You’re on the right track with your understanding of the webhook. When users interact with your bot, Telegram does send POST requests to your webhook URL. Your webhook should process these incoming updates and parse the accompanying JSON payload.
Regarding the authentication flow, when your webhook receives the /start command along with the token, you need to extract that token from the message text and check it against your database. If it matches, you can then associate the user’s Telegram chat ID with their account in your system, and remove the token to prevent reuse.
Consider implementing token expiration (typically set for 5-10 minutes) to enhance security. Additionally, ensure that your webhook sends a response with an HTTP 200 status code to confirm receipt; otherwise, Telegram will continue to resend the same update. Based on my experience, sending a confirmation message back to the user upon successful verification can be very helpful, as it provides immediate feedback that the linking process was successful.