deepgram-webhooks-events

# Deepgram Webhooks Events

## Overview
Implement callback URL handling for asynchronous Deepgram transcription workflows.

## Prerequisites
- Publicly accessible HTTPS endpoint
- Deepgram API key with transcription permissions
- Request validation capabilities
- Secure storage for transcription results

## Deepgram Callback Flow

1. Client sends transcription request with callback URL
2. Deepgram processes audio asynchronously
3. Deepgram POSTs results to callback URL
4. Your server processes and stores results

## Instructions

### Step 1: Create Callback Endpoint
Set up an HTTPS endpoint to receive results.

### Step 2: Implement Request Validation
Verify callbacks are from Deepgram.

### Step 3: Process Results
Handle the transcription response.

### Step 4: Store and Notify
Save results and notify clients.

## Examples

### TypeScript Callback Server (Express)
```typescript
// server/callback.ts
import express from 'express';
import crypto from 'crypto';
import { logger } from './logger';
import { storeTranscription, notifyClient } from './services';

const app = express();

// Raw body for signature verification
app.use('/webhooks/deepgram', express.raw({ type: 'application/json' }));
app.use(express.json());

interface DeepgramCallback {
  request_id: string;
  metadata: {
    request_id: string;
    transaction_key: string;
    sha256: string;
    created: string;
    duration: number;
    channels: number;
    models: string[];
  };
  results: {
    channels: Array<{
      alternatives: Array<{
        transcript: string;
        confidence: number;
        words: Array<{
          word: string;
          start: number;
          end: number;
          confidence: number;
        }>;
      }>;
    }>;
  };
}

// Verify callback is from Deepgram
function verifyDeepgramSignature(
  payload: Buffer,
  signature: string | undefined,
  secret: string
): boolean {
  if (!signature) return false;

  const expectedSignature = crypto
    .createHmac('sha256', secret