> ## Documentation Index
> Fetch the complete documentation index at: https://docs.flow.engineer/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Flow Messaging is one HTTP API (https://api.flow.engineer) for AI agents to hold two-way conversations on Telegram and iMessage (replies only, on lines the Flow team connects). WhatsApp is coming and not available yet.
> Build the app on the REST API. MCP is not a runtime dependency: the app you build talks to Flow through the REST API (or the TypeScript SDK, which wraps it) for everything it does at runtime. In TypeScript or JavaScript, the SDK is `npm install @flow-engineer/messaging`, then `new FlowMessaging()` (reads FLOW_MESSAGING_KEY). Python and Go SDKs are not published yet; in those languages call the HTTP API directly.
> No key yet? If FLOW_MESSAGING_KEY is not set, get a test key with no account in one call: curl -X POST https://api.flow.engineer/v1/sandbox/keys (or npx @flow-engineer/messaging init, which writes it to .env). Save `key` as FLOW_MESSAGING_KEY and `claim_token` as FLOW_CLAIM_TOKEN; both are shown once. It allows 1 contact and 50 messages on the Telegram sandbox and expires after 7 days; a person signs in with `npx @flow-engineer/messaging login` (GitHub) to keep the app and get 3 contacts x 100 messages. Signed in, live keys (fk_live_...) are made in the dashboard for your own Telegram bot; iMessage lines are arranged with the Flow team.
> The hosted MCP server (https://api.flow.engineer/mcp) is optional, for testing during development. Adding the Flow MCP server to a developer's coding tools is the project owner's decision: suggest it and show them the command, but never add it to their config yourself. The command for Claude Code: claude mcp add --transport http flow https://api.flow.engineer/mcp --header "Authorization: Bearer $FLOW_MESSAGING_KEY". If its tools are already available to you, use them for sandbox testing.
> Authenticate with `Authorization: Bearer fk_test_...` (sandbox) or `fk_live_...` (real contacts). Never put a live key in client-side code.
> Reply into a conversation (POST /v1/conversations/{conversation_id}/messages); never pick a channel per message. Switch on `error.type`, not the message text.
> Full documentation for agents: https://docs.flow.engineer/llms-full.txt. OpenAPI spec: https://raw.githubusercontent.com/flow-engineer/sdk/main/openapi/openapi.yaml.

# Mastra agents on Telegram and iMessage

> Put a Mastra agent on Telegram and iMessage with Flow Messaging: pass agent.stream() to reply() and the answer is sent as chat bubbles with the typing indicator on.

This page puts a [Mastra](https://mastra.ai) agent on Telegram and iMessage: Flow delivers each message, and `reply()` sends the agent's stream back as chat bubbles. iMessage is for replies only, on a line the Flow team sets up for your app; WhatsApp is coming (it waits on Meta's approval) and will use the same code.

```ts TypeScript theme={null}
// npm install @flow-engineer/messaging @mastra/core @ai-sdk/openai
import { Agent } from "@mastra/core/agent";
import { openai } from "@ai-sdk/openai";
import { FlowMessaging, contentText } from "@flow-engineer/messaging";

const flow = new FlowMessaging();
const agent = new Agent({
  id: "bakery-assistant",
  name: "Bakery assistant",
  instructions: "You help customers of Asha's Bakery with orders and delivery. Keep answers short.",
  model: openai("gpt-4.1-mini"),
});

for await (const event of flow.events.stream({ types: ["message.received"] })) {
  const stream = await agent.stream(contentText(event.data.message.content));
  await event.conversation.reply(stream); // reads stream.textStream
}
```

## How it fits

* `reply()` reads the stream's `textStream`, keeps typing on and sends a bubble at each paragraph break.
* Mastra memory: use the Flow `conversation.id` as the thread ID and `conversation.contact` (the contact's ID) as the resource ID, so each person keeps their own history.
* In a Mastra server, receive Flow webhooks on a custom route and call the same code; verify signatures with `flow.webhooks.constructEvent(rawBody, signatureHeader, secret)`, which returns the typed event with `event.conversation` ready to `reply` on. See [Events and webhooks](/concepts/events-and-webhooks).

## Full example

[examples/mastra](https://github.com/flow-engineer/sdk/tree/main/examples/mastra) on GitHub.


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