update

models/GrammarMapping.js

@@ -0,0 +1,56 @@
+const { DataTypes } = require('sequelize');
+const { sequelize } = require('../config/database');
+
+const GrammarMapping = sequelize.define('GrammarMapping', {
+  id: {
+    type: DataTypes.UUID,
+    defaultValue: DataTypes.UUIDV4,
+    primaryKey: true
+  },
+  grammar_id: {
+    type: DataTypes.UUID,
+    allowNull: false,
+    references: {
+      model: 'grammars',
+      key: 'id'
+    },
+    onDelete: 'CASCADE',
+    comment: 'Foreign key to grammars table'
+  },
+  book_id: {
+    type: DataTypes.STRING(100),
+    allowNull: false,
+    comment: 'Book identifier (e.g., "global-success-2")'
+  },
+  grade: {
+    type: DataTypes.INTEGER,
+    allowNull: false,
+    comment: 'Grade level'
+  },
+  unit: {
+    type: DataTypes.INTEGER,
+    allowNull: true,
+    comment: 'Unit number in the book'
+  },
+  lesson: {
+    type: DataTypes.INTEGER,
+    allowNull: true,
+    comment: 'Lesson number within the unit'
+  },
+  context_note: {
+    type: DataTypes.TEXT,
+    allowNull: true,
+    comment: 'Additional context about where this grammar appears'
+  }
+}, {
+  tableName: 'grammar_mappings',
+  timestamps: true,
+  indexes: [
+    { fields: ['grammar_id'] },
+    { fields: ['book_id'] },
+    { fields: ['grade'] },
+    { fields: ['book_id', 'grade', 'unit', 'lesson'] }
+  ]
+});
+
+module.exports = GrammarMapping;