diff --git a/Cargo.lock b/Cargo.lock
index 05e1059..3b63a26 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -267,6 +267,7 @@ dependencies = [
  "anyhow",
  "bevy",
  "bytes",
+ "clap",
  "crossbeam-channel",
  "egui",
  "futures-lite",
diff --git a/crates/app/Cargo.toml b/crates/app/Cargo.toml
index e77d010..44a804a 100644
--- a/crates/app/Cargo.toml
+++ b/crates/app/Cargo.toml
@@ -34,6 +34,7 @@ futures-lite = "2.0"
 rkyv = { workspace = true }
 bytes = "1.0"
 crossbeam-channel = "0.5.15"
+clap = { version = "4.0", features = ["derive"] }
 
 [target.'cfg(target_os = "ios")'.dependencies]
 objc = "0.2"
diff --git a/crates/app/src/bin/marathonctl.rs b/crates/app/src/bin/marathonctl.rs
new file mode 100644
index 0000000..6f86ef8
--- /dev/null
+++ b/crates/app/src/bin/marathonctl.rs
@@ -0,0 +1,193 @@
+//! Marathon control CLI
+//!
+//! Send control commands to a running Marathon instance via Unix domain socket.
+//!
+//! # Usage
+//!
+//! ```bash
+//! # Get session status
+//! marathonctl status
+//!
+//! # Start networking with a session
+//! marathonctl start <session-code>
+//!
+//! # Use custom socket
+//! marathonctl --socket /tmp/marathon1.sock status
+//! ```
+
+use clap::{Parser, Subcommand};
+use std::io::{Read, Write};
+use std::os::unix::net::UnixStream;
+
+use libmarathon::networking::{ControlCommand, ControlResponse, SessionId};
+
+/// Marathon control CLI
+#[derive(Parser, Debug)]
+#[command(version, about, long_about = None)]
+struct Args {
+    /// Path to the control socket
+    #[arg(long, default_value = "/tmp/marathon-control.sock")]
+    socket: String,
+
+    #[command(subcommand)]
+    command: Commands,
+}
+
+#[derive(Subcommand, Debug)]
+enum Commands {
+    /// Start networking with a session
+    Start {
+        /// Session code (e.g., abc-def-123)
+        session_code: String,
+    },
+    /// Stop networking
+    Stop,
+    /// Get current session status
+    Status,
+    /// Send a test message
+    Test {
+        /// Message content
+        content: String,
+    },
+    /// Broadcast a ping message
+    Ping,
+}
+
+fn main() {
+    let args = Args::parse();
+
+    // Build command from subcommand
+    let command = match args.command {
+        Commands::Start { session_code } => ControlCommand::JoinSession { session_code },
+        Commands::Stop => ControlCommand::LeaveSession,
+        Commands::Status => ControlCommand::GetStatus,
+        Commands::Test { content } => ControlCommand::SendTestMessage { content },
+        Commands::Ping => {
+            use libmarathon::networking::{SyncMessage, VectorClock};
+            use uuid::Uuid;
+
+            // For ping, we send a SyncRequest (lightweight ping-like message)
+            let node_id = Uuid::new_v4();
+            ControlCommand::BroadcastMessage {
+                message: SyncMessage::SyncRequest {
+                    node_id,
+                    vector_clock: VectorClock::new(),
+                },
+            }
+        }
+    };
+
+    // Connect to Unix socket
+    let socket_path = &args.socket;
+    let mut stream = match UnixStream::connect(&socket_path) {
+        Ok(s) => s,
+        Err(e) => {
+            eprintln!("Failed to connect to {}: {}", socket_path, e);
+            eprintln!("Is the Marathon app running?");
+            std::process::exit(1);
+        }
+    };
+
+    // Send command
+    if let Err(e) = send_command(&mut stream, &command) {
+        eprintln!("Failed to send command: {}", e);
+        std::process::exit(1);
+    }
+
+    // Receive response
+    match receive_response(&mut stream) {
+        Ok(response) => {
+            print_response(response);
+        }
+        Err(e) => {
+            eprintln!("Failed to receive response: {}", e);
+            std::process::exit(1);
+        }
+    }
+}
+
+fn send_command(stream: &mut UnixStream, command: &ControlCommand) -> Result<(), Box<dyn std::error::Error>> {
+    let bytes = command.to_bytes()?;
+    let len = bytes.len() as u32;
+
+    // Write length prefix
+    stream.write_all(&len.to_le_bytes())?;
+    // Write command bytes
+    stream.write_all(&bytes)?;
+    stream.flush()?;
+
+    Ok(())
+}
+
+fn receive_response(stream: &mut UnixStream) -> Result<ControlResponse, Box<dyn std::error::Error>> {
+    // Read length prefix
+    let mut len_buf = [0u8; 4];
+    stream.read_exact(&mut len_buf)?;
+    let len = u32::from_le_bytes(len_buf) as usize;
+
+    // Read response bytes
+    let mut response_buf = vec![0u8; len];
+    stream.read_exact(&mut response_buf)?;
+
+    // Deserialize response
+    let response = ControlResponse::from_bytes(&response_buf)?;
+    Ok(response)
+}
+
+fn print_response(response: ControlResponse) {
+    use libmarathon::networking::{SessionInfo, PeerInfo};
+
+    match response {
+        ControlResponse::Status {
+            node_id,
+            session_id,
+            outgoing_queue_size,
+            incoming_queue_size,
+            connected_peers,
+        } => {
+            println!("Session Status:");
+            println!("  Node ID: {}", node_id);
+            println!("  Session: {}", session_id);
+            println!("  Outgoing Queue: {} messages", outgoing_queue_size);
+            println!("  Incoming Queue: {} messages", incoming_queue_size);
+            if let Some(peers) = connected_peers {
+                println!("  Connected Peers: {}", peers);
+            }
+        }
+        ControlResponse::SessionInfo(info) => {
+            println!("Session Info:");
+            println!("  ID: {}", info.session_id);
+            if let Some(ref name) = info.session_name {
+                println!("  Name: {}", name);
+            }
+            println!("  State: {:?}", info.state);
+            println!("  Entities: {}", info.entity_count);
+            println!("  Created: {}", info.created_at);
+            println!("  Last Active: {}", info.last_active);
+        }
+        ControlResponse::Sessions(sessions) => {
+            println!("Sessions ({} total):", sessions.len());
+            for session in sessions {
+                println!("  {}: {:?} ({} entities)", session.session_id, session.state, session.entity_count);
+            }
+        }
+        ControlResponse::Peers(peers) => {
+            println!("Connected Peers ({} total):", peers.len());
+            for peer in peers {
+                print!("  {}", peer.node_id);
+                if let Some(since) = peer.connected_since {
+                    println!(" (connected since: {})", since);
+                } else {
+                    println!();
+                }
+            }
+        }
+        ControlResponse::Ok { message } => {
+            println!("Success: {}", message);
+        }
+        ControlResponse::Error { error } => {
+            eprintln!("Error: {}", error);
+            std::process::exit(1);
+        }
+    }
+}
diff --git a/crates/app/src/control.rs b/crates/app/src/control.rs
new file mode 100644
index 0000000..4ae3e67
--- /dev/null
+++ b/crates/app/src/control.rs
@@ -0,0 +1,159 @@
+//! Standalone control socket for engine control
+//!
+//! This control socket starts at app launch and allows external control
+//! of the engine, including starting/stopping networking, before any
+//! networking is initialized.
+
+use anyhow::Result;
+use bevy::prelude::*;
+use libmarathon::{
+    engine::{EngineBridge, EngineCommand},
+    networking::{ControlCommand, ControlResponse, SessionId},
+};
+
+/// Resource holding the control socket path
+#[derive(Resource)]
+pub struct ControlSocketPath(pub String);
+
+/// 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};
+    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
+    let bridge = bridge.clone();
+
+    // Spawn tokio runtime in background thread
+    std::thread::spawn(move || {
+        let rt = tokio::runtime::Runtime::new().unwrap();
+        rt.block_on(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: {}", e);
+                    return;
+                }
+            };
+
+            // Accept connections in a loop
+            loop {
+                match listener.accept().await {
+                    Ok((mut stream, _addr)) => {
+                        let bridge = bridge.clone();
+
+                        tokio::spawn(async move {
+                            // Read command length
+                            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: {}", e),
+                                    };
+                                    let _ = send_response(&mut stream, response).await;
+                                    return;
+                                }
+                            };
+
+                            info!("Received control command: {:?}", command);
+
+                            // Handle command
+                            let response = handle_command(command, &bridge).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 connection: {}", e);
+                    }
+                }
+            }
+        });
+    });
+}
+
+/// 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 {
+    match command {
+        ControlCommand::JoinSession { session_code } => {
+            match SessionId::from_code(&session_code) {
+                Ok(session_id) => {
+                    bridge.send_command(EngineCommand::StartNetworking {
+                        session_id: session_id.clone(),
+                    });
+                    ControlResponse::Ok {
+                        message: format!("Starting networking with session: {}", session_id),
+                    }
+                }
+                Err(e) => ControlResponse::Error {
+                    error: format!("Invalid session code: {}", e),
+                },
+            }
+        }
+
+        ControlCommand::LeaveSession => {
+            bridge.send_command(EngineCommand::StopNetworking);
+            ControlResponse::Ok {
+                message: "Stopping networking".to_string(),
+            }
+        }
+
+        _ => ControlResponse::Error {
+            error: format!("Command {:?} not yet implemented", command),
+        },
+    }
+}
+
+/// 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;
+
+    stream.write_all(&len.to_le_bytes()).await?;
+    stream.write_all(&bytes).await?;
+    stream.flush().await?;
+
+    Ok(())
+}
+
+// No-op stubs for iOS and release builds
+#[cfg(any(target_os = "ios", not(debug_assertions)))]
+pub fn start_control_socket_system() {}
diff --git a/crates/app/src/main.rs b/crates/app/src/main.rs
index 037e9f7..13368d1 100644
--- a/crates/app/src/main.rs
+++ b/crates/app/src/main.rs
@@ -3,6 +3,7 @@
 //! This demonstrates real-time CRDT synchronization with Apple Pencil input.
 
 use bevy::prelude::*;
+use clap::Parser;
 use libmarathon::{
     engine::{
         EngineBridge,
@@ -16,6 +17,19 @@ use bevy::app::ScheduleRunnerPlugin;
 #[cfg(feature = "headless")]
 use std::time::Duration;
 
+/// Marathon - CRDT-based collaborative editing engine
+#[derive(Parser, Debug)]
+#[command(version, about, long_about = None)]
+struct Args {
+    /// Path to the database file
+    #[arg(long, default_value = "marathon.db")]
+    db_path: String,
+
+    /// Path to the control socket (Unix domain socket)
+    #[arg(long, default_value = "/tmp/marathon-control.sock")]
+    control_socket: String,
+}
+
 mod camera;
 mod control;
 mod cube;
@@ -40,6 +54,9 @@ use session::*;
 use session_ui::*;
 
 fn main() {
+    // Parse command-line arguments
+    let args = Args::parse();
+
     // Note: eprintln doesn't work on iOS, but tracing-oslog will once initialized
     eprintln!(">>> RUST ENTRY: main() started");
 
@@ -81,9 +98,8 @@ fn main() {
     // Application configuration
     const APP_NAME: &str = "Aspen";
 
-    // Get platform-appropriate database path
-    eprintln!(">>> Getting database path");
-    let db_path = libmarathon::platform::get_database_path(APP_NAME);
+    // Use database path from CLI args
+    let db_path = std::path::PathBuf::from(&args.db_path);
     let db_path_str = db_path.to_str().unwrap().to_string();
     info!("Database path: {}", db_path_str);
     eprintln!(">>> Database path: {}", db_path_str);
@@ -185,6 +201,9 @@ fn main() {
     app.add_plugins(EngineBridgePlugin);
     app.add_plugins(CubePlugin);
     app.add_systems(Startup, initialize_offline_resources);
+
+    // Insert control socket path as resource
+    app.insert_resource(control::ControlSocketPath(args.control_socket.clone()));
     app.add_systems(Startup, control::start_control_socket_system);
 
     // Rendering-only plugins