diff --git a/desktop/src/components/chat/CodeViewer.tsx b/desktop/src/components/chat/CodeViewer.tsx
index 4af18121..57abd7ed 100644
--- a/desktop/src/components/chat/CodeViewer.tsx
+++ b/desktop/src/components/chat/CodeViewer.tsx
@@ -1,5 +1,5 @@
-import { useMemo, useState } from 'react'
-import hljs from 'highlight.js'
+import { useState } from 'react'
+import { Highlight, themes } from 'prism-react-renderer'
 import { CopyButton } from '../shared/CopyButton'
 
 type Props = {
@@ -12,37 +12,14 @@ type Props = {
 export function CodeViewer({ code, language, maxLines = 20, showLineNumbers = true }: Props) {
   const [expanded, setExpanded] = useState(false)
 
-  const lines = code.split('\n')
-  const isTruncated = !expanded && lines.length > maxLines
-  const visibleCode = isTruncated ? lines.slice(0, maxLines).join('\n') : code
-
-  // Only highlight when language is explicitly known.
-  // Do NOT use highlightAuto — it misdetects plain text as code.
-  const hasLanguage = !!language && !!hljs.getLanguage(language)
-  const effectiveShowLineNumbers = showLineNumbers && hasLanguage
-
-  const highlightedLines = useMemo(() => {
-    return visibleCode.split('\n').map((line) => {
-      try {
-        if (hasLanguage) {
-          return hljs.highlight(line || ' ', { language: language!, ignoreIllegals: true }).value
-        }
-        return escapeHtml(line || ' ')
-      } catch {
-        return escapeHtml(line)
-      }
-    })
-  }, [hasLanguage, language, visibleCode])
-
-  const startLine = 1
+  const allLines = code.split('\n')
+  const isTruncated = !expanded && allLines.length > maxLines
+  const visibleCode = isTruncated ? allLines.slice(0, maxLines).join('\n') : code
 
+  const effectiveShowLineNumbers = showLineNumbers && !!language && language !== 'text'
   const languageLabel = language || 'code'
-
-  const visibleLines = visibleCode.split('\n')
-
-  const lineCountLabel = `${lines.length} ${lines.length === 1 ? 'line' : 'lines'}`
-
-  const showExpandToggle = lines.length > maxLines
+  const lineCountLabel = `${allLines.length} ${allLines.length === 1 ? 'line' : 'lines'}`
+  const showExpandToggle = allLines.length > maxLines
 
   return (
     <div className="overflow-hidden rounded-lg border border-[#d0d7de] bg-[#f6f8fa] text-[#24292f]">
@@ -58,34 +35,45 @@ export function CodeViewer({ code, language, maxLines = 20, showLineNumbers = tr
       </div>
 
       <div className="max-h-[420px] overflow-auto">
-        <div className="min-w-full font-[var(--font-mono)] text-[12px] leading-[1.3]">
-          {visibleLines.map((line, index) => (
-            effectiveShowLineNumbers ? (
-              <div
-                key={`${startLine + index}-${line}`}
-                className="grid grid-cols-[3rem,minmax(0,1fr)] gap-0 hover:bg-[#f6f8fa]/50"
-              >
-                <span className="select-none border-r border-[#eaeef2] bg-[#fafbfc] px-2 py-px text-right text-[11px] text-[#8b949e]">
-                  {startLine + index}
-                </span>
-                <span
-                  className="overflow-hidden bg-white px-3 py-px whitespace-pre-wrap break-words text-[#24292f]"
-                  dangerouslySetInnerHTML={{ __html: highlightedLines[index] ?? escapeHtml(line) }}
-                />
-              </div>
-            ) : (
-              <div
-                key={`${startLine + index}-${line}`}
-                className="hover:bg-[#f6f8fa]/50"
-              >
-                <span
-                  className="block bg-white px-3 py-px whitespace-pre-wrap break-words text-[#24292f]"
-                  dangerouslySetInnerHTML={{ __html: highlightedLines[index] ?? escapeHtml(line) }}
-                />
-              </div>
-            )
-          ))}
-        </div>
+        <Highlight theme={themes.github} code={visibleCode} language={language || 'text'}>
+          {({ tokens, getLineProps, getTokenProps }) => (
+            <pre className="m-0 bg-white p-0 font-[var(--font-mono)] text-[12px] leading-[1.3]">
+              {tokens.map((line, i) => {
+                const lineProps = getLineProps({ line })
+                return effectiveShowLineNumbers ? (
+                  <div
+                    key={i}
+                    {...lineProps}
+                    className="grid grid-cols-[3rem,minmax(0,1fr)] gap-0 hover:bg-[#f6f8fa]/50"
+                    style={undefined}
+                  >
+                    <span className="select-none border-r border-[#eaeef2] bg-[#fafbfc] px-2 py-px text-right text-[11px] text-[#8b949e]">
+                      {i + 1}
+                    </span>
+                    <span className="overflow-hidden px-3 py-px whitespace-pre-wrap break-words">
+                      {line.map((token, key) => (
+                        <span key={key} {...getTokenProps({ token })} />
+                      ))}
+                    </span>
+                  </div>
+                ) : (
+                  <div
+                    key={i}
+                    {...lineProps}
+                    className="hover:bg-[#f6f8fa]/50"
+                    style={undefined}
+                  >
+                    <span className="block px-3 py-px whitespace-pre-wrap break-words">
+                      {line.map((token, key) => (
+                        <span key={key} {...getTokenProps({ token })} />
+                      ))}
+                    </span>
+                  </div>
+                )
+              })}
+            </pre>
+          )}
+        </Highlight>
       </div>
 
       {showExpandToggle && (
@@ -93,17 +81,9 @@ export function CodeViewer({ code, language, maxLines = 20, showLineNumbers = tr
           onClick={() => setExpanded((value) => !value)}
           className="w-full border-t border-[#d0d7de] bg-[#f6f8fa] py-1.5 text-[10px] font-semibold uppercase tracking-[0.14em] text-[#57606a] transition-colors hover:bg-[#eaeef2] hover:text-[#24292f]"
         >
-          {expanded ? 'Collapse' : `Show ${lines.length - maxLines} more lines`}
+          {expanded ? 'Collapse' : `Show ${allLines.length - maxLines} more lines`}
         </button>
       )}
     </div>
   )
 }
-
-function escapeHtml(str: string): string {
-  return str
-    .replace(/&/g, '&amp;')
-    .replace(/</g, '&lt;')
-    .replace(/>/g, '&gt;')
-    .replace(/"/g, '&quot;')
-}