fix: preserve list ordering

Author: zirkelc

src/splitter.test.ts

@@ -436,6 +436,32 @@ End of list.`;
       expect(chunks[4]).toBe('End of list.');
     });
 
+    it('should preserve ordered list numbering when splitting', () => {
+      const splitter = chunkdown({
+        chunkSize: 50,
+        maxOverflowRatio: 1.0,
+      });
+      const text = `Instructions:
+
+1. First step with some content
+2. Second step with some content
+3. Third step with some content
+4. Fourth step with some content
+5. Fifth step with some content
+6. Sixth step with some content
+
+End of instructions.`;
+      const chunks = splitter.splitText(text);
+
+      // Find the chunks containing ordered list items
+      const listChunks = chunks.filter((chunk) => /^\d+\./.test(chunk.trim()));
+
+      expect(listChunks.length).toBe(6);
+      for (let i = 1; i < listChunks.length; i++) {
+        expect(listChunks[i]).toMatch(new RegExp(`^[${i + 1}]\.`));
+      }
+    });
+
     it('should keep tables together if possible', () => {
       const splitter = chunkdown({
         chunkSize: 50,
@@ -1077,7 +1103,7 @@ Here's a sentence with a footnote[^1].
              // Code block in list item
              const example = true;
              \`\`\`",
-            "1. Third item with blockquote:
+            "3. Third item with blockquote:
              > This is a blockquote inside a list item
              > with multiple lines",
             "### Table with Complex Content

src/splitter.ts

@@ -1,4 +1,12 @@
-import type { Blockquote, List, Node, Root, RootContent, Table } from 'mdast';
+import type {
+  Blockquote,
+  List,
+  ListItem,
+  Node,
+  Root,
+  RootContent,
+  Table,
+} from 'mdast';
 import {
   createHierarchicalAST,
   flattenHierarchicalAST,
@@ -417,10 +425,21 @@ export const chunkdown = (options: ChunkdownOptions) => {
     // Helper to flush accumulated items
     const flushCurrentItems = () => {
       if (currentItems.length > 0) {
-        const containerMarkdown = toMarkdown({
+        const currentContainer = {
           ...container,
           children: currentItems,
-        } as TContainer);
+        };
+
+        // For ordered lists, calculate the correct start number
+        if (container.type === 'list' && container.ordered) {
+          const originalStart = container.start || 1;
+          const firstItemIndex = container.children.indexOf(
+            currentItems[0] as ListItem,
+          );
+          (currentContainer as List).start = originalStart + firstItemIndex;
+        }
+
+        const containerMarkdown = toMarkdown(currentContainer);
         chunks.push(containerMarkdown.trim());
         currentItems = [];
         currentSize = 0;

www/src/components/ASTVisualizer.tsx

@@ -67,13 +67,21 @@ function TreeNode({
     }
   }, [collapseAll, depth]);
 
+  const extractTextFromNode = (node: Node): string => {
+    if ('value' in node && typeof node.value === 'string') {
+      return node.value;
+    }
+    if ('children' in node && Array.isArray(node.children)) {
+      return node.children.map(extractTextFromNode).join('');
+    }
+    return '';
+  };
+
   const getNodeLabel = () => {
     if (isSection(node)) {
       // Handle Section node
       const headingText =
-        node.heading?.children
-          ?.map((child) => ('value' in child ? child.value : ''))
-          .join('') || '';
+        node.heading?.children?.map(extractTextFromNode).join('') || '';
       const truncated =
         headingText.length > 40
           ? `${headingText.substring(0, 40)}...`