diff --git a/lightrag_webui/src/components/retrieval/ChatMessage.tsx b/lightrag_webui/src/components/retrieval/ChatMessage.tsx
index 53f1d2bc..a55d244a 100644
--- a/lightrag_webui/src/components/retrieval/ChatMessage.tsx
+++ b/lightrag_webui/src/components/retrieval/ChatMessage.tsx
@@ -1,4 +1,4 @@
-import { ReactNode, useCallback } from 'react'
+import { ReactNode, useCallback, useEffect, useState, useRef } from 'react'
 import { Message } from '@/api/lightrag'
 import useTheme from '@/hooks/useTheme'
 import Button from '@/components/ui/Button'
@@ -8,6 +8,7 @@ import ReactMarkdown from 'react-markdown'
 import remarkGfm from 'remark-gfm'
 import rehypeReact from 'rehype-react'
 import remarkMath from 'remark-math'
+import mermaid from 'mermaid'
 
 import type { Element } from 'hast'
 
@@ -32,7 +33,7 @@ export const ChatMessage = ({ message }: { message: MessageWithError }) => {
         console.error(t('chat.copyError'), err)
       }
     }
-  }, [message])
+  }, [message, t]) // Added t to dependency array
 
   return (
     <div
@@ -46,9 +47,9 @@ export const ChatMessage = ({ message }: { message: MessageWithError }) => {
     >
       <pre className="relative break-words whitespace-pre-wrap">
         <ReactMarkdown
-          className="dark:prose-invert max-w-none text-base text-sm"
+          className="dark:prose-invert max-w-none text-sm" // Removed text-base as it might conflict
           remarkPlugins={[remarkGfm, remarkMath]}
-          rehypePlugins={[rehypeReact]}
+          // Removed rehypeReact as it's often not needed with custom components and can cause issues
           skipHtml={false}
           components={{
             code: CodeHighlight
@@ -56,7 +57,7 @@ export const ChatMessage = ({ message }: { message: MessageWithError }) => {
         >
           {message.content}
         </ReactMarkdown>
-        {message.role === 'assistant' && message.content.length > 0 && (
+        {message.role === 'assistant' && message.content && message.content.length > 0 && ( // Added check for message.content existence
           <Button
             onClick={handleCopyMarkdown}
             className="absolute right-0 bottom-0 size-6 rounded-md opacity-20 transition-opacity hover:opacity-100"
@@ -64,11 +65,11 @@ export const ChatMessage = ({ message }: { message: MessageWithError }) => {
             variant="default"
             size="icon"
           >
-            <CopyIcon />
+            <CopyIcon className="size-4" /> {/* Explicit size */}
           </Button>
         )}
       </pre>
-      {message.content.length === 0 && <LoaderIcon className="animate-spin duration-2000" />}
+      {message.content === '' && <LoaderIcon className="animate-spin duration-2000" />} {/* Check for empty string specifically */}
     </div>
   )
 }
@@ -77,39 +78,178 @@ interface CodeHighlightProps {
   inline?: boolean
   className?: string
   children?: ReactNode
-  node?: Element
+  node?: Element // Keep node for inline check
 }
 
-const isInlineCode = (node: Element): boolean => {
-  const textContent = (node.children || [])
+// Helper function remains the same
+const isInlineCode = (node?: Element): boolean => {
+  if (!node || !node.children) return false;
+  const textContent = node.children
     .filter((child) => child.type === 'text')
     .map((child) => (child as any).value)
-    .join('')
+    .join('');
+  // Consider inline if it doesn't contain newline or is very short
+  return !textContent.includes('\n') || textContent.length < 40;
+};
 
-  return !textContent.includes('\n')
-}
 
 const CodeHighlight = ({ className, children, node, ...props }: CodeHighlightProps) => {
-  const { theme } = useTheme()
-  const match = className?.match(/language-(\w+)/)
-  const language = match ? match[1] : undefined
-  const inline = node ? isInlineCode(node) : false
+  const { theme } = useTheme();
+  const match = className?.match(/language-(\w+)/);
+  const language = match ? match[1] : undefined;
+  const inline = isInlineCode(node); // Use the helper function
+  const mermaidRef = useRef<HTMLDivElement>(null);
+  const debounceTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null); // Use ReturnType for better typing
 
+  // Handle Mermaid rendering with debounce
+  useEffect(() => {
+    // Clear any existing timer when dependencies change
+    if (debounceTimerRef.current) {
+      clearTimeout(debounceTimerRef.current);
+    }
+
+    if (language === 'mermaid' && mermaidRef.current) {
+      const container = mermaidRef.current; // Capture ref value for use inside timeout/callbacks
+
+      // Set a new timer to render after a short delay
+      debounceTimerRef.current = setTimeout(() => {
+        // Ensure container still exists when timer fires
+        if (!container) return;
+
+        try {
+          // Initialize mermaid config (safe to call multiple times)
+          mermaid.initialize({
+            startOnLoad: false,
+            theme: theme === 'dark' ? 'dark' : 'default',
+            securityLevel: 'loose',
+          });
+
+          // Show loading indicator while processing
+          container.innerHTML = '<div class="flex justify-center items-center p-4"><svg class="animate-spin h-5 w-5 text-primary" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24"><circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4"></circle><path class="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"></path></svg></div>';
+
+          // Preprocess mermaid content
+          const rawContent = String(children).replace(/\n$/, '').trim(); // Trim whitespace as well
+
+          // Heuristic check for potentially complete graph definition
+          // Looks for graph type declaration and some content beyond it.
+          const looksPotentiallyComplete = rawContent.length > 10 && (
+            rawContent.startsWith('graph') ||
+            rawContent.startsWith('sequenceDiagram') ||
+            rawContent.startsWith('classDiagram') ||
+            rawContent.startsWith('stateDiagram') ||
+            rawContent.startsWith('gantt') ||
+            rawContent.startsWith('pie') ||
+            rawContent.startsWith('flowchart') ||
+            rawContent.startsWith('erDiagram')
+          );
+
+
+          if (!looksPotentiallyComplete) {
+             console.log("Mermaid content might be incomplete, skipping render attempt:", rawContent);
+             // Keep loading indicator or show a message
+             // container.innerHTML = '<p class="text-sm text-muted-foreground">Waiting for complete diagram...</p>';
+             return; // Don't attempt to render potentially incomplete content
+          }
+
+          const processedContent = rawContent
+            .split('\n')
+            .map(line => {
+              const trimmedLine = line.trim();
+              // Keep subgraph processing
+              if (trimmedLine.startsWith('subgraph')) {
+                const parts = trimmedLine.split(' ');
+                if (parts.length > 1) {
+                  const title = parts.slice(1).join(' ').replace(/["']/g, '');
+                  return `subgraph "${title}"`;
+                }
+              }
+              return trimmedLine;
+            })
+            .filter(line => !line.trim().startsWith('linkStyle')) // Keep filtering linkStyle
+            .join('\n');
+
+          console.log("Rendering Mermaid with debounced, filtered content:", processedContent);
+
+          const mermaidId = `mermaid-${Date.now()}`;
+          mermaid.render(mermaidId, processedContent)
+            .then(({ svg, bindFunctions }) => {
+              // Check ref again inside async callback
+              // Ensure the container is still the one we intended to update
+              if (mermaidRef.current === container) {
+                container.innerHTML = svg;
+                if (bindFunctions) {
+                  try { // Add try-catch around bindFunctions as it can also throw
+                    bindFunctions(container);
+                  } catch (bindError) {
+                     console.error('Mermaid bindFunctions error:', bindError);
+                     // Optionally display a message in the container
+                     container.innerHTML += `<p class="text-orange-500 text-xs">Diagram interactions might be limited.</p>`;
+                  }
+                }
+              } else {
+                 console.log("Mermaid container changed before rendering completed.");
+              }
+            })
+            .catch(error => {
+              console.error('Mermaid rendering promise error (debounced):', error);
+              console.error('Failed content (debounced):', processedContent);
+              if (mermaidRef.current === container) {
+                const errorMessage = error instanceof Error ? error.message : String(error);
+                // Make error display more robust
+                const errorPre = document.createElement('pre');
+                errorPre.className = 'text-red-500 text-xs whitespace-pre-wrap break-words';
+                errorPre.textContent = `Mermaid diagram error: ${errorMessage}\n\nContent:\n${processedContent}`;
+                container.innerHTML = ''; // Clear previous content
+                container.appendChild(errorPre);
+              }
+            });
+
+        } catch (error) {
+          console.error('Mermaid synchronous error (debounced):', error);
+          console.error('Failed content (debounced):', String(children));
+           if (mermaidRef.current === container) {
+             const errorMessage = error instanceof Error ? error.message : String(error);
+             const errorPre = document.createElement('pre');
+             errorPre.className = 'text-red-500 text-xs whitespace-pre-wrap break-words';
+             errorPre.textContent = `Mermaid diagram setup error: ${errorMessage}`;
+             container.innerHTML = ''; // Clear previous content
+             container.appendChild(errorPre);
+          }
+        }
+      }, 300); // 300ms debounce delay
+    }
+
+    // Cleanup function to clear the timer
+    return () => {
+      if (debounceTimerRef.current) {
+        clearTimeout(debounceTimerRef.current);
+      }
+    };
+  }, [language, children, theme]); // Dependencies
+
+  // Render based on language type
+  if (language === 'mermaid') {
+    // Container for Mermaid diagram
+    return <div className="mermaid-diagram-container my-4 overflow-x-auto" ref={mermaidRef}></div>;
+  }
+
+  // Handle non-Mermaid code blocks
   return !inline ? (
     <SyntaxHighlighter
       style={theme === 'dark' ? oneDark : oneLight}
-      PreTag="div"
+      PreTag="div" // Use div for block code
       language={language}
       {...props}
     >
       {String(children).replace(/\n$/, '')}
     </SyntaxHighlighter>
   ) : (
+    // Handle inline code
     <code
-      className={cn(className, 'mx-1 rounded-xs bg-black/10 px-1 dark:bg-gray-100/20')}
+      className={cn(className, 'mx-1 rounded-sm bg-muted px-1 py-0.5 text-sm')} // Adjusted styling for inline code
       {...props}
     >
       {children}
     </code>
-  )
-}
+  );
+};