fix: subscription extend instead of overwrite, improve placeholder pages

- Subscription purchase now extends expire_time when user has active
  subscription, instead of cancelling and replacing
- Admin subscription creation uses same extend logic
- Subscribe page shows "续费" button and extend message for renewals
- Help and contact pages: add pink header, centered icon + text

miniprogram/pages/contact/contact.wxml

@@ -1,9 +1,13 @@
 <view class="page">
-  <view class="page-header" style="padding-top: {{statusBarHeight + 24}}px;">
+  <view class="page-header page-header-pink" style="padding-top: {{statusBarHeight + 24}}px;">
     <view class="nav-back" bindtap="onBack">‹ 返回</view>
     <view class="page-header-title">联系我们</view>
   </view>
   <view class="page-content">
-    <view class="placeholder">内容建设中...</view>
+    <view class="placeholder-container">
+      <view class="placeholder-icon">📬</view>
+      <view class="placeholder-text">内容建设中</view>
+      <view class="placeholder-sub">联系方式正在整理，敬请期待</view>
+    </view>
   </view>
 </view>

miniprogram/pages/contact/contact.wxss

@@ -1,6 +1,24 @@
-.placeholder {
+.placeholder-container {
-  text-align: center;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  padding: 120rpx 40rpx;
+}
+
+.placeholder-icon {
+  font-size: 100rpx;
+  margin-bottom: 32rpx;
+}
+
+.placeholder-text {
+  font-size: 32rpx;
+  font-weight: 600;
+  color: #333333;
+  margin-bottom: 12rpx;
+}
+
+.placeholder-sub {
+  font-size: 26rpx;
   color: #999999;
-  font-size: 28rpx;
-  padding: 80rpx 0;
 }

miniprogram/pages/help/help.wxml

@@ -1,9 +1,13 @@
 <view class="page">
-  <view class="page-header" style="padding-top: {{statusBarHeight + 24}}px;">
+  <view class="page-header page-header-pink" style="padding-top: {{statusBarHeight + 24}}px;">
     <view class="nav-back" bindtap="onBack">‹ 返回</view>
     <view class="page-header-title">使用帮助</view>
   </view>
   <view class="page-content">
-    <view class="placeholder">内容建设中...</view>
+    <view class="placeholder-container">
+      <view class="placeholder-icon">📖</view>
+      <view class="placeholder-text">内容建设中</view>
+      <view class="placeholder-sub">帮助文档正在编写，敬请期待</view>
+    </view>
   </view>
 </view>

miniprogram/pages/help/help.wxss

@@ -1,6 +1,24 @@
-.placeholder {
+.placeholder-container {
-  text-align: center;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  padding: 120rpx 40rpx;
+}
+
+.placeholder-icon {
+  font-size: 100rpx;
+  margin-bottom: 32rpx;
+}
+
+.placeholder-text {
+  font-size: 32rpx;
+  font-weight: 600;
+  color: #333333;
+  margin-bottom: 12rpx;
+}
+
+.placeholder-sub {
+  font-size: 26rpx;
   color: #999999;
-  font-size: 28rpx;
-  padding: 80rpx 0;
 }

miniprogram/pages/subscribe-plans/subscribe-plans.js

@@ -118,9 +118,16 @@ Page({
       return
     }
 
+    var isRenew = self.data.subscription && self.data.subscription.status === 'active' && self.data.subRemaining > 0
+    var planDays = plan.key === 'yearly' ? 365 : 30
+    var title = isRenew ? '确认续费' : '确认支付'
+    var content = isRenew
+      ? '在现有订阅基础上延长' + planDays + '天，模拟支付 ¥' + plan.price + '？（测试环境）'
+      : '模拟支付 ¥' + plan.price + '？（测试环境）'
+
     wx.showModal({
-      title: '确认支付',
+      title: title,
-      content: '模拟支付 ¥' + plan.price + '？（测试环境）',
+      content: content,
       success: function (res) {
         if (res.confirm) {
           self.doPurchase(plan)

miniprogram/pages/subscribe-plans/subscribe-plans.wxml

@@ -38,7 +38,7 @@
     </view>
 
     <button class="btn-primary btn-primary-gold" bindtap="onPurchase" disabled="{{purchasing}}" loading="{{purchasing}}">
-      确认支付
+      {{subscription && subscription.status === 'active' && subRemaining > 0 ? '续费' : '确认支付'}}
     </button>
     <view class="agreement">支付即表示同意《订阅协议》</view>
   </view>

server/src/dao/subscription.dao.js

@@ -62,7 +62,9 @@ async function createTrial(userId, orderId) {
 }
 
 /**
- * Purchase / activate a subscription: expire old active subs, insert new one
+ * Purchase / activate a subscription: extend existing or create new
+ * If user has an active subscription, add days to current expire_time.
+ * If no active subscription, insert a new one starting NOW().
  * @param {number} userId
  * @param {string} plan - 'monthly' | 'yearly' | 'trial'
  * @param {number} amount
@@ -72,6 +74,18 @@ async function createTrial(userId, orderId) {
  */
 async function purchase(userId, plan, amount, orderId, days) {
   return transaction(async conn => {
+    const [rows] = await conn.execute(
+      'SELECT subscription_id FROM subscriptions WHERE user_id = ? AND status = 1 AND expire_time > NOW() LIMIT 1',
+      [userId]
+    )
+    if (rows.length > 0) {
+      // Extend existing active subscription
+      await conn.execute(
+        'UPDATE subscriptions SET expire_time = DATE_ADD(expire_time, INTERVAL ? DAY), plan = ?, amount = amount + ? WHERE subscription_id = ?',
+        [days, plan, amount, rows[0].subscription_id]
+      )
+    } else {
+      // Expire any stale rows (status=1 but already past expire_time), then insert new
       await conn.execute(
         'UPDATE subscriptions SET status = 2 WHERE user_id = ? AND status = 1',
         [userId]
@@ -80,12 +94,14 @@ async function purchase(userId, plan, amount, orderId, days) {
         'INSERT INTO subscriptions (user_id, plan, status, amount, order_id, start_time, expire_time) VALUES (?, ?, 1, ?, ?, NOW(), DATE_ADD(NOW(), INTERVAL ? DAY))',
         [userId, plan, amount, orderId, days]
       )
+    }
   })
 }
 
 /**
- * Admin-create a subscription (expire old, insert new) without transaction
+ * Admin-create a subscription: extend existing or create new
- * Used by admin subscription creation endpoint
+ * If user has an active subscription, add days to current expire_time.
+ * If no active subscription, insert a new one starting NOW().
  * @param {number} userId
  * @param {string} plan
  * @param {number} amount
@@ -94,6 +110,18 @@ async function purchase(userId, plan, amount, orderId, days) {
  * @returns {Promise<void>}
  */
 async function adminCreate(userId, plan, amount, orderId, days) {
+  const active = await one(
+    'SELECT subscription_id FROM subscriptions WHERE user_id = :user_id AND status = 1 AND expire_time > NOW() LIMIT 1',
+    { user_id: userId }
+  )
+  if (active) {
+    // Extend existing active subscription
+    await query(
+      'UPDATE subscriptions SET expire_time = DATE_ADD(expire_time, INTERVAL :days DAY), plan = :plan, amount = amount + :amount WHERE subscription_id = :sid',
+      { days, plan, amount, sid: active.subscription_id }
+    )
+  } else {
+    // Expire any stale rows, then insert new
     await query(
       'UPDATE subscriptions SET status = 2 WHERE user_id = :user_id AND status = 1',
       { user_id: userId }
@@ -102,6 +130,7 @@ async function adminCreate(userId, plan, amount, orderId, days) {
       'INSERT INTO subscriptions (user_id, plan, status, amount, order_id, start_time, expire_time) VALUES (:user_id, :plan, 1, :amount, :order_id, NOW(), DATE_ADD(NOW(), INTERVAL :days DAY))',
       { user_id: userId, plan, amount, order_id: orderId, days }
     )
+  }
 }
 
 /**

server/src/routes/subscription.js

@@ -55,7 +55,8 @@ router.post('/subscription/mock-purchase', requireUser, wrap(async (req, res) =>
   const orderId = 'MOCK' + Date.now()
   await subscriptionDao.purchase(req.user.user_id, plan, p.amount, orderId, p.days)
   await logDao.write({ user_id: req.user.user_id, action: 'subscription_mock_purchase', detail: '模拟购买: ' + plan, ip: req.ip })
-  res.json(ok({ status: 'active', plan, remaining_days: p.days }))
+  const sub = await subscriptionDao.findActive(req.user.user_id)
+  res.json(ok({ status: 'active', plan, remaining_days: sub ? sub.remaining_days : p.days }))
 }))
 
 router.post('/subscription/trial', requireUser, wrap(async (req, res) => {
@@ -76,7 +77,8 @@ router.post('/subscription/verify', requireAdmin, wrap(async (req, res) => {
   const p = PLANS[plan]
   await subscriptionDao.purchase(userId, plan, p.amount, req.body.order_id || 'ORD' + Date.now(), p.days)
   await logDao.write({ admin_id: req.admin.admin_id, action: 'subscription_verify', detail: '订阅生效: ' + plan + ' user:' + userId, ip: req.ip })
-  res.json(ok({ status: 'active', plan, remaining_days: p.days }))
+  const sub = await subscriptionDao.findActive(userId)
+  res.json(ok({ status: 'active', plan, remaining_days: sub ? sub.remaining_days : p.days }))
 }))
 
 module.exports = router