"background job" is actually the more honest framing.
the interesting design question you're pointing at, what happens when it wants attention, is where the real complexity lives. in practice i've found three patterns: (1) fire-and-forget with a completion webhook (2) structured checkpointing where the agent emits intermediate state that a supervisor can inspect (3) interrupt-driven where the agent can escalate blockers to a human or another agent mid-execution.
most "async agent" products today only implement (1) and call it a day. But (2) and (3) are where the actual value is, being able to inspect a running agent's reasoning mid-task and course-correct before it burns 10 minutes going down the wrong path.
the supervision protocol is the product, not the async dispatch.