subgraphs

Subgraphs (Composition) Example

Background

As Agent systems grow in complexity, managing a single monolithic graph becomes unwieldy. Subgraphs allow developers to encapsulate logic into smaller, reusable graphs and compose them into larger systems. This is analogous to breaking a large program into functions or microservices. A subgraph appears to the parent graph as just another node, but internally it manages its own state and execution flow.

Features

• Encapsulation: Hide the complexity of a sub-task (e.g., "Research Topic") behind a single node.
• Reusability: Define a graph once and use it in multiple places or projects.
• State Mapping: Automatically passes the parent's state to the child and merges the child's result back (assuming compatible schemas).

Implementation Principle

The AddSubgraph method in graph/subgraph.go wraps a MessageGraph (or StateGraph) into a Subgraph struct.

1. The subgraph is compiled into a Runnable.
2. A wrapper function is created that matches the Node signature (func(ctx, state) (interface{}, error)).
3. When executed, this wrapper invokes the subgraph's Runnable.Invoke.
4. The result is returned to the parent graph as the node's output.

Code Walkthrough

In main.go:

1. Child Graph: Defined as a simple graph that adds a "child_trace" to the state.

2. Parent Graph: Defined as a graph that adds "parent_trace".

3. Composition:

   parent.AddSubgraph("nested_graph", child)
   

   The child graph is registered as a node named "nested_graph".

4. Wiring: start -> nested_graph -> end. The parent graph treats "nested_graph" like any other node.

How to Run

go run main.go