Allow some sidebars to be collapsible, but others not.

packages/docusaurus-theme-classic/src/theme/DocPage/index.js

@@ -41,6 +41,9 @@ function DocPage(props) {
     : permalinkToSidebar[currentRoute.path];
   const {
     siteConfig: {themeConfig: {sidebarCollapsible = true} = {}} = {},
+    siteConfig: {
+      themeConfig: {sidebarCollapsibleOverrides = []},
+    },
     isClient,
   } = useDocusaurusContext();
 
@@ -61,7 +64,11 @@ function DocPage(props) {
               docsSidebars={docsSidebars}
               path={isHomePage ? homePagePath : currentRoute.path}
               sidebar={sidebar}
-              sidebarCollapsible={sidebarCollapsible}
+              sidebarCollapsible={
+                sidebarCollapsibleOverrides.includes(sidebar)
+                  ? !sidebarCollapsible
+                  : sidebarCollapsible
+              }
             />
           </div>
         )}

website/docs/docs.md

@@ -303,6 +303,21 @@ module.exports = {
 };
 ```
 
+#### Overriding themeConfig.sidebarCollapsible on some sidebars
+
+If you have multiple sidebars, and would like to collapse some but not others, you can override the `themeConfig.sidebarCollapsible` behavior on a per-sidebar basis. Set `themeConfig.sidebarCollapsibleOverrides` to a list of names of sidebars that should behave the opposite of what you have `themeConfig.sidebarCollapsible` set to.
+
+```js {5} title="docusaurus.config.js"
+module.exports = {
+  // ...
+  themeConfig: {
+    sidebarCollapsible: false,
+    sidebarCollapsibleOverrides: ['secondSidebar'],
+    // ...
+  },
+};
+```
+
 #### Expanded categories by default
 
 For docs that have collapsible categories, you may want more fine-grain control over certain categories. If you want specific categories to be always expanded, you can set `collapsed` to `false`: