newest
suspend fun newestMessageMetadataWithBackend(backend: BackendSource, ids: List<ConversationId>): Map<String, MessageMetadataEntry>
The newest message metadata of each conversation, read from the backend.
A 32-character id names a legacy conversation from an imported archive. It has no backend topic, and a read that names its topic fails as a whole, so such an id is refused with InvalidArgument before any request.