2V1-d: offline login -> select -> loading against a fake 40250 server

port.login_flow drives the real 40250 root scripts through the ported
CPythonNetworkStream and CAccountConnector against a loopback auth + game
server built from net/classic (wire layouts, sequence table, cipher) that
answers like the 40250 desc.cpp/input*.cpp: handshake, key agreement,
LOGIN3/AUTH_SUCCESS, LOGIN2, the character list, DirectEnter reconnect,
CHARACTER_SELECT, the loading packets and CLIENT_VERSION, with every
sequence byte checked.

- NetStream::ActivateCipher decrypts ciphertext already buffered behind
  KEY_AGREEMENT_COMPLETED (PORT)
- CPythonApplication is final (PORT): no application object exists on the
  platform yet, so its virtual overrides must be called directly
- app.GetTime (GetGlobalTime) and camera/center-position stubs
- SendClientVersionPacket verbatim in the PhaseGame stand-in

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

extension/src/platform/UserInterface/PythonApplication.cpp

@@ -49,6 +49,15 @@ void CPythonApplication::Abort()
 	PythonBoot::AppRequestQuit();
 }
 void CPythonApplication::SetMinFog(float) { MT_PLATFORM_STUB(); }
+// In 40250 Process() copies CTimer::GetCurrentSecond() into m_fGlobalTime right after Advance() and
+// this returns it. PORT: no member to hold it; the timer only advances in Process(), so reading it
+// here gives the same value.
+float CPythonApplication::GetGlobalTime() { return CTimer::Instance().GetCurrentSecond(); }
+// Camera (2V3).
+void CPythonApplication::SetEventCamera(const SCameraSetting&) { MT_PLATFORM_STUB(); }
+void CPythonApplication::SetDefaultCamera() { MT_PLATFORM_STUB(); }
+// In 40250 this stores m_v3CenterPosition for the game view (introselect.py sets it on the character list).
+void CPythonApplication::SetCenterPosition(float, float, float) { MT_PLATFORM_STUB(); }
 void CPythonApplication::SetFrameSkip(bool) { MT_PLATFORM_STUB(); }
 // PORT: 40250 creates the Win32 window, the D3D8 device, cursors, sound, keyboard, the net device,
 // fonts and the IME here. The Godot window and its canvas are the device on this platform and they

extension/src/platform/pending/UserInterface/PythonNetworkStreamPhaseGame.cpp

@@ -3,6 +3,7 @@
 // file in the commit that ports the unit into port/ (docs/PORT-PLAN.md 2V1).
 #include "UserInterface/StdAfx.h"
 #include "UserInterface/PythonNetworkStream.h"
+#include "EterBase/Filename.h"
 
 #include "../../PlatformStub.h"
 
@@ -44,10 +45,40 @@ bool CPythonNetworkStream::SendChatPacket(const char *, BYTE)
 	return mt_platform_stub_return<bool>();
 }
 
+// PORT: the 40250 body verbatim ahead of its unit: the loading phase sends it on the main-character packet.
 bool CPythonNetworkStream::SendClientVersionPacket()
 {
-	MT_PLATFORM_STUB();
-	return mt_platform_stub_return<bool>();
+	std::string filename;
+
+	GetExcutedFileName(filename);
+
+	filename = CFileNameHelper::NoPath(filename);
+	CFileNameHelper::ChangeDosPath(filename);
+
+	if (LocaleService_IsEUROPE() && false == LocaleService_IsYMIR())
+	{
+		TPacketCGClientVersion2 kVersionPacket;
+		kVersionPacket.header = HEADER_CG_CLIENT_VERSION2;
+		strncpy(kVersionPacket.filename, filename.c_str(), sizeof(kVersionPacket.filename)-1);
+		strncpy(kVersionPacket.timestamp, "1215955205", sizeof(kVersionPacket.timestamp)-1); // # python time.time 앞자리
+		//strncpy(kVersionPacket.timestamp, __TIMESTAMP__, sizeof(kVersionPacket.timestamp)-1); // old_string_ver
+		//strncpy(kVersionPacket.timestamp, "1218055205", sizeof(kVersionPacket.timestamp)-1); // new_future
+		//strncpy(kVersionPacket.timestamp, "1214055205", sizeof(kVersionPacket.timestamp)-1); // old_past
+
+		if (!Send(sizeof(kVersionPacket), &kVersionPacket))
+			Tracef("SendClientReportPacket Error");
+	}
+	else
+	{
+		TPacketCGClientVersion kVersionPacket;
+		kVersionPacket.header = HEADER_CG_CLIENT_VERSION;
+		strncpy(kVersionPacket.filename, filename.c_str(), sizeof(kVersionPacket.filename)-1);
+		strncpy(kVersionPacket.timestamp, __TIMESTAMP__, sizeof(kVersionPacket.timestamp)-1);
+
+		if (!Send(sizeof(kVersionPacket), &kVersionPacket))
+			Tracef("SendClientReportPacket Error");
+	}
+	return SendSequence();
 }
 
 bool CPythonNetworkStream::SendExchangeAcceptPacket()

extension/src/port/CMakeLists.txt

@@ -211,6 +211,15 @@ if(BUILD_TESTING AND CMAKE_SYSTEM_NAME STREQUAL CMAKE_HOST_SYSTEM_NAME)
                  COMMAND $<TARGET_FILE:port_app_loop_test> ${MT_40250_CLIENT} ${MT_PYTHON_STDLIB_ZIP})
         set_tests_properties(port.app_loop PROPERTIES SKIP_RETURN_CODE 77)
 
+        add_executable(port_login_flow_test ${CMAKE_CURRENT_SOURCE_DIR}/../../tests/port_login_flow_test.cpp
+            ${CMAKE_CURRENT_SOURCE_DIR}/../../tests/port_login_flow_server.cpp
+            ${CMAKE_CURRENT_SOURCE_DIR}/../net/classic/classic_cipher.cpp)
+        target_link_libraries(port_login_flow_test PRIVATE port_platform)
+        add_dependencies(port_login_flow_test mtpython_stdlib)
+        add_test(NAME port.login_flow
+                 COMMAND $<TARGET_FILE:port_login_flow_test> ${MT_40250_CLIENT} ${MT_PYTHON_STDLIB_ZIP})
+        set_tests_properties(port.login_flow PROPERTIES SKIP_RETURN_CODE 77)
+
         add_executable(port_python_ui_modules_test ${CMAKE_CURRENT_SOURCE_DIR}/../../tests/port_python_ui_modules_test.cpp)
         target_link_libraries(port_python_ui_modules_test PRIVATE port_platform)
         add_dependencies(port_python_ui_modules_test mtpython_stdlib)

extension/src/port/EterLib/NetStream.cpp

@@ -3006,6 +3006,12 @@ bool CNetworkStream::Activate(size_t agreed_length, const void* buffer, size_t l
 
 void CNetworkStream::ActivateCipher()
 {
-	return m_cipher.set_activated(true);
+	m_cipher.set_activated(true);
+	// PORT: __RecvInternalBuffer decrypts each recv as it arrives, so encrypted bytes the server sent right
+	// behind KEY_AGREEMENT_COMPLETED that landed in the same recv are still ciphertext. In 40250 the
+	// server's next pulse usually keeps them apart; on loopback or a fast LAN they arrive together, so
+	// decrypt the unread rest of the buffer here.
+	if (m_recvBufInputPos > m_recvBufOutputPos)
+		m_cipher.Decrypt(m_recvBuf + m_recvBufOutputPos, m_recvBufInputPos - m_recvBufOutputPos);
 }
 #endif // _IMPROVED_PACKET_ENCRYPTION_

extension/src/port/UserInterface/PythonApplication.h

@@ -42,7 +42,11 @@
 #include "AbstractApplication.h"
 #include "MovieMan.h"
 
-class CPythonApplication : public CMSApplication, public CInputKeyboard, public IAbstractApplication
+// PORT: `final` added. The platform has no CPythonApplication object yet (platform/UserInterface/
+// PythonApplication.cpp), so its members are called on an empty Instance(); `final` lets the compiler
+// call the IAbstractApplication/CMSApplication overrides directly instead of through a vtable that
+// does not exist. Drop it with that note once the application object is constructed.
+class CPythonApplication final : public CMSApplication, public CInputKeyboard, public IAbstractApplication
 {
 	public:
 		enum EDeviceState