markdown: normalize ordered list markers

Author: maxbuchan

frontend/components/design-system-components/MessageMarkdown.tsx

@@ -280,6 +280,25 @@ const markdownComponents: any = {
   }
 } as const
 
+// Normalize ordered list markers so that lines starting with "1) " are
+// converted to the CommonMark style "1. ". This helps react-markdown parse
+// them as ordered lists. We avoid transforming content inside fenced code blocks.
+const normalizeOrderedListMarkers = (markdown: string) => {
+  let inCodeFence = false
+  const fenceRegex = /^\s*```/
+  return markdown
+    .split('\n')
+    .map(line => {
+      if (fenceRegex.test(line)) {
+        inCodeFence = !inCodeFence
+        return line
+      }
+      if (inCodeFence) return line
+      return line.replace(/^(\s*)(\d+)\)\s+/, '$1$2. ')
+    })
+    .join('\n')
+}
+
 const MessageMarkdown = ({
   children,
   className,
@@ -291,6 +310,7 @@ const MessageMarkdown = ({
   allowHtml?: boolean
   textSize?: MarkdownTextSize
 }) => {
+  const normalizedChildren = normalizeOrderedListMarkers(children)
   return (
     <MarkdownContext.Provider value={textSize}>
       <MemoizedReactMarkdown
@@ -307,7 +327,7 @@ const MessageMarkdown = ({
         }
         components={markdownComponents}
       >
-        {children}
+        {normalizedChildren}
       </MemoizedReactMarkdown>
     </MarkdownContext.Provider>
   )