fix: guard WeChat page follow-up context

wechat/prompts/page-generate.mjs

@@ -8,7 +8,14 @@ import { buildWechatPageImageInstruction } from '../image-generation-policy.mjs'
 /**
  * Service-account-only page generation prompt. Does not use H5 buildAutoChatSkillPrefix.
  */
-export function buildPageGenerateAgentPrompt(intent, { wantsDocx = false, imagePolicy = null } = {}) {
+export function buildPageGenerateAgentPrompt(
+  intent,
+  {
+    wantsDocx = false,
+    imagePolicy = null,
+    preferImmediateContext = false,
+  } = {},
+) {
   const topic = String(intent?.agentText ?? intent?.displayText ?? '').trim();
   const pageDataTask = isPageDataIntent(topic) || isPageDataDevIntent(topic);
   const scheduleTimezone = process.env.H5_DEFAULT_TIMEZONE || 'Asia/Shanghai';
@@ -22,6 +29,14 @@ export function buildPageGenerateAgentPrompt(intent, { wantsDocx = false, imageP
   const imageBlock = buildWechatPageImageInstruction(imagePolicy, {
     sourceMessageId: intent?.msgId,
   });
+  const immediateContextBlock = preferImmediateContext
+    ? [
+        '【即时上下文优先】当前需求是对本会话紧邻内容的续作。',
+        '“这个/刚才/做成页面”等指代只能解析为当前会话最近一轮内容，禁止用长期记忆、历史偏好或旧任务替换主题。',
+        '如果当前会话没有可辨识的紧邻内容，必须请用户补充主题，禁止猜测并生成其他页面。',
+        '',
+      ].join('\n')
+    : '';
   const coverExample = imageBlock
     ? '<本轮 generate_image 返回的 asset.htmlSrc>'
     : 'assets/hero.jpg';
@@ -42,6 +57,7 @@ export function buildPageGenerateAgentPrompt(intent, { wantsDocx = false, imageP
     '',
     docxBlock,
     imageBlock,
+    immediateContextBlock,
     pageDataBlock,
     '步骤（必须全部完成）：',
     pageDataTask