feat(berad): Bera minting every block with withdrawal to BGT contract

examples/berad/pkg/chain-spec/berachain.go

@@ -33,6 +33,9 @@ type BeraChainSpec struct {
 	]
 	// BGTContractAddress is the address of the BGT contract.
 	BGTContractAddress [20]byte `mapstructure:"bgt-contract-address"`
+	// MaxBeraMintAmount is the amount of BERA minted per block to the BGT
+	// contract.
+	MaxBeraMintAmount uint64 `mapstructure:"max-bera-mint-amount"`
 	// MaxCommitteeSize is the maximum size of the committee.
 	MaxCommitteeSize uint64 `mapstructure:"max-committee-size"`
 }

examples/berad/pkg/state-transition/state_processor_staking.go

@@ -172,7 +172,7 @@ func (sp *StateProcessor[
 	_ BeaconStateT,
 	_ BeaconBlockBodyT,
 ) error {
-	// TODO: implement
+	// TODO: implement by calling ExpectedWithdrawals and then applying them.
 	return nil
 }
 
@@ -190,7 +190,20 @@ func (sp *StateProcessor[
 // ExpectedWithdrawals retrieves the expected withdrawals.
 func (sp *StateProcessor[
 	_, _, _, BeaconStateT, _, _, _,
-	_, _, _, _, _, _, _, WithdrawalsT, _,
+	_, _, _, _, _, _, WithdrawalT, WithdrawalsT, _,
 ]) ExpectedWithdrawals(st BeaconStateT) (WithdrawalsT, error) {
-	return st.GetWithdrawals()
+	withdrawals, err := st.GetWithdrawals()
+	if err != nil {
+		return nil, err
+	}
+
+	var bgtWithdrawal WithdrawalT
+	bgtWithdrawal = bgtWithdrawal.New(
+		math.U64(len(withdrawals)),
+		math.ValidatorIndex(0), // TODO: replace with validator set cap.
+		sp.cs.BGTContractAddress,
+		math.U64(sp.cs.MaxBeraMintAmount),
+	)
+
+	return append(withdrawals, bgtWithdrawal), nil
 }

mod/chain-spec/pkg/chain/chain_spec.go

@@ -134,6 +134,13 @@ type Spec[
 	// slashing penalties.
 	ProportionalSlashingMultiplier() uint64
 
+	// BGTContractAddress is the address of the BGT contract.
+	BGTContractAddress() [20]byte
+
+	// MaxBeraMintAmount is the amount of BERA minted per block to the BGT
+	// contract.
+	MaxBeraMintAmount() uint64
+
 	// Capella Values
 
 	// MaxWithdrawalsPerPayload returns the maximum number of withdrawals per
@@ -416,6 +423,21 @@ func (c chainSpec[
 	return c.Data.ProportionalSlashingMultiplier
 }
 
+// BGTContractAddress is the address of the BGT contract.
+func (c chainSpec[
+	DomainTypeT, EpochT, ExecutionAddressT, SlotT, CometBFTConfigT,
+]) BGTContractAddress() [20]byte {
+	return c.Data.BGTContractAddress
+}
+
+// MaxBeraMintAmount is the amount of BERA minted per block to the BGT
+// contract.
+func (c chainSpec[
+	DomainTypeT, EpochT, ExecutionAddressT, SlotT, CometBFTConfigT,
+]) MaxBeraMintAmount() uint64 {
+	return c.Data.MaxBeraMintAmount
+}
+
 // MaxWithdrawalsPerPayload returns the maximum number of withdrawals per
 // payload.
 func (c chainSpec[

mod/chain-spec/pkg/chain/data.go

@@ -117,6 +117,12 @@ type SpecData[
 	// base penalty.
 	ProportionalSlashingMultiplier uint64 `mapstructure:"proportional-slashing-multiplier"`
 
+	// BGTContractAddress is the address of the BGT contract.
+	BGTContractAddress [20]byte `mapstructure:"bgt-contract-address"`
+	// MaxBeraMintAmount is the amount of BERA minted per block to the BGT
+	// contract.
+	MaxBeraMintAmount uint64 `mapstructure:"max-bera-mint-amount"`
+
 	// Capella Values
 	//
 	// MaxWithdrawalsPerPayload indicates the maximum number of withdrawal

mod/state-transition/pkg/core/state/statedb.go

@@ -209,6 +209,23 @@ func (s *StateDB[
 		return nil, err
 	}
 
+	// Note by prepending the withdrawals for bera minting here we
+	// explicitly request for these (automatic) withdrawals to be
+	// included in a block. This feels future-proof if we ever change
+	// the amount, but may be considered wasteful as well.
+	var mintWithdrawal WithdrawalT
+	withdrawals = append(withdrawals, mintWithdrawal.New(
+		math.U64(withdrawalIndex),
+
+		// QUESTION: if we use withdrawals, what do we use here?
+		// Proposer index? 0 (which is a valid index)? MaxU64??
+		0,
+
+		s.cs.BGTContractAddress(),
+		math.Gwei(s.cs.MaxBeraMintAmount()),
+	))
+	withdrawalIndex++
+
 	validatorIndex, err := s.GetNextWithdrawalValidatorIndex()
 	if err != nil {
 		return nil, err