A causal event chain links each event to the event, request or action that produced it. The resulting lineage lets a system distinguish chronological proximity from actual causation and trace a final output back through every relevant step.
Causal links are useful when concurrent agents process many events at once. They support debugging, auditing and replay by showing which prompt, tool call and intermediate result belonged to a particular workflow rather than relying only on timestamps.
ELI5
A causal event chain records which earlier request or action produced each later event. It shows why something happened rather than only listing events in time order.
For example, a tool result can point to the exact agent call that created it, which points to the user request that started the workflow. When several agents work at once, those links help maintainers trace one failure without confusing it with an unrelated event that happened nearby.
