对生图优化提示词补充原始需求避免偏差

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

@@ -146,7 +146,17 @@ function applyOptimizedPromptToLatestUserMessage(
     const textPart = msg.parts.find(
       (part): part is { type: "text"; text: string } => part.type === "text",
     );
-    const finalPrompt = `${hiddenPromptPrefix}${prompt}`.trim();
+    const originalText = textPart?.text?.trim() || "";
+    const normalizedOriginal = hiddenPromptPrefix && originalText.startsWith(hiddenPromptPrefix)
+      ? originalText.slice(hiddenPromptPrefix.length).trim()
+      : originalText;
+    const shouldAppendOriginal =
+      normalizedOriginal &&
+      normalizedOriginal !== prompt &&
+      !prompt.includes(normalizedOriginal);
+    const finalPrompt = shouldAppendOriginal
+      ? `${hiddenPromptPrefix}${prompt}\n\n用户原始需求：${normalizedOriginal}`.trim()
+      : `${hiddenPromptPrefix}${prompt}`.trim();
 
     if (textPart) {
       textPart.text = finalPrompt;