Webhook signature verification

Verify webhook payloads from Apian Labs Relay before processing them.

Steps

1. Capture the raw request body exactly as received.
2. Read x-apian-timestamp and x-apian-signature headers.
3. Use the Relay SDK helper to verify the signature.
4. Reject requests that fail validation (401).

If verification fails

• Ensure the webhook secret matches the workspace
• Confirm the raw body is not modified before verification