fix: lang switch

app/[locale]/[slug]/page.tsx

@@ -1,4 +1,4 @@
-import { notFound } from 'next/navigation';
+import { notFound, redirect } from 'next/navigation';
 import { Container, Badge, Heading } from '@/components/ui';
 import { getTranslations, setRequestLocale } from 'next-intl/server';
 import { Metadata } from 'next';
@@ -21,15 +21,18 @@ export async function generateMetadata({ params }: PageProps): Promise<Metadata>
 
   if (!pageData) return {};
 
-  const fileSlug = await mapSlugToFileSlug(slug, locale);
+  const fileSlug = await mapSlugToFileSlug(pageData.slug || slug, locale);
   const deSlug = await mapFileSlugToTranslated(fileSlug, 'de');
   const enSlug = await mapFileSlugToTranslated(fileSlug, 'en');
 
+  // Determine correct localized slug based on current locale
+  const currentLocaleSlug = locale === 'de' ? deSlug : enSlug;
+
   return {
     title: pageData.frontmatter.title,
     description: pageData.frontmatter.excerpt || '',
     alternates: {
-      canonical: `${SITE_URL}/${locale}/${slug}`,
+      canonical: `${SITE_URL}/${locale}/${currentLocaleSlug}`,
       languages: {
         de: `${SITE_URL}/de/${deSlug}`,
         en: `${SITE_URL}/en/${enSlug}`,
@@ -39,7 +42,7 @@ export async function generateMetadata({ params }: PageProps): Promise<Metadata>
     openGraph: {
       title: `${pageData.frontmatter.title} | KLZ Cables`,
       description: pageData.frontmatter.excerpt || '',
-      url: `${SITE_URL}/${locale}/${slug}`,
+      url: `${SITE_URL}/${locale}/${currentLocaleSlug}`,
     },
     twitter: {
       card: 'summary_large_image',
@@ -59,6 +62,13 @@ export default async function StandardPage({ params }: PageProps) {
     notFound();
   }
 
+  // Redirect if accessed via a different locale's slug
+  const fileSlug = await mapSlugToFileSlug(pageData.slug || slug, locale);
+  const correctSlug = await mapFileSlugToTranslated(fileSlug, locale);
+  if (correctSlug && correctSlug !== slug) {
+    redirect(`/${locale}/${correctSlug}`);
+  }
+
   // Full-bleed pages render blocks edge-to-edge without the generic article wrapper
   if (pageData.frontmatter.layout === 'fullBleed') {
     return (

app/[locale]/blog/[slug]/page.tsx

@@ -1,4 +1,4 @@
-import { notFound } from 'next/navigation';
+import { notFound, redirect } from 'next/navigation';
 import JsonLd from '@/components/JsonLd';
 import { SITE_URL } from '@/lib/schema';
 import { getPostBySlug, getAdjacentPosts, getReadingTime } from '@/lib/blog';
@@ -32,7 +32,7 @@ export async function generateMetadata({ params }: BlogPostProps): Promise<Metad
     title: post.frontmatter.title,
     description: description,
     alternates: {
-      canonical: `${SITE_URL}/${locale}/blog/${slug}`,
+      canonical: `${SITE_URL}/${locale}/blog/${post.slug}`,
     },
     openGraph: {
       title: `${post.frontmatter.title} | KLZ Cables`,
@@ -40,7 +40,7 @@ export async function generateMetadata({ params }: BlogPostProps): Promise<Metad
       type: 'article',
       publishedTime: post.frontmatter.date,
       authors: ['KLZ Cables'],
-      url: `${SITE_URL}/${locale}/blog/${slug}`,
+      url: `${SITE_URL}/${locale}/blog/${post.slug}`,
     },
     twitter: {
       card: 'summary_large_image',
@@ -54,12 +54,19 @@ export default async function BlogPost({ params }: BlogPostProps) {
   const { locale, slug } = await params;
   setRequestLocale(locale);
   const post = await getPostBySlug(slug, locale);
-  const { prev, next, isPrevRandom, isNextRandom } = await getAdjacentPosts(slug, locale);
 
   if (!post) {
     notFound();
   }
 
+  // If the user accessed this post using a slug from a different locale
+  // (e.g. via the generic language switcher), redirect them to the correct localized slug URL
+  if (post.slug && post.slug !== slug) {
+    redirect(`/${locale}/blog/${post.slug}`);
+  }
+
+  const { prev, next, isPrevRandom, isNextRandom } = await getAdjacentPosts(post.slug, locale);
+
   // Convert Lexical content into a plain string to estimate reading time roughly
   const rawTextContent = JSON.stringify(post.content);
 

app/[locale]/contact/page.tsx

@@ -59,6 +59,21 @@ export default async function ContactPage({ params }: ContactPageProps) {
   const { locale } = await params;
   setRequestLocale(locale);
   const t = await getTranslations({ locale, namespace: 'Contact' });
+
+  // Get translated slug to redirect if user used incorrect static slug
+  const { headers } = await import('next/headers');
+  const headersList = await headers();
+  const urlPath = headersList.get('x-invoke-path') || '';
+  const currentSlug = urlPath.split('/').pop();
+
+  if (currentSlug) {
+    const contactSlugDe = locale === 'de' ? 'kontakt' : 'contact';
+    if (currentSlug !== contactSlugDe && (currentSlug === 'kontakt' || currentSlug === 'contact')) {
+      const { redirect } = await import('next/navigation');
+      redirect(`/${locale}/${contactSlugDe}`);
+    }
+  }
+
   return (
     <div className="flex flex-col min-h-screen bg-neutral-light">
       <JsonLd

app/[locale]/not-found.tsx

@@ -1,66 +1,137 @@
-'use client';
+import { getTranslations } from 'next-intl/server';
-import { useTranslations } from 'next-intl';
 import { Container, Button, Heading } from '@/components/ui';
 import Scribble from '@/components/Scribble';
-import { useEffect } from 'react';
+import { getPayload } from 'payload';
-import { useAnalytics } from '@/components/analytics/useAnalytics';
+import configPromise from '@payload-config';
-import { AnalyticsEvents } from '@/components/analytics/analytics-events';
+import { headers } from 'next/headers';
+import ClientNotFoundTracker from '@/components/analytics/ClientNotFoundTracker';
 
-export default function NotFound() {
+export default async function NotFound() {
-  const t = useTranslations('Error.notFound');
+  const t = await getTranslations('Error.notFound');
-  const { trackEvent } = useAnalytics();
 
-  useEffect(() => {
+  // Try to determine the requested path
-    const errorUrl = typeof window !== 'undefined' ? window.location.pathname : 'unknown';
+  const headersList = await headers();
-    trackEvent(AnalyticsEvents.ERROR, {
+  const urlPath = headersList.get('x-invoke-path') || '';
-      type: '404_not_found',
-      path: errorUrl,
-    });
 
-    // Explicitly send the 404 to Sentry so we have visibility into broken links
+  let suggestedUrl = null;
-    import('@sentry/nextjs').then((Sentry) => {
+  let suggestedLang = null;
-      Sentry.withScope((scope) => {
+
-        scope.setTag('status_code', '404');
+  // If we have a path, try to see if the last segment (slug) exists in ANY locale
-        scope.setTag('path', errorUrl);
+  if (urlPath) {
-        Sentry.captureMessage(`Route Not Found: ${errorUrl}`, 'warning');
+    const slug = urlPath.split('/').filter(Boolean).pop();
-      });
+    if (slug) {
-    });
+      try {
-  }, [trackEvent]);
+        const payload = await getPayload({ config: configPromise });
+
+        // Check posts
+        const postRes = await payload.find({
+          collection: 'posts',
+          where: { slug: { equals: slug } },
+          locale: 'all',
+          limit: 1,
+        });
+
+        // Check products
+        const productRes =
+          postRes.docs.length === 0
+            ? await payload.find({
+                collection: 'products',
+                where: { slug: { equals: slug } },
+                locale: 'all',
+                limit: 1,
+              })
+            : { docs: [] };
+
+        // Check pages
+        const pageRes =
+          postRes.docs.length === 0 && productRes.docs.length === 0
+            ? await payload.find({
+                collection: 'pages',
+                where: { slug: { equals: slug } },
+                locale: 'all',
+                limit: 1,
+              })
+            : { docs: [] };
+
+        const anyDoc = postRes.docs[0] || productRes.docs[0] || pageRes.docs[0];
+
+        if (anyDoc) {
+          // If the doc exists, we can figure out its native locale or
+          // offer the alternative locale (if we are in 'de', offer 'en')
+          const currentLocale = urlPath.startsWith('/en') ? 'en' : 'de';
+          const alternativeLocale = currentLocale === 'de' ? 'en' : 'de';
+
+          suggestedLang = alternativeLocale === 'de' ? 'Deutsch' : 'English';
+
+          // Reconstruct the URL for the alternative locale
+          const pathParts = urlPath.split('/').filter(Boolean);
+          if (pathParts.length > 0 && (pathParts[0] === 'en' || pathParts[0] === 'de')) {
+            pathParts[0] = alternativeLocale;
+          } else {
+            pathParts.unshift(alternativeLocale);
+          }
+          suggestedUrl = '/' + pathParts.join('/');
+        }
+      } catch (e) {
+        // Ignore Payload errors in 404
+      }
+    }
+  }
 
   return (
-    <Container className="relative py-24 flex flex-col items-center justify-center text-center min-h-[70vh] overflow-hidden">
+    <>
-      {/* Industrial Background Element */}
+      <ClientNotFoundTracker path={urlPath} />
-      <div className="absolute inset-0 -z-10 opacity-[0.03] pointer-events-none flex items-center justify-center">
+      <Container className="relative py-24 flex flex-col items-center justify-center text-center min-h-[70vh] overflow-hidden">
-        <span className="text-[20rem] font-bold select-none">404</span>
+        {/* Industrial Background Element */}
-      </div>
+        <div className="absolute inset-0 -z-10 opacity-[0.03] pointer-events-none flex items-center justify-center">
+          <span className="text-[20rem] font-bold select-none">404</span>
+        </div>
 
-      <div className="relative mb-8">
+        <div className="relative mb-8">
-        <Heading level={1} className="text-6xl md:text-8xl font-bold mb-2">
+          <Heading level={1} className="text-6xl md:text-8xl font-bold mb-2">
-          404
+            404
+          </Heading>
+          <Scribble
+            variant="circle"
+            className="w-[150%] h-[150%] -top-[25%] -left-[25%] text-accent/40"
+          />
+        </div>
+
+        <Heading level={2} className="text-2xl md:text-3xl font-bold mb-4 text-primary">
+          {t('title')}
         </Heading>
-        <Scribble
-          variant="circle"
-          className="w-[150%] h-[150%] -top-[25%] -left-[25%] text-accent/40"
-        />
-      </div>
 
-      <Heading level={2} className="text-2xl md:text-3xl font-bold mb-4 text-primary">
+        <p className="text-text-secondary mb-10 max-w-md text-lg">{t('description')}</p>
-        {t('title')}
-      </Heading>
 
-      <p className="text-white/60 mb-10 max-w-md text-lg">{t('description')}</p>
+        {suggestedUrl && (
+          <div className="mb-12 p-6 bg-accent/10 border border-accent/20 rounded-2xl animate-fade-in shadow-lg relative overflow-hidden group">
+            <div className="absolute inset-0 bg-accent/5 -skew-x-12 translate-x-full group-hover:translate-x-0 transition-transform duration-700" />
+            <div className="relative z-10">
+              <h3 className="text-primary font-bold mb-2 text-lg">
+                Did you mean to visit the {suggestedLang} version?
+              </h3>
+              <p className="text-text-secondary text-sm mb-4">
+                This page exists, but in another language.
+              </p>
+              <Button href={suggestedUrl} variant="accent" size="md" className="w-full sm:w-auto">
+                Go to {suggestedLang} Version
+              </Button>
+            </div>
+          </div>
+        )}
 
-      <div className="flex flex-col sm:flex-row gap-4">
+        <div className="flex flex-col sm:flex-row gap-4">
-        <Button href="/" variant="accent" size="lg">
+          <Button href="/" variant={suggestedUrl ? 'outline' : 'accent'} size="lg">
-          {t('cta')}
+            {t('cta')}
-        </Button>
+          </Button>
-        <Button href="/contact" variant="outline" size="lg">
+          <Button href="/contact" variant={suggestedUrl ? 'ghost' : 'outline'} size="lg">
-          Contact Support
+            Contact Support
-        </Button>
+          </Button>
-      </div>
+        </div>
 
-      {/* Decorative Industrial Line */}
+        {/* Decorative Industrial Line */}
-      <div className="absolute bottom-0 left-1/2 -translate-x-1/2 w-px h-24 bg-gradient-to-t from-accent/50 to-transparent" />
+        <div className="absolute bottom-0 left-1/2 -translate-x-1/2 w-px h-24 bg-gradient-to-t from-accent/50 to-transparent" />
-    </Container>
+      </Container>
+    </>
   );
 }

app/[locale]/products/[...slug]/page.tsx

@@ -14,7 +14,7 @@ import { getTranslations, setRequestLocale } from 'next-intl/server';
 import { getProductOGImageMetadata } from '@/lib/metadata';
 import Image from 'next/image';
 import Link from 'next/link';
-import { notFound } from 'next/navigation';
+import { notFound, redirect } from 'next/navigation';
 import ProductEngagementTracker from '@/components/analytics/ProductEngagementTracker';
 import PayloadRichText from '@/components/PayloadRichText';
 
@@ -53,7 +53,7 @@ export async function generateMetadata({ params }: ProductPageProps): Promise<Me
       title: categoryTitle,
       description: categoryDesc,
       alternates: {
-        canonical: `${SITE_URL}/${locale}/${await mapFileSlugToTranslated('products', locale)}/${productSlug}`,
+        canonical: `${SITE_URL}/${locale}/${await mapFileSlugToTranslated('products', locale)}/${await mapFileSlugToTranslated(fileSlug, locale)}`,
         languages: {
           de: `${SITE_URL}/de/${await mapFileSlugToTranslated('products', 'de')}/${await mapFileSlugToTranslated(fileSlug, 'de')}`,
           en: `${SITE_URL}/en/${await mapFileSlugToTranslated('products', 'en')}/${await mapFileSlugToTranslated(fileSlug, 'en')}`,
@@ -75,11 +75,13 @@ export async function generateMetadata({ params }: ProductPageProps): Promise<Me
   const product = await getProductBySlug(productSlug, locale);
   if (!product) return {};
 
+  const currentLocalePath = await getLocalizedPath(locale);
+
   return {
     title: product.frontmatter.title,
     description: product.frontmatter.description,
     alternates: {
-      canonical: `${SITE_URL}/${locale}/${await mapFileSlugToTranslated('products', locale)}/${slug.join('/')}`,
+      canonical: `${SITE_URL}/${locale}/${currentLocalePath}`,
       languages: {
         de: `${SITE_URL}/de/${await getLocalizedPath('de')}`,
         en: `${SITE_URL}/en/${await getLocalizedPath('en')}`,
@@ -90,7 +92,7 @@ export async function generateMetadata({ params }: ProductPageProps): Promise<Me
       title: product.frontmatter.title,
       description: product.frontmatter.description,
       type: 'website',
-      url: `${SITE_URL}/${locale}/products/${slug.join('/')}`,
+      url: `${SITE_URL}/${locale}/${currentLocalePath}`,
       images: getProductOGImageMetadata(productSlug, product.frontmatter.title, locale),
     },
     twitter: {
@@ -114,7 +116,19 @@ export default async function ProductPage({ params }: ProductPageProps) {
     'high-voltage-cables',
     'solar-cables',
   ];
-  const fileSlug = await mapSlugToFileSlug(productSlug, locale);
+
+  const fileSlugs = await Promise.all(slug.map((s) => mapSlugToFileSlug(s, locale)));
+  const translatedSlugsForLocale = await Promise.all(
+    fileSlugs.map((fs) => mapFileSlugToTranslated(fs, locale)),
+  );
+
+  // If the requested slugs don't exactly match the translated slugs for the current locale
+  // (i.e. if the user used the static language switcher but kept the original locale's slugs)
+  if (slug.join('/') !== translatedSlugsForLocale.join('/')) {
+    redirect(`/${locale}/${productsSlug}/${translatedSlugsForLocale.join('/')}`);
+  }
+
+  const fileSlug = fileSlugs[fileSlugs.length - 1];
 
   if (categories.includes(fileSlug)) {
     const allProducts = await getAllProducts(locale);

components/analytics/ClientNotFoundTracker.tsx

@@ -0,0 +1,26 @@
+'use client';
+
+import { useEffect } from 'react';
+import { useAnalytics } from './useAnalytics';
+import { AnalyticsEvents } from './analytics-events';
+
+export default function ClientNotFoundTracker({ path }: { path: string }) {
+  const { trackEvent } = useAnalytics();
+
+  useEffect(() => {
+    trackEvent(AnalyticsEvents.ERROR, {
+      type: '404_not_found',
+      path,
+    });
+
+    import('@sentry/nextjs').then((Sentry) => {
+      Sentry.withScope((scope) => {
+        scope.setTag('status_code', '404');
+        scope.setTag('path', path);
+        Sentry.captureMessage(`Route Not Found: ${path}`, 'warning');
+      });
+    });
+  }, [trackEvent, path]);
+
+  return null;
+}

lib/blog.ts

@@ -59,7 +59,8 @@ export async function getPostBySlug(slug: string, locale: string): Promise<PostD
   try {
     const payload = await getPayload({ config: configPromise });
 
-    const { docs } = await payload.find({
+    // First try: Find in the requested locale
+    let { docs } = await payload.find({
       collection: 'posts',
       where: {
         slug: { equals: slug },
@@ -70,6 +71,38 @@ export async function getPostBySlug(slug: string, locale: string): Promise<PostD
       limit: 1,
     });
 
+    // Fallback: If not found, try searching across all locales.
+    // This happens when a user uses the static language switcher
+    // e.g. switching from /en/blog/en-slug to /de/blog/en-slug.
+    if (!docs || docs.length === 0) {
+      const { docs: crossLocaleDocs } = await payload.find({
+        collection: 'posts',
+        where: {
+          slug: { equals: slug },
+          ...(!config.showDrafts ? { _status: { equals: 'published' } } : {}),
+        },
+        locale: 'all',
+        draft: config.showDrafts,
+        limit: 1,
+      });
+
+      if (crossLocaleDocs && crossLocaleDocs.length > 0) {
+        // Fetch the found document again, but strictly in the requested locale
+        // so we get the correctly translated fields (like the localized slug)
+        const { docs: correctLocaleDocs } = await payload.find({
+          collection: 'posts',
+          where: {
+            id: { equals: crossLocaleDocs[0].id },
+          },
+          locale: locale as any,
+          draft: config.showDrafts,
+          limit: 1,
+        });
+
+        docs = correctLocaleDocs;
+      }
+    }
+
     if (!docs || docs.length === 0) return null;
 
     const doc = docs[0];

lib/pages.ts

@@ -1,5 +1,7 @@
 import { getPayload } from 'payload';
 import configPromise from '@payload-config';
+import { mapSlugToFileSlug } from './slugs';
+import { config } from '@/lib/config';
 
 export interface PageFrontmatter {
   title: string;
@@ -44,19 +46,81 @@ function mapDoc(doc: any): PageData {
 export async function getPageBySlug(slug: string, locale: string): Promise<PageData | null> {
   try {
     const payload = await getPayload({ config: configPromise });
+    const fileSlug = await mapSlugToFileSlug(slug, locale);
 
-    const result = await payload.find({
+    // Try finding exact match first
-      collection: 'pages' as any,
+    let result = await payload.find({
+      collection: 'pages',
       where: {
-        slug: { equals: slug },
+        and: [
+          { slug: { equals: fileSlug } },
+          ...(!config.showDrafts ? [{ _status: { equals: 'published' } }] : []),
+        ],
       },
       locale: locale as any,
+      depth: 1,
       limit: 1,
     });
 
-    const docs = result.docs as any[];
+    // Fallback: search ALL locales
-    if (!docs || docs.length === 0) return null;
+    if (result.docs.length === 0) {
-    return mapDoc(docs[0]);
+      const crossResult = await payload.find({
+        collection: 'pages',
+        where: {
+          and: [
+            { slug: { equals: fileSlug } },
+            ...(!config.showDrafts ? [{ _status: { equals: 'published' } }] : []),
+          ],
+        },
+        locale: 'all',
+        depth: 1,
+        limit: 1,
+      });
+
+      if (crossResult.docs.length > 0) {
+        // Fetch missing exact match by internal id
+        result = await payload.find({
+          collection: 'pages',
+          where: {
+            id: { equals: crossResult.docs[0].id },
+          },
+          locale: locale as any,
+          depth: 1,
+          limit: 1,
+        });
+      }
+    }
+
+    if (result.docs.length > 0) {
+      const doc = result.docs[0];
+
+      return {
+        slug: doc.slug,
+        frontmatter: {
+          title: doc.title,
+          excerpt: doc.excerpt || '',
+          featuredImage:
+            typeof doc.featuredImage === 'object' && doc.featuredImage !== null
+              ? doc.featuredImage.sizes?.card?.url || doc.featuredImage.url
+              : null,
+          focalX:
+            typeof doc.featuredImage === 'object' && doc.featuredImage !== null
+              ? doc.featuredImage.focalX
+              : 50,
+          focalY:
+            typeof doc.featuredImage === 'object' && doc.featuredImage !== null
+              ? doc.featuredImage.focalY
+              : 50,
+          layout:
+            doc.layout === 'fullBleed' || doc.layout === 'default'
+              ? doc.layout
+              : ('default' as const),
+        },
+        content: doc.content,
+      };
+    }
+
+    return null;
   } catch (error) {
     console.error(`[Payload] getPageBySlug failed for ${slug}:`, error);
     return null;