Cool, great read. I’ll update the PR to only reveal the preimage once the invoice has been confirmed paid 

WeAreAllSatoshi

That's mostly what I was I looking for. Some confirmation that as a rule it shouldn't be done even if there may be exceptions.

I know preimages better now yay!

k00b

bitcoin

What could go wrong revealing a bolt11 preimage to a payer before they've paid?

There's potentially something there with payers constructing their own route through you with that same preimage, reminds me of this: https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-October/002857.html

Browsing it again, there could also be something there with altering amounts and having it route through you, though I'm not sure if it would result in payee loss of funds. It might be uncharted territory since it's kind of a taboo thing to do. 