feat: enhance product detail page to support default variant selection from query parameters

src/app/core/services/catalog/catalog.service.ts

@@ -35,9 +35,14 @@ export class CatalogService {
     );
   }
 
-  getProducto(id: number): Observable<ProductDetail> {
+  getProducto(id: number, defaultVariantId?: number): Observable<ProductDetail> {
+    const params =
+      defaultVariantId === undefined
+        ? undefined
+        : new HttpParams({ fromObject: { default_variant: defaultVariantId } });
+
     return this.http
-      .get<ApiResponse<ProductDetail>>(`${this.tenantApiUrl}/productos/${id}`)
+      .get<ApiResponse<ProductDetail>>(`${this.tenantApiUrl}/productos/${id}`, { params })
       .pipe(map((response) => response.data));
   }
 

src/app/features/store/pages/product-detail-page/product-detail-page.component.spec.ts

@@ -31,6 +31,7 @@ describe('ProductDetailPageComponent', () => {
   };
 
   let paramMapSubject: BehaviorSubject<any>;
+  let queryParamMapSubject: BehaviorSubject<any>;
   let catalogServiceStub: any;
   let routerStub: any;
 
@@ -48,6 +49,7 @@ describe('ProductDetailPageComponent', () => {
   beforeEach(() => {
     vi.restoreAllMocks();
     paramMapSubject = new BehaviorSubject(convertToParamMap({ id: '1' }));
+    queryParamMapSubject = new BehaviorSubject(convertToParamMap({}));
     catalogServiceStub = {
       getProducto: vi.fn().mockReturnValue(of(mockProduct))
     };
@@ -62,7 +64,10 @@ describe('ProductDetailPageComponent', () => {
       providers: [
         {
           provide: ActivatedRoute,
-          useValue: { paramMap: paramMapSubject.asObservable() }
+          useValue: {
+            paramMap: paramMapSubject.asObservable(),
+            queryParamMap: queryParamMapSubject.asObservable()
+          }
         },
         {
           provide: CatalogService,
@@ -83,7 +88,7 @@ describe('ProductDetailPageComponent', () => {
 
     const element = fixture.nativeElement as HTMLElement;
 
-    expect(catalogServiceStub.getProducto).toHaveBeenCalledWith(1);
+    expect(catalogServiceStub.getProducto).toHaveBeenCalledWith(1, undefined);
 
     expect(element.querySelector('app-product-carousel')).not.toBeNull();
     expect(element.querySelector('.product-detail__title')?.textContent).toContain('Auriculares Bluetooth');
@@ -103,6 +108,26 @@ describe('ProductDetailPageComponent', () => {
     expect(element.textContent).toContain('No pudimos cargar los detalles del producto.');
   });
 
+  it('passes default_variant from the query params when loading the product', async () => {
+    queryParamMapSubject.next(convertToParamMap({ default_variant: '123' }));
+
+    await configureTestingModule();
+    const fixture = TestBed.createComponent(ProductDetailPageComponent);
+    fixture.detectChanges();
+
+    expect(catalogServiceStub.getProducto).toHaveBeenCalledWith(1, 123);
+  });
+
+  it('ignores an invalid default_variant query param', async () => {
+    queryParamMapSubject.next(convertToParamMap({ default_variant: 'abc' }));
+
+    await configureTestingModule();
+    const fixture = TestBed.createComponent(ProductDetailPageComponent);
+    fixture.detectChanges();
+
+    expect(catalogServiceStub.getProducto).toHaveBeenCalledWith(1, undefined);
+  });
+
   it('should use default variant images if present', async () => {
     const detailProduct: ProductDetail = {
       ...mockProduct,

src/app/features/store/pages/product-detail-page/product-detail-page.component.ts

@@ -12,7 +12,7 @@ import {
 } from '@angular/core';
 import { CommonModule } from '@angular/common';
 import { ActivatedRoute, Router, RouterModule } from '@angular/router';
-import { Subscription } from 'rxjs';
+import { combineLatest, Subscription } from 'rxjs';
 
 import { CatalogService } from '../../../../core/services/catalog/catalog.service';
 import {
@@ -90,17 +90,17 @@ export class ProductDetailPageComponent implements OnInit, OnDestroy {
   }
 
   ngOnInit(): void {
-    this.routeSub = this.route.paramMap.subscribe((params) => {
-      const idParam = params.get('id');
-      if (idParam) {
-        const id = Number(idParam);
-        if (Number.isInteger(id)) {
-          this.loadProduct(id);
-        } else {
+    this.routeSub = combineLatest([this.route.paramMap, this.route.queryParamMap]).subscribe(
+      ([params, queryParams]) => {
+        const id = this.parseIntegerParam(params.get('id'));
+        if (id === null) {
           this.error.set('ID de producto inválido');
+          return;
         }
+
+        this.loadProduct(id, this.parseIntegerParam(queryParams.get('default_variant')) ?? undefined);
       }
-    });
+    );
   }
 
   ngOnDestroy(): void {
@@ -110,13 +110,13 @@ export class ProductDetailPageComponent implements OnInit, OnDestroy {
     this.clearMeasurementTimer();
   }
 
-  private loadProduct(id: number): void {
+  private loadProduct(id: number, defaultVariantId?: number): void {
     this.loading.set(true);
     this.error.set(null);
     this.product.set(null);
 
     this.productSub?.unsubscribe();
-    this.productSub = this.catalogService.getProducto(id).subscribe({
+    this.productSub = this.catalogService.getProducto(id, defaultVariantId).subscribe({
       next: (prod) => {
         this.product.set(prod);
         this.initializeSelections(prod);
@@ -240,6 +240,16 @@ export class ProductDetailPageComponent implements OnInit, OnDestroy {
 
     return null;
   }
+
+  private parseIntegerParam(value: string | null): number | null {
+    if (!value) {
+      return null;
+    }
+
+    const parsed = Number(value);
+    return Number.isInteger(parsed) ? parsed : null;
+  }
+
   private normalizeText(value: string | null | undefined): string {
     return (value ?? '')
       .normalize('NFD')