Base abstract message class.
Messages are the inputs and outputs of a chat model.
Examples include HumanMessage,
AIMessage, and
SystemMessage.
Fake chat models for testing purposes.
Configuration for a Runnable.
Custom values
The TypedDict has total=False set intentionally to:
merge_configsvar_child_runnable_config (a ContextVar that automatically passes
config down the call stack without explicit parameter passing), where
configs are merged rather than replaced# Parent sets tags
chain.invoke(input, config={"tags": ["parent"]})
# Child automatically inherits and can add:
# ensure_config({"tags": ["child"]}) -> {"tags": ["parent", "child"]}