feat(paint-slots): concrete-plate finish + try defaults (wall=concrete, slab=wood plank 48, ceiling=soft white)

- material-library: add 'concrete-plate' KTX2 finish (512, fabric/leather-style
  pipeline) + editor-app texture mirror.
- viewer: shared resolveSlotDefaultMaterial(colour|library ref) so a kind's slot
  default can be a catalog finish, not just a flat colour.
- wall default -> library:concrete-plate (interior + exterior).
- slab default -> library:wood-woodplank48 (slab geometry resolves it via the
  shared helper).
- ceiling default -> soft white #f2eee6 (ceiling renders flat-tinted).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/core/src/material-library.ts

@@ -3860,6 +3860,44 @@ 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',

packages/core/src/schema/nodes/wall.ts

@@ -52,8 +52,8 @@ export type WallSurfaceSide = 'interior' | 'exterior'
 // 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: '#ffffff',
-  exterior: '#ffffff',
+  interior: 'library:concrete-plate',
+  exterior: 'library:concrete-plate',
 }
 
 export type WallSurfaceMaterialSpec = {

packages/nodes/src/ceiling/slots.ts

@@ -2,8 +2,9 @@ import type { SlotDeclaration } from '@pascal-app/core'
 
 export type CeilingSlotId = 'surface'
 
-// Visual parity with the retired DEFAULT_CEILING_MATERIAL (warm beige).
-export const CEILING_SLOT_DEFAULT_COLOR = '#f5f5dc'
+// 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[] {

packages/nodes/src/slab/geometry.ts

@@ -8,9 +8,10 @@ import {
   generateSlabGeometry,
   type RenderShading,
   resolveMaterialRef,
+  resolveSlotDefaultMaterial,
 } from '@pascal-app/viewer'
 import { FrontSide, Group, type Material, Mesh, type Texture } from 'three'
-import { SLAB_SLOT_DEFAULT_COLOR } from './slots'
+import { SLAB_SLOT_DEFAULT } from './slots'
 
 /**
  * Stage B builder for slab. Reuses `generateSlabGeometry` (pure
@@ -62,8 +63,8 @@ function getSlabMaterial(
     return getLegacySlabMaterial(node, shading)
   }
 
-  // Declared slot default (visual parity with the retired DEFAULT_SLAB_MATERIAL).
-  return createDefaultMaterial(SLAB_SLOT_DEFAULT_COLOR, 0.8, 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 {
@@ -83,7 +84,7 @@ function getLegacySlabMaterial(node: SlabNode, shading: RenderShading): Material
     ? createDefaultMaterial('#ffffff', 0.5, shading)
     : node.material
       ? createMaterial(node.material, shading).clone()
-      : createDefaultMaterial(SLAB_SLOT_DEFAULT_COLOR, 0.8, shading)
+      : createDefaultMaterial('#e5e5e5', 0.8, shading)
 
   if (preset) {
     applyMaterialPresetToMaterials(material, preset)

packages/nodes/src/slab/slots.ts

@@ -2,10 +2,12 @@ import type { SlotDeclaration } from '@pascal-app/core'
 
 export type SlabSlotId = 'surface'
 
-// Visual parity with the retired DEFAULT_SLAB_MATERIAL (light grey).
-export const SLAB_SLOT_DEFAULT_COLOR = '#e5e5e5'
+// 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_COLOR }]
+  return [{ slotId: 'surface', label: 'Surface', default: SLAB_SLOT_DEFAULT }]
 }

packages/viewer/src/index.ts

@@ -69,6 +69,7 @@ export {
   PRESET_PALETTES,
   type RenderShading,
   resolveMaterialRef,
+  resolveSlotDefaultMaterial,
   resolveSurfaceColor,
   WHITE_PALETTE,
 } from './lib/materials'

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,