dynamic_interrupt

Dynamic Interrupt Example

This example demonstrates the Dynamic Interrupt feature in LangGraphGo, similar to Python LangGraph's interrupt function.

1. Background

Dynamic interrupts allow a node to pause execution at runtime and wait for external input (e.g., from a human). Unlike static InterruptBefore configuration, this allows the decision to interrupt to be made inside the node's logic.

2. Key Concepts

• graph.Interrupt(ctx, value): A function that can be called inside a node.
  • If called for the first time, it stops execution and returns a GraphInterrupt error containing the value.
  • If called during resumption (with a ResumeValue provided), it returns the ResumeValue and continues execution.
• Config.ResumeValue: The value provided when resuming execution, which will be returned by graph.Interrupt.

3. How It Works

1. Initial Run: The graph runs until it hits graph.Interrupt("What is your name?").
2. Interruption: The Invoke method returns a GraphInterrupt error. We catch this error and see the query.
3. User Input: We simulate getting input ("Alice") from the user.
4. Resume: We call Invoke again, but this time passing ResumeValue: "Alice" in the config.
5. Replay: The node runs again. graph.Interrupt sees the resume value and returns "Alice" immediately. The node continues to finish.

4. Code Highlights

Inside the Node

name, err := graph.Interrupt(ctx, "What is your name?")
if err != nil {
    return nil, err // Propagate the interrupt
}
// Use the input
return fmt.Sprintf("Hello, %v!", name), nil

Handling the Interrupt

_, err := runnable.Invoke(ctx, nil)
if interrupt, ok := err.(*graph.GraphInterrupt); ok {
    // Get user input...
    config := &graph.Config{ResumeValue: userInput}
    // Resume
    runnable.InvokeWithConfig(ctx, nil, config)
}

5. Running the Example

go run main.go