We've made several improvements to the open-source LangGraph library:

• For MessageGraph and add_messages state reducer, a built-in ability to remove a previous message from the list by sending a RemoveMessage(id=... message to your messages channel. This unlocks more human in the loop scenarios.

• Checkpointing of pending writes. This improves error recovery for graphs with parallel nodes. Now, when multiple nodes run in parallel, we checkpoint each node's results as they finish, guaranteeing that they won't be re-done if another node later fails.

• Ability to render metadata key-value pairs in mermaid drawings of graphs. One use case is to mark a version/variant of a node being used when iterating on a graph.