Double-booking is a classic race: two sessions see the same slot until one commits. At the database layer We rely on Laravel transactions that lock the inventory row for the candidate range so the second request blocks or fails fast with a clear domain error.
The booking flow stays one narrative from availability check to Stripe confirmation. Splitting that into multiple “maybe” steps trains users to abandon at the worst moment; a single atomic pipeline with explicit states is easier to reason about and log.
MySQL indexing matters as much as locking: queries that scan huge ranges under load will still hurt. We align indexes with how we query availability by vehicle and date range.
Frontend feedback mirrors backend state: if inventory moved, the user sees it immediately–not a generic error after payment. That pairing of Laravel discipline and UX clarity is what makes high-concurrency reservations survivable in production.
