handling-attachments

XMTP attachments

Handle file attachments using encrypted remote attachments. Files are encrypted locally, uploaded to your storage provider, and sent as a remote attachment message.

When to apply

Reference these guidelines when:

• Sending files or images from an agent
• Receiving and downloading attachments
• Implementing custom upload storage
• Working with encrypted file transfers

Rule categories by priority

Priority	Category	Impact	Prefix
1	Send	CRITICAL	send-
2	Receive	CRITICAL	receive-
3	Upload	HIGH	upload-

Quick reference

Send (CRITICAL)

• send-remote-attachment - Send encrypted file attachments

Receive (CRITICAL)

• receive-attachment - Download and decrypt attachments

Upload (HIGH)

• upload-callback - Implement custom upload storage (Pinata, S3, etc.)

Quick start

import { type AttachmentUploadCallback } from "@xmtp/agent-sdk/util";

// Send an attachment
const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
await ctx.conversation.sendRemoteAttachment(file, uploadCallback);

// Receive an attachment
agent.on("attachment", async (ctx) => {
  const attachment = await downloadRemoteAttachment(ctx.message.content, agent);
  console.log(`Received: ${attachment.filename}`);
});

How to use

Read individual rule files for detailed explanations:

rules/send-remote-attachment.md
rules/receive-attachment.md
rules/upload-callback.md