) =>
+        ({
+          ...wall,
+          start: [x, 0],
+          end: [x + 4, 0],
+        }) as WallNode,
+    )
+    const unrelated = { ...remote, start: [100, 0], end: [104, 0] } as WallNode
+    useScene.setState({
+      nodes: nodes(level, layouts[0]!, ...neighbours, unrelated),
+      rootNodeIds: [level.id],
+      collections: {},
+      installedPlugins: [],
+      dirtyNodes: new Set(),
+      readOnly: false,
+    })
+    clearSceneHistory()
+    for (const moved of layouts.slice(1)) {
+      useScene.setState({ nodes: { ...useScene.getState().nodes, [wall.id]: moved } })
+    }
+    expect(useScene.temporal.getState().pastStates).toHaveLength(3)
+
+    for (const direction of ['undo', 'redo'] as const) {
+      for (const beforeIndex of direction === 'undo' ? [3, 2, 1] : [0, 1, 2]) {
+        const afterIndex = beforeIndex + (direction === 'undo' ? -1 : 1)
+        useScene.getState().dirtyNodes.clear()
+        useScene.temporal.getState()[direction]()
+        await Promise.resolve()
+        expect(useScene.getState().nodes[wall.id]).toBe(layouts[afterIndex])
+        expect([...useScene.getState().dirtyNodes].sort()).toEqual(
+          [level.id, wall.id, neighbours[beforeIndex]!.id, neighbours[afterIndex]!.id].sort(),
+        )
+      }
+    }
+  })
+})

From 5aa651594b9767ae7b706b800e6e16c2c1be84db Mon Sep 17 00:00:00 2001
From: Wassim SAMAD <wass08@gmail.com>
Date: Wed, 9 Sep 2026 15:45:57 -0400
Subject: [PATCH 11/11] fix: invalidate old slab covering dependents on
 reparent

Refresh covering dependents below both parent levels, deduplicating equal resolved levels. Cover reparent from level 2 to level 3 and undo with exact wall/ceiling sets and unrelated levels left clean.
---
 .../spatial-grid/spatial-grid-sync.test.ts    | 55 +++++++++++++++++++
 .../hooks/spatial-grid/spatial-grid-sync.ts   |  9 ++-
 2 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
index e25865cadd..f84ed61625 100644
--- a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
+++ b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.test.ts
@@ -681,6 +681,61 @@ describe('temporal writes update slab support dependencies', () => {
     }
   })
 
+  test('slab reparent and undo mark covering dependents below both parent levels', async () => {
+    const levels = [0, 1, 2, 3].map((ordinal) =>
+      makeLevel(`level_${ordinal}`, ordinal, 2.5, [
+        `wall_covering_${ordinal}`,
+        `ceiling_covering_${ordinal}`,
+        ...(ordinal === 2 ? ['slab_reparent'] : []),
+      ]),
+    )
+    const consumers = levels.flatMap((level, ordinal) => [
+      {
+        ...makeChild(`wall_covering_${ordinal}`, 'wall', level.id),
+        start: [20, 0],
+        end: [24, 0],
+      } as AnyNode,
+      makeChild(`ceiling_covering_${ordinal}`, 'ceiling', level.id),
+    ])
+    const slab = makeSlab('slab_reparent', 'level_2')
+    useScene.setState({
+      nodes: nodesFor(...levels, ...consumers, slab),
+      rootNodeIds: levels.map((level) => level.id),
+      installedPlugins: [],
+      dirtyNodes: new Set(),
+      readOnly: false,
+    })
+    clearSceneHistory()
+    stop = initSpatialGridSync()
+    const coveringDirtyIds = () => dirtyIds().filter((id) => id.includes('_covering_'))
+    const expected = [
+      'ceiling_covering_1',
+      'ceiling_covering_2',
+      'wall_covering_1',
+      'wall_covering_2',
+    ]
+    useScene.getState().dirtyNodes.clear()
+    useScene.setState({
+      nodes: {
+        ...useScene.getState().nodes,
+        [slab.id]: { ...slab, parentId: 'level_3' } as AnyNode,
+        level_2: { ...levels[2]!, children: ['wall_covering_2', 'ceiling_covering_2'] } as AnyNode,
+        level_3: {
+          ...levels[3]!,
+          children: ['wall_covering_3', 'ceiling_covering_3', slab.id],
+        } as AnyNode,
+      },
+    })
+    await Promise.resolve()
+    expect(coveringDirtyIds()).toEqual(expected)
+
+    useScene.getState().dirtyNodes.clear()
+    useScene.temporal.getState().undo()
+    await Promise.resolve()
+    expect(useScene.getState().nodes[slab.id]?.parentId).toBe('level_2')
+    expect(coveringDirtyIds()).toEqual(expected)
+  })
+
   test('slab elevation and level height subscribers fire during real temporal restoration', async () => {
     const level = LevelNode.parse({
       id: 'level_vertical_history',
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 edeeaf224c..01869c84c1 100644
--- a/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
+++ b/packages/core/src/hooks/spatial-grid/spatial-grid-sync.ts
@@ -382,7 +382,14 @@ export function markSlabChangeDependents(
     next.thickness !== previous.thickness ||
     next.recessed !== previous.recessed
   ) {
-    markCoveringDependentsBelow(resolveLevelId(next, nodes), nodes, markDirty)
+    const nextLevelId = resolveLevelId(next, nodes)
+    markCoveringDependentsBelow(nextLevelId, nodes, markDirty)
+    if (next.parentId !== previous.parentId) {
+      const previousLevelId = resolveLevelId(previous, previousNodes)
+      if (previousLevelId !== nextLevelId) {
+        markCoveringDependentsBelow(previousLevelId, nodes, markDirty)
+      }
+    }
   }
 }