diff --git a/apps/editor/public/material/concrete/concrete_plate/concrete_plate_ao_512.ktx2 b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_ao_512.ktx2
new file mode 100644
index 000000000..35e24b319
Binary files /dev/null and b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_ao_512.ktx2 differ
diff --git a/apps/editor/public/material/concrete/concrete_plate/concrete_plate_basecolor_512.ktx2 b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_basecolor_512.ktx2
new file mode 100644
index 000000000..7d82bd561
Binary files /dev/null and b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_basecolor_512.ktx2 differ
diff --git a/apps/editor/public/material/concrete/concrete_plate/concrete_plate_normal_512.ktx2 b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_normal_512.ktx2
new file mode 100644
index 000000000..4da4bb115
Binary files /dev/null and b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_normal_512.ktx2 differ
diff --git a/apps/editor/public/material/concrete/concrete_plate/concrete_plate_roughness_512.ktx2 b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_roughness_512.ktx2
new file mode 100644
index 000000000..8a5044f22
Binary files /dev/null and b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_roughness_512.ktx2 differ
diff --git a/apps/editor/public/material/concrete/concrete_plate/concrete_plate_thumb.webp b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_thumb.webp
new file mode 100644
index 000000000..495ef6cae
Binary files /dev/null and b/apps/editor/public/material/concrete/concrete_plate/concrete_plate_thumb.webp differ
diff --git a/packages/core/src/material-library.ts b/packages/core/src/material-library.ts
index d743d03cd..eedf63e4c 100644
--- a/packages/core/src/material-library.ts
+++ b/packages/core/src/material-library.ts
@@ -3442,7 +3442,9 @@ export const MATERIAL_CATALOG: MaterialCatalogItem[] = [
         bumpScale: 1,
         emissiveColor: '#000000',
         aoMapIntensity: 1,
-        side: 2,
+        // FrontSide — DoubleSide on a NodeMaterial poisons the WebGPU MRT scene
+        // pass (window/door glass relies on this). It's the only glass we use.
+        side: 0,
         opacity: 0.3,
         lightMapIntensity: 1,
       },
@@ -3860,6 +3862,44 @@ export const MATERIAL_CATALOG: MaterialCatalogItem[] = [
       },
     },
   },
+  {
+    id: 'concrete-plate',
+    label: 'Concrete Plate',
+    category: 'concrete',
+    surfaces: ['wall', 'floor'],
+    description: 'Smooth cast concrete plate',
+    previewThumbnailUrl: '/material/concrete/concrete_plate/concrete_plate_thumb.webp',
+    preset: {
+      maps: {
+        albedoMap: '/material/concrete/concrete_plate/concrete_plate_basecolor_512.ktx2',
+        normalMap: '/material/concrete/concrete_plate/concrete_plate_normal_512.ktx2',
+        roughnessMap: '/material/concrete/concrete_plate/concrete_plate_roughness_512.ktx2',
+        aoMap: '/material/concrete/concrete_plate/concrete_plate_ao_512.ktx2',
+      },
+      mapProperties: {
+        color: '#ffffff',
+        roughness: 0.8,
+        metalness: 0,
+        repeatX: 0.5,
+        repeatY: 0.5,
+        rotation: 0,
+        wrapS: 'Repeat',
+        wrapT: 'Repeat',
+        normalScaleX: 1,
+        normalScaleY: 1,
+        emissiveIntensity: 1,
+        displacementScale: 0,
+        transparent: false,
+        flipY: false,
+        bumpScale: 1,
+        emissiveColor: '#000000',
+        aoMapIntensity: 1,
+        side: 0,
+        opacity: 1,
+        lightMapIntensity: 1,
+      },
+    },
+  },
   {
     id: 'concrete-stucco',
     label: 'White Stucco',
@@ -3915,7 +3955,7 @@ export const MATERIAL_CATALOG: MaterialCatalogItem[] = [
       mapProperties: {
         color: '#ffffff',
         roughness: 0.4,
-        metalness: 1,
+        metalness: 0.6,
         repeatX: 1,
         repeatY: 1,
         rotation: 0,
@@ -3954,7 +3994,7 @@ export const MATERIAL_CATALOG: MaterialCatalogItem[] = [
       mapProperties: {
         color: '#ffffff',
         roughness: 0.3,
-        metalness: 1,
+        metalness: 0.6,
         repeatX: 1,
         repeatY: 1,
         rotation: 0,
@@ -3995,7 +4035,77 @@ export const MATERIAL_CATALOG: MaterialCatalogItem[] = [
       mapProperties: {
         color: '#ffffff',
         roughness: 0.45,
-        metalness: 1,
+        metalness: 0.6,
+        repeatX: 1,
+        repeatY: 1,
+        rotation: 0,
+        wrapS: 'Repeat',
+        wrapT: 'Repeat',
+        normalScaleX: 1,
+        normalScaleY: 1,
+        emissiveIntensity: 1,
+        displacementScale: 0,
+        transparent: false,
+        flipY: false,
+        bumpScale: 1,
+        emissiveColor: '#000000',
+        aoMapIntensity: 1,
+        side: 0,
+        opacity: 1,
+        lightMapIntensity: 1,
+      },
+    },
+  },
+  {
+    // Parameter-only metal (no texture maps) — a worked example of a non-PBR
+    // catalog finish driven purely by three.js material settings.
+    id: 'metal-brass',
+    label: 'Brass',
+    category: 'metal',
+    surfaces: ['furniture', 'wall'],
+    description: 'Polished brass (flat metal, no maps)',
+    previewColor: '#b08d57',
+    preset: {
+      maps: {},
+      mapProperties: {
+        color: '#b08d57',
+        roughness: 0.35,
+        metalness: 0.9,
+        repeatX: 1,
+        repeatY: 1,
+        rotation: 0,
+        wrapS: 'Repeat',
+        wrapT: 'Repeat',
+        normalScaleX: 1,
+        normalScaleY: 1,
+        emissiveIntensity: 1,
+        displacementScale: 0,
+        transparent: false,
+        flipY: false,
+        bumpScale: 1,
+        emissiveColor: '#000000',
+        aoMapIntensity: 1,
+        side: 0,
+        opacity: 1,
+        lightMapIntensity: 1,
+      },
+    },
+  },
+  {
+    // Parameter-only chrome (no texture maps) — moderate metalness so it reads
+    // as bright metal under direct/ambient light without needing an env map.
+    id: 'metal-chrome',
+    label: 'Chrome',
+    category: 'metal',
+    surfaces: ['furniture', 'wall'],
+    description: 'Polished chrome (flat metal, no maps)',
+    previewColor: '#c8ccce',
+    preset: {
+      maps: {},
+      mapProperties: {
+        color: '#c8ccce',
+        roughness: 0.2,
+        metalness: 0.6,
         repeatX: 1,
         repeatY: 1,
         rotation: 0,
diff --git a/packages/core/src/registry/types.ts b/packages/core/src/registry/types.ts
index bbeca31ad..826f1332e 100644
--- a/packages/core/src/registry/types.ts
+++ b/packages/core/src/registry/types.ts
@@ -1,5 +1,5 @@
 import type { ComponentType } from 'react'
-import type { BufferGeometry, Object3D } from 'three'
+import type { BufferGeometry, Object3D, Ray } from 'three'
 import type { ZodObject, z } from 'zod'
 import type { MaterialSchema } from '../schema/material'
 import type { SceneMaterial, SceneMaterialId } from '../schema/scene-material'
@@ -1212,6 +1212,14 @@ export type PaintResolveArgs = {
   hitObjectName?: string
   /** Optional: the three.js object that received the pointer hit. Items read userData.slotId off it. */
   hitObject?: Object3D
+  /**
+   * Optional: the pointer's world ray, so a kind can re-raycast its OWN subtree
+   * to pick the precise sub-mesh under the cursor — independent of what the
+   * shared scene raycast hit first. Door/window use this: their opening proxy
+   * (a proud invisible cutout) wins the scene raycast over the wall in front of
+   * the recessed door body, then they re-raycast their parts to find the slot.
+   */
+  ray?: Ray
 }
 
 export type PaintPatchArgs = {
diff --git a/packages/core/src/schema/index.ts b/packages/core/src/schema/index.ts
index f0baa8db0..ca8fc1845 100644
--- a/packages/core/src/schema/index.ts
+++ b/packages/core/src/schema/index.ts
@@ -154,6 +154,7 @@ export type { WallSurfaceMaterialSpec, WallSurfaceSide } from './nodes/wall'
 export {
   getEffectiveWallSurfaceMaterial,
   getWallSurfaceMaterialSignature,
+  WALL_SLOT_DEFAULT,
   WallNode,
 } from './nodes/wall'
 export { WindowNode, WindowType } from './nodes/window'
diff --git a/packages/core/src/schema/nodes/ceiling.ts b/packages/core/src/schema/nodes/ceiling.ts
index 724bb0fde..b94aaaa2b 100644
--- a/packages/core/src/schema/nodes/ceiling.ts
+++ b/packages/core/src/schema/nodes/ceiling.ts
@@ -11,6 +11,10 @@ export const CeilingNode = BaseNode.extend({
   children: z.array(ItemNode.shape.id).default([]),
   material: MaterialSchema.optional(),
   materialPreset: z.string().optional(),
+  // Per-slot material overrides on the unified slot model, mirroring
+  // `ShelfNode.slots`. Key = slot id (`surface`), value = a `MaterialRef`
+  // (`library:<id>` / `scene:<id>`). Absent = the declared slot default.
+  slots: z.record(z.string(), z.string()).optional(),
   polygon: z.array(z.tuple([z.number(), z.number()])),
   holes: z.array(z.array(z.tuple([z.number(), z.number()]))).default([]),
   holeMetadata: z.array(SurfaceHoleMetadata).default([]),
diff --git a/packages/core/src/schema/nodes/door.ts b/packages/core/src/schema/nodes/door.ts
index fd26ad687..26b4170e0 100644
--- a/packages/core/src/schema/nodes/door.ts
+++ b/packages/core/src/schema/nodes/door.ts
@@ -41,6 +41,10 @@ export const DoorNode = BaseNode.extend({
   id: objectId('door'),
   type: nodeType('door'),
   material: MaterialSchema.optional(),
+  // Per-slot material overrides on the unified slot model. Keys: `panel` (the
+  // door body), `glass`. Value = a `MaterialRef` (`library:<id>` / `scene:<id>`).
+  // Absent = the body/glass default. Mirrors `ShelfNode.slots`.
+  slots: z.record(z.string(), z.string()).optional(),
 
   position: z.tuple([z.number(), z.number(), z.number()]).default([0, 0, 0]),
   rotation: z.tuple([z.number(), z.number(), z.number()]).default([0, 0, 0]),
diff --git a/packages/core/src/schema/nodes/slab.ts b/packages/core/src/schema/nodes/slab.ts
index 5232eaaf8..fe3c47c1d 100644
--- a/packages/core/src/schema/nodes/slab.ts
+++ b/packages/core/src/schema/nodes/slab.ts
@@ -9,6 +9,10 @@ export const SlabNode = BaseNode.extend({
   type: nodeType('slab'),
   material: MaterialSchema.optional(),
   materialPreset: z.string().optional(),
+  // Per-slot material overrides on the unified slot model, mirroring
+  // `ShelfNode.slots`. Key = slot id (`surface`), value = a `MaterialRef`
+  // (`library:<id>` / `scene:<id>`). Absent = the declared slot default.
+  slots: z.record(z.string(), z.string()).optional(),
   polygon: z.array(z.tuple([z.number(), z.number()])),
   holes: z.array(z.array(z.tuple([z.number(), z.number()]))).default([]),
   holeMetadata: z.array(SurfaceHoleMetadata).default([]),
diff --git a/packages/core/src/schema/nodes/wall.ts b/packages/core/src/schema/nodes/wall.ts
index ebce121c2..c1d65e4b8 100644
--- a/packages/core/src/schema/nodes/wall.ts
+++ b/packages/core/src/schema/nodes/wall.ts
@@ -46,6 +46,16 @@ export type WallNode = z.infer<typeof WallNode>
 
 export type WallSurfaceSide = 'interior' | 'exterior'
 
+// Declared default appearance for an unpainted wall face in colored mode —
+// visual parity with the retired DEFAULT_WALL_MATERIAL. Lives in core so the
+// slot declaration (nodes) and the material resolver (viewer) share one value.
+// May be a `#rrggbb` colour or a `library:<id>` ref. Textures-off still
+// collapses to the themed wall role (the escape hatch).
+export const WALL_SLOT_DEFAULT: Record<WallSurfaceSide, string> = {
+  interior: 'library:concrete-plate',
+  exterior: 'library:concrete-plate',
+}
+
 export type WallSurfaceMaterialSpec = {
   material?: z.infer<typeof MaterialSchema>
   materialPreset?: string
diff --git a/packages/core/src/schema/nodes/window.ts b/packages/core/src/schema/nodes/window.ts
index c5a1f5f01..08c5ce4ef 100644
--- a/packages/core/src/schema/nodes/window.ts
+++ b/packages/core/src/schema/nodes/window.ts
@@ -21,6 +21,10 @@ export const WindowNode = BaseNode.extend({
   id: objectId('window'),
   type: nodeType('window'),
   material: MaterialSchema.optional(),
+  // Per-slot material overrides on the unified slot model. Keys: `frame`,
+  // `glass`. Value = a `MaterialRef` (`library:<id>` / `scene:<id>`). Absent =
+  // the frame/glass default. Mirrors `ShelfNode.slots`.
+  slots: z.record(z.string(), z.string()).optional(),
 
   position: z.tuple([z.number(), z.number(), z.number()]).default([0, 0, 0]),
   rotation: z.tuple([z.number(), z.number(), z.number()]).default([0, 0, 0]),
diff --git a/packages/editor/src/components/editor/index.tsx b/packages/editor/src/components/editor/index.tsx
index c6903080a..1398dec38 100644
--- a/packages/editor/src/components/editor/index.tsx
+++ b/packages/editor/src/components/editor/index.tsx
@@ -7,7 +7,13 @@ import {
   spatialGridManager,
   useScene,
 } from '@pascal-app/core'
-import { type HoverStyles, InteractiveSystem, useViewer, Viewer } from '@pascal-app/viewer'
+import {
+  type HoverStyles,
+  InteractiveSystem,
+  SceneEnvironment,
+  useViewer,
+  Viewer,
+} from '@pascal-app/viewer'
 import { memo, type ReactNode, useCallback, useEffect, useRef, useState } from 'react'
 import { ViewerOverlay } from '../../components/viewer-overlay'
 import { ViewerZoneSystem } from '../../components/viewer-zone-system'
@@ -602,6 +608,7 @@ const ViewerSceneContent = memo(function ViewerSceneContent({
   const noEditing = isVersionPreviewMode || isFirstPersonMode || isStudioMode
   return (
     <>
+      <SceneEnvironment />
       {!(isFirstPersonMode || isStudioMode) && <SelectionManager />}
       {!noEditing && <BoxSelectTool />}
       {!noEditing && <NodeArrowHandles />}
diff --git a/packages/editor/src/components/editor/selection-manager.tsx b/packages/editor/src/components/editor/selection-manager.tsx
index b1a3e50ac..e6cc48c11 100644
--- a/packages/editor/src/components/editor/selection-manager.tsx
+++ b/packages/editor/src/components/editor/selection-manager.tsx
@@ -907,6 +907,7 @@ export const SelectionManager = () => {
           localPosition: event.localPosition as readonly [number, number, number] | undefined,
           hitObjectName: event.nativeEvent.object?.name,
           hitObject: getEventObject(event),
+          ray: event.nativeEvent.ray,
         })
         const compatible = role !== null && paintEnabled
         return {
@@ -1059,13 +1060,7 @@ export const SelectionManager = () => {
       // before any of the legacy roof / stair / single-surface arms
       // below run.
 
-      if (
-        node.type === 'fence' ||
-        node.type === 'column' ||
-        node.type === 'slab' ||
-        node.type === 'ceiling' ||
-        node.type === 'shelf'
-      ) {
+      if (node.type === 'fence' || node.type === 'column' || node.type === 'shelf') {
         const compatible = paintEnabled
 
         return {
@@ -1094,7 +1089,7 @@ export const SelectionManager = () => {
         }
       }
 
-      const disabledNodeTypes = ['window', 'door', 'zone']
+      const disabledNodeTypes = ['zone']
       if (disabledNodeTypes.includes(node.type)) {
         return {
           key: `${node.type}:${node.id}:unsupported`,
@@ -1191,6 +1186,11 @@ export const SelectionManager = () => {
 
     for (const type of subscribedKinds) {
       emitter.on(`${type}:enter` as any, onEnter as any)
+      // Re-evaluate on move so the hover preview tracks the cursor across a
+      // kind's sub-parts (door/window panel↔frame↔glass↔hardware, wall
+      // interior↔exterior) — not just on the initial enter. onEnter is
+      // idempotent (no-ops when the resolved part is unchanged).
+      emitter.on(`${type}:move` as any, onEnter as any)
       emitter.on(`${type}:leave` as any, onLeave as any)
       emitter.on(`${type}:click` as any, onClick as any)
     }
@@ -1198,6 +1198,7 @@ export const SelectionManager = () => {
     return () => {
       for (const type of subscribedKinds) {
         emitter.off(`${type}:enter` as any, onEnter as any)
+        emitter.off(`${type}:move` as any, onEnter as any)
         emitter.off(`${type}:leave` as any, onLeave as any)
         emitter.off(`${type}:click` as any, onClick as any)
       }
@@ -1558,6 +1559,7 @@ export const SelectionManager = () => {
               localPosition: event.localPosition as readonly [number, number, number] | undefined,
               hitObjectName: event.nativeEvent.object?.name,
               hitObject: getEventObject(event),
+              ray: event.nativeEvent.ray,
             })
             if (role) {
               setSelectedMaterialTargetForNode(nodeToSelect, role as MaterialTargetRole)
diff --git a/packages/editor/src/lib/material-paint.ts b/packages/editor/src/lib/material-paint.ts
index bd672f153..7f86c05e1 100644
--- a/packages/editor/src/lib/material-paint.ts
+++ b/packages/editor/src/lib/material-paint.ts
@@ -382,8 +382,6 @@ export function resolveActivePaintMaterialFromSelection(params: {
   if (
     (selectedNode.type === 'fence' ||
       selectedNode.type === 'column' ||
-      selectedNode.type === 'slab' ||
-      selectedNode.type === 'ceiling' ||
       selectedNode.type === 'shelf') &&
     selectedMaterialTarget.role === 'surface'
   ) {
diff --git a/packages/nodes/src/ceiling/definition.ts b/packages/nodes/src/ceiling/definition.ts
index a59a70349..118c0abae 100644
--- a/packages/nodes/src/ceiling/definition.ts
+++ b/packages/nodes/src/ceiling/definition.ts
@@ -10,8 +10,10 @@ import {
   ceilingMoveVertexAffordance,
 } from './floorplan-affordances'
 import { ceilingFloorplanMoveTarget } from './floorplan-move'
+import { ceilingPaint } from './paint'
 import { ceilingParametrics } from './parametrics'
 import { CeilingNode } from './schema'
+import { ceilingSlots } from './slots'
 
 const HEIGHT_HANDLE_OFFSET = 0.22
 const MIN_CEILING_HEIGHT = 0.5
@@ -102,6 +104,10 @@ export const ceilingDefinition: NodeDefinition<typeof CeilingNode> = {
     },
     duplicable: true,
     deletable: true,
+    // Unified slot model: one paintable underside surface with a declared
+    // default, painted through the registry `capabilities.paint` dispatch.
+    slots: () => ceilingSlots(),
+    paint: ceilingPaint,
   },
 
   relations: {
diff --git a/packages/nodes/src/ceiling/materials.ts b/packages/nodes/src/ceiling/materials.ts
new file mode 100644
index 000000000..a6e4e590e
--- /dev/null
+++ b/packages/nodes/src/ceiling/materials.ts
@@ -0,0 +1,80 @@
+import {
+  getMaterialPresetByRef,
+  parseMaterialRef,
+  resolveMaterial,
+  type SceneMaterial,
+  type SceneMaterialId,
+} from '@pascal-app/core'
+import { float, mix, positionWorld, smoothstep } from 'three/tsl'
+import { BackSide, FrontSide, MeshBasicNodeMaterial } from 'three/webgpu'
+
+/**
+ * Ceiling material builders, shared by the renderer (mesh appearance) and the
+ * paint capability (hover preview). A ceiling is a flat tinted surface: the
+ * underside (`bottom`, seen from inside the room, `BackSide`) is opaque, while
+ * the `top` carries a transparent TSL grid overlay used while placing /
+ * selecting ceiling-hosted items. Both derive from a single colour, so slot
+ * painting resolves a colour and rebuilds these — it never applies a PBR map.
+ */
+
+const gridScale = 5
+const gridX = positionWorld.x.mul(gridScale).fract()
+const gridY = positionWorld.z.mul(gridScale).fract()
+const lineWidth = 0.05
+const lineX = smoothstep(lineWidth, 0, gridX).add(smoothstep(1.0 - lineWidth, 1.0, gridX))
+const lineY = smoothstep(lineWidth, 0, gridY).add(smoothstep(1.0 - lineWidth, 1.0, gridY))
+const gridPattern = lineX.max(lineY)
+const gridOpacity = mix(float(0.2), float(0.6), gridPattern)
+
+export type CeilingMaterials = {
+  topMaterial: MeshBasicNodeMaterial
+  bottomMaterial: MeshBasicNodeMaterial
+}
+
+function createCeilingMaterials(color = '#999999'): CeilingMaterials {
+  const topMaterial = new MeshBasicNodeMaterial({
+    color,
+    transparent: true,
+    depthWrite: false,
+    side: FrontSide,
+  })
+  topMaterial.opacityNode = gridOpacity
+
+  const bottomMaterial = new MeshBasicNodeMaterial({
+    color,
+    transparent: true,
+    side: BackSide,
+  })
+
+  return { topMaterial, bottomMaterial }
+}
+
+const ceilingMaterialCache = new Map<string, CeilingMaterials>()
+
+export function getCeilingMaterials(color = '#999999'): CeilingMaterials {
+  const cached = ceilingMaterialCache.get(color)
+  if (cached) return cached
+  const materials = createCeilingMaterials(color)
+  ceilingMaterialCache.set(color, materials)
+  return materials
+}
+
+/**
+ * Resolve a slot `MaterialRef` to a flat colour for the ceiling surface.
+ * `library:` refs use the catalog preset's base colour; `scene:` refs use the
+ * stored material's colour. Returns null for a dangling / unparseable ref so
+ * the caller falls back to its default.
+ */
+export function ceilingColorFromRef(
+  ref: string | undefined,
+  sceneMaterials: Record<SceneMaterialId, SceneMaterial> | undefined,
+): string | null {
+  const parsed = parseMaterialRef(ref)
+  if (!parsed) return null
+  if (parsed.kind === 'library') {
+    return getMaterialPresetByRef(ref)?.mapProperties.color ?? null
+  }
+  const sceneMaterial = sceneMaterials?.[parsed.id as SceneMaterialId]
+  if (!sceneMaterial) return null
+  return resolveMaterial(sceneMaterial.material).color ?? null
+}
diff --git a/packages/nodes/src/ceiling/paint.ts b/packages/nodes/src/ceiling/paint.ts
new file mode 100644
index 000000000..3efce6994
--- /dev/null
+++ b/packages/nodes/src/ceiling/paint.ts
@@ -0,0 +1,42 @@
+import {
+  type AnyNode,
+  type CeilingNode,
+  getMaterialPresetByRef,
+  resolveMaterial,
+} from '@pascal-app/core'
+import type { Mesh } from 'three'
+import { createSlotPaintCapability } from '../shared/slot-paint'
+import { getCeilingMaterials } from './materials'
+
+/**
+ * Ceiling paint on the unified slot model. A ceiling has one paintable surface,
+ * so every hit resolves to `surface`; commit writes `node.slots.surface`. The
+ * preview swaps the registered underside mesh to the ceiling's own flat-tinted
+ * material (built `BackSide`, the way it renders), so the hover preview matches
+ * the committed result — a generic PBR preview would be invisible from below.
+ */
+export const ceilingPaint = createSlotPaintCapability({
+  resolveRole: () => 'surface',
+  applyPreview: ({ material, materialPreset, root }) => {
+    const color = materialPreset
+      ? (getMaterialPresetByRef(materialPreset)?.mapProperties.color ?? null)
+      : material
+        ? (resolveMaterial(material).color ?? null)
+        : null
+    if (!color) return () => {}
+    const mesh = root as Mesh
+    if (!mesh.isMesh) return null
+    const previous = mesh.material
+    mesh.material = getCeilingMaterials(color).bottomMaterial
+    return () => {
+      mesh.material = previous
+    }
+  },
+  legacyEffective: (node: AnyNode) => {
+    const ceiling = node as CeilingNode
+    if (ceiling.materialPreset || ceiling.material) {
+      return { material: ceiling.material, materialPreset: ceiling.materialPreset }
+    }
+    return null
+  },
+})
diff --git a/packages/nodes/src/ceiling/renderer.tsx b/packages/nodes/src/ceiling/renderer.tsx
index 263c4fd81..9f49086c8 100644
--- a/packages/nodes/src/ceiling/renderer.tsx
+++ b/packages/nodes/src/ceiling/renderer.tsx
@@ -15,53 +15,15 @@ import {
   useViewer,
 } from '@pascal-app/viewer'
 import { useEffect, useLayoutEffect, useMemo, useRef } from 'react'
-import { float, mix, positionWorld, smoothstep } from 'three/tsl'
-import { BackSide, FrontSide, type Mesh, MeshBasicNodeMaterial } from 'three/webgpu'
+import { BackSide, type Mesh } from 'three/webgpu'
 import { createPlaceholderGeometry } from '../shared/placeholder-geometry'
+import { ceilingColorFromRef, getCeilingMaterials } from './materials'
+import { CEILING_SLOT_DEFAULT_COLOR } from './slots'
 
 function createEmptyGeometry() {
   return createPlaceholderGeometry()
 }
 
-const gridScale = 5
-const gridX = positionWorld.x.mul(gridScale).fract()
-const gridY = positionWorld.z.mul(gridScale).fract()
-const lineWidth = 0.05
-const lineX = smoothstep(lineWidth, 0, gridX).add(smoothstep(1.0 - lineWidth, 1.0, gridX))
-const lineY = smoothstep(lineWidth, 0, gridY).add(smoothstep(1.0 - lineWidth, 1.0, gridY))
-const gridPattern = lineX.max(lineY)
-const gridOpacity = mix(float(0.2), float(0.6), gridPattern)
-
-function createCeilingMaterials(color = '#999999') {
-  const topMaterial = new MeshBasicNodeMaterial({
-    color,
-    transparent: true,
-    depthWrite: false,
-    side: FrontSide,
-  })
-  topMaterial.opacityNode = gridOpacity
-
-  const bottomMaterial = new MeshBasicNodeMaterial({
-    color,
-    transparent: true,
-    side: BackSide,
-  })
-
-  return { topMaterial, bottomMaterial }
-}
-
-const ceilingMaterialCache = new Map<string, ReturnType<typeof createCeilingMaterials>>()
-
-function getCeilingMaterials(color = '#999999') {
-  const cacheKey = color
-  const cached = ceilingMaterialCache.get(cacheKey)
-  if (cached) return cached
-
-  const materials = createCeilingMaterials(color)
-  ceilingMaterialCache.set(cacheKey, materials)
-  return materials
-}
-
 export const CeilingRenderer = ({ node }: { node: CeilingNode }) => {
   const ref = useRef<Mesh>(null!)
   const placeholderGeometry = useMemo(createEmptyGeometry, [])
@@ -80,6 +42,9 @@ export const CeilingRenderer = ({ node }: { node: CeilingNode }) => {
   const textures = useViewer((s) => s.textures)
   const colorPreset = useViewer((s) => s.colorPreset)
   const sceneTheme = useViewer((s) => s.sceneTheme)
+  // Subscribe to the scene-material library so editing a `scene:` material the
+  // ceiling slot references re-tints it live.
+  const sceneMaterials = useScene((s) => s.materials)
   const liveTransform = useLiveTransforms((s) => s.get(node.id))
   const ceilingY = (node.height ?? 2.5) - 0.01 + (liveTransform?.position[1] ?? 0)
   const position: [number, number, number] = [
@@ -97,18 +62,15 @@ export const CeilingRenderer = ({ node }: { node: CeilingNode }) => {
   )
 
   const materials = useMemo(() => {
-    // Untextured ceilings (and everything in textures-off mode) take the themed
-    // 'ceiling' role colour; only an explicit preset/material keeps a texture.
-    const hasExplicit = Boolean(node.materialPreset || node.material)
-    if (!textures || !hasExplicit) {
-      // Bottom (seen from inside the room, looking up) stays opaque so the
-      // ceiling reads as a solid surface. Top uses the transparent
-      // grid-pattern material so the ceiling stays see-through whenever
-      // the editor reveals the `ceiling-grid` overlay (placing a
-      // ceiling-hosted item, or selecting one of its children — e.g.
-      // after committing a placement). Without this the top mesh shipped
-      // an opaque surface-role material, so a top-down camera lost view
-      // of everything under the ceiling once the overlay turned on.
+    // Textures-off mode takes the themed 'ceiling' role colour — the guaranteed
+    // escape hatch, independent of any slot override. The bottom (seen from
+    // inside the room, looking up) stays opaque so the ceiling reads as a solid
+    // surface; the top keeps the transparent grid material so a top-down camera
+    // can see through the ceiling whenever the `ceiling-grid` overlay is
+    // revealed (placing a ceiling-hosted item, or selecting one of its
+    // children). Without that the top mesh would ship an opaque surface-role
+    // material and a top-down camera would lose everything under the ceiling.
+    if (!textures) {
       const ceilingColor = resolveSurfaceColor('ceiling', colorPreset, sceneTheme)
       return {
         topMaterial: getCeilingMaterials(ceilingColor).topMaterial,
@@ -116,14 +78,26 @@ export const CeilingRenderer = ({ node }: { node: CeilingNode }) => {
       }
     }
 
-    const preset = getMaterialPresetByRef(node.materialPreset)
-    const props = preset?.mapProperties ?? resolveMaterial(node.material)
-    const color = props.color || '#999999'
-    return getCeilingMaterials(color)
+    // Unified slot override — shared scene material or catalog `library:` finish
+    // (resolved to its base colour; a ceiling renders flat-tinted, not mapped).
+    const slotColor = ceilingColorFromRef(node.slots?.surface, sceneMaterials)
+    if (slotColor) return getCeilingMaterials(slotColor)
+
+    // Legacy inline material / preset (scenes painted before the slot model).
+    if (node.materialPreset || node.material) {
+      const preset = getMaterialPresetByRef(node.materialPreset)
+      const props = preset?.mapProperties ?? resolveMaterial(node.material)
+      return getCeilingMaterials(props.color || '#999999')
+    }
+
+    // Declared slot default.
+    return getCeilingMaterials(CEILING_SLOT_DEFAULT_COLOR)
   }, [
     textures,
     colorPreset,
     sceneTheme,
+    sceneMaterials,
+    node.slots,
     node.materialPreset,
     node.material,
     node.material?.preset,
diff --git a/packages/nodes/src/ceiling/slots.ts b/packages/nodes/src/ceiling/slots.ts
new file mode 100644
index 000000000..7b7c48a99
--- /dev/null
+++ b/packages/nodes/src/ceiling/slots.ts
@@ -0,0 +1,12 @@
+import type { SlotDeclaration } from '@pascal-app/core'
+
+export type CeilingSlotId = 'surface'
+
+// Soft white — the default underside colour for an unpainted ceiling. (A
+// ceiling renders flat-tinted, so this is a colour, not a `library:` finish.)
+export const CEILING_SLOT_DEFAULT_COLOR = '#f2eee6'
+
+/** A ceiling exposes a single paintable underside surface. */
+export function ceilingSlots(): SlotDeclaration[] {
+  return [{ slotId: 'surface', label: 'Surface', default: CEILING_SLOT_DEFAULT_COLOR }]
+}
diff --git a/packages/nodes/src/door/definition.ts b/packages/nodes/src/door/definition.ts
index f006e2634..4846413c5 100644
--- a/packages/nodes/src/door/definition.ts
+++ b/packages/nodes/src/door/definition.ts
@@ -12,8 +12,10 @@ import { scaleHandleHeight } from './door-math'
 import { buildDoorFloorplan } from './floorplan'
 import { doorWidthAffordance } from './floorplan-affordances'
 import { doorFloorplanMoveTarget } from './floorplan-move'
+import { doorPaint } from './paint'
 import { doorParametrics } from './parametrics'
 import { DoorNode } from './schema'
+import { doorSlots } from './slots'
 
 const SIDE_HANDLE_OFFSET = 0.24
 const HEIGHT_HANDLE_OFFSET = 0.24
@@ -174,6 +176,10 @@ export const doorDefinition: NodeDefinition<typeof DoorNode> = {
     // placed. Host apps strip these at preset-save time via
     // `getHostRefFields(def)`.
     hostRefFields: ['wallId', 'roofSegmentId', 'roofFace'],
+    // Panel / glass slots painted through the registry. The door system tags
+    // each mesh with its `userData.slotId`; paint writes `node.slots`.
+    slots: () => doorSlots(),
+    paint: doorPaint,
   },
 
   parametrics: doorParametrics,
diff --git a/packages/nodes/src/door/paint.ts b/packages/nodes/src/door/paint.ts
new file mode 100644
index 000000000..e236a5e38
--- /dev/null
+++ b/packages/nodes/src/door/paint.ts
@@ -0,0 +1,16 @@
+import {
+  createSlotPaintCapability,
+  previewSlotByUserData,
+  resolveSlotByReRaycast,
+} from '../shared/slot-paint'
+
+/**
+ * Door paint on the unified slot model. The door's opening proxy (a proud,
+ * invisible cutout) wins the shared scene raycast over the wall in front of the
+ * recessed door body, so `resolveSlotByReRaycast` re-raycasts the door's own
+ * subtree to find the part (panel / frame / glass / hardware) under the cursor.
+ */
+export const doorPaint = createSlotPaintCapability({
+  resolveRole: resolveSlotByReRaycast,
+  applyPreview: previewSlotByUserData,
+})
diff --git a/packages/nodes/src/door/slots.ts b/packages/nodes/src/door/slots.ts
new file mode 100644
index 000000000..2e2218793
--- /dev/null
+++ b/packages/nodes/src/door/slots.ts
@@ -0,0 +1,25 @@
+import type { SlotDeclaration } from '@pascal-app/core'
+
+export type DoorSlotId = 'panel' | 'frame' | 'glass' | 'hardware'
+
+// Picker swatches. Rendering falls back to the live body/glass/hardware defaults
+// (which already track shading + theme), so these are just the indicator colours.
+const PANEL_DEFAULT = 'library:preset-softwhite'
+const FRAME_DEFAULT = 'library:preset-softwhite'
+const GLASS_DEFAULT = 'library:preset-glass'
+// Chrome — a flat (non-PBR) catalog metal finish.
+const HARDWARE_DEFAULT = 'library:metal-chrome'
+
+/**
+ * A door exposes four paintable slots: `panel` (leaf faces), `frame`, `glass`,
+ * and `hardware` (handle / hinges / closer / panic bar). The opening reveal
+ * keeps its own material.
+ */
+export function doorSlots(): SlotDeclaration[] {
+  return [
+    { slotId: 'panel', label: 'Panel', default: PANEL_DEFAULT },
+    { slotId: 'frame', label: 'Frame', default: FRAME_DEFAULT },
+    { slotId: 'glass', label: 'Glass', default: GLASS_DEFAULT },
+    { slotId: 'hardware', label: 'Hardware', default: HARDWARE_DEFAULT },
+  ]
+}
diff --git a/packages/nodes/src/shared/slot-paint.ts b/packages/nodes/src/shared/slot-paint.ts
new file mode 100644
index 000000000..c2d24066f
--- /dev/null
+++ b/packages/nodes/src/shared/slot-paint.ts
@@ -0,0 +1,264 @@
+import {
+  type AnyNode,
+  type AnyNodeId,
+  generateSceneMaterialId,
+  type MaterialSchema,
+  type PaintCapability,
+  type PaintPreviewArgs,
+  type PaintResolveArgs,
+  parseMaterialRef,
+  type SceneMaterial,
+  type SceneMaterialId,
+  sceneRegistry,
+  toSceneMaterialRef,
+  useScene,
+} from '@pascal-app/core'
+import { createMaterial, createMaterialFromPresetRef, useViewer } from '@pascal-app/viewer'
+import { type Material, type Mesh, type Object3D, Raycaster } from 'three'
+
+/**
+ * Shared paint capability for procedural kinds on the unified slot model
+ * (`node.slots: Record<slotId, MaterialRef>` + the shared scene-material
+ * palette) — the same data shape items derive from their GLB and the shelf
+ * declares via `capabilities.slots`. Distinct from `surface-paint.ts`, which
+ * writes the legacy inline `node.material` copy the plan is retiring.
+ *
+ * The commit / resolve / effective-material logic is identical across kinds;
+ * only the slot-resolution from a pointer hit and the mesh preview differ, so
+ * those are injected per kind.
+ */
+
+type SlotsNode = AnyNode & { slots?: Record<string, string> }
+
+function deepEqual(a: unknown, b: unknown): boolean {
+  if (Object.is(a, b)) return true
+  if (typeof a !== typeof b) return false
+  if (a === null || b === null) return false
+  if (Array.isArray(a) || Array.isArray(b)) {
+    if (!Array.isArray(a) || !Array.isArray(b) || a.length !== b.length) return false
+    for (let index = 0; index < a.length; index += 1) {
+      if (!deepEqual(a[index], b[index])) return false
+    }
+    return true
+  }
+  if (typeof a === 'object') {
+    const aRecord = a as Record<string, unknown>
+    const bRecord = b as Record<string, unknown>
+    const aKeys = Object.keys(aRecord)
+    const bKeys = Object.keys(bRecord)
+    if (aKeys.length !== bKeys.length) return false
+    for (const key of aKeys) {
+      if (!Object.hasOwn(bRecord, key)) return false
+      if (!deepEqual(aRecord[key], bRecord[key])) return false
+    }
+    return true
+  }
+  return false
+}
+
+function findMatchingSceneMaterial(
+  materials: Record<SceneMaterialId, SceneMaterial>,
+  material: MaterialSchema,
+): SceneMaterial | null {
+  for (const sceneMaterial of Object.values(materials)) {
+    if (deepEqual(sceneMaterial.material, material)) return sceneMaterial
+  }
+  return null
+}
+
+function commitSlotPaint(
+  node: SlotsNode,
+  role: string,
+  material: MaterialSchema | undefined,
+  materialPreset: string | undefined,
+): void {
+  const nodeId = node.id as AnyNodeId
+  const state = useScene.getState()
+  const currentNode = (state.nodes[nodeId] as SlotsNode | undefined) ?? node
+
+  let ref: string | undefined
+  let newSceneMaterial: SceneMaterial | null = null
+
+  if (material === undefined && materialPreset === undefined) {
+    ref = undefined
+  } else if (materialPreset) {
+    ref = materialPreset
+  } else if (material) {
+    const existing = findMatchingSceneMaterial(state.materials, material)
+    if (existing) {
+      ref = toSceneMaterialRef(existing.id)
+    } else {
+      const id = generateSceneMaterialId()
+      newSceneMaterial = {
+        id,
+        name: `Material ${Object.keys(state.materials).length + 1}`,
+        material,
+      }
+      ref = toSceneMaterialRef(id)
+    }
+  } else {
+    return
+  }
+
+  const nextSlots = { ...(currentNode.slots ?? {}) }
+  if (ref) nextSlots[role] = ref
+  else delete nextSlots[role]
+
+  if (newSceneMaterial) {
+    // Creating the scene material and setting the slot ref are one logical
+    // edit, so apply both in a single `set` — zundo records one history entry,
+    // and one undo removes both the ref and its (now orphaned) material.
+    const sceneMaterial = newSceneMaterial
+    useScene.setState((s) => {
+      if (s.readOnly) return s
+      const node2 = s.nodes[nodeId] as SlotsNode | undefined
+      if (!node2) return s
+      return {
+        materials: { ...s.materials, [sceneMaterial.id as SceneMaterialId]: sceneMaterial },
+        nodes: {
+          ...s.nodes,
+          [nodeId]: { ...node2, slots: nextSlots } as AnyNode,
+        },
+      }
+    })
+    useScene.getState().markDirty(nodeId)
+    return
+  }
+
+  state.updateNode(nodeId, { slots: nextSlots } as Partial<AnyNode>)
+}
+
+/** Preview material for a slot paint — mirrors the commit's resolution. */
+export function buildSlotPreviewMaterial(
+  material: MaterialSchema | undefined,
+  materialPreset: string | undefined,
+): Material | null {
+  const shading = useViewer.getState().shading
+  if (materialPreset) return createMaterialFromPresetRef(materialPreset, shading)
+  if (material) return createMaterial(material, shading)
+  return null
+}
+
+/**
+ * Preview for kinds whose meshes are produced by `def.geometry` and tagged
+ * with `userData.slotId` (+ `__fromGeometry`). Swaps every builder mesh whose
+ * slot matches `role`, leaving hosted-child meshes (which can carry a colliding
+ * `userData.slotId` from their own GLB) untouched.
+ */
+export function previewGeometrySlot(args: PaintPreviewArgs): (() => void) | null {
+  const { role, root, material, materialPreset } = args
+  const preview = buildSlotPreviewMaterial(material, materialPreset)
+  if (!preview) return () => {}
+
+  const restores: Array<() => void> = []
+  ;(root as Object3D).traverse((object) => {
+    const mesh = object as Mesh
+    if (!mesh.isMesh) return
+    const userData = mesh.userData as { slotId?: string | null; __fromGeometry?: boolean }
+    if (userData.__fromGeometry !== true) return
+    if (userData.slotId !== role) return
+    const previous = mesh.material
+    mesh.material = preview
+    restores.push(() => {
+      mesh.material = previous
+    })
+  })
+
+  if (restores.length === 0) return null
+  return () => {
+    for (let index = restores.length - 1; index >= 0; index -= 1) restores[index]?.()
+  }
+}
+
+/**
+ * Preview for kinds whose meshes are built by a viewer system (window, door)
+ * and tagged with `userData.slotId` — no `__fromGeometry` marker and no hosted
+ * children to guard against, so it swaps every mesh whose slot matches `role`.
+ */
+export function previewSlotByUserData(args: PaintPreviewArgs): (() => void) | null {
+  const { role, root, material, materialPreset } = args
+  const preview = buildSlotPreviewMaterial(material, materialPreset)
+  if (!preview) return () => {}
+
+  const restores: Array<() => void> = []
+  ;(root as Object3D).traverse((object) => {
+    const mesh = object as Mesh
+    if (!mesh.isMesh) return
+    if ((mesh.userData as { slotId?: string | null }).slotId !== role) return
+    const previous = mesh.material
+    mesh.material = preview
+    restores.push(() => {
+      mesh.material = previous
+    })
+  })
+
+  if (restores.length === 0) return null
+  return () => {
+    for (let index = restores.length - 1; index >= 0; index -= 1) restores[index]?.()
+  }
+}
+
+// Reused across calls — set from the pointer ray each time.
+const subtreeRaycaster = new Raycaster()
+
+/**
+ * Resolve the slot for a kind whose paint hit lands on a proud opening proxy
+ * (door/window: a 1m-deep invisible cutout that wins the scene raycast over the
+ * wall in front of the recessed body) rather than the part itself. Re-raycasts
+ * the kind's OWN registered subtree (ignoring everything else) and returns the
+ * first tagged sub-mesh under the cursor; falls back to the direct hit's slot
+ * (e.g. a proud part the scene raycast hit directly).
+ */
+export function resolveSlotByReRaycast(args: PaintResolveArgs): string | null {
+  const direct = (args.hitObject?.userData as { slotId?: string } | undefined)?.slotId
+  if (typeof direct === 'string') return direct
+  const root = sceneRegistry.nodes.get(args.node.id as AnyNodeId)
+  if (!root || !args.ray) return null
+  subtreeRaycaster.ray.copy(args.ray)
+  for (const hit of subtreeRaycaster.intersectObject(root, true)) {
+    const slot = (hit.object.userData as { slotId?: string }).slotId
+    if (typeof slot === 'string') return slot
+  }
+  return null
+}
+
+export type SlotPaintConfig = {
+  /** Resolve the slot id for a pointer hit (`null` = not paintable here). */
+  resolveRole: (args: PaintResolveArgs) => string | null
+  /** Apply a preview to the registered mesh subtree for `role`. */
+  applyPreview: (args: PaintPreviewArgs) => (() => void) | null
+  /**
+   * Optional legacy fallback for the picker's current-value indicator — read
+   * when no `node.slots[role]` ref exists yet (e.g. a scene painted before the
+   * kind moved onto the slot model still carries inline `material`/`preset`).
+   */
+  legacyEffective?: (
+    node: AnyNode,
+    role: string,
+  ) => { material: MaterialSchema | undefined; materialPreset: string | undefined } | null
+}
+
+export function createSlotPaintCapability(config: SlotPaintConfig): PaintCapability {
+  return {
+    resolveRole: config.resolveRole,
+    buildPatch: ({ node, role, materialPreset }) => {
+      const slots = { ...((node as SlotsNode).slots ?? {}) }
+      if (materialPreset) slots[role] = materialPreset
+      else delete slots[role]
+      return { slots } as Partial<AnyNode>
+    },
+    commit: ({ node, role, material, materialPreset }) =>
+      commitSlotPaint(node as SlotsNode, role, material, materialPreset),
+    applyPreview: config.applyPreview,
+    getEffectiveMaterial: ({ node, role }) => {
+      const ref = (node as SlotsNode).slots?.[role]
+      const parsed = parseMaterialRef(ref)
+      if (parsed) {
+        if (parsed.kind === 'library') return { material: undefined, materialPreset: ref }
+        const sceneMaterial = useScene.getState().materials[parsed.id as SceneMaterialId]
+        if (sceneMaterial) return { material: sceneMaterial.material, materialPreset: undefined }
+      }
+      return config.legacyEffective?.(node, role) ?? null
+    },
+  }
+}
diff --git a/packages/nodes/src/slab/definition.ts b/packages/nodes/src/slab/definition.ts
index 4b63d0700..fc0ab43c2 100644
--- a/packages/nodes/src/slab/definition.ts
+++ b/packages/nodes/src/slab/definition.ts
@@ -12,8 +12,10 @@ import {
 } from './floorplan-affordances'
 import { slabFloorplanMoveTarget } from './floorplan-move'
 import { buildSlabGeometry } from './geometry'
+import { slabPaint } from './paint'
 import { slabParametrics } from './parametrics'
 import { SlabNode } from './schema'
+import { slabSlots } from './slots'
 
 const HEIGHT_HANDLE_OFFSET = 0.22
 const MIN_SLAB_ELEVATION = 0.02
@@ -155,6 +157,10 @@ export const slabDefinition: NodeDefinition<typeof SlabNode> = {
     },
     duplicable: true,
     deletable: true,
+    // Unified slot model: one paintable floor surface with a declared default,
+    // painted through the registry `capabilities.paint` dispatch like the shelf.
+    slots: () => slabSlots(),
+    paint: slabPaint,
   },
 
   relations: {
diff --git a/packages/nodes/src/slab/geometry.ts b/packages/nodes/src/slab/geometry.ts
index dd1a68080..851660ec6 100644
--- a/packages/nodes/src/slab/geometry.ts
+++ b/packages/nodes/src/slab/geometry.ts
@@ -1,25 +1,28 @@
-import { getMaterialPresetByRef, type SlabNode } from '@pascal-app/core'
+import { type GeometryContext, getMaterialPresetByRef, type SlabNode } from '@pascal-app/core'
 import {
   applyMaterialPresetToMaterials,
   type ColorPreset,
   createDefaultMaterial,
   createMaterial,
   createSurfaceRoleMaterial,
-  DEFAULT_SLAB_MATERIAL,
   generateSlabGeometry,
   type RenderShading,
+  resolveMaterialRef,
+  resolveSlotDefaultMaterial,
 } from '@pascal-app/viewer'
 import { FrontSide, Group, type Material, Mesh, type Texture } from 'three'
+import { SLAB_SLOT_DEFAULT } from './slots'
 
 /**
  * Stage B builder for slab. Reuses `generateSlabGeometry` (pure
  * triangulation + hole CSG from viewer) and the same material cache
  * pattern the legacy slab renderer used.
  *
- * Materials are cached by `{material, materialPreset}` signature so
- * slabs sharing settings share the GPU resource. Cached entry mutation
- * (preset apply) is preserved — async texture loads still update the
- * rendered material after re-mount.
+ * Materials follow the unified slot model: the single `surface` slot resolves
+ * `node.slots.surface` (a shared scene material or `library:` finish) → the
+ * legacy inline `node.material` / `materialPreset` (pre-slot-model scenes) →
+ * the declared slot default colour. Textures-off collapses to the themed
+ * `floor` role — the guaranteed monochrome escape hatch.
  */
 type SlabMaterial = Material & {
   alphaMap?: Texture | null
@@ -35,19 +38,39 @@ function getSlabMaterial(
   shading: RenderShading,
   textures: boolean,
   colorPreset: ColorPreset,
-  sceneTheme?: string,
+  sceneTheme: string | undefined,
+  sceneMaterials: GeometryContext['materials'],
 ): Material {
-  // Untextured slabs (and everything in textures-off mode) take the themed
-  // 'floor' role colour. createSurfaceRoleMaterial returns a shared cached
-  // material, so it is returned as-is without the mutation below.
-  // FrontSide — DoubleSide on the role material's NodeMaterial poisons the
-  // MRT scene pass (see `materials.ts` line 77 / glazing fix 9400f1c5).
-  // Slab side faces still render correctly because `generateSlabGeometry`
-  // produces outward-facing normals on the top, bottom, and perimeter.
-  if (!textures || (!node.materialPreset && !node.material)) {
+  // Textures-off mode takes the themed 'floor' role colour — the guaranteed
+  // escape hatch, independent of any slot override. createSurfaceRoleMaterial
+  // returns a shared cached material. FrontSide — DoubleSide on the role
+  // material's NodeMaterial poisons the MRT scene pass (see `materials.ts`
+  // line 77 / glazing fix 9400f1c5). Slab side faces still render correctly
+  // because `generateSlabGeometry` produces outward-facing normals.
+  if (!textures) {
     return createSurfaceRoleMaterial('floor', colorPreset, FrontSide, sceneTheme)
   }
 
+  // Unified slot override — shared scene material or catalog `library:` finish.
+  const slotRef = node.slots?.surface
+  if (slotRef) {
+    const resolved = resolveMaterialRef(slotRef, sceneMaterials, shading)
+    if (resolved) return resolved
+  }
+
+  // Legacy inline material / preset, for scenes painted before the slot model.
+  if (node.materialPreset || node.material) {
+    return getLegacySlabMaterial(node, shading)
+  }
+
+  // Declared slot default — a catalog `library:` finish or a flat colour.
+  return resolveSlotDefaultMaterial(SLAB_SLOT_DEFAULT, shading, 0.8)
+}
+
+function getLegacySlabMaterial(node: SlabNode, shading: RenderShading): Material {
+  // Cached by `{material, materialPreset}` signature so slabs sharing settings
+  // share the GPU resource; cached entry mutation (preset apply) is preserved
+  // so async texture loads still update the rendered material after re-mount.
   const cacheKey = JSON.stringify({
     shading,
     material: node.material ?? null,
@@ -61,7 +84,7 @@ function getSlabMaterial(
     ? createDefaultMaterial('#ffffff', 0.5, shading)
     : node.material
       ? createMaterial(node.material, shading).clone()
-      : DEFAULT_SLAB_MATERIAL(shading).clone()
+      : createDefaultMaterial('#e5e5e5', 0.8, shading)
 
   if (preset) {
     applyMaterialPresetToMaterials(material, preset)
@@ -84,7 +107,7 @@ function getSlabMaterial(
 
 export function buildSlabGeometry(
   node: SlabNode,
-  _ctx?: unknown,
+  ctx?: GeometryContext,
   shading: RenderShading = 'rendered',
   textures = true,
   colorPreset: ColorPreset = 'clay',
@@ -92,10 +115,12 @@ export function buildSlabGeometry(
 ): Group {
   const group = new Group()
   const geometry = generateSlabGeometry(node)
-  const material = getSlabMaterial(node, shading, textures, colorPreset, sceneTheme)
+  const material = getSlabMaterial(node, shading, textures, colorPreset, sceneTheme, ctx?.materials)
   const mesh = new Mesh(geometry, material)
   mesh.castShadow = true
   mesh.receiveShadow = true
+  // Tag the surface so the unified slot paint can resolve the hit and preview.
+  mesh.userData.slotId = 'surface'
   const elevation = node.elevation ?? 0.05
   if (elevation < 0) mesh.position.y = elevation
   group.add(mesh)
diff --git a/packages/nodes/src/slab/paint.ts b/packages/nodes/src/slab/paint.ts
new file mode 100644
index 000000000..a5387849a
--- /dev/null
+++ b/packages/nodes/src/slab/paint.ts
@@ -0,0 +1,19 @@
+import type { AnyNode, SlabNode } from '@pascal-app/core'
+import { createSlotPaintCapability, previewGeometrySlot } from '../shared/slot-paint'
+
+/**
+ * Slab paint on the unified slot model. A slab has one paintable surface, so
+ * every face resolves to the `surface` slot; commit writes `node.slots.surface`
+ * (a shared scene-material or `library:` ref) like the shelf.
+ */
+export const slabPaint = createSlotPaintCapability({
+  resolveRole: () => 'surface',
+  applyPreview: previewGeometrySlot,
+  legacyEffective: (node: AnyNode) => {
+    const slab = node as SlabNode
+    if (slab.materialPreset || slab.material) {
+      return { material: slab.material, materialPreset: slab.materialPreset }
+    }
+    return null
+  },
+})
diff --git a/packages/nodes/src/slab/slots.ts b/packages/nodes/src/slab/slots.ts
new file mode 100644
index 000000000..094bdb0cf
--- /dev/null
+++ b/packages/nodes/src/slab/slots.ts
@@ -0,0 +1,13 @@
+import type { SlotDeclaration } from '@pascal-app/core'
+
+export type SlabSlotId = 'surface'
+
+// Declared default appearance for an unpainted slab surface in colored mode —
+// a catalog `library:<id>` finish or a `#rrggbb` colour. Textures-off collapses
+// to the themed floor role (the escape hatch).
+export const SLAB_SLOT_DEFAULT = 'library:wood-woodplank48'
+
+/** A slab exposes a single paintable floor surface. */
+export function slabSlots(): SlotDeclaration[] {
+  return [{ slotId: 'surface', label: 'Surface', default: SLAB_SLOT_DEFAULT }]
+}
diff --git a/packages/nodes/src/wall/definition.ts b/packages/nodes/src/wall/definition.ts
index 0e0face2c..d200c4367 100644
--- a/packages/nodes/src/wall/definition.ts
+++ b/packages/nodes/src/wall/definition.ts
@@ -6,6 +6,7 @@ import { wallFloorplanSiblingOverrides } from './floorplan-overrides'
 import { wallPaint } from './paint'
 import { wallParametrics } from './parametrics'
 import { WallNode } from './schema'
+import { wallSlots } from './slots'
 
 /**
  * Wall — the Phase 3 stress test of the registry-driven node model.
@@ -56,6 +57,11 @@ export const wallDefinition: NodeDefinition<typeof WallNode> = {
     // preview through this entry rather than carrying a kind-name
     // arm.
     paint: wallPaint,
+    // Declared paintable slots (interior / exterior) with their default
+    // appearance — the same `{ slotId, label, default }` contract every other
+    // paintable kind exposes. Paint still writes the legacy inline fields via
+    // `wallPaint`; migrating those into `node.slots` is a later step.
+    slots: () => wallSlots(),
   },
 
   relations: {
diff --git a/packages/nodes/src/wall/slots.ts b/packages/nodes/src/wall/slots.ts
new file mode 100644
index 000000000..d6bded909
--- /dev/null
+++ b/packages/nodes/src/wall/slots.ts
@@ -0,0 +1,17 @@
+import { type SlotDeclaration, WALL_SLOT_DEFAULT } from '@pascal-app/core'
+
+/**
+ * A wall exposes two paintable faces — interior + exterior. Painting still
+ * writes the legacy `interiorMaterial*` / `exteriorMaterial*` fields via
+ * `wallPaint` (the inline model isn't migrated to `node.slots` yet); this
+ * declaration surfaces the slot list + declared defaults for the picker and
+ * keeps walls on the same `{ slotId, label, default }` contract as every other
+ * paintable kind. The defaults come from core so the viewer's material
+ * resolver renders the identical value.
+ */
+export function wallSlots(): SlotDeclaration[] {
+  return [
+    { slotId: 'interior', label: 'Interior', default: WALL_SLOT_DEFAULT.interior },
+    { slotId: 'exterior', label: 'Exterior', default: WALL_SLOT_DEFAULT.exterior },
+  ]
+}
diff --git a/packages/nodes/src/window/definition.ts b/packages/nodes/src/window/definition.ts
index 96f8b11c2..bdd659632 100644
--- a/packages/nodes/src/window/definition.ts
+++ b/packages/nodes/src/window/definition.ts
@@ -11,8 +11,10 @@ import { buildRoofWallOpeningCut } from '../shared/roof-wall-opening-cut'
 import { buildWindowFloorplan } from './floorplan'
 import { windowWidthAffordance } from './floorplan-affordances'
 import { windowFloorplanMoveTarget } from './floorplan-move'
+import { windowPaint } from './paint'
 import { windowParametrics } from './parametrics'
 import { WindowNode } from './schema'
+import { windowSlots } from './slots'
 
 const SIDE_HANDLE_OFFSET = 0.24
 const HEIGHT_HANDLE_OFFSET = 0.24
@@ -162,6 +164,10 @@ export const windowDefinition: NodeDefinition<typeof WindowNode> = {
     // `wallId` / `roofSegmentId` are re-derived from the surface under
     // the cursor at preset placement time — see door for the pattern.
     hostRefFields: ['wallId', 'roofSegmentId', 'roofFace'],
+    // Frame / glass slots painted through the registry. The window system tags
+    // each mesh with its `userData.slotId`; paint writes `node.slots`.
+    slots: () => windowSlots(),
+    paint: windowPaint,
   },
 
   parametrics: windowParametrics,
diff --git a/packages/nodes/src/window/paint.ts b/packages/nodes/src/window/paint.ts
new file mode 100644
index 000000000..ca5120d28
--- /dev/null
+++ b/packages/nodes/src/window/paint.ts
@@ -0,0 +1,16 @@
+import {
+  createSlotPaintCapability,
+  previewSlotByUserData,
+  resolveSlotByReRaycast,
+} from '../shared/slot-paint'
+
+/**
+ * Window paint on the unified slot model. The window's opening proxy (a proud,
+ * invisible cutout) wins the shared scene raycast over the wall in front of the
+ * recessed window, so `resolveSlotByReRaycast` re-raycasts the window's own
+ * subtree to find the part (frame / glass) under the cursor.
+ */
+export const windowPaint = createSlotPaintCapability({
+  resolveRole: resolveSlotByReRaycast,
+  applyPreview: previewSlotByUserData,
+})
diff --git a/packages/nodes/src/window/slots.ts b/packages/nodes/src/window/slots.ts
new file mode 100644
index 000000000..4067d4d49
--- /dev/null
+++ b/packages/nodes/src/window/slots.ts
@@ -0,0 +1,16 @@
+import type { SlotDeclaration } from '@pascal-app/core'
+
+export type WindowSlotId = 'frame' | 'glass'
+
+// Picker swatches. Rendering falls back to the live frame/glass defaults (which
+// already track shading + theme), so these are just the indicator colours.
+const FRAME_DEFAULT = 'library:preset-softwhite'
+const GLASS_DEFAULT = 'library:preset-glass'
+
+/** A window exposes two paintable slots: the joinery frame and the glass. */
+export function windowSlots(): SlotDeclaration[] {
+  return [
+    { slotId: 'frame', label: 'Frame', default: FRAME_DEFAULT },
+    { slotId: 'glass', label: 'Glass', default: GLASS_DEFAULT },
+  ]
+}
diff --git a/packages/viewer/src/components/viewer/post-processing.tsx b/packages/viewer/src/components/viewer/post-processing.tsx
index 67645cf5b..301ccec4e 100644
--- a/packages/viewer/src/components/viewer/post-processing.tsx
+++ b/packages/viewer/src/components/viewer/post-processing.tsx
@@ -280,7 +280,6 @@ const PostProcessingPasses = ({
       denoise: denoiseEnabled,
       outline: outlineEnabled,
       perfDisable,
-      hoverHighlightMode,
       projectId,
       shading,
       rendererCtor: (renderer as any).constructor?.name,
@@ -487,9 +486,12 @@ const PostProcessingPasses = ({
       renderPipelineRef.current = null
     }
   }, [
+    // NOTE: hoverHighlightMode intentionally excluded — the hover style is
+    // pushed to uniforms in a separate effect, so a hover must NOT rebuild the
+    // whole pipeline. The uniform refs below are stable (useMemo), so they
+    // never trigger a rebuild either.
     camera,
     hoverHiddenColor,
-    hoverHighlightMode,
     hoverPulseMix,
     hoverStrength,
     hoverVisibleColor,
diff --git a/packages/viewer/src/components/viewer/scene-environment.tsx b/packages/viewer/src/components/viewer/scene-environment.tsx
new file mode 100644
index 000000000..1834c8f3e
--- /dev/null
+++ b/packages/viewer/src/components/viewer/scene-environment.tsx
@@ -0,0 +1,22 @@
+'use client'
+
+import { Environment } from '@react-three/drei'
+import { Suspense } from 'react'
+
+/**
+ * Scene IBL — drei's prefiltered environment map, exported as an opt-in
+ * <Viewer> *child* rather than baked into the Viewer component, so embed /
+ * thumbnail surfaces that don't want the HDRI fetch simply don't mount it.
+ * This is what gives PBR metals their reflections and lifts the lighting on
+ * vertical surfaces (walls), which flat directional + hemisphere lights can't
+ * do alone. Intensity is dialled below the preset default so it complements
+ * the scene lights rather than washing them out. Only visible in `rendered`
+ * shading.
+ */
+export function SceneEnvironment() {
+  return (
+    <Suspense fallback={null}>
+      <Environment preset="sunset" environmentIntensity={0.6} />
+    </Suspense>
+  )
+}
diff --git a/packages/viewer/src/index.ts b/packages/viewer/src/index.ts
index f8e55fa33..6782d31cf 100644
--- a/packages/viewer/src/index.ts
+++ b/packages/viewer/src/index.ts
@@ -18,6 +18,7 @@ export {
   DEFAULT_HOVER_STYLES,
   SSGI_PARAMS,
 } from './components/viewer/post-processing'
+export { SceneEnvironment } from './components/viewer/scene-environment'
 export { WalkthroughControls } from './components/viewer/walkthrough-controls'
 export { useAssetUrl } from './hooks/use-asset-url'
 export { useGLTFKTX2 } from './hooks/use-gltf-ktx2'
@@ -69,6 +70,7 @@ export {
   PRESET_PALETTES,
   type RenderShading,
   resolveMaterialRef,
+  resolveSlotDefaultMaterial,
   resolveSurfaceColor,
   WHITE_PALETTE,
 } from './lib/materials'
diff --git a/packages/viewer/src/lib/box-uv.ts b/packages/viewer/src/lib/box-uv.ts
new file mode 100644
index 000000000..fe73d2721
--- /dev/null
+++ b/packages/viewer/src/lib/box-uv.ts
@@ -0,0 +1,40 @@
+import type { BoxGeometry } from 'three'
+
+/**
+ * Rewrite a default `BoxGeometry`'s UVs to world scale — 1 UV unit = 1 metre —
+ * so tiled finishes (with `repeat` in tiles-per-metre) render at a consistent
+ * real-world scale instead of stretching to fit each face. Matches the
+ * world-scale UV convention used by the procedural slab/wall geometry.
+ *
+ * three.js builds box faces in the fixed order [+X, -X, +Y, -Y, +Z, -Z], four
+ * verts each, with UVs spanning 0→1 across the face. Each face's two in-plane
+ * dimensions differ, so we scale U/V per face by that face's size in metres.
+ */
+export function applyWorldScaleBoxUVs(
+  geometry: BoxGeometry,
+  w: number,
+  h: number,
+  d: number,
+): void {
+  const uv = geometry.getAttribute('uv')
+  if (!uv || uv.count < 24) return // non-default segmentation — leave as-is
+
+  // [uScaleMetres, vScaleMetres] per face, in three's face order.
+  const faceScale: Array<[number, number]> = [
+    [d, h], // +X
+    [d, h], // -X
+    [w, d], // +Y
+    [w, d], // -Y
+    [w, h], // +Z
+    [w, h], // -Z
+  ]
+
+  for (let face = 0; face < 6; face += 1) {
+    const [us, vs] = faceScale[face]!
+    for (let v = 0; v < 4; v += 1) {
+      const i = face * 4 + v
+      uv.setXY(i, uv.getX(i) * us, uv.getY(i) * vs)
+    }
+  }
+  uv.needsUpdate = true
+}
diff --git a/packages/viewer/src/lib/materials.ts b/packages/viewer/src/lib/materials.ts
index fbfdc1acd..677b1d13f 100644
--- a/packages/viewer/src/lib/materials.ts
+++ b/packages/viewer/src/lib/materials.ts
@@ -516,6 +516,26 @@ export function resolveMaterialRef(
   return createMaterial(sceneMaterial.material, shading)
 }
 
+/**
+ * Resolve a node kind's declared slot default — either a catalog `library:<id>`
+ * finish or a flat `#rrggbb` colour — to a renderable material. Shared by the
+ * procedural kinds whose colored-mode unpainted appearance comes from a
+ * declarative default (slab, wall).
+ */
+export function resolveSlotDefaultMaterial(
+  slotDefault: string,
+  shading: RenderShading = 'rendered',
+  roughness = 0.9,
+): THREE.Material {
+  if (parseMaterialRef(slotDefault)?.kind === 'library') {
+    return (
+      createMaterialFromPresetRef(slotDefault, shading) ??
+      createDefaultMaterial('#ffffff', roughness, shading)
+    )
+  }
+  return createDefaultMaterial(slotDefault, roughness, shading)
+}
+
 export function createDefaultMaterial(
   color = '#ffffff',
   roughness = 0.9,
diff --git a/packages/viewer/src/systems/door/door-system.tsx b/packages/viewer/src/systems/door/door-system.tsx
index 2a93b9265..3342f4fd7 100644
--- a/packages/viewer/src/systems/door/door-system.tsx
+++ b/packages/viewer/src/systems/door/door-system.tsx
@@ -5,6 +5,8 @@ import {
   DoorNode as DoorNodeSchema,
   getDoorRenderOpenAmount,
   getEffectiveNode,
+  type SceneMaterial,
+  type SceneMaterialId,
   sceneRegistry,
   useInteractive,
   useLiveNodeOverrides,
@@ -13,19 +15,44 @@ import {
 import { useFrame } from '@react-three/fiber'
 import { useEffect, useRef } from 'react'
 import * as THREE from 'three'
+import { applyWorldScaleBoxUVs } from '../../lib/box-uv'
 import {
+  type ColorPreset,
+  createDefaultMaterial,
   createSurfaceRoleMaterial,
   glassMaterial as defaultGlassMaterial,
   baseMaterial as getBaseMaterial,
+  type RenderShading,
+  resolveMaterialRef,
 } from '../../lib/materials'
 import useViewer from '../../store/use-viewer'
 
 // Invisible material for root mesh — used as selection hitbox only
 const hitboxMaterial = new THREE.MeshBasicMaterial({ visible: false })
 const defaultRevealMaterial = new THREE.MeshBasicMaterial({ color: '#7f766c' })
+// Door hardware (handle / hinges / closer / panic bar) renders a catalog metal
+// finish by default (chrome), separate from the door body. The flat material is
+// only a fallback if the catalog ref ever fails to resolve.
+const HARDWARE_DEFAULT_REF = 'library:metal-chrome'
+// Door body defaults to a catalog colour (generic approach). Glass keeps the
+// built-in FrontSide glass material — the catalog `preset-glass` is DoubleSide,
+// which poisons the WebGPU MRT scene pass.
+const PANEL_DEFAULT_REF = 'library:preset-softwhite'
+const FRAME_DEFAULT_REF = 'library:preset-softwhite'
+const GLASS_DEFAULT_REF = 'library:preset-glass'
+const defaultHardwareMaterial = createDefaultMaterial('#3a3a3a', 0.4)
 let baseMaterial = getBaseMaterial()
+let frameMaterial: THREE.Material = getBaseMaterial()
 let revealMaterial: THREE.Material = defaultRevealMaterial
 let glassMaterial: THREE.Material = defaultGlassMaterial
+let hardwareMaterial: THREE.Material = defaultHardwareMaterial
+let currentDoorSlot: string | undefined
+// Per-frame viewer state, captured so the per-node mesh builder (which runs
+// outside React) can resolve each door's slot materials.
+let currentShading: RenderShading = 'rendered'
+let currentTextures = true
+let currentColorPreset: ColorPreset = 'clay'
+let currentSceneMaterials: Record<SceneMaterialId, SceneMaterial> | undefined
 
 const DOOR_RENDER_DEFAULTS = DoorNodeSchema.parse({ id: 'door_render_default' })
 const MAX_DOOR_REBUILDS_PER_FRAME = 16
@@ -50,6 +77,7 @@ export const DoorSystem = () => {
   const shading = useViewer((state) => state.shading)
   const textures = useViewer((state) => state.textures)
   const colorPreset = useViewer((state) => state.colorPreset)
+  const sceneMaterials = useScene((state) => state.materials)
   const materialRevisionRef = useRef<string | null>(null)
   // Subscribe so an override-only update (no scene write) still re-runs
   // the component, letting the gate below pick up the latest dirtyNodes
@@ -59,8 +87,10 @@ export const DoorSystem = () => {
 
   const joineryMaterial = createSurfaceRoleMaterial('joinery', colorPreset)
   baseMaterial = textures ? getBaseMaterial(shading) : joineryMaterial
+  frameMaterial = textures ? getBaseMaterial(shading) : joineryMaterial
   revealMaterial = textures ? defaultRevealMaterial : joineryMaterial
   glassMaterial = textures ? defaultGlassMaterial : joineryMaterial
+  hardwareMaterial = textures ? defaultHardwareMaterial : joineryMaterial
 
   useEffect(() => {
     const materialRevision = `${shading}:${textures ? 'textures' : 'solid'}:${colorPreset}`
@@ -75,12 +105,29 @@ export const DoorSystem = () => {
     }
   })
 
+  // Editing a scene material a door slot references must rebuild that door
+  // (door meshes are built by this system, not <GeometrySystem>).
+  useEffect(() => {
+    const nodes = useScene.getState().nodes
+    for (const node of Object.values(nodes)) {
+      if (node?.type !== 'door') continue
+      if (!nodeReferencesSceneMaterial(node)) continue
+      useScene.getState().dirtyNodes.add(node.id as AnyNodeId)
+    }
+  }, [sceneMaterials])
+
   useFrame(() => {
     if (dirtyNodes.size === 0) return
     const frameJoineryMaterial = createSurfaceRoleMaterial('joinery', colorPreset)
     baseMaterial = textures ? getBaseMaterial(shading) : frameJoineryMaterial
+    frameMaterial = textures ? getBaseMaterial(shading) : frameJoineryMaterial
     revealMaterial = textures ? defaultRevealMaterial : frameJoineryMaterial
     glassMaterial = textures ? defaultGlassMaterial : frameJoineryMaterial
+    hardwareMaterial = textures ? defaultHardwareMaterial : frameJoineryMaterial
+    currentShading = shading
+    currentTextures = textures
+    currentColorPreset = colorPreset
+    currentSceneMaterials = sceneMaterials
 
     const nodes = useScene.getState().nodes
     const dirtyDoorIds: AnyNodeId[] = []
@@ -134,6 +181,59 @@ export const DoorSystem = () => {
   return null
 }
 
+function tagDoorSlot(mesh: THREE.Mesh): THREE.Mesh {
+  mesh.userData.slotId = currentDoorSlot
+  return mesh
+}
+
+function nodeReferencesSceneMaterial(node: { slots?: Record<string, string> }): boolean {
+  const slots = node.slots
+  if (!slots) return false
+  for (const ref of Object.values(slots)) {
+    if (typeof ref === 'string' && ref.startsWith('scene:')) return true
+  }
+  return false
+}
+
+type DoorMaterialSlotId = 'panel' | 'frame' | 'glass' | 'hardware'
+
+function doorSlotDefault(slotId: DoorMaterialSlotId): THREE.Material {
+  if (!currentTextures) return createSurfaceRoleMaterial('joinery', currentColorPreset)
+  if (slotId === 'glass') {
+    return (
+      resolveMaterialRef(GLASS_DEFAULT_REF, currentSceneMaterials, currentShading) ??
+      defaultGlassMaterial
+    )
+  }
+  if (slotId === 'hardware') {
+    return (
+      resolveMaterialRef(HARDWARE_DEFAULT_REF, currentSceneMaterials, currentShading) ??
+      defaultHardwareMaterial
+    )
+  }
+  if (slotId === 'frame') {
+    return (
+      resolveMaterialRef(FRAME_DEFAULT_REF, currentSceneMaterials, currentShading) ??
+      getBaseMaterial(currentShading)
+    )
+  }
+  return (
+    resolveMaterialRef(PANEL_DEFAULT_REF, currentSceneMaterials, currentShading) ??
+    getBaseMaterial(currentShading)
+  )
+}
+
+// Resolve a door's slot to a material: the `node.slots` override (colored mode
+// only) → the body/glass/hardware default. Textures-off ignores overrides — the
+// monochrome escape hatch.
+function resolveDoorSlotMaterial(node: DoorNode, slotId: DoorMaterialSlotId): THREE.Material {
+  const fallback = doorSlotDefault(slotId)
+  if (!currentTextures) return fallback
+  const ref = node.slots?.[slotId]
+  if (!ref) return fallback
+  return resolveMaterialRef(ref, currentSceneMaterials, currentShading) ?? fallback
+}
+
 function addBox(
   parent: THREE.Object3D,
   material: THREE.Material,
@@ -144,8 +244,11 @@ function addBox(
   y: number,
   z: number,
 ) {
-  const m = new THREE.Mesh(new THREE.BoxGeometry(w, h, d), material)
+  const geometry = new THREE.BoxGeometry(w, h, d)
+  applyWorldScaleBoxUVs(geometry, w, h, d)
+  const m = new THREE.Mesh(geometry, material)
   m.position.set(x, y, z)
+  tagDoorSlot(m)
   parent.add(m)
 }
 
@@ -160,9 +263,12 @@ function addRotatedBox(
   z: number,
   rotationY: number,
 ) {
-  const m = new THREE.Mesh(new THREE.BoxGeometry(w, h, d), material)
+  const geometry = new THREE.BoxGeometry(w, h, d)
+  applyWorldScaleBoxUVs(geometry, w, h, d)
+  const m = new THREE.Mesh(geometry, material)
   m.position.set(x, y, z)
   m.rotation.y = rotationY
+  tagDoorSlot(m)
   parent.add(m)
 }
 
@@ -177,9 +283,12 @@ function addBoxWithRotation(
   z: number,
   rotation: [number, number, number],
 ) {
-  const m = new THREE.Mesh(new THREE.BoxGeometry(w, h, d), material)
+  const geometry = new THREE.BoxGeometry(w, h, d)
+  applyWorldScaleBoxUVs(geometry, w, h, d)
+  const m = new THREE.Mesh(geometry, material)
   m.position.set(x, y, z)
   m.rotation.set(rotation[0], rotation[1], rotation[2])
+  tagDoorSlot(m)
   parent.add(m)
 }
 
@@ -196,6 +305,7 @@ function addShape(
   })
   geometry.translate(0, 0, -depth / 2)
   const mesh = new THREE.Mesh(geometry, material)
+  tagDoorSlot(mesh)
   parent.add(mesh)
 }
 
@@ -215,6 +325,7 @@ function addShapeAt(
   })
   geometry.translate(x, y, z - depth / 2)
   const mesh = new THREE.Mesh(geometry, material)
+  tagDoorSlot(mesh)
   parent.add(mesh)
 }
 
@@ -757,6 +868,7 @@ function addLeafSegmentContent({
   const cpX = contentPadding[0]
   const cpY = contentPadding[1]
   if (renderPerimeterFrame && shouldRenderFrame && cpY > 0) {
+    currentDoorSlot = 'panel'
     addLeafBox(
       baseMaterial,
       leafWidth,
@@ -778,6 +890,7 @@ function addLeafSegmentContent({
   }
   if (renderPerimeterFrame && shouldRenderFrame && cpX > 0) {
     const innerH = leafHeight - 2 * cpY
+    currentDoorSlot = 'panel'
     addLeafBox(
       baseMaterial,
       cpX,
@@ -857,6 +970,7 @@ function addLeafSegmentContent({
 
     if (seg.type !== 'empty') {
       cx = leafCenterX - contentW / 2
+      currentDoorSlot = 'panel'
       for (let c = 0; c < numCols - 1; c++) {
         cx += colWidths[c]!
         const dividerLeft = cx
@@ -894,6 +1008,7 @@ function addLeafSegmentContent({
       const colX = colXCenters[c]!
 
       if (seg.type === 'glass') {
+        currentDoorSlot = 'glass'
         const glassDepth = Math.max(0.004, leafDepth * 0.15)
         const segmentLeft = colX - colW / 2
         const segmentRight = colX + colW / 2
@@ -914,6 +1029,7 @@ function addLeafSegmentContent({
           addLeafBox(glassMaterial, colW, segH, glassDepth, colX, segCenterY, 0)
         }
       } else if (seg.type === 'panel') {
+        currentDoorSlot = 'panel'
         const segmentLeft = colX - colW / 2
         const segmentRight = colX + colW / 2
         const outerPanelShape =
@@ -1051,6 +1167,7 @@ function addDoorLeaf(
   const usesShapedLeafFrame = openingShape === 'rounded' || openingShape === 'arch'
 
   if (usesShapedLeafFrame && hasLeafContent) {
+    currentDoorSlot = 'panel'
     if (openingShape === 'rounded') {
       const roundedLeafShape = roundedBoundary
         ? createRoundedClippedLeafFrameShape(
@@ -1141,6 +1258,7 @@ function addDoorLeaf(
   })
 
   if (hasLeafContent && handle) {
+    currentDoorSlot = 'hardware'
     const handleY = handleHeight - doorHeight / 2
     const faceZ = leafDepth / 2
     const handleX =
@@ -1148,20 +1266,21 @@ function addDoorLeaf(
         ? leafCenterX + leafWidth / 2 - 0.045
         : leafCenterX - leafWidth / 2 + 0.045
 
-    addLeafBox(baseMaterial, 0.028, 0.14, 0.01, handleX, handleY, faceZ + 0.005)
-    addLeafBox(baseMaterial, 0.022, 0.1, 0.035, handleX, handleY, faceZ + 0.025)
+    addLeafBox(hardwareMaterial, 0.028, 0.14, 0.01, handleX, handleY, faceZ + 0.005)
+    addLeafBox(hardwareMaterial, 0.022, 0.1, 0.035, handleX, handleY, faceZ + 0.025)
 
     if (handleBothSides) {
-      addLeafBox(baseMaterial, 0.028, 0.14, 0.01, handleX, handleY, -faceZ - 0.005)
-      addLeafBox(baseMaterial, 0.022, 0.1, 0.035, handleX, handleY, -faceZ - 0.025)
+      addLeafBox(hardwareMaterial, 0.028, 0.14, 0.01, handleX, handleY, -faceZ - 0.005)
+      addLeafBox(hardwareMaterial, 0.022, 0.1, 0.035, handleX, handleY, -faceZ - 0.025)
     }
   }
 
   if (hasLeafContent && doorCloser) {
+    currentDoorSlot = 'hardware'
     const closerY = leafCenterY + leafHeight / 2 - 0.04
-    addLeafBox(baseMaterial, 0.28, 0.055, 0.055, leafCenterX, closerY, leafDepth / 2 + 0.03)
+    addLeafBox(hardwareMaterial, 0.28, 0.055, 0.055, leafCenterX, closerY, leafDepth / 2 + 0.03)
     addLeafBox(
-      baseMaterial,
+      hardwareMaterial,
       0.14,
       0.015,
       0.015,
@@ -1172,18 +1291,37 @@ function addDoorLeaf(
   }
 
   if (hasLeafContent && panicBar) {
+    currentDoorSlot = 'hardware'
     const barY = panicBarHeight - doorHeight / 2
-    addLeafBox(baseMaterial, leafWidth * 0.72, 0.04, 0.055, leafCenterX, barY, leafDepth / 2 + 0.03)
+    addLeafBox(
+      hardwareMaterial,
+      leafWidth * 0.72,
+      0.04,
+      0.055,
+      leafCenterX,
+      barY,
+      leafDepth / 2 + 0.03,
+    )
   }
 
   if (hasLeafContent) {
+    currentDoorSlot = 'hardware'
     const hingeMarkerX = hingeSide === 'right' ? hingeX - 0.012 : hingeX + 0.012
     const hingeH = 0.1
     const hingeW = 0.024
     const hingeD = leafDepth + 0.016
-    addBox(mesh, baseMaterial, hingeW, hingeH, hingeD, hingeMarkerX, leafBottom + 0.25, 0)
-    addBox(mesh, baseMaterial, hingeW, hingeH, hingeD, hingeMarkerX, (leafBottom + leafTop) / 2, 0)
-    addBox(mesh, baseMaterial, hingeW, hingeH, hingeD, hingeMarkerX, leafTop - 0.25, 0)
+    addBox(mesh, hardwareMaterial, hingeW, hingeH, hingeD, hingeMarkerX, leafBottom + 0.25, 0)
+    addBox(
+      mesh,
+      hardwareMaterial,
+      hingeW,
+      hingeH,
+      hingeD,
+      hingeMarkerX,
+      (leafBottom + leafTop) / 2,
+      0,
+    )
+    addBox(mesh, hardwareMaterial, hingeW, hingeH, hingeD, hingeMarkerX, leafTop - 0.25, 0)
   }
 }
 
@@ -1222,9 +1360,10 @@ function addFoldingDoor(
   const panelLength = insideWidth / panelCount
   const foldAngle = Math.PI * 0.44 * foldAmount
 
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    baseMaterial,
+    hardwareMaterial,
     insideWidth,
     Math.min(frameThickness * 0.5, 0.025),
     Math.max(frameDepth * 0.45, 0.035),
@@ -1244,6 +1383,7 @@ function addFoldingDoor(
     })
   }
 
+  currentDoorSlot = undefined
   for (let index = 0; index < panelCount; index++) {
     const start = vertices[index]!
     const end = vertices[index + 1]!
@@ -1291,6 +1431,7 @@ function addFoldingDoor(
       keepFrameWhenEmpty: true,
     })
 
+    currentDoorSlot = undefined
     for (const point of [start, end]) {
       addBox(
         mesh,
@@ -1307,9 +1448,10 @@ function addFoldingDoor(
 
   const handlePoint = vertices[vertices.length - 1]!
   const handleY = handleHeight - doorHeight / 2
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    baseMaterial,
+    hardwareMaterial,
     0.035,
     0.16,
     leafDepth + 0.035,
@@ -1319,7 +1461,7 @@ function addFoldingDoor(
   )
   addBox(
     mesh,
-    baseMaterial,
+    hardwareMaterial,
     0.035,
     0.16,
     leafDepth + 0.035,
@@ -1368,9 +1510,10 @@ function addPocketDoor(
   const handleY = handleHeight - doorHeight / 2
   const handleX = leafCenterX - slideSign * (leafWidth / 2 - 0.055)
 
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    baseMaterial,
+    hardwareMaterial,
     insideWidth * 2,
     Math.min(frameThickness * 0.45, 0.024),
     Math.max(frameDepth * 0.38, 0.03),
@@ -1378,6 +1521,7 @@ function addPocketDoor(
     topY - 0.018,
     0,
   )
+  currentDoorSlot = undefined
   addBox(
     mesh,
     revealMaterial,
@@ -1419,8 +1563,27 @@ function addPocketDoor(
     segments,
     contentPadding,
   })
-  addBox(mesh, baseMaterial, 0.03, 0.18, leafDepth + 0.03, handleX, handleY, leafDepth / 2 + 0.02)
-  addBox(mesh, baseMaterial, 0.03, 0.18, leafDepth + 0.03, handleX, handleY, -leafDepth / 2 - 0.02)
+  currentDoorSlot = 'hardware'
+  addBox(
+    mesh,
+    hardwareMaterial,
+    0.03,
+    0.18,
+    leafDepth + 0.03,
+    handleX,
+    handleY,
+    leafDepth / 2 + 0.02,
+  )
+  addBox(
+    mesh,
+    hardwareMaterial,
+    0.03,
+    0.18,
+    leafDepth + 0.03,
+    handleX,
+    handleY,
+    -leafDepth / 2 - 0.02,
+  )
 }
 
 function addBarnDoor(
@@ -1465,9 +1628,10 @@ function addBarnDoor(
   const handleX = leafCenterX - slideSign * (leafWidth / 2 - 0.075)
   const wheelY = trackY - 0.075
 
-  addBox(mesh, revealMaterial, railLength, 0.035, 0.035, railCenterX, trackY, faceZ + 0.01)
-  addBox(mesh, revealMaterial, 0.05, 0.13, 0.035, -insideWidth / 2, trackY - 0.02, faceZ + 0.01)
-  addBox(mesh, revealMaterial, 0.05, 0.13, 0.035, insideWidth / 2, trackY - 0.02, faceZ + 0.01)
+  currentDoorSlot = 'hardware'
+  addBox(mesh, hardwareMaterial, railLength, 0.035, 0.035, railCenterX, trackY, faceZ + 0.01)
+  addBox(mesh, hardwareMaterial, 0.05, 0.13, 0.035, -insideWidth / 2, trackY - 0.02, faceZ + 0.01)
+  addBox(mesh, hardwareMaterial, 0.05, 0.13, 0.035, insideWidth / 2, trackY - 0.02, faceZ + 0.01)
 
   const addBarnLeafBox = (
     material: THREE.Material,
@@ -1491,6 +1655,7 @@ function addBarnDoor(
     keepFrameWhenEmpty: true,
   })
 
+  currentDoorSlot = undefined
   addRotatedBox(
     mesh,
     revealMaterial,
@@ -1514,11 +1679,12 @@ function addBarnDoor(
     0.52,
   )
 
+  currentDoorSlot = 'hardware'
   for (const offset of [-leafWidth * 0.28, leafWidth * 0.28]) {
-    addBox(mesh, revealMaterial, 0.085, 0.085, 0.035, leafCenterX + offset, wheelY, faceZ + 0.022)
+    addBox(mesh, hardwareMaterial, 0.085, 0.085, 0.035, leafCenterX + offset, wheelY, faceZ + 0.022)
     addBox(
       mesh,
-      revealMaterial,
+      hardwareMaterial,
       0.026,
       0.16,
       0.026,
@@ -1528,9 +1694,10 @@ function addBarnDoor(
     )
   }
 
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    baseMaterial,
+    hardwareMaterial,
     0.032,
     0.22,
     leafDepth + 0.034,
@@ -1540,7 +1707,7 @@ function addBarnDoor(
   )
   addBox(
     mesh,
-    baseMaterial,
+    hardwareMaterial,
     0.032,
     0.22,
     leafDepth + 0.034,
@@ -1595,10 +1762,20 @@ function addSlidingDoor(
   const handleY = handleHeight - doorHeight / 2
   const handleX = activeX + activeSign * (panelWidth / 2 - 0.06)
 
-  addBox(mesh, revealMaterial, insideWidth, 0.024, Math.max(frameDepth * 0.32, 0.026), 0, railY, 0)
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    revealMaterial,
+    hardwareMaterial,
+    insideWidth,
+    0.024,
+    Math.max(frameDepth * 0.32, 0.026),
+    0,
+    railY,
+    0,
+  )
+  addBox(
+    mesh,
+    hardwareMaterial,
     insideWidth,
     0.018,
     Math.max(frameDepth * 0.28, 0.022),
@@ -1649,8 +1826,27 @@ function addSlidingDoor(
     contentPadding,
     keepFrameWhenEmpty: true,
   })
-  addBox(mesh, baseMaterial, 0.032, 0.24, 0.016, handleX, handleY, frontZ + leafDepth / 2 + 0.01)
-  addBox(mesh, baseMaterial, 0.032, 0.24, 0.016, handleX, handleY, frontZ - leafDepth / 2 - 0.01)
+  currentDoorSlot = 'hardware'
+  addBox(
+    mesh,
+    hardwareMaterial,
+    0.032,
+    0.24,
+    0.016,
+    handleX,
+    handleY,
+    frontZ + leafDepth / 2 + 0.01,
+  )
+  addBox(
+    mesh,
+    hardwareMaterial,
+    0.032,
+    0.24,
+    0.016,
+    handleX,
+    handleY,
+    frontZ - leafDepth / 2 - 0.01,
+  )
 }
 
 function addGarageSectionalDoor(
@@ -1687,9 +1883,10 @@ function addGarageSectionalDoor(
   const railY = leafCenterY + leafHeight / 2 - 0.04
   const railZ = -travelDepth / 2
 
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    revealMaterial,
+    hardwareMaterial,
     0.035,
     Math.max(0.04, frameThickness * 0.75),
     travelDepth,
@@ -1699,7 +1896,7 @@ function addGarageSectionalDoor(
   )
   addBox(
     mesh,
-    revealMaterial,
+    hardwareMaterial,
     0.035,
     Math.max(0.04, frameThickness * 0.75),
     travelDepth,
@@ -1730,6 +1927,7 @@ function addGarageSectionalDoor(
     const trimDepth = 0.01
     const trimFaceOffset = leafDepth / 2 + trimDepth + 0.006
     const addSectionalTrim = (localY: number) => {
+      currentDoorSlot = undefined
       addBoxWithRotation(
         mesh,
         revealMaterial,
@@ -1743,6 +1941,7 @@ function addGarageSectionalDoor(
       )
     }
 
+    currentDoorSlot = 'panel'
     addBoxWithRotation(
       mesh,
       baseMaterial,
@@ -1758,7 +1957,8 @@ function addGarageSectionalDoor(
     addSectionalTrim(-revealOffset)
   }
 
-  addBox(mesh, revealMaterial, insideWidth, 0.032, Math.max(frameDepth * 0.36, 0.03), 0, railY, 0)
+  currentDoorSlot = 'hardware'
+  addBox(mesh, hardwareMaterial, insideWidth, 0.032, Math.max(frameDepth * 0.36, 0.03), 0, railY, 0)
 }
 
 function addGarageRollupDoor(
@@ -1791,9 +1991,10 @@ function addGarageRollupDoor(
   const drumY = topY + drumMaxRadius * 0.12
   const drumZ = -frameDepth / 2 - drumMaxRadius * 0.72
 
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    revealMaterial,
+    hardwareMaterial,
     0.032,
     leafHeight,
     Math.max(frameDepth * 0.48, 0.035),
@@ -1803,7 +2004,7 @@ function addGarageRollupDoor(
   )
   addBox(
     mesh,
-    revealMaterial,
+    hardwareMaterial,
     0.032,
     leafHeight,
     Math.max(frameDepth * 0.48, 0.035),
@@ -1813,8 +2014,10 @@ function addGarageRollupDoor(
   )
 
   if (visibleHeight > 0.01) {
+    currentDoorSlot = 'panel'
     addBox(mesh, baseMaterial, insideWidth, visibleHeight, leafDepth, 0, curtainCenterY, 0)
 
+    currentDoorSlot = undefined
     for (let index = 0; index < visibleSlatCount; index++) {
       const y = topY - Math.min(visibleHeight, index * slatHeight)
       addBox(mesh, revealMaterial, insideWidth - 0.08, 0.01, 0.012, 0, y, leafDepth / 2 + 0.012)
@@ -1832,17 +2035,20 @@ function addGarageRollupDoor(
     )
   }
 
+  currentDoorSlot = 'panel'
   const drum = new THREE.Mesh(
     new THREE.CylinderGeometry(drumMaxRadius, drumMaxRadius, insideWidth + frameThickness, 36),
     baseMaterial,
   )
   drum.position.set(0, drumY, drumZ)
   drum.rotation.z = Math.PI / 2
+  tagDoorSlot(drum)
   mesh.add(drum)
 
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    revealMaterial,
+    hardwareMaterial,
     insideWidth + frameThickness,
     0.026,
     Math.max(frameDepth * 0.52, 0.04),
@@ -1881,9 +2087,10 @@ function addGarageTiltupDoor(
   const railY = hingeY - frameThickness * 0.35
   const railZ = -railLength / 2
 
+  currentDoorSlot = 'hardware'
   addBox(
     mesh,
-    revealMaterial,
+    hardwareMaterial,
     0.03,
     Math.max(frameThickness * 0.7, 0.035),
     railLength,
@@ -1893,7 +2100,7 @@ function addGarageTiltupDoor(
   )
   addBox(
     mesh,
-    revealMaterial,
+    hardwareMaterial,
     0.03,
     Math.max(frameThickness * 0.7, 0.035),
     railLength,
@@ -1902,6 +2109,7 @@ function addGarageTiltupDoor(
     railZ,
   )
 
+  currentDoorSlot = 'panel'
   addBoxWithRotation(
     mesh,
     baseMaterial,
@@ -1919,6 +2127,7 @@ function addGarageTiltupDoor(
   const trimDepth = 0.012
   const trimFaceOffset = leafDepth / 2 + trimDepth + 0.006
   const addTiltupTrim = (localX: number, localY: number, trimWidth: number, trimHeight: number) => {
+    currentDoorSlot = undefined
     addBoxWithRotation(
       mesh,
       revealMaterial,
@@ -1937,7 +2146,17 @@ function addGarageTiltupDoor(
   addTiltupTrim(-insetWidth / 2, 0, 0.018, insetHeight)
   addTiltupTrim(insetWidth / 2, 0, 0.018, insetHeight)
 
-  addBox(mesh, revealMaterial, insideWidth, 0.026, Math.max(frameDepth * 0.4, 0.035), 0, hingeY, 0)
+  currentDoorSlot = 'hardware'
+  addBox(
+    mesh,
+    hardwareMaterial,
+    insideWidth,
+    0.026,
+    Math.max(frameDepth * 0.4, 0.035),
+    0,
+    hingeY,
+    0,
+  )
 }
 
 function getEffectiveOpeningShape(node: DoorNode): DoorNode['openingShape'] {
@@ -1951,6 +2170,7 @@ function getEffectiveOpeningShape(node: DoorNode): DoorNode['openingShape'] {
 
 function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
   const node = normalizeDoorNodeForRender(rawNode)
+  currentDoorSlot = undefined
 
   // Root mesh is an invisible hitbox; all visuals live in child meshes
   mesh.geometry.dispose()
@@ -1968,6 +2188,14 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
     mesh.remove(child)
   }
 
+  // Point the builder-facing materials at this door's slot overrides for the
+  // duration of its build (recomputed per node, so the next door resets cleanly
+  // without a restore). Reveal keeps its own material.
+  baseMaterial = resolveDoorSlotMaterial(node, 'panel')
+  frameMaterial = resolveDoorSlotMaterial(node, 'frame')
+  glassMaterial = resolveDoorSlotMaterial(node, 'glass')
+  hardwareMaterial = resolveDoorSlotMaterial(node, 'hardware')
+
   const {
     width,
     height,
@@ -2012,6 +2240,7 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
   const swingDirectionSign = swingDirection === 'inward' ? 1 : -1
 
   // ── Frame members ──
+  currentDoorSlot = 'frame'
   if (openingShape === 'arch') {
     const frameBottom = -height / 2
     const frameTop = height / 2
@@ -2025,7 +2254,7 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
 
     addBox(
       mesh,
-      baseMaterial,
+      frameMaterial,
       frameThickness,
       postHeight,
       frameDepth,
@@ -2035,7 +2264,7 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
     )
     addBox(
       mesh,
-      baseMaterial,
+      frameMaterial,
       frameThickness,
       postHeight,
       frameDepth,
@@ -2045,7 +2274,7 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
     )
     addShape(
       mesh,
-      baseMaterial,
+      frameMaterial,
       useShallowHeadBar
         ? createArchHeadBarShape(width, frameHeadBottomY, frameSpringY, frameTop)
         : createArchBandShape(
@@ -2061,7 +2290,7 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
   } else if (openingShape === 'rounded') {
     addShape(
       mesh,
-      baseMaterial,
+      frameMaterial,
       createRoundedDoorFrameShape(
         width,
         height,
@@ -2074,7 +2303,7 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
     // Left post — full height
     addBox(
       mesh,
-      baseMaterial,
+      frameMaterial,
       frameThickness,
       height,
       frameDepth,
@@ -2085,7 +2314,7 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
     // Right post — full height
     addBox(
       mesh,
-      baseMaterial,
+      frameMaterial,
       frameThickness,
       height,
       frameDepth,
@@ -2096,7 +2325,7 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
     // Head (top bar) — full width
     addBox(
       mesh,
-      baseMaterial,
+      frameMaterial,
       width,
       frameThickness,
       frameDepth,
@@ -2108,9 +2337,10 @@ function updateDoorMesh(rawNode: DoorNode, mesh: THREE.Mesh) {
 
   // ── Threshold (inside the frame) ──
   if (threshold) {
+    currentDoorSlot = 'frame'
     addBox(
       mesh,
-      baseMaterial,
+      frameMaterial,
       insideWidth,
       thresholdHeight,
       frameDepth,
@@ -2331,6 +2561,10 @@ function syncDoorCutout(node: DoorNode, mesh: THREE.Mesh) {
   if (!cutout) {
     cutout = new THREE.Mesh()
     cutout.name = 'cutout'
+    // The cutout (a 1m-deep CSG helper, invisible) is proud of the wall, so it
+    // wins the scene raycast over the wall in front of the recessed door body —
+    // making it the selection AND paint hit target for the whole opening. The
+    // paint capability then re-raycasts the door's parts to find the slot.
     mesh.add(cutout)
   }
   cutout.geometry.dispose()
diff --git a/packages/viewer/src/systems/wall/wall-materials.ts b/packages/viewer/src/systems/wall/wall-materials.ts
index 3c807dc8b..a37690719 100644
--- a/packages/viewer/src/systems/wall/wall-materials.ts
+++ b/packages/viewer/src/systems/wall/wall-materials.ts
@@ -2,7 +2,9 @@ import {
   getEffectiveWallSurfaceMaterial,
   getMaterialPresetByRef,
   getWallSurfaceMaterialSignature,
+  parseMaterialRef,
   resolveMaterial,
+  WALL_SLOT_DEFAULT,
   type WallNode,
   type WallSurfaceMaterialSpec,
 } from '@pascal-app/core'
@@ -12,6 +14,7 @@ import { MeshLambertNodeMaterial, MeshStandardNodeMaterial } from 'three/webgpu'
 import {
   baseMaterial,
   type ColorPreset,
+  createDefaultMaterial,
   createMaterial,
   createMaterialFromPresetRef,
   createSurfaceRoleMaterial,
@@ -88,6 +91,15 @@ function hasExplicitMaterial(spec: WallSurfaceMaterialSpec): boolean {
   return Boolean(spec.materialPreset || spec.material)
 }
 
+// Resolve a wall face's declared default — a catalog `library:` finish or a
+// flat colour — to a renderable material.
+function resolveWallSlotDefault(slotDefault: string, shading: RenderShading): Material {
+  if (parseMaterialRef(slotDefault)?.kind === 'library') {
+    return createMaterialFromPresetRef(slotDefault, shading) ?? baseMaterial(shading)
+  }
+  return createDefaultMaterial(slotDefault, 0.9, shading)
+}
+
 function getSurfaceColor(spec: WallSurfaceMaterialSpec, fallback = DEFAULT_WALL_COLOR): string {
   const preset = getMaterialPresetByRef(spec.materialPreset)
   if (preset?.mapProperties?.color) {
@@ -216,17 +228,19 @@ export function getMaterialsForWall(
   const exteriorSpec = getEffectiveWallSurfaceMaterial(wallNode, 'exterior')
   const wallRoleMaterial = createSurfaceRoleMaterial('wall', colorPreset, undefined, sceneTheme)
 
-  // Untextured surfaces take the themed wall role colour even with textures on;
-  // only surfaces with an explicit preset/material keep their texture.
+  // Colored mode: an unpainted face takes its declared slot default (parity
+  // with the retired DEFAULT_WALL_MATERIAL); only an explicit preset/material
+  // keeps a texture. Textures-off collapses every face to the themed wall role
+  // (the guaranteed escape hatch). The edge/cap slot (index 0) stays role-based.
   const visible: WallMaterialArray = textures
     ? [
         wallRoleMaterial,
         hasExplicitMaterial(interiorSpec)
           ? getSurfaceVisibleMaterial(interiorSpec, shading)
-          : wallRoleMaterial,
+          : resolveWallSlotDefault(WALL_SLOT_DEFAULT.interior, shading),
         hasExplicitMaterial(exteriorSpec)
           ? getSurfaceVisibleMaterial(exteriorSpec, shading)
-          : wallRoleMaterial,
+          : resolveWallSlotDefault(WALL_SLOT_DEFAULT.exterior, shading),
       ]
     : [wallRoleMaterial, wallRoleMaterial, wallRoleMaterial]
 
diff --git a/packages/viewer/src/systems/window/window-system.tsx b/packages/viewer/src/systems/window/window-system.tsx
index 6f953877e..57c938924 100644
--- a/packages/viewer/src/systems/window/window-system.tsx
+++ b/packages/viewer/src/systems/window/window-system.tsx
@@ -1,6 +1,8 @@
 import {
   type AnyNodeId,
   getEffectiveNode,
+  type SceneMaterial,
+  type SceneMaterialId,
   sceneRegistry,
   useInteractive,
   useLiveNodeOverrides,
@@ -10,10 +12,14 @@ import {
 import { useFrame } from '@react-three/fiber'
 import { useEffect, useRef } from 'react'
 import * as THREE from 'three'
+import { applyWorldScaleBoxUVs } from '../../lib/box-uv'
 import {
+  type ColorPreset,
   createSurfaceRoleMaterial,
   glassMaterial as defaultGlassMaterial,
   baseMaterial as getBaseMaterial,
+  type RenderShading,
+  resolveMaterialRef,
 } from '../../lib/materials'
 import useViewer from '../../store/use-viewer'
 
@@ -21,6 +27,13 @@ import useViewer from '../../store/use-viewer'
 const hitboxMaterial = new THREE.MeshBasicMaterial({ visible: false })
 let baseMaterial = getBaseMaterial()
 let glassMaterial: THREE.Material = defaultGlassMaterial
+let currentWindowSlot: string | undefined
+// Per-frame viewer state, captured so the per-node mesh builder (which runs
+// outside React) can resolve each window's slot materials.
+let currentShading: RenderShading = 'rendered'
+let currentTextures = true
+let currentColorPreset: ColorPreset = 'clay'
+let currentSceneMaterials: Record<SceneMaterialId, SceneMaterial> | undefined
 export const CASEMENT_WINDOW_SASH_NAME = 'casement-window-sash'
 export const FRENCH_CASEMENT_LEFT_SASH_NAME = 'french-casement-left-sash'
 export const FRENCH_CASEMENT_RIGHT_SASH_NAME = 'french-casement-right-sash'
@@ -42,6 +55,7 @@ export const WindowSystem = () => {
   const shading = useViewer((state) => state.shading)
   const textures = useViewer((state) => state.textures)
   const colorPreset = useViewer((state) => state.colorPreset)
+  const sceneMaterials = useScene((state) => state.materials)
   const materialRevisionRef = useRef<string | null>(null)
   // Subscribe so override-only updates re-run this component. Mirrors
   // WallSystem + DoorSystem.
@@ -67,6 +81,18 @@ export const WindowSystem = () => {
     }
   })
 
+  // Editing a scene material a window slot references must rebuild that window
+  // (window meshes are built by this system, not <GeometrySystem>, so its
+  // scene-material re-dirty doesn't cover them).
+  useEffect(() => {
+    const nodes = useScene.getState().nodes
+    for (const node of Object.values(nodes)) {
+      if (node?.type !== 'window') continue
+      if (!nodeReferencesSceneMaterial(node)) continue
+      useScene.getState().dirtyNodes.add(node.id as AnyNodeId)
+    }
+  }, [sceneMaterials])
+
   useFrame(() => {
     if (dirtyNodes.size === 0) return
     baseMaterial = textures
@@ -75,6 +101,10 @@ export const WindowSystem = () => {
     glassMaterial = textures
       ? defaultGlassMaterial
       : createSurfaceRoleMaterial('glazing', colorPreset)
+    currentShading = shading
+    currentTextures = textures
+    currentColorPreset = colorPreset
+    currentSceneMaterials = sceneMaterials
 
     const nodes = useScene.getState().nodes
     const dirtyWindowIds: AnyNodeId[] = []
@@ -128,6 +158,52 @@ export const WindowSystem = () => {
   return null
 }
 
+function tagWindowSlot(mesh: THREE.Mesh): THREE.Mesh {
+  mesh.userData.slotId = currentWindowSlot
+  return mesh
+}
+
+function nodeReferencesSceneMaterial(node: { slots?: Record<string, string> }): boolean {
+  const slots = node.slots
+  if (!slots) return false
+  for (const ref of Object.values(slots)) {
+    if (typeof ref === 'string' && ref.startsWith('scene:')) return true
+  }
+  return false
+}
+
+// Window frame/glass default to catalog finishes (generic approach). `preset-glass`
+// is now FrontSide (it was the only glass we use), so it's safe for the WebGPU
+// MRT scene pass.
+const FRAME_DEFAULT_REF = 'library:preset-softwhite'
+const GLASS_DEFAULT_REF = 'library:preset-glass'
+
+function windowSlotDefault(slotId: 'frame' | 'glass'): THREE.Material {
+  if (slotId === 'glass') {
+    if (!currentTextures) return createSurfaceRoleMaterial('glazing', currentColorPreset)
+    return (
+      resolveMaterialRef(GLASS_DEFAULT_REF, currentSceneMaterials, currentShading) ??
+      defaultGlassMaterial
+    )
+  }
+  if (!currentTextures) return createSurfaceRoleMaterial('joinery', currentColorPreset)
+  return (
+    resolveMaterialRef(FRAME_DEFAULT_REF, currentSceneMaterials, currentShading) ??
+    getBaseMaterial(currentShading)
+  )
+}
+
+// Resolve a window's slot to a material: the `node.slots` override (colored mode
+// only) → the role/base default. Textures-off ignores overrides — the monochrome
+// escape hatch.
+function resolveWindowSlotMaterial(node: WindowNode, slotId: 'frame' | 'glass'): THREE.Material {
+  const fallback = windowSlotDefault(slotId)
+  if (!currentTextures) return fallback
+  const ref = node.slots?.[slotId]
+  if (!ref) return fallback
+  return resolveMaterialRef(ref, currentSceneMaterials, currentShading) ?? fallback
+}
+
 function addBox(
   parent: THREE.Object3D,
   material: THREE.Material,
@@ -138,8 +214,11 @@ function addBox(
   y: number,
   z: number,
 ) {
-  const m = new THREE.Mesh(new THREE.BoxGeometry(w, h, d), material)
+  const geometry = new THREE.BoxGeometry(w, h, d)
+  applyWorldScaleBoxUVs(geometry, w, h, d)
+  const m = new THREE.Mesh(geometry, material)
   m.position.set(x, y, z)
+  tagWindowSlot(m)
   parent.add(m)
 }
 
@@ -157,6 +236,7 @@ function addShape(
   })
   geometry.translate(0, 0, -depth / 2 + z)
   const mesh = new THREE.Mesh(geometry, material)
+  tagWindowSlot(mesh)
   parent.add(mesh)
 }
 
@@ -493,6 +573,7 @@ function addRoundedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = innerTop - innerBottom
   const innerRadii = insetCornerRadii(outerRadii, inset, innerW, innerH)
 
+  currentWindowSlot = 'frame'
   addShape(
     mesh,
     baseMaterial,
@@ -502,6 +583,7 @@ function addRoundedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
 
   if (innerW > 0.01 && innerH > 0.01) {
     const glassDepth = Math.max(0.004, frameDepth * 0.08)
+    currentWindowSlot = 'glass'
     addShape(
       mesh,
       glassMaterial,
@@ -519,6 +601,7 @@ function addRoundedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     const rowHeights = rowRatios.map((r) => (r / rowSum) * usableH)
 
     let x = innerLeft
+    currentWindowSlot = 'frame'
     for (let c = 0; c < numCols - 1; c++) {
       x += colWidths[c]!
       const x1 = x
@@ -539,6 +622,7 @@ function addRoundedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     }
 
     let y = innerTop
+    currentWindowSlot = 'frame'
     for (let r = 0; r < numRows - 1; r++) {
       y -= rowHeights[r]!
       const yTop = y
@@ -565,6 +649,7 @@ function addRoundedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -606,10 +691,12 @@ function addArchedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerArchHeight = getClampedArchHeight(innerW, innerH, archHeight - inset)
   const innerSpringY = innerTop - innerArchHeight
 
+  currentWindowSlot = 'frame'
   addShape(mesh, baseMaterial, createArchedFrameShape(width, height, archHeight, inset), frameDepth)
 
   if (innerW > 0.01 && innerH > 0.01) {
     const glassDepth = Math.max(0.004, frameDepth * 0.08)
+    currentWindowSlot = 'glass'
     addShape(
       mesh,
       glassMaterial,
@@ -628,6 +715,7 @@ function addArchedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     const innerHalfWidth = innerW / 2
 
     let x = innerLeft
+    currentWindowSlot = 'frame'
     for (let c = 0; c < numCols - 1; c++) {
       x += colWidths[c]!
       const x1 = x
@@ -648,6 +736,7 @@ function addArchedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     }
 
     let y = innerTop
+    currentWindowSlot = 'frame'
     for (let r = 0; r < numRows - 1; r++) {
       y -= rowHeights[r]!
       const yTop = y
@@ -675,6 +764,7 @@ function addArchedWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -714,6 +804,7 @@ function addSlidingWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   // Outer frame.
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -776,6 +867,7 @@ function addSlidingWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     mesh.add(activePanel)
 
     // Twin tracks signal the sliding operation without adding editor-only state.
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -797,10 +889,12 @@ function addSlidingWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       0,
     )
 
+    currentWindowSlot = 'glass'
     addBox(activePanel, glassMaterial, panelWidth, panelH, glassDepth, 0, 0, 0)
     addBox(mesh, glassMaterial, panelWidth, panelH, glassDepth, rightPanelX, 0, rightZ)
 
     // The right sash stays fixed. The left sash is the active panel that slides across it.
+    currentWindowSlot = 'frame'
     addBox(
       activePanel,
       baseMaterial,
@@ -846,6 +940,7 @@ function addSlidingWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -882,6 +977,7 @@ function addRectCasementSash(
   sash.rotation.y = rotationY
   parent.add(sash)
 
+  currentWindowSlot = 'frame'
   addBox(
     sash,
     baseMaterial,
@@ -922,6 +1018,7 @@ function addRectCasementSash(
     0,
     0,
   )
+  currentWindowSlot = 'glass'
   addBox(sash, glassMaterial, glassW, glassH, glassDepth, sashCenterX, 0, sashDepth * 0.08)
 }
 
@@ -934,6 +1031,7 @@ function addFrenchCasementHingeMarkers(
 ) {
   const markerW = Math.max(frameThickness * 0.38, 0.018)
   const markerH = innerH * 0.24
+  currentWindowSlot = 'frame'
   for (const pivotX of [-innerW / 2, innerW / 2]) {
     addBox(
       mesh,
@@ -1112,6 +1210,7 @@ function addShapedFrenchCasementSash(
     const outerArchHeight = getClampedArchHeight(node.width, node.height, node.archHeight)
     const sashArchHeight = getClampedArchHeight(fullW, leafH, outerArchHeight - frameThickness)
     const sashSpringY = node.height / 2 - outerArchHeight
+    currentWindowSlot = 'frame'
     addShape(
       sashVisual,
       baseMaterial,
@@ -1128,6 +1227,7 @@ function addShapedFrenchCasementSash(
     )
     const glassInset = Math.min(sashFrameThickness, leafW / 2 - 0.005, leafH / 2 - 0.005)
     if (glassInset > 0.001) {
+      currentWindowSlot = 'glass'
       addShape(
         sashVisual,
         glassMaterial,
@@ -1153,6 +1253,7 @@ function addShapedFrenchCasementSash(
     fullW,
     leafH,
   )
+  currentWindowSlot = 'frame'
   addShape(
     sashVisual,
     baseMaterial,
@@ -1161,6 +1262,7 @@ function addShapedFrenchCasementSash(
   )
   const glassInset = Math.min(sashFrameThickness, leafW / 2 - 0.005, leafH / 2 - 0.005)
   if (glassInset > 0.001) {
+    currentWindowSlot = 'glass'
     addShape(
       sashVisual,
       glassMaterial,
@@ -1177,6 +1279,7 @@ function addFrenchCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   // Fixed outer frame.
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -1249,6 +1352,7 @@ function addFrenchCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1268,6 +1372,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   if (node.openingShape === 'arch') {
+    currentWindowSlot = 'frame'
     addShape(
       mesh,
       baseMaterial,
@@ -1280,6 +1385,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       frameDepth,
     )
   } else {
+    currentWindowSlot = 'frame'
     addShape(
       mesh,
       baseMaterial,
@@ -1331,6 +1437,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     if (sill) {
       const sillW = width + sillDepth * 0.4
       const sillZ = frameDepth / 2 + sillDepth / 2
+      currentWindowSlot = 'frame'
       addBox(
         mesh,
         baseMaterial,
@@ -1371,6 +1478,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
         innerH,
         (node.archHeight ?? innerW / 2) - frameThickness,
       )
+      currentWindowSlot = 'frame'
       addShape(
         sashVisual,
         baseMaterial,
@@ -1381,6 +1489,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       if (glassInset > 0.001) {
         const glassW = innerW - 2 * glassInset
         const glassH = innerH - 2 * glassInset
+        currentWindowSlot = 'glass'
         addShape(
           sashVisual,
           glassMaterial,
@@ -1397,6 +1506,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       }
     } else {
       const outerRadii = getWindowRoundedRadii(node, innerW, innerH)
+      currentWindowSlot = 'frame'
       addShape(
         sashVisual,
         baseMaterial,
@@ -1407,6 +1517,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       if (glassInset > 0.001) {
         const glassW = innerW - 2 * glassInset
         const glassH = innerH - 2 * glassInset
+        currentWindowSlot = 'glass'
         addShape(
           sashVisual,
           glassMaterial,
@@ -1423,6 +1534,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       }
     }
 
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1448,6 +1560,7 @@ function addShapedCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1478,6 +1591,7 @@ function addCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   // Fixed outer frame.
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -1538,6 +1652,7 @@ function addCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     sash.rotation.y = hingeSign * openAngle
     mesh.add(sash)
 
+    currentWindowSlot = 'frame'
     addBox(
       sash,
       baseMaterial,
@@ -1578,9 +1693,11 @@ function addCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       0,
       0,
     )
+    currentWindowSlot = 'glass'
     addBox(sash, glassMaterial, glassW, glassH, glassDepth, sashCenterX, 0, sashDepth * 0.08)
 
     // Small hinge markers make the pivot side legible when the sash is closed.
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1606,6 +1723,7 @@ function addCasementWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1631,6 +1749,7 @@ function addAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   // Fixed outer frame.
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -1690,6 +1809,7 @@ function addAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     sash.rotation.x = -openAngle
     mesh.add(sash)
 
+    currentWindowSlot = 'frame'
     addBox(
       sash,
       baseMaterial,
@@ -1730,9 +1850,11 @@ function addAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       sashCenterY,
       0,
     )
+    currentWindowSlot = 'glass'
     addBox(sash, glassMaterial, glassW, glassH, glassDepth, 0, sashCenterY, sashDepth * 0.08)
 
     // Compact hinge rail, visible even when the sash is closed.
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1748,6 +1870,7 @@ function addAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1767,6 +1890,7 @@ function addShapedAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   if (node.openingShape === 'arch') {
+    currentWindowSlot = 'frame'
     addShape(
       mesh,
       baseMaterial,
@@ -1779,6 +1903,7 @@ function addShapedAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       frameDepth,
     )
   } else {
+    currentWindowSlot = 'frame'
     addShape(
       mesh,
       baseMaterial,
@@ -1816,6 +1941,7 @@ function addShapedAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
         innerH,
         (node.archHeight ?? innerW / 2) - frameThickness,
       )
+      currentWindowSlot = 'frame'
       addShape(
         sashVisual,
         baseMaterial,
@@ -1826,6 +1952,7 @@ function addShapedAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       if (glassInset > 0.001) {
         const glassW = innerW - 2 * glassInset
         const glassH = innerH - 2 * glassInset
+        currentWindowSlot = 'glass'
         addShape(
           sashVisual,
           glassMaterial,
@@ -1842,6 +1969,7 @@ function addShapedAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       }
     } else {
       const outerRadii = getWindowRoundedRadii(node, innerW, innerH)
+      currentWindowSlot = 'frame'
       addShape(
         sashVisual,
         baseMaterial,
@@ -1852,6 +1980,7 @@ function addShapedAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       if (glassInset > 0.001) {
         const glassW = innerW - 2 * glassInset
         const glassH = innerH - 2 * glassInset
+        currentWindowSlot = 'glass'
         addShape(
           sashVisual,
           glassMaterial,
@@ -1868,6 +1997,7 @@ function addShapedAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       }
     }
 
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1883,6 +2013,7 @@ function addShapedAwningWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -1908,6 +2039,7 @@ function addHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   // Fixed outer frame.
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -1965,6 +2097,7 @@ function addHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     sash.rotation.x = -openAngle
     mesh.add(sash)
 
+    currentWindowSlot = 'frame'
     addBox(
       sash,
       baseMaterial,
@@ -1996,9 +2129,11 @@ function addHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       innerH / 2,
       0,
     )
+    currentWindowSlot = 'glass'
     addBox(sash, glassMaterial, glassW, glassH, glassDepth, 0, innerH / 2, sashDepth * 0.08)
 
     // Compact bottom hinge rail, visible even when the sash is closed.
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2014,6 +2149,7 @@ function addHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2033,6 +2169,7 @@ function addShapedHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   if (node.openingShape === 'arch') {
+    currentWindowSlot = 'frame'
     addShape(
       mesh,
       baseMaterial,
@@ -2045,6 +2182,7 @@ function addShapedHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       frameDepth,
     )
   } else {
+    currentWindowSlot = 'frame'
     addShape(
       mesh,
       baseMaterial,
@@ -2081,6 +2219,7 @@ function addShapedHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
         innerH,
         (node.archHeight ?? innerW / 2) - frameThickness,
       )
+      currentWindowSlot = 'frame'
       addShape(
         sashVisual,
         baseMaterial,
@@ -2091,6 +2230,7 @@ function addShapedHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       if (glassInset > 0.001) {
         const glassW = innerW - 2 * glassInset
         const glassH = innerH - 2 * glassInset
+        currentWindowSlot = 'glass'
         addShape(
           sashVisual,
           glassMaterial,
@@ -2107,6 +2247,7 @@ function addShapedHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       }
     } else {
       const outerRadii = getWindowRoundedRadii(node, innerW, innerH)
+      currentWindowSlot = 'frame'
       addShape(
         sashVisual,
         baseMaterial,
@@ -2117,6 +2258,7 @@ function addShapedHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       if (glassInset > 0.001) {
         const glassW = innerW - 2 * glassInset
         const glassH = innerH - 2 * glassInset
+        currentWindowSlot = 'glass'
         addShape(
           sashVisual,
           glassMaterial,
@@ -2133,6 +2275,7 @@ function addShapedHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       }
     }
 
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2148,6 +2291,7 @@ function addShapedHopperWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2171,6 +2315,7 @@ function addHungSash(
   glassW: number,
   glassH: number,
 ) {
+  currentWindowSlot = 'frame'
   addBox(
     parent,
     baseMaterial,
@@ -2211,6 +2356,7 @@ function addHungSash(
     0,
     0,
   )
+  currentWindowSlot = 'glass'
   addBox(parent, glassMaterial, glassW, glassH, glassDepth, 0, 0, 0)
 }
 
@@ -2221,6 +2367,7 @@ function addSingleHungWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   // Fixed outer frame.
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -2285,6 +2432,7 @@ function addSingleHungWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     mesh.add(activeSash)
 
     // Side tracks show the lower sash is the moving element.
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2331,6 +2479,7 @@ function addSingleHungWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     )
 
     // Meeting rails: top sash fixed, bottom sash moves upward over it.
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2356,6 +2505,7 @@ function addSingleHungWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2376,6 +2526,7 @@ function addDoubleHungWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = height - 2 * frameThickness
 
   // Fixed outer frame.
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -2444,6 +2595,7 @@ function addDoubleHungWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     mesh.add(bottomSash)
 
     // Side tracks show both sashes move vertically.
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2487,6 +2639,7 @@ function addDoubleHungWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     )
 
     // Opposing meeting rails: top sash descends while bottom sash rises.
+    currentWindowSlot = 'frame'
     addBox(
       topSash,
       baseMaterial,
@@ -2512,6 +2665,7 @@ function addDoubleHungWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2530,6 +2684,7 @@ function addBayWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerW = width - 2 * frameThickness
   const innerH = height - 2 * frameThickness
 
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -2590,6 +2745,7 @@ function addBayWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     const addBayPanel = (parent: THREE.Object3D, panelW: number) => {
       const glassW = Math.max(panelW - 2 * sashFrameThickness, 0.01)
       const glassH = Math.max(innerH - 2 * sashFrameThickness, 0.01)
+      currentWindowSlot = 'frame'
       addBox(
         parent,
         baseMaterial,
@@ -2630,10 +2786,12 @@ function addBayWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
         0,
         0,
       )
+      currentWindowSlot = 'glass'
       addBox(parent, glassMaterial, glassW, glassH, glassDepth, 0, 0, panelDepth * 0.08)
     }
 
     const addBayCap = (centerY: number) => {
+      currentWindowSlot = 'frame'
       const halfThickness = frameThickness / 2
       const vertices: number[] = []
       const indices: number[] = []
@@ -2688,7 +2846,7 @@ function addBayWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       geometry.setAttribute('position', new THREE.Float32BufferAttribute(vertices, 3))
       geometry.setIndex(indices)
       geometry.computeVertexNormals()
-      mesh.add(new THREE.Mesh(geometry, baseMaterial))
+      mesh.add(tagWindowSlot(new THREE.Mesh(geometry, baseMaterial)))
     }
 
     const center = new THREE.Group()
@@ -2715,6 +2873,7 @@ function addBayWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2733,6 +2892,7 @@ function addBowWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerW = width - 2 * frameThickness
   const innerH = height - 2 * frameThickness
 
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -2859,15 +3019,19 @@ function addBowWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     }
 
     const addCurvedMesh = (material: THREE.Material, geometry: THREE.BufferGeometry) => {
-      mesh.add(new THREE.Mesh(geometry, material))
+      mesh.add(tagWindowSlot(new THREE.Mesh(geometry, material)))
     }
 
+    currentWindowSlot = 'frame'
     addCurvedMesh(baseMaterial, createCurvedVerticalBand(glassTop, innerH / 2))
     addCurvedMesh(baseMaterial, createCurvedVerticalBand(-innerH / 2, glassBottom))
+    currentWindowSlot = 'glass'
     addCurvedMesh(glassMaterial, createCurvedVerticalBand(glassBottom, glassTop, frameDepth * 0.04))
+    currentWindowSlot = 'frame'
     addCurvedMesh(baseMaterial, createCurvedCap(slabYTop, frameThickness))
     addCurvedMesh(baseMaterial, createCurvedCap(slabYBottom, frameThickness))
 
+    currentWindowSlot = 'frame'
     for (let index = 0; index <= mullionCount; index += 1) {
       const x = -halfSpan + (innerW * index) / mullionCount
       addBox(mesh, baseMaterial, sashFrameThickness, innerH, frameDepth * 0.72, x, 0, arcZAt(x))
@@ -2877,6 +3041,7 @@ function addBowWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2901,6 +3066,7 @@ function addLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerW = width - 2 * frameThickness
   const innerH = height - 2 * frameThickness
 
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -2955,6 +3121,7 @@ function addLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     slats.name = LOUVERED_WINDOW_SLATS_NAME
     mesh.add(slats)
 
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -2976,6 +3143,7 @@ function addLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       0,
     )
 
+    currentWindowSlot = 'glass'
     for (let index = 0; index < slatCount; index += 1) {
       const y = innerH / 2 - slatGap * (index + 0.5)
       const slat = new THREE.Group()
@@ -2998,6 +3166,7 @@ function addLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -3025,6 +3194,7 @@ function addShapedLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   const innerH = innerTop - innerBottom
 
   if (node.openingShape === 'arch') {
+    currentWindowSlot = 'frame'
     addShape(
       mesh,
       baseMaterial,
@@ -3037,6 +3207,7 @@ function addShapedLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
       frameDepth,
     )
   } else {
+    currentWindowSlot = 'frame'
     addShape(
       mesh,
       baseMaterial,
@@ -3087,6 +3258,7 @@ function addShapedLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
           })()
 
     const addVerticalRail = (x: number) => {
+      currentWindowSlot = 'frame'
       const railX1 = x
       const railX2 = x + (x < 0 ? railThickness : -railThickness)
       const sampleX = x < 0 ? Math.max(railX1, railX2) : Math.min(railX1, railX2)
@@ -3120,6 +3292,7 @@ function addShapedLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
     addVerticalRail(innerLeft)
     addVerticalRail(innerRight)
 
+    currentWindowSlot = 'glass'
     for (let index = 0; index < slatCount; index += 1) {
       const y = innerTop - slatGap * (index + 0.5)
       const topBounds = getBoundsAtY(Math.min(y + slatHeight / 2, innerTop))
@@ -3140,6 +3313,7 @@ function addShapedLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
   if (sill) {
     const sillW = width + sillDepth * 0.4
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -3154,6 +3328,8 @@ function addShapedLouveredWindowVisuals(node: WindowNode, mesh: THREE.Mesh) {
 }
 
 function updateWindowMesh(node: WindowNode, mesh: THREE.Mesh) {
+  currentWindowSlot = undefined
+
   // Root mesh is an invisible hitbox; all visuals live in child meshes
   mesh.geometry.dispose()
   mesh.geometry = new THREE.BoxGeometry(node.width, node.height, node.frameDepth)
@@ -3170,6 +3346,12 @@ function updateWindowMesh(node: WindowNode, mesh: THREE.Mesh) {
     mesh.remove(child)
   }
 
+  // Point the builder-facing frame/glass materials at this window's slot
+  // overrides for the duration of its build (recomputed per node, so the next
+  // window resets cleanly without a restore).
+  baseMaterial = resolveWindowSlotMaterial(node, 'frame')
+  glassMaterial = resolveWindowSlotMaterial(node, 'glass')
+
   const {
     width,
     height,
@@ -3263,6 +3445,7 @@ function updateWindowMesh(node: WindowNode, mesh: THREE.Mesh) {
 
   // ── Frame members ──
   // Top / bottom — full width
+  currentWindowSlot = 'frame'
   addBox(
     mesh,
     baseMaterial,
@@ -3337,6 +3520,7 @@ function updateWindowMesh(node: WindowNode, mesh: THREE.Mesh) {
 
   // Column dividers — full inner height
   cx = -innerW / 2
+  currentWindowSlot = 'frame'
   for (let c = 0; c < numCols - 1; c++) {
     cx += colWidths[c]!
     addBox(
@@ -3354,6 +3538,7 @@ function updateWindowMesh(node: WindowNode, mesh: THREE.Mesh) {
 
   // Row dividers — per column width, so they don't overlap column dividers (top to bottom)
   cy = innerH / 2
+  currentWindowSlot = 'frame'
   for (let r = 0; r < numRows - 1; r++) {
     cy -= rowHeights[r]!
     const divY = cy - rowDividerThickness / 2
@@ -3374,6 +3559,7 @@ function updateWindowMesh(node: WindowNode, mesh: THREE.Mesh) {
 
   // Glass panes
   const glassDepth = Math.max(0.004, frameDepth * 0.08)
+  currentWindowSlot = 'glass'
   for (let c = 0; c < numCols; c++) {
     for (let r = 0; r < numRows; r++) {
       addBox(
@@ -3394,6 +3580,7 @@ function updateWindowMesh(node: WindowNode, mesh: THREE.Mesh) {
     const sillW = width + sillDepth * 0.4 // slightly wider than frame
     // Protrudes from the front face of the frame (+Z)
     const sillZ = frameDepth / 2 + sillDepth / 2
+    currentWindowSlot = 'frame'
     addBox(
       mesh,
       baseMaterial,
@@ -3415,6 +3602,10 @@ function syncWindowCutout(node: WindowNode, mesh: THREE.Mesh) {
   if (!cutout) {
     cutout = new THREE.Mesh()
     cutout.name = 'cutout'
+    // The cutout (a 1m-deep CSG helper, invisible) is proud of the wall, so it
+    // wins the scene raycast over the wall in front of the recessed window —
+    // making it the selection AND paint hit target for the whole opening. The
+    // paint capability then re-raycasts the window's parts to find the slot.
     mesh.add(cutout)
   }
   cutout.geometry.dispose()