feat: 简化为'每天5次免费→充值星尘'模型——问答免费优先星尘扣减(10/次)+充值引导弹窗+我的页星尘余额卡(去掉免费/Pro分层)

server/src/routes/aiChat.js

@@ -1,6 +1,6 @@
 const express = require('express')
 const router = express.Router()
-const { AIChatQuota, AIModel } = require('../models')
+const { AIChatQuota, AIModel, User } = require('../models')
 const ApiResponse = require('../utils/response')
 const { userAuthMiddleware, optionalAuthMiddleware } = require('../middleware/auth')
 const logger = require('../utils/logger')
@@ -81,10 +81,27 @@ router.post('/ask', askRateLimit, optionalAuthMiddleware, async (req, res) => {
     const quota = await getOrCreateQuota(openid, isGuest)
 
     if (!quota.hasQuota()) {
-      const msg = isGuest
-        ? `今日 ${GUEST_DAILY_QUOTA} 次游客体验已用完，登录后每天可问 5 次`
-        : '今日问答次数已用完，分享好友可获得更多次数'
-      return ApiResponse.error(res, msg, 403, { isGuest, needLogin: isGuest })
+      if (isGuest) {
+        return ApiResponse.error(res, `今日 ${GUEST_DAILY_QUOTA} 次游客体验已用完，登录后每天可问 5 次`, 403, { isGuest, needLogin: true })
+      }
+      // 免费额度用完 → 检查星尘余额，有则扣星尘（10星尘/次）
+      const user = await User.findOne({ openid })
+      const coins = (user && user.vpayCoins) || 0
+      if (coins < 10) {
+        return ApiResponse.error(res, '今日免费次数已用完，充值星尘可继续提问（10星尘/次）', 402, { needRecharge: true, coins, costPerAsk: 10 })
+      }
+      // 扣星尘（原子操作防并发）
+      const updated = await User.updateOne({ _id: user._id, vpayCoins: { $gte: 10 } }, { $inc: { vpayCoins: -10 } })
+      if (updated.modifiedCount === 0) {
+        return ApiResponse.error(res, '星尘余额不足，请充值后继续', 402, { needRecharge: true })
+      }
+      // 跳过正常 quota 扣减，直接用星尘
+      const aiModels2 = await AIModel.getActiveModels()
+      if (!aiModels2 || aiModels2.length === 0) {
+        const env2 = [{ name: 'env-model', apiUrl: process.env.OPENAI_API_URL || 'https://api.openai.com/v1/chat/completions', apiKey: process.env.OPENAI_API_KEY, modelId: process.env.OPENAI_MODEL || 'gpt-3.5-turbo' }]
+        return await tryModels(env2, question, dimension, res, quota, isGuest)
+      }
+      return await tryModels(aiModels2, question, dimension, res, quota, isGuest)
     }
 
     const aiModels = await AIModel.getActiveModels()