Core: Support code syntax in headings

.changeset/shy-pigs-push.md

@@ -0,0 +1,5 @@
+---
+'fumadocs-core': patch
+---
+
+Remark Headings: Support code syntax in headings

packages/core/src/mdx-plugins/remark-heading.ts

@@ -3,6 +3,7 @@ import type { Heading, Root } from 'mdast';
 import type { Transformer } from 'unified';
 import { visit } from 'unist-util-visit';
 import type { TOCItemType } from '@/server/get-toc';
+import { flattenNode } from '@/mdx-plugins/remark-utils';
 
 const slugger = new Slugger();
 
@@ -40,33 +41,36 @@ export function remarkHeading({
     slugger.reset();
 
     visit(root, 'heading', (heading) => {
-      const node = heading.children.at(-1);
-      if (!node || node.type !== 'text') return;
-
       heading.data ||= {};
       heading.data.hProperties ||= {};
+      const lastNode = heading.children.at(-1);
 
-      let id = heading.data.hProperties.id;
-
-      if (!id && customId) {
-        const match = regex.exec(node.value);
+      if (
+        !heading.data.hProperties.id &&
+        lastNode?.type === 'text' &&
+        customId
+      ) {
+        const match = regex.exec(lastNode.value);
 
         if (match?.[1]) {
-          id = match[1];
-          node.value = node.value.slice(0, match.index);
+          heading.data.hProperties.id = match[1];
+          lastNode.value = lastNode.value.slice(0, match.index);
         }
       }
 
+      const value = flattenNode(heading);
+
+      let id = heading.data.hProperties.id;
       if (!id) {
         id = defaultSlug
-          ? defaultSlug(root, heading, node.value)
-          : slugger.slug(node.value);
+          ? defaultSlug(root, heading, value)
+          : slugger.slug(value);
       }
 
       heading.data.hProperties.id = id;
 
       toc.push({
-        title: node.value,
+        title: value,
         url: `#${id}`,
         depth: heading.depth,
       });

packages/core/test/fixtures/remark-heading.md

@@ -21,3 +21,7 @@ Some text here
 ### Custom heading id hello-world]
 
 Some text here
+
+### `code` here
+
+hi

packages/core/test/fixtures/remark-heading.output.json

@@ -29,4 +29,9 @@
     "title": "Custom heading id hello-world]",
     "url": "#custom-heading-id-hello-world",
   },
+  {
+    "depth": 3,
+    "title": "code here",
+    "url": "#code-here",
+  },
 ]