Add state diff serialization (#15250)

* Add serialization code for state diffs

Adds serialization code for state diffs.
Adds code to create and apply state diffs
Adds fuzz tests and benchmarks for serialization/deserialization

Co-authored-by: Claude <noreply@anthropic.com>

* Add Fulu support

* Review #1

* gazelle

* Fix some fuzzers

* Failing cases from the fuzzers in consensus-types/hdiff

* Fix more fuzz tests

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* add comparison tests

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Use ConvertToElectra in UpgradeToElectra

* Add comments on constants

* Fix readEth1Data

* remove colons from error messages

* Add design doc

* Apply suggestions from code review

Bast

Co-authored-by: Bastin <43618253+Inspector-Butters@users.noreply.github.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Preston Van Loon <preston@pvl.dev>
Co-authored-by: Bastin <43618253+Inspector-Butters@users.noreply.github.com>

beacon-chain/state/interfaces.go

@@ -266,6 +266,8 @@ type WriteOnlyEth1Data interface {
 	SetEth1DepositIndex(val uint64) error
 	ExitEpochAndUpdateChurn(exitBalance primitives.Gwei) (primitives.Epoch, error)
 	ExitEpochAndUpdateChurnForTotalBal(totalActiveBalance primitives.Gwei, exitBalance primitives.Gwei) (primitives.Epoch, error)
+	SetExitBalanceToConsume(val primitives.Gwei) error
+	SetEarliestExitEpoch(val primitives.Epoch) error
 }
 
 // WriteOnlyValidators defines a struct which only has write access to validators methods.
@@ -333,6 +335,7 @@ type WriteOnlyWithdrawals interface {
 	DequeuePendingPartialWithdrawals(num uint64) error
 	SetNextWithdrawalIndex(i uint64) error
 	SetNextWithdrawalValidatorIndex(i primitives.ValidatorIndex) error
+	SetPendingPartialWithdrawals(val []*ethpb.PendingPartialWithdrawal) error
 }
 
 type WriteOnlyConsolidations interface {

beacon-chain/state/state-native/setters_churn.go

@@ -91,3 +91,33 @@ func (b *BeaconState) exitEpochAndUpdateChurn(totalActiveBalance primitives.Gwei
 
 	return b.earliestExitEpoch, nil
 }
+
+// SetExitBalanceToConsume sets the exit balance to consume. This method mutates the state.
+func (b *BeaconState) SetExitBalanceToConsume(exitBalanceToConsume primitives.Gwei) error {
+	if b.version < version.Electra {
+		return errNotSupported("SetExitBalanceToConsume", b.version)
+	}
+
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	b.exitBalanceToConsume = exitBalanceToConsume
+	b.markFieldAsDirty(types.ExitBalanceToConsume)
+
+	return nil
+}
+
+// SetEarliestExitEpoch sets the earliest exit epoch. This method mutates the state.
+func (b *BeaconState) SetEarliestExitEpoch(earliestExitEpoch primitives.Epoch) error {
+	if b.version < version.Electra {
+		return errNotSupported("SetEarliestExitEpoch", b.version)
+	}
+
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	b.earliestExitEpoch = earliestExitEpoch
+	b.markFieldAsDirty(types.EarliestExitEpoch)
+
+	return nil
+}

beacon-chain/state/state-native/setters_withdrawal.go

@@ -100,3 +100,24 @@ func (b *BeaconState) DequeuePendingPartialWithdrawals(n uint64) error {
 
 	return nil
 }
+
+// SetPendingPartialWithdrawals sets the pending partial withdrawals. This method mutates the state.
+func (b *BeaconState) SetPendingPartialWithdrawals(pendingPartialWithdrawals []*eth.PendingPartialWithdrawal) error {
+	if b.version < version.Electra {
+		return errNotSupported("SetPendingPartialWithdrawals", b.version)
+	}
+
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	if pendingPartialWithdrawals == nil {
+		return errors.New("cannot set nil pending partial withdrawals")
+	}
+	b.sharedFieldReferences[types.PendingPartialWithdrawals].MinusRef()
+	b.sharedFieldReferences[types.PendingPartialWithdrawals] = stateutil.NewRef(1)
+
+	b.pendingPartialWithdrawals = pendingPartialWithdrawals
+	b.markFieldAsDirty(types.PendingPartialWithdrawals)
+
+	return nil
+}

beacon-chain/state/state-native/state_trie.go

@@ -650,6 +650,11 @@ func InitializeFromProtoUnsafeFulu(st *ethpb.BeaconStateFulu) (state.BeaconState
 	for i, v := range st.ProposerLookahead {
 		proposerLookahead[i] = primitives.ValidatorIndex(v)
 	}
+	// Proposer lookahead must be exactly 2 * SLOTS_PER_EPOCH in length. We fill in with zeroes instead of erroring out here
+	for i := len(proposerLookahead); i < 2*fieldparams.SlotsPerEpoch; i++ {
+		proposerLookahead = append(proposerLookahead, 0)
+	}
+
 	fieldCount := params.BeaconConfig().BeaconStateFuluFieldCount
 	b := &BeaconState{
 		version:                           version.Fulu,