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docs(x/evmutil): Remove akava and evmbankkeeper from spec (#1968)

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32
x/evmutil/spec/01_concepts.md
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@ -4,34 +4,6 @@ order: 1
# Concepts
## EVM Gas Denom
In order to use the EVM and be compatible with existing clients, the gas denom used by the EVM must be in 18 decimals. Since `ukava` has 6 decimals of precision, it cannot be used as the EVM gas denom directly.
To use the Kava token on the EVM, the evmutil module provides an `EvmBankKeeper` that is responsible for the conversion of `ukava` and `akava`. A user's excess `akava` balance is stored in the `x/evmutil` store, while its `ukava` balance remains in the cosmos-sdk `x/bank` module.
## `EvmBankKeeper` Overview
The `EvmBankKeeper` provides access to an account's total `akava` balance and the ability to transfer, mint, and burn `akava`. If anything other than the `akava` denom is requested, the `EvmBankKeeper` will panic.
This keeper implements the `x/evm` module's `BankKeeper` interface to enable the usage of `akava` denom on the EVM.
### `x/evm` Parameter Requirements
Since the EVM denom `akava` is required to use the `EvmBankKeeper`, it is necessary to set the `EVMDenom` param of the `x/evm` module to `akava`.
### Balance Calculation of `akava`
The `akava` balance of an account is derived from an account's **spendable** `ukava` balance times 10^12 (to derive its `akava` equivalent), plus the account's excess `akava` balance that can be accessed via the module `Keeper`.
### `akava` <> `ukava` Conversion
When an account does not have sufficient `akava` to cover a transfer or burn, the `EvmBankKeeper` will try to swap 1 `ukava` to its equivalent `akava` amount. It does this by transferring 1 `ukava` from the sender to the `x/evmutil` module account, then adding the equivalent `akava` amount to the sender's balance in the module state.
In reverse, if an account has enough `akava` balance for one or more `ukava`, the excess `akava` balance will be converted to `ukava`. This is done by removing the excess `akava` balance in the module store, then transferring the equivalent `ukava` coins from the `x/evmutil` module account to the target account.
The swap logic ensures that all `akava` is backed by the equivalent `ukava` balance stored in the module account.
## ERC20 token <> sdk.Coin Conversion
`x/evmutil` facilitates moving assets between Kava's EVM and Cosmos co-chains. This must be handled differently depending on which co-chain to which the asset it native. The messages controlling these flows involve two accounts:
@ -65,7 +37,3 @@ EVM-native asset conversion is done through the use of the `MsgConvertERC20ToCoi
Only ERC20 contract address that are in the `EnabledConversionPairs` param (see **[Params](05_params.md)**) can be converted via these messages.
`EnabledConversionPairs` can be altered through governance.
## Module Keeper
The module Keeper provides access to an account's excess `akava` balance and the ability to update the balance.

16
x/evmutil/spec/02_state.md
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@ -51,24 +51,12 @@ message AllowedCosmosCoinERC20Token {
```protobuf
message GenesisState {
repeated Account accounts = 1 [(gogoproto.nullable) = false];
// previously stored accounts containing fractional balances.
reserved 1;
Params params = 2 [(gogoproto.nullable) = false];
}
```
## Account
An `Account` is a struct representing the excess `akava` balance of an address.
Since an address's total `akava` balance is derived from its `ukava` balance and the excess `akava` balance stored by the `Account` struct, the `akava` balance here should never exceed 1 `ukava` (10^12 `akava`).
```protobuf
message Account {
bytes address = 1;
string balance = 2;
}
```
## Deployed Cosmos Coin Contract Addresses
Addresses for the ERC20 contracts representing cosmos-sdk `Coin`s are kept in the module store. They are stored as bytes by the cosmos-sdk denom they represent.

7
x/evmutil/spec/README.md
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@ -21,13 +21,6 @@ parent:
The evmutil module provides additional functionalities on top of the evm module.
### EVM `akava` Usage
evmutil stores additional state data for evm accounts and exposes an `EvmBankKeeper` that should be used by the `x/evm` keeper for bank operations.
The purpose of the `EvmBankKeeper` is to allow the usage of the `akava` balance on the EVM via an account's existing `ukava` balance. This is needed because the EVM gas token use 18 decimals, and since `ukava` has 6 decimals, it cannot be used as the EVM gas denom directly.
For additional details on how balance conversions work, see **[Concepts](01_concepts.md)**.
### ERC20 Token <> sdk.Coin Conversion
evmutil exposes messages to allow for the conversion of Kava ERC20 tokens and sdk.Coins via a whitelist.