A tweet from 2023 explains how Ark can work non-interactively without softfork: https://x.com/SomsenRuben/status/1681442410348576772.

In this write-up, he explains Ark in simpler terms: https://gist.github.com/RubenSomsen/a394beb1dea9e47e981216768e007454?permalink_comment_id=4633382#file-_simplest_ark-md. Once you read this, you can scroll down and read the second post, "Reducing Ark Interactivity Without Soft Fork".


As far as I understand, it goes like this:

• Alice wants to send money to Bob, but Bob is offline.
• Alice requests from the Server to sign a new REDEEM_TX_AB with script: B+S or A+S or A in 1 month, which is the same as her previous REDEEM_TX_A but with different timelock and the addition of B+S.
• Alice forfeits REDEEM_TX_A (which means the Server can claim her funds if she ever publishes REDEEM_TX_A)
• Alice can perform the swap for Bob (since he is offline), and she can get the proof of payment from the Server.
• The Server is incentivized to be cooperative along the way.

Please correct me if I've misunderstood. I'm still trying to grasp the concept.