What common mistake do developers make with Idempotency, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Idempotency, why does the mistake cause problems, and what is the safer approach? One recurring problem with idempotency is applying it without understanding the boundary it protects. Assuming a queued job runs exactly once; workers can retry jobs, so external side effects should be made idempotent where possible. In addition, Queued jobs should be designed so retrying them does not accidentally duplicate irreversible business effects. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.