Idempotency Key

An idempotency key is a unique identifier you attach to a request so that running it twice has the same effect as running it once. In automation, the same trigger often fires more than once — a webhook is redelivered, a scenario is replayed after an error, a polling step re-reads a row before your status update saved. Without protection, each retry creates a duplicate: two charges, two Slack messages, two rows. Why it matters: reliable automations must assume every step can run again, and the cheapest defense is a key derived from the event itself (an order ID, a message ID) that the downstream system uses to recognize and ignore repeats. Practical note: many payment and messaging APIs accept an idempotency key header directly; when a tool doesn't, store processed keys in a data store and add a filter that drops any event whose key you've already seen before doing the real work.