Tx processing by credit

[JoowonYun]

Summary

If the account that cannot pay the fee can pay the fee after processing the tx, we accept the tx.

Problem Definition

Many dApps are running under the influence of many app chains and cosmwasm in the cosmos ecosystem. When a user is first onboarded to a dApp, the user has the token, but there is no coin to pay the chain fee, so accessibility is often poor. To solve this, I thought about allowing tx by credit.

The scenario I'm thinking of is as follows.

• There is an AMM pair of A coin and B token.
• Users only have B tokens.
• When enough B tokens are swapped to pay the fee, the network deducts the fee from the resulting A coin.

The code for the PoC is here. xpladev@1d3640a

I look forward to many good comments.

[alexanderbez]

So a few thoughts:

1. This is already sort of covered by x/feegrant, any account can pay fees for you on your behalf, with limits and periods.
2. Anything more custom probably doesn't belong in the SDK, i.e. AMM specific logic
3. More generally, "If the account that cannot pay the fee can pay the fee after processing the tx, we accept the tx.", is sort of tricky in the current SDK design.

[JoowonYun]

Thanks for the quick comment.
My thoughts on your comments are below.

1. x/feegrant is a coin that is distributed free of charge, and it is a part that reflects the value of the actual account, so I think it is a slightly different part.
2. AMM is just an example and if you limit it to cosmos-sdk, we can solve other inconvenient situations. If there is a user who has delegated without leaving a fee to spend, they have to get a coin from somewhere and claim it. But in this scenario, they can make a claim.
3. I totally agree that it's tricky to apply to the design of the current SDK. Still, I think it's worth thinking about.