Subgraphs

What are Subgraphs?

A subgraph is simply a graph used as a node inside another graph. Think of it as encapsulation for LangGraph: each subgraph is a self-contained unit that can be combined to build larger, more complex systems.

When should I use this?

Subgraphs are useful when you need to structure a graph into smaller, reusable pieces. They let you build multi-agent systems, reuse node sets across multiple graphs, and let different teams develop separate parts of a graph independently.

How does CopilotKit support this?

CopilotKit supports streaming directly from subgraphs, so nested graphs can emit events in real time just like a single graph.

Using this feature requires no extra steps on the agent side. All you need to do, is to enable subgraph streaming in the useCoAgent hook:

  const { state, nodeName } = useCoAgent<AgentState>({
    name: "sample_agent",
    initialState: INITIAL_STATE,
    config: {
      streamSubgraphs: true, 
    }
  });

The subgraph nodes will stream as usual, and you will be able to see which subgraph is streaming using the nodeName variable. You can also use interrupt() directly from a subgraph.