diff --git a/README.md b/README.md
index 73d090a..1f79a79 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # 🏮 Roj1 (Roji)
 
 ![CI Status](https://github.com/1ureka/roj1/actions/workflows/ci.yml/badge.svg)
-![Go Report Card](https://goreportcard.com/badge/github.com/1ureka/roj1)
+[![Go Report Card](https://goreportcard.com/badge/github.com/1ureka/roj1)](https://goreportcard.com/report/github.com/1ureka/roj1)
 
 `Roj1` (pronounced as *Roji*, Japanese for "alleyway") is a lightweight tool that carves a private, **1-to-1** path between any two points on the internet. Share Minecraft servers, AI APIs, or local databases directly and securely—without port forwarding, static IPs, or middleman fees.
 
@@ -56,6 +56,35 @@ The **Host** needs [Visual Studio Code](https://code.visualstudio.com/) installe
 
 ---
 
+## CLI Arguments
+
+For automation or LAN setups, **Roj1** can be launched entirely from the command line, bypassing the interactive prompts. If `-role` is omitted, the tool falls back to the default interactive mode.
+
+| Flag | Description | Applies To |
+| --- | --- | --- |
+| `-role` | `host` or `client` | Both |
+| `-port` | Target port (Host) or virtual service port (Client) | Both |
+| `-wsPort` | WebSocket signaling server port (default: random) | Host |
+| `-wsUrl` | WebSocket URL to connect to | Client |
+| `-wsListen` | Listen on all network interfaces (LAN-accessible) | Host |
+| `-debug` | Enable debug logging | Both |
+
+**Host example:**
+
+```sh
+roj1 -role host -port 25565 -wsPort 9000 -wsListen
+```
+
+**Client example:**
+
+```sh
+roj1 -role client -port 25565 -wsUrl ws://192.168.1.10:9000/ws
+```
+
+> **TIP:** When both machines are on the same local network, use `-wsListen` on the Host to make the WebSocket signaling server directly reachable via LAN IP. This eliminates the need for VS Code Port Forwarding entirely — the Client simply connects using `ws://<host-lan-ip>:<wsPort>/ws`.
+
+---
+
 ## Network Compatibility
 
 * **Optimal:** Fiber, Home Wi-Fi, 4G/5G mobile hotspots.
diff --git a/cmd/roj1/main.go b/cmd/roj1/main.go
index 172b102..b128180 100644
--- a/cmd/roj1/main.go
+++ b/cmd/roj1/main.go
@@ -3,6 +3,9 @@
 // This tool creates a P2P tunnel over WebRTC DataChannel, forwarding a remote
 // TCP service to a local port. No relay servers are needed after the signaling
 // phase (which uses WebSocket).
+//
+// It can be launched interactively (no flags) or non-interactively via CLI
+// flags (-role, -port, -wsPort, -wsUrl, -wsListen).
 package main
 
 import (
@@ -29,6 +32,12 @@ func main() {
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
 	defer stop()
 
+	// CLI flags.
+	role := flag.String("role", "", "Role: host or client")
+	port := flag.Int("port", 0, "Target port (host) or virtual service port (client), 1~65535")
+	wsPortFlag := flag.Int("wsPort", 0, "WebSocket signaling server port (host only)")
+	wsURLFlag := flag.String("wsUrl", "", "WebSocket URL to connect to (client only)")
+	wsListenFlag := flag.Bool("wsListen", false, "Listen on all network interfaces (host only, for LAN access)")
 	debugMode := flag.Bool("debug", false, "Enable debug logging")
 	flag.Parse()
 
@@ -39,56 +48,134 @@ func main() {
 	pterm.Info.Println(fmt.Sprintf("Roj1 — v%s", version))
 	pterm.Println()
 
-	role, _ := pterm.DefaultInteractiveSelect.
-		WithOptions([]string{"Host  — Expose a local service", "Client — Connect to a remote host"}).
-		WithDefaultText("Select your role").
-		Show()
-
-	pterm.Println()
+	switch *role {
+	case "":
+		// No -role flag → interactive mode.
+		runInteractive(ctx)
 
-	// ---- Run the appropriate tunnel logic based on the selected role ------------------------------
+	case "host":
+		if *port < 1 || *port > 65535 {
+			util.LogError("invalid or missing -port (must be 1~65535)")
+			os.Exit(1)
+		}
 
-	if strings.HasPrefix(role, "Host") {
-		port := askPort("Target port to forward (1 ~ 65535)")
+		var wsAddr string
 
-		tr, err := signaling.EstablishAsHost(ctx)
-		if err != nil {
-			util.LogError("failed to establish tunnel: %v", err)
-			os.Exit(1)
+		switch {
+		case *wsListenFlag:
+			wsAddr = fmt.Sprintf(":%d", *wsPortFlag)
+		case *wsPortFlag > 0:
+			wsAddr = fmt.Sprintf("127.0.0.1:%d", *wsPortFlag)
+		default:
+			wsAddr = ":0"
 		}
-		defer tr.Close()
 
-		util.StartStatsReporter(ctx)
-		util.LogSuccess("P2P tunnel established — forwarding traffic to 127.0.0.1:%d", port)
+		runHost(ctx, *port, wsAddr)
 
-		if err := adapter.RunAsHost(ctx, tr, fmt.Sprintf("127.0.0.1:%d", port)); err != nil {
-			util.LogError("failed to handle tunnel connection: %v", err)
+	case "client":
+		if *port < 1 || *port > 65535 {
+			util.LogError("invalid or missing -port (must be 1~65535)")
 			os.Exit(1)
 		}
-	} else {
-		wsURL := askURL()
-		port := askPort("Local port for virtual service (1 ~ 65535)")
 
-		tr, err := signaling.EstablishAsClient(ctx, wsURL)
-		if err != nil {
-			util.LogError("failed to establish tunnel: %v", err)
+		if *wsURLFlag == "" {
+			util.LogError("missing -wsUrl for client role")
 			os.Exit(1)
 		}
-		defer tr.Close()
 
-		util.StartStatsReporter(ctx)
-		util.LogSuccess("P2P tunnel established — forwarding traffic to Host")
+		wsURL, err := normalizeWSURL(*wsURLFlag)
 
-		if err := adapter.RunAsClient(ctx, tr, fmt.Sprintf("127.0.0.1:%d", port)); err != nil {
-			util.LogError("failed to handle tunnel connection: %v", err)
+		if err != nil {
+			util.LogError("%v", err)
 			os.Exit(1)
 		}
+
+		runClient(ctx, *port, wsURL)
+
+	default:
+		util.LogError("invalid -role: must be 'host' or 'client'")
+		os.Exit(1)
 	}
 
 	util.LogInfo("successfully closed tunnel connection")
 }
 
-// ----------- Helper Functions ------------------------------------------------------
+// ---------------------------------------------------------------------------
+// Run modes
+// ---------------------------------------------------------------------------
+
+// runInteractive falls back to the original interactive prompts when no -role
+// flag is provided.
+func runInteractive(ctx context.Context) {
+	role, _ := pterm.DefaultInteractiveSelect.
+		WithOptions([]string{"Host  — Expose a local service", "Client — Connect to a remote host"}).
+		WithDefaultText("Select your role").
+		Show()
+
+	pterm.Println()
+
+	if strings.HasPrefix(role, "Host") {
+		port := askPort("Target port to forward (1 ~ 65535)")
+		runHost(ctx, port, ":0")
+	} else {
+		wsURL := askURL()
+		port := askPort("Local port for virtual service (1 ~ 65535)")
+		runClient(ctx, port, wsURL)
+	}
+}
+
+// runHost executes the host-side tunnel logic.
+func runHost(ctx context.Context, port int, wsAddr string) {
+	tr, err := signaling.EstablishAsHost(ctx, wsAddr)
+	if err != nil {
+		util.LogError("failed to establish tunnel: %v", err)
+		os.Exit(1)
+	}
+	defer tr.Close()
+
+	util.StartStatsReporter(ctx)
+	util.LogSuccess("P2P tunnel established — forwarding traffic to 127.0.0.1:%d", port)
+
+	if err := adapter.RunAsHost(ctx, tr, fmt.Sprintf("127.0.0.1:%d", port)); err != nil {
+		util.LogError("failed to handle tunnel connection: %v", err)
+		os.Exit(1)
+	}
+}
+
+// runClient executes the client-side tunnel logic.
+func runClient(ctx context.Context, port int, wsURL string) {
+	tr, err := signaling.EstablishAsClient(ctx, wsURL)
+	if err != nil {
+		util.LogError("failed to establish tunnel: %v", err)
+		os.Exit(1)
+	}
+	defer tr.Close()
+
+	util.StartStatsReporter(ctx)
+	util.LogSuccess("P2P tunnel established — forwarding traffic to Host")
+
+	if err := adapter.RunAsClient(ctx, tr, fmt.Sprintf("127.0.0.1:%d", port)); err != nil {
+		util.LogError("failed to handle tunnel connection: %v", err)
+		os.Exit(1)
+	}
+}
+
+// ---------------------------------------------------------------------------
+// Helper Functions
+// ---------------------------------------------------------------------------
+
+// normalizeWSURL validates and normalizes a raw WebSocket URL string.
+func normalizeWSURL(raw string) (string, error) {
+	u, err := url.Parse(strings.TrimSpace(raw))
+	if err != nil || u.Host == "" {
+		return "", fmt.Errorf("invalid WebSocket URL: %s", raw)
+	}
+	scheme := "wss"
+	if u.Scheme == "ws" || u.Scheme == "wss" {
+		scheme = u.Scheme
+	}
+	return fmt.Sprintf("%s://%s/ws", scheme, u.Host), nil
+}
 
 // askPort prompts the user for a port number until a valid one is entered.
 func askPort(prompt string) int {
@@ -115,15 +202,10 @@ func askURL() string {
 			WithDefaultText("WebSocket URL (e.g. wss://***.asse.devtunnels.ms/ws)").
 			Show()
 
-		url, err := url.Parse(strings.TrimSpace(raw))
-		if err == nil && url.Host != "" {
-			var scheme = "wss"
-			if url.Scheme == "ws" || url.Scheme == "wss" {
-				scheme = url.Scheme
-			}
-
+		wsURL, err := normalizeWSURL(raw)
+		if err == nil {
 			pterm.Println()
-			return fmt.Sprintf("%s://%s/ws", scheme, url.Host)
+			return wsURL
 		}
 
 		pterm.Println()
diff --git a/internal/signaling/signaling.go b/internal/signaling/signaling.go
index d3b8010..8f3a5da 100644
--- a/internal/signaling/signaling.go
+++ b/internal/signaling/signaling.go
@@ -17,21 +17,21 @@ import (
 )
 
 // EstablishAsHost executes the full host-side signaling flow:
-//  1. Start a WS server on a random port
+//  1. Start a WS server on wsAddr (e.g. ":0" for random port)
 //  2. Wait for the client to connect
 //  3. Create a Transport
 //  4. Perform SDP/ICE exchange
 //  5. Wait for the DataChannel to be ready
 //  6. Close the WS server and connection (resource cleanup)
 //  7. Return the ready Transport
-func EstablishAsHost(ctx context.Context) (*transport.Transport, error) {
+func EstablishAsHost(ctx context.Context, wsAddr string) (*transport.Transport, error) {
 	// 1. Start WS server.
 	spinner, _ := pterm.DefaultSpinner.
 		WithRemoveWhenDone(true).
 		Start("starting WebSocket signaling server...")
 
 	srv := &server{connCh: make(chan *websocket.Conn, 1)}
-	wsPort, err := srv.start()
+	wsPort, err := srv.start(wsAddr)
 	if err != nil {
 		spinner.Fail("failed to start WebSocket server")
 		return nil, err
diff --git a/internal/signaling/ws.go b/internal/signaling/ws.go
index 898c839..08f1d43 100644
--- a/internal/signaling/ws.go
+++ b/internal/signaling/ws.go
@@ -19,9 +19,10 @@ type server struct {
 	connCh   chan *websocket.Conn
 }
 
-// start begins listening on a random port. Returns the assigned port number.
-func (s *server) start() (int, error) {
-	listener, err := net.Listen("tcp", ":0")
+// start begins listening on the given address (e.g. ":0", "127.0.0.1:9000").
+// Returns the assigned port number.
+func (s *server) start(addr string) (int, error) {
+	listener, err := net.Listen("tcp", addr)
 	if err != nil {
 		return 0, fmt.Errorf("failed to start WS server: %w", err)
 	}
diff --git a/internal/transport/transport.go b/internal/transport/transport.go
index 9bc74c1..f64f2d3 100644
--- a/internal/transport/transport.go
+++ b/internal/transport/transport.go
@@ -73,12 +73,18 @@ func NewTransport(ctx context.Context) (*Transport, error) {
 		tCancel()
 	})
 
-	// Record PC state (informational only).
+	// Record PC state; auto-close on "failed" (pion/webrtc does not
+	// propagate failed → DC close like browsers do).
 	pc.OnConnectionStateChange(func(state webrtc.PeerConnectionState) {
 		util.LogInfo("PeerConnection state changed → %s", state)
 		t.mu.Lock()
 		t.pcState = state
 		t.mu.Unlock()
+
+		if state == webrtc.PeerConnectionStateFailed {
+			util.LogWarning("PeerConnection entered failed state — closing transport")
+			tCancel()
+		}
 	})
 
 	// Start the sender goroutine.