I can't help but think this won't work for the majority of uses. Say you're an Onlyfans creator, and say you want to have users pay for content. It makes much more sense to have each user pay 0.0002BTC to a unique address, instead of having them pay a certain amount collectively.
The primary use case we have in mind is for a content creator one-on-one with a customer selling their completed work. It allows the simple flow from payment to the unlocking of content. That collective unlocking is possible is simply an interesting side-effect.
Address reuse isn't dangerous, it's bad for privacy. But you're still doing it: when I set a larger amount than the address has received, your site tells me to pay the difference between that amount and the amount already sent to the address.
You are right again. Partial payments are not really intended though.
You could ask the user for their master public key, which allows you to generate different addresses for each link request. To avoid a large "gap" in between addresses, you could for instance start over after the first 100 unused addresses.
Thanks for the suggestion. We will consider further how selling the same content repeatedly could work, but we think some kind of account creation would be required for that use case, which is something we're trying to avoid for simplicity sake.
