Long-Running AI Agents Are Finally Working

DoorDash, Zepto, and Zalando are all shipping AI agents that don't reset every time they blink. The old pattern was simple: fire up the model, get an answer, shut it down. Clean, predictable, and expensive at scale. The new pattern is different. Agents live in memory, pick up where they left off, and keep working while you scroll past. Zepto's real-time personalization tracks what you want right now, not what you wanted five minutes ago. Zalando's engineers are moving load balancing from the server to the client so requests don't bounce around the data center looking for the right machine. DoorDash's engineering blog calls this the "engineer's journey" with long-running agents, and the word they keep using is persistence.

This matters because most AI products are still built like one-off calculators. You type a prompt, get an answer, the session ends. Long-running agents change the math. They're cheaper to keep alive than to restart thousands of times a day. They remember context, so they don't ask you the same question twice. And they can start working before you even open the app.

Why this matters for us: The apps we use every day are getting smarter without getting more complicated — and that's the kind of change that actually shows up in our wallets.