What is a Durable Execution?

A normal in-memory function loses all its progress if the process running it dies partway through. Durable execution frameworks checkpoint each completed step (and its output) to durable storage, so a workflow that's ten steps into a thirty-step process can pick up at step eleven after a crash rather than re-running steps one through ten or failing outright. This matters enormously for workflows involving external side effects — you don't want to accidentally re-send an email or re-charge a card because a retry re-ran a step that already succeeded. The pattern typically pairs with idempotency keys on each step, so even if a step's completion record is ambiguous, re-running it is safe. It's especially valuable for agentic workflows, which can involve many sequential tool calls over minutes or hours — a single transient network blip shouldn't force the whole task to restart. Durable execution is what separates a genuinely reliable automation platform from a demo that only works when nothing goes wrong.