Rework self-service kiosk account lookup for privacy and safety (1.3.2)

Replaces the explicit "look up existing account" search field with automatic
lookup as email/phone are entered, requires operator confirmation before any
matched account's name/email/phone/preference is changed, adds a password
show/hide toggle, and fixes two bugs found during testing: entering a phone
number belonging to a different account could silently overwrite the form
with that account's details, and re-checking an unchanged field (e.g. from
tapping a ticket quantity button) could revert edits already made. Also adds
a server-side check rejecting registrations whose email and phone resolve to
two different existing accounts, as defense in depth.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "event-management-backend",
-  "version": "1.3.1",
+  "version": "1.3.2",
   "description": "Event Management System Backend",
   "main": "src/index.js",
   "scripts": {

backend/src/controllers/registrationController.js

@@ -764,32 +764,66 @@ const createManualRegistration = async (req, res) => {
       ? prefFromBody
       : (hasValidEmail && phone ? 'both' : phone ? 'whatsapp' : 'email');
 
-    // Always search by email AND/OR phone regardless of guestOnly
-    // Also try the alternate format (27xxx ↔ 0xxx) so both representations match
+    // Always search by email AND/OR phone regardless of guestOnly.
+    // Resolve each channel independently (rather than a single findFirst with an OR
+    // across both) so that an email belonging to one account and a phone number
+    // belonging to a *different* account can never be silently collapsed into
+    // whichever record happens to match first — that would let a registration
+    // hijack or corrupt someone else's account. Also try the alternate phone
+    // format (27xxx ↔ 0xxx) so both representations match.
     const phoneAlt = phone && phone.startsWith('27') ? '0' + phone.slice(2) : (phone && phone.length === 9 ? '27' + phone : null);
-    const searchClauses = [
-      ...(hasValidEmail ? [{ email: user.email }] : []),
-      ...(phone ? [{ phoneNumber: phone }] : []),
-      ...(phoneAlt ? [{ phoneNumber: phoneAlt }] : []),
-    ];
-    const existingUser = searchClauses.length > 0
-      ? await prisma.user.findFirst({ where: { OR: searchClauses } })
+    const emailUser = hasValidEmail
+      ? await prisma.user.findUnique({ where: { email: user.email } })
       : null;
+    const phoneUser = phone
+      ? await prisma.user.findFirst({ where: { OR: [{ phoneNumber: phone }, ...(phoneAlt ? [{ phoneNumber: phoneAlt }] : [])] } })
+      : null;
+
+    if (emailUser && phoneUser && emailUser.id !== phoneUser.id) {
+      res.status(409);
+      throw new Error(
+        `This email and phone number belong to two different existing accounts (${emailUser.name} vs ${phoneUser.name}). Please verify the visitor's details before registering.`
+      );
+    }
+
+    const existingUser = emailUser || phoneUser || null;
 
     if (existingUser) {
       userId = existingUser.id;
       const updateData = {};
-      // Update preference only when the caller explicitly specified one
-      if (prefFromBody && validPrefs.includes(prefFromBody)) {
-        updateData.notificationPreference = prefFromBody;
+      // The kiosk shows the operator a diff of name/email/phone against the matched
+      // account and requires explicit confirmation before submitting, so any
+      // difference reaching this point is an already-confirmed correction — apply
+      // it as a full overwrite rather than only filling in blanks.
+      if (user.name && user.name.trim() && user.name.trim() !== existingUser.name) {
+        updateData.name = user.name.trim();
       }
-      // Fill in a missing contact channel with the newly supplied value, without overwriting an existing one
-      if (phone && !existingUser.phoneNumber) {
+      if (phone && phone !== existingUser.phoneNumber) {
         updateData.phoneNumber = phone;
       }
-      if (hasValidEmail && existingUser.email !== user.email && existingUser.email.endsWith('@guest.local')) {
+      if (hasValidEmail && existingUser.email !== user.email) {
         updateData.email = user.email;
       }
+
+      // Update preference only when the caller explicitly specified one, but validate it
+      // against the contact info that will actually be on the account after this update —
+      // a stale "whatsapp"/"both" preference must not survive a phone number being
+      // removed, nor "email" survive an email being cleared in favor of a real phone.
+      if (prefFromBody && validPrefs.includes(prefFromBody)) {
+        const { isValidZAPhone } = require('../utils/whatsapp');
+        const finalPhone = updateData.phoneNumber !== undefined ? updateData.phoneNumber : existingUser.phoneNumber;
+        const finalEmail = updateData.email !== undefined ? updateData.email : existingUser.email;
+        const finalEmailValid = !!(finalEmail && !finalEmail.endsWith('@guest.local'));
+        let candidatePref = prefFromBody;
+        if ((candidatePref === 'whatsapp' || candidatePref === 'both') && !isValidZAPhone(finalPhone)) {
+          candidatePref = finalEmailValid ? 'email' : candidatePref;
+        }
+        if (candidatePref === 'email' && !finalEmailValid && isValidZAPhone(finalPhone)) {
+          candidatePref = 'whatsapp';
+        }
+        updateData.notificationPreference = candidatePref;
+      }
+
       if (Object.keys(updateData).length > 0) {
         await prisma.user.update({ where: { id: userId }, data: updateData }).catch(() => {});
       }

backend/src/controllers/userController.js

@@ -482,7 +482,7 @@ const checkUserExists = async (req, res) => {
 
     const existingUser = await prisma.user.findFirst({
       where: { OR: searchClauses },
-      select: { name: true, email: true, phoneNumber: true, notificationPreference: true },
+      select: { id: true, name: true, email: true, phoneNumber: true, notificationPreference: true },
     });
 
     const hasEmail = !!existingUser?.email && !existingUser.email.endsWith('@guest.local');
@@ -494,7 +494,11 @@ const checkUserExists = async (req, res) => {
       hasPhone,
       // Safe-to-display fields only, for autofilling a lookup form — never the password.
       // Guest placeholder emails are withheld the same way hasEmail already treats them.
+      // `id` lets the kiosk tell two different matched accounts apart (e.g. when the
+      // typed email and phone number resolve to different people) — it's never shown,
+      // only compared client-side, and this endpoint is already Private/Supervisor.
       user: existingUser ? {
+        id: existingUser.id,
         name: existingUser.name,
         email: hasEmail ? existingUser.email : null,
         phoneNumber: hasPhone ? existingUser.phoneNumber : null,