feat: Add spawn/delete commands, fix session state and entity broadcast

- marathonctl now supports spawn/delete entity commands
- Fixed session state bug (was transitioning to Left every 5s)
- Fixed entity broadcast to detect Added<NetworkedEntity>
- Added AppCommandQueue pattern for app-level control commands

References: #131, #132

crates/app/src/bin/marathonctl.rs

@@ -19,7 +19,7 @@ use clap::{Parser, Subcommand};
 use std::io::{Read, Write};
 use std::os::unix::net::UnixStream;
 
-use libmarathon::networking::{ControlCommand, ControlResponse, SessionId};
+use libmarathon::networking::{ControlCommand, ControlResponse};
 
 /// Marathon control CLI
 #[derive(Parser, Debug)]
@@ -51,6 +51,25 @@ enum Commands {
     },
     /// Broadcast a ping message
     Ping,
+    /// Spawn an entity
+    Spawn {
+        /// Entity type (e.g., "cube")
+        entity_type: String,
+        /// X position
+        #[arg(short, long, default_value = "0.0")]
+        x: f32,
+        /// Y position
+        #[arg(short, long, default_value = "0.0")]
+        y: f32,
+        /// Z position
+        #[arg(short, long, default_value = "0.0")]
+        z: f32,
+    },
+    /// Delete an entity by UUID
+    Delete {
+        /// Entity UUID
+        entity_id: String,
+    },
 }
 
 fn main() {
@@ -75,6 +94,22 @@ fn main() {
                 },
             }
         }
+        Commands::Spawn { entity_type, x, y, z } => {
+            ControlCommand::SpawnEntity {
+                entity_type,
+                position: [x, y, z],
+            }
+        }
+        Commands::Delete { entity_id } => {
+            use uuid::Uuid;
+            match Uuid::parse_str(&entity_id) {
+                Ok(uuid) => ControlCommand::DeleteEntity { entity_id: uuid },
+                Err(e) => {
+                    eprintln!("Invalid UUID '{}': {}", entity_id, e);
+                    std::process::exit(1);
+                }
+            }
+        }
     };
 
     // Connect to Unix socket
@@ -135,8 +170,6 @@ fn receive_response(stream: &mut UnixStream) -> Result<ControlResponse, Box<dyn
 }
 
 fn print_response(response: ControlResponse) {
-    use libmarathon::networking::{SessionInfo, PeerInfo};
-
     match response {
         ControlResponse::Status {
             node_id,

crates/app/src/control.rs

@@ -6,27 +6,90 @@
 
 use anyhow::Result;
 use bevy::prelude::*;
+use crossbeam_channel::{Receiver, Sender, unbounded};
 use libmarathon::{
     engine::{EngineBridge, EngineCommand},
     networking::{ControlCommand, ControlResponse, SessionId},
 };
+use uuid::Uuid;
 
 /// Resource holding the control socket path
 #[derive(Resource)]
 pub struct ControlSocketPath(pub String);
 
+pub fn cleanup_control_socket(
+    mut exit_events: MessageReader<bevy::app::AppExit>,
+    socket_path: Option<Res<ControlSocketPath>>,
+) {
+    for _ in exit_events.read() {
+        if let Some(ref path) = socket_path {
+            info!("Cleaning up control socket at {}", path.0);
+            let _ = std::fs::remove_file(&path.0);
+        }
+    }
+}
+
+/// Commands that can be sent from the control socket to the app
+#[derive(Debug, Clone)]
+pub enum AppCommand {
+    SpawnEntity {
+        entity_type: String,
+        position: Vec3,
+    },
+    DeleteEntity {
+        entity_id: Uuid,
+    },
+}
+
+/// Queue for app-level commands from control socket
+#[derive(Resource, Clone)]
+pub struct AppCommandQueue {
+    sender: Sender<AppCommand>,
+    receiver: Receiver<AppCommand>,
+}
+
+impl AppCommandQueue {
+    pub fn new() -> Self {
+        let (sender, receiver) = unbounded();
+        Self { sender, receiver }
+    }
+
+    pub fn send(&self, command: AppCommand) {
+        let _ = self.sender.send(command);
+    }
+
+    pub fn try_recv(&self) -> Option<AppCommand> {
+        self.receiver.try_recv().ok()
+    }
+}
+
+impl Default for AppCommandQueue {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 /// Startup system to launch the control socket server
 #[cfg(not(target_os = "ios"))]
 #[cfg(debug_assertions)]
-pub fn start_control_socket_system(socket_path_res: Res<ControlSocketPath>, bridge: Res<EngineBridge>) {
-    use tokio::io::{AsyncReadExt, AsyncWriteExt};
+pub fn start_control_socket_system(
+    mut commands: Commands,
+    socket_path_res: Res<ControlSocketPath>,
+    bridge: Res<EngineBridge>,
+) {
+    use tokio::io::AsyncReadExt;
     use tokio::net::UnixListener;
 
     let socket_path = socket_path_res.0.clone();
     info!("Starting control socket at {}", socket_path);
 
-    // Clone bridge for the async task
+    // Create app command queue
+    let app_queue = AppCommandQueue::new();
+    commands.insert_resource(app_queue.clone());
+
+    // Clone bridge and queue for the async task
     let bridge = bridge.clone();
+    let queue = app_queue;
 
     // Spawn tokio runtime in background thread
     std::thread::spawn(move || {
@@ -52,6 +115,7 @@ pub fn start_control_socket_system(socket_path_res: Res<ControlSocketPath>, brid
                     Ok((mut stream, _addr)) => {
                         let bridge = bridge.clone();
 
+                        let queue_clone = queue.clone();
                         tokio::spawn(async move {
                             // Read command length
                             let mut len_buf = [0u8; 4];
@@ -84,7 +148,7 @@ pub fn start_control_socket_system(socket_path_res: Res<ControlSocketPath>, brid
                             info!("Received control command: {:?}", command);
 
                             // Handle command
-                            let response = handle_command(command, &bridge).await;
+                            let response = handle_command(command, &bridge, &queue_clone).await;
 
                             // Send response
                             if let Err(e) = send_response(&mut stream, response).await {
@@ -104,7 +168,11 @@ pub fn start_control_socket_system(socket_path_res: Res<ControlSocketPath>, brid
 /// Handle a control command and generate a response
 #[cfg(not(target_os = "ios"))]
 #[cfg(debug_assertions)]
-async fn handle_command(command: ControlCommand, bridge: &EngineBridge) -> ControlResponse {
+async fn handle_command(
+    command: ControlCommand,
+    bridge: &EngineBridge,
+    app_queue: &AppCommandQueue,
+) -> ControlResponse {
     match command {
         ControlCommand::JoinSession { session_code } => {
             match SessionId::from_code(&session_code) {
@@ -129,12 +197,58 @@ async fn handle_command(command: ControlCommand, bridge: &EngineBridge) -> Contr
             }
         }
 
+        ControlCommand::SpawnEntity { entity_type, position } => {
+            app_queue.send(AppCommand::SpawnEntity {
+                entity_type,
+                position: Vec3::from_array(position),
+            });
+            ControlResponse::Ok {
+                message: "Entity spawn command queued".to_string(),
+            }
+        }
+
+        ControlCommand::DeleteEntity { entity_id } => {
+            app_queue.send(AppCommand::DeleteEntity { entity_id });
+            ControlResponse::Ok {
+                message: format!("Entity delete command queued for {}", entity_id),
+            }
+        }
+
         _ => ControlResponse::Error {
             error: format!("Command {:?} not yet implemented", command),
         },
     }
 }
 
+/// System to process app commands from the control socket
+pub fn process_app_commands(
+    queue: Option<Res<AppCommandQueue>>,
+    mut spawn_cube_writer: MessageWriter<crate::cube::SpawnCubeEvent>,
+    mut delete_cube_writer: MessageWriter<crate::cube::DeleteCubeEvent>,
+) {
+    let Some(queue) = queue else { return };
+
+    while let Some(command) = queue.try_recv() {
+        match command {
+            AppCommand::SpawnEntity { entity_type, position } => {
+                match entity_type.as_str() {
+                    "cube" => {
+                        info!("Spawning cube at {:?}", position);
+                        spawn_cube_writer.write(crate::cube::SpawnCubeEvent { position });
+                    }
+                    _ => {
+                        warn!("Unknown entity type: {}", entity_type);
+                    }
+                }
+            }
+            AppCommand::DeleteEntity { entity_id } => {
+                info!("Deleting entity {}", entity_id);
+                delete_cube_writer.write(crate::cube::DeleteCubeEvent { entity_id });
+            }
+        }
+    }
+}
+
 /// Send a response back through the Unix socket
 #[cfg(not(target_os = "ios"))]
 #[cfg(debug_assertions)]

crates/app/src/main.rs

@@ -205,6 +205,7 @@ fn main() {
     // Insert control socket path as resource
     app.insert_resource(control::ControlSocketPath(args.control_socket.clone()));
     app.add_systems(Startup, control::start_control_socket_system);
+    app.add_systems(Update, (control::process_app_commands, control::cleanup_control_socket));
 
     // Rendering-only plugins
     #[cfg(not(feature = "headless"))]

crates/app/src/setup/control_socket.rs

@@ -0,0 +1,253 @@
+//! Unix domain socket control server for remote engine control
+//!
+//! This module provides a Unix socket server for controlling the engine
+//! programmatically without needing screen access or network ports.
+//!
+//! # Security
+//!
+//! Currently debug-only. See issue #135 for production security requirements.
+
+use anyhow::Result;
+use bevy::prelude::*;
+use libmarathon::networking::{ControlCommand, ControlResponse, GossipBridge, SessionId};
+use uuid::Uuid;
+
+/// Spawn Unix domain socket control server for remote engine control
+///
+/// This spawns a tokio task that listens on a Unix socket for control commands.
+/// The socket path is `/tmp/marathon-{session_id}.sock`.
+///
+/// **Security Note**: This is currently debug-only. See issue #135 for production
+/// security requirements (authentication, rate limiting, etc.).
+///
+/// # Platform Support
+///
+/// This function is only compiled on non-iOS platforms.
+#[cfg(not(target_os = "ios"))]
+#[cfg(debug_assertions)]
+pub fn spawn_control_socket(session_id: SessionId, bridge: GossipBridge, node_id: Uuid) {
+    use tokio::io::AsyncReadExt;
+    use tokio::net::UnixListener;
+
+    let socket_path = format!("/tmp/marathon-{}.sock", session_id);
+
+    tokio::spawn(async move {
+        // Clean up any existing socket
+        let _ = std::fs::remove_file(&socket_path);
+
+        let listener = match UnixListener::bind(&socket_path) {
+            Ok(l) => {
+                info!("Control socket listening at {}", socket_path);
+                l
+            }
+            Err(e) => {
+                error!("Failed to bind control socket at {}: {}", socket_path, e);
+                return;
+            }
+        };
+
+        // Accept connections in a loop
+        loop {
+            match listener.accept().await {
+                Ok((mut stream, _addr)) => {
+                    let bridge = bridge.clone();
+                    let session_id = session_id.clone();
+
+                    // Spawn a task to handle this connection
+                    tokio::spawn(async move {
+                        // Read command length (4 bytes)
+                        let mut len_buf = [0u8; 4];
+                        if let Err(e) = stream.read_exact(&mut len_buf).await {
+                            error!("Failed to read command length: {}", e);
+                            return;
+                        }
+                        let len = u32::from_le_bytes(len_buf) as usize;
+
+                        // Read command bytes
+                        let mut cmd_buf = vec![0u8; len];
+                        if let Err(e) = stream.read_exact(&mut cmd_buf).await {
+                            error!("Failed to read command: {}", e);
+                            return;
+                        }
+
+                        // Deserialize command
+                        let command = match ControlCommand::from_bytes(&cmd_buf) {
+                            Ok(cmd) => cmd,
+                            Err(e) => {
+                                error!("Failed to deserialize command: {}", e);
+                                let response = ControlResponse::Error {
+                                    error: format!("Failed to deserialize command: {}", e),
+                                };
+                                let _ = send_response(&mut stream, response).await;
+                                return;
+                            }
+                        };
+
+                        info!("Received control command: {:?}", command);
+
+                        // Execute command
+                        let response = handle_control_command(command, &bridge, session_id, node_id).await;
+
+                        // Send response
+                        if let Err(e) = send_response(&mut stream, response).await {
+                            error!("Failed to send response: {}", e);
+                        }
+                    });
+                }
+                Err(e) => {
+                    error!("Failed to accept control socket connection: {}", e);
+                }
+            }
+        }
+    });
+}
+
+/// Handle a control command and return a response
+#[cfg(not(target_os = "ios"))]
+#[cfg(debug_assertions)]
+async fn handle_control_command(
+    command: ControlCommand,
+    bridge: &GossipBridge,
+    session_id: SessionId,
+    node_id: Uuid,
+) -> ControlResponse {
+    match command {
+        ControlCommand::GetStatus => {
+            // Get queue sizes from bridge
+            let outgoing_size = bridge.try_recv_outgoing().map(|msg| {
+                // Put it back
+                let _ = bridge.send(msg);
+                1
+            }).unwrap_or(0);
+
+            ControlResponse::Status {
+                node_id,
+                session_id,
+                outgoing_queue_size: outgoing_size,
+                incoming_queue_size: 0, // We'd need to peek without consuming
+                connected_peers: None, // Not easily available from bridge
+            }
+        }
+        ControlCommand::SendTestMessage { content } => {
+            use libmarathon::networking::{VersionedMessage, VectorClock, SyncMessage};
+
+            // Send a SyncRequest as a test message (lightweight ping-like message)
+            let message = SyncMessage::SyncRequest {
+                node_id,
+                vector_clock: VectorClock::new(),
+            };
+            let versioned = VersionedMessage::new(message);
+
+            match bridge.send(versioned) {
+                Ok(_) => ControlResponse::Ok {
+                    message: format!("Sent test message: {}", content),
+                },
+                Err(e) => ControlResponse::Error {
+                    error: format!("Failed to send: {}", e),
+                },
+            }
+        }
+        ControlCommand::InjectMessage { message } => {
+            match bridge.push_incoming(message) {
+                Ok(_) => ControlResponse::Ok {
+                    message: "Message injected into incoming queue".to_string(),
+                },
+                Err(e) => ControlResponse::Error {
+                    error: format!("Failed to inject message: {}", e),
+                },
+            }
+        }
+        ControlCommand::BroadcastMessage { message } => {
+            use libmarathon::networking::VersionedMessage;
+
+            let versioned = VersionedMessage::new(message);
+            match bridge.send(versioned) {
+                Ok(_) => ControlResponse::Ok {
+                    message: "Message broadcast".to_string(),
+                },
+                Err(e) => ControlResponse::Error {
+                    error: format!("Failed to broadcast: {}", e),
+                },
+            }
+        }
+        ControlCommand::Shutdown => {
+            warn!("Shutdown command received via control socket");
+            ControlResponse::Ok {
+                message: "Shutdown not yet implemented".to_string(),
+            }
+        }
+
+        // Session lifecycle commands (TODO: implement these properly)
+        ControlCommand::JoinSession { session_code } => {
+            ControlResponse::Error {
+                error: format!("JoinSession not yet implemented (requested: {})", session_code),
+            }
+        }
+        ControlCommand::LeaveSession => {
+            ControlResponse::Error {
+                error: "LeaveSession not yet implemented".to_string(),
+            }
+        }
+        ControlCommand::GetSessionInfo => {
+            ControlResponse::Error {
+                error: "GetSessionInfo not yet implemented".to_string(),
+            }
+        }
+        ControlCommand::ListSessions => {
+            ControlResponse::Error {
+                error: "ListSessions not yet implemented".to_string(),
+            }
+        }
+        ControlCommand::DeleteSession { session_code } => {
+            ControlResponse::Error {
+                error: format!("DeleteSession not yet implemented (requested: {})", session_code),
+            }
+        }
+        ControlCommand::ListPeers => {
+            ControlResponse::Error {
+                error: "ListPeers not yet implemented".to_string(),
+            }
+        }
+        ControlCommand::SpawnEntity { .. } => {
+            ControlResponse::Error {
+                error: "SpawnEntity not available on session-level socket. Use app-level socket.".to_string(),
+            }
+        }
+        ControlCommand::DeleteEntity { .. } => {
+            ControlResponse::Error {
+                error: "DeleteEntity not available on session-level socket. Use app-level socket.".to_string(),
+            }
+        }
+    }
+}
+
+/// Send a response back through the Unix socket
+#[cfg(not(target_os = "ios"))]
+#[cfg(debug_assertions)]
+async fn send_response(
+    stream: &mut tokio::net::UnixStream,
+    response: ControlResponse,
+) -> Result<()> {
+    use tokio::io::AsyncWriteExt;
+
+    let bytes = response.to_bytes()?;
+    let len = bytes.len() as u32;
+
+    // Write length prefix
+    stream.write_all(&len.to_le_bytes()).await?;
+    // Write response bytes
+    stream.write_all(&bytes).await?;
+    stream.flush().await?;
+
+    Ok(())
+}
+
+// No-op stub for iOS builds
+#[cfg(target_os = "ios")]
+pub fn spawn_control_socket(_session_id: SessionId, _bridge: GossipBridge, _node_id: Uuid) {}
+
+// No-op stub for release builds
+#[cfg(all(not(target_os = "ios"), not(debug_assertions)))]
+pub fn spawn_control_socket(_session_id: SessionId, _bridge: GossipBridge, _node_id: Uuid) {
+    // TODO(#135): Implement secure control socket for release builds with authentication
+}

crates/app/src/setup/mod.rs

@@ -47,11 +47,15 @@
 //! 2. **Tokio → Bevy**: GossipBridge's internal queue (push_incoming)
 //! 3. **Thread handoff**: crossbeam_channel (one-time GossipBridge transfer)
 
+mod control_socket;
+
 use anyhow::Result;
 use bevy::prelude::*;
 use libmarathon::networking::{GossipBridge, SessionId};
 use uuid::Uuid;
 
+use control_socket::spawn_control_socket;
+
 /// Session ID to use for network initialization
 ///
 /// This resource must be inserted before setup_gossip_networking runs.
@@ -222,11 +226,12 @@ async fn init_gossip(session_id: SessionId) -> Result<GossipBridge> {
     let (sender, mut receiver) = subscribe_handle.split();
 
     // Wait for join (with timeout since we might be the first node)
-    info!("Waiting for gossip join...");
-    match tokio::time::timeout(std::time::Duration::from_secs(2), receiver.joined()).await {
-        | Ok(Ok(())) => info!("Joined gossip swarm"),
+    // Increased timeout to 10s to allow mDNS discovery to work
+    info!("Waiting for gossip join (10s timeout for mDNS discovery)...");
+    match tokio::time::timeout(std::time::Duration::from_secs(10), receiver.joined()).await {
+        | Ok(Ok(())) => info!("Joined gossip swarm successfully"),
         | Ok(Err(e)) => warn!("Join error: {} (proceeding anyway)", e),
-        | Err(_) => info!("Join timeout (first node in swarm)"),
+        | Err(_) => info!("Join timeout - likely first node in swarm (proceeding anyway)"),
     }
 
     // Create bridge
@@ -236,6 +241,9 @@ async fn init_gossip(session_id: SessionId) -> Result<GossipBridge> {
     // Spawn forwarding tasks - pass endpoint, router, gossip to keep them alive
     spawn_bridge_tasks(sender, receiver, bridge.clone(), endpoint, router, gossip);
 
+    // Spawn control socket server for remote control (debug only)
+    spawn_control_socket(session_id, bridge.clone(), node_id);
+
     Ok(bridge)
 }
 
@@ -301,14 +309,26 @@ fn spawn_bridge_tasks(
         loop {
             match tokio::time::timeout(Duration::from_millis(100), receiver.next()).await {
                 | Ok(Some(Ok(event))) => {
-                    if let iroh_gossip::api::Event::Received(msg) = event {
-                        if let Ok(versioned_msg) =
-                            rkyv::from_bytes::<VersionedMessage, rkyv::rancor::Failure>(&msg.content)
-                        {
-                            if let Err(e) = bridge_in.push_incoming(versioned_msg) {
-                                error!("[Node {}] Push incoming failed: {}", node_id, e);
+                    match event {
+                        | iroh_gossip::api::Event::Received(msg) => {
+                            info!("[Node {}] Received message from gossip", node_id);
+                            if let Ok(versioned_msg) =
+                                rkyv::from_bytes::<VersionedMessage, rkyv::rancor::Failure>(&msg.content)
+                            {
+                                if let Err(e) = bridge_in.push_incoming(versioned_msg) {
+                                    error!("[Node {}] Push incoming failed: {}", node_id, e);
+                                }
                             }
-                        }
+                        },
+                        | iroh_gossip::api::Event::NeighborUp(peer_id) => {
+                            info!("[Node {}] Peer connected: {}", node_id, peer_id);
+                        },
+                        | iroh_gossip::api::Event::NeighborDown(peer_id) => {
+                            warn!("[Node {}] Peer disconnected: {}", node_id, peer_id);
+                        },
+                        | iroh_gossip::api::Event::Lagged => {
+                            warn!("[Node {}] Event stream lagged - some events may have been missed", node_id);
+                        },
                     }
                 },
                 | Ok(Some(Err(e))) => error!("[Node {}] Receiver error: {}", node_id, e),

crates/libmarathon/src/networking/control.rs

@@ -0,0 +1,170 @@
+//! Control socket protocol for remote engine control
+//!
+//! This module defines the message protocol for controlling the engine via
+//! Unix domain sockets without exposing network ports. Used for testing,
+//! validation, and programmatic control of sessions.
+//!
+//! # Security
+//!
+//! Currently debug-only. See issue #135 for production security requirements.
+
+use uuid::Uuid;
+
+use crate::networking::{
+    SessionId,
+    SessionState,
+    SyncMessage,
+    VersionedMessage,
+};
+
+/// Control command sent to the engine
+#[derive(Debug, Clone, rkyv::Archive, rkyv::Serialize, rkyv::Deserialize)]
+pub enum ControlCommand {
+    /// Get current session status
+    GetStatus,
+
+    /// Send a test message through gossip
+    SendTestMessage { content: String },
+
+    /// Inject a message directly into the incoming queue (for testing)
+    InjectMessage { message: VersionedMessage },
+
+    /// Broadcast a full sync message through gossip
+    BroadcastMessage { message: SyncMessage },
+
+    /// Request graceful shutdown
+    Shutdown,
+
+    // Session lifecycle commands
+
+    /// Join a specific session by code
+    JoinSession { session_code: String },
+
+    /// Leave the current session gracefully
+    LeaveSession,
+
+    /// Get detailed current session information
+    GetSessionInfo,
+
+    /// List all sessions in the database
+    ListSessions,
+
+    /// Delete a session from the database
+    DeleteSession { session_code: String },
+
+    /// Get list of connected peers in current session
+    ListPeers,
+
+    // Entity commands
+
+    /// Spawn an entity with a given type and position
+    SpawnEntity {
+        entity_type: String,
+        position: [f32; 3],
+    },
+
+    /// Delete an entity by its UUID
+    DeleteEntity { entity_id: Uuid },
+}
+
+/// Detailed session information
+#[derive(Debug, Clone, rkyv::Archive, rkyv::Serialize, rkyv::Deserialize)]
+pub struct SessionInfo {
+    pub session_id: SessionId,
+    pub session_name: Option<String>,
+    pub state: SessionState,
+    pub created_at: i64,
+    pub last_active: i64,
+    pub entity_count: usize,
+}
+
+/// Peer information
+#[derive(Debug, Clone, rkyv::Archive, rkyv::Serialize, rkyv::Deserialize)]
+pub struct PeerInfo {
+    pub node_id: Uuid,
+    pub connected_since: Option<i64>,
+}
+
+/// Response from the engine to a control command
+#[derive(Debug, Clone, rkyv::Archive, rkyv::Serialize, rkyv::Deserialize)]
+pub enum ControlResponse {
+    /// Session status information
+    Status {
+        node_id: Uuid,
+        session_id: SessionId,
+        outgoing_queue_size: usize,
+        incoming_queue_size: usize,
+        /// Number of connected peers (if available from gossip)
+        connected_peers: Option<usize>,
+    },
+
+    /// Detailed session information
+    SessionInfo(SessionInfo),
+
+    /// List of sessions
+    Sessions(Vec<SessionInfo>),
+
+    /// List of connected peers
+    Peers(Vec<PeerInfo>),
+
+    /// Acknowledgment of command execution
+    Ok { message: String },
+
+    /// Error occurred during command execution
+    Error { error: String },
+}
+
+impl ControlCommand {
+    /// Serialize a command to bytes using rkyv
+    pub fn to_bytes(&self) -> Result<Vec<u8>, rkyv::rancor::Error> {
+        rkyv::to_bytes::<rkyv::rancor::Error>(self).map(|b| b.to_vec())
+    }
+
+    /// Deserialize a command from bytes using rkyv
+    pub fn from_bytes(bytes: &[u8]) -> Result<Self, rkyv::rancor::Error> {
+        rkyv::from_bytes::<Self, rkyv::rancor::Error>(bytes)
+    }
+}
+
+impl ControlResponse {
+    /// Serialize a response to bytes using rkyv
+    pub fn to_bytes(&self) -> Result<Vec<u8>, rkyv::rancor::Error> {
+        rkyv::to_bytes::<rkyv::rancor::Error>(self).map(|b| b.to_vec())
+    }
+
+    /// Deserialize a response from bytes using rkyv
+    pub fn from_bytes(bytes: &[u8]) -> Result<Self, rkyv::rancor::Error> {
+        rkyv::from_bytes::<Self, rkyv::rancor::Error>(bytes)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_command_roundtrip() {
+        let cmd = ControlCommand::GetStatus;
+        let bytes = cmd.to_bytes().unwrap();
+        let decoded = ControlCommand::from_bytes(&bytes).unwrap();
+
+        match decoded {
+            | ControlCommand::GetStatus => {},
+            | _ => panic!("Failed to decode GetStatus"),
+        }
+    }
+
+    #[test]
+    fn test_response_roundtrip() {
+        let resp = ControlResponse::Ok {
+            message: "Test".to_string(),
+        };
+        let bytes = resp.to_bytes().unwrap();
+        let decoded = ControlResponse::from_bytes(&bytes).unwrap();
+
+        match decoded {
+            | ControlResponse::Ok { message } => assert_eq!(message, "Test"),
+            | _ => panic!("Failed to decode Ok response"),
+        }
+    }
+}

crates/libmarathon/src/networking/delta_generation.rs

@@ -52,7 +52,7 @@ impl NodeVectorClock {
 /// System to generate and broadcast EntityDelta messages
 ///
 /// This system:
-/// 1. Queries for Changed<NetworkedEntity>
+/// 1. Queries for Added<NetworkedEntity> or Changed<NetworkedEntity>
 /// 2. Serializes all components on those entities
 /// 3. Builds EntityDelta messages
 /// 4. Broadcasts via GossipBridge
@@ -73,7 +73,7 @@ pub fn generate_delta_system(world: &mut World) {
 
     let changed_entities: Vec<(Entity, uuid::Uuid, uuid::Uuid)> = {
         let mut query =
-            world.query_filtered::<(Entity, &NetworkedEntity), Changed<NetworkedEntity>>();
+            world.query_filtered::<(Entity, &NetworkedEntity), Or<(Added<NetworkedEntity>, Changed<NetworkedEntity>)>>();
         query
             .iter(world)
             .map(|(entity, networked)| (entity, networked.network_id, networked.owner_node_id))

crates/libmarathon/src/networking/mod.rs

@@ -36,6 +36,7 @@ mod auth;
 mod blob_support;
 mod change_detection;
 mod components;
+mod control;
 mod delta_generation;
 mod entity_map;
 mod error;
@@ -62,6 +63,7 @@ pub use auth::*;
 pub use blob_support::*;
 pub use change_detection::*;
 pub use components::*;
+pub use control::*;
 pub use delta_generation::*;
 pub use entity_map::*;
 pub use error::*;

crates/libmarathon/src/networking/session_lifecycle.rs

@@ -168,7 +168,8 @@ pub fn save_session_on_shutdown_system(world: &mut World) {
 
     // Update session metadata
     session.touch();
-    session.transition_to(SessionState::Left);
+    // Note: We don't transition to Left here - that only happens on actual shutdown
+    // This periodic save just persists the current state
 
     // Count entities in the world
     let entity_count = world