feat: add one-time grain restoration vote (#1339)

# Related Github tickets

VolumeFi#2570 (comment) 

# Background

This change introduces a new vote which can be used to recreate the 1.3b
GRAIN tokens which are lost forever on BASE. They will be funded to the
Paloma Foundation wallets.

# Testing completed

- [x] test coverage exists or has been added/updated
- [x] tested in a private testnet

# Breaking changes

- [x] I have checked my code for breaking changes
- [x] If there are breaking changes, there is a supporting migration.

proto/palomachain/paloma/skyway/msgs.proto

@@ -72,6 +72,7 @@ service Msg {
       "/palomachain/paloma/skyway/erc20-to-token-denom";
   }
 
+  rpc ReplenishLostGrainsProposal(MsgReplenishLostGrainsProposal) returns (google.protobuf.Empty);
   rpc OverrideNonceProposal(MsgNonceOverrideProposal) returns (google.protobuf.Empty);
 }
 
@@ -85,6 +86,14 @@ message MsgNonceOverrideProposal {
   uint64 nonce = 3;
 }
 
+// TODO: Remove this message after usage
+message MsgReplenishLostGrainsProposal {
+  option deprecated = true;
+  option (cosmos.msg.v1.signer) = "metadata";
+  palomachain.paloma.valset.MsgMetadata metadata = 1
+      [ (gogoproto.nullable) = false ];
+}
+
 // MsgSendToRemote
 // This is the message that a user calls when they want to bridge an asset
 // it will later be removed when it is included in a batch and successfully

x/skyway/keeper/msg_server.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	sdkerrors "cosmossdk.io/errors"
+	"cosmossdk.io/math"
 	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	errorsmod "github.com/cosmos/cosmos-sdk/types/errors"
@@ -425,6 +426,46 @@ func (k *msgServer) OverrideNonceProposal(ctx context.Context, req *types.MsgNon
 	return &emptypb.Empty{}, k.overrideNonce(ctx, req.ChainReferenceId, req.Nonce)
 }
 
+func (k *msgServer) ReplenishLostGrainsProposal(ctx context.Context, req *types.MsgReplenishLostGrainsProposal) (*emptypb.Empty, error) {
+	if err := req.ValidateBasic(); err != nil {
+		return nil, sdkerrors.Wrapf(govtypes.ErrInvalidSigner, "message validation failed: %v", err)
+	}
+	if req.Metadata.Creator != k.authority {
+		return nil, sdkerrors.Wrapf(govtypes.ErrInvalidSigner, "invalid authority; expected %s, got %s", k.authority, req.Metadata.Creator)
+	}
+
+	ctx, commit := sdk.UnwrapSDKContext(ctx).CacheContext()
+	store := k.GetStore(ctx, types.StoreModulePrefix)
+	if store.Get(types.ReplenishedGrainRecordsKey) != nil {
+		return nil, fmt.Errorf("operation may only be run once.")
+	}
+
+	for _, addr := range []string{
+		"paloma17t5pd5l0d8a3p54r0p92src8tx2tvs7l2afmd9",
+		"paloma1vlrsw0hf6ddkje99jtnzh4raaa4dqpwqapeaz6",
+	} {
+
+		amount := sdk.NewCoin("ugrain", math.NewInt(665625000000000))
+		err := k.bankKeeper.MintCoins(ctx, types.ModuleName, sdk.NewCoins(amount))
+		if err != nil {
+			return nil, fmt.Errorf("MintCoins: %w", err)
+		}
+
+		receiver := sdk.MustAccAddressFromBech32(addr)
+		err = k.bankKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName,
+			receiver,
+			sdk.NewCoins(amount))
+		if err != nil {
+			return nil, fmt.Errorf("SendCoinsFromModuleToAccount: %w", err)
+		}
+	}
+
+	store.Set(types.ReplenishedGrainRecordsKey, []byte("1"))
+
+	commit()
+	return &emptypb.Empty{}, nil
+}
+
 func (k *msgServer) SetERC20ToTokenDenom(ctx context.Context, msg *types.MsgSetERC20ToTokenDenom) (*emptypb.Empty, error) {
 	sdkCtx := sdk.UnwrapSDKContext(ctx)
 	sender, err := sdk.AccAddressFromBech32(msg.Metadata.Creator)

x/skyway/types/codec.go

@@ -31,6 +31,7 @@ func RegisterInterfaces(registry types.InterfaceRegistry) {
 		&MsgSubmitBadSignatureEvidence{},
 		&MsgLightNodeSaleClaim{},
 		&MsgNonceOverrideProposal{},
+		&MsgReplenishLostGrainsProposal{},
 		&MsgSetERC20ToTokenDenom{},
 	)
 
@@ -86,5 +87,6 @@ func RegisterCodec(cdc *codec.LegacyAmino) {
 	cdc.RegisterConcrete(&MsgLightNodeSaleClaim{}, "skyway/MsgLightNodeSaleClaim", nil)
 	cdc.RegisterConcrete(&SetLightNodeSaleContractsProposal{}, "skyway/SetLightNodeSaleContractsProposal", nil)
 	cdc.RegisterConcrete(&MsgNonceOverrideProposal{}, "skyway/MsgNonceOverrideProposal", nil)
+	cdc.RegisterConcrete(&MsgReplenishLostGrainsProposal{}, "skyway/MsgReplenishLostGrainsProposal", nil)
 	cdc.RegisterConcrete(&MsgSetERC20ToTokenDenom{}, "skyway/MsgSetERC20ToTokenDenom", nil)
 }

x/skyway/types/key.go

@@ -115,6 +115,8 @@ var (
 	// [0x06a6b30651341e80276e0d2e19449250]
 	LastUnBondingBlockHeight = HashString("LastUnBondingBlockHeight")
 
+	ReplenishedGrainRecordsKey = HashString("ReplenishedGrainRecordsKey")
+
 	// PastEthSignatureCheckpointKey indexes eth signature checkpoints that have existed
 	// [0x1cbe0be407a979331b98e599eeedd09f]
 	PastEthSignatureCheckpointKey = HashString("PastEthSignatureCheckpointKey")

x/skyway/types/msgs.go

@@ -24,6 +24,7 @@ var (
 	_ sdk.Msg = &MsgUpdateParams{}
 	_ sdk.Msg = &MsgLightNodeSaleClaim{}
 	_ sdk.Msg = &MsgSetERC20ToTokenDenom{}
+	_ sdk.Msg = &MsgReplenishLostGrainsProposal{}
 )
 
 // NewMsgSendToRemote returns a new msgSendToRemote
@@ -481,3 +482,17 @@ func (msg *MsgSetERC20ToTokenDenom) GetSigners() []sdk.AccAddress {
 
 func (msg MsgSetERC20ToTokenDenom) Type() string  { return "set-erc20-to-denom" }
 func (msg MsgSetERC20ToTokenDenom) Route() string { return RouterKey }
+
+func (msg MsgReplenishLostGrainsProposal) Route() string { return RouterKey }
+func (msg MsgReplenishLostGrainsProposal) Type() string  { return "replenish_lost_grains_proposal" }
+func (msg MsgReplenishLostGrainsProposal) ValidateBasic() error {
+	return libmeta.ValidateBasic(&msg)
+}
+
+func (msg MsgReplenishLostGrainsProposal) GetSignBytes() []byte {
+	return sdk.MustSortJSON(ModuleCdc.MustMarshalJSON(msg))
+}
+
+func (msg MsgReplenishLostGrainsProposal) GetSigners() []sdk.AccAddress {
+	return libmeta.GetSigners(&msg)
+}