Idempotency Is the Hidden Requirement of Automation

Automated systems retry tasks when something fails. Network blip, timeout, transient error—the task runs again. That's good. Unless the operation isn't idempotent.

Idempotent means safe to run multiple times. Running it once or five times produces the same result. No duplicates, no accumulated side effects.

If operations are not idempotent, retries can create duplicates—two database rows instead of one, two notifications instead of one—or corrupt state. We learned this the hard way when certain tasks ran twice and produced conflicting results. A task that "creates a record" ran twice and created two records. A task that "updates status" ran twice and overwrote a subsequent update.

Automation requires every operation to be safe to repeat.