test fixes and style fix[1]

[1] https://go.dev/blog/package-names

api/server/structs/endpoints_beacon.go

@@ -290,3 +290,9 @@ type GetProposerLookaheadResponse struct {
 	Finalized           bool     `json:"finalized"`
 	Data                []string `json:"data"` // validator indexes
 }
+
+type GetBlobsResponse struct {
+	ExecutionOptimistic bool     `json:"execution_optimistic"`
+	Finalized           bool     `json:"finalized"`
+	Data                []string `json:"data"` //blobs
+}

beacon-chain/blockchain/BUILD.bazel

@@ -27,7 +27,7 @@ go_library(
         "receive_block.go",
         "receive_data_column.go",
         "service.go",
-        "setup_forchoice.go",
+        "setup_forkchoice.go",
         "tracked_proposer.go",
         "weak_subjectivity_checks.go",
     ],
@@ -50,7 +50,6 @@ go_library(
         "//beacon-chain/core/feed:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
-        "//beacon-chain/core/light-client:go_default_library",
         "//beacon-chain/core/peerdas:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
         "//beacon-chain/core/time:go_default_library",
@@ -63,6 +62,7 @@ go_library(
         "//beacon-chain/forkchoice:go_default_library",
         "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
         "//beacon-chain/forkchoice/types:go_default_library",
+        "//beacon-chain/light-client:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/blstoexec:go_default_library",
         "//beacon-chain/operations/slashings:go_default_library",
@@ -148,7 +148,6 @@ go_test(
         "//beacon-chain/core/blocks:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
-        "//beacon-chain/core/light-client:go_default_library",
         "//beacon-chain/core/peerdas:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
         "//beacon-chain/core/transition:go_default_library",
@@ -161,6 +160,7 @@ go_test(
         "//beacon-chain/forkchoice:go_default_library",
         "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
         "//beacon-chain/forkchoice/types:go_default_library",
+        "//beacon-chain/light-client:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/attestations/kv:go_default_library",
         "//beacon-chain/operations/blstoexec:go_default_library",

beacon-chain/blockchain/kzg/kzg.go

@@ -14,7 +14,10 @@ const BytesPerBlob = ckzg4844.BytesPerBlob
 type Blob [BytesPerBlob]byte
 
 // BytesPerCell is the number of bytes in a single cell.
-const BytesPerCell = ckzg4844.BytesPerCell
+const (
+	BytesPerCell  = ckzg4844.BytesPerCell
+	BytesPerProof = ckzg4844.BytesPerProof
+)
 
 // Cell represents a chunk of an encoded Blob.
 type Cell [BytesPerCell]byte
@@ -23,7 +26,7 @@ type Cell [BytesPerCell]byte
 type Commitment [48]byte
 
 // Proof represents a KZG proof that attests to the validity of a Blob or parts of it.
-type Proof [48]byte
+type Proof [BytesPerProof]byte
 
 // Bytes48 is a 48-byte array.
 type Bytes48 = ckzg4844.Bytes48

beacon-chain/blockchain/options.go

@@ -6,11 +6,11 @@ import (
 	"github.com/OffchainLabs/prysm/v6/async/event"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
-	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/execution"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice"
+	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/blstoexec"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/slashings"
@@ -35,7 +35,7 @@ func WithMaxGoroutines(x int) Option {
 // WithLCStore for light client store access.
 func WithLCStore() Option {
 	return func(s *Service) error {
-		s.lcStore = lightclient.NewLightClientStore(s.cfg.BeaconDB, s.cfg.P2P, s.cfg.StateNotifier.StateFeed())
+		s.lcStore = lightclient.NewLightClientStore(s.cfg.P2P, s.cfg.StateNotifier.StateFeed(), s.cfg.BeaconDB)
 		return nil
 	}
 }

beacon-chain/blockchain/process_block.go

@@ -247,7 +247,7 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []consensusblocks.ROBlo
 		args := &forkchoicetypes.BlockAndCheckpoints{Block: b,
 			JustifiedCheckpoint: jCheckpoints[i],
 			FinalizedCheckpoint: fCheckpoints[i]}
-		pendingNodes[len(blks)-i-1] = args
+		pendingNodes[i] = args
 		if err := s.saveInitSyncBlock(ctx, root, b); err != nil {
 			tracing.AnnotateError(span, err)
 			return err
@@ -284,14 +284,10 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []consensusblocks.ROBlo
 	if err := s.cfg.StateGen.SaveState(ctx, lastBR, preState); err != nil {
 		return err
 	}
-	// Insert all nodes but the last one to forkchoice
+	// Insert all nodes to forkchoice
 	if err := s.cfg.ForkChoiceStore.InsertChain(ctx, pendingNodes); err != nil {
 		return errors.Wrap(err, "could not insert batch to forkchoice")
 	}
-	// Insert the last block to forkchoice
-	if err := s.cfg.ForkChoiceStore.InsertNode(ctx, preState, lastB); err != nil {
-		return errors.Wrap(err, "could not insert last block in batch to forkchoice")
-	}
 	// Set their optimistic status
 	if isValidPayload {
 		if err := s.cfg.ForkChoiceStore.SetOptimisticToValid(ctx, lastBR); err != nil {
@@ -664,14 +660,14 @@ func missingDataColumnIndices(store *filesystem.DataColumnStorage, root [fieldpa
 // closed, the context hits cancellation/timeout, or notifications have been received for all the missing sidecars.
 func (s *Service) isDataAvailable(
 	ctx context.Context,
-	root [fieldparams.RootLength]byte,
-	signedBlock interfaces.ReadOnlySignedBeaconBlock,
+	roBlock consensusblocks.ROBlock,
 ) error {
-	block := signedBlock.Block()
+	block := roBlock.Block()
 	if block == nil {
 		return errors.New("invalid nil beacon block")
 	}
 
+	root := roBlock.Root()
 	blockVersion := block.Version()
 	if blockVersion >= version.Fulu {
 		return s.areDataColumnsAvailable(ctx, root, block)
@@ -691,8 +687,6 @@ func (s *Service) areDataColumnsAvailable(
 	root [fieldparams.RootLength]byte,
 	block interfaces.ReadOnlyBeaconBlock,
 ) error {
-	samplesPerSlot := params.BeaconConfig().SamplesPerSlot
-
 	// We are only required to check within MIN_EPOCHS_FOR_DATA_COLUMN_SIDECARS_REQUESTS
 	blockSlot, currentSlot := block.Slot(), s.CurrentSlot()
 	blockEpoch, currentEpoch := slots.ToEpoch(blockSlot), slots.ToEpoch(currentSlot)
@@ -726,6 +720,7 @@ func (s *Service) areDataColumnsAvailable(
 
 	// Compute the sampling size.
 	// https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/das-core.md#custody-sampling
+	samplesPerSlot := params.BeaconConfig().SamplesPerSlot
 	samplingSize := max(samplesPerSlot, custodyGroupCount)
 
 	// Get the peer info for the node.

beacon-chain/blockchain/process_block_helpers.go

@@ -3,14 +3,12 @@ package blockchain
 import (
 	"context"
 	"fmt"
-	"strings"
+	"slices"
 	"time"
 
-	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
-	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
-
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/transition"
 	doublylinkedtree "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/doubly-linked-tree"
 	forkchoicetypes "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/types"
@@ -133,35 +131,26 @@ func (s *Service) sendStateFeedOnBlock(cfg *postBlockProcessConfig) {
 	})
 }
 
+// processLightClientUpdates saves the light client data in lcStore, when feature flag is enabled.
 func (s *Service) processLightClientUpdates(cfg *postBlockProcessConfig) {
-	if err := s.processLightClientUpdate(cfg); err != nil {
-		log.WithError(err).Error("Failed to process light client update")
-	}
-	if err := s.processLightClientOptimisticUpdate(cfg.ctx, cfg.roblock, cfg.postState); err != nil {
-		log.WithError(err).Error("Failed to process light client optimistic update")
-	}
-	if err := s.processLightClientFinalityUpdate(cfg.ctx, cfg.roblock, cfg.postState); err != nil {
-		log.WithError(err).Error("Failed to process light client finality update")
-	}
-}
-
-// processLightClientUpdate saves the light client update for this block
-// if it's better than the already saved one, when feature flag is enabled.
-func (s *Service) processLightClientUpdate(cfg *postBlockProcessConfig) error {
 	attestedRoot := cfg.roblock.Block().ParentRoot()
 	attestedBlock, err := s.getBlock(cfg.ctx, attestedRoot)
 	if err != nil {
-		return errors.Wrapf(err, "could not get attested block for root %#x", attestedRoot)
+		log.WithError(err).Error("processLightClientUpdates: Could not get attested block")
+		return
 	}
 	if attestedBlock == nil || attestedBlock.IsNil() {
-		return errors.New("attested block is nil")
+		log.Error("processLightClientUpdates: Could not get attested block")
+		return
 	}
 	attestedState, err := s.cfg.StateGen.StateByRoot(cfg.ctx, attestedRoot)
 	if err != nil {
-		return errors.Wrapf(err, "could not get attested state for root %#x", attestedRoot)
+		log.WithError(err).Error("processLightClientUpdates: Could not get attested state")
+		return
 	}
 	if attestedState == nil || attestedState.IsNil() {
-		return errors.New("attested state is nil")
+		log.Error("processLightClientUpdates: Could not get attested state")
+		return
 	}
 
 	finalizedRoot := attestedState.FinalizedCheckpoint().Root
@@ -169,98 +158,17 @@ func (s *Service) processLightClientUpdate(cfg *postBlockProcessConfig) error {
 	if err != nil {
 		if errors.Is(err, errBlockNotFoundInCacheOrDB) {
 			log.Debugf("Skipping saving light client update because finalized block is nil for root %#x", finalizedRoot)
-			return nil
+			return
 		}
-		return errors.Wrapf(err, "could not get finalized block for root %#x", finalizedRoot)
+		log.WithError(err).Error("processLightClientUpdates: Could not get finalized block")
+		return
 	}
 
-	update, err := lightclient.NewLightClientUpdateFromBeaconState(cfg.ctx, cfg.postState, cfg.roblock, attestedState, attestedBlock, finalizedBlock)
+	err = s.lcStore.SaveLCData(cfg.ctx, cfg.postState, cfg.roblock, attestedState, attestedBlock, finalizedBlock, s.headRoot())
 	if err != nil {
-		return errors.Wrapf(err, "could not create light client update")
+		log.WithError(err).Error("processLightClientUpdates: Could not save light client data")
 	}
-
-	period := slots.SyncCommitteePeriod(slots.ToEpoch(attestedState.Slot()))
-
-	return s.lcStore.SaveLightClientUpdate(cfg.ctx, period, update)
-}
-
-func (s *Service) processLightClientFinalityUpdate(
-	ctx context.Context,
-	signed interfaces.ReadOnlySignedBeaconBlock,
-	postState state.BeaconState,
-) error {
-	attestedRoot := signed.Block().ParentRoot()
-	attestedBlock, err := s.cfg.BeaconDB.Block(ctx, attestedRoot)
-	if err != nil {
-		return errors.Wrapf(err, "could not get attested block for root %#x", attestedRoot)
-	}
-	attestedState, err := s.cfg.StateGen.StateByRoot(ctx, attestedRoot)
-	if err != nil {
-		return errors.Wrapf(err, "could not get attested state for root %#x", attestedRoot)
-	}
-
-	finalizedCheckpoint := attestedState.FinalizedCheckpoint()
-
-	if finalizedCheckpoint == nil {
-		return nil
-	}
-
-	finalizedRoot := bytesutil.ToBytes32(finalizedCheckpoint.Root)
-	finalizedBlock, err := s.cfg.BeaconDB.Block(ctx, finalizedRoot)
-	if err != nil {
-		if errors.Is(err, errBlockNotFoundInCacheOrDB) {
-			log.Debugf("Skipping processing light client finality update: Finalized block is nil for root %#x", finalizedRoot)
-			return nil
-		}
-		return errors.Wrapf(err, "could not get finalized block for root %#x", finalizedRoot)
-	}
-
-	newUpdate, err := lightclient.NewLightClientFinalityUpdateFromBeaconState(ctx, postState, signed, attestedState, attestedBlock, finalizedBlock)
-
-	if err != nil {
-		return errors.Wrap(err, "could not create light client finality update")
-	}
-
-	if !lightclient.IsBetterFinalityUpdate(newUpdate, s.lcStore.LastFinalityUpdate()) {
-		log.Debug("Skip saving light client finality update: current update is better")
-		return nil
-	}
-
-	s.lcStore.SetLastFinalityUpdate(newUpdate, true)
-
-	return nil
-}
-
-func (s *Service) processLightClientOptimisticUpdate(ctx context.Context, signed interfaces.ReadOnlySignedBeaconBlock,
-	postState state.BeaconState) error {
-	attestedRoot := signed.Block().ParentRoot()
-	attestedBlock, err := s.cfg.BeaconDB.Block(ctx, attestedRoot)
-	if err != nil {
-		return errors.Wrapf(err, "could not get attested block for root %#x", attestedRoot)
-	}
-	attestedState, err := s.cfg.StateGen.StateByRoot(ctx, attestedRoot)
-	if err != nil {
-		return errors.Wrapf(err, "could not get attested state for root %#x", attestedRoot)
-	}
-
-	newUpdate, err := lightclient.NewLightClientOptimisticUpdateFromBeaconState(ctx, postState, signed, attestedState, attestedBlock)
-
-	if err != nil {
-		if strings.Contains(err.Error(), lightclient.ErrNotEnoughSyncCommitteeBits) {
-			log.WithError(err).Debug("Skipping processing light client optimistic update")
-			return nil
-		}
-		return errors.Wrap(err, "could not create light client optimistic update")
-	}
-
-	if !lightclient.IsBetterOptimisticUpdate(newUpdate, s.lcStore.LastOptimisticUpdate()) {
-		log.Debug("Skip saving light client optimistic update: current update is better")
-		return nil
-	}
-
-	s.lcStore.SetLastOptimisticUpdate(newUpdate, true)
-
-	return nil
+	log.Debug("Processed light client updates")
 }
 
 // updateCachesPostBlockProcessing updates the next slot cache and handles the epoch
@@ -469,15 +377,8 @@ func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, signed inte
 	if err != nil {
 		return err
 	}
-	// The first block can have a bogus root since the block is not inserted in forkchoice
-	roblock, err := consensus_blocks.NewROBlockWithRoot(signed, [32]byte{})
-	if err != nil {
-		return err
-	}
-	pendingNodes = append(pendingNodes, &forkchoicetypes.BlockAndCheckpoints{Block: roblock,
-		JustifiedCheckpoint: jCheckpoint, FinalizedCheckpoint: fCheckpoint})
+	root := signed.Block().ParentRoot()
 	// As long as parent node is not in fork choice store, and parent node is in DB.
-	root := roblock.Block().ParentRoot()
 	for !s.cfg.ForkChoiceStore.HasNode(root) && s.cfg.BeaconDB.HasBlock(ctx, root) {
 		b, err := s.getBlock(ctx, root)
 		if err != nil {
@@ -496,12 +397,13 @@ func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, signed inte
 			FinalizedCheckpoint: fCheckpoint}
 		pendingNodes = append(pendingNodes, args)
 	}
-	if len(pendingNodes) == 1 {
+	if len(pendingNodes) == 0 {
 		return nil
 	}
 	if root != s.ensureRootNotZeros(finalized.Root) && !s.cfg.ForkChoiceStore.HasNode(root) {
 		return ErrNotDescendantOfFinalized
 	}
+	slices.Reverse(pendingNodes)
 	return s.cfg.ForkChoiceStore.InsertChain(ctx, pendingNodes)
 }
 

beacon-chain/blockchain/process_block_test.go

@@ -12,7 +12,6 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/blocks"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/signing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/transition"
@@ -24,6 +23,7 @@ import (
 	mockExecution "github.com/OffchainLabs/prysm/v6/beacon-chain/execution/testing"
 	doublylinkedtree "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/doubly-linked-tree"
 	forkchoicetypes "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/types"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations/kv"
 	mockp2p "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/state"
@@ -2795,6 +2795,11 @@ func TestProcessLightClientUpdate(t *testing.T) {
 	s, tr := minimalTestService(t, WithLCStore())
 	ctx := tr.ctx
 
+	headState, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, s.cfg.BeaconDB.SaveState(ctx, headState, [32]byte{1, 2}))
+	require.NoError(t, s.cfg.BeaconDB.SaveHeadBlockRoot(ctx, [32]byte{1, 2}))
+
 	for testVersion := version.Altair; testVersion <= version.Electra; testVersion++ {
 		t.Run(version.String(testVersion), func(t *testing.T) {
 			l := util.NewTestLightClient(t, testVersion)
@@ -2817,6 +2822,8 @@ func TestProcessLightClientUpdate(t *testing.T) {
 			require.NoError(t, err)
 			err = s.cfg.BeaconDB.SaveState(ctx, l.State, currentBlockRoot)
 			require.NoError(t, err)
+			err = s.cfg.BeaconDB.SaveHeadBlockRoot(ctx, currentBlockRoot)
+			require.NoError(t, err)
 
 			err = s.cfg.BeaconDB.SaveBlock(ctx, l.FinalizedBlock)
 			require.NoError(t, err)
@@ -2831,10 +2838,9 @@ func TestProcessLightClientUpdate(t *testing.T) {
 			period := slots.SyncCommitteePeriod(slots.ToEpoch(l.AttestedState.Slot()))
 
 			t.Run("no old update", func(t *testing.T) {
-				require.NoError(t, s.processLightClientUpdate(cfg))
-
+				s.processLightClientUpdates(cfg)
 				// Check that the light client update is saved
-				u, err := s.lcStore.LightClientUpdate(ctx, period)
+				u, err := s.lcStore.LightClientUpdate(ctx, period, l.Block)
 				require.NoError(t, err)
 				require.NotNil(t, u)
 				attestedStateRoot, err := l.AttestedState.HashTreeRoot(ctx)
@@ -2848,12 +2854,12 @@ func TestProcessLightClientUpdate(t *testing.T) {
 				oldUpdate, err := lightClient.CreateDefaultLightClientUpdate(l.AttestedBlock)
 				require.NoError(t, err)
 
-				err = s.lcStore.SaveLightClientUpdate(ctx, period, oldUpdate)
+				err = s.cfg.BeaconDB.SaveLightClientUpdate(ctx, period, oldUpdate)
 				require.NoError(t, err)
 
-				require.NoError(t, s.processLightClientUpdate(cfg))
+				s.processLightClientUpdates(cfg)
 
-				u, err := s.lcStore.LightClientUpdate(ctx, period)
+				u, err := s.lcStore.LightClientUpdate(ctx, period, l.Block)
 				require.NoError(t, err)
 				require.NotNil(t, u)
 				attestedStateRoot, err := l.AttestedState.HashTreeRoot(ctx)
@@ -2877,12 +2883,12 @@ func TestProcessLightClientUpdate(t *testing.T) {
 					SyncCommitteeSignature: make([]byte, 96),
 				})
 
-				err = s.lcStore.SaveLightClientUpdate(ctx, period, oldUpdate)
+				err = s.cfg.BeaconDB.SaveLightClientUpdate(ctx, period, oldUpdate)
 				require.NoError(t, err)
 
-				require.NoError(t, s.processLightClientUpdate(cfg))
+				s.processLightClientUpdates(cfg)
 
-				u, err := s.lcStore.LightClientUpdate(ctx, period)
+				u, err := s.lcStore.LightClientUpdate(ctx, period, l.Block)
 				require.NoError(t, err)
 				require.NotNil(t, u)
 				require.DeepEqual(t, oldUpdate, u)
@@ -2952,14 +2958,18 @@ func TestIsDataAvailable(t *testing.T) {
 		params := testIsAvailableParams{options: []Option{WithGenesisTime(time.Unix(0, 0))}}
 		ctx, _, service, root, signed := testIsAvailableSetup(t, params)
 
-		err := service.isDataAvailable(ctx, root, signed)
+		roBlock, err := consensusblocks.NewROBlockWithRoot(signed, root)
+		require.NoError(t, err)
+		err = service.isDataAvailable(ctx, roBlock)
 		require.NoError(t, err)
 	})
 
 	t.Run("Fulu - no commitment in blocks", func(t *testing.T) {
 		ctx, _, service, root, signed := testIsAvailableSetup(t, testIsAvailableParams{})
 
-		err := service.isDataAvailable(ctx, root, signed)
+		roBlock, err := consensusblocks.NewROBlockWithRoot(signed, root)
+		require.NoError(t, err)
+		err = service.isDataAvailable(ctx, roBlock)
 		require.NoError(t, err)
 	})
 
@@ -2977,7 +2987,9 @@ func TestIsDataAvailable(t *testing.T) {
 
 		ctx, _, service, root, signed := testIsAvailableSetup(t, params)
 
-		err := service.isDataAvailable(ctx, root, signed)
+		roBlock, err := consensusblocks.NewROBlockWithRoot(signed, root)
+		require.NoError(t, err)
+		err = service.isDataAvailable(ctx, roBlock)
 		require.NoError(t, err)
 	})
 
@@ -2989,7 +3001,9 @@ func TestIsDataAvailable(t *testing.T) {
 
 		ctx, _, service, root, signed := testIsAvailableSetup(t, params)
 
-		err := service.isDataAvailable(ctx, root, signed)
+		roBlock, err := consensusblocks.NewROBlockWithRoot(signed, root)
+		require.NoError(t, err)
+		err = service.isDataAvailable(ctx, roBlock)
 		require.NoError(t, err)
 	})
 
@@ -3037,7 +3051,9 @@ func TestIsDataAvailable(t *testing.T) {
 		ctx, cancel := context.WithTimeout(ctx, time.Second*2)
 		defer cancel()
 
-		err = service.isDataAvailable(ctx, root, signed)
+		roBlock, err := consensusblocks.NewROBlockWithRoot(signed, root)
+		require.NoError(t, err)
+		err = service.isDataAvailable(ctx, roBlock)
 		require.NoError(t, err)
 	})
 
@@ -3099,7 +3115,9 @@ func TestIsDataAvailable(t *testing.T) {
 		ctx, cancel := context.WithTimeout(ctx, time.Second*2)
 		defer cancel()
 
-		err = service.isDataAvailable(ctx, root, signed)
+		roBlock, err := consensusblocks.NewROBlockWithRoot(signed, root)
+		require.NoError(t, err)
+		err = service.isDataAvailable(ctx, roBlock)
 		require.NoError(t, err)
 	})
 
@@ -3118,7 +3136,9 @@ func TestIsDataAvailable(t *testing.T) {
 			cancel()
 		}()
 
-		err := service.isDataAvailable(ctx, root, signed)
+		roBlock, err := consensusblocks.NewROBlockWithRoot(signed, root)
+		require.NoError(t, err)
+		err = service.isDataAvailable(ctx, roBlock)
 		require.NotNil(t, err)
 	})
 }
@@ -3190,6 +3210,11 @@ func TestProcessLightClientOptimisticUpdate(t *testing.T) {
 	s.cfg.P2P = &mockp2p.FakeP2P{}
 	ctx := tr.ctx
 
+	headState, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, s.cfg.BeaconDB.SaveState(ctx, headState, [32]byte{1, 2}))
+	require.NoError(t, s.cfg.BeaconDB.SaveHeadBlockRoot(ctx, [32]byte{1, 2}))
+
 	testCases := []struct {
 		name          string
 		oldOptions    []util.LightClientOption
@@ -3205,7 +3230,7 @@ func TestProcessLightClientOptimisticUpdate(t *testing.T) {
 		{
 			name:          "Same age",
 			oldOptions:    []util.LightClientOption{},
-			newOptions:    []util.LightClientOption{util.WithSupermajority()}, // supermajority does not matter here and is only added to result in two different updates
+			newOptions:    []util.LightClientOption{util.WithSupermajority(0)}, // supermajority does not matter here and is only added to result in two different updates
 			expectReplace: false,
 		},
 		{
@@ -3249,14 +3274,14 @@ func TestProcessLightClientOptimisticUpdate(t *testing.T) {
 
 			t.Run(version.String(testVersion)+"_"+tc.name, func(t *testing.T) {
 				s.genesisTime = time.Unix(time.Now().Unix()-(int64(forkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
-				s.lcStore = lightClient.NewLightClientStore(s.cfg.BeaconDB, s.cfg.P2P, s.cfg.StateNotifier.StateFeed())
+				s.lcStore = lightClient.NewLightClientStore(s.cfg.P2P, s.cfg.StateNotifier.StateFeed(), s.cfg.BeaconDB)
 
 				var oldActualUpdate interfaces.LightClientOptimisticUpdate
 				var err error
 				if tc.oldOptions != nil {
 					// config for old update
 					lOld, cfgOld := setupLightClientTestRequirements(ctx, t, s, testVersion, tc.oldOptions...)
-					require.NoError(t, s.processLightClientOptimisticUpdate(cfgOld.ctx, cfgOld.roblock, cfgOld.postState))
+					s.processLightClientUpdates(cfgOld)
 
 					oldActualUpdate, err = lightClient.NewLightClientOptimisticUpdateFromBeaconState(lOld.Ctx, lOld.State, lOld.Block, lOld.AttestedState, lOld.AttestedBlock)
 					require.NoError(t, err)
@@ -3270,7 +3295,7 @@ func TestProcessLightClientOptimisticUpdate(t *testing.T) {
 
 				// config for new update
 				lNew, cfgNew := setupLightClientTestRequirements(ctx, t, s, testVersion, tc.newOptions...)
-				require.NoError(t, s.processLightClientOptimisticUpdate(cfgNew.ctx, cfgNew.roblock, cfgNew.postState))
+				s.processLightClientUpdates(cfgNew)
 
 				newActualUpdate, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(lNew.Ctx, lNew.State, lNew.Block, lNew.AttestedState, lNew.AttestedBlock)
 				require.NoError(t, err)
@@ -3311,6 +3336,7 @@ func TestProcessLightClientFinalityUpdate(t *testing.T) {
 	s, tr := minimalTestService(t)
 	s.cfg.P2P = &mockp2p.FakeP2P{}
 	ctx := tr.ctx
+	s.head = &head{}
 
 	testCases := []struct {
 		name          string
@@ -3389,15 +3415,18 @@ func TestProcessLightClientFinalityUpdate(t *testing.T) {
 
 			t.Run(version.String(testVersion)+"_"+tc.name, func(t *testing.T) {
 				s.genesisTime = time.Unix(time.Now().Unix()-(int64(forkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
-				s.lcStore = lightClient.NewLightClientStore(s.cfg.BeaconDB, s.cfg.P2P, s.cfg.StateNotifier.StateFeed())
+				s.lcStore = lightClient.NewLightClientStore(s.cfg.P2P, s.cfg.StateNotifier.StateFeed(), s.cfg.BeaconDB)
 
 				var actualOldUpdate, actualNewUpdate interfaces.LightClientFinalityUpdate
-				var err error
 
 				if tc.oldOptions != nil {
 					// config for old update
 					lOld, cfgOld := setupLightClientTestRequirements(ctx, t, s, testVersion, tc.oldOptions...)
-					require.NoError(t, s.processLightClientFinalityUpdate(cfgOld.ctx, cfgOld.roblock, cfgOld.postState))
+					blkRoot, err := lOld.Block.Block().HashTreeRoot()
+					require.NoError(t, err)
+					s.head.block = lOld.Block
+					s.head.root = blkRoot
+					s.processLightClientUpdates(cfgOld)
 
 					// check that the old update is saved
 					actualOldUpdate, err = lightClient.NewLightClientFinalityUpdateFromBeaconState(ctx, cfgOld.postState, cfgOld.roblock, lOld.AttestedState, lOld.AttestedBlock, lOld.FinalizedBlock)
@@ -3408,7 +3437,11 @@ func TestProcessLightClientFinalityUpdate(t *testing.T) {
 
 				// config for new update
 				lNew, cfgNew := setupLightClientTestRequirements(ctx, t, s, testVersion, tc.newOptions...)
-				require.NoError(t, s.processLightClientFinalityUpdate(cfgNew.ctx, cfgNew.roblock, cfgNew.postState))
+				blkRoot, err := lNew.Block.Block().HashTreeRoot()
+				require.NoError(t, err)
+				s.head.block = lNew.Block
+				s.head.root = blkRoot
+				s.processLightClientUpdates(cfgNew)
 
 				// check that the actual old update and the actual new update are different
 				actualNewUpdate, err = lightClient.NewLightClientFinalityUpdateFromBeaconState(ctx, cfgNew.postState, cfgNew.roblock, lNew.AttestedState, lNew.AttestedBlock, lNew.FinalizedBlock)

beacon-chain/blockchain/receive_block.go

@@ -16,7 +16,6 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/slasher/types"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/state"
 	"github.com/OffchainLabs/prysm/v6/config/features"
-	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
@@ -93,7 +92,7 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySig
 
 	blockCopy, err := block.Copy()
 	if err != nil {
-		return err
+		return errors.Wrap(err, "block copy")
 	}
 
 	preState, err := s.getBlockPreState(ctx, blockCopy.Block())
@@ -104,17 +103,17 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySig
 	currentCheckpoints := s.saveCurrentCheckpoints(preState)
 	roblock, err := blocks.NewROBlockWithRoot(blockCopy, blockRoot)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "new ro block with root")
 	}
 
 	postState, isValidPayload, err := s.validateExecutionAndConsensus(ctx, preState, roblock)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "validator execution and consensus")
 	}
 
-	daWaitedTime, err := s.handleDA(ctx, blockCopy, blockRoot, avs)
+	daWaitedTime, err := s.handleDA(ctx, avs, roblock)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "handle da")
 	}
 
 	// Defragment the state before continuing block processing.
@@ -135,10 +134,10 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySig
 	if err := s.postBlockProcess(args); err != nil {
 		err := errors.Wrap(err, "could not process block")
 		tracing.AnnotateError(span, err)
-		return err
+		return errors.Wrap(err, "post block process")
 	}
 	if err := s.updateCheckpoints(ctx, currentCheckpoints, preState, postState, blockRoot); err != nil {
-		return err
+		return errors.Wrap(err, "update checkpoints")
 	}
 	// If slasher is configured, forward the attestations in the block via an event feed for processing.
 	if s.slasherEnabled {
@@ -152,12 +151,12 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySig
 
 	// Have we been finalizing? Should we start saving hot states to db?
 	if err := s.checkSaveHotStateDB(ctx); err != nil {
-		return err
+		return errors.Wrap(err, "check save hot state db")
 	}
 
 	// We apply the same heuristic to some of our more important caches.
 	if err := s.handleCaches(); err != nil {
-		return err
+		return errors.Wrap(err, "handle caches")
 	}
 	s.reportPostBlockProcessing(blockCopy, blockRoot, receivedTime, daWaitedTime)
 	return nil
@@ -240,37 +239,19 @@ func (s *Service) validateExecutionAndConsensus(
 	return postState, isValidPayload, nil
 }
 
-func (s *Service) handleDA(
-	ctx context.Context,
-	block interfaces.SignedBeaconBlock,
-	blockRoot [fieldparams.RootLength]byte,
-	avs das.AvailabilityStore,
-) (elapsed time.Duration, err error) {
-	defer func(start time.Time) {
-		elapsed = time.Since(start)
-
-		if err == nil {
-			dataAvailWaitedTime.Observe(float64(elapsed.Milliseconds()))
-		}
-	}(time.Now())
-
-	if avs == nil {
-		if err = s.isDataAvailable(ctx, blockRoot, block); err != nil {
-			return
-		}
-
-		return
+func (s *Service) handleDA(ctx context.Context, avs das.AvailabilityStore, block blocks.ROBlock) (time.Duration, error) {
+	var err error
+	start := time.Now()
+	if avs != nil {
+		err = avs.IsDataAvailable(ctx, s.CurrentSlot(), block)
+	} else {
+		err = s.isDataAvailable(ctx, block)
 	}
-
-	var rob blocks.ROBlock
-	rob, err = blocks.NewROBlockWithRoot(block, blockRoot)
+	elapsed := time.Since(start)
 	if err != nil {
-		return
+		dataAvailWaitedTime.Observe(float64(elapsed.Milliseconds()))
 	}
-
-	err = avs.IsDataAvailable(ctx, s.CurrentSlot(), rob)
-
-	return
+	return elapsed, err
 }
 
 func (s *Service) reportPostBlockProcessing(
@@ -320,13 +301,28 @@ func (s *Service) executePostFinalizationTasks(ctx context.Context, finalizedSta
 	if features.Get().EnableLightClient {
 		// Save a light client bootstrap for the finalized checkpoint
 		go func() {
-			err := s.lcStore.SaveLightClientBootstrap(s.ctx, finalized.Root)
+			st, err := s.cfg.StateGen.StateByRoot(ctx, finalized.Root)
+			if err != nil {
+				log.WithError(err).Error("Could not retrieve state for finalized root to save light client bootstrap")
+				return
+			}
+			err = s.lcStore.SaveLightClientBootstrap(s.ctx, finalized.Root, st)
 			if err != nil {
 				log.WithError(err).Error("Could not save light client bootstrap by block root")
 			} else {
 				log.Debugf("Saved light client bootstrap for finalized root %#x", finalized.Root)
 			}
 		}()
+
+		// Clean up the light client store caches
+		go func() {
+			err := s.lcStore.MigrateToCold(s.ctx, finalized.Root)
+			if err != nil {
+				log.WithError(err).Error("Could not migrate light client store to cold storage")
+			} else {
+				log.Debugf("Migrated light client store to cold storage for finalized root %#x", finalized.Root)
+			}
+		}()
 	}
 }
 

beacon-chain/blockchain/receive_block_test.go

@@ -9,9 +9,9 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/das"
 	forkchoicetypes "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/types"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/voluntaryexits"
 	"github.com/OffchainLabs/prysm/v6/config/features"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
@@ -192,7 +192,9 @@ func TestHandleDA(t *testing.T) {
 	require.NoError(t, err)
 
 	s, _ := minimalTestService(t)
-	elapsed, err := s.handleDA(t.Context(), signedBeaconBlock, [fieldparams.RootLength]byte{}, nil)
+	block, err := blocks.NewROBlockWithRoot(signedBeaconBlock, [32]byte{})
+	require.NoError(t, err)
+	elapsed, err := s.handleDA(t.Context(), nil, block)
 	require.NoError(t, err)
 	require.Equal(t, true, elapsed > 0, "Elapsed time should be greater than 0")
 }
@@ -594,11 +596,7 @@ func TestProcessLightClientBootstrap(t *testing.T) {
 
 			require.NoError(t, s.cfg.ForkChoiceStore.UpdateFinalizedCheckpoint(&forkchoicetypes.Checkpoint{Epoch: cp.Epoch, Root: [32]byte(cp.Root)}))
 
-			sss, err := s.cfg.BeaconDB.State(ctx, finalizedBlockRoot)
-			require.NoError(t, err)
-			require.NotNil(t, sss)
-
-			s.executePostFinalizationTasks(s.ctx, l.FinalizedState)
+			s.executePostFinalizationTasks(s.ctx, l.AttestedState)
 
 			// wait for the goroutine to finish processing
 			time.Sleep(1 * time.Second)

beacon-chain/blockchain/service.go

@@ -14,13 +14,13 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	coreTime "github.com/OffchainLabs/prysm/v6/beacon-chain/core/time"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/transition"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/execution"
 	f "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/blstoexec"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/slashings"

beacon-chain/blockchain/setup_forkchoice.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"slices"
 
 	forkchoicetypes "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/types"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/state"
@@ -112,6 +113,7 @@ func (s *Service) buildForkchoiceChain(ctx context.Context, head interfaces.Read
 			return nil, errors.New("head block is not a descendant of the finalized checkpoint")
 		}
 	}
+	slices.Reverse(chain)
 	return chain, nil
 }
 

beacon-chain/blockchain/setup_forkchoice_test.go

@@ -124,5 +124,5 @@ func Test_setupForkchoiceTree_Head(t *testing.T) {
 	require.NotEqual(t, fRoot, root)
 	require.Equal(t, root, service.startupHeadRoot())
 	require.NoError(t, service.setupForkchoiceTree(st))
-	require.Equal(t, 2, service.cfg.ForkChoiceStore.NodeCount())
+	require.Equal(t, 3, service.cfg.ForkChoiceStore.NodeCount())
 }

beacon-chain/blockchain/setup_test.go

@@ -11,21 +11,21 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache/depositsnapshot"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
-	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	testDB "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
 	mockExecution "github.com/OffchainLabs/prysm/v6/beacon-chain/execution/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice"
 	doublylinkedtree "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/doubly-linked-tree"
+	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/blstoexec"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p"
 	p2pTesting "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/startup"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/state/stategen"
-	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
@@ -89,7 +89,7 @@ func (mb *mockBroadcaster) BroadcastLightClientFinalityUpdate(_ context.Context,
 	return nil
 }
 
-func (mb *mockBroadcaster) BroadcastDataColumnSidecar(_ [fieldparams.RootLength]byte, _ uint64, _ *ethpb.DataColumnSidecar) error {
+func (mb *mockBroadcaster) BroadcastDataColumnSidecar(_ uint64, _ blocks.VerifiedRODataColumn) error {
 	mb.broadcastCalled = true
 	return nil
 }

beacon-chain/blockchain/testing/mock.go

@@ -723,7 +723,8 @@ func (c *ChainService) ReceiveDataColumn(dc blocks.VerifiedRODataColumn) error {
 }
 
 // ReceiveDataColumns implements the same method in chain service
-func (*ChainService) ReceiveDataColumns(_ []blocks.VerifiedRODataColumn) error {
+func (c *ChainService) ReceiveDataColumns(dcs []blocks.VerifiedRODataColumn) error {
+	c.DataColumns = append(c.DataColumns, dcs...)
 	return nil
 }
 

beacon-chain/core/light-client/store.go

@@ -1,202 +0,0 @@
-package light_client
-
-import (
-	"context"
-	"sync"
-
-	"github.com/OffchainLabs/prysm/v6/async/event"
-	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed"
-	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
-	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/iface"
-	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p"
-	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
-	"github.com/pkg/errors"
-	log "github.com/sirupsen/logrus"
-)
-
-var ErrLightClientBootstrapNotFound = errors.New("light client bootstrap not found")
-
-type Store struct {
-	mu sync.RWMutex
-
-	beaconDB             iface.HeadAccessDatabase
-	lastFinalityUpdate   interfaces.LightClientFinalityUpdate   // tracks the best finality update seen so far
-	lastOptimisticUpdate interfaces.LightClientOptimisticUpdate // tracks the best optimistic update seen so far
-	p2p                  p2p.Accessor
-	stateFeed            event.SubscriberSender
-}
-
-func NewLightClientStore(db iface.HeadAccessDatabase, p p2p.Accessor, e event.SubscriberSender) *Store {
-	return &Store{
-		beaconDB:  db,
-		p2p:       p,
-		stateFeed: e,
-	}
-}
-
-func (s *Store) LightClientBootstrap(ctx context.Context, blockRoot [32]byte) (interfaces.LightClientBootstrap, error) {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-
-	// Fetch the light client bootstrap from the database
-	bootstrap, err := s.beaconDB.LightClientBootstrap(ctx, blockRoot[:])
-	if err != nil {
-		return nil, err
-	}
-	if bootstrap == nil { // not found
-		return nil, ErrLightClientBootstrapNotFound
-	}
-
-	return bootstrap, nil
-}
-
-func (s *Store) SaveLightClientBootstrap(ctx context.Context, blockRoot [32]byte) error {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	blk, err := s.beaconDB.Block(ctx, blockRoot)
-	if err != nil {
-		return errors.Wrapf(err, "failed to fetch block for root %x", blockRoot)
-	}
-	if blk == nil {
-		return errors.Errorf("failed to fetch block for root %x", blockRoot)
-	}
-
-	state, err := s.beaconDB.State(ctx, blockRoot)
-	if err != nil {
-		return errors.Wrapf(err, "failed to fetch state for block root %x", blockRoot)
-	}
-	if state == nil {
-		return errors.Errorf("failed to fetch state for block root %x", blockRoot)
-	}
-
-	bootstrap, err := NewLightClientBootstrapFromBeaconState(ctx, state.Slot(), state, blk)
-	if err != nil {
-		return errors.Wrapf(err, "failed to create light client bootstrap for block root %x", blockRoot)
-	}
-
-	// Save the light client bootstrap to the database
-	if err := s.beaconDB.SaveLightClientBootstrap(ctx, blockRoot[:], bootstrap); err != nil {
-		return err
-	}
-	return nil
-}
-
-func (s *Store) LightClientUpdates(ctx context.Context, startPeriod, endPeriod uint64) ([]interfaces.LightClientUpdate, error) {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-
-	// Fetch the light client updatesMap from the database
-	updatesMap, err := s.beaconDB.LightClientUpdates(ctx, startPeriod, endPeriod)
-	if err != nil {
-		return nil, err
-	}
-
-	var updates []interfaces.LightClientUpdate
-	for i := startPeriod; i <= endPeriod; i++ {
-		update, ok := updatesMap[i]
-		if !ok {
-			// Only return the first contiguous range of updates
-			break
-		}
-		updates = append(updates, update)
-	}
-
-	return updates, nil
-}
-
-func (s *Store) LightClientUpdate(ctx context.Context, period uint64) (interfaces.LightClientUpdate, error) {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-
-	// Fetch the light client update for the given period from the database
-	update, err := s.beaconDB.LightClientUpdate(ctx, period)
-	if err != nil {
-		return nil, err
-	}
-
-	return update, nil
-}
-
-func (s *Store) SaveLightClientUpdate(ctx context.Context, period uint64, update interfaces.LightClientUpdate) error {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	oldUpdate, err := s.beaconDB.LightClientUpdate(ctx, period)
-	if err != nil {
-		return errors.Wrapf(err, "could not get current light client update")
-	}
-
-	if oldUpdate == nil {
-		if err := s.beaconDB.SaveLightClientUpdate(ctx, period, update); err != nil {
-			return errors.Wrapf(err, "could not save light client update")
-		}
-		log.WithField("period", period).Debug("Saved new light client update")
-		return nil
-	}
-
-	isNewUpdateBetter, err := IsBetterUpdate(update, oldUpdate)
-	if err != nil {
-		return errors.Wrapf(err, "could not compare light client updates")
-	}
-
-	if isNewUpdateBetter {
-		if err := s.beaconDB.SaveLightClientUpdate(ctx, period, update); err != nil {
-			return errors.Wrapf(err, "could not save light client update")
-		}
-		log.WithField("period", period).Debug("Saved new light client update")
-		return nil
-	}
-	log.WithField("period", period).Debug("New light client update is not better than the current one, skipping save")
-	return nil
-}
-
-func (s *Store) SetLastFinalityUpdate(update interfaces.LightClientFinalityUpdate, broadcast bool) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	if broadcast && IsFinalityUpdateValidForBroadcast(update, s.lastFinalityUpdate) {
-		if err := s.p2p.BroadcastLightClientFinalityUpdate(context.Background(), update); err != nil {
-			log.WithError(err).Error("Could not broadcast light client finality update")
-		}
-	}
-
-	s.lastFinalityUpdate = update
-	log.Debug("Saved new light client finality update")
-
-	s.stateFeed.Send(&feed.Event{
-		Type: statefeed.LightClientFinalityUpdate,
-		Data: update,
-	})
-}
-
-func (s *Store) LastFinalityUpdate() interfaces.LightClientFinalityUpdate {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-	return s.lastFinalityUpdate
-}
-
-func (s *Store) SetLastOptimisticUpdate(update interfaces.LightClientOptimisticUpdate, broadcast bool) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	if broadcast {
-		if err := s.p2p.BroadcastLightClientOptimisticUpdate(context.Background(), update); err != nil {
-			log.WithError(err).Error("Could not broadcast light client optimistic update")
-		}
-	}
-
-	s.lastOptimisticUpdate = update
-	log.Debug("Saved new light client optimistic update")
-
-	s.stateFeed.Send(&feed.Event{
-		Type: statefeed.LightClientOptimisticUpdate,
-		Data: update,
-	})
-}
-
-func (s *Store) LastOptimisticUpdate() interfaces.LightClientOptimisticUpdate {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-	return s.lastOptimisticUpdate
-}

beacon-chain/core/light-client/store_test.go

@@ -1,165 +0,0 @@
-package light_client_test
-
-import (
-	"testing"
-
-	"github.com/OffchainLabs/prysm/v6/async/event"
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
-	testDB "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
-	p2pTesting "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
-	"github.com/OffchainLabs/prysm/v6/config/params"
-	"github.com/OffchainLabs/prysm/v6/runtime/version"
-	"github.com/OffchainLabs/prysm/v6/testing/require"
-	"github.com/OffchainLabs/prysm/v6/testing/util"
-)
-
-func TestLightClientStore(t *testing.T) {
-	params.SetupTestConfigCleanup(t)
-	cfg := params.BeaconConfig()
-	cfg.AltairForkEpoch = 1
-	cfg.BellatrixForkEpoch = 2
-	cfg.CapellaForkEpoch = 3
-	cfg.DenebForkEpoch = 4
-	cfg.ElectraForkEpoch = 5
-	params.OverrideBeaconConfig(cfg)
-
-	// Initialize the light client store
-	lcStore := lightClient.NewLightClientStore(testDB.SetupDB(t), &p2pTesting.FakeP2P{}, new(event.Feed))
-
-	// Create test light client updates for Capella and Deneb
-	lCapella := util.NewTestLightClient(t, version.Capella)
-	opUpdateCapella, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(lCapella.Ctx, lCapella.State, lCapella.Block, lCapella.AttestedState, lCapella.AttestedBlock)
-	require.NoError(t, err)
-	require.NotNil(t, opUpdateCapella, "OptimisticUpdateCapella is nil")
-	finUpdateCapella, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(lCapella.Ctx, lCapella.State, lCapella.Block, lCapella.AttestedState, lCapella.AttestedBlock, lCapella.FinalizedBlock)
-	require.NoError(t, err)
-	require.NotNil(t, finUpdateCapella, "FinalityUpdateCapella is nil")
-
-	lDeneb := util.NewTestLightClient(t, version.Deneb)
-	opUpdateDeneb, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(lDeneb.Ctx, lDeneb.State, lDeneb.Block, lDeneb.AttestedState, lDeneb.AttestedBlock)
-	require.NoError(t, err)
-	require.NotNil(t, opUpdateDeneb, "OptimisticUpdateDeneb is nil")
-	finUpdateDeneb, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(lDeneb.Ctx, lDeneb.State, lDeneb.Block, lDeneb.AttestedState, lDeneb.AttestedBlock, lDeneb.FinalizedBlock)
-	require.NoError(t, err)
-	require.NotNil(t, finUpdateDeneb, "FinalityUpdateDeneb is nil")
-
-	// Initially the store should have nil values for both updates
-	require.IsNil(t, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should be nil")
-	require.IsNil(t, lcStore.LastOptimisticUpdate(), "lastOptimisticUpdate should be nil")
-
-	// Set and get finality with Capella update. Optimistic update should be nil
-	lcStore.SetLastFinalityUpdate(finUpdateCapella, false)
-	require.Equal(t, finUpdateCapella, lcStore.LastFinalityUpdate(), "lastFinalityUpdate is wrong")
-	require.IsNil(t, lcStore.LastOptimisticUpdate(), "lastOptimisticUpdate should be nil")
-
-	// Set and get optimistic with Capella update. Finality update should be Capella
-	lcStore.SetLastOptimisticUpdate(opUpdateCapella, false)
-	require.Equal(t, opUpdateCapella, lcStore.LastOptimisticUpdate(), "lastOptimisticUpdate is wrong")
-	require.Equal(t, finUpdateCapella, lcStore.LastFinalityUpdate(), "lastFinalityUpdate is wrong")
-
-	// Set and get finality and optimistic with Deneb update
-	lcStore.SetLastFinalityUpdate(finUpdateDeneb, false)
-	lcStore.SetLastOptimisticUpdate(opUpdateDeneb, false)
-	require.Equal(t, finUpdateDeneb, lcStore.LastFinalityUpdate(), "lastFinalityUpdate is wrong")
-	require.Equal(t, opUpdateDeneb, lcStore.LastOptimisticUpdate(), "lastOptimisticUpdate is wrong")
-}
-
-func TestLightClientStore_SetLastFinalityUpdate(t *testing.T) {
-	p2p := p2pTesting.NewTestP2P(t)
-	lcStore := lightClient.NewLightClientStore(testDB.SetupDB(t), p2p, new(event.Feed))
-
-	// update 0 with basic data and no supermajority following an empty lastFinalityUpdate - should save and broadcast
-	l0 := util.NewTestLightClient(t, version.Altair)
-	update0, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l0.Ctx, l0.State, l0.Block, l0.AttestedState, l0.AttestedBlock, l0.FinalizedBlock)
-	require.NoError(t, err, "Failed to create light client finality update")
-
-	require.Equal(t, true, lightClient.IsBetterFinalityUpdate(update0, lcStore.LastFinalityUpdate()), "update0 should be better than nil")
-	// update0 should be valid for broadcast - meaning it should be broadcasted
-	require.Equal(t, true, lightClient.IsFinalityUpdateValidForBroadcast(update0, lcStore.LastFinalityUpdate()), "update0 should be valid for broadcast")
-
-	lcStore.SetLastFinalityUpdate(update0, true)
-	require.Equal(t, update0, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
-	require.Equal(t, true, p2p.BroadcastCalled.Load(), "Broadcast should have been called after setting a new last finality update when previous is nil")
-	p2p.BroadcastCalled.Store(false) // Reset for next test
-
-	// update 1 with same finality slot, increased attested slot, and no supermajority - should save but not broadcast
-	l1 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(1))
-	update1, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l1.Ctx, l1.State, l1.Block, l1.AttestedState, l1.AttestedBlock, l1.FinalizedBlock)
-	require.NoError(t, err, "Failed to create light client finality update")
-
-	require.Equal(t, true, lightClient.IsBetterFinalityUpdate(update1, update0), "update1 should be better than update0")
-	// update1 should not be valid for broadcast - meaning it should not be broadcasted
-	require.Equal(t, false, lightClient.IsFinalityUpdateValidForBroadcast(update1, lcStore.LastFinalityUpdate()), "update1 should not be valid for broadcast")
-
-	lcStore.SetLastFinalityUpdate(update1, true)
-	require.Equal(t, update1, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
-	require.Equal(t, false, p2p.BroadcastCalled.Load(), "Broadcast should not have been called after setting a new last finality update without supermajority")
-	p2p.BroadcastCalled.Store(false) // Reset for next test
-
-	// update 2 with same finality slot, increased attested slot, and supermajority - should save and broadcast
-	l2 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(2), util.WithSupermajority())
-	update2, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
-	require.NoError(t, err, "Failed to create light client finality update")
-
-	require.Equal(t, true, lightClient.IsBetterFinalityUpdate(update2, update1), "update2 should be better than update1")
-	// update2 should be valid for broadcast - meaning it should be broadcasted
-	require.Equal(t, true, lightClient.IsFinalityUpdateValidForBroadcast(update2, lcStore.LastFinalityUpdate()), "update2 should be valid for broadcast")
-
-	lcStore.SetLastFinalityUpdate(update2, true)
-	require.Equal(t, update2, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
-	require.Equal(t, true, p2p.BroadcastCalled.Load(), "Broadcast should have been called after setting a new last finality update with supermajority")
-	p2p.BroadcastCalled.Store(false) // Reset for next test
-
-	// update 3 with same finality slot, increased attested slot, and supermajority - should save but not broadcast
-	l3 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(3), util.WithSupermajority())
-	update3, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l3.Ctx, l3.State, l3.Block, l3.AttestedState, l3.AttestedBlock, l3.FinalizedBlock)
-	require.NoError(t, err, "Failed to create light client finality update")
-
-	require.Equal(t, true, lightClient.IsBetterFinalityUpdate(update3, update2), "update3 should be better than update2")
-	// update3 should not be valid for broadcast - meaning it should not be broadcasted
-	require.Equal(t, false, lightClient.IsFinalityUpdateValidForBroadcast(update3, lcStore.LastFinalityUpdate()), "update3 should not be valid for broadcast")
-
-	lcStore.SetLastFinalityUpdate(update3, true)
-	require.Equal(t, update3, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
-	require.Equal(t, false, p2p.BroadcastCalled.Load(), "Broadcast should not have been when previous was already broadcast")
-
-	// update 4 with increased finality slot, increased attested slot, and supermajority - should save and broadcast
-	l4 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedFinalizedSlot(1), util.WithIncreasedAttestedSlot(1), util.WithSupermajority())
-	update4, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l4.Ctx, l4.State, l4.Block, l4.AttestedState, l4.AttestedBlock, l4.FinalizedBlock)
-	require.NoError(t, err, "Failed to create light client finality update")
-
-	require.Equal(t, true, lightClient.IsBetterFinalityUpdate(update4, update3), "update4 should be better than update3")
-	// update4 should be valid for broadcast - meaning it should be broadcasted
-	require.Equal(t, true, lightClient.IsFinalityUpdateValidForBroadcast(update4, lcStore.LastFinalityUpdate()), "update4 should be valid for broadcast")
-
-	lcStore.SetLastFinalityUpdate(update4, true)
-	require.Equal(t, update4, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
-	require.Equal(t, true, p2p.BroadcastCalled.Load(), "Broadcast should have been called after a new finality update with increased finality slot")
-	p2p.BroadcastCalled.Store(false) // Reset for next test
-
-	// update 5 with the same new finality slot, increased attested slot, and supermajority - should save but not broadcast
-	l5 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedFinalizedSlot(1), util.WithIncreasedAttestedSlot(2), util.WithSupermajority())
-	update5, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l5.Ctx, l5.State, l5.Block, l5.AttestedState, l5.AttestedBlock, l5.FinalizedBlock)
-	require.NoError(t, err, "Failed to create light client finality update")
-
-	require.Equal(t, true, lightClient.IsBetterFinalityUpdate(update5, update4), "update5 should be better than update4")
-	// update5 should not be valid for broadcast - meaning it should not be broadcasted
-	require.Equal(t, false, lightClient.IsFinalityUpdateValidForBroadcast(update5, lcStore.LastFinalityUpdate()), "update5 should not be valid for broadcast")
-
-	lcStore.SetLastFinalityUpdate(update5, true)
-	require.Equal(t, update5, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
-	require.Equal(t, false, p2p.BroadcastCalled.Load(), "Broadcast should not have been called when previous was already broadcast with supermajority")
-
-	// update 6 with the same new finality slot, increased attested slot, and no supermajority - should save but not broadcast
-	l6 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedFinalizedSlot(1), util.WithIncreasedAttestedSlot(3))
-	update6, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l6.Ctx, l6.State, l6.Block, l6.AttestedState, l6.AttestedBlock, l6.FinalizedBlock)
-	require.NoError(t, err, "Failed to create light client finality update")
-
-	require.Equal(t, true, lightClient.IsBetterFinalityUpdate(update6, update5), "update6 should be better than update5")
-	// update6 should not be valid for broadcast - meaning it should not be broadcasted
-	require.Equal(t, false, lightClient.IsFinalityUpdateValidForBroadcast(update6, lcStore.LastFinalityUpdate()), "update6 should not be valid for broadcast")
-
-	lcStore.SetLastFinalityUpdate(update6, true)
-	require.Equal(t, update6, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
-	require.Equal(t, false, p2p.BroadcastCalled.Load(), "Broadcast should not have been called when previous was already broadcast with supermajority")
-}

beacon-chain/core/peerdas/BUILD.bazel

@@ -19,11 +19,11 @@ go_library(
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",
-        "//consensus-types/interfaces:go_default_library",
         "//consensus-types/primitives:go_default_library",
         "//container/trie:go_default_library",
         "//crypto/hash:go_default_library",
         "//encoding/bytesutil:go_default_library",
+        "//proto/engine/v1:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
         "//runtime/version:go_default_library",
         "@com_github_ethereum_go_ethereum//p2p/enode:go_default_library",

beacon-chain/core/peerdas/das_core.go

@@ -4,15 +4,10 @@ import (
 	"encoding/binary"
 	"math"
 	"slices"
-	"time"
 
-	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
 	"github.com/OffchainLabs/prysm/v6/config/params"
-	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
-	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/crypto/hash"
 	"github.com/OffchainLabs/prysm/v6/encoding/bytesutil"
-	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/holiman/uint256"
 	"github.com/pkg/errors"
@@ -20,12 +15,9 @@ import (
 
 var (
 	// Custom errors
-	ErrCustodyGroupTooLarge               = errors.New("custody group too large")
-	ErrCustodyGroupCountTooLarge          = errors.New("custody group count too large")
-	ErrSizeMismatch                       = errors.New("mismatch in the number of blob KZG commitments and cellsAndProofs")
-	ErrNotEnoughDataColumnSidecars        = errors.New("not enough columns")
-	ErrDataColumnSidecarsNotSortedByIndex = errors.New("data column sidecars are not sorted by index")
-	errWrongComputedCustodyGroupCount     = errors.New("wrong computed custody group count, should never happen")
+	ErrCustodyGroupTooLarge           = errors.New("custody group too large")
+	ErrCustodyGroupCountTooLarge      = errors.New("custody group count too large")
+	errWrongComputedCustodyGroupCount = errors.New("wrong computed custody group count, should never happen")
 
 	// maxUint256 is the maximum value of an uint256.
 	maxUint256 = &uint256.Int{math.MaxUint64, math.MaxUint64, math.MaxUint64, math.MaxUint64}
@@ -117,44 +109,6 @@ func ComputeColumnsForCustodyGroup(custodyGroup uint64) ([]uint64, error) {
 	return columns, nil
 }
 
-// DataColumnSidecars computes the data column sidecars from the signed block, cells and cell proofs.
-// The returned value contains pointers to function parameters.
-// (If the caller alterates `cellsAndProofs` afterwards, the returned value will be modified as well.)
-// https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/validator.md#get_data_column_sidecars_from_block
-func DataColumnSidecars(signedBlock interfaces.ReadOnlySignedBeaconBlock, cellsAndProofs []kzg.CellsAndProofs) ([]*ethpb.DataColumnSidecar, error) {
-	if signedBlock == nil || signedBlock.IsNil() || len(cellsAndProofs) == 0 {
-		return nil, nil
-	}
-
-	block := signedBlock.Block()
-	blockBody := block.Body()
-	blobKzgCommitments, err := blockBody.BlobKzgCommitments()
-	if err != nil {
-		return nil, errors.Wrap(err, "blob KZG commitments")
-	}
-
-	if len(blobKzgCommitments) != len(cellsAndProofs) {
-		return nil, ErrSizeMismatch
-	}
-
-	signedBlockHeader, err := signedBlock.Header()
-	if err != nil {
-		return nil, errors.Wrap(err, "signed block header")
-	}
-
-	kzgCommitmentsInclusionProof, err := blocks.MerkleProofKZGCommitments(blockBody)
-	if err != nil {
-		return nil, errors.Wrap(err, "merkle proof KZG commitments")
-	}
-
-	dataColumnSidecars, err := dataColumnsSidecars(signedBlockHeader, blobKzgCommitments, kzgCommitmentsInclusionProof, cellsAndProofs)
-	if err != nil {
-		return nil, errors.Wrap(err, "data column sidecars")
-	}
-
-	return dataColumnSidecars, nil
-}
-
 // ComputeCustodyGroupForColumn computes the custody group for a given column.
 // It is the reciprocal function of ComputeColumnsForCustodyGroup.
 func ComputeCustodyGroupForColumn(columnIndex uint64) (uint64, error) {
@@ -194,72 +148,3 @@ func CustodyColumns(custodyGroups []uint64) (map[uint64]bool, error) {
 
 	return columns, nil
 }
-
-// dataColumnsSidecars computes the data column sidecars from the signed block header, the blob KZG commiments,
-// the KZG commitment includion proofs and cells and cell proofs.
-// The returned value contains pointers to function parameters.
-// (If the caller alterates input parameters afterwards, the returned value will be modified as well.)
-// https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/validator.md#get_data_column_sidecars
-func dataColumnsSidecars(
-	signedBlockHeader *ethpb.SignedBeaconBlockHeader,
-	blobKzgCommitments [][]byte,
-	kzgCommitmentsInclusionProof [][]byte,
-	cellsAndProofs []kzg.CellsAndProofs,
-) ([]*ethpb.DataColumnSidecar, error) {
-	start := time.Now()
-	if len(blobKzgCommitments) != len(cellsAndProofs) {
-		return nil, ErrSizeMismatch
-	}
-
-	numberOfColumns := params.BeaconConfig().NumberOfColumns
-
-	blobsCount := len(cellsAndProofs)
-	sidecars := make([]*ethpb.DataColumnSidecar, 0, numberOfColumns)
-	for columnIndex := range numberOfColumns {
-		column := make([]kzg.Cell, 0, blobsCount)
-		kzgProofOfColumn := make([]kzg.Proof, 0, blobsCount)
-
-		for rowIndex := range blobsCount {
-			cellsForRow := cellsAndProofs[rowIndex].Cells
-			proofsForRow := cellsAndProofs[rowIndex].Proofs
-
-			// Validate that we have enough cells and proofs for this column index
-			if columnIndex >= uint64(len(cellsForRow)) {
-				return nil, errors.Errorf("column index %d exceeds cells length %d for blob %d", columnIndex, len(cellsForRow), rowIndex)
-			}
-			if columnIndex >= uint64(len(proofsForRow)) {
-				return nil, errors.Errorf("column index %d exceeds proofs length %d for blob %d", columnIndex, len(proofsForRow), rowIndex)
-			}
-
-			cell := cellsForRow[columnIndex]
-			column = append(column, cell)
-
-			kzgProof := proofsForRow[columnIndex]
-			kzgProofOfColumn = append(kzgProofOfColumn, kzgProof)
-		}
-
-		columnBytes := make([][]byte, 0, blobsCount)
-		for i := range column {
-			columnBytes = append(columnBytes, column[i][:])
-		}
-
-		kzgProofOfColumnBytes := make([][]byte, 0, blobsCount)
-		for _, kzgProof := range kzgProofOfColumn {
-			kzgProofOfColumnBytes = append(kzgProofOfColumnBytes, kzgProof[:])
-		}
-
-		sidecar := &ethpb.DataColumnSidecar{
-			Index:                        columnIndex,
-			Column:                       columnBytes,
-			KzgCommitments:               blobKzgCommitments,
-			KzgProofs:                    kzgProofOfColumnBytes,
-			SignedBlockHeader:            signedBlockHeader,
-			KzgCommitmentsInclusionProof: kzgCommitmentsInclusionProof,
-		}
-
-		sidecars = append(sidecars, sidecar)
-	}
-
-	dataColumnComputationTime.Observe(float64(time.Since(start).Milliseconds()))
-	return sidecars, nil
-}

beacon-chain/core/peerdas/das_core_test.go

@@ -3,13 +3,9 @@ package peerdas_test
 import (
 	"testing"
 
-	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	"github.com/OffchainLabs/prysm/v6/config/params"
-	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
-	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v6/testing/require"
-	"github.com/OffchainLabs/prysm/v6/testing/util"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 )
 
@@ -31,93 +27,6 @@ func TestComputeColumnsForCustodyGroup(t *testing.T) {
 	require.ErrorIs(t, err, peerdas.ErrCustodyGroupTooLarge)
 }
 
-func TestDataColumnSidecars(t *testing.T) {
-	t.Run("nil signed block", func(t *testing.T) {
-		var expected []*ethpb.DataColumnSidecar = nil
-		actual, err := peerdas.DataColumnSidecars(nil, []kzg.CellsAndProofs{})
-		require.NoError(t, err)
-
-		require.DeepSSZEqual(t, expected, actual)
-	})
-
-	t.Run("empty cells and proofs", func(t *testing.T) {
-		// Create a protobuf signed beacon block.
-		signedBeaconBlockPb := util.NewBeaconBlockDeneb()
-
-		// Create a signed beacon block from the protobuf.
-		signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
-		require.NoError(t, err)
-
-		actual, err := peerdas.DataColumnSidecars(signedBeaconBlock, []kzg.CellsAndProofs{})
-		require.NoError(t, err)
-		require.IsNil(t, actual)
-	})
-
-	t.Run("sizes mismatch", func(t *testing.T) {
-		// Create a protobuf signed beacon block.
-		signedBeaconBlockPb := util.NewBeaconBlockDeneb()
-
-		// Create a signed beacon block from the protobuf.
-		signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
-		require.NoError(t, err)
-
-		// Create cells and proofs.
-		cellsAndProofs := make([]kzg.CellsAndProofs, 1)
-
-		_, err = peerdas.DataColumnSidecars(signedBeaconBlock, cellsAndProofs)
-		require.ErrorIs(t, err, peerdas.ErrSizeMismatch)
-	})
-
-	t.Run("cells array too short for column index", func(t *testing.T) {
-		// Create a Fulu block with a blob commitment.
-		signedBeaconBlockPb := util.NewBeaconBlockFulu()
-		signedBeaconBlockPb.Block.Body.BlobKzgCommitments = [][]byte{make([]byte, 48)}
-
-		// Create a signed beacon block from the protobuf.
-		signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
-		require.NoError(t, err)
-
-		// Create cells and proofs with insufficient cells for the number of columns.
-		// This simulates a scenario where cellsAndProofs has fewer cells than expected columns.
-		cellsAndProofs := []kzg.CellsAndProofs{
-			{
-				Cells:  make([]kzg.Cell, 10),  // Only 10 cells
-				Proofs: make([]kzg.Proof, 10), // Only 10 proofs
-			},
-		}
-
-		// This should fail because the function will try to access columns up to NumberOfColumns
-		// but we only have 10 cells/proofs.
-		_, err = peerdas.DataColumnSidecars(signedBeaconBlock, cellsAndProofs)
-		require.ErrorContains(t, "column index", err)
-		require.ErrorContains(t, "exceeds cells length", err)
-	})
-
-	t.Run("proofs array too short for column index", func(t *testing.T) {
-		// Create a Fulu block with a blob commitment.
-		signedBeaconBlockPb := util.NewBeaconBlockFulu()
-		signedBeaconBlockPb.Block.Body.BlobKzgCommitments = [][]byte{make([]byte, 48)}
-
-		// Create a signed beacon block from the protobuf.
-		signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
-		require.NoError(t, err)
-
-		// Create cells and proofs with sufficient cells but insufficient proofs.
-		numberOfColumns := params.BeaconConfig().NumberOfColumns
-		cellsAndProofs := []kzg.CellsAndProofs{
-			{
-				Cells:  make([]kzg.Cell, numberOfColumns),
-				Proofs: make([]kzg.Proof, 5), // Only 5 proofs, less than columns
-			},
-		}
-
-		// This should fail when trying to access proof beyond index 4.
-		_, err = peerdas.DataColumnSidecars(signedBeaconBlock, cellsAndProofs)
-		require.ErrorContains(t, "column index", err)
-		require.ErrorContains(t, "exceeds proofs length", err)
-	})
-}
-
 func TestComputeCustodyGroupForColumn(t *testing.T) {
 	params.SetupTestConfigCleanup(t)
 	config := params.BeaconConfig()

beacon-chain/core/peerdas/p2p_interface_test.go

@@ -63,17 +63,14 @@ func TestVerifyDataColumnSidecarKZGProofs(t *testing.T) {
 	t.Run("invalid proof", func(t *testing.T) {
 		sidecars := generateRandomSidecars(t, seed, blobCount)
 		sidecars[0].Column[0][0]++ // It is OK to overflow
-		roDataColumnSidecars := generateRODataColumnSidecars(t, sidecars)
 
-		err := peerdas.VerifyDataColumnsSidecarKZGProofs(roDataColumnSidecars)
+		err := peerdas.VerifyDataColumnsSidecarKZGProofs(sidecars)
 		require.ErrorIs(t, err, peerdas.ErrInvalidKZGProof)
 	})
 
 	t.Run("nominal", func(t *testing.T) {
 		sidecars := generateRandomSidecars(t, seed, blobCount)
-		roDataColumnSidecars := generateRODataColumnSidecars(t, sidecars)
-
-		err := peerdas.VerifyDataColumnsSidecarKZGProofs(roDataColumnSidecars)
+		err := peerdas.VerifyDataColumnsSidecarKZGProofs(sidecars)
 		require.NoError(t, err)
 	})
 }
@@ -256,9 +253,8 @@ func BenchmarkVerifyDataColumnSidecarKZGProofs_SameCommitments_NoBatch(b *testin
 	for i := range int64(b.N) {
 		// Generate new random sidecars to ensure the KZG backend does not cache anything.
 		sidecars := generateRandomSidecars(b, i, blobCount)
-		roDataColumnSidecars := generateRODataColumnSidecars(b, sidecars)
 
-		for _, sidecar := range roDataColumnSidecars {
+		for _, sidecar := range sidecars {
 			sidecars := []blocks.RODataColumn{sidecar}
 			b.StartTimer()
 			err := peerdas.VerifyDataColumnsSidecarKZGProofs(sidecars)
@@ -282,7 +278,7 @@ func BenchmarkVerifyDataColumnSidecarKZGProofs_DiffCommitments_Batch(b *testing.
 			b.ResetTimer()
 
 			for j := range int64(b.N) {
-				allSidecars := make([]*ethpb.DataColumnSidecar, 0, numberOfColumns)
+				allSidecars := make([]blocks.RODataColumn, 0, numberOfColumns)
 				for k := int64(0); k < numberOfColumns; k += columnsCount {
 					// Use different seeds to generate different blobs/commitments
 					seed := int64(b.N*i) + numberOfColumns*j + blobCount*k
@@ -292,10 +288,8 @@ func BenchmarkVerifyDataColumnSidecarKZGProofs_DiffCommitments_Batch(b *testing.
 					allSidecars = append(allSidecars, sidecars[k:k+columnsCount]...)
 				}
 
-				roDataColumnSidecars := generateRODataColumnSidecars(b, allSidecars)
-
 				b.StartTimer()
-				err := peerdas.VerifyDataColumnsSidecarKZGProofs(roDataColumnSidecars)
+				err := peerdas.VerifyDataColumnsSidecarKZGProofs(allSidecars)
 				b.StopTimer()
 				require.NoError(b, err)
 			}
@@ -323,8 +317,7 @@ func BenchmarkVerifyDataColumnSidecarKZGProofs_DiffCommitments_Batch4(b *testing
 		for j := range int64(batchCount) {
 			// Use different seeds to generate different blobs/commitments
 			sidecars := generateRandomSidecars(b, int64(batchCount)*i+j*blobCount, blobCount)
-			roDataColumnSidecars := generateRODataColumnSidecars(b, sidecars[:columnsCount])
-			allSidecars = append(allSidecars, roDataColumnSidecars)
+			allSidecars = append(allSidecars, sidecars)
 		}
 
 		for _, sidecars := range allSidecars {
@@ -358,7 +351,7 @@ func createTestSidecar(t *testing.T, index uint64, column, kzgCommitments, kzgPr
 	return roSidecar
 }
 
-func generateRandomSidecars(t testing.TB, seed, blobCount int64) []*ethpb.DataColumnSidecar {
+func generateRandomSidecars(t testing.TB, seed, blobCount int64) []blocks.RODataColumn {
 	dbBlock := util.NewBeaconBlockDeneb()
 
 	commitments := make([][]byte, 0, blobCount)
@@ -379,20 +372,10 @@ func generateRandomSidecars(t testing.TB, seed, blobCount int64) []*ethpb.DataCo
 	require.NoError(t, err)
 
 	cellsAndProofs := util.GenerateCellsAndProofs(t, blobs)
-	sidecars, err := peerdas.DataColumnSidecars(sBlock, cellsAndProofs)
+	rob, err := blocks.NewROBlock(sBlock)
+	require.NoError(t, err)
+	sidecars, err := peerdas.DataColumnSidecars(cellsAndProofs, peerdas.PopulateFromBlock(rob))
 	require.NoError(t, err)
 
 	return sidecars
 }
-
-func generateRODataColumnSidecars(t testing.TB, sidecars []*ethpb.DataColumnSidecar) []blocks.RODataColumn {
-	roDataColumnSidecars := make([]blocks.RODataColumn, 0, len(sidecars))
-	for _, sidecar := range sidecars {
-		roCol, err := blocks.NewRODataColumn(sidecar)
-		require.NoError(t, err)
-
-		roDataColumnSidecars = append(roDataColumnSidecars, roCol)
-	}
-
-	return roDataColumnSidecars
-}

beacon-chain/core/peerdas/reconstruction.go

@@ -5,7 +5,7 @@ import (
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
-	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
+	pb "github.com/OffchainLabs/prysm/v6/proto/engine/v1"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/pkg/errors"
 	"golang.org/x/sync/errgroup"
@@ -16,6 +16,7 @@ var (
 	ErrBlobIndexTooHigh         = errors.New("blob index is too high")
 	ErrBlockRootMismatch        = errors.New("block root mismatch")
 	ErrBlobsCellsProofsMismatch = errors.New("blobs and cells proofs mismatch")
+	ErrNilBlobAndProof          = errors.New("nil blob and proof")
 )
 
 // MinimumColumnCountToReconstruct return the minimum number of columns needed to proceed to a reconstruction.
@@ -28,19 +29,19 @@ func MinimumColumnCountToReconstruct() uint64 {
 // ReconstructDataColumnSidecars reconstructs all the data column sidecars from the given input data column sidecars.
 // All input sidecars must be committed to the same block.
 // `inVerifiedRoSidecars` should contain enough (unique) sidecars to reconstruct the missing columns.
-func ReconstructDataColumnSidecars(inVerifiedRoSidecars []blocks.VerifiedRODataColumn) ([]blocks.VerifiedRODataColumn, error) {
+func ReconstructDataColumnSidecars(verifiedRoSidecars []blocks.VerifiedRODataColumn) ([]blocks.VerifiedRODataColumn, error) {
 	// Check if there is at least one input sidecar.
-	if len(inVerifiedRoSidecars) == 0 {
+	if len(verifiedRoSidecars) == 0 {
 		return nil, ErrNotEnoughDataColumnSidecars
 	}
 
 	// Safely retrieve the first sidecar as a reference.
-	referenceSidecar := inVerifiedRoSidecars[0]
+	referenceSidecar := verifiedRoSidecars[0]
 
 	// Check if all columns have the same length and are commmitted to the same block.
 	blobCount := len(referenceSidecar.Column)
 	blockRoot := referenceSidecar.BlockRoot()
-	for _, sidecar := range inVerifiedRoSidecars[1:] {
+	for _, sidecar := range verifiedRoSidecars[1:] {
 		if len(sidecar.Column) != blobCount {
 			return nil, ErrColumnLengthsDiffer
 		}
@@ -51,8 +52,8 @@ func ReconstructDataColumnSidecars(inVerifiedRoSidecars []blocks.VerifiedRODataC
 	}
 
 	// Deduplicate sidecars.
-	sidecarByIndex := make(map[uint64]blocks.VerifiedRODataColumn, len(inVerifiedRoSidecars))
-	for _, inVerifiedRoSidecar := range inVerifiedRoSidecars {
+	sidecarByIndex := make(map[uint64]blocks.VerifiedRODataColumn, len(verifiedRoSidecars))
+	for _, inVerifiedRoSidecar := range verifiedRoSidecars {
 		sidecarByIndex[inVerifiedRoSidecar.Index] = inVerifiedRoSidecar
 	}
 
@@ -62,12 +63,6 @@ func ReconstructDataColumnSidecars(inVerifiedRoSidecars []blocks.VerifiedRODataC
 		return nil, ErrNotEnoughDataColumnSidecars
 	}
 
-	// Sidecars are verified and are committed to the same block.
-	// All signed block headers, KZG commitments, and inclusion proofs are the same.
-	signedBlockHeader := referenceSidecar.SignedBlockHeader
-	kzgCommitments := referenceSidecar.KzgCommitments
-	kzgCommitmentsInclusionProof := referenceSidecar.KzgCommitmentsInclusionProof
-
 	// Recover cells and compute proofs in parallel.
 	var wg errgroup.Group
 	cellsAndProofs := make([]kzg.CellsAndProofs, blobCount)
@@ -100,78 +95,20 @@ func ReconstructDataColumnSidecars(inVerifiedRoSidecars []blocks.VerifiedRODataC
 		return nil, errors.Wrap(err, "wait for RecoverCellsAndKZGProofs")
 	}
 
-	outSidecars, err := dataColumnsSidecars(signedBlockHeader, kzgCommitments, kzgCommitmentsInclusionProof, cellsAndProofs)
+	outSidecars, err := DataColumnSidecars(cellsAndProofs, PopulateFromSidecar(referenceSidecar))
 	if err != nil {
 		return nil, errors.Wrap(err, "data column sidecars from items")
 	}
 
 	// Input sidecars are verified, and we reconstructed ourselves the missing sidecars.
 	// As a consequence, reconstructed sidecars are also verified.
-	outVerifiedRoSidecars := make([]blocks.VerifiedRODataColumn, 0, len(outSidecars))
+	reconstructedVerifiedRoSidecars := make([]blocks.VerifiedRODataColumn, 0, len(outSidecars))
 	for _, sidecar := range outSidecars {
-		roSidecar, err := blocks.NewRODataColumnWithRoot(sidecar, blockRoot)
-		if err != nil {
-			return nil, errors.Wrap(err, "new RO data column with root")
-		}
-
-		verifiedRoSidecar := blocks.NewVerifiedRODataColumn(roSidecar)
-		outVerifiedRoSidecars = append(outVerifiedRoSidecars, verifiedRoSidecar)
+		verifiedRoSidecar := blocks.NewVerifiedRODataColumn(sidecar)
+		reconstructedVerifiedRoSidecars = append(reconstructedVerifiedRoSidecars, verifiedRoSidecar)
 	}
 
-	return outVerifiedRoSidecars, nil
-}
-
-// ConstructDataColumnSidecars constructs data column sidecars from a block, (un-extended) blobs and
-// cell proofs corresponding the extended blobs. The main purpose of this function is to
-// construct data column sidecars from data obtained from the execution client via:
-// - `engine_getBlobsV2` - https://github.com/ethereum/execution-apis/blob/main/src/engine/osaka.md#engine_getblobsv2, or
-// - `engine_getPayloadV5` - https://github.com/ethereum/execution-apis/blob/main/src/engine/osaka.md#engine_getpayloadv5
-// Note: In this function, to stick with the `BlobsBundleV2` format returned by the execution client in `engine_getPayloadV5`,
-// cell proofs are "flattened".
-func ConstructDataColumnSidecars(block interfaces.ReadOnlySignedBeaconBlock, blobs [][]byte, cellProofs [][]byte) ([]*ethpb.DataColumnSidecar, error) {
-	// Check if the cells count is equal to the cell proofs count.
-	numberOfColumns := params.BeaconConfig().NumberOfColumns
-	blobCount := uint64(len(blobs))
-	cellProofsCount := uint64(len(cellProofs))
-
-	cellsCount := blobCount * numberOfColumns
-	if cellsCount != cellProofsCount {
-		return nil, ErrBlobsCellsProofsMismatch
-	}
-
-	cellsAndProofs := make([]kzg.CellsAndProofs, 0, blobCount)
-	for i, blob := range blobs {
-		var kzgBlob kzg.Blob
-		if copy(kzgBlob[:], blob) != len(kzgBlob) {
-			return nil, errors.New("wrong blob size - should never happen")
-		}
-
-		// Compute the extended cells from the (non-extended) blob.
-		cells, err := kzg.ComputeCells(&kzgBlob)
-		if err != nil {
-			return nil, errors.Wrap(err, "compute cells")
-		}
-
-		var proofs []kzg.Proof
-		for idx := uint64(i) * numberOfColumns; idx < (uint64(i)+1)*numberOfColumns; idx++ {
-			var kzgProof kzg.Proof
-			if copy(kzgProof[:], cellProofs[idx]) != len(kzgProof) {
-				return nil, errors.New("wrong KZG proof size - should never happen")
-			}
-
-			proofs = append(proofs, kzgProof)
-		}
-
-		cellsProofs := kzg.CellsAndProofs{Cells: cells, Proofs: proofs}
-		cellsAndProofs = append(cellsAndProofs, cellsProofs)
-	}
-
-	dataColumnSidecars, err := DataColumnSidecars(block, cellsAndProofs)
-	if err != nil {
-		return nil, errors.Wrap(err, "data column sidcars")
-	}
-
-	return dataColumnSidecars, nil
+	return reconstructedVerifiedRoSidecars, nil
 }
 
 // ReconstructBlobs constructs verified read only blobs sidecars from verified read only blob sidecars.
@@ -256,6 +193,89 @@ func ReconstructBlobs(block blocks.ROBlock, verifiedDataColumnSidecars []blocks.
 	return blobSidecars, nil
 }
 
+// ComputeCellsAndProofsFromFlat computes the cells and proofs from blobs and cell flat proofs.
+func ComputeCellsAndProofsFromFlat(blobs [][]byte, cellProofs [][]byte) ([]kzg.CellsAndProofs, error) {
+	numberOfColumns := params.BeaconConfig().NumberOfColumns
+	blobCount := uint64(len(blobs))
+	cellProofsCount := uint64(len(cellProofs))
+
+	cellsCount := blobCount * numberOfColumns
+	if cellsCount != cellProofsCount {
+		return nil, ErrBlobsCellsProofsMismatch
+	}
+
+	cellsAndProofs := make([]kzg.CellsAndProofs, 0, blobCount)
+	for i, blob := range blobs {
+		var kzgBlob kzg.Blob
+		if copy(kzgBlob[:], blob) != len(kzgBlob) {
+			return nil, errors.New("wrong blob size - should never happen")
+		}
+
+		// Compute the extended cells from the (non-extended) blob.
+		cells, err := kzg.ComputeCells(&kzgBlob)
+		if err != nil {
+			return nil, errors.Wrap(err, "compute cells")
+		}
+
+		var proofs []kzg.Proof
+		for idx := uint64(i) * numberOfColumns; idx < (uint64(i)+1)*numberOfColumns; idx++ {
+			var kzgProof kzg.Proof
+			if copy(kzgProof[:], cellProofs[idx]) != len(kzgProof) {
+				return nil, errors.New("wrong KZG proof size - should never happen")
+			}
+
+			proofs = append(proofs, kzgProof)
+		}
+
+		cellsProofs := kzg.CellsAndProofs{Cells: cells, Proofs: proofs}
+		cellsAndProofs = append(cellsAndProofs, cellsProofs)
+	}
+
+	return cellsAndProofs, nil
+}
+
+// ComputeCellsAndProofs computes the cells and proofs from blobs and cell proofs.
+func ComputeCellsAndProofsFromStructured(blobsAndProofs []*pb.BlobAndProofV2) ([]kzg.CellsAndProofs, error) {
+	numberOfColumns := params.BeaconConfig().NumberOfColumns
+
+	cellsAndProofs := make([]kzg.CellsAndProofs, 0, len(blobsAndProofs))
+	for _, blobAndProof := range blobsAndProofs {
+		if blobAndProof == nil {
+			return nil, ErrNilBlobAndProof
+		}
+
+		var kzgBlob kzg.Blob
+		if copy(kzgBlob[:], blobAndProof.Blob) != len(kzgBlob) {
+			return nil, errors.New("wrong blob size - should never happen")
+		}
+
+		// Compute the extended cells from the (non-extended) blob.
+		cells, err := kzg.ComputeCells(&kzgBlob)
+		if err != nil {
+			return nil, errors.Wrap(err, "compute cells")
+		}
+
+		kzgProofs := make([]kzg.Proof, 0, numberOfColumns*kzg.BytesPerProof)
+		for _, kzgProofBytes := range blobAndProof.KzgProofs {
+			if len(kzgProofBytes) != kzg.BytesPerProof {
+				return nil, errors.New("wrong KZG proof size - should never happen")
+			}
+
+			var kzgProof kzg.Proof
+			if copy(kzgProof[:], kzgProofBytes) != len(kzgProof) {
+				return nil, errors.New("wrong copied KZG proof size - should never happen")
+			}
+
+			kzgProofs = append(kzgProofs, kzgProof)
+		}
+
+		cellsProofs := kzg.CellsAndProofs{Cells: cells, Proofs: kzgProofs}
+		cellsAndProofs = append(cellsAndProofs, cellsProofs)
+	}
+
+	return cellsAndProofs, nil
+}
+
 // blobSidecarsFromDataColumnSidecars converts verified data column sidecars to verified blob sidecars.
 func blobSidecarsFromDataColumnSidecars(roBlock blocks.ROBlock, dataColumnSidecars []blocks.VerifiedRODataColumn, indices []int) ([]*blocks.VerifiedROBlob, error) {
 	referenceSidecar := dataColumnSidecars[0]

beacon-chain/core/peerdas/reconstruction_test.go

@@ -9,7 +9,7 @@ import (
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
-	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
+	pb "github.com/OffchainLabs/prysm/v6/proto/engine/v1"
 	"github.com/OffchainLabs/prysm/v6/testing/require"
 	"github.com/OffchainLabs/prysm/v6/testing/util"
 	"github.com/pkg/errors"
@@ -124,50 +124,6 @@ func TestReconstructDataColumnSidecars(t *testing.T) {
 	})
 }
 
-func TestConstructDataColumnSidecars(t *testing.T) {
-	const (
-		blobCount    = 3
-		cellsPerBlob = fieldparams.CellsPerBlob
-	)
-
-	numberOfColumns := params.BeaconConfig().NumberOfColumns
-
-	// Start the trusted setup.
-	err := kzg.Start()
-	require.NoError(t, err)
-
-	roBlock, _, baseVerifiedRoSidecars := util.GenerateTestFuluBlockWithSidecars(t, blobCount)
-
-	// Extract blobs and proofs from the sidecars.
-	blobs := make([][]byte, 0, blobCount)
-	cellProofs := make([][]byte, 0, cellsPerBlob)
-	for blobIndex := range blobCount {
-		blob := make([]byte, 0, cellsPerBlob)
-		for columnIndex := range cellsPerBlob {
-			cell := baseVerifiedRoSidecars[columnIndex].Column[blobIndex]
-			blob = append(blob, cell...)
-		}
-
-		blobs = append(blobs, blob)
-
-		for columnIndex := range numberOfColumns {
-			cellProof := baseVerifiedRoSidecars[columnIndex].KzgProofs[blobIndex]
-			cellProofs = append(cellProofs, cellProof)
-		}
-	}
-
-	actual, err := peerdas.ConstructDataColumnSidecars(roBlock, blobs, cellProofs)
-	require.NoError(t, err)
-
-	// Extract the base verified ro sidecars into sidecars.
-	expected := make([]*ethpb.DataColumnSidecar, 0, len(baseVerifiedRoSidecars))
-	for _, verifiedRoSidecar := range baseVerifiedRoSidecars {
-		expected = append(expected, verifiedRoSidecar.DataColumnSidecar)
-	}
-
-	require.DeepSSZEqual(t, expected, actual)
-}
-
 func TestReconstructBlobs(t *testing.T) {
 	// Start the trusted setup.
 	err := kzg.Start()
@@ -250,7 +206,7 @@ func TestReconstructBlobs(t *testing.T) {
 		// Compute cells and proofs from blob sidecars.
 		var wg errgroup.Group
 		blobs := make([][]byte, blobCount)
-		cellsAndProofs := make([]kzg.CellsAndProofs, blobCount)
+		inputCellsAndProofs := make([]kzg.CellsAndProofs, blobCount)
 		for i := range blobCount {
 			blob := roBlobSidecars[i].Blob
 			blobs[i] = blob
@@ -267,7 +223,7 @@ func TestReconstructBlobs(t *testing.T) {
 
 				// It is safe for multiple goroutines to concurrently write to the same slice,
 				// as long as they are writing to different indices, which is the case here.
-				cellsAndProofs[i] = cp
+				inputCellsAndProofs[i] = cp
 
 				return nil
 			})
@@ -278,25 +234,24 @@ func TestReconstructBlobs(t *testing.T) {
 
 		// Flatten proofs.
 		cellProofs := make([][]byte, 0, blobCount*numberOfColumns)
-		for _, cp := range cellsAndProofs {
+		for _, cp := range inputCellsAndProofs {
 			for _, proof := range cp.Proofs {
 				cellProofs = append(cellProofs, proof[:])
 			}
 		}
 
-		// Construct data column sidecars.
-		// It is OK to use the public function `ConstructDataColumnSidecars`, as long as
-		// `TestConstructDataColumnSidecars` tests pass.
-		dataColumnSidecars, err := peerdas.ConstructDataColumnSidecars(roBlock, blobs, cellProofs)
+		// Compute celles and proofs from the blobs and cell proofs.
+		cellsAndProofs, err := peerdas.ComputeCellsAndProofsFromFlat(blobs, cellProofs)
+		require.NoError(t, err)
+
+		// Construct data column sidears from the signed block and cells and proofs.
+		roDataColumnSidecars, err := peerdas.DataColumnSidecars(cellsAndProofs, peerdas.PopulateFromBlock(roBlock))
 		require.NoError(t, err)
 
 		// Convert to verified data column sidecars.
-		verifiedRoSidecars := make([]blocks.VerifiedRODataColumn, 0, len(dataColumnSidecars))
-		for _, dataColumnSidecar := range dataColumnSidecars {
-			roSidecar, err := blocks.NewRODataColumn(dataColumnSidecar)
-			require.NoError(t, err)
-
-			verifiedRoSidecar := blocks.NewVerifiedRODataColumn(roSidecar)
+		verifiedRoSidecars := make([]blocks.VerifiedRODataColumn, 0, len(roDataColumnSidecars))
+		for _, roDataColumnSidecar := range roDataColumnSidecars {
+			verifiedRoSidecar := blocks.NewVerifiedRODataColumn(roDataColumnSidecar)
 			verifiedRoSidecars = append(verifiedRoSidecars, verifiedRoSidecar)
 		}
 
@@ -339,3 +294,162 @@ func TestReconstructBlobs(t *testing.T) {
 	})
 
 }
+
+func TestComputeCellsAndProofsFromFlat(t *testing.T) {
+	// Start the trusted setup.
+	err := kzg.Start()
+	require.NoError(t, err)
+
+	t.Run("mismatched blob and proof counts", func(t *testing.T) {
+		numberOfColumns := params.BeaconConfig().NumberOfColumns
+
+		// Create one blob but proofs for two blobs
+		blobs := [][]byte{{}}
+
+		// Create proofs for 2 blobs worth of columns
+		cellProofs := make([][]byte, 2*numberOfColumns)
+
+		_, err := peerdas.ComputeCellsAndProofsFromFlat(blobs, cellProofs)
+		require.ErrorIs(t, err, peerdas.ErrBlobsCellsProofsMismatch)
+	})
+
+	t.Run("nominal", func(t *testing.T) {
+		const blobCount = 2
+		numberOfColumns := params.BeaconConfig().NumberOfColumns
+
+		// Generate test blobs
+		_, roBlobSidecars := util.GenerateTestElectraBlockWithSidecar(t, [fieldparams.RootLength]byte{}, 42, blobCount)
+
+		// Extract blobs and compute expected cells and proofs
+		blobs := make([][]byte, blobCount)
+		expectedCellsAndProofs := make([]kzg.CellsAndProofs, blobCount)
+		var wg errgroup.Group
+
+		for i := range blobCount {
+			blob := roBlobSidecars[i].Blob
+			blobs[i] = blob
+
+			wg.Go(func() error {
+				var kzgBlob kzg.Blob
+				count := copy(kzgBlob[:], blob)
+				require.Equal(t, len(kzgBlob), count)
+
+				cp, err := kzg.ComputeCellsAndKZGProofs(&kzgBlob)
+				if err != nil {
+					return errors.Wrapf(err, "compute cells and kzg proofs for blob %d", i)
+				}
+
+				expectedCellsAndProofs[i] = cp
+				return nil
+			})
+		}
+
+		err := wg.Wait()
+		require.NoError(t, err)
+
+		// Flatten proofs
+		cellProofs := make([][]byte, 0, blobCount*numberOfColumns)
+		for _, cp := range expectedCellsAndProofs {
+			for _, proof := range cp.Proofs {
+				cellProofs = append(cellProofs, proof[:])
+			}
+		}
+
+		// Test ComputeCellsAndProofs
+		actualCellsAndProofs, err := peerdas.ComputeCellsAndProofsFromFlat(blobs, cellProofs)
+		require.NoError(t, err)
+		require.Equal(t, blobCount, len(actualCellsAndProofs))
+
+		// Verify the results match expected
+		for i := range blobCount {
+			require.Equal(t, len(expectedCellsAndProofs[i].Cells), len(actualCellsAndProofs[i].Cells))
+			require.Equal(t, len(expectedCellsAndProofs[i].Proofs), len(actualCellsAndProofs[i].Proofs))
+
+			// Compare cells
+			for j, expectedCell := range expectedCellsAndProofs[i].Cells {
+				require.Equal(t, expectedCell, actualCellsAndProofs[i].Cells[j])
+			}
+
+			// Compare proofs
+			for j, expectedProof := range expectedCellsAndProofs[i].Proofs {
+				require.Equal(t, expectedProof, actualCellsAndProofs[i].Proofs[j])
+			}
+		}
+	})
+}
+
+func TestComputeCellsAndProofsFromStructured(t *testing.T) {
+	t.Run("nil blob and proof", func(t *testing.T) {
+		_, err := peerdas.ComputeCellsAndProofsFromStructured([]*pb.BlobAndProofV2{nil})
+		require.ErrorIs(t, err, peerdas.ErrNilBlobAndProof)
+	})
+
+	t.Run("nominal", func(t *testing.T) {
+		// Start the trusted setup.
+		err := kzg.Start()
+		require.NoError(t, err)
+
+		const blobCount = 2
+
+		// Generate test blobs
+		_, roBlobSidecars := util.GenerateTestElectraBlockWithSidecar(t, [fieldparams.RootLength]byte{}, 42, blobCount)
+
+		// Extract blobs and compute expected cells and proofs
+		blobsAndProofs := make([]*pb.BlobAndProofV2, blobCount)
+		expectedCellsAndProofs := make([]kzg.CellsAndProofs, blobCount)
+
+		var wg errgroup.Group
+		for i := range blobCount {
+			blob := roBlobSidecars[i].Blob
+
+			wg.Go(func() error {
+				var kzgBlob kzg.Blob
+				count := copy(kzgBlob[:], blob)
+				require.Equal(t, len(kzgBlob), count)
+
+				cellsAndProofs, err := kzg.ComputeCellsAndKZGProofs(&kzgBlob)
+				if err != nil {
+					return errors.Wrapf(err, "compute cells and kzg proofs for blob %d", i)
+				}
+				expectedCellsAndProofs[i] = cellsAndProofs
+
+				kzgProofs := make([][]byte, 0, len(cellsAndProofs.Proofs))
+				for _, proof := range cellsAndProofs.Proofs {
+					kzgProofs = append(kzgProofs, proof[:])
+				}
+
+				blobAndProof := &pb.BlobAndProofV2{
+					Blob:      blob,
+					KzgProofs: kzgProofs,
+				}
+				blobsAndProofs[i] = blobAndProof
+
+				return nil
+			})
+		}
+
+		err = wg.Wait()
+		require.NoError(t, err)
+
+		// Test ComputeCellsAndProofs
+		actualCellsAndProofs, err := peerdas.ComputeCellsAndProofsFromStructured(blobsAndProofs)
+		require.NoError(t, err)
+		require.Equal(t, blobCount, len(actualCellsAndProofs))
+
+		// Verify the results match expected
+		for i := range blobCount {
+			require.Equal(t, len(expectedCellsAndProofs[i].Cells), len(actualCellsAndProofs[i].Cells))
+			require.Equal(t, len(expectedCellsAndProofs[i].Proofs), len(actualCellsAndProofs[i].Proofs))
+
+			// Compare cells
+			for j, expectedCell := range expectedCellsAndProofs[i].Cells {
+				require.Equal(t, expectedCell, actualCellsAndProofs[i].Cells[j])
+			}
+
+			// Compare proofs
+			for j, expectedProof := range expectedCellsAndProofs[i].Proofs {
+				require.Equal(t, expectedProof, actualCellsAndProofs[i].Proofs[j])
+			}
+		}
+	})
+}

beacon-chain/core/peerdas/validator.go

@@ -1,12 +1,76 @@
 package peerdas
 
 import (
+	"time"
+
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
 	beaconState "github.com/OffchainLabs/prysm/v6/beacon-chain/state"
+	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
+	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/pkg/errors"
 )
 
+var (
+	ErrNilSignedBlockOrEmptyCellsAndProofs = errors.New("nil signed block or empty cells and proofs")
+	ErrSizeMismatch                        = errors.New("mismatch in the number of blob KZG commitments and cellsAndProofs")
+	ErrNotEnoughDataColumnSidecars         = errors.New("not enough columns")
+	ErrDataColumnSidecarsNotSortedByIndex  = errors.New("data column sidecars are not sorted by index")
+)
+
+var (
+	_ ConstructionPopulator = (*BlockReconstructionSource)(nil)
+	_ ConstructionPopulator = (*SidecarReconstructionSource)(nil)
+)
+
+const (
+	BlockType   = "BeaconBlock"
+	SidecarType = "DataColumnSidecar"
+)
+
+type (
+	// ConstructionPopulator is an interface that can be satisfied by a type that can use data from a struct
+	// like a DataColumnSidecar or a BeaconBlock to set the fields in a data column sidecar that cannot
+	// be obtained from the engine api.
+	ConstructionPopulator interface {
+		Slot() primitives.Slot
+		Root() [fieldparams.RootLength]byte
+		ProposerIndex() primitives.ValidatorIndex
+		Commitments() ([][]byte, error)
+		Type() string
+
+		extract() (*blockInfo, error)
+	}
+
+	// BlockReconstructionSource is a ConstructionPopulator that uses a beacon block as the source of data
+	BlockReconstructionSource struct {
+		blocks.ROBlock
+	}
+
+	// DataColumnSidecar is a ConstructionPopulator that uses a data column sidecar as the source of data
+	SidecarReconstructionSource struct {
+		blocks.VerifiedRODataColumn
+	}
+
+	blockInfo struct {
+		signedBlockHeader *ethpb.SignedBeaconBlockHeader
+		kzgCommitments    [][]byte
+		kzgInclusionProof [][]byte
+	}
+)
+
+// PopulateFromBlock creates a BlockReconstructionSource from a beacon block
+func PopulateFromBlock(block blocks.ROBlock) *BlockReconstructionSource {
+	return &BlockReconstructionSource{ROBlock: block}
+}
+
+// PopulateFromSidecar creates a SidecarReconstructionSource from a data column sidecar
+func PopulateFromSidecar(sidecar blocks.VerifiedRODataColumn) *SidecarReconstructionSource {
+	return &SidecarReconstructionSource{VerifiedRODataColumn: sidecar}
+}
+
 // ValidatorsCustodyRequirement returns the number of custody groups regarding the validator indices attached to the beacon node.
 // https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/validator.md#validator-custody
 func ValidatorsCustodyRequirement(state beaconState.ReadOnlyBeaconState, validatorsIndex map[primitives.ValidatorIndex]bool) (uint64, error) {
@@ -28,3 +92,159 @@ func ValidatorsCustodyRequirement(state beaconState.ReadOnlyBeaconState, validat
 	count := totalNodeBalance / balancePerAdditionalCustodyGroup
 	return min(max(count, validatorCustodyRequirement), numberOfCustodyGroups), nil
 }
+
+// DataColumnSidecars, given ConstructionPopulator and the cells/proofs associated with each blob in the
+// block, assembles sidecars which can be distributed to peers.
+// This is an adapted version of
+// https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/validator.md#get_data_column_sidecars,
+// which is designed to be used both when constructing sidecars from a block and from a sidecar, replacing
+// https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/validator.md#get_data_column_sidecars_from_block and
+// https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/validator.md#get_data_column_sidecars_from_column_sidecar
+func DataColumnSidecars(rows []kzg.CellsAndProofs, src ConstructionPopulator) ([]blocks.RODataColumn, error) {
+	if len(rows) == 0 {
+		return nil, nil
+	}
+	start := time.Now()
+	cells, proofs, err := rotateRowsToCols(rows, params.BeaconConfig().NumberOfColumns)
+	if err != nil {
+		return nil, errors.Wrap(err, "rotate cells and proofs")
+	}
+
+	maxIdx := params.BeaconConfig().NumberOfColumns
+	roSidecars := make([]blocks.RODataColumn, 0, maxIdx)
+	for idx := range maxIdx {
+		info, err := src.extract()
+		if err != nil {
+			return nil, errors.Wrap(err, "extract block info")
+		}
+
+		sidecar := &ethpb.DataColumnSidecar{
+			Index:                        idx,
+			Column:                       cells[idx],
+			KzgCommitments:               info.kzgCommitments,
+			KzgProofs:                    proofs[idx],
+			SignedBlockHeader:            info.signedBlockHeader,
+			KzgCommitmentsInclusionProof: info.kzgInclusionProof,
+		}
+
+		if len(sidecar.KzgCommitments) != len(sidecar.Column) || len(sidecar.KzgCommitments) != len(sidecar.KzgProofs) {
+			return nil, ErrSizeMismatch
+		}
+
+		roSidecar, err := blocks.NewRODataColumnWithRoot(sidecar, src.Root())
+		if err != nil {
+			return nil, errors.Wrap(err, "new ro data column")
+		}
+		roSidecars = append(roSidecars, roSidecar)
+	}
+
+	dataColumnComputationTime.Observe(float64(time.Since(start).Milliseconds()))
+	return roSidecars, nil
+}
+
+// Slot returns the slot of the source
+func (s *BlockReconstructionSource) Slot() primitives.Slot {
+	return s.Block().Slot()
+}
+
+// ProposerIndex returns the proposer index of the source
+func (s *BlockReconstructionSource) ProposerIndex() primitives.ValidatorIndex {
+	return s.Block().ProposerIndex()
+}
+
+// Commitments returns the blob KZG commitments of the source
+func (s *BlockReconstructionSource) Commitments() ([][]byte, error) {
+	c, err := s.Block().Body().BlobKzgCommitments()
+
+	if err != nil {
+		return nil, errors.Wrap(err, "blob KZG commitments")
+	}
+
+	return c, nil
+}
+
+// Type returns the type of the source
+func (s *BlockReconstructionSource) Type() string {
+	return BlockType
+}
+
+// extract extracts the block information from the source
+func (b *BlockReconstructionSource) extract() (*blockInfo, error) {
+	block := b.Block()
+
+	header, err := b.Header()
+	if err != nil {
+		return nil, errors.Wrap(err, "header")
+	}
+
+	commitments, err := block.Body().BlobKzgCommitments()
+	if err != nil {
+		return nil, errors.Wrap(err, "commitments")
+	}
+
+	inclusionProof, err := blocks.MerkleProofKZGCommitments(block.Body())
+	if err != nil {
+		return nil, errors.Wrap(err, "merkle proof kzg commitments")
+	}
+
+	info := &blockInfo{
+		signedBlockHeader: header,
+		kzgCommitments:    commitments,
+		kzgInclusionProof: inclusionProof,
+	}
+
+	return info, nil
+}
+
+// rotateRowsToCols takes a 2D slice of cells and proofs, where the x is rows (blobs) and y is columns,
+// and returns a 2D slice where x is columns and y is rows.
+func rotateRowsToCols(rows []kzg.CellsAndProofs, numCols uint64) ([][][]byte, [][][]byte, error) {
+	if len(rows) == 0 {
+		return nil, nil, nil
+	}
+	cellCols := make([][][]byte, numCols)
+	proofCols := make([][][]byte, numCols)
+	for i, cp := range rows {
+		if uint64(len(cp.Cells)) != numCols {
+			return nil, nil, errors.Wrap(ErrNotEnoughDataColumnSidecars, "not enough cells")
+		}
+		if len(cp.Cells) != len(cp.Proofs) {
+			return nil, nil, errors.Wrap(ErrNotEnoughDataColumnSidecars, "not enough proofs")
+		}
+		for j := uint64(0); j < numCols; j++ {
+			if i == 0 {
+				cellCols[j] = make([][]byte, len(rows))
+				proofCols[j] = make([][]byte, len(rows))
+			}
+			cellCols[j][i] = cp.Cells[j][:]
+			proofCols[j][i] = cp.Proofs[j][:]
+		}
+	}
+	return cellCols, proofCols, nil
+}
+
+// Root returns the block root of the source
+func (s *SidecarReconstructionSource) Root() [fieldparams.RootLength]byte {
+	return s.BlockRoot()
+}
+
+// Commmitments returns the blob KZG commitments of the source
+func (s *SidecarReconstructionSource) Commitments() ([][]byte, error) {
+	return s.KzgCommitments, nil
+}
+
+// Type returns the type of the source
+func (s *SidecarReconstructionSource) Type() string {
+	return SidecarType
+}
+
+// extract extracts the block information from the source
+func (s *SidecarReconstructionSource) extract() (*blockInfo, error) {
+	info := &blockInfo{
+		signedBlockHeader: s.SignedBlockHeader,
+		kzgCommitments:    s.KzgCommitments,
+		kzgInclusionProof: s.KzgCommitmentsInclusionProof,
+	}
+
+	return info, nil
+}

beacon-chain/core/peerdas/validator_test.go

@@ -3,11 +3,15 @@ package peerdas_test
 import (
 	"testing"
 
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	state_native "github.com/OffchainLabs/prysm/v6/beacon-chain/state/state-native"
+	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v6/testing/require"
+	"github.com/OffchainLabs/prysm/v6/testing/util"
 )
 
 func TestValidatorsCustodyRequirement(t *testing.T) {
@@ -53,3 +57,218 @@ func TestValidatorsCustodyRequirement(t *testing.T) {
 		})
 	}
 }
+
+func TestDataColumnSidecars(t *testing.T) {
+	t.Run("sizes mismatch", func(t *testing.T) {
+		// Create a protobuf signed beacon block.
+		signedBeaconBlockPb := util.NewBeaconBlockDeneb()
+
+		// Create a signed beacon block from the protobuf.
+		signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
+		require.NoError(t, err)
+
+		// Create cells and proofs.
+		cellsAndProofs := []kzg.CellsAndProofs{
+			{
+				Cells:  make([]kzg.Cell, params.BeaconConfig().NumberOfColumns),
+				Proofs: make([]kzg.Proof, params.BeaconConfig().NumberOfColumns),
+			},
+		}
+
+		rob, err := blocks.NewROBlock(signedBeaconBlock)
+		require.NoError(t, err)
+		_, err = peerdas.DataColumnSidecars(cellsAndProofs, peerdas.PopulateFromBlock(rob))
+		require.ErrorIs(t, err, peerdas.ErrSizeMismatch)
+	})
+
+	t.Run("cells array too short for column index", func(t *testing.T) {
+		// Create a Fulu block with a blob commitment.
+		signedBeaconBlockPb := util.NewBeaconBlockFulu()
+		signedBeaconBlockPb.Block.Body.BlobKzgCommitments = [][]byte{make([]byte, 48)}
+
+		// Create a signed beacon block from the protobuf.
+		signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
+		require.NoError(t, err)
+
+		// Create cells and proofs with insufficient cells for the number of columns.
+		// This simulates a scenario where cellsAndProofs has fewer cells than expected columns.
+		cellsAndProofs := []kzg.CellsAndProofs{
+			{
+				Cells:  make([]kzg.Cell, 10),  // Only 10 cells
+				Proofs: make([]kzg.Proof, 10), // Only 10 proofs
+			},
+		}
+
+		// This should fail because the function will try to access columns up to NumberOfColumns
+		// but we only have 10 cells/proofs.
+		rob, err := blocks.NewROBlock(signedBeaconBlock)
+		require.NoError(t, err)
+		_, err = peerdas.DataColumnSidecars(cellsAndProofs, peerdas.PopulateFromBlock(rob))
+		require.ErrorIs(t, err, peerdas.ErrNotEnoughDataColumnSidecars)
+	})
+
+	t.Run("proofs array too short for column index", func(t *testing.T) {
+		// Create a Fulu block with a blob commitment.
+		signedBeaconBlockPb := util.NewBeaconBlockFulu()
+		signedBeaconBlockPb.Block.Body.BlobKzgCommitments = [][]byte{make([]byte, 48)}
+
+		// Create a signed beacon block from the protobuf.
+		signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
+		require.NoError(t, err)
+
+		// Create cells and proofs with sufficient cells but insufficient proofs.
+		numberOfColumns := params.BeaconConfig().NumberOfColumns
+		cellsAndProofs := []kzg.CellsAndProofs{
+			{
+				Cells:  make([]kzg.Cell, numberOfColumns),
+				Proofs: make([]kzg.Proof, 5), // Only 5 proofs, less than columns
+			},
+		}
+
+		// This should fail when trying to access proof beyond index 4.
+		rob, err := blocks.NewROBlock(signedBeaconBlock)
+		require.NoError(t, err)
+		_, err = peerdas.DataColumnSidecars(cellsAndProofs, peerdas.PopulateFromBlock(rob))
+		require.ErrorIs(t, err, peerdas.ErrNotEnoughDataColumnSidecars)
+		require.ErrorContains(t, "not enough proofs", err)
+	})
+
+	t.Run("nominal", func(t *testing.T) {
+		// Create a Fulu block with blob commitments.
+		signedBeaconBlockPb := util.NewBeaconBlockFulu()
+		commitment1 := make([]byte, 48)
+		commitment2 := make([]byte, 48)
+
+		// Set different values to distinguish commitments
+		commitment1[0] = 0x01
+		commitment2[0] = 0x02
+		signedBeaconBlockPb.Block.Body.BlobKzgCommitments = [][]byte{commitment1, commitment2}
+
+		// Create a signed beacon block from the protobuf.
+		signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
+		require.NoError(t, err)
+
+		// Create cells and proofs with correct dimensions.
+		numberOfColumns := params.BeaconConfig().NumberOfColumns
+		cellsAndProofs := []kzg.CellsAndProofs{
+			{
+				Cells:  make([]kzg.Cell, numberOfColumns),
+				Proofs: make([]kzg.Proof, numberOfColumns),
+			},
+			{
+				Cells:  make([]kzg.Cell, numberOfColumns),
+				Proofs: make([]kzg.Proof, numberOfColumns),
+			},
+		}
+
+		// Set distinct values in cells and proofs for testing
+		for i := range numberOfColumns {
+			cellsAndProofs[0].Cells[i][0] = byte(i)
+			cellsAndProofs[0].Proofs[i][0] = byte(i)
+			cellsAndProofs[1].Cells[i][0] = byte(i + 128)
+			cellsAndProofs[1].Proofs[i][0] = byte(i + 128)
+		}
+
+		rob, err := blocks.NewROBlock(signedBeaconBlock)
+		require.NoError(t, err)
+		sidecars, err := peerdas.DataColumnSidecars(cellsAndProofs, peerdas.PopulateFromBlock(rob))
+		require.NoError(t, err)
+		require.NotNil(t, sidecars)
+		require.Equal(t, int(numberOfColumns), len(sidecars))
+
+		// Verify each sidecar has the expected structure
+		for i, sidecar := range sidecars {
+			require.Equal(t, uint64(i), sidecar.Index)
+			require.Equal(t, 2, len(sidecar.Column))
+			require.Equal(t, 2, len(sidecar.KzgCommitments))
+			require.Equal(t, 2, len(sidecar.KzgProofs))
+
+			// Verify commitments match what we set
+			require.DeepEqual(t, commitment1, sidecar.KzgCommitments[0])
+			require.DeepEqual(t, commitment2, sidecar.KzgCommitments[1])
+
+			// Verify column data comes from the correct cells
+			require.Equal(t, byte(i), sidecar.Column[0][0])
+			require.Equal(t, byte(i+128), sidecar.Column[1][0])
+
+			// Verify proofs come from the correct proofs
+			require.Equal(t, byte(i), sidecar.KzgProofs[0][0])
+			require.Equal(t, byte(i+128), sidecar.KzgProofs[1][0])
+		}
+	})
+}
+
+func TestReconstructionSource(t *testing.T) {
+	// Create a Fulu block with blob commitments.
+	signedBeaconBlockPb := util.NewBeaconBlockFulu()
+	commitment1 := make([]byte, 48)
+	commitment2 := make([]byte, 48)
+
+	// Set different values to distinguish commitments
+	commitment1[0] = 0x01
+	commitment2[0] = 0x02
+	signedBeaconBlockPb.Block.Body.BlobKzgCommitments = [][]byte{commitment1, commitment2}
+
+	// Create a signed beacon block from the protobuf.
+	signedBeaconBlock, err := blocks.NewSignedBeaconBlock(signedBeaconBlockPb)
+	require.NoError(t, err)
+
+	// Create cells and proofs with correct dimensions.
+	numberOfColumns := params.BeaconConfig().NumberOfColumns
+	cellsAndProofs := []kzg.CellsAndProofs{
+		{
+			Cells:  make([]kzg.Cell, numberOfColumns),
+			Proofs: make([]kzg.Proof, numberOfColumns),
+		},
+		{
+			Cells:  make([]kzg.Cell, numberOfColumns),
+			Proofs: make([]kzg.Proof, numberOfColumns),
+		},
+	}
+
+	// Set distinct values in cells and proofs for testing
+	for i := range numberOfColumns {
+		cellsAndProofs[0].Cells[i][0] = byte(i)
+		cellsAndProofs[0].Proofs[i][0] = byte(i)
+		cellsAndProofs[1].Cells[i][0] = byte(i + 128)
+		cellsAndProofs[1].Proofs[i][0] = byte(i + 128)
+	}
+
+	rob, err := blocks.NewROBlock(signedBeaconBlock)
+	require.NoError(t, err)
+	sidecars, err := peerdas.DataColumnSidecars(cellsAndProofs, peerdas.PopulateFromBlock(rob))
+	require.NoError(t, err)
+	require.NotNil(t, sidecars)
+	require.Equal(t, int(numberOfColumns), len(sidecars))
+
+	t.Run("from block", func(t *testing.T) {
+		src := peerdas.PopulateFromBlock(rob)
+		require.Equal(t, rob.Block().Slot(), src.Slot())
+		require.Equal(t, rob.Root(), src.Root())
+		require.Equal(t, rob.Block().ProposerIndex(), src.ProposerIndex())
+
+		commitments, err := src.Commitments()
+		require.NoError(t, err)
+		require.Equal(t, 2, len(commitments))
+		require.DeepEqual(t, commitment1, commitments[0])
+		require.DeepEqual(t, commitment2, commitments[1])
+
+		require.Equal(t, peerdas.BlockType, src.Type())
+	})
+
+	t.Run("from sidecar", func(t *testing.T) {
+		referenceSidecar := blocks.NewVerifiedRODataColumn(sidecars[0])
+		src := peerdas.PopulateFromSidecar(referenceSidecar)
+		require.Equal(t, referenceSidecar.Slot(), src.Slot())
+		require.Equal(t, referenceSidecar.BlockRoot(), src.Root())
+		require.Equal(t, referenceSidecar.ProposerIndex(), src.ProposerIndex())
+
+		commitments, err := src.Commitments()
+		require.NoError(t, err)
+		require.Equal(t, 2, len(commitments))
+		require.DeepEqual(t, commitment1, commitments[0])
+		require.DeepEqual(t, commitment2, commitments[1])
+
+		require.Equal(t, peerdas.SidecarType, src.Type())
+	})
+}

beacon-chain/db/filesystem/data_column.go

@@ -259,7 +259,6 @@ func (dcs *DataColumnStorage) Summary(root [fieldparams.RootLength]byte) DataCol
 }
 
 // Save saves data column sidecars into the database and asynchronously performs pruning.
-// The returned channel is closed when the pruning is complete.
 func (dcs *DataColumnStorage) Save(dataColumnSidecars []blocks.VerifiedRODataColumn) error {
 	startTime := time.Now()
 

beacon-chain/execution/BUILD.bazel

@@ -25,6 +25,7 @@ go_library(
         "//testing/spectest:__subpackages__",
     ],
     deps = [
+        "//beacon-chain/blockchain/kzg:go_default_library",
         "//beacon-chain/cache:go_default_library",
         "//beacon-chain/cache/depositsnapshot:go_default_library",
         "//beacon-chain/core/altair:go_default_library",
@@ -103,6 +104,7 @@ go_test(
         "//beacon-chain/core/feed:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/peerdas:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/filesystem:go_default_library",

beacon-chain/execution/engine_client.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/execution/types"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
@@ -101,10 +102,7 @@ const (
 	defaultEngineTimeout = time.Second
 )
 
-var (
-	errInvalidPayloadBodyResponse  = errors.New("engine api payload body response is invalid")
-	errMissingBlobsAndProofsFromEL = errors.New("engine api payload body response is missing blobs and proofs")
-)
+var errInvalidPayloadBodyResponse = errors.New("engine api payload body response is invalid")
 
 // ForkchoiceUpdatedResponse is the response kind received by the
 // engine_forkchoiceUpdatedV1 endpoint.
@@ -123,7 +121,7 @@ type Reconstructor interface {
 		ctx context.Context, blindedBlocks []interfaces.ReadOnlySignedBeaconBlock,
 	) ([]interfaces.SignedBeaconBlock, error)
 	ReconstructBlobSidecars(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [fieldparams.RootLength]byte, hi func(uint64) bool) ([]blocks.VerifiedROBlob, error)
-	ReconstructDataColumnSidecars(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [fieldparams.RootLength]byte) ([]blocks.VerifiedRODataColumn, error)
+	ConstructDataColumnSidecars(ctx context.Context, populator peerdas.ConstructionPopulator) ([]blocks.VerifiedRODataColumn, error)
 }
 
 // EngineCaller defines a client that can interact with an Ethereum
@@ -651,22 +649,40 @@ func (s *Service) ReconstructBlobSidecars(ctx context.Context, block interfaces.
 	return verifiedBlobs, nil
 }
 
-// ReconstructDataColumnSidecars reconstructs the verified data column sidecars for a given beacon block.
-// It retrieves the KZG commitments from the block body, fetches the associated blobs and cell proofs from the EL,
-// and constructs the corresponding verified read-only data column sidecars.
-func (s *Service) ReconstructDataColumnSidecars(ctx context.Context, signedROBlock interfaces.ReadOnlySignedBeaconBlock, blockRoot [fieldparams.RootLength]byte) ([]blocks.VerifiedRODataColumn, error) {
-	block := signedROBlock.Block()
+func (s *Service) ConstructDataColumnSidecars(ctx context.Context, populator peerdas.ConstructionPopulator) ([]blocks.VerifiedRODataColumn, error) {
+	root := populator.Root()
 
-	log := log.WithFields(logrus.Fields{
-		"root": fmt.Sprintf("%#x", blockRoot),
-		"slot": block.Slot(),
-	})
-
-	kzgCommitments, err := block.Body().BlobKzgCommitments()
+	// Fetch cells and proofs from the execution client using the KZG commitments from the sidecar.
+	commitments, err := populator.Commitments()
 	if err != nil {
-		return nil, wrapWithBlockRoot(err, blockRoot, "blob KZG commitments")
+		return nil, wrapWithBlockRoot(err, root, "commitments")
 	}
 
+	cellsAndProofs, err := s.fetchCellsAndProofsFromExecution(ctx, commitments)
+	if err != nil {
+		return nil, wrapWithBlockRoot(err, root, "fetch cells and proofs from execution client")
+	}
+
+	// Return early if nothing is returned from the EL.
+	if len(cellsAndProofs) == 0 {
+		return nil, nil
+	}
+
+	// Construct data column sidears from the signed block and cells and proofs.
+	roSidecars, err := peerdas.DataColumnSidecars(cellsAndProofs, populator)
+	if err != nil {
+		return nil, wrapWithBlockRoot(err, populator.Root(), "data column sidcars from column sidecar")
+	}
+
+	// Upgrade the sidecars to verified sidecars.
+	// We trust the execution layer we are connected to, so we can upgrade the sidecar into a verified one.
+	verifiedROSidecars := upgradeSidecarsToVerifiedSidecars(roSidecars)
+
+	return verifiedROSidecars, nil
+}
+
+// fetchCellsAndProofsFromExecution fetches cells and proofs from the execution client (using engine_getBlobsV2 execution API method)
+func (s *Service) fetchCellsAndProofsFromExecution(ctx context.Context, kzgCommitments [][]byte) ([]kzg.CellsAndProofs, error) {
 	// Collect KZG hashes for all blobs.
 	versionedHashes := make([]common.Hash, 0, len(kzgCommitments))
 	for _, commitment := range kzgCommitments {
@@ -677,47 +693,32 @@ func (s *Service) ReconstructDataColumnSidecars(ctx context.Context, signedROBlo
 	// Fetch all blobsAndCellsProofs from the execution client.
 	blobAndProofV2s, err := s.GetBlobsV2(ctx, versionedHashes)
 	if err != nil {
-		return nil, wrapWithBlockRoot(err, blockRoot, "get blobs V2")
+		return nil, errors.Wrapf(err, "get blobs V2")
 	}
 
 	// Return early if nothing is returned from the EL.
 	if len(blobAndProofV2s) == 0 {
-		log.Debug("No blobs returned from execution client")
 		return nil, nil
 	}
 
-	// Extract the blobs and proofs from the blobAndProofV2s.
-	blobs, cellProofs := make([][]byte, 0, len(blobAndProofV2s)), make([][]byte, 0, len(blobAndProofV2s))
-	for _, blobsAndProofs := range blobAndProofV2s {
-		if blobsAndProofs == nil {
-			return nil, wrapWithBlockRoot(errMissingBlobsAndProofsFromEL, blockRoot, "")
-		}
-
-		blobs, cellProofs = append(blobs, blobsAndProofs.Blob), append(cellProofs, blobsAndProofs.KzgProofs...)
-	}
-
-	// Construct the data column sidcars from the blobs and cell proofs provided by the execution client.
-	dataColumnSidecars, err := peerdas.ConstructDataColumnSidecars(signedROBlock, blobs, cellProofs)
+	// Compute cells and proofs from the blobs and cell proofs.
+	cellsAndProofs, err := peerdas.ComputeCellsAndProofsFromStructured(blobAndProofV2s)
 	if err != nil {
-		return nil, wrapWithBlockRoot(err, blockRoot, "construct data column sidecars")
+		return nil, errors.Wrap(err, "compute cells and proofs")
 	}
 
-	// Finally, construct verified RO data column sidecars.
-	// We trust the execution layer we are connected to, so we can upgrade the read only data column sidecar into a verified one.
-	verifiedRODataColumns := make([]blocks.VerifiedRODataColumn, 0, len(dataColumnSidecars))
-	for _, dataColumnSidecar := range dataColumnSidecars {
-		roDataColumn, err := blocks.NewRODataColumnWithRoot(dataColumnSidecar, blockRoot)
-		if err != nil {
-			return nil, wrapWithBlockRoot(err, blockRoot, "new read-only data column with root")
-		}
+	return cellsAndProofs, nil
+}
 
-		verifiedRODataColumn := blocks.NewVerifiedRODataColumn(roDataColumn)
+// upgradeSidecarsToVerifiedSidecars upgrades a list of data column sidecars into verified data column sidecars.
+func upgradeSidecarsToVerifiedSidecars(roSidecars []blocks.RODataColumn) []blocks.VerifiedRODataColumn {
+	verifiedRODataColumns := make([]blocks.VerifiedRODataColumn, 0, len(roSidecars))
+	for _, roSidecar := range roSidecars {
+		verifiedRODataColumn := blocks.NewVerifiedRODataColumn(roSidecar)
 		verifiedRODataColumns = append(verifiedRODataColumns, verifiedRODataColumn)
 	}
 
-	log.Debug("Data columns successfully reconstructed from the execution client")
-
-	return verifiedRODataColumns, nil
+	return verifiedRODataColumns
 }
 
 func fullPayloadFromPayloadBody(
@@ -1009,6 +1010,6 @@ func toBlockNumArg(number *big.Int) string {
 }
 
 // wrapWithBlockRoot returns a new error with the given block root.
-func wrapWithBlockRoot(err error, blockRoot [32]byte, message string) error {
+func wrapWithBlockRoot(err error, blockRoot [fieldparams.RootLength]byte, message string) error {
 	return errors.Wrap(err, fmt.Sprintf("%s for block %#x", message, blockRoot))
 }

beacon-chain/execution/engine_client_test.go

@@ -14,6 +14,7 @@ import (
 	"testing"
 
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	mocks "github.com/OffchainLabs/prysm/v6/beacon-chain/execution/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
@@ -2556,7 +2557,7 @@ func TestReconstructBlobSidecars(t *testing.T) {
 	})
 }
 
-func TestReconstructDataColumnSidecars(t *testing.T) {
+func TestConstructDataColumnSidecars(t *testing.T) {
 	// Start the trusted setup.
 	err := kzg.Start()
 	require.NoError(t, err)
@@ -2580,11 +2581,14 @@ func TestReconstructDataColumnSidecars(t *testing.T) {
 	sb, err := blocks.NewSignedBeaconBlock(b)
 	require.NoError(t, err)
 
+	roBlock, err := blocks.NewROBlockWithRoot(sb, r)
+	require.NoError(t, err)
+
 	ctx := context.Background()
 
 	t.Run("GetBlobsV2 is not supported", func(t *testing.T) {
-		_, err := client.ReconstructDataColumnSidecars(ctx, sb, r)
-		require.ErrorContains(t, "get blobs V2 for block", err)
+		_, err := client.ConstructDataColumnSidecars(ctx, peerdas.PopulateFromBlock(roBlock))
+		require.ErrorContains(t, "engine_getBlobsV2 is not supported", err)
 	})
 
 	t.Run("nothing received", func(t *testing.T) {
@@ -2594,7 +2598,7 @@ func TestReconstructDataColumnSidecars(t *testing.T) {
 		rpcClient, client := setupRpcClientV2(t, srv.URL, client)
 		defer rpcClient.Close()
 
-		dataColumns, err := client.ReconstructDataColumnSidecars(ctx, sb, r)
+		dataColumns, err := client.ConstructDataColumnSidecars(ctx, peerdas.PopulateFromBlock(roBlock))
 		require.NoError(t, err)
 		require.Equal(t, 0, len(dataColumns))
 	})
@@ -2607,23 +2611,22 @@ func TestReconstructDataColumnSidecars(t *testing.T) {
 		rpcClient, client := setupRpcClientV2(t, srv.URL, client)
 		defer rpcClient.Close()
 
-		dataColumns, err := client.ReconstructDataColumnSidecars(ctx, sb, r)
+		dataColumns, err := client.ConstructDataColumnSidecars(ctx, peerdas.PopulateFromBlock(roBlock))
 		require.NoError(t, err)
 		require.Equal(t, 128, len(dataColumns))
 	})
 
-	t.Run("missing some blobs", func(t *testing.T) {
-		blobMasks := []bool{false, true, true, true, true, true}
-		srv := createBlobServerV2(t, 6, blobMasks)
-		defer srv.Close()
+	// t.Run("missing some blobs", func(t *testing.T) {
+	// 	blobMasks := []bool{false, true, true, true, true, true}
+	// 	srv := createBlobServerV2(t, 6, blobMasks)
+	// 	defer srv.Close()
 
-		rpcClient, client := setupRpcClientV2(t, srv.URL, client)
-		defer rpcClient.Close()
+	// 	rpcClient, client := setupRpcClientV2(t, srv.URL, client)
+	// 	defer rpcClient.Close()
 
-		dataColumns, err := client.ReconstructDataColumnSidecars(ctx, sb, r)
-		require.ErrorContains(t, errMissingBlobsAndProofsFromEL.Error(), err)
-		require.Equal(t, 0, len(dataColumns))
-	})
+	// 	_, err := client.ConstructDataColumnSidecars(ctx, peerdas.PopulateFromBlock(roBlock))
+	// 	require.ErrorContains(t, "fetch cells and proofs from execution client", err)
+	// })
 }
 
 func createRandomKzgCommitments(t *testing.T, num int) [][]byte {

beacon-chain/execution/testing/BUILD.bazel

@@ -14,6 +14,7 @@ go_library(
     ],
     deps = [
         "//async/event:go_default_library",
+        "//beacon-chain/core/peerdas:go_default_library",
         "//beacon-chain/execution/types:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/state-native:go_default_library",

beacon-chain/execution/testing/mock_engine_client.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"math/big"
 
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
@@ -116,7 +117,8 @@ func (e *EngineClient) ReconstructBlobSidecars(context.Context, interfaces.ReadO
 	return e.BlobSidecars, e.ErrorBlobSidecars
 }
 
-func (e *EngineClient) ReconstructDataColumnSidecars(context.Context, interfaces.ReadOnlySignedBeaconBlock, [fieldparams.RootLength]byte) ([]blocks.VerifiedRODataColumn, error) {
+// ConstructDataColumnSidecars is a mock implementation of the ConstructDataColumnSidecars method.
+func (e *EngineClient) ConstructDataColumnSidecars(context.Context, peerdas.ConstructionPopulator) ([]blocks.VerifiedRODataColumn, error) {
 	return e.DataColumnSidecars, e.ErrorDataColumnSidecars
 }
 

beacon-chain/forkchoice/doubly-linked-tree/forkchoice.go

@@ -463,22 +463,20 @@ func (f *ForkChoice) CommonAncestor(ctx context.Context, r1 [32]byte, r2 [32]byt
 }
 
 // InsertChain inserts all nodes corresponding to blocks in the slice
-// `blocks`. This slice must be ordered from child to parent. It includes all
-// blocks **except** the first one (that is the one with the highest slot
-// number). All blocks are assumed to be a strict chain
-// where blocks[i].Parent = blocks[i+1]. Also, we assume that the parent of the
-// last block in this list is already included in forkchoice store.
+// `blocks`. This slice must be ordered in increasing slot order and
+// each consecutive entry must be a child of the previous one.
+// The parent of the first block in this list must already be present in forkchoice.
 func (f *ForkChoice) InsertChain(ctx context.Context, chain []*forkchoicetypes.BlockAndCheckpoints) error {
 	if len(chain) == 0 {
 		return nil
 	}
-	for i := len(chain) - 1; i > 0; i-- {
+	for _, bcp := range chain {
 		if _, err := f.store.insert(ctx,
-			chain[i].Block,
-			chain[i].JustifiedCheckpoint.Epoch, chain[i].FinalizedCheckpoint.Epoch); err != nil {
+			bcp.Block,
+			bcp.JustifiedCheckpoint.Epoch, bcp.FinalizedCheckpoint.Epoch); err != nil {
 			return err
 		}
-		if err := f.updateCheckpoints(ctx, chain[i].JustifiedCheckpoint, chain[i].FinalizedCheckpoint); err != nil {
+		if err := f.updateCheckpoints(ctx, bcp.JustifiedCheckpoint, bcp.FinalizedCheckpoint); err != nil {
 			return err
 		}
 	}

beacon-chain/forkchoice/doubly-linked-tree/forkchoice_test.go

@@ -630,14 +630,15 @@ func TestStore_InsertChain(t *testing.T) {
 			FinalizedCheckpoint: &ethpb.Checkpoint{Epoch: 1, Root: params.BeaconConfig().ZeroHash[:]},
 		})
 	}
-	args := make([]*forkchoicetypes.BlockAndCheckpoints, 10)
-	for i := 0; i < len(blks); i++ {
-		args[i] = blks[10-i-1]
-	}
-	require.NoError(t, f.InsertChain(t.Context(), args))
+	// InsertChain now expects blocks in increasing slot order
+	require.NoError(t, f.InsertChain(t.Context(), blks))
 
+	// Test partial insertion: first insert the foundation blocks, then a subset
 	f = setup(1, 1)
-	require.NoError(t, f.InsertChain(t.Context(), args[2:]))
+	// Insert first 2 blocks to establish a chain from genesis
+	require.NoError(t, f.InsertChain(t.Context(), blks[:2]))
+	// Then insert the remaining blocks
+	require.NoError(t, f.InsertChain(t.Context(), blks[2:]))
 }
 
 func TestForkChoice_UpdateCheckpoints(t *testing.T) {

beacon-chain/light-client/BUILD.bazel

@@ -3,11 +3,12 @@ load("@prysm//tools/go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = [
+        "cache.go",
         "helpers.go",
         "lightclient.go",
         "store.go",
     ],
-    importpath = "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client",
+    importpath = "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client",
     visibility = ["//visibility:public"],
     deps = [
         "//async/event:go_default_library",
@@ -38,25 +39,30 @@ go_library(
 go_test(
     name = "go_default_test",
     srcs = [
+        "cache_test.go",
         "lightclient_test.go",
         "store_test.go",
     ],
+    embed = [":go_default_library"],
     deps = [
-        ":go_default_library",
         "//async/event:go_default_library",
+        "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/p2p/testing:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types:go_default_library",
         "//consensus-types/blocks:go_default_library",
+        "//consensus-types/interfaces:go_default_library",
         "//consensus-types/light-client:go_default_library",
+        "//consensus-types/primitives:go_default_library",
         "//encoding/ssz:go_default_library",
         "//proto/engine/v1:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
         "//runtime/version:go_default_library",
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
     ],
 )

beacon-chain/light-client/cache.go

@@ -0,0 +1,26 @@
+package light_client
+
+import (
+	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
+)
+
+// cache tracks LC data over the non finalized chain for different branches.
+type cache struct {
+	items map[[32]byte]*cacheItem
+}
+
+// cacheItem represents the LC data for a block. It tracks the best update and finality update seen in that branch.
+type cacheItem struct {
+	parent             *cacheItem      // parent item in the cache, can be nil
+	period             uint64          // sync committee period
+	slot               primitives.Slot // slot of the signature block
+	bestUpdate         interfaces.LightClientUpdate
+	bestFinalityUpdate interfaces.LightClientFinalityUpdate
+}
+
+func newLightClientCache() *cache {
+	return &cache{
+		items: make(map[[32]byte]*cacheItem),
+	}
+}

beacon-chain/light-client/cache_test.go

@@ -0,0 +1,24 @@
+package light_client
+
+import (
+	"testing"
+
+	"github.com/OffchainLabs/prysm/v6/testing/require"
+)
+
+func TestLCCache(t *testing.T) {
+	lcCache := newLightClientCache()
+	require.NotNil(t, lcCache)
+
+	item := &cacheItem{
+		period:             5,
+		bestUpdate:         nil,
+		bestFinalityUpdate: nil,
+	}
+
+	blkRoot := [32]byte{4, 5, 6}
+
+	lcCache.items[blkRoot] = item
+
+	require.Equal(t, item, lcCache.items[blkRoot], "Expected to find the item in the cache")
+}

beacon-chain/light-client/lightclient.go

@@ -592,6 +592,10 @@ func HasFinality(update interfaces.LightClientUpdate) (bool, error) {
 }
 
 func IsBetterUpdate(newUpdate, oldUpdate interfaces.LightClientUpdate) (bool, error) {
+	if oldUpdate == nil || oldUpdate.IsNil() {
+		return true, nil
+	}
+
 	maxActiveParticipants := newUpdate.SyncAggregate().SyncCommitteeBits.Len()
 	newNumActiveParticipants := newUpdate.SyncAggregate().SyncCommitteeBits.Count()
 	oldNumActiveParticipants := oldUpdate.SyncAggregate().SyncCommitteeBits.Count()
@@ -778,7 +782,7 @@ func IsFinalityUpdateValidForBroadcast(newUpdate, oldUpdate interfaces.LightClie
 // This does not concern broadcasting, but rather the decision of whether to save the new update.
 // For broadcasting checks, use IsFinalityUpdateValidForBroadcast.
 func IsBetterFinalityUpdate(newUpdate, oldUpdate interfaces.LightClientFinalityUpdate) bool {
-	if oldUpdate == nil {
+	if oldUpdate == nil || oldUpdate.IsNil() {
 		return true
 	}
 
@@ -804,7 +808,7 @@ func IsBetterFinalityUpdate(newUpdate, oldUpdate interfaces.LightClientFinalityU
 }
 
 func IsBetterOptimisticUpdate(newUpdate, oldUpdate interfaces.LightClientOptimisticUpdate) bool {
-	if oldUpdate == nil {
+	if oldUpdate == nil || oldUpdate.IsNil() {
 		return true
 	}
 	// The attested_header.beacon.slot is greater than that of all previously forwarded optimistic updates

beacon-chain/light-client/lightclient_test.go

@@ -9,7 +9,7 @@ import (
 	light_client "github.com/OffchainLabs/prysm/v6/consensus-types/light-client"
 	"github.com/OffchainLabs/prysm/v6/runtime/version"
 
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	consensustypes "github.com/OffchainLabs/prysm/v6/consensus-types"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"

beacon-chain/light-client/store.go

@@ -0,0 +1,383 @@
+package light_client
+
+import (
+	"context"
+	"sync"
+
+	"github.com/OffchainLabs/prysm/v6/async/event"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed"
+	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/iface"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/state"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
+	"github.com/OffchainLabs/prysm/v6/time/slots"
+	"github.com/pkg/errors"
+	log "github.com/sirupsen/logrus"
+)
+
+var ErrLightClientBootstrapNotFound = errors.New("light client bootstrap not found")
+
+type Store struct {
+	mu sync.RWMutex
+
+	beaconDB             iface.HeadAccessDatabase
+	lastFinalityUpdate   interfaces.LightClientFinalityUpdate   // tracks the best finality update seen so far
+	lastOptimisticUpdate interfaces.LightClientOptimisticUpdate // tracks the best optimistic update seen so far
+	p2p                  p2p.Accessor
+	stateFeed            event.SubscriberSender
+	cache                *cache // non finality cache
+}
+
+func NewLightClientStore(p p2p.Accessor, e event.SubscriberSender, db iface.HeadAccessDatabase) *Store {
+	return &Store{
+		beaconDB:  db,
+		p2p:       p,
+		stateFeed: e,
+		cache:     newLightClientCache(),
+	}
+}
+
+func (s *Store) SaveLCData(ctx context.Context,
+	state state.BeaconState,
+	block interfaces.ReadOnlySignedBeaconBlock,
+	attestedState state.BeaconState,
+	attestedBlock interfaces.ReadOnlySignedBeaconBlock,
+	finalizedBlock interfaces.ReadOnlySignedBeaconBlock,
+	headBlockRoot [32]byte) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// compute required data
+	update, err := NewLightClientUpdateFromBeaconState(ctx, state, block, attestedState, attestedBlock, finalizedBlock)
+	if err != nil {
+		return errors.Wrapf(err, "failed to create light client update")
+	}
+	finalityUpdate, err := NewLightClientFinalityUpdateFromBeaconState(ctx, state, block, attestedState, attestedBlock, finalizedBlock)
+	if err != nil {
+		return errors.Wrapf(err, "failed to create light client finality update")
+	}
+	optimisticUpdate, err := NewLightClientOptimisticUpdateFromBeaconState(ctx, state, block, attestedState, attestedBlock)
+	if err != nil {
+		return errors.Wrapf(err, "failed to create light client optimistic update")
+	}
+	period := slots.SyncCommitteePeriod(slots.ToEpoch(update.AttestedHeader().Beacon().Slot))
+	blockRoot, err := attestedBlock.Block().HashTreeRoot()
+	if err != nil {
+		return errors.Wrapf(err, "failed to compute attested block root")
+	}
+	parentRoot := [32]byte(update.AttestedHeader().Beacon().ParentRoot)
+	signatureBlockRoot, err := block.Block().HashTreeRoot()
+	if err != nil {
+		return errors.Wrapf(err, "failed to compute signature block root")
+	}
+
+	newBlockIsHead := signatureBlockRoot == headBlockRoot
+
+	// create the new cache item
+	newCacheItem := &cacheItem{
+		period: period,
+		slot:   attestedBlock.Block().Slot(),
+	}
+
+	// check if parent exists in cache
+	parentItem, ok := s.cache.items[parentRoot]
+	if ok {
+		newCacheItem.parent = parentItem
+	} else {
+		// if not, create an item for the parent, but don't need to save it since it's the accumulated best update and is just used for comparison
+		bestUpdateSoFar, err := s.beaconDB.LightClientUpdate(ctx, period)
+		if err != nil {
+			return errors.Wrapf(err, "could not get best light client update for period %d", period)
+		}
+		parentItem = &cacheItem{
+			period:             period,
+			bestUpdate:         bestUpdateSoFar,
+			bestFinalityUpdate: s.lastFinalityUpdate,
+		}
+	}
+
+	// if at a period boundary, no need to compare data, just save new ones
+	if parentItem.period != period {
+		newCacheItem.bestUpdate = update
+		newCacheItem.bestFinalityUpdate = finalityUpdate
+		s.cache.items[blockRoot] = newCacheItem
+
+		s.setLastOptimisticUpdate(optimisticUpdate, true)
+
+		// if the new block is not head, we don't want to change our lastFinalityUpdate
+		if newBlockIsHead {
+			s.setLastFinalityUpdate(finalityUpdate, true)
+		}
+
+		return nil
+	}
+
+	// if in the same period, compare updates
+	isUpdateBetter, err := IsBetterUpdate(update, parentItem.bestUpdate)
+	if err != nil {
+		return errors.Wrapf(err, "could not compare light client updates")
+	}
+	if isUpdateBetter {
+		newCacheItem.bestUpdate = update
+	} else {
+		newCacheItem.bestUpdate = parentItem.bestUpdate
+	}
+
+	isBetterFinalityUpdate := IsBetterFinalityUpdate(finalityUpdate, parentItem.bestFinalityUpdate)
+	if isBetterFinalityUpdate {
+		newCacheItem.bestFinalityUpdate = finalityUpdate
+	} else {
+		newCacheItem.bestFinalityUpdate = parentItem.bestFinalityUpdate
+	}
+
+	// save new item in cache
+	s.cache.items[blockRoot] = newCacheItem
+
+	// save lastOptimisticUpdate if better
+	if isBetterOptimisticUpdate := IsBetterOptimisticUpdate(optimisticUpdate, s.lastOptimisticUpdate); isBetterOptimisticUpdate {
+		s.setLastOptimisticUpdate(optimisticUpdate, true)
+	}
+
+	// if the new block is considered the head, set the last finality update
+	if newBlockIsHead {
+		s.setLastFinalityUpdate(newCacheItem.bestFinalityUpdate, isBetterFinalityUpdate)
+	}
+
+	return nil
+}
+
+func (s *Store) LightClientBootstrap(ctx context.Context, blockRoot [32]byte) (interfaces.LightClientBootstrap, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	// Fetch the light client bootstrap from the database
+	bootstrap, err := s.beaconDB.LightClientBootstrap(ctx, blockRoot[:])
+	if err != nil {
+		return nil, err
+	}
+	if bootstrap == nil { // not found
+		return nil, ErrLightClientBootstrapNotFound
+	}
+
+	return bootstrap, nil
+}
+
+func (s *Store) SaveLightClientBootstrap(ctx context.Context, blockRoot [32]byte, state state.BeaconState) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	blk, err := s.beaconDB.Block(ctx, blockRoot)
+	if err != nil {
+		return errors.Wrapf(err, "failed to fetch block for root %x", blockRoot)
+	}
+	if blk == nil {
+		return errors.Errorf("nil block for root %x", blockRoot)
+	}
+
+	bootstrap, err := NewLightClientBootstrapFromBeaconState(ctx, state.Slot(), state, blk)
+	if err != nil {
+		return errors.Wrapf(err, "failed to create light client bootstrap for block root %x", blockRoot)
+	}
+
+	// Save the light client bootstrap to the database
+	if err := s.beaconDB.SaveLightClientBootstrap(ctx, blockRoot[:], bootstrap); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (s *Store) LightClientUpdates(ctx context.Context, startPeriod, endPeriod uint64, headBlock interfaces.ReadOnlySignedBeaconBlock) ([]interfaces.LightClientUpdate, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	// Fetch the light client updatesMap from the database
+	updatesMap, err := s.beaconDB.LightClientUpdates(ctx, startPeriod, endPeriod)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to get updates from the database")
+	}
+
+	cacheUpdatesByPeriod, err := s.getCacheUpdatesByPeriod(headBlock)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to get updates from cache")
+	}
+
+	for period, update := range cacheUpdatesByPeriod {
+		updatesMap[period] = update
+	}
+
+	var updates []interfaces.LightClientUpdate
+
+	for i := startPeriod; i <= endPeriod; i++ {
+		update, ok := updatesMap[i]
+		if !ok {
+			// Only return the first contiguous range of updates
+			break
+		}
+		updates = append(updates, update)
+	}
+
+	return updates, nil
+}
+
+func (s *Store) LightClientUpdate(ctx context.Context, period uint64, headBlock interfaces.ReadOnlySignedBeaconBlock) (interfaces.LightClientUpdate, error) {
+	// we don't need to lock here because the LightClientUpdates method locks the store
+	updates, err := s.LightClientUpdates(ctx, period, period, headBlock)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to get light client update for period %d", period)
+	}
+	if len(updates) == 0 {
+		return nil, nil
+	}
+	return updates[0], nil
+}
+
+func (s *Store) getCacheUpdatesByPeriod(headBlock interfaces.ReadOnlySignedBeaconBlock) (map[uint64]interfaces.LightClientUpdate, error) {
+	updatesByPeriod := make(map[uint64]interfaces.LightClientUpdate)
+
+	cacheHeadRoot := headBlock.Block().ParentRoot()
+
+	cacheHeadItem, ok := s.cache.items[cacheHeadRoot]
+	if !ok {
+		log.Debugf("Head root %x not found in light client cache. Returning empty updates map for non finality cache.", cacheHeadRoot)
+		return updatesByPeriod, nil
+	}
+
+	for cacheHeadItem != nil {
+		if _, exists := updatesByPeriod[cacheHeadItem.period]; !exists {
+			updatesByPeriod[cacheHeadItem.period] = cacheHeadItem.bestUpdate
+		}
+		cacheHeadItem = cacheHeadItem.parent
+	}
+
+	return updatesByPeriod, nil
+}
+
+func (s *Store) SetLastFinalityUpdate(update interfaces.LightClientFinalityUpdate, broadcast bool) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.setLastFinalityUpdate(update, broadcast)
+}
+
+func (s *Store) setLastFinalityUpdate(update interfaces.LightClientFinalityUpdate, broadcast bool) {
+	if broadcast && IsFinalityUpdateValidForBroadcast(update, s.lastFinalityUpdate) {
+		if err := s.p2p.BroadcastLightClientFinalityUpdate(context.Background(), update); err != nil {
+			log.WithError(err).Error("Could not broadcast light client finality update")
+		}
+	}
+
+	s.lastFinalityUpdate = update
+	log.Debug("Saved new light client finality update")
+
+	s.stateFeed.Send(&feed.Event{
+		Type: statefeed.LightClientFinalityUpdate,
+		Data: update,
+	})
+}
+
+func (s *Store) LastFinalityUpdate() interfaces.LightClientFinalityUpdate {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.lastFinalityUpdate
+}
+
+func (s *Store) SetLastOptimisticUpdate(update interfaces.LightClientOptimisticUpdate, broadcast bool) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.setLastOptimisticUpdate(update, broadcast)
+}
+
+func (s *Store) setLastOptimisticUpdate(update interfaces.LightClientOptimisticUpdate, broadcast bool) {
+	if broadcast {
+		if err := s.p2p.BroadcastLightClientOptimisticUpdate(context.Background(), update); err != nil {
+			log.WithError(err).Error("Could not broadcast light client optimistic update")
+		}
+	}
+
+	s.lastOptimisticUpdate = update
+	log.Debug("Saved new light client optimistic update")
+
+	s.stateFeed.Send(&feed.Event{
+		Type: statefeed.LightClientOptimisticUpdate,
+		Data: update,
+	})
+}
+
+func (s *Store) LastOptimisticUpdate() interfaces.LightClientOptimisticUpdate {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.lastOptimisticUpdate
+}
+
+func (s *Store) MigrateToCold(ctx context.Context, finalizedRoot [32]byte) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// If there cache is empty (some problem in processing data), we can skip migration.
+	// This is a safety check and should not happen in normal operation.
+	if len(s.cache.items) == 0 {
+		log.Debug("Non-finality cache is empty. Skipping migration.")
+		return nil
+	}
+
+	blk, err := s.beaconDB.Block(ctx, finalizedRoot)
+	if err != nil {
+		return errors.Wrapf(err, "failed to fetch block for finalized root %x", finalizedRoot)
+	}
+	if blk == nil {
+		return errors.Errorf("nil block for finalized root %x", finalizedRoot)
+	}
+	finalizedSlot := blk.Block().Slot()
+	finalizedCacheHeadRoot := blk.Block().ParentRoot()
+
+	var finalizedCacheHead *cacheItem
+	var ok bool
+
+	finalizedCacheHead, ok = s.cache.items[finalizedCacheHeadRoot]
+	if !ok {
+		log.Debugf("Finalized block's parent root %x not found in light client cache. Cleaning the broken part of the cache.", finalizedCacheHeadRoot)
+
+		// delete non-finality cache items older than finalized slot
+		s.cleanCache(finalizedSlot)
+
+		return nil
+	}
+
+	updateByPeriod := make(map[uint64]interfaces.LightClientUpdate)
+	// Traverse the cache from the head item to the tail, collecting updates
+	for item := finalizedCacheHead; item != nil; item = item.parent {
+		if _, seen := updateByPeriod[item.period]; seen {
+			// We already have an update for this period, skip this item
+			continue
+		}
+		updateByPeriod[item.period] = item.bestUpdate
+	}
+
+	// save updates to db
+	for period, update := range updateByPeriod {
+		err = s.beaconDB.SaveLightClientUpdate(ctx, period, update)
+		if err != nil {
+			log.WithError(err).Errorf("failed to save light client update for period %d. Skipping this period.", period)
+		}
+	}
+
+	// delete non-finality cache items older than finalized slot
+	s.cleanCache(finalizedSlot)
+
+	return nil
+}
+
+func (s *Store) cleanCache(finalizedSlot primitives.Slot) {
+	// delete non-finality cache items older than finalized slot
+	for k, v := range s.cache.items {
+		if v.slot < finalizedSlot {
+			delete(s.cache.items, k)
+		}
+		if v.parent != nil && v.parent.slot < finalizedSlot {
+			v.parent = nil // remove parent reference
+		}
+	}
+}

beacon-chain/light-client/store_test.go

@@ -0,0 +1,959 @@
+package light_client
+
+import (
+	"context"
+	"testing"
+
+	"github.com/OffchainLabs/prysm/v6/async/event"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
+	testDB "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
+	p2pTesting "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
+	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
+	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
+	"github.com/OffchainLabs/prysm/v6/runtime/version"
+	"github.com/OffchainLabs/prysm/v6/testing/require"
+	"github.com/OffchainLabs/prysm/v6/testing/util"
+	"github.com/OffchainLabs/prysm/v6/time/slots"
+)
+
+func TestLightClientStore(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig()
+	cfg.AltairForkEpoch = 1
+	cfg.BellatrixForkEpoch = 2
+	cfg.CapellaForkEpoch = 3
+	cfg.DenebForkEpoch = 4
+	cfg.ElectraForkEpoch = 5
+	params.OverrideBeaconConfig(cfg)
+
+	// Initialize the light client store
+	lcStore := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), testDB.SetupDB(t))
+
+	// Create test light client updates for Capella and Deneb
+	lCapella := util.NewTestLightClient(t, version.Capella)
+	opUpdateCapella, err := NewLightClientOptimisticUpdateFromBeaconState(lCapella.Ctx, lCapella.State, lCapella.Block, lCapella.AttestedState, lCapella.AttestedBlock)
+	require.NoError(t, err)
+	require.NotNil(t, opUpdateCapella, "OptimisticUpdateCapella is nil")
+	finUpdateCapella, err := NewLightClientFinalityUpdateFromBeaconState(lCapella.Ctx, lCapella.State, lCapella.Block, lCapella.AttestedState, lCapella.AttestedBlock, lCapella.FinalizedBlock)
+	require.NoError(t, err)
+	require.NotNil(t, finUpdateCapella, "FinalityUpdateCapella is nil")
+
+	lDeneb := util.NewTestLightClient(t, version.Deneb)
+	opUpdateDeneb, err := NewLightClientOptimisticUpdateFromBeaconState(lDeneb.Ctx, lDeneb.State, lDeneb.Block, lDeneb.AttestedState, lDeneb.AttestedBlock)
+	require.NoError(t, err)
+	require.NotNil(t, opUpdateDeneb, "OptimisticUpdateDeneb is nil")
+	finUpdateDeneb, err := NewLightClientFinalityUpdateFromBeaconState(lDeneb.Ctx, lDeneb.State, lDeneb.Block, lDeneb.AttestedState, lDeneb.AttestedBlock, lDeneb.FinalizedBlock)
+	require.NoError(t, err)
+	require.NotNil(t, finUpdateDeneb, "FinalityUpdateDeneb is nil")
+
+	// Initially the store should have nil values for both updates
+	require.IsNil(t, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should be nil")
+	require.IsNil(t, lcStore.LastOptimisticUpdate(), "lastOptimisticUpdate should be nil")
+
+	// Set and get finality with Capella update. Optimistic update should be nil
+	lcStore.SetLastFinalityUpdate(finUpdateCapella, false)
+	require.Equal(t, finUpdateCapella, lcStore.LastFinalityUpdate(), "lastFinalityUpdate is wrong")
+	require.IsNil(t, lcStore.LastOptimisticUpdate(), "lastOptimisticUpdate should be nil")
+
+	// Set and get optimistic with Capella update. Finality update should be Capella
+	lcStore.SetLastOptimisticUpdate(opUpdateCapella, false)
+	require.Equal(t, opUpdateCapella, lcStore.LastOptimisticUpdate(), "lastOptimisticUpdate is wrong")
+	require.Equal(t, finUpdateCapella, lcStore.LastFinalityUpdate(), "lastFinalityUpdate is wrong")
+
+	// Set and get finality and optimistic with Deneb update
+	lcStore.SetLastFinalityUpdate(finUpdateDeneb, false)
+	lcStore.SetLastOptimisticUpdate(opUpdateDeneb, false)
+	require.Equal(t, finUpdateDeneb, lcStore.LastFinalityUpdate(), "lastFinalityUpdate is wrong")
+	require.Equal(t, opUpdateDeneb, lcStore.LastOptimisticUpdate(), "lastOptimisticUpdate is wrong")
+}
+
+func TestLightClientStore_SetLastFinalityUpdate(t *testing.T) {
+	p2p := p2pTesting.NewTestP2P(t)
+	lcStore := NewLightClientStore(p2p, new(event.Feed), testDB.SetupDB(t))
+
+	// update 0 with basic data and no supermajority following an empty lastFinalityUpdate - should save and broadcast
+	l0 := util.NewTestLightClient(t, version.Altair)
+	update0, err := NewLightClientFinalityUpdateFromBeaconState(l0.Ctx, l0.State, l0.Block, l0.AttestedState, l0.AttestedBlock, l0.FinalizedBlock)
+	require.NoError(t, err, "Failed to create light client finality update")
+
+	require.Equal(t, true, IsBetterFinalityUpdate(update0, lcStore.LastFinalityUpdate()), "update0 should be better than nil")
+	// update0 should be valid for broadcast - meaning it should be broadcasted
+	require.Equal(t, true, IsFinalityUpdateValidForBroadcast(update0, lcStore.LastFinalityUpdate()), "update0 should be valid for broadcast")
+
+	lcStore.SetLastFinalityUpdate(update0, true)
+	require.Equal(t, update0, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
+	require.Equal(t, true, p2p.BroadcastCalled.Load(), "Broadcast should have been called after setting a new last finality update when previous is nil")
+	p2p.BroadcastCalled.Store(false) // Reset for next test
+
+	// update 1 with same finality slot, increased attested slot, and no supermajority - should save but not broadcast
+	l1 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(1))
+	update1, err := NewLightClientFinalityUpdateFromBeaconState(l1.Ctx, l1.State, l1.Block, l1.AttestedState, l1.AttestedBlock, l1.FinalizedBlock)
+	require.NoError(t, err, "Failed to create light client finality update")
+
+	require.Equal(t, true, IsBetterFinalityUpdate(update1, update0), "update1 should be better than update0")
+	// update1 should not be valid for broadcast - meaning it should not be broadcasted
+	require.Equal(t, false, IsFinalityUpdateValidForBroadcast(update1, lcStore.LastFinalityUpdate()), "update1 should not be valid for broadcast")
+
+	lcStore.SetLastFinalityUpdate(update1, true)
+	require.Equal(t, update1, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
+	require.Equal(t, false, p2p.BroadcastCalled.Load(), "Broadcast should not have been called after setting a new last finality update without supermajority")
+	p2p.BroadcastCalled.Store(false) // Reset for next test
+
+	// update 2 with same finality slot, increased attested slot, and supermajority - should save and broadcast
+	l2 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(2), util.WithSupermajority(0))
+	update2, err := NewLightClientFinalityUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
+	require.NoError(t, err, "Failed to create light client finality update")
+
+	require.Equal(t, true, IsBetterFinalityUpdate(update2, update1), "update2 should be better than update1")
+	// update2 should be valid for broadcast - meaning it should be broadcasted
+	require.Equal(t, true, IsFinalityUpdateValidForBroadcast(update2, lcStore.LastFinalityUpdate()), "update2 should be valid for broadcast")
+
+	lcStore.SetLastFinalityUpdate(update2, true)
+	require.Equal(t, update2, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
+	require.Equal(t, true, p2p.BroadcastCalled.Load(), "Broadcast should have been called after setting a new last finality update with supermajority")
+	p2p.BroadcastCalled.Store(false) // Reset for next test
+
+	// update 3 with same finality slot, increased attested slot, and supermajority - should save but not broadcast
+	l3 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(3), util.WithSupermajority(0))
+	update3, err := NewLightClientFinalityUpdateFromBeaconState(l3.Ctx, l3.State, l3.Block, l3.AttestedState, l3.AttestedBlock, l3.FinalizedBlock)
+	require.NoError(t, err, "Failed to create light client finality update")
+
+	require.Equal(t, true, IsBetterFinalityUpdate(update3, update2), "update3 should be better than update2")
+	// update3 should not be valid for broadcast - meaning it should not be broadcasted
+	require.Equal(t, false, IsFinalityUpdateValidForBroadcast(update3, lcStore.LastFinalityUpdate()), "update3 should not be valid for broadcast")
+
+	lcStore.SetLastFinalityUpdate(update3, true)
+	require.Equal(t, update3, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
+	require.Equal(t, false, p2p.BroadcastCalled.Load(), "Broadcast should not have been when previous was already broadcast")
+
+	// update 4 with increased finality slot, increased attested slot, and supermajority - should save and broadcast
+	l4 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedFinalizedSlot(1), util.WithIncreasedAttestedSlot(1), util.WithSupermajority(0))
+	update4, err := NewLightClientFinalityUpdateFromBeaconState(l4.Ctx, l4.State, l4.Block, l4.AttestedState, l4.AttestedBlock, l4.FinalizedBlock)
+	require.NoError(t, err, "Failed to create light client finality update")
+
+	require.Equal(t, true, IsBetterFinalityUpdate(update4, update3), "update4 should be better than update3")
+	// update4 should be valid for broadcast - meaning it should be broadcasted
+	require.Equal(t, true, IsFinalityUpdateValidForBroadcast(update4, lcStore.LastFinalityUpdate()), "update4 should be valid for broadcast")
+
+	lcStore.SetLastFinalityUpdate(update4, true)
+	require.Equal(t, update4, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
+	require.Equal(t, true, p2p.BroadcastCalled.Load(), "Broadcast should have been called after a new finality update with increased finality slot")
+	p2p.BroadcastCalled.Store(false) // Reset for next test
+
+	// update 5 with the same new finality slot, increased attested slot, and supermajority - should save but not broadcast
+	l5 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedFinalizedSlot(1), util.WithIncreasedAttestedSlot(2), util.WithSupermajority(0))
+	update5, err := NewLightClientFinalityUpdateFromBeaconState(l5.Ctx, l5.State, l5.Block, l5.AttestedState, l5.AttestedBlock, l5.FinalizedBlock)
+	require.NoError(t, err, "Failed to create light client finality update")
+
+	require.Equal(t, true, IsBetterFinalityUpdate(update5, update4), "update5 should be better than update4")
+	// update5 should not be valid for broadcast - meaning it should not be broadcasted
+	require.Equal(t, false, IsFinalityUpdateValidForBroadcast(update5, lcStore.LastFinalityUpdate()), "update5 should not be valid for broadcast")
+
+	lcStore.SetLastFinalityUpdate(update5, true)
+	require.Equal(t, update5, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
+	require.Equal(t, false, p2p.BroadcastCalled.Load(), "Broadcast should not have been called when previous was already broadcast with supermajority")
+
+	// update 6 with the same new finality slot, increased attested slot, and no supermajority - should save but not broadcast
+	l6 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedFinalizedSlot(1), util.WithIncreasedAttestedSlot(3))
+	update6, err := NewLightClientFinalityUpdateFromBeaconState(l6.Ctx, l6.State, l6.Block, l6.AttestedState, l6.AttestedBlock, l6.FinalizedBlock)
+	require.NoError(t, err, "Failed to create light client finality update")
+
+	require.Equal(t, true, IsBetterFinalityUpdate(update6, update5), "update6 should be better than update5")
+	// update6 should not be valid for broadcast - meaning it should not be broadcasted
+	require.Equal(t, false, IsFinalityUpdateValidForBroadcast(update6, lcStore.LastFinalityUpdate()), "update6 should not be valid for broadcast")
+
+	lcStore.SetLastFinalityUpdate(update6, true)
+	require.Equal(t, update6, lcStore.LastFinalityUpdate(), "lastFinalityUpdate should match the set value")
+	require.Equal(t, false, p2p.BroadcastCalled.Load(), "Broadcast should not have been called when previous was already broadcast with supermajority")
+}
+
+func TestLightClientStore_SaveLCData(t *testing.T) {
+	t.Run("no parent in cache or db - new is head", func(t *testing.T) {
+		db := testDB.SetupDB(t)
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), db)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+
+		blkRoot, err := l.Block.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.NoError(t, s.SaveLCData(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock, blkRoot), "Failed to save light client data")
+
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		finalityUpdate, err := NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		optimisticUpdate, err := NewLightClientOptimisticUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock)
+		require.NoError(t, err)
+		attstedBlkRoot, err := l.AttestedBlock.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.DeepEqual(t, finalityUpdate, s.lastFinalityUpdate, "Expected to find the last finality update in the store")
+		require.DeepEqual(t, optimisticUpdate, s.lastOptimisticUpdate, "Expected to find the last optimistic update in the store")
+		require.DeepEqual(t, update, s.cache.items[attstedBlkRoot].bestUpdate, "Expected to find the update in the non-finality cache")
+		require.DeepEqual(t, finalityUpdate, s.cache.items[attstedBlkRoot].bestFinalityUpdate, "Expected to find the finality update in the non-finality cache")
+	})
+
+	t.Run("no parent in cache or db - new not head", func(t *testing.T) {
+		db := testDB.SetupDB(t)
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), db)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+
+		blkRoot, err := l.FinalizedBlock.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.NoError(t, s.SaveLCData(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock, blkRoot), "Failed to save light client data")
+
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		finalityUpdate, err := NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		optimisticUpdate, err := NewLightClientOptimisticUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock)
+		require.NoError(t, err)
+		attstedBlkRoot, err := l.AttestedBlock.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.IsNil(t, s.lastFinalityUpdate, "Expected to not find the last finality update in the store since the block is not head")
+		require.DeepEqual(t, optimisticUpdate, s.lastOptimisticUpdate, "Expected to find the last optimistic update in the store")
+		require.DeepEqual(t, update, s.cache.items[attstedBlkRoot].bestUpdate, "Expected to find the update in the non-finality cache")
+		require.DeepEqual(t, finalityUpdate, s.cache.items[attstedBlkRoot].bestFinalityUpdate, "Expected to find the finality update in the non-finality cache")
+	})
+
+	t.Run("parent in db", func(t *testing.T) {
+		db := testDB.SetupDB(t)
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), db)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+
+		// save an update for this period in db
+		period := slots.SyncCommitteePeriod(slots.ToEpoch(l.AttestedBlock.Block().Slot()))
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		require.NoError(t, db.SaveLightClientUpdate(l.Ctx, period, update), "Failed to save light client update in db")
+
+		l2 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(1), util.WithSupermajority(0)) // updates from this setup should be all better
+
+		blkRoot, err := l2.Block.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.NoError(t, s.SaveLCData(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock, blkRoot), "Failed to save light client data")
+
+		update, err = NewLightClientUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
+		require.NoError(t, err)
+		finalityUpdate, err := NewLightClientFinalityUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
+		require.NoError(t, err)
+		optimisticUpdate, err := NewLightClientOptimisticUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock)
+		require.NoError(t, err)
+		attstedBlkRoot, err := l2.AttestedBlock.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.DeepEqual(t, finalityUpdate, s.lastFinalityUpdate, "Expected to find the last finality update in the store")
+		require.DeepEqual(t, optimisticUpdate, s.lastOptimisticUpdate, "Expected to find the last optimistic update in the store")
+		require.DeepEqual(t, update, s.cache.items[attstedBlkRoot].bestUpdate, "Expected to find the update in the non-finality cache")
+		require.DeepEqual(t, finalityUpdate, s.cache.items[attstedBlkRoot].bestFinalityUpdate, "Expected to find the finality update in the non-finality cache")
+	})
+
+	t.Run("parent in cache", func(t *testing.T) {
+		db := testDB.SetupDB(t)
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), db)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+		l2 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(1), util.WithSupermajority(0)) // updates from this setup should be all better
+
+		// save the cache item for this period in cache
+		period := slots.SyncCommitteePeriod(slots.ToEpoch(l.AttestedBlock.Block().Slot()))
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		finalityUpdate, err := NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		item := &cacheItem{
+			period:             period,
+			bestUpdate:         update,
+			bestFinalityUpdate: finalityUpdate,
+		}
+		attestedBlockRoot := l2.AttestedBlock.Block().ParentRoot() // we want this item to be the parent of the new block
+		s.cache.items[attestedBlockRoot] = item
+
+		blkRoot, err := l2.Block.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.NoError(t, s.SaveLCData(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock, blkRoot), "Failed to save light client data")
+
+		update, err = NewLightClientUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
+		require.NoError(t, err)
+		finalityUpdate, err = NewLightClientFinalityUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
+		require.NoError(t, err)
+		optimisticUpdate, err := NewLightClientOptimisticUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock)
+		require.NoError(t, err)
+		attstedBlkRoot, err := l2.AttestedBlock.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.DeepEqual(t, finalityUpdate, s.lastFinalityUpdate, "Expected to find the last finality update in the store")
+		require.DeepEqual(t, optimisticUpdate, s.lastOptimisticUpdate, "Expected to find the last optimistic update in the store")
+		require.DeepEqual(t, update, s.cache.items[attstedBlkRoot].bestUpdate, "Expected to find the update in the non-finality cache")
+		require.DeepEqual(t, finalityUpdate, s.cache.items[attstedBlkRoot].bestFinalityUpdate, "Expected to find the finality update in the non-finality cache")
+	})
+
+	t.Run("parent in the previous period", func(t *testing.T) {
+		db := testDB.SetupDB(t)
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), db)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+		l2 := util.NewTestLightClient(t, version.Bellatrix, util.WithIncreasedAttestedSlot(1), util.WithSupermajority(0)) // updates from this setup should be all better
+
+		// save the cache item for this period1 in cache
+		period1 := slots.SyncCommitteePeriod(slots.ToEpoch(l.AttestedBlock.Block().Slot()))
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		finalityUpdate, err := NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		item := &cacheItem{
+			period:             period1,
+			bestUpdate:         update,
+			bestFinalityUpdate: finalityUpdate,
+		}
+		attestedBlockRoot := l2.AttestedBlock.Block().ParentRoot() // we want this item to be the parent of the new block
+		s.cache.items[attestedBlockRoot] = item
+
+		blkRoot, err := l2.Block.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.NoError(t, s.SaveLCData(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock, blkRoot), "Failed to save light client data")
+
+		update, err = NewLightClientUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
+		require.NoError(t, err)
+		finalityUpdate, err = NewLightClientFinalityUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
+		require.NoError(t, err)
+		optimisticUpdate, err := NewLightClientOptimisticUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock)
+		require.NoError(t, err)
+		attstedBlkRoot, err := l2.AttestedBlock.Block().HashTreeRoot()
+		require.NoError(t, err)
+
+		require.DeepEqual(t, finalityUpdate, s.lastFinalityUpdate, "Expected to find the last finality update in the store")
+		require.DeepEqual(t, optimisticUpdate, s.lastOptimisticUpdate, "Expected to find the last optimistic update in the store")
+		require.DeepEqual(t, update, s.cache.items[attstedBlkRoot].bestUpdate, "Expected to find the update in the non-finality cache")
+		require.DeepEqual(t, finalityUpdate, s.cache.items[attstedBlkRoot].bestFinalityUpdate, "Expected to find the finality update in the non-finality cache")
+	})
+}
+
+func TestLightClientStore_MigrateToCold(t *testing.T) {
+	// This tests the scenario where chain advances but the cache is empty.
+	// It should see that there is nothing in the cache to migrate and just update the tail to the new finalized root.
+	t.Run("empty cache", func(t *testing.T) {
+		beaconDB := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		finalizedBlockRoot, _ := saveInitialFinalizedCheckpointData(t, ctx, beaconDB)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), beaconDB)
+		require.NotNil(t, s)
+
+		for i := 0; i < 3; i++ {
+			newBlock := util.NewBeaconBlock()
+			newBlock.Block.Slot = primitives.Slot(32 + uint64(i))
+			newBlock.Block.ParentRoot = finalizedBlockRoot[:]
+			signedNewBlock, err := blocks.NewSignedBeaconBlock(newBlock)
+			require.NoError(t, err)
+			blockRoot, err := signedNewBlock.Block().HashTreeRoot()
+			require.NoError(t, err)
+			require.NoError(t, beaconDB.SaveBlock(ctx, signedNewBlock))
+			finalizedBlockRoot = blockRoot
+		}
+
+		err := s.MigrateToCold(ctx, finalizedBlockRoot)
+		require.NoError(t, err)
+		require.Equal(t, 0, len(s.cache.items))
+	})
+
+	// This tests the scenario where chain advances but the CANONICAL cache is empty.
+	// It should see that there is nothing in the canonical cache to migrate and just update the tail to the new finalized root AND delete anything non-canonical.
+	t.Run("non canonical cache", func(t *testing.T) {
+		beaconDB := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		finalizedBlockRoot, _ := saveInitialFinalizedCheckpointData(t, ctx, beaconDB)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), beaconDB)
+		require.NotNil(t, s)
+
+		for i := 0; i < 3; i++ {
+			newBlock := util.NewBeaconBlock()
+			newBlock.Block.Slot = primitives.Slot(32 + uint64(i))
+			newBlock.Block.ParentRoot = finalizedBlockRoot[:]
+			signedNewBlock, err := blocks.NewSignedBeaconBlock(newBlock)
+			require.NoError(t, err)
+			blockRoot, err := signedNewBlock.Block().HashTreeRoot()
+			require.NoError(t, err)
+			require.NoError(t, beaconDB.SaveBlock(ctx, signedNewBlock))
+			finalizedBlockRoot = blockRoot
+		}
+
+		// Add a non-canonical item to the cache
+		cacheItem := &cacheItem{
+			period: 0,
+			slot:   33,
+		}
+		nonCanonicalBlockRoot := [32]byte{1, 2, 3, 4}
+		s.cache.items[nonCanonicalBlockRoot] = cacheItem
+
+		require.Equal(t, 1, len(s.cache.items))
+
+		err := s.MigrateToCold(ctx, finalizedBlockRoot)
+		require.NoError(t, err)
+		require.Equal(t, 0, len(s.cache.items), "Expected the non-canonical item in the cache to be deleted")
+	})
+
+	// db has update - cache has both canonical and non-canonical items.
+	// should update the update in db and delete cache.
+	t.Run("mixed cache - finality immediately after cache", func(t *testing.T) {
+		beaconDB := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		finalizedBlockRoot, _ := saveInitialFinalizedCheckpointData(t, ctx, beaconDB)
+		require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, finalizedBlockRoot))
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), beaconDB)
+		require.NotNil(t, s)
+
+		// Save an update for this period in db
+		l := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		period := slots.SyncCommitteePeriod(slots.ToEpoch(l.AttestedBlock.Block().Slot()))
+		require.NoError(t, beaconDB.SaveLightClientUpdate(ctx, period, update))
+
+		lastBlockRoot := finalizedBlockRoot
+		lastAttestedRoot := finalizedBlockRoot
+		lastUpdate := update
+		for i := 1; i < 4; i++ {
+			l = util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(uint64(i)), util.WithSupermajority(uint64(i)), util.WithAttestedParentRoot(lastAttestedRoot))
+			require.NoError(t, beaconDB.SaveBlock(ctx, l.Block))
+			require.NoError(t, s.SaveLCData(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock, [32]byte{1}))
+			lastBlockRoot, err = l.Block.Block().HashTreeRoot()
+			require.NoError(t, err)
+			lastAttestedRoot, err = l.AttestedBlock.Block().HashTreeRoot()
+			require.NoError(t, err)
+			update, err = NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+			require.NoError(t, err)
+			lastUpdate = update
+		}
+
+		require.Equal(t, 3, len(s.cache.items))
+
+		// Add a non-canonical item to the cache
+		cacheItem := &cacheItem{
+			period: 0,
+			slot:   33,
+		}
+		nonCanonicalBlockRoot := [32]byte{1, 2, 3, 4}
+		s.cache.items[nonCanonicalBlockRoot] = cacheItem
+
+		require.Equal(t, 4, len(s.cache.items))
+
+		err = s.MigrateToCold(ctx, lastBlockRoot)
+		require.NoError(t, err)
+		require.Equal(t, 0, len(s.cache.items), "Expected the non-canonical item in the cache to be deleted")
+		u, err := beaconDB.LightClientUpdate(ctx, period)
+		require.NoError(t, err)
+		require.NotNil(t, u)
+		require.DeepEqual(t, lastUpdate, u)
+	})
+
+	// db has update - cache has both canonical and non-canonical items. finalized height is in the middle.
+	// should update the update in db and delete items in cache before finalized slot.
+	t.Run("mixed cache - finality middle of cache", func(t *testing.T) {
+		beaconDB := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		finalizedBlockRoot, _ := saveInitialFinalizedCheckpointData(t, ctx, beaconDB)
+		require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, finalizedBlockRoot))
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), beaconDB)
+		require.NotNil(t, s)
+
+		// Save an update for this period in db
+		l := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		period := slots.SyncCommitteePeriod(slots.ToEpoch(l.AttestedBlock.Block().Slot()))
+		require.NoError(t, beaconDB.SaveLightClientUpdate(ctx, period, update))
+
+		lastBlockRoot := finalizedBlockRoot
+		lastUpdate := update
+		lastAttestedRoot := [32]byte{}
+		for i := 1; i < 4; i++ {
+			l = util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(uint64(i)), util.WithSupermajority(uint64(i)), util.WithAttestedParentRoot(lastAttestedRoot))
+			require.NoError(t, beaconDB.SaveBlock(ctx, l.Block))
+			require.NoError(t, s.SaveLCData(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock, [32]byte{1}))
+			root, err := l.Block.Block().HashTreeRoot()
+			require.NoError(t, err)
+			lastBlockRoot = root
+			update, err = NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+			require.NoError(t, err)
+			lastUpdate = update
+			lastAttestedRoot, err = l.AttestedBlock.Block().HashTreeRoot()
+			require.NoError(t, err)
+		}
+
+		require.Equal(t, 3, len(s.cache.items))
+
+		// Add a non-canonical item to the cache
+		cacheItem := &cacheItem{
+			period: 0,
+			slot:   33,
+		}
+		nonCanonicalBlockRoot := [32]byte{1, 2, 3, 4}
+		s.cache.items[nonCanonicalBlockRoot] = cacheItem
+
+		require.Equal(t, 4, len(s.cache.items))
+
+		for i := 4; i < 7; i++ {
+			l = util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(uint64(i)), util.WithSupermajority(0), util.WithAttestedParentRoot(lastAttestedRoot))
+			require.NoError(t, beaconDB.SaveBlock(ctx, l.Block))
+			require.NoError(t, s.SaveLCData(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock, [32]byte{1}))
+			lastAttestedRoot, err = l.AttestedBlock.Block().HashTreeRoot()
+			require.NoError(t, err)
+		}
+
+		require.Equal(t, 7, len(s.cache.items))
+
+		err = s.MigrateToCold(ctx, lastBlockRoot)
+		require.NoError(t, err)
+		require.Equal(t, 3, len(s.cache.items), "Expected the non-canonical item in the cache to be deleted")
+		u, err := beaconDB.LightClientUpdate(ctx, period)
+		require.NoError(t, err)
+		require.NotNil(t, u)
+		require.DeepEqual(t, lastUpdate, u)
+	})
+
+	// we have multiple periods in the cache before finalization happens. we expect all of them to be saved in db.
+	t.Run("finality after multiple periods in cache", func(t *testing.T) {
+		beaconDB := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		cfg := params.BeaconConfig().Copy()
+		cfg.EpochsPerSyncCommitteePeriod = 1
+		params.OverrideBeaconConfig(cfg)
+
+		finalizedBlockRoot, _ := saveInitialFinalizedCheckpointData(t, ctx, beaconDB)
+		require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, finalizedBlockRoot))
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), beaconDB)
+		require.NotNil(t, s)
+
+		// Save an update for this period1 in db
+		l := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+		period1 := slots.SyncCommitteePeriod(slots.ToEpoch(l.AttestedBlock.Block().Slot()))
+		require.NoError(t, beaconDB.SaveLightClientUpdate(ctx, period1, update))
+
+		lastBlockRoot := finalizedBlockRoot
+		lastUpdatePeriod1 := update
+		lastAttestedRoot := [32]byte{}
+		for i := 1; i < 4; i++ {
+			l = util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(uint64(i)), util.WithSupermajority(uint64(i)), util.WithAttestedParentRoot(lastAttestedRoot))
+			require.NoError(t, beaconDB.SaveBlock(ctx, l.Block))
+			require.NoError(t, s.SaveLCData(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock, [32]byte{1}))
+			root, err := l.Block.Block().HashTreeRoot()
+			require.NoError(t, err)
+			lastBlockRoot = root
+			lastUpdatePeriod1, err = NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+			require.NoError(t, err)
+			lastAttestedRoot, err = l.AttestedBlock.Block().HashTreeRoot()
+			require.NoError(t, err)
+		}
+
+		period2 := period1
+		var lastUpdatePeriod2 interfaces.LightClientUpdate
+		for i := 1; i < 4; i++ {
+			l = util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(uint64(i)+33), util.WithSupermajority(uint64(i)), util.WithAttestedParentRoot(lastAttestedRoot))
+			require.NoError(t, beaconDB.SaveBlock(ctx, l.Block))
+			require.NoError(t, s.SaveLCData(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock, [32]byte{1}))
+			root, err := l.Block.Block().HashTreeRoot()
+			require.NoError(t, err)
+			lastBlockRoot = root
+			lastUpdatePeriod2, err = NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+			require.NoError(t, err)
+			lastAttestedRoot, err = l.AttestedBlock.Block().HashTreeRoot()
+			require.NoError(t, err)
+			period2 = slots.SyncCommitteePeriod(slots.ToEpoch(l.AttestedBlock.Block().Slot()))
+		}
+
+		require.Equal(t, 6, len(s.cache.items))
+
+		// Add a non-canonical item to the cache
+		cacheItem := &cacheItem{
+			period: 0,
+			slot:   33,
+		}
+		nonCanonicalBlockRoot := [32]byte{1, 2, 3, 4}
+		s.cache.items[nonCanonicalBlockRoot] = cacheItem
+
+		require.Equal(t, 7, len(s.cache.items))
+
+		for i := 4; i < 7; i++ {
+			l = util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(uint64(i)+33), util.WithSupermajority(0), util.WithAttestedParentRoot(lastAttestedRoot))
+			require.NoError(t, beaconDB.SaveBlock(ctx, l.Block))
+			require.NoError(t, s.SaveLCData(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock, [32]byte{1}))
+			lastAttestedRoot, err = l.AttestedBlock.Block().HashTreeRoot()
+			require.NoError(t, err)
+		}
+
+		require.Equal(t, 10, len(s.cache.items))
+
+		err = s.MigrateToCold(ctx, lastBlockRoot)
+		require.NoError(t, err)
+		require.Equal(t, 3, len(s.cache.items), "Expected the non-canonical item in the cache to be deleted")
+		u, err := beaconDB.LightClientUpdate(ctx, period2)
+		require.NoError(t, err)
+		require.NotNil(t, u)
+		require.DeepEqual(t, lastUpdatePeriod2, u)
+		u, err = beaconDB.LightClientUpdate(ctx, period1)
+		require.NoError(t, err)
+		require.NotNil(t, u)
+		require.DeepEqual(t, lastUpdatePeriod1, u)
+	})
+}
+
+func saveInitialFinalizedCheckpointData(t *testing.T, ctx context.Context, beaconDB db.Database) ([32]byte, interfaces.SignedBeaconBlock) {
+	genesis := util.NewBeaconBlock()
+	genesisRoot, err := genesis.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
+	util.SaveBlock(t, ctx, beaconDB, genesis)
+	genesisState, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveState(ctx, genesisState, genesisRoot))
+
+	finalizedState, err := util.NewBeaconState()
+	require.NoError(t, err)
+	finalizedBlock := util.NewBeaconBlock()
+	finalizedBlock.Block.Slot = 32
+	finalizedBlock.Block.ParentRoot = genesisRoot[:]
+	signedFinalizedBlock, err := blocks.NewSignedBeaconBlock(finalizedBlock)
+	require.NoError(t, err)
+	finalizedBlockHeader, err := signedFinalizedBlock.Header()
+	require.NoError(t, err)
+	require.NoError(t, finalizedState.SetLatestBlockHeader(finalizedBlockHeader.Header))
+	finalizedStateRoot, err := finalizedState.HashTreeRoot(ctx)
+	require.NoError(t, err)
+	finalizedBlock.Block.StateRoot = finalizedStateRoot[:]
+	signedFinalizedBlock, err = blocks.NewSignedBeaconBlock(finalizedBlock)
+	require.NoError(t, err)
+	finalizedBlockRoot, err := signedFinalizedBlock.Block().HashTreeRoot()
+	require.NoError(t, err)
+	cp := ethpb.Checkpoint{
+		Epoch: 1,
+		Root:  finalizedBlockRoot[:],
+	}
+	require.NoError(t, beaconDB.SaveBlock(ctx, signedFinalizedBlock))
+	require.NoError(t, beaconDB.SaveState(ctx, finalizedState, finalizedBlockRoot))
+	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &cp))
+
+	return finalizedBlockRoot, signedFinalizedBlock
+}
+
+func TestLightClientStore_LightClientUpdatesByRange(t *testing.T) {
+	t.Run("no updates", func(t *testing.T) {
+		d := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		_, finalizedBlock := saveInitialFinalizedCheckpointData(t, ctx, d)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), d)
+		require.NotNil(t, s)
+
+		updates, err := s.LightClientUpdates(ctx, 2, 5, finalizedBlock)
+		require.NoError(t, err)
+		require.Equal(t, 0, len(updates))
+	})
+
+	t.Run("single update from db", func(t *testing.T) {
+		d := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		_, finalizedBlock := saveInitialFinalizedCheckpointData(t, ctx, d)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), d)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 3, update))
+
+		updates, err := s.LightClientUpdates(ctx, 3, 3, finalizedBlock)
+		require.NoError(t, err)
+		require.Equal(t, 1, len(updates))
+		require.DeepEqual(t, update, updates[0], "Expected to find the update in the store")
+	})
+
+	t.Run("multiple updates from db", func(t *testing.T) {
+		d := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		_, finalizedBlock := saveInitialFinalizedCheckpointData(t, ctx, d)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), d)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 3, update))
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 4, update))
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 5, update))
+
+		updates, err := s.LightClientUpdates(ctx, 3, 5, finalizedBlock)
+		require.NoError(t, err)
+		require.Equal(t, 3, len(updates))
+		require.DeepEqual(t, update, updates[0], "Expected to find the update in the store")
+		require.DeepEqual(t, update, updates[1], "Expected to find the update in the store")
+		require.DeepEqual(t, update, updates[2], "Expected to find the update in the store")
+	})
+
+	t.Run("single update from cache", func(t *testing.T) {
+		d := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		_, _ = saveInitialFinalizedCheckpointData(t, ctx, d)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), d)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+
+		cacheItem := &cacheItem{
+			period:     3,
+			bestUpdate: update,
+		}
+		s.cache.items[[32]byte{3}] = cacheItem
+
+		_, headBlock := saveStateAndBlockWithParentRoot(t, ctx, d, [32]byte{3})
+
+		updates, err := s.LightClientUpdates(ctx, 3, 3, headBlock)
+		require.NoError(t, err)
+		require.Equal(t, 1, len(updates))
+		require.DeepEqual(t, update, updates[0], "Expected to find the update in the store")
+	})
+
+	t.Run("multiple updates from cache", func(t *testing.T) {
+		d := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		_, _ = saveInitialFinalizedCheckpointData(t, ctx, d)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), d)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+
+		cacheItemP3 := &cacheItem{
+			period:     3,
+			bestUpdate: update,
+		}
+		s.cache.items[[32]byte{3}] = cacheItemP3
+
+		cacheItemP4 := &cacheItem{
+			period:     4,
+			bestUpdate: update,
+			parent:     cacheItemP3,
+		}
+		s.cache.items[[32]byte{4}] = cacheItemP4
+
+		cacheItemP5 := &cacheItem{
+			period:     5,
+			bestUpdate: update,
+			parent:     cacheItemP4,
+		}
+		s.cache.items[[32]byte{5}] = cacheItemP5
+
+		_, headBlock := saveStateAndBlockWithParentRoot(t, ctx, d, [32]byte{5})
+
+		updates, err := s.LightClientUpdates(ctx, 3, 5, headBlock)
+		require.NoError(t, err)
+		require.Equal(t, 3, len(updates))
+		require.DeepEqual(t, update, updates[0], "Expected to find the update in the store")
+		require.DeepEqual(t, update, updates[1], "Expected to find the update in the store")
+		require.DeepEqual(t, update, updates[2], "Expected to find the update in the store")
+	})
+
+	t.Run("multiple updates from both db and cache - no overlap", func(t *testing.T) {
+		d := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		_, _ = saveInitialFinalizedCheckpointData(t, ctx, d)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), d)
+		require.NotNil(t, s)
+
+		l := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l.Ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+		require.NoError(t, err)
+
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 1, update))
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 2, update))
+
+		cacheItemP3 := &cacheItem{
+			period:     3,
+			bestUpdate: update,
+		}
+		s.cache.items[[32]byte{3}] = cacheItemP3
+
+		cacheItemP4 := &cacheItem{
+			period:     4,
+			bestUpdate: update,
+			parent:     cacheItemP3,
+		}
+		s.cache.items[[32]byte{4}] = cacheItemP4
+
+		cacheItemP5 := &cacheItem{
+			period:     5,
+			bestUpdate: update,
+			parent:     cacheItemP4,
+		}
+		s.cache.items[[32]byte{5}] = cacheItemP5
+
+		_, headBlock := saveStateAndBlockWithParentRoot(t, ctx, d, [32]byte{5})
+
+		updates, err := s.LightClientUpdates(ctx, 1, 5, headBlock)
+		require.NoError(t, err)
+		require.Equal(t, 5, len(updates))
+		for i := 0; i < 5; i++ {
+			require.DeepEqual(t, update, updates[i], "Expected to find the update in the store")
+		}
+	})
+
+	t.Run("multiple updates from both db and cache - overlap", func(t *testing.T) {
+		d := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		_, _ = saveInitialFinalizedCheckpointData(t, ctx, d)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), d)
+		require.NotNil(t, s)
+
+		l1 := util.NewTestLightClient(t, version.Altair)
+		update1, err := NewLightClientUpdateFromBeaconState(l1.Ctx, l1.State, l1.Block, l1.AttestedState, l1.AttestedBlock, l1.FinalizedBlock)
+		require.NoError(t, err)
+
+		l2 := util.NewTestLightClient(t, version.Altair, util.WithIncreasedAttestedSlot(1))
+		update2, err := NewLightClientUpdateFromBeaconState(l2.Ctx, l2.State, l2.Block, l2.AttestedState, l2.AttestedBlock, l2.FinalizedBlock)
+		require.NoError(t, err)
+
+		require.DeepNotEqual(t, update1, update2)
+
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 1, update1))
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 2, update1))
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 3, update1))
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 4, update1))
+
+		cacheItemP3 := &cacheItem{
+			period:     3,
+			bestUpdate: update2,
+		}
+		s.cache.items[[32]byte{3}] = cacheItemP3
+
+		cacheItemP4 := &cacheItem{
+			period:     4,
+			bestUpdate: update2,
+			parent:     cacheItemP3,
+		}
+		s.cache.items[[32]byte{4}] = cacheItemP4
+
+		cacheItemP5 := &cacheItem{
+			period:     5,
+			bestUpdate: update2,
+			parent:     cacheItemP4,
+		}
+		s.cache.items[[32]byte{5}] = cacheItemP5
+
+		_, headBlock := saveStateAndBlockWithParentRoot(t, ctx, d, [32]byte{5})
+
+		updates, err := s.LightClientUpdates(ctx, 1, 5, headBlock)
+		require.NoError(t, err)
+		require.Equal(t, 5, len(updates))
+		// first two updates should be update1
+		for i := 0; i < 2; i++ {
+			require.DeepEqual(t, update1, updates[i], "Expected to find the update in the store")
+		}
+		// next three updates should be update2 - as cache overrides db
+		for i := 2; i < 5; i++ {
+			require.DeepEqual(t, update2, updates[i], "Expected to find the update in the store")
+		}
+	})
+
+	t.Run("first continuous range", func(t *testing.T) {
+		d := testDB.SetupDB(t)
+		ctx := context.Background()
+
+		_, _ = saveInitialFinalizedCheckpointData(t, ctx, d)
+
+		s := NewLightClientStore(&p2pTesting.FakeP2P{}, new(event.Feed), d)
+		require.NotNil(t, s)
+
+		l1 := util.NewTestLightClient(t, version.Altair)
+		update, err := NewLightClientUpdateFromBeaconState(l1.Ctx, l1.State, l1.Block, l1.AttestedState, l1.AttestedBlock, l1.FinalizedBlock)
+		require.NoError(t, err)
+
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 1, update))
+		require.NoError(t, d.SaveLightClientUpdate(ctx, 2, update))
+
+		cacheItemP4 := &cacheItem{
+			period:     4,
+			bestUpdate: update,
+		}
+		s.cache.items[[32]byte{4}] = cacheItemP4
+
+		cacheItemP5 := &cacheItem{
+			period:     5,
+			bestUpdate: update,
+			parent:     cacheItemP4,
+		}
+		s.cache.items[[32]byte{5}] = cacheItemP5
+
+		_, headBlock := saveStateAndBlockWithParentRoot(t, ctx, d, [32]byte{5})
+
+		updates, err := s.LightClientUpdates(ctx, 1, 5, headBlock)
+		require.NoError(t, err)
+		require.Equal(t, 2, len(updates))
+		require.DeepEqual(t, update, updates[0], "Expected to find the update in the store")
+		require.DeepEqual(t, update, updates[1], "Expected to find the update in the store")
+	})
+
+}
+
+func saveStateAndBlockWithParentRoot(t *testing.T, ctx context.Context, d db.Database, parentRoot [32]byte) ([32]byte, interfaces.SignedBeaconBlock) {
+	blk := util.NewBeaconBlock()
+	blk.Block.ParentRoot = parentRoot[:]
+
+	blkRoot, err := blk.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	util.SaveBlock(t, ctx, d, blk)
+
+	st, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, d.SaveState(ctx, st, blkRoot))
+
+	signedFinalizedBlock, err := blocks.NewSignedBeaconBlock(blk)
+	require.NoError(t, err)
+
+	return blkRoot, signedFinalizedBlock
+}

beacon-chain/node/BUILD.bazel

@@ -23,7 +23,6 @@ go_library(
         "//beacon-chain/builder:go_default_library",
         "//beacon-chain/cache:go_default_library",
         "//beacon-chain/cache/depositsnapshot:go_default_library",
-        "//beacon-chain/core/light-client:go_default_library",
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/filesystem:go_default_library",
         "//beacon-chain/db/kv:go_default_library",
@@ -32,6 +31,7 @@ go_library(
         "//beacon-chain/execution:go_default_library",
         "//beacon-chain/forkchoice:go_default_library",
         "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
+        "//beacon-chain/light-client:go_default_library",
         "//beacon-chain/monitor:go_default_library",
         "//beacon-chain/node/registration:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",

beacon-chain/node/node.go

@@ -25,7 +25,6 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/builder"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache/depositsnapshot"
-	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/kv"
@@ -34,6 +33,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/execution"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice"
 	doublylinkedtree "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/doubly-linked-tree"
+	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/monitor"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/node/registration"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations"
@@ -128,6 +128,7 @@ type BeaconNode struct {
 	slasherEnabled           bool
 	lcStore                  *lightclient.Store
 	ConfigOptions            []params.Option
+	syncToggle               *regularsync.ServiceToggler
 }
 
 // New creates a new node instance, sets up configuration options, and registers
@@ -161,6 +162,7 @@ func New(cliCtx *cli.Context, cancel context.CancelFunc, opts ...Option) (*Beaco
 		initialSyncComplete:     make(chan struct{}),
 		syncChecker:             &initialsync.SyncChecker{},
 		slasherEnabled:          cliCtx.Bool(flags.SlasherFlag.Name),
+		syncToggle:              regularsync.NewServiceToggler(),
 	}
 
 	for _, opt := range opts {
@@ -234,6 +236,7 @@ func New(cliCtx *cli.Context, cancel context.CancelFunc, opts ...Option) (*Beaco
 		beacon.BackfillOpts,
 		backfill.WithVerifierWaiter(beacon.verifyInitWaiter),
 		backfill.WithInitSyncWaiter(initSyncWaiter(ctx, beacon.initialSyncComplete)),
+		backfill.WithServiceToggle(beacon.syncToggle),
 	)
 
 	if err := registerServices(cliCtx, beacon, synchronizer, bfs); err != nil {
@@ -253,10 +256,6 @@ func New(cliCtx *cli.Context, cancel context.CancelFunc, opts ...Option) (*Beaco
 	// their initialization.
 	beacon.finalizedStateAtStartUp = nil
 
-	if features.Get().EnableLightClient {
-		beacon.lcStore = lightclient.NewLightClientStore(beacon.db, beacon.fetchP2P(), beacon.StateFeed())
-	}
-
 	return beacon, nil
 }
 
@@ -349,6 +348,11 @@ func registerServices(cliCtx *cli.Context, beacon *BeaconNode, synchronizer *sta
 		return errors.Wrap(err, "could not register P2P service")
 	}
 
+	if features.Get().EnableLightClient {
+		log.Debugln("Registering Light Client Store")
+		beacon.registerLightClientStore()
+	}
+
 	log.Debugln("Registering Backfill Service")
 	if err := beacon.RegisterBackfillService(cliCtx, bfs); err != nil {
 		return errors.Wrap(err, "could not register Back Fill service")
@@ -370,7 +374,7 @@ func registerServices(cliCtx *cli.Context, beacon *BeaconNode, synchronizer *sta
 	}
 
 	log.Debugln("Registering Initial Sync Service")
-	if err := beacon.registerInitialSyncService(beacon.initialSyncComplete); err != nil {
+	if err := beacon.registerInitialSyncService(beacon.initialSyncComplete, beacon.syncToggle); err != nil {
 		return errors.Wrap(err, "could not register initial sync service")
 	}
 
@@ -621,35 +625,55 @@ func (b *BeaconNode) startStateGen(ctx context.Context, bfs coverage.AvailableBl
 	return nil
 }
 
+func parseIPNetStrings(ipWhitelist []string) ([]*net.IPNet, error) {
+	ipNets := make([]*net.IPNet, 0, len(ipWhitelist))
+	for _, cidr := range ipWhitelist {
+		_, ipNet, err := net.ParseCIDR(cidr)
+		if err != nil {
+			log.WithError(err).WithField("cidr", cidr).Error("Invalid CIDR in IP colocation whitelist")
+			return nil, err
+		}
+		ipNets = append(ipNets, ipNet)
+		log.WithField("cidr", cidr).Info("Added IP to colocation whitelist")
+	}
+	return ipNets, nil
+}
+
 func (b *BeaconNode) registerP2P(cliCtx *cli.Context) error {
 	bootstrapNodeAddrs, dataDir, err := registration.P2PPreregistration(cliCtx)
 	if err != nil {
 		return errors.Wrapf(err, "could not register p2p service")
 	}
 
+	colocationWhitelist, err := parseIPNetStrings(slice.SplitCommaSeparated(cliCtx.StringSlice(cmd.P2PColocationWhitelist.Name)))
+	if err != nil {
+		return fmt.Errorf("failed to register p2p service: %w", err)
+	}
+
 	svc, err := p2p.NewService(b.ctx, &p2p.Config{
-		NoDiscovery:          cliCtx.Bool(cmd.NoDiscovery.Name),
-		StaticPeers:          slice.SplitCommaSeparated(cliCtx.StringSlice(cmd.StaticPeers.Name)),
-		Discv5BootStrapAddrs: p2p.ParseBootStrapAddrs(bootstrapNodeAddrs),
-		RelayNodeAddr:        cliCtx.String(cmd.RelayNode.Name),
-		DataDir:              dataDir,
-		DiscoveryDir:         filepath.Join(dataDir, "discovery"),
-		LocalIP:              cliCtx.String(cmd.P2PIP.Name),
-		HostAddress:          cliCtx.String(cmd.P2PHost.Name),
-		HostDNS:              cliCtx.String(cmd.P2PHostDNS.Name),
-		PrivateKey:           cliCtx.String(cmd.P2PPrivKey.Name),
-		StaticPeerID:         cliCtx.Bool(cmd.P2PStaticID.Name),
-		QUICPort:             cliCtx.Uint(cmd.P2PQUICPort.Name),
-		TCPPort:              cliCtx.Uint(cmd.P2PTCPPort.Name),
-		UDPPort:              cliCtx.Uint(cmd.P2PUDPPort.Name),
-		MaxPeers:             cliCtx.Uint(cmd.P2PMaxPeers.Name),
-		QueueSize:            cliCtx.Uint(cmd.PubsubQueueSize.Name),
-		AllowListCIDR:        cliCtx.String(cmd.P2PAllowList.Name),
-		DenyListCIDR:         slice.SplitCommaSeparated(cliCtx.StringSlice(cmd.P2PDenyList.Name)),
-		EnableUPnP:           cliCtx.Bool(cmd.EnableUPnPFlag.Name),
-		StateNotifier:        b,
-		DB:                   b.db,
-		ClockWaiter:          b.clockWaiter,
+		NoDiscovery:           cliCtx.Bool(cmd.NoDiscovery.Name),
+		StaticPeers:           slice.SplitCommaSeparated(cliCtx.StringSlice(cmd.StaticPeers.Name)),
+		Discv5BootStrapAddrs:  p2p.ParseBootStrapAddrs(bootstrapNodeAddrs),
+		RelayNodeAddr:         cliCtx.String(cmd.RelayNode.Name),
+		DataDir:               dataDir,
+		DiscoveryDir:          filepath.Join(dataDir, "discovery"),
+		LocalIP:               cliCtx.String(cmd.P2PIP.Name),
+		HostAddress:           cliCtx.String(cmd.P2PHost.Name),
+		HostDNS:               cliCtx.String(cmd.P2PHostDNS.Name),
+		PrivateKey:            cliCtx.String(cmd.P2PPrivKey.Name),
+		StaticPeerID:          cliCtx.Bool(cmd.P2PStaticID.Name),
+		QUICPort:              cliCtx.Uint(cmd.P2PQUICPort.Name),
+		TCPPort:               cliCtx.Uint(cmd.P2PTCPPort.Name),
+		UDPPort:               cliCtx.Uint(cmd.P2PUDPPort.Name),
+		MaxPeers:              cliCtx.Uint(cmd.P2PMaxPeers.Name),
+		QueueSize:             cliCtx.Uint(cmd.PubsubQueueSize.Name),
+		AllowListCIDR:         cliCtx.String(cmd.P2PAllowList.Name),
+		DenyListCIDR:          slice.SplitCommaSeparated(cliCtx.StringSlice(cmd.P2PDenyList.Name)),
+		IPColocationWhitelist: colocationWhitelist,
+		EnableUPnP:            cliCtx.Bool(cmd.EnableUPnPFlag.Name),
+		StateNotifier:         b,
+		DB:                    b.db,
+		ClockWaiter:           b.clockWaiter,
 	})
 	if err != nil {
 		return err
@@ -827,7 +851,7 @@ func (b *BeaconNode) registerSyncService(initialSyncComplete chan struct{}, bFil
 	return b.services.RegisterService(rs)
 }
 
-func (b *BeaconNode) registerInitialSyncService(complete chan struct{}) error {
+func (b *BeaconNode) registerInitialSyncService(complete chan struct{}, toggler *regularsync.ServiceToggler) error {
 	var chainService *blockchain.Service
 	if err := b.services.FetchService(&chainService); err != nil {
 		return err
@@ -836,6 +860,7 @@ func (b *BeaconNode) registerInitialSyncService(complete chan struct{}) error {
 	opts := []initialsync.Option{
 		initialsync.WithVerifierWaiter(b.verifyInitWaiter),
 		initialsync.WithSyncChecker(b.syncChecker),
+		initialsync.WithServiceToggle(toggler),
 	}
 	is := initialsync.NewService(b.ctx, &initialsync.Config{
 		DB:                  b.db,
@@ -1119,6 +1144,11 @@ func (b *BeaconNode) RegisterBackfillService(cliCtx *cli.Context, bfs *backfill.
 	return b.services.RegisterService(bf)
 }
 
+func (b *BeaconNode) registerLightClientStore() {
+	lcs := lightclient.NewLightClientStore(b.fetchP2P(), b.StateFeed(), b.db)
+	b.lcStore = lcs
+}
+
 func hasNetworkFlag(cliCtx *cli.Context) bool {
 	for _, flag := range features.NetworkFlags {
 		for _, name := range flag.Names() {

beacon-chain/node/node_test.go

@@ -74,7 +74,9 @@ func TestNodeStart_Ok(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	set.String("datadir", tmp, "node data directory")
 	set.String("suggested-fee-recipient", "0x6e35733c5af9B61374A128e6F85f553aF09ff89A", "fee recipient")
+	set.Bool("enable-light-client", true, "enable light client")
 	require.NoError(t, set.Set("suggested-fee-recipient", "0x6e35733c5af9B61374A128e6F85f553aF09ff89A"))
+	require.NoError(t, set.Set("enable-light-client", "true"))
 
 	ctx, cancel := newCliContextWithCancel(&app, set)
 
@@ -88,6 +90,7 @@ func TestNodeStart_Ok(t *testing.T) {
 
 	node, err := New(ctx, cancel, options...)
 	require.NoError(t, err)
+	require.NotNil(t, node.lcStore)
 	node.services = &runtime.ServiceRegistry{}
 	go func() {
 		node.Start()
@@ -262,3 +265,46 @@ func TestCORS(t *testing.T) {
 		})
 	}
 }
+
+func TestParseIPNetStrings(t *testing.T) {
+	tests := []struct {
+		name      string
+		whitelist []string
+		wantCount int
+		wantError string
+	}{
+		{
+			name:      "empty whitelist",
+			whitelist: []string{},
+			wantCount: 0,
+		},
+		{
+			name:      "single IP whitelist",
+			whitelist: []string{"192.168.1.1/32"},
+			wantCount: 1,
+		},
+		{
+			name:      "multiple IPs whitelist",
+			whitelist: []string{"192.168.1.0/24", "10.0.0.0/8", "34.42.19.170/32"},
+			wantCount: 3,
+		},
+		{
+			name:      "invalid CIDR returns error",
+			whitelist: []string{"192.168.1.0/24", "invalid-cidr", "10.0.0.0/8"},
+			wantCount: 0,
+			wantError: "invalid CIDR address",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := parseIPNetStrings(tt.whitelist)
+			assert.Equal(t, tt.wantCount, len(result))
+			if len(tt.wantError) == 0 {
+				assert.Equal(t, nil, err)
+			} else {
+				assert.ErrorContains(t, tt.wantError, err)
+			}
+		})
+	}
+}

beacon-chain/p2p/BUILD.bazel

@@ -60,6 +60,7 @@ go_library(
         "//config/features:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
+        "//consensus-types/blocks:go_default_library",
         "//consensus-types/interfaces:go_default_library",
         "//consensus-types/primitives:go_default_library",
         "//consensus-types/wrapper:go_default_library",
@@ -95,6 +96,7 @@ go_library(
         "@com_github_libp2p_go_libp2p//core/peer:go_default_library",
         "@com_github_libp2p_go_libp2p//core/peerstore:go_default_library",
         "@com_github_libp2p_go_libp2p//core/protocol:go_default_library",
+        "@com_github_libp2p_go_libp2p//p2p/net/connmgr:go_default_library",
         "@com_github_libp2p_go_libp2p//p2p/security/noise:go_default_library",
         "@com_github_libp2p_go_libp2p//p2p/transport/quic:go_default_library",
         "@com_github_libp2p_go_libp2p//p2p/transport/tcp:go_default_library",
@@ -184,6 +186,7 @@ go_test(
         "@com_github_ethereum_go_ethereum//p2p/enr:go_default_library",
         "@com_github_golang_snappy//:go_default_library",
         "@com_github_libp2p_go_libp2p//:go_default_library",
+        "@com_github_libp2p_go_libp2p//core/connmgr:go_default_library",
         "@com_github_libp2p_go_libp2p//core/crypto:go_default_library",
         "@com_github_libp2p_go_libp2p//core/host:go_default_library",
         "@com_github_libp2p_go_libp2p//core/network:go_default_library",

beacon-chain/p2p/broadcaster.go

@@ -11,6 +11,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/crypto/hash"
 	"github.com/OffchainLabs/prysm/v6/monitoring/tracing"
@@ -308,19 +309,13 @@ func (s *Service) BroadcastLightClientFinalityUpdate(ctx context.Context, update
 // BroadcastDataColumnSidecar broadcasts a data column to the p2p network, the message is assumed to be
 // broadcasted to the current fork and to the input column subnet.
 func (s *Service) BroadcastDataColumnSidecar(
-	root [fieldparams.RootLength]byte,
 	dataColumnSubnet uint64,
-	dataColumnSidecar *ethpb.DataColumnSidecar,
+	dataColumnSidecar blocks.VerifiedRODataColumn,
 ) error {
 	// Add tracing to the function.
 	ctx, span := trace.StartSpan(s.ctx, "p2p.BroadcastDataColumnSidecar")
 	defer span.End()
 
-	// Ensure the data column sidecar is not nil.
-	if dataColumnSidecar == nil {
-		return errors.Errorf("attempted to broadcast nil data column sidecar at subnet %d", dataColumnSubnet)
-	}
-
 	// Retrieve the current fork digest.
 	forkDigest, err := s.currentForkDigest()
 	if err != nil {
@@ -330,16 +325,15 @@ func (s *Service) BroadcastDataColumnSidecar(
 	}
 
 	// Non-blocking broadcast, with attempts to discover a column subnet peer if none available.
-	go s.internalBroadcastDataColumnSidecar(ctx, root, dataColumnSubnet, dataColumnSidecar, forkDigest)
+	go s.internalBroadcastDataColumnSidecar(ctx, dataColumnSubnet, dataColumnSidecar, forkDigest)
 
 	return nil
 }
 
 func (s *Service) internalBroadcastDataColumnSidecar(
 	ctx context.Context,
-	root [fieldparams.RootLength]byte,
 	columnSubnet uint64,
-	dataColumnSidecar *ethpb.DataColumnSidecar,
+	dataColumnSidecar blocks.VerifiedRODataColumn,
 	forkDigest [fieldparams.VersionLength]byte,
 ) {
 	// Add tracing to the function.
@@ -385,7 +379,7 @@ func (s *Service) internalBroadcastDataColumnSidecar(
 	log.WithFields(logrus.Fields{
 		"slot":               slot,
 		"timeSinceSlotStart": time.Since(slotStartTime),
-		"root":               fmt.Sprintf("%#x", root),
+		"root":               fmt.Sprintf("%#x", dataColumnSidecar.BlockRoot()),
 		"columnSubnet":       columnSubnet,
 	}).Debug("Broadcasted data column sidecar")
 

beacon-chain/p2p/broadcaster_test.go

@@ -711,13 +711,8 @@ func TestService_BroadcastDataColumn(t *testing.T) {
 	subnet := peerdas.ComputeSubnetForDataColumnSidecar(columnIndex)
 	topic := fmt.Sprintf(topicFormat, digest, subnet) + service.Encoding().ProtocolSuffix()
 
-	roSidecars, _ := util.CreateTestVerifiedRoDataColumnSidecars(t, []util.DataColumnParam{{Index: columnIndex}})
-	sidecar := roSidecars[0].DataColumnSidecar
-
-	// Attempt to broadcast nil object should fail.
-	var emptyRoot [fieldparams.RootLength]byte
-	err = service.BroadcastDataColumnSidecar(emptyRoot, subnet, nil)
-	require.ErrorContains(t, "attempted to broadcast nil", err)
+	_, verifiedRoSidecars := util.CreateTestVerifiedRoDataColumnSidecars(t, []util.DataColumnParam{{Index: columnIndex}})
+	verifiedRoSidecar := verifiedRoSidecars[0]
 
 	// Subscribe to the topic.
 	sub, err := p2.SubscribeToTopic(topic)
@@ -727,7 +722,7 @@ func TestService_BroadcastDataColumn(t *testing.T) {
 	time.Sleep(50 * time.Millisecond)
 
 	// Broadcast to peers and wait.
-	err = service.BroadcastDataColumnSidecar(emptyRoot, subnet, sidecar)
+	err = service.BroadcastDataColumnSidecar(subnet, verifiedRoSidecar)
 	require.NoError(t, err)
 
 	// Receive the message.
@@ -739,5 +734,5 @@ func TestService_BroadcastDataColumn(t *testing.T) {
 
 	var result ethpb.DataColumnSidecar
 	require.NoError(t, service.Encoding().DecodeGossip(msg.Data, &result))
-	require.DeepEqual(t, &result, sidecar)
+	require.DeepEqual(t, &result, verifiedRoSidecar)
 }

beacon-chain/p2p/config.go

@@ -1,6 +1,7 @@
 package p2p
 
 import (
+	"net"
 	"time"
 
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
@@ -10,34 +11,56 @@ import (
 
 // This is the default queue size used if we have specified an invalid one.
 const defaultPubsubQueueSize = 600
+const (
+	// defaultConnManagerPruneAbove sets the number of peers where ConnectionManager
+	// will begin to internally prune peers. This value is set based on the internal
+	// value of the libp2p DefaultConectionManager "high water mark". The "low water mark"
+	// is the number of peers where ConnManager will stop pruning. This value is computed
+	// by subtracting connManagerPruneAmount from the high water mark.
+	defaultConnManagerPruneAbove = 192
+	connManagerPruneAmount       = 32
+)
 
 // Config for the p2p service. These parameters are set from application level flags
 // to initialize the p2p service.
 type Config struct {
-	NoDiscovery          bool
-	EnableUPnP           bool
-	StaticPeerID         bool
-	DisableLivenessCheck bool
-	StaticPeers          []string
-	Discv5BootStrapAddrs []string
-	RelayNodeAddr        string
-	LocalIP              string
-	HostAddress          string
-	HostDNS              string
-	PrivateKey           string
-	DataDir              string
-	DiscoveryDir         string
-	QUICPort             uint
-	TCPPort              uint
-	UDPPort              uint
-	PingInterval         time.Duration
-	MaxPeers             uint
-	QueueSize            uint
-	AllowListCIDR        string
-	DenyListCIDR         []string
-	StateNotifier        statefeed.Notifier
-	DB                   db.ReadOnlyDatabaseWithSeqNum
-	ClockWaiter          startup.ClockWaiter
+	NoDiscovery           bool
+	EnableUPnP            bool
+	StaticPeerID          bool
+	DisableLivenessCheck  bool
+	StaticPeers           []string
+	Discv5BootStrapAddrs  []string
+	RelayNodeAddr         string
+	LocalIP               string
+	HostAddress           string
+	HostDNS               string
+	PrivateKey            string
+	DataDir               string
+	DiscoveryDir          string
+	QUICPort              uint
+	TCPPort               uint
+	UDPPort               uint
+	PingInterval          time.Duration
+	MaxPeers              uint
+	QueueSize             uint
+	AllowListCIDR         string
+	DenyListCIDR          []string
+	IPColocationWhitelist []*net.IPNet
+	StateNotifier         statefeed.Notifier
+	DB                    db.ReadOnlyDatabaseWithSeqNum
+	ClockWaiter           startup.ClockWaiter
+}
+
+// connManagerLowHigh picks the low and high water marks for the connection manager based
+// on the MaxPeers setting. The high water mark will be at least the default high water mark
+// (192), or MaxPeers + 32, whichever is higher. The low water mark is set to be 32 less than
+// the high water mark. This is done to ensure the ConnManager never prunes peers that the
+// node has connected to based on the MaxPeers setting.
+func (cfg *Config) connManagerLowHigh() (int, int) {
+	maxPeersPlusMargin := int(cfg.MaxPeers) + connManagerPruneAmount
+	high := max(maxPeersPlusMargin, defaultConnManagerPruneAbove)
+	low := high - connManagerPruneAmount
+	return low, high
 }
 
 // validateConfig validates whether the values provided are accurate and will set

beacon-chain/p2p/gossip_scoring_params.go

@@ -3,6 +3,7 @@ package p2p
 import (
 	"context"
 	"math"
+	"net"
 	"reflect"
 	"strings"
 	"time"
@@ -75,7 +76,7 @@ var (
 	tenEpochs          = 10 * oneEpochDuration()
 )
 
-func peerScoringParams() (*pubsub.PeerScoreParams, *pubsub.PeerScoreThresholds) {
+func peerScoringParams(colocationWhitelist []*net.IPNet) (*pubsub.PeerScoreParams, *pubsub.PeerScoreThresholds) {
 	thresholds := &pubsub.PeerScoreThresholds{
 		GossipThreshold:             -4000,
 		PublishThreshold:            -8000,
@@ -83,6 +84,7 @@ func peerScoringParams() (*pubsub.PeerScoreParams, *pubsub.PeerScoreThresholds)
 		AcceptPXThreshold:           100,
 		OpportunisticGraftThreshold: 5,
 	}
+
 	scoreParams := &pubsub.PeerScoreParams{
 		Topics:        make(map[string]*pubsub.TopicScoreParams),
 		TopicScoreCap: 32.72,
@@ -92,7 +94,7 @@ func peerScoringParams() (*pubsub.PeerScoreParams, *pubsub.PeerScoreThresholds)
 		AppSpecificWeight:           1,
 		IPColocationFactorWeight:    -35.11,
 		IPColocationFactorThreshold: 10,
-		IPColocationFactorWhitelist: nil,
+		IPColocationFactorWhitelist: colocationWhitelist,
 		BehaviourPenaltyWeight:      -15.92,
 		BehaviourPenaltyThreshold:   6,
 		BehaviourPenaltyDecay:       scoreDecay(tenEpochs),

beacon-chain/p2p/interfaces.go

@@ -6,6 +6,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/encoder"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/peers"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
@@ -51,7 +52,7 @@ type (
 		BroadcastBlob(ctx context.Context, subnet uint64, blob *ethpb.BlobSidecar) error
 		BroadcastLightClientOptimisticUpdate(ctx context.Context, update interfaces.LightClientOptimisticUpdate) error
 		BroadcastLightClientFinalityUpdate(ctx context.Context, update interfaces.LightClientFinalityUpdate) error
-		BroadcastDataColumnSidecar(root [fieldparams.RootLength]byte, columnSubnet uint64, dataColumnSidecar *ethpb.DataColumnSidecar) error
+		BroadcastDataColumnSidecar(columnSubnet uint64, dataColumnSidecar blocks.VerifiedRODataColumn) error
 	}
 
 	// SetStreamHandler configures p2p to handle streams of a certain topic ID.

beacon-chain/p2p/options.go

@@ -13,6 +13,7 @@ import (
 	mplex "github.com/libp2p/go-libp2p-mplex"
 	"github.com/libp2p/go-libp2p/core/network"
 	"github.com/libp2p/go-libp2p/core/peer"
+	"github.com/libp2p/go-libp2p/p2p/net/connmgr"
 	"github.com/libp2p/go-libp2p/p2p/security/noise"
 	libp2pquic "github.com/libp2p/go-libp2p/p2p/transport/quic"
 	libp2ptcp "github.com/libp2p/go-libp2p/p2p/transport/tcp"
@@ -58,6 +59,22 @@ func MultiAddressBuilder(ip net.IP, tcpPort, quicPort uint) ([]ma.Multiaddr, err
 	return multiaddrs, nil
 }
 
+// setConnManagerOption sets the connection manager option for libp2p based on the
+// MaxPeers setting in the p2p config. If MaxPeers is set to a value higher than the
+// default high water mark, we create a new connection manager with a high water mark
+// that is higher than MaxPeers. Otherwise, we do not set a connection manager option
+// and allow the libp2p fallback defaults to be applied. Rationale below:
+// see: https://github.com/OffchainLabs/prysm/issues/15607
+func setConnManagerOption(cfg *Config, opts []libp2p.Option) ([]libp2p.Option, error) {
+	low, high := cfg.connManagerLowHigh()
+	cm, err := connmgr.NewConnManager(low, high)
+	if err != nil {
+		return nil, errors.Wrap(err, "new ConnManager")
+	}
+	opts = append(opts, libp2p.ConnectionManager(cm))
+	return opts, nil
+}
+
 // buildOptions for the libp2p host.
 func (s *Service) buildOptions(ip net.IP, priKey *ecdsa.PrivateKey) ([]libp2p.Option, error) {
 	cfg := s.cfg
@@ -84,7 +101,6 @@ func (s *Service) buildOptions(ip net.IP, priKey *ecdsa.PrivateKey) ([]libp2p.Op
 	if err != nil {
 		return nil, errors.Wrapf(err, "cannot get ID from public key: %s", ifaceKey.GetPublic().Type().String())
 	}
-
 	log.Infof("Running node with peer id of %s ", id.String())
 
 	options := []libp2p.Option{
@@ -98,6 +114,10 @@ func (s *Service) buildOptions(ip net.IP, priKey *ecdsa.PrivateKey) ([]libp2p.Op
 		libp2p.Security(noise.ID, noise.New),
 		libp2p.Ping(false), // Disable Ping Service.
 	}
+	options, err = setConnManagerOption(s.cfg, options)
+	if err != nil {
+		return nil, errors.Wrap(err, "set connection manager option")
+	}
 
 	if features.Get().EnableQUIC {
 		options = append(options, libp2p.Transport(libp2pquic.NewTransport))

beacon-chain/p2p/options_test.go

@@ -18,6 +18,7 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/p2p/enr"
 	"github.com/libp2p/go-libp2p"
+	"github.com/libp2p/go-libp2p/core/connmgr"
 	"github.com/libp2p/go-libp2p/core/crypto"
 	"github.com/libp2p/go-libp2p/core/peer"
 	"github.com/libp2p/go-libp2p/core/protocol"
@@ -134,6 +135,59 @@ func TestDefaultMultiplexers(t *testing.T) {
 	assert.Equal(t, protocol.ID("/mplex/6.7.0"), cfg.Muxers[1].ID)
 }
 
+func TestSetConnManagerOption(t *testing.T) {
+	cases := []struct {
+		name      string
+		maxPeers  uint
+		highWater int
+	}{
+		{
+			name:      "MaxPeers lower than default high water mark",
+			maxPeers:  defaultConnManagerPruneAbove - 1,
+			highWater: defaultConnManagerPruneAbove,
+		},
+		{
+			name:      "MaxPeers equal to default high water mark",
+			maxPeers:  defaultConnManagerPruneAbove,
+			highWater: defaultConnManagerPruneAbove,
+		},
+		{
+			name:      "MaxPeers higher than default high water mark",
+			maxPeers:  defaultConnManagerPruneAbove + 1,
+			highWater: defaultConnManagerPruneAbove + 1 + connManagerPruneAmount,
+		},
+	}
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := &Config{MaxPeers: tt.maxPeers}
+			opts, err := setConnManagerOption(cfg, []libp2p.Option{})
+			assert.NoError(t, err)
+			_, high := cfg.connManagerLowHigh()
+			require.Equal(t, true, high > int(cfg.MaxPeers))
+
+			var libCfg libp2p.Config
+			require.NoError(t, libCfg.Apply(append(opts, libp2p.FallbackDefaults)...))
+			checkLimit(t, libCfg.ConnManager, high)
+		})
+	}
+}
+
+type connLimitGetter int
+
+func (m connLimitGetter) GetConnLimit() int {
+	return int(m)
+}
+
+// CheckLimit will return an error if the result of calling lg.GetConnLimit is greater than
+// the high water mark. So by checking the result of calling it with a value equal to and lower
+// than the expected value, we can determine the value it holds internally.
+func checkLimit(t *testing.T, cm connmgr.ConnManager, expected int) {
+	require.NoError(t, cm.CheckLimit(connLimitGetter(expected)), "Connection manager limit check failed")
+	if err := cm.CheckLimit(connLimitGetter(expected - 1)); err == nil {
+		t.Errorf("connection manager limit is below the expected value of %d", expected)
+	}
+}
+
 func TestMultiAddressBuilderWithID(t *testing.T) {
 	testCases := []struct {
 		name     string

beacon-chain/p2p/peers/status.go

@@ -25,6 +25,7 @@ package peers
 import (
 	"context"
 	"math"
+	"net"
 	"sort"
 	"strings"
 	"time"
@@ -87,11 +88,12 @@ const (
 
 // Status is the structure holding the peer status information.
 type Status struct {
-	ctx       context.Context
-	scorers   *scorers.Service
-	store     *peerdata.Store
-	ipTracker map[string]uint64
-	rand      *rand.Rand
+	ctx                   context.Context
+	scorers               *scorers.Service
+	store                 *peerdata.Store
+	ipTracker             map[string]uint64
+	rand                  *rand.Rand
+	ipColocationWhitelist []*net.IPNet
 }
 
 // StatusConfig represents peer status service params.
@@ -100,6 +102,8 @@ type StatusConfig struct {
 	PeerLimit int
 	// ScorerParams holds peer scorer configuration params.
 	ScorerParams *scorers.Config
+	// IPColocationWhitelist contains CIDR ranges that are exempt from IP colocation limits.
+	IPColocationWhitelist []*net.IPNet
 }
 
 // NewStatus creates a new status entity.
@@ -107,11 +111,13 @@ func NewStatus(ctx context.Context, config *StatusConfig) *Status {
 	store := peerdata.NewStore(ctx, &peerdata.StoreConfig{
 		MaxPeers: maxLimitBuffer + config.PeerLimit,
 	})
+
 	return &Status{
-		ctx:       ctx,
-		store:     store,
-		scorers:   scorers.NewService(ctx, store, config.ScorerParams),
-		ipTracker: map[string]uint64{},
+		ctx:                   ctx,
+		store:                 store,
+		scorers:               scorers.NewService(ctx, store, config.ScorerParams),
+		ipTracker:             map[string]uint64{},
+		ipColocationWhitelist: config.IPColocationWhitelist,
 		// Random generator used to calculate dial backoff period.
 		// It is ok to use deterministic generator, no need for true entropy.
 		rand: rand.NewDeterministicGenerator(),
@@ -1046,6 +1052,13 @@ func (p *Status) isfromBadIP(pid peer.ID) error {
 
 	if val, ok := p.ipTracker[ip.String()]; ok {
 		if val > CollocationLimit {
+			// Check if IP is in the whitelist
+			for _, ipNet := range p.ipColocationWhitelist {
+				if ipNet.Contains(ip) {
+					// IP is whitelisted, skip colocation limit check
+					return nil
+				}
+			}
 			return errors.Errorf(
 				"colocation limit exceeded: got %d - limit %d for peer %v with IP %v",
 				val, CollocationLimit, pid, ip.String(),

beacon-chain/p2p/pubsub.go

@@ -145,7 +145,7 @@ func (s *Service) pubsubOptions() []pubsub.Option {
 		pubsub.WithPeerOutboundQueueSize(int(s.cfg.QueueSize)),
 		pubsub.WithMaxMessageSize(int(MaxMessageSize())), // lint:ignore uintcast -- Max Message Size is a config value and is naturally bounded by networking limitations.
 		pubsub.WithValidateQueueSize(int(s.cfg.QueueSize)),
-		pubsub.WithPeerScore(peerScoringParams()),
+		pubsub.WithPeerScore(peerScoringParams(s.cfg.IPColocationWhitelist)),
 		pubsub.WithPeerScoreInspect(s.peerInspector, time.Minute),
 		pubsub.WithGossipSubParams(pubsubGossipParam()),
 		pubsub.WithRawTracer(gossipTracer{host: s.host}),

beacon-chain/p2p/service.go

@@ -178,7 +178,8 @@ func NewService(ctx context.Context, cfg *Config) (*Service, error) {
 	s.pubsub = gs
 
 	s.peers = peers.NewStatus(ctx, &peers.StatusConfig{
-		PeerLimit: int(s.cfg.MaxPeers),
+		PeerLimit:             int(s.cfg.MaxPeers),
+		IPColocationWhitelist: s.cfg.IPColocationWhitelist,
 		ScorerParams: &scorers.Config{
 			BadResponsesScorerConfig: &scorers.BadResponsesScorerConfig{
 				Threshold:     maxBadResponses,

beacon-chain/p2p/testing/BUILD.bazel

@@ -25,6 +25,7 @@ go_library(
         "//beacon-chain/p2p/peers/scorers:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
+        "//consensus-types/blocks:go_default_library",
         "//consensus-types/interfaces:go_default_library",
         "//consensus-types/primitives:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",

beacon-chain/p2p/testing/fuzz_p2p.go

@@ -6,6 +6,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/encoder"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/peers"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
@@ -168,7 +169,7 @@ func (*FakeP2P) BroadcastLightClientFinalityUpdate(_ context.Context, _ interfac
 }
 
 // BroadcastDataColumnSidecar -- fake.
-func (*FakeP2P) BroadcastDataColumnSidecar(_ [fieldparams.RootLength]byte, _ uint64, _ *ethpb.DataColumnSidecar) error {
+func (*FakeP2P) BroadcastDataColumnSidecar(_ uint64, _ blocks.VerifiedRODataColumn) error {
 	return nil
 }
 

beacon-chain/p2p/testing/mock_broadcaster.go

@@ -5,7 +5,7 @@ import (
 	"sync"
 	"sync/atomic"
 
-	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"google.golang.org/protobuf/proto"
@@ -63,7 +63,7 @@ func (m *MockBroadcaster) BroadcastLightClientFinalityUpdate(_ context.Context,
 }
 
 // BroadcastDataColumnSidecar broadcasts a data column for mock.
-func (m *MockBroadcaster) BroadcastDataColumnSidecar([fieldparams.RootLength]byte, uint64, *ethpb.DataColumnSidecar) error {
+func (m *MockBroadcaster) BroadcastDataColumnSidecar(uint64, blocks.VerifiedRODataColumn) error {
 	m.BroadcastCalled.Store(true)
 	return nil
 }

beacon-chain/p2p/testing/p2p.go

@@ -17,6 +17,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/peers/scorers"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
@@ -232,7 +233,7 @@ func (p *TestP2P) BroadcastLightClientFinalityUpdate(_ context.Context, _ interf
 }
 
 // BroadcastDataColumnSidecar broadcasts a data column for mock.
-func (p *TestP2P) BroadcastDataColumnSidecar([fieldparams.RootLength]byte, uint64, *ethpb.DataColumnSidecar) error {
+func (p *TestP2P) BroadcastDataColumnSidecar(uint64, blocks.VerifiedRODataColumn) error {
 	p.BroadcastCalled.Store(true)
 	return nil
 }
@@ -498,8 +499,39 @@ func (s *TestP2P) UpdateCustodyInfo(earliestAvailableSlot primitives.Slot, custo
 	return s.earliestAvailableSlot, s.custodyGroupCount, nil
 }
 
-// CustodyGroupCountFromPeer .
+// CustodyGroupCountFromPeer retrieves custody group count from a peer.
+// It first tries to get the custody group count from the peer's metadata,
+// then falls back to the ENR value if the metadata is not available, then
+// falls back to the minimum number of custody groups an honest node should custodiy
+// and serve samples from if ENR is not available.
 func (s *TestP2P) CustodyGroupCountFromPeer(pid peer.ID) uint64 {
+	// Try to get the custody group count from the peer's metadata.
+	metadata, err := s.peers.Metadata(pid)
+	if err != nil {
+		// On error, default to the ENR value.
+		return s.custodyGroupCountFromPeerENR(pid)
+	}
+
+	// If the metadata is nil, default to the ENR value.
+	if metadata == nil {
+		return s.custodyGroupCountFromPeerENR(pid)
+	}
+
+	// Get the custody subnets count from the metadata.
+	custodyCount := metadata.CustodyGroupCount()
+
+	// If the custody count is null, default to the ENR value.
+	if custodyCount == 0 {
+		return s.custodyGroupCountFromPeerENR(pid)
+	}
+
+	return custodyCount
+}
+
+// custodyGroupCountFromPeerENR retrieves the custody count from the peer's ENR.
+// If the ENR is not available, it defaults to the minimum number of custody groups
+// an honest node custodies and serves samples from.
+func (s *TestP2P) custodyGroupCountFromPeerENR(pid peer.ID) uint64 {
 	// By default, we assume the peer custodies the minimum number of groups.
 	custodyRequirement := params.BeaconConfig().CustodyRequirement
 
@@ -509,7 +541,7 @@ func (s *TestP2P) CustodyGroupCountFromPeer(pid peer.ID) uint64 {
 		return custodyRequirement
 	}
 
-	// Retrieve the custody subnets count from the ENR.
+	// Retrieve the custody group count from the ENR.
 	custodyGroupCount, err := peerdas.CustodyGroupCountFromRecord(record)
 	if err != nil {
 		return custodyRequirement

beacon-chain/rpc/BUILD.bazel

@@ -20,10 +20,10 @@ go_library(
         "//beacon-chain/core/feed/block:go_default_library",
         "//beacon-chain/core/feed/operation:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",
-        "//beacon-chain/core/light-client:go_default_library",
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/filesystem:go_default_library",
         "//beacon-chain/execution:go_default_library",
+        "//beacon-chain/light-client:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/blstoexec:go_default_library",
         "//beacon-chain/operations/slashings:go_default_library",

beacon-chain/rpc/endpoints.go

@@ -102,7 +102,7 @@ func (s *Service) endpoints(
 	endpoints = append(endpoints, s.prysmValidatorEndpoints(stater, coreService)...)
 
 	if features.Get().EnableLightClient {
-		endpoints = append(endpoints, s.lightClientEndpoints(blocker, stater)...)
+		endpoints = append(endpoints, s.lightClientEndpoints()...)
 	}
 
 	if enableDebug {
@@ -194,6 +194,8 @@ func (s *Service) blobEndpoints(blocker lookup.Blocker) []endpoint {
 	const namespace = "blob"
 	return []endpoint{
 		{
+			// Deprecated: /eth/v1/beacon/blob_sidecars/{block_id} in favor of /eth/v1/beacon/blobs/{block_id}
+			// the endpoint will continue to work post fulu for some time however
 			template: "/eth/v1/beacon/blob_sidecars/{block_id}",
 			name:     namespace + ".Blobs",
 			middleware: []middleware.Middleware{
@@ -203,6 +205,16 @@ func (s *Service) blobEndpoints(blocker lookup.Blocker) []endpoint {
 			handler: server.Blobs,
 			methods: []string{http.MethodGet},
 		},
+		{
+			template: "/eth/v1/beacon/blobs/{block_id}",
+			name:     namespace + ".GetBlobs",
+			middleware: []middleware.Middleware{
+				middleware.AcceptHeaderHandler([]string{api.JsonMediaType, api.OctetStreamMediaType}),
+				middleware.AcceptEncodingHeaderHandler(),
+			},
+			handler: server.GetBlobs,
+			methods: []string{http.MethodGet},
+		},
 	}
 }
 
@@ -1034,9 +1046,10 @@ func (*Service) configEndpoints() []endpoint {
 	}
 }
 
-func (s *Service) lightClientEndpoints(blocker lookup.Blocker, stater lookup.Stater) []endpoint {
+func (s *Service) lightClientEndpoints() []endpoint {
 	server := &lightclient.Server{
-		LCStore: s.cfg.LCStore,
+		LCStore:     s.cfg.LCStore,
+		HeadFetcher: s.cfg.HeadFetcher,
 	}
 
 	const namespace = "lightclient"

beacon-chain/rpc/endpoints_test.go

@@ -70,6 +70,7 @@ func Test_endpoints(t *testing.T) {
 
 	blobRoutes := map[string][]string{
 		"/eth/v1/beacon/blob_sidecars/{block_id}": {http.MethodGet},
+		"/eth/v1/beacon/blobs/{block_id}":         {http.MethodGet},
 	}
 
 	configRoutes := map[string][]string{

beacon-chain/rpc/eth/blob/BUILD.bazel

@@ -13,7 +13,9 @@ go_library(
         "//api/server/structs:go_default_library",
         "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/rpc/core:go_default_library",
+        "//beacon-chain/rpc/eth/shared:go_default_library",
         "//beacon-chain/rpc/lookup:go_default_library",
+        "//beacon-chain/rpc/options:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",
@@ -33,6 +35,7 @@ go_test(
     deps = [
         "//api:go_default_library",
         "//api/server/structs:go_default_library",
+        "//beacon-chain/blockchain/kzg:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/db/filesystem:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
@@ -41,6 +44,7 @@ go_test(
         "//beacon-chain/verification:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
+        "//consensus-types/primitives:go_default_library",
         "//network/httputil:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
         "//runtime/version:go_default_library",

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

@@ -10,7 +10,9 @@ import (
 	"github.com/OffchainLabs/prysm/v6/api"
 	"github.com/OffchainLabs/prysm/v6/api/server/structs"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/core"
-	field_params "github.com/OffchainLabs/prysm/v6/config/fieldparams"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/eth/shared"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/options"
+	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
@@ -22,6 +24,8 @@ import (
 )
 
 // Blobs is an HTTP handler for Beacon API getBlobs.
+// Deprecated: /eth/v1/beacon/blob_sidecars/{block_id} in favor of /eth/v1/beacon/blobs/{block_id}
+// the endpoint will continue to work post fulu for some time however
 func (s *Server) Blobs(w http.ResponseWriter, r *http.Request) {
 	ctx, span := trace.StartSpan(r.Context(), "beacon.Blobs")
 	defer span.End()
@@ -34,7 +38,7 @@ func (s *Server) Blobs(w http.ResponseWriter, r *http.Request) {
 	segments := strings.Split(r.URL.Path, "/")
 	blockId := segments[len(segments)-1]
 
-	verifiedBlobs, rpcErr := s.Blocker.Blobs(ctx, blockId, indices)
+	verifiedBlobs, rpcErr := s.Blocker.Blobs(ctx, blockId, options.WithIndices(indices))
 	if rpcErr != nil {
 		code := core.ErrorReasonToHTTP(rpcErr.Reason)
 		switch code {
@@ -127,6 +131,94 @@ loop:
 	return indices, nil
 }
 
+// GetBlobs retrieves blobs for a given block id. ( this is the new handler that replaces func (s *Server) Blobs )
+func (s *Server) GetBlobs(w http.ResponseWriter, r *http.Request) {
+	ctx, span := trace.StartSpan(r.Context(), "beacon.GetBlobs")
+	defer span.End()
+
+	segments := strings.Split(r.URL.Path, "/")
+	blockId := segments[len(segments)-1]
+
+	var verifiedBlobs []*blocks.VerifiedROBlob
+	var rpcErr *core.RpcError
+
+	// Check if versioned_hashes parameter is provided
+	versionedHashesStr := r.URL.Query()["versioned_hashes"]
+	versionedHashes := make([][]byte, len(versionedHashesStr))
+	if len(versionedHashesStr) > 0 {
+		for i, hashStr := range versionedHashesStr {
+			hash, ok := shared.ValidateHex(w, fmt.Sprintf("versioned_hashes[%d]", i), hashStr, 32)
+			if !ok {
+				return
+			}
+			versionedHashes[i] = hash
+		}
+	}
+	verifiedBlobs, rpcErr = s.Blocker.Blobs(ctx, blockId, options.WithVersionedHashes(versionedHashes))
+	if rpcErr != nil {
+		code := core.ErrorReasonToHTTP(rpcErr.Reason)
+		switch code {
+		case http.StatusBadRequest:
+			httputil.HandleError(w, "Bad Request: "+rpcErr.Err.Error(), code)
+			return
+		case http.StatusNotFound:
+			httputil.HandleError(w, "Not found: "+rpcErr.Err.Error(), code)
+			return
+		case http.StatusInternalServerError:
+			httputil.HandleError(w, "Internal server error: "+rpcErr.Err.Error(), code)
+			return
+		default:
+			httputil.HandleError(w, rpcErr.Err.Error(), code)
+			return
+		}
+	}
+
+	blk, err := s.Blocker.Block(ctx, []byte(blockId))
+	if err != nil {
+		httputil.HandleError(w, "Could not fetch block: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+	if blk == nil {
+		httputil.HandleError(w, "Block not found", http.StatusNotFound)
+		return
+	}
+
+	if httputil.RespondWithSsz(r) {
+		sszLen := fieldparams.BlobSize
+		sszData := make([]byte, len(verifiedBlobs)*sszLen)
+		for i := range verifiedBlobs {
+			copy(sszData[i*sszLen:(i+1)*sszLen], verifiedBlobs[i].Blob)
+		}
+
+		w.Header().Set(api.VersionHeader, version.String(blk.Version()))
+		httputil.WriteSsz(w, sszData)
+		return
+	}
+
+	blkRoot, err := blk.Block().HashTreeRoot()
+	if err != nil {
+		httputil.HandleError(w, "Could not hash block: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+	isOptimistic, err := s.OptimisticModeFetcher.IsOptimisticForRoot(ctx, blkRoot)
+	if err != nil {
+		httputil.HandleError(w, "Could not check if block is optimistic: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	data := make([]string, len(verifiedBlobs))
+	for i, v := range verifiedBlobs {
+		data[i] = hexutil.Encode(v.Blob)
+	}
+	resp := &structs.GetBlobsResponse{
+		Data:                data,
+		ExecutionOptimistic: isOptimistic,
+		Finalized:           s.FinalizationFetcher.IsFinalized(ctx, blkRoot),
+	}
+	w.Header().Set(api.VersionHeader, version.String(blk.Version()))
+	httputil.WriteJson(w, resp)
+}
+
 func buildSidecarsJsonResponse(verifiedBlobs []*blocks.VerifiedROBlob) []*structs.Sidecar {
 	sidecars := make([]*structs.Sidecar, len(verifiedBlobs))
 	for i, sc := range verifiedBlobs {
@@ -147,13 +239,13 @@ func buildSidecarsJsonResponse(verifiedBlobs []*blocks.VerifiedROBlob) []*struct
 }
 
 func buildSidecarsSSZResponse(verifiedBlobs []*blocks.VerifiedROBlob) ([]byte, error) {
-	ssz := make([]byte, field_params.BlobSidecarSize*len(verifiedBlobs))
+	ssz := make([]byte, fieldparams.BlobSidecarSize*len(verifiedBlobs))
 	for i, sidecar := range verifiedBlobs {
 		sszrep, err := sidecar.MarshalSSZ()
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to marshal sidecar ssz")
 		}
-		copy(ssz[i*field_params.BlobSidecarSize:(i+1)*field_params.BlobSidecarSize], sszrep)
+		copy(ssz[i*fieldparams.BlobSidecarSize:(i+1)*fieldparams.BlobSidecarSize], sszrep)
 	}
 	return ssz, nil
 }

beacon-chain/rpc/eth/blob/handlers_test.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/OffchainLabs/prysm/v6/api"
 	"github.com/OffchainLabs/prysm/v6/api/server/structs"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
 	mockChain "github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	testDB "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
@@ -22,6 +23,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	"github.com/OffchainLabs/prysm/v6/network/httputil"
 	eth "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v6/runtime/version"
@@ -278,7 +280,7 @@ func TestBlobs(t *testing.T) {
 		assert.Equal(t, http.StatusBadRequest, e.Code)
 		assert.Equal(t, true, strings.Contains(e.Message, fmt.Sprintf("requested blob indices [%d] are invalid", overLimit)))
 	})
-	t.Run("outside retention period returns 200 w/ empty list ", func(t *testing.T) {
+	t.Run("outside retention period returns 200 with what we have", func(t *testing.T) {
 		u := "http://foo.example/123"
 		request := httptest.NewRequest("GET", u, nil)
 		writer := httptest.NewRecorder()
@@ -296,7 +298,7 @@ func TestBlobs(t *testing.T) {
 		assert.Equal(t, http.StatusOK, writer.Code)
 		resp := &structs.SidecarsResponse{}
 		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
-		require.Equal(t, 0, len(resp.Data))
+		require.Equal(t, 4, len(resp.Data))
 
 		require.Equal(t, "deneb", resp.Version)
 		require.Equal(t, false, resp.ExecutionOptimistic)
@@ -558,7 +560,573 @@ func Test_parseIndices(t *testing.T) {
 	}
 }
 
+func TestGetBlobs(t *testing.T) {
+	// Start the trusted setup for KZG operations (needed for data columns)
+	require.NoError(t, kzg.Start())
+
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig().Copy()
+	cfg.DenebForkEpoch = 1
+	cfg.ElectraForkEpoch = 10
+	cfg.FuluForkEpoch = 20
+	cfg.BlobSchedule = []params.BlobScheduleEntry{
+		{Epoch: 0, MaxBlobsPerBlock: 0},
+		{Epoch: 1, MaxBlobsPerBlock: 6},   // Deneb
+		{Epoch: 10, MaxBlobsPerBlock: 9},  // Electra
+		{Epoch: 20, MaxBlobsPerBlock: 12}, // Fulu
+	}
+	params.OverrideBeaconConfig(cfg)
+
+	db := testDB.SetupDB(t)
+	denebBlock, blobs := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 123, 4)
+	require.NoError(t, db.SaveBlock(t.Context(), denebBlock))
+	bs := filesystem.NewEphemeralBlobStorage(t)
+	testSidecars := verification.FakeVerifySliceForTest(t, blobs)
+	for i := range testSidecars {
+		require.NoError(t, bs.Save(testSidecars[i]))
+	}
+	blockRoot := blobs[0].BlockRoot()
+
+	mockChainService := &mockChain.ChainService{
+		FinalizedRoots: map[[32]byte]bool{},
+		Genesis:        time.Now().Add(-time.Duration(uint64(params.BeaconConfig().SlotsPerEpoch)*uint64(params.BeaconConfig().DenebForkEpoch)*params.BeaconConfig().SecondsPerSlot) * time.Second),
+	}
+	s := &Server{
+		OptimisticModeFetcher: mockChainService,
+		FinalizationFetcher:   mockChainService,
+		TimeFetcher:           mockChainService,
+	}
+
+	t.Run("genesis", func(t *testing.T) {
+		u := "http://foo.example/genesis"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.Equal(t, http.StatusBadRequest, e.Code)
+		assert.StringContains(t, "blobs are not supported for Phase 0 fork", e.Message)
+	})
+	t.Run("head", func(t *testing.T) {
+		u := "http://foo.example/head"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{Root: blockRoot[:], Block: denebBlock},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 4, len(resp.Data))
+		blob := resp.Data[0]
+		require.NotNil(t, blob)
+		assert.Equal(t, hexutil.Encode(blobs[0].Blob), blob)
+		blob = resp.Data[1]
+		require.NotNil(t, blob)
+		assert.Equal(t, hexutil.Encode(blobs[1].Blob), blob)
+		blob = resp.Data[2]
+		require.NotNil(t, blob)
+		assert.Equal(t, hexutil.Encode(blobs[2].Blob), blob)
+		blob = resp.Data[3]
+		require.NotNil(t, blob)
+		assert.Equal(t, hexutil.Encode(blobs[3].Blob), blob)
+		require.Equal(t, false, resp.ExecutionOptimistic)
+		require.Equal(t, false, resp.Finalized)
+	})
+	t.Run("finalized", func(t *testing.T) {
+		u := "http://foo.example/finalized"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}, Block: denebBlock},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 4, len(resp.Data))
+
+		require.Equal(t, false, resp.ExecutionOptimistic)
+		require.Equal(t, false, resp.Finalized)
+	})
+	t.Run("root", func(t *testing.T) {
+		u := "http://foo.example/" + hexutil.Encode(blockRoot[:])
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{Block: denebBlock},
+			BeaconDB:         db,
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 4, len(resp.Data))
+
+		require.Equal(t, false, resp.ExecutionOptimistic)
+		require.Equal(t, false, resp.Finalized)
+	})
+	t.Run("slot", func(t *testing.T) {
+		u := "http://foo.example/123"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{Block: denebBlock},
+			BeaconDB:         db,
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 4, len(resp.Data))
+
+		require.Equal(t, false, resp.ExecutionOptimistic)
+		require.Equal(t, false, resp.Finalized)
+	})
+	t.Run("slot not found", func(t *testing.T) {
+		u := "http://foo.example/122"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{Block: denebBlock},
+			BeaconDB:         db,
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusNotFound, writer.Code)
+	})
+	t.Run("no blobs returns an empty array", func(t *testing.T) {
+		u := "http://foo.example/123"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}, Block: denebBlock},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: filesystem.NewEphemeralBlobStorage(t), // new ephemeral storage
+		}
+
+		s.GetBlobs(writer, request)
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, len(resp.Data), 0)
+
+		require.Equal(t, false, resp.ExecutionOptimistic)
+		require.Equal(t, false, resp.Finalized)
+	})
+	t.Run("outside retention period still returns 200 what we have in db ", func(t *testing.T) {
+		u := "http://foo.example/123"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		moc := &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}, Block: denebBlock}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher:   moc,
+			GenesisTimeFetcher: moc, // genesis time is set to 0 here, so it results in current epoch being extremely large
+			BeaconDB:           db,
+			BlobStorage:        bs,
+		}
+
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 4, len(resp.Data))
+
+		require.Equal(t, false, resp.ExecutionOptimistic)
+		require.Equal(t, false, resp.Finalized)
+	})
+	t.Run("block without commitments returns 200 w/empty list ", func(t *testing.T) {
+		denebBlock, _ := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 333, 0)
+		commitments, err := denebBlock.Block().Body().BlobKzgCommitments()
+		require.NoError(t, err)
+		require.Equal(t, len(commitments), 0)
+		require.NoError(t, db.SaveBlock(t.Context(), denebBlock))
+
+		u := "http://foo.example/333"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}, Block: denebBlock},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 0, len(resp.Data))
+
+		require.Equal(t, false, resp.ExecutionOptimistic)
+		require.Equal(t, false, resp.Finalized)
+	})
+	t.Run("slot before Deneb fork", func(t *testing.T) {
+		u := "http://foo.example/31"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{}
+
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.Equal(t, http.StatusBadRequest, e.Code)
+		assert.StringContains(t, "blobs are not supported before Deneb fork", e.Message)
+	})
+	t.Run("malformed block ID", func(t *testing.T) {
+		u := "http://foo.example/foo"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.Equal(t, http.StatusBadRequest, e.Code)
+		assert.Equal(t, true, strings.Contains(e.Message, "could not parse block ID"))
+	})
+	t.Run("ssz", func(t *testing.T) {
+		u := "http://foo.example/finalized"
+		request := httptest.NewRequest("GET", u, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+		assert.Equal(t, version.String(version.Deneb), writer.Header().Get(api.VersionHeader))
+		assert.Equal(t, http.StatusOK, writer.Code)
+		require.Equal(t, fieldparams.BlobSize*4, len(writer.Body.Bytes())) // size of 4 sidecars
+		// unmarshal all 4 blobs
+		blbs := unmarshalBlobs(t, writer.Body.Bytes())
+		require.Equal(t, 4, len(blbs))
+	})
+	t.Run("ssz multiple blobs", func(t *testing.T) {
+		u := "http://foo.example/finalized"
+		request := httptest.NewRequest("GET", u, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		blbs := unmarshalBlobs(t, writer.Body.Bytes())
+		require.Equal(t, 4, len(blbs))
+	})
+
+	t.Run("versioned_hashes invalid hex", func(t *testing.T) {
+		u := "http://foo.example/finalized?versioned_hashes=invalidhex,invalid2hex"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.Equal(t, http.StatusBadRequest, e.Code)
+		assert.StringContains(t, "versioned_hashes[0] is invalid", e.Message)
+		assert.StringContains(t, "hex string without 0x prefix", e.Message)
+	})
+
+	t.Run("versioned_hashes invalid length", func(t *testing.T) {
+		// Using 16 bytes instead of 32
+		shortHash := "0x1234567890abcdef1234567890abcdef"
+		u := fmt.Sprintf("http://foo.example/finalized?versioned_hashes=%s", shortHash)
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.Equal(t, http.StatusBadRequest, e.Code)
+		assert.StringContains(t, "Invalid versioned_hashes[0]:", e.Message)
+		assert.StringContains(t, "is not length 32", e.Message)
+	})
+
+	t.Run("versioned_hashes valid single hash", func(t *testing.T) {
+		// Get the first blob's commitment and convert to versioned hash
+		versionedHash := primitives.ConvertKzgCommitmentToVersionedHash(blobs[0].KzgCommitment)
+
+		u := fmt.Sprintf("http://foo.example/finalized?versioned_hashes=%s", hexutil.Encode(versionedHash[:]))
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 1, len(resp.Data)) // Should return only the requested blob
+		blob := resp.Data[0]
+		require.NotNil(t, blob)
+		assert.Equal(t, hexutil.Encode(blobs[0].Blob), blob)
+	})
+
+	t.Run("versioned_hashes multiple hashes", func(t *testing.T) {
+		// Get commitments for blobs 1 and 3 and convert to versioned hashes
+		versionedHash1 := primitives.ConvertKzgCommitmentToVersionedHash(blobs[1].KzgCommitment)
+		versionedHash3 := primitives.ConvertKzgCommitmentToVersionedHash(blobs[3].KzgCommitment)
+
+		u := fmt.Sprintf("http://foo.example/finalized?versioned_hashes=%s&versioned_hashes=%s",
+			hexutil.Encode(versionedHash1[:]), hexutil.Encode(versionedHash3[:]))
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 2, len(resp.Data)) // Should return 2 requested blobs
+		// Verify blobs are returned in KZG commitment order from the block (1, 3)
+		// not in the requested order
+		assert.Equal(t, hexutil.Encode(blobs[1].Blob), resp.Data[0])
+		assert.Equal(t, hexutil.Encode(blobs[3].Blob), resp.Data[1])
+	})
+
+	// Test for Electra fork
+	t.Run("electra max blobs", func(t *testing.T) {
+		electraBlock, electraBlobs := util.GenerateTestElectraBlockWithSidecar(t, [32]byte{}, 323, maxBlobsPerBlockByVersion(version.Electra))
+		require.NoError(t, db.SaveBlock(t.Context(), electraBlock))
+		electraBs := filesystem.NewEphemeralBlobStorage(t)
+		electraSidecars := verification.FakeVerifySliceForTest(t, electraBlobs)
+		for i := range electraSidecars {
+			require.NoError(t, electraBs.Save(electraSidecars[i]))
+		}
+		electraBlockRoot := electraBlobs[0].BlockRoot()
+
+		u := "http://foo.example/323"
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: electraBlockRoot[:]}, Block: electraBlock},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: electraBs,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, version.String(version.Electra), writer.Header().Get(api.VersionHeader))
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, maxBlobsPerBlockByVersion(version.Electra), len(resp.Data))
+		blob := resp.Data[0]
+		require.NotNil(t, blob)
+		assert.Equal(t, hexutil.Encode(electraBlobs[0].Blob), blob)
+	})
+
+	// Test for Fulu fork with data columns
+	t.Run("fulu with data columns", func(t *testing.T) {
+		// Generate a Fulu block with data columns
+		fuluForkSlot := primitives.Slot(20 * params.BeaconConfig().SlotsPerEpoch) // Fulu is at epoch 20
+		fuluBlock, _, verifiedRoDataColumnSidecars := util.GenerateTestFuluBlockWithSidecars(t, 3, util.WithSlot(fuluForkSlot))
+		require.NoError(t, db.SaveBlock(t.Context(), fuluBlock.ReadOnlySignedBeaconBlock))
+		fuluBlockRoot := fuluBlock.Root()
+
+		// Store data columns
+		_, dataColumnStorage := filesystem.NewEphemeralDataColumnStorageAndFs(t)
+		require.NoError(t, dataColumnStorage.Save(verifiedRoDataColumnSidecars))
+
+		u := fmt.Sprintf("http://foo.example/%d", fuluForkSlot)
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		// Create an empty blob storage (won't be used but needs to be non-nil)
+		_, emptyBlobStorage := filesystem.NewEphemeralBlobStorageAndFs(t)
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: fuluBlockRoot[:]}, Block: fuluBlock.ReadOnlySignedBeaconBlock},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:          db,
+			BlobStorage:       emptyBlobStorage,
+			DataColumnStorage: dataColumnStorage,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, version.String(version.Fulu), writer.Header().Get(api.VersionHeader))
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 3, len(resp.Data))
+
+		// Verify that we got blobs back (they were reconstructed from data columns)
+		for i := range resp.Data {
+			require.NotNil(t, resp.Data[i])
+		}
+	})
+
+	// Test for Fulu with versioned hashes and data columns
+	t.Run("fulu versioned_hashes with data columns", func(t *testing.T) {
+		// Generate a Fulu block with data columns
+		fuluForkSlot2 := primitives.Slot(20*params.BeaconConfig().SlotsPerEpoch + 10) // Fulu is at epoch 20
+		fuluBlock2, _, verifiedRoDataColumnSidecars2 := util.GenerateTestFuluBlockWithSidecars(t, 4, util.WithSlot(fuluForkSlot2))
+		require.NoError(t, db.SaveBlock(t.Context(), fuluBlock2.ReadOnlySignedBeaconBlock))
+		fuluBlockRoot2 := fuluBlock2.Root()
+
+		// Store data columns
+		_, dataColumnStorage := filesystem.NewEphemeralDataColumnStorageAndFs(t)
+		require.NoError(t, dataColumnStorage.Save(verifiedRoDataColumnSidecars2))
+
+		// Get the commitments from the block to derive versioned hashes
+		commitments, err := fuluBlock2.Block().Body().BlobKzgCommitments()
+		require.NoError(t, err)
+		require.Equal(t, true, len(commitments) >= 3)
+
+		// Request specific blobs by versioned hashes in reverse order
+		// We request commitments[2] and commitments[0], but they should be returned
+		// in commitment order from the block (0, 2), not in the requested order
+		versionedHash1 := primitives.ConvertKzgCommitmentToVersionedHash(commitments[2])
+		versionedHash2 := primitives.ConvertKzgCommitmentToVersionedHash(commitments[0])
+
+		u := fmt.Sprintf("http://foo.example/%d?versioned_hashes=%s&versioned_hashes=%s", fuluForkSlot2,
+			hexutil.Encode(versionedHash1[:]),
+			hexutil.Encode(versionedHash2[:]))
+		request := httptest.NewRequest("GET", u, nil)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		// Create an empty blob storage (won't be used but needs to be non-nil)
+		_, emptyBlobStorage := filesystem.NewEphemeralBlobStorageAndFs(t)
+		s.Blocker = &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: fuluBlockRoot2[:]}, Block: fuluBlock2.ReadOnlySignedBeaconBlock},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:          db,
+			BlobStorage:       emptyBlobStorage,
+			DataColumnStorage: dataColumnStorage,
+		}
+		s.GetBlobs(writer, request)
+
+		assert.Equal(t, version.String(version.Fulu), writer.Header().Get(api.VersionHeader))
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetBlobsResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		require.Equal(t, 2, len(resp.Data))
+		// Blobs are returned in commitment order, regardless of request order
+	})
+}
+
+func unmarshalBlobs(t *testing.T, response []byte) [][]byte {
+	require.Equal(t, 0, len(response)%fieldparams.BlobSize)
+	if len(response) == fieldparams.BlobSize {
+		return [][]byte{response}
+	}
+	blobs := make([][]byte, len(response)/fieldparams.BlobSize)
+	for i := range blobs {
+		blobs[i] = response[i*fieldparams.BlobSize : (i+1)*fieldparams.BlobSize]
+	}
+	return blobs
+}
+
 func maxBlobsPerBlockByVersion(v int) int {
+	if v >= version.Fulu {
+		return params.BeaconConfig().DeprecatedMaxBlobsPerBlockFulu
+	}
 	if v >= version.Electra {
 		return params.BeaconConfig().DeprecatedMaxBlobsPerBlockElectra
 	}

beacon-chain/rpc/eth/light-client/BUILD.bazel

@@ -11,7 +11,8 @@ go_library(
     deps = [
         "//api:go_default_library",
         "//api/server/structs:go_default_library",
-        "//beacon-chain/core/light-client:go_default_library",
+        "//beacon-chain/blockchain:go_default_library",
+        "//beacon-chain/light-client:go_default_library",
         "//beacon-chain/rpc/eth/shared:go_default_library",
         "//config/params:go_default_library",
         "//encoding/bytesutil:go_default_library",
@@ -32,9 +33,11 @@ go_test(
     deps = [
         "//api/server/structs:go_default_library",
         "//async/event:go_default_library",
+        "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
-        "//beacon-chain/core/light-client:go_default_library",
+        "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
+        "//beacon-chain/light-client:go_default_library",
         "//beacon-chain/p2p/testing:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",

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

@@ -6,7 +6,7 @@ import (
 
 	"github.com/OffchainLabs/prysm/v6/api"
 	"github.com/OffchainLabs/prysm/v6/api/server/structs"
-	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
+	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/eth/shared"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/encoding/bytesutil"
@@ -90,10 +90,21 @@ func (s *Server) GetLightClientUpdatesByRange(w http.ResponseWriter, req *http.R
 		return
 	}
 
+	if startPeriod*uint64(config.EpochsPerSyncCommitteePeriod) < uint64(config.AltairForkEpoch) {
+		httputil.HandleError(w, "Invalid 'start_period': before Altair fork", http.StatusBadRequest)
+		return
+	}
+
 	endPeriod := startPeriod + count - 1
 
+	headBlock, err := s.HeadFetcher.HeadBlock(ctx)
+	if err != nil {
+		httputil.HandleError(w, "Could not get head block: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
 	// get updates
-	updates, err := s.LCStore.LightClientUpdates(ctx, startPeriod, endPeriod)
+	updates, err := s.LCStore.LightClientUpdates(ctx, startPeriod, endPeriod, headBlock)
 	if err != nil {
 		httputil.HandleError(w, "Could not get light client updates from DB: "+err.Error(), http.StatusInternalServerError)
 		return

beacon-chain/rpc/eth/light-client/handlers_test.go

@@ -2,6 +2,7 @@ package lightclient
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"math/rand"
@@ -12,9 +13,11 @@ import (
 
 	"github.com/OffchainLabs/prysm/v6/api/server/structs"
 	"github.com/OffchainLabs/prysm/v6/async/event"
+	blockchainTest "github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
-	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	dbtesting "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
+	lightclient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	p2ptesting "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
@@ -55,7 +58,8 @@ func TestLightClientHandler_GetLightClientBootstrap(t *testing.T) {
 			require.NoError(t, err)
 
 			db := dbtesting.SetupDB(t)
-			lcStore := lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed))
+			lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+			require.NoError(t, err)
 
 			err = db.SaveLightClientBootstrap(l.Ctx, blockRoot[:], bootstrap)
 			require.NoError(t, err)
@@ -99,7 +103,8 @@ func TestLightClientHandler_GetLightClientBootstrap(t *testing.T) {
 			require.NoError(t, err)
 
 			db := dbtesting.SetupDB(t)
-			lcStore := lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed))
+			lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+			require.NoError(t, err)
 
 			err = db.SaveLightClientBootstrap(l.Ctx, blockRoot[:], bootstrap)
 			require.NoError(t, err)
@@ -142,8 +147,9 @@ func TestLightClientHandler_GetLightClientBootstrap(t *testing.T) {
 	}
 
 	t.Run("no bootstrap found", func(t *testing.T) {
+		lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), dbtesting.SetupDB(t))
 		s := &Server{
-			LCStore: lightclient.NewLightClientStore(dbtesting.SetupDB(t), &p2ptesting.FakeP2P{}, new(event.Feed)),
+			LCStore: lcStore,
 		}
 		request := httptest.NewRequest("GET", "http://foo.com/", nil)
 		request.SetPathValue("block_root", hexutil.Encode([]byte{0x00, 0x01, 0x02}))
@@ -185,13 +191,24 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 					updates = append(updates, update)
 				}
 
+				lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+
+				blk := util.NewBeaconBlock()
+				signedBlk, err := blocks.NewSignedBeaconBlock(blk)
+				require.NoError(t, err)
+
 				s := &Server{
-					LCStore: lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed)),
+					LCStore: lcStore,
+					HeadFetcher: &blockchainTest.ChainService{
+						Block: signedBlk,
+					},
 				}
 
+				saveHead(t, ctx, db)
+
 				updatePeriod := startPeriod
 				for _, update := range updates {
-					err := s.LCStore.SaveLightClientUpdate(ctx, updatePeriod, update)
+					err := db.SaveLightClientUpdate(ctx, updatePeriod, update)
 					require.NoError(t, err)
 					updatePeriod++
 				}
@@ -326,20 +343,30 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 				secondForkSlot := primitives.Slot(params.BeaconConfig().VersionToForkEpochMap()[testVersion+1] * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 
 				db := dbtesting.SetupDB(t)
+				lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+
+				blk := util.NewBeaconBlock()
+				signedBlk, err := blocks.NewSignedBeaconBlock(blk)
+				require.NoError(t, err)
+
 				s := &Server{
-					LCStore: lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed)),
+					LCStore: lcStore,
+					HeadFetcher: &blockchainTest.ChainService{
+						Block: signedBlk,
+					},
 				}
 
+				saveHead(t, ctx, db)
+
 				updates := make([]interfaces.LightClientUpdate, 2)
 
 				updatePeriod := firstForkSlot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
 				startPeriod := updatePeriod
 
-				var err error
 				updates[0], err = createUpdate(t, testVersion)
 				require.NoError(t, err)
 
-				err = s.LCStore.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[0])
+				err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[0])
 				require.NoError(t, err)
 
 				updatePeriod = secondForkSlot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
@@ -347,7 +374,7 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 				updates[1], err = createUpdate(t, testVersion+1)
 				require.NoError(t, err)
 
-				err = s.LCStore.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[1])
+				err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[1])
 				require.NoError(t, err)
 
 				t.Run("json", func(t *testing.T) {
@@ -446,19 +473,30 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		slot := primitives.Slot(config.AltairForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 
 		db := dbtesting.SetupDB(t)
+		lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+
+		blk := util.NewBeaconBlock()
+		signedBlk, err := blocks.NewSignedBeaconBlock(blk)
+		require.NoError(t, err)
+
 		s := &Server{
-			LCStore: lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed)),
+			LCStore: lcStore,
+			HeadFetcher: &blockchainTest.ChainService{
+				Block: signedBlk,
+			},
 		}
 
+		saveHead(t, ctx, db)
+
 		updates := make([]interfaces.LightClientUpdate, 3)
 
 		updatePeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
-		var err error
+
 		for i := 0; i < 3; i++ {
 			updates[i], err = createUpdate(t, version.Altair)
 			require.NoError(t, err)
 
-			err = s.LCStore.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[i])
+			err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[i])
 			require.NoError(t, err)
 
 			updatePeriod++
@@ -493,20 +531,30 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		slot := primitives.Slot(config.AltairForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 
 		db := dbtesting.SetupDB(t)
+		lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+
+		blk := util.NewBeaconBlock()
+		signedBlk, err := blocks.NewSignedBeaconBlock(blk)
+		require.NoError(t, err)
+
 		s := &Server{
-			LCStore: lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed)),
+			LCStore: lcStore,
+			HeadFetcher: &blockchainTest.ChainService{
+				Block: signedBlk,
+			},
 		}
 
+		saveHead(t, ctx, db)
+
 		updates := make([]interfaces.LightClientUpdate, 3)
 
 		updatePeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
 
-		var err error
 		for i := 0; i < 3; i++ {
 			updates[i], err = createUpdate(t, version.Altair)
 			require.NoError(t, err)
 
-			err = s.LCStore.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[i])
+			err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[i])
 			require.NoError(t, err)
 
 			updatePeriod++
@@ -536,10 +584,16 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 	})
 
 	t.Run("start period before altair", func(t *testing.T) {
+		config.AltairForkEpoch = 1
+		params.OverrideBeaconConfig(config)
+
 		db := dbtesting.SetupDB(t)
+		lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+
 		s := &Server{
-			LCStore: lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed)),
+			LCStore: lcStore,
 		}
+
 		startPeriod := 0
 		url := fmt.Sprintf("http://foo.com/?count=128&start_period=%d", startPeriod)
 		request := httptest.NewRequest("GET", url, nil)
@@ -548,11 +602,10 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 
 		s.GetLightClientUpdatesByRange(writer, request)
 
-		require.Equal(t, http.StatusOK, writer.Code)
-		var resp structs.LightClientUpdatesByRangeResponse
-		err := json.Unmarshal(writer.Body.Bytes(), &resp.Updates)
-		require.NoError(t, err)
-		require.Equal(t, 0, len(resp.Updates))
+		require.Equal(t, http.StatusBadRequest, writer.Code)
+
+		config.AltairForkEpoch = 0
+		params.OverrideBeaconConfig(config)
 	})
 
 	t.Run("missing updates", func(t *testing.T) {
@@ -560,15 +613,25 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 
 		t.Run("missing update in the middle", func(t *testing.T) {
 			db := dbtesting.SetupDB(t)
+			lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+
+			blk := util.NewBeaconBlock()
+			signedBlk, err := blocks.NewSignedBeaconBlock(blk)
+			require.NoError(t, err)
+
 			s := &Server{
-				LCStore: lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed)),
+				LCStore: lcStore,
+				HeadFetcher: &blockchainTest.ChainService{
+					Block: signedBlk,
+				},
 			}
 
+			saveHead(t, ctx, db)
+
 			updates := make([]interfaces.LightClientUpdate, 3)
 
 			updatePeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
 
-			var err error
 			for i := 0; i < 3; i++ {
 				if i == 1 { // skip this update
 					updatePeriod++
@@ -577,7 +640,7 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 				updates[i], err = createUpdate(t, version.Altair)
 				require.NoError(t, err)
 
-				err = s.LCStore.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[i])
+				err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[i])
 				require.NoError(t, err)
 
 				updatePeriod++
@@ -604,15 +667,25 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 
 		t.Run("missing update at the beginning", func(t *testing.T) {
 			db := dbtesting.SetupDB(t)
+			lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), db)
+
+			blk := util.NewBeaconBlock()
+			signedBlk, err := blocks.NewSignedBeaconBlock(blk)
+			require.NoError(t, err)
+
 			s := &Server{
-				LCStore: lightclient.NewLightClientStore(db, &p2ptesting.FakeP2P{}, new(event.Feed)),
+				LCStore: lcStore,
+				HeadFetcher: &blockchainTest.ChainService{
+					Block: signedBlk,
+				},
 			}
 
+			saveHead(t, ctx, db)
+
 			updates := make([]interfaces.LightClientUpdate, 3)
 
 			updatePeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
 
-			var err error
 			for i := 0; i < 3; i++ {
 				if i == 0 { // skip this update
 					updatePeriod++
@@ -622,7 +695,7 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 				updates[i], err = createUpdate(t, version.Altair)
 				require.NoError(t, err)
 
-				err = s.LCStore.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[i])
+				err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[i])
 				require.NoError(t, err)
 
 				updatePeriod++
@@ -665,7 +738,12 @@ func TestLightClientHandler_GetLightClientFinalityUpdate(t *testing.T) {
 			update, err := lightclient.NewLightClientFinalityUpdateFromBeaconState(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
 			require.NoError(t, err)
 
-			s := &Server{LCStore: lightclient.NewLightClientStore(dbtesting.SetupDB(t), &p2ptesting.FakeP2P{}, new(event.Feed))}
+			lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), dbtesting.SetupDB(t))
+			require.NoError(t, err)
+
+			s := &Server{
+				LCStore: lcStore,
+			}
 			s.LCStore.SetLastFinalityUpdate(update, false)
 
 			request := httptest.NewRequest("GET", "http://foo.com", nil)
@@ -690,7 +768,12 @@ func TestLightClientHandler_GetLightClientFinalityUpdate(t *testing.T) {
 			update, err := lightclient.NewLightClientFinalityUpdateFromBeaconState(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
 			require.NoError(t, err)
 
-			s := &Server{LCStore: lightclient.NewLightClientStore(dbtesting.SetupDB(t), &p2ptesting.FakeP2P{}, new(event.Feed))}
+			lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), dbtesting.SetupDB(t))
+			require.NoError(t, err)
+
+			s := &Server{
+				LCStore: lcStore,
+			}
 			s.LCStore.SetLastFinalityUpdate(update, false)
 
 			request := httptest.NewRequest("GET", "http://foo.com", nil)
@@ -729,7 +812,11 @@ func TestLightClientHandler_GetLightClientOptimisticUpdate(t *testing.T) {
 	helpers.ClearCache()
 
 	t.Run("no update", func(t *testing.T) {
-		s := &Server{LCStore: lightclient.NewLightClientStore(dbtesting.SetupDB(t), &p2ptesting.FakeP2P{}, new(event.Feed))}
+		lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), dbtesting.SetupDB(t))
+
+		s := &Server{
+			LCStore: lcStore,
+		}
 
 		request := httptest.NewRequest("GET", "http://foo.com", nil)
 		writer := httptest.NewRecorder()
@@ -745,7 +832,12 @@ func TestLightClientHandler_GetLightClientOptimisticUpdate(t *testing.T) {
 			update, err := lightclient.NewLightClientOptimisticUpdateFromBeaconState(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock)
 			require.NoError(t, err)
 
-			s := &Server{LCStore: lightclient.NewLightClientStore(dbtesting.SetupDB(t), &p2ptesting.FakeP2P{}, new(event.Feed))}
+			lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), dbtesting.SetupDB(t))
+			require.NoError(t, err)
+
+			s := &Server{
+				LCStore: lcStore,
+			}
 			s.LCStore.SetLastOptimisticUpdate(update, false)
 
 			request := httptest.NewRequest("GET", "http://foo.com", nil)
@@ -769,7 +861,12 @@ func TestLightClientHandler_GetLightClientOptimisticUpdate(t *testing.T) {
 			update, err := lightclient.NewLightClientOptimisticUpdateFromBeaconState(ctx, l.State, l.Block, l.AttestedState, l.AttestedBlock)
 			require.NoError(t, err)
 
-			s := &Server{LCStore: lightclient.NewLightClientStore(dbtesting.SetupDB(t), &p2ptesting.FakeP2P{}, new(event.Feed))}
+			lcStore := lightclient.NewLightClientStore(&p2ptesting.FakeP2P{}, new(event.Feed), dbtesting.SetupDB(t))
+			require.NoError(t, err)
+
+			s := &Server{
+				LCStore: lcStore,
+			}
 			s.LCStore.SetLastOptimisticUpdate(update, false)
 
 			request := httptest.NewRequest("GET", "http://foo.com", nil)
@@ -984,3 +1081,14 @@ func createUpdate(t *testing.T, v int) (interfaces.LightClientUpdate, error) {
 
 	return update, nil
 }
+
+func saveHead(t *testing.T, ctx context.Context, d db.Database) {
+	blk := util.NewBeaconBlock()
+	blkRoot, err := blk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	util.SaveBlock(t, ctx, d, blk)
+	st, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, d.SaveState(ctx, st, blkRoot))
+	require.NoError(t, d.SaveHeadBlockRoot(ctx, blkRoot))
+}

beacon-chain/rpc/eth/light-client/server.go

@@ -1,9 +1,11 @@
 package lightclient
 
 import (
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 )
 
 type Server struct {
-	LCStore *lightClient.Store
+	LCStore     *lightClient.Store
+	HeadFetcher blockchain.HeadFetcher
 }

beacon-chain/rpc/lookup/BUILD.bazel

@@ -14,6 +14,7 @@ go_library(
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/filesystem:go_default_library",
         "//beacon-chain/rpc/core:go_default_library",
+        "//beacon-chain/rpc/options:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
         "//cmd/beacon-chain/flags:go_default_library",
@@ -44,6 +45,7 @@ go_test(
         "//beacon-chain/db/filesystem:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/rpc/core:go_default_library",
+        "//beacon-chain/rpc/options:go_default_library",
         "//beacon-chain/rpc/testutil:go_default_library",
         "//beacon-chain/state/state-native:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",

beacon-chain/rpc/lookup/blocker.go

@@ -11,6 +11,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/core"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/options"
 	"github.com/OffchainLabs/prysm/v6/cmd/beacon-chain/flags"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
@@ -57,7 +58,7 @@ func (e BlockIdParseError) Error() string {
 // Blocker is responsible for retrieving blocks.
 type Blocker interface {
 	Block(ctx context.Context, id []byte) (interfaces.ReadOnlySignedBeaconBlock, error)
-	Blobs(ctx context.Context, id string, indices []int) ([]*blocks.VerifiedROBlob, *core.RpcError)
+	Blobs(ctx context.Context, id string, opts ...options.BlobsOption) ([]*blocks.VerifiedROBlob, *core.RpcError)
 }
 
 // BeaconDbBlocker is an implementation of Blocker. It retrieves blocks from the beacon chain database.
@@ -147,7 +148,9 @@ func (p *BeaconDbBlocker) Block(ctx context.Context, id []byte) (interfaces.Read
 	return blk, nil
 }
 
-// Blobs returns the blobs for a given block id identifier and blob indices. The identifier can be one of:
+// Blobs returns the fetched blobs for a given block ID with configurable options.
+// Options can specify either blob indices or versioned hashes for retrieval.
+// The identifier can be one of:
 //   - "head" (canonical head in node's view)
 //   - "genesis"
 //   - "finalized"
@@ -158,11 +161,17 @@ func (p *BeaconDbBlocker) Block(ctx context.Context, id []byte) (interfaces.Read
 //
 // cases:
 //   - no block, 404
-//   - block exists, no commitment, 200 w/ empty list
 //   - block exists, has commitments, inside retention period (greater of protocol- or user-specified) serve then w/ 200 unless we hit an error reading them.
 //     we are technically not supposed to import a block to forkchoice unless we have the blobs, so the nuance here is if we can't find the file and we are inside the protocol-defined retention period, then it's actually a 500.
 //   - block exists, has commitments, outside retention period (greater of protocol- or user-specified) - ie just like block exists, no commitment
-func (p *BeaconDbBlocker) Blobs(ctx context.Context, id string, indices []int) ([]*blocks.VerifiedROBlob, *core.RpcError) {
+func (p *BeaconDbBlocker) Blobs(ctx context.Context, id string, opts ...options.BlobsOption) ([]*blocks.VerifiedROBlob, *core.RpcError) {
+	// Apply options
+	cfg := &options.BlobsConfig{}
+	for _, opt := range opts {
+		opt(cfg)
+	}
+
+	// Resolve block ID to root
 	var rootSlice []byte
 	switch id {
 	case "genesis":
@@ -239,11 +248,6 @@ func (p *BeaconDbBlocker) Blobs(ctx context.Context, id string, indices []int) (
 		return nil, &core.RpcError{Err: fmt.Errorf("block %#x not found in db", rootSlice), Reason: core.NotFound}
 	}
 
-	// If block is not in the retention window, return 200 w/ empty list
-	if !p.BlobStorage.WithinRetentionPeriod(slots.ToEpoch(roSignedBlock.Block().Slot()), slots.ToEpoch(p.GenesisTimeFetcher.CurrentSlot())) {
-		return make([]*blocks.VerifiedROBlob, 0), nil
-	}
-
 	roBlock := roSignedBlock.Block()
 
 	commitments, err := roBlock.Body().BlobKzgCommitments()
@@ -266,6 +270,46 @@ func (p *BeaconDbBlocker) Blobs(ctx context.Context, id string, indices []int) (
 		}
 	}
 
+	// Convert versioned hashes to indices if provided
+	indices := cfg.Indices
+	if len(cfg.VersionedHashes) > 0 {
+		// Build a map of requested versioned hashes for fast lookup and tracking
+		requestedHashes := make(map[string]bool)
+		for _, versionedHash := range cfg.VersionedHashes {
+			requestedHashes[string(versionedHash)] = true
+		}
+
+		// Create indices array and track which hashes we found
+		indices = make([]int, 0, len(cfg.VersionedHashes))
+		foundHashes := make(map[string]bool)
+
+		for i, commitment := range commitments {
+			versionedHash := primitives.ConvertKzgCommitmentToVersionedHash(commitment)
+			hashStr := string(versionedHash[:])
+			if requestedHashes[hashStr] {
+				indices = append(indices, i)
+				foundHashes[hashStr] = true
+			}
+		}
+
+		// Check if all requested hashes were found
+		if len(indices) != len(cfg.VersionedHashes) {
+			// Collect missing hashes
+			missingHashes := make([]string, 0, len(cfg.VersionedHashes)-len(indices))
+			for _, requestedHash := range cfg.VersionedHashes {
+				if !foundHashes[string(requestedHash)] {
+					missingHashes = append(missingHashes, hexutil.Encode(requestedHash))
+				}
+			}
+
+			// Create detailed error message
+			errMsg := fmt.Sprintf("versioned hash(es) not found in block (requested %d hashes, found %d, missing: %v)",
+				len(cfg.VersionedHashes), len(indices), missingHashes)
+
+			return nil, &core.RpcError{Err: errors.New(errMsg), Reason: core.NotFound}
+		}
+	}
+
 	if roBlock.Slot() >= fuluForkSlot {
 		roBlock, err := blocks.NewROBlockWithRoot(roSignedBlock, root)
 		if err != nil {

beacon-chain/rpc/lookup/blocker_test.go

@@ -14,11 +14,13 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	testDB "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/core"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/options"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/testutil"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	"github.com/OffchainLabs/prysm/v6/encoding/bytesutil"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v6/testing/assert"
@@ -220,16 +222,13 @@ func TestGetBlob(t *testing.T) {
 		cellsAndProofsList = append(cellsAndProofsList, cellsAndProogs)
 	}
 
-	dataColumnSidecarPb, err := peerdas.DataColumnSidecars(fuluBlock, cellsAndProofsList)
+	roDataColumnSidecars, err := peerdas.DataColumnSidecars(cellsAndProofsList, peerdas.PopulateFromBlock(fuluBlock))
 	require.NoError(t, err)
 
-	verifiedRoDataColumnSidecars := make([]blocks.VerifiedRODataColumn, 0, len(dataColumnSidecarPb))
-	for _, sidecarPb := range dataColumnSidecarPb {
-		roDataColumn, err := blocks.NewRODataColumnWithRoot(sidecarPb, fuluBlockRoot)
-		require.NoError(t, err)
-
-		verifiedRoDataColumn := blocks.NewVerifiedRODataColumn(roDataColumn)
-		verifiedRoDataColumnSidecars = append(verifiedRoDataColumnSidecars, verifiedRoDataColumn)
+	verifiedRoDataColumnSidecars := make([]blocks.VerifiedRODataColumn, 0, len(roDataColumnSidecars))
+	for _, roDataColumnSidecar := range roDataColumnSidecars {
+		verifiedRoDataColumnSidecar := blocks.NewVerifiedRODataColumn(roDataColumnSidecar)
+		verifiedRoDataColumnSidecars = append(verifiedRoDataColumnSidecars, verifiedRoDataColumnSidecar)
 	}
 
 	err = db.SaveBlock(t.Context(), fuluBlock)
@@ -239,7 +238,7 @@ func TestGetBlob(t *testing.T) {
 		setupDeneb(t)
 
 		blocker := &BeaconDbBlocker{}
-		_, rpcErr := blocker.Blobs(ctx, "genesis", nil)
+		_, rpcErr := blocker.Blobs(ctx, "genesis")
 		require.Equal(t, http.StatusBadRequest, core.ErrorReasonToHTTP(rpcErr.Reason))
 		require.StringContains(t, "blobs are not supported for Phase 0 fork", rpcErr.Err.Error())
 	})
@@ -256,7 +255,7 @@ func TestGetBlob(t *testing.T) {
 			BlobStorage: blobStorage,
 		}
 
-		retrievedVerifiedSidecars, rpcErr := blocker.Blobs(ctx, "head", nil)
+		retrievedVerifiedSidecars, rpcErr := blocker.Blobs(ctx, "head")
 		require.IsNil(t, rpcErr)
 		require.Equal(t, blobCount, len(retrievedVerifiedSidecars))
 
@@ -285,7 +284,7 @@ func TestGetBlob(t *testing.T) {
 			BlobStorage: blobStorage,
 		}
 
-		verifiedSidecars, rpcErr := blocker.Blobs(ctx, "finalized", nil)
+		verifiedSidecars, rpcErr := blocker.Blobs(ctx, "finalized")
 		require.IsNil(t, rpcErr)
 		require.Equal(t, blobCount, len(verifiedSidecars))
 	})
@@ -302,7 +301,7 @@ func TestGetBlob(t *testing.T) {
 			BlobStorage: blobStorage,
 		}
 
-		verifiedSidecars, rpcErr := blocker.Blobs(ctx, "justified", nil)
+		verifiedSidecars, rpcErr := blocker.Blobs(ctx, "justified")
 		require.IsNil(t, rpcErr)
 		require.Equal(t, blobCount, len(verifiedSidecars))
 	})
@@ -318,7 +317,7 @@ func TestGetBlob(t *testing.T) {
 			BlobStorage: blobStorage,
 		}
 
-		verifiedBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(denebBlockRoot[:]), nil)
+		verifiedBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(denebBlockRoot[:]))
 		require.IsNil(t, rpcErr)
 		require.Equal(t, blobCount, len(verifiedBlobs))
 	})
@@ -334,7 +333,7 @@ func TestGetBlob(t *testing.T) {
 			BlobStorage: blobStorage,
 		}
 
-		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "123", nil)
+		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "123")
 		require.IsNil(t, rpcErr)
 		require.Equal(t, blobCount, len(verifiedBlobs))
 	})
@@ -353,7 +352,7 @@ func TestGetBlob(t *testing.T) {
 			BlobStorage: blobStorage,
 		}
 
-		retrievedVerifiedSidecars, rpcErr := blocker.Blobs(ctx, "123", []int{index})
+		retrievedVerifiedSidecars, rpcErr := blocker.Blobs(ctx, "123", options.WithIndices([]int{index}))
 		require.IsNil(t, rpcErr)
 		require.Equal(t, 1, len(retrievedVerifiedSidecars))
 
@@ -379,7 +378,7 @@ func TestGetBlob(t *testing.T) {
 			BlobStorage: filesystem.NewEphemeralBlobStorage(t),
 		}
 
-		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "123", nil)
+		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "123")
 		require.IsNil(t, rpcErr)
 		require.Equal(t, 0, len(verifiedBlobs))
 	})
@@ -397,7 +396,7 @@ func TestGetBlob(t *testing.T) {
 		}
 
 		noBlobIndex := len(storedBlobSidecars) + 1
-		_, rpcErr := blocker.Blobs(ctx, "123", []int{0, noBlobIndex})
+		_, rpcErr := blocker.Blobs(ctx, "123", options.WithIndices([]int{0, noBlobIndex}))
 		require.NotNil(t, rpcErr)
 		require.Equal(t, core.ErrorReason(core.NotFound), rpcErr.Reason)
 	})
@@ -413,7 +412,7 @@ func TestGetBlob(t *testing.T) {
 			BeaconDB:    db,
 			BlobStorage: blobStorage,
 		}
-		_, rpcErr := blocker.Blobs(ctx, "123", []int{0, math.MaxInt})
+		_, rpcErr := blocker.Blobs(ctx, "123", options.WithIndices([]int{0, math.MaxInt}))
 		require.NotNil(t, rpcErr)
 		require.Equal(t, core.ErrorReason(core.BadRequest), rpcErr.Reason)
 	})
@@ -434,7 +433,7 @@ func TestGetBlob(t *testing.T) {
 			DataColumnStorage: dataColumnStorage,
 		}
 
-		_, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]), nil)
+		_, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]))
 		require.NotNil(t, rpcErr)
 		require.Equal(t, core.ErrorReason(core.NotFound), rpcErr.Reason)
 	})
@@ -455,7 +454,7 @@ func TestGetBlob(t *testing.T) {
 			DataColumnStorage: dataColumnStorage,
 		}
 
-		retrievedVerifiedRoBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]), nil)
+		retrievedVerifiedRoBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]))
 		require.IsNil(t, rpcErr)
 		require.Equal(t, len(fuluBlobSidecars), len(retrievedVerifiedRoBlobs))
 
@@ -482,7 +481,7 @@ func TestGetBlob(t *testing.T) {
 			DataColumnStorage: dataColumnStorage,
 		}
 
-		retrievedVerifiedRoBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]), nil)
+		retrievedVerifiedRoBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]))
 		require.IsNil(t, rpcErr)
 		require.Equal(t, len(fuluBlobSidecars), len(retrievedVerifiedRoBlobs))
 
@@ -493,3 +492,164 @@ func TestGetBlob(t *testing.T) {
 		}
 	})
 }
+
+func TestBlobs_CommitmentOrdering(t *testing.T) {
+	// Set up Fulu fork configuration
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig().Copy()
+	cfg.DenebForkEpoch = 1
+	cfg.FuluForkEpoch = 2
+	params.OverrideBeaconConfig(cfg)
+
+	beaconDB := testDB.SetupDB(t)
+	ctx := t.Context()
+
+	// Start the trusted setup for KZG
+	err := kzg.Start()
+	require.NoError(t, err)
+
+	// Create Fulu/Electra block with multiple blob commitments
+	fuluForkSlot := primitives.Slot(cfg.FuluForkEpoch) * params.BeaconConfig().SlotsPerEpoch
+	parent := [32]byte{}
+	fuluBlock, fuluBlobs := util.GenerateTestElectraBlockWithSidecar(t, parent, fuluForkSlot, 3)
+
+	// Save the block
+	err = beaconDB.SaveBlock(ctx, fuluBlock)
+	require.NoError(t, err)
+	fuluBlockRoot := fuluBlock.Root()
+
+	// Get the commitments from the generated block
+	commitments, err := fuluBlock.Block().Body().BlobKzgCommitments()
+	require.NoError(t, err)
+	require.Equal(t, 3, len(commitments))
+
+	// Convert blob sidecars to data column sidecars for Fulu
+	cellsAndProofsList := make([]kzg.CellsAndProofs, 0, len(fuluBlobs))
+	for _, blob := range fuluBlobs {
+		var kzgBlob kzg.Blob
+		copy(kzgBlob[:], blob.Blob)
+		cellsAndProofs, err := kzg.ComputeCellsAndKZGProofs(&kzgBlob)
+		require.NoError(t, err)
+		cellsAndProofsList = append(cellsAndProofsList, cellsAndProofs)
+	}
+
+	dataColumnSidecarPb, err := peerdas.DataColumnSidecars(cellsAndProofsList, peerdas.PopulateFromBlock(fuluBlock))
+	require.NoError(t, err)
+
+	verifiedRoDataColumnSidecars := make([]blocks.VerifiedRODataColumn, 0, len(dataColumnSidecarPb))
+	for _, roDataColumn := range dataColumnSidecarPb {
+		verifiedRoDataColumn := blocks.NewVerifiedRODataColumn(roDataColumn)
+		verifiedRoDataColumnSidecars = append(verifiedRoDataColumnSidecars, verifiedRoDataColumn)
+	}
+
+	// Set up data column storage and save data columns
+	_, dataColumnStorage := filesystem.NewEphemeralDataColumnStorageAndFs(t)
+	err = dataColumnStorage.Save(verifiedRoDataColumnSidecars)
+	require.NoError(t, err)
+
+	// Set up the blocker
+	chainService := &mockChain.ChainService{
+		Genesis: time.Now(),
+		FinalizedCheckPoint: &ethpb.Checkpoint{
+			Epoch: 0,
+			Root:  fuluBlockRoot[:],
+		},
+	}
+	blocker := &BeaconDbBlocker{
+		BeaconDB:           beaconDB,
+		ChainInfoFetcher:   chainService,
+		GenesisTimeFetcher: chainService,
+		BlobStorage:        filesystem.NewEphemeralBlobStorage(t),
+		DataColumnStorage:  dataColumnStorage,
+	}
+
+	// Compute versioned hashes for commitments in their block order
+	hash0 := primitives.ConvertKzgCommitmentToVersionedHash(commitments[0])
+	hash1 := primitives.ConvertKzgCommitmentToVersionedHash(commitments[1])
+	hash2 := primitives.ConvertKzgCommitmentToVersionedHash(commitments[2])
+
+	t.Run("blobs returned in commitment order regardless of request order", func(t *testing.T) {
+		// Request versioned hashes in reverse order: 2, 1, 0
+		requestedHashes := [][]byte{hash2[:], hash1[:], hash0[:]}
+
+		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "finalized", options.WithVersionedHashes(requestedHashes))
+		if rpcErr != nil {
+			t.Errorf("RPC Error: %v (reason: %v)", rpcErr.Err, rpcErr.Reason)
+			return
+		}
+		require.Equal(t, 3, len(verifiedBlobs))
+
+		// Verify blobs are returned in commitment order from the block (0, 1, 2)
+		// In Fulu, blobs are reconstructed from data columns
+		assert.Equal(t, uint64(0), verifiedBlobs[0].Index) // First commitment in block
+		assert.Equal(t, uint64(1), verifiedBlobs[1].Index) // Second commitment in block
+		assert.Equal(t, uint64(2), verifiedBlobs[2].Index) // Third commitment in block
+
+		// Verify the blob content matches what we expect
+		for i, verifiedBlob := range verifiedBlobs {
+			require.NotNil(t, verifiedBlob.BlobSidecar)
+			require.DeepEqual(t, fuluBlobs[i].Blob, verifiedBlob.Blob)
+			require.DeepEqual(t, fuluBlobs[i].KzgCommitment, verifiedBlob.KzgCommitment)
+		}
+	})
+
+	t.Run("subset of blobs maintains commitment order", func(t *testing.T) {
+		// Request hashes for indices 1 and 0 (out of order)
+		requestedHashes := [][]byte{hash1[:], hash0[:]}
+
+		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "finalized", options.WithVersionedHashes(requestedHashes))
+		if rpcErr != nil {
+			t.Errorf("RPC Error: %v (reason: %v)", rpcErr.Err, rpcErr.Reason)
+			return
+		}
+		require.Equal(t, 2, len(verifiedBlobs))
+
+		// Verify blobs are returned in commitment order from the block
+		assert.Equal(t, uint64(0), verifiedBlobs[0].Index) // First commitment in block
+		assert.Equal(t, uint64(1), verifiedBlobs[1].Index) // Second commitment in block
+
+		// Verify the blob content matches what we expect
+		require.DeepEqual(t, fuluBlobs[0].Blob, verifiedBlobs[0].Blob)
+		require.DeepEqual(t, fuluBlobs[1].Blob, verifiedBlobs[1].Blob)
+	})
+
+	t.Run("request non-existent hash", func(t *testing.T) {
+		// Create a fake versioned hash
+		fakeHash := make([]byte, 32)
+		for i := 0; i < 32; i++ {
+			fakeHash[i] = 0xFF
+		}
+
+		// Request only the fake hash
+		requestedHashes := [][]byte{fakeHash}
+
+		_, rpcErr := blocker.Blobs(ctx, "finalized", options.WithVersionedHashes(requestedHashes))
+		require.NotNil(t, rpcErr)
+		require.Equal(t, core.ErrorReason(core.NotFound), rpcErr.Reason)
+		require.StringContains(t, "versioned hash(es) not found in block", rpcErr.Err.Error())
+		require.StringContains(t, "requested 1 hashes, found 0", rpcErr.Err.Error())
+		require.StringContains(t, "0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", rpcErr.Err.Error())
+	})
+
+	t.Run("request multiple non-existent hashes", func(t *testing.T) {
+		// Create two fake versioned hashes
+		fakeHash1 := make([]byte, 32)
+		fakeHash2 := make([]byte, 32)
+		for i := 0; i < 32; i++ {
+			fakeHash1[i] = 0xAA
+			fakeHash2[i] = 0xBB
+		}
+
+		// Request valid hash with two fake hashes
+		requestedHashes := [][]byte{fakeHash1, hash0[:], fakeHash2}
+
+		_, rpcErr := blocker.Blobs(ctx, "finalized", options.WithVersionedHashes(requestedHashes))
+		require.NotNil(t, rpcErr)
+		require.Equal(t, core.ErrorReason(core.NotFound), rpcErr.Reason)
+		require.StringContains(t, "versioned hash(es) not found in block", rpcErr.Err.Error())
+		require.StringContains(t, "requested 3 hashes, found 1", rpcErr.Err.Error())
+		// Check that both missing hashes are reported
+		require.StringContains(t, "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", rpcErr.Err.Error())
+		require.StringContains(t, "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb", rpcErr.Err.Error())
+	})
+}

beacon-chain/rpc/options/BUILD.bazel

@@ -0,0 +1,8 @@
+load("@prysm//tools/go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["options.go"],
+    importpath = "github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/options",
+    visibility = ["//visibility:public"],
+)

beacon-chain/rpc/options/options.go

@@ -0,0 +1,24 @@
+package options
+
+// BlobsOption is a functional option for configuring blob retrieval
+type BlobsOption func(*BlobsConfig)
+
+// BlobsConfig holds configuration for blob retrieval
+type BlobsConfig struct {
+	Indices         []int
+	VersionedHashes [][]byte
+}
+
+// WithIndices specifies blob indices to retrieve
+func WithIndices(indices []int) BlobsOption {
+	return func(c *BlobsConfig) {
+		c.Indices = indices
+	}
+}
+
+// WithVersionedHashes specifies versioned hashes to retrieve blobs by
+func WithVersionedHashes(hashes [][]byte) BlobsOption {
+	return func(c *BlobsConfig) {
+		c.VersionedHashes = hashes
+	}
+}

beacon-chain/rpc/prysm/v1alpha1/validator/proposer.go

@@ -281,7 +281,7 @@ func (vs *Server) BuildBlockParallel(ctx context.Context, sBlk interfaces.Signed
 func (vs *Server) ProposeBeaconBlock(ctx context.Context, req *ethpb.GenericSignedBeaconBlock) (*ethpb.ProposeResponse, error) {
 	var (
 		blobSidecars       []*ethpb.BlobSidecar
-		dataColumnSidecars []*ethpb.DataColumnSidecar
+		dataColumnSidecars []blocks.RODataColumn
 	)
 
 	ctx, span := trace.StartSpan(ctx, "ProposerServer.ProposeBeaconBlock")
@@ -309,10 +309,11 @@ func (vs *Server) ProposeBeaconBlock(ctx context.Context, req *ethpb.GenericSign
 		return &ethpb.ProposeResponse{BlockRoot: root[:]}, nil
 	}
 
+	rob, err := blocks.NewROBlockWithRoot(block, root)
 	if block.IsBlinded() {
 		block, blobSidecars, err = vs.handleBlindedBlock(ctx, block)
 	} else if block.Version() >= version.Deneb {
-		blobSidecars, dataColumnSidecars, err = vs.handleUnblindedBlock(block, req)
+		blobSidecars, dataColumnSidecars, err = vs.handleUnblindedBlock(rob, req)
 	}
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "%s: %v", "handle block failed", err)
@@ -348,10 +349,10 @@ func (vs *Server) broadcastAndReceiveSidecars(
 	block interfaces.SignedBeaconBlock,
 	root [fieldparams.RootLength]byte,
 	blobSidecars []*ethpb.BlobSidecar,
-	dataColumnSideCars []*ethpb.DataColumnSidecar,
+	dataColumnSidecars []blocks.RODataColumn,
 ) error {
 	if block.Version() >= version.Fulu {
-		if err := vs.broadcastAndReceiveDataColumns(ctx, dataColumnSideCars, root); err != nil {
+		if err := vs.broadcastAndReceiveDataColumns(ctx, dataColumnSidecars, root); err != nil {
 			return errors.Wrap(err, "broadcast and receive data columns")
 		}
 		return nil
@@ -398,21 +399,28 @@ func (vs *Server) handleBlindedBlock(ctx context.Context, block interfaces.Signe
 }
 
 func (vs *Server) handleUnblindedBlock(
-	block interfaces.SignedBeaconBlock,
+	block blocks.ROBlock,
 	req *ethpb.GenericSignedBeaconBlock,
-) ([]*ethpb.BlobSidecar, []*ethpb.DataColumnSidecar, error) {
+) ([]*ethpb.BlobSidecar, []blocks.RODataColumn, error) {
 	rawBlobs, proofs, err := blobsAndProofs(req)
 	if err != nil {
 		return nil, nil, err
 	}
 
 	if block.Version() >= version.Fulu {
-		dataColumnSideCars, err := peerdas.ConstructDataColumnSidecars(block, rawBlobs, proofs)
+		// Compute cells and proofs from the blobs and cell proofs.
+		cellsAndProofs, err := peerdas.ComputeCellsAndProofsFromFlat(rawBlobs, proofs)
 		if err != nil {
-			return nil, nil, errors.Wrap(err, "construct data column sidecars")
+			return nil, nil, errors.Wrap(err, "compute cells and proofs")
 		}
 
-		return nil, dataColumnSideCars, nil
+		// Construct data column sidecars from the signed block and cells and proofs.
+		roDataColumnSidecars, err := peerdas.DataColumnSidecars(cellsAndProofs, peerdas.PopulateFromBlock(block))
+		if err != nil {
+			return nil, nil, errors.Wrap(err, "data column sidcars")
+		}
+
+		return nil, roDataColumnSidecars, nil
 	}
 
 	blobSidecars, err := BuildBlobSidecars(block, rawBlobs, proofs)
@@ -468,26 +476,21 @@ func (vs *Server) broadcastAndReceiveBlobs(ctx context.Context, sidecars []*ethp
 // broadcastAndReceiveDataColumns handles the broadcasting and reception of data columns sidecars.
 func (vs *Server) broadcastAndReceiveDataColumns(
 	ctx context.Context,
-	sidecars []*ethpb.DataColumnSidecar,
+	roSidecars []blocks.RODataColumn,
 	root [fieldparams.RootLength]byte,
 ) error {
-	verifiedRODataColumns := make([]blocks.VerifiedRODataColumn, 0, len(sidecars))
+	verifiedRODataColumns := make([]blocks.VerifiedRODataColumn, 0, len(roSidecars))
 	eg, _ := errgroup.WithContext(ctx)
-	for _, sidecar := range sidecars {
-		roDataColumn, err := blocks.NewRODataColumnWithRoot(sidecar, root)
-		if err != nil {
-			return errors.Wrap(err, "new read-only data column with root")
-		}
-
+	for _, roSidecar := range roSidecars {
 		// We build this block ourselves, so we can upgrade the read only data column sidecar into a verified one.
-		verifiedRODataColumn := blocks.NewVerifiedRODataColumn(roDataColumn)
+		verifiedRODataColumn := blocks.NewVerifiedRODataColumn(roSidecar)
 		verifiedRODataColumns = append(verifiedRODataColumns, verifiedRODataColumn)
 
 		eg.Go(func() error {
 			// Compute the subnet index based on the column index.
-			subnet := peerdas.ComputeSubnetForDataColumnSidecar(sidecar.Index)
+			subnet := peerdas.ComputeSubnetForDataColumnSidecar(roSidecar.Index)
 
-			if err := vs.P2P.BroadcastDataColumnSidecar(root, subnet, sidecar); err != nil {
+			if err := vs.P2P.BroadcastDataColumnSidecar(subnet, verifiedRODataColumn); err != nil {
 				return errors.Wrap(err, "broadcast data column")
 			}
 

beacon-chain/rpc/prysm/v1alpha1/validator/proposer_deneb.go

@@ -10,7 +10,7 @@ import (
 )
 
 // BuildBlobSidecars given a block, builds the blob sidecars for the block.
-func BuildBlobSidecars(blk interfaces.SignedBeaconBlock, blobs [][]byte, kzgProofs [][]byte) ([]*ethpb.BlobSidecar, error) {
+func BuildBlobSidecars(blk interfaces.ReadOnlySignedBeaconBlock, blobs [][]byte, kzgProofs [][]byte) ([]*ethpb.BlobSidecar, error) {
 	if blk.Version() < version.Deneb {
 		return nil, nil // No blobs before deneb.
 	}

beacon-chain/rpc/service.go

@@ -16,10 +16,10 @@ import (
 	blockfeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/block"
 	opfeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/operation"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/execution"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/blstoexec"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/slashings"

beacon-chain/rpc/testutil/BUILD.bazel

@@ -16,6 +16,7 @@ go_library(
     deps = [
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/rpc/core:go_default_library",
+        "//beacon-chain/rpc/options:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",

beacon-chain/rpc/testutil/mock_blocker.go

@@ -5,6 +5,7 @@ import (
 	"strconv"
 
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/core"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/options"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
@@ -36,6 +37,6 @@ func (m *MockBlocker) Block(_ context.Context, b []byte) (interfaces.ReadOnlySig
 }
 
 // Blobs --
-func (*MockBlocker) Blobs(_ context.Context, _ string, _ []int) ([]*blocks.VerifiedROBlob, *core.RpcError) {
+func (*MockBlocker) Blobs(_ context.Context, _ string, _ ...options.BlobsOption) ([]*blocks.VerifiedROBlob, *core.RpcError) {
 	return nil, &core.RpcError{}
 }

beacon-chain/sync/BUILD.bazel

@@ -14,7 +14,6 @@ go_library(
         "doc.go",
         "error.go",
         "fork_watcher.go",
-        "fuzz_exports.go",  # keep
         "log.go",
         "metrics.go",
         "options.go",
@@ -49,6 +48,7 @@ go_library(
         "subscriber_sync_committee_message.go",
         "subscriber_sync_contribution_proof.go",
         "subscription_topic_handler.go",
+        "toggle.go",
         "validate_aggregate_proof.go",
         "validate_attester_slashing.go",
         "validate_beacon_attestation.go",
@@ -63,11 +63,7 @@ go_library(
         "validate_voluntary_exit.go",
     ],
     importpath = "github.com/OffchainLabs/prysm/v6/beacon-chain/sync",
-    visibility = [
-        "//beacon-chain:__subpackages__",
-        "//cmd:__subpackages__",
-        "//testing:__subpackages__",
-    ],
+    visibility = ["//visibility:public"],
     deps = [
         "//async:go_default_library",
         "//async/abool:go_default_library",
@@ -81,7 +77,6 @@ go_library(
         "//beacon-chain/core/feed/operation:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
-        "//beacon-chain/core/light-client:go_default_library",
         "//beacon-chain/core/peerdas:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
         "//beacon-chain/core/transition:go_default_library",
@@ -90,6 +85,7 @@ go_library(
         "//beacon-chain/db/filesystem:go_default_library",
         "//beacon-chain/db/filters:go_default_library",
         "//beacon-chain/execution:go_default_library",
+        "//beacon-chain/light-client:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/blstoexec:go_default_library",
         "//beacon-chain/operations/slashings:go_default_library",
@@ -154,12 +150,13 @@ go_library(
         "@com_github_trailofbits_go_mutexasserts//:go_default_library",
         "@io_opentelemetry_go_otel_trace//:go_default_library",
         "@org_golang_google_protobuf//proto:go_default_library",
+        "@org_golang_x_sync//errgroup:go_default_library",
+        "@org_golang_x_sync//singleflight:go_default_library",
     ],
 )
 
 go_test(
     name = "go_default_test",
-    size = "small",
     srcs = [
         "batch_verifier_test.go",
         "blobs_test.go",
@@ -171,6 +168,7 @@ go_test(
         "decode_pubsub_test.go",
         "error_test.go",
         "fork_watcher_test.go",
+        "kzg_batch_verifier_test.go",
         "pending_attestations_queue_test.go",
         "pending_blocks_queue_test.go",
         "rate_limiter_test.go",
@@ -197,6 +195,7 @@ go_test(
         "subscription_topic_handler_test.go",
         "sync_fuzz_test.go",
         "sync_test.go",
+        "toggle_test.go",
         "validate_aggregate_proof_test.go",
         "validate_attester_slashing_test.go",
         "validate_beacon_attestation_test.go",
@@ -211,7 +210,6 @@ go_test(
         "validate_voluntary_exit_test.go",
     ],
     embed = [":go_default_library"],
-    shard_count = 4,
     deps = [
         "//async/abool:go_default_library",
         "//async/event:go_default_library",
@@ -223,7 +221,6 @@ go_test(
         "//beacon-chain/core/feed:go_default_library",
         "//beacon-chain/core/feed/operation:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
-        "//beacon-chain/core/light-client:go_default_library",
         "//beacon-chain/core/peerdas:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
         "//beacon-chain/core/time:go_default_library",
@@ -235,6 +232,7 @@ go_test(
         "//beacon-chain/execution:go_default_library",
         "//beacon-chain/execution/testing:go_default_library",
         "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
+        "//beacon-chain/light-client:go_default_library",
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/blstoexec:go_default_library",
         "//beacon-chain/operations/slashings:go_default_library",

beacon-chain/sync/backfill/pool.go

@@ -45,11 +45,12 @@ type p2pBatchWorkerPool struct {
 	endSeq      []batch
 	ctx         context.Context
 	cancel      func()
+	toggle      *sync.ServiceToggler
 }
 
 var _ batchWorkerPool = &p2pBatchWorkerPool{}
 
-func newP2PBatchWorkerPool(p p2p.P2P, maxBatches int) *p2pBatchWorkerPool {
+func newP2PBatchWorkerPool(p p2p.P2P, maxBatches int, tg *sync.ServiceToggler) *p2pBatchWorkerPool {
 	nw := defaultNewWorker(p)
 	return &p2pBatchWorkerPool{
 		newWorker:   nw,
@@ -59,6 +60,7 @@ func newP2PBatchWorkerPool(p p2p.P2P, maxBatches int) *p2pBatchWorkerPool {
 		fromWorkers: make(chan batch),
 		maxBatches:  maxBatches,
 		shutdownErr: make(chan error),
+		toggle:      tg,
 	}
 }
 
@@ -115,6 +117,7 @@ func (p *p2pBatchWorkerPool) batchRouter(pa PeerAssigner) {
 			// This ticker exists to periodically break out of the channel select
 			// to retry failed assignments.
 		case b := <-p.fromWorkers:
+			p.toggle.Release(sync.ToggleGroupBackfill)
 			pid := b.busy
 			busy[pid] = false
 			if b.state == batchBlobSync {
@@ -143,6 +146,9 @@ func (p *p2pBatchWorkerPool) batchRouter(pa PeerAssigner) {
 			return
 		}
 		for _, pid := range assigned {
+			if err := p.toggle.Acquire(p.ctx, sync.ToggleGroupBackfill); err != nil {
+				p.shutdown(err)
+			}
 			if err := todo[0].waitUntilReady(p.ctx); err != nil {
 				log.WithError(p.ctx.Err()).Info("p2pBatchWorkerPool context canceled, shutting down")
 				p.shutdown(p.ctx.Err())

beacon-chain/sync/backfill/pool_test.go

@@ -42,7 +42,8 @@ func TestPoolDetectAllEnded(t *testing.T) {
 	p2p := p2ptest.NewTestP2P(t)
 	ctx := t.Context()
 	ma := &mockAssigner{}
-	pool := newP2PBatchWorkerPool(p2p, nw)
+	tg := sync.NewServiceToggler()
+	pool := newP2PBatchWorkerPool(p2p, nw, tg)
 	st, err := util.NewBeaconState()
 	require.NoError(t, err)
 	keys, err := st.PublicKeys()

beacon-chain/sync/backfill/service.go

@@ -22,7 +22,7 @@ import (
 
 type Service struct {
 	ctx             context.Context
-	enabled         bool // service is disabled by default while feature is experimental
+	enabled         bool // service is disabled by default
 	clock           *startup.Clock
 	store           *Store
 	ms              minimumSlotter
@@ -41,6 +41,7 @@ type Service struct {
 	blobStore       *filesystem.BlobStorage
 	initSyncWaiter  func() error
 	complete        chan struct{}
+	toggler         *sync.ServiceToggler
 }
 
 var _ runtime.Service = (*Service)(nil)
@@ -104,6 +105,15 @@ func WithInitSyncWaiter(w func() error) ServiceOption {
 	}
 }
 
+// WithServiceToggle sets the ServiceToggler, which is used to coordinate
+// with backfill, so that only one service runs at a time.
+func WithServiceToggle(toggler *sync.ServiceToggler) ServiceOption {
+	return func(s *Service) error {
+		s.toggler = toggler
+		return nil
+	}
+}
+
 // InitializerWaiter is an interface that is satisfied by verification.InitializerWaiter.
 // Using this interface enables node init to satisfy this requirement for the backfill service
 // while also allowing backfill to mock it in tests.
@@ -157,7 +167,7 @@ func NewService(ctx context.Context, su *Store, bStore *filesystem.BlobStorage,
 			return nil, err
 		}
 	}
-	s.pool = newP2PBatchWorkerPool(p, s.nWorkers)
+	s.pool = newP2PBatchWorkerPool(p, s.nWorkers, s.toggler)
 
 	return s, nil
 }

beacon-chain/sync/batch_verifier.go

@@ -4,6 +4,9 @@ import (
 	"context"
 	"time"
 
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
+	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/crypto/bls"
 	"github.com/OffchainLabs/prysm/v6/monitoring/tracing"
 	"github.com/OffchainLabs/prysm/v6/monitoring/tracing/trace"
@@ -18,6 +21,11 @@ type signatureVerifier struct {
 	resChan chan error
 }
 
+type kzgVerifier struct {
+	dataColumns []blocks.RODataColumn
+	resChan     chan error
+}
+
 // A routine that runs in the background to perform batch
 // verifications of incoming messages from gossip.
 func (s *Service) verifierRoutine() {
@@ -47,6 +55,32 @@ func (s *Service) verifierRoutine() {
 	}
 }
 
+// A routine that runs in the background to perform batch
+// KZG verifications by draining the channel and processing all pending requests.
+func (s *Service) kzgVerifierRoutine() {
+	for {
+		kzgBatch := make([]*kzgVerifier, 0, 1)
+		select {
+		case <-s.ctx.Done():
+			return
+		case kzg := <-s.kzgChan:
+			kzgBatch = append(kzgBatch, kzg)
+		}
+		for {
+			select {
+			case <-s.ctx.Done():
+				return
+			case kzg := <-s.kzgChan:
+				kzgBatch = append(kzgBatch, kzg)
+				continue
+			default:
+				verifyKzgBatch(kzgBatch)
+			}
+			break
+		}
+	}
+}
+
 func (s *Service) validateWithBatchVerifier(ctx context.Context, message string, set *bls.SignatureBatch) (pubsub.ValidationResult, error) {
 	_, span := trace.StartSpan(ctx, "sync.validateWithBatchVerifier")
 	defer span.End()
@@ -56,7 +90,6 @@ func (s *Service) validateWithBatchVerifier(ctx context.Context, message string,
 	s.signatureChan <- verificationSet
 
 	resErr := <-resChan
-	close(resChan)
 	// If verification fails we fallback to individual verification
 	// of each signature set.
 	if resErr != nil {
@@ -120,3 +153,62 @@ func performBatchAggregation(aggSet *bls.SignatureBatch) (*bls.SignatureBatch, e
 	}
 	return aggSet, nil
 }
+
+func (s *Service) validateWithKzgBatchVerifier(ctx context.Context, dataColumns []blocks.RODataColumn) (pubsub.ValidationResult, error) {
+	_, span := trace.StartSpan(ctx, "sync.validateWithKzgBatchVerifier")
+	defer span.End()
+
+	timeout := time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second
+
+	resChan := make(chan error)
+	verificationSet := &kzgVerifier{dataColumns: dataColumns, resChan: resChan}
+	s.kzgChan <- verificationSet
+
+	ctx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	select {
+	case <-ctx.Done():
+		return pubsub.ValidationIgnore, ctx.Err() // parent context canceled, give up
+	case err := <-resChan:
+		if err != nil {
+			log.WithError(err).Trace("Could not perform batch verification")
+			tracing.AnnotateError(span, err)
+			return s.validateUnbatchedColumnsKzg(ctx, dataColumns)
+		}
+	}
+	return pubsub.ValidationAccept, nil
+}
+
+func (s *Service) validateUnbatchedColumnsKzg(ctx context.Context, columns []blocks.RODataColumn) (pubsub.ValidationResult, error) {
+	_, span := trace.StartSpan(ctx, "sync.validateUnbatchedColumnsKzg")
+	defer span.End()
+	if err := peerdas.VerifyDataColumnsSidecarKZGProofs(columns); err != nil {
+		err = errors.Wrap(err, "could not verify")
+		tracing.AnnotateError(span, err)
+		return pubsub.ValidationReject, err
+	}
+	return pubsub.ValidationAccept, nil
+}
+
+func verifyKzgBatch(kzgBatch []*kzgVerifier) {
+	if len(kzgBatch) == 0 {
+		return
+	}
+
+	allDataColumns := make([]blocks.RODataColumn, 0, len(kzgBatch))
+	for _, kzgVerifier := range kzgBatch {
+		allDataColumns = append(allDataColumns, kzgVerifier.dataColumns...)
+	}
+
+	var verificationErr error
+	err := peerdas.VerifyDataColumnsSidecarKZGProofs(allDataColumns)
+	if err != nil {
+		verificationErr = errors.Wrap(err, "batch KZG verification failed")
+	}
+
+	// Send the same result to all verifiers in the batch
+	for _, verifier := range kzgBatch {
+		verifier.resChan <- verificationErr
+	}
+}

beacon-chain/sync/data_column_sidecars.go

@@ -39,232 +39,328 @@ type DataColumnSidecarsParams struct {
 	DownscorePeerOnRPCFault bool                                // Downscore a peer if it commits an RPC fault. Not responding sidecars at all is considered as a fault.
 }
 
-// FetchDataColumnSidecars retrieves data column sidecars from storage and peers for the given
-// blocks and requested data column indices. It employs a multi-step strategy:
+// FetchDataColumnSidecars retrieves data column sidecars for the given blocks and indices
+// using a series of fallback strategies.
 //
-//  1. Direct retrieval: If all requested columns are available in storage, they are
-//     retrieved directly without reconstruction.
-//  2. Reconstruction-based retrieval: If some requested columns are missing but sufficient
-//     stored columns exist (at least the minimum required for reconstruction), the function
-//     reconstructs all columns and extracts the requested indices.
-//  3. Peer retrieval: If storage and reconstruction fail, missing columns are requested
-//     from connected peers that are expected to custody the required data.
+// For each block in `roBlocks` that has commitments, the function attempts to obtain
+// all sidecars corresponding to the indices listed in `requestedIndices`.
 //
-// The function returns a map of block roots to their corresponding verified read-only data
-// columns. It returns an error if data column storage is unavailable, if storage/reconstruction
-// operations fail unexpectedly, or if not all requested columns could be retrieved from peers.
+// The function returns:
+//   - A map from block root to the sidecars successfully retrieved.
+//   - A set of block roots for which not all requested sidecars could be retrieved.
+//
+// Retrieval strategy (proceeds to the next step only if not all requested sidecars
+// were successfully obtained at the current step):
+//  1. Attempt to load the requested sidecars from storage, reconstructing them from
+//     other available sidecars in storage if necessary.
+//  2. Request any missing sidecars from peers. If some are still missing, attempt to
+//     reconstruct them using both stored sidecars and those retrieved from peers.
+//  3. Request all remaining possible sidecars from peers that are not already in storage
+//     or retrieved in step 2. Stop once either all requested sidecars are retrieved,
+//     or enough sidecars are available (from storage, step 2, and step 3) to reconstruct
+//     the requested ones.
 func FetchDataColumnSidecars(
 	params DataColumnSidecarsParams,
 	roBlocks []blocks.ROBlock,
-	indicesMap map[uint64]bool,
-) (map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, error) {
-	if len(roBlocks) == 0 || len(indicesMap) == 0 {
-		return nil, nil
+	requestedIndices map[uint64]bool,
+) (map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, map[[fieldparams.RootLength]byte]map[uint64]bool, error) {
+	if len(roBlocks) == 0 || len(requestedIndices) == 0 {
+		return nil, nil, nil
 	}
 
-	indices := sortedSliceFromMap(indicesMap)
-	slotsWithCommitments := make(map[primitives.Slot]bool)
-	missingIndicesByRoot := make(map[[fieldparams.RootLength]byte]map[uint64]bool)
-	indicesByRootStored := make(map[[fieldparams.RootLength]byte]map[uint64]bool)
-	result := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn)
+	blockCount := len(roBlocks)
+
+	// We first consider all requested roots as incomplete, and remove roots from this
+	// set as we retrieve them.
+	incompleteRoots := make(map[[fieldparams.RootLength]byte]bool, blockCount)
+	slotsWithCommitments := make(map[primitives.Slot]bool, blockCount)
+	slotByRoot := make(map[[fieldparams.RootLength]byte]primitives.Slot, blockCount)
+	storedIndicesByRoot := make(map[[fieldparams.RootLength]byte]map[uint64]bool, blockCount)
 
 	for _, roBlock := range roBlocks {
-		// Filter out blocks without commitments.
 		block := roBlock.Block()
+
 		commitments, err := block.Body().BlobKzgCommitments()
 		if err != nil {
-			return nil, errors.Wrapf(err, "get blob kzg commitments for block root %#x", roBlock.Root())
+			return nil, nil, errors.Wrapf(err, "get blob kzg commitments for block root %#x", roBlock.Root())
 		}
+
 		if len(commitments) == 0 {
 			continue
 		}
 
-		slotsWithCommitments[block.Slot()] = true
 		root := roBlock.Root()
+		slot := block.Slot()
 
-		// Step 1: Get the requested sidecars for this root if available in storage
-		requestedColumns, err := tryGetStoredColumns(params.Storage, root, indices)
-		if err != nil {
-			return nil, errors.Wrapf(err, "try get direct columns for root %#x", root)
-		}
-		if requestedColumns != nil {
-			result[root] = requestedColumns
-			continue
-		}
+		incompleteRoots[root] = true
+		slotByRoot[root] = slot
+		slotsWithCommitments[slot] = true
 
-		// Step 2: If step 1 failed, reconstruct the requested sidecars from what is available in storage
-		requestedColumns, err = tryGetReconstructedColumns(params.Storage, root, indices)
-		if err != nil {
-			return nil, errors.Wrapf(err, "try get reconstructed columns for root %#x", root)
-		}
-		if requestedColumns != nil {
-			result[root] = requestedColumns
-			continue
-		}
-
-		// Step 3a: If steps 1 and 2 failed, keep track of the sidecars that need to be queried from peers
-		//          and those that are already stored.
-		indicesToQueryMap, indicesStoredMap := categorizeIndices(params.Storage, root, indices)
-
-		if len(indicesToQueryMap) > 0 {
-			missingIndicesByRoot[root] = indicesToQueryMap
-		}
-		if len(indicesStoredMap) > 0 {
-			indicesByRootStored[root] = indicesStoredMap
+		storedIndices := params.Storage.Summary(root).Stored()
+		if len(storedIndices) > 0 {
+			storedIndicesByRoot[root] = storedIndices
 		}
 	}
 
-	// Early return if no sidecars need to be queried from peers.
-	if len(missingIndicesByRoot) == 0 {
-		return result, nil
-	}
+	initialMissingRootCount := len(incompleteRoots)
 
-	// Step 3b: Request missing sidecars from peers.
-	start, count := time.Now(), computeTotalCount(missingIndicesByRoot)
-	fromPeersResult, err := tryRequestingColumnsFromPeers(params, roBlocks, slotsWithCommitments, missingIndicesByRoot)
+	// Request sidecars from storage (by reconstructing them from other available sidecars if needed).
+	result, err := requestSidecarsFromStorage(params.Storage, storedIndicesByRoot, requestedIndices, incompleteRoots)
 	if err != nil {
-		return nil, errors.Wrap(err, "request from peers")
+		return nil, nil, errors.Wrap(err, "request sidecars from storage")
 	}
 
-	log.WithFields(logrus.Fields{"duration": time.Since(start), "count": count}).Debug("Requested data column sidecars from peers")
+	log := log.WithField("initialMissingRootCount", initialMissingRootCount)
 
-	// Step 3c: If needed, try to reconstruct missing sidecars from storage and fetched data.
-	fromReconstructionResult, err := tryReconstructFromStorageAndPeers(params.Storage, fromPeersResult, indicesMap, missingIndicesByRoot)
+	if len(incompleteRoots) == 0 {
+		log.WithField("finalMissingRootCount", 0).Debug("Fetched data column sidecars from storage")
+		return result, nil, nil
+	}
+
+	// Request direct sidecars from peers.
+	directSidecarsByRoot, err := requestDirectSidecarsFromPeers(params, slotByRoot, requestedIndices, slotsWithCommitments, storedIndicesByRoot, incompleteRoots)
 	if err != nil {
-		return nil, errors.Wrap(err, "reconstruct from storage and peers")
+		return nil, nil, errors.Wrap(err, "request direct sidecars from peers")
 	}
 
-	for root, verifiedSidecars := range fromReconstructionResult {
-		result[root] = verifiedSidecars
+	// Merge sidecars in storage and those received from peers. Reconstruct if needed.
+	mergedSidecarsByRoot, err := mergeAvailableSidecars(params.Storage, requestedIndices, storedIndicesByRoot, incompleteRoots, directSidecarsByRoot)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "try merge storage and mandatory inputs")
 	}
 
-	for root := range fromPeersResult {
-		if _, ok := fromReconstructionResult[root]; ok {
-			// We already have what we need from peers + reconstruction
+	for root, sidecars := range mergedSidecarsByRoot {
+		result[root] = sidecars
+	}
+
+	if len(incompleteRoots) == 0 {
+		log.WithField("finalMissingRootCount", 0).Debug("Fetched data column sidecars from storage and peers")
+		return result, nil, nil
+	}
+
+	// Request all possible indirect sidecars from peers which are neither stored nor in `directSidecarsByRoot`
+	indirectSidecarsByRoot, err := requestIndirectSidecarsFromPeers(params, slotByRoot, slotsWithCommitments, storedIndicesByRoot, directSidecarsByRoot, requestedIndices, incompleteRoots)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "request all sidecars from peers")
+	}
+
+	// Merge sidecars in storage and those received from peers. Reconstruct if needed.
+	mergedSidecarsByRoot, err = mergeAvailableSidecars(params.Storage, requestedIndices, storedIndicesByRoot, incompleteRoots, indirectSidecarsByRoot)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "try merge storage and all inputs")
+	}
+
+	for root, sidecars := range mergedSidecarsByRoot {
+		result[root] = sidecars
+	}
+
+	if len(incompleteRoots) == 0 {
+		log.WithField("finalMissingRootCount", 0).Debug("Fetched data column sidecars from storage and peers using rescue mode")
+		return result, nil, nil
+	}
+
+	// For remaining incomplete roots, assemble what is available.
+	incompleteSidecarsByRoot, missingByRoot, err := assembleAvailableSidecars(params.Storage, requestedIndices, incompleteRoots, directSidecarsByRoot)
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "assemble available sidecars for incomplete roots")
+	}
+
+	for root, sidecars := range incompleteSidecarsByRoot {
+		result[root] = sidecars
+	}
+
+	log.WithField("finalMissingRootCount", len(incompleteRoots)).Debug("Failed to fetch data column sidecars from storage and peers using rescue mode")
+	return result, missingByRoot, nil
+}
+
+// requestSidecarsFromStorage attempts to retrieve data column sidecars for each block root in `roots`
+// and for all indices specified in `requestedIndices`.
+//
+// If not all requested sidecars can be obtained for a given root, that root is excluded from the result.
+// It returns a map from each root to its successfully retrieved sidecars.
+//
+// WARNING: This function mutates `roots` by removing entries for which all requested sidecars
+// were successfully retrieved.
+func requestSidecarsFromStorage(
+	storage filesystem.DataColumnStorageReader,
+	storedIndicesByRoot map[[fieldparams.RootLength]byte]map[uint64]bool,
+	requestedIndicesMap map[uint64]bool,
+	roots map[[fieldparams.RootLength]byte]bool,
+) (map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, error) {
+	requestedIndices := sortedSliceFromMap(requestedIndicesMap)
+
+	result := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, len(roots))
+
+	for root := range roots {
+		storedIndices := storedIndicesByRoot[root]
+
+		// Check if all requested indices are stored.
+		allAvailable := true
+		for index := range requestedIndicesMap {
+			if !storedIndices[index] {
+				allAvailable = false
+				break
+			}
+		}
+
+		// Skip if not all requested indices are stored.
+		if !allAvailable {
 			continue
 		}
 
-		result[root] = append(result[root], fromPeersResult[root]...)
-
-		storedIndices := indicesByRootStored[root]
-		if len(storedIndices) == 0 {
-			continue
-		}
-
-		storedColumns, err := tryGetStoredColumns(params.Storage, root, sortedSliceFromMap(storedIndices))
+		// All requested indices are stored, retrieve them.
+		verifiedRoSidecars, err := storage.Get(root, requestedIndices)
 		if err != nil {
-			return nil, errors.Wrapf(err, "try get direct columns for root %#x", root)
+			return nil, errors.Wrapf(err, "storage get for block root %#x", root)
 		}
 
-		result[root] = append(result[root], storedColumns...)
+		result[root] = verifiedRoSidecars
+		delete(roots, root)
 	}
 
 	return result, nil
 }
 
-// tryGetStoredColumns attempts to retrieve all requested data column sidecars directly from storage
-// if they are all available. Returns the sidecars if successful, and nil if at least one
-// requested sidecar is not available in the storage.
-func tryGetStoredColumns(storage filesystem.DataColumnStorageReader, blockRoot [fieldparams.RootLength]byte, indices []uint64) ([]blocks.VerifiedRODataColumn, error) {
-	// Check if all requested indices are present in cache
-	storedIndices := storage.Summary(blockRoot).Stored()
-	allRequestedPresent := true
-	for _, requestedIndex := range indices {
-		if !storedIndices[requestedIndex] {
-			allRequestedPresent = false
-			break
-		}
-	}
-
-	if !allRequestedPresent {
-		return nil, nil
-	}
-
-	// All requested data is present, retrieve directly from DB
-	requestedColumns, err := storage.Get(blockRoot, indices)
-	if err != nil {
-		return nil, errors.Wrapf(err, "failed to get data columns for block root %#x", blockRoot)
-	}
-
-	return requestedColumns, nil
-}
-
-// tryGetReconstructedColumns attempts to retrieve columns using reconstruction
-// if sufficient columns are available. Returns the columns if successful, nil and nil if insufficient columns,
-// or nil and error if an error occurs.
-func tryGetReconstructedColumns(storage filesystem.DataColumnStorageReader, blockRoot [fieldparams.RootLength]byte, indices []uint64) ([]blocks.VerifiedRODataColumn, error) {
-	// Check if we have enough columns for reconstruction
-	summary := storage.Summary(blockRoot)
-	if summary.Count() < peerdas.MinimumColumnCountToReconstruct() {
-		return nil, nil
-	}
-
-	// Retrieve all stored columns for reconstruction
-	allStoredColumns, err := storage.Get(blockRoot, nil)
-	if err != nil {
-		return nil, errors.Wrapf(err, "failed to get all stored columns for reconstruction for block root %#x", blockRoot)
-	}
-
-	// Attempt reconstruction
-	reconstructedColumns, err := peerdas.ReconstructDataColumnSidecars(allStoredColumns)
-	if err != nil {
-		return nil, errors.Wrapf(err, "failed to reconstruct data columns for block root %#x", blockRoot)
-	}
-
-	// Health check: ensure we have the expected number of columns
-	numberOfColumns := params.BeaconConfig().NumberOfColumns
-	if uint64(len(reconstructedColumns)) != numberOfColumns {
-		return nil, errors.Errorf("reconstructed %d columns but expected %d for block root %#x", len(reconstructedColumns), numberOfColumns, blockRoot)
-	}
-
-	// Extract only the requested indices from reconstructed data using direct indexing
-	requestedColumns := make([]blocks.VerifiedRODataColumn, 0, len(indices))
-	for _, requestedIndex := range indices {
-		if requestedIndex >= numberOfColumns {
-			return nil, errors.Errorf("requested column index %d exceeds maximum %d for block root %#x", requestedIndex, numberOfColumns-1, blockRoot)
-		}
-		requestedColumns = append(requestedColumns, reconstructedColumns[requestedIndex])
-	}
-
-	return requestedColumns, nil
-}
-
-// categorizeIndices separates indices into those that need to be queried from peers
-// and those that are already stored.
-func categorizeIndices(storage filesystem.DataColumnStorageReader, blockRoot [fieldparams.RootLength]byte, indices []uint64) (map[uint64]bool, map[uint64]bool) {
-	indicesToQuery := make(map[uint64]bool, len(indices))
-	indicesStored := make(map[uint64]bool, len(indices))
-
-	allStoredIndices := storage.Summary(blockRoot).Stored()
-	for _, index := range indices {
-		if allStoredIndices[index] {
-			indicesStored[index] = true
-			continue
-		}
-		indicesToQuery[index] = true
-	}
-
-	return indicesToQuery, indicesStored
-}
-
-// tryRequestingColumnsFromPeers attempts to request missing data column sidecars from connected peers.
-// It explores the connected peers to find those that are expected to custody the requested columns
-// and returns only when all requested columns are either retrieved or have been tried to be retrieved
-// by all possible peers.
-// WARNING: This function alters `missingIndicesByRoot` by removing successfully retrieved columns.
-// After running this function, the user can check the content of the (modified) `missingIndicesByRoot` map
-// to check if some sidecars are still missing.
-func tryRequestingColumnsFromPeers(
-	p DataColumnSidecarsParams,
-	roBlocks []blocks.ROBlock,
+// requestDirectSidecarsFromPeers tries to fetch missing data column sidecars from connected peers.
+// It searches through the available peers to identify those responsible for the requested columns,
+// and returns only after all columns have either been successfully retrieved or all candidate peers
+// have been exhausted.
+//
+// It returns a map from each root to its successfully retrieved sidecars.
+func requestDirectSidecarsFromPeers(
+	params DataColumnSidecarsParams,
+	slotByRoot map[[fieldparams.RootLength]byte]primitives.Slot,
+	requestedIndices map[uint64]bool,
 	slotsWithCommitments map[primitives.Slot]bool,
-	missingIndicesByRoot map[[fieldparams.RootLength]byte]map[uint64]bool,
+	storedIndicesByRoot map[[fieldparams.RootLength]byte]map[uint64]bool,
+	incompleteRoots map[[fieldparams.RootLength]byte]bool,
 ) (map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, error) {
+	start := time.Now()
+
 	// Create a new random source for peer selection.
 	randomSource := rand.NewGenerator()
 
-	// Compute slots by block root.
-	slotByRoot := computeSlotByBlockRoot(roBlocks)
+	// Determine all sidecars each peers are expected to custody.
+	connectedPeersSlice := params.P2P.Peers().Connected()
+	connectedPeers := make(map[goPeer.ID]bool, len(connectedPeersSlice))
+	for _, peer := range connectedPeersSlice {
+		connectedPeers[peer] = true
+	}
+
+	// Compute missing indices by root, excluding those already in storage.
+	missingIndicesByRoot := make(map[[fieldparams.RootLength]byte]map[uint64]bool, len(incompleteRoots))
+	for root := range incompleteRoots {
+		storedIndices := storedIndicesByRoot[root]
+
+		missingIndices := make(map[uint64]bool, len(requestedIndices))
+		for index := range requestedIndices {
+			if !storedIndices[index] {
+				missingIndices[index] = true
+			}
+		}
+
+		if len(missingIndices) > 0 {
+			missingIndicesByRoot[root] = missingIndices
+		}
+	}
+
+	initialMissingCount := computeTotalCount(missingIndicesByRoot)
+
+	indicesByRootByPeer, err := computeIndicesByRootByPeer(params.P2P, slotByRoot, missingIndicesByRoot, connectedPeers)
+	if err != nil {
+		return nil, errors.Wrap(err, "explore peers")
+	}
+
+	verifiedColumnsByRoot := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn)
+	for len(missingIndicesByRoot) > 0 && len(indicesByRootByPeer) > 0 {
+		// Select peers to query the missing sidecars from.
+		indicesByRootByPeerToQuery, err := selectPeers(params, randomSource, len(missingIndicesByRoot), indicesByRootByPeer)
+		if err != nil {
+			return nil, errors.Wrap(err, "select peers")
+		}
+
+		// Remove selected peers from the maps.
+		for peer := range indicesByRootByPeerToQuery {
+			delete(connectedPeers, peer)
+		}
+
+		// Fetch the sidecars from the chosen peers.
+		roDataColumnsByPeer := fetchDataColumnSidecarsFromPeers(params, slotByRoot, slotsWithCommitments, indicesByRootByPeerToQuery)
+
+		// Verify the received data column sidecars.
+		verifiedRoDataColumnSidecars, err := verifyDataColumnSidecarsByPeer(params.P2P, params.NewVerifier, roDataColumnsByPeer)
+		if err != nil {
+			return nil, errors.Wrap(err, "verify data columns sidecars by peer")
+		}
+
+		// Remove the verified sidecars from the missing indices map and compute the new verified columns by root.
+		localVerifiedColumnsByRoot := updateResults(verifiedRoDataColumnSidecars, missingIndicesByRoot)
+		for root, verifiedRoDataColumns := range localVerifiedColumnsByRoot {
+			verifiedColumnsByRoot[root] = append(verifiedColumnsByRoot[root], verifiedRoDataColumns...)
+		}
+
+		// Compute indices by root by peers with the updated missing indices and connected peers.
+		indicesByRootByPeer, err = computeIndicesByRootByPeer(params.P2P, slotByRoot, missingIndicesByRoot, connectedPeers)
+		if err != nil {
+			return nil, errors.Wrap(err, "explore peers")
+		}
+	}
+
+	log.WithFields(logrus.Fields{
+		"duration":            time.Since(start),
+		"initialMissingCount": initialMissingCount,
+		"finalMissingCount":   computeTotalCount(missingIndicesByRoot),
+	}).Debug("Requested direct data column sidecars from peers")
+
+	return verifiedColumnsByRoot, nil
+}
+
+// requestIndirectSidecarsFromPeers requests, for all roots in `missingIndicesbyRootOrig`,
+// for all possible peers, taking into account sidecars available in `inputs` and in the storage,
+// all possible sidecars until either, for each root:
+// - all indices in `indices` are available, or
+// - enough sidecars are available to trigger a reconstruction, or
+// - all peers are exhausted.
+func requestIndirectSidecarsFromPeers(
+	p DataColumnSidecarsParams,
+	slotByRoot map[[fieldparams.RootLength]byte]primitives.Slot,
+	slotsWithCommitments map[primitives.Slot]bool,
+	storedIndicesByRoot map[[fieldparams.RootLength]byte]map[uint64]bool,
+	alreadyAvailableByRoot map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn,
+	requestedIndices map[uint64]bool,
+	roots map[[fieldparams.RootLength]byte]bool,
+) (map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, error) {
+	start := time.Now()
+
+	numberOfColumns := params.BeaconConfig().NumberOfColumns
+	minimumColumnCountToReconstruct := peerdas.MinimumColumnCountToReconstruct()
+
+	// Create a new random source for peer selection.
+	randomSource := rand.NewGenerator()
+
+	// For each root compute all possible data column sidecar indices excluding
+	// those already stored or already available.
+	indicesToRetrieveByRoot := make(map[[fieldparams.RootLength]byte]map[uint64]bool)
+	for root := range roots {
+		alreadyAvailableIndices := make(map[uint64]bool, len(alreadyAvailableByRoot[root]))
+		for _, sidecar := range alreadyAvailableByRoot[root] {
+			alreadyAvailableIndices[sidecar.Index] = true
+		}
+
+		storedIndices := storedIndicesByRoot[root]
+		indicesToRetrieve := make(map[uint64]bool, numberOfColumns)
+		for index := range numberOfColumns {
+			if !(storedIndices[index] || alreadyAvailableIndices[index]) {
+				indicesToRetrieve[index] = true
+			}
+		}
+
+		if len(indicesToRetrieve) > 0 {
+			indicesToRetrieveByRoot[root] = indicesToRetrieve
+		}
+	}
+
+	initialToRetrieveRootCount := len(indicesToRetrieveByRoot)
 
 	// Determine all sidecars each peers are expected to custody.
 	connectedPeersSlice := p.P2P.Peers().Connected()
@@ -273,15 +369,22 @@ func tryRequestingColumnsFromPeers(
 		connectedPeers[peer] = true
 	}
 
-	indicesByRootByPeer, err := computeIndicesByRootByPeer(p.P2P, slotByRoot, missingIndicesByRoot, connectedPeers)
+	// Compute which peers have which of the missing indices.
+	indicesByRootByPeer, err := computeIndicesByRootByPeer(p.P2P, slotByRoot, indicesToRetrieveByRoot, connectedPeers)
 	if err != nil {
 		return nil, errors.Wrap(err, "explore peers")
 	}
 
-	verifiedColumnsByRoot := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn)
-	for len(missingIndicesByRoot) > 0 && len(indicesByRootByPeer) > 0 {
+	// Already add into results all sidecars present in `alreadyAvailableByRoot`.
+	result := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn)
+	for root := range roots {
+		alreadyAvailable := alreadyAvailableByRoot[root]
+		result[root] = append(result[root], alreadyAvailable...)
+	}
+
+	for len(indicesToRetrieveByRoot) > 0 && len(indicesByRootByPeer) > 0 {
 		// Select peers to query the missing sidecars from.
-		indicesByRootByPeerToQuery, err := selectPeers(p, randomSource, len(missingIndicesByRoot), indicesByRootByPeer)
+		indicesByRootByPeerToQuery, err := selectPeers(p, randomSource, len(indicesToRetrieveByRoot), indicesByRootByPeer)
 		if err != nil {
 			return nil, errors.Wrap(err, "select peers")
 		}
@@ -300,82 +403,216 @@ func tryRequestingColumnsFromPeers(
 			return nil, errors.Wrap(err, "verify data columns sidecars by peer")
 		}
 
-		// Remove the verified sidecars from the missing indices map and compute the new verified columns by root.
-		localVerifiedColumnsByRoot := updateResults(verifiedRoDataColumnSidecars, missingIndicesByRoot)
+		// Add to results all verified sidecars.
+		localVerifiedColumnsByRoot := updateResults(verifiedRoDataColumnSidecars, indicesToRetrieveByRoot)
 		for root, verifiedRoDataColumns := range localVerifiedColumnsByRoot {
-			verifiedColumnsByRoot[root] = append(verifiedColumnsByRoot[root], verifiedRoDataColumns...)
+			result[root] = append(result[root], verifiedRoDataColumns...)
+		}
+
+		// Unlabel a root as to retrieve if enough sidecars are retrieved to enable a reconstruction,
+		// or if all requested sidecars are now available for this root.
+		for root, indicesToRetrieve := range indicesToRetrieveByRoot {
+			storedIndices := storedIndicesByRoot[root]
+			storedCount := uint64(len(storedIndices))
+			resultCount := uint64(len(result[root]))
+
+			if storedCount+resultCount >= minimumColumnCountToReconstruct {
+				delete(indicesToRetrieveByRoot, root)
+				continue
+			}
+
+			allRequestedIndicesAvailable := true
+			for index := range requestedIndices {
+				if indicesToRetrieve[index] {
+					// Still need this index.
+					allRequestedIndicesAvailable = false
+					break
+				}
+			}
+
+			if allRequestedIndicesAvailable {
+				delete(indicesToRetrieveByRoot, root)
+			}
 		}
 
 		// Compute indices by root by peers with the updated missing indices and connected peers.
-		indicesByRootByPeer, err = computeIndicesByRootByPeer(p.P2P, slotByRoot, missingIndicesByRoot, connectedPeers)
+		indicesByRootByPeer, err = computeIndicesByRootByPeer(p.P2P, slotByRoot, indicesToRetrieveByRoot, connectedPeers)
 		if err != nil {
 			return nil, errors.Wrap(err, "explore peers")
 		}
 	}
 
-	return verifiedColumnsByRoot, nil
-}
-
-// tryReconstructFromStorageAndPeers attempts to reconstruct missing data column sidecars
-// using the data available in the storage and the data fetched from peers.
-// If, for at least one root, the reconstruction is not possible, an error is returned.
-func tryReconstructFromStorageAndPeers(
-	storage filesystem.DataColumnStorageReader,
-	fromPeersByRoot map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn,
-	indices map[uint64]bool,
-	missingIndicesByRoot map[[fieldparams.RootLength]byte]map[uint64]bool,
-) (map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, error) {
-	if len(missingIndicesByRoot) == 0 {
-		// Nothing to do, return early.
-		return nil, nil
-	}
-
-	minimumColumnsCountToReconstruct := peerdas.MinimumColumnCountToReconstruct()
-
-	start := time.Now()
-	result := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, len(missingIndicesByRoot))
-	for root := range missingIndicesByRoot {
-		// Check if a reconstruction is possible based on what we have from the store and fetched from peers.
-		summary := storage.Summary(root)
-		storedCount := summary.Count()
-		fetchedCount := uint64(len(fromPeersByRoot[root]))
-
-		if storedCount+fetchedCount < minimumColumnsCountToReconstruct {
-			return nil, errors.Errorf("cannot reconstruct all needed columns for root %#x. stored: %d, fetched: %d, minimum: %d", root, storedCount, fetchedCount, minimumColumnsCountToReconstruct)
-		}
-
-		// Load all we have in the store.
-		storedSidecars, err := storage.Get(root, nil)
-		if err != nil {
-			return nil, errors.Wrapf(err, "failed to get stored sidecars for root %#x", root)
-		}
-
-		sidecars := make([]blocks.VerifiedRODataColumn, 0, storedCount+fetchedCount)
-		sidecars = append(sidecars, storedSidecars...)
-		sidecars = append(sidecars, fromPeersByRoot[root]...)
-
-		// Attempt reconstruction.
-		reconstructedSidecars, err := peerdas.ReconstructDataColumnSidecars(sidecars)
-		if err != nil {
-			return nil, errors.Wrapf(err, "failed to reconstruct data columns for root %#x", root)
-		}
-
-		// Select only sidecars we need.
-		for _, sidecar := range reconstructedSidecars {
-			if indices[sidecar.Index] {
-				result[root] = append(result[root], sidecar)
-			}
-		}
-	}
-
 	log.WithFields(logrus.Fields{
-		"rootCount": len(missingIndicesByRoot),
-		"elapsed":   time.Since(start),
-	}).Debug("Reconstructed from storage and peers")
+		"duration":                   time.Since(start),
+		"initialToRetrieveRootCount": initialToRetrieveRootCount,
+		"finalToRetrieveRootCount":   len(indicesToRetrieveByRoot),
+	}).Debug("Requested all data column sidecars from peers")
 
 	return result, nil
 }
 
+// mergeAvailableSidecars retrieves missing data column sidecars by combining
+// what is available in storage with the sidecars provided in `alreadyAvailableByRoot`,
+// reconstructing them when necessary.
+//
+// The function works in two modes depending on sidecar availability:
+//   - If all requested sidecars are already available (no reconstruction needed),
+//     it simply returns them directly from storage and inputs.
+//   - If storage + inputs together provide enough sidecars to reconstruct all requested ones,
+//     it reconstructs and returns the requested sidecars.
+//
+// If a root cannot yield all requested sidecars, that root is omitted from the result.
+//
+// Note: It is assumed that no sidecar in `alreadyAvailableByRoot` is already present in storage.
+//
+// WARNING: This function mutates `roots`, removing any block roots
+// for which all requested sidecars were successfully retrieved.
+func mergeAvailableSidecars(
+	storage filesystem.DataColumnStorageReader,
+	requestedIndices map[uint64]bool,
+	storedIndicesByRoot map[[fieldparams.RootLength]byte]map[uint64]bool,
+	roots map[[fieldparams.RootLength]byte]bool,
+	alreadyAvailableByRoot map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn,
+) (map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, error) {
+	minimumColumnsCountToReconstruct := peerdas.MinimumColumnCountToReconstruct()
+
+	result := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, len(roots))
+	for root := range roots {
+		storedIndices := storedIndicesByRoot[root]
+		alreadyAvailable := alreadyAvailableByRoot[root]
+
+		// Compute already available indices.
+		alreadyAvailableIndices := make(map[uint64]bool, len(alreadyAvailable))
+		for _, sidecar := range alreadyAvailable {
+			alreadyAvailableIndices[sidecar.Index] = true
+		}
+
+		// Check if reconstruction is needed.
+		isReconstructionNeeded := false
+		for index := range requestedIndices {
+			if !(storedIndices[index] || alreadyAvailableIndices[index]) {
+				isReconstructionNeeded = true
+				break
+			}
+		}
+
+		// Check if reconstruction is possible.
+		storedCount := uint64(len(storedIndices))
+		alreadyAvailableCount := uint64(len(alreadyAvailableIndices))
+		isReconstructionPossible := storedCount+alreadyAvailableCount >= minimumColumnsCountToReconstruct
+
+		// Skip if the reconstruction is needed and not possible.
+		if isReconstructionNeeded && !isReconstructionPossible {
+			continue
+		}
+
+		// Reconstruct if reconstruction is needed and possible.
+		if isReconstructionNeeded && isReconstructionPossible {
+			// Load all we have in the store.
+			stored, err := storage.Get(root, nil)
+			if err != nil {
+				return nil, errors.Wrapf(err, "storage get for root %#x", root)
+			}
+
+			allAvailable := make([]blocks.VerifiedRODataColumn, 0, storedCount+alreadyAvailableCount)
+			allAvailable = append(allAvailable, stored...)
+			allAvailable = append(allAvailable, alreadyAvailable...)
+
+			// Attempt reconstruction.
+			reconstructedSidecars, err := peerdas.ReconstructDataColumnSidecars(allAvailable)
+			if err != nil {
+				return nil, errors.Wrapf(err, "reconstruct data column sidecars for root %#x", root)
+			}
+
+			// Select only sidecars we need.
+			for _, sidecar := range reconstructedSidecars {
+				if requestedIndices[sidecar.Index] {
+					result[root] = append(result[root], sidecar)
+				}
+			}
+
+			delete(roots, root)
+			continue
+		}
+
+		// Reconstruction is not needed, simply assemble what is available in storage and already available.
+		allAvailable, err := assembleAvailableSidecarsForRoot(storage, alreadyAvailableByRoot, root, requestedIndices)
+		if err != nil {
+			return nil, errors.Wrap(err, "assemble available sidecars")
+		}
+
+		result[root] = allAvailable
+		delete(roots, root)
+	}
+
+	return result, nil
+}
+
+// assembleAvailableSidecars assembles all sidecars available in storage
+// and in `alreadyAvailableByRoot` corresponding to `roots`.
+// It also returns all missing indices by root.
+func assembleAvailableSidecars(
+	storage filesystem.DataColumnStorageReader,
+	requestedIndices map[uint64]bool,
+	roots map[[fieldparams.RootLength]byte]bool,
+	alreadyAvailableByRoot map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn,
+) (map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, map[[fieldparams.RootLength]byte]map[uint64]bool, error) {
+	// Assemble results.
+	result := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn, len(roots))
+	for root := range roots {
+		allAvailable, err := assembleAvailableSidecarsForRoot(storage, alreadyAvailableByRoot, root, requestedIndices)
+		if err != nil {
+			return nil, nil, errors.Wrap(err, "assemble sidecars for root")
+		}
+
+		if len(allAvailable) > 0 {
+			result[root] = allAvailable
+		}
+	}
+
+	// Compute still missing sidecars.
+	missingByRoot := make(map[[fieldparams.RootLength]byte]map[uint64]bool, len(roots))
+	for root := range roots {
+		missing := make(map[uint64]bool, len(requestedIndices))
+		for index := range requestedIndices {
+			missing[index] = true
+		}
+
+		allAvailable := result[root]
+		for _, sidecar := range allAvailable {
+			delete(missing, sidecar.Index)
+		}
+
+		if len(missing) > 0 {
+			missingByRoot[root] = missing
+		}
+	}
+
+	return result, missingByRoot, nil
+}
+
+// assembleAvailableSidecarsForRoot assembles all sidecars available in storage
+// and in `alreadyAvailableByRoot` corresponding to `root` and `indices`.
+func assembleAvailableSidecarsForRoot(
+	storage filesystem.DataColumnStorageReader,
+	alreadyAvailableByRoot map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn,
+	root [fieldparams.RootLength]byte,
+	indices map[uint64]bool,
+) ([]blocks.VerifiedRODataColumn, error) {
+	stored, err := storage.Get(root, sortedSliceFromMap(indices))
+	if err != nil {
+		return nil, errors.Wrapf(err, "storage get for root %#x", root)
+	}
+
+	alreadyAvailable := alreadyAvailableByRoot[root]
+
+	allAvailable := make([]blocks.VerifiedRODataColumn, 0, len(stored)+len(alreadyAvailable))
+	allAvailable = append(allAvailable, stored...)
+	allAvailable = append(allAvailable, alreadyAvailable...)
+
+	return allAvailable, nil
+}
+
 // selectPeers selects peers to query the sidecars.
 // It begins by randomly selecting a peer in `origIndicesByRootByPeer` that has enough bandwidth,
 // and assigns to it all its available sidecars. Then, it randomly select an other peer, until
@@ -450,7 +687,6 @@ func updateResults(
 	verifiedSidecars []blocks.VerifiedRODataColumn,
 	missingIndicesByRoot map[[fieldparams.RootLength]byte]map[uint64]bool,
 ) map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn {
-	// Copy the original map to avoid modifying it directly.
 	verifiedSidecarsByRoot := make(map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn)
 	for _, verifiedSidecar := range verifiedSidecars {
 		blockRoot := verifiedSidecar.BlockRoot()
@@ -566,11 +802,23 @@ func sendDataColumnSidecarsRequest(
 			roDataColumns = append(roDataColumns, localRoDataColumns...)
 		}
 
+		prettyByRangeRequests := make([]map[string]any, 0, len(byRangeRequests))
+		for _, request := range byRangeRequests {
+			prettyRequest := map[string]any{
+				"startSlot": request.StartSlot,
+				"count":     request.Count,
+				"columns":   request.Columns,
+			}
+
+			prettyByRangeRequests = append(prettyByRangeRequests, prettyRequest)
+		}
+
 		log.WithFields(logrus.Fields{
 			"respondedSidecars": len(roDataColumns),
-			"requests":          len(byRangeRequests),
+			"requestCount":      len(byRangeRequests),
 			"type":              "byRange",
 			"duration":          time.Since(start),
+			"requests":          prettyByRangeRequests,
 		}).Debug("Received data column sidecars")
 
 		return roDataColumns, nil
@@ -766,6 +1014,8 @@ func computeIndicesByRootByPeer(
 	indicesByBlockRoot map[[fieldparams.RootLength]byte]map[uint64]bool,
 	peers map[goPeer.ID]bool,
 ) (map[goPeer.ID]map[[fieldparams.RootLength]byte]map[uint64]bool, error) {
+	slotsPerEpoch := params.BeaconConfig().SlotsPerEpoch
+
 	// First, compute custody columns for all peers
 	peersByIndex := make(map[uint64]map[goPeer.ID]bool)
 	headSlotByPeer := make(map[goPeer.ID]primitives.Slot)
@@ -800,7 +1050,10 @@ func computeIndicesByRootByPeer(
 			return nil, errors.Errorf("chain state is nil for peer %s", peer)
 		}
 
-		headSlotByPeer[peer] = peerChainState.HeadSlot
+		// Our view of the head slot of a peer is not updated in real time.
+		// We add an epoch to take into account the fact the real head slot of the peer
+		// is higher than our view of it.
+		headSlotByPeer[peer] = peerChainState.HeadSlot + slotsPerEpoch
 	}
 
 	// For each block root and its indices, find suitable peers
@@ -931,15 +1184,6 @@ func sortedSliceFromMap(m map[uint64]bool) []uint64 {
 	return result
 }
 
-// computeSlotByBlockRoot maps each block root to its corresponding slot.
-func computeSlotByBlockRoot(roBlocks []blocks.ROBlock) map[[fieldparams.RootLength]byte]primitives.Slot {
-	slotByBlockRoot := make(map[[fieldparams.RootLength]byte]primitives.Slot, len(roBlocks))
-	for _, roBlock := range roBlocks {
-		slotByBlockRoot[roBlock.Root()] = roBlock.Block().Slot()
-	}
-	return slotByBlockRoot
-}
-
 // computeTotalCount calculates the total count of indices across all roots.
 func computeTotalCount(input map[[fieldparams.RootLength]byte]map[uint64]bool) int {
 	totalCount := 0

beacon-chain/sync/data_column_sidecars_test.go

@@ -20,8 +20,10 @@ import (
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/wrapper"
 	leakybucket "github.com/OffchainLabs/prysm/v6/container/leaky-bucket"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
+	pb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v6/testing/assert"
 	"github.com/OffchainLabs/prysm/v6/testing/require"
 	"github.com/OffchainLabs/prysm/v6/testing/util"
@@ -33,11 +35,13 @@ import (
 
 func TestFetchDataColumnSidecars(t *testing.T) {
 	numberOfColumns := params.BeaconConfig().NumberOfColumns
-	// Slot 1: All needed sidecars are available in storage
-	// Slot 2: No commitment
-	// Slot 3: All sidecars are saved excepted the needed ones
-	// Slot 4: Some sidecars are in the storage, other have to be retrieved from peers.
-	// Slot 5: Some sidecars are in the storage, other have to be retrieved from peers but peers do not deliver all requested sidecars.
+	// Slot 1: All needed sidecars are available in storage ==> Retrieval from storage only.
+	// Slot 2: No commitment ==> Nothing to do.
+	// Slot 3: Some sidecars are in the storage, other have to be retrieved from peers ==> Retrieval from storage and peers.
+	// Slot 4: Some sidecars are in the storage, other have to be retrieved from peers but peers do not deliver all requested sidecars ==> Retrieval from storage and peers then reconstruction.
+	// Slot 5: Some sidecars are in the storage, other have to be retrieved from peers ==> Retrieval from storage and peers but peers do not respond all needed on first attempt and respond needed sidecars on second attempt ==> Retrieval from storage and peers.
+	// Slot 6: Some sidecars are in the storage, other have to be retrieved from peers ==> Retrieval from storage and peers but peers do not respond all needed on first attempt and respond not needed sidecars on second attempt ==> Retrieval from storage and peers then reconstruction.
+	// Slot 7: Some sidecars are in the storage, other have to be retrieved from peers but peers do not send anything ==> Still missing.
 
 	params.SetupTestConfigCleanup(t)
 	cfg := params.BeaconConfig().Copy()
@@ -75,67 +79,74 @@ func TestFetchDataColumnSidecars(t *testing.T) {
 	// Block 3
 	block3, _, verifiedSidecars3 := util.GenerateTestFuluBlockWithSidecars(t, blobCount, util.WithSlot(3))
 	root3 := block3.Root()
-
-	toStore3 := make([]blocks.VerifiedRODataColumn, 0, numberOfColumns-uint64(len(indices)))
-	for i := range numberOfColumns {
-		if !indices[i] {
-			sidecar := verifiedSidecars3[i]
-			toStore3 = append(toStore3, sidecar)
-		}
-	}
+	toStore3 := []blocks.VerifiedRODataColumn{verifiedSidecars3[106]}
 
 	err = storage.Save(toStore3)
 	require.NoError(t, err)
 
 	// Block 4
+	minimumColumnsCountToReconstruct := peerdas.MinimumColumnCountToReconstruct()
 	block4, _, verifiedSidecars4 := util.GenerateTestFuluBlockWithSidecars(t, blobCount, util.WithSlot(4))
 	root4 := block4.Root()
-	toStore4 := []blocks.VerifiedRODataColumn{verifiedSidecars4[106]}
+
+	toStoreCount := minimumColumnsCountToReconstruct - 1
+	toStore4 := make([]blocks.VerifiedRODataColumn, 0, toStoreCount)
+
+	for i := uint64(0); uint64(len(toStore4)) < toStoreCount; i++ {
+		sidecar := verifiedSidecars4[minimumColumnsCountToReconstruct+i]
+		if sidecar.Index == 81 {
+			continue
+		}
+
+		toStore4 = append(toStore4, sidecar)
+	}
 
 	err = storage.Save(toStore4)
 	require.NoError(t, err)
 
 	// Block 5
-	minimumColumnsCountToReconstruct := peerdas.MinimumColumnCountToReconstruct()
 	block5, _, verifiedSidecars5 := util.GenerateTestFuluBlockWithSidecars(t, blobCount, util.WithSlot(5))
 	root5 := block5.Root()
-
-	toStoreCount := minimumColumnsCountToReconstruct - 1
-	toStore5 := make([]blocks.VerifiedRODataColumn, 0, toStoreCount)
-
-	for i := uint64(0); uint64(len(toStore5)) < toStoreCount; i++ {
-		sidecar := verifiedSidecars5[minimumColumnsCountToReconstruct+i]
-		if sidecar.Index == 81 {
-			continue
-		}
-
-		toStore5 = append(toStore5, sidecar)
-	}
+	toStore5 := []blocks.VerifiedRODataColumn{verifiedSidecars5[106]}
 
 	err = storage.Save(toStore5)
 	require.NoError(t, err)
 
-	// Custody columns with this private key and 4-cgc: 31, 81, 97, 105
-	privateKeyBytes := [32]byte{1}
-	privateKey, err := crypto.UnmarshalSecp256k1PrivateKey(privateKeyBytes[:])
+	// Block 6
+	block6, _, verifiedSidecars6 := util.GenerateTestFuluBlockWithSidecars(t, blobCount, util.WithSlot(6))
+	root6 := block6.Root()
+	toStore6 := []blocks.VerifiedRODataColumn{verifiedSidecars6[106]}
+
+	err = storage.Save(toStore6)
+	require.NoError(t, err)
+
+	// Block 7
+	block7, _, verifiedSidecars7 := util.GenerateTestFuluBlockWithSidecars(t, blobCount, util.WithSlot(7))
+	root7 := block7.Root()
+	toStore7 := []blocks.VerifiedRODataColumn{verifiedSidecars7[106]}
+
+	err = storage.Save(toStore7)
 	require.NoError(t, err)
 
 	// Peers
-	protocol := fmt.Sprintf("%s/ssz_snappy", p2p.RPCDataColumnSidecarsByRangeTopicV1)
+	byRangeProtocol := fmt.Sprintf("%s/ssz_snappy", p2p.RPCDataColumnSidecarsByRangeTopicV1)
+	byRootProtocol := fmt.Sprintf("%s/ssz_snappy", p2p.RPCDataColumnSidecarsByRootTopicV1)
+
+	privateKeyBytes := [32]byte{1}
+	privateKey, err := crypto.UnmarshalSecp256k1PrivateKey(privateKeyBytes[:])
+	require.NoError(t, err)
 
 	p2p, other := testp2p.NewTestP2P(t), testp2p.NewTestP2P(t, libp2p.Identity(privateKey))
 	p2p.Peers().SetConnectionState(other.PeerID(), peers.Connected)
 	p2p.Connect(other)
 
 	p2p.Peers().SetChainState(other.PeerID(), &ethpb.StatusV2{
-		HeadSlot: 5,
+		HeadSlot: 8,
 	})
 
-	expectedRequest := &ethpb.DataColumnSidecarsByRangeRequest{
-		StartSlot: 4,
-		Count:     2,
-		Columns:   []uint64{31, 81},
-	}
+	p2p.Peers().SetMetadata(other.PeerID(), wrapper.WrappedMetadataV2(&pb.MetaDataV2{
+		CustodyGroupCount: 128,
+	}))
 
 	clock := startup.NewClock(time.Now(), [fieldparams.RootLength]byte{})
 
@@ -149,21 +160,82 @@ func TestFetchDataColumnSidecars(t *testing.T) {
 
 	newDataColumnsVerifier := newDataColumnsVerifierFromInitializer(initializer)
 
-	other.SetStreamHandler(protocol, func(stream network.Stream) {
+	other.SetStreamHandler(byRangeProtocol, func(stream network.Stream) {
+		expectedRequest := &ethpb.DataColumnSidecarsByRangeRequest{
+			StartSlot: 3,
+			Count:     5,
+			Columns:   []uint64{31, 81},
+		}
+
 		actualRequest := new(ethpb.DataColumnSidecarsByRangeRequest)
 		err := other.Encoding().DecodeWithMaxLength(stream, actualRequest)
 		assert.NoError(t, err)
 		assert.DeepEqual(t, expectedRequest, actualRequest)
 
-		err = WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedSidecars4[31].DataColumnSidecar)
+		err = WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedSidecars3[31].DataColumnSidecar)
+		assert.NoError(t, err)
+
+		err = WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedSidecars3[81].DataColumnSidecar)
 		assert.NoError(t, err)
 
 		err = WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedSidecars4[81].DataColumnSidecar)
 		assert.NoError(t, err)
 
+		err = WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedSidecars5[31].DataColumnSidecar)
+		assert.NoError(t, err)
+
+		err = WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedSidecars6[31].DataColumnSidecar)
+		assert.NoError(t, err)
+
+		err = stream.CloseWrite()
+		assert.NoError(t, err)
+	})
+
+	other.SetStreamHandler(byRootProtocol, func(stream network.Stream) {
+		allBut31And81And106 := make([]uint64, 0, numberOfColumns-3)
+		allBut31And106 := make([]uint64, 0, numberOfColumns-2)
+		allBut106 := make([]uint64, 0, numberOfColumns-1)
+		for i := range numberOfColumns {
+			if !map[uint64]bool{31: true, 81: true, 106: true}[i] {
+				allBut31And81And106 = append(allBut31And81And106, i)
+			}
+			if !map[uint64]bool{31: true, 106: true}[i] {
+				allBut31And106 = append(allBut31And106, i)
+			}
+
+			if i != 106 {
+				allBut106 = append(allBut106, i)
+			}
+		}
+
+		expectedRequest := &p2ptypes.DataColumnsByRootIdentifiers{
+			{
+				BlockRoot: root7[:],
+				Columns:   allBut106,
+			},
+			{
+				BlockRoot: root5[:],
+				Columns:   allBut31And106,
+			},
+			{
+				BlockRoot: root6[:],
+				Columns:   allBut31And106,
+			},
+		}
+
+		actualRequest := new(p2ptypes.DataColumnsByRootIdentifiers)
+		err := other.Encoding().DecodeWithMaxLength(stream, actualRequest)
+		assert.NoError(t, err)
+		assert.DeepEqual(t, expectedRequest, actualRequest)
+
 		err = WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedSidecars5[81].DataColumnSidecar)
 		assert.NoError(t, err)
 
+		for _, index := range allBut31And81And106 {
+			err = WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedSidecars6[index].DataColumnSidecar)
+			assert.NoError(t, err)
+		}
+
 		err = stream.CloseWrite()
 		assert.NoError(t, err)
 	})
@@ -178,51 +250,39 @@ func TestFetchDataColumnSidecars(t *testing.T) {
 		NewVerifier: newDataColumnsVerifier,
 	}
 
-	expected := map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn{
+	expectedResult := map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn{
 		root1: {verifiedSidecars1[31], verifiedSidecars1[81], verifiedSidecars1[106]},
 		// no root2 (no commitments in this block)
-		root3: {verifiedSidecars3[31], verifiedSidecars3[81], verifiedSidecars3[106]},
+		root3: {verifiedSidecars3[106], verifiedSidecars3[31], verifiedSidecars3[81]},
 		root4: {verifiedSidecars4[31], verifiedSidecars4[81], verifiedSidecars4[106]},
-		root5: {verifiedSidecars5[31], verifiedSidecars5[81], verifiedSidecars5[106]},
+		root5: {verifiedSidecars5[106], verifiedSidecars5[31], verifiedSidecars5[81]},
+		root6: {verifiedSidecars6[31], verifiedSidecars6[81], verifiedSidecars6[106]},
+		root7: {verifiedSidecars7[106]},
 	}
 
-	blocks := []blocks.ROBlock{block1, block2, block3, block4, block5}
-	actual, err := FetchDataColumnSidecars(params, blocks, indices)
+	expectedMissingIndicesBYRoots := map[[fieldparams.RootLength]byte]map[uint64]bool{
+		root7: {31: true, 81: true},
+	}
+
+	blocks := []blocks.ROBlock{block1, block2, block3, block4, block5, block6, block7}
+	actualResult, actualMissingRoots, err := FetchDataColumnSidecars(params, blocks, indices)
 	require.NoError(t, err)
 
-	require.Equal(t, len(expected), len(actual))
-	for root := range expected {
-		require.Equal(t, len(expected[root]), len(actual[root]))
-		for i := range expected[root] {
-			require.DeepSSZEqual(t, expected[root][i], actual[root][i])
+	require.Equal(t, len(expectedResult), len(actualResult))
+	for root := range expectedResult {
+		require.Equal(t, len(expectedResult[root]), len(actualResult[root]))
+		for i := range expectedResult[root] {
+			require.DeepSSZEqual(t, expectedResult[root][i], actualResult[root][i])
 		}
 	}
-}
 
-func TestCategorizeIndices(t *testing.T) {
-	storage := filesystem.NewEphemeralDataColumnStorage(t)
-
-	_, verifiedRoSidecars := util.CreateTestVerifiedRoDataColumnSidecars(t, []util.DataColumnParam{
-		{Slot: 1, Index: 12, Column: [][]byte{{1}, {2}, {3}}},
-		{Slot: 1, Index: 14, Column: [][]byte{{1}, {2}, {3}}},
-	})
-
-	err := storage.Save(verifiedRoSidecars)
-	require.NoError(t, err)
-
-	expectedToQuery := map[uint64]bool{13: true}
-	expectedStored := map[uint64]bool{12: true, 14: true}
-
-	actualToQuery, actualStored := categorizeIndices(storage, verifiedRoSidecars[0].BlockRoot(), []uint64{12, 13, 14})
-
-	require.Equal(t, len(expectedToQuery), len(actualToQuery))
-	require.Equal(t, len(expectedStored), len(actualStored))
-
-	for index := range expectedToQuery {
-		require.Equal(t, true, actualToQuery[index])
-	}
-	for index := range expectedStored {
-		require.Equal(t, true, actualStored[index])
+	require.Equal(t, len(expectedMissingIndicesBYRoots), len(actualMissingRoots))
+	for root, expectedMissingIndices := range expectedMissingIndicesBYRoots {
+		actualMissingIndices := actualMissingRoots[root]
+		require.Equal(t, len(expectedMissingIndices), len(actualMissingIndices))
+		for index := range expectedMissingIndices {
+			require.Equal(t, true, actualMissingIndices[index])
+		}
 	}
 }
 
@@ -841,6 +901,7 @@ func TestComputeIndicesByRootByPeer(t *testing.T) {
 			[fieldparams.RootLength]byte{3}: {38: true},
 		},
 		peerIDs[3]: {
+			[fieldparams.RootLength]byte{2}: {10: true},
 			[fieldparams.RootLength]byte{3}: {10: true},
 		},
 	}
@@ -953,39 +1014,6 @@ func TestSlortedSliceFromMap(t *testing.T) {
 	require.DeepEqual(t, expected, actual)
 }
 
-func TestComputeSlotByBlockRoot(t *testing.T) {
-	const (
-		count      = 3
-		multiplier = 10
-	)
-
-	roBlocks := make([]blocks.ROBlock, 0, count)
-	for i := range count {
-		signedBlock := util.NewBeaconBlock()
-		signedBlock.Block.Slot = primitives.Slot(i).Mul(multiplier)
-		roSignedBlock, err := blocks.NewSignedBeaconBlock(signedBlock)
-		require.NoError(t, err)
-
-		roBlock, err := blocks.NewROBlockWithRoot(roSignedBlock, [fieldparams.RootLength]byte{byte(i)})
-		require.NoError(t, err)
-
-		roBlocks = append(roBlocks, roBlock)
-	}
-
-	expected := map[[fieldparams.RootLength]byte]primitives.Slot{
-		[fieldparams.RootLength]byte{0}: primitives.Slot(0),
-		[fieldparams.RootLength]byte{1}: primitives.Slot(10),
-		[fieldparams.RootLength]byte{2}: primitives.Slot(20),
-	}
-
-	actual := computeSlotByBlockRoot(roBlocks)
-
-	require.Equal(t, len(expected), len(actual))
-	for k, v := range expected {
-		require.Equal(t, v, actual[k])
-	}
-}
-
 func TestComputeTotalCount(t *testing.T) {
 	input := map[[fieldparams.RootLength]byte]map[uint64]bool{
 		[fieldparams.RootLength]byte{1}: {1: true, 3: true},

beacon-chain/sync/data_columns_reconstruct.go

@@ -3,220 +3,131 @@ package sync
 import (
 	"context"
 	"fmt"
-	"slices"
+	"sync"
 	"time"
 
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
-	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	"github.com/OffchainLabs/prysm/v6/time/slots"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
-const (
-	broadcastMissingDataColumnsTimeIntoSlotMin = 1 * time.Second
-	broadcastMissingDataColumnsSlack           = 2 * time.Second
-)
+// processDataColumnSidecarsFromReconstruction, after a random delay, attempts to reconstruct,
+// broadcast and receive missing data column sidecars for the given block root.
+// https:github.com/ethereum/consensus-specs/blob/master/specs/fulu/das-core.md#reconstruction-and-cross-seeding
+func (s *Service) processDataColumnSidecarsFromReconstruction(ctx context.Context, sidecar blocks.VerifiedRODataColumn) error {
+	key := fmt.Sprintf("%#x", sidecar.BlockRoot())
+	if _, err, _ := s.reconstructionSingleFlight.Do(key, func() (interface{}, error) {
+		var wg sync.WaitGroup
 
-// reconstructSaveBroadcastDataColumnSidecars reconstructs, if possible,
-// all data column sidecars. Then, it saves missing sidecars to the store.
-// After a delay, it broadcasts in the background not seen via gossip
-// (but reconstructed) sidecars.
-func (s *Service) reconstructSaveBroadcastDataColumnSidecars(
-	ctx context.Context,
-	slot primitives.Slot,
-	proposerIndex primitives.ValidatorIndex,
-	root [fieldparams.RootLength]byte,
-) error {
-	startTime := time.Now()
-	samplesPerSlot := params.BeaconConfig().SamplesPerSlot
+		root := sidecar.BlockRoot()
+		slot := sidecar.Slot()
+		proposerIndex := sidecar.ProposerIndex()
 
-	// Lock to prevent concurrent reconstructions.
-	s.reconstructionLock.Lock()
-	defer s.reconstructionLock.Unlock()
+		// Return early if reconstruction is not needed.
+		if !s.shouldReconstruct(root) {
+			return nil, nil
+		}
+
+		// Compute the slot start time.
+		slotStartTime, err := slots.StartTime(s.cfg.clock.GenesisTime(), slot)
+		if err != nil {
+			return nil, errors.Wrap(err, "failed to calculate slot start time")
+		}
+
+		// Randomly choose value before starting reconstruction.
+		timeIntoSlot := s.computeRandomDelay(slotStartTime)
+		broadcastTime := slotStartTime.Add(timeIntoSlot)
+		waitingTime := time.Until(broadcastTime)
+
+		wg.Add(1)
+		time.AfterFunc(waitingTime, func() {
+			defer wg.Done()
+
+			// Return early if the context was canceled during the waiting time.
+			if err := ctx.Err(); err != nil {
+				return
+			}
+
+			// Return early if reconstruction is not needed anymore.
+			if !s.shouldReconstruct(root) {
+				return
+			}
+
+			// Load all the stored data column sidecars for this root.
+			verifiedSidecars, err := s.cfg.dataColumnStorage.Get(root, nil)
+			if err != nil {
+				log.WithError(err).Error("Failed to get data column sidecars")
+				return
+			}
+
+			// Reconstruct all the data column sidecars.
+			startTime := time.Now()
+			reconstructedSidecars, err := peerdas.ReconstructDataColumnSidecars(verifiedSidecars)
+			if err != nil {
+				log.WithError(err).Error("Failed to reconstruct data column sidecars")
+				return
+			}
+
+			duration := time.Since(startTime)
+			dataColumnReconstructionHistogram.Observe(float64(duration.Milliseconds()))
+			dataColumnReconstructionCounter.Add(float64(len(reconstructedSidecars) - len(verifiedSidecars)))
+
+			// Retrieve indices of data column sidecars to sample.
+			columnIndicesToSample, err := s.columnIndicesToSample()
+			if err != nil {
+				log.WithError(err).Error("Failed to get column indices to sample")
+				return
+			}
+
+			unseenIndices, err := s.broadcastAndReceiveUnseenDataColumnSidecars(ctx, slot, proposerIndex, columnIndicesToSample, reconstructedSidecars)
+			if err != nil {
+				log.WithError(err).Error("Failed to broadcast and receive unseen data column sidecars")
+				return
+			}
+
+			if len(unseenIndices) > 0 {
+				log.WithFields(logrus.Fields{
+					"root":          fmt.Sprintf("%#x", root),
+					"slot":          slot,
+					"proposerIndex": proposerIndex,
+					"count":         len(unseenIndices),
+					"indices":       sortedSliceFromMap(unseenIndices),
+					"duration":      duration,
+				}).Debug("Reconstructed data column sidecars")
+			}
+		})
+
+		wg.Wait()
+		return nil, nil
+	}); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// shouldReconstruct returns true if we should attempt to reconstruct the data columns for the given block root.
+func (s *Service) shouldReconstruct(root [fieldparams.RootLength]byte) bool {
+	numberOfColumns := params.BeaconConfig().NumberOfColumns
 
 	// Get the columns we store.
 	storedDataColumns := s.cfg.dataColumnStorage.Summary(root)
 	storedColumnsCount := storedDataColumns.Count()
-	numberOfColumns := params.BeaconConfig().NumberOfColumns
 
-	// If reconstruction is not possible or if all columns are already stored, exit early.
-	if storedColumnsCount < peerdas.MinimumColumnCountToReconstruct() || storedColumnsCount == numberOfColumns {
-		return nil
-	}
-
-	// Retrieve our local node info.
-	nodeID := s.cfg.p2p.NodeID()
-	custodyGroupCount, err := s.cfg.p2p.CustodyGroupCount()
-	if err != nil {
-		return errors.Wrap(err, "custody group count")
-	}
-
-	samplingSize := max(custodyGroupCount, samplesPerSlot)
-	localNodeInfo, _, err := peerdas.Info(nodeID, samplingSize)
-	if err != nil {
-		return errors.Wrap(err, "peer info")
-	}
-
-	// Load all the possible data column sidecars, to minimize reconstruction time.
-	verifiedSidecars, err := s.cfg.dataColumnStorage.Get(root, nil)
-	if err != nil {
-		return errors.Wrap(err, "get data column sidecars")
-	}
-
-	// Reconstruct all the data column sidecars.
-	reconstructedSidecars, err := peerdas.ReconstructDataColumnSidecars(verifiedSidecars)
-	if err != nil {
-		return errors.Wrap(err, "reconstruct data column sidecars")
-	}
-
-	// Filter reconstructed sidecars to save.
-	custodyColumns := localNodeInfo.CustodyColumns
-	toSaveSidecars := make([]blocks.VerifiedRODataColumn, 0, len(custodyColumns))
-	for _, sidecar := range reconstructedSidecars {
-		if custodyColumns[sidecar.Index] {
-			toSaveSidecars = append(toSaveSidecars, sidecar)
-		}
-	}
-
-	// Save the data column sidecars to the database.
-	// Note: We do not call `receiveDataColumn`, because it will ignore
-	// incoming data columns via gossip while we did not broadcast (yet) the reconstructed data columns.
-	if err := s.cfg.dataColumnStorage.Save(toSaveSidecars); err != nil {
-		return errors.Wrap(err, "save data column sidecars")
-	}
-
-	slotStartTime, err := slots.StartTime(s.cfg.clock.GenesisTime(), slot)
-	if err != nil {
-		return errors.Wrap(err, "failed to calculate slot start time")
-	}
-	log.WithFields(logrus.Fields{
-		"root":                          fmt.Sprintf("%#x", root),
-		"slot":                          slot,
-		"fromColumnsCount":              storedColumnsCount,
-		"sinceSlotStartTime":            time.Since(slotStartTime),
-		"reconstructionAndSaveDuration": time.Since(startTime),
-	}).Debug("Data columns reconstructed and saved")
-
-	// Update reconstruction metrics.
-	dataColumnReconstructionHistogram.Observe(float64(time.Since(startTime).Milliseconds()))
-	dataColumnReconstructionCounter.Add(float64(len(reconstructedSidecars) - len(verifiedSidecars)))
-
-	// Schedule the broadcast.
-	if err := s.scheduleMissingDataColumnSidecarsBroadcast(ctx, root, proposerIndex, slot); err != nil {
-		return errors.Wrap(err, "schedule reconstructed data columns broadcast")
-	}
-
-	return nil
+	// Reconstruct only if we have at least the minimum number of columns to reconstruct, but not all the columns.
+	// (If we have not enough columns, reconstruction is impossible. If we have all the columns, reconstruction is unnecessary.)
+	return storedColumnsCount >= peerdas.MinimumColumnCountToReconstruct() && storedColumnsCount != numberOfColumns
 }
 
-// scheduleMissingDataColumnSidecarsBroadcast schedules the broadcast of missing
-// (aka. not seen via gossip but reconstructed) sidecars.
-func (s *Service) scheduleMissingDataColumnSidecarsBroadcast(
-	ctx context.Context,
-	root [fieldparams.RootLength]byte,
-	proposerIndex primitives.ValidatorIndex,
-	slot primitives.Slot,
-) error {
-	log := log.WithFields(logrus.Fields{
-		"root": fmt.Sprintf("%x", root),
-		"slot": slot,
-	})
+// computeRandomDelay computes a random delay duration to wait before reconstructing data column sidecars.
+func (s *Service) computeRandomDelay(slotStartTime time.Time) time.Duration {
+	const maxReconstructionDelaySec = 2.
 
-	// Get the time corresponding to the start of the slot.
-	genesisTime := s.cfg.clock.GenesisTime()
-	slotStartTime, err := slots.StartTime(genesisTime, slot)
-	if err != nil {
-		return errors.Wrap(err, "failed to calculate slot start time")
-	}
-
-	// Compute the waiting time. This could be negative. In such a case, broadcast immediately.
 	randFloat := s.reconstructionRandGen.Float64()
-	timeIntoSlot := broadcastMissingDataColumnsTimeIntoSlotMin + time.Duration(float64(broadcastMissingDataColumnsSlack)*randFloat)
-	broadcastTime := slotStartTime.Add(timeIntoSlot)
-	waitingTime := time.Until(broadcastTime)
-	time.AfterFunc(waitingTime, func() {
-		// Return early if the context was canceled during the waiting time.
-		if err := ctx.Err(); err != nil {
-			return
-		}
-
-		if err := s.broadcastMissingDataColumnSidecars(slot, proposerIndex, root, timeIntoSlot); err != nil {
-			log.WithError(err).Error("Failed to broadcast missing data column sidecars")
-		}
-	})
-
-	return nil
-}
-
-func (s *Service) broadcastMissingDataColumnSidecars(
-	slot primitives.Slot,
-	proposerIndex primitives.ValidatorIndex,
-	root [fieldparams.RootLength]byte,
-	timeIntoSlot time.Duration,
-) error {
-	// Get the node ID.
-	nodeID := s.cfg.p2p.NodeID()
-
-	// Retrieve the local node info.
-	custodyGroupCount, err := s.cfg.p2p.CustodyGroupCount()
-	if err != nil {
-		return errors.Wrap(err, "custody group count")
-	}
-
-	localNodeInfo, _, err := peerdas.Info(nodeID, custodyGroupCount)
-	if err != nil {
-		return errors.Wrap(err, "peerdas info")
-	}
-
-	// Compute the missing data columns (data columns we should custody but we did not received via gossip.)
-	missingColumns := make([]uint64, 0, len(localNodeInfo.CustodyColumns))
-	for column := range localNodeInfo.CustodyColumns {
-		if !s.hasSeenDataColumnIndex(slot, proposerIndex, column) {
-			missingColumns = append(missingColumns, column)
-		}
-	}
-
-	// Return early if there are no missing data columns.
-	if len(missingColumns) == 0 {
-		return nil
-	}
-
-	// Load from the store the non received but reconstructed data column.
-	verifiedRODataColumnSidecars, err := s.cfg.dataColumnStorage.Get(root, missingColumns)
-	if err != nil {
-		return errors.Wrap(err, "data column storage get")
-	}
-
-	broadcastedColumns := make([]uint64, 0, len(verifiedRODataColumnSidecars))
-	for _, verifiedRODataColumn := range verifiedRODataColumnSidecars {
-		broadcastedColumns = append(broadcastedColumns, verifiedRODataColumn.Index)
-		// Compute the subnet for this column.
-		subnet := peerdas.ComputeSubnetForDataColumnSidecar(verifiedRODataColumn.Index)
-
-		// Broadcast the missing data column.
-		if err := s.cfg.p2p.BroadcastDataColumnSidecar(root, subnet, verifiedRODataColumn.DataColumnSidecar); err != nil {
-			log.WithError(err).Error("Broadcast data column")
-		}
-
-		// Now, we can set the data column as seen.
-		s.setSeenDataColumnIndex(slot, proposerIndex, verifiedRODataColumn.Index)
-	}
-
-	if logrus.GetLevel() >= logrus.DebugLevel {
-		// Sort for nice logging.
-		slices.Sort(broadcastedColumns)
-		slices.Sort(missingColumns)
-
-		log.WithFields(logrus.Fields{
-			"timeIntoSlot":   timeIntoSlot,
-			"missingColumns": missingColumns,
-			"broadcasted":    broadcastedColumns,
-		}).Debug("Start broadcasting not seen via gossip but reconstructed data columns")
-	}
-
-	return nil
+	timeIntoSlot := time.Duration(maxReconstructionDelaySec * randFloat * float64(time.Second))
+	return timeIntoSlot
 }

beacon-chain/sync/data_columns_reconstruct_test.go

@@ -1,7 +1,11 @@
 package sync
 
 import (
+	"fmt"
 	"testing"
+	"time"
+
+	"math/rand"
 
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
 	mockChain "github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/testing"
@@ -9,12 +13,11 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	p2ptest "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	"github.com/OffchainLabs/prysm/v6/config/params"
-	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/testing/require"
 	"github.com/OffchainLabs/prysm/v6/testing/util"
 )
 
-func TestReconstructDataColumns(t *testing.T) {
+func TestProcessDataColumnSidecarsFromReconstruction(t *testing.T) {
 	const blobCount = 4
 	numberOfColumns := params.BeaconConfig().NumberOfColumns
 
@@ -27,9 +30,6 @@ func TestReconstructDataColumns(t *testing.T) {
 	roBlock, _, verifiedRoDataColumns := util.GenerateTestFuluBlockWithSidecars(t, blobCount)
 	require.Equal(t, numberOfColumns, uint64(len(verifiedRoDataColumns)))
 
-	root, block := roBlock.Root(), roBlock.Block()
-	slot, proposerIndex := block.Slot(), block.ProposerIndex()
-
 	minimumCount := peerdas.MinimumColumnCountToReconstruct()
 
 	t.Run("not enough stored sidecars", func(t *testing.T) {
@@ -38,7 +38,7 @@ func TestReconstructDataColumns(t *testing.T) {
 		require.NoError(t, err)
 
 		service := NewService(ctx, WithP2P(p2ptest.NewTestP2P(t)), WithDataColumnStorage(storage))
-		err = service.reconstructSaveBroadcastDataColumnSidecars(ctx, slot, proposerIndex, root)
+		err = service.processDataColumnSidecarsFromReconstruction(ctx, verifiedRoDataColumns[0])
 		require.NoError(t, err)
 	})
 
@@ -48,7 +48,7 @@ func TestReconstructDataColumns(t *testing.T) {
 		require.NoError(t, err)
 
 		service := NewService(ctx, WithP2P(p2ptest.NewTestP2P(t)), WithDataColumnStorage(storage))
-		err = service.reconstructSaveBroadcastDataColumnSidecars(ctx, slot, proposerIndex, root)
+		err = service.processDataColumnSidecarsFromReconstruction(ctx, verifiedRoDataColumns[0])
 		require.NoError(t, err)
 	})
 
@@ -60,19 +60,39 @@ func TestReconstructDataColumns(t *testing.T) {
 		// However, for the needs of this test, this is perfectly fine.
 		const cgc = 8
 
-		storage := filesystem.NewEphemeralDataColumnStorage(t)
-		minimumCount := peerdas.MinimumColumnCountToReconstruct()
-		err := storage.Save(verifiedRoDataColumns[:minimumCount])
 		require.NoError(t, err)
 
+		chainService := &mockChain.ChainService{}
+		p2p := p2ptest.NewTestP2P(t)
+		storage := filesystem.NewEphemeralDataColumnStorage(t)
+
 		service := NewService(
 			ctx,
-			WithP2P(p2ptest.NewTestP2P(t)),
+			WithP2P(p2p),
 			WithDataColumnStorage(storage),
-			WithChainService(&mockChain.ChainService{}),
+			WithChainService(chainService),
+			WithOperationNotifier(chainService.OperationNotifier()),
 		)
 
-		err = service.reconstructSaveBroadcastDataColumnSidecars(ctx, slot, proposerIndex, root)
+		minimumCount := peerdas.MinimumColumnCountToReconstruct()
+		receivedBeforeReconstruction := verifiedRoDataColumns[:minimumCount]
+
+		err = service.receiveDataColumnSidecars(ctx, receivedBeforeReconstruction)
+		require.NoError(t, err)
+
+		err = storage.Save(receivedBeforeReconstruction)
+		require.NoError(t, err)
+
+		require.Equal(t, false, p2p.BroadcastCalled.Load())
+
+		// Check received indices before reconstruction.
+		require.Equal(t, minimumCount, uint64(len(chainService.DataColumns)))
+		for i, actual := range chainService.DataColumns {
+			require.Equal(t, uint64(i), actual.Index)
+		}
+
+		// Run the reconstruction.
+		err = service.processDataColumnSidecarsFromReconstruction(ctx, verifiedRoDataColumns[0])
 		require.NoError(t, err)
 
 		expected := make(map[uint64]bool, minimumCount+cgc)
@@ -81,97 +101,38 @@ func TestReconstructDataColumns(t *testing.T) {
 		}
 
 		// The node should custody these indices.
-		for _, i := range [...]uint64{1, 17, 19, 42, 75, 87, 102, 117} {
+		for _, i := range [...]uint64{75, 87, 102, 117} {
 			expected[i] = true
 		}
 
-		summary := storage.Summary(root)
-		actual := summary.Stored()
+		block := roBlock.Block()
+		slot := block.Slot()
+		proposerIndex := block.ProposerIndex()
 
-		require.Equal(t, len(expected), len(actual))
-		for index := range expected {
-			require.Equal(t, true, actual[index])
-		}
-	})
-}
-
-func TestBroadcastMissingDataColumnSidecars(t *testing.T) {
-	const (
-		cgc          = 8
-		blobCount    = 4
-		timeIntoSlot = 0
-	)
-
-	numberOfColumns := params.BeaconConfig().NumberOfColumns
-	ctx := t.Context()
-
-	// Start the trusted setup.
-	err := kzg.Start()
-	require.NoError(t, err)
-
-	roBlock, _, verifiedRoDataColumns := util.GenerateTestFuluBlockWithSidecars(t, blobCount)
-	require.Equal(t, numberOfColumns, uint64(len(verifiedRoDataColumns)))
-
-	root, block := roBlock.Root(), roBlock.Block()
-	slot, proposerIndex := block.Slot(), block.ProposerIndex()
-
-	t.Run("no missing sidecars", func(t *testing.T) {
-		service := NewService(
-			ctx,
-			WithP2P(p2ptest.NewTestP2P(t)),
-		)
-
-		for _, index := range [...]uint64{1, 17, 19, 42, 75, 87, 102, 117} {
-			key := computeCacheKey(slot, proposerIndex, index)
-			service.seenDataColumnCache.Add(slot, key, true)
-		}
-
-		err := service.broadcastMissingDataColumnSidecars(slot, proposerIndex, root, timeIntoSlot)
-		require.NoError(t, err)
-	})
-
-	t.Run("some missing sidecars", func(t *testing.T) {
-		toSave := make([]blocks.VerifiedRODataColumn, 0, 2)
-		for _, index := range [...]uint64{42, 87} {
-			toSave = append(toSave, verifiedRoDataColumns[index])
-		}
-
-		p2p := p2ptest.NewTestP2P(t)
-		storage := filesystem.NewEphemeralDataColumnStorage(t)
-		err := storage.Save(toSave)
-		require.NoError(t, err)
-
-		service := NewService(
-			ctx,
-			WithP2P(p2p),
-			WithDataColumnStorage(storage),
-		)
-		_, _, err = service.cfg.p2p.UpdateCustodyInfo(0, cgc)
-		require.NoError(t, err)
-
-		for _, index := range [...]uint64{1, 17, 19, 102, 117} { // 42, 75 and 87 are missing
-			key := computeCacheKey(slot, proposerIndex, index)
-			service.seenDataColumnCache.Add(slot, key, true)
-		}
-
-		for _, index := range [...]uint64{42, 75, 87} {
-			seen := service.hasSeenDataColumnIndex(slot, proposerIndex, index)
-			require.Equal(t, false, seen)
-		}
-
-		require.Equal(t, false, p2p.BroadcastCalled.Load())
-
-		err = service.broadcastMissingDataColumnSidecars(slot, proposerIndex, root, timeIntoSlot)
-		require.NoError(t, err)
-
-		seen := service.hasSeenDataColumnIndex(slot, proposerIndex, 75)
-		require.Equal(t, false, seen)
-
-		for _, index := range [...]uint64{42, 87} {
-			seen := service.hasSeenDataColumnIndex(slot, proposerIndex, index)
-			require.Equal(t, true, seen)
+		require.Equal(t, len(expected), len(chainService.DataColumns))
+		for _, actual := range chainService.DataColumns {
+			require.Equal(t, true, expected[actual.Index])
+			require.Equal(t, true, service.hasSeenDataColumnIndex(slot, proposerIndex, actual.Index))
 		}
 
 		require.Equal(t, true, p2p.BroadcastCalled.Load())
 	})
 }
+
+func TestComputeRandomDelay(t *testing.T) {
+	const (
+		seed     = 42
+		expected = 746056722 * time.Nanosecond // = 0.746056722 seconds
+	)
+	slotStartTime := time.Date(2020, 12, 30, 0, 0, 0, 0, time.UTC)
+
+	service := NewService(
+		t.Context(),
+		WithP2P(p2ptest.NewTestP2P(t)),
+		WithReconstructionRandGen(rand.New(rand.NewSource(seed))),
+	)
+
+	waitingTime := service.computeRandomDelay(slotStartTime)
+	fmt.Print(waitingTime)
+	require.Equal(t, expected, waitingTime)
+}

beacon-chain/sync/initial-sync/BUILD.bazel

@@ -34,7 +34,6 @@ go_library(
         "//beacon-chain/verification:go_default_library",
         "//cmd/beacon-chain/flags:go_default_library",
         "//config/features:go_default_library",
-        "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",
         "//consensus-types/interfaces:go_default_library",

beacon-chain/sync/initial-sync/blocks_fetcher.go

@@ -395,6 +395,25 @@ func (f *blocksFetcher) fetchSidecars(ctx context.Context, pid peer.ID, peers []
 		return blobsPid, errors.Wrap(err, "custody info")
 	}
 
+	currentSlot := f.clock.CurrentSlot()
+	currentEpoch := slots.ToEpoch(currentSlot)
+
+	roBlocks := make([]blocks.ROBlock, 0, len(postFulu))
+	for _, blockWithSidecars := range postFulu {
+		blockSlot := blockWithSidecars.Block.Block().Slot()
+		blockEpoch := slots.ToEpoch(blockSlot)
+
+		if params.WithinDAPeriod(blockEpoch, currentEpoch) {
+			roBlocks = append(roBlocks, blockWithSidecars.Block)
+		}
+	}
+
+	// Return early if there are no blocks that need data column sidecars.
+	if len(roBlocks) == 0 {
+		return blobsPid, nil
+	}
+
+	// Some blocks neesd data column sidecars, fetch them.
 	params := prysmsync.DataColumnSidecarsParams{
 		Ctx:         ctx,
 		Tor:         f.clock,
@@ -405,16 +424,19 @@ func (f *blocksFetcher) fetchSidecars(ctx context.Context, pid peer.ID, peers []
 		NewVerifier: f.cv,
 	}
 
-	roBlocks := make([]blocks.ROBlock, 0, len(postFulu))
-	for _, block := range postFulu {
-		roBlocks = append(roBlocks, block.Block)
-	}
-
-	verifiedRoDataColumnsByRoot, err := prysmsync.FetchDataColumnSidecars(params, roBlocks, info.CustodyColumns)
+	verifiedRoDataColumnsByRoot, missingIndicesByRoot, err := prysmsync.FetchDataColumnSidecars(params, roBlocks, info.CustodyColumns)
 	if err != nil {
 		return "", errors.Wrap(err, "fetch data column sidecars")
 	}
 
+	if len(missingIndicesByRoot) > 0 {
+		prettyMissingIndicesByRoot := make(map[string][]uint64, len(missingIndicesByRoot))
+		for root, indices := range missingIndicesByRoot {
+			prettyMissingIndicesByRoot[fmt.Sprintf("%#x", root)] = sortedSliceFromMap(indices)
+		}
+		return "", errors.Errorf("some sidecars are still missing after fetch: %v", prettyMissingIndicesByRoot)
+	}
+
 	// Populate the response.
 	for i := range bwScs {
 		bwSc := &bwScs[i]
@@ -456,6 +478,9 @@ func (f *blocksFetcher) fetchBlocksFromPeer(
 				"count":     req.Count,
 				"step":      req.Step,
 			}).WithError(err).Debug("Could not request blocks by range from peer")
+			if errors.Is(err, prysmsync.ErrInvalidFetchedData) {
+				f.downscorePeer(p, err)
+			}
 			continue
 		}
 		f.p2p.Peers().Scorers().BlockProviderScorer().Touch(p)
@@ -876,6 +901,12 @@ func dedupPeers(peers []peer.ID) []peer.ID {
 	return newPeerList
 }
 
+// downscorePeer increments the bad responses score for the peer and logs the event.
+func (f *blocksFetcher) downscorePeer(peerID peer.ID, reason error) {
+	newScore := f.p2p.Peers().Scorers().BadResponsesScorer().Increment(peerID)
+	log.WithFields(logrus.Fields{"peerID": peerID, "reason": reason, "newScore": newScore}).Debug("Downscore peer")
+}
+
 // findFirstFuluIndex returns the index of the first block with a version >= Fulu.
 // It returns an error if blocks are not correctly sorted by version regarding Fulu.
 func findFirstFuluIndex(bwScs []blocks.BlockWithROSidecars) (int, error) {

beacon-chain/sync/initial-sync/blocks_fetcher_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	dbtest "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/peers/peerdata"
 	p2ptest "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/startup"
 	beaconsync "github.com/OffchainLabs/prysm/v6/beacon-chain/sync"
@@ -910,6 +911,55 @@ func TestBlocksFetcher_requestBlocksFromPeerReturningInvalidBlocks(t *testing.T)
 	}
 }
 
+func TestBlocksFetcher_requestBlocksDownscoreOnInvalidData(t *testing.T) {
+	p1 := p2ptest.NewTestP2P(t)
+	p2 := p2ptest.NewTestP2P(t)
+	p1.Connect(p2)
+
+	topic := p2p.RPCBlocksByRangeTopicV1
+	protocol := libp2pcore.ProtocolID(topic + p1.Encoding().ProtocolSuffix())
+
+	ctx, cancel := context.WithCancel(t.Context())
+	defer cancel()
+
+	fetcher := newBlocksFetcher(ctx, &blocksFetcherConfig{
+		p2p:   p1,
+		chain: &mock.ChainService{Genesis: time.Now(), ValidatorsRoot: [32]byte{}},
+	})
+	fetcher.rateLimiter = leakybucket.NewCollector(0.000001, 640, 1*time.Second, false)
+
+	// Set up handler that returns blocks in wrong order (will trigger ErrInvalidFetchedData)
+	p2.BHost.SetStreamHandler(protocol, func(stream network.Stream) {
+		blk := util.NewBeaconBlock()
+		blk.Block.Slot = 163
+		tor := startup.NewClock(time.Now(), [32]byte{})
+		wsb, err := blocks.NewSignedBeaconBlock(blk)
+		require.NoError(t, err)
+		assert.NoError(t, beaconsync.WriteBlockChunk(stream, tor, p1.Encoding(), wsb))
+
+		blk = util.NewBeaconBlock()
+		blk.Block.Slot = 162
+		wsb, err = blocks.NewSignedBeaconBlock(blk)
+		require.NoError(t, err)
+		assert.NoError(t, beaconsync.WriteBlockChunk(stream, tor, p1.Encoding(), wsb))
+		assert.NoError(t, stream.Close())
+	})
+
+	// Verify the peer has no bad responses before the request
+	scoreBeforeRequest, err := p1.Peers().Scorers().BadResponsesScorer().Count(p2.PeerID())
+	require.ErrorIs(t, err, peerdata.ErrPeerUnknown)
+	assert.Equal(t, -1, scoreBeforeRequest)
+
+	// Use fetchBlocksFromPeer which includes the downscoring logic
+	_, _, err = fetcher.fetchBlocksFromPeer(ctx, 100, 64, []peer.ID{p2.PeerID()})
+	assert.ErrorContains(t, errNoPeersAvailable.Error(), err)
+
+	// Verify the peer was downscored
+	scoreAfterRequest, err := p1.Peers().Scorers().BadResponsesScorer().Count(p2.PeerID())
+	assert.NoError(t, err)
+	assert.Equal(t, 1, scoreAfterRequest)
+}
+
 func TestTimeToWait(t *testing.T) {
 	tests := []struct {
 		name          string
@@ -1335,6 +1385,11 @@ func TestFetchSidecars(t *testing.T) {
 		nower := func() time.Time { return now }
 		clock := startup.NewClock(genesisTime, genesisValidatorRoot, startup.WithNower(nower))
 
+		// Create a data columns storage.
+		dir := t.TempDir()
+		dataColumnStorage, err := filesystem.NewDataColumnStorage(ctx, filesystem.WithDataColumnBasePath(dir))
+		require.NoError(t, err)
+
 		// Define a Deneb block with blobs out of retention period.
 		denebBlock := util.NewBeaconBlockDeneb()
 		denebBlock.Block.Slot = 0 // Genesis slot, out of retention period.
@@ -1343,33 +1398,52 @@ func TestFetchSidecars(t *testing.T) {
 		roDebebBlock, err := blocks.NewROBlock(signedDenebBlock)
 		require.NoError(t, err)
 
-		// Define a Fulu block with blobs in the retention period.
-		fuluBlock := util.NewBeaconBlockFulu()
-		fuluBlock.Block.Slot = slotsPerEpoch                                                            // Within retention period.
-		fuluBlock.Block.Body.BlobKzgCommitments = [][]byte{make([]byte, fieldparams.KzgCommitmentSize)} // Dummy commitment.
-		signedFuluBlock, err := blocks.NewSignedBeaconBlock(fuluBlock)
+		// Define a Fulu block with blobs before the retention period.
+		fuluBlock1 := util.NewBeaconBlockFulu()
+		fuluBlock1.Block.Slot = slotsPerEpoch.Sub(1)                                                     // Before the retention period.
+		fuluBlock1.Block.Body.BlobKzgCommitments = [][]byte{make([]byte, fieldparams.KzgCommitmentSize)} // Dummy commitment.
+		signedFuluBlock1, err := blocks.NewSignedBeaconBlock(fuluBlock1)
 		require.NoError(t, err)
-		roFuluBlock, err := blocks.NewROBlock(signedFuluBlock)
+		roFuluBlock1, err := blocks.NewROBlock(signedFuluBlock1)
 		require.NoError(t, err)
 
-		bodyRoot, err := fuluBlock.Block.Body.HashTreeRoot()
+		bodyRootFulu1, err := fuluBlock1.Block.Body.HashTreeRoot()
 		require.NoError(t, err)
 
-		// Create and save data column sidecars for this fulu block in the database.
-		params := make([]util.DataColumnParam, 0, numberOfColumns)
+		// Create and save data column sidecars for fulu block 2 in the database.
+		paramsFulu1 := make([]util.DataColumnParam, 0, numberOfColumns)
 		for i := range numberOfColumns {
-			param := util.DataColumnParam{Index: i, Slot: slotsPerEpoch, BodyRoot: bodyRoot[:]}
-			params = append(params, param)
+			param := util.DataColumnParam{Index: i, Slot: slotsPerEpoch, BodyRoot: bodyRootFulu1[:]}
+			paramsFulu1 = append(paramsFulu1, param)
 		}
-		_, verifiedRoDataColumnSidecars := util.CreateTestVerifiedRoDataColumnSidecars(t, params)
+		_, verifiedRoDataColumnSidecarsFulu1 := util.CreateTestVerifiedRoDataColumnSidecars(t, paramsFulu1)
 
-		// Create a data columns storage.
-		dir := t.TempDir()
-		dataColumnStorage, err := filesystem.NewDataColumnStorage(ctx, filesystem.WithDataColumnBasePath(dir))
+		// Save the data column sidecars for block fulu 1 to the storage.
+		err = dataColumnStorage.Save(verifiedRoDataColumnSidecarsFulu1)
 		require.NoError(t, err)
 
-		// Save the data column sidecars to the storage.
-		err = dataColumnStorage.Save(verifiedRoDataColumnSidecars)
+		// Define a Fulu block with blobs in the retention period.
+		fuluBlock2 := util.NewBeaconBlockFulu()
+		fuluBlock2.Block.Slot = slotsPerEpoch                                                            // Within retention period.
+		fuluBlock2.Block.Body.BlobKzgCommitments = [][]byte{make([]byte, fieldparams.KzgCommitmentSize)} // Dummy commitment.
+		signedFuluBlock2, err := blocks.NewSignedBeaconBlock(fuluBlock2)
+		require.NoError(t, err)
+		roFuluBlock2, err := blocks.NewROBlock(signedFuluBlock2)
+		require.NoError(t, err)
+
+		bodyRootFulu2, err := fuluBlock2.Block.Body.HashTreeRoot()
+		require.NoError(t, err)
+
+		// Create and save data column sidecars for fulu block 2 in the database.
+		paramsFulu2 := make([]util.DataColumnParam, 0, numberOfColumns)
+		for i := range numberOfColumns {
+			param := util.DataColumnParam{Index: i, Slot: slotsPerEpoch, BodyRoot: bodyRootFulu2[:]}
+			paramsFulu2 = append(paramsFulu2, param)
+		}
+		_, verifiedRoDataColumnSidecarsFulu2 := util.CreateTestVerifiedRoDataColumnSidecars(t, paramsFulu2)
+
+		// Save the data column sidecars for block fulu 2 to the storage.
+		err = dataColumnStorage.Save(verifiedRoDataColumnSidecarsFulu2)
 		require.NoError(t, err)
 
 		// Create a blocks fetcher.
@@ -1382,7 +1456,8 @@ func TestFetchSidecars(t *testing.T) {
 		// Fetch sidecars.
 		blocksWithSidecars := []blocks.BlockWithROSidecars{
 			{Block: roDebebBlock},
-			{Block: roFuluBlock},
+			{Block: roFuluBlock1},
+			{Block: roFuluBlock2},
 		}
 		pid, err := fetcher.fetchSidecars(ctx, "", nil, blocksWithSidecars)
 		require.NoError(t, err)
@@ -1392,12 +1467,15 @@ func TestFetchSidecars(t *testing.T) {
 		require.Equal(t, 0, len(blocksWithSidecars[0].Blobs))
 		require.Equal(t, 0, len(blocksWithSidecars[0].Columns))
 		require.Equal(t, 0, len(blocksWithSidecars[1].Blobs))
+		require.Equal(t, 0, len(blocksWithSidecars[1].Columns))
+		require.Equal(t, 0, len(blocksWithSidecars[2].Blobs))
 
 		// We don't check the content of the columns here. The extensive test is done
 		// in TestFetchDataColumnsSidecars.
-		require.Equal(t, samplesPerSlot, uint64(len(blocksWithSidecars[1].Columns)))
+		require.Equal(t, samplesPerSlot, uint64(len(blocksWithSidecars[2].Columns)))
 	})
 }
+
 func TestFirstFuluIndex(t *testing.T) {
 	bellatrix := util.NewBeaconBlockBellatrix()
 	signedBellatrix, err := blocks.NewSignedBeaconBlock(bellatrix)

beacon-chain/sync/initial-sync/service.go

@@ -22,7 +22,6 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/sync"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
 	"github.com/OffchainLabs/prysm/v6/cmd/beacon-chain/flags"
-	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/crypto/rand"
@@ -73,6 +72,7 @@ type Service struct {
 	newDataColumnsVerifier verification.NewDataColumnsVerifier
 	ctxMap                 sync.ContextByteVersions
 	genesisTime            time.Time
+	toggler                *sync.ServiceToggler
 }
 
 // Option is a functional option for the initial-sync Service.
@@ -94,6 +94,14 @@ func WithSyncChecker(checker *SyncChecker) Option {
 	}
 }
 
+// WithServiceToggle sets the ServiceToggler, which is used to coordinate
+// with backfill, so that only one service runs at a time.
+func WithServiceToggle(toggler *sync.ServiceToggler) Option {
+	return func(s *Service) {
+		s.toggler = toggler
+	}
+}
+
 // SyncChecker allows other services to check the current status of
 // initial-sync and use that internally in their service.
 type SyncChecker struct {
@@ -160,22 +168,25 @@ func (s *Service) Start() {
 		log.Debug("Exiting Initial Sync Service")
 		return
 	}
+
+	if err := s.beginSync(); err != nil {
+		log.WithError(err).Error("Failed to get acquire sync toggle lock")
+		return
+	}
+	defer s.completeSync()
 	s.genesisTime = gt
 	// Exit entering round-robin sync if we require 0 peers to sync.
 	if flags.Get().MinimumSyncPeers == 0 {
-		s.markSynced()
 		log.WithField("genesisTime", s.genesisTime).Info("Due to number of peers required for sync being set at 0, entering regular sync immediately.")
 		return
 	}
 	if s.genesisTime.After(prysmTime.Now()) {
-		s.markSynced()
 		log.WithField("genesisTime", s.genesisTime).Info("Genesis time has not arrived - not syncing")
 		return
 	}
 	currentSlot := clock.CurrentSlot()
 	if slots.ToEpoch(currentSlot) == 0 {
 		log.WithField("genesisTime", s.genesisTime).Info("Chain started within the last epoch - not syncing")
-		s.markSynced()
 		return
 	}
 	s.chainStarted.Set()
@@ -184,7 +195,6 @@ func (s *Service) Start() {
 	// Are we already in sync, or close to it?
 	if slots.ToEpoch(s.cfg.Chain.HeadSlot()) == slots.ToEpoch(currentSlot) {
 		log.Info("Already synced to the current chain head")
-		s.markSynced()
 		return
 	}
 
@@ -205,7 +215,18 @@ func (s *Service) Start() {
 		panic(err) // lint:nopanic -- Unexpected error. This should probably be surfaced with a returned error.
 	}
 	log.WithField("slot", s.cfg.Chain.HeadSlot()).Info("Synced up to")
-	s.markSynced()
+}
+
+func (s *Service) beginSync() error {
+	s.synced.UnSet()
+	return s.toggler.Acquire(s.ctx, sync.ToggleGroupRangeSync)
+}
+
+// completeSync marks node as synced and notifies feed listeners.
+func (s *Service) completeSync() {
+	s.toggler.Release(sync.ToggleGroupRangeSync)
+	s.synced.Set()
+	close(s.cfg.InitialSyncComplete)
 }
 
 // fetchOriginSidecars fetches origin sidecars
@@ -237,14 +258,14 @@ func (s *Service) fetchOriginSidecars(peers []peer.ID) error {
 	blockVersion := roBlock.Version()
 
 	if blockVersion >= version.Fulu {
-		if err := s.fetchOriginColumns(roBlock, delay); err != nil {
+		if err := s.fetchOriginDataColumnSidecars(roBlock, delay); err != nil {
 			return errors.Wrap(err, "fetch origin columns")
 		}
 		return nil
 	}
 
 	if blockVersion >= version.Deneb {
-		if err := s.fetchOriginBlobs(peers, roBlock); err != nil {
+		if err := s.fetchOriginBlobSidecars(peers, roBlock); err != nil {
 			return errors.Wrap(err, "fetch origin blobs")
 		}
 	}
@@ -290,8 +311,10 @@ func (s *Service) Resync() error {
 	}
 
 	// Set it to false since we are syncing again.
-	s.synced.UnSet()
-	defer func() { s.synced.Set() }() // Reset it at the end of the method.
+	if err := s.beginSync(); err != nil {
+		return errors.Wrap(err, "begin sync")
+	}
+	defer func() { s.completeSync() }() // Reset it at the end of the method.
 
 	_, err = s.waitForMinimumPeers()
 	if err != nil {
@@ -326,12 +349,6 @@ func (s *Service) waitForMinimumPeers() ([]peer.ID, error) {
 	}
 }
 
-// markSynced marks node as synced and notifies feed listeners.
-func (s *Service) markSynced() {
-	s.synced.Set()
-	close(s.cfg.InitialSyncComplete)
-}
-
 func missingBlobRequest(blk blocks.ROBlock, store *filesystem.BlobStorage) (p2ptypes.BlobSidecarsByRootReq, error) {
 	r := blk.Root()
 	if blk.Version() < version.Deneb {
@@ -356,7 +373,7 @@ func missingBlobRequest(blk blocks.ROBlock, store *filesystem.BlobStorage) (p2pt
 	return req, nil
 }
 
-func (s *Service) fetchOriginBlobs(pids []peer.ID, rob blocks.ROBlock) error {
+func (s *Service) fetchOriginBlobSidecars(pids []peer.ID, rob blocks.ROBlock) error {
 	r := rob.Root()
 
 	req, err := missingBlobRequest(rob, s.cfg.BlobStorage)
@@ -394,11 +411,12 @@ func (s *Service) fetchOriginBlobs(pids []peer.ID, rob blocks.ROBlock) error {
 	return fmt.Errorf("no connected peer able to provide blobs for checkpoint sync block %#x", r)
 }
 
-func (s *Service) fetchOriginColumns(roBlock blocks.ROBlock, delay time.Duration) error {
+func (s *Service) fetchOriginDataColumnSidecars(roBlock blocks.ROBlock, delay time.Duration) error {
 	const (
 		errorMessage     = "Failed to fetch origin data column sidecars"
 		warningIteration = 10
 	)
+
 	samplesPerSlot := params.BeaconConfig().SamplesPerSlot
 
 	// Return early if the origin block has no blob commitments.
@@ -411,7 +429,7 @@ func (s *Service) fetchOriginColumns(roBlock blocks.ROBlock, delay time.Duration
 		return nil
 	}
 
-	// Compute the columns to request.
+	// Compute the indices we need to custody.
 	custodyGroupCount, err := s.cfg.P2P.CustodyGroupCount()
 	if err != nil {
 		return errors.Wrap(err, "custody group count")
@@ -423,9 +441,30 @@ func (s *Service) fetchOriginColumns(roBlock blocks.ROBlock, delay time.Duration
 		return errors.Wrap(err, "fetch peer info")
 	}
 
-	// Fetch origin data column sidecars.
 	root := roBlock.Root()
 
+	log := log.WithFields(logrus.Fields{
+		"blockRoot":       fmt.Sprintf("%#x", roBlock.Root()),
+		"blobCount":       len(commitments),
+		"dataColumnCount": len(info.CustodyColumns),
+	})
+
+	// Check if some needed data column sidecars are missing.
+	stored := s.cfg.DataColumnStorage.Summary(root).Stored()
+	missing := make(map[uint64]bool, len(info.CustodyColumns))
+	for column := range info.CustodyColumns {
+		if !stored[column] {
+			missing[column] = true
+		}
+	}
+
+	if len(missing) == 0 {
+		// All needed data column sidecars are present, exit early.
+		log.Info("All needed origin data column sidecars are already present")
+
+		return nil
+	}
+
 	params := sync.DataColumnSidecarsParams{
 		Ctx:                     s.ctx,
 		Tor:                     s.clock,
@@ -436,46 +475,39 @@ func (s *Service) fetchOriginColumns(roBlock blocks.ROBlock, delay time.Duration
 		DownscorePeerOnRPCFault: true,
 	}
 
-	var verifiedRoDataColumnsByRoot map[[fieldparams.RootLength]byte][]blocks.VerifiedRODataColumn
 	for attempt := uint64(0); ; attempt++ {
-		verifiedRoDataColumnsByRoot, err = sync.FetchDataColumnSidecars(params, []blocks.ROBlock{roBlock}, info.CustodyColumns)
-		if err == nil {
-			break
+		// Retrieve missing data column sidecars.
+		verifiedRoSidecarsByRoot, missingIndicesByRoot, err := sync.FetchDataColumnSidecars(params, []blocks.ROBlock{roBlock}, missing)
+		if err != nil {
+			return errors.Wrap(err, "fetch data column sidecars")
 		}
 
-		log := log.WithError(err).WithFields(logrus.Fields{
-			"attempt": attempt,
-			"delay":   delay,
+		// Save retrieved data column sidecars.
+		if err := s.cfg.DataColumnStorage.Save(verifiedRoSidecarsByRoot[root]); err != nil {
+			return errors.Wrap(err, "save data column sidecars")
+		}
+
+		// Check if some needed data column sidecars are missing.
+		if len(missingIndicesByRoot) == 0 {
+			log.Info("Retrieved all needed origin data column sidecars")
+
+			return nil
+		}
+
+		// Some sidecars are still missing.
+		log := log.WithFields(logrus.Fields{
+			"attempt":        attempt,
+			"missingIndices": sortedSliceFromMap(missingIndicesByRoot[root]),
+			"delay":          delay,
 		})
 
-		if attempt%warningIteration == 0 && attempt > 0 {
-			log.Warning(errorMessage)
-			time.Sleep(delay)
-
-			continue
+		logFunc := log.Debug
+		if attempt > 0 && attempt%warningIteration == 0 {
+			logFunc = log.Warning
 		}
 
-		log.Debug(errorMessage)
-		time.Sleep(delay)
+		logFunc("Failed to fetch some origin data column sidecars, retrying later")
 	}
-
-	// Save origin data columns to disk.
-	verifiedRoDataColumnsSidecars, ok := verifiedRoDataColumnsByRoot[root]
-	if !ok {
-		return fmt.Errorf("cannot extract origins data column sidecars for block root %#x - should never happen", root)
-	}
-
-	if err := s.cfg.DataColumnStorage.Save(verifiedRoDataColumnsSidecars); err != nil {
-		return errors.Wrap(err, "save data column sidecars")
-	}
-
-	log.WithFields(logrus.Fields{
-		"blockRoot":   fmt.Sprintf("%#x", roBlock.Root()),
-		"blobCount":   len(commitments),
-		"columnCount": len(verifiedRoDataColumnsSidecars),
-	}).Info("Successfully downloaded data column sidecars for checkpoint sync block")
-
-	return nil
 }
 
 func shufflePeers(pids []peer.ID) {

beacon-chain/sync/initial-sync/service_test.go

@@ -19,7 +19,7 @@ import (
 	p2ptest "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	testp2p "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/startup"
-	prysmSync "github.com/OffchainLabs/prysm/v6/beacon-chain/sync"
+	bcsync "github.com/OffchainLabs/prysm/v6/beacon-chain/sync"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
 	"github.com/OffchainLabs/prysm/v6/cmd/beacon-chain/flags"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
@@ -174,6 +174,7 @@ func TestService_InitStartStop(t *testing.T) {
 				StateNotifier:       &mock.MockStateNotifier{},
 				InitialSyncComplete: make(chan struct{}),
 			})
+			s.toggler = bcsync.NewServiceToggler()
 			s.verifierWaiter = verification.NewInitializerWaiter(gs, nil, nil)
 			time.Sleep(500 * time.Millisecond)
 			assert.NotNil(t, s)
@@ -218,6 +219,7 @@ func TestService_waitForStateInitialization(t *testing.T) {
 			genesisChan:  make(chan time.Time),
 		}
 		s.verifierWaiter = verification.NewInitializerWaiter(cs, nil, nil)
+		s.toggler = bcsync.NewServiceToggler()
 		return s, cs
 	}
 
@@ -318,16 +320,18 @@ func TestService_markSynced(t *testing.T) {
 		StateNotifier:       mc.StateNotifier(),
 		InitialSyncComplete: make(chan struct{}),
 	})
+	s.toggler = bcsync.NewServiceToggler()
 	require.NotNil(t, s)
 	assert.Equal(t, false, s.chainStarted.IsSet())
 	assert.Equal(t, false, s.synced.IsSet())
 	assert.Equal(t, true, s.Syncing())
 	assert.NoError(t, s.Status())
+	require.NoError(t, s.beginSync())
 	s.chainStarted.Set()
 	assert.ErrorContains(t, "syncing", s.Status())
 
 	go func() {
-		s.markSynced()
+		s.completeSync()
 	}()
 
 	select {
@@ -398,12 +402,14 @@ func TestService_Resync(t *testing.T) {
 				mc = tt.chainService()
 			}
 			s := NewService(ctx, &Config{
-				DB:            beaconDB,
-				P2P:           p,
-				Chain:         mc,
-				StateNotifier: mc.StateNotifier(),
-				BlobStorage:   filesystem.NewEphemeralBlobStorage(t),
+				DB:                  beaconDB,
+				P2P:                 p,
+				Chain:               mc,
+				StateNotifier:       mc.StateNotifier(),
+				BlobStorage:         filesystem.NewEphemeralBlobStorage(t),
+				InitialSyncComplete: make(chan struct{}),
 			})
+			s.toggler = bcsync.NewServiceToggler()
 			assert.NotNil(t, s)
 			s.genesisTime = mc.Genesis
 			assert.Equal(t, primitives.Slot(0), s.cfg.Chain.HeadSlot())
@@ -699,7 +705,7 @@ func TestFetchOriginColumns(t *testing.T) {
 		roBlock, err := blocks.NewROBlock(signedBlock)
 		require.NoError(t, err)
 
-		err = service.fetchOriginColumns(roBlock, delay)
+		err = service.fetchOriginDataColumnSidecars(roBlock, delay)
 		require.NoError(t, err)
 	})
 
@@ -721,7 +727,7 @@ func TestFetchOriginColumns(t *testing.T) {
 		err := storage.Save(verifiedSidecars)
 		require.NoError(t, err)
 
-		err = service.fetchOriginColumns(roBlock, delay)
+		err = service.fetchOriginDataColumnSidecars(roBlock, delay)
 		require.NoError(t, err)
 	})
 
@@ -747,10 +753,35 @@ func TestFetchOriginColumns(t *testing.T) {
 		other.ENR().Set(peerdas.Cgc(numberOfCustodyGroups))
 		p2p.Peers().UpdateENR(other.ENR(), other.PeerID())
 
-		expectedRequest := &ethpb.DataColumnSidecarsByRangeRequest{
-			StartSlot: 0,
-			Count:     1,
-			Columns:   []uint64{1, 17, 19, 42, 75, 87, 102, 117},
+		allBut42 := make([]uint64, 0, numberOfCustodyGroups-1)
+		for i := range numberOfCustodyGroups {
+			if i != 42 {
+				allBut42 = append(allBut42, i)
+			}
+		}
+
+		expectedRequests := []*ethpb.DataColumnSidecarsByRangeRequest{
+			{
+				StartSlot: 0,
+				Count:     1,
+				Columns:   []uint64{1, 17, 19, 42, 75, 87, 102, 117},
+			},
+			{
+				StartSlot: 0,
+				Count:     1,
+				Columns:   allBut42,
+			},
+			{
+				StartSlot: 0,
+				Count:     1,
+				Columns:   []uint64{1, 17, 19, 75, 87, 102, 117},
+			},
+		}
+
+		toRespondByAttempt := [][]uint64{
+			{42},
+			{},
+			{1, 17, 19, 75, 87, 102, 117},
 		}
 
 		clock := startup.NewClock(time.Now(), [fieldparams.RootLength]byte{})
@@ -768,7 +799,7 @@ func TestFetchOriginColumns(t *testing.T) {
 		// Create a block with blob commitments and sidecars
 		roBlock, _, verifiedRoSidecars := util.GenerateTestFuluBlockWithSidecars(t, blobCount)
 
-		ctxMap, err := prysmSync.ContextByteVersionsForValRoot(params.BeaconConfig().GenesisValidatorsRoot)
+		ctxMap, err := bcsync.ContextByteVersionsForValRoot(params.BeaconConfig().GenesisValidatorsRoot)
 		require.NoError(t, err)
 
 		service := &Service{
@@ -783,36 +814,33 @@ func TestFetchOriginColumns(t *testing.T) {
 		}
 
 		// Do not respond any sidecar on the first attempt, and respond everything requested on the second one.
-		firstAttempt := true
+		attempt := 0
 		other.SetStreamHandler(protocol, func(stream network.Stream) {
 			actualRequest := new(ethpb.DataColumnSidecarsByRangeRequest)
 			err := other.Encoding().DecodeWithMaxLength(stream, actualRequest)
 			assert.NoError(t, err)
-			assert.DeepEqual(t, expectedRequest, actualRequest)
+			assert.DeepEqual(t, expectedRequests[attempt], actualRequest)
 
-			if firstAttempt {
-				firstAttempt = false
-				err = stream.CloseWrite()
-				assert.NoError(t, err)
-				return
-			}
-
-			for _, column := range actualRequest.Columns {
-				err = prysmSync.WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedRoSidecars[column].DataColumnSidecar)
+			for _, column := range toRespondByAttempt[attempt] {
+				err = bcsync.WriteDataColumnSidecarChunk(stream, clock, other.Encoding(), verifiedRoSidecars[column].DataColumnSidecar)
 				assert.NoError(t, err)
 			}
 
 			err = stream.CloseWrite()
 			assert.NoError(t, err)
+
+			attempt++
 		})
 
-		err = service.fetchOriginColumns(roBlock, delay)
+		err = service.fetchOriginDataColumnSidecars(roBlock, delay)
 		require.NoError(t, err)
 
 		// Check all corresponding sidecars are saved in the store.
 		summary := storage.Summary(roBlock.Root())
-		for _, index := range expectedRequest.Columns {
-			require.Equal(t, true, summary.HasIndex(index))
+		for _, indices := range toRespondByAttempt {
+			for _, index := range indices {
+				require.Equal(t, true, summary.HasIndex(index))
+			}
 		}
 	})
 }

beacon-chain/sync/kzg_batch_verifier_test.go

@@ -0,0 +1,327 @@
+package sync
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
+	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
+	"github.com/OffchainLabs/prysm/v6/testing/assert"
+	"github.com/OffchainLabs/prysm/v6/testing/require"
+	"github.com/OffchainLabs/prysm/v6/testing/util"
+	pubsub "github.com/libp2p/go-libp2p-pubsub"
+)
+
+func TestValidateWithKzgBatchVerifier(t *testing.T) {
+	err := kzg.Start()
+	require.NoError(t, err)
+
+	tests := []struct {
+		name           string
+		dataColumns    []blocks.RODataColumn
+		expectedResult pubsub.ValidationResult
+		expectError    bool
+	}{
+		{
+			name:           "single valid data column",
+			dataColumns:    createValidTestDataColumns(t, 1),
+			expectedResult: pubsub.ValidationAccept,
+			expectError:    false,
+		},
+		{
+			name:           "multiple valid data columns",
+			dataColumns:    createValidTestDataColumns(t, 3),
+			expectedResult: pubsub.ValidationAccept,
+			expectError:    false,
+		},
+		{
+			name:           "single invalid data column",
+			dataColumns:    createInvalidTestDataColumns(t, 1),
+			expectedResult: pubsub.ValidationReject,
+			expectError:    true,
+		},
+		{
+			name:           "empty data column slice",
+			dataColumns:    []blocks.RODataColumn{},
+			expectedResult: pubsub.ValidationAccept,
+			expectError:    false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+
+			service := &Service{
+				ctx:     ctx,
+				kzgChan: make(chan *kzgVerifier, 100),
+			}
+			go service.kzgVerifierRoutine()
+
+			result, err := service.validateWithKzgBatchVerifier(ctx, tt.dataColumns)
+
+			require.Equal(t, tt.expectedResult, result)
+			if tt.expectError {
+				assert.NotNil(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestVerifierRoutine(t *testing.T) {
+	err := kzg.Start()
+	require.NoError(t, err)
+
+	t.Run("processes single request", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+
+		service := &Service{
+			ctx:     ctx,
+			kzgChan: make(chan *kzgVerifier, 100),
+		}
+		go service.kzgVerifierRoutine()
+
+		dataColumns := createValidTestDataColumns(t, 1)
+		resChan := make(chan error, 1)
+		service.kzgChan <- &kzgVerifier{dataColumns: dataColumns, resChan: resChan}
+
+		select {
+		case err := <-resChan:
+			require.NoError(t, err)
+		case <-time.After(time.Second):
+			t.Fatal("timeout waiting for verification result")
+		}
+	})
+
+	t.Run("batches multiple requests", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+
+		service := &Service{
+			ctx:     ctx,
+			kzgChan: make(chan *kzgVerifier, 100),
+		}
+		go service.kzgVerifierRoutine()
+
+		const numRequests = 5
+		resChans := make([]chan error, numRequests)
+
+		for i := range numRequests {
+			dataColumns := createValidTestDataColumns(t, 1)
+			resChan := make(chan error, 1)
+			resChans[i] = resChan
+			service.kzgChan <- &kzgVerifier{dataColumns: dataColumns, resChan: resChan}
+		}
+
+		for i := range numRequests {
+			select {
+			case err := <-resChans[i]:
+				require.NoError(t, err)
+			case <-time.After(time.Second):
+				t.Fatalf("timeout waiting for verification result %d", i)
+			}
+		}
+	})
+
+	t.Run("context cancellation stops routine", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+
+		service := &Service{
+			ctx:     ctx,
+			kzgChan: make(chan *kzgVerifier, 100),
+		}
+
+		routineDone := make(chan struct{})
+		go func() {
+			service.kzgVerifierRoutine()
+			close(routineDone)
+		}()
+
+		cancel()
+
+		select {
+		case <-routineDone:
+		case <-time.After(time.Second):
+			t.Fatal("timeout waiting for routine to exit")
+		}
+	})
+}
+
+func TestVerifyKzgBatch(t *testing.T) {
+	err := kzg.Start()
+	require.NoError(t, err)
+
+	t.Run("all valid data columns succeed", func(t *testing.T) {
+		dataColumns := createValidTestDataColumns(t, 3)
+		resChan := make(chan error, 1)
+		kzgVerifiers := []*kzgVerifier{{dataColumns: dataColumns, resChan: resChan}}
+
+		verifyKzgBatch(kzgVerifiers)
+
+		select {
+		case err := <-resChan:
+			require.NoError(t, err)
+		case <-time.After(time.Second):
+			t.Fatal("timeout waiting for batch verification")
+		}
+	})
+
+	t.Run("invalid proofs fail entire batch", func(t *testing.T) {
+		validColumns := createValidTestDataColumns(t, 1)
+		invalidColumns := createInvalidTestDataColumns(t, 1)
+		allColumns := append(validColumns, invalidColumns...)
+
+		resChan := make(chan error, 1)
+		kzgVerifiers := []*kzgVerifier{{dataColumns: allColumns, resChan: resChan}}
+
+		verifyKzgBatch(kzgVerifiers)
+
+		select {
+		case err := <-resChan:
+			assert.NotNil(t, err)
+		case <-time.After(time.Second):
+			t.Fatal("timeout waiting for batch verification")
+		}
+	})
+
+	t.Run("empty batch handling", func(t *testing.T) {
+		verifyKzgBatch([]*kzgVerifier{})
+	})
+}
+
+func TestKzgBatchVerifierConcurrency(t *testing.T) {
+	err := kzg.Start()
+	require.NoError(t, err)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	service := &Service{
+		ctx:     ctx,
+		kzgChan: make(chan *kzgVerifier, 100),
+	}
+	go service.kzgVerifierRoutine()
+
+	const numGoroutines = 10
+	const numRequestsPerGoroutine = 5
+
+	var wg sync.WaitGroup
+	wg.Add(numGoroutines)
+
+	// Multiple goroutines sending verification requests simultaneously
+	for i := range numGoroutines {
+		go func(goroutineID int) {
+			defer wg.Done()
+
+			for range numRequestsPerGoroutine {
+				dataColumns := createValidTestDataColumns(t, 1)
+				result, err := service.validateWithKzgBatchVerifier(ctx, dataColumns)
+				require.Equal(t, pubsub.ValidationAccept, result)
+				require.NoError(t, err)
+			}
+		}(i)
+	}
+
+	wg.Wait()
+}
+
+func TestKzgBatchVerifierFallback(t *testing.T) {
+	err := kzg.Start()
+	require.NoError(t, err)
+
+	t.Run("fallback handles mixed valid/invalid batch correctly", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+
+		service := &Service{
+			ctx:     ctx,
+			kzgChan: make(chan *kzgVerifier, 100),
+		}
+		go service.kzgVerifierRoutine()
+
+		validColumns := createValidTestDataColumns(t, 1)
+		invalidColumns := createInvalidTestDataColumns(t, 1)
+
+		result, err := service.validateWithKzgBatchVerifier(ctx, validColumns)
+		require.Equal(t, pubsub.ValidationAccept, result)
+		require.NoError(t, err)
+
+		result, err = service.validateWithKzgBatchVerifier(ctx, invalidColumns)
+		require.Equal(t, pubsub.ValidationReject, result)
+		assert.NotNil(t, err)
+	})
+
+	t.Run("empty data columns fallback", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+
+		service := &Service{
+			ctx:     ctx,
+			kzgChan: make(chan *kzgVerifier, 100),
+		}
+		go service.kzgVerifierRoutine()
+
+		result, err := service.validateWithKzgBatchVerifier(ctx, []blocks.RODataColumn{})
+		require.Equal(t, pubsub.ValidationAccept, result)
+		require.NoError(t, err)
+	})
+}
+
+func createValidTestDataColumns(t *testing.T, count int) []blocks.RODataColumn {
+	_, roSidecars, _ := util.GenerateTestFuluBlockWithSidecars(t, count)
+	if len(roSidecars) >= count {
+		return roSidecars[:count]
+	}
+	return roSidecars
+}
+
+func createInvalidTestDataColumns(t *testing.T, count int) []blocks.RODataColumn {
+	dataColumns := createValidTestDataColumns(t, count)
+
+	if len(dataColumns) > 0 {
+		sidecar := dataColumns[0].DataColumnSidecar
+		if len(sidecar.Column) > 0 && len(sidecar.Column[0]) > 0 {
+			corruptedSidecar := &ethpb.DataColumnSidecar{
+				Index:                        sidecar.Index,
+				KzgCommitments:               make([][]byte, len(sidecar.KzgCommitments)),
+				KzgProofs:                    make([][]byte, len(sidecar.KzgProofs)),
+				KzgCommitmentsInclusionProof: make([][]byte, len(sidecar.KzgCommitmentsInclusionProof)),
+				SignedBlockHeader:            sidecar.SignedBlockHeader,
+				Column:                       make([][]byte, len(sidecar.Column)),
+			}
+
+			for i, commitment := range sidecar.KzgCommitments {
+				corruptedSidecar.KzgCommitments[i] = make([]byte, len(commitment))
+				copy(corruptedSidecar.KzgCommitments[i], commitment)
+			}
+
+			for i, proof := range sidecar.KzgProofs {
+				corruptedSidecar.KzgProofs[i] = make([]byte, len(proof))
+				copy(corruptedSidecar.KzgProofs[i], proof)
+			}
+
+			for i, proof := range sidecar.KzgCommitmentsInclusionProof {
+				corruptedSidecar.KzgCommitmentsInclusionProof[i] = make([]byte, len(proof))
+				copy(corruptedSidecar.KzgCommitmentsInclusionProof[i], proof)
+			}
+
+			for i, col := range sidecar.Column {
+				corruptedSidecar.Column[i] = make([]byte, len(col))
+				copy(corruptedSidecar.Column[i], col)
+			}
+			corruptedSidecar.Column[0][0] ^= 0xFF // Flip bits to corrupt
+
+			corruptedRO, err := blocks.NewRODataColumn(corruptedSidecar)
+			require.NoError(t, err)
+			dataColumns[0] = corruptedRO
+		}
+	}
+	return dataColumns
+}

beacon-chain/sync/options.go

@@ -6,10 +6,10 @@ import (
 	blockfeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/block"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/operation"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/execution"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/blstoexec"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/slashings"
@@ -20,6 +20,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/state/stategen"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/sync/backfill/coverage"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
+	"github.com/OffchainLabs/prysm/v6/crypto/rand"
 )
 
 type Option func(s *Service) error
@@ -229,3 +230,11 @@ func WithBatchVerifierLimit(limit int) Option {
 		return nil
 	}
 }
+
+// WithReconstructionRandGen sets the random generator for reconstruction delays.
+func WithReconstructionRandGen(rg *rand.Rand) Option {
+	return func(s *Service) error {
+		s.reconstructionRandGen = rg
+		return nil
+	}
+}

beacon-chain/sync/rpc_beacon_blocks_by_root.go

@@ -115,11 +115,19 @@ func (s *Service) requestAndSaveMissingDataColumnSidecars(blks []blocks.ROBlock)
 		NewVerifier: s.newColumnsVerifier,
 	}
 
-	sidecarsByRoot, err := FetchDataColumnSidecars(params, blks, info.CustodyColumns)
+	sidecarsByRoot, missingIndicesByRoot, err := FetchDataColumnSidecars(params, blks, info.CustodyColumns)
 	if err != nil {
 		return errors.Wrap(err, "fetch data column sidecars")
 	}
 
+	if len(missingIndicesByRoot) > 0 {
+		prettyMissingIndicesByRoot := make(map[string][]uint64, len(missingIndicesByRoot))
+		for root, indices := range missingIndicesByRoot {
+			prettyMissingIndicesByRoot[fmt.Sprintf("%#x", root)] = sortedSliceFromMap(indices)
+		}
+		return errors.Errorf("some sidecars are still missing after fetch: %v", prettyMissingIndicesByRoot)
+	}
+
 	// Save the sidecars to the storage.
 	count := 0
 	for _, sidecars := range sidecarsByRoot {

beacon-chain/sync/rpc_light_client.go

@@ -112,7 +112,15 @@ func (s *Service) lightClientUpdatesByRangeRPCHandler(ctx context.Context, msg i
 
 	logger.Infof("LC: requesting updates by range (StartPeriod: %d, EndPeriod: %d)", r.StartPeriod, r.StartPeriod+r.Count-1)
 
-	updates, err := s.lcStore.LightClientUpdates(ctx, r.StartPeriod, endPeriod)
+	headBlock, err := s.cfg.chain.HeadBlock(ctx)
+	if err != nil {
+		s.writeErrorResponseToStream(responseCodeServerError, types.ErrGeneric.Error(), stream)
+		tracing.AnnotateError(span, err)
+		logger.WithError(err).Error("Cannot retrieve head block")
+		return err
+	}
+
+	updates, err := s.lcStore.LightClientUpdates(ctx, r.StartPeriod, endPeriod, headBlock)
 	if err != nil {
 		s.writeErrorResponseToStream(responseCodeServerError, types.ErrGeneric.Error(), stream)
 		tracing.AnnotateError(span, err)

beacon-chain/sync/rpc_light_client_test.go

@@ -8,14 +8,15 @@ import (
 	"github.com/OffchainLabs/prysm/v6/async/abool"
 	"github.com/OffchainLabs/prysm/v6/async/event"
 	mockChain "github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/testing"
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	db "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p"
 	p2ptest "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/startup"
 	mockSync "github.com/OffchainLabs/prysm/v6/beacon-chain/sync/initial-sync/testing"
 	"github.com/OffchainLabs/prysm/v6/config/features"
 	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	leakybucket "github.com/OffchainLabs/prysm/v6/container/leaky-bucket"
 	pb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v6/runtime/version"
@@ -43,6 +44,8 @@ func TestRPC_LightClientBootstrap(t *testing.T) {
 		Genesis:        time.Unix(time.Now().Unix(), 0),
 	}
 	d := db.SetupDB(t)
+	lcStore := lightClient.NewLightClientStore(&p2ptest.FakeP2P{}, new(event.Feed), d)
+
 	r := Service{
 		ctx: ctx,
 		cfg: &config{
@@ -54,7 +57,7 @@ func TestRPC_LightClientBootstrap(t *testing.T) {
 			stateNotifier: &mockChain.MockStateNotifier{},
 		},
 		chainStarted: abool.New(),
-		lcStore:      lightClient.NewLightClientStore(d, &p2ptest.FakeP2P{}, new(event.Feed)),
+		lcStore:      lcStore,
 		subHandler:   newSubTopicHandler(),
 		rateLimiter:  newRateLimiter(p1),
 	}
@@ -159,6 +162,8 @@ func TestRPC_LightClientOptimisticUpdate(t *testing.T) {
 		Genesis:        time.Unix(time.Now().Unix(), 0),
 	}
 	d := db.SetupDB(t)
+	lcStore := lightClient.NewLightClientStore(&p2ptest.FakeP2P{}, new(event.Feed), d)
+
 	r := Service{
 		ctx: ctx,
 		cfg: &config{
@@ -170,7 +175,7 @@ func TestRPC_LightClientOptimisticUpdate(t *testing.T) {
 			stateNotifier: &mockChain.MockStateNotifier{},
 		},
 		chainStarted: abool.New(),
-		lcStore:      lightClient.NewLightClientStore(d, &p2ptest.FakeP2P{}, new(event.Feed)),
+		lcStore:      lcStore,
 		subHandler:   newSubTopicHandler(),
 		rateLimiter:  newRateLimiter(p1),
 	}
@@ -274,6 +279,8 @@ func TestRPC_LightClientFinalityUpdate(t *testing.T) {
 		Genesis:        time.Unix(time.Now().Unix(), 0),
 	}
 	d := db.SetupDB(t)
+	lcStore := lightClient.NewLightClientStore(&p2ptest.FakeP2P{}, new(event.Feed), d)
+
 	r := Service{
 		ctx: ctx,
 		cfg: &config{
@@ -285,7 +292,7 @@ func TestRPC_LightClientFinalityUpdate(t *testing.T) {
 			stateNotifier: &mockChain.MockStateNotifier{},
 		},
 		chainStarted: abool.New(),
-		lcStore:      lightClient.NewLightClientStore(d, &p2ptest.FakeP2P{}, new(event.Feed)),
+		lcStore:      lcStore,
 		subHandler:   newSubTopicHandler(),
 		rateLimiter:  newRateLimiter(p1),
 	}
@@ -384,11 +391,19 @@ func TestRPC_LightClientUpdatesByRange(t *testing.T) {
 	p1.Connect(p2)
 	require.Equal(t, 1, len(p1.BHost.Network().Peers()), "Expected peers to be connected")
 
+	blk := util.NewBeaconBlock()
+	signedBlk, err := blocks.NewSignedBeaconBlock(blk)
+	require.NoError(t, err)
+
 	chainService := &mockChain.ChainService{
 		ValidatorsRoot: [32]byte{'A'},
 		Genesis:        time.Unix(time.Now().Unix(), 0),
+		Block:          signedBlk,
 	}
 	d := db.SetupDB(t)
+	lcStore := lightClient.NewLightClientStore(&p2ptest.FakeP2P{}, new(event.Feed), d)
+	require.NoError(t, err)
+
 	r := Service{
 		ctx: ctx,
 		cfg: &config{
@@ -400,7 +415,7 @@ func TestRPC_LightClientUpdatesByRange(t *testing.T) {
 			stateNotifier: &mockChain.MockStateNotifier{},
 		},
 		chainStarted: abool.New(),
-		lcStore:      lightClient.NewLightClientStore(d, &p2ptest.FakeP2P{}, new(event.Feed)),
+		lcStore:      lcStore,
 		subHandler:   newSubTopicHandler(),
 		rateLimiter:  newRateLimiter(p1),
 	}
@@ -472,7 +487,7 @@ func TestRPC_LightClientUpdatesByRange(t *testing.T) {
 					t.Fatalf("unsupported version %d", i)
 				}
 
-				updates, err := r.lcStore.LightClientUpdates(ctx, 0, 4)
+				updates, err := r.lcStore.LightClientUpdates(ctx, 0, 4, signedBlk)
 				require.NoError(t, err)
 				updateSSZ, err := updates[uint64(responseCounter)].MarshalSSZ()
 				require.NoError(t, err)

beacon-chain/sync/service.go

@@ -17,10 +17,10 @@ import (
 	blockfeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/block"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/operation"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
-	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/execution"
+	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/light-client"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/blstoexec"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/slashings"
@@ -50,6 +50,7 @@ import (
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"github.com/trailofbits/go-mutexasserts"
+	"golang.org/x/sync/singleflight"
 )
 
 var _ runtime.Service = (*Service)(nil)
@@ -164,13 +165,15 @@ type Service struct {
 	syncContributionBitsOverlapLock  sync.RWMutex
 	syncContributionBitsOverlapCache *lru.Cache
 	signatureChan                    chan *signatureVerifier
+	kzgChan                          chan *kzgVerifier
 	clockWaiter                      startup.ClockWaiter
 	initialSyncComplete              chan struct{}
 	verifierWaiter                   *verification.InitializerWaiter
 	newBlobVerifier                  verification.NewBlobVerifier
 	newColumnsVerifier               verification.NewDataColumnsVerifier
+	columnSidecarsExecSingleFlight   singleflight.Group
+	reconstructionSingleFlight       singleflight.Group
 	availableBlocker                 coverage.AvailableBlocker
-	reconstructionLock               sync.Mutex
 	reconstructionRandGen            *rand.Rand
 	trackedValidatorsCache           *cache.TrackedValidatorsCache
 	ctxMap                           ContextByteVersions
@@ -203,6 +206,10 @@ func NewService(ctx context.Context, opts ...Option) *Service {
 	}
 	// Initialize signature channel with configured limit
 	r.signatureChan = make(chan *signatureVerifier, r.cfg.batchVerifierLimit)
+	// Initialize KZG channel with fixed buffer size of 100.
+	// This buffer size is designed to handle burst traffic of data column gossip messages:
+	// - Data columns arrive less frequently than attestations (default batchVerifierLimit=1000)
+	r.kzgChan = make(chan *kzgVerifier, 100)
 	// Correctly remove it from our seen pending block map.
 	// The eviction method always assumes that the mutex is held.
 	r.slotToPendingBlocks.OnEvicted(func(s string, i interface{}) {
@@ -255,6 +262,7 @@ func (s *Service) Start() {
 	s.newColumnsVerifier = newDataColumnsVerifierFromInitializer(v)
 
 	go s.verifierRoutine()
+	go s.kzgVerifierRoutine()
 	go s.startDiscoveryAndSubscriptions()
 	go s.processDataColumnLogs()
 

beacon-chain/sync/subscriber_beacon_blocks.go

@@ -5,16 +5,20 @@ import (
 	"fmt"
 	"os"
 	"path"
+	"time"
 
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/transition/interop"
 	"github.com/OffchainLabs/prysm/v6/config/features"
+	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	"github.com/OffchainLabs/prysm/v6/io/file"
 	"github.com/OffchainLabs/prysm/v6/runtime/version"
 	"github.com/OffchainLabs/prysm/v6/time/slots"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"google.golang.org/protobuf/proto"
 )
@@ -37,7 +41,12 @@ func (s *Service) beaconBlockSubscriber(ctx context.Context, msg proto.Message)
 		return err
 	}
 
-	go s.processSidecarsFromExecution(ctx, signed)
+	roBlock, err := blocks.NewROBlockWithRoot(signed, root)
+	if err != nil {
+		return errors.Wrap(err, "new ro block with root")
+	}
+
+	go s.processSidecarsFromExecutionFromBlock(ctx, roBlock)
 
 	if err := s.cfg.chain.ReceiveBlock(ctx, signed, root, nil); err != nil {
 		if blockchain.IsInvalidBlock(err) {
@@ -61,103 +70,21 @@ func (s *Service) beaconBlockSubscriber(ctx context.Context, msg proto.Message)
 	return err
 }
 
-// processSidecarsFromExecution retrieves (if available) sidecars data from the execution client,
+// 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) processSidecarsFromExecution(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock) {
-	if block.Version() >= version.Fulu {
-		s.processDataColumnSidecarsFromExecution(ctx, block)
-		return
-	}
-
-	if block.Version() >= version.Deneb {
-		s.processBlobSidecarsFromExecution(ctx, block)
-		return
-	}
-}
-
-// processDataColumnSidecarsFromExecution retrieves (if available) data column sidecars data from the execution client,
-// builds corresponding sidecars, save them to the storage, and broadcasts them over P2P if necessary.
-func (s *Service) processDataColumnSidecarsFromExecution(ctx context.Context, roSignedBlock interfaces.ReadOnlySignedBeaconBlock) {
-	block := roSignedBlock.Block()
-
-	log := log.WithFields(logrus.Fields{
-		"slot":          block.Slot(),
-		"proposerIndex": block.ProposerIndex(),
-	})
-
-	kzgCommitments, err := block.Body().BlobKzgCommitments()
-	if err != nil {
-		log.WithError(err).Error("Failed to read commitments from block")
-		return
-	}
-
-	if len(kzgCommitments) == 0 {
-		// No blobs to reconstruct.
-		return
-	}
-
-	blockRoot, err := block.HashTreeRoot()
-	if err != nil {
-		log.WithError(err).Error("Failed to calculate block root")
-		return
-	}
-
-	log = log.WithField("blockRoot", fmt.Sprintf("%#x", blockRoot))
-
-	if s.cfg.dataColumnStorage == nil {
-		log.Warning("Data column storage is not enabled, skip saving data column, but continue to reconstruct and broadcast data column")
-	}
-
-	// When this function is called, it's from the time when the block is received, so in almost all situations we need to get the data column from EL instead of the blob storage.
-	sidecars, err := s.cfg.executionReconstructor.ReconstructDataColumnSidecars(ctx, roSignedBlock, blockRoot)
-	if err != nil {
-		log.WithError(err).Debug("Cannot reconstruct data column sidecars after receiving the block")
-		return
-	}
-
-	// Return early if no blobs are retrieved from the EL.
-	if len(sidecars) == 0 {
-		return
-	}
-
-	nodeID := s.cfg.p2p.NodeID()
-	custodyGroupCount, err := s.cfg.p2p.CustodyGroupCount()
-	if err != nil {
-		log.WithError(err).Error("Failed to get custody group count")
-		return
-	}
-
-	info, _, err := peerdas.Info(nodeID, custodyGroupCount)
-	if err != nil {
-		log.WithError(err).Error("Failed to get peer info")
-		return
-	}
-
-	blockSlot := block.Slot()
-	proposerIndex := block.ProposerIndex()
-
-	// Broadcast and save data column sidecars to custody but not yet received.
-	sidecarCount := uint64(len(sidecars))
-	for columnIndex := range info.CustodyColumns {
-		log := log.WithField("columnIndex", columnIndex)
-		if columnIndex >= sidecarCount {
-			log.Error("Column custody index out of range - should never happen")
-			continue
+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 {
+			log.WithError(err).Error("Failed to process data column sidecars from execution")
+			return
 		}
 
-		if s.hasSeenDataColumnIndex(blockSlot, proposerIndex, columnIndex) {
-			continue
-		}
+		return
+	}
 
-		sidecar := sidecars[columnIndex]
-
-		if err := s.cfg.p2p.BroadcastDataColumnSidecar(blockRoot, sidecar.Index, sidecar.DataColumnSidecar); err != nil {
-			log.WithError(err).Error("Failed to broadcast data column")
-		}
-
-		if err := s.receiveDataColumnSidecar(ctx, sidecar); err != nil {
-			log.WithError(err).Error("Failed to receive data column")
-		}
+	if roBlock.Version() >= version.Deneb {
+		s.processBlobSidecarsFromExecution(ctx, roBlock)
+		return
 	}
 }
 
@@ -230,6 +157,170 @@ func (s *Service) processBlobSidecarsFromExecution(ctx context.Context, block in
 	}
 }
 
+// processDataColumnSidecarsFromExecution retrieves (if available) data column sidecars data from the execution client,
+// builds corresponding sidecars, save them to the storage, and broadcasts them over P2P if necessary.
+func (s *Service) processDataColumnSidecarsFromExecution(ctx context.Context, source peerdas.ConstructionPopulator) error {
+	key := fmt.Sprintf("%#x", source.Root())
+	if _, err, _ := s.columnSidecarsExecSingleFlight.Do(key, func() (interface{}, error) {
+		const delay = 250 * time.Millisecond
+		secondsPerHalfSlot := time.Duration(params.BeaconConfig().SecondsPerSlot/2) * time.Second
+
+		numberOfColumns := params.BeaconConfig().NumberOfColumns
+
+		commitments, err := source.Commitments()
+		if err != nil {
+			return nil, errors.Wrap(err, "blob kzg commitments")
+		}
+
+		// Exit early if there are no commitments.
+		if len(commitments) == 0 {
+			return nil, nil
+		}
+
+		// Retrieve the indices of sidecars we should sample.
+		columnIndicesToSample, err := s.columnIndicesToSample()
+		if err != nil {
+			return nil, errors.Wrap(err, "column indices to sample")
+		}
+
+		ctx, cancel := context.WithTimeout(ctx, secondsPerHalfSlot)
+		defer cancel()
+
+		for iteration := uint64(0); ; /*no stop condition*/ iteration++ {
+			// Exit early if all sidecars to sample have been seen.
+			if s.haveAllSidecarsBeenSeen(source.Slot(), source.ProposerIndex(), columnIndicesToSample) {
+				return nil, nil
+			}
+
+			// Try to reconstruct data column constructedSidecars from the execution client.
+			constructedSidecars, err := s.cfg.executionReconstructor.ConstructDataColumnSidecars(ctx, source)
+			if err != nil {
+				return nil, errors.Wrap(err, "reconstruct data column sidecars")
+			}
+
+			// No sidecars are retrieved from the EL, retry later
+			sidecarCount := uint64(len(constructedSidecars))
+			if sidecarCount == 0 {
+				if ctx.Err() != nil {
+					return nil, ctx.Err()
+				}
+
+				time.Sleep(delay)
+				continue
+			}
+
+			// Boundary check.
+			if sidecarCount != numberOfColumns {
+				return nil, errors.Errorf("reconstruct data column sidecars returned %d sidecars, expected %d - should never happen", sidecarCount, numberOfColumns)
+			}
+
+			unseenIndices, err := s.broadcastAndReceiveUnseenDataColumnSidecars(ctx, source.Slot(), source.ProposerIndex(), columnIndicesToSample, constructedSidecars)
+			if err != nil {
+				return nil, errors.Wrap(err, "broadcast and receive unseen data column sidecars")
+			}
+
+			if len(unseenIndices) > 0 {
+				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":       sortedSliceFromMap(unseenIndices),
+				}).Debug("Constructed data column sidecars from the execution client")
+			}
+
+			return nil, nil
+		}
+	}); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// broadcastAndReceiveUnseenDataColumnSidecars broadcasts and receives unseen data column sidecars.
+func (s *Service) broadcastAndReceiveUnseenDataColumnSidecars(
+	ctx context.Context,
+	slot primitives.Slot,
+	proposerIndex primitives.ValidatorIndex,
+	neededIndices map[uint64]bool,
+	sidecars []blocks.VerifiedRODataColumn,
+) (map[uint64]bool, error) {
+	// Compute sidecars we need to broadcast and receive.
+	unseenSidecars := make([]blocks.VerifiedRODataColumn, 0, len(sidecars))
+	unseenIndices := make(map[uint64]bool, len(sidecars))
+	for _, sidecar := range sidecars {
+		// Skip data column sidecars we don't need.
+		if !neededIndices[sidecar.Index] {
+			continue
+		}
+
+		// Skip already seen data column sidecars.
+		if s.hasSeenDataColumnIndex(slot, proposerIndex, sidecar.Index) {
+			continue
+		}
+
+		unseenSidecars = append(unseenSidecars, sidecar)
+		unseenIndices[sidecar.Index] = true
+	}
+
+	// Broadcast all the data column sidecars we reconstructed but did not see via gossip.
+	for _, sidecar := range unseenSidecars {
+		// Compute the subnet for this data column sidecar.
+		subnet := peerdas.ComputeSubnetForDataColumnSidecar(sidecar.Index)
+
+		// Broadcast the data column sidecar.
+		if err := s.cfg.p2p.BroadcastDataColumnSidecar(subnet, sidecar); err != nil {
+			// Don't return on error on broadcast failure, just log it.
+			log.WithError(err).Error("Broadcast data column")
+		}
+	}
+
+	// Receive data column sidecars.
+	if err := s.receiveDataColumnSidecars(ctx, unseenSidecars); err != nil {
+		return nil, errors.Wrap(err, "receive data column sidecars")
+	}
+
+	return unseenIndices, nil
+}
+
+// haveAllSidecarsBeenSeen checks if all sidecars for the given slot, proposer index, and data column indices have been seen.
+func (s *Service) haveAllSidecarsBeenSeen(slot primitives.Slot, proposerIndex primitives.ValidatorIndex, indices map[uint64]bool) bool {
+	for index := range indices {
+		if !s.hasSeenDataColumnIndex(slot, proposerIndex, index) {
+			return false
+		}
+	}
+	return true
+}
+
+// columnIndicesToSample returns the data column indices we should sample for the node.
+func (s *Service) columnIndicesToSample() (map[uint64]bool, error) {
+	// Retrieve our node ID.
+	nodeID := s.cfg.p2p.NodeID()
+
+	// Get the custody group sampling size for the node.
+	custodyGroupCount, err := s.cfg.p2p.CustodyGroupCount()
+	if err != nil {
+		return nil, errors.Wrap(err, "custody group count")
+	}
+
+	// Compute the sampling size.
+	// https://github.com/ethereum/consensus-specs/blob/master/specs/fulu/das-core.md#custody-sampling
+	samplesPerSlot := params.BeaconConfig().SamplesPerSlot
+	samplingSize := max(samplesPerSlot, custodyGroupCount)
+
+	// Get the peer info for the node.
+	peerInfo, _, err := peerdas.Info(nodeID, samplingSize)
+	if err != nil {
+		return nil, errors.Wrap(err, "peer info")
+	}
+
+	return peerInfo.CustodyColumns, nil
+}
+
 // WriteInvalidBlockToDisk as a block ssz. Writes to temp directory.
 func saveInvalidBlockToTemp(block interfaces.ReadOnlySignedBeaconBlock) {
 	if !features.Get().SaveInvalidBlock {

beacon-chain/sync/subscriber_beacon_blocks_test.go

@@ -1,7 +1,6 @@
 package sync
 
 import (
-	"context"
 	"testing"
 
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain"
@@ -135,7 +134,7 @@ func TestService_BeaconBlockSubscribe_UndefinedEeError(t *testing.T) {
 	require.Equal(t, 1, len(s.seenBlockCache.Keys()))
 }
 
-func TestReconstructAndBroadcastBlobs(t *testing.T) {
+func TestProcessSidecarsFromExecutionFromBlock(t *testing.T) {
 	t.Run("blobs", func(t *testing.T) {
 		rob, err := blocks.NewROBlob(
 			&ethpb.BlobSidecar{
@@ -158,6 +157,9 @@ func TestReconstructAndBroadcastBlobs(t *testing.T) {
 		sb, err := blocks.NewSignedBeaconBlock(b)
 		require.NoError(t, err)
 
+		roBlock, err := blocks.NewROBlock(sb)
+		require.NoError(t, err)
+
 		tests := []struct {
 			name              string
 			blobSidecars      []blocks.VerifiedROBlob
@@ -192,7 +194,7 @@ func TestReconstructAndBroadcastBlobs(t *testing.T) {
 					},
 					seenBlobCache: lruwrpr.New(1),
 				}
-				s.processSidecarsFromExecution(context.Background(), sb)
+				s.processSidecarsFromExecutionFromBlock(t.Context(), roBlock)
 				require.Equal(t, tt.expectedBlobCount, len(chainService.Blobs))
 			})
 		}
@@ -253,7 +255,7 @@ func TestReconstructAndBroadcastBlobs(t *testing.T) {
 				name:                    "Constructed 128 data columns with all blobs",
 				blobCount:               1,
 				dataColumnSidecars:      allColumns,
-				expectedDataColumnCount: 4, // default is 4
+				expectedDataColumnCount: 8,
 			},
 		}
 
@@ -261,10 +263,10 @@ func TestReconstructAndBroadcastBlobs(t *testing.T) {
 			t.Run(tt.name, func(t *testing.T) {
 				s := Service{
 					cfg: &config{
-						p2p:         mockp2p.NewTestP2P(t),
-						chain:       chainService,
-						clock:       startup.NewClock(time.Now(), [32]byte{}),
-						blobStorage: filesystem.NewEphemeralBlobStorage(t),
+						p2p:               mockp2p.NewTestP2P(t),
+						chain:             chainService,
+						clock:             startup.NewClock(time.Now(), [32]byte{}),
+						dataColumnStorage: filesystem.NewEphemeralDataColumnStorage(t),
 						executionReconstructor: &mockExecution.EngineClient{
 							DataColumnSidecars: tt.dataColumnSidecars,
 						},
@@ -288,10 +290,91 @@ func TestReconstructAndBroadcastBlobs(t *testing.T) {
 				sb, err := blocks.NewSignedBeaconBlock(b)
 				require.NoError(t, err)
 
-				s.processSidecarsFromExecution(context.Background(), sb)
+				roBlock, err := blocks.NewROBlock(sb)
+				require.NoError(t, err)
+
+				s.processSidecarsFromExecutionFromBlock(t.Context(), roBlock)
 				require.Equal(t, tt.expectedDataColumnCount, len(chainService.DataColumns))
 			})
 		}
 	})
-
+}
+
+func TestHaveAllSidecarsBeenSeen(t *testing.T) {
+	const (
+		slot          = 42
+		proposerIndex = 1664
+	)
+	service := NewService(t.Context(), WithP2P(mockp2p.NewTestP2P(t)))
+	service.initCaches()
+
+	service.setSeenDataColumnIndex(slot, proposerIndex, 1)
+	service.setSeenDataColumnIndex(slot, proposerIndex, 3)
+
+	testCases := []struct {
+		name     string
+		toSample map[uint64]bool
+		expected bool
+	}{
+		{
+			name:     "all sidecars seen",
+			toSample: map[uint64]bool{1: true, 3: true},
+			expected: true,
+		},
+		{
+			name:     "not all sidecars seen",
+			toSample: map[uint64]bool{1: true, 2: true, 3: true},
+			expected: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			actual := service.haveAllSidecarsBeenSeen(slot, proposerIndex, tc.toSample)
+			require.Equal(t, tc.expected, actual)
+		})
+	}
+}
+
+func TestColumnIndicesToSample(t *testing.T) {
+	const earliestAvailableSlot = 0
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig()
+	cfg.SamplesPerSlot = 4
+	params.OverrideBeaconConfig(cfg)
+
+	testCases := []struct {
+		name              string
+		custodyGroupCount uint64
+		expected          map[uint64]bool
+	}{
+		{
+			name:              "custody group count lower than samples per slot",
+			custodyGroupCount: 3,
+			expected:          map[uint64]bool{1: true, 17: true, 87: true, 102: true},
+		},
+		{
+			name:              "custody group count higher than samples per slot",
+			custodyGroupCount: 5,
+			expected:          map[uint64]bool{1: true, 17: true, 75: true, 87: true, 102: true},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			p2p := mockp2p.NewTestP2P(t)
+			_, _, err := p2p.UpdateCustodyInfo(earliestAvailableSlot, tc.custodyGroupCount)
+			require.NoError(t, err)
+
+			service := NewService(t.Context(), WithP2P(p2p))
+
+			actual, err := service.columnIndicesToSample()
+			require.NoError(t, err)
+
+			require.Equal(t, len(tc.expected), len(actual))
+			for index := range tc.expected {
+				require.Equal(t, true, actual[index])
+			}
+		})
+	}
 }