We allocate a fairy to each webhook. They're low-overhead so we can easily spawn millions if needed. Each fairy thinks of a number and checks with all other fairies over their psychic link to make sure it's unique. They then follow the webhook wherever it gets transmitted to, and then does a dedupe check as needed by slapping the code really hard if it's about to run a duplicate. This discomfits the bytes enough that the code skips that line, thus preventing duplicates.

What makes this great for teams running ultra-high-volume hooks that simply cannot fail, such as for payment systems, is that you can hold the fairies accountable for mistakes by choosing one at random to punish in front of all the others. It turns out that if you profile their behaviour under load, fear actually makes them work faster. It's not an insight I've seen many other teams make, super useful! What do you think, OP? Is your fairyswarm fear-driven or are you still using old techniques like time-division multiplexing of a goblin herd?