first commit

apps/backend/src/models/budget.model.ts

@@ -0,0 +1,18 @@
+import mongoose, { type InferSchemaType } from 'mongoose';
+
+const budgetSchema = new mongoose.Schema(
+  {
+    category: { type: String, required: true },
+    amount: { type: Number, required: true, min: 0 },
+    currency: { type: String, default: 'CNY' },
+    period: { type: String, enum: ['monthly', 'weekly'], default: 'monthly' },
+    threshold: { type: Number, min: 0, max: 1, default: 0.8 },
+    usage: { type: Number, min: 0, default: 0 },
+    userId: { type: mongoose.Schema.Types.ObjectId, ref: 'User', required: false }
+  },
+  { timestamps: true }
+);
+
+export type BudgetDocument = InferSchemaType<typeof budgetSchema>;
+
+export const BudgetModel = mongoose.models.Budget ?? mongoose.model('Budget', budgetSchema);