[release/10.0] [Blazor] Fix metadata comments incorrectly being processed as logical elements

src/Components/Web.JS/src/Rendering/LogicalElements.ts

@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-import { ComponentDescriptor } from '../Services/ComponentDescriptorDiscovery';
+import { ComponentDescriptor, isMetadataComment } from '../Services/ComponentDescriptorDiscovery';
 
 /*
   A LogicalElement plays the same role as an Element instance from the point of view of the
@@ -109,6 +109,12 @@ export function toLogicalElement(element: Node, allowExistingContents?: boolean)
     }
 
     element.childNodes.forEach(child => {
+      // Skip metadata comments that will be consumed during discovery
+      // These are not components and should not be part of the logical tree
+      if (isMetadataComment(child)) {
+        return;
+      }
+
       const childLogicalElement = toLogicalElement(child, /* allowExistingContents */ true);
       childLogicalElement[logicalParentPropname] = element;
       childrenArray.push(childLogicalElement);

src/Components/Web.JS/src/Services/ComponentDescriptorDiscovery.ts

@@ -1,6 +1,19 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+// Metadata comments are consumed during discovery and should not be part of the logical tree.
+// They include: WebAssembly options, component state, and web initializers.
+export function isMetadataComment(node: Node): boolean {
+  if (node.nodeType !== Node.COMMENT_NODE) {
+    return false;
+  }
+  const content = node.textContent || '';
+  return content.trim().startsWith('Blazor-Server-Component-State:') ||
+         content.trim().startsWith('Blazor-WebAssembly-Component-State:') ||
+         content.trim().startsWith('Blazor-Web-Initializers:') ||
+         content.trim().startsWith('Blazor-WebAssembly:');
+}
+
 export function discoverComponents(root: Node, type: 'webassembly' | 'server' | 'auto'): ComponentDescriptor[] {
   switch (type) {
     case 'webassembly':