[curryst]

If you want to be 100% sure that you get all the webhooks, the sender could implement an incrementing "webhook ID". If the receiver knows the last webhook ID was 53 and the sender sends one for 55, you can tell one has been dropped. There are some other concerns around that like if 54 has been sent but they arrived out of order, or if they arrive almost simultaneously. Nothing that isn't solvable afaict though.

Of course, then you need a way for the receiver to retrigger or view the webhook if one gets missed, which starts to look like you have to have a polling endpoint anyways, though.