fix(front-end): seo improvemnts

frontend/public/sitemap-static.xml

@@ -6,7 +6,7 @@
     <xhtml:link rel="alternate" hreflang="en-CH" href="https://3d-fab.ch/en" />
     <xhtml:link rel="alternate" hreflang="de-CH" href="https://3d-fab.ch/de" />
     <xhtml:link rel="alternate" hreflang="fr-CH" href="https://3d-fab.ch/fr" />
-    <xhtml:link rel="alternate" hreflang="x-default" href="https://3d-fab.ch/it" />
+    <xhtml:link rel="alternate" hreflang="x-default" href="https://3d-fab.ch/" />
     <changefreq>weekly</changefreq>
     <priority>1.0</priority>
   </url>
@@ -16,7 +16,7 @@
     <xhtml:link rel="alternate" hreflang="en-CH" href="https://3d-fab.ch/en" />
     <xhtml:link rel="alternate" hreflang="de-CH" href="https://3d-fab.ch/de" />
     <xhtml:link rel="alternate" hreflang="fr-CH" href="https://3d-fab.ch/fr" />
-    <xhtml:link rel="alternate" hreflang="x-default" href="https://3d-fab.ch/it" />
+    <xhtml:link rel="alternate" hreflang="x-default" href="https://3d-fab.ch/" />
     <changefreq>weekly</changefreq>
     <priority>1.0</priority>
   </url>
@@ -26,7 +26,7 @@
     <xhtml:link rel="alternate" hreflang="en-CH" href="https://3d-fab.ch/en" />
     <xhtml:link rel="alternate" hreflang="de-CH" href="https://3d-fab.ch/de" />
     <xhtml:link rel="alternate" hreflang="fr-CH" href="https://3d-fab.ch/fr" />
-    <xhtml:link rel="alternate" hreflang="x-default" href="https://3d-fab.ch/it" />
+    <xhtml:link rel="alternate" hreflang="x-default" href="https://3d-fab.ch/" />
     <changefreq>weekly</changefreq>
     <priority>1.0</priority>
   </url>
@@ -36,7 +36,7 @@
     <xhtml:link rel="alternate" hreflang="en-CH" href="https://3d-fab.ch/en" />
     <xhtml:link rel="alternate" hreflang="de-CH" href="https://3d-fab.ch/de" />
     <xhtml:link rel="alternate" hreflang="fr-CH" href="https://3d-fab.ch/fr" />
-    <xhtml:link rel="alternate" hreflang="x-default" href="https://3d-fab.ch/it" />
+    <xhtml:link rel="alternate" hreflang="x-default" href="https://3d-fab.ch/" />
     <changefreq>weekly</changefreq>
     <priority>1.0</priority>
   </url>

frontend/src/app/core/services/seo.service.spec.ts

@@ -117,6 +117,34 @@ describe('SeoService', () => {
     expect(ogLocaleCall?.[0].content).toBe('it_CH');
   });
 
+  it('uses the locale-adaptive root as x-default for home pages', () => {
+    createService({
+      url: '/de',
+      data: {
+        seoTitleKey: 'SEO.ROUTES.HOME.TITLE',
+        seoDescriptionKey: 'SEO.ROUTES.HOME.DESCRIPTION',
+      },
+      translations: {
+        'SEO.ROUTES.HOME.TITLE': '3D-Druck in Zürich | 3D fab',
+        'SEO.ROUTES.HOME.DESCRIPTION': '3D-Druckservice in Zürich',
+      },
+    });
+
+    const alternates = Array.from(
+      document.head.querySelectorAll(
+        'link[rel="alternate"][data-seo-managed="true"]',
+      ),
+    ).map((node) => ({
+      hreflang: node.getAttribute('hreflang'),
+      href: node.getAttribute('href'),
+    }));
+
+    expect(alternates).toContain({
+      hreflang: 'x-default',
+      href: `${document.location.origin}/`,
+    });
+  });
+
   it('resolves translated route metadata for the active language', () => {
     const { meta, title } = createService({
       url: '/en/about',

frontend/src/app/core/services/seo.service.ts

@@ -105,7 +105,7 @@ export class SeoService {
       cleanPath,
       canonicalPath,
       alternates,
-      alternates.it ?? canonicalPath,
+      this.buildXDefaultPath(canonicalPath, alternates),
       lang,
     );
   }
@@ -119,8 +119,7 @@ export class SeoService {
     const alternates = this.normalizeAlternatePaths(override.alternates);
     const xDefault =
       this.normalizeSeoPath(override.xDefault) ??
-      alternates?.it ??
+      this.buildXDefaultPath(canonicalPath, alternates);
-      canonicalPath;
 
     this.applySeoValues(
       title,
@@ -162,7 +161,7 @@ export class SeoService {
       cleanPath,
       canonicalPath,
       alternates,
-      alternates.it ?? canonicalPath,
+      this.buildXDefaultPath(canonicalPath, alternates),
       lang,
     );
   }
@@ -360,6 +359,25 @@ export class SeoService {
     }, {});
   }
 
+  private buildXDefaultPath(
+    canonicalPath: string | null,
+    alternates: SeoMap | null,
+  ): string | null {
+    if (canonicalPath && this.isLocalizedHomePath(canonicalPath)) {
+      return '/';
+    }
+
+    return alternates?.it ?? canonicalPath;
+  }
+
+  private isLocalizedHomePath(path: string): boolean {
+    const segments = path.split('/').filter(Boolean);
+    return (
+      segments.length === 1 &&
+      this.supportedLangSet.has(segments[0] as SupportedLang)
+    );
+  }
+
   private normalizeAlternatePaths(
     paths: SeoMap | null | undefined,
   ): SeoMap | null {