I am not sure why I find it hard to describe the need for something like this. I think a lot of users of SimplicityHL think about writing the .simf file and that’s the end of it. Creating the contract is probably the most mentally challenging part, but there is a fair amount of (tedious) work in creating the wallet that interacts with the contract.
Currently, simplicity contracts basically require their custom wallets to be developed. My goal for txmanifest is to create a standardized, descriptive format that wallets can implement for building transactions interacting with simplicity inputs and are able to generate addresses.
The file itself can grow quite complex, so I’ve created a book to guide users through learning it, and that’s my recommended learning path: Introduction - The tx-manifest Cookbook
At the same time, I’ve created an ELIP and I’ll be editing it as I test out more and more use cases with it.
I’ll keep adding to this thread to keep everyone up to date. I’d love some feedback.