refactor(paint-slots): paint panel — three fixed bands, scroll only the grid

Layout is now: fixed eraser/reset + category tabs (no longer sticky-inside-
scroll), a single scrolling catalog grid, and an always-visible scene-material
footer. The custom-material "+" moved out of the colors-only grid cell onto the
scene-material section header, so a custom material can be added from any
category (creates a blank scene material, selects it as the brush, opens its
inline editor).

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

packages/editor/src/components/ui/controls/material-paint-panel.tsx

@@ -8,7 +8,7 @@ import {
   useScene,
 } from '@pascal-app/core'
 import { useViewer } from '@pascal-app/viewer'
-import { Eraser, RotateCcw } from 'lucide-react'
+import { Eraser, Plus, RotateCcw } from 'lucide-react'
 import { useEffect, useState } from 'react'
 import {
   buildResetSurfaceMaterialUpdates,
@@ -16,15 +16,16 @@ import {
 } from './../../../lib/material-paint'
 import useEditor from './../../../store/use-editor'
 import { Button } from '../primitives/button'
+import { Tooltip, TooltipContent, TooltipTrigger } from '../primitives/tooltip'
 import { MaterialPicker } from './material-picker'
-import { PanelSection } from './panel-section'
 import { SceneMaterialList } from './scene-material-list'
 
 /**
  * Material picker for paint mode. Embedders render this wherever paint controls
  * belong (the community editor places it in the Build sidebar while paint mode
- * is active). It owns the paint-target/material wiring so the host only needs
+ * is active). It fills its container's height and lays out as three bands: a
- * to mount it; it fills its container's width.
+ * fixed control/category header, a single scrolling catalog grid, and a fixed
+ * scene-material footer (always visible, with a `+` to add a custom material).
  */
 export function MaterialPaintPanel() {
   const activePaintMaterial = useEditor((state) => state.activePaintMaterial)
@@ -55,11 +56,33 @@ export function MaterialPaintPanel() {
     useScene.getState().updateNodes(buildResetSurfaceMaterialUpdates(nodes, selectedNode))
   }
 
+  // Create a blank custom scene material, select it as the brush (`scene:` ref so
+  // edits propagate), and open its inline editor. Available from any category.
+  const createCustomMaterial = () => {
+    const id = generateSceneMaterialId()
+    const count = Object.keys(useScene.getState().materials).length
+    useScene.getState().addSceneMaterial({
+      id,
+      name: `Material ${count + 1}`,
+      material: {
+        preset: 'custom',
+        properties: {
+          color: '#ffffff',
+          roughness: 0.5,
+          metalness: 0,
+          opacity: 1,
+          transparent: false,
+          side: 'front',
+        },
+      },
+    })
+    setActivePaintMaterial({ materialPreset: toSceneMaterialRef(id), sourceTarget: activePaintTarget })
+    setAutoEditMaterialId(id)
+  }
+
   return (
-    // Fill the host's scroll slot and own the scroll internally: the eraser /
-    // reset row stays pinned (shrink-0) while only the material list below
-    // scrolls. The category tabs pin too (sticky, inside the scroll region).
     <div className="flex h-full min-h-0 w-full flex-col">
+      {/* Fixed: eraser / reset. */}
       <div className="flex shrink-0 items-center gap-2 pb-2">
         <Button
           aria-pressed={paintEraser}
@@ -82,33 +105,47 @@ export function MaterialPaintPanel() {
           Reset all
         </Button>
       </div>
-      <div className="subtle-scrollbar min-h-0 flex-1 space-y-2 overflow-y-auto">
+
+      {/* Scrolls: category tabs (fixed inside) + catalog grid (the scroll). */}
+      <div className="min-h-0 flex-1">
         <MaterialPicker
-          onChange={(material) => {
-            // Custom-create: pre-create a scene material and select it as the
-            // brush via a `scene:` ref so painting stores the ref and edits to
-            // it propagate everywhere. The user edits it inline in the scene-
-            // material list below (auto-opened) — no separate right-side pane.
-            const id = generateSceneMaterialId()
-            const count = Object.keys(useScene.getState().materials).length
-            useScene.getState().addSceneMaterial({ id, name: `Material ${count + 1}`, material })
-            setActivePaintMaterial({
-              materialPreset: toSceneMaterialRef(id),
-              sourceTarget: activePaintTarget,
-            })
-            setAutoEditMaterialId(id)
-          }}
           onSelectMaterialPreset={(materialPreset) => {
             setActivePaintMaterial({ materialPreset, sourceTarget: activePaintTarget })
           }}
           selectedMaterialPreset={activePaintMaterial?.materialPreset}
-          value={activePaintMaterial?.material}
         />
+      </div>
+
+      {/* Fixed footer: scene materials, always visible, with a `+` to add one. */}
+      <div className="mt-2 shrink-0 space-y-1.5 border-border/60 border-t pt-2">
+        <div className="flex items-center justify-between">
+          <span className="font-medium text-muted-foreground text-xs uppercase tracking-[0.12em]">
+            Scene materials
+          </span>
+          <Tooltip>
+            <TooltipTrigger asChild>
+              <Button
+                aria-label="Add material"
+                onClick={createCustomMaterial}
+                size="icon-sm"
+                type="button"
+                variant="outline"
+              >
+                <Plus />
+              </Button>
+            </TooltipTrigger>
+            <TooltipContent>Add material</TooltipContent>
+          </Tooltip>
+        </div>
+        <div className="subtle-scrollbar max-h-56 overflow-y-auto">
           {materialCount > 0 ? (
-          <PanelSection title="Scene materials">
             <SceneMaterialList autoEditId={autoEditMaterialId} />
-          </PanelSection>
+          ) : (
-        ) : null}
+            <p className="px-0.5 py-1 text-muted-foreground text-xs">
+              No custom materials yet — add one with +.
+            </p>
+          )}
+        </div>
       </div>
     </div>
   )

packages/editor/src/components/ui/controls/material-picker.tsx

@@ -5,7 +5,6 @@ import {
   getLibraryMaterialIdFromRef,
   getMaterialsForCategory,
   MATERIAL_CATEGORIES,
-  type MaterialSchema,
   type MaterialTarget,
   toLibraryMaterialRef,
 } from '@pascal-app/core'
@@ -13,9 +12,7 @@ import { useEffect, useState } from 'react'
 import { triggerSFX } from '../../../lib/sfx-bus'
 
 type MaterialPickerProps = {
-  value?: MaterialSchema
   selectedMaterialPreset?: string
-  onChange?: (material: MaterialSchema) => void
   onSelectMaterialPreset?: (materialPreset: string) => void
   disabled?: boolean
   nodeType?: MaterialTarget
@@ -26,14 +23,16 @@ function getCategoryLabel(category: (typeof MATERIAL_CATEGORIES)[number]) {
   return category.charAt(0).toUpperCase() + category.slice(1)
 }
 
+/**
+ * Catalog material picker: a fixed row of category tabs over a scrollable grid
+ * of swatches. Custom-material creation lives in the scene-material section
+ * (the host's `+` action), not here, so it's available from any category.
+ */
 export function MaterialPicker({
-  value,
   selectedMaterialPreset,
-  onChange,
   onSelectMaterialPreset,
   disabled = false,
 }: MaterialPickerProps) {
-  const [showCustom, setShowCustom] = useState<boolean>(!!value?.properties)
   const [selectedCategory, setSelectedCategory] = useState<(typeof MATERIAL_CATEGORIES)[number]>(
     MATERIAL_CATEGORIES[0],
   )
@@ -42,61 +41,25 @@ export function MaterialPicker({
   )
   const catalogItems = getMaterialsForCategory(selectedCategory)
 
+  // Keep the visible category in sync with the externally-selected catalog
+  // material (a `scene:` ref matches no catalog entry, so the tab stays put).
   useEffect(() => {
-    setShowCustom(!!value?.properties && !selectedMaterialPreset)
+    const catalogId = getLibraryMaterialIdFromRef(selectedMaterialPreset) ?? undefined
-  }, [selectedMaterialPreset, value?.properties])
+    const entry = getCatalogMaterialById(catalogId)
-
+    if (entry?.category) setSelectedCategory(entry.category)
-  useEffect(() => {
+  }, [selectedMaterialPreset])
-    if (!selectedMaterialPreset && value?.properties) {
-      setSelectedCategory('colors')
-      return
-    }
-
-    const catalogId =
-      getLibraryMaterialIdFromRef(selectedMaterialPreset) ?? value?.id ?? undefined
-    const selectedCatalogEntry = getCatalogMaterialById(catalogId)
-    if (selectedCatalogEntry?.category) {
-      setSelectedCategory(selectedCatalogEntry.category)
-    }
-  }, [selectedMaterialPreset, value?.id])
-
-  const selectedCatalogId =
-    selectedMaterialPreset ?? (value?.id ? toLibraryMaterialRef(value.id) : undefined)
-  const selectedCatalogMaterialId = getLibraryMaterialIdFromRef(selectedCatalogId) ?? undefined
-  const selectedCatalogEntry = getCatalogMaterialById(selectedCatalogMaterialId)
 
   const handleCatalogSelect = (materialId: string) => {
     if (disabled) return
-    setShowCustom(false)
     onSelectMaterialPreset?.(toLibraryMaterialRef(materialId))
   }
 
-  // Seed a new custom material from the current/forked colour and hand it to
-  // the host (MaterialPaintPanel), which pre-creates a scene material the user
-  // edits inline in the build pane — no separate right-side editor pane.
-  const handleCustomOpen = () => {
-    if (disabled) return
-    const forkColor = selectedMaterialPreset
-      ? (selectedCatalogEntry?.previewColor ?? '#ffffff')
-      : '#ffffff'
-    onChange?.({
-      preset: 'custom',
-      properties: {
-        color: value?.properties?.color || forkColor,
-        roughness: value?.properties?.roughness ?? 0.5,
-        metalness: value?.properties?.metalness ?? 0,
-        opacity: value?.properties?.opacity ?? 1,
-        transparent: value?.properties?.transparent ?? false,
-        side: value?.properties?.side ?? 'front',
-      },
-    })
-  }
-
   return (
-    <div className={`min-w-0 space-y-3 ${disabled ? 'pointer-events-none opacity-50' : ''}`}>
+    <div
-      {(catalogItems.length > 0 || onChange) && (
+      className={`flex h-full min-h-0 flex-col gap-2 ${disabled ? 'pointer-events-none opacity-50' : ''}`}
-        <div className="min-w-0 space-y-1">
+    >
-          <div className="sticky top-0 z-10 flex flex-wrap gap-1 bg-sidebar pb-1">
+      {/* Fixed category tabs — outside the scroll region. */}
+      <div className="flex shrink-0 flex-wrap gap-1">
         {availableCategories.map((category) => (
           <button
             className={`rounded-full px-3 py-1 font-medium text-xs transition-colors ${
@@ -107,11 +70,10 @@ export function MaterialPicker({
             key={category}
             onClick={() => {
               setSelectedCategory(category)
-                  // Auto-select the first material in the category so the brush
+              // Auto-select the first material in the category so the brush is
-                  // is immediately ready (and the row shows as selected).
+              // immediately ready (and the swatch shows as selected).
               const first = getMaterialsForCategory(category)[0]
               if (first) handleCatalogSelect(first.id)
-                  else if (showCustom) setShowCustom(false)
             }}
             type="button"
           >
@@ -119,12 +81,13 @@ export function MaterialPicker({
           </button>
         ))}
       </div>
+      {/* The only scrolling region. */}
       <div
-            className="grid gap-2 pb-1"
+        className="subtle-scrollbar grid min-h-0 flex-1 auto-rows-min gap-2 overflow-y-auto pb-1"
         style={{ gridTemplateColumns: 'repeat(auto-fill, minmax(72px, 1fr))' }}
       >
         {catalogItems.map((item) => {
-              const isSelected = selectedCatalogId === toLibraryMaterialRef(item.id)
+          const isSelected = selectedMaterialPreset === toLibraryMaterialRef(item.id)
           return (
             <button
               className={`group relative flex flex-col gap-1.5 rounded-xl p-1.5 transition-colors hover:cursor-pointer hover:bg-sidebar-accent ${
@@ -158,29 +121,7 @@ export function MaterialPicker({
             </button>
           )
         })}
-            {selectedCategory === 'colors' && onChange ? (
-              <button
-                className={`group relative flex flex-col gap-1.5 rounded-xl p-1.5 transition-colors hover:cursor-pointer hover:bg-sidebar-accent ${
-                  showCustom ? 'bg-sidebar-accent ring-1 ring-primary ring-inset' : ''
-                }`}
-                onClick={() => {
-                  triggerSFX('sfx:menu-click')
-                  handleCustomOpen()
-                }}
-                onMouseEnter={() => triggerSFX('sfx:menu-hover')}
-                type="button"
-              >
-                <div className="flex aspect-square w-full items-center justify-center rounded-lg bg-muted text-lg text-muted-foreground group-hover:text-foreground">
-                  +
       </div>
-                <span className="truncate px-0.5 text-left font-medium text-[11px] text-muted-foreground group-hover:text-foreground">
-                  Custom
-                </span>
-              </button>
-            ) : null}
-          </div>
-        </div>
-      )}
     </div>
   )
 }