telegram-agent-kit

Wire LLM agents to Telegram: render Markdown, stream replies into a live native draft, and drive a snapshot/rollback turn-loop — over thin injected interfaces, with zero runtime dependencies in the core.

ESM-only. Runs on Node 18+, Bun, Deno, and the browser (the formatting core).

Why this exists

Connecting an LLM agent to a Telegram bot looks simple until you hit the edges:

• LLMs emit arbitrary Markdown — Telegram speaks a small, strict HTML subset. A single unclosed tag makes the Bot API reject the whole message.
• Token streaming into a live draft means you render partial Markdown many times a second, where marks and fences are routinely mid-token.
• A failed turn must roll back cleanly so the conversation thread isn't corrupted.

telegram-agent-kit solves these once. Notably, it's the only JS package that renders Markdown to Telegram-HTML with totality (never throws on arbitrary LLM output) and a streaming/partial mode (auto-closes unclosed marks and fences, so a live draft never flashes broken markup).

It is runtime-agnostic: you supply all I/O through small injected interfaces, and the kit owns the orchestration. No HTTP client, no framework, no globals.

Features

• Markdown → Telegram-HTML that never throws, with a partial mode for live drafts.
• Live draft streaming — a throttle / keepalive / typing-heartbeat / drain state machine that animates one native Telegram draft from a growing string.
• Turn-loop orchestration — snapshot → stream → animate → finalize → reply, with rollback on error and a guarantee it never throws out.
• Resilient send path — automatic chunking, surrogate-safe splitting, and deterministic 400 fallbacks (rich → HTML → plain text; photo → text).
• Optional deepagents adapter on a separate subpath, so the core never pulls in langchain.

Installation

npm install telegram-agent-kit

The optional telegram-agent-kit/deepagents subpath needs its peers — install them only if you use it:

npm install @langchain/core deepagents

Quick start

Implement a thin BotClient over the Bot API, then drive one turn per incoming message. The example uses the deepagents adapter, but any AgentStream works.

import { runTelegramTurn, TelegramApiError, type BotClient } from 'telegram-agent-kit';
import { toAgentStream } from 'telegram-agent-kit/deepagents';

// 1. Raw Bot API primitives — one HTTP call each. Throw TelegramApiError on a
//    Bot API error so the kit's deterministic-400 fallbacks can fire.
const client: BotClient = {
  sendMessage:        (p, signal) => call('sendMessage',        { chat_id: p.chatId, text: p.text, parse_mode: p.parseMode }, signal),
  sendRichMessage:    (p, signal) => call('sendMessage',        { chat_id: p.chatId, text: p.markdown },                       signal),
  sendPhoto:          (p, signal) => call('sendPhoto',          { chat_id: p.chatId, photo: p.url, caption: p.caption, parse_mode: p.parseMode }, signal),
  sendChatAction:     (p, signal) => call('sendChatAction',     { chat_id: p.chatId, action: p.action ?? 'typing' },          signal),
  sendMessageDraft:   (p, signal) => call('sendMessageDraft',   { chat_id: p.chatId, draft_id: p.draftId, text: p.text },     signal),
  sendRichMessageDraft:(p, signal) => call('sendRichMessageDraft',{ chat_id: p.chatId, draft_id: p.draftId, text: p.markdown },signal),
};

// 2. Drive one turn.
await runTelegramTurn({
  chatKey: { chatId, agentId: 'main' },
  userText,
  draftId: updateId,        // non-zero, unique per turn — reused for every draft write
  rich: true,
  client,
  agentStream: toAgentStream(agent),   // your deepagents agent
  checkpointer: {
    snapshot: (threadId)     => saver.snapshotId(threadId),
    rollback: (threadId, id) => saver.rollbackThread(threadId, id),
  },
  threadStore: {
    resolve: (key)      => threads.resolve(key.chatId, key.agentId),
    touch:   (key, now) => threads.touch(key.chatId, key.agentId, now),
  },
  log: console,
});

// Thin transport helper.
async function call(method: string, body: unknown, signal?: AbortSignal) {
  const res = await fetch(`https://api.telegram.org/bot${TOKEN}/${method}`, {
    method: 'POST',
    headers: { 'content-type': 'application/json' },
    body: JSON.stringify(body),
    signal,
  });
  if (!res.ok) {
    const j = await res.json().catch(() => ({}));
    throw new TelegramApiError(res.status, j.description);
  }
}

Note: sendRichMessage / sendRichMessageDraft map to your bot's rich-text transport. If your bot has no rich endpoint, point them at plain sendMessage and set rich: false — the kit then renders via HTML only.

How it works

The kit is three layers plus one optional adapter. The dependency direction is strictly Bridge → Draft → Formatting; lower layers never import higher ones, and the core never imports the adapter.

┌─────────────────────────────────────────────────────────────┐
│  /deepagents  (optional subpath)                            │
│  toAgentStream · streamAgent  →  AgentStream                │
└─────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────┐
│  Bridge       runTelegramTurn · sendReply · sendText        │
│               + the four interfaces you implement           │
└─────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────┐
│  Draft        createDraftStreamer (throttle/keepalive/drain)│
└─────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────┐
│  Format       mdToTelegramHtml · chunk* · rich helpers      │
│               pure, zero deps, browser-safe                 │
└─────────────────────────────────────────────────────────────┘

Transport vs. orchestration. You provide raw Bot API primitives — one HTTP call each, no chunking, rendering, or fallback. The kit owns all orchestration over them: HTML rendering, chunking, the rich → classic and photo → text 400 fallbacks, and the trailing-cover photo flow.

The four interfaces

You implement these; the kit drives them.

| Interface | Shape | Role | | -------------- | --------------------------------------------------------------------- | ---- | | BotClient | sendMessage, sendRichMessage, sendPhoto, sendChatAction, sendMessageDraft, sendRichMessageDraft | Raw transport. Each throws TelegramApiError on a Bot API error. | | AgentStream | (input, { threadId, signal, configurable }) => AsyncIterable<RenderEvent> | Your agent. threadId must reach it so the checkpointer writes to the snapshotted thread. configurable is an optional pass-through bag forwarded verbatim from runTelegramTurn's configurable option. | | Checkpointer | { snapshot(threadId), rollback(threadId, id) } | Per-thread snapshot/rollback for clean recovery on a failed turn. | | ThreadStore | { resolve(chatKey, now), touch(chatKey, now) } | Maps { chatId, agentId } to a thread id (so two bots over one chat id don't collide). |

A RenderEvent is one of token, tool_start, tool_end, or error. The kit appends token text to the live draft and treats an error event as a rollback.

API reference

Core entry — telegram-agent-kit

Formatting (pure, zero deps)

• mdToTelegramHtml(md, opts?) — Markdown → Telegram-HTML. Never throws. opts.partial auto-closes unclosed marks/fences for live drafts.
• chunkText(text) / safeSlice(text, max) / chunkRich(md) — surrogate-safe splitting (classic limit 4096, rich limit 32768).
• repairRichTables(md) · neutralizeRichMedia(md) · extractTrailingCover(reply) — rich helpers.

Draft engine

• createDraftStreamer(deps) → { start(), push(fullText), finalize(), abort() }.
• DEFAULT_DRAFT_CONSTANTS / DraftConstants — overridable tunables (throttle, keepalive, typing heartbeat, preview cap, drain, …).

Bridge

• runTelegramTurn(opts) — orchestrate one turn. Never throws out; every failure is caught and logged. Accepts an optional configurable bag forwarded to your AgentStream as context.configurable, for passing per-turn data (e.g. pendingImages) to the agent without widening the core input type.
• sendReply(client, chatId, reply, opts, signal?) / sendText(...) — the send path on its own.
• Types: BotClient, AgentStream, Checkpointer, ThreadStore, RenderEvent, ChatKey, Logger.

Errors

• TelegramApiError — throw this from BotClient primitives (carries error_code).
• isBadRequest(err) — true only for a deterministic 400 (rejected, safe to retry on a degraded path).

Optional entry — telegram-agent-kit/deepagents

• toAgentStream(agent) → AgentStream — adapts a deepagents/langgraph agent to the kit's contract. The context.configurable bag is merged into the LangGraph RunnableConfig, but the reserved keys thread_id, thread_ts, checkpoint_id, checkpoint_ns, checkpoint_map, and run_id — plus any __pregel_* LangGraph internal-execution key — are stripped so the kit retains full control over checkpoint routing and execution.
• streamAgent(agent, input, config, signal?) — lower-level event stream if you need direct control.

@langchain/core and deepagents are type-only, optional peers. The built /deepagents bundle contains no runtime import of either, so the core stays dependency-free.

Design guarantees

These are intentional and enforced by tests:

• mdToTelegramHtml is total — it never throws on any LLM output. The send path also wraps it and falls back to plain text as defence-in-depth.
• Deterministic 400 fallbacks keyed off isBadRequest: rich → classic HTML → plain text, and photo → text. Any non-400 error always propagates.
• runTelegramTurn never throws out — snapshot happens only after a turn isn't skipped, rollback fires only on a real failure, and draft teardown is idempotent.
• Surrogate-safe splitting — chunking never severs a UTF-16 surrogate pair.

Development

npm run build       # tsup → dist/ (ESM + .d.ts) for both entry points
npm run typecheck   # tsc --noEmit
npm test            # vitest run
npm run lint        # biome check .
npm run format      # biome format --write .

Run a single test:

npx vitest run test/format/md-to-html.test.ts     # one file
npx vitest run -t "renders nested bold"           # by name

Build before testing if you touch /deepagents: one test greps the built bundle to prove it carries no runtime import of the optional peers (it skips when dist/ is absent). CI runs build before test for this reason.

Contributing

Issues and pull requests are welcome. Before opening a PR, please run npm run lint, npm run typecheck, and npm test — and npm run build if your change touches the /deepagents entry. See CHANGELOG.md for the project history.

License

MIT © Ivan Kalinichenko