修复连续生图保真：锁定视角背景并禁用编辑扩写

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

@@ -200,7 +200,10 @@ function hasUserCustomizedImageParams(params?: PostRequestBody["imageParams"]):
   const customizedImageSize =
     typeof params.imageSize === "string" && params.imageSize.trim() && params.imageSize.toUpperCase() !== "2K";
   const customizedImageCount = typeof params.imageCount === "number" && params.imageCount !== 1;
-  const customizedAdvanced = Boolean(params.size || params.seed !== undefined || params.n || params.negativePrompt);
+  const customizedPromptExtend = typeof params.promptExtend === "boolean";
+  const customizedAdvanced = Boolean(
+    params.size || params.seed !== undefined || params.n || params.negativePrompt || customizedPromptExtend
+  );
   return customizedAspectRatio || customizedImageSize || customizedImageCount || customizedAdvanced;
 }
 
@@ -236,6 +239,9 @@ function mergeImageParamsWithAgentRecommendation(params: {
 
   if (intent === "image_edit") {
     merged.imageCount = 1;
+    if (typeof base.promptExtend !== "boolean") {
+      merged.promptExtend = false;
+    }
   }
 
   return Object.keys(merged).length > 0 ? merged : undefined;

lib/ai/auto-agent-graph.ts

@@ -111,6 +111,10 @@ function sanitizeRecommendedImageParams(
     safe.promptExtend = params.promptExtend;
   }
 
+  if (intent === "image_edit") {
+    safe.promptExtend = false;
+  }
+
   return Object.keys(safe).length > 0 ? safe : undefined;
 }
 
@@ -121,7 +125,7 @@ function heuristicImageParams(
   const normalized = text.toLowerCase();
   const params: AgentRecommendedImageParams = {
     imageSize: "2K",
-    promptExtend: true,
+    promptExtend: analysis.intent === "image_edit" ? false : true,
   };
 
   if (analysis.intent === "image_edit") {

lib/ai/prompt-optimizer.ts

@@ -316,6 +316,56 @@ function sanitizeSuggestedParams(input?: {
   return Object.keys(output).length > 0 ? output : undefined;
 }
 
+function shouldKeepBackgroundAsIs(originalPrompt: string, subIntent?: string): boolean {
+  if (subIntent === "replace_background" || subIntent === "remove_background") {
+    return false;
+  }
+  return !/(换背景|改背景|替换背景|背景改成|背景换成|白底|黑底|透明背景|场景换成|背景变成)/i.test(
+    originalPrompt
+  );
+}
+
+function shouldKeepCameraAsIs(originalPrompt: string): boolean {
+  return !/(角度|视角|机位|镜头|构图|俯拍|仰拍|侧拍|旋转|翻转|远景|近景|特写)/i.test(
+    originalPrompt
+  );
+}
+
+function enforceImageEditStability(params: {
+  optimizedPrompt: string;
+  originalPrompt: string;
+  subIntent?: string;
+  negativePrompt?: string;
+}) {
+  const keepBackground = shouldKeepBackgroundAsIs(params.originalPrompt, params.subIntent);
+  const keepCamera = shouldKeepCameraAsIs(params.originalPrompt);
+
+  const stabilityRules = [
+    "只修改用户明确要求的内容，其他元素保持不变",
+    keepCamera ? "保持原图拍摄角度、主体朝向、构图和透视关系不变" : "",
+    keepBackground
+      ? "保持原图背景颜色与明暗不变；若原图是白底，继续保持纯白背景(#FFFFFF)"
+      : "",
+    "保持主体形状比例、材质纹理和光影一致，禁止出现黑底/灰底污染",
+  ].filter(Boolean);
+
+  const mergedNegativePrompt = [
+    params.negativePrompt || "",
+    keepCamera ? "角度变化，构图漂移，主体旋转" : "",
+    keepBackground ? "背景变黑，背景变灰，背景误改，白底丢失" : "",
+    "主体变形，比例错误，材质改变，边缘脏污",
+  ]
+    .filter(Boolean)
+    .join("，");
+
+  const promptWithStability = `${params.optimizedPrompt.trim()}\n\n保真约束：${stabilityRules.join("；")}。`;
+
+  return {
+    optimizedPrompt: promptWithStability,
+    negativePrompt: mergedNegativePrompt,
+  };
+}
+
 function fallbackImageGenPrompt(originalPrompt: string): OptimizeResult {
   const normalized = originalPrompt.replace(/\s+/g, " ").trim();
   const optimizedPrompt = [
@@ -439,10 +489,22 @@ export async function optimizePromptWithLLM(params: {
     const parsedResult = parseOptimizerJson(responseText);
     if (parsedResult) {
       console.log("[Prompt Optimizer LLM] Result parsed");
+      const stabilized =
+        intent === "image_edit"
+          ? enforceImageEditStability({
+              optimizedPrompt: parsedResult.optimizedPrompt || originalPrompt,
+              originalPrompt,
+              subIntent,
+              negativePrompt: parsedResult.negativePrompt || "模糊，低质量，变形，失真",
+            })
+          : {
+              optimizedPrompt: parsedResult.optimizedPrompt || originalPrompt,
+              negativePrompt: parsedResult.negativePrompt || "模糊，低质量，变形，失真",
+            };
       return {
         originalPrompt,
-        optimizedPrompt: parsedResult.optimizedPrompt || originalPrompt,
-        negativePrompt: parsedResult.negativePrompt || "模糊，低质量，变形，失真",
+        optimizedPrompt: stabilized.optimizedPrompt,
+        negativePrompt: stabilized.negativePrompt,
         recommendedImageParams: sanitizeSuggestedParams(parsedResult.suggestedParams),
         friendlyMessage: intent === "image_edit" ? FRIENDLY_MESSAGES[subIntent || ""]?.template : undefined,
       };
@@ -574,6 +636,17 @@ export function optimizePrompt(params: {
     friendlyMessage: friendlyMessage || `好的，我来帮你处理这张图片~`,
   };
 
+  if (intent === "image_edit") {
+    const stabilized = enforceImageEditStability({
+      optimizedPrompt: result.optimizedPrompt,
+      originalPrompt,
+      subIntent,
+      negativePrompt: result.negativePrompt,
+    });
+    result.optimizedPrompt = stabilized.optimizedPrompt;
+    result.negativePrompt = stabilized.negativePrompt;
+  }
+
   console.log("[Prompt Optimizer] Output:", result);
   return result;
 }

lib/ai/smart-analyzer.ts

@@ -23,6 +23,35 @@ export interface AnalysisResult {
   conversationalReply?: string; // 🆕 自然对话回复
 }
 
+function normalizeIntentForImageContext(
+  result: AnalysisResult,
+  text: string,
+  hasImage: boolean
+): AnalysisResult {
+  if (!hasImage || result.intent !== "image_gen") {
+    return result;
+  }
+
+  const normalizedText = text.toLowerCase();
+  const explicitGenerate =
+    /重新生成|再来一张|生成新图|新建图片|创作一张|参考.*生成|按这个风格生成|以这张图为灵感生成/.test(
+      normalizedText
+    );
+  const editSignal =
+    /改|调整|优化|去掉|换成|改成|保留|继续|再.*一点|修|抠|替换|增强|清晰|重绘/.test(normalizedText);
+
+  if (explicitGenerate && !editSignal) {
+    return result;
+  }
+
+  return {
+    ...result,
+    intent: "image_edit",
+    subIntent: result.subIntent,
+    confidence: Math.max(result.confidence, 0.78),
+  };
+}
+
 // 系统提示词 - 针对图片编辑场景优化，生成自然对话
 const ANALYZER_SYSTEM_PROMPT = `你是一个友好的AI图片编辑助手。用户会给你发送图片和编辑请求，你需要：
 1. 理解用户想要对图片做什么
@@ -319,7 +348,7 @@ ${historyText}
   if (jsonMatch) {
     try {
       const result = JSON.parse(jsonMatch[0]) as AnalysisResult;
-      return result;
+      return normalizeIntentForImageContext(result, text, hasImage);
     } catch (e) {
       console.error("[Smart Analyzer] Failed to parse LLM response:", e);
     }