const mongoose = require('mongoose'); const notificationSchema = new mongoose.Schema({ title: { type: String, required: true }, message: { type: String, required: true }, type: { type: String, enum: ['INFO', 'ALERT', 'WIN', 'UPDATE'], default: 'INFO' }, target_user_id: { type: mongoose.Schema.Types.ObjectId, ref: 'User', default: null }, created_at: { type: Date, default: Date.now, expires: '3d' } }); module.exports = mongoose.model('Notification', notificationSchema);