What is Idempotency in Laravel, and what role does it play in a real application?

What is Idempotency in Laravel, and what role does it play in a real application? In Laravel, idempotency should be understood as part of a larger application architecture rather than as an isolated API call. Queued jobs should be designed so retrying them does not accidentally duplicate irreversible business effects. A strong understanding includes its purpose, the layer where it belongs, the data or request flow it affects, and the situations where another mechanism may be more appropriate. Practical context: Laravel queues move slow tasks into background workers so web requests can respond without waiting for lengthy operations. The specific focus here is idempotency: Queued jobs should be designed so retrying them does not accidentally duplicate irreversible business effects. This question is designed to test not only terminology, but also how the concept fits into Laravel's request, application, database, security, or deployment workflow.