Show empty-canvas hint on a page with no components yet

.empty-canvas-hint existed in editor.css but was never rendered
anywhere. Wire it up in Canvas.tsx: an EmptyCanvasHint component reads
Craft's ROOT node via useEditor and shows the hint once ROOT exists
with zero children, hiding again the instant something is dropped in
or while a drag is in progress. It's absolutely positioned over the
Frame with pointer-events: none so it never intercepts clicks/drops
meant for the underlying (empty) canvas -- scoped to regular page
editing only, not the header/footer editing mode.

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

craft/src/editor/Canvas.tsx

@@ -1,5 +1,5 @@
 import React, { useMemo, useRef, useEffect } from 'react';
-import { Frame, Element } from '@craftjs/core';
+import { Frame, Element, useEditor } from '@craftjs/core';
 import { Container } from '../components/layout/Container';
 import { usePages } from '../state/PageContext';
 import { DeviceMode } from '../types';
@@ -93,6 +93,33 @@ const ZonePreview: React.FC<{ craftState: string | null; zone: 'header' | 'foote
   );
 };
 
+/**
+ * First-run hint shown over the canvas drop area once the current page's
+ * root node exists and has no children yet. Hidden the instant something
+ * is dropped in, and while a drag is in progress (so it never fights the
+ * drop-target UI). `pointer-events: none` (see .empty-canvas-hint in
+ * editor.css) keeps it from intercepting clicks/drops meant for the
+ * underlying empty canvas.
+ */
+export const EmptyCanvasHint: React.FC = () => {
+  const { isEmpty, isDragging } = useEditor((state) => {
+    const root = state.nodes['ROOT'];
+    return {
+      isEmpty: !!root && root.data.nodes.length === 0,
+      isDragging: state.events.dragged.size > 0,
+    };
+  });
+
+  if (!isEmpty || isDragging) return null;
+
+  return (
+    <div className="empty-canvas-hint">
+      <i className="fa fa-cubes" aria-hidden />
+      <span>Drag blocks from the left panel, or pick a Template to start.</span>
+    </div>
+  );
+};
+
 export const Canvas: React.FC<CanvasProps> = ({ device }) => {
   const width = DEVICE_WIDTHS[device];
   const { isEditingHeader, isEditingFooter, headerPage, footerPage } = usePages();
@@ -140,14 +167,17 @@ export const Canvas: React.FC<CanvasProps> = ({ device }) => {
           <ZonePreview craftState={headerPage.craftState} zone="header" />
         )}
 
-        <Frame>
-          <Element
-            is={Container}
-            canvas
-            tag={frameTag}
-            style={frameStyle}
-          />
-        </Frame>
+        <div style={{ position: 'relative' }}>
+          <Frame>
+            <Element
+              is={Container}
+              canvas
+              tag={frameTag}
+              style={frameStyle}
+            />
+          </Frame>
+          {isEditingRegularPage && <EmptyCanvasHint />}
+        </div>
 
         {isEditingRegularPage && (
           <ZonePreview craftState={footerPage.craftState} zone="footer" />

craft/src/editor/EmptyCanvasHint.test.tsx

@@ -0,0 +1,67 @@
+import { describe, test, expect, vi, beforeEach } from 'vitest';
+import React from 'react';
+import { createRoot, Root } from 'react-dom/client';
+import { act } from 'react-dom/test-utils';
+
+/* Same DOM-harness pattern as Footer.editguard.test.tsx: mock @craftjs/core's
+   useEditor so we can drive editor state without a real <Editor> tree. */
+let mockNodes: Record<string, { data: { nodes: string[] } }> = {};
+let mockDraggedSize = 0;
+
+vi.mock('@craftjs/core', () => ({
+  useEditor: (collect: (state: any) => any) =>
+    collect({
+      nodes: mockNodes,
+      events: { dragged: { size: mockDraggedSize } },
+    }),
+}));
+
+import { EmptyCanvasHint } from './Canvas';
+
+let container: HTMLDivElement;
+let root: Root;
+
+function render(ui: React.ReactElement) {
+  container = document.createElement('div');
+  document.body.appendChild(container);
+  act(() => {
+    root = createRoot(container);
+    root.render(ui);
+  });
+}
+
+beforeEach(() => {
+  mockNodes = {};
+  mockDraggedSize = 0;
+});
+
+describe('EmptyCanvasHint', () => {
+  test('renders nothing before ROOT has mounted (no root node yet)', () => {
+    render(<EmptyCanvasHint />);
+    expect(container.querySelector('.empty-canvas-hint')).toBeNull();
+    container.remove();
+  });
+
+  test('renders the hint once ROOT exists with zero children', () => {
+    mockNodes = { ROOT: { data: { nodes: [] } } };
+    render(<EmptyCanvasHint />);
+    expect(container.querySelector('.empty-canvas-hint')).not.toBeNull();
+    expect(container.textContent).toContain('Drag blocks from the left panel');
+    container.remove();
+  });
+
+  test('hides once the page has content', () => {
+    mockNodes = { ROOT: { data: { nodes: ['node-1'] } } };
+    render(<EmptyCanvasHint />);
+    expect(container.querySelector('.empty-canvas-hint')).toBeNull();
+    container.remove();
+  });
+
+  test('hides while a drag is in progress, even on an empty root', () => {
+    mockNodes = { ROOT: { data: { nodes: [] } } };
+    mockDraggedSize = 1;
+    render(<EmptyCanvasHint />);
+    expect(container.querySelector('.empty-canvas-hint')).toBeNull();
+    container.remove();
+  });
+});