diff --git a/garnet/bin/zxdb/client/process_impl.cc b/garnet/bin/zxdb/client/process_impl.cc
index 8979341..ec52d43 100644
--- a/garnet/bin/zxdb/client/process_impl.cc
+++ b/garnet/bin/zxdb/client/process_impl.cc
@@ -255,7 +255,6 @@
 }
 
 void ProcessImpl::OnSymbolLoadFailure(const Err& err) {
-  TIME_BLOCK();
   for (auto& observer : observers())
     observer.OnSymbolLoadFailure(this, err);
 }
diff --git a/garnet/bin/zxdb/client/session.cc b/garnet/bin/zxdb/client/session.cc
index a81d3e9..e6dd999 100644
--- a/garnet/bin/zxdb/client/session.cc
+++ b/garnet/bin/zxdb/client/session.cc
@@ -603,6 +603,9 @@
                                    std::vector<char> data) {
   debug_ipc::MessageReader reader(std::move(data));
 
+  DEBUG_LOG() << "Got " << debug_ipc::MsgHeader::TypeToString(header.type)
+              << " notification.";
+
   switch (header.type) {
     case debug_ipc::MsgHeader::Type::kNotifyProcessExiting: {
       debug_ipc::NotifyProcessExiting notify;
diff --git a/src/developer/debug/debug_agent/debug_agent.cc b/src/developer/debug/debug_agent/debug_agent.cc
index cb576b0..8d845a6 100644
--- a/src/developer/debug/debug_agent/debug_agent.cc
+++ b/src/developer/debug/debug_agent/debug_agent.cc
@@ -41,12 +41,11 @@
 
 DebugAgent::~DebugAgent() = default;
 
-void DebugAgent::OnProcessStart(const std::string& filter, zx::process process,
-                                zx::thread initial_thread) {
+void DebugAgent::OnProcessStart(const std::string& filter,
+                                zx::process process) {
   TIME_BLOCK();
   auto process_koid = KoidForObject(process);
   auto process_name = NameForObject(process);
-  auto thread_koid = KoidForObject(initial_thread);
 
   debug_ipc::NotifyProcessStarting notify;
   notify.koid = process_koid;
@@ -73,13 +72,6 @@
   create_info.handle = std::move(process);
   create_info.resume_initial_thread = false;
   AddDebuggedProcess(std::move(create_info));
-
-  // Attached to the process. At that point it will get a new thread
-  // notification for the initial thread which it can stop or continue as it
-  // desires. Therefore, we can always resume the thread in the "new process"
-  // exception.
-  debug_ipc::MessageLoopTarget::Current()->ResumeFromException(
-      thread_koid, initial_thread, 0);
 }
 
 void DebugAgent::RemoveDebuggedProcess(zx_koid_t process_koid) {
@@ -531,6 +523,8 @@
 
 void DebugAgent::LaunchProcess(const debug_ipc::LaunchRequest& request,
                                debug_ipc::LaunchReply* reply) {
+  FXL_DCHECK(!request.argv.empty());
+  DEBUG_LOG() << "Launching binary " << request.argv.front();
   Launcher launcher(services_);
   reply->inferior_type = debug_ipc::InferiorType::kBinary;
 
diff --git a/src/developer/debug/debug_agent/debug_agent.h b/src/developer/debug/debug_agent/debug_agent.h
index 48075b8..982ecec 100644
--- a/src/developer/debug/debug_agent/debug_agent.h
+++ b/src/developer/debug/debug_agent/debug_agent.h
@@ -44,8 +44,7 @@
 
   void RemoveBreakpoint(uint32_t breakpoint_id);
 
-  void OnProcessStart(const std::string& filter, zx::process,
-                      zx::thread initial_thread) override;
+  void OnProcessStart(const std::string& filter, zx::process) override;
 
   bool should_quit() const { return should_quit_; }
 
diff --git a/src/developer/debug/debug_agent/debugged_job.cc b/src/developer/debug/debug_agent/debugged_job.cc
index ca5dbde..20c2518 100644
--- a/src/developer/debug/debug_agent/debugged_job.cc
+++ b/src/developer/debug/debug_agent/debugged_job.cc
@@ -40,7 +40,7 @@
 
   zx::process process = GetProcessFromKoid(process_koid);
   auto proc_name = NameForObject(process);
-  zx::thread thread = ThreadForKoid(process.get(), thread_koid);
+  zx::thread initial_thread = ThreadForKoid(process.get(), thread_koid);
 
   // Tools like fx serve will connect every second or so to the target, spamming
   // logging for this with a lot of "/boot/bin/sh" starting.
@@ -71,9 +71,16 @@
   if (matching_filter) {
     DEBUG_LOG() << "Filter " << matching_filter->filter << " matches process "
                 << proc_name << ". Attaching.";
-    handler_->OnProcessStart(matching_filter->filter, std::move(process),
-                             std::move(thread));
+    handler_->OnProcessStart(matching_filter->filter, std::move(process));
   }
+
+  // Attached to the process. At that point it will get a new thread
+  // notification for the initial thread which it can stop or continue as it
+  // desires. Therefore, we can always resume the thread in the "new process"
+  // exception.
+  debug_ipc::MessageLoopTarget::Current()->ResumeFromException(
+      thread_koid, initial_thread, 0);
+
 }
 
 void DebuggedJob::SetFilters(std::vector<std::string> filters) {
diff --git a/src/developer/debug/debug_agent/debugged_job.h b/src/developer/debug/debug_agent/debugged_job.h
index 6c7e814..d3fca28 100644
--- a/src/developer/debug/debug_agent/debugged_job.h
+++ b/src/developer/debug/debug_agent/debugged_job.h
@@ -28,8 +28,8 @@
   //
   // The DebuggedJob matching filter passed in case the handler is tracking from
   // which this event comes from.
-  virtual void OnProcessStart(const std::string& filter, zx::process process,
-                              zx::thread thread) = 0;
+  virtual void OnProcessStart(const std::string& filter,
+                              zx::process process) = 0;
 };
 
 class DebuggedJob : public debug_ipc::ZirconExceptionWatcher {
diff --git a/src/developer/debug/debug_agent/integration_tests/debugged_job_test.cc b/src/developer/debug/debug_agent/integration_tests/debugged_job_test.cc
index a8558ab..c535421 100644
--- a/src/developer/debug/debug_agent/integration_tests/debugged_job_test.cc
+++ b/src/developer/debug/debug_agent/integration_tests/debugged_job_test.cc
@@ -205,7 +205,7 @@
 
 }  // namespace
 
-TEST(DebuggedJobIntegrationTest, DISABLED_OneProcess) {
+TEST(DebuggedJobIntegrationTest, RepresentativeScenario) {
   MessageLoopWrapper message_loop_wrapper;
   MessageLoop* message_loop = message_loop_wrapper.loop();
 
diff --git a/src/developer/debug/debug_agent/main.cc b/src/developer/debug/debug_agent/main.cc
index e3b2cce..717a2c0 100644
--- a/src/developer/debug/debug_agent/main.cc
+++ b/src/developer/debug/debug_agent/main.cc
@@ -172,8 +172,9 @@
   static std::map<std::string, std::string> options = {
       {"auwind", R"(
       [Experimental] Use the unwinder from AOSP.)"},
-      {"async-message-loop", R"(
-      [Experimental] Use async-loop backend message loop.)"},
+      {"legacy-message-loop", R"(
+      [DEPRECATED] Use the originalbackend message loop.
+                   Will be removed eventually.)"},
       {"debug-mode", R"(
       Run the agent on debug mode. This will enable conditional logging messages
       and timing profiling. Mainly useful for people developing zxdb.)"},
@@ -239,11 +240,11 @@
     debug_agent::SetUnwinderType(debug_agent::UnwinderType::kAndroid);
   }
 
-  // By default use the original agent message loop.
-  auto message_loop_type = MessageLoopTarget::Type::kZircon;
-  if (cmdline.HasOption("async-message-loop")) {
+  // By default use the async agent message loop.
+  auto message_loop_type = MessageLoopTarget::Type::kAsync;
+  if (cmdline.HasOption("legacy-message-loop")) {
     // Use new async loop.
-    message_loop_type = MessageLoopTarget::Type::kAsync;
+    message_loop_type = MessageLoopTarget::Type::kZircon;
   }
 
   if (cmdline.HasOption("debug-mode")) {