fix(createNested): add clear() method for proper state reset

- Add clear() that resets children, parents, openedIds, and group state
- Preserve open state across nav rebuilds in useNavNested
- Fix duplicate divider when combining skill and feature filters

Author: johnleider

apps/docs/src/components/app/AppNav.vue

@@ -60,6 +60,11 @@
     if (hasPage(configuredNav.value, path)) return null
     return findPage(app.nav, path)
   })
+
+  // Check if nav has real content (not just dividers)
+  const hasNavContent = computed(() =>
+    configuredNav.value.some(item => !('divider' in item)),
+  )
   const navRef = useTemplateRef<AtomExpose>('nav')
 
   // Match Tailwind's md breakpoint (768px) for nav visibility
@@ -180,7 +185,8 @@
       </template>
 
       <template v-if="selectedLevels.size > 0">
-        <li class="px-4">
+        <!-- Skip divider if Active page section already added one and nav has no real content -->
+        <li v-if="!filteredOutPage || hasNavContent" class="px-4">
           <AppDivider />
         </li>
 

apps/docs/src/composables/useNavNested.ts

@@ -89,9 +89,15 @@ export function createNavNested (nav: MaybeRefOrGetter<NavItem[]>) {
   const scrollEnabled = shallowRef(false)
 
   // SSR-safe: Build tree structure on server and client
+  // Preserve open state across nav changes (e.g., filtering)
   watch(() => toValue(nav), items => {
+    const savedOpenIds = [...nested.openedIds]
     nested.clear()
     nested.onboard(navToNestedItems(items))
+    // Restore any open IDs that still exist in the new tree
+    if (savedOpenIds.length > 0) {
+      nested.open(savedOpenIds.filter(id => nested.has(id)))
+    }
   }, { immediate: true })
 
   // Top-level sections to open on first visit

packages/0/src/composables/createNested/index.ts

@@ -588,13 +588,17 @@ export function createNested<
     return registrations.map(registration => register(registration))
   }
 
-  function reset (): void {
+  function clear (): void {
     children.clear()
     parents.clear()
     openedIds.clear()
     group.reset()
   }
 
+  function reset (): void {
+    clear()
+  }
+
   const context = {
     ...group,
     children: children as ReadonlyMap<ID, readonly ID[]>,
@@ -630,6 +634,7 @@ export function createNested<
     unregister,
     offboard,
     onboard,
+    clear,
     reset,
     get size () {
       return group.size

packages/0/src/composables/createNested/types.ts

@@ -164,6 +164,8 @@ export interface NestedContext<Z extends NestedTicket> extends Omit<GroupContext
   unregister: (id: ID, cascade?: boolean) => void
   /** Offboard multiple nodes, optionally cascading */
   offboard: (ids: ID[], cascade?: boolean) => void
+  /** Clear all nodes and nested state (children, parents, openedIds) */
+  clear: () => void
 }
 
 /**