Add WebSocket reconnection with exponential backoff

Automatically reconnect when the WebSocket connection is lost (e.g.
phone sleep, alt-tab, network blip) instead of exiting the game.

- Add reconnection state machine (CONNECTED → RECONNECTING → CONNECTED
  or DISCONNECTED) with exponential backoff (1s→30s cap, 10 max attempts)
- Add OnConnectionStatusChanged callback (connected/reconnecting/failed/
  rejected) to PlatformCallbacks, with Emscripten CustomEvent dispatch
  and native SDL_Log implementations
- Add WorldStateSync::ResetForReconnect() to clear session state
- Only exit the game on room-full rejection (WasRejected); connection
  loss is handled internally by the state machine
- Rename WasDisconnected→WasRejected, CheckDisconnected→CheckRejected,
  IsMultiplayerDisconnected→IsMultiplayerRejected through the full call
  chain for accurate naming
- Remove Module._exitCode from JS onclose; use C++ callback +
  sessionStorage for room-full signaling instead
- Clean up EXIT_CONNECTION_LOST constant (obsolete)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ISLE/isleapp.cpp

@@ -1300,7 +1300,7 @@ inline bool IsleApp::Tick()
 	}
 
 #ifdef EXTENSIONS
-	if (Extensions::IsMultiplayerDisconnected()) {
+	if (Extensions::IsMultiplayerRejected()) {
 		g_closed = TRUE;
 		return true;
 	}

extensions/include/extensions/multiplayer.h

@@ -45,7 +45,7 @@ class MultiplayerExt {
 	static MxBool IsClonedCharacter(const char* p_name);
 	static void HandleBeforeSaveLoad();
 	static void HandleSaveLoaded();
-	static MxBool CheckDisconnected();
+	static MxBool CheckRejected();
 
 	static Multiplayer::NetworkManager* GetNetworkManager();
 
@@ -58,7 +58,7 @@ class MultiplayerExt {
 };
 
 #ifdef EXTENSIONS
-LEGO1_EXPORT bool IsMultiplayerDisconnected();
+LEGO1_EXPORT bool IsMultiplayerRejected();
 #endif
 
 namespace MP
@@ -72,7 +72,7 @@ constexpr auto HandleROIClick = &MultiplayerExt::HandleROIClick;
 constexpr auto IsClonedCharacter = &MultiplayerExt::IsClonedCharacter;
 constexpr auto HandleBeforeSaveLoad = &MultiplayerExt::HandleBeforeSaveLoad;
 constexpr auto HandleSaveLoaded = &MultiplayerExt::HandleSaveLoaded;
-constexpr auto CheckDisconnected = &MultiplayerExt::CheckDisconnected;
+constexpr auto CheckRejected = &MultiplayerExt::CheckRejected;
 #else
 constexpr decltype(&MultiplayerExt::HandleCreate) HandleCreate = nullptr;
 constexpr decltype(&MultiplayerExt::HandleWorldEnable) HandleWorldEnable = nullptr;
@@ -82,7 +82,7 @@ constexpr decltype(&MultiplayerExt::HandleROIClick) HandleROIClick = nullptr;
 constexpr decltype(&MultiplayerExt::IsClonedCharacter) IsClonedCharacter = nullptr;
 constexpr decltype(&MultiplayerExt::HandleBeforeSaveLoad) HandleBeforeSaveLoad = nullptr;
 constexpr decltype(&MultiplayerExt::HandleSaveLoaded) HandleSaveLoaded = nullptr;
-constexpr decltype(&MultiplayerExt::CheckDisconnected) CheckDisconnected = nullptr;
+constexpr decltype(&MultiplayerExt::CheckRejected) CheckRejected = nullptr;
 #endif
 } // namespace MP
 

extensions/include/extensions/multiplayer/networkmanager.h

@@ -30,6 +30,12 @@ class NameBubbleRenderer;
 
 class NetworkManager : public MxCore {
 public:
+	enum ConnectionState {
+		STATE_DISCONNECTED,
+		STATE_CONNECTED,
+		STATE_RECONNECTING
+	};
+
 	NetworkManager();
 	~NetworkManager() override;
 
@@ -49,7 +55,7 @@ class NetworkManager : public MxCore {
 	void Connect(const char* p_roomId);
 	void Disconnect();
 	bool IsConnected() const;
-	bool WasDisconnected() const;
+	bool WasRejected() const;
 
 	void SetWalkAnimation(uint8_t p_walkAnimId);
 	void SetIdleAnimation(uint8_t p_idleAnimId);
@@ -114,6 +120,10 @@ class NetworkManager : public MxCore {
 	void RemoveRemotePlayer(uint32_t p_peerId);
 	void RemoveAllRemotePlayers();
 
+	void CheckConnectionState();
+	void AttemptReconnect();
+	void ResetStateAfterReconnect();
+
 	void NotifyPlayerCountChanged();
 	void EnforceDisableNPCs();
 
@@ -149,8 +159,18 @@ class NetworkManager : public MxCore {
 	bool m_lastCameraEnabled;
 	bool m_wasInRestrictedArea;
 
-	static const uint32_t BROADCAST_INTERVAL_MS = 66; // ~15Hz
-	static const uint32_t TIMEOUT_MS = 5000;          // 5 second timeout
+	ConnectionState m_connectionState;
+	bool m_wasRejected;
+	std::string m_roomId;
+	uint32_t m_reconnectAttempt;
+	uint32_t m_reconnectDelay;
+	uint32_t m_nextReconnectTime;
+
+	static const uint32_t BROADCAST_INTERVAL_MS = 66;       // ~15Hz
+	static const uint32_t TIMEOUT_MS = 5000;                // 5 second timeout
+	static const uint32_t RECONNECT_INITIAL_DELAY_MS = 1000;
+	static const uint32_t RECONNECT_MAX_DELAY_MS = 30000;
+	static const uint32_t RECONNECT_MAX_ATTEMPTS = 10;
 };
 
 } // namespace Multiplayer

extensions/include/extensions/multiplayer/networktransport.h

@@ -7,9 +7,6 @@
 namespace Multiplayer
 {
 
-static const int EXIT_ROOM_FULL = 10;
-static const int EXIT_CONNECTION_LOST = 11;
-
 class NetworkTransport {
 public:
 	virtual ~NetworkTransport() = default;

extensions/include/extensions/multiplayer/platformcallbacks.h

@@ -3,6 +3,11 @@
 namespace Multiplayer
 {
 
+static const int CONNECTION_STATUS_CONNECTED = 0;
+static const int CONNECTION_STATUS_RECONNECTING = 1;
+static const int CONNECTION_STATUS_FAILED = 2;
+static const int CONNECTION_STATUS_REJECTED = 3;
+
 class PlatformCallbacks {
 public:
 	virtual ~PlatformCallbacks() = default;
@@ -19,6 +24,9 @@ class PlatformCallbacks {
 
 	// Called when the allow-customization setting changes.
 	virtual void OnAllowCustomizeChanged(bool p_enabled) = 0;
+
+	// Called when the connection status changes (connected, reconnecting, failed).
+	virtual void OnConnectionStatusChanged(int p_status) = 0;
 };
 
 } // namespace Multiplayer

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

@@ -13,6 +13,7 @@ class EmscriptenCallbacks : public PlatformCallbacks {
 	void OnThirdPersonChanged(bool p_enabled) override;
 	void OnNameBubblesChanged(bool p_enabled) override;
 	void OnAllowCustomizeChanged(bool p_enabled) override;
+	void OnConnectionStatusChanged(int p_status) override;
 };
 
 } // namespace Multiplayer

extensions/include/extensions/multiplayer/platforms/native/nativecallbacks.h

@@ -13,6 +13,7 @@ class NativeCallbacks : public PlatformCallbacks {
 	void OnThirdPersonChanged(bool p_enabled) override;
 	void OnNameBubblesChanged(bool p_enabled) override;
 	void OnAllowCustomizeChanged(bool p_enabled) override;
+	void OnConnectionStatusChanged(int p_status) override;
 };
 
 } // namespace Multiplayer

extensions/include/extensions/multiplayer/worldstatesync.h

@@ -48,6 +48,9 @@ class WorldStateSync {
 	// Returns TRUE if the local action should be suppressed (non-host).
 	MxBool HandleSkyLightMutation(uint8_t p_entityType, uint8_t p_changeType);
 
+	// Resets session state for reconnection (peer ID, sequence, host, pending events).
+	void ResetForReconnect();
+
 private:
 	void ApplySkyLightState(const char* p_skyColor, int p_lightPos);
 	void SendSnapshotRequest();

extensions/src/multiplayer.cpp

@@ -251,9 +251,9 @@ MxBool MultiplayerExt::IsClonedCharacter(const char* p_name)
 	return s_networkManager->IsClonedCharacter(p_name) ? TRUE : FALSE;
 }
 
-MxBool MultiplayerExt::CheckDisconnected()
+MxBool MultiplayerExt::CheckRejected()
 {
-	if (s_networkManager && s_networkManager->WasDisconnected()) {
+	if (s_networkManager && s_networkManager->WasRejected()) {
 		return TRUE;
 	}
 
@@ -265,7 +265,7 @@ Multiplayer::NetworkManager* MultiplayerExt::GetNetworkManager()
 	return s_networkManager;
 }
 
-bool Extensions::IsMultiplayerDisconnected()
+bool Extensions::IsMultiplayerRejected()
 {
-	return Extension<MultiplayerExt>::Call(MP::CheckDisconnected).value_or(FALSE);
+	return Extension<MultiplayerExt>::Call(MP::CheckRejected).value_or(FALSE);
 }

extensions/src/multiplayer/networkmanager.cpp

@@ -49,7 +49,9 @@ NetworkManager::NetworkManager()
 	  m_sequence(0), m_lastBroadcastTime(0), m_lastValidActorId(0), m_localAllowRemoteCustomize(true),
 	  m_inIsleWorld(false), m_registered(false), m_pendingToggleThirdPerson(false), m_pendingToggleNameBubbles(false),
 	  m_pendingWalkAnim(-1), m_pendingIdleAnim(-1), m_pendingEmote(-1), m_pendingToggleAllowCustomize(false),
-	  m_disableAllNPCs(false), m_showNameBubbles(true), m_lastCameraEnabled(false), m_wasInRestrictedArea(false)
+	  m_disableAllNPCs(false), m_showNameBubbles(true), m_lastCameraEnabled(false), m_wasInRestrictedArea(false),
+	  m_connectionState(STATE_DISCONNECTED), m_wasRejected(false), m_reconnectAttempt(0), m_reconnectDelay(0),
+	  m_nextReconnectTime(0)
 {
 }
 
@@ -66,6 +68,7 @@ static ThirdPersonCamera::Controller* GetCamera()
 MxResult NetworkManager::Tickle()
 {
 	ProcessPendingRequests();
+	CheckConnectionState();
 
 	if (m_disableAllNPCs) {
 		EnforceDisableNPCs();
@@ -171,12 +174,15 @@ void NetworkManager::Shutdown()
 void NetworkManager::Connect(const char* p_roomId)
 {
 	if (m_transport) {
+		m_roomId = p_roomId;
 		m_transport->Connect(p_roomId);
+		m_connectionState = STATE_CONNECTED;
 	}
 }
 
 void NetworkManager::Disconnect()
 {
+	m_connectionState = STATE_DISCONNECTED;
 	if (m_transport) {
 		m_transport->Disconnect();
 	}
@@ -188,9 +194,9 @@ bool NetworkManager::IsConnected() const
 	return m_transport && m_transport->IsConnected();
 }
 
-bool NetworkManager::WasDisconnected() const
+bool NetworkManager::WasRejected() const
 {
-	return m_transport && m_transport->WasDisconnected();
+	return m_wasRejected;
 }
 
 void NetworkManager::OnWorldEnabled(LegoWorld* p_world)
@@ -322,6 +328,88 @@ void NetworkManager::EnforceDisableNPCs()
 	}
 }
 
+void NetworkManager::CheckConnectionState()
+{
+	if (!m_transport || m_connectionState == STATE_DISCONNECTED) {
+		return;
+	}
+
+	if (m_connectionState == STATE_CONNECTED) {
+		if (!m_transport->WasDisconnected()) {
+			return;
+		}
+
+		if (m_transport->WasRejected()) {
+			// Room full on initial connect - flag for game loop to exit
+			m_wasRejected = true;
+			m_connectionState = STATE_DISCONNECTED;
+
+			if (m_callbacks) {
+				m_callbacks->OnConnectionStatusChanged(CONNECTION_STATUS_REJECTED);
+			}
+			return;
+		}
+
+		// Connection lost - enter reconnection
+		m_connectionState = STATE_RECONNECTING;
+		RemoveAllRemotePlayers();
+		m_reconnectAttempt = 0;
+		m_reconnectDelay = RECONNECT_INITIAL_DELAY_MS;
+		m_nextReconnectTime = SDL_GetTicks() + m_reconnectDelay;
+
+		if (m_callbacks) {
+			m_callbacks->OnConnectionStatusChanged(CONNECTION_STATUS_RECONNECTING);
+		}
+		return;
+	}
+
+	// STATE_RECONNECTING
+	if (m_transport->IsConnected()) {
+		ResetStateAfterReconnect();
+		m_connectionState = STATE_CONNECTED;
+
+		if (m_callbacks) {
+			m_callbacks->OnConnectionStatusChanged(CONNECTION_STATUS_CONNECTED);
+		}
+		return;
+	}
+
+	uint32_t now = SDL_GetTicks();
+	if (now < m_nextReconnectTime) {
+		return;
+	}
+
+	if (m_reconnectAttempt >= RECONNECT_MAX_ATTEMPTS) {
+		// Give up - stay alive but without multiplayer
+		m_connectionState = STATE_DISCONNECTED;
+
+		if (m_callbacks) {
+			m_callbacks->OnConnectionStatusChanged(CONNECTION_STATUS_FAILED);
+		}
+		return;
+	}
+
+	AttemptReconnect();
+}
+
+void NetworkManager::AttemptReconnect()
+{
+	m_reconnectAttempt++;
+	m_transport->Disconnect();
+	m_transport->Connect(m_roomId.c_str());
+	m_reconnectDelay = SDL_min(m_reconnectDelay * 2, RECONNECT_MAX_DELAY_MS);
+	m_nextReconnectTime = SDL_GetTicks() + m_reconnectDelay;
+}
+
+void NetworkManager::ResetStateAfterReconnect()
+{
+	m_localPeerId = 0;
+	m_hostPeerId = 0;
+	m_sequence = 0;
+	m_lastBroadcastTime = 0;
+	m_worldSync.ResetForReconnect();
+}
+
 void NetworkManager::ProcessPendingRequests()
 {
 	ThirdPersonCamera::Controller* cam = GetCamera();

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

@@ -50,6 +50,20 @@ void EmscriptenCallbacks::OnAllowCustomizeChanged(bool p_enabled)
 	DispatchBoolEvent("allowCustomizeChanged", p_enabled);
 }
 
+void EmscriptenCallbacks::OnConnectionStatusChanged(int p_status)
+{
+	// clang-format off
+	MAIN_THREAD_EM_ASM({
+		var canvas = Module.canvas;
+		if (canvas) {
+			canvas.dispatchEvent(new CustomEvent('connectionStatusChanged', {
+				detail: { status: $0 }
+			}));
+		}
+	}, p_status);
+	// clang-format on
+}
+
 } // namespace Multiplayer
 
 #endif // __EMSCRIPTEN__

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

@@ -44,8 +44,6 @@ void WebSocketTransport::Connect(const char* p_roomId)
 		var connPtr = $1;
 		var discPtr = $2;
 		var everConnPtr = $3;
-		var exitRoomFull = $4;
-		var exitConnLost = $5;
 		var socketId = Module._mpNextSocketId++;
 		Module._mpMessageQueues[socketId] = [];
 
@@ -66,10 +64,8 @@ void WebSocketTransport::Connect(const char* p_roomId)
 			};
 
 			ws.onclose = function() {
-				var wasEverConnected = Atomics.load(HEAP32, everConnPtr >> 2);
 				Atomics.store(HEAP32, connPtr >> 2, 0);
 				Atomics.store(HEAP32, discPtr >> 2, 1);
-				Module._exitCode = wasEverConnected ? exitConnLost : exitRoomFull;
 			};
 
 			ws.onerror = function() {
@@ -83,7 +79,7 @@ void WebSocketTransport::Connect(const char* p_roomId)
 		}
 
 		return socketId;
-	}, url.c_str(), &m_connectedFlag, &m_disconnectedFlag, &m_wasEverConnected, EXIT_ROOM_FULL, EXIT_CONNECTION_LOST);
+	}, url.c_str(), &m_connectedFlag, &m_disconnectedFlag, &m_wasEverConnected);
 	// clang-format on
 
 	if (m_socketId <= 0) {

extensions/src/multiplayer/platforms/native/nativecallbacks.cpp

@@ -32,6 +32,26 @@ void NativeCallbacks::OnAllowCustomizeChanged(bool p_enabled)
 	SDL_Log("[Multiplayer] Allow customization: %s", p_enabled ? "enabled" : "disabled");
 }
 
+void NativeCallbacks::OnConnectionStatusChanged(int p_status)
+{
+	const char* statusStr = "unknown";
+	switch (p_status) {
+	case CONNECTION_STATUS_CONNECTED:
+		statusStr = "connected";
+		break;
+	case CONNECTION_STATUS_RECONNECTING:
+		statusStr = "reconnecting";
+		break;
+	case CONNECTION_STATUS_FAILED:
+		statusStr = "failed";
+		break;
+	case CONNECTION_STATUS_REJECTED:
+		statusStr = "rejected (room full)";
+		break;
+	}
+	SDL_Log("[Multiplayer] Connection status: %s", statusStr);
+}
+
 } // namespace Multiplayer
 
 #endif // !__EMSCRIPTEN__

extensions/src/multiplayer/worldstatesync.cpp

@@ -66,6 +66,15 @@ void WorldStateSync::ApplySkyLightState(const char* p_skyColor, int p_lightPos)
 	VariableTable()->SetVariable("lightposition", buf);
 }
 
+void WorldStateSync::ResetForReconnect()
+{
+	m_localPeerId = 0;
+	m_sequence = 0;
+	m_isHost = false;
+	m_snapshotRequested = false;
+	m_pendingWorldEvents.clear();
+}
+
 void WorldStateSync::OnHostChanged()
 {
 	if (!m_isHost) {