Add plain-text mode for Windows telnet compatibility

CLAUDE.md

@@ -11,6 +11,7 @@ make build              # or: go build -o chat-server ./cmd/ts-chat
 # Run the server
 make run                # builds and runs
 ./chat-server           # run directly
+./chat-server --plain-text  # run with plain-text mode (Windows telnet compatibility)
 
 # Run tests
 make test               # runs: go test -v ./internal/chat/

README.md

@@ -64,6 +64,23 @@ docker run -e TS_AUTHKEY=tskey-auth-xxxxx chat-tails --tailscale --hostname mych
 | `--hostname` | `-H` | "chatroom" | Tailscale hostname (requires `--tailscale`) |
 | `--history` | | false | Enable message history for new users |
 | `--history-size` | | 50 | Number of messages to keep in history |
+| `--plain-text` | | false | Disable ANSI formatting (for Windows telnet) |
+| `--version` | `-v` | | Show version information |
+
+## Windows Telnet Compatibility
+
+Windows telnet has limited ANSI escape sequence support. If you see garbled formatting characters when connecting from Windows telnet, start the server with the `--plain-text` flag:
+
+```bash
+./chat-server --plain-text
+```
+
+This disables all ANSI color codes and cursor control sequences for a better experience on legacy telnet clients.
+
+**Recommended:** For the best experience on Windows, use a modern terminal emulator like:
+- Windows Terminal with `telnet` or `ssh`
+- PuTTY
+- WSL with `nc` or `telnet`
 
 ## Tailscale Setup
 

cmd/chat-tails/main.go

@@ -34,6 +34,7 @@ type config struct {
 	HostName        string
 	EnableHistory   bool
 	HistorySize     int
+	PlainText       bool
 }
 
 func main() {
@@ -72,6 +73,7 @@ func main() {
 		HostName:        cfg.HostName,
 		EnableHistory:   cfg.EnableHistory,
 		HistorySize:     cfg.HistorySize,
+		PlainText:       cfg.PlainText,
 	})
 	if err != nil {
 		log.Fatalf("Failed to create server: %v", err)
@@ -116,6 +118,7 @@ func parseFlags() (config, bool) {
 	pflag.StringVarP(&cfg.HostName, "hostname", "H", defaultHostname, "Tailscale hostname (only used if --tailscale is enabled)")
 	pflag.BoolVar(&cfg.EnableHistory, "history", false, "Enable message history for new users")
 	pflag.IntVar(&cfg.HistorySize, "history-size", defaultHistorySize, "Number of messages to keep in history")
+	pflag.BoolVar(&cfg.PlainText, "plain-text", false, "Disable ANSI formatting (for Windows telnet compatibility)")
 	pflag.BoolVarP(&showVersion, "version", "v", false, "Show version information")
 
 	// Display help message

internal/chat/client.go

@@ -118,7 +118,13 @@ func NewClient(conn net.Conn, room *Room) (*Client, error) {
 // requestNickname asks the user for a nickname
 func (c *Client) requestNickname() error {
 	// Send welcome message
-	if err := c.write(ui.FormatTitle("Welcome to Chat Tails") + "\r\n\r\n"); err != nil {
+	var welcomeTitle string
+	if c.room.PlainText {
+		welcomeTitle = ui.FormatTitlePlain("Welcome to Chat Tails")
+	} else {
+		welcomeTitle = ui.FormatTitle("Welcome to Chat Tails")
+	}
+	if err := c.write(welcomeTitle + "\r\n\r\n"); err != nil {
 		return fmt.Errorf("failed to write welcome message: %w", err)
 	}
 
@@ -176,13 +182,21 @@ func (c *Client) sendWelcomeMessage() error {
 ║                                                            ║
 ╚════════════════════════════════════════════════════════════╝
 `
-	coloredBanner := ui.SystemStyle.Render(banner)
-	welcomeMsg := ui.FormatWelcomeMessage(c.room.Name, c.Nickname)
-
+	var coloredBanner, welcomeMsg string
+
+	if c.room.PlainText {
+		// In plain text mode, skip the banner styling
+		coloredBanner = banner
+		welcomeMsg = ui.FormatWelcomeMessagePlain(c.room.Name, c.Nickname)
+	} else {
+		coloredBanner = ui.SystemStyle.Render(banner)
+		welcomeMsg = ui.FormatWelcomeMessage(c.room.Name, c.Nickname)
+	}
+
 	if err := c.write(coloredBanner + "\r\n"); err != nil {
 		return fmt.Errorf("failed to write banner: %w", err)
 	}
-	
+
 	if err := c.write(welcomeMsg + "\r\n\r\n"); err != nil {
 		return fmt.Errorf("failed to write welcome message: %w", err)
 	}
@@ -197,13 +211,22 @@ func (c *Client) sendHistory() {
 		return
 	}
 
-	c.write(ui.FormatSystemMessage("--- Recent messages ---") + "\r\n")
+	var headerMsg, footerMsg string
+	if c.room.PlainText {
+		headerMsg = ui.FormatSystemMessagePlain("--- Recent messages ---")
+		footerMsg = ui.FormatSystemMessagePlain("--- End of history ---")
+	} else {
+		headerMsg = ui.FormatSystemMessage("--- Recent messages ---")
+		footerMsg = ui.FormatSystemMessage("--- End of history ---")
+	}
+
+	c.write(headerMsg + "\r\n")
 
 	for _, msg := range history {
 		c.sendMessage(msg)
 	}
 
-	c.write(ui.FormatSystemMessage("--- End of history ---") + "\r\n\r\n")
+	c.write(footerMsg + "\r\n\r\n")
 }
 
 // Handle handles client interactions
@@ -300,7 +323,10 @@ func (c *Client) Handle(ctx context.Context) {
 
 // clearInputLine clears the echoed input line
 func (c *Client) clearInputLine() {
-	c.write(cursorUp + clearLine + cursorToStart)
+	// Skip cursor manipulation in plain text mode
+	if !c.room.PlainText {
+		c.write(cursorUp + clearLine + cursorToStart)
+	}
 }
 
 // showPrompt displays the input prompt
@@ -399,13 +425,23 @@ func (c *Client) handleCommand(cmd string) error {
 // showUserList shows the list of users in the room
 func (c *Client) showUserList() error {
 	users := c.room.GetUserList()
-	msg := ui.FormatUserList(c.room.Name, users, c.room.MaxUsers)
+	var msg string
+	if c.room.PlainText {
+		msg = ui.FormatUserListPlain(c.room.Name, users, c.room.MaxUsers)
+	} else {
+		msg = ui.FormatUserList(c.room.Name, users, c.room.MaxUsers)
+	}
 	return c.write(msg + "\r\n")
 }
 
 // showHelp shows the help message
 func (c *Client) showHelp() error {
-	helpMsg := ui.FormatHelp()
+	var helpMsg string
+	if c.room.PlainText {
+		helpMsg = ui.FormatHelpPlain()
+	} else {
+		helpMsg = ui.FormatHelp()
+	}
 	return c.write(helpMsg + "\r\n")
 }
 
@@ -426,12 +462,24 @@ func (c *Client) sendMessage(msg Message) {
 	var formatted string
 	timeStr := msg.Timestamp.Format("15:04:05")
 
-	if msg.IsSystem {
-		formatted = ui.FormatSystemMessage(msg.Content) + "\r\n"
-	} else if msg.IsAction {
-		formatted = ui.FormatActionMessage(msg.From, msg.Content) + "\r\n"
+	if c.room.PlainText {
+		// Use plain text formatters
+		if msg.IsSystem {
+			formatted = ui.FormatSystemMessagePlain(msg.Content) + "\r\n"
+		} else if msg.IsAction {
+			formatted = ui.FormatActionMessagePlain(msg.From, msg.Content) + "\r\n"
+		} else {
+			formatted = ui.FormatUserMessagePlain(msg.From, msg.Content, timeStr) + "\r\n"
+		}
 	} else {
-		formatted = ui.FormatUserMessage(msg.From, msg.Content, timeStr) + "\r\n"
+		// Use ANSI formatters
+		if msg.IsSystem {
+			formatted = ui.FormatSystemMessage(msg.Content) + "\r\n"
+		} else if msg.IsAction {
+			formatted = ui.FormatActionMessage(msg.From, msg.Content) + "\r\n"
+		} else {
+			formatted = ui.FormatUserMessage(msg.From, msg.Content, timeStr) + "\r\n"
+		}
 	}
 
 	c.mu.Lock()

internal/chat/room.go

@@ -32,10 +32,11 @@ type Room struct {
 	historySize   int
 	history       []Message
 	historyMu     sync.RWMutex
+	PlainText     bool
 }
 
 // NewRoom creates a new chat room
-func NewRoom(name string, maxUsers int, enableHistory bool, historySize int) *Room {
+func NewRoom(name string, maxUsers int, enableHistory bool, historySize int, plainText bool) *Room {
 	ctx, cancel := context.WithCancel(context.Background())
 	room := &Room{
 		Name:          name,
@@ -50,6 +51,7 @@ func NewRoom(name string, maxUsers int, enableHistory bool, historySize int) *Ro
 		enableHistory: enableHistory,
 		historySize:   historySize,
 		history:       make([]Message, 0, historySize),
+		PlainText:     plainText,
 	}
 
 	go room.run()

internal/chat/room_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 func TestNewRoom(t *testing.T) {
-	room := NewRoom("Test Room", 10, false, 0)
+	room := NewRoom("Test Room", 10, false, 0, false)
 	defer room.Stop()
 
 	if room.Name != "Test Room" {
@@ -35,7 +35,7 @@ func TestNewRoom(t *testing.T) {
 }
 
 func TestRoomStop(t *testing.T) {
-	room := NewRoom("Test Room", 10, false, 0)
+	room := NewRoom("Test Room", 10, false, 0, false)
 
 	// Give room time to start
 	time.Sleep(10 * time.Millisecond)
@@ -83,7 +83,7 @@ func TestMessageStruct(t *testing.T) {
 }
 
 func TestRoomChannels(t *testing.T) {
-	room := NewRoom("Test Room", 5, false, 0)
+	room := NewRoom("Test Room", 5, false, 0, false)
 	defer room.Stop()
 
 	// Test that channels are properly initialized

internal/server/config.go

@@ -9,4 +9,5 @@ type Config struct {
 	HostName        string // Tailscale hostname (only used if EnableTailscale is true)
 	EnableHistory   bool   // Whether to enable message history for new users
 	HistorySize     int    // Number of messages to keep in history
+	PlainText       bool   // Whether to disable ANSI formatting (for Windows telnet compatibility)
 }

internal/server/server.go

@@ -31,7 +31,7 @@ func NewServer(cfg Config) (*Server, error) {
 	ctx, cancel := context.WithCancel(context.Background())
 
 	// Create a new chat room
-	room := chat.NewRoom(cfg.RoomName, cfg.MaxUsers, cfg.EnableHistory, cfg.HistorySize)
+	room := chat.NewRoom(cfg.RoomName, cfg.MaxUsers, cfg.EnableHistory, cfg.HistorySize, cfg.PlainText)
 
 	return &Server{
 		config:      cfg,

internal/ui/plaintext.go

@@ -0,0 +1,55 @@
+package ui
+
+import "fmt"
+
+// PlainText formatters for Windows telnet and other clients with limited ANSI support
+
+// FormatSystemMessagePlain formats a system message without ANSI codes
+func FormatSystemMessagePlain(message string) string {
+	return "[System] " + message
+}
+
+// FormatUserMessagePlain formats a user message without ANSI codes
+func FormatUserMessagePlain(username, message, timestamp string) string {
+	return "[" + timestamp + "] " + username + ": " + message
+}
+
+// FormatSelfMessagePlain formats the user's own message without ANSI codes
+func FormatSelfMessagePlain(message, timestamp string) string {
+	return "[" + timestamp + "] You: " + message
+}
+
+// FormatActionMessagePlain formats an action message without ANSI codes
+func FormatActionMessagePlain(username, action string) string {
+	return "* " + username + " " + action
+}
+
+// FormatTitlePlain formats a title without ANSI codes
+func FormatTitlePlain(title string) string {
+	return "=== " + title + " ==="
+}
+
+// FormatHelpPlain formats the help message without ANSI codes
+func FormatHelpPlain() string {
+	return `
+Available Commands:
+  /who - Show all users in the room
+  /me <action> - Perform an action
+  /help - Show this help message
+  /quit - Leave the chat
+`
+}
+
+// FormatUserListPlain formats the user list without ANSI codes
+func FormatUserListPlain(roomName string, users []string, maxUsers int) string {
+	content := fmt.Sprintf("Users in %s (%d/%d):\n", roomName, len(users), maxUsers)
+	for _, user := range users {
+		content += "- " + user + "\n"
+	}
+	return content
+}
+
+// FormatWelcomeMessagePlain formats the welcome message without ANSI codes
+func FormatWelcomeMessagePlain(roomName, nickname string) string {
+	return fmt.Sprintf("Welcome to %s, %s!\n\nType a message and press Enter to send. Use /help to see available commands.", roomName, nickname)
+}