diff --git a/frontend/src/components/doc-content.vue b/frontend/src/components/doc-content.vue
index 5057229af..3959af6f8 100644
--- a/frontend/src/components/doc-content.vue
+++ b/frontend/src/components/doc-content.vue
@@ -936,8 +936,10 @@ const processMarkdown = (markdownText) => {
   const safeMarkdown = safeMarkdownToHTML(mathSafeText);
 
   // 使用标记渲染
-  marked.use({ renderer });
-  let html = marked.parse(safeMarkdown) as string;
+  // Do not register this renderer globally. DocumentPreview uses the same
+  // `marked` module; registering here made its later Markdown preview reuse
+  // this image validator after the user had opened the chunk view.
+  let html = marked.parse(safeMarkdown, { renderer }) as string;
 
   // 还原被转义的 <br>
   html = html.replace(/&lt;br\s*\/?&gt;/gi, '<br>');
diff --git a/frontend/src/components/document-preview.vue b/frontend/src/components/document-preview.vue
index 7a15bbc60..f83ef2c0d 100644
--- a/frontend/src/components/document-preview.vue
+++ b/frontend/src/components/document-preview.vue
@@ -239,10 +239,11 @@ async function renderMarkdown(blob: Blob) {
     }
     return `<pre><code class="hljs">${highlighted}</code></pre>`;
   };
-  marked.use({ renderer });
   const mathSafeText = preprocessMathDelimiters(text);
   const safeText = safeMarkdownToHTML(mathSafeText);
-  const rawHtml = marked.parse(safeText) as string;
+  // Keep this renderer local. `marked.use` mutates a shared singleton and
+  // would otherwise inherit renderers installed by the chunk-content view.
+  const rawHtml = marked.parse(safeText, { renderer }) as string;
   markdownHtml.value = sanitizeHTML(rawHtml);
 }