Fix code block state tracking for embedded fence markers

Track the indentation level of opening code fences and only treat  appears inside code blocks (e.g., in Python strings containing markdown examples).

Author: cursoragent

app/api/markdown/[[...slug]]/route.ts

@@ -179,26 +179,43 @@ function extractFrontmatterMeta(frontmatter: string): {
 function normalizeIndentation(text: string): string {
   const finalLines: string[] = [];
   let inCodeBlock = false;
+  let fenceIndent = 0; // Track indentation level of opening fence
 
   for (const line of text.split("\n")) {
-    if (line.trim().startsWith("```")) {
-      inCodeBlock = !inCodeBlock;
-      finalLines.push(line.trimStart()); // Code block markers should start at column 0
+    const trimmed = line.trim();
+    const leadingSpaces = line.length - trimmed.length;
+
+    if (trimmed.startsWith("```")) {
+      if (!inCodeBlock) {
+        // Opening fence - track its indentation
+        inCodeBlock = true;
+        fenceIndent = leadingSpaces;
+        finalLines.push(line.trimStart()); // Code block markers should start at column 0
+      } else if (leadingSpaces <= fenceIndent) {
+        // Closing fence - only if not indented more than opening fence
+        inCodeBlock = false;
+        fenceIndent = 0;
+        finalLines.push(line.trimStart());
+      } else {
+        // ``` inside code block (indented more than opening fence)
+        finalLines.push(line); // Preserve as code block content
+      }
     } else if (inCodeBlock) {
       finalLines.push(line); // Preserve indentation inside code blocks
     } else {
-      const trimmed = line.trimStart();
+      const trimmedLine = line.trimStart();
       // Preserve indentation for nested list items and blockquotes
       const isListItem =
-        UNORDERED_LIST_REGEX.test(trimmed) || ORDERED_LIST_REGEX.test(trimmed);
-      const isBlockquote = trimmed.startsWith(">");
+        UNORDERED_LIST_REGEX.test(trimmedLine) ||
+        ORDERED_LIST_REGEX.test(trimmedLine);
+      const isBlockquote = trimmedLine.startsWith(">");
       if ((isListItem || isBlockquote) && line.startsWith("  ")) {
         // Keep markdown-meaningful indentation (but normalize to 2-space increments)
-        const leadingSpaces = line.length - line.trimStart().length;
-        const normalizedIndent = "  ".repeat(Math.floor(leadingSpaces / 2));
-        finalLines.push(normalizedIndent + trimmed);
+        const leadingSpacesCount = line.length - line.trimStart().length;
+        const normalizedIndent = "  ".repeat(Math.floor(leadingSpacesCount / 2));
+        finalLines.push(normalizedIndent + trimmedLine);
       } else {
-        finalLines.push(trimmed); // Remove leading whitespace for other lines
+        finalLines.push(trimmedLine); // Remove leading whitespace for other lines
       }
     }
   }