root_listeners

Custom values

The TypedDict has total=False set intentionally to:

• Allow partial configs to be created and merged together via merge_configs
• Support config propagation from parent to child runnables via var_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"]}