> It's much easier to remove namespaces later using `using namespaces`

lol how? sed? that's not a "much easier", that's a hack. it's actually much easier to remove `using namespace` because then the compiler will catch resolution errors.

i actually didn't notice this was a header in which ok fine don't use `using namespace` but still this is java EE levels of boiler plate you've got going on;

  void SetupInput(const basis::UnitInitializeOptions &options,
                  basis::core::transport::TransportManager *transport_manager,
                  basis::core::containers::SubscriberQueueSharedPtr &subscriber_queue,
                  basis::core::threading::ThreadPool *thread_pool,
                  const std::unordered_map<std::string, std::string> &templated_topic_to_runtime_topic) {

this signature is 90% namespace resolution - i have to squint to actually find the types...