Add sessionHolding template, unique 8-digit codes, reason slot for sessionCancelled, and disable unused notifications

utils/mongooseUniqueCodePlugin.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const { generateUniqueCode } = require('./uniqueCode');
+
+/**
+ * Mongoose plugin: auto-assigns an 8-digit uniqueCode before validation if missing.
+ */
+const uniqueCodePlugin = (schema, options = {}) => {
+  const field = options.field || 'uniqueCode';
+
+  schema.add({
+    [field]: {
+      type: String,
+      unique: true,
+      sparse: true,
+      trim: true,
+      index: true
+    }
+  });
+
+  schema.pre('validate', async function assignUniqueCode(next) {
+    if (this[field]) return next();
+    try {
+      this[field] = await generateUniqueCode(this.constructor, field);
+      return next();
+    } catch (err) {
+      return next(err);
+    }
+  });
+};
+
+module.exports = uniqueCodePlugin;