Translates a Vapi end-of-call-report into one Agnost voice conversation. The Vapi call ID becomes the conversation ID, the caller number becomes the user ID, and each caller/assistant exchange becomes an event. The completed call total is attached to exactly one event so conversation cost aggregation does not multiply it by the turn count.

The caller number may be supplied in either message.call.customer.number or message.customer.number. Transcript content may be supplied in message.artifact.messages, message.artifact.transcript, or message.transcript. Internal function calls found in the artifact are stored as child tool events beneath their synthetic agent tool-call events, including their arguments, results, timing, and success state.