Stateful vs Stateless AI Agents

When agents need durable run state, HITL suspend, and recovery — and when a stateless request/response loop is enough.

A stateless agent treats each request as independent: prompt in, answer out. That is enough for many read-only assistants.

A stateful / durable agent keeps run state across turns, failures, and human waits. You need that when:

A tool call requires human approval mid-flight
Work spans minutes or hours
The process may crash and must resume

HazelJS Agent OS stores durable runs (DurableRunStore), supports worker leases, and resumes HITL after restart when durable suspend is enabled. That composition is what we call the durable kernel — not a separate npm package.

Avoid:

while (true) {
  await agent.run();
}

…unless you accept losing in-memory state on every crash.

Stateful vs Stateless AI Agents

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