Appointment booking MVP: prevent double bookings before adding features

A booking app's central promise is that the confirmed slot will actually be available. Calendar styling, reminders and customer profiles are useful, but the first release should make reservation behavior unambiguous under concurrent use.

1. 01

   Start by identifying the resource being reserved. A practitioner, a room and a piece of equipment may have different availability. If an appointment needs both a person and a room, a free time on one calendar is insufficient. Write this rule into the data model and the acceptance criteria.

2. 02

   Distinguish a temporary hold from a confirmed booking. Decide when a hold expires and whether a payment or staff approval is needed before confirmation. Two people attempting the same slot should not both receive success. The server must enforce that rule; checking availability only when the page loads leaves a gap.

3. 03

   Use concrete time examples in testing. Show the same booking to users in two time zones, test an appointment that crosses midnight and check a daylight-saving transition relevant to the operating location. Store an unambiguous appointment time and preserve the location context needed to display it correctly.

4. 04

   Define cancellation and rescheduling as state changes. Does moving an appointment release its previous slot immediately? What happens if the new slot becomes unavailable during the change? Can a staff member override a rule, and is the reason recorded? These questions are part of the core workflow rather than advanced administration.

5. 05

   A pilot checklist should include simultaneous reservations, an expired hold, repeated requests and a failed confirmation email. Email failure must not create a second booking or erase a valid one. Measure completed bookings and the number of reservations that require staff correction. That combination shows whether the first release saves coordination work instead of merely shifting it into support.