add a new type appEntryPoint and a corresponding initializer and load them up in the app element

src/Umbraco.Web.UI.Client/src/apps/app/app.element.ts

@@ -14,8 +14,8 @@ import { pathWithoutBasePath } from '@umbraco-cms/backoffice/router';
 import { OpenAPI, RuntimeLevelModel } from '@umbraco-cms/backoffice/external/backend-api';
 import { UmbContextDebugController } from '@umbraco-cms/backoffice/debug';
 import {
+	UmbAppEntryPointExtensionInitializer,
 	UmbBundleExtensionInitializer,
-	UmbEntryPointExtensionInitializer,
 	UmbServerExtensionRegistrator,
 } from '@umbraco-cms/backoffice/extension-api';
 import { umbExtensionsRegistry } from '@umbraco-cms/backoffice/extension-registry';
@@ -85,8 +85,7 @@ export class UmbAppElement extends UmbLitElement {
 
 		new UmbBundleExtensionInitializer(this, umbExtensionsRegistry);
 
-		// Initialise any entryPoints that export the 'beforeInit' function
-		new UmbEntryPointExtensionInitializer(this, umbExtensionsRegistry, 'beforeInit');
+		new UmbAppEntryPointExtensionInitializer(this, umbExtensionsRegistry);
 
 		new UmbIconRegistry().attach(this);
 		new UUIIconRegistryEssential().attach(this);

src/Umbraco.Web.UI.Client/src/libs/extension-api/initializers/app-entry-point-extension-initializer.ts

@@ -0,0 +1,34 @@
+import type { ManifestAppEntryPoint } from '../types/index.js';
+import { hasInitExport, loadManifestPlainJs } from '../functions/index.js';
+import type { UmbExtensionRegistry } from '../registry/extension.registry.js';
+import { UmbExtensionInitializerBase } from './extension-initializer-base.js';
+import type { UmbElement } from '@umbraco-cms/backoffice/element-api';
+
+/**
+ * Extension initializer for the `appEntryPoint` extension type
+ */
+export class UmbAppEntryPointExtensionInitializer extends UmbExtensionInitializerBase<
+	'appEntryPoint',
+	ManifestAppEntryPoint
+> {
+	constructor(host: UmbElement, extensionRegistry: UmbExtensionRegistry<ManifestAppEntryPoint>) {
+		super(host, extensionRegistry, 'appEntryPoint');
+	}
+
+	async instantiateExtension(manifest: ManifestAppEntryPoint) {
+		if (manifest.js) {
+			const js = await loadManifestPlainJs(manifest.js);
+
+			// If the extension has known exports, be sure to run those
+			if (hasInitExport(js)) {
+				js.onInit(this.host, this.extensionRegistry);
+			}
+		}
+	}
+
+	// eslint-disable-next-line @typescript-eslint/no-unused-vars
+	unloadExtension(_manifest: ManifestAppEntryPoint): void {
+		// No-op
+		// Entry points are not unloaded, but if they were, this is where you would do it.
+	}
+}

src/Umbraco.Web.UI.Client/src/libs/extension-api/initializers/index.ts

@@ -1,3 +1,4 @@
+export * from './app-entry-point-extension-initializer.js';
 export * from './bundle-extension-initializer.js';
 export * from './entry-point-extension-initializer.js';
 export * from './extension-initializer-base.js';

src/Umbraco.Web.UI.Client/src/libs/extension-api/types/index.ts

@@ -1,5 +1,6 @@
 export * from './base.types.js';
 export * from './condition.types.js';
+export * from './manifest-app-entrypoint.interface.js';
 export * from './manifest-base.interface.js';
 export * from './manifest-bundle.interface.js';
 export * from './manifest-condition.interface.js';

src/Umbraco.Web.UI.Client/src/libs/extension-api/types/manifest-app-entrypoint.interface.ts

@@ -0,0 +1,10 @@
+import type { UmbEntryPointModule } from '../models/index.js';
+import type { ManifestPlainJs } from './base.types.js';
+
+/**
+ * This type of extension gives full control and will simply load the specified JS file
+ * You could have custom logic to decide which extensions to load/register by using extensionRegistry
+ */
+export interface ManifestAppEntryPoint extends ManifestPlainJs<UmbEntryPointModule> {
+	type: 'appEntryPoint';
+}