An external reference ID is your own identifier, such as a work order task number, attached to a ResolveGrid session so that events and summaries route straight back to the right record.
When your system creates a session, it passes the ID it already uses for the job. ResolveGrid carries that ID on every event and summary it sends back.
Your integration never has to look up which session belongs to which job. The answer travels with the data.
Every session, webhook, and summary in the ResolveGrid API carries the external reference you supplied, whether the session was created by a person, an integration, or an AI agent.