fix(ui): 初始背景跟随外观 + 修复跟随系统

- app.config 移除写死的浅色背景，交给 theme.json 按系统外观选择首帧底色
- 跟随系统模式增加 setInterval 轮询兜底，onThemeChange 不回调时也能跟上切换

dist/app.json

@@ -1 +1 @@
-{"darkmode":true,"themeLocation":"theme.json","pages":["pages/index/index","pages/shop/index","pages/shop/detail/index","pages/product/index","pages/diy/index","pages/diy/stickerEdit/index","pages/checkout/index","pages/designList/index","pages/orders/index","pages/profile/index","pages/service/index","pages/wordcloud/index","pages/orderDetail/index","pages/address/index","pages/settings/index","pages/agreement/index","pages/userDatabase/index"],"window":{"backgroundTextStyle":"dark","navigationStyle":"custom","navigationBarBackgroundColor":"#faf7f2","backgroundColor":"#faf7f2","backgroundColorTop":"#faf7f2","backgroundColorBottom":"#faf7f2","navigationBarTextStyle":"black"},"tabBar":{"custom":true,"list":[{"pagePath":"pages/index/index","text":"首页"},{"pagePath":"pages/shop/index","text":"商品"},{"pagePath":"pages/designList/index","text":"设计清单"},{"pagePath":"pages/orders/index","text":"订单"},{"pagePath":"pages/profile/index","text":"我的"}]}}
+{"darkmode":true,"themeLocation":"theme.json","pages":["pages/index/index","pages/shop/index","pages/shop/detail/index","pages/product/index","pages/diy/index","pages/diy/stickerEdit/index","pages/checkout/index","pages/designList/index","pages/orders/index","pages/profile/index","pages/service/index","pages/wordcloud/index","pages/orderDetail/index","pages/address/index","pages/settings/index","pages/agreement/index","pages/userDatabase/index"],"window":{"navigationStyle":"custom"},"tabBar":{"custom":true,"list":[{"pagePath":"pages/index/index","text":"首页"},{"pagePath":"pages/shop/index","text":"商品"},{"pagePath":"pages/designList/index","text":"设计清单"},{"pagePath":"pages/orders/index","text":"订单"},{"pagePath":"pages/profile/index","text":"我的"}]}}

src/app.config.ts

@@ -23,16 +23,9 @@ export default defineAppConfig({
     'pages/userDatabase/index'
   ],
   window: {
-    backgroundTextStyle: 'dark',
+    // 初始窗口/导航背景交给 theme.json 按系统外观自动选择，
+    // 避免首帧先固定成浅色再被 JS 切到深色而闪烁。
     navigationStyle: 'custom',
-    // 顶部/窗口颜色先显式固定为小程序浅色主题，避免 iOS 顶部区域跟随系统深色；
-    // 应用启动后页面 Hook 会按小程序内主题实时覆盖上面的值。
-    navigationBarBackgroundColor: '#faf7f2',
-    backgroundColor: '#faf7f2',
-    backgroundColorTop: '#faf7f2',
-    backgroundColorBottom: '#faf7f2',
-    // 状态栏文字默认黑字；各页面 useStatusBar 会按小程序主题覆盖它。
-    navigationBarTextStyle: 'black',
   },
   tabBar: {
     custom: true,

src/context/ThemeContext.tsx

@@ -1,4 +1,4 @@
-import { createContext, useContext, useState, useCallback, useEffect } from 'react'
+import { createContext, useContext, useState, useCallback, useEffect, useRef } from 'react'
 import Taro, { useDidShow } from '@tarojs/taro'
 import { View } from '@tarojs/components'
 import { getTheme, setTheme as saveTheme, resolveTheme, setDetectedSystemTheme, type ThemeMode } from '../utils/store'
@@ -31,6 +31,7 @@ type ThemeChangeApi = {
 export function ThemeProvider({ children }: { children: React.ReactNode }) {
   const [theme, set] = useState<ThemeMode>(getTheme())
   const [resolvedTheme, setResolved] = useState<'light' | 'dark'>(resolveTheme(getTheme()))
+  const systemThemeRef = useRef<'light' | 'dark' | null>(null)
 
   const updateResolved = useCallback((mode: ThemeMode) => {
     setResolved(resolveTheme(mode))
@@ -42,6 +43,7 @@ export function ThemeProvider({ children }: { children: React.ReactNode }) {
    */
   const updateFromSystem = useCallback((t: 'light' | 'dark') => {
     setDetectedSystemTheme(t)
+    systemThemeRef.current = t
     if (getTheme() === 'auto') {
       setResolved(t)
     }
@@ -102,6 +104,23 @@ export function ThemeProvider({ children }: { children: React.ReactNode }) {
     }
   }, [updateFromSystem])
 
+  // 部分机型/工具上 onThemeChange 不回调，自动模式再轮询兜底，保证系统切换能跟上
+  useEffect(() => {
+    if (theme !== 'auto') return
+    const timer = setInterval(() => {
+      try {
+        const info = Taro.getAppBaseInfo()
+        const next = info.theme === 'dark' ? 'dark' : 'light'
+        if (next !== systemThemeRef.current) {
+          updateFromSystem(next)
+        }
+      } catch {
+        /* ignore */
+      }
+    }, 2000)
+    return () => clearInterval(timer)
+  }, [theme, updateFromSystem])
+
   // 广播实际生效主题，供 custom-tab-bar 等独立组件订阅
   useEffect(() => {
     Taro.eventCenter.trigger(THEME_CHANGE_EVENT, resolvedTheme)

tools/liquid-glass.test.mjs

@@ -42,3 +42,16 @@ test('app sets page background before first render without a blinking full fade'
   assert.match(appSource, /componentWillMount/)
   assert.doesNotMatch(appCss, /animation:\s*page-fade-in/)
 })
+
+test('delegates initial background to themeLocation instead of hardcoding light', () => {
+  const config = read('src/app.config.ts')
+  assert.match(config, /themeLocation:\s*'theme\.json'/)
+  assert.doesNotMatch(config, /navigationBarBackgroundColor:\s*'#faf7f2'/)
+  assert.doesNotMatch(config, /backgroundColorTop:\s*'#faf7f2'/)
+})
+
+test('polls the system theme while following the system', () => {
+  const ctx = read('src/context/ThemeContext.tsx')
+  assert.match(ctx, /setInterval/)
+  assert.match(ctx, /getAppBaseInfo\(\)/)
+})