Example

{
  "type": "session.usage.updated",
  "event_id": "evt_usage_001",
  "usage": {
    "seconds": 32.5
  },
  "context_window": {
    "usage_ratio": 0.12
  }
}

session.closed

Returned after the Live session finishes finalizing, with the close reason, final session snapshot, and cumulative audio usage. A connection closing without this event does not confirm successful finalization.