diff --git a/frontend/i18n/messages/en-US/chat.json b/frontend/i18n/messages/en-US/chat.json
index b332728f..a10d19a2 100644
--- a/frontend/i18n/messages/en-US/chat.json
+++ b/frontend/i18n/messages/en-US/chat.json
@@ -155,6 +155,12 @@
     "thinking": {
       "active": "Thinking",
       "done": "Thinking complete"
+    },
+    "diagram": {
+      "downloadDiagram": "Download diagram",
+      "downloadDiagramAsSvg": "Download diagram as SVG",
+      "downloadDiagramAsPng": "Download diagram as PNG",
+      "downloadDiagramAsMmd": "Download diagram as MMD"
     }
   },
   "artifacts": {
diff --git a/frontend/i18n/messages/zh-CN/chat.json b/frontend/i18n/messages/zh-CN/chat.json
index c03014bf..5bc349b0 100644
--- a/frontend/i18n/messages/zh-CN/chat.json
+++ b/frontend/i18n/messages/zh-CN/chat.json
@@ -155,6 +155,12 @@
     "thinking": {
       "active": "正在思考",
       "done": "思考完成"
+    },
+    "diagram": {
+      "downloadDiagram": "下载图表",
+      "downloadDiagramAsSvg": "导出为 SVG",
+      "downloadDiagramAsPng": "导出为 PNG",
+      "downloadDiagramAsMmd": "导出为 MMD 源码"
     }
   },
   "artifacts": {
diff --git a/frontend/shared/components/markdown/streamdown-render.tsx b/frontend/shared/components/markdown/streamdown-render.tsx
index eba79b3b..2df55d73 100644
--- a/frontend/shared/components/markdown/streamdown-render.tsx
+++ b/frontend/shared/components/markdown/streamdown-render.tsx
@@ -104,13 +104,26 @@ const STREAMDOWN_CONTROLS = {
   },
   mermaid: {
     copy: true,
-    download: false,
+    download: true,
     fullscreen: true,
     panZoom: true,
   },
   table: false,
 } as const;
 
+function useStreamdownTranslations() {
+  const t = useTranslations("chat.markdown.diagram");
+  return React.useMemo(
+    () => ({
+      downloadDiagram: t("downloadDiagram"),
+      downloadDiagramAsSvg: t("downloadDiagramAsSvg"),
+      downloadDiagramAsPng: t("downloadDiagramAsPng"),
+      downloadDiagramAsMmd: t("downloadDiagramAsMmd"),
+    }),
+    [t],
+  );
+}
+
 const STREAMDOWN_REMEND = {
   linkMode: "text-only",
 } as const;
@@ -216,7 +229,8 @@ const BASE_MARKDOWN_CLASSNAME = cn(
   "[&_[data-streamdown='mermaid']_svg]:mx-auto [&_[data-streamdown='mermaid']_svg]:block [&_[data-streamdown='mermaid']_svg]:h-auto [&_[data-streamdown='mermaid']_svg]:max-h-[280px] [&_[data-streamdown='mermaid']_svg]:max-w-full [&_[data-streamdown='mermaid']_svg]:bg-transparent",
   "[&_[data-streamdown='mermaid']>div>div:first-child]:!left-0 [&_[data-streamdown='mermaid']>div>div:first-child]:rounded-none [&_[data-streamdown='mermaid']>div>div:first-child]:border-0 [&_[data-streamdown='mermaid']>div>div:first-child]:bg-transparent [&_[data-streamdown='mermaid']>div>div:first-child]:p-0 [&_[data-streamdown='mermaid']>div>div:first-child]:shadow-none [&_[data-streamdown='mermaid']>div>div:first-child]:backdrop-blur-none",
   "[&_[data-streamdown='mermaid-block-actions']]:gap-2 [&_[data-streamdown='mermaid-block-actions']]:border-0 [&_[data-streamdown='mermaid-block-actions']]:rounded-none [&_[data-streamdown='mermaid-block-actions']]:bg-transparent [&_[data-streamdown='mermaid-block-actions']]:p-0 [&_[data-streamdown='mermaid-block-actions']]:shadow-none [&_[data-streamdown='mermaid-block-actions']]:backdrop-blur-none",
-  "[&_[data-streamdown='mermaid-block-actions']_button]:border-0 [&_[data-streamdown='mermaid-block-actions']_button]:bg-transparent [&_[data-streamdown='mermaid-block-actions']_button]:shadow-none [&_[data-streamdown='mermaid-block-actions']_button:hover]:bg-foreground/[0.04] [&_[data-streamdown='mermaid-block-actions']_button:hover]:text-foreground",
+  "[&_[data-streamdown='mermaid-block-actions']>button]:border-0 [&_[data-streamdown='mermaid-block-actions']>button]:bg-transparent [&_[data-streamdown='mermaid-block-actions']>button]:shadow-none [&_[data-streamdown='mermaid-block-actions']>button:hover]:bg-foreground/[0.04] [&_[data-streamdown='mermaid-block-actions']>button:hover]:text-foreground",
+  "[&_[data-streamdown='mermaid-block-actions']>div>button]:border-0 [&_[data-streamdown='mermaid-block-actions']>div>button]:bg-transparent [&_[data-streamdown='mermaid-block-actions']>div>button]:shadow-none [&_[data-streamdown='mermaid-block-actions']>div>button:hover]:bg-foreground/[0.04] [&_[data-streamdown='mermaid-block-actions']>div>button:hover]:text-foreground",
   "[&_[data-streamdown='mermaid-block-actions']_svg]:size-3",
   "[&_[data-streamdown='mermaid-block']_button>svg]:size-3",
   "[&_code:not(pre_code)]:rounded-md [&_code:not(pre_code)]:bg-foreground/[0.05] [&_code:not(pre_code)]:px-1.5 [&_code:not(pre_code)]:py-0.5 [&_code:not(pre_code)]:font-mono [&_code:not(pre_code)]:text-[0.85em] [&_code:not(pre_code)]:text-primary [&_code:not(pre_code)]:whitespace-pre-wrap [&_code:not(pre_code)]:break-words [&_code:not(pre_code)]:[overflow-wrap:anywhere]",
@@ -451,6 +465,7 @@ function ThinkingSegmentBlock({
   streaming: boolean;
 }) {
   const t = useTranslations("chat.markdown.thinking");
+  const translations = useStreamdownTranslations();
   const active = streaming || incomplete;
   const [accordionValue, setAccordionValue] = React.useState(() => (active ? "thinking" : ""));
   const wasActiveRef = React.useRef(active);
@@ -525,6 +540,7 @@ function ThinkingSegmentBlock({
               shikiTheme={["github-light", "github-dark"]}
               animated={false}
               isAnimating={false}
+              translations={translations}
             >
               {content}
             </Streamdown>
@@ -546,6 +562,7 @@ function HTMLMarkdownRenderProvider({
   components: Components;
   plugins: PluginConfig;
 }) {
+  const translations = useStreamdownTranslations();
   const renderHTMLMarkdown = React.useCallback(
     (source: string) => (
       <MarkdownHTMLMarkdownRendererContext.Provider value={null}>
@@ -563,12 +580,13 @@ function HTMLMarkdownRenderProvider({
           shikiTheme={["github-light", "github-dark"]}
           animated={false}
           isAnimating={false}
+          translations={translations}
         >
           {source}
         </Streamdown>
       </MarkdownHTMLMarkdownRendererContext.Provider>
     ),
-    [className, components, plugins],
+    [className, components, plugins, translations],
   );
 
   return (
@@ -613,6 +631,7 @@ export const StreamdownRender = React.memo(function StreamdownRender({
     () => segments.filter((segment): segment is Extract<RenderSegment, { type: "thinking" }> => segment.type === "thinking"),
     [segments],
   );
+  const translations = useStreamdownTranslations();
   const markdownSegments = React.useMemo(
     () => segments.filter((segment): segment is Extract<RenderSegment, { type: "markdown" }> => segment.type === "markdown"),
     [segments],
@@ -683,6 +702,7 @@ export const StreamdownRender = React.memo(function StreamdownRender({
                 shikiTheme={["github-light", "github-dark"]}
                 animated={false}
                 isAnimating={streaming}
+                translations={translations}
               >
                 {segment.content}
               </Streamdown>