line-client

name	line-client
description	LINE messaging integration via Chrome extension gateway. Send/read LINE messages, manage contacts, groups, profile, and reactions. Authenticate with QR code login. Provides HMAC-signed API access through the Chrome extension gateway (line-chrome-gw.line-apps.com).

LINE Client Skill

Full LINE messaging client via the Chrome extension gateway JSON API.

Repo & Files

• Repo: /data/workspace/line-client (github.com/2manslkh/line-api)
• Main client: src/chrome_client.py → LineChromeClient
• QR login: src/auth/qr_login.py → QRLogin
• HMAC signer: src/hmac/signer.js (Node.js, auto-starts on port 18944)
• Token storage: ~/.line-client/tokens.json
• Certificate cache: ~/.line-client/sqr_cert
• WASM files: lstm.wasm + lstmSandbox.js (required, in repo root)

Quick Start

import json
from pathlib import Path
from src.chrome_client import LineChromeClient

tokens = json.loads((Path.home() / ".line-client" / "tokens.json").read_text())
client = LineChromeClient(auth_token=tokens["auth_token"])

# Check if chat has E2EE before sending
if client.is_e2ee_chat("C..."):
    print("⚠️  E2EE chat — send_message won't work, see E2EE section below")
else:
    client.send_message("C...", "Hello!")

# Send a message (non-E2EE chats only)
client.send_message("U...", "Hello!")

# Get profile
profile = client.get_profile()

Tokens expire in ~7 days. If expired (APIError(10051)), re-run QR login.

⚠️ E2EE Limitation

Groups with E2EE v2 enabled cannot receive messages via send_message().

• Error: code 82 "types mismatch" when sending to E2EE chats
• Messages in E2EE chats appear with chunks field (encrypted) instead of plaintext text
• Use client.is_e2ee_chat(chat_id) to check before sending
• E2EE encryption module exists in src/e2ee/crypto.py but is NOT wired into send_message yet
• Reading messages from E2EE chats works (returns encrypted chunks)
• Sending requires encrypting with each member's Curve25519 public key — not yet implemented

Workaround: For E2EE groups, use the LINE Official Account API or have the user send manually.

QR Login (Authentication)

QR login requires user interaction: scan QR on phone + enter PIN.

from src.hmac import HmacSigner
from src.auth.qr_login import QRLogin
import qrcode

signer = HmacSigner(mode="server")
login = QRLogin(signer)
result = login.run(
    on_qr=lambda url: send_qr_image_to_user(qrcode.make(url)),
    on_pin=lambda pin: send_pin_to_user_IMMEDIATELY(pin),  # TIME SENSITIVE!
    on_status=lambda msg: print(msg),
)
# result.auth_token, result.mid, result.refresh_token

Critical: The PIN must reach the user within ~60 seconds. Send it the instant on_pin fires.

QR Login State Machine

1. createSession → session ID
2. createQrCode → callback URL (append ?secret={curve25519_pubkey}&e2eeVersion=1)
3. checkQrCodeVerified — poll until scan (uses X-Line-Session-ID, no origin header)
4. verifyCertificate — MUST be called even if it fails (required state transition!)
5. createPinCode → 6-digit PIN (skip if cert verified in step 4)
6. checkPinCodeVerified — poll until user enters PIN
7. qrCodeLoginV2 → JWT token + certificate + refresh token

Server-Side Login Script

python scripts/qr_login_server.py /tmp/qr.png

Emits JSON events on stdout: {"event": "qr", "path": "...", "url": "..."}, {"event": "pin", "pin": "123456"}, {"event": "done", "mid": "U..."}.

Standalone Login (Recommended for Agents)

Best for automation — writes QR/PIN/status to files for fast pickup:

# 1. Start HMAC signer
cd /path/to/line-client && node src/hmac/signer.js serve &

# 2. Run login (background)
python3 scripts/qr_login_standalone.py &

# 3. Watch for QR (send to user via messaging)
# File: /data/workspace/line_qr.png

# 4. Watch for PIN (relay to user IMMEDIATELY — 60s window!)
# File: /data/workspace/line_pin.txt

# 5. Check completion
# File: /data/workspace/line_done.txt → "OK:<mid>" or "FAILED"

Agent orchestration pattern:

# Start login in background
nohup python3 scripts/qr_login_standalone.py > /tmp/line_login.log 2>&1 &

# Poll for QR ready
while [ ! -f /data/workspace/line_status.txt ] || ! grep -q QR_READY /data/workspace/line_status.txt; do
  sleep 0.5
done
# → Send /data/workspace/line_qr.png to user

# Poll for PIN (fast — check every 0.2s)
while [ ! -f /data/workspace/line_pin.txt ]; do
  sleep 0.2
done
PIN=$(cat /data/workspace/line_pin.txt)
# → Send PIN to user IMMEDIATELY

# Poll for completion
while [ ! -f /data/workspace/line_done.txt ]; do
  sleep 1
done
# → Check result

Critical learnings:

• Always clear ~/.line-client/sqr_cert before login to force PIN prompt
• PIN window is ~60 seconds — relay speed is everything
• The standalone script clears cert automatically
• If running from a subagent, the subagent tool-call latency can eat the PIN window
• Best approach: poll PIN file from main thread with minimal sleep interval

Dependencies

# Debian/Ubuntu (no pip needed)
apt-get install -y python3-requests python3-qrcode python3-pil python3-nacl python3-cryptography python3-httpx python3-rsa python3-pycryptodome

# Also need Crypto alias if pycryptodome installs as Cryptodome
ln -sf /usr/lib/python3/dist-packages/Cryptodome /usr/lib/python3/dist-packages/Crypto

All API Methods

Contacts & Friends

Method	Args	Description
get_profile()	—	Get your own profile (displayName, mid, statusMessage, etc.)
get_contact(mid)	mid: str	Get a single contact's profile
get_contacts(mids)	mids: list[str]	Get multiple contacts
get_all_contact_ids()	—	List all friend MIDs
find_contact_by_userid(userid)	userid: str	Search by LINE ID
find_and_add_contact_by_mid(mid)	mid: str	Add friend by MID
find_contacts_by_phone(phones)	phones: list[str]	Search by phone numbers
add_friend_by_mid(mid)	mid: str	Add friend (RelationService)
get_blocked_contact_ids()	—	List blocked MIDs
get_blocked_recommendation_ids()	—	List blocked recommendations
block_contact(mid)	mid: str	Block a contact
unblock_contact(mid)	mid: str	Unblock a contact
block_recommendation(mid)	mid: str	Block a friend suggestion
update_contact_setting(mid, flag, value)	mid, flag: int, value: str	Update contact setting (e.g. mute)
get_favorite_mids()	—	List favorited contact MIDs
get_recommendation_ids()	—	List friend suggestions

Messages

Method	Args	Description
send_message(to, text, ...)	to: str, text: str, reply_to: str (opt)	Send a text message. Supports replies via reply_to=message_id
unsend_message(message_id)	message_id: str	Unsend/delete a sent message
get_recent_messages(chat_id, count=50)	chat_id: str	Get latest messages in a chat
get_previous_messages(chat_id, end_seq, count=50)	chat_id, end_seq: int	Paginated history (older messages)
get_messages_by_ids(message_ids)	message_ids: list[str]	Fetch specific messages
get_message_boxes(count=50)	—	Get chat list with last message (inbox view)
get_message_boxes_by_ids(chat_ids)	chat_ids: list[str]	Get specific chats with last message
get_message_read_range(chat_ids)	chat_ids: list[str]	Get read receipt info
send_chat_checked(chat_id, last_message_id)	chat_id, last_message_id: str	Mark messages as read
send_chat_removed(chat_id, last_message_id)	chat_id, last_message_id: str	Remove chat from inbox
send_postback(to, postback_data)	to, postback_data: str	Send postback (bot interactions)

Chats & Groups

Method	Args	Description
get_chats(chat_ids, with_members=True, with_invitees=True)	chat_ids: list[str]	Get chat/group details
get_all_chat_mids()	—	List all chat MIDs (groups + invites)
create_chat(name, target_mids)	name: str, target_mids: list[str]	Create a new group chat
accept_chat_invitation(chat_id)	chat_id: str	Accept group invite
reject_chat_invitation(chat_id)	chat_id: str	Reject group invite
invite_into_chat(chat_id, mids)	chat_id: str, mids: list[str]	Invite users to group
cancel_chat_invitation(chat_id, mids)	chat_id: str, mids: list[str]	Cancel pending invites
delete_other_from_chat(chat_id, mids)	chat_id: str, mids: list[str]	Kick members from group
leave_chat(chat_id)	chat_id: str	Leave a group chat
update_chat(chat_id, updates)	chat_id: str, updates: dict	Update group name/settings
set_chat_hidden_status(chat_id, hidden)	chat_id: str, hidden: bool	Archive/unarchive a chat
get_rooms(room_ids)	room_ids: list[str]	Get legacy room info
invite_into_room(room_id, mids)	room_id: str, mids: list[str]	Invite to legacy room
leave_room(room_id)	room_id: str	Leave legacy room

Reactions

Method	Args	Description
react(message_id, reaction_type)	message_id: str, type: int	React to a message. Types: 2=like, 3=love, 4=laugh, 5=surprised, 6=sad, 7=angry
cancel_reaction(message_id)	message_id: str	Remove your reaction

Profile & Settings

Method	Args	Description
update_profile_attributes(attr, value, meta={})	attr: int, value: str	Update profile. Attrs: 2=DISPLAY_NAME, 16=STATUS_MESSAGE, 4=PICTURE_STATUS
update_status_message(message)	message: str	Shortcut: update status message
update_display_name(name)	name: str	Shortcut: update display name
get_settings()	—	Get all account settings
get_settings_attributes(attr_bitset)	attr_bitset: int	Get specific settings
update_settings_attributes(attr_bitset, settings)	attr_bitset: int, settings: dict	Update settings

Polling & Events

Method	Args	Description
get_last_op_revision()	—	Get latest operation revision number
fetch_ops(count=50)	—	Fetch pending operations (may long-poll)
poll()	—	Generator yielding operations as they arrive
on_message(handler)	handler: Callable(msg, client)	Start polling thread, calls handler on new messages. Op types: 26=SEND_MESSAGE, 27=RECEIVE_MESSAGE
stop()	—	Stop the polling thread

Other Services

Method	Args	Description
get_server_time()	—	Get LINE server timestamp
get_configurations()	—	Get server configurations
get_rsa_key_info()	—	Get RSA key for auth
issue_channel_token(channel_id)	channel_id: str	Issue channel token (LINE Login/LIFF)
get_buddy_detail(mid)	mid: str	Get official account info
report_abuse(mid, category=0, reason="")	mid: str	Report a user
add_friend_by_mid(mid)	mid: str	Add friend (RelationService)
logout()	—	Logout and invalidate token

MID Format

LINE identifies entities by MID:

• U... or u... → User (toType=0)
• C... or c... → Group chat (toType=2)
• R... or r... → Room (toType=1)

The client auto-detects toType from the MID prefix when sending messages.

HMAC Signing

All API calls require X-Hmac header. The WASM signer handles this automatically:

• Derives key from version "3.7.1" + access token via proprietary KDF (in lstm.wasm)
• Signs path + body → base64 → X-Hmac
• Server mode: ~13ms/sign (Node.js HTTP server on port 18944, auto-started)
• Subprocess mode: ~2s/sign (fallback)

Error Handling

from src.chrome_client import APIError

try:
    client.send_message(mid, "test")
except APIError as e:
    print(e.code, e.api_message)
    # 10051 = session expired / invalid
    # 10052 = HTTP error from backend
    # 10102 = invalid arguments

Architecture

User's Phone (LINE app)
    ↕ (scan QR / enter PIN)
LINE Servers (line-chrome-gw.line-apps.com)
    ↕ (JSON REST + X-Hmac signing)
LineChromeClient (this repo)
    ↕ (WASM HMAC via Node.js signer)
lstm.wasm + lstmSandbox.js

The Chrome Gateway translates JSON ↔ Thrift internally. We never deal with Thrift binary — everything is clean JSON.