fix: loadMessages 对历史剧本 plotJson 自动初始化首条 AI 消息

mini-program/src/pages/main/ScriptView.vue

@@ -663,7 +663,16 @@ const loadMessages = async () => {
 
   try {
     const res = await listMessagesByConversation({ conversationId: conversationId.value, includeVersions: false })
-    messages.value = res.data || []
+    let loaded = res.data || []
+
+    // 历史剧本兼容：若 API 返回空且 plotJson 有内容，自动初始化首条 AI 消息
+    if (loaded.length === 0 && currentResult.value?.plotJson?.fullContent) {
+      await initializeFirstAIMessage()
+      const retryRes = await listMessagesByConversation({ conversationId: conversationId.value, includeVersions: false })
+      loaded = retryRes.data || []
+    }
+
+    messages.value = loaded
     const scriptMessages = messages.value.filter(m => m.type === 'script')
     if (scriptMessages.length > 0) {
       const rootMessage = scriptMessages[0]
@@ -675,6 +684,41 @@ const loadMessages = async () => {
   }
 }
 
+/**
+ * 历史剧本兼容：基于 plotJson 初始化首条 AI 剧本消息
+ * 触发条件：loadMessages 返回空列表，且 currentResult.plotJson.fullContent 存在
+ */
+const initializeFirstAIMessage = async () => {
+  const content = currentResult.value?.plotJson?.fullContent || ''
+  if (!content) return
+
+  try {
+    // 先保存用户心愿消息（theme）
+    const theme = currentResult.value?.theme || currentResult.value?.title || ''
+    if (theme) {
+      await createMessage({
+        conversationId: conversationId.value,
+        content: theme,
+        sender: 'user',
+        type: 'chat'
+      })
+    }
+
+    // 再保存 AI 剧本消息
+    await createMessage({
+      conversationId: conversationId.value,
+      content,
+      sender: 'assistant',
+      type: 'script',
+      metadata: JSON.stringify(currentResult.value?.plotJson || {}),
+      versionNumber: 1
+    })
+  } catch (error) {
+    // 初始化失败不阻塞页面加载，仅日志
+    console.warn('[ScriptView] initializeFirstAIMessage failed:', error)
+  }
+}
+
 const sendChat = async () => {
   if (!chatInput.value.trim() || generating.value) return
   const content = chatInput.value.trim()