Extract PlatformCallbacks interface and consolidate Emscripten files

Move all Emscripten-specific multiplayer code under platforms/emscripten/
and introduce an abstract PlatformCallbacks interface for outbound
notifications, mirroring the existing NetworkTransport pattern. This
removes all #ifdef __EMSCRIPTEN__ blocks from networkmanager.cpp.

CMakeLists.txt

@@ -535,9 +535,14 @@ if (ISLE_EXTENSIONS)
     extensions/src/multiplayer/charactercloner.cpp
     extensions/src/multiplayer/networkmanager.cpp
     extensions/src/multiplayer/remoteplayer.cpp
-    extensions/src/multiplayer/websockettransport.cpp
     extensions/src/multiplayer/worldstatesync.cpp
   )
+  if(EMSCRIPTEN)
+    target_sources(lego1 PRIVATE
+      extensions/src/multiplayer/platforms/emscripten/websockettransport.cpp
+      extensions/src/multiplayer/platforms/emscripten/callbacks.cpp
+    )
+  endif()
 endif()
 
 if (ISLE_BUILD_APP)
@@ -595,7 +600,7 @@ if (ISLE_BUILD_APP)
     )
     if(ISLE_EXTENSIONS)
       target_sources(isle PRIVATE
-        extensions/src/multiplayer/wasm_exports.cpp
+        extensions/src/multiplayer/platforms/emscripten/wasm_exports.cpp
       )
     endif()
     target_compile_definitions(isle PRIVATE "ISLE_EMSCRIPTEN_HOST=\"${ISLE_EMSCRIPTEN_HOST}\"")

extensions/include/extensions/multiplayer.h

@@ -13,6 +13,7 @@ namespace Multiplayer
 {
 class NetworkManager;
 class NetworkTransport;
+class PlatformCallbacks;
 } // namespace Multiplayer
 
 namespace Extensions
@@ -42,6 +43,7 @@ class MultiplayerExt {
 private:
 	static Multiplayer::NetworkManager* s_networkManager;
 	static Multiplayer::NetworkTransport* s_transport;
+	static Multiplayer::PlatformCallbacks* s_callbacks;
 };
 
 #ifdef EXTENSIONS

extensions/include/extensions/multiplayer/networkmanager.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "extensions/multiplayer/networktransport.h"
+#include "extensions/multiplayer/platformcallbacks.h"
 #include "extensions/multiplayer/protocol.h"
 #include "extensions/multiplayer/remoteplayer.h"
 #include "extensions/multiplayer/worldstatesync.h"
@@ -33,7 +34,7 @@ class NetworkManager : public MxCore {
 		return !strcmp(p_name, NetworkManager::ClassName()) || MxCore::IsA(p_name);
 	}
 
-	void Initialize(NetworkTransport* p_transport);
+	void Initialize(NetworkTransport* p_transport, PlatformCallbacks* p_callbacks);
 	void Shutdown();
 
 	void Connect(const char* p_roomId);
@@ -78,6 +79,7 @@ class NetworkManager : public MxCore {
 	void SendMessage(const T& p_msg);
 
 	NetworkTransport* m_transport;
+	PlatformCallbacks* m_callbacks;
 	WorldStateSync m_worldSync;
 	std::map<uint32_t, std::unique_ptr<RemotePlayer>> m_remotePlayers;
 

extensions/include/extensions/multiplayer/platformcallbacks.h

@@ -0,0 +1,15 @@
+#pragma once
+
+namespace Multiplayer
+{
+
+class PlatformCallbacks {
+public:
+	virtual ~PlatformCallbacks() = default;
+
+	// Called when the visible player count changes (joins, leaves, world transitions).
+	// p_count = players visible in current world, or -1 if not in a multiplayer world.
+	virtual void OnPlayerCountChanged(int p_count) = 0;
+};
+
+} // namespace Multiplayer

extensions/include/extensions/multiplayer/platforms/emscripten/callbacks.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#ifdef __EMSCRIPTEN__
+
+#include "extensions/multiplayer/platformcallbacks.h"
+
+namespace Multiplayer
+{
+
+class EmscriptenCallbacks : public PlatformCallbacks {
+public:
+	void OnPlayerCountChanged(int p_count) override;
+};
+
+} // namespace Multiplayer
+
+#endif // __EMSCRIPTEN__

extensions/src/multiplayer.cpp

@@ -8,8 +8,11 @@
 #include "legoentity.h"
 #include "legogamestate.h"
 #include "misc.h"
+
 #ifdef __EMSCRIPTEN__
-#include "extensions/multiplayer/websockettransport.h"
+#include "extensions/multiplayer/platforms/emscripten/callbacks.h"
+#include "extensions/multiplayer/platforms/emscripten/websockettransport.h"
+
 #include <emscripten.h>
 #endif
 
@@ -21,6 +24,7 @@ std::string MultiplayerExt::relayUrl;
 std::string MultiplayerExt::room;
 Multiplayer::NetworkManager* MultiplayerExt::s_networkManager = nullptr;
 Multiplayer::NetworkTransport* MultiplayerExt::s_transport = nullptr;
+Multiplayer::PlatformCallbacks* MultiplayerExt::s_callbacks = nullptr;
 
 void MultiplayerExt::Initialize()
 {
@@ -33,9 +37,10 @@ void MultiplayerExt::Initialize()
 
 #ifdef __EMSCRIPTEN__
 	s_transport = new Multiplayer::WebSocketTransport(relayUrl);
+	s_callbacks = new Multiplayer::EmscriptenCallbacks();
 
 	s_networkManager = new Multiplayer::NetworkManager();
-	s_networkManager->Initialize(s_transport);
+	s_networkManager->Initialize(s_transport, s_callbacks);
 
 	s_networkManager->Connect(room.c_str());
 #endif

extensions/src/multiplayer/networkmanager.cpp

@@ -11,9 +11,6 @@
 #include <SDL3/SDL_stdinc.h>
 #include <SDL3/SDL_timer.h>
 #include <vector>
-#ifdef __EMSCRIPTEN__
-#include <emscripten.h>
-#endif
 
 using namespace Multiplayer;
 
@@ -32,8 +29,9 @@ void NetworkManager::SendMessage(const T& p_msg)
 }
 
 NetworkManager::NetworkManager()
-	: m_transport(nullptr), m_localPeerId(0), m_hostPeerId(0), m_sequence(0), m_lastBroadcastTime(0),
-	  m_lastValidActorId(0), m_localWalkAnimId(0), m_localIdleAnimId(0), m_inIsleWorld(false), m_registered(false)
+	: m_transport(nullptr), m_callbacks(nullptr), m_localPeerId(0), m_hostPeerId(0), m_sequence(0),
+	  m_lastBroadcastTime(0), m_lastValidActorId(0), m_localWalkAnimId(0), m_localIdleAnimId(0), m_inIsleWorld(false),
+	  m_registered(false)
 {
 }
 
@@ -78,9 +76,10 @@ MxResult NetworkManager::Tickle()
 	return SUCCESS;
 }
 
-void NetworkManager::Initialize(NetworkTransport* p_transport)
+void NetworkManager::Initialize(NetworkTransport* p_transport, PlatformCallbacks* p_callbacks)
 {
 	m_transport = p_transport;
+	m_callbacks = p_callbacks;
 	m_worldSync.SetTransport(p_transport);
 }
 
@@ -460,7 +459,10 @@ void NetworkManager::RemoveAllRemotePlayers()
 
 void NetworkManager::NotifyPlayerCountChanged()
 {
-#ifdef __EMSCRIPTEN__
+	if (!m_callbacks) {
+		return;
+	}
+
 	int count = -1;
 	if (m_inIsleWorld) {
 		count = 1; // local player
@@ -470,17 +472,8 @@ void NetworkManager::NotifyPlayerCountChanged()
 			}
 		}
 	}
-	// clang-format off
-	MAIN_THREAD_EM_ASM({
-		var canvas = Module.canvas;
-		if (canvas) {
-			canvas.dispatchEvent(new CustomEvent('playerCountChanged', {
-				detail: { count: $0 < 0 ? null : $0 }
-			}));
-		}
-	}, count);
-	// clang-format on
-#endif
+
+	m_callbacks->OnPlayerCountChanged(count);
 }
 
 int8_t NetworkManager::DetectLocalVehicleType()

extensions/src/multiplayer/platforms/emscripten/callbacks.cpp

@@ -0,0 +1,26 @@
+#ifdef __EMSCRIPTEN__
+
+#include "extensions/multiplayer/platforms/emscripten/callbacks.h"
+
+#include <emscripten.h>
+
+namespace Multiplayer
+{
+
+void EmscriptenCallbacks::OnPlayerCountChanged(int p_count)
+{
+	// clang-format off
+	MAIN_THREAD_EM_ASM({
+		var canvas = Module.canvas;
+		if (canvas) {
+			canvas.dispatchEvent(new CustomEvent('playerCountChanged', {
+				detail: { count: $0 < 0 ? null : $0 }
+			}));
+		}
+	}, p_count);
+	// clang-format on
+}
+
+} // namespace Multiplayer
+
+#endif // __EMSCRIPTEN__

extensions/src/multiplayer/platforms/emscripten/wasm_exports.cpp

@@ -0,0 +1,39 @@
+#ifdef __EMSCRIPTEN__
+
+#include "extensions/multiplayer.h"
+#include "extensions/multiplayer/networkmanager.h"
+
+#include <emscripten.h>
+
+using namespace Extensions;
+
+extern "C"
+{
+
+	EMSCRIPTEN_KEEPALIVE void mp_set_walk_animation(int index)
+	{
+		Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
+		if (mgr) {
+			mgr->SetWalkAnimation(static_cast<uint8_t>(index));
+		}
+	}
+
+	EMSCRIPTEN_KEEPALIVE void mp_set_idle_animation(int index)
+	{
+		Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
+		if (mgr) {
+			mgr->SetIdleAnimation(static_cast<uint8_t>(index));
+		}
+	}
+
+	EMSCRIPTEN_KEEPALIVE void mp_trigger_emote(int index)
+	{
+		Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
+		if (mgr) {
+			mgr->SendEmote(static_cast<uint8_t>(index));
+		}
+	}
+
+} // extern "C"
+
+#endif

extensions/src/multiplayer/platforms/emscripten/websockettransport.cpp

@@ -1,6 +1,6 @@
 #ifdef __EMSCRIPTEN__
 
-#include "extensions/multiplayer/websockettransport.h"
+#include "extensions/multiplayer/platforms/emscripten/websockettransport.h"
 
 #include <SDL3/SDL_stdinc.h>
 #include <emscripten.h>

extensions/src/multiplayer/wasm_exports.cpp

@@ -1,38 +0,0 @@
-#ifdef __EMSCRIPTEN__
-
-#include "extensions/multiplayer.h"
-#include "extensions/multiplayer/networkmanager.h"
-
-#include <emscripten.h>
-
-using namespace Extensions;
-
-extern "C" {
-
-EMSCRIPTEN_KEEPALIVE void mp_set_walk_animation(int index)
-{
-	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
-	if (mgr) {
-		mgr->SetWalkAnimation(static_cast<uint8_t>(index));
-	}
-}
-
-EMSCRIPTEN_KEEPALIVE void mp_set_idle_animation(int index)
-{
-	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
-	if (mgr) {
-		mgr->SetIdleAnimation(static_cast<uint8_t>(index));
-	}
-}
-
-EMSCRIPTEN_KEEPALIVE void mp_trigger_emote(int index)
-{
-	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
-	if (mgr) {
-		mgr->SendEmote(static_cast<uint8_t>(index));
-	}
-}
-
-} // extern "C"
-
-#endif