Return ErrStateDiffIncompatible when state-diff enabled on incompatible database

When the state-diff feature is enabled but the database was created
without state-diff support, NewKVStore now returns the store along
with ErrStateDiffIncompatible. The caller (openDB) checks for this
error, logs a warning, disables the feature, and continues using
the returned store.

This prevents migrateToColdHdiff from being called on a database
that lacks the required state-diff infrastructure.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

BUILD.bazel

@@ -193,7 +193,7 @@ nogo(
         "//tools/analyzers/featureconfig:go_default_library",
         "//tools/analyzers/gocognit:go_default_library",
         "//tools/analyzers/ineffassign:go_default_library",
-        "//tools/analyzers/httperror:go_default_library",
+        "//tools/analyzers/httpwriter:go_default_library",
         "//tools/analyzers/interfacechecker:go_default_library",
         "//tools/analyzers/logcapitalization:go_default_library",
         "//tools/analyzers/logruswitherror:go_default_library",

beacon-chain/blockchain/execution_engine.go

@@ -323,14 +323,17 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,
 	var ok bool
 	e := slots.ToEpoch(slot)
 	stateEpoch := slots.ToEpoch(st.Slot())
-	if e == stateEpoch {
+	fuluAndNextEpoch := st.Version() >= version.Fulu && e == stateEpoch+1
+	if e == stateEpoch || fuluAndNextEpoch {
 		val, ok = s.trackedProposer(st, slot)
 		if !ok {
 			return emptyAttri
 		}
 	}
-	st = st.Copy()
 	if slot > st.Slot() {
+		// At this point either we know we are proposing on a future slot or we need to still compute the
+		// right proposer index pre-Fulu, either way we need to copy the state to process it.
+		st = st.Copy()
 		var err error
 		st, err = transition.ProcessSlotsUsingNextSlotCache(ctx, st, headRoot, slot)
 		if err != nil {
@@ -338,7 +341,7 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,
 			return emptyAttri
 		}
 	}
-	if e > stateEpoch {
+	if e > stateEpoch && !fuluAndNextEpoch {
 		emptyAttri := payloadattribute.EmptyWithVersion(st.Version())
 		val, ok = s.trackedProposer(st, slot)
 		if !ok {

beacon-chain/blockchain/process_attestation_helpers.go

@@ -22,7 +22,7 @@ import (
 // The caller of this function must have a lock on forkchoice.
 func (s *Service) getRecentPreState(ctx context.Context, c *ethpb.Checkpoint) state.ReadOnlyBeaconState {
 	headEpoch := slots.ToEpoch(s.HeadSlot())
-	if c.Epoch < headEpoch || c.Epoch == 0 {
+	if c.Epoch+1 < headEpoch || c.Epoch == 0 {
 		return nil
 	}
 	// Only use head state if the head state is compatible with the target checkpoint.
@@ -30,11 +30,13 @@ func (s *Service) getRecentPreState(ctx context.Context, c *ethpb.Checkpoint) st
 	if err != nil {
 		return nil
 	}
-	headDependent, err := s.cfg.ForkChoiceStore.DependentRootForEpoch([32]byte(headRoot), c.Epoch-1)
+	// headEpoch - 1 equals c.Epoch if c is from the previous epoch and equals c.Epoch - 1 if c is from the current epoch.
+	// We don't use the smaller c.Epoch - 1 because forkchoice would not have the data to answer that.
+	headDependent, err := s.cfg.ForkChoiceStore.DependentRootForEpoch([32]byte(headRoot), headEpoch-1)
 	if err != nil {
 		return nil
 	}
-	targetDependent, err := s.cfg.ForkChoiceStore.DependentRootForEpoch([32]byte(c.Root), c.Epoch-1)
+	targetDependent, err := s.cfg.ForkChoiceStore.DependentRootForEpoch([32]byte(c.Root), headEpoch-1)
 	if err != nil {
 		return nil
 	}
@@ -43,7 +45,7 @@ func (s *Service) getRecentPreState(ctx context.Context, c *ethpb.Checkpoint) st
 	}
 
 	// If the head state alone is enough, we can return it directly read only.
-	if c.Epoch == headEpoch {
+	if c.Epoch <= headEpoch {
 		st, err := s.HeadStateReadOnly(ctx)
 		if err != nil {
 			return nil

beacon-chain/blockchain/process_attestation_test.go

@@ -170,12 +170,13 @@ func TestService_GetRecentPreState(t *testing.T) {
 	err = s.SetFinalizedCheckpoint(cp0)
 	require.NoError(t, err)
 
-	st, root, err := prepareForkchoiceState(ctx, 31, [32]byte(ckRoot), [32]byte{}, [32]byte{'R'}, cp0, cp0)
+	st, blk, err := prepareForkchoiceState(ctx, 31, [32]byte(ckRoot), [32]byte{}, [32]byte{'R'}, cp0, cp0)
 	require.NoError(t, err)
-	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, root))
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blk))
 	service.head = &head{
 		root:  [32]byte(ckRoot),
 		state: s,
+		block: blk,
 		slot:  31,
 	}
 	require.NotNil(t, service.getRecentPreState(ctx, &ethpb.Checkpoint{Epoch: 1, Root: ckRoot}))
@@ -197,12 +198,13 @@ func TestService_GetRecentPreState_Old_Checkpoint(t *testing.T) {
 	err = s.SetFinalizedCheckpoint(cp0)
 	require.NoError(t, err)
 
-	st, root, err := prepareForkchoiceState(ctx, 33, [32]byte(ckRoot), [32]byte{}, [32]byte{'R'}, cp0, cp0)
+	st, blk, err := prepareForkchoiceState(ctx, 33, [32]byte(ckRoot), [32]byte{}, [32]byte{'R'}, cp0, cp0)
 	require.NoError(t, err)
-	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, root))
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blk))
 	service.head = &head{
 		root:  [32]byte(ckRoot),
 		state: s,
+		block: blk,
 		slot:  33,
 	}
 	require.IsNil(t, service.getRecentPreState(ctx, &ethpb.Checkpoint{}))
@@ -227,6 +229,7 @@ func TestService_GetRecentPreState_Same_DependentRoots(t *testing.T) {
 	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blk))
 	st, blk, err = prepareForkchoiceState(ctx, 64, [32]byte{'T'}, blk.Root(), [32]byte{}, cp0, cp0)
 	require.NoError(t, err)
+	headBlock := blk
 	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blk))
 	st, blk, err = prepareForkchoiceState(ctx, 33, [32]byte{'U'}, [32]byte(ckRoot), [32]byte{}, cp0, cp0)
 	require.NoError(t, err)
@@ -235,8 +238,9 @@ func TestService_GetRecentPreState_Same_DependentRoots(t *testing.T) {
 
 	service.head = &head{
 		root:  [32]byte{'T'},
-		state: s,
+		block: headBlock,
 		slot:  64,
+		state: s,
 	}
 	require.NotNil(t, service.getRecentPreState(ctx, &ethpb.Checkpoint{Epoch: 2, Root: cpRoot[:]}))
 }
@@ -263,6 +267,7 @@ func TestService_GetRecentPreState_Different_DependentRoots(t *testing.T) {
 	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blk))
 	st, blk, err = prepareForkchoiceState(ctx, 64, [32]byte{'U'}, blk.Root(), [32]byte{}, cp0, cp0)
 	require.NoError(t, err)
+	headBlock := blk
 	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blk))
 	st, blk, err = prepareForkchoiceState(ctx, 33, [32]byte{'V'}, [32]byte(ckRoot), [32]byte{}, cp0, cp0)
 	require.NoError(t, err)
@@ -270,7 +275,8 @@ func TestService_GetRecentPreState_Different_DependentRoots(t *testing.T) {
 	cpRoot := blk.Root()
 
 	service.head = &head{
-		root:  [32]byte{'T'},
+		root:  [32]byte{'U'},
+		block: headBlock,
 		state: s,
 		slot:  64,
 	}
@@ -287,12 +293,13 @@ func TestService_GetRecentPreState_Different(t *testing.T) {
 	err = s.SetFinalizedCheckpoint(cp0)
 	require.NoError(t, err)
 
-	st, root, err := prepareForkchoiceState(ctx, 33, [32]byte(ckRoot), [32]byte{}, [32]byte{'R'}, cp0, cp0)
+	st, blk, err := prepareForkchoiceState(ctx, 33, [32]byte(ckRoot), [32]byte{}, [32]byte{'R'}, cp0, cp0)
 	require.NoError(t, err)
-	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, root))
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blk))
 	service.head = &head{
 		root:  [32]byte(ckRoot),
 		state: s,
+		block: blk,
 		slot:  33,
 	}
 	require.IsNil(t, service.getRecentPreState(ctx, &ethpb.Checkpoint{}))

beacon-chain/blockchain/process_block.go

@@ -295,14 +295,6 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []consensusblocks.ROBlo
 			return errors.Wrap(err, "could not set optimistic block to valid")
 		}
 	}
-	arg := &fcuConfig{
-		headState: preState,
-		headRoot:  lastBR,
-		headBlock: lastB,
-	}
-	if _, err := s.notifyForkchoiceUpdate(ctx, arg); err != nil {
-		return err
-	}
 	return s.saveHeadNoDB(ctx, lastB, lastBR, preState, !isValidPayload)
 }
 

beacon-chain/blockchain/process_block_test.go

@@ -820,24 +820,6 @@ func TestOnBlock_NilBlock(t *testing.T) {
 	require.Equal(t, true, IsInvalidBlock(err))
 }
 
-func TestOnBlock_InvalidSignature(t *testing.T) {
-	service, tr := minimalTestService(t)
-	ctx := tr.ctx
-
-	gs, keys := util.DeterministicGenesisState(t, 32)
-	require.NoError(t, service.saveGenesisData(ctx, gs))
-
-	blk, err := util.GenerateFullBlock(gs, keys, util.DefaultBlockGenConfig(), 1)
-	require.NoError(t, err)
-	blk.Signature = []byte{'a'} // Mutate the signature.
-	wsb, err := consensusblocks.NewSignedBeaconBlock(blk)
-	require.NoError(t, err)
-	preState, err := service.getBlockPreState(ctx, wsb.Block())
-	require.NoError(t, err)
-	_, err = service.validateStateTransition(ctx, preState, wsb)
-	require.Equal(t, true, IsInvalidBlock(err))
-}
-
 func TestOnBlock_CallNewPayloadAndForkchoiceUpdated(t *testing.T) {
 	params.SetupTestConfigCleanup(t)
 	config := params.BeaconConfig()

beacon-chain/core/blocks/header_test.go

@@ -290,52 +290,3 @@ func TestProcessBlockHeader_OK(t *testing.T) {
 	}
 	assert.Equal(t, true, proto.Equal(nsh, expected), "Expected %v, received %v", expected, nsh)
 }
-
-func TestBlockSignatureSet_OK(t *testing.T) {
-	validators := make([]*ethpb.Validator, params.BeaconConfig().MinGenesisActiveValidatorCount)
-	for i := range validators {
-		validators[i] = &ethpb.Validator{
-			PublicKey:             make([]byte, 32),
-			WithdrawalCredentials: make([]byte, 32),
-			ExitEpoch:             params.BeaconConfig().FarFutureEpoch,
-			Slashed:               true,
-		}
-	}
-
-	state, err := util.NewBeaconState()
-	require.NoError(t, err)
-	require.NoError(t, state.SetValidators(validators))
-	require.NoError(t, state.SetSlot(10))
-	require.NoError(t, state.SetLatestBlockHeader(util.HydrateBeaconHeader(&ethpb.BeaconBlockHeader{
-		Slot:          9,
-		ProposerIndex: 0,
-	})))
-
-	latestBlockSignedRoot, err := state.LatestBlockHeader().HashTreeRoot()
-	require.NoError(t, err)
-
-	currentEpoch := time.CurrentEpoch(state)
-	priv, err := bls.RandKey()
-	require.NoError(t, err)
-	pID, err := helpers.BeaconProposerIndex(t.Context(), state)
-	require.NoError(t, err)
-	block := util.NewBeaconBlock()
-	block.Block.Slot = 10
-	block.Block.ProposerIndex = pID
-	block.Block.Body.RandaoReveal = bytesutil.PadTo([]byte{'A', 'B', 'C'}, 96)
-	block.Block.ParentRoot = latestBlockSignedRoot[:]
-	block.Signature, err = signing.ComputeDomainAndSign(state, currentEpoch, block.Block, params.BeaconConfig().DomainBeaconProposer, priv)
-	require.NoError(t, err)
-	proposerIdx, err := helpers.BeaconProposerIndex(t.Context(), state)
-	require.NoError(t, err)
-	validators[proposerIdx].Slashed = false
-	validators[proposerIdx].PublicKey = priv.PublicKey().Marshal()
-	err = state.UpdateValidatorAtIndex(proposerIdx, validators[proposerIdx])
-	require.NoError(t, err)
-	set, err := blocks.BlockSignatureBatch(state, block.Block.ProposerIndex, block.Signature, block.Block.HashTreeRoot)
-	require.NoError(t, err)
-
-	verified, err := set.Verify()
-	require.NoError(t, err)
-	assert.Equal(t, true, verified, "Block signature set returned a set which was unable to be verified")
-}

beacon-chain/core/blocks/signature.go

@@ -122,24 +122,6 @@ func VerifyBlockSignatureUsingCurrentFork(beaconState state.ReadOnlyBeaconState,
 	return nil
 }
 
-// BlockSignatureBatch retrieves the block signature batch from the provided block and its corresponding state.
-func BlockSignatureBatch(beaconState state.ReadOnlyBeaconState,
-	proposerIndex primitives.ValidatorIndex,
-	sig []byte,
-	rootFunc func() ([32]byte, error)) (*bls.SignatureBatch, error) {
-	currentEpoch := slots.ToEpoch(beaconState.Slot())
-	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorsRoot())
-	if err != nil {
-		return nil, err
-	}
-	proposer, err := beaconState.ValidatorAtIndex(proposerIndex)
-	if err != nil {
-		return nil, err
-	}
-	proposerPubKey := proposer.PublicKey
-	return signing.BlockSignatureBatch(proposerPubKey, sig, domain, rootFunc)
-}
-
 // RandaoSignatureBatch retrieves the relevant randao specific signature batch object
 // from a block and its corresponding state.
 func RandaoSignatureBatch(

beacon-chain/core/electra/consolidations.go

@@ -278,12 +278,12 @@ func ProcessConsolidationRequests(ctx context.Context, st state.BeaconState, req
 		if uint64(curEpoch) < e {
 			continue
 		}
-		bal, err := st.PendingBalanceToWithdraw(srcIdx)
+		hasBal, err := st.HasPendingBalanceToWithdraw(srcIdx)
 		if err != nil {
 			log.WithError(err).Error("Failed to fetch pending balance to withdraw")
 			continue
 		}
-		if bal > 0 {
+		if hasBal {
 			continue
 		}
 

beacon-chain/core/transition/transition_no_verify_sig.go

@@ -182,12 +182,6 @@ func ProcessBlockNoVerifyAnySig(
 		return nil, nil, err
 	}
 
-	sig := signed.Signature()
-	bSet, err := b.BlockSignatureBatch(st, blk.ProposerIndex(), sig[:], blk.HashTreeRoot)
-	if err != nil {
-		tracing.AnnotateError(span, err)
-		return nil, nil, errors.Wrap(err, "could not retrieve block signature set")
-	}
 	randaoReveal := signed.Block().Body().RandaoReveal()
 	rSet, err := b.RandaoSignatureBatch(ctx, st, randaoReveal[:])
 	if err != nil {
@@ -201,7 +195,7 @@ func ProcessBlockNoVerifyAnySig(
 
 	// Merge beacon block, randao and attestations signatures into a set.
 	set := bls.NewSet()
-	set.Join(bSet).Join(rSet).Join(aSet)
+	set.Join(rSet).Join(aSet)
 
 	if blk.Version() >= version.Capella {
 		changes, err := signed.Block().Body().BLSToExecutionChanges()

beacon-chain/core/transition/transition_no_verify_sig_test.go

@@ -157,9 +157,8 @@ func TestProcessBlockNoVerify_SigSetContainsDescriptions(t *testing.T) {
 	set, _, err := transition.ProcessBlockNoVerifyAnySig(t.Context(), beaconState, wsb)
 	require.NoError(t, err)
 	assert.Equal(t, len(set.Signatures), len(set.Descriptions), "Signatures and descriptions do not match up")
-	assert.Equal(t, "block signature", set.Descriptions[0])
-	assert.Equal(t, "randao signature", set.Descriptions[1])
-	assert.Equal(t, "attestation signature", set.Descriptions[2])
+	assert.Equal(t, "randao signature", set.Descriptions[0])
+	assert.Equal(t, "attestation signature", set.Descriptions[1])
 }
 
 func TestProcessOperationsNoVerifyAttsSigs_OK(t *testing.T) {

beacon-chain/das/needs.go

@@ -67,9 +67,9 @@ func NewSyncNeeds(current CurrentSlotter, oldestSlotFlagPtr *primitives.Slot, bl
 
 	// Override spec minimum block retention with user-provided flag only if it is lower than the spec minimum.
 	sn.blockRetention = primitives.Epoch(params.BeaconConfig().MinEpochsForBlockRequests)
+
 	if oldestSlotFlagPtr != nil {
-		oldestEpoch := slots.ToEpoch(*oldestSlotFlagPtr)
-		if oldestEpoch < sn.blockRetention {
+		if *oldestSlotFlagPtr <= syncEpochOffset(current(), sn.blockRetention) {
 			sn.validOldestSlotPtr = oldestSlotFlagPtr
 		} else {
 			log.WithField("backfill-oldest-slot", *oldestSlotFlagPtr).

beacon-chain/das/needs_test.go

@@ -128,6 +128,9 @@ func TestSyncNeedsInitialize(t *testing.T) {
 	slotsPerEpoch := params.BeaconConfig().SlotsPerEpoch
 	minBlobEpochs := params.BeaconConfig().MinEpochsForBlobsSidecarsRequest
 	minColEpochs := params.BeaconConfig().MinEpochsForDataColumnSidecarsRequest
+	denebSlot := slots.UnsafeEpochStart(params.BeaconConfig().DenebForkEpoch)
+	fuluSlot := slots.UnsafeEpochStart(params.BeaconConfig().FuluForkEpoch)
+	minSlots := slots.UnsafeEpochStart(primitives.Epoch(params.BeaconConfig().MinEpochsForBlockRequests))
 
 	currentSlot := primitives.Slot(10000)
 	currentFunc := func() primitives.Slot { return currentSlot }
@@ -141,6 +144,7 @@ func TestSyncNeedsInitialize(t *testing.T) {
 		expectedCol       primitives.Epoch
 		name              string
 		input             SyncNeeds
+		current           func() primitives.Slot
 	}{
 		{
 			name:              "basic initialization with no flags",
@@ -174,13 +178,13 @@ func TestSyncNeedsInitialize(t *testing.T) {
 		{
 			name:              "valid oldestSlotFlagPtr (earlier than spec minimum)",
 			blobRetentionFlag: 0,
-			oldestSlotFlagPtr: func() *primitives.Slot {
-				slot := primitives.Slot(10)
-				return &slot
-			}(),
+			oldestSlotFlagPtr: &denebSlot,
 			expectValidOldest: true,
 			expectedBlob:      minBlobEpochs,
 			expectedCol:       minColEpochs,
+			current: func() primitives.Slot {
+				return fuluSlot + minSlots
+			},
 		},
 		{
 			name:              "invalid oldestSlotFlagPtr (later than spec minimum)",
@@ -210,6 +214,9 @@ func TestSyncNeedsInitialize(t *testing.T) {
 		{
 			name:              "both blob retention flag and oldest slot set",
 			blobRetentionFlag: minBlobEpochs + 5,
+			current: func() primitives.Slot {
+				return fuluSlot + minSlots
+			},
 			oldestSlotFlagPtr: func() *primitives.Slot {
 				slot := primitives.Slot(100)
 				return &slot
@@ -232,16 +239,27 @@ func TestSyncNeedsInitialize(t *testing.T) {
 			expectedBlob:      5000,
 			expectedCol:       5000,
 		},
+		{
+			name:              "regression for deneb start",
+			blobRetentionFlag: 8212500,
+			expectValidOldest: true,
+			oldestSlotFlagPtr: &denebSlot,
+			current: func() primitives.Slot {
+				return fuluSlot + minSlots
+			},
+			expectedBlob: 8212500,
+			expectedCol:  8212500,
+		},
 	}
 
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
-			result, err := NewSyncNeeds(currentFunc, tc.oldestSlotFlagPtr, tc.blobRetentionFlag)
+			if tc.current == nil {
+				tc.current = currentFunc
+			}
+			result, err := NewSyncNeeds(tc.current, tc.oldestSlotFlagPtr, tc.blobRetentionFlag)
 			require.NoError(t, err)
 
-			// Check that current, deneb, fulu are set correctly
-			require.Equal(t, currentSlot, result.current())
-
 			// Check retention calculations
 			require.Equal(t, tc.expectedBlob, result.blobRetention)
 			require.Equal(t, tc.expectedCol, result.colRetention)

beacon-chain/db/filesystem/BUILD.bazel

@@ -38,7 +38,6 @@ go_library(
         "@com_github_prometheus_client_golang//prometheus/promauto:go_default_library",
         "@com_github_sirupsen_logrus//:go_default_library",
         "@com_github_spf13_afero//:go_default_library",
-        "@org_golang_x_sync//errgroup:go_default_library",
     ],
 )
 

beacon-chain/db/filesystem/data_column.go

@@ -25,7 +25,6 @@ import (
 	"github.com/OffchainLabs/prysm/v7/time/slots"
 	"github.com/pkg/errors"
 	"github.com/spf13/afero"
-	"golang.org/x/sync/errgroup"
 )
 
 const (
@@ -626,7 +625,7 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsExistingFile(filePath string
 	}
 
 	// Create the SSZ encoded data column sidecars.
-	var sszEncodedDataColumnSidecarsBytes []byte
+	var sszEncodedDataColumnSidecars []byte
 
 	// Initialize the count of the saved SSZ encoded data column sidecar.
 	storedCount := uint8(0)
@@ -637,26 +636,7 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsExistingFile(filePath string
 			break
 		}
 
-		var wg errgroup.Group
-		sszEncodedDataColumnSidecars := make([][]byte, len(dataColumnSidecars))
-		for i, dataColumnSidecar := range dataColumnSidecars {
-			wg.Go(func() error {
-				// SSZ encode the data column sidecar.
-				sszEncodedDataColumnSidecar, err := dataColumnSidecar.MarshalSSZ()
-				if err != nil {
-					return errors.Wrap(err, "data column sidecar marshal SSZ")
-				}
-
-				sszEncodedDataColumnSidecars[i] = sszEncodedDataColumnSidecar
-				return nil
-			})
-		}
-
-		if err := wg.Wait(); err != nil {
-			return err
-		}
-
-		for i, dataColumnSidecar := range dataColumnSidecars {
+		for _, dataColumnSidecar := range dataColumnSidecars {
 			// Extract the data columns index.
 			dataColumnIndex := dataColumnSidecar.Index
 
@@ -678,7 +658,10 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsExistingFile(filePath string
 			}
 
 			// SSZ encode the data column sidecar.
-			sszEncodedDataColumnSidecar := sszEncodedDataColumnSidecars[i]
+			sszEncodedDataColumnSidecar, err := dataColumnSidecar.MarshalSSZ()
+			if err != nil {
+				return errors.Wrap(err, "data column sidecar marshal SSZ")
+			}
 
 			// Compute the size of the SSZ encoded data column sidecar.
 			incomingSszEncodedDataColumnSidecarSize := uint32(len(sszEncodedDataColumnSidecar))
@@ -697,7 +680,7 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsExistingFile(filePath string
 			storedCount++
 
 			// Append the SSZ encoded data column sidecar to the SSZ encoded data column sidecars.
-			sszEncodedDataColumnSidecarsBytes = append(sszEncodedDataColumnSidecarsBytes, sszEncodedDataColumnSidecar...)
+			sszEncodedDataColumnSidecars = append(sszEncodedDataColumnSidecars, sszEncodedDataColumnSidecar...)
 		}
 	}
 
@@ -712,11 +695,11 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsExistingFile(filePath string
 	}
 
 	// Append the SSZ encoded data column sidecars to the end of the file.
-	count, err = file.WriteAt(sszEncodedDataColumnSidecarsBytes, metadata.fileSize)
+	count, err = file.WriteAt(sszEncodedDataColumnSidecars, metadata.fileSize)
 	if err != nil {
 		return errors.Wrap(err, "write SSZ encoded data column sidecars")
 	}
-	if count != len(sszEncodedDataColumnSidecarsBytes) {
+	if count != len(sszEncodedDataColumnSidecars) {
 		return errWrongBytesWritten
 	}
 
@@ -738,7 +721,7 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsNewFile(filePath string, inp
 
 	var (
 		sszEncodedDataColumnSidecarRefSize int
-		sszEncodedDataColumnSidecarsBytes  []byte
+		sszEncodedDataColumnSidecars       []byte
 	)
 
 	// Initialize the count of the saved SSZ encoded data column sidecar.
@@ -750,26 +733,7 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsNewFile(filePath string, inp
 			break
 		}
 
-		var wg errgroup.Group
-		sszEncodedDataColumnSidecars := make([][]byte, len(dataColumnSidecars))
-		for i, dataColumnSidecar := range dataColumnSidecars {
-			wg.Go(func() error {
-				// SSZ encode the first data column sidecar.
-				sszEncodedDataColumnSidecar, err := dataColumnSidecar.MarshalSSZ()
-				if err != nil {
-					return errors.Wrap(err, "data column sidecar marshal SSZ")
-				}
-
-				sszEncodedDataColumnSidecars[i] = sszEncodedDataColumnSidecar
-				return nil
-			})
-		}
-
-		if err := wg.Wait(); err != nil {
-			return err
-		}
-
-		for i, dataColumnSidecar := range dataColumnSidecars {
+		for _, dataColumnSidecar := range dataColumnSidecars {
 			// Extract the data column index.
 			dataColumnIndex := dataColumnSidecar.Index
 
@@ -792,7 +756,10 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsNewFile(filePath string, inp
 			storedCount++
 
 			// SSZ encode the first data column sidecar.
-			sszEncodedDataColumnSidecar := sszEncodedDataColumnSidecars[i]
+			sszEncodedDataColumnSidecar, err := dataColumnSidecar.MarshalSSZ()
+			if err != nil {
+				return errors.Wrap(err, "data column sidecar marshal SSZ")
+			}
 
 			// Check if the size of the SSZ encoded data column sidecar is correct.
 			if sszEncodedDataColumnSidecarRefSize != 0 && len(sszEncodedDataColumnSidecar) != sszEncodedDataColumnSidecarRefSize {
@@ -803,7 +770,7 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsNewFile(filePath string, inp
 			sszEncodedDataColumnSidecarRefSize = len(sszEncodedDataColumnSidecar)
 
 			// Append the first SSZ encoded data column sidecar to the SSZ encoded data column sidecars.
-			sszEncodedDataColumnSidecarsBytes = append(sszEncodedDataColumnSidecarsBytes, sszEncodedDataColumnSidecar...)
+			sszEncodedDataColumnSidecars = append(sszEncodedDataColumnSidecars, sszEncodedDataColumnSidecar...)
 		}
 	}
 
@@ -840,12 +807,12 @@ func (dcs *DataColumnStorage) saveDataColumnSidecarsNewFile(filePath string, inp
 	rawIndices := indices.raw()
 
 	// Concatenate the version, the data column sidecar size, the data column indices and the SSZ encoded data column sidecar.
-	countToWrite := headerSize + len(sszEncodedDataColumnSidecarsBytes)
+	countToWrite := headerSize + len(sszEncodedDataColumnSidecars)
 	bytes := make([]byte, 0, countToWrite)
 	bytes = append(bytes, byte(version))
 	bytes = append(bytes, encodedSszEncodedDataColumnSidecarSize[:]...)
 	bytes = append(bytes, rawIndices[:]...)
-	bytes = append(bytes, sszEncodedDataColumnSidecarsBytes...)
+	bytes = append(bytes, sszEncodedDataColumnSidecars...)
 
 	countWritten, err := file.Write(bytes)
 	if err != nil {

beacon-chain/db/iface/interface.go

@@ -89,6 +89,7 @@ type NoHeadAccessDatabase interface {
 	SaveBlocks(ctx context.Context, blocks []interfaces.ReadOnlySignedBeaconBlock) error
 	SaveROBlocks(ctx context.Context, blks []blocks.ROBlock, cache bool) error
 	SaveGenesisBlockRoot(ctx context.Context, blockRoot [32]byte) error
+	SlotByBlockRoot(context.Context, [32]byte) (primitives.Slot, error)
 	// State related methods.
 	SaveState(ctx context.Context, state state.ReadOnlyBeaconState, blockRoot [32]byte) error
 	SaveStates(ctx context.Context, states []state.ReadOnlyBeaconState, blockRoots [][32]byte) error
@@ -96,6 +97,7 @@ type NoHeadAccessDatabase interface {
 	DeleteStates(ctx context.Context, blockRoots [][32]byte) error
 	SaveStateSummary(ctx context.Context, summary *ethpb.StateSummary) error
 	SaveStateSummaries(ctx context.Context, summaries []*ethpb.StateSummary) error
+	SlotInDiffTree(primitives.Slot) (uint64, int, error)
 	// Checkpoint operations.
 	SaveJustifiedCheckpoint(ctx context.Context, checkpoint *ethpb.Checkpoint) error
 	SaveFinalizedCheckpoint(ctx context.Context, checkpoint *ethpb.Checkpoint) error

beacon-chain/db/kv/BUILD.bazel

@@ -32,6 +32,7 @@ go_library(
         "state_diff_helpers.go",
         "state_summary.go",
         "state_summary_cache.go",
+        "testing_helpers.go",
         "utils.go",
         "validated_checkpoint.go",
         "wss.go",

beacon-chain/db/kv/error.go

@@ -22,6 +22,10 @@ var ErrNotFoundFeeRecipient = errors.Wrap(ErrNotFound, "fee recipient")
 // ErrNotFoundMetadataSeqNum is a not found error specifically for the metadata sequence number getter
 var ErrNotFoundMetadataSeqNum = errors.Wrap(ErrNotFound, "metadata sequence number")
 
+// ErrStateDiffIncompatible is returned when state-diff feature is enabled
+// but the database was created without state-diff support.
+var ErrStateDiffIncompatible = errors.New("state-diff feature enabled but database was created without state-diff support")
+
 var errEmptyBlockSlice = errors.New("[]blocks.ROBlock is empty")
 var errIncorrectBlockParent = errors.New("unexpected missing or forked blocks in a []ROBlock")
 var errFinalizedChildNotFound = errors.New("unable to find finalized root descending from backfill batch")

beacon-chain/db/kv/genesis.go

@@ -7,6 +7,7 @@ import (
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/blocks"
 	dbIface "github.com/OffchainLabs/prysm/v7/beacon-chain/db/iface"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/state"
+	"github.com/OffchainLabs/prysm/v7/config/features"
 	"github.com/OffchainLabs/prysm/v7/encoding/ssz/detect"
 	"github.com/OffchainLabs/prysm/v7/genesis"
 	ethpb "github.com/OffchainLabs/prysm/v7/proto/prysm/v1alpha1"
@@ -42,6 +43,15 @@ func (s *Store) SaveGenesisData(ctx context.Context, genesisState state.BeaconSt
 	if err := s.SaveGenesisBlockRoot(ctx, genesisBlkRoot); err != nil {
 		return errors.Wrap(err, "could not save genesis block root")
 	}
+
+	// Initialize state-diff if enabled and not yet initialized.
+	if features.Get().EnableStateDiff && s.stateDiffCache == nil {
+		if err := s.initializeStateDiff(0, genesisState); err != nil {
+			return errors.Wrap(err, "failed to initialize state diff for genesis")
+		}
+		log.Info("Initialized state-diff with genesis state")
+	}
+
 	return nil
 }
 

beacon-chain/db/kv/kv.go

@@ -204,11 +204,31 @@ func NewKVStore(ctx context.Context, dirPath string, opts ...KVStoreOption) (*St
 	}
 
 	if features.Get().EnableStateDiff {
-		sdCache, err := newStateDiffCache(kv)
+		// Check if offset already exists (existing state-diff database).
+		hasOffset, err := kv.hasStateDiffOffset()
 		if err != nil {
 			return nil, err
 		}
-		kv.stateDiffCache = sdCache
+
+		if hasOffset {
+			// Existing state-diff database - restarts not yet supported.
+			return nil, errors.New("restarting with existing state-diff database not yet supported")
+		}
+
+		// Check if this is a new database (no head block).
+		headBlock, err := kv.HeadBlock(ctx)
+		if err != nil {
+			return nil, errors.Wrap(err, "could not get head block")
+		}
+
+		if headBlock == nil {
+			// New database - will be initialized later during checkpoint/genesis sync.
+			// stateDiffCache stays nil until SaveOrigin or SaveGenesisData initializes it.
+			log.Info("State-diff enabled: will be initialized during checkpoint or genesis sync")
+		} else {
+			// Existing database without state-diff - return store with error for caller to handle.
+			return kv, ErrStateDiffIncompatible
+		}
 	}
 
 	return kv, nil

beacon-chain/db/kv/state_diff.go

@@ -23,6 +23,16 @@ const (
 	The data at level 0 is saved every 2**exponent[0] slots and always contains a full state snapshot that is used as a base for the delta saved at other levels.
 */
 
+// SlotInDiffTree returns whether the given slot is a saving point in the diff tree.
+// It it is, it also returns the offset and level in the tree.
+func (s *Store) SlotInDiffTree(slot primitives.Slot) (uint64, int, error) {
+	offset := s.getOffset()
+	if uint64(slot) < offset {
+		return 0, -1, ErrSlotBeforeOffset
+	}
+	return offset, computeLevel(offset, slot), nil
+}
+
 // saveStateByDiff takes a state and decides between saving a full state snapshot or a diff.
 func (s *Store) saveStateByDiff(ctx context.Context, st state.ReadOnlyBeaconState) error {
 	_, span := trace.StartSpan(ctx, "BeaconDB.saveStateByDiff")
@@ -33,13 +43,10 @@ func (s *Store) saveStateByDiff(ctx context.Context, st state.ReadOnlyBeaconStat
 	}
 
 	slot := st.Slot()
-	offset := s.getOffset()
-	if uint64(slot) < offset {
-		return ErrSlotBeforeOffset
+	offset, lvl, err := s.SlotInDiffTree(slot)
+	if err != nil {
+		return errors.Wrap(err, "could not determine if slot is in diff tree")
 	}
-
-	// Find the level to save the state.
-	lvl := computeLevel(offset, slot)
 	if lvl == -1 {
 		return nil
 	}

beacon-chain/db/kv/state_diff_helpers.go

@@ -14,6 +14,7 @@ import (
 	"github.com/OffchainLabs/prysm/v7/math"
 	ethpb "github.com/OffchainLabs/prysm/v7/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v7/runtime/version"
+	pkgerrors "github.com/pkg/errors"
 	"go.etcd.io/bbolt"
 )
 
@@ -119,6 +120,54 @@ func (s *Store) getOffset() uint64 {
 	return s.stateDiffCache.getOffset()
 }
 
+// hasStateDiffOffset checks if the state-diff offset has been set in the database.
+// This is used to detect if an existing database has state-diff enabled.
+func (s *Store) hasStateDiffOffset() (bool, error) {
+	var hasOffset bool
+	err := s.db.View(func(tx *bbolt.Tx) error {
+		bucket := tx.Bucket(stateDiffBucket)
+		if bucket == nil {
+			return nil
+		}
+		hasOffset = bucket.Get(offsetKey) != nil
+		return nil
+	})
+	return hasOffset, err
+}
+
+// initializeStateDiff sets up the state-diff schema for a new database.
+// This should be called during checkpoint sync or genesis sync.
+func (s *Store) initializeStateDiff(slot primitives.Slot, initialState state.ReadOnlyBeaconState) error {
+	// Write offset directly to the database (without using cache which doesn't exist yet).
+	err := s.db.Update(func(tx *bbolt.Tx) error {
+		bucket := tx.Bucket(stateDiffBucket)
+		if bucket == nil {
+			return bbolt.ErrBucketNotFound
+		}
+
+		offsetBytes := make([]byte, 8)
+		binary.LittleEndian.PutUint64(offsetBytes, uint64(slot))
+		return bucket.Put(offsetKey, offsetBytes)
+	})
+	if err != nil {
+		return pkgerrors.Wrap(err, "failed to set offset")
+	}
+
+	// Create the state diff cache (this will read the offset from the database).
+	sdCache, err := newStateDiffCache(s)
+	if err != nil {
+		return pkgerrors.Wrap(err, "failed to create state diff cache")
+	}
+	s.stateDiffCache = sdCache
+
+	// Save the initial state as a full snapshot.
+	if err := s.saveFullSnapshot(initialState); err != nil {
+		return pkgerrors.Wrap(err, "failed to save initial snapshot")
+	}
+
+	return nil
+}
+
 func keyForSnapshot(v int) ([]byte, error) {
 	switch v {
 	case version.Fulu:

beacon-chain/db/kv/testing_helpers.go

@@ -0,0 +1,35 @@
+package kv
+
+import (
+	"encoding/binary"
+
+	"go.etcd.io/bbolt"
+)
+
+// InitStateDiffCacheForTesting initializes the state diff cache with the given offset.
+// This is intended for testing purposes when setting up state diff after database creation.
+// This file is only compiled when the "testing" build tag is set.
+func (s *Store) InitStateDiffCacheForTesting(offset uint64) error {
+	// First, set the offset in the database.
+	err := s.db.Update(func(tx *bbolt.Tx) error {
+		bucket := tx.Bucket(stateDiffBucket)
+		if bucket == nil {
+			return bbolt.ErrBucketNotFound
+		}
+
+		offsetBytes := make([]byte, 8)
+		binary.LittleEndian.PutUint64(offsetBytes, offset)
+		return bucket.Put([]byte("offset"), offsetBytes)
+	})
+	if err != nil {
+		return err
+	}
+
+	// Then create the state diff cache.
+	sdCache, err := newStateDiffCache(s)
+	if err != nil {
+		return err
+	}
+	s.stateDiffCache = sdCache
+	return nil
+}

beacon-chain/db/kv/wss.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 
+	"github.com/OffchainLabs/prysm/v7/config/features"
 	"github.com/OffchainLabs/prysm/v7/config/params"
 	"github.com/OffchainLabs/prysm/v7/consensus-types/primitives"
 	"github.com/OffchainLabs/prysm/v7/encoding/ssz/detect"
@@ -111,5 +112,13 @@ func (s *Store) SaveOrigin(ctx context.Context, serState, serBlock []byte) error
 		return errors.Wrap(err, "save finalized checkpoint")
 	}
 
+	// Initialize state-diff if enabled and not yet initialized.
+	if features.Get().EnableStateDiff && s.stateDiffCache == nil {
+		if err := s.initializeStateDiff(state.Slot(), state); err != nil {
+			return errors.Wrap(err, "failed to initialize state diff")
+		}
+		log.WithField("slot", state.Slot()).Info("Initialized state-diff with checkpoint state")
+	}
+
 	return nil
 }

beacon-chain/execution/BUILD.bazel

@@ -40,7 +40,6 @@ go_library(
         "//beacon-chain/state/state-native:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
         "//beacon-chain/verification:go_default_library",
-        "//cmd/beacon-chain/flags:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",

beacon-chain/execution/engine_client.go

@@ -11,7 +11,6 @@ import (
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/peerdas"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/execution/types"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/verification"
-	"github.com/OffchainLabs/prysm/v7/cmd/beacon-chain/flags"
 	fieldparams "github.com/OffchainLabs/prysm/v7/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v7/config/params"
 	"github.com/OffchainLabs/prysm/v7/consensus-types/blocks"
@@ -539,10 +538,6 @@ func (s *Service) GetBlobsV2(ctx context.Context, versionedHashes []common.Hash)
 		return nil, errors.New(fmt.Sprintf("%s is not supported", GetBlobsV2))
 	}
 
-	if flags.Get().DisableGetBlobsV2 {
-		return []*pb.BlobAndProofV2{}, nil
-	}
-
 	result := make([]*pb.BlobAndProofV2, len(versionedHashes))
 	err := s.rpcClient.CallContext(ctx, &result, GetBlobsV2, versionedHashes)
 

beacon-chain/node/node.go

@@ -540,7 +540,12 @@ func openDB(ctx context.Context, dbPath string, clearer *dbClearer) (*kv.Store,
 	log.WithField("databasePath", dbPath).Info("Checking DB")
 
 	d, err := kv.NewKVStore(ctx, dbPath)
-	if err != nil {
+	if errors.Is(err, kv.ErrStateDiffIncompatible) {
+		log.WithError(err).Warn("Disabling state-diff feature")
+		cfg := features.Get()
+		cfg.EnableStateDiff = false
+		features.Init(cfg)
+	} else if err != nil {
 		return nil, errors.Wrapf(err, "could not create database at %s", dbPath)
 	}
 

beacon-chain/rpc/eth/beacon/handlers.go

@@ -14,6 +14,7 @@ import (
 	"github.com/OffchainLabs/prysm/v7/api"
 	"github.com/OffchainLabs/prysm/v7/api/server/structs"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/blockchain/kzg"
+	coreblocks "github.com/OffchainLabs/prysm/v7/beacon-chain/core/blocks"
 	corehelpers "github.com/OffchainLabs/prysm/v7/beacon-chain/core/helpers"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/transition"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/db/filters"
@@ -957,6 +958,13 @@ func (s *Server) validateConsensus(ctx context.Context, b *eth.GenericSignedBeac
 			}
 		}
 	}
+	blockRoot, err := blk.Block().HashTreeRoot()
+	if err != nil {
+		return errors.Wrap(err, "could not hash block")
+	}
+	if err := coreblocks.VerifyBlockSignatureUsingCurrentFork(parentState, blk, blockRoot); err != nil {
+		return errors.Wrap(err, "could not verify block signature")
+	}
 	_, err = transition.ExecuteStateTransition(ctx, parentState, blk)
 	if err != nil {
 		return errors.Wrap(err, "could not execute state transition")

beacon-chain/rpc/eth/config/handlers.go

@@ -40,6 +40,7 @@ func GetForkSchedule(w http.ResponseWriter, r *http.Request) {
 		httputil.WriteJson(w, &structs.GetForkScheduleResponse{
 			Data: data,
 		})
+		return
 	}
 	previous := schedule[0]
 	for _, entry := range schedule {

beacon-chain/state/stategen/BUILD.bazel

@@ -29,6 +29,7 @@ go_library(
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/sync/backfill/coverage:go_default_library",
         "//cache/lru:go_default_library",
+        "//config/features:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",
         "//consensus-types/interfaces:go_default_library",
@@ -68,11 +69,14 @@ go_test(
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/db:go_default_library",
+        "//beacon-chain/db/kv:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/state-native:go_default_library",
         "//beacon-chain/state/testing:go_default_library",
+        "//cmd/beacon-chain/flags:go_default_library",
+        "//config/features:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",
         "//consensus-types/blocks/testing:go_default_library",

beacon-chain/state/stategen/migrate.go

@@ -5,10 +5,13 @@ import (
 	"encoding/hex"
 	"fmt"
 
+	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/transition"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/state"
+	"github.com/OffchainLabs/prysm/v7/config/features"
 	"github.com/OffchainLabs/prysm/v7/consensus-types/primitives"
 	"github.com/OffchainLabs/prysm/v7/encoding/bytesutil"
 	"github.com/OffchainLabs/prysm/v7/monitoring/tracing/trace"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
@@ -25,6 +28,10 @@ func (s *State) MigrateToCold(ctx context.Context, fRoot [32]byte) error {
 	s.migrationLock.Lock()
 	defer s.migrationLock.Unlock()
 
+	if features.Get().EnableStateDiff {
+		return s.migrateToColdHdiff(ctx, fRoot)
+	}
+
 	s.finalizedInfo.lock.RLock()
 	oldFSlot := s.finalizedInfo.slot
 	s.finalizedInfo.lock.RUnlock()
@@ -90,21 +97,8 @@ func (s *State) MigrateToCold(ctx context.Context, fRoot [32]byte) error {
 				}
 			}
 		}
-
 		if s.beaconDB.HasState(ctx, aRoot) {
-			// If you are migrating a state and its already part of the hot state cache saved to the db,
-			// you can just remove it from the hot state cache as it becomes redundant.
-			s.saveHotStateDB.lock.Lock()
-			roots := s.saveHotStateDB.blockRootsOfSavedStates
-			for i := range roots {
-				if aRoot == roots[i] {
-					s.saveHotStateDB.blockRootsOfSavedStates = append(roots[:i], roots[i+1:]...)
-					// There shouldn't be duplicated roots in `blockRootsOfSavedStates`.
-					// Break here is ok.
-					break
-				}
-			}
-			s.saveHotStateDB.lock.Unlock()
+			s.migrateHotToCold(aRoot)
 			continue
 		}
 
@@ -129,3 +123,103 @@ func (s *State) MigrateToCold(ctx context.Context, fRoot [32]byte) error {
 
 	return nil
 }
+
+// migrateToColdHdiff saves the state-diffs for slots that are in the state diff tree after finalization
+func (s *State) migrateToColdHdiff(ctx context.Context, fRoot [32]byte) error {
+	s.finalizedInfo.lock.RLock()
+	oldFSlot := s.finalizedInfo.slot
+	s.finalizedInfo.lock.RUnlock()
+	fSlot, err := s.beaconDB.SlotByBlockRoot(ctx, fRoot)
+	if err != nil {
+		return errors.Wrap(err, "could not get slot by block root")
+	}
+	for slot := oldFSlot; slot < fSlot; slot++ {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		_, lvl, err := s.beaconDB.SlotInDiffTree(slot)
+		if err != nil {
+			log.WithError(err).Errorf("could not determine if slot %d is in diff tree", slot)
+			continue
+		}
+		if lvl == -1 {
+			continue
+		}
+		// The state needs to be saved.
+		// Try the epoch boundary cache first.
+		cached, exists, err := s.epochBoundaryStateCache.getBySlot(slot)
+		if err != nil {
+			log.WithError(err).Errorf("could not get epoch boundary state for slot %d", slot)
+			cached = nil
+			exists = false
+		}
+		var aRoot [32]byte
+		var aState state.BeaconState
+		if exists {
+			aRoot = cached.root
+			aState = cached.state
+		} else {
+			_, roots, err := s.beaconDB.HighestRootsBelowSlot(ctx, slot)
+			if err != nil {
+				return err
+			}
+			// Given the block has been finalized, the db should not have more than one block in a given slot.
+			// We should error out when this happens.
+			if len(roots) != 1 {
+				return errUnknownBlock
+			}
+			aRoot = roots[0]
+			// Different than the legacy MigrateToCold, we need to always get the state even if
+			// the state exists in DB as part of the hot state db, because we need to process slots
+			// to the state diff tree slots.
+			aState, err = s.StateByRoot(ctx, aRoot)
+			if err != nil {
+				return err
+			}
+		}
+		if s.beaconDB.HasState(ctx, aRoot) {
+			s.migrateHotToCold(aRoot)
+			continue
+		}
+		// advance slots to the target slot
+		if aState.Slot() < slot {
+			aState, err = transition.ProcessSlots(ctx, aState, slot)
+			if err != nil {
+				return errors.Wrapf(err, "could not process slots to slot %d", slot)
+			}
+		}
+		if err := s.beaconDB.SaveState(ctx, aState, aRoot); err != nil {
+			return err
+		}
+		log.WithFields(
+			logrus.Fields{
+				"slot": aState.Slot(),
+				"root": fmt.Sprintf("%#x", aRoot),
+			}).Info("Saved state in DB")
+	}
+	// Update finalized info in memory.
+	fInfo, ok, err := s.epochBoundaryStateCache.getByBlockRoot(fRoot)
+	if err != nil {
+		return err
+	}
+	if ok {
+		s.SaveFinalizedState(fSlot, fRoot, fInfo.state)
+	}
+	return nil
+}
+
+func (s *State) migrateHotToCold(aRoot [32]byte) {
+	// If you are migrating a state and its already part of the hot state cache saved to the db,
+	// you can just remove it from the hot state cache as it becomes redundant.
+	s.saveHotStateDB.lock.Lock()
+	roots := s.saveHotStateDB.blockRootsOfSavedStates
+	for i := range roots {
+		if aRoot == roots[i] {
+			s.saveHotStateDB.blockRootsOfSavedStates = append(roots[:i], roots[i+1:]...)
+			// There shouldn't be duplicated roots in `blockRootsOfSavedStates`.
+			// Break here is ok.
+			break
+		}
+	}
+	s.saveHotStateDB.lock.Unlock()
+}

beacon-chain/state/stategen/migrate_test.go

@@ -4,8 +4,11 @@ import (
 	"testing"
 
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/blocks"
+	"github.com/OffchainLabs/prysm/v7/beacon-chain/db/kv"
 	testDB "github.com/OffchainLabs/prysm/v7/beacon-chain/db/testing"
 	doublylinkedtree "github.com/OffchainLabs/prysm/v7/beacon-chain/forkchoice/doubly-linked-tree"
+	"github.com/OffchainLabs/prysm/v7/cmd/beacon-chain/flags"
+	"github.com/OffchainLabs/prysm/v7/config/features"
 	consensusblocks "github.com/OffchainLabs/prysm/v7/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v7/consensus-types/primitives"
 	ethpb "github.com/OffchainLabs/prysm/v7/proto/prysm/v1alpha1"
@@ -224,3 +227,170 @@ func TestMigrateToCold_ParallelCalls(t *testing.T) {
 	assert.DeepEqual(t, [][32]byte{r7}, service.saveHotStateDB.blockRootsOfSavedStates, "Did not remove all saved hot state roots")
 	require.LogsContain(t, hook, "Saved state in DB")
 }
+
+// =========================================================================
+// Tests for migrateToColdHdiff (state diff migration)
+// =========================================================================
+
+// setStateDiffExponents sets state diff exponents for testing.
+// Uses exponents [6, 5] which means:
+// - Level 0: Every 2^6 = 64 slots (full snapshot)
+// - Level 1: Every 2^5 = 32 slots (diff)
+func setStateDiffExponents() {
+	globalFlags := flags.GlobalFlags{
+		StateDiffExponents: []int{6, 5},
+	}
+	flags.Init(&globalFlags)
+}
+
+// TestMigrateToColdHdiff_CanUpdateFinalizedInfo verifies that the migration
+// correctly updates finalized info when migrating to slots not in the diff tree.
+func TestMigrateToColdHdiff_CanUpdateFinalizedInfo(t *testing.T) {
+	ctx := t.Context()
+	// Set exponents and create DB first (without EnableStateDiff flag).
+	setStateDiffExponents()
+	beaconDB := testDB.SetupDB(t)
+	// Initialize the state diff cache via the method on *kv.Store (not in interface).
+	require.NoError(t, beaconDB.(*kv.Store).InitStateDiffCacheForTesting(0))
+	// Now enable the feature flag.
+	resetCfg := features.InitWithReset(&features.Flags{EnableStateDiff: true})
+	defer resetCfg()
+	service := New(beaconDB, doublylinkedtree.New())
+
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
+	genesisStateRoot, err := beaconState.HashTreeRoot(ctx)
+	require.NoError(t, err)
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	util.SaveBlock(t, ctx, beaconDB, genesis)
+	gRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, gRoot))
+
+	// Put genesis state in epoch boundary cache so migrateToColdHdiff doesn't need to retrieve from DB.
+	require.NoError(t, service.epochBoundaryStateCache.put(gRoot, beaconState))
+
+	// Set initial finalized info at genesis.
+	service.finalizedInfo = &finalizedInfo{
+		slot:  0,
+		root:  gRoot,
+		state: beaconState,
+	}
+
+	// Create finalized block at slot 10 (not in diff tree, so no intermediate states saved).
+	finalizedState := beaconState.Copy()
+	require.NoError(t, finalizedState.SetSlot(10))
+	b := util.NewBeaconBlock()
+	b.Block.Slot = 10
+	fRoot, err := b.Block.HashTreeRoot()
+	require.NoError(t, err)
+	util.SaveBlock(t, ctx, beaconDB, b)
+	require.NoError(t, service.epochBoundaryStateCache.put(fRoot, finalizedState))
+
+	require.NoError(t, service.MigrateToCold(ctx, fRoot))
+
+	// Verify finalized info is updated.
+	assert.Equal(t, primitives.Slot(10), service.finalizedInfo.slot)
+	assert.DeepEqual(t, fRoot, service.finalizedInfo.root)
+	expectedHTR, err := finalizedState.HashTreeRoot(ctx)
+	require.NoError(t, err)
+	actualHTR, err := service.finalizedInfo.state.HashTreeRoot(ctx)
+	require.NoError(t, err)
+	assert.DeepEqual(t, expectedHTR, actualHTR)
+}
+
+// TestMigrateToColdHdiff_SkipsSlotsNotInDiffTree verifies that the migration
+// skips slots that are not in the diff tree.
+func TestMigrateToColdHdiff_SkipsSlotsNotInDiffTree(t *testing.T) {
+	hook := logTest.NewGlobal()
+	ctx := t.Context()
+	// Set exponents and create DB first (without EnableStateDiff flag).
+	setStateDiffExponents()
+	beaconDB := testDB.SetupDB(t)
+	// Initialize the state diff cache via the method on *kv.Store (not in interface).
+	require.NoError(t, beaconDB.(*kv.Store).InitStateDiffCacheForTesting(0))
+	// Now enable the feature flag.
+	resetCfg := features.InitWithReset(&features.Flags{EnableStateDiff: true})
+	defer resetCfg()
+	service := New(beaconDB, doublylinkedtree.New())
+
+	beaconState, pks := util.DeterministicGenesisState(t, 32)
+	genesisStateRoot, err := beaconState.HashTreeRoot(ctx)
+	require.NoError(t, err)
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	util.SaveBlock(t, ctx, beaconDB, genesis)
+	gRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, gRoot))
+
+	// Start from slot 1 to avoid slot 0 which is in the diff tree.
+	service.finalizedInfo = &finalizedInfo{
+		slot:  1,
+		root:  gRoot,
+		state: beaconState,
+	}
+
+	// Reset the log hook to ignore setup logs.
+	hook.Reset()
+
+	// Create a block at slot 20 (NOT in diff tree with exponents [6,5]).
+	b20, err := util.GenerateFullBlock(beaconState, pks, util.DefaultBlockGenConfig(), 20)
+	require.NoError(t, err)
+	r20, err := b20.Block.HashTreeRoot()
+	require.NoError(t, err)
+	util.SaveBlock(t, ctx, beaconDB, b20)
+	require.NoError(t, beaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Slot: 20, Root: r20[:]}))
+
+	// Put finalized state in cache.
+	finalizedState := beaconState.Copy()
+	require.NoError(t, finalizedState.SetSlot(20))
+	require.NoError(t, service.epochBoundaryStateCache.put(r20, finalizedState))
+
+	require.NoError(t, service.MigrateToCold(ctx, r20))
+
+	// Verify NO states were saved during migration (slots 1-19 are not in diff tree).
+	assert.LogsDoNotContain(t, hook, "Saved state in DB")
+}
+
+// TestMigrateToColdHdiff_NoOpWhenFinalizedSlotNotAdvanced verifies that
+// migration is a no-op when the finalized slot has not advanced.
+func TestMigrateToColdHdiff_NoOpWhenFinalizedSlotNotAdvanced(t *testing.T) {
+	ctx := t.Context()
+	// Set exponents and create DB first (without EnableStateDiff flag).
+	setStateDiffExponents()
+	beaconDB := testDB.SetupDB(t)
+	// Initialize the state diff cache via the method on *kv.Store (not in interface).
+	require.NoError(t, beaconDB.(*kv.Store).InitStateDiffCacheForTesting(0))
+	// Now enable the feature flag.
+	resetCfg := features.InitWithReset(&features.Flags{EnableStateDiff: true})
+	defer resetCfg()
+	service := New(beaconDB, doublylinkedtree.New())
+
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
+	genesisStateRoot, err := beaconState.HashTreeRoot(ctx)
+	require.NoError(t, err)
+	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
+	util.SaveBlock(t, ctx, beaconDB, genesis)
+	gRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, gRoot))
+
+	// Set finalized info already at slot 50.
+	finalizedState := beaconState.Copy()
+	require.NoError(t, finalizedState.SetSlot(50))
+	service.finalizedInfo = &finalizedInfo{
+		slot:  50,
+		root:  gRoot,
+		state: finalizedState,
+	}
+
+	// Create block at same slot 50.
+	b := util.NewBeaconBlock()
+	b.Block.Slot = 50
+	fRoot, err := b.Block.HashTreeRoot()
+	require.NoError(t, err)
+	util.SaveBlock(t, ctx, beaconDB, b)
+	require.NoError(t, service.epochBoundaryStateCache.put(fRoot, finalizedState))
+
+	// Migration should be a no-op (finalized slot not advancing).
+	require.NoError(t, service.MigrateToCold(ctx, fRoot))
+}

beacon-chain/sync/subscriber_beacon_blocks.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"os"
 	"path"
-	"sync"
 	"time"
 
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/blockchain"
@@ -49,15 +48,7 @@ func (s *Service) beaconBlockSubscriber(ctx context.Context, msg proto.Message)
 		return errors.Wrap(err, "new ro block with root")
 	}
 
-	var wg sync.WaitGroup
-	wg.Go(func() {
-		if err := s.processSidecarsFromExecutionFromBlock(ctx, roBlock); err != nil {
-			log.WithError(err).WithFields(logrus.Fields{
-				"root": fmt.Sprintf("%#x", root),
-				"slot": block.Slot(),
-			}).Error("Failed to process sidecars from execution from block")
-		}
-	})
+	go s.processSidecarsFromExecutionFromBlock(ctx, roBlock)
 
 	if err := s.cfg.chain.ReceiveBlock(ctx, signed, root, nil); err != nil {
 		if blockchain.IsInvalidBlock(err) {
@@ -78,33 +69,28 @@ func (s *Service) beaconBlockSubscriber(ctx context.Context, msg proto.Message)
 		}
 		return err
 	}
-
 	if err := s.processPendingAttsForBlock(ctx, root); err != nil {
 		return errors.Wrap(err, "process pending atts for block")
 	}
-
-	wg.Wait()
-
 	return nil
 }
 
 // processSidecarsFromExecutionFromBlock retrieves (if available) sidecars data from the execution client,
 // builds corresponding sidecars, save them to the storage, and broadcasts them over P2P if necessary.
-func (s *Service) processSidecarsFromExecutionFromBlock(ctx context.Context, roBlock blocks.ROBlock) error {
+func (s *Service) processSidecarsFromExecutionFromBlock(ctx context.Context, roBlock blocks.ROBlock) {
 	if roBlock.Version() >= version.Fulu {
 		if err := s.processDataColumnSidecarsFromExecution(ctx, peerdas.PopulateFromBlock(roBlock)); err != nil {
-			return errors.Wrap(err, "process data column sidecars from execution")
+			log.WithError(err).Error("Failed to process data column sidecars from execution")
+			return
 		}
 
-		return nil
+		return
 	}
 
 	if roBlock.Version() >= version.Deneb {
 		s.processBlobSidecarsFromExecution(ctx, roBlock)
-		return nil
+		return
 	}
-
-	return nil
 }
 
 // processBlobSidecarsFromExecution retrieves (if available) blob sidecars data from the execution client,
@@ -182,6 +168,7 @@ func (s *Service) processDataColumnSidecarsFromExecution(ctx context.Context, so
 	key := fmt.Sprintf("%#x", source.Root())
 	if _, err, _ := s.columnSidecarsExecSingleFlight.Do(key, func() (any, error) {
 		const delay = 250 * time.Millisecond
+		secondsPerHalfSlot := time.Duration(params.BeaconConfig().SecondsPerSlot/2) * time.Second
 
 		commitments, err := source.Commitments()
 		if err != nil {
@@ -199,6 +186,9 @@ func (s *Service) processDataColumnSidecarsFromExecution(ctx context.Context, so
 			return nil, errors.Wrap(err, "column indices to sample")
 		}
 
+		ctx, cancel := context.WithTimeout(ctx, secondsPerHalfSlot)
+		defer cancel()
+
 		log := log.WithFields(logrus.Fields{
 			"root":          fmt.Sprintf("%#x", source.Root()),
 			"slot":          source.Slot(),
@@ -219,11 +209,6 @@ func (s *Service) processDataColumnSidecarsFromExecution(ctx context.Context, so
 				return nil, nil
 			}
 
-			// Return if the context is done.
-			if ctx.Err() != nil {
-				return nil, ctx.Err()
-			}
-
 			if iteration == 0 {
 				dataColumnsRecoveredFromELAttempts.Inc()
 			}
@@ -235,10 +220,20 @@ func (s *Service) processDataColumnSidecarsFromExecution(ctx context.Context, so
 			}
 
 			// No sidecars are retrieved from the EL, retry later
-			constructedCount := uint64(len(constructedSidecars))
+			constructedSidecarCount = uint64(len(constructedSidecars))
+			if constructedSidecarCount == 0 {
+				if ctx.Err() != nil {
+					return nil, ctx.Err()
+				}
+
+				time.Sleep(delay)
+				continue
+			}
+
+			dataColumnsRecoveredFromELTotal.Inc()
 
 			// Boundary check.
-			if constructedSidecarCount > 0 && constructedSidecarCount != fieldparams.NumberOfColumns {
+			if constructedSidecarCount != fieldparams.NumberOfColumns {
 				return nil, errors.Errorf("reconstruct data column sidecars returned %d sidecars, expected %d - should never happen", constructedSidecarCount, fieldparams.NumberOfColumns)
 			}
 
@@ -247,24 +242,14 @@ func (s *Service) processDataColumnSidecarsFromExecution(ctx context.Context, so
 				return nil, errors.Wrap(err, "broadcast and receive unseen data column sidecars")
 			}
 
-			if constructedCount > 0 {
-				dataColumnsRecoveredFromELTotal.Inc()
+			log.WithFields(logrus.Fields{
+				"count":   len(unseenIndices),
+				"indices": helpers.SortedPrettySliceFromMap(unseenIndices),
+			}).Debug("Constructed data column sidecars from the execution client")
 
-				log.WithFields(logrus.Fields{
-					"root":          fmt.Sprintf("%#x", source.Root()),
-					"slot":          source.Slot(),
-					"proposerIndex": source.ProposerIndex(),
-					"iteration":     iteration,
-					"type":          source.Type(),
-					"count":         len(unseenIndices),
-					"indices":       helpers.SortedPrettySliceFromMap(unseenIndices),
-				}).Debug("Constructed data column sidecars from the execution client")
+			dataColumnSidecarsObtainedViaELCount.Observe(float64(len(unseenIndices)))
 
-				return nil, nil
-			}
-
-			// Wait before retrying.
-			time.Sleep(delay)
+			return nil, nil
 		}
 	}); err != nil {
 		return err
@@ -299,11 +284,6 @@ func (s *Service) broadcastAndReceiveUnseenDataColumnSidecars(
 		unseenIndices[sidecar.Index] = true
 	}
 
-	// Exit early if there are no nothing to broadcast or receive.
-	if len(unseenSidecars) == 0 {
-		return nil, nil
-	}
-
 	// Broadcast all the data column sidecars we reconstructed but did not see via gossip (non blocking).
 	if err := s.cfg.p2p.BroadcastDataColumnSidecars(ctx, unseenSidecars); err != nil {
 		return nil, errors.Wrap(err, "broadcast data column sidecars")

beacon-chain/sync/subscriber_beacon_blocks_test.go

@@ -194,8 +194,7 @@ func TestProcessSidecarsFromExecutionFromBlock(t *testing.T) {
 					},
 					seenBlobCache: lruwrpr.New(1),
 				}
-				err := s.processSidecarsFromExecutionFromBlock(t.Context(), roBlock)
-				require.NoError(t, err)
+				s.processSidecarsFromExecutionFromBlock(t.Context(), roBlock)
 				require.Equal(t, tt.expectedBlobCount, len(chainService.Blobs))
 			})
 		}
@@ -294,8 +293,7 @@ func TestProcessSidecarsFromExecutionFromBlock(t *testing.T) {
 				roBlock, err := blocks.NewROBlock(sb)
 				require.NoError(t, err)
 
-				err = s.processSidecarsFromExecutionFromBlock(t.Context(), roBlock)
-				require.NoError(t, err)
+				s.processSidecarsFromExecutionFromBlock(t.Context(), roBlock)
 				require.Equal(t, tt.expectedDataColumnCount, len(chainService.DataColumns))
 			})
 		}

beacon-chain/sync/subscriber_data_column_sidecar.go

@@ -25,12 +25,12 @@ func (s *Service) dataColumnSubscriber(ctx context.Context, msg proto.Message) e
 	}
 
 	if err := s.receiveDataColumnSidecar(ctx, sidecar); err != nil {
-		return wrapDataColumnError(sidecar, "receive data column sidecar", err)
+		return errors.Wrap(err, "receive data column sidecar")
 	}
 
 	wg.Go(func() error {
 		if err := s.processDataColumnSidecarsFromReconstruction(ctx, sidecar); err != nil {
-			return wrapDataColumnError(sidecar, "process data column sidecars from reconstruction", err)
+			return errors.Wrap(err, "process data column sidecars from reconstruction")
 		}
 
 		return nil
@@ -38,7 +38,7 @@ func (s *Service) dataColumnSubscriber(ctx context.Context, msg proto.Message) e
 
 	wg.Go(func() error {
 		if err := s.processDataColumnSidecarsFromExecution(ctx, peerdas.PopulateFromSidecar(sidecar)); err != nil {
-			return wrapDataColumnError(sidecar, "process data column sidecars from execution", err)
+			return errors.Wrap(err, "process data column sidecars from execution")
 		}
 
 		return nil
@@ -110,7 +110,3 @@ func (s *Service) allDataColumnSubnets(_ primitives.Slot) map[uint64]bool {
 
 	return allSubnets
 }
-
-func wrapDataColumnError(sidecar blocks.VerifiedRODataColumn, message string, err error) error {
-	return fmt.Errorf("%s - slot %d, root %s: %w", message, sidecar.SignedBlockHeader.Header.Slot, fmt.Sprintf("%#x", sidecar.BlockRoot()), err)
-}

changelog/builder-index.md

@@ -0,0 +1,3 @@
+### Added
+
+- `primitives.BuilderIndex`: SSZ `uint64` wrapper for builder registry indices.

changelog/kasey_fix-backfill-flag.md

@@ -0,0 +1,2 @@
+#### Fixed
+- Fix validation logic for `--backfill-oldest-slot`, which was rejecting slots newer than 1056767.

changelog/manu_disable_get_blobs_v2.md

@@ -1,2 +0,0 @@
-### Added
-- `--disable-get-blobs-v2` flag.

changelog/potuz_hdiff_migrate_to_cold.md

@@ -0,0 +1,3 @@
+### Added
+
+- Migrate to cold with the hdiff feature. 

changelog/potuz_next_epoch_attributes.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- Do not process slots and copy states for next epoch proposers after Fulu

changelog/potuz_no_fcu_on_batches.md

@@ -0,0 +1,2 @@
+### Ignored
+- D  not send FCU on block batches. 

changelog/potuz_remove_signature_check.md

@@ -0,0 +1,3 @@
+### Changed
+
+- Do not check block signature on state transition. 

changelog/potuz_use_head_previous_epoch.md

@@ -0,0 +1,3 @@
+### Added
+
+- Use the head state to validate attestations for the previous epoch if head is compatible with the target checkpoint.

changelog/radek_extend-http-analyzer.md

@@ -0,0 +1,3 @@
+### Changed
+
+- Extend `httperror` analyzer to more functions.

changelog/sashass1315_fix-panic.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- avoid panic when fork schedule is empty [#16175](https://github.com/OffchainLabs/prysm/pull/16175)

changelog/satushh-consolidation.md

@@ -0,0 +1,3 @@
+### Changed
+
+- Performance improvement in ProcessConsolidationRequests: Use more performance HasPendingBalanceToWithdraw instead of PendingBalanceToWithdraw as no need to calculate full total pending balance. 

cmd/beacon-chain/flags/base.go

@@ -356,9 +356,4 @@ var (
 		Usage: "A comma-separated list of exponents (of 2) in decreasing order, defining the state diff hierarchy levels. The last exponent must be greater than or equal to 5.",
 		Value: cli.NewIntSlice(21, 18, 16, 13, 11, 9, 5),
 	}
-	// DisableGetBlobsV2 disables the engine_getBlobsV2 usage.
-	DisableGetBlobsV2 = &cli.BoolFlag{
-		Name:  "disable-get-blobs-v2",
-		Usage: "Disables the engine_getBlobsV2 usage.",
-	}
 )

cmd/beacon-chain/flags/config.go

@@ -17,7 +17,6 @@ type GlobalFlags struct {
 	SubscribeToAllSubnets           bool
 	Supernode                       bool
 	SemiSupernode                   bool
-	DisableGetBlobsV2               bool
 	MinimumSyncPeers                int
 	MinimumPeersPerSubnet           int
 	MaxConcurrentDials              int
@@ -73,11 +72,6 @@ func ConfigureGlobalFlags(ctx *cli.Context) error {
 		cfg.SemiSupernode = true
 	}
 
-	if ctx.Bool(DisableGetBlobsV2.Name) {
-		log.Warning("Disabling `engine_getBlobsV2` API")
-		cfg.DisableGetBlobsV2 = true
-	}
-
 	// State-diff-exponents
 	cfg.StateDiffExponents = ctx.IntSlice(StateDiffExponents.Name)
 	if features.Get().EnableStateDiff {

cmd/beacon-chain/main.go

@@ -147,7 +147,6 @@ var appFlags = []cli.Flag{
 	flags.SlasherDirFlag,
 	flags.SlasherFlag,
 	flags.JwtId,
-	flags.DisableGetBlobsV2,
 	storage.BlobStoragePathFlag,
 	storage.DataColumnStoragePathFlag,
 	storage.BlobStorageLayout,
@@ -157,6 +156,7 @@ var appFlags = []cli.Flag{
 	dasFlags.BackfillOldestSlot,
 	dasFlags.BlobRetentionEpochFlag,
 	flags.BatchVerifierLimit,
+	flags.StateDiffExponents,
 }
 
 func init() {

cmd/beacon-chain/usage.go

@@ -74,6 +74,7 @@ var appHelpFlagGroups = []flagGroup{
 			flags.RPCHost,
 			flags.RPCPort,
 			flags.BatchVerifierLimit,
+			flags.StateDiffExponents,
 		},
 	},
 	{
@@ -169,7 +170,6 @@ var appHelpFlagGroups = []flagGroup{
 			flags.ExecutionJWTSecretFlag,
 			flags.JwtId,
 			flags.InteropMockEth1DataVotesFlag,
-			flags.DisableGetBlobsV2,
 		},
 	},
 	{ // Flags relevant to configuring beacon chain monitoring.

config/features/flags.go

@@ -270,6 +270,7 @@ var BeaconChainFlags = combinedFlags([]cli.Flag{
 	DisableQUIC,
 	EnableDiscoveryReboot,
 	enableExperimentalAttestationPool,
+	EnableStateDiff,
 	forceHeadFlag,
 	blacklistRoots,
 }, deprecatedBeaconFlags, deprecatedFlags, upcomingDeprecation)

consensus-types/primitives/BUILD.bazel

@@ -4,6 +4,7 @@ go_library(
     name = "go_default_library",
     srcs = [
         "basis_points.go",
+        "builder_index.go",
         "committee_bits_mainnet.go",
         "committee_bits_minimal.go",  # keep
         "committee_index.go",
@@ -31,6 +32,7 @@ go_library(
 go_test(
     name = "go_default_test",
     srcs = [
+        "builder_index_test.go",
         "committee_index_test.go",
         "domain_test.go",
         "epoch_test.go",

consensus-types/primitives/builder_index.go

@@ -0,0 +1,54 @@
+package primitives
+
+import (
+	"fmt"
+
+	fssz "github.com/prysmaticlabs/fastssz"
+)
+
+var _ fssz.HashRoot = (BuilderIndex)(0)
+var _ fssz.Marshaler = (*BuilderIndex)(nil)
+var _ fssz.Unmarshaler = (*BuilderIndex)(nil)
+
+// BuilderIndex is an index into the builder registry.
+type BuilderIndex uint64
+
+// HashTreeRoot returns the SSZ hash tree root of the index.
+func (b BuilderIndex) HashTreeRoot() ([32]byte, error) {
+	return fssz.HashWithDefaultHasher(b)
+}
+
+// HashTreeRootWith appends the SSZ uint64 representation of the index to the given hasher.
+func (b BuilderIndex) HashTreeRootWith(hh *fssz.Hasher) error {
+	hh.PutUint64(uint64(b))
+	return nil
+}
+
+// UnmarshalSSZ decodes the SSZ-encoded uint64 index from buf.
+func (b *BuilderIndex) UnmarshalSSZ(buf []byte) error {
+	if len(buf) != b.SizeSSZ() {
+		return fmt.Errorf("expected buffer of length %d received %d", b.SizeSSZ(), len(buf))
+	}
+	*b = BuilderIndex(fssz.UnmarshallUint64(buf))
+	return nil
+}
+
+// MarshalSSZTo appends the SSZ-encoded index to dst and returns the extended buffer.
+func (b *BuilderIndex) MarshalSSZTo(dst []byte) ([]byte, error) {
+	marshalled, err := b.MarshalSSZ()
+	if err != nil {
+		return nil, err
+	}
+	return append(dst, marshalled...), nil
+}
+
+// MarshalSSZ encodes the index as an SSZ uint64.
+func (b *BuilderIndex) MarshalSSZ() ([]byte, error) {
+	marshalled := fssz.MarshalUint64([]byte{}, uint64(*b))
+	return marshalled, nil
+}
+
+// SizeSSZ returns the size of the SSZ-encoded index in bytes.
+func (b *BuilderIndex) SizeSSZ() int {
+	return 8
+}

consensus-types/primitives/builder_index_test.go

@@ -0,0 +1,86 @@
+package primitives_test
+
+import (
+	"encoding/binary"
+	"slices"
+	"strconv"
+	"testing"
+
+	"github.com/OffchainLabs/prysm/v7/consensus-types/primitives"
+	"github.com/OffchainLabs/prysm/v7/testing/require"
+)
+
+func TestBuilderIndex_SSZRoundTripAndHashRoot(t *testing.T) {
+	cases := []uint64{
+		0,
+		1,
+		42,
+		(1 << 32) - 1,
+		1 << 32,
+		^uint64(0),
+	}
+
+	for _, v := range cases {
+		t.Run("v="+u64name(v), func(t *testing.T) {
+			t.Parallel()
+
+			val := primitives.BuilderIndex(v)
+			require.Equal(t, 8, (&val).SizeSSZ())
+
+			enc, err := (&val).MarshalSSZ()
+			require.NoError(t, err)
+			require.Equal(t, 8, len(enc))
+
+			wantEnc := make([]byte, 8)
+			binary.LittleEndian.PutUint64(wantEnc, v)
+			require.DeepEqual(t, wantEnc, enc)
+
+			dstPrefix := []byte("prefix:")
+			dst, err := (&val).MarshalSSZTo(slices.Clone(dstPrefix))
+			require.NoError(t, err)
+			wantDst := append(dstPrefix, wantEnc...)
+			require.DeepEqual(t, wantDst, dst)
+
+			var decoded primitives.BuilderIndex
+			require.NoError(t, (&decoded).UnmarshalSSZ(enc))
+			require.Equal(t, val, decoded)
+
+			root, err := val.HashTreeRoot()
+			require.NoError(t, err)
+
+			var wantRoot [32]byte
+			binary.LittleEndian.PutUint64(wantRoot[:8], v)
+			require.Equal(t, wantRoot, root)
+		})
+	}
+}
+
+func TestBuilderIndex_UnmarshalSSZRejectsWrongSize(t *testing.T) {
+	for _, size := range []int{7, 9} {
+		t.Run("size="+strconv.Itoa(size), func(t *testing.T) {
+			t.Parallel()
+			var v primitives.BuilderIndex
+			err := (&v).UnmarshalSSZ(make([]byte, size))
+			require.ErrorContains(t, "expected buffer of length 8", err)
+		})
+	}
+}
+
+func u64name(v uint64) string {
+	switch v {
+	case 0:
+		return "0"
+	case 1:
+		return "1"
+	case 42:
+		return "42"
+	case (1 << 32) - 1:
+		return "2^32-1"
+	case 1 << 32:
+		return "2^32"
+	case ^uint64(0):
+		return "max"
+	default:
+		return "custom"
+	}
+}

network/httputil/writer.go

@@ -43,6 +43,7 @@ func WriteJson(w http.ResponseWriter, v any) {
 func WriteSsz(w http.ResponseWriter, respSsz []byte) {
 	w.Header().Set("Content-Length", strconv.Itoa(len(respSsz)))
 	w.Header().Set("Content-Type", api.OctetStreamMediaType)
+	w.WriteHeader(http.StatusOK)
 	if _, err := io.Copy(w, io.NopCloser(bytes.NewReader(respSsz))); err != nil {
 		log.WithError(err).Error("Could not write response message")
 	}

testing/endtoend/BUILD.bazel

@@ -95,6 +95,7 @@ go_test(
         "endtoend_setup_test.go",
         "endtoend_test.go",
         "minimal_e2e_test.go",
+        "minimal_hdiff_e2e_test.go",
         "minimal_slashing_e2e_test.go",
         "slasher_simulator_e2e_test.go",
     ],

testing/endtoend/minimal_hdiff_e2e_test.go

@@ -0,0 +1,16 @@
+package endtoend
+
+import (
+	"testing"
+
+	"github.com/OffchainLabs/prysm/v7/config/params"
+	"github.com/OffchainLabs/prysm/v7/runtime/version"
+	"github.com/OffchainLabs/prysm/v7/testing/endtoend/types"
+)
+
+func TestEndToEnd_MinimalConfig_WithStateDiff(t *testing.T) {
+	r := e2eMinimal(t, types.InitForkCfg(version.Bellatrix, version.Electra, params.E2ETestConfig()),
+		types.WithStateDiff(),
+	)
+	r.run()
+}

testing/endtoend/types/types.go

@@ -67,6 +67,15 @@ func WithSSZOnly() E2EConfigOpt {
 	}
 }
 
+func WithStateDiff() E2EConfigOpt {
+	return func(cfg *E2EConfig) {
+		cfg.BeaconFlags = append(cfg.BeaconFlags,
+			"--enable-state-diff",
+			"--state-diff-exponents=6,5", // Small exponents for quick testing
+		)
+	}
+}
+
 // E2EConfig defines the struct for all configurations needed for E2E testing.
 type E2EConfig struct {
 	TestCheckpointSync      bool

tools/analyzers/httpwriter/BUILD.bazel

@@ -3,7 +3,7 @@ load("@prysm//tools/go:def.bzl", "go_library")
 go_library(
     name = "go_default_library",
     srcs = ["analyzer.go"],
-    importpath = "github.com/OffchainLabs/prysm/v7/tools/analyzers/httperror",
+    importpath = "github.com/OffchainLabs/prysm/v7/tools/analyzers/httpwriter",
     visibility = ["//visibility:public"],
     deps = [
         "@org_golang_x_tools//go/analysis:go_default_library",

tools/analyzers/httpwriter/analyzer.go

@@ -1,4 +1,4 @@
-package httperror
+package httpwriter
 
 import (
 	"go/ast"
@@ -9,8 +9,8 @@ import (
 )
 
 var Analyzer = &analysis.Analyzer{
-	Name: "httperror",
-	Doc:  "Ensures calls to httputil.HandleError are immediately followed by a return statement.",
+	Name: "httpwriter",
+	Doc:  "Ensures that httputil functions which make use of the writer are immediately followed by a return statement.",
 	Requires: []*analysis.Analyzer{
 		inspect.Analyzer,
 	},
@@ -99,7 +99,7 @@ func checkBlock(pass *analysis.Pass, fn *ast.FuncDecl, block *ast.BlockStmt, nex
 
 		// Now check the current statement itself: is it (or does it contain) a direct call to httputil.HandleError?
 		// We only consider ExprStmt that are direct CallExpr to httputil.HandleError.
-		call := findHandleErrorCall(stmt)
+		call, name := findHandleErrorCall(stmt)
 		if call == nil {
 			continue
 		}
@@ -121,7 +121,7 @@ func checkBlock(pass *analysis.Pass, fn *ast.FuncDecl, block *ast.BlockStmt, nex
 				continue
 			}
 			// otherwise it's not a return (even if it's an if/for etc) -> violation
-			pass.Reportf(stmt.Pos(), "call to httputil.HandleError must be immediately followed by a return statement")
+			pass.Reportf(stmt.Pos(), "call to httputil.%s must be immediately followed by a return statement", name)
 			continue
 		}
 
@@ -133,31 +133,33 @@ func checkBlock(pass *analysis.Pass, fn *ast.FuncDecl, block *ast.BlockStmt, nex
 		}
 
 		// Non-void function and it's the last statement → violation
-		pass.Reportf(stmt.Pos(), "call to httputil.HandleError must be followed by return because function has return values")
+		pass.Reportf(stmt.Pos(), "call to httputil.%s must be immediately followed by a return statement", name)
 	}
 }
 
 // findHandleErrorCall returns the call expression if stmt is a direct call to httputil.HandleError(...),
 // otherwise nil. We only match direct ExprStmt -> CallExpr -> SelectorExpr where selector is httputil.HandleError.
-func findHandleErrorCall(stmt ast.Stmt) *ast.CallExpr {
+func findHandleErrorCall(stmt ast.Stmt) (*ast.CallExpr, string) {
 	es, ok := stmt.(*ast.ExprStmt)
 	if !ok {
-		return nil
+		return nil, ""
 	}
 	call, ok := es.X.(*ast.CallExpr)
 	if !ok {
-		return nil
+		return nil, ""
 	}
 	sel, ok := call.Fun.(*ast.SelectorExpr)
 	if !ok {
-		return nil
+		return nil, ""
 	}
 	pkgIdent, ok := sel.X.(*ast.Ident)
 	if !ok {
-		return nil
+		return nil, ""
 	}
-	if pkgIdent.Name == "httputil" && sel.Sel.Name == "HandleError" {
-		return call
+	selectorName := sel.Sel.Name
+	if pkgIdent.Name == "httputil" &&
+		(selectorName == "HandleError" || selectorName == "WriteError" || selectorName == "WriteJson" || selectorName == "WriteSSZ") {
+		return call, selectorName
 	}
-	return nil
+	return nil, ""
 }