The alternative is a path handoff, which is what the speaker-analysis boundary does for bulk audio -- and it puts an owner's frames at rest outside the journal and outside retention, with a cleanup step a killed child never runs. Content crossing this boundary is in flight or it is nowhere. The cost is real and belongs in the contract rather than in a consumer's surprise: a screen recording's frames are megabytes each going in, so a client must write requests and read responses concurrently or it deadlocks both sides.