Post-Launch Feature for Pet Grooming App – Waitlist and Last-Minute Booking System

The main iOS and Android app has now been completed and released. Customers can create pet profiles, book grooming appointments, make payments through Stripe, and receive push notifications. After using the app in production, we identified one additional feature that would help us reduce lost appointment slots caused by last-minute cancellations. We would like to add a simple waitlist and last-minute booking system to the existing React Native application. When a customer’s preferred appointment time is unavailable, they should be able to join a waitlist for a specific day or time range. If another customer cancels, the backend should automatically identify eligible customers and send a push notification that the slot is available. The first customer to accept the offer should be able to confirm the appointment through the app. The system needs to prevent two customers from claiming the same slot. The additional work includes: Add a “Join Waitlist” option to the existing booking flow Allow customers to select preferred dates or time ranges Trigger push notifications when matching appointments become available Add a time limit for accepting an available slot Update the backend and REST APIs Prevent duplicate or conflicting bookings Add basic waitlist management to the admin dashboard Test the feature on both iOS and Android This is an extension of the existing project, so the current authentication, user roles, booking system, and backend architecture should be reused rather than rebuilt.