Cursor Webhooks Skill

When to Use This Skill

• Setting up Cursor Cloud Agent webhook handlers
• Debugging signature verification failures
• Understanding Cursor webhook event types and payloads
• Handling Cloud Agent status change events (ERROR, FINISHED)

Essential Code (USE THIS)

Cursor Signature Verification (JavaScript)

const crypto = require('crypto');

function verifyCursorWebhook(rawBody, signatureHeader, secret) {
  if (!signatureHeader || !secret) return false;

  // Cursor sends: sha256=xxxx
  const [algorithm, signature] = signatureHeader.split('=');
  if (algorithm !== 'sha256') return false;

  const expected = crypto
    .createHmac('sha256', secret)
    .update(rawBody)
    .digest('hex');

  try {
    return crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(expected));
  } catch {
    return false;
  }
}

Express Webhook Handler

const express = require('express');
const app = express();

// CRITICAL: Use express.raw() - Cursor requires raw body for signature verification
app.post('/webhooks/cursor',
  express.raw({ type: 'application/json' }),
  (req, res) => {
    const signature = req.headers['x-webhook-signature'];
    const webhookId = req.headers['x-webhook-id'];
    const event = req.headers['x-webhook-event'];

    // Verify signature
    if (!verifyCursorWebhook(req.body, signature, process.env.CURSOR_WEBHOOK_SECRET)) {
      console.error('Cursor signature verification failed');
      return res.status(401).send('Invalid signature');
    }

    // Parse payload after verification
    const payload = JSON.parse(req.body.toString());

    console.log(`Received ${event} (id: ${webhookId})`);

    // Handle status changes
    if (event === 'statusChange') {
      console.log(`Agent ${payload.id} status: ${payload.status}`);

      if (payload.status === 'FINISHED') {
        console.log(`Summary: ${payload.summary}`);
      } else if (payload.status === 'ERROR') {
        console.error(`Agent error for ${payload.id}`);
      }
    }

    res.json({ received: true });
  }
);

Python Signature Verification (FastAPI)

import hmac
import hashlib
from fastapi import Request, HTTPException

def verify_cursor_webhook(body: bytes, signature_header: str, secret: str) -> bool:
    if not signature_header or not secret:
        return False

    # Cursor sends: sha256=xxxx
    parts = signature_header.split('=')
    if len(parts) != 2 or parts[0] != 'sha256':
        return False

    signature = parts[1]
    expected = hmac.new(
        secret.encode(),
        body,
        hashlib.sha256
    ).hexdigest()

    # Timing-safe comparison
    return hmac.compare_digest(signature, expected)

Common Event Types

Event Payload Structure

{
  "event": "statusChange",
  "timestamp": "2024-01-01T12:00:00.000Z",
  "id": "agent_123456",
  "status": "FINISHED",  // or "ERROR"
  "source": {
    "repository": "https://github.com/user/repo",
    "ref": "main"
  },
  "target": {
    "url": "https://github.com/user/repo/pull/123",
    "branchName": "feature-branch",
    "prUrl": "https://github.com/user/repo/pull/123"
  },
  "summary": "Updated 3 files and fixed linting errors"
}

Environment Variables

# Your Cursor webhook signing secret
CURSOR_WEBHOOK_SECRET=your_webhook_secret_here

Local Development

For local webhook testing, install Hookdeck CLI:

Then start the tunnel:

npx hookdeck-cli listen 3000 cursor --path /webhooks/cursor

No account required. Provides local tunnel + web UI for inspecting requests.

Resources

• overview.md - What Cursor webhooks are, event types
• setup.md - Configure webhooks in Cursor dashboard
• verification.md - Signature verification details and gotchas
• examples/ - Runnable examples per framework