arch(sprint1): add unknown widget fallback diagnostics

src/app/core/runtime/runtime-diagnostics.service.ts

@@ -0,0 +1,16 @@
+import { Injectable } from '@angular/core';
+
+export interface UnknownWidgetDiagnostic {
+  tenant: string;
+  page: string;
+  section: string;
+  widget: string;
+  reason: string;
+}
+
+@Injectable({ providedIn: 'root' })
+export class RuntimeDiagnosticsService {
+  logUnknownWidget(event: UnknownWidgetDiagnostic): void {
+    console.warn('[PlatformRuntime][UnknownWidget]', event);
+  }
+}

src/app/layouts/containers/dynamic-page-layout.component.ts

@@ -4,6 +4,9 @@ import { NgComponentOutlet } from '@angular/common';
 import { PageRenderModel } from '../../dynamic-renderer/page-renderer/page-renderer.model';
 import { WidgetRenderNode } from '../../dynamic-renderer/widget-host/widget-host.model';
 import { WidgetHostService } from '../../dynamic-renderer/widget-host/widget-host.service';
+import { RuntimeDiagnosticsService } from '../../core/runtime/runtime-diagnostics.service';
+import { UnknownWidgetComponent } from '../../widgets/ui';
+import { ConfigService } from '../../core/config/config.service';
 
 @Component({
   selector: 'app-dynamic-page-layout',
@@ -16,7 +19,7 @@ import { WidgetHostService } from '../../dynamic-renderer/widget-host/widget-hos
           <section class="dynamic-section" [attr.data-section-type]="section.type">
             @for (widget of section.widgets; track widget.id) {
               <div class="dynamic-widget" [attr.data-widget-type]="widget.type">
-                @if (resolveWidget(widget); as resolved) {
+                @if (resolveWidget(widget, section.id); as resolved) {
                   <ng-container *ngComponentOutlet="resolved.component; inputs: resolved.props"></ng-container>
                 }
               </div>
@@ -36,10 +39,42 @@ import { WidgetHostService } from '../../dynamic-renderer/widget-host/widget-hos
 })
 export class DynamicPageLayoutComponent {
   @Input() model: PageRenderModel | null = null;
+  private readonly loggedUnknownWidgets = new Set<string>();
 
-  constructor(private readonly widgetHost: WidgetHostService) {}
+  constructor(
+    private readonly widgetHost: WidgetHostService,
+    private readonly diagnostics: RuntimeDiagnosticsService,
+    private readonly configService: ConfigService
+  ) {}
 
-  resolveWidget(widget: WidgetRenderNode) {
-    return this.widgetHost.resolveWidget(widget.source);
+  resolveWidget(widget: WidgetRenderNode, sectionId?: string) {
+    const resolved = this.widgetHost.resolveWidget(widget.source);
+    if (resolved) {
+      return resolved;
+    }
+
+    const diagnosticKey = `${this.model?.id ?? 'unknown'}:${sectionId ?? 'unknown'}:${widget.id}`;
+    if (!this.loggedUnknownWidgets.has(diagnosticKey)) {
+      this.loggedUnknownWidgets.add(diagnosticKey);
+
+      const tenantId = this.configService.getBootstrapSnapshot()?.tenant.id ?? 'unknown';
+      this.diagnostics.logUnknownWidget({
+        tenant: tenantId,
+        page: this.model?.key ?? 'unknown',
+        section: sectionId ?? 'unknown',
+        widget: `${widget.type}@${widget.version}`,
+        reason: 'not_registered_in_widget_registry'
+      });
+    }
+
+    return {
+      type: widget.type,
+      version: widget.version,
+      component: UnknownWidgetComponent,
+      props: {
+        widgetType: widget.type,
+        widgetVersion: widget.version
+      }
+    };
   }
 }

src/app/widgets/ui/index.ts

@@ -1,3 +1,4 @@
 export * from './footer-navigation-widget.component';
 export * from './hero-widget.component';
 export * from './product-carousel-widget.component';
+export * from './unknown-widget.component';

src/app/widgets/ui/unknown-widget.component.ts

@@ -0,0 +1,38 @@
+import { ChangeDetectionStrategy, Component, Input } from '@angular/core';
+
+@Component({
+  selector: 'app-unknown-widget',
+  standalone: true,
+  template: `
+    <section class="unknown-widget" role="status" aria-live="polite">
+      <strong>Widget unavailable</strong>
+      <p>{{ widgetType }}@{{ widgetVersion }}</p>
+    </section>
+  `,
+  styles: [
+    `
+      .unknown-widget {
+        border: 1px dashed var(--border-color, #d3dad9);
+        border-radius: var(--radius-md, 12px);
+        padding: 0.75rem;
+        color: var(--text-secondary, #667a77);
+        background: var(--background-secondary, #f5f5f5);
+      }
+
+      .unknown-widget strong {
+        display: block;
+        font-size: 0.9rem;
+      }
+
+      .unknown-widget p {
+        margin: 0.25rem 0 0;
+        font-size: 0.8rem;
+      }
+    `
+  ],
+  changeDetection: ChangeDetectionStrategy.OnPush
+})
+export class UnknownWidgetComponent {
+  @Input() widgetType: string = 'unknown';
+  @Input() widgetVersion: string = 'unknown';
+}