LINE Channel Integration

The LINE channel enables Weaver to interact through LINE Official Accounts using the Messaging API. It supports webhooks for message reception, reply and push APIs for sending, and features like quote replies and loading animations.

Prerequisites

A LINE account
Access to LINE Developers Console
A publicly accessible HTTPS endpoint for webhooks (or use ngrok for testing)

Creating a LINE Official Account

Create a LINE Developers Account
- Go to https://developers.line.biz/
- Log in with your LINE account
- Accept the terms and conditions
Create a Provider
- Click “Create” on the Providers page
- Enter a provider name (e.g., “My Company”)
Create a Messaging API Channel
- Click “Create Channel”
- Select “Messaging API”
- Fill in the required information:
  - Channel name: Your bot’s name
  - Channel description: Brief description
  - Category: Select appropriate category
  - Subcategory: Select subcategory
- Upload channel icon (optional)
- Click “Create”
Get Channel Access Token
- Go to your channel’s “Messaging API” tab
- Under “Channel access token”, click “Issue”
- Save this token - starts with a long string
Get Channel Secret
- In the “Basic settings” tab
- Find “Channel secret”
- Save this secret
Configure Webhook
- In “Messaging API” tab
- Set “Webhook URL” to your server endpoint:
  https://your-server.com/webhook/line
- Enable “Use webhook”
- Disable “Auto-reply messages” (important!)
- Disable “Greeting messages” (optional)

Configuration

Add the LINE channel to your config.yaml:

channels:
  line:
    enabled: true
    channel_secret: "YOUR_CHANNEL_SECRET"
    channel_access_token: "YOUR_CHANNEL_ACCESS_TOKEN"
    webhook_host: "0.0.0.0"  # Listen on all interfaces
    webhook_port: 8080
    webhook_path: "/webhook/line"
    allow_from:
      - "U1234567890abcdef1234567890abcdef"  # LINE user IDs

Configuration Options

Field	Type	Required	Description
`enabled`	boolean	Yes	Enable LINE channel
`channel_secret`	string	Yes	Channel secret for signature verification
`channel_access_token`	string	Yes	Channel access token for API
`webhook_host`	string	No	Host to bind webhook server (default: `0.0.0.0`)
`webhook_port`	int	No	Port for webhook server (default: `8080`)
`webhook_path`	string	No	Webhook endpoint path (default: `/webhook/line`)
`allow_from`	array	No	Allowed LINE user IDs

User ID Format

LINE uses 33-character user IDs like U1234567890abcdef1234567890abcdef. Finding User IDs:

Have the user message your bot

Check Weaver logs:

Received message sender_id=U1234567890abcdef1234567890abcdef

Webhook Setup

For Production (Public Server)

Ensure HTTPS: LINE requires HTTPS for webhooks

Configure reverse proxy (nginx example):

server {
    listen 443 ssl;
    server_name your-server.com;
    
    ssl_certificate /path/to/cert.pem;
    ssl_certificate_key /path/to/key.pem;
    
    location /webhook/line {
        proxy_pass http://127.0.0.1:8080;
        proxy_set_header X-Line-Signature $http_x_line_signature;
    }
}

Set webhook URL in LINE Console:
```
https://your-server.com/webhook/line
```

For Development (ngrok)

Install ngrok: https://ngrok.com/
Start Weaver (listens on port 8080 by default)
Start ngrok:
```
ngrok http 8080
```

Copy HTTPS URL from ngrok output:

Forwarding: https://abcd1234.ngrok.io -> http://localhost:8080

Set in LINE Console:
```
https://abcd1234.ngrok.io/webhook/line
```
Verify webhook in LINE Console (should show success)

Supported Features

Message Types

Text Messages - Full support with quote replies
Images - Downloaded as image.jpg
Audio - Downloaded as audio.m4a
Video - Downloaded as video.mp4
Files - Metadata only (no content download)
Stickers - Detected as [sticker]

Bot Behavior

1:1 Chats:

Bot responds to all messages
No mention required

Group Chats:

Bot only responds when @mentioned
Mention detection uses display name or user ID
Mention is stripped from message before processing

Reply Features

Reply API: Used first (free, 25-second validity)
Push API: Fallback if reply token expires
Quote Replies: Original message quoted in response
Loading Animation: 60-second loading indicator shown

Message Sending

LINE channel uses a two-tier sending strategy:

Reply API (Free)
- Valid for ~25 seconds after receiving message
- Cached and used automatically if available
- No additional cost
Push API (Paid)
- Used when reply token expired or unavailable
- Requires messaging plan for high volumes
- First 500 messages/month free (varies by region)

Quote Replies

When configured, bot responses quote the original message:

User: Hello bot!
Bot: > Hello bot!
     Hi! How can I help you?

Quote tokens are automatically captured and used in replies.

Mention Detection

In group chats, the bot detects mentions by:

Mention Metadata: LINE’s mention object (primary)
Display Name: Fallback text-based detection using @BotName
User ID Match: Matches bot’s user ID from mention data

Example:

User: @WeaverBot what is the weather?
Bot receives: what is the weather?

The @WeaverBot mention is stripped before processing.

Signature Verification

All webhook requests are verified using HMAC-SHA256:

LINE signs requests with your channel secret
Weaver verifies the X-Line-Signature header
Invalid signatures are rejected (403 Forbidden)

This prevents unauthorized webhook calls.

Error Handling

Common Issues

Invalid Signature

Invalid webhook signature

Verify channel_secret is correct
Ensure webhook request is from LINE servers

Webhook Not Reachable

LINE Console: Webhook verification failed

Check webhook URL is publicly accessible
Verify HTTPS certificate is valid
Ensure firewall allows inbound connections
Test with: curl -X POST https://your-server.com/webhook/line

Missing Bot Info

Failed to fetch bot info (mention detection disabled)

Non-fatal warning
Bot still works but may not detect mentions properly
Verify channel access token is valid

Failed to Send Message

LINE API error (status 401): {...}

Check channel access token
Verify token has not expired
Ensure channel is not deleted/suspended

Security Considerations

Signature Verification: Always enabled, validates all webhooks
Token Security: Keep channel secret and access token secure
HTTPS Required: LINE mandates HTTPS for production webhooks
Allowlist: Use allow_from to restrict bot access
IP Whitelisting: Consider restricting to LINE’s webhook IPs

Metadata Captured

Each LINE message includes:

metadata:
  platform: "line"
  source_type: "user"  # or "group", "room"
  message_id: "1234567890123"

Example Configurations

Production Setup

channels:
  line:
    enabled: true
    channel_secret: "abc123def456ghi789jkl012mno345pq"
    channel_access_token: "abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQR=="
    webhook_host: "0.0.0.0"
    webhook_port: 8080
    webhook_path: "/webhook/line"
    allow_from:
      - "U1234567890abcdef1234567890abcdef"

Development with ngrok

channels:
  line:
    enabled: true
    channel_secret: "abc123def456ghi789jkl012mno345pq"
    channel_access_token: "abcdefg..."
    webhook_host: "127.0.0.1"
    webhook_port: 8080

Then run:

ngrok http 8080

Logging

Monitor LINE activity:

# View LINE-specific logs
grep "line" weaver.log

# Monitor webhook requests
tail -f weaver.log | grep line

Log examples:

Starting LINE channel (Webhook Mode)
Bot info fetched bot_user_id=U1234567890abcdef1234567890abcdef basic_id=@abc123
LINE webhook server listening addr=0.0.0.0:8080 path=/webhook/line
Received message sender_id=U1234567890abcdef1234567890abcdef message_type=text
Message sent via Reply API chat_id=U1234567890abcdef1234567890abcdef quoted=true

Cost Considerations

Reply API: Free (use within 25 seconds of receiving message)
Push API:
- Free tier: First 500 messages/month (Japan)
- Paid plans available for higher volumes
- Check LINE Official Account pricing

Weaver automatically uses Reply API when possible to minimize costs.

Best Practices

Respond Quickly: Use Reply API (free) by responding within 25 seconds
Disable Auto-Reply: Turn off LINE’s auto-reply to avoid duplicate responses
Add Rich Menu: Configure rich menu in LINE Console for user guidance
Monitor Costs: Track Push API usage if on paid plan
Test Webhooks: Use “Verify” button in LINE Console
Handle Groups Carefully: Only respond to mentions to avoid spam

Next Steps

Configure Agents to respond on LINE
Set up Quote Replies for better context
Enable Multimodal for image understanding

LLM Providers

Chat Channels

LINE Channel Integration

Prerequisites

Creating a LINE Official Account

Configuration

Configuration Options

User ID Format

Webhook Setup

For Production (Public Server)

For Development (ngrok)

Supported Features

Message Types

Bot Behavior

Reply Features

Message Sending

Quote Replies

Mention Detection

Signature Verification

Error Handling

Common Issues

Security Considerations

Metadata Captured

Example Configurations

Production Setup

Development with ngrok

Logging

Cost Considerations

Best Practices

Next Steps

Build docs developers (and LLMs) love

LLM Providers

Chat Channels

​Prerequisites

​Creating a LINE Official Account

​Configuration

​Configuration Options

​User ID Format

​Webhook Setup

​For Production (Public Server)

​For Development (ngrok)

​Supported Features

​Message Types

​Bot Behavior

​Reply Features

​Message Sending

​Quote Replies

​Mention Detection

​Signature Verification

​Error Handling

​Common Issues

​Security Considerations

​Metadata Captured

​Example Configurations

​Production Setup

​Development with ngrok

​Logging

​Cost Considerations

​Best Practices

​Next Steps

Build docs developers (and LLMs) love

Prerequisites

Creating a LINE Official Account

Configuration

Configuration Options

User ID Format

Webhook Setup

For Production (Public Server)

For Development (ngrok)

Supported Features

Message Types

Bot Behavior

Reply Features

Message Sending

Quote Replies

Mention Detection

Signature Verification

Error Handling

Common Issues

Security Considerations

Metadata Captured

Example Configurations

Production Setup

Development with ngrok

Logging

Cost Considerations

Best Practices

Next Steps