a

.changeset/giant-garlics-kiss.md

@@ -0,0 +1,7 @@
+---
+"nextra": patch
+"nextra-theme-blog": patch
+"nextra-theme-docs": patch
+---
+
+fix regression from Nextra 3 setting [`theme.collapsed?: boolean` in `_meta` file](https://nextra.site/docs/file-conventions/meta-file#theme-option) for folders has no effect in sidebar

docs/app/docs/page.mdx

@@ -53,8 +53,8 @@ project. If you have a question that isn't answered here, please
 
 <details>
   <summary className="mb-2">Can I use X with Nextra?</summary>
-  The answer is "yes" for most things. Since Nextra is just a Next.js plugin, almost all the things
-  that can be done with React can be done with Nextra. Here are some examples and guides:
+The answer is "yes" for most things. Since Nextra is just a Next.js plugin, almost all the things
+that can be done with React can be done with Nextra. Here are some examples and guides:
 
 - [Use Tailwind CSS](/docs/guide/tailwind-css)
 - [Use custom CSS and Sass](/docs/guide/custom-css)

packages/nextra/src/client/normalize-pages.ts

@@ -6,7 +6,7 @@ import type { Folder, FrontMatter, MdxFile, PageMapItem } from '../types.js'
 
 const DEFAULT_PAGE_THEME: PageTheme = {
   breadcrumb: true,
-  collapsed: false,
+  collapsed: undefined,
   footer: true,
   layout: 'default',
   navbar: true,
@@ -177,6 +177,13 @@ export function normalizePages({
     })
     const item: Item = getItem()
     const docsItem: DocsItem = getItem()
+    if ('children' in docsItem) {
+      const { collapsed } = extendedMeta.theme
+      if (typeof collapsed === 'boolean') {
+        // @ts-expect-error -- fixme
+        docsItem.theme = { collapsed }
+      }
+    }
     const pageItem: PageItem = getItem()
 
     docsItem.isUnderCurrentDocsTree = underCurrentDocsRoot