LINE

Install

Quick start

import { Chat } from "chat";
import { createLineAdapter } from "chat-adapter-line";
import { createMemoryState } from "@chat-adapter/state-memory";

const bot = new Chat({
  userName: "mybot",
  adapters: {
    line: createLineAdapter(),
  },
  state: createMemoryState(),
});

bot.onDirectMessage(async (thread, message) => {
  await thread.post(`You said: ${message.text}`);
});

The memory state adapter keeps subscriptions and locks in process memory, which suits local development. Use Redis or PostgreSQL in production.

When called with no arguments, createLineAdapter() reads LINE_CHANNEL_ACCESS_TOKEN and LINE_CHANNEL_SECRET from the environment.

Platform setup

1. Create a provider and channel in the LINE Developers Console.
2. Enable the Messaging API for the channel.
3. Copy the channel access token and channel secret.
4. Set the webhook URL to a public HTTPS endpoint, such as https://your-domain.com/api/webhooks/line.
5. Subscribe to message and postback events.

Configuration

Environment variables

Webhooks

import { after } from "next/server";
import { bot } from "@/lib/bot";

export async function POST(request: Request): Promise<Response> {
  return bot.webhooks.line(request, {
    waitUntil: (task) => after(() => task),
  });
}

LINE sends each webhook with an x-line-signature header. The adapter computes an HMAC-SHA256 digest with the channel secret and compares it with the header before parsing the body.

Messages and cards

Text and Markdown output are converted to plain text. Chat SDK cards become LINE Flex Messages: the card title and text become the bubble body, and buttons become postback actions in the footer. Button clicks dispatch to Chat SDK action handlers.

Attachments

The adapter receives image, video, audio, and file messages as attachments. It doesn't upload outbound files. Posting a message with files logs a warning and sends any text or card content.

Streaming

Streaming is buffered. The adapter sends a text message after it collects more than 500 characters, then sends the remaining text after the stream ends. It sends at most five messages per stream.

Thread IDs

line:<channelId>:<sourceType>:<sourceId>

sourceType is user, group, or room. sourceId is the LINE user, group, or room ID.

Feature support