Blueprints: Fix intermittent blank workspace when creating documents from blueprints (closes #21996)

src/Umbraco.Web.UI.Client/src/packages/core/router/route/router-slot.element.ts

@@ -30,10 +30,7 @@ export class UmbRouterSlotElement extends UmbLitElement {
 	public set routes(value: UmbRoute[] | undefined) {
 		value ??= [];
 		const oldValue = this.#router.routes;
-		if (
-			value.length !== oldValue?.length ||
-			value.filter((route) => oldValue?.findIndex((r) => r.path === route.path) === -1).length > 0
-		) {
+		if (value.length !== oldValue?.length || value.some((route, index) => route !== oldValue?.[index])) {
 			this.#router.routes = value;
 		}
 	}

src/Umbraco.Web.UI.Client/src/packages/core/view/context/view.controller.ts

@@ -66,6 +66,8 @@ export class UmbViewController extends UmbControllerBase {
 
 	public readonly viewAlias: string | null;
 
+	#destroyed = false;
+
 	#variantId = new UmbClassState<UmbVariantId | undefined>(undefined);
 	protected readonly variantId = this.#variantId.asObservable();
 
@@ -127,7 +129,7 @@ export class UmbViewController extends UmbControllerBase {
 	}
 
 	public provideAt(controllerHost: UmbClassInterface): void {
-		if (this.#currentProvideHost === controllerHost) return;
+		if (this.#destroyed || this.#currentProvideHost === controllerHost) return;
 
 		this.unprovide();
 
@@ -357,10 +359,10 @@ export class UmbViewController extends UmbControllerBase {
 	}
 
 	override destroy(): void {
+		this.#destroyed = true;
 		this.#inherit = false;
 		this.#removeActive();
 		this.#autoActivate = false;
-		(this as any).provideAt = undefined;
 		this.unprovide();
 		super.destroy();
 		this.#consumeParentCtrl = undefined;

src/Umbraco.Web.UI.Client/src/packages/documents/documents/workspace/document-workspace.context.ts

@@ -241,10 +241,20 @@ export class UmbDocumentWorkspaceContext
 
 	async create(parent: UmbEntityModel, documentTypeUnique: string, blueprintUnique?: string) {
 		if (blueprintUnique) {
+			// Reset state and set loading immediately, before the async blueprint data fetch.
+			// This ensures the workspace shows a loading indicator while the data is being fetched,
+			// preventing the previous workspace editor's inner router from firing history.replaceState
+			// (via the default-variant redirect route) which would cancel the outer navigation. (#21996)
+			this.resetState();
+			this.loading.addState({ unique: 'blueprint-fetch' });
+
 			const blueprintRepository = new UmbDocumentBlueprintDetailRepository(this);
 			const { data } = await blueprintRepository.scaffoldByUnique(blueprintUnique);
 
-			if (!data) throw new Error('Blueprint data is missing');
+			if (!data) {
+				this.loading.removeState('blueprint-fetch');
+				throw new Error('Blueprint data is missing');
+			}
 
 			return this.createScaffold({
 				parent,