Send and receive messages, manage group chats, and handle files in Lark IM.

• Supports messaging workflows: send/reply to messages, search chat history, batch fetch messages by ID, and manage emoji reactions and message pins
• Group chat operations include create, list, search, update name/description, and manage members (add/remove users and bots)
• File and media handling: upload images, download files with automatic chunked support for large files (8MB chunks), and forward messages or threads
• Bookmark messages or threads at message or feed layer; send in-app, SMS, and phone urgent notifications (bot identity only)
• Works with both user and bot identities; user identity typically has broader contact and chat access, while bot identity requires explicit app visibility and membership settings