Skema 🚀

Skema compiles the Telegram TL (Type Language) Schema and Telegram RPC Errors Schema into highly usable JavaScript classes with first-class TypeScript support.

This project was originally based on the source code from @tgsnake/core 🐍.

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Layer 227

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⚠️ Requirements & Compatibility in v2.0.0

Important

Starting with the major release v2.0.0, @tgsnake/skema is compiled as a pure ECMAScript Module (ESM). Since Node.js 20 introduced native support for require(ESM) under experimental flags (and subsequent stabilizing in newer versions), we fully transitioned to ESM. So, the minimum Node.js version required for installation and execution is Node.js 22. Ensure your runtime matches or exceeds this version before installing the package.

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✨ Features

• Up-to-date with Telegram's compiled TL Schema.
• Bi-directional Serialization: Clean and efficient API to serialize TL schema classes into binary Buffer structures (.write()) and parse them back (.read()).
• Comprehensive Error Mapping: Built-in classes for standard Telegram RPCError exceptions, custom security mismatches, websocket timeouts, and MTProto packet notifications.
• Out-of-the-box Type Safety: Fully typed modules providing precise autocompletion for Telegram functions, requests, and constructors.
• Multi-Runtime Support: Compatible with modern ESM environments across Node.js, Deno, Bun, and Browser.

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📦 Installation

Install @tgsnake/skema using your preferred package manager:

# Using npm
npm install @tgsnake/skema

# Using yarn
yarn add @tgsnake/skema

# Using pnpm
pnpm add @tgsnake/skema

# Using Bun
bun add @tgsnake/skema

Deno / JSR (Native Deno Import)

# Add the dependency via JSR
deno add jsr:@tgsnake/skema

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🛠️ Usage Guide

Constructing Schema Objects

You can construct Telegram MTProto API requests and constructors using the Raw namespace.

import { Raw } from '@tgsnake/skema';

// Create a SendMessage request parameters object
const sendMessageRequest = new Raw.messages.SendMessage({
  peer: new Raw.InputPeerSelf(),
  message: 'Hello from Skema! 🐍',
  randomId: 1234567890n, // BigInt support for long/int128/int256 types
});

console.log(sendMessageRequest.className); // "messages.SendMessage"

Catching & Handling Errors

Skema includes robust exceptions mapping Telegram errors to digestible error classes.

import { RPCError, Exceptions } from '@tgsnake/skema';

try {
  // E.g., MTProto request execution logic...
} catch (error) {
  if (error instanceof RPCError) {
    console.error(`RPC Error [${error.code}]: ${error.message} (${error.description})`);

    // Check for specific error types
    if (error instanceof Exceptions.BadRequest.PeerIdInvalid) {
      console.error('The provided peer ID is invalid.');
    }
  }
}

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🗃️ Key Exports & Architecture

Below is a breakdown of the primary entry points and structures exported by @tgsnake/skema:

🌐 Namespaces & Schema Engines

• Raw: Contains the entire Telegram TL Schema constructors and requests. All types conform to MTProto Layer 225.
  • Raw.Layer: The active layer number.
  • Raw.HighestSCLayer: The highest secret chat layer supported.

🏗️ Core Classes

• TLObject: The base class for all compiled types. Implements common helper functions (read, write, toJSON, toString).
• Message: Represents an individual MTProto envelope message encapsulating a payload, msg_id, seq_no, and length.
• MsgContainer: A container class handling transport multiplexing of multiple MTProto messages.
• GzipPacked: Helper utility handling compression and decompression of zlib payloads inside MTProto communications.

🧰 Math & Buffer Helpers

• bufferToBigint(buffer: Buffer): Parses a binary buffer into a BigInt.
• bigintToBuffer(number: bigint, padding?: number): Converts a BigInt to its equivalent binary buffer.
• mod(n: number, m: number) / bigIntMod(n: bigint, m: bigint): Standard modulus helpers.

🚨 Exceptional Errors Mappings

• RPCError: Base class representing standard Telegram RPC failures.
• BadMsgNotification: Raised when the MTProto server rejects a message envelope structure (such as incorrect server salt or out-of-sync message ID).
• SecurityError / SecurityCheckMismatch: Raised when cryptographic assertions, signature checks, or padding validations fail during keys derivation.
• CDNFileHashMismatch: Raised if a file chunk downloaded from a Telegram CDN fails checksum verification.
• TimeoutError: Raised when a task exceeds its execution time boundary.

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🤔 Why Skema?

1. Eliminates Boilerplate: Automates the tedious, error-prone manual serialization layout and serialization rules of MTProto schemas.
2. Type Safety: Write codebase with confidence using fully generated TypeScript definition files that precisely mirror the official Telegram Type Language layers.
3. Optimized for Modern Environments: Native ESM and modern Node.js features support, making it lightweight and highly performant.

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📄 License

This project is licensed under the MIT License - Copyright (C) 2026 tgsnake.