unread_count is present when the update was triggered by an inbound message; last_message_at is present on both the inbound and the API-send paths.{
"conversation_uuid": "2b7c1a90-95f3-4a1e-bb0e-1d4b6f0f9c22",
"contact_uuid": "9c2e4f31-7a55-4d0b-8f6a-2c9d1e5b7a03",
"channel_uuid": "123e4567-e89b-12d3-a456-426614174000",
"status": "open",
"unread_count": 2,
"last_message_at": "2026-08-25T14:31:09.412-03:00"
}