Prevent Duplicate API Calls With Idempotency: Patterns That Work

A failure pattern I have seen repeatedly in enterprise integrations: a payment request times out at the caller, succeeds downstream, and is then retried as though it failed. MuleSoft projects, this is especially easy to miss because a single inbound request may trigger payment, ERP, inventory, and messaging calls before the caller receives a final response. It succeeded 2 times.