[v1.0][web_core][react] ComponentNode and useNodeView omit component metadata.extensions from resolved nodes and toJSON() #3469

Summary

When MessageProcessor.applyComponentUpdate processes a v1.0 component carrying metadata: { extensions: { ... } }, it stores metadata on ComponentModel.metadata (typescript/core/web_core/src/state/component-model.ts line 45).

However, when NodeResolver builds the reactive ComponentNode tree (typescript/core/web_core/src/resolution/component-node.ts and node-resolver.ts):

1. ComponentNode (MutableComponentNode) has no metadata property or getter.
2. ComponentNode.toJSON() (lines 213–226 of component-node.ts) serializes { id, type, ...props } and completely omits metadata (unlike ComponentModel.componentTree, which includes ...(this.metadata !== undefined ? {metadata: this.metadata} : {})).
3. When ComponentModel.metadata is updated on an existing component (existing.metadata = metadata; existing.properties = properties; at message-processor.ts lines 1059–1060), if properties are shallow-equal (setProps in component-node.ts line 238), node.props does not emit and React views subscribed via useNodeView in @a2ui/react do not re-render on a metadata-only update.

Affected Component / Files

• Repository commit: e9dbcc3 (main) and npm packages @a2ui/[email protected], @a2ui/[email protected]
• File path(s):
  • typescript/core/web_core/src/resolution/component-node.ts (lines 50–119, 213–241)
  • typescript/core/web_core/src/resolution/node-resolver.ts (lines 380–450)
  • typescript/renderers/react/src/node-view.tsx (lines 207–266)

Steps to Reproduce / Evidence

import { MessageProcessor, NodeResolver, basicCatalog } from '@a2ui/web_core/v1_0';

const processor = new MessageProcessor([basicCatalog], undefined, { version: 'v1.0' });
processor.processMessages([
  {
    version: 'v1.0',
    createSurface: {
      surfaceId: 's1',
      catalogId: basicCatalog.id,
      components: [
        {
          id: 'root',
          component: 'Text',
          text: 'Hello',
          metadata: {
            extensions: {
              custom_theme: { variant: 'dark' },
            },
          },
        },
      ],
    },
  },
]);

const surface = processor.model.getSurface('s1');
const resolver = new NodeResolver(surface);
const rootNode = resolver.rootNode.peek();

console.log('ComponentModel.componentTree:', surface.componentsModel.get('root').componentTree);
// Includes: metadata: { extensions: { custom_theme: { variant: 'dark' } } }

console.log('ComponentNode.toJSON():', rootNode.toJSON());
// Actual output: { id: 'root', type: 'Text', text: 'Hello', variant: 'body' }
// `metadata` is completely missing from ComponentNode and rootNode.toJSON()!

Expected Behavior

1. ComponentNode should expose metadata (or reactive metadata signal/property from context?.componentModel.metadata) and include metadata in ComponentNode.toJSON() when defined.
2. Updating a component's metadata.extensions via updateComponents should notify NodeResolver / useNodeView subscribers even when component schema properties (text, variant, etc.) are unchanged.

Actual Behavior

ComponentNode omits metadata from its interface and toJSON(), and metadata-only updateComponents payloads do not trigger node.props updates when schema properties are unchanged.

Suggested Fix

Expose readonly metadata?: Record<string, unknown> on ComponentNode (backed by this.context?.componentModel.metadata), include metadata in MutableComponentNode.toJSON() when defined, and include metadata in NodeResolver's change detection when ComponentModel.onUpdated fires.