> ## Documentation Index
> Fetch the complete documentation index at: https://comis-feature-matrix-channel.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# LINE

> Connect Comis to LINE with step-by-step setup

Connect your Comis agent to LINE private and group chats. Supports file
attachments up to 200 MB and Flex Message formatting. LINE uses webhooks for
receiving messages, so your Comis instance must be accessible from the internet.

<Info>
  You don't need to understand the technical details to use this feature. The configuration examples below are copy-paste ready.
</Info>

## Prerequisites

* Comis installed and running ([Quickstart](/get-started/quickstart))

- A LINE account
- A [LINE Developer Console](https://developers.line.biz/console/) account
- A publicly accessible URL for webhooks (or a tunnel like ngrok for testing)

<Warning>
  LINE uses **webhooks** to deliver messages to your bot. Your Comis gateway must
  be reachable from the internet at the webhook URL you configure. For local
  testing, use a tunnel service like [ngrok](https://ngrok.com). For production,
  deploy behind a reverse proxy with HTTPS.
</Warning>

## Setup

<Steps>
  <Step title="Create a LINE Messaging API channel">
    Go to the [LINE Developer Console](https://developers.line.biz/console/)
    and sign in with your LINE account.

    * Create a new **Provider** (or use an existing one)
    * Under the provider, create a new **Messaging API** channel
    * Give it a name and description -- this is what users will see when they
      add your bot as a friend
    * Note the **Channel ID** on the channel overview page
  </Step>

  <Step title="Get your credentials">
    In the channel settings, go to the **Messaging API** tab:

    * Scroll to the bottom and click **Issue** next to Channel Access Token
      (long-lived). Copy this token -- it is your bot's API key.

    Go to the **Basic settings** tab:

    * Copy the **Channel Secret**. This is used to verify that webhook requests
      actually come from LINE.
  </Step>

  <Step title="Configure the webhook URL">
    In the LINE Developer Console, go to **Messaging API** then
    **Webhook settings**:

    * Set the **Webhook URL** to `https://your-domain:port/webhooks/line`
      (replace `your-domain:port` with your actual gateway address)
    * Enable **Use webhook**
    * Disable **Auto-reply messages** and **Greeting messages** (Comis handles
      responses itself)

    LINE verifies webhook requests with HMAC-SHA256 using your channel secret;
    Comis enforces this signature check on every incoming event.
  </Step>

  <Step title="Configure Comis">
    Add the LINE channel to your Comis configuration file
    (`~/.comis/config.yaml`):

    ```yaml theme={null}
    channels:
      line:
        enabled: true
        botToken: "${LINE_CHANNEL_ACCESS_TOKEN}"
        channelSecret: "${LINE_CHANNEL_SECRET}"
        webhookPath: "/webhooks/line"
    ```

    Set the environment variables in your `~/.comis/.env` file:

    ```bash theme={null}
    LINE_CHANNEL_ACCESS_TOKEN=your-access-token-from-step-2
    LINE_CHANNEL_SECRET=your-channel-secret-from-step-2
    ```

    <Warning>
      Never store API keys, tokens, or passwords directly in `config.yaml`. Use the `.env` file or [Secret Manager](/security/secrets) for credential management.
    </Warning>
  </Step>

  <Step title="Restart and verify">
    Restart the Comis daemon to pick up the new configuration:

    ```bash theme={null}
    comis daemon stop && comis daemon start
    ```

    Check the logs for a successful startup:

    ```bash theme={null}
    comis daemon logs
    ```

    Look for **"LINE adapter started"** or **"channel-line activated"**.

    Back in the LINE Developer Console, click **Verify** next to the webhook
    URL to confirm the connection works. Then add the bot as a friend in the
    LINE app and send it a message.
  </Step>
</Steps>

## Configuration

These options go under `channels.line` in your `config.yaml`:

| Option                             | Type               | Default            | What it does                                                                   |
| ---------------------------------- | ------------------ | ------------------ | ------------------------------------------------------------------------------ |
| `enabled`                          | boolean            | `false`            | Turns on the LINE adapter                                                      |
| `botToken`                         | string / SecretRef | (required)         | Channel Access Token from the LINE Developer Console                           |
| `channelSecret`                    | string / SecretRef | (required)         | Channel Secret for webhook signature verification                              |
| `webhookPath`                      | string             | `"/webhooks/line"` | URL path where LINE sends webhook events                                       |
| `allowFrom`                        | string\[]          | `[]` (all)         | Restrict to specific LINE user IDs. Empty means all users can talk to the bot. |
| `mediaProcessing.transcribeAudio`  | boolean            | `true`             | Transcribe voice messages to text before passing to the agent                  |
| `mediaProcessing.analyzeImages`    | boolean            | `true`             | Describe images sent to the bot using AI vision                                |
| `mediaProcessing.describeVideos`   | boolean            | `true`             | Extract descriptions from video content                                        |
| `mediaProcessing.extractDocuments` | boolean            | `true`             | Extract text from PDFs, DOCX, and other documents                              |
| `mediaProcessing.understandLinks`  | boolean            | `true`             | Fetch and summarize URLs included in messages                                  |

## What your agent can do

Once connected to LINE, your agent can:

* Send and receive messages in private chats and groups
* Send and receive image, video, and audio messages (up to 200 MB)
* Send native voice messages (audio uploaded as LINE audio messages)
* Receive location messages (lat/lon coordinates flow into the agent's metadata)
* Send Flex Messages for rich formatted content via the
  `sendFlex` [platform action](/agent-tools/platform-actions) -- you can pass a
  raw `FlexContainer` JSON or a high-level `FlexTemplate` (header, body, footer,
  hero image) that the adapter renders for you

LINE does **not** support reactions, editing or deleting sent messages, fetching
message history, threads, typing indicators, native polls, traditional buttons
(use Flex postback actions instead), or `@mentions`.

<Note>
  LINE issues a 30-second reply token for every inbound event. Comis ignores it
  and uses `pushMessage` instead so responses still deliver after long agent
  turns; this consumes from your monthly push-message quota.
</Note>

## Platform limits

| Limit           | Value            | What Comis does about it                                                           |
| --------------- | ---------------- | ---------------------------------------------------------------------------------- |
| Message length  | 5,000 characters | Automatically splits long responses into multiple messages at paragraph boundaries |
| Attachment size | 200 MB           | Generous limit that is rarely hit in practice                                      |

## Troubleshooting

<AccordionGroup>
  <Accordion title="Bot can send messages but never receives any">
    **What happened:** The webhook URL is not configured correctly or is not
    reachable from LINE's servers.

    **How to fix it:** In the LINE Developer Console, go to Messaging API and
    check the Webhook settings. Verify the URL points to your Comis gateway
    (including the correct port) and click **Verify** to test the connection.
    Make sure your server is accessible from the internet and not blocked by
    a firewall.
  </Accordion>

  <Accordion title="Invalid signature error in logs">
    **What happened:** The Channel Secret in your Comis config does not match
    the one in the LINE Developer Console.

    **How to fix it:** Go to the LINE Developer Console, open the **Basic
    settings** tab, and copy the Channel Secret. Update the
    `LINE_CHANNEL_SECRET` value in your `~/.comis/.env` file and restart
    the daemon.
  </Accordion>

  <Accordion title="Webhook URL verification fails">
    **What happened:** Comis is not running, the gateway is not accessible, or
    the webhook path does not match.

    **How to fix it:** Make sure Comis is running (`comis daemon status`). Check
    that the `webhookPath` in your config matches the path in the LINE Developer
    Console (default is `/webhooks/line`). If you are running locally, make sure
    your tunnel (e.g., ngrok) is active and pointing to the correct port.
  </Accordion>
</AccordionGroup>

<CardGroup cols={2}>
  <Card title="Delivery Infrastructure" icon="truck-fast" href="/channels/delivery">
    How streaming, typing indicators, and retry logic work under the hood.
  </Card>

  <Card title="Multiple users & teams" icon="users" href="/channels/multi-user">
    Run one install for a whole team - private per person, isolated per agent.
  </Card>

  <Card title="All Channels" icon="message-dots" href="/channels">
    Compare all 11 supported platforms side by side.
  </Card>

  <Card title="Agent Configuration" icon="robot" href="/agents">
    Set up your agent's personality, tools, and behavior.
  </Card>

  <Card title="Secret Management" icon="key" href="/security/secrets">
    Learn how to manage API keys and tokens securely.
  </Card>
</CardGroup>