backend/src/main/java/com/printcalculator/controller/PublicShopController.java

@@ -62,6 +62,12 @@ public class PublicShopController {
         return ResponseEntity.ok(publicShopCatalogService.getProductByPublicPath(publicPath, lang));
     }
 
+    @GetMapping("/products/by-id-prefix/{idPrefix}")
+    public ResponseEntity<ShopProductDetailDto> getProductByIdPrefix(@PathVariable String idPrefix,
+                                                                     @RequestParam(required = false) String lang) {
+        return ResponseEntity.ok(publicShopCatalogService.getProductByIdPrefix(idPrefix, lang));
+    }
+
     @GetMapping("/products/{slug}/model")
     public ResponseEntity<Resource> getProductModel(@PathVariable String slug) throws IOException {
         PublicShopCatalogService.ProductModelDownload model = publicShopCatalogService.getProductModelDownload(slug);

backend/src/main/java/com/printcalculator/service/shop/PublicShopCatalogService.java

@@ -163,6 +163,28 @@ public class PublicShopCatalogService {
         );
     }
 
+    public ShopProductDetailDto getProductByIdPrefix(String idPrefix, String language) {
+        String normalizedLanguage = normalizeLanguage(language);
+        String normalizedIdPrefix = normalizeProductIdPrefix(idPrefix);
+        if (normalizedIdPrefix == null) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "Product not found");
+        }
+
+        CategoryContext categoryContext = loadCategoryContext(normalizedLanguage);
+        PublicProductContext productContext = loadPublicProductContext(categoryContext, normalizedLanguage);
+        ProductEntry entry = requirePublicProductEntry(
+                productContext.entriesByIdPrefix().get(normalizedIdPrefix),
+                categoryContext
+        );
+
+        return toProductDetailDto(
+                entry,
+                productContext.productMediaBySlug(),
+                productContext.variantColorHexByMaterialAndColor(),
+                normalizedLanguage
+        );
+    }
+
     public ProductModelDownload getProductModelDownload(String slug) {
         CategoryContext categoryContext = loadCategoryContext(null);
         PublicProductContext productContext = loadPublicProductContext(categoryContext, null);
@@ -231,11 +253,19 @@ public class PublicShopCatalogService {
                         (left, right) -> left,
                         LinkedHashMap::new
                 ));
+        Map<String, ProductEntry> entriesByIdPrefix = entries.stream()
+                .collect(Collectors.toMap(
+                        entry -> normalizeProductIdPrefix(ShopPublicPathSupport.productIdPrefix(entry.product().getId())),
+                        entry -> entry,
+                        (left, right) -> left,
+                        LinkedHashMap::new
+                ));
 
         return new PublicProductContext(
                 entries,
                 entriesBySlug,
                 entriesByPublicPath,
+                entriesByIdPrefix,
                 productMediaBySlug,
                 variantColorHexByMaterialAndColor
         );
@@ -566,6 +596,15 @@ public class PublicShopCatalogService {
         return normalized.toLowerCase(Locale.ROOT);
     }
 
+    private String normalizeProductIdPrefix(String idPrefix) {
+        String normalized = trimToNull(idPrefix);
+        if (normalized == null) {
+            return null;
+        }
+        normalized = normalized.toLowerCase(Locale.ROOT);
+        return normalized.matches("^[0-9a-f]{8}$") ? normalized : null;
+    }
+
     private String trimToNull(String value) {
         String raw = String.valueOf(value == null ? "" : value).trim();
         if (raw.isEmpty()) {
@@ -662,6 +701,7 @@ public class PublicShopCatalogService {
             List<ProductEntry> entries,
             Map<String, ProductEntry> entriesBySlug,
             Map<String, ProductEntry> entriesByPublicPath,
+            Map<String, ProductEntry> entriesByIdPrefix,
             Map<String, List<PublicMediaUsageDto>> productMediaBySlug,
             Map<String, String> variantColorHexByMaterialAndColor
     ) {

backend/src/test/java/com/printcalculator/service/shop/PublicShopCatalogServiceTest.java

@@ -108,6 +108,21 @@ class PublicShopCatalogServiceTest {
         assertEquals("/en/shop/p/12345678-bike-wall-hanger", response.localizedPaths().get("en"));
     }
 
+    @Test
+    void getProductByIdPrefix_shouldResolveLocalizedProduct() {
+        ShopCategory category = buildCategory();
+        ShopProduct product = buildProduct(category);
+        ShopProductVariant variant = buildVariant(product);
+
+        stubPublicCatalog(category, product, variant);
+
+        ShopProductDetailDto response = service.getProductByIdPrefix("12345678", "de");
+
+        assertEquals("bike-wall-hanger", response.slug());
+        assertEquals("12345678-bike-wall-hanger", response.publicPath());
+        assertEquals("/de/shop/p/12345678-bike-wall-hanger", response.localizedPaths().get("de"));
+    }
+
     @Test
     void getProductByPublicPath_shouldRejectNonCanonicalSegment() {
         ShopCategory category = buildCategory();

frontend/src/app/core/interceptors/server-origin.interceptor.spec.ts

@@ -92,10 +92,10 @@ describe('serverOriginInterceptor', () => {
   it('uses the internal SSR API origin for public shop discovery calls', () => {
     testGlobal.__SSR_INTERNAL_API_ORIGIN__ = 'http://backend:8000/';
 
-    http.get('/api/shop/products/by-path/example?lang=de').subscribe();
+    http.get('/api/shop/products/by-id-prefix/91823f84?lang=de').subscribe();
 
     const request = httpMock.expectOne(
-      'http://backend:8000/api/shop/products/by-path/example?lang=de',
+      'http://backend:8000/api/shop/products/by-id-prefix/91823f84?lang=de',
     );
     expect(request.request.headers.get('authorization')).toBe(
       'Basic dGVzdDp0ZXN0',
@@ -133,10 +133,10 @@ describe('serverOriginInterceptor', () => {
     http = TestBed.inject(HttpClient);
     httpMock = TestBed.inject(HttpTestingController);
 
-    http.get('/api/shop/products/by-path/example?lang=de').subscribe();
+    http.get('/api/shop/products/by-id-prefix/91823f84?lang=de').subscribe();
 
     const request = httpMock.expectOne(
-      'http://backend:8000/api/shop/products/by-path/example?lang=de',
+      'http://backend:8000/api/shop/products/by-id-prefix/91823f84?lang=de',
     );
     expect(request.request.headers.get('authorization')).toBeNull();
     expect(request.request.headers.get('cookie')).toBe('session=abc123');
@@ -184,10 +184,10 @@ describe('serverOriginInterceptor', () => {
     http = TestBed.inject(HttpClient);
     httpMock = TestBed.inject(HttpTestingController);
 
-    http.get('/api/shop/products/by-path/example?lang=de').subscribe();
+    http.get('/api/shop/products/by-id-prefix/91823f84?lang=de').subscribe();
 
     const request = httpMock.expectOne(
-      'https://dev.3d-fab.ch/api/shop/products/by-path/example?lang=de',
+      'https://dev.3d-fab.ch/api/shop/products/by-id-prefix/91823f84?lang=de',
     );
     expect(request.request.headers.get('authorization')).toBeNull();
     expect(request.request.headers.get('cookie')).toBe('session=abc123');

frontend/src/app/core/interceptors/server-origin.interceptor.ts

@@ -19,6 +19,7 @@ const FORWARDED_REQUEST_HEADERS = [
 const SHOP_DISCOVERY_API_PATTERNS = [
   /^\/api\/shop\/categories(?:\/[^/?#]+)?$/i,
   /^\/api\/shop\/products$/i,
+  /^\/api\/shop\/products\/by-id-prefix\/[^/?#]+$/i,
   /^\/api\/shop\/products\/by-path\/[^/?#]+$/i,
   /^\/api\/shop\/products\/[^/?#]+$/i,
 ] as const;

frontend/src/app/features/shop/product-detail.component.spec.ts

@@ -71,7 +71,13 @@ describe('ProductDetailComponent', () => {
     };
   }
 
-  function createComponent(routerUrl = '/de/shop/p/91823f84-bike-wall-hanger') {
+  function createComponent(
+    routerUrl = '/de/shop/p/91823f84-bike-wall-hanger',
+    options?: {
+      currentLang?: 'it' | 'en' | 'de' | 'fr';
+      selectedLang?: 'it' | 'en' | 'de' | 'fr';
+    },
+  ) {
     const responseInit: { status?: number } = {};
     const seoService = jasmine.createSpyObj<SeoService>('SeoService', [
       'applyResolvedSeo',
@@ -93,10 +99,12 @@ describe('ProductDetailComponent', () => {
       return translations[key] ?? key;
     });
 
-    const currentLang = signal<'it' | 'en' | 'de' | 'fr'>('de');
+    const currentLang = signal<'it' | 'en' | 'de' | 'fr'>(
+      options?.currentLang ?? 'de',
+    );
     const languageService = {
       currentLang,
-      selectedLang: () => currentLang(),
+      selectedLang: () => options?.selectedLang ?? currentLang(),
       setLocalizedRouteOverrides: jasmine.createSpy(
         'setLocalizedRouteOverrides',
       ),
@@ -193,6 +201,21 @@ describe('ProductDetailComponent', () => {
     );
   });
 
+  it('uses the route language for canonical SEO even if the selected translation language lags', () => {
+    const { component, seoService } = createComponent(undefined, {
+      currentLang: 'de',
+      selectedLang: 'en',
+    });
+
+    (component as any).applySeo(buildProduct());
+
+    expect(seoService.applyResolvedSeo).toHaveBeenCalledWith(
+      jasmine.objectContaining({
+        canonicalPath: '/de/shop/p/91823f84-bike-wall-hanger',
+      }),
+    );
+  });
+
   it('applies noindex for products explicitly marked as non-indexable', () => {
     const { component, seoService } = createComponent();
 

frontend/src/app/features/shop/product-detail.component.ts

@@ -605,7 +605,7 @@ export class ProductDetailComponent {
       this.translate.instant('SHOP.CATALOG_META_DESCRIPTION');
     const robots =
       product.indexable === false ? 'noindex, nofollow' : 'index, follow';
-    const lang = this.languageService.selectedLang();
+    const lang = this.languageService.currentLang();
     const canonicalPath =
       product.localizedPaths?.[lang] ?? product.localizedPaths?.it ?? null;
 
@@ -857,7 +857,7 @@ export class ProductDetailComponent {
     }
 
     const currentTree = this.router.parseUrl(this.router.url);
-    const lang = this.languageService.selectedLang();
+    const lang = this.languageService.currentLang();
     const targetPath =
       product.localizedPaths?.[lang] ??
       `/${lang}/shop/p/${this.shopRouteService.productPathSegment(product)}`;

frontend/src/app/features/shop/services/shop.service.spec.ts

@@ -1,3 +1,4 @@
+import { signal } from '@angular/core';
 import { TestBed } from '@angular/core/testing';
 import {
   HttpClientTestingModule,
@@ -13,6 +14,11 @@ import { LanguageService } from '../../../core/services/language.service';
 describe('ShopService', () => {
   let service: ShopService;
   let httpMock: HttpTestingController;
+  const currentLang = signal<'it' | 'en' | 'de' | 'fr'>('it');
+  const languageService = {
+    currentLang,
+    selectedLang: jasmine.createSpy('selectedLang').and.returnValue('it'),
+  };
 
   const buildCart = (): ShopCartResponse => ({
     session: {
@@ -131,13 +137,14 @@ describe('ShopService', () => {
         ShopService,
         {
           provide: LanguageService,
-          useValue: {
-            selectedLang: () => 'it',
-          },
+          useValue: languageService,
         },
       ],
     });
 
+    currentLang.set('it');
+    languageService.selectedLang.and.returnValue('it');
+
     service = TestBed.inject(ShopService);
     httpMock = TestBed.inject(HttpTestingController);
   });
@@ -196,7 +203,7 @@ describe('ShopService', () => {
       return (
         request.method === 'GET' &&
         request.url ===
-          'http://localhost:8000/api/shop/products/by-path/12345678-supporto-cavo-scrivania' &&
+          'http://localhost:8000/api/shop/products/by-id-prefix/12345678' &&
         request.params.get('lang') === 'it'
       );
     });
@@ -206,47 +213,74 @@ describe('ShopService', () => {
     expect(response?.name).toBe('Supporto cavo scrivania');
   });
 
-  it('rejects product paths whose slug tail does not match the canonical path', () => {
-    let errorResponse: { status?: number } | undefined;
+  it('resolves products from the stable uuid prefix even if the slug tail is stale', () => {
+    let response: ShopProductDetail | undefined;
 
     service.getProductByPublicPath('12345678-qualunque-nome').subscribe({
-      next: () => fail('Expected canonical path mismatch to return 404'),
-      error: (error) => {
-        errorResponse = error;
+      next: (product) => {
+        response = product;
       },
+      error: () => fail('Expected stale slug tails to resolve from the uuid prefix'),
     });
 
     const request = httpMock.expectOne((request) => {
       return (
         request.method === 'GET' &&
         request.url ===
-          'http://localhost:8000/api/shop/products/by-path/12345678-qualunque-nome' &&
+          'http://localhost:8000/api/shop/products/by-id-prefix/12345678' &&
         request.params.get('lang') === 'it'
       );
     });
-    request.flush('Not found', { status: 404, statusText: 'Not Found' });
-    expect(errorResponse?.status).toBe(404);
+    request.flush(buildProduct());
+
+    expect(response?.id).toBe('12345678-abcd-4abc-9abc-1234567890ab');
   });
 
-  it('rejects bare uuid product paths without the localized slug tail', () => {
-    let errorResponse: { status?: number } | undefined;
+  it('resolves bare uuid product paths through the stable uuid prefix endpoint', () => {
+    let response: ShopProductDetail | undefined;
 
     service.getProductByPublicPath('12345678').subscribe({
-      next: () => fail('Expected bare uuid path to return 404'),
-      error: (error) => {
-        errorResponse = error;
+      next: (product) => {
+        response = product;
       },
+      error: () => fail('Expected bare uuid path to resolve from the uuid prefix'),
     });
 
     const request = httpMock.expectOne((request) => {
       return (
         request.method === 'GET' &&
         request.url ===
-          'http://localhost:8000/api/shop/products/by-path/12345678' &&
+          'http://localhost:8000/api/shop/products/by-id-prefix/12345678' &&
         request.params.get('lang') === 'it'
       );
     });
-    request.flush('Not found', { status: 404, statusText: 'Not Found' });
-    expect(errorResponse?.status).toBe(404);
+    request.flush(buildProduct());
+
+    expect(response?.publicPath).toBe('12345678-supporto-cavo-scrivania');
+  });
+
+  it('uses the route language for public shop lookups when translate.currentLang lags behind', () => {
+    let response: ShopProductDetail | undefined;
+
+    currentLang.set('de');
+    languageService.selectedLang.and.returnValue('en');
+
+    service
+      .getProductByPublicPath('12345678-schreibtisch-kabelhalter')
+      .subscribe((product) => {
+        response = product;
+      });
+
+    const request = httpMock.expectOne((request) => {
+      return (
+        request.method === 'GET' &&
+        request.url ===
+          'http://localhost:8000/api/shop/products/by-id-prefix/12345678' &&
+        request.params.get('lang') === 'de'
+      );
+    });
+    request.flush(buildProduct());
+
+    expect(response?.id).toBe('12345678-abcd-4abc-9abc-1234567890ab');
   });
 });

frontend/src/app/features/shop/services/shop.service.ts

@@ -290,8 +290,13 @@ export class ShopService {
       }));
     }
 
+    const productIdPrefix = this.extractProductIdPrefix(normalizedPath);
+    const endpoint = productIdPrefix
+      ? `${this.apiUrl}/products/by-id-prefix/${encodeURIComponent(productIdPrefix)}`
+      : `${this.apiUrl}/products/by-path/${encodeURIComponent(normalizedPath)}`;
+
     return this.http.get<ShopProductDetail>(
-      `${this.apiUrl}/products/by-path/${encodeURIComponent(normalizedPath)}`,
+      endpoint,
       {
         params: this.buildLangParams(),
       },
@@ -304,6 +309,11 @@ export class ShopService {
       .toLowerCase();
   }
 
+  private extractProductIdPrefix(value: string): string | null {
+    const match = value.match(/^([0-9a-f]{8})(?:-|$)/);
+    return match?.[1] ?? null;
+  }
+
   loadCart(): Observable<ShopCartResponse> {
     this.cartLoading.set(true);
     return this.http
@@ -455,7 +465,10 @@ export class ShopService {
   }
 
   private buildLangParams(): HttpParams {
-    return new HttpParams().set('lang', this.languageService.selectedLang());
+    // Public shop URLs are localized. During direct loads the translation
+    // service can still momentarily reflect the browser language, while the
+    // route language has already been resolved from the URL.
+    return new HttpParams().set('lang', this.languageService.currentLang());
   }
 
   private setCart(cart: ShopCartResponse): void {