fix: reject empty gpt image results

app/(chat)/api/chat/route.ts

@@ -129,6 +129,7 @@ import {
   buildAgentToolVideoMarkdown,
   prependImageModelBadge,
 } from "@/lib/ai/runtime/agent-media-markdown";
+import { extractImageUrlsFromText } from "@/lib/image-url";
 import { saveGeneratedImages } from "@/lib/ai/runtime/generated-image-persistence";
 import {
   recordAiModelHealthFailure,
@@ -6332,6 +6333,21 @@ export async function POST(request: Request) {
             return injectHistoryImagesToLastUserMessage(messagesForGemini, smartAutoHistoryImages);
           };
 
+          const assertGeneratedImageMarkdown = (markdown: string, modelLabel: string) => {
+            const normalizedMarkdown = String(markdown || "").trim();
+            const imageUrls = extractImageUrlsFromText(normalizedMarkdown);
+            if (imageUrls.length > 0) {
+              return normalizedMarkdown;
+            }
+
+            const failureHintPattern =
+              /生成图片失败|未找到图片数据|未解析到图片|模型未返回生成图片|图片数据不可用/i;
+            const reason = failureHintPattern.test(normalizedMarkdown)
+              ? normalizedMarkdown
+              : "模型响应未包含可用图片";
+            throw new Error(`${modelLabel} 未返回可用图片：${reason.slice(0, 160)}`);
+          };
+
           // 🆕 尝试生成图片的函数（支持备用模型切换）
           const tryGenerateImage = async (modelIdToUse: string, isRetry = false): Promise<string> => {
             chatApiLogger.info(`[Chat API] ${isRetry ? "🔄 Retry with fallback" : "🚀 Trying"} model: ${modelIdToUse}`);
@@ -6352,7 +6368,10 @@ export async function POST(request: Request) {
               overrideModelId: isRetry ? modelIdToUse : undefined, // 🆕 使用备用模型 ID
             });
             
-            return result.text || "图片生成失败";
+            return assertGeneratedImageMarkdown(
+              result.text || "",
+              isRetry ? `备用模型 ${modelIdToUse}` : `主模型 ${modelIdToUse}`,
+            );
           };
           
           let stopKeepalive: (() => void) | null = null;
@@ -6428,7 +6447,10 @@ export async function POST(request: Request) {
                       imageSize: defaultImageQualityParams.imageSize,
                     },
                   });
-                  imageMarkdown = fallbackResult.text;
+                  imageMarkdown = assertGeneratedImageMarkdown(
+                    fallbackResult.text,
+                    `备用模型 ${fallbackResult.displayName}`,
+                  );
                   usedModelId = fallbackResult.usedModelId;
                   fallbackSuccess = true;
                   chatApiLogger.info(`[Chat API] ✅ Fallback model ${fallbackResult.displayName} succeeded!`);
@@ -6493,7 +6515,10 @@ export async function POST(request: Request) {
                         imageCount: defaultImageQualityParams.imageCount,
                       },
                     });
-                    imageMarkdown = fallbackResult.text;
+                    imageMarkdown = assertGeneratedImageMarkdown(
+                      fallbackResult.text,
+                      `跨服务备用模型 ${fallbackResult.displayName}`,
+                    );
                     usedModelId = fallbackResult.usedModelId;
                     fallbackSuccess = true;
                     chatApiLogger.info(`[Chat API] ✅ Gemini cross-provider fallback model ${fallbackResult.displayName} succeeded!`);