fix: 自动生成封面添加用户提示，修复静默返回问题 (#1317)

apps/web/src/pages/generate/hooks/useStep6Cover.ts

@@ -3,6 +3,7 @@
  * 封装封面设置的交互逻辑，对接后端封面模板 CRUD API
  */
 import { useCallback, useEffect, useRef, useState } from "react"
+import { message } from "antd"
 import type { CoverConfig, CoverTemplate } from "../../editing-planner/types"
 import { generateCover } from "@/api/template-editor"
 import {
@@ -66,7 +67,21 @@ export function useStep6Cover({
 
   /** 调用后端智能封面 API，生成封面并更新预览 */
   const generateAutoCover = useCallback(async () => {
-    if (!selectedTemplate || assetIds.length === 0 || generatingRef.current) return
+    if (generatingRef.current) {
+      message.warning("封面正在生成中，请稍候...")
+      return
+    }
+
+    if (!selectedTemplate) {
+      message.error("请先选择模板")
+      return
+    }
+
+    if (assetIds.length === 0) {
+      message.error("请先选择素材")
+      return
+    }
+
     generatingRef.current = true
     try {
       const response = await generateCover(selectedTemplate, {
@@ -80,9 +95,13 @@ export function useStep6Cover({
           thumbnail_url: thumbnailUrl,
           ai_suggested_time: response.cover?.frame_time ?? null,
         })
+        message.success("封面生成成功")
+      } else {
+        message.warning("封面生成未返回图片，请重试")
       }
     } catch (err) {
       console.warn("[Step6] 智能封面生成失败:", err)
+      message.error("封面生成失败，请稍后重试")
     } finally {
       generatingRef.current = false
     }