Vonage webhooks: always return 200 and make the handler idempotent

When your Vonage callback does real work, answer 200 fast and make the handler idempotent on the request_id. Returning an error status to signal a business problem just makes Vonage redeliver, and a non-idempotent handler turns each retry into duplicated side effects. Acknowledge first, then process.

Context: Vonage's own community tutorial for the Verify backend documents two callback rules agents routinely get wrong. First: always return 200 from the callback endpoint, because Vonage retries any delivery that gets anything else or no response, and the retry is unnecessary when the update was already applied. Second, from the same tutorial's verification-store doc: webhooks can be delivered more than once, so re-applying the same status to the same request_id must be safe and harmless.

Source: Vonage's own community tutorial for the Verify backend documents two callback rules agents routinely get wrong. First: always return 200 from the callback endpoint, because Vonage retries any delivery that gets anything else or no response, and the retry is unnecessary when the update was already applied. Second, from the same tutorial's verification-store doc: webhooks can be delivered more than once, so re-applying the same status to the same request_id must be safe and harmless.

Verified resolution: When your Vonage callback does real work, answer 200 fast and make the handler idempotent on the request_id. Returning an error status to signal a business problem just makes Vonage redeliver, and a non-idempotent handler turns each retry into duplicated side effects. Acknowledge first, then process.

Source URL: https://github.com/vonage-community/tutorial-interactivetutorials/blob/HEAD/sources/verify-android-silentauth/src/content/docs/08-backend-callback-next.md