Secure and Idempotent Telegram Webhook Handler in Pure PHP

When building a Telegram bot for production—such as a lead capture system, an e-commerce storefront, or a booking assistant—handling incoming updates reliably is critical. If you simply expose a public PHP script that processes payloads on the fly, your application is vulnerable to two severe issues. First, because your webhook URL is public, anyone who discovers it can send forged payloads to simulate actions, bypass authorization, or inject malicious data. Second, Telegram expects your server to acknowledge every webhook request with an HTTP 200 OK status within a strict timeout window (typi