LINE

Tip: After npm install -g agent-messenger, agent-line is available directly. For one-off execution without a global install you can use npm exec --package agent-messenger agent-line ..., pnpm dlx --package agent-messenger agent-line ..., yarn dlx agent-messenger agent-line ..., or bunx --package agent-messenger agent-line ....

Key Concepts

Before diving in, a few things about LINE's architecture:

Quick Start

# 1. Login (QR code — opens in browser, scan with LINE app)
agent-line auth login

# 2. List chat rooms
agent-line chat list

# 3. Send a message
agent-line message send <chat-id> "Hello from agent-line!"

# 4. List messages in a chat
agent-line message list <chat-id>

Authentication

LINE offers three authentication methods. QR code login is recommended because it doesn't require your email or password.

Method 1: QR Code Login (Recommended)

Registers the CLI as a secondary device using the ANDROIDSECONDARY slot by default. Your phone and desktop sessions keep running.

# Interactive — opens QR code in browser + prints to terminal
agent-line auth login

On login:

1. The CLI generates a QR code URL and opens it in your browser
2. The QR code also prints in the terminal as a fallback
3. Scan the QR code with the LINE mobile app
4. LINE may display a PIN to confirm on your phone
5. Login completes automatically after confirmation

Method 2: Email/Password Login

Uses email and password credentials. LINE may still require PIN verification on your phone.

# Interactive — prompts for email and password
agent-line auth login --email user@example.com --password mypass

Method 3: Token Login

Directly authenticates with an existing auth token. Useful when you already have a valid token from another source.

agent-line auth login --token <auth-token>

Device Types

LINE allows multiple simultaneous sessions depending on the device type:

# Default: ANDROIDSECONDARY (safe for most users)
agent-line auth login

# Use iPad slot instead
agent-line auth login --device IOSIPAD

# Replace desktop session (kicks LINE desktop)
agent-line auth login --device DESKTOPMAC

Non-Interactive Mode (AI Agents)

When running outside a TTY (no interactive terminal), the CLI returns a next_action JSON response instead of displaying the QR code:

{
  "next_action": "run_interactive",
  "message": "QR code login requires an interactive terminal. Run agent-line auth login in a terminal with TTY support."
}

For non-interactive environments, use --email/--password or --token to authenticate without a QR code.

Auth Management

# Check auth status
agent-line auth status

# List all stored accounts
agent-line auth list

# Switch active account
agent-line auth use <account-id>

# Remove stored credentials
agent-line auth logout
agent-line auth logout <account-id>

Commands

Whoami Command

# Show current authenticated user
agent-line whoami
agent-line whoami --pretty

Output includes:

• mid — your LINE user ID
• display_name — your display name
• status_message — your status message
• picture_url — profile picture URL

Friend Commands

# List all friends
agent-line friend list
agent-line friend list --pretty

Output includes:

• mid — friend's LINE user ID
• display_name — friend's display name
• status_message — friend's status message
• picture_url — friend's profile picture URL

Chat Commands

# List conversations (DMs and groups)
agent-line chat list
agent-line chat list --pretty

# Limit number of chats returned
agent-line chat list -n 20

Output includes:

• chat_id — MID of the chat (u/c/r prefix)
• type — chat type (user, group, room, square)
• display_name — chat or contact name
• member_count — number of members (groups only)

Message Commands

# List messages in a chat room
agent-line message list <chat-id>
agent-line message list <chat-id> -n 50
agent-line message list <chat-id> --pretty

# Send a text message
agent-line message send <chat-id> "Hello world"
agent-line message send <chat-id> "Hello world" --pretty

Each message includes:

• message_id — unique message identifier
• chat_id — which chat the message belongs to
• author_id — sender's MID
• author_name — sender's display name, resolved from contacts (omitted when it can't be resolved)
• text — message text content (null for non-text or undecryptable messages). Letter Sealing (E2EE) messages are decrypted automatically when key material is available
• decryption_error — present only when an E2EE message couldn't be decrypted; { code, message } where code is missing_e2ee_key or decrypt_failed
• content_type — message type (NONE = text, IMAGE, VIDEO, etc.)
• sent_at — ISO 8601 timestamp

Fetching More Messages

Use the -n flag to control how many messages to fetch in a single request:

# Get latest 20 messages (default)
agent-line message list c7a8b9c0d1e2f3a4b5c6d7e8

# Get 50 messages
agent-line message list c7a8b9c0d1e2f3a4b5c6d7e8 -n 50

# Get 200 messages
agent-line message list c7a8b9c0d1e2f3a4b5c6d7e8 -n 200

Global Options

Storage

• Credentials stored in ~/.config/agent-messenger/line-credentials.json (0600 permissions)
• E2EE key storage in ~/.config/agent-messenger/line-storage/

Limitations

• No file upload or download
• No channel/chat room creation or management
• No reactions or emoji
• No message editing or deletion
• No search across chats
• Plain text messages only (no photos, videos, or rich content)
• Sending to chats that require E2EE (Letter Sealing) needs E2EE key material from a prior QR/email login; without it such sends fail with e2ee_required
• Chat IDs are MID strings, not human-readable — use chat list to discover them

Troubleshooting

agent-line: command not found

agent-line is NOT the npm package name. The npm package is agent-messenger.

# If installed globally
agent-line chat list --pretty

# If not installed, use --package
npx -y --package agent-messenger agent-line chat list --pretty

NEVER run npx agent-line without --package agent-messenger. It will fail or install a wrong package.

No credentials found

If auth status shows no account:

1. Run agent-line auth login to authenticate via QR code
2. Or use agent-line auth login --email ... --password ... for email login
3. Verify it worked with agent-line auth status

QR code not displaying

If the QR code doesn't open in your browser:

1. Check the terminal output for the ASCII QR code fallback
2. The QR URL is also printed — you can open it manually
3. Make sure you're running in an interactive terminal (TTY)

E2EE errors

The CLI tries E2EE (Letter Sealing) first and falls back to plaintext when possible, so most messages still send. When E2EE key material is available — restored from a prior QR/email login — the CLI encrypts and decrypts those messages. Chats that require E2EE reject the plaintext fallback, so if no key material is present the send fails with e2ee_required. Re-run agent-line auth login (QR) to provision E2EE keys.

PIN verification timeout

If the PIN expires before you confirm on your phone:

1. Run agent-line auth login again — a new QR code and PIN will be generated
2. Confirm the PIN on your phone within the time limit
3. The CLI automatically completes login after confirmation

SDK Usage

For programmatic access, import LineClient directly:

import { LineClient } from 'agent-messenger/line'

const client = await new LineClient().login()
try {
  const profile = await client.getProfile()
  console.log(profile.display_name)

  const chats = await client.getChats()
  const firstChat = chats[0]
  if (!firstChat) throw new Error('No chats available')

  await client.sendMessage(firstChat.chat_id, 'Hello from SDK!')
} finally {
  client.close()
}

AI Agent Integration

See skills/agent-line/ for:

• Complete skill documentation
• Common patterns for AI agent workflows