Phase 5 batch kind: slab migrates to registry (always-on)

Same shape as fence — thin renderer + system re-export, capabilities
declared, panel slider-drag fix recipe applied. Pure geometry +
floor-plan ports are later milestones.

Files added (packages/nodes/src/slab/):
 - schema.ts: re-exports SlabNode from core.
 - parametrics.ts: elevation slider only. Polygon + holes edited
   via floor-plan boundary / hole editors, not number inputs.
 - definition.ts: capabilities (no `movable` — slab move is bespoke
   whole-translation through MoveSlabTool that integrates with the
   boundary editor; capability-driven dispatch keeps the legacy mover),
   surfaces.top with elevation-as-height for stacked items, relations
   (hosts: ['item'], cascadeDelete: 'descendants'), toolHints (trace /
   finish / cancel for the placement tool).
 - renderer.tsx: thin placeholder mesh + markDirty on mount + node
   events + cached material via the same getSlabMaterial pattern as
   the legacy renderer (preset apply on shared material instance).
 - system.tsx: re-exports the legacy SlabSystem from viewer.
 - index.ts: barrel.

Files changed:
 - packages/viewer/src/index.ts: exports SlabSystem (already had
   DEFAULT_SLAB_MATERIAL, applyMaterialPresetToMaterials, createMaterial
   from earlier exports).
 - packages/nodes/src/index.ts: appends slabDefinition unconditionally
   to builtinPlugin.nodes.
 - packages/editor/src/components/ui/panels/slab-panel.tsx: applied
   the panel slider-drag fix recipe from plans/editor-node-registry.md
   prophylactically (nodeRef pattern, useScene.getState().updateNode
   inside handler, drop subscribed updateNode dep). Slab's elevation
   slider is the only drag-driven control in the panel — would have
   triggered the same Maximum update depth cascade as wall/fence.

No behavior change. Slab now mounts via the registry path, but the
legacy SlabSystem still does the actual polygon triangulation + hole
CSG work (re-exported, not duplicated).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/editor/src/components/ui/panels/slab-panel.tsx

@@ -3,7 +3,7 @@
 import { type AnyNode, type SlabNode, useScene } from '@pascal-app/core'
 import { useViewer } from '@pascal-app/viewer'
 import { Edit, Move, Plus, Trash2 } from 'lucide-react'
-import { useCallback, useEffect } from 'react'
+import { useCallback, useEffect, useRef } from 'react'
 import { sfxEmitter } from '../../../lib/sfx-bus'
 import useEditor from '../../../store/use-editor'
 import { ActionButton, ActionGroup } from '../controls/action-button'
@@ -14,7 +14,6 @@ import { PanelWrapper } from './panel-wrapper'
 export function SlabPanel() {
   const selectedId = useViewer((s) => s.selection.selectedIds[0])
   const setSelection = useViewer((s) => s.setSelection)
-  const updateNode = useScene((s) => s.updateNode)
   const editingHole = useEditor((s) => s.editingHole)
   const setEditingHole = useEditor((s) => s.setEditingHole)
   const setMovingNode = useEditor((s) => s.setMovingNode)
@@ -23,12 +22,18 @@ export function SlabPanel() {
     selectedId ? (s.nodes[selectedId as AnyNode['id']] as SlabNode | undefined) : undefined,
   )
 
+  // See "Panel slider-drag fix recipe" in plans/editor-node-registry.md.
+  // Stable handler refs across re-renders so slider drags don't trigger
+  // a Maximum update depth cascade on the panel's SliderControls.
+  const nodeRef = useRef(node)
+  nodeRef.current = node
+
   const handleUpdate = useCallback(
     (updates: Partial<SlabNode>) => {
       if (!selectedId) return
-      updateNode(selectedId as AnyNode['id'], updates)
+      useScene.getState().updateNode(selectedId as AnyNode['id'], updates)
     },
-    [selectedId, updateNode],
+    [selectedId],
   )
 
   const handleClose = useCallback(() => {

packages/nodes/src/index.ts

@@ -1,6 +1,7 @@
 import type { AnyNodeDefinition, Plugin } from '@pascal-app/core'
 import { fenceDefinition } from './fence'
 import { shelfDefinition } from './shelf'
+import { slabDefinition } from './slab'
 import { spawnDefinition } from './spawn'
 import { wallDefinition } from './wall'
 
@@ -30,10 +31,12 @@ export const builtinPlugin: Plugin = {
     spawnDefinition as unknown as AnyNodeDefinition,
     wallDefinition as unknown as AnyNodeDefinition,
     fenceDefinition as unknown as AnyNodeDefinition,
+    slabDefinition as unknown as AnyNodeDefinition,
   ],
 }
 
 export { fenceDefinition } from './fence'
 export { shelfDefinition } from './shelf'
+export { slabDefinition } from './slab'
 export { spawnDefinition } from './spawn'
 export { wallDefinition } from './wall'

packages/nodes/src/slab/definition.ts

@@ -0,0 +1,88 @@
+import type { NodeDefinition } from '@pascal-app/core'
+import { slabParametrics } from './parametrics'
+import { SlabNode } from './schema'
+
+/**
+ * Slab — Phase 5 batch kind, polygon-based.
+ *
+ * Capabilities:
+ *  - **No `movable`**: slab's "move" today is whole-slab translation via
+ *    legacy `MoveSlabTool`, which integrates with the floor-plan boundary /
+ *    hole editors. Per the capability-driven dispatch rule, omitting
+ *    `movable` keeps the legacy mover (preserves polygon-aware behavior).
+ *    Migration to the generic mover is possible in a later milestone if
+ *    the legacy mover proves equivalent.
+ *  - **`surfaces.top`**: items host on the slab top at `elevation`.
+ *  - `selectable`, `duplicable`, `deletable` standard.
+ *
+ * Relations:
+ *  - `hosts: ['item']` — items mount on the slab top.
+ *  - `cascadeDelete: 'descendants'` — deleting a slab removes hosted items.
+ *
+ * Renderer + system: thin renderer + re-export of the legacy `SlabSystem`.
+ * Same shape as wall / fence runtime port.
+ *
+ * Tool field absent: slab has 3 tools (slab-tool, boundary-editor, hole-
+ * editor) wired through editor state, not registry dispatch.
+ */
+export const slabDefinition: NodeDefinition<typeof SlabNode> = {
+  kind: 'slab',
+  schemaVersion: 1,
+  schema: SlabNode,
+  category: 'structure',
+
+  defaults: () => ({
+    object: 'node',
+    parentId: null,
+    visible: true,
+    metadata: {},
+    polygon: [],
+    holes: [],
+    holeMetadata: [],
+    elevation: 0.05,
+    autoFromWalls: false,
+  }),
+
+  capabilities: {
+    selectable: { hitVolume: 'bbox' },
+    surfaces: {
+      top: { height: (n) => (n as SlabNode).elevation },
+    },
+    duplicable: true,
+    deletable: true,
+  },
+
+  relations: {
+    hosts: ['item'],
+    cascadeDelete: 'descendants',
+  },
+
+  parametrics: slabParametrics,
+
+  renderer: {
+    kind: 'parametric',
+    module: () => import('./renderer'),
+  },
+  system: {
+    module: () => import('./system'),
+    priority: 4,
+  },
+
+  toolHints: [
+    { key: 'Left click', label: 'Trace slab outline' },
+    { key: 'Enter', label: 'Finish slab' },
+    { key: 'Esc', label: 'Cancel' },
+  ],
+
+  presentation: {
+    label: 'Slab',
+    description: 'A polygon-bounded floor surface that hosts items on top.',
+    icon: { kind: 'iconify', name: 'lucide:square' },
+    paletteSection: 'structure',
+    paletteOrder: 30,
+  },
+
+  mcp: {
+    description: 'A polygon-bounded slab (floor) with optional cutout holes.',
+  },
+}

packages/nodes/src/slab/index.ts

@@ -0,0 +1,2 @@
+export { slabDefinition } from './definition'
+export { SlabNode } from './schema'

packages/nodes/src/slab/parametrics.ts

@@ -0,0 +1,17 @@
+import type { ParametricDescriptor } from '@pascal-app/core'
+import type { SlabNode } from './schema'
+
+/**
+ * Inspector descriptor for slab. Polygon + holes are edited via the
+ * floor-plan boundary / hole editors — not number inputs. The inspector
+ * exposes only the per-instance scalars (elevation + auto-from-walls
+ * toggle).
+ */
+export const slabParametrics: ParametricDescriptor<SlabNode> = {
+  groups: [
+    {
+      label: 'Elevation',
+      fields: [{ key: 'elevation', kind: 'number', unit: 'm', min: 0.02, max: 1, step: 0.01 }],
+    },
+  ],
+}

packages/nodes/src/slab/renderer.tsx

@@ -0,0 +1,116 @@
+'use client'
+
+import { getMaterialPresetByRef, type SlabNode, useRegistry, useScene } from '@pascal-app/core'
+import {
+  applyMaterialPresetToMaterials,
+  createMaterial,
+  DEFAULT_SLAB_MATERIAL,
+  useNodeEvents,
+} from '@pascal-app/viewer'
+import { useEffect, useLayoutEffect, useMemo, useRef } from 'react'
+import type { Mesh } from 'three'
+import * as THREE from 'three'
+
+/**
+ * Thin slab renderer. Mounts a placeholder mesh, registers it with
+ * `sceneRegistry`, and marks the node dirty so `SlabSystem` fills the
+ * geometry next frame.
+ *
+ * Behaviorally identical to the legacy `SlabRenderer` in
+ * `@pascal-app/viewer/components/renderers/slab/slab-renderer.tsx` —
+ * same placeholder geometry, same material cache, same render output.
+ *
+ * Material logic is preserved from legacy: slab can carry either a raw
+ * `material` or a `materialPreset` (preset takes precedence; preset
+ * apply mutates the cached material instance so async texture loads
+ * still hit the rendered mesh on re-mount).
+ *
+ * No `def.geometry` yet — slab polygon geometry depends on holes +
+ * triangulation that lives inside `SlabSystem`'s useFrame body. Future
+ * milestone can extract a pure builder if useful, but the system is
+ * already efficient (rebuilds only dirty nodes); no urgency.
+ */
+const slabMaterialCache = new Map<string, THREE.MeshStandardMaterial>()
+
+function createEmptyGeometry() {
+  const geometry = new THREE.BufferGeometry()
+  geometry.setAttribute('position', new THREE.Float32BufferAttribute([], 3))
+  return geometry
+}
+
+function getSlabMaterial(
+  cacheKey: string,
+  params: { material?: SlabNode['material']; materialPreset?: string },
+) {
+  const cached = slabMaterialCache.get(cacheKey)
+  if (cached) return cached
+
+  const preset = getMaterialPresetByRef(params.materialPreset)
+  const slabMaterial = preset
+    ? new THREE.MeshStandardMaterial()
+    : params.material
+      ? createMaterial(params.material).clone()
+      : DEFAULT_SLAB_MATERIAL.clone()
+
+  if (preset) {
+    applyMaterialPresetToMaterials(slabMaterial, preset)
+  }
+
+  slabMaterial.transparent = false
+  slabMaterial.opacity = 1
+  slabMaterial.alphaMap = null
+  slabMaterial.side = THREE.DoubleSide
+  slabMaterial.depthWrite = true
+  slabMaterial.needsUpdate = true
+
+  slabMaterialCache.set(cacheKey, slabMaterial)
+  return slabMaterial
+}
+
+const SlabRenderer = ({ node }: { node: SlabNode }) => {
+  const ref = useRef<Mesh>(null!)
+  const placeholderGeometry = useMemo(createEmptyGeometry, [])
+  const handlers = useNodeEvents(node, 'slab')
+
+  useRegistry(node.id, 'slab', ref)
+
+  useLayoutEffect(() => {
+    useScene.getState().markDirty(node.id)
+  }, [node.id])
+
+  useEffect(() => () => placeholderGeometry.dispose(), [placeholderGeometry])
+
+  const material = useMemo(() => {
+    const resolvedMaterial = node.material
+    const resolvedMaterialPreset = node.materialPreset
+    const cacheKey = JSON.stringify({
+      material: resolvedMaterial ?? null,
+      materialPreset: resolvedMaterialPreset ?? null,
+    })
+
+    return getSlabMaterial(cacheKey, {
+      material: resolvedMaterial,
+      materialPreset: resolvedMaterialPreset,
+    })
+  }, [
+    node.material,
+    node.material?.preset,
+    node.material?.properties,
+    node.material?.texture,
+    node.materialPreset,
+  ])
+
+  return (
+    <mesh
+      castShadow
+      geometry={placeholderGeometry}
+      material={material}
+      receiveShadow
+      ref={ref}
+      visible={node.visible}
+      {...handlers}
+    />
+  )
+}
+
+export default SlabRenderer

packages/nodes/src/slab/schema.ts

@@ -0,0 +1 @@
+export { SlabNode } from '@pascal-app/core'

packages/nodes/src/slab/system.tsx

@@ -0,0 +1,20 @@
+'use client'
+
+import { SlabSystem } from '@pascal-app/viewer'
+
+/**
+ * Registry-driven slab system bundle. Re-exports the legacy `SlabSystem`
+ * (still in viewer) so it mounts via `RegisteredSystems` when slab is
+ * registry-driven. `<LegacySystem kind="slab">` in viewer/components/
+ * viewer/index.tsx short-circuits whenever `nodeRegistry.has('slab')`
+ * is true — same shape wall and fence use.
+ *
+ * Future Phase 5+: extract polygon triangulation + hole CSG into a pure
+ * `buildSlabGeometry(node)` and migrate to `def.geometry`. The legacy
+ * system body has it well-isolated; should be a clean extraction.
+ */
+const SlabSystems = () => {
+  return <SlabSystem />
+}
+
+export default SlabSystems

packages/viewer/src/index.ts

@@ -38,6 +38,10 @@ export { FenceSystem } from './systems/fence/fence-system'
 export { InteractiveSystem } from './systems/interactive/interactive-system'
 export { snapLevelsToTruePositions } from './systems/level/level-utils'
 export { getRoofMaterialArray } from './systems/roof/roof-materials'
+// Slab system follows the wall + fence re-export pattern — composed into
+// the registry-driven slab definition's `def.system`. Removed in Phase 6
+// alongside the legacy slab mount point.
+export { SlabSystem } from './systems/slab/slab-system'
 export { getStairBodyMaterials, getStairRailingMaterial } from './systems/stair/stair-materials'
 export { WallCutout } from './systems/wall/wall-cutout'
 export { getVisibleWallMaterials } from './systems/wall/wall-materials'