The datafeed.source.* event family is a public abstraction over the internal datasource.* events; the gateway transparently maps event names, filters, and delivered payloads in both directions, so callers always work in datafeed.source.*/datafeed-id terms. A request mixing datafeed.source.* and other events fans out into independent subscriptions that are settled independently, so one failing does not drop the other. Requires the api:write scope.