LINE

TypeScript SDK reference for LINE — client, real-time events, credential management, and types.

Installation

npm install agent-messenger

import { LineClient, LineListener, LineError, LineCredentialManager } from 'agent-messenger/line'

LineClient

The main client for interacting with LINE via the Thrift protocol. Maintains a persistent connection to LINE servers. Call close() when done.

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

const client = await new LineClient().login()

Or pass a custom credential manager:

const credManager = new LineCredentialManager()
const client = await new LineClient(credManager).login()

Auto-login reads credentials from stored login state:

const client = await new LineClient().login()

Explicit login with known credentials:

const client = await new LineClient().login({
  account_id: 'u1234abcd...',
  auth_token: 'eyJ...',
  device: 'ANDROIDSECONDARY',
  display_name: 'Alice',
  created_at: '2025-01-15T09:00:00Z',
  updated_at: '2025-03-28T14:30:00Z',
})

Authenticate by scanning a QR code with your phone. The onQRUrl callback receives the URL to display, and onPincode receives the PIN the user must enter in the LINE mobile app.

const result = await client.loginWithQR({
  device: 'ANDROIDSECONDARY',
  onQRUrl: (url) => console.log(`Scan this QR code: ${url}`),
  onPincode: (pin) => console.log(`Enter this PIN in the LINE mobile app: ${pin}`),
})
// → LineLoginResult { authenticated, account_id, display_name, device }

Authenticate with email and password. Enter the displayed PIN in the LINE mobile app if LINE requires an extra verification step.

const result = await client.loginWithEmail({
  email: 'alice@example.com',
  password: 'hunter2',
  device: 'ANDROIDSECONDARY',
  onPincode: (pin) => console.log(`Enter this PIN in the LINE mobile app: ${pin}`),
})
// → LineLoginResult { authenticated, account_id, display_name, device }

Profile

const profile = await client.getProfile()
// → LineProfile { mid, display_name, status_message?, picture_url? }

Friends

const friends = await client.getFriends()
// → LineFriend[] { mid, display_name, status_message?, picture_url? }

Chat Rooms

// List chat rooms
const chats = await client.getChats()
// → LineChat[] { chat_id, type, display_name, member_count?, picture_url? }

// Limit results
const recent = await client.getChats({ limit: 10 })

Messages

// Get messages from a chat (default: 20)
const messages = await client.getMessages('c1234abcd...')
// → LineMessage[] { message_id, chat_id, author_id, text, content_type, sent_at }

// Get more messages
const more = await client.getMessages('c1234abcd...', { count: 50 })

Sending

const result = await client.sendMessage('c1234abcd...', 'Hello from SDK!')
// → LineSendResult { success, chat_id, message_id, sent_at }

The client tries E2EE (end-to-end encryption) first and falls back to plaintext automatically.

Cleanup

client.close()

Once closed, any subsequent method call throws a LineError with code not_connected. Call login() again to reconnect, or create a new client if you prefer a fresh instance.

LineListener

Real-time event listener that receives push events from LINE. Manages its own session with automatic reconnection.

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

const client = await new LineClient().login()
const listener = new LineListener(client)

listener.on('connected', (info) => {
  console.log(`Connected as ${info.account_id}`)
})

listener.on('message', (event) => {
  console.log(`[${event.chat_id}] ${event.author_id}: ${event.text}`)
})

listener.on('disconnected', () => console.log('Reconnecting...'))
listener.on('error', (err) => console.error(err))

await listener.start()
// listener.stop() to disconnect
// client.close() to release resources

Events

Event	Payload	Description
`message`	`LinePushMessageEvent`	New message received
`line_event`	`LinePushGenericEvent`	Catch-all for all LINE events
`connected`	`{ account_id: string }`	Connected to LINE server
`disconnected`	—	Disconnected (will auto-reconnect)
`error`	`Error`	Connection or protocol error

Reconnection

The listener automatically reconnects with exponential backoff (1s, 2s, 4s ... up to 30s max) when the connection drops.

LineCredentialManager

Manages LINE credentials stored at ~/.config/agent-messenger/line-credentials.json. Files are written with 0o600 permissions.

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

const manager = new LineCredentialManager()

// Load full config from disk (returns defaults if file doesn't exist)
const config = await manager.load()
// → LineConfig { current_account, accounts }

// Save full config to disk
await manager.save(config)

// Get the current account's credentials
const account = await manager.getAccount()
// → LineAccountCredentials | null

// Get a specific account by MID
const specific = await manager.getAccount('u1234abcd...')
// → LineAccountCredentials | null

// Store account credentials
await manager.setAccount(credentials)

// Remove an account
await manager.removeAccount('u1234abcd...')

// Switch the current account
await manager.setCurrentAccount('u1234abcd...')

// List all stored accounts
const accounts = await manager.listAccounts()
// → Array<{ account_id, display_name?, device, is_current, created_at }>

// Remove all stored credentials
await manager.clearAll()

Types

import type {
  LineAccountCredentials,
  LineChat,
  LineConfig,
  LineDevice,
  LineFriend,
  LineListenerEventMap,
  LineLoginResult,
  LineMessage,
  LineProfile,
  LinePushGenericEvent,
  LinePushMessageEvent,
  LineSendResult,
} from 'agent-messenger/line'

Zod Schemas

Runtime-validated schemas are also exported for parsing API responses:

import {
  LineAccountCredentialsSchema,
  LineChatSchema,
  LineConfigSchema,
  LineFriendSchema,
  LineMessageSchema,
  LineProfileSchema,
  LineSendResultSchema,
} from 'agent-messenger/line'

Examples

Chat Summary

List chats and print a summary of each conversation.

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

const client = await new LineClient().login()

try {
  const chats = await client.getChats()
  console.log(`${chats.length} chats:`)
  for (const chat of chats) {
    const label = chat.type === 'group' ? `[Group] ${chat.display_name}` : chat.display_name
    console.log(`  ${label} (${chat.member_count ?? 1} members)`)
  }
} finally {
  client.close()
}

Send Notification

Find a chat by name and send a message.

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

const client = await new LineClient().login()

try {
  const chats = await client.getChats()
  const target = chats.find((c) => c.display_name.includes('Team'))

  if (target) {
    const result = await client.sendMessage(target.chat_id, 'Deploy complete!')
    console.log(`Sent (message_id: ${result.message_id})`)
  }
} finally {
  client.close()
}

Message Monitor

Real-time listener that responds to keywords.

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

const client = await new LineClient().login()
const listener = new LineListener(client)

listener.on('message', async (event) => {
  if (event.text?.toLowerCase().includes('ping')) {
    await client.sendMessage(event.chat_id, 'pong!')
  }
})

listener.on('error', (err) => console.error('Listener error:', err))

await listener.start()

Multi-Account

Switch between accounts and send from different identities.

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

const manager = new LineCredentialManager()
const accounts = await manager.listAccounts()

for (const acct of accounts) {
  await manager.setCurrentAccount(acct.account_id)
  const client = await new LineClient(manager).login()

  try {
    const profile = await client.getProfile()
    console.log(`Logged in as ${profile.display_name} (${profile.mid})`)

    const chats = await client.getChats({ limit: 5 })
    console.log(`  ${chats.length} recent chats`)
  } finally {
    client.close()
  }
}

LINE

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