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"])

# Send a message
client.send_message("U...", "Hello!")

# Get profile
profile = client.get_profile()

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

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.

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

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..."}.

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.