Complex Subgraphs¶

complex-subgraphs demonstrates a coordinator graph with specialist subgraphs and one nested grandchild graph. The OpenAI request adapter supplies the final user message as question. The keyword graph keeps its selected terms in graph state and emits an optional status update. The selected specialist writes the final assistant message to the shared messages channel.

LangGraph Topology¶

The native xray view expands the specialist and keyword subgraphs.

graph TD;
  __start__ --> route_question;
  route_question -.-> api_collect["api_contract_graph:collect_contract_checks"];
  route_question -.-> docs_extract["docs_graph:keyword_graph:extract_keywords"];
  api_summary["api_contract_graph:summarize_contract"] --> __end__;
  docs_summary["docs_graph:summarize_docs"] --> __end__;
  subgraph api_contract_graph
    api_collect --> api_summary;
  end
  subgraph docs_graph
    docs_prepare["docs_graph:keyword_graph:prepare_keyword_context"] --> docs_summary;
    subgraph keyword_graph
      docs_extract --> docs_prepare;
    end
  end

Request Flow¶

flowchart TD
  request(["UI → LGOS /v1/responses<br/>User message"]) --> adapter["request_to_input"]
  adapter --> route["Normalize question and select route"]

  subgraph api["API contract subgraph"]
    checks["Collect contract checks"] --> api_summary["Stream contract summary"]
  end

  subgraph docs["Docs specialist subgraph"]
    subgraph keywords["Keyword grandchild subgraph"]
      extract["Extract keywords"] --> prepare["Build context and emit status"]
    end
    prepare --> docs_summary["Stream docs summary"]
  end

  route -->|"API, OpenAI, adapter, stream, or serve"| checks
  route -->|"other questions"| extract
  api_summary --> output["final assistant message"]
  docs_summary --> output
  output --> response(["LGOS /v1/responses → UI<br/>Assistant text"])

LGOS exposes the answer-producing nested nodes summarize_contract and summarize_docs as assistant text. The keyword node's selected terms are available as graph state and as a status update because the graph declares GraphFeature.CLIENT_EVENTS. The final assistant message is identical for streaming and non-streaming requests. A streaming Responses request receives the status as commentary without a metadata opt-in. Chat Completions ignores custom stream events and returns only the final assistant text.

The graph is deterministic and has no checkpointer or Store. Its routing, keywords, checks, and messages exist only for the current request. Any conversation history must come from messages supplied by the client.

Try It¶