diff --git a/app/(chat)/api/chat/route.ts b/app/(chat)/api/chat/route.ts
index 737b5f8..8687727 100644
--- a/app/(chat)/api/chat/route.ts
+++ b/app/(chat)/api/chat/route.ts
@@ -124,6 +124,54 @@ function applyHiddenPromptToMessages(messages: ChatMessage[], hiddenPrompt?: str
   return cloned;
 }
 
+function guessImageMediaType(url: string): string {
+  const cleanUrl = url.split("?")[0]?.toLowerCase() || "";
+  if (cleanUrl.endsWith(".jpg") || cleanUrl.endsWith(".jpeg")) return "image/jpeg";
+  if (cleanUrl.endsWith(".webp")) return "image/webp";
+  if (cleanUrl.endsWith(".gif")) return "image/gif";
+  if (cleanUrl.endsWith(".bmp")) return "image/bmp";
+  if (cleanUrl.endsWith(".svg")) return "image/svg+xml";
+  return "image/png";
+}
+
+function injectHistoryImagesToLastUserMessage(
+  messages: ChatMessage[],
+  historyImages: string[]
+): ChatMessage[] {
+  if (!historyImages || historyImages.length === 0) return messages;
+
+  let lastUserIndex = -1;
+  for (let i = messages.length - 1; i >= 0; i--) {
+    if (messages[i]?.role === "user") {
+      lastUserIndex = i;
+      break;
+    }
+  }
+
+  if (lastUserIndex < 0) return messages;
+
+  const lastUserMessage = messages[lastUserIndex];
+  const hasExistingImage = lastUserMessage.parts?.some(
+    (p: any) => p.type === "file" || p.type === "image" || p.type === "image_url"
+  );
+  if (hasExistingImage) return messages;
+
+  const imageParts = historyImages.map((url, index) => ({
+    type: "file" as const,
+    url,
+    name: `history-image-${index + 1}`,
+    mediaType: guessImageMediaType(url),
+    mimeType: guessImageMediaType(url),
+  }));
+
+  const updatedMessage: ChatMessage = {
+    ...lastUserMessage,
+    parts: [...lastUserMessage.parts, ...imageParts],
+  };
+
+  return messages.map((msg, idx) => (idx === lastUserIndex ? updatedMessage : msg));
+}
+
 /**
  * 自定义消息转换函数
  * 注意：gemini-image 和 huanke-gemini 都需要 URL 格式（不是 Base64）
@@ -823,7 +871,8 @@ export async function POST(request: Request) {
             
             // 只传递最后一条用户消息，避免上下文历史干扰生图效果
             const lastUserMessage = uiMessagesForModel.filter((m) => m.role === "user").pop();
-            const messagesForGemini = lastUserMessage ? [lastUserMessage] : uiMessagesForModel;
+            let messagesForGemini = lastUserMessage ? [lastUserMessage] : uiMessagesForModel;
+            messagesForGemini = injectHistoryImagesToLastUserMessage(messagesForGemini, smartAutoHistoryImages);
             console.log("[Chat API] Gemini: Using only last user message (no history context)");
             
             // 转换消息：gemini-image 需要 base64 格式，huanke-gemini 需要 URL 格式
@@ -971,7 +1020,10 @@ export async function POST(request: Request) {
                   console.log("[Chat API] Executing Volcano Vision failover...");
                   
                   // 转换消息（火山引擎会自动处理 Base64）
-                  const volcanoMessages = await convertMessagesWithImages(uiMessagesForModel, "volcano");
+                  const volcanoMessages = await convertMessagesWithImages(
+                    injectHistoryImagesToLastUserMessage(uiMessagesForModel, smartAutoHistoryImages),
+                    "volcano"
+                  );
                   
                   // 调用火山引擎生成（故障转移时只生成 1 张，保持与 Gemini 一致）
                   const volcanoResult = await (volcanoLanguageModel as any).doGenerate({
@@ -1189,32 +1241,7 @@ export async function POST(request: Request) {
               }));
             }
             
-            // 🆕 如果使用了历史图片，将其注入到消息中（支持多张）
-            if (smartAutoHistoryImages.length > 0 && messagesForAlibaba.length > 0) {
-              console.log("[Chat API] 🖼️ Injecting", smartAutoHistoryImages.length, "history image(s) into message");
-              messagesForAlibaba = messagesForAlibaba.map((msg) => {
-                // 检查消息中是否已有图片
-                const hasExistingImage = msg.parts.some(
-                  (p: any) => p.type === "file" || p.type === "image"
-                );
-                
-                if (!hasExistingImage) {
-                  // 注入所有历史图片
-                  const imageParts = smartAutoHistoryImages.map((url) => ({
-                    type: "file" as const,
-                    url,
-                    mediaType: "image/png",
-                    mimeType: "image/png",
-                  }));
-                  return {
-                    ...msg,
-                    // @ts-ignore - 类型兼容性问题，运行时正确
-                    parts: [...msg.parts, ...imageParts],
-                  };
-                }
-                return msg;
-              });
-            }
+            messagesForAlibaba = injectHistoryImagesToLastUserMessage(messagesForAlibaba, smartAutoHistoryImages);
             
             const tryGenerateImage = async (modelIdToUse: string, isRetry: boolean) => {
               // 转换消息（阿里生图支持 URL，会自动上传 base64）
@@ -1435,6 +1462,8 @@ export async function POST(request: Request) {
           return msg;
         });
       }
+
+      messagesForVolcano = injectHistoryImagesToLastUserMessage(messagesForVolcano, smartAutoHistoryImages);
       
       const volcanoStream = createUIMessageStream({
         execute: async ({ writer }) => {
@@ -1763,7 +1792,10 @@ export async function POST(request: Request) {
         console.log("[Chat API] Provider type:", (languageModel as any).provider); // 调试日志
 
         // 转换消息，对于 Gemini 和千问视频将图片 URL 转换为 base64
-        const convertedMessages = await convertMessagesWithImages(uiMessagesForModel, (languageModel as any).provider || "");
+        const convertedMessages = await convertMessagesWithImages(
+          injectHistoryImagesToLastUserMessage(uiMessagesForModel, smartAutoHistoryImages),
+          (languageModel as any).provider || ""
+        );
         console.log("[Chat API] Messages converted, count:", convertedMessages.length); // 调试日志
 
         // 🆕 检测是否是视频模型