멀티 에이전트 오케스트레이션 패턴 템플릿 (SPEC §6, R5; 트렌드 보고서 Tier 2.5).

빌딩 블록은 기존 프리미티브뿐이다 — 조건부 엣지 + 노드(워커) + :messages 채널. 신규 추상화 없이, 자주 쓰는 멀티 에이전트 형태를 미리 조립한 컴파일된 그래프로 제공한다.

supervisor (오케스트레이터-워커)

오케스트레이터 노드가 LLM으로 다음 워커를 고르고(또는 종료), 조건부 엣지가 해당 워커로 라우팅한다. 워커는 결과를 :messages에 append하고 오케스트레이터로 복귀한다. max_steps로 라운드 폭주를 막는다.

workers = [
  %{name: :researcher, description: "gathers facts", run: &MyApp.research/2},
  %{name: :writer, description: "writes the answer", run: &MyApp.write/2}
]
graph = ElGraph.Orchestration.supervisor(llm, workers, system: "...")
ElGraph.invoke(graph, %{messages: [ElGraph.LLM.user("Write a report")]})

magentic (task-ledger)

magentic/3 is supervisor/3 plus a task ledger and a stall guard (magentic-one pattern). The ledger (:ledger channel) records every worker the orchestrator chooses; when the same worker is picked more than :max_stalls times in a row the run is forced to terminate, defusing the classic "agent loops forever" failure.

Cross-agent handoff

In both templates worker results flow back to the orchestrator purely via the shared :messages channel — a worker appends its output and the orchestrator reads the full transcript on its next turn. Direct, out-of-band handoff between agents is also expressible without new orchestration code: have a worker emit on the signal bus (ElGraph.Skills.SignalReAct :emit) and have the target worker subscribe — the bus delivers the payload independently of the :messages transcript. The orchestration templates here deliberately stick to :messages; the signal bus is the escape hatch when you need agent-to-agent side-channels.