When working with non-deterministic systems that make model-based decisions (e.g., agents powered by LLMs), it can be useful to examine their decision-making process in detail:
  1. 🤔 Understand reasoning: Analyze the steps that led to a successful result.
  2. 🐞 Debug mistakes: Identify where and why errors occurred.
  3. 🔍 Explore alternatives: Test different paths to uncover better solutions.
LangGraph provides time travel functionality to support these use cases. Specifically, you can resume execution from a prior checkpoint — either replaying the same state or modifying it to explore alternatives. In all cases, resuming past execution produces a new fork in the history.
For information on how to use time travel, see Use time travel and Time travel using Server API.