PerformMessageQuery: Add comment regarding sort assumption

server/server.go

@@ -154,6 +154,7 @@ func (s *Server) PerformMessageQuery(query *MessagesQuery) []model.Message {
 	})
 
 	// Apply before/after filters
+	// The following code assumes the messages are sorted by date ascending
 	if query.BeforeGUID != nil {
 		beforeGUID := *query.BeforeGUID
 		for i := range messages {