Summary

Fixes encrypted media (images, audio recordings, files) not being decrypted in Matrix E2EE rooms.

Previously, when users sent images or audio recordings in encrypted Matrix rooms, the bot would fail to decrypt them. Text messages worked fine, but media attachments were broken.

Root Cause

The decryptMedia function from matrix-bot-sdk's CryptoClient was being called with incorrect parameters:

// Before (broken) - passing 2 args
const decrypted = await params.client.crypto.decryptMedia(
  Buffer.from(encryptedBuffer),
  params.file,
);

However, according to the matrix-bot-sdk documentation, decryptMedia takes only a single EncryptedFile parameter and handles the download internally:

// Correct signature
public async decryptMedia(file: EncryptedFile): Promise<Buffer>

Fix

• Call decryptMedia(file) with just the EncryptedFile object
• Remove redundant manual download (the SDK handles it internally)
• Move size check to after decryption

Testing

• Unit tests updated and passing
• Tested on live Matrix E2EE room with encrypted image attachments

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