u

src/nav.js

@@ -20,15 +20,6 @@ export const NAV_ITEMS = [
   { path: '/infos', label: 'Infos', icon: InfoIcon },
 ];
 
-export function isNavItemActive(pathname, navPath) {
-  if (navPath === '/artikel') {
-    return pathname === navPath
-      || pathname.startsWith(`${navPath}/`)
-      || isKategorienPath(pathname);
-  }
-  return pathname === navPath || pathname.startsWith(`${navPath}/`);
-}
-
 export const SUB_NAV = {
   '/artikel': [
     { segment: '', icon: ViewListIcon },
@@ -45,3 +36,49 @@ export const SUB_NAV = {
     { segment: 'kontakte', label: 'Kontakte', icon: ContactPageIcon },
   ],
 };
+
+export function isNavItemActive(pathname, navPath) {
+  if (navPath === '/artikel') {
+    return (
+      pathname === navPath ||
+      pathname.startsWith(`${navPath}/`) ||
+      isKategorienPath(pathname)
+    );
+  }
+  return pathname === navPath || pathname.startsWith(`${navPath}/`);
+}
+
+/** Stable across article tab changes (e.g. always `/artikel`). */
+export function resolveActiveNav(pathname) {
+  for (const item of NAV_ITEMS) {
+    if (isNavItemActive(pathname, item.path)) return item.path;
+  }
+  return null;
+}
+
+/**
+ * Active sub-nav segment for a section.
+ * `''` = section index, `null` = none (e.g. article detail tabs).
+ */
+export function resolveActiveSub(pathname, sectionPath) {
+  const subNav = SUB_NAV[sectionPath];
+  if (!subNav) return null;
+
+  const knownSegments = new Set(subNav.map((item) => item.segment).filter(Boolean));
+  const rest = pathname.slice(sectionPath.length).replace(/^\//, '').split('/')[0];
+  const isArticleDetail =
+    sectionPath === '/artikel' &&
+    !isKategorienPath(pathname) &&
+    rest &&
+    !knownSegments.has(rest);
+  if (isArticleDetail) return null;
+
+  const active = subNav.find((item) => {
+    if (item.segment === 'kategorien') {
+      return isKategorienPath(pathname);
+    }
+    const subPath = item.segment ? `${sectionPath}/${item.segment}` : sectionPath;
+    return pathname === subPath || pathname === `${subPath}/`;
+  });
+  return active ? active.segment : null;
+}