Preventing Invalid Transitions

In a standard Python script, complex state management is hard. "Wait, can the user go from 'Payment' back to 'Cart'?"

Visual Auditing

In LangGraph, you define the only valid edges.

graph TD
    Cart --> Checkout
    Checkout --> Payment
    Payment -- Success --> OrderPlaced
    Payment -- Failure --> Checkout
    
    %% Notice: No edge from Payment -> Cart.
    %% It is physically impossible for the code to jump that way.

This makes auditing easy. You don't need to read 1000 lines of code to see if a transition is possible. You just look at the graph definition. If the edge isn't there, the transition can't happen.