Event data use cached proposer index

* comment updates and changelog

* some missed comments

CHANGELOG.md

@@ -4,6 +4,64 @@ All notable changes to this project will be documented in this file.
 
 The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.
 
+## [v6.0.0](https://github.com/prysmaticlabs/prysm/compare/v5.3.2...v6.0.0) - 2025-04-21
+
+This release introduces Mainnet support for the upcoming Electra + Prague (Pectra) fork. The fork is scheduled for mainnet epoch 364032 (May 7, 2025, 10:05:11 UTC). You MUST update Prysm Beacon Node, Prysm Validator Client, and your execution layer client to the Pectra ready release prior to the fork to stay on the correct chain.
+
+Besides Pectra, we have more light client API support, cleanups, and a few bugfixes. Please review the changelog below and update your client as soon as practical before May 7.
+
+This release is **mandatory** for all operators before May 7.
+
+### Added
+
+- Implemented validator identities Beacon API endpoint. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15086)
+- Add SSZ support to light client updates by range API. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15082)
+- Add light client ssz types to the spec test. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15097)
+- Added the ability for execution requests to be tested in e2e with electra. [[PR]](https://github.com/prysmaticlabs/prysm/pull/14971)
+- Add warning messages for gas limit ranges that might be problematic. Low gas limits (≤10% of default) may cause transactions to fail, while high gas limits (>150% of default) could lead to block propagation issues. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15078)
+- Add light client store object to the beacon node object. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15120)
+- prysmctl option in wrapper script to generate devnet ssz. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15145)
+- Add support for Electra fork epoch. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15132)
+
+### Changed
+
+- The validator client will no longer use the full list of committee values but instead use the committee length and validator committee index. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15039)
+- Remove the header `Content-Disposition` from the `httputil.WriteSSZ` function. No `filename` parameter is needed anymore. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15092)
+- Sort attestations in proposer block by reward. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15093)
+- More efficient query method for stategen to retrieve blocks between a given state and the replay target block. This avoids attempting to look up blocks that are not needed for head replay queries, which may be missing due to a previous rollback bug. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15063)
+- removed old web3signer metrics in favor for a universal one. [[PR]](https://github.com/prysmaticlabs/prysm/pull/14920)
+- Deprecated everything related with the gRPC API. [[PR]](https://github.com/prysmaticlabs/prysm/pull/14944)
+- Migrate Prysm repo to Offchain Labs organization ahead of Pectra upgrade v6. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15140)
+
+### Deprecated
+
+- deprecates and removes usage of the `--trace` flag and`--cpuprofile` flag in favor of just using `--pprof`. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15083)
+
+### Removed
+
+- Remove /eth/v1/beacon/states/head/committees call when getting duties. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15039)
+- Removed unused hack scripts. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15157)
+- Remove `disable-committee-aware-packing` flag. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15162)
+- Remove deprecated flags for the major release. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15165)
+- Removed Beacon API endpoints which have been deprecated at the Deneb fork. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15166)
+
+### Fixed
+
+- The `--rpc` flag will now properly enable the keymanager APIs without web. The `--web` will enable both validator api endpoints and web. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15080)
+- Use latest state to pack attestation. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15113)
+- Clean up dangling block index entries for blocks that were previously deleted by incomplete cleanup code. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15040)
+- Fixed to use io stream instead of stream read. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15089)
+- When using a DV, send all aggregations for a slot and committee. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15110)
+- Fixed a bug in consolidation request processing. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15122)
+- Fix State Getter for pending withdrawal balance. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15123)
+- Fixed a bug in checking for attestation lengths in our block. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15134)
+- Fix Committee Index Check For Aggregates. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15146)
+- Fix filtering by committee index post-Electra in `ListAttestationsV2`. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15148)
+- Peers giving invalid data in range syncing are now downscored. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15149)
+- Adding fork guard to attestation api endpoints so that it doesn't accidentally include wrong attestation types in the pool. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15161)
+- fixed underflow with balances in leaking edge case with expected withdrawals. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15191)
+- Attribute block and blob issues to correct peers during range syncing. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15173)
+
 ## [v5.3.2](https://github.com/prysmaticlabs/prysm/compare/v5.3.1...v5.3.2) - 2025-03-25
 
 This release introduces support for the `Hoodi` testnet.
@@ -3255,4 +3313,4 @@ There are no security updates in this release.
 
 # Older than v2.0.0
 
-For changelog history for releases older than v2.0.0, please refer to https://github.com/prysmaticlabs/prysm/releases
+For changelog history for releases older than v2.0.0, please refer to https://github.com/prysmaticlabs/prysm/releases

api/server/structs/endpoints_beacon.go

@@ -263,6 +263,13 @@ type ChainHead struct {
 	OptimisticStatus           bool   `json:"optimistic_status"`
 }
 
+type GetPendingConsolidationsResponse struct {
+	Version             string                  `json:"version"`
+	ExecutionOptimistic bool                    `json:"execution_optimistic"`
+	Finalized           bool                    `json:"finalized"`
+	Data                []*PendingConsolidation `json:"data"`
+}
+
 type GetPendingDepositsResponse struct {
 	Version             string            `json:"version"`
 	ExecutionOptimistic bool              `json:"execution_optimistic"`

beacon-chain/blockchain/chain_info.go

@@ -51,6 +51,7 @@ type ForkchoiceFetcher interface {
 	ProposerBoost() [32]byte
 	RecentBlockSlot(root [32]byte) (primitives.Slot, error)
 	IsCanonical(ctx context.Context, blockRoot [32]byte) (bool, error)
+	DependentRoot(primitives.Epoch) ([32]byte, error)
 }
 
 // TimeFetcher retrieves the Ethereum consensus data that's related to time.

beacon-chain/blockchain/execution_engine.go

@@ -184,13 +184,13 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *fcuConfig) (*
 	return payloadID, nil
 }
 
-func firePayloadAttributesEvent(_ context.Context, f event.SubscriberSender, nextSlot primitives.Slot) {
+func firePayloadAttributesEvent(f event.SubscriberSender, block interfaces.ReadOnlySignedBeaconBlock, root [32]byte, nextSlot primitives.Slot) {
 	// the fcu args have differing amounts of completeness based on the code path,
 	// and there is work we only want to do if a client is actually listening to the events beacon api endpoint.
 	// temporary solution: just fire a blank event and fill in the details in the api handler.
 	f.Send(&feed.Event{
 		Type: statefeed.PayloadAttributes,
-		Data: payloadattribute.EventData{ProposalSlot: nextSlot},
+		Data: payloadattribute.EventData{HeadBlock: block, HeadRoot: root, ProposalSlot: nextSlot},
 	})
 }
 

beacon-chain/blockchain/forkchoice_update_execution.go

@@ -102,7 +102,7 @@ func (s *Service) forkchoiceUpdateWithExecution(ctx context.Context, args *fcuCo
 		log.WithError(err).Error("could not save head")
 	}
 
-	go firePayloadAttributesEvent(ctx, s.cfg.StateNotifier.StateFeed(), s.CurrentSlot()+1)
+	go firePayloadAttributesEvent(s.cfg.StateNotifier.StateFeed(), args.headBlock, args.headRoot, s.CurrentSlot()+1)
 
 	// Only need to prune attestations from pool if the head has changed.
 	s.pruneAttsFromPool(s.ctx, args.headState, args.headBlock)

beacon-chain/blockchain/kzg/BUILD.bazel

@@ -3,15 +3,19 @@ load("@prysm//tools/go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = [
+        "kzg.go",
         "trusted_setup.go",
         "validation.go",
     ],
-    embedsrcs = ["trusted_setup.json"],
+    embedsrcs = ["trusted_setup_4096.json"],
     importpath = "github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg",
     visibility = ["//visibility:public"],
     deps = [
         "//consensus-types/blocks:go_default_library",
         "@com_github_crate_crypto_go_kzg_4844//:go_default_library",
+        "@com_github_ethereum_c_kzg_4844//bindings/go:go_default_library",
+        "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
+        "@com_github_ethereum_go_ethereum//crypto/kzg4844:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
     ],
 )

beacon-chain/blockchain/kzg/kzg.go

@@ -0,0 +1,143 @@
+package kzg
+
+import (
+	"github.com/pkg/errors"
+
+	ckzg4844 "github.com/ethereum/c-kzg-4844/v2/bindings/go"
+	"github.com/ethereum/go-ethereum/crypto/kzg4844"
+)
+
+// BytesPerBlob is the number of bytes in a single blob.
+const BytesPerBlob = ckzg4844.BytesPerBlob
+
+// Blob represents a serialized chunk of data.
+type Blob [BytesPerBlob]byte
+
+// BytesPerCell is the number of bytes in a single cell.
+const BytesPerCell = ckzg4844.BytesPerCell
+
+// Cell represents a chunk of an encoded Blob.
+type Cell [BytesPerCell]byte
+
+// Commitment represent a KZG commitment to a Blob.
+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
+
+// Bytes48 is a 48-byte array.
+type Bytes48 = ckzg4844.Bytes48
+
+// Bytes32 is a 32-byte array.
+type Bytes32 = ckzg4844.Bytes32
+
+// CellsAndProofs represents the Cells and Proofs corresponding to a single blob.
+type CellsAndProofs struct {
+	Cells  []Cell
+	Proofs []Proof
+}
+
+// BlobToKZGCommitment computes a KZG commitment from a given blob.
+func BlobToKZGCommitment(blob *Blob) (Commitment, error) {
+	var kzgBlob kzg4844.Blob
+	copy(kzgBlob[:], blob[:])
+
+	commitment, err := kzg4844.BlobToCommitment(&kzgBlob)
+	if err != nil {
+		return Commitment{}, err
+	}
+
+	return Commitment(commitment), nil
+}
+
+// ComputeCells computes the (extended) cells from a given blob.
+func ComputeCells(blob *Blob) ([]Cell, error) {
+	var ckzgBlob ckzg4844.Blob
+	copy(ckzgBlob[:], blob[:])
+
+	ckzgCells, err := ckzg4844.ComputeCells(&ckzgBlob)
+	if err != nil {
+		return nil, errors.Wrap(err, "compute cells")
+	}
+
+	cells := make([]Cell, len(ckzgCells))
+	for i := range ckzgCells {
+		cells[i] = Cell(ckzgCells[i])
+	}
+
+	return cells, nil
+}
+
+// ComputeBlobKZGProof computes the blob KZG proof from a given blob and its commitment.
+func ComputeBlobKZGProof(blob *Blob, commitment Commitment) (Proof, error) {
+	var kzgBlob kzg4844.Blob
+	copy(kzgBlob[:], blob[:])
+
+	proof, err := kzg4844.ComputeBlobProof(&kzgBlob, kzg4844.Commitment(commitment))
+	if err != nil {
+		return [48]byte{}, err
+	}
+	return Proof(proof), nil
+}
+
+// ComputeCellsAndKZGProofs computes the cells and cells KZG proofs from a given blob.
+func ComputeCellsAndKZGProofs(blob *Blob) (CellsAndProofs, error) {
+	var ckzgBlob ckzg4844.Blob
+	copy(ckzgBlob[:], blob[:])
+
+	ckzgCells, ckzgProofs, err := ckzg4844.ComputeCellsAndKZGProofs(&ckzgBlob)
+	if err != nil {
+		return CellsAndProofs{}, err
+	}
+
+	return makeCellsAndProofs(ckzgCells[:], ckzgProofs[:])
+}
+
+// VerifyCellKZGProofBatch verifies the KZG proofs for a given slice of commitments, cells indices, cells and proofs.
+// Note: It is way more efficient to call once this function with big slices than calling it multiple times with small slices.
+func VerifyCellKZGProofBatch(commitmentsBytes []Bytes48, cellIndices []uint64, cells []Cell, proofsBytes []Bytes48) (bool, error) {
+	// Convert `Cell` type to `ckzg4844.Cell`
+	ckzgCells := make([]ckzg4844.Cell, len(cells))
+
+	for i := range cells {
+		ckzgCells[i] = ckzg4844.Cell(cells[i])
+	}
+
+	return ckzg4844.VerifyCellKZGProofBatch(commitmentsBytes, cellIndices, ckzgCells, proofsBytes)
+}
+
+// RecoverCellsAndKZGProofs recovers the complete cells and KZG proofs from a given set of cell indices and partial cells.
+func RecoverCellsAndKZGProofs(cellIndices []uint64, partialCells []Cell) (CellsAndProofs, error) {
+	// Convert `Cell` type to `ckzg4844.Cell`
+	ckzgPartialCells := make([]ckzg4844.Cell, len(partialCells))
+	for i := range partialCells {
+		ckzgPartialCells[i] = ckzg4844.Cell(partialCells[i])
+	}
+
+	ckzgCells, ckzgProofs, err := ckzg4844.RecoverCellsAndKZGProofs(cellIndices, ckzgPartialCells)
+	if err != nil {
+		return CellsAndProofs{}, errors.Wrap(err, "recover cells and KZG proofs")
+	}
+
+	return makeCellsAndProofs(ckzgCells[:], ckzgProofs[:])
+}
+
+// makeCellsAndProofs converts cells/proofs to the CellsAndProofs type defined in this package.
+func makeCellsAndProofs(ckzgCells []ckzg4844.Cell, ckzgProofs []ckzg4844.KZGProof) (CellsAndProofs, error) {
+	if len(ckzgCells) != len(ckzgProofs) {
+		return CellsAndProofs{}, errors.New("different number of cells/proofs")
+	}
+
+	cells := make([]Cell, 0, len(ckzgCells))
+	proofs := make([]Proof, 0, len(ckzgProofs))
+
+	for i := range ckzgCells {
+		cells = append(cells, Cell(ckzgCells[i]))
+		proofs = append(proofs, Proof(ckzgProofs[i]))
+	}
+
+	return CellsAndProofs{
+		Cells:  cells,
+		Proofs: proofs,
+	}, nil
+}

beacon-chain/blockchain/kzg/trusted_setup.go

@@ -5,24 +5,69 @@ import (
 	"encoding/json"
 
 	GoKZG "github.com/crate-crypto/go-kzg-4844"
+	CKZG "github.com/ethereum/c-kzg-4844/v2/bindings/go"
+	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/pkg/errors"
 )
 
 var (
-	//go:embed trusted_setup.json
+	// https://github.com/ethereum/consensus-specs/blob/dev/presets/mainnet/trusted_setups/trusted_setup_4096.json
+	//go:embed trusted_setup_4096.json
 	embeddedTrustedSetup []byte // 1.2Mb
 	kzgContext           *GoKZG.Context
+	kzgLoaded            bool
 )
 
+type TrustedSetup struct {
+	G1Monomial [GoKZG.ScalarsPerBlob]GoKZG.G1CompressedHexStr `json:"g1_monomial"`
+	G1Lagrange [GoKZG.ScalarsPerBlob]GoKZG.G1CompressedHexStr `json:"g1_lagrange"`
+	G2Monomial [65]GoKZG.G2CompressedHexStr                   `json:"g2_monomial"`
+}
+
 func Start() error {
-	parsedSetup := GoKZG.JSONTrustedSetup{}
-	err := json.Unmarshal(embeddedTrustedSetup, &parsedSetup)
+	trustedSetup := &TrustedSetup{}
+	err := json.Unmarshal(embeddedTrustedSetup, trustedSetup)
 	if err != nil {
 		return errors.Wrap(err, "could not parse trusted setup JSON")
 	}
-	kzgContext, err = GoKZG.NewContext4096(&parsedSetup)
+
+	kzgContext, err = GoKZG.NewContext4096(&GoKZG.JSONTrustedSetup{
+		SetupG2:         trustedSetup.G2Monomial[:],
+		SetupG1Lagrange: trustedSetup.G1Lagrange,
+	})
 	if err != nil {
 		return errors.Wrap(err, "could not initialize go-kzg context")
 	}
+
+	// Length of a G1 point, converted from hex to binary.
+	g1MonomialBytes := make([]byte, len(trustedSetup.G1Monomial)*(len(trustedSetup.G1Monomial[0])-2)/2)
+	for i, g1 := range &trustedSetup.G1Monomial {
+		copy(g1MonomialBytes[i*(len(g1)-2)/2:], hexutil.MustDecode(g1))
+	}
+
+	// Length of a G1 point, converted from hex to binary.
+	g1LagrangeBytes := make([]byte, len(trustedSetup.G1Lagrange)*(len(trustedSetup.G1Lagrange[0])-2)/2)
+	for i, g1 := range &trustedSetup.G1Lagrange {
+		copy(g1LagrangeBytes[i*(len(g1)-2)/2:], hexutil.MustDecode(g1))
+	}
+
+	// Length of a G2 point, converted from hex to binary.
+	g2MonomialBytes := make([]byte, len(trustedSetup.G2Monomial)*(len(trustedSetup.G2Monomial[0])-2)/2)
+	for i, g2 := range &trustedSetup.G2Monomial {
+		copy(g2MonomialBytes[i*(len(g2)-2)/2:], hexutil.MustDecode(g2))
+	}
+
+	if !kzgLoaded {
+		const precompute uint = 8
+
+		kzgLoaded = true
+
+		// Free the current trusted setup before running this method.
+		// CKZG panics if the same setup is run multiple times.
+		if err = CKZG.LoadTrustedSetup(g1MonomialBytes, g1LagrangeBytes, g2MonomialBytes, precompute); err != nil {
+			return errors.Wrap(err, "load trust setup")
+		}
+	}
+
 	return nil
 }

beacon-chain/blockchain/options.go

@@ -4,6 +4,7 @@ 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"
@@ -220,3 +221,10 @@ func WithSlasherEnabled(enabled bool) Option {
 		return nil
 	}
 }
+
+func WithLightClientStore(lcs *lightclient.Store) Option {
+	return func(s *Service) error {
+		s.lcStore = lcs
+		return nil
+	}
+}

beacon-chain/blockchain/process_block.go

@@ -729,9 +729,13 @@ func (s *Service) lateBlockTasks(ctx context.Context) {
 	attribute := s.getPayloadAttribute(ctx, headState, s.CurrentSlot()+1, headRoot[:])
 	// return early if we are not proposing next slot
 	if attribute.IsEmpty() {
+		headBlock, err := s.headBlock()
+		if err != nil {
+			log.WithError(err).WithField("head_root", headRoot).Error("unable to retrieve head block to fire payload attributes event")
+		}
 		// notifyForkchoiceUpdate fires the payload attribute event. But in this case, we won't
 		// call notifyForkchoiceUpdate, so the event is fired here.
-		go firePayloadAttributesEvent(ctx, s.cfg.StateNotifier.StateFeed(), s.CurrentSlot()+1)
+		go firePayloadAttributesEvent(s.cfg.StateNotifier.StateFeed(), headBlock, headRoot, s.CurrentSlot()+1)
 		return
 	}
 

beacon-chain/blockchain/process_block_helpers.go

@@ -254,7 +254,7 @@ func (s *Service) processLightClientFinalityUpdate(
 		return errors.Wrapf(err, "could not get finalized block for root %#x", finalizedRoot)
 	}
 
-	update, err := lightclient.NewLightClientFinalityUpdateFromBeaconState(
+	newUpdate, err := lightclient.NewLightClientFinalityUpdateFromBeaconState(
 		ctx,
 		postState.Slot(),
 		postState,
@@ -268,9 +268,32 @@ func (s *Service) processLightClientFinalityUpdate(
 		return errors.Wrap(err, "could not create light client finality update")
 	}
 
+	lastUpdate := s.lcStore.LastFinalityUpdate()
+	if lastUpdate != nil {
+		// The finalized_header.beacon.lastUpdateSlot is greater than that of all previously forwarded finality_updates,
+		// or it matches the highest previously forwarded lastUpdateSlot and also has a sync_aggregate indicating supermajority (> 2/3)
+		// sync committee participation while the previously forwarded finality_update for that lastUpdateSlot did not indicate supermajority
+		newUpdateSlot := newUpdate.FinalizedHeader().Beacon().Slot
+		newHasSupermajority := lightclient.UpdateHasSupermajority(newUpdate.SyncAggregate())
+
+		lastUpdateSlot := lastUpdate.FinalizedHeader().Beacon().Slot
+		lastHasSupermajority := lightclient.UpdateHasSupermajority(lastUpdate.SyncAggregate())
+
+		if newUpdateSlot < lastUpdateSlot {
+			log.Debug("Skip saving light client finality newUpdate: Older than local newUpdate")
+			return nil
+		}
+		if newUpdateSlot == lastUpdateSlot && (lastHasSupermajority || !newHasSupermajority) {
+			log.Debug("Skip saving light client finality update: No supermajority advantage")
+			return nil
+		}
+	}
+	log.Debug("Saving new light client finality update")
+	s.lcStore.SetLastFinalityUpdate(newUpdate)
+
 	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 		Type: statefeed.LightClientFinalityUpdate,
-		Data: update,
+		Data: newUpdate,
 	})
 	return nil
 }
@@ -287,7 +310,7 @@ func (s *Service) processLightClientOptimisticUpdate(ctx context.Context, signed
 		return errors.Wrapf(err, "could not get attested state for root %#x", attestedRoot)
 	}
 
-	update, err := lightclient.NewLightClientOptimisticUpdateFromBeaconState(
+	newUpdate, err := lightclient.NewLightClientOptimisticUpdateFromBeaconState(
 		ctx,
 		postState.Slot(),
 		postState,
@@ -304,9 +327,21 @@ func (s *Service) processLightClientOptimisticUpdate(ctx context.Context, signed
 		return errors.Wrap(err, "could not create light client optimistic update")
 	}
 
+	lastUpdate := s.lcStore.LastOptimisticUpdate()
+	if lastUpdate != nil {
+		// The attested_header.beacon.slot is greater than that of all previously forwarded optimistic updates
+		if newUpdate.AttestedHeader().Beacon().Slot <= lastUpdate.AttestedHeader().Beacon().Slot {
+			log.Debug("Skip saving light client optimistic update: Older than local update")
+			return nil
+		}
+	}
+
+	log.Debug("Saving new light client optimistic update")
+	s.lcStore.SetLastOptimisticUpdate(newUpdate)
+
 	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 		Type: statefeed.LightClientOptimisticUpdate,
-		Data: update,
+		Data: newUpdate,
 	})
 
 	return nil

beacon-chain/blockchain/process_block_test.go

@@ -2653,7 +2653,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 
 	t.Run("Altair", func(t *testing.T) {
 		t.Run("No old update", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestAltair(0, true)
+			l := util.NewTestLightClient(t, version.Altair)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().AltairForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -2699,7 +2699,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 		})
 
 		t.Run("New update is better", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestAltair(0, true)
+			l := util.NewTestLightClient(t, version.Altair)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().AltairForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -2751,7 +2751,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 		})
 
 		t.Run("Old update is better", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestAltair(0, false)
+			l := util.NewTestLightClient(t, version.Altair)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().AltairForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -2812,7 +2812,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 
 	t.Run("Capella", func(t *testing.T) {
 		t.Run("No old update", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapella(false, 0, true)
+			l := util.NewTestLightClient(t, version.Capella)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().CapellaForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -2857,7 +2857,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 		})
 
 		t.Run("New update is better", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapella(false, 0, true)
+			l := util.NewTestLightClient(t, version.Capella)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().CapellaForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -2909,7 +2909,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 		})
 
 		t.Run("Old update is better", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapella(false, 0, false)
+			l := util.NewTestLightClient(t, version.Capella)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().CapellaForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -2970,7 +2970,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 
 	t.Run("Deneb", func(t *testing.T) {
 		t.Run("No old update", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestDeneb(false, 0, true)
+			l := util.NewTestLightClient(t, version.Deneb)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().DenebForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -3015,7 +3015,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 		})
 
 		t.Run("New update is better", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestDeneb(false, 0, true)
+			l := util.NewTestLightClient(t, version.Deneb)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().DenebForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -3067,7 +3067,7 @@ func TestSaveLightClientUpdate(t *testing.T) {
 		})
 
 		t.Run("Old update is better", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestDeneb(false, 0, false)
+			l := util.NewTestLightClient(t, version.Deneb)
 
 			s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().DenebForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -3138,7 +3138,7 @@ func TestSaveLightClientBootstrap(t *testing.T) {
 	ctx := tr.ctx
 
 	t.Run("Altair", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestAltair(0, true)
+		l := util.NewTestLightClient(t, version.Altair)
 
 		s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().AltairForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -3173,7 +3173,7 @@ func TestSaveLightClientBootstrap(t *testing.T) {
 	})
 
 	t.Run("Capella", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestCapella(false, 0, true)
+		l := util.NewTestLightClient(t, version.Capella)
 
 		s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().CapellaForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -3208,7 +3208,7 @@ func TestSaveLightClientBootstrap(t *testing.T) {
 	})
 
 	t.Run("Deneb", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestDeneb(false, 0, true)
+		l := util.NewTestLightClient(t, version.Deneb)
 
 		s.genesisTime = time.Unix(time.Now().Unix()-(int64(params.BeaconConfig().DenebForkEpoch)*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot)), 0)
 
@@ -3244,3 +3244,338 @@ func TestSaveLightClientBootstrap(t *testing.T) {
 
 	reset()
 }
+
+func setupLightClientTestRequirements(ctx context.Context, t *testing.T, s *Service, v int, options ...util.LightClientOption) (*util.TestLightClient, *postBlockProcessConfig) {
+	var l *util.TestLightClient
+	switch v {
+	case version.Altair:
+		l = util.NewTestLightClient(t, version.Altair, options...)
+	case version.Bellatrix:
+		l = util.NewTestLightClient(t, version.Bellatrix, options...)
+	case version.Capella:
+		l = util.NewTestLightClient(t, version.Capella, options...)
+	case version.Deneb:
+		l = util.NewTestLightClient(t, version.Deneb, options...)
+	case version.Electra:
+		l = util.NewTestLightClient(t, version.Electra, options...)
+	default:
+		t.Errorf("Unsupported fork version %s", version.String(v))
+		return nil, nil
+	}
+
+	err := s.cfg.BeaconDB.SaveBlock(ctx, l.AttestedBlock)
+	require.NoError(t, err)
+	attestedBlockRoot, err := l.AttestedBlock.Block().HashTreeRoot()
+	require.NoError(t, err)
+	err = s.cfg.BeaconDB.SaveState(ctx, l.AttestedState, attestedBlockRoot)
+	require.NoError(t, err)
+
+	currentBlockRoot, err := l.Block.Block().HashTreeRoot()
+	require.NoError(t, err)
+	roblock, err := consensusblocks.NewROBlockWithRoot(l.Block, currentBlockRoot)
+	require.NoError(t, err)
+
+	err = s.cfg.BeaconDB.SaveBlock(ctx, roblock)
+	require.NoError(t, err)
+	err = s.cfg.BeaconDB.SaveState(ctx, l.State, currentBlockRoot)
+	require.NoError(t, err)
+
+	err = s.cfg.BeaconDB.SaveBlock(ctx, l.FinalizedBlock)
+	require.NoError(t, err)
+
+	cfg := &postBlockProcessConfig{
+		ctx:            ctx,
+		roblock:        roblock,
+		postState:      l.State,
+		isValidPayload: true,
+	}
+
+	return l, cfg
+}
+
+func TestProcessLightClientOptimisticUpdate(t *testing.T) {
+	featCfg := &features.Flags{}
+	featCfg.EnableLightClient = true
+	reset := features.InitWithReset(featCfg)
+	defer reset()
+
+	params.SetupTestConfigCleanup(t)
+	beaconCfg := params.BeaconConfig()
+	beaconCfg.AltairForkEpoch = 1
+	beaconCfg.BellatrixForkEpoch = 2
+	beaconCfg.CapellaForkEpoch = 3
+	beaconCfg.DenebForkEpoch = 4
+	beaconCfg.ElectraForkEpoch = 5
+	params.OverrideBeaconConfig(beaconCfg)
+
+	s, tr := minimalTestService(t)
+	ctx := tr.ctx
+
+	testCases := []struct {
+		name          string
+		oldOptions    []util.LightClientOption
+		newOptions    []util.LightClientOption
+		expectReplace bool
+	}{
+		{
+			name:          "No old update",
+			oldOptions:    nil,
+			newOptions:    []util.LightClientOption{},
+			expectReplace: true,
+		},
+		{
+			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
+			expectReplace: false,
+		},
+		{
+			name:          "Old update is better - age",
+			oldOptions:    []util.LightClientOption{util.WithIncreasedAttestedSlot(1)},
+			newOptions:    []util.LightClientOption{},
+			expectReplace: false,
+		},
+		{
+			name:          "New update is better - age",
+			oldOptions:    []util.LightClientOption{},
+			newOptions:    []util.LightClientOption{util.WithIncreasedAttestedSlot(1)},
+			expectReplace: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		for testVersion := 1; testVersion < 6; testVersion++ { // test all forks
+			var forkEpoch uint64
+			var expectedVersion int
+
+			switch testVersion {
+			case 1:
+				forkEpoch = uint64(params.BeaconConfig().AltairForkEpoch)
+				expectedVersion = version.Altair
+			case 2:
+				forkEpoch = uint64(params.BeaconConfig().BellatrixForkEpoch)
+				expectedVersion = version.Altair
+			case 3:
+				forkEpoch = uint64(params.BeaconConfig().CapellaForkEpoch)
+				expectedVersion = version.Capella
+			case 4:
+				forkEpoch = uint64(params.BeaconConfig().DenebForkEpoch)
+				expectedVersion = version.Deneb
+			case 5:
+				forkEpoch = uint64(params.BeaconConfig().ElectraForkEpoch)
+				expectedVersion = version.Deneb
+			default:
+				t.Errorf("Unsupported fork version %s", version.String(testVersion))
+			}
+
+			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.Store{}
+
+				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))
+
+					oldActualUpdate, err = lightClient.NewLightClientOptimisticUpdateFromBeaconState(
+						lOld.Ctx,
+						lOld.State.Slot(),
+						lOld.State,
+						lOld.Block,
+						lOld.AttestedState,
+						lOld.AttestedBlock,
+					)
+					require.NoError(t, err)
+
+					// check that the old update is saved
+					oldUpdate := s.lcStore.LastOptimisticUpdate()
+					require.NotNil(t, oldUpdate)
+
+					require.DeepEqual(t, oldUpdate, oldActualUpdate, "old update should be saved")
+				}
+
+				// config for new update
+				lNew, cfgNew := setupLightClientTestRequirements(ctx, t, s, testVersion, tc.newOptions...)
+				require.NoError(t, s.processLightClientOptimisticUpdate(cfgNew.ctx, cfgNew.roblock, cfgNew.postState))
+
+				newActualUpdate, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(
+					lNew.Ctx,
+					lNew.State.Slot(),
+					lNew.State,
+					lNew.Block,
+					lNew.AttestedState,
+					lNew.AttestedBlock,
+				)
+				require.NoError(t, err)
+
+				require.DeepNotEqual(t, newActualUpdate, oldActualUpdate, "new update should not be equal to old update")
+
+				// check that the new update is saved or skipped
+				newUpdate := s.lcStore.LastOptimisticUpdate()
+				require.NotNil(t, newUpdate)
+
+				if tc.expectReplace {
+					require.DeepEqual(t, newActualUpdate, newUpdate)
+					require.Equal(t, expectedVersion, newUpdate.Version())
+				} else {
+					require.DeepEqual(t, oldActualUpdate, newUpdate)
+					require.Equal(t, expectedVersion, newUpdate.Version())
+				}
+			})
+		}
+	}
+}
+
+func TestProcessLightClientFinalityUpdate(t *testing.T) {
+	featCfg := &features.Flags{}
+	featCfg.EnableLightClient = true
+	reset := features.InitWithReset(featCfg)
+	defer reset()
+
+	params.SetupTestConfigCleanup(t)
+	beaconCfg := params.BeaconConfig()
+	beaconCfg.AltairForkEpoch = 1
+	beaconCfg.BellatrixForkEpoch = 2
+	beaconCfg.CapellaForkEpoch = 3
+	beaconCfg.DenebForkEpoch = 4
+	beaconCfg.ElectraForkEpoch = 5
+	params.OverrideBeaconConfig(beaconCfg)
+
+	s, tr := minimalTestService(t)
+	ctx := tr.ctx
+
+	testCases := []struct {
+		name          string
+		oldOptions    []util.LightClientOption
+		newOptions    []util.LightClientOption
+		expectReplace bool
+	}{
+		{
+			name:          "No old update",
+			oldOptions:    nil,
+			newOptions:    []util.LightClientOption{},
+			expectReplace: true,
+		},
+		{
+			name:          "Old update is better - age - no supermajority",
+			oldOptions:    []util.LightClientOption{util.WithIncreasedFinalizedSlot(1)},
+			newOptions:    []util.LightClientOption{},
+			expectReplace: false,
+		},
+		{
+			name:          "Old update is better - age - both supermajority",
+			oldOptions:    []util.LightClientOption{util.WithIncreasedFinalizedSlot(1), util.WithSupermajority()},
+			newOptions:    []util.LightClientOption{util.WithSupermajority()},
+			expectReplace: false,
+		},
+		{
+			name:          "Old update is better - supermajority",
+			oldOptions:    []util.LightClientOption{util.WithSupermajority()},
+			newOptions:    []util.LightClientOption{},
+			expectReplace: false,
+		},
+		{
+			name:          "New update is better - age - both supermajority",
+			oldOptions:    []util.LightClientOption{util.WithSupermajority()},
+			newOptions:    []util.LightClientOption{util.WithIncreasedFinalizedSlot(1), util.WithSupermajority()},
+			expectReplace: true,
+		},
+		{
+			name:          "New update is better - age - no supermajority",
+			oldOptions:    []util.LightClientOption{},
+			newOptions:    []util.LightClientOption{util.WithIncreasedFinalizedSlot(1)},
+			expectReplace: true,
+		},
+		{
+			name:          "New update is better - supermajority",
+			oldOptions:    []util.LightClientOption{},
+			newOptions:    []util.LightClientOption{util.WithSupermajority()},
+			expectReplace: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		for testVersion := 1; testVersion < 6; testVersion++ { // test all forks
+			var forkEpoch uint64
+			var expectedVersion int
+
+			switch testVersion {
+			case 1:
+				forkEpoch = uint64(params.BeaconConfig().AltairForkEpoch)
+				expectedVersion = version.Altair
+			case 2:
+				forkEpoch = uint64(params.BeaconConfig().BellatrixForkEpoch)
+				expectedVersion = version.Altair
+			case 3:
+				forkEpoch = uint64(params.BeaconConfig().CapellaForkEpoch)
+				expectedVersion = version.Capella
+			case 4:
+				forkEpoch = uint64(params.BeaconConfig().DenebForkEpoch)
+				expectedVersion = version.Deneb
+			case 5:
+				forkEpoch = uint64(params.BeaconConfig().ElectraForkEpoch)
+				expectedVersion = version.Electra
+			default:
+				t.Errorf("Unsupported fork version %s", version.String(testVersion))
+			}
+
+			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.Store{}
+
+				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))
+
+					// check that the old update is saved
+					actualOldUpdate, err = lightClient.NewLightClientFinalityUpdateFromBeaconState(
+						ctx,
+						cfgOld.postState.Slot(),
+						cfgOld.postState,
+						cfgOld.roblock,
+						lOld.AttestedState,
+						lOld.AttestedBlock,
+						lOld.FinalizedBlock,
+					)
+					require.NoError(t, err)
+					oldUpdate := s.lcStore.LastFinalityUpdate()
+					require.DeepEqual(t, actualOldUpdate, oldUpdate)
+				}
+
+				// config for new update
+				lNew, cfgNew := setupLightClientTestRequirements(ctx, t, s, testVersion, tc.newOptions...)
+				require.NoError(t, s.processLightClientFinalityUpdate(cfgNew.ctx, cfgNew.roblock, cfgNew.postState))
+
+				// check that the actual old update and the actual new update are different
+				actualNewUpdate, err = lightClient.NewLightClientFinalityUpdateFromBeaconState(
+					ctx,
+					cfgNew.postState.Slot(),
+					cfgNew.postState,
+					cfgNew.roblock,
+					lNew.AttestedState,
+					lNew.AttestedBlock,
+					lNew.FinalizedBlock,
+				)
+				require.NoError(t, err)
+				require.DeepNotEqual(t, actualOldUpdate, actualNewUpdate)
+
+				// check that the new update is saved or skipped
+				newUpdate := s.lcStore.LastFinalityUpdate()
+
+				if tc.expectReplace {
+					require.DeepEqual(t, actualNewUpdate, newUpdate)
+					require.Equal(t, expectedVersion, newUpdate.Version())
+				} else {
+					require.DeepEqual(t, actualOldUpdate, newUpdate)
+					require.Equal(t, expectedVersion, newUpdate.Version())
+				}
+			})
+		}
+	}
+}

beacon-chain/blockchain/service.go

@@ -15,6 +15,7 @@ import (
 	"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"
+	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"
@@ -64,6 +65,7 @@ type Service struct {
 	blockBeingSynced     *currentlySyncingBlock
 	blobStorage          *filesystem.BlobStorage
 	slasherEnabled       bool
+	lcStore              *lightClient.Store
 }
 
 // config options for the service.

beacon-chain/blockchain/setup_test.go

@@ -10,6 +10,7 @@ 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"
@@ -122,6 +123,7 @@ func minimalTestService(t *testing.T, opts ...Option) (*Service, *testServiceReq
 		WithBlobStorage(filesystem.NewEphemeralBlobStorage(t)),
 		WithSyncChecker(mock.MockChecker{}),
 		WithExecutionEngineCaller(&mockExecution.EngineClient{}),
+		WithLightClientStore(&lightclient.Store{}),
 	}
 	// append the variadic opts so they override the defaults by being processed afterwards
 	opts = append(defOpts, opts...)

beacon-chain/blockchain/testing/mock.go

@@ -53,6 +53,7 @@ type ChainService struct {
 	InitSyncBlockRoots          map[[32]byte]bool
 	DB                          db.Database
 	State                       state.BeaconState
+	HeadStateErr                error
 	Block                       interfaces.ReadOnlySignedBeaconBlock
 	VerifyBlkDescendantErr      error
 	stateNotifier               statefeed.Notifier
@@ -364,6 +365,9 @@ func (s *ChainService) HeadState(context.Context) (state.BeaconState, error) {
 
 // HeadStateReadOnly mocks HeadStateReadOnly method in chain service.
 func (s *ChainService) HeadStateReadOnly(context.Context) (state.ReadOnlyBeaconState, error) {
+	if s.HeadStateErr != nil {
+		return nil, s.HeadStateErr
+	}
 	return s.State, nil
 }
 
@@ -448,6 +452,11 @@ func (s *ChainService) IsCanonical(_ context.Context, r [32]byte) (bool, error)
 	return true, nil
 }
 
+// DependentRoot mocks the base method in the chain service.
+func (*ChainService) DependentRoot(_ primitives.Epoch) ([32]byte, error) {
+	return [32]byte{}, nil
+}
+
 // HasBlock mocks the same method in the chain service.
 func (s *ChainService) HasBlock(ctx context.Context, rt [32]byte) bool {
 	if s.DB == nil {

beacon-chain/core/blocks/attestation.go

@@ -106,7 +106,7 @@ func VerifyAttestationNoVerifySignature(
 	if err != nil {
 		return err
 	}
-	c := helpers.SlotCommitteeCount(activeValidatorCount)
+	committeeCount := helpers.SlotCommitteeCount(activeValidatorCount)
 
 	var indexedAtt ethpb.IndexedAtt
 
@@ -115,13 +115,14 @@ func VerifyAttestationNoVerifySignature(
 			return errors.New("committee index must be 0 post-Electra")
 		}
 
+		aggBits := att.GetAggregationBits()
 		committeeIndices := att.CommitteeBitsVal().BitIndices()
 		committees := make([][]primitives.ValidatorIndex, len(committeeIndices))
 		participantsCount := 0
 		var err error
 		for i, ci := range committeeIndices {
-			if uint64(ci) >= c {
-				return fmt.Errorf("committee index %d >= committee count %d", ci, c)
+			if uint64(ci) >= committeeCount {
+				return fmt.Errorf("committee index %d >= committee count %d", ci, committeeCount)
 			}
 			committees[i], err = helpers.BeaconCommitteeFromState(ctx, beaconState, att.GetData().Slot, primitives.CommitteeIndex(ci))
 			if err != nil {
@@ -129,16 +130,32 @@ func VerifyAttestationNoVerifySignature(
 			}
 			participantsCount += len(committees[i])
 		}
-		if att.GetAggregationBits().Len() != uint64(participantsCount) {
+		if aggBits.Len() != uint64(participantsCount) {
 			return fmt.Errorf("aggregation bits count %d is different than participant count %d", att.GetAggregationBits().Len(), participantsCount)
 		}
+
+		committeeOffset := 0
+		for ci, c := range committees {
+			attesterFound := false
+			for i := range c {
+				if aggBits.BitAt(uint64(committeeOffset + i)) {
+					attesterFound = true
+					break
+				}
+			}
+			if !attesterFound {
+				return fmt.Errorf("no attesting indices found for committee index %d", ci)
+			}
+			committeeOffset += len(c)
+		}
+
 		indexedAtt, err = attestation.ConvertToIndexed(ctx, att, committees...)
 		if err != nil {
 			return err
 		}
 	} else {
-		if uint64(att.GetData().CommitteeIndex) >= c {
-			return fmt.Errorf("committee index %d >= committee count %d", att.GetData().CommitteeIndex, c)
+		if uint64(att.GetData().CommitteeIndex) >= committeeCount {
+			return fmt.Errorf("committee index %d >= committee count %d", att.GetData().CommitteeIndex, committeeCount)
 		}
 
 		// Verify attesting indices are correct.

beacon-chain/core/blocks/attestation_test.go

@@ -296,6 +296,22 @@ func TestVerifyAttestationNoVerifySignature_Electra(t *testing.T) {
 		err = blocks.VerifyAttestationNoVerifySignature(context.TODO(), beaconState, att)
 		assert.ErrorContains(t, "aggregation bits count 123 is different than participant count 3", err)
 	})
+	t.Run("no attester in committee", func(t *testing.T) {
+		aggBits := bitfield.NewBitlist(3)
+		committeeBits := bitfield.NewBitvector64()
+		committeeBits.SetBitAt(0, true)
+		att := &ethpb.AttestationElectra{
+			Data: &ethpb.AttestationData{
+				Source: &ethpb.Checkpoint{Epoch: 0, Root: mockRoot[:]},
+				Target: &ethpb.Checkpoint{Epoch: 0, Root: make([]byte, 32)},
+			},
+			AggregationBits: aggBits,
+			CommitteeBits:   committeeBits,
+		}
+		att.Signature = zeroSig[:]
+		err = blocks.VerifyAttestationNoVerifySignature(context.TODO(), beaconState, att)
+		assert.ErrorContains(t, "no attesting indices found for committee index 0", err)
+	})
 }
 
 func TestConvertToIndexed_OK(t *testing.T) {

beacon-chain/core/blocks/proposer_slashing.go

@@ -16,6 +16,9 @@ import (
 	"google.golang.org/protobuf/proto"
 )
 
+// ErrCouldNotVerifyBlockHeader is returned when a block header's signature cannot be verified.
+var ErrCouldNotVerifyBlockHeader = errors.New("could not verify beacon block header")
+
 type slashValidatorFunc func(
 	ctx context.Context,
 	st state.BeaconState,
@@ -114,7 +117,7 @@ func VerifyProposerSlashing(
 	for _, header := range headers {
 		if err := signing.ComputeDomainVerifySigningRoot(beaconState, pIdx, slots.ToEpoch(hSlot),
 			header.Header, params.BeaconConfig().DomainBeaconProposer, header.Signature); err != nil {
-			return errors.Wrap(err, "could not verify beacon block header")
+			return errors.Wrap(ErrCouldNotVerifyBlockHeader, err.Error())
 		}
 	}
 	return nil

beacon-chain/core/fulu/upgrade.go

@@ -11,7 +11,7 @@ import (
 )
 
 // UpgradeToFulu updates inputs a generic state to return the version Fulu state.
-// https://github.com/ethereum/consensus-specs/blob/dev/specs/fulu/fork.md#upgrading-the-state
+// https://github.com/ethereum/consensus-specs/blob/v1.5.0-beta.5/specs/fulu/fork.md#upgrading-the-state
 func UpgradeToFulu(beaconState state.BeaconState) (state.BeaconState, error) {
 	currentSyncCommittee, err := beaconState.CurrentSyncCommittee()
 	if err != nil {
@@ -69,6 +69,10 @@ func UpgradeToFulu(beaconState state.BeaconState) (state.BeaconState, error) {
 	if err != nil {
 		return nil, err
 	}
+	depositRequestsStartIndex, err := beaconState.DepositRequestsStartIndex()
+	if err != nil {
+		return nil, err
+	}
 	depositBalanceToConsume, err := beaconState.DepositBalanceToConsume()
 	if err != nil {
 		return nil, err
@@ -154,7 +158,7 @@ func UpgradeToFulu(beaconState state.BeaconState) (state.BeaconState, error) {
 		NextWithdrawalValidatorIndex: vi,
 		HistoricalSummaries:          summaries,
 
-		DepositRequestsStartIndex:     params.BeaconConfig().UnsetDepositRequestsStartIndex,
+		DepositRequestsStartIndex:     depositRequestsStartIndex,
 		DepositBalanceToConsume:       depositBalanceToConsume,
 		ExitBalanceToConsume:          exitBalanceToConsume,
 		EarliestExitEpoch:             earliestExitEpoch,

beacon-chain/core/helpers/validators.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/binary"
+	"fmt"
 
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/time"
@@ -299,9 +300,12 @@ func ProposerIndexAtSlotFromCheckpoint(c *forkchoicetypes.Checkpoint, slot primi
 // BeaconProposerIndexAtSlot returns proposer index at the given slot from the
 // point of view of the given state as head state
 func BeaconProposerIndexAtSlot(ctx context.Context, state state.ReadOnlyBeaconState, slot primitives.Slot) (primitives.ValidatorIndex, error) {
+	pid, err := GetCachedProposerIndex(state, slot)
+	if err == nil {
+		return pid, nil
+	}
+
 	e := slots.ToEpoch(slot)
-	// The cache uses the state root of the previous epoch - minimum_seed_lookahead last slot as key. (e.g. Starting epoch 1, slot 32, the key would be block root at slot 31)
-	// For simplicity, the node will skip caching of genesis epoch.
 	if e > params.BeaconConfig().GenesisEpoch+params.BeaconConfig().MinSeedLookahead {
 		s, err := slots.EpochEnd(e - 1)
 		if err != nil {
@@ -312,14 +316,10 @@ func BeaconProposerIndexAtSlot(ctx context.Context, state state.ReadOnlyBeaconSt
 			return 0, err
 		}
 		if r != nil && !bytes.Equal(r, params.BeaconConfig().ZeroHash[:]) {
-			pid, err := cachedProposerIndexAtSlot(slot, [32]byte(r))
-			if err == nil {
-				return pid, nil
-			}
 			if err := UpdateProposerIndicesInCache(ctx, state, e); err != nil {
 				return 0, errors.Wrap(err, "could not update proposer index cache")
 			}
-			pid, err = cachedProposerIndexAtSlot(slot, [32]byte(r))
+			pid, err := cachedProposerIndexAtSlot(slot, [32]byte(r))
 			if err == nil {
 				return pid, nil
 			}
@@ -342,6 +342,34 @@ func BeaconProposerIndexAtSlot(ctx context.Context, state state.ReadOnlyBeaconSt
 	return ComputeProposerIndex(state, indices, seedWithSlotHash)
 }
 
+var ErrProposerNotFound = errors.New("invalid nil or unknown node")
+
+func GetCachedProposerIndex(state state.ReadOnlyBeaconState, slot primitives.Slot) (primitives.ValidatorIndex, error) {
+	epoch := slots.ToEpoch(slot)
+	if epoch <= params.BeaconConfig().GenesisEpoch+params.BeaconConfig().MinSeedLookahead {
+		return 0, fmt.Errorf("epoch %d is too early to get cached proposer index", epoch)
+	}
+
+	endSlot, err := slots.EpochEnd(epoch - 1)
+	if err != nil {
+		return 0, err
+	}
+
+	root, err := StateRootAtSlot(state, endSlot)
+	if err != nil {
+		return 0, err
+	}
+	if root == nil || bytes.Equal(root, params.BeaconConfig().ZeroHash[:]) {
+		return 0, ErrProposerNotFound
+	}
+
+	proposerIndex, err := cachedProposerIndexAtSlot(slot, [32]byte(root))
+	if err != nil {
+		return 0, ErrProposerNotFound
+	}
+	return proposerIndex, nil
+}
+
 // ComputeProposerIndex returns the index sampled by effective balance, which is used to calculate proposer.
 //
 // nolint:dupword

beacon-chain/core/light-client/BUILD.bazel

@@ -45,6 +45,7 @@ go_test(
         "//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",
         "@com_github_pkg_errors//:go_default_library",

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

@@ -1013,3 +1013,9 @@ func createDefaultLightClientBootstrap(currentSlot primitives.Slot) (interfaces.
 
 	return light_client.NewWrappedBootstrap(m)
 }
+
+func UpdateHasSupermajority(syncAggregate *pb.SyncAggregate) bool {
+	maxActiveParticipants := syncAggregate.SyncCommitteeBits.Len()
+	numActiveParticipants := syncAggregate.SyncCommitteeBits.Count()
+	return numActiveParticipants*3 >= maxActiveParticipants*2
+}

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

@@ -8,6 +8,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	light_client "github.com/OffchainLabs/prysm/v6/consensus-types/light-client"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
+	"github.com/OffchainLabs/prysm/v6/runtime/version"
 
 	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
@@ -32,7 +33,7 @@ func TestLightClient_NewLightClientOptimisticUpdateFromBeaconState(t *testing.T)
 	params.OverrideBeaconConfig(cfg)
 
 	t.Run("Altair", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestAltair(0, true)
+		l := util.NewTestLightClient(t, version.Altair)
 
 		update, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock)
 		require.NoError(t, err)
@@ -44,7 +45,7 @@ func TestLightClient_NewLightClientOptimisticUpdateFromBeaconState(t *testing.T)
 	})
 
 	t.Run("Capella", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestCapella(false, 0, true)
+		l := util.NewTestLightClient(t, version.Capella)
 
 		update, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock)
 		require.NoError(t, err)
@@ -57,7 +58,7 @@ func TestLightClient_NewLightClientOptimisticUpdateFromBeaconState(t *testing.T)
 	})
 
 	t.Run("Deneb", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestDeneb(false, 0, true)
+		l := util.NewTestLightClient(t, version.Deneb)
 
 		update, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock)
 		require.NoError(t, err)
@@ -70,7 +71,7 @@ func TestLightClient_NewLightClientOptimisticUpdateFromBeaconState(t *testing.T)
 	})
 
 	t.Run("Electra", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestElectra(false, 0, true)
+		l := util.NewTestLightClient(t, version.Electra)
 
 		update, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock)
 		require.NoError(t, err)
@@ -94,7 +95,7 @@ func TestLightClient_NewLightClientFinalityUpdateFromBeaconState(t *testing.T) {
 	params.OverrideBeaconConfig(cfg)
 
 	t.Run("Altair", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestAltair(0, true)
+		l := util.NewTestLightClient(t, version.Altair)
 
 		t.Run("FinalizedBlock Not Nil", func(t *testing.T) {
 			update, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
@@ -131,7 +132,7 @@ func TestLightClient_NewLightClientFinalityUpdateFromBeaconState(t *testing.T) {
 	t.Run("Capella", func(t *testing.T) {
 
 		t.Run("FinalizedBlock Not Nil", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapella(false, 0, true)
+			l := util.NewTestLightClient(t, version.Capella)
 			update, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
 			require.NoError(t, err)
 			require.NotNil(t, update, "update is nil")
@@ -205,7 +206,7 @@ func TestLightClient_NewLightClientFinalityUpdateFromBeaconState(t *testing.T) {
 		})
 
 		t.Run("FinalizedBlock In Previous Fork", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapellaFinalizedBlockAltair(false)
+			l := util.NewTestLightClient(t, version.Capella, util.WithFinalizedCheckpointInPrevFork())
 			update, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
 			require.NoError(t, err)
 			require.NotNil(t, update, "update is nil")
@@ -238,7 +239,7 @@ func TestLightClient_NewLightClientFinalityUpdateFromBeaconState(t *testing.T) {
 	t.Run("Deneb", func(t *testing.T) {
 
 		t.Run("FinalizedBlock Not Nil", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestDeneb(false, 0, true)
+			l := util.NewTestLightClient(t, version.Deneb)
 
 			update, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
 			require.NoError(t, err)
@@ -313,7 +314,7 @@ func TestLightClient_NewLightClientFinalityUpdateFromBeaconState(t *testing.T) {
 		})
 
 		t.Run("FinalizedBlock In Previous Fork", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestDenebFinalizedBlockCapella(false)
+			l := util.NewTestLightClient(t, version.Deneb, util.WithFinalizedCheckpointInPrevFork())
 
 			update, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
 			require.NoError(t, err)
@@ -390,7 +391,7 @@ func TestLightClient_NewLightClientFinalityUpdateFromBeaconState(t *testing.T) {
 
 	t.Run("Electra", func(t *testing.T) {
 		t.Run("FinalizedBlock Not Nil", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestElectra(false, 0, true)
+			l := util.NewTestLightClient(t, version.Electra)
 
 			update, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
 			require.NoError(t, err)
@@ -465,7 +466,7 @@ func TestLightClient_NewLightClientFinalityUpdateFromBeaconState(t *testing.T) {
 		})
 
 		t.Run("FinalizedBlock In Previous Fork", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestElectraFinalizedBlockDeneb(false)
+			l := util.NewTestLightClient(t, version.Electra, util.WithFinalizedCheckpointInPrevFork())
 
 			update, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
 			require.NoError(t, err)
@@ -542,7 +543,7 @@ func TestLightClient_NewLightClientFinalityUpdateFromBeaconState(t *testing.T) {
 
 func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 	t.Run("Altair", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestAltair(0, true)
+		l := util.NewTestLightClient(t, version.Altair)
 
 		header, err := lightClient.BlockToLightClientHeader(
 			l.Ctx,
@@ -565,7 +566,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 	})
 
 	t.Run("Bellatrix", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestBellatrix(0, true)
+		l := util.NewTestLightClient(t, version.Bellatrix)
 
 		header, err := lightClient.BlockToLightClientHeader(
 			l.Ctx,
@@ -589,7 +590,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 
 	t.Run("Capella", func(t *testing.T) {
 		t.Run("Non-Blinded Beacon Block", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapella(false, 0, true)
+			l := util.NewTestLightClient(t, version.Capella)
 
 			header, err := lightClient.BlockToLightClientHeader(
 				l.Ctx,
@@ -650,7 +651,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 		})
 
 		t.Run("Blinded Beacon Block", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapella(true, 0, true)
+			l := util.NewTestLightClient(t, version.Capella, util.WithBlinded())
 
 			header, err := lightClient.BlockToLightClientHeader(
 				l.Ctx,
@@ -713,7 +714,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 
 	t.Run("Deneb", func(t *testing.T) {
 		t.Run("Non-Blinded Beacon Block", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestDeneb(false, 0, true)
+			l := util.NewTestLightClient(t, version.Deneb)
 
 			header, err := lightClient.BlockToLightClientHeader(
 				l.Ctx,
@@ -782,7 +783,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 		})
 
 		t.Run("Blinded Beacon Block", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestDeneb(true, 0, true)
+			l := util.NewTestLightClient(t, version.Deneb, util.WithBlinded())
 
 			header, err := lightClient.BlockToLightClientHeader(
 				l.Ctx,
@@ -853,7 +854,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 
 	t.Run("Electra", func(t *testing.T) {
 		t.Run("Non-Blinded Beacon Block", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestElectra(false, 0, true)
+			l := util.NewTestLightClient(t, version.Electra)
 
 			header, err := lightClient.BlockToLightClientHeader(l.Ctx, l.State.Slot(), l.Block)
 			require.NoError(t, err)
@@ -918,7 +919,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 		})
 
 		t.Run("Blinded Beacon Block", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestElectra(true, 0, true)
+			l := util.NewTestLightClient(t, version.Electra, util.WithBlinded())
 
 			header, err := lightClient.BlockToLightClientHeader(l.Ctx, l.State.Slot(), l.Block)
 			require.NoError(t, err)
@@ -984,7 +985,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 	})
 
 	t.Run("Capella fork with Altair block", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestAltair(0, true)
+		l := util.NewTestLightClient(t, version.Altair)
 
 		header, err := lightClient.BlockToLightClientHeader(
 			l.Ctx,
@@ -1006,7 +1007,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 	})
 
 	t.Run("Deneb fork with Altair block", func(t *testing.T) {
-		l := util.NewTestLightClient(t).SetupTestAltair(0, true)
+		l := util.NewTestLightClient(t, version.Altair)
 
 		header, err := lightClient.BlockToLightClientHeader(
 			l.Ctx,
@@ -1029,7 +1030,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 
 	t.Run("Deneb fork with Capella block", func(t *testing.T) {
 		t.Run("Non-Blinded Beacon Block", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapella(false, 0, true)
+			l := util.NewTestLightClient(t, version.Capella)
 
 			header, err := lightClient.BlockToLightClientHeader(
 				l.Ctx,
@@ -1089,7 +1090,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 		})
 
 		t.Run("Blinded Beacon Block", func(t *testing.T) {
-			l := util.NewTestLightClient(t).SetupTestCapella(true, 0, true)
+			l := util.NewTestLightClient(t, version.Capella, util.WithBlinded())
 
 			header, err := lightClient.BlockToLightClientHeader(
 				l.Ctx,

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

@@ -5,6 +5,7 @@ import (
 
 	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
 	"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"
 )
@@ -23,7 +24,7 @@ func TestLightClientStore(t *testing.T) {
 	lcStore := &lightClient.Store{}
 
 	// Create test light client updates for Capella and Deneb
-	lCapella := util.NewTestLightClient(t).SetupTestCapella(false, 0, true)
+	lCapella := util.NewTestLightClient(t, version.Capella)
 	opUpdateCapella, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(lCapella.Ctx, lCapella.State.Slot(), lCapella.State, lCapella.Block, lCapella.AttestedState, lCapella.AttestedBlock)
 	require.NoError(t, err)
 	require.NotNil(t, opUpdateCapella, "OptimisticUpdateCapella is nil")
@@ -31,7 +32,7 @@ func TestLightClientStore(t *testing.T) {
 	require.NoError(t, err)
 	require.NotNil(t, finUpdateCapella, "FinalityUpdateCapella is nil")
 
-	lDeneb := util.NewTestLightClient(t).SetupTestDeneb(false, 0, true)
+	lDeneb := util.NewTestLightClient(t, version.Deneb)
 	opUpdateDeneb, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(lDeneb.Ctx, lDeneb.State.Slot(), lDeneb.State, lDeneb.Block, lDeneb.AttestedState, lDeneb.AttestedBlock)
 	require.NoError(t, err)
 	require.NotNil(t, opUpdateDeneb, "OptimisticUpdateDeneb is nil")

beacon-chain/node/node.go

@@ -779,6 +779,7 @@ func (b *BeaconNode) registerBlockchainService(fc forkchoice.ForkChoicer, gs *st
 		blockchain.WithPayloadIDCache(b.payloadIDCache),
 		blockchain.WithSyncChecker(b.syncChecker),
 		blockchain.WithSlasherEnabled(b.slasherEnabled),
+		blockchain.WithLightClientStore(b.lcStore),
 	)
 
 	blockchainService, err := blockchain.NewService(b.ctx, opts...)
@@ -1010,6 +1011,7 @@ func (b *BeaconNode) registerRPCService(router *http.ServeMux) error {
 		BlobStorage:               b.BlobStorage,
 		TrackedValidatorsCache:    b.trackedValidatorsCache,
 		PayloadIDCache:            b.payloadIDCache,
+		LCStore:                   b.lcStore,
 	})
 
 	return b.services.RegisterService(rpcService)

beacon-chain/p2p/BUILD.bazel

@@ -56,6 +56,7 @@ go_library(
         "//cmd/beacon-chain/flags:go_default_library",
         "//config/features:go_default_library",
         "//config/params:go_default_library",
+        "//consensus-types/interfaces:go_default_library",
         "//consensus-types/primitives:go_default_library",
         "//consensus-types/wrapper:go_default_library",
         "//container/leaky-bucket:go_default_library",
@@ -140,6 +141,7 @@ go_test(
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/cache:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/light-client:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/p2p/encoder:go_default_library",
@@ -152,6 +154,7 @@ go_test(
         "//cmd/beacon-chain/flags:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
+        "//consensus-types/interfaces:go_default_library",
         "//consensus-types/primitives:go_default_library",
         "//consensus-types/wrapper:go_default_library",
         "//container/leaky-bucket:go_default_library",
@@ -163,10 +166,12 @@ go_test(
         "//proto/eth/v1:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
         "//proto/testing:go_default_library",
+        "//runtime/version:go_default_library",
         "//testing/assert:go_default_library",
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",
         "//time:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_ethereum_go_ethereum//crypto:go_default_library",
         "@com_github_ethereum_go_ethereum//p2p/discover:go_default_library",
         "@com_github_ethereum_go_ethereum//p2p/enode:go_default_library",

beacon-chain/p2p/broadcaster.go

@@ -10,9 +10,11 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/altair"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
 	"github.com/OffchainLabs/prysm/v6/config/params"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/crypto/hash"
 	"github.com/OffchainLabs/prysm/v6/monitoring/tracing"
 	"github.com/OffchainLabs/prysm/v6/monitoring/tracing/trace"
+	"github.com/OffchainLabs/prysm/v6/network/forks"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v6/time/slots"
 	"github.com/pkg/errors"
@@ -268,6 +270,58 @@ func (s *Service) internalBroadcastBlob(ctx context.Context, subnet uint64, blob
 	}
 }
 
+func (s *Service) BroadcastLightClientOptimisticUpdate(ctx context.Context, update interfaces.LightClientOptimisticUpdate) error {
+	ctx, span := trace.StartSpan(ctx, "p2p.BroadcastLightClientOptimisticUpdate")
+	defer span.End()
+
+	if update == nil || update.IsNil() {
+		return errors.New("attempted to broadcast nil light client optimistic update")
+	}
+
+	forkDigest, err := forks.ForkDigestFromEpoch(slots.ToEpoch(update.AttestedHeader().Beacon().Slot), s.genesisValidatorsRoot)
+	if err != nil {
+		err := errors.Wrap(err, "could not retrieve fork digest")
+		tracing.AnnotateError(span, err)
+		return err
+	}
+
+	// TODO: should we check if the update is too early or too late to broadcast?
+
+	if err := s.broadcastObject(ctx, update, lcOptimisticToTopic(forkDigest)); err != nil {
+		err := errors.Wrap(err, "could not publish message")
+		tracing.AnnotateError(span, err)
+		return err
+	}
+
+	return nil
+}
+
+func (s *Service) BroadcastLightClientFinalityUpdate(ctx context.Context, update interfaces.LightClientFinalityUpdate) error {
+	ctx, span := trace.StartSpan(ctx, "p2p.BroadcastLightClientFinalityUpdate")
+	defer span.End()
+
+	if update == nil || update.IsNil() {
+		return errors.New("attempted to broadcast nil light client finality update")
+	}
+
+	forkDigest, err := forks.ForkDigestFromEpoch(slots.ToEpoch(update.AttestedHeader().Beacon().Slot), s.genesisValidatorsRoot)
+	if err != nil {
+		err := errors.Wrap(err, "could not retrieve fork digest")
+		tracing.AnnotateError(span, err)
+		return err
+	}
+
+	// TODO: should we check if the update is too early or too late to broadcast?
+
+	if err := s.broadcastObject(ctx, update, lcFinalityToTopic(forkDigest)); err != nil {
+		err := errors.Wrap(err, "could not publish message")
+		tracing.AnnotateError(span, err)
+		return err
+	}
+
+	return nil
+}
+
 // method to broadcast messages to other peers in our gossip mesh.
 func (s *Service) broadcastObject(ctx context.Context, obj ssz.Marshaler, topic string) error {
 	ctx, span := trace.StartSpan(ctx, "p2p.broadcastObject")
@@ -308,3 +362,11 @@ func syncCommitteeToTopic(subnet uint64, forkDigest [4]byte) string {
 func blobSubnetToTopic(subnet uint64, forkDigest [4]byte) string {
 	return fmt.Sprintf(BlobSubnetTopicFormat, forkDigest, subnet)
 }
+
+func lcOptimisticToTopic(forkDigest [4]byte) string {
+	return fmt.Sprintf(LightClientOptimisticUpdateTopicFormat, forkDigest)
+}
+
+func lcFinalityToTopic(forkDigest [4]byte) string {
+	return fmt.Sprintf(LightClientFinalityUpdateTopicFormat, forkDigest)
+}

beacon-chain/p2p/broadcaster_test.go

@@ -10,17 +10,22 @@ import (
 	"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/p2p/peers"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/peers/scorers"
 	p2ptest "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/wrapper"
 	"github.com/OffchainLabs/prysm/v6/encoding/bytesutil"
+	"github.com/OffchainLabs/prysm/v6/network/forks"
 	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	testpb "github.com/OffchainLabs/prysm/v6/proto/testing"
+	"github.com/OffchainLabs/prysm/v6/runtime/version"
 	"github.com/OffchainLabs/prysm/v6/testing/assert"
 	"github.com/OffchainLabs/prysm/v6/testing/require"
 	"github.com/OffchainLabs/prysm/v6/testing/util"
+	"github.com/OffchainLabs/prysm/v6/time/slots"
 	pubsub "github.com/libp2p/go-libp2p-pubsub"
 	"github.com/libp2p/go-libp2p/core/host"
 	"github.com/prysmaticlabs/go-bitfield"
@@ -516,3 +521,137 @@ func TestService_BroadcastBlob(t *testing.T) {
 	require.NoError(t, p.BroadcastBlob(ctx, subnet, blobSidecar))
 	require.Equal(t, false, util.WaitTimeout(&wg, 1*time.Second), "Failed to receive pubsub within 1s")
 }
+
+func TestService_BroadcastLightClientOptimisticUpdate(t *testing.T) {
+	p1 := p2ptest.NewTestP2P(t)
+	p2 := p2ptest.NewTestP2P(t)
+	p1.Connect(p2)
+	require.NotEqual(t, 0, len(p1.BHost.Network().Peers()))
+
+	p := &Service{
+		host:                  p1.BHost,
+		pubsub:                p1.PubSub(),
+		joinedTopics:          map[string]*pubsub.Topic{},
+		cfg:                   &Config{},
+		genesisTime:           time.Now(),
+		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
+		subnetsLock:           make(map[uint64]*sync.RWMutex),
+		subnetsLockLock:       sync.Mutex{},
+		peers: peers.NewStatus(context.Background(), &peers.StatusConfig{
+			ScorerParams: &scorers.Config{},
+		}),
+	}
+
+	l := util.NewTestLightClient(t, version.Altair)
+	msg, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock)
+	require.NoError(t, err)
+
+	GossipTypeMapping[reflect.TypeOf(msg)] = LightClientOptimisticUpdateTopicFormat
+	digest, err := forks.ForkDigestFromEpoch(slots.ToEpoch(msg.AttestedHeader().Beacon().Slot), p.genesisValidatorsRoot)
+	require.NoError(t, err)
+	topic := fmt.Sprintf(LightClientOptimisticUpdateTopicFormat, digest)
+
+	// External peer subscribes to the topic.
+	topic += p.Encoding().ProtocolSuffix()
+	sub, err := p2.SubscribeToTopic(topic)
+	require.NoError(t, err)
+
+	time.Sleep(50 * time.Millisecond) // libp2p fails without this delay...
+
+	// Async listen for the pubsub, must be before the broadcast.
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func(tt *testing.T) {
+		defer wg.Done()
+		ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+		defer cancel()
+
+		incomingMessage, err := sub.Next(ctx)
+		require.NoError(t, err)
+
+		result := &ethpb.LightClientOptimisticUpdateAltair{}
+		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
+		if !proto.Equal(result, msg.Proto()) {
+			tt.Errorf("Did not receive expected message, got %+v, wanted %+v", result, msg)
+		}
+	}(t)
+
+	// Broadcasting nil should fail.
+	ctx := context.Background()
+	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastLightClientOptimisticUpdate(ctx, nil))
+	var nilUpdate interfaces.LightClientOptimisticUpdate
+	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastLightClientOptimisticUpdate(ctx, nilUpdate))
+
+	// Broadcast to peers and wait.
+	require.NoError(t, p.BroadcastLightClientOptimisticUpdate(ctx, msg))
+	if util.WaitTimeout(&wg, 1*time.Second) {
+		t.Error("Failed to receive pubsub within 1s")
+	}
+}
+
+func TestService_BroadcastLightClientFinalityUpdate(t *testing.T) {
+	p1 := p2ptest.NewTestP2P(t)
+	p2 := p2ptest.NewTestP2P(t)
+	p1.Connect(p2)
+	require.NotEqual(t, 0, len(p1.BHost.Network().Peers()))
+
+	p := &Service{
+		host:                  p1.BHost,
+		pubsub:                p1.PubSub(),
+		joinedTopics:          map[string]*pubsub.Topic{},
+		cfg:                   &Config{},
+		genesisTime:           time.Now(),
+		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
+		subnetsLock:           make(map[uint64]*sync.RWMutex),
+		subnetsLockLock:       sync.Mutex{},
+		peers: peers.NewStatus(context.Background(), &peers.StatusConfig{
+			ScorerParams: &scorers.Config{},
+		}),
+	}
+
+	l := util.NewTestLightClient(t, version.Altair)
+	msg, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
+	require.NoError(t, err)
+
+	GossipTypeMapping[reflect.TypeOf(msg)] = LightClientFinalityUpdateTopicFormat
+	digest, err := forks.ForkDigestFromEpoch(slots.ToEpoch(msg.AttestedHeader().Beacon().Slot), p.genesisValidatorsRoot)
+	require.NoError(t, err)
+	topic := fmt.Sprintf(LightClientFinalityUpdateTopicFormat, digest)
+
+	// External peer subscribes to the topic.
+	topic += p.Encoding().ProtocolSuffix()
+	sub, err := p2.SubscribeToTopic(topic)
+	require.NoError(t, err)
+
+	time.Sleep(50 * time.Millisecond) // libp2p fails without this delay...
+
+	// Async listen for the pubsub, must be before the broadcast.
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func(tt *testing.T) {
+		defer wg.Done()
+		ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+		defer cancel()
+
+		incomingMessage, err := sub.Next(ctx)
+		require.NoError(t, err)
+
+		result := &ethpb.LightClientFinalityUpdateAltair{}
+		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
+		if !proto.Equal(result, msg.Proto()) {
+			tt.Errorf("Did not receive expected message, got %+v, wanted %+v", result, msg)
+		}
+	}(t)
+
+	// Broadcasting nil should fail.
+	ctx := context.Background()
+	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastLightClientFinalityUpdate(ctx, nil))
+	var nilUpdate interfaces.LightClientFinalityUpdate
+	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastLightClientFinalityUpdate(ctx, nilUpdate))
+
+	// Broadcast to peers and wait.
+	require.NoError(t, p.BroadcastLightClientFinalityUpdate(ctx, msg))
+	if util.WaitTimeout(&wg, 1*time.Second) {
+		t.Error("Failed to receive pubsub within 1s")
+	}
+}

beacon-chain/p2p/discovery.go

@@ -105,7 +105,8 @@ func (l *listenerWrapper) RandomNodes() enode.Iterator {
 func (l *listenerWrapper) Ping(node *enode.Node) error {
 	l.mu.RLock()
 	defer l.mu.RUnlock()
-	return l.listener.Ping(node)
+	_, err := l.listener.Ping(node)
+	return err
 }
 
 func (l *listenerWrapper) RequestENR(node *enode.Node) (*enode.Node, error) {

beacon-chain/p2p/gossip_topic_mappings.go

@@ -22,6 +22,8 @@ var gossipTopicMappings = map[string]func() proto.Message{
 	SyncCommitteeSubnetTopicFormat:            func() proto.Message { return &ethpb.SyncCommitteeMessage{} },
 	BlsToExecutionChangeSubnetTopicFormat:     func() proto.Message { return &ethpb.SignedBLSToExecutionChange{} },
 	BlobSubnetTopicFormat:                     func() proto.Message { return &ethpb.BlobSidecar{} },
+	LightClientOptimisticUpdateTopicFormat:    func() proto.Message { return &ethpb.LightClientOptimisticUpdateAltair{} },
+	LightClientFinalityUpdateTopicFormat:      func() proto.Message { return &ethpb.LightClientFinalityUpdateAltair{} },
 }
 
 // GossipTopicMappings is a function to return the assigned data type
@@ -63,6 +65,25 @@ func GossipTopicMappings(topic string, epoch primitives.Epoch) proto.Message {
 			return &ethpb.SignedAggregateAttestationAndProofElectra{}
 		}
 		return gossipMessage(topic)
+	case LightClientOptimisticUpdateTopicFormat:
+		if epoch >= params.BeaconConfig().DenebForkEpoch {
+			return &ethpb.LightClientOptimisticUpdateDeneb{}
+		}
+		if epoch >= params.BeaconConfig().CapellaForkEpoch {
+			return &ethpb.LightClientOptimisticUpdateCapella{}
+		}
+		return gossipMessage(topic)
+	case LightClientFinalityUpdateTopicFormat:
+		if epoch >= params.BeaconConfig().ElectraForkEpoch {
+			return &ethpb.LightClientFinalityUpdateElectra{}
+		}
+		if epoch >= params.BeaconConfig().DenebForkEpoch {
+			return &ethpb.LightClientFinalityUpdateDeneb{}
+		}
+		if epoch >= params.BeaconConfig().CapellaForkEpoch {
+			return &ethpb.LightClientFinalityUpdateCapella{}
+		}
+		return gossipMessage(topic)
 	default:
 		return gossipMessage(topic)
 	}
@@ -97,21 +118,28 @@ func init() {
 
 	// Specially handle Altair objects.
 	GossipTypeMapping[reflect.TypeOf(&ethpb.SignedBeaconBlockAltair{})] = BlockSubnetTopicFormat
+	GossipTypeMapping[reflect.TypeOf(&ethpb.LightClientFinalityUpdateAltair{})] = LightClientFinalityUpdateTopicFormat
+	GossipTypeMapping[reflect.TypeOf(&ethpb.LightClientOptimisticUpdateAltair{})] = LightClientOptimisticUpdateTopicFormat
 
 	// Specially handle Bellatrix objects.
 	GossipTypeMapping[reflect.TypeOf(&ethpb.SignedBeaconBlockBellatrix{})] = BlockSubnetTopicFormat
 
 	// Specially handle Capella objects.
 	GossipTypeMapping[reflect.TypeOf(&ethpb.SignedBeaconBlockCapella{})] = BlockSubnetTopicFormat
+	GossipTypeMapping[reflect.TypeOf(&ethpb.LightClientOptimisticUpdateCapella{})] = LightClientOptimisticUpdateTopicFormat
+	GossipTypeMapping[reflect.TypeOf(&ethpb.LightClientFinalityUpdateCapella{})] = LightClientFinalityUpdateTopicFormat
 
 	// Specially handle Deneb objects.
 	GossipTypeMapping[reflect.TypeOf(&ethpb.SignedBeaconBlockDeneb{})] = BlockSubnetTopicFormat
+	GossipTypeMapping[reflect.TypeOf(&ethpb.LightClientOptimisticUpdateDeneb{})] = LightClientOptimisticUpdateTopicFormat
+	GossipTypeMapping[reflect.TypeOf(&ethpb.LightClientFinalityUpdateDeneb{})] = LightClientFinalityUpdateTopicFormat
 
 	// Specially handle Electra objects.
 	GossipTypeMapping[reflect.TypeOf(&ethpb.SignedBeaconBlockElectra{})] = BlockSubnetTopicFormat
 	GossipTypeMapping[reflect.TypeOf(&ethpb.SingleAttestation{})] = AttestationSubnetTopicFormat
 	GossipTypeMapping[reflect.TypeOf(&ethpb.AttesterSlashingElectra{})] = AttesterSlashingSubnetTopicFormat
 	GossipTypeMapping[reflect.TypeOf(&ethpb.SignedAggregateAttestationAndProofElectra{})] = AggregateAndProofSubnetTopicFormat
+	GossipTypeMapping[reflect.TypeOf(&ethpb.LightClientFinalityUpdateElectra{})] = LightClientFinalityUpdateTopicFormat
 
 	// Specially handle Fulu objects.
 	GossipTypeMapping[reflect.TypeOf(&ethpb.SignedBeaconBlockFulu{})] = BlockSubnetTopicFormat

beacon-chain/p2p/peers/scorers/bad_responses.go

@@ -102,6 +102,9 @@ func (s *BadResponsesScorer) countNoLock(pid peer.ID) (int, error) {
 // Increment increments the number of bad responses we have received from the given remote peer.
 // If peer doesn't exist this method is no-op.
 func (s *BadResponsesScorer) Increment(pid peer.ID) {
+	if pid == "" {
+		return
+	}
 	s.store.Lock()
 	defer s.store.Unlock()
 

beacon-chain/p2p/peers/scorers/block_providers.go

@@ -124,6 +124,9 @@ func (s *BlockProviderScorer) Params() *BlockProviderScorerConfig {
 
 // IncrementProcessedBlocks increments the number of blocks that have been successfully processed.
 func (s *BlockProviderScorer) IncrementProcessedBlocks(pid peer.ID, cnt uint64) {
+	if pid == "" {
+		return
+	}
 	s.store.Lock()
 	defer s.store.Unlock()
 	defer s.touchNoLock(pid)

beacon-chain/p2p/topics.go

@@ -30,6 +30,10 @@ const (
 	GossipBlsToExecutionChangeMessage = "bls_to_execution_change"
 	// GossipBlobSidecarMessage is the name for the blob sidecar message type.
 	GossipBlobSidecarMessage = "blob_sidecar"
+	// GossipLightClientFinalityUpdateMessage is the name for the light client finality update message type.
+	GossipLightClientFinalityUpdateMessage = "light_client_finality_update"
+	// GossipLightClientOptimisticUpdateMessage is the name for the light client optimistic update message type.
+	GossipLightClientOptimisticUpdateMessage = "light_client_optimistic_update"
 	// Topic Formats
 	//
 	// AttestationSubnetTopicFormat is the topic format for the attestation subnet.
@@ -52,4 +56,8 @@ const (
 	BlsToExecutionChangeSubnetTopicFormat = GossipProtocolAndDigest + GossipBlsToExecutionChangeMessage
 	// BlobSubnetTopicFormat is the topic format for the blob subnet.
 	BlobSubnetTopicFormat = GossipProtocolAndDigest + GossipBlobSidecarMessage + "_%d"
+	// LightClientFinalityUpdateTopicFormat is the topic format for the light client finality update subnet.
+	LightClientFinalityUpdateTopicFormat = GossipProtocolAndDigest + GossipLightClientFinalityUpdateMessage
+	// LightClientOptimisticUpdateTopicFormat is the topic format for the light client optimistic update subnet.
+	LightClientOptimisticUpdateTopicFormat = GossipProtocolAndDigest + GossipLightClientOptimisticUpdateMessage
 )

beacon-chain/p2p/types/types.go

@@ -162,9 +162,9 @@ func (b *BlobSidecarsByRootReq) MarshalSSZ() ([]byte, error) {
 // BlobSidecarsByRootReq value.
 func (b *BlobSidecarsByRootReq) UnmarshalSSZ(buf []byte) error {
 	bufLen := len(buf)
-	maxLength := int(params.BeaconConfig().MaxRequestBlobSidecars) * blobIdSize
+	maxLength := int(params.BeaconConfig().MaxRequestBlobSidecarsElectra) * blobIdSize
 	if bufLen > maxLength {
-		return errors.Errorf("expected buffer with length of up to %d but received length %d", maxLength, bufLen)
+		return errors.Wrapf(ssz.ErrIncorrectListSize, "expected buffer with length of up to %d but received length %d", maxLength, bufLen)
 	}
 	if bufLen%blobIdSize != 0 {
 		return errors.Wrapf(ssz.ErrIncorrectByteSize, "size=%d", bufLen)

beacon-chain/p2p/types/types_test.go

@@ -43,6 +43,15 @@ func TestBlobSidecarsByRootReq_MarshalSSZ(t *testing.T) {
 			name: "10 item list",
 			ids:  generateBlobIdentifiers(10),
 		},
+		{
+			name: "max list",
+			ids:  generateBlobIdentifiers(int(params.BeaconConfig().MaxRequestBlobSidecarsElectra)),
+		},
+		{
+			name:         "beyond max list",
+			ids:          generateBlobIdentifiers(int(params.BeaconConfig().MaxRequestBlobSidecarsElectra) + 1),
+			unmarshalErr: ssz.ErrIncorrectListSize,
+		},
 		{
 			name: "wonky unmarshal size",
 			ids:  generateBlobIdentifiers(10),

beacon-chain/rpc/BUILD.bazel

@@ -20,6 +20,7 @@ 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/rpc/endpoints.go

@@ -894,6 +894,15 @@ func (s *Service) beaconEndpoints(
 			handler: server.GetPendingDeposits,
 			methods: []string{http.MethodGet},
 		},
+		{
+			template: "/eth/v1/beacon/states/{state_id}/pending_consolidations",
+			name:     namespace + ".GetPendingConsolidations",
+			middleware: []middleware.Middleware{
+				middleware.AcceptHeaderHandler([]string{api.JsonMediaType}),
+			},
+			handler: server.GetPendingDeposits,
+			methods: []string{http.MethodGet},
+		},
 		{
 			template: "/eth/v1/beacon/states/{state_id}/pending_partial_withdrawals",
 			name:     namespace + ".GetPendingPartialWithdrawals",
@@ -946,6 +955,7 @@ func (s *Service) lightClientEndpoints(blocker lookup.Blocker, stater lookup.Sta
 		HeadFetcher:      s.cfg.HeadFetcher,
 		ChainInfoFetcher: s.cfg.ChainInfoFetcher,
 		BeaconDB:         s.cfg.BeaconDB,
+		LCStore:          s.cfg.LCStore,
 	}
 
 	const namespace = "lightclient"
@@ -1040,6 +1050,7 @@ func (s *Service) eventsEndpoints() []endpoint {
 		HeadFetcher:            s.cfg.HeadFetcher,
 		ChainInfoFetcher:       s.cfg.ChainInfoFetcher,
 		TrackedValidatorsCache: s.cfg.TrackedValidatorsCache,
+		StateGen:               s.cfg.StateGen,
 	}
 
 	const namespace = "events"

beacon-chain/rpc/endpoints_test.go

@@ -30,6 +30,7 @@ func Test_endpoints(t *testing.T) {
 		"/eth/v1/beacon/states/{state_id}/randao":                      {http.MethodGet},
 		"/eth/v1/beacon/states/{state_id}/pending_deposits":            {http.MethodGet},
 		"/eth/v1/beacon/states/{state_id}/pending_partial_withdrawals": {http.MethodGet},
+		"/eth/v1/beacon/states/{state_id}/pending_consolidations":      {http.MethodGet},
 		"/eth/v1/beacon/headers":                                       {http.MethodGet},
 		"/eth/v1/beacon/headers/{block_id}":                            {http.MethodGet},
 		"/eth/v1/beacon/blinded_blocks":                                {http.MethodPost},

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

@@ -1613,6 +1613,62 @@ func (s *Server) broadcastSeenBlockSidecars(
 	return nil
 }
 
+// GetPendingConsolidations returns pending deposits for state with given 'stateId'.
+// Should return 400 if the state retrieved is prior to Electra.
+// Supports both JSON and SSZ responses based on Accept header.
+func (s *Server) GetPendingConsolidations(w http.ResponseWriter, r *http.Request) {
+	ctx, span := trace.StartSpan(r.Context(), "beacon.GetPendingDeposits")
+	defer span.End()
+
+	stateId := r.PathValue("state_id")
+	if stateId == "" {
+		httputil.HandleError(w, "state_id is required in URL params", http.StatusBadRequest)
+		return
+	}
+	st, err := s.Stater.State(ctx, []byte(stateId))
+	if err != nil {
+		shared.WriteStateFetchError(w, err)
+		return
+	}
+	if st.Version() < version.Electra {
+		httputil.HandleError(w, "state_id is prior to electra", http.StatusBadRequest)
+		return
+	}
+	pd, err := st.PendingConsolidations()
+	if err != nil {
+		httputil.HandleError(w, "Could not get pending consolidations: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set(api.VersionHeader, version.String(st.Version()))
+	if httputil.RespondWithSsz(r) {
+		sszData, err := serializeItems(pd)
+		if err != nil {
+			httputil.HandleError(w, "Failed to serialize pending consolidations: "+err.Error(), http.StatusInternalServerError)
+			return
+		}
+		httputil.WriteSsz(w, sszData)
+	} else {
+		isOptimistic, err := helpers.IsOptimistic(ctx, []byte(stateId), s.OptimisticModeFetcher, s.Stater, s.ChainInfoFetcher, s.BeaconDB)
+		if err != nil {
+			httputil.HandleError(w, "Could not check optimistic status: "+err.Error(), http.StatusInternalServerError)
+			return
+		}
+		blockRoot, err := st.LatestBlockHeader().HashTreeRoot()
+		if err != nil {
+			httputil.HandleError(w, "Could not calculate root of latest block header: "+err.Error(), http.StatusInternalServerError)
+			return
+		}
+		isFinalized := s.FinalizationFetcher.IsFinalized(ctx, blockRoot)
+		resp := structs.GetPendingConsolidationsResponse{
+			Version:             version.String(st.Version()),
+			ExecutionOptimistic: isOptimistic,
+			Finalized:           isFinalized,
+			Data:                structs.PendingConsolidationsFromConsensus(pd),
+		}
+		httputil.WriteJson(w, resp)
+	}
+}
+
 // GetPendingDeposits returns pending deposits for state with given 'stateId'.
 // Should return 400 if the state retrieved is prior to Electra.
 // Supports both JSON and SSZ responses based on Accept header.

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

@@ -4755,6 +4755,191 @@ func Test_validateBlobSidecars(t *testing.T) {
 	require.ErrorContains(t, "could not verify blob proof: can't verify opening proof", s.validateBlobSidecars(b, [][]byte{blob[:]}, [][]byte{proof[:]}))
 }
 
+func TestGetPendingConsolidations(t *testing.T) {
+	st, _ := util.DeterministicGenesisStateElectra(t, 10)
+
+	cs := make([]*eth.PendingConsolidation, 10)
+	for i := 0; i < len(cs); i += 1 {
+		cs[i] = &eth.PendingConsolidation{
+			SourceIndex: primitives.ValidatorIndex(i),
+			TargetIndex: primitives.ValidatorIndex(i + 1),
+		}
+	}
+	require.NoError(t, st.SetPendingConsolidations(cs))
+
+	chainService := &chainMock.ChainService{
+		Optimistic:     false,
+		FinalizedRoots: map[[32]byte]bool{},
+	}
+	server := &Server{
+		Stater: &testutil.MockStater{
+			BeaconState: st,
+		},
+		OptimisticModeFetcher: chainService,
+		FinalizationFetcher:   chainService,
+	}
+
+	t.Run("json response", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "http://example.com/eth/v1/beacon/states/{state_id}/pending_consolidations", nil)
+		req.SetPathValue("state_id", "head")
+		rec := httptest.NewRecorder()
+		rec.Body = new(bytes.Buffer)
+
+		server.GetPendingConsolidations(rec, req)
+		require.Equal(t, http.StatusOK, rec.Code)
+		require.Equal(t, "electra", rec.Header().Get(api.VersionHeader))
+
+		var resp structs.GetPendingConsolidationsResponse
+		require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+
+		expectedVersion := version.String(st.Version())
+		require.Equal(t, expectedVersion, resp.Version)
+
+		require.Equal(t, false, resp.ExecutionOptimistic)
+		require.Equal(t, false, resp.Finalized)
+
+		expectedConsolidations := structs.PendingConsolidationsFromConsensus(cs)
+		require.DeepEqual(t, expectedConsolidations, resp.Data)
+	})
+	t.Run("ssz response", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "http://example.com/eth/v1/beacon/states/{state_id}/pending_consolidations", nil)
+		req.Header.Set("Accept", "application/octet-stream")
+		req.SetPathValue("state_id", "head")
+		rec := httptest.NewRecorder()
+		rec.Body = new(bytes.Buffer)
+
+		server.GetPendingConsolidations(rec, req)
+		require.Equal(t, http.StatusOK, rec.Code)
+		require.Equal(t, "electra", rec.Header().Get(api.VersionHeader))
+
+		responseBytes := rec.Body.Bytes()
+		var recoveredConsolidations []*eth.PendingConsolidation
+
+		// Verify total size matches expected number of deposits
+		consolidationSize := (&eth.PendingConsolidation{}).SizeSSZ()
+		require.Equal(t, len(responseBytes), consolidationSize*len(cs))
+
+		for i := 0; i < len(cs); i++ {
+			start := i * consolidationSize
+			end := start + consolidationSize
+
+			var c eth.PendingConsolidation
+			require.NoError(t, c.UnmarshalSSZ(responseBytes[start:end]))
+			recoveredConsolidations = append(recoveredConsolidations, &c)
+		}
+		require.DeepEqual(t, cs, recoveredConsolidations)
+	})
+	t.Run("pre electra state", func(t *testing.T) {
+		preElectraSt, _ := util.DeterministicGenesisStateDeneb(t, 1)
+		preElectraServer := &Server{
+			Stater: &testutil.MockStater{
+				BeaconState: preElectraSt,
+			},
+			OptimisticModeFetcher: chainService,
+			FinalizationFetcher:   chainService,
+		}
+
+		// Test JSON request
+		req := httptest.NewRequest(http.MethodGet, "http://example.com/eth/v1/beacon/states/{state_id}/pending_consolidations", nil)
+		req.SetPathValue("state_id", "head")
+		rec := httptest.NewRecorder()
+		rec.Body = new(bytes.Buffer)
+
+		preElectraServer.GetPendingConsolidations(rec, req)
+		require.Equal(t, http.StatusBadRequest, rec.Code)
+
+		var errResp struct {
+			Code    int    `json:"code"`
+			Message string `json:"message"`
+		}
+		require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &errResp))
+		require.Equal(t, "state_id is prior to electra", errResp.Message)
+
+		// Test SSZ request
+		sszReq := httptest.NewRequest(http.MethodGet, "http://example.com/eth/v1/beacon/states/{state_id}/pending_consolidations", nil)
+		sszReq.Header.Set("Accept", "application/octet-stream")
+		sszReq.SetPathValue("state_id", "head")
+		sszRec := httptest.NewRecorder()
+		sszRec.Body = new(bytes.Buffer)
+
+		preElectraServer.GetPendingConsolidations(sszRec, sszReq)
+		require.Equal(t, http.StatusBadRequest, sszRec.Code)
+
+		var sszErrResp struct {
+			Code    int    `json:"code"`
+			Message string `json:"message"`
+		}
+		require.NoError(t, json.Unmarshal(sszRec.Body.Bytes(), &sszErrResp))
+		require.Equal(t, "state_id is prior to electra", sszErrResp.Message)
+	})
+	t.Run("missing state_id parameter", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "http://example.com/eth/v1/beacon/states/{state_id}/pending_consolidations", nil)
+		// Intentionally not setting state_id
+		rec := httptest.NewRecorder()
+		rec.Body = new(bytes.Buffer)
+
+		server.GetPendingConsolidations(rec, req)
+		require.Equal(t, http.StatusBadRequest, rec.Code)
+
+		var errResp struct {
+			Code    int    `json:"code"`
+			Message string `json:"message"`
+		}
+		require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &errResp))
+		require.Equal(t, "state_id is required in URL params", errResp.Message)
+	})
+	t.Run("optimistic node", func(t *testing.T) {
+		optimisticChainService := &chainMock.ChainService{
+			Optimistic:     true,
+			FinalizedRoots: map[[32]byte]bool{},
+		}
+		optimisticServer := &Server{
+			Stater:                server.Stater,
+			OptimisticModeFetcher: optimisticChainService,
+			FinalizationFetcher:   optimisticChainService,
+		}
+
+		req := httptest.NewRequest(http.MethodGet, "http://example.com/eth/v1/beacon/states/{state_id}/pending_consolidations", nil)
+		req.SetPathValue("state_id", "head")
+		rec := httptest.NewRecorder()
+		rec.Body = new(bytes.Buffer)
+
+		optimisticServer.GetPendingConsolidations(rec, req)
+		require.Equal(t, http.StatusOK, rec.Code)
+
+		var resp structs.GetPendingConsolidationsResponse
+		require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+		require.Equal(t, true, resp.ExecutionOptimistic)
+	})
+
+	t.Run("finalized node", func(t *testing.T) {
+		blockRoot, err := st.LatestBlockHeader().HashTreeRoot()
+		require.NoError(t, err)
+
+		finalizedChainService := &chainMock.ChainService{
+			Optimistic:     false,
+			FinalizedRoots: map[[32]byte]bool{blockRoot: true},
+		}
+		finalizedServer := &Server{
+			Stater:                server.Stater,
+			OptimisticModeFetcher: finalizedChainService,
+			FinalizationFetcher:   finalizedChainService,
+		}
+
+		req := httptest.NewRequest(http.MethodGet, "http://example.com/eth/v1/beacon/states/{state_id}/pending_consolidations", nil)
+		req.SetPathValue("state_id", "head")
+		rec := httptest.NewRecorder()
+		rec.Body = new(bytes.Buffer)
+
+		finalizedServer.GetPendingConsolidations(rec, req)
+		require.Equal(t, http.StatusOK, rec.Code)
+
+		var resp structs.GetPendingConsolidationsResponse
+		require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+		require.Equal(t, true, resp.Finalized)
+	})
+}
+
 func TestGetPendingDeposits(t *testing.T) {
 	st, _ := util.DeterministicGenesisStateElectra(t, 10)
 

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

@@ -20,6 +20,7 @@ go_library(
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/transition:go_default_library",
         "//beacon-chain/state:go_default_library",
+        "//beacon-chain/state/stategen:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/interfaces:go_default_library",
         "//consensus-types/payload-attribute:go_default_library",
@@ -53,6 +54,7 @@ go_test(
         "//beacon-chain/core/feed/operation:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",
         "//beacon-chain/state:go_default_library",
+        "//beacon-chain/state/stategen/mock:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",

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

@@ -681,53 +681,45 @@ var zeroRoot [32]byte
 // needsFill allows tests to provide filled EventData values. An ordinary event data value fired by the blockchain package will have
 // all of the checked fields empty, so the logical short circuit should hit immediately.
 func needsFill(ev payloadattribute.EventData) bool {
-	return ev.HeadState == nil || ev.HeadState.IsNil() || ev.HeadState.LatestBlockHeader() == nil ||
-		ev.HeadBlock == nil || ev.HeadBlock.IsNil() ||
-		ev.HeadRoot == zeroRoot || len(ev.ParentBlockRoot) == 0 || len(ev.ParentBlockHash) == 0 ||
+	return len(ev.ParentBlockHash) == 0 ||
 		ev.Attributer == nil || ev.Attributer.IsEmpty()
 }
 
 func (s *Server) fillEventData(ctx context.Context, ev payloadattribute.EventData) (payloadattribute.EventData, error) {
-	var err error
-
 	if !needsFill(ev) {
 		return ev, nil
 	}
-
-	ev.HeadState, err = s.HeadFetcher.HeadState(ctx)
-	if err != nil {
-		return ev, errors.Wrap(err, "could not get head state")
+	if ev.HeadBlock == nil || ev.HeadBlock.IsNil() {
+		return ev, errors.New("head block is nil")
+	}
+	if ev.HeadRoot == zeroRoot {
+		return ev, errors.New("head root is empty")
 	}
 
-	ev.HeadBlock, err = s.HeadFetcher.HeadBlock(ctx)
-	if err != nil {
-		return ev, errors.Wrap(err, "could not look up head block")
-	}
-	ev.HeadRoot, err = ev.HeadBlock.Block().HashTreeRoot()
-	if err != nil {
-		return ev, errors.Wrap(err, "could not compute head block root")
-	}
-	pr := ev.HeadBlock.Block().ParentRoot()
-	ev.ParentBlockRoot = pr[:]
+	var err error
+	var st state.BeaconState
 
-	hsr, err := ev.HeadState.LatestBlockHeader().HashTreeRoot()
-	if err != nil {
-		return ev, errors.Wrap(err, "could not compute latest block header root")
-	}
+	proposalSlot := ev.ProposalSlot
 
-	pse := slots.ToEpoch(ev.ProposalSlot)
-	st := ev.HeadState
-	if slots.ToEpoch(st.Slot()) != pse {
-		st, err = transition.ProcessSlotsUsingNextSlotCache(ctx, st, hsr[:], ev.ProposalSlot)
+	index, err := helpers.GetCachedProposerIndex(st, proposalSlot)
+	if err == nil {
+		ev.ProposerIndex = index
+	} else {
+		st, err = s.StateGen.StateByRoot(ctx, ev.HeadRoot)
+		if err != nil {
+			return ev, errors.Wrap(err, "could not get head state")
+		}
+		st, err = transition.ProcessSlotsUsingNextSlotCache(ctx, st, ev.HeadRoot[:], proposalSlot)
 		if err != nil {
 			return ev, errors.Wrap(err, "could not run process blocks on head state into the proposal slot epoch")
 		}
+		ev.ProposerIndex, err = helpers.BeaconProposerIndexAtSlot(ctx, st, ev.ProposalSlot)
+		if err != nil {
+			return ev, errors.Wrap(err, "failed to compute proposer index")
+		}
 	}
-	ev.ProposerIndex, err = helpers.BeaconProposerIndexAtSlot(ctx, st, ev.ProposalSlot)
-	if err != nil {
-		return ev, errors.Wrap(err, "failed to compute proposer index")
-	}
-	randao, err := helpers.RandaoMix(st, pse)
+
+	randao, err := helpers.RandaoMix(st, slots.ToEpoch(proposalSlot))
 	if err != nil {
 		return ev, errors.Wrap(err, "could not get head state randado")
 	}
@@ -743,7 +735,7 @@ func (s *Server) fillEventData(ctx context.Context, ev payloadattribute.EventDat
 	if err != nil {
 		return ev, errors.Wrap(err, "could not get head state slot time")
 	}
-	ev.Attributer, err = s.computePayloadAttributes(ctx, st, hsr, ev.ProposerIndex, uint64(t.Unix()), randao)
+	ev.Attributer, err = s.computePayloadAttributes(ctx, st, ev.HeadRoot, ev.ProposerIndex, uint64(t.Unix()), randao)
 	return ev, err
 }
 
@@ -772,7 +764,7 @@ func (s *Server) payloadAttributesReader(ctx context.Context, ev payloadattribut
 			ProposerIndex:     strconv.FormatUint(uint64(ev.ProposerIndex), 10),
 			ProposalSlot:      strconv.FormatUint(uint64(ev.ProposalSlot), 10),
 			ParentBlockNumber: strconv.FormatUint(ev.ParentBlockNumber, 10),
-			ParentBlockRoot:   hexutil.Encode(ev.ParentBlockRoot),
+			ParentBlockRoot:   hexutil.Encode(ev.HeadRoot[:]),
 			ParentBlockHash:   hexutil.Encode(ev.ParentBlockHash),
 			PayloadAttributes: attributesBytes,
 		})

beacon-chain/rpc/eth/events/events_test.go

@@ -18,6 +18,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/operation"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/state"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/state/stategen/mock"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
@@ -528,9 +529,13 @@ func TestStreamEvents_OperationsEvents(t *testing.T) {
 					Block: b,
 					Slot:  &currentSlot,
 				}
+				headRoot, err := b.Block().HashTreeRoot()
+				require.NoError(t, err)
 
 				stn := mockChain.NewEventFeedWrapper()
 				opn := mockChain.NewEventFeedWrapper()
+				stategen := mock.NewService()
+				stategen.AddStateForRoot(st, headRoot)
 				s := &Server{
 					StateNotifier:          &mockChain.SimpleNotifier{Feed: stn},
 					OperationNotifier:      &mockChain.SimpleNotifier{Feed: opn},
@@ -538,6 +543,7 @@ func TestStreamEvents_OperationsEvents(t *testing.T) {
 					ChainInfoFetcher:       mockChainService,
 					TrackedValidatorsCache: cache.NewTrackedValidatorsCache(),
 					EventWriteTimeout:      testEventWriteTimeout,
+					StateGen:               stategen,
 				}
 				if tc.SetTrackedValidatorsCache != nil {
 					tc.SetTrackedValidatorsCache(s.TrackedValidatorsCache)
@@ -553,11 +559,9 @@ func TestStreamEvents_OperationsEvents(t *testing.T) {
 							ProposerIndex:     0,
 							ProposalSlot:      0,
 							ParentBlockNumber: 0,
-							ParentBlockRoot:   make([]byte, 32),
 							ParentBlockHash:   make([]byte, 32),
-							HeadState:         st,
 							HeadBlock:         b,
-							HeadRoot:          [fieldparams.RootLength]byte{},
+							HeadRoot:          headRoot,
 						},
 					},
 				}
@@ -575,8 +579,6 @@ func TestStreamEvents_OperationsEvents(t *testing.T) {
 func TestFillEventData(t *testing.T) {
 	ctx := context.Background()
 	t.Run("AlreadyFilledData_ShouldShortCircuitWithoutError", func(t *testing.T) {
-		st, err := util.NewBeaconStateBellatrix()
-		require.NoError(t, err)
 		b, err := blocks.NewSignedBeaconBlock(util.HydrateSignedBeaconBlockBellatrix(&eth.SignedBeaconBlockBellatrix{}))
 		require.NoError(t, err)
 		attributor, err := payloadattribute.New(&enginev1.PayloadAttributes{
@@ -584,11 +586,9 @@ func TestFillEventData(t *testing.T) {
 		})
 		require.NoError(t, err)
 		alreadyFilled := payloadattribute.EventData{
-			HeadState:       st,
 			HeadBlock:       b,
 			HeadRoot:        [32]byte{1, 2, 3},
 			Attributer:      attributor,
-			ParentBlockRoot: []byte{1, 2, 3},
 			ParentBlockHash: []byte{4, 5, 6},
 		}
 		srv := &Server{} // No real HeadFetcher needed here since it won't be called.
@@ -612,12 +612,14 @@ func TestFillEventData(t *testing.T) {
 			Timestamp: uint64(time.Now().Unix()),
 		})
 		require.NoError(t, err)
+		headRoot, err := b.Block().HashTreeRoot()
+		require.NoError(t, err)
 		// Create an event data object missing certain fields:
 		partial := payloadattribute.EventData{
-			// The presence of a nil HeadState, nil HeadBlock, zeroed HeadRoot, etc.
-			// will cause fillEventData to try to fill the values.
 			ProposalSlot: 42,         // different epoch from current slot
 			Attributer:   attributor, // Must be Bellatrix or later
+			HeadBlock:    b,
+			HeadRoot:     headRoot,
 		}
 		currentSlot := primitives.Slot(0)
 		// to avoid slot processing
@@ -629,6 +631,8 @@ func TestFillEventData(t *testing.T) {
 			Slot:  &currentSlot,
 		}
 
+		stategen := mock.NewService()
+		stategen.AddStateForRoot(st, headRoot)
 		stn := mockChain.NewEventFeedWrapper()
 		opn := mockChain.NewEventFeedWrapper()
 		srv := &Server{
@@ -638,16 +642,15 @@ func TestFillEventData(t *testing.T) {
 			ChainInfoFetcher:       mockChainService,
 			TrackedValidatorsCache: cache.NewTrackedValidatorsCache(),
 			EventWriteTimeout:      testEventWriteTimeout,
+			StateGen:               stategen,
 		}
 
 		filled, err := srv.fillEventData(ctx, partial)
 		require.NoError(t, err, "expected successful fill of partial event data")
 
 		// Verify that fields have been updated from the mock data:
-		require.NotNil(t, filled.HeadState, "HeadState should be assigned")
 		require.NotNil(t, filled.HeadBlock, "HeadBlock should be assigned")
 		require.NotEqual(t, [32]byte{}, filled.HeadRoot, "HeadRoot should no longer be zero")
-		require.NotEmpty(t, filled.ParentBlockRoot, "ParentBlockRoot should be filled")
 		require.NotEmpty(t, filled.ParentBlockHash, "ParentBlockHash should be filled")
 		require.Equal(t, uint64(0), filled.ParentBlockNumber, "ParentBlockNumber must match mock block")
 

beacon-chain/rpc/eth/events/server.go

@@ -10,6 +10,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/cache"
 	opfeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/operation"
 	statefeed "github.com/OffchainLabs/prysm/v6/beacon-chain/core/feed/state"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/state/stategen"
 )
 
 // Server defines a server implementation of the http events service,
@@ -23,4 +24,5 @@ type Server struct {
 	KeepAliveInterval      time.Duration
 	EventFeedDepth         int
 	EventWriteTimeout      time.Duration
+	StateGen               stategen.StateManager
 }

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

@@ -19,7 +19,6 @@ go_library(
         "//beacon-chain/rpc/lookup:go_default_library",
         "//config/features:go_default_library",
         "//config/params:go_default_library",
-        "//consensus-types/interfaces:go_default_library",
         "//encoding/bytesutil:go_default_library",
         "//monitoring/tracing/trace:go_default_library",
         "//network/forks:go_default_library",
@@ -27,7 +26,6 @@ go_library(
         "//runtime/version:go_default_library",
         "//time/slots:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
-        "@com_github_pkg_errors//:go_default_library",
         "@com_github_prysmaticlabs_fastssz//:go_default_library",
     ],
 )
@@ -45,12 +43,10 @@ go_test(
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/light-client:go_default_library",
         "//beacon-chain/db/testing:go_default_library",
-        "//beacon-chain/rpc/testutil:go_default_library",
         "//beacon-chain/state: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",
         "//consensus-types/light-client:go_default_library",
         "//consensus-types/primitives:go_default_library",
@@ -61,5 +57,6 @@ go_test(
         "//testing/util:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
         "@com_github_prysmaticlabs_fastssz//:go_default_library",
+        "@org_golang_google_protobuf//proto:go_default_library",
     ],
 )

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

@@ -1,19 +1,15 @@
 package lightclient
 
 import (
-	"context"
 	"fmt"
-	"math"
 	"net/http"
 
 	"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"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/signing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/eth/shared"
 	"github.com/OffchainLabs/prysm/v6/config/features"
 	"github.com/OffchainLabs/prysm/v6/config/params"
-	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
 	"github.com/OffchainLabs/prysm/v6/encoding/bytesutil"
 	"github.com/OffchainLabs/prysm/v6/monitoring/tracing/trace"
 	"github.com/OffchainLabs/prysm/v6/network/forks"
@@ -21,7 +17,6 @@ import (
 	"github.com/OffchainLabs/prysm/v6/runtime/version"
 	"github.com/OffchainLabs/prysm/v6/time/slots"
 	"github.com/ethereum/go-ethereum/common/hexutil"
-	"github.com/pkg/errors"
 	ssz "github.com/prysmaticlabs/fastssz"
 )
 
@@ -197,70 +192,32 @@ func (s *Server) GetLightClientFinalityUpdate(w http.ResponseWriter, req *http.R
 		return
 	}
 
-	ctx, span := trace.StartSpan(req.Context(), "beacon.GetLightClientFinalityUpdate")
+	_, span := trace.StartSpan(req.Context(), "beacon.GetLightClientFinalityUpdate")
 	defer span.End()
 
-	// Finality update needs super majority of sync committee signatures
-	minSyncCommitteeParticipants := float64(params.BeaconConfig().MinSyncCommitteeParticipants)
-	minSignatures := uint64(math.Ceil(minSyncCommitteeParticipants * 2 / 3))
-
-	block, err := s.suitableBlock(ctx, minSignatures)
-	if !shared.WriteBlockFetchError(w, block, err) {
-		return
-	}
-
-	st, err := s.Stater.StateBySlot(ctx, block.Block().Slot())
-	if err != nil {
-		httputil.HandleError(w, "Could not get state: "+err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	attestedRoot := block.Block().ParentRoot()
-	attestedBlock, err := s.Blocker.Block(ctx, attestedRoot[:])
-	if !shared.WriteBlockFetchError(w, block, errors.Wrap(err, "could not get attested block")) {
-		return
-	}
-	attestedSlot := attestedBlock.Block().Slot()
-	attestedState, err := s.Stater.StateBySlot(ctx, attestedSlot)
-	if err != nil {
-		httputil.HandleError(w, "Could not get attested state: "+err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	var finalizedBlock interfaces.ReadOnlySignedBeaconBlock
-	finalizedCheckpoint := attestedState.FinalizedCheckpoint()
-	if finalizedCheckpoint == nil {
-		httputil.HandleError(w, "Attested state does not have a finalized checkpoint", http.StatusInternalServerError)
-		return
-	}
-	finalizedRoot := bytesutil.ToBytes32(finalizedCheckpoint.Root)
-	finalizedBlock, err = s.Blocker.Block(ctx, finalizedRoot[:])
-	if !shared.WriteBlockFetchError(w, block, errors.Wrap(err, "could not get finalized block")) {
-		return
-	}
-
-	update, err := lightclient.NewLightClientFinalityUpdateFromBeaconState(ctx, s.ChainInfoFetcher.CurrentSlot(), st, block, attestedState, attestedBlock, finalizedBlock)
-	if err != nil {
-		httputil.HandleError(w, "Could not get light client finality update: "+err.Error(), http.StatusInternalServerError)
+	update := s.LCStore.LastFinalityUpdate()
+	if update == nil {
+		httputil.HandleError(w, "No light client finality update available", http.StatusNotFound)
 		return
 	}
 
+	w.Header().Set(api.VersionHeader, version.String(update.Version()))
 	if httputil.RespondWithSsz(req) {
-		ssz, err := update.MarshalSSZ()
+		data, err := update.MarshalSSZ()
 		if err != nil {
 			httputil.HandleError(w, "Could not marshal finality update to SSZ: "+err.Error(), http.StatusInternalServerError)
 			return
 		}
-		httputil.WriteSsz(w, ssz)
+		httputil.WriteSsz(w, data)
 	} else {
-		updateStruct, err := structs.LightClientFinalityUpdateFromConsensus(update)
+		data, err := structs.LightClientFinalityUpdateFromConsensus(update)
 		if err != nil {
 			httputil.HandleError(w, "Could not convert light client finality update to API struct: "+err.Error(), http.StatusInternalServerError)
 			return
 		}
 		response := &structs.LightClientFinalityUpdateResponse{
-			Version: version.String(attestedState.Version()),
-			Data:    updateStruct,
+			Version: version.String(update.Version()),
+			Data:    data,
 		}
 		httputil.WriteJson(w, response)
 	}
@@ -273,111 +230,33 @@ func (s *Server) GetLightClientOptimisticUpdate(w http.ResponseWriter, req *http
 		return
 	}
 
-	ctx, span := trace.StartSpan(req.Context(), "beacon.GetLightClientOptimisticUpdate")
+	_, span := trace.StartSpan(req.Context(), "beacon.GetLightClientOptimisticUpdate")
 	defer span.End()
 
-	block, err := s.suitableBlock(ctx, params.BeaconConfig().MinSyncCommitteeParticipants)
-	if !shared.WriteBlockFetchError(w, block, err) {
-		return
-	}
-	st, err := s.Stater.StateBySlot(ctx, block.Block().Slot())
-	if err != nil {
-		httputil.HandleError(w, "could not get state: "+err.Error(), http.StatusInternalServerError)
-		return
-	}
-	attestedRoot := block.Block().ParentRoot()
-	attestedBlock, err := s.Blocker.Block(ctx, attestedRoot[:])
-	if err != nil {
-		httputil.HandleError(w, "Could not get attested block: "+err.Error(), http.StatusInternalServerError)
-		return
-	}
-	if attestedBlock == nil {
-		httputil.HandleError(w, "Attested block is nil", http.StatusInternalServerError)
-		return
-	}
-	attestedSlot := attestedBlock.Block().Slot()
-	attestedState, err := s.Stater.StateBySlot(ctx, attestedSlot)
-	if err != nil {
-		httputil.HandleError(w, "Could not get attested state: "+err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	update, err := lightclient.NewLightClientOptimisticUpdateFromBeaconState(ctx, s.ChainInfoFetcher.CurrentSlot(), st, block, attestedState, attestedBlock)
-	if err != nil {
-		httputil.HandleError(w, "Could not get light client optimistic update: "+err.Error(), http.StatusInternalServerError)
+	update := s.LCStore.LastOptimisticUpdate()
+	if update == nil {
+		httputil.HandleError(w, "No light client optimistic update available", http.StatusNotFound)
 		return
 	}
 
+	w.Header().Set(api.VersionHeader, version.String(update.Version()))
 	if httputil.RespondWithSsz(req) {
-		ssz, err := update.MarshalSSZ()
+		data, err := update.MarshalSSZ()
 		if err != nil {
 			httputil.HandleError(w, "Could not marshal optimistic update to SSZ: "+err.Error(), http.StatusInternalServerError)
 			return
 		}
-		httputil.WriteSsz(w, ssz)
+		httputil.WriteSsz(w, data)
 	} else {
-		updateStruct, err := structs.LightClientOptimisticUpdateFromConsensus(update)
+		data, err := structs.LightClientOptimisticUpdateFromConsensus(update)
 		if err != nil {
 			httputil.HandleError(w, "Could not convert light client optimistic update to API struct: "+err.Error(), http.StatusInternalServerError)
 			return
 		}
 		response := &structs.LightClientOptimisticUpdateResponse{
-			Version: version.String(attestedState.Version()),
-			Data:    updateStruct,
+			Version: version.String(update.Version()),
+			Data:    data,
 		}
 		httputil.WriteJson(w, response)
 	}
 }
-
-// suitableBlock returns the latest block that satisfies all criteria required for creating a new update
-func (s *Server) suitableBlock(ctx context.Context, minSignaturesRequired uint64) (interfaces.ReadOnlySignedBeaconBlock, error) {
-	st, err := s.HeadFetcher.HeadState(ctx)
-	if err != nil {
-		return nil, errors.Wrap(err, "could not get head state")
-	}
-
-	latestBlockHeader := st.LatestBlockHeader()
-	stateRoot, err := st.HashTreeRoot(ctx)
-	if err != nil {
-		return nil, errors.Wrap(err, "could not get state root")
-	}
-	latestBlockHeader.StateRoot = stateRoot[:]
-	latestBlockHeaderRoot, err := latestBlockHeader.HashTreeRoot()
-	if err != nil {
-		return nil, errors.Wrap(err, "could not get latest block header root")
-	}
-
-	block, err := s.Blocker.Block(ctx, latestBlockHeaderRoot[:])
-	if err != nil {
-		return nil, errors.Wrap(err, "could not get latest block")
-	}
-	if block == nil {
-		return nil, errors.New("latest block is nil")
-	}
-
-	// Loop through the blocks until we find a block that satisfies minSignaturesRequired requirement
-	var numOfSyncCommitteeSignatures uint64
-	if syncAggregate, err := block.Block().Body().SyncAggregate(); err == nil {
-		numOfSyncCommitteeSignatures = syncAggregate.SyncCommitteeBits.Count()
-	}
-
-	for numOfSyncCommitteeSignatures < minSignaturesRequired {
-		// Get the parent block
-		parentRoot := block.Block().ParentRoot()
-		block, err = s.Blocker.Block(ctx, parentRoot[:])
-		if err != nil {
-			return nil, errors.Wrap(err, "could not get parent block")
-		}
-		if block == nil {
-			return nil, errors.New("parent block is nil")
-		}
-
-		// Get the number of sync committee signatures
-		numOfSyncCommitteeSignatures = 0
-		if syncAggregate, err := block.Block().Body().SyncAggregate(); err == nil {
-			numOfSyncCommitteeSignatures = syncAggregate.SyncCommitteeBits.Count()
-		}
-	}
-
-	return block, nil
-}

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

@@ -2,6 +2,7 @@ package lightclient
 
 import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain"
+	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/rpc/lookup"
 )
@@ -12,4 +13,5 @@ type Server struct {
 	HeadFetcher      blockchain.HeadFetcher
 	ChainInfoFetcher blockchain.ChainInfoFetcher
 	BeaconDB         db.HeadAccessDatabase
+	LCStore          *lightClient.Store
 }

beacon-chain/rpc/prysm/v1alpha1/beacon/assignments.go

@@ -18,7 +18,7 @@ import (
 
 const errEpoch = "cannot retrieve information about an epoch in the future, current epoch %d, requesting %d"
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListValidatorAssignments retrieves the validator assignments for a given epoch,
 // optional validator indices or public keys may be included to filter validator assignments.

beacon-chain/rpc/prysm/v1alpha1/beacon/attestations.go

@@ -49,7 +49,7 @@ func mapAttestationsByTargetRoot(atts []ethpb.Att) map[[32]byte][]ethpb.Att {
 	return attsMap
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListAttestations retrieves attestations by block root, slot, or epoch.
 // Attestations are sorted by data slot by default.
@@ -115,7 +115,7 @@ func (bs *Server) ListAttestations(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListAttestationsElectra retrieves attestations by block root, slot, or epoch.
 // Attestations are sorted by data slot by default.
@@ -180,7 +180,7 @@ func (bs *Server) ListAttestationsElectra(ctx context.Context, req *ethpb.ListAt
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListIndexedAttestations retrieves indexed attestations by block root.
 // IndexedAttestationsForEpoch are sorted by data slot by default. Start-end epoch
@@ -242,7 +242,7 @@ func (bs *Server) ListIndexedAttestations(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListIndexedAttestationsElectra retrieves indexed attestations by block root.
 // IndexedAttestationsForEpoch are sorted by data slot by default. Start-end epoch
@@ -305,7 +305,7 @@ func (bs *Server) ListIndexedAttestationsElectra(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // AttestationPool retrieves pending attestations.
 //
@@ -350,7 +350,7 @@ func (bs *Server) AttestationPool(_ context.Context, req *ethpb.AttestationPoolR
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 func (bs *Server) AttestationPoolElectra(_ context.Context, req *ethpb.AttestationPoolRequest) (*ethpb.AttestationPoolElectraResponse, error) {
 	var atts []*ethpb.AttestationElectra
 	var err error

beacon-chain/rpc/prysm/v1alpha1/beacon/blocks.go

@@ -26,7 +26,7 @@ type blockContainer struct {
 	isCanonical bool
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListBeaconBlocks retrieves blocks by root, slot, or epoch.
 //
@@ -246,7 +246,7 @@ func (bs *Server) listBlocksForGenesis(ctx context.Context, _ *ethpb.ListBlocksR
 	}}, 1, strconv.Itoa(0), nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetChainHead retrieves information about the head of the beacon chain from
 // the view of the beacon chain node.

beacon-chain/rpc/prysm/v1alpha1/beacon/committees.go

@@ -15,7 +15,7 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListBeaconCommittees for a given epoch.
 //

beacon-chain/rpc/prysm/v1alpha1/beacon/config.go

@@ -10,7 +10,7 @@ import (
 	"google.golang.org/protobuf/types/known/emptypb"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetBeaconConfig retrieves the current configuration parameters of the beacon chain.
 func (_ *Server) GetBeaconConfig(_ context.Context, _ *emptypb.Empty) (*ethpb.BeaconConfig, error) {

beacon-chain/rpc/prysm/v1alpha1/beacon/slashings.go

@@ -11,7 +11,7 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitProposerSlashing receives a proposer slashing object via
 // RPC and injects it into the beacon node's operations pool.
@@ -38,12 +38,12 @@ func (bs *Server) SubmitProposerSlashing(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 func (bs *Server) SubmitAttesterSlashing(ctx context.Context, req *ethpb.AttesterSlashing) (*ethpb.SubmitSlashingResponse, error) {
 	return bs.submitAttesterSlashing(ctx, req)
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitAttesterSlashingElectra receives an attester slashing object via
 // RPC and injects it into the beacon node's operations pool.

beacon-chain/rpc/prysm/v1alpha1/beacon/validators.go

@@ -24,7 +24,7 @@ import (
 	"google.golang.org/protobuf/types/known/emptypb"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListValidatorBalances retrieves the validator balances for a given set of public keys.
 // An optional Epoch parameter is provided to request historical validator balances from
@@ -182,7 +182,7 @@ func (bs *Server) ListValidatorBalances(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListValidators retrieves the current list of active validators with an optional historical epoch flag to
 // retrieve validator set in time.
@@ -342,7 +342,7 @@ func (bs *Server) ListValidators(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetValidator information from any validator in the registry by index or public key.
 func (bs *Server) GetValidator(
@@ -388,7 +388,7 @@ func (bs *Server) GetValidator(
 	return nil, status.Error(codes.NotFound, "No validator matched filter criteria")
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetValidatorActiveSetChanges retrieves the active set changes for a given epoch.
 //
@@ -416,7 +416,7 @@ func (bs *Server) GetValidatorActiveSetChanges(
 	return as, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetValidatorParticipation retrieves the validator participation information for a given epoch,
 // it returns the information about validator's participation rate in voting on the proof of stake
@@ -443,7 +443,7 @@ func (bs *Server) GetValidatorParticipation(
 	return vp, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetValidatorQueue retrieves the current validator queue information.
 func (bs *Server) GetValidatorQueue(
@@ -536,7 +536,7 @@ func (bs *Server) GetValidatorQueue(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetValidatorPerformance reports the validator's latest balance along with other important metrics on
 // rewards and penalties throughout its lifecycle in the beacon chain.
@@ -550,7 +550,7 @@ func (bs *Server) GetValidatorPerformance(
 	return response, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetIndividualVotes retrieves individual voting status of validators.
 func (bs *Server) GetIndividualVotes(

beacon-chain/rpc/prysm/v1alpha1/debug/block.go

@@ -17,7 +17,7 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetBlock in an ssz-encoded format by block root.
 func (ds *Server) GetBlock(
@@ -41,7 +41,7 @@ func (ds *Server) GetBlock(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetInclusionSlot of an attestation in block.
 func (ds *Server) GetInclusionSlot(ctx context.Context, req *pbrpc.InclusionSlotRequest) (*pbrpc.InclusionSlotResponse, error) {

beacon-chain/rpc/prysm/v1alpha1/debug/p2p.go

@@ -13,7 +13,7 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetPeer returns the data known about the peer defined by the provided peer id.
 func (ds *Server) GetPeer(_ context.Context, peerReq *ethpb.PeerRequest) (*ethpb.DebugPeerResponse, error) {
@@ -24,7 +24,7 @@ func (ds *Server) GetPeer(_ context.Context, peerReq *ethpb.PeerRequest) (*ethpb
 	return ds.getPeer(pid)
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListPeers returns all peers known to the host node, regardless of if they are connected/
 // disconnected.

beacon-chain/rpc/prysm/v1alpha1/debug/state.go

@@ -10,7 +10,7 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetBeaconState retrieves an ssz-encoded beacon state
 // from the beacon node by either a slot or block root.

beacon-chain/rpc/prysm/v1alpha1/node/server.go

@@ -49,7 +49,7 @@ type Server struct {
 	BeaconMonitoringPort int
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetHealth checks the health of the node
 func (ns *Server) GetHealth(ctx context.Context, request *ethpb.HealthRequest) (*empty.Empty, error) {
@@ -80,7 +80,7 @@ func (ns *Server) GetHealth(ctx context.Context, request *ethpb.HealthRequest) (
 	return &empty.Empty{}, status.Errorf(codes.Unavailable, "service unavailable")
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetSyncStatus checks the current network sync status of the node.
 func (ns *Server) GetSyncStatus(_ context.Context, _ *empty.Empty) (*ethpb.SyncStatus, error) {
@@ -89,7 +89,7 @@ func (ns *Server) GetSyncStatus(_ context.Context, _ *empty.Empty) (*ethpb.SyncS
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetGenesis fetches genesis chain information of Ethereum. Returns unix timestamp 0
 // if a genesis time has yet to be determined.
@@ -115,7 +115,7 @@ func (ns *Server) GetGenesis(ctx context.Context, _ *empty.Empty) (*ethpb.Genesi
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetVersion checks the version information of the beacon node.
 func (_ *Server) GetVersion(_ context.Context, _ *empty.Empty) (*ethpb.Version, error) {
@@ -124,7 +124,7 @@ func (_ *Server) GetVersion(_ context.Context, _ *empty.Empty) (*ethpb.Version,
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListImplementedServices lists the services implemented and enabled by this node.
 //
@@ -143,7 +143,7 @@ func (ns *Server) ListImplementedServices(_ context.Context, _ *empty.Empty) (*e
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetHost returns the p2p data on the current local and host peer.
 func (ns *Server) GetHost(_ context.Context, _ *empty.Empty) (*ethpb.HostData, error) {
@@ -168,7 +168,7 @@ func (ns *Server) GetHost(_ context.Context, _ *empty.Empty) (*ethpb.HostData, e
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetPeer returns the data known about the peer defined by the provided peer id.
 func (ns *Server) GetPeer(_ context.Context, peerReq *ethpb.PeerRequest) (*ethpb.Peer, error) {
@@ -215,7 +215,7 @@ func (ns *Server) GetPeer(_ context.Context, peerReq *ethpb.PeerRequest) (*ethpb
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ListPeers lists the peers connected to this node.
 func (ns *Server) ListPeers(ctx context.Context, _ *empty.Empty) (*ethpb.Peers, error) {
@@ -270,7 +270,7 @@ func (ns *Server) ListPeers(ctx context.Context, _ *empty.Empty) (*ethpb.Peers,
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetETH1ConnectionStatus gets data about the ETH1 endpoints.
 func (ns *Server) GetETH1ConnectionStatus(_ context.Context, _ *empty.Empty) (*ethpb.ETH1ConnectionStatus, error) {
@@ -286,7 +286,7 @@ func (ns *Server) GetETH1ConnectionStatus(_ context.Context, _ *empty.Empty) (*e
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // StreamBeaconLogs from the beacon node via a gRPC server-side stream.
 // DEPRECATED: This endpoint doesn't appear to be used and have been marked for deprecation.

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

@@ -17,7 +17,7 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitAggregateSelectionProof is called by a validator when its assigned to be an aggregator.
 // The aggregator submits the selection proof to obtain the aggregated attestation
@@ -55,7 +55,7 @@ func (vs *Server) SubmitAggregateSelectionProof(ctx context.Context, req *ethpb.
 	return &ethpb.AggregateSelectionResponse{AggregateAndProof: attAndProof}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitAggregateSelectionProofElectra is called by a validator when its assigned to be an aggregator.
 // The aggregator submits the selection proof to obtain the aggregated attestation
@@ -149,7 +149,7 @@ func (vs *Server) processAggregateSelection(ctx context.Context, req *ethpb.Aggr
 	return indexInCommittee, validatorIndex, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitSignedAggregateSelectionProof is called by a validator to broadcast a signed
 // aggregated and proof object.
@@ -163,7 +163,7 @@ func (vs *Server) SubmitSignedAggregateSelectionProof(
 	return &ethpb.SignedAggregateSubmitResponse{}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitSignedAggregateSelectionProofElectra is called by a validator to broadcast a signed
 // aggregated and proof object.

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

@@ -22,7 +22,7 @@ import (
 	"google.golang.org/protobuf/types/known/emptypb"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetAttestationData requests that the beacon node produce an attestation data object,
 // which the validator acting as an attester will then sign.
@@ -44,7 +44,7 @@ func (vs *Server) GetAttestationData(ctx context.Context, req *ethpb.Attestation
 	return res, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ProposeAttestation is a function called by an attester to vote
 // on a block via an attestation object as defined in the Ethereum specification.
@@ -74,7 +74,7 @@ func (vs *Server) ProposeAttestation(ctx context.Context, att *ethpb.Attestation
 	return resp, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ProposeAttestationElectra is a function called by an attester to vote
 // on a block via an attestation object as defined in the Ethereum specification.
@@ -114,7 +114,7 @@ func (vs *Server) ProposeAttestationElectra(ctx context.Context, singleAtt *ethp
 	return resp, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubscribeCommitteeSubnets subscribes to the committee ID subnet given subscribe request.
 func (vs *Server) SubscribeCommitteeSubnets(ctx context.Context, req *ethpb.CommitteeSubnetsSubscribeRequest) (*emptypb.Empty, error) {

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

@@ -82,7 +82,7 @@ func TestProposeAttestation(t *testing.T) {
 		config := params.BeaconConfig()
 		config.ElectraForkEpoch = 0
 		params.OverrideBeaconConfig(config)
-		
+
 		state, err := util.NewBeaconState()
 		require.NoError(t, err)
 		require.NoError(t, state.SetSlot(params.BeaconConfig().SlotsPerEpoch+1))

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

@@ -9,12 +9,13 @@ import (
 	"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/time/slots"
 	"github.com/pkg/errors"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // StreamBlocksAltair to clients every single time a block is received by the beacon node.
 func (vs *Server) StreamBlocksAltair(req *ethpb.StreamBlocksRequest, stream ethpb.BeaconNodeValidator_StreamBlocksAltairServer) error {
@@ -49,9 +50,9 @@ func (vs *Server) StreamBlocksAltair(req *ethpb.StreamBlocksRequest, stream ethp
 	}
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
-// StreamSlots sends a block's slot to clients every single time a block is received by the beacon node.
+// StreamSlots sends a the block's slot and dependent roots to clients every single time a block is received by the beacon node.
 func (vs *Server) StreamSlots(req *ethpb.StreamSlotsRequest, stream ethpb.BeaconNodeValidator_StreamSlotsServer) error {
 	ch := make(chan *feed.Event, 1)
 	var sub event.Subscription
@@ -85,7 +86,24 @@ func (vs *Server) StreamSlots(req *ethpb.StreamSlotsRequest, stream ethpb.Beacon
 				}
 				s = data.SignedBlock.Block().Slot()
 			}
-			if err := stream.Send(&ethpb.StreamSlotsResponse{Slot: s}); err != nil {
+			currEpoch := slots.ToEpoch(s)
+			currDepRoot, err := vs.ForkchoiceFetcher.DependentRoot(currEpoch)
+			if err != nil {
+				return status.Errorf(codes.Internal, "Could not get dependent root: %v", err)
+			}
+			prevDepRoot := currDepRoot
+			if currEpoch > 0 {
+				prevDepRoot, err = vs.ForkchoiceFetcher.DependentRoot(currEpoch - 1)
+				if err != nil {
+					return status.Errorf(codes.Internal, "Could not get dependent root: %v", err)
+				}
+			}
+			if err := stream.Send(
+				&ethpb.StreamSlotsResponse{
+					Slot:                      s,
+					PreviousDutyDependentRoot: prevDepRoot[:],
+					CurrentDutyDependentRoot:  currDepRoot[:],
+				}); err != nil {
 				return status.Errorf(codes.Unavailable, "Could not send over stream: %v", err)
 			}
 		case <-sub.Err():

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

@@ -297,15 +297,20 @@ func TestServer_StreamSlots_OnHeadUpdated(t *testing.T) {
 
 	chainService := &chainMock.ChainService{}
 	server := &Server{
-		Ctx:           ctx,
-		BlockNotifier: chainService.BlockNotifier(),
+		Ctx:               ctx,
+		ForkchoiceFetcher: chainService,
+		BlockNotifier:     chainService.BlockNotifier(),
 	}
 	exitRoutine := make(chan bool)
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()
 	mockStream := mock.NewMockBeaconNodeValidator_StreamSlotsServer(ctrl)
 
-	mockStream.EXPECT().Send(&ethpb.StreamSlotsResponse{Slot: 123}).Do(func(arg0 interface{}) {
+	mockStream.EXPECT().Send(&ethpb.StreamSlotsResponse{
+		Slot:                      123,
+		PreviousDutyDependentRoot: params.BeaconConfig().ZeroHash[:],
+		CurrentDutyDependentRoot:  params.BeaconConfig().ZeroHash[:],
+	}).Do(func(arg0 interface{}) {
 		exitRoutine <- true
 	})
 	mockStream.EXPECT().Context().Return(ctx).AnyTimes()
@@ -329,14 +334,19 @@ func TestServer_StreamSlotsVerified_OnHeadUpdated(t *testing.T) {
 	ctx := context.Background()
 	chainService := &chainMock.ChainService{}
 	server := &Server{
-		Ctx:           ctx,
-		StateNotifier: chainService.StateNotifier(),
+		Ctx:               ctx,
+		ForkchoiceFetcher: chainService,
+		StateNotifier:     chainService.StateNotifier(),
 	}
 	exitRoutine := make(chan bool)
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()
 	mockStream := mock.NewMockBeaconNodeValidator_StreamSlotsServer(ctrl)
-	mockStream.EXPECT().Send(&ethpb.StreamSlotsResponse{Slot: 123}).Do(func(arg0 interface{}) {
+	mockStream.EXPECT().Send(&ethpb.StreamSlotsResponse{
+		Slot:                      123,
+		PreviousDutyDependentRoot: params.BeaconConfig().ZeroHash[:],
+		CurrentDutyDependentRoot:  params.BeaconConfig().ZeroHash[:],
+	}).Do(func(arg0 interface{}) {
 		exitRoutine <- true
 	})
 	mockStream.EXPECT().Context().Return(ctx).AnyTimes()

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

@@ -16,7 +16,7 @@ import (
 	"google.golang.org/protobuf/types/known/emptypb"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetDuties returns the duties assigned to a list of validators specified
 // in the request object.
@@ -159,13 +159,26 @@ func (vs *Server) duties(ctx context.Context, req *ethpb.DutiesRequest) (*ethpb.
 		validatorAssignments = append(validatorAssignments, assignment)
 		nextValidatorAssignments = append(nextValidatorAssignments, nextAssignment)
 	}
+	currDependentRoot, err := vs.ForkchoiceFetcher.DependentRoot(currentEpoch)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "Could not get dependent root: %v", err)
+	}
+	prevDependentRoot := currDependentRoot
+	if currDependentRoot != [32]byte{} && currentEpoch > 0 {
+		prevDependentRoot, err = vs.ForkchoiceFetcher.DependentRoot(currentEpoch - 1)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "Could not get previous dependent root: %v", err)
+		}
+	}
 	return &ethpb.DutiesResponse{
-		CurrentEpochDuties: validatorAssignments,
-		NextEpochDuties:    nextValidatorAssignments,
+		PreviousDutyDependentRoot: prevDependentRoot[:],
+		CurrentDutyDependentRoot:  currDependentRoot[:],
+		CurrentEpochDuties:        validatorAssignments,
+		NextEpochDuties:           nextValidatorAssignments,
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // AssignValidatorToSubnet checks the status and pubkey of a particular validator
 // to discern whether persistent subnets need to be registered for them.

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

@@ -55,10 +55,11 @@ func TestGetDuties_OK(t *testing.T) {
 		State: bs, Root: genesisRoot[:], Genesis: time.Now(),
 	}
 	vs := &Server{
-		HeadFetcher:    chain,
-		TimeFetcher:    chain,
-		SyncChecker:    &mockSync.Sync{IsSyncing: false},
-		PayloadIDCache: cache.NewPayloadIDCache(),
+		HeadFetcher:       chain,
+		TimeFetcher:       chain,
+		ForkchoiceFetcher: chain,
+		SyncChecker:       &mockSync.Sync{IsSyncing: false},
+		PayloadIDCache:    cache.NewPayloadIDCache(),
 	}
 
 	// Test the first validator in registry.
@@ -140,11 +141,12 @@ func TestGetAltairDuties_SyncCommitteeOK(t *testing.T) {
 		State: bs, Root: genesisRoot[:], Genesis: time.Now().Add(time.Duration(-1*int64(slot-1)) * time.Second),
 	}
 	vs := &Server{
-		HeadFetcher:     chain,
-		TimeFetcher:     chain,
-		Eth1InfoFetcher: &mockExecution.Chain{},
-		SyncChecker:     &mockSync.Sync{IsSyncing: false},
-		PayloadIDCache:  cache.NewPayloadIDCache(),
+		HeadFetcher:       chain,
+		TimeFetcher:       chain,
+		ForkchoiceFetcher: chain,
+		Eth1InfoFetcher:   &mockExecution.Chain{},
+		SyncChecker:       &mockSync.Sync{IsSyncing: false},
+		PayloadIDCache:    cache.NewPayloadIDCache(),
 	}
 
 	// Test the first validator in registry.
@@ -246,11 +248,12 @@ func TestGetBellatrixDuties_SyncCommitteeOK(t *testing.T) {
 		State: bs, Root: genesisRoot[:], Genesis: time.Now().Add(time.Duration(-1*int64(slot-1)) * time.Second),
 	}
 	vs := &Server{
-		HeadFetcher:     chain,
-		TimeFetcher:     chain,
-		Eth1InfoFetcher: &mockExecution.Chain{},
-		SyncChecker:     &mockSync.Sync{IsSyncing: false},
-		PayloadIDCache:  cache.NewPayloadIDCache(),
+		HeadFetcher:       chain,
+		TimeFetcher:       chain,
+		ForkchoiceFetcher: chain,
+		Eth1InfoFetcher:   &mockExecution.Chain{},
+		SyncChecker:       &mockSync.Sync{IsSyncing: false},
+		PayloadIDCache:    cache.NewPayloadIDCache(),
 	}
 
 	// Test the first validator in registry.
@@ -338,12 +341,13 @@ func TestGetAltairDuties_UnknownPubkey(t *testing.T) {
 	require.NoError(t, err)
 
 	vs := &Server{
-		HeadFetcher:     chain,
-		TimeFetcher:     chain,
-		Eth1InfoFetcher: &mockExecution.Chain{},
-		SyncChecker:     &mockSync.Sync{IsSyncing: false},
-		DepositFetcher:  depositCache,
-		PayloadIDCache:  cache.NewPayloadIDCache(),
+		HeadFetcher:       chain,
+		ForkchoiceFetcher: chain,
+		TimeFetcher:       chain,
+		Eth1InfoFetcher:   &mockExecution.Chain{},
+		SyncChecker:       &mockSync.Sync{IsSyncing: false},
+		DepositFetcher:    depositCache,
+		PayloadIDCache:    cache.NewPayloadIDCache(),
 	}
 
 	unknownPubkey := bytesutil.PadTo([]byte{'u'}, 48)
@@ -361,7 +365,8 @@ func TestGetDuties_SlotOutOfUpperBound(t *testing.T) {
 		Genesis: time.Now(),
 	}
 	vs := &Server{
-		TimeFetcher: chain,
+		ForkchoiceFetcher: chain,
+		TimeFetcher:       chain,
 	}
 	req := &ethpb.DutiesRequest{
 		Epoch: primitives.Epoch(chain.CurrentSlot()/params.BeaconConfig().SlotsPerEpoch + 2),
@@ -396,10 +401,11 @@ func TestGetDuties_CurrentEpoch_ShouldNotFail(t *testing.T) {
 		State: bState, Root: genesisRoot[:], Genesis: time.Now(),
 	}
 	vs := &Server{
-		HeadFetcher:    chain,
-		TimeFetcher:    chain,
-		SyncChecker:    &mockSync.Sync{IsSyncing: false},
-		PayloadIDCache: cache.NewPayloadIDCache(),
+		HeadFetcher:       chain,
+		ForkchoiceFetcher: chain,
+		TimeFetcher:       chain,
+		SyncChecker:       &mockSync.Sync{IsSyncing: false},
+		PayloadIDCache:    cache.NewPayloadIDCache(),
 	}
 
 	// Test the first validator in registry.
@@ -435,10 +441,11 @@ func TestGetDuties_MultipleKeys_OK(t *testing.T) {
 		State: bs, Root: genesisRoot[:], Genesis: time.Now(),
 	}
 	vs := &Server{
-		HeadFetcher:    chain,
-		TimeFetcher:    chain,
-		SyncChecker:    &mockSync.Sync{IsSyncing: false},
-		PayloadIDCache: cache.NewPayloadIDCache(),
+		HeadFetcher:       chain,
+		ForkchoiceFetcher: chain,
+		TimeFetcher:       chain,
+		SyncChecker:       &mockSync.Sync{IsSyncing: false},
+		PayloadIDCache:    cache.NewPayloadIDCache(),
 	}
 
 	pubkey0 := deposits[0].Data.PublicKey

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

@@ -12,7 +12,7 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ProposeExit proposes an exit for a validator.
 func (vs *Server) ProposeExit(ctx context.Context, req *ethpb.SignedVoluntaryExit) (*ethpb.ProposeExitResponse, error) {

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

@@ -45,7 +45,7 @@ const (
 	defaultBuilderBoostFactor = primitives.Gwei(100)
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetBeaconBlock is called by a proposer during its assigned slot to request a block to sign
 // by passing in the slot and the signed randao reveal of the slot.
@@ -271,7 +271,7 @@ func (vs *Server) BuildBlockParallel(ctx context.Context, sBlk interfaces.Signed
 	return vs.constructGenericBeaconBlock(sBlk, bundle, winningBid)
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ProposeBeaconBlock handles the proposal of beacon blocks.
 func (vs *Server) ProposeBeaconBlock(ctx context.Context, req *ethpb.GenericSignedBeaconBlock) (*ethpb.ProposeResponse, error) {
@@ -412,7 +412,7 @@ func (vs *Server) broadcastAndReceiveBlobs(ctx context.Context, sidecars []*ethp
 	return eg.Wait()
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // PrepareBeaconProposer caches and updates the fee recipient for the given proposer.
 func (vs *Server) PrepareBeaconProposer(
@@ -449,7 +449,7 @@ func (vs *Server) PrepareBeaconProposer(
 	return &emptypb.Empty{}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetFeeRecipientByPubKey returns a fee recipient from the beacon node's settings or db based on a given public key
 func (vs *Server) GetFeeRecipientByPubKey(ctx context.Context, request *ethpb.FeeRecipientByPubKeyRequest) (*ethpb.FeeRecipientByPubKeyResponse, error) {
@@ -506,7 +506,7 @@ func (vs *Server) computeStateRoot(ctx context.Context, block interfaces.ReadOnl
 	return root[:], nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitValidatorRegistrations submits validator registrations.
 func (vs *Server) SubmitValidatorRegistrations(ctx context.Context, reg *ethpb.SignedValidatorRegistrationsV1) (*emptypb.Empty, error) {

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

@@ -82,7 +82,7 @@ type Server struct {
 	AttestationStateFetcher blockchain.AttestationStateFetcher
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // WaitForActivation checks if a validator public key exists in the active validator registry of the current
 // beacon state, if not, then it creates a stream which listens for canonical states which contain
@@ -132,7 +132,7 @@ func (vs *Server) WaitForActivation(req *ethpb.ValidatorActivationRequest, strea
 	}
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ValidatorIndex is called by a validator to get its index location in the beacon state.
 func (vs *Server) ValidatorIndex(ctx context.Context, req *ethpb.ValidatorIndexRequest) (*ethpb.ValidatorIndexResponse, error) {
@@ -151,7 +151,7 @@ func (vs *Server) ValidatorIndex(ctx context.Context, req *ethpb.ValidatorIndexR
 	return &ethpb.ValidatorIndexResponse{Index: index}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // DomainData fetches the current domain version information from the beacon state.
 func (vs *Server) DomainData(ctx context.Context, request *ethpb.DomainRequest) (*ethpb.DomainResponse, error) {
@@ -183,7 +183,7 @@ func (vs *Server) DomainData(ctx context.Context, request *ethpb.DomainRequest)
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // WaitForChainStart queries the logs of the Deposit Contract in order to verify the beacon chain
 // has started its runtime and validators begin their responsibilities. If it has not, it then

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

@@ -29,7 +29,7 @@ var nonExistentIndex = primitives.ValidatorIndex(^uint64(0))
 
 var errParticipation = status.Errorf(codes.Internal, "Failed to obtain epoch participation")
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // ValidatorStatus returns the validator status of the current epoch.
 // The status response can be one of the following:
@@ -54,7 +54,7 @@ func (vs *Server) ValidatorStatus(
 	return vStatus, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // MultipleValidatorStatus is the same as ValidatorStatus. Supports retrieval of multiple
 // validator statuses. Takes a list of public keys or a list of validator indices.
@@ -104,7 +104,7 @@ func (vs *Server) MultipleValidatorStatus(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // CheckDoppelGanger checks if the provided keys are currently active in the network.
 func (vs *Server) CheckDoppelGanger(ctx context.Context, req *ethpb.DoppelGangerRequest) (*ethpb.DoppelGangerResponse, error) {

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

@@ -12,7 +12,7 @@ import (
 	"google.golang.org/protobuf/types/known/emptypb"
 )
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetSyncMessageBlockRoot retrieves the sync committee block root of the beacon chain.
 func (vs *Server) GetSyncMessageBlockRoot(
@@ -34,7 +34,7 @@ func (vs *Server) GetSyncMessageBlockRoot(
 	}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitSyncMessage submits the sync committee message to the network.
 // It also saves the sync committee message into the pending pool for block inclusion.
@@ -45,7 +45,7 @@ func (vs *Server) SubmitSyncMessage(ctx context.Context, msg *ethpb.SyncCommitte
 	return &emptypb.Empty{}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetSyncSubcommitteeIndex is called by a sync committee participant to get
 // its subcommittee index for sync message aggregation duty.
@@ -63,7 +63,7 @@ func (vs *Server) GetSyncSubcommitteeIndex(
 	return &ethpb.SyncSubcommitteeIndexResponse{Indices: indices}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // GetSyncCommitteeContribution is called by a sync committee aggregator
 // to retrieve sync committee contribution object.
@@ -106,7 +106,7 @@ func (vs *Server) GetSyncCommitteeContribution(
 	return contribution, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // SubmitSignedContributionAndProof is called by a sync committee aggregator
 // to submit signed contribution and proof object.
@@ -120,7 +120,7 @@ func (vs *Server) SubmitSignedContributionAndProof(
 	return &emptypb.Empty{}, nil
 }
 
-// Deprecated: gRPC API will still be supported for some time, most likely until v8 in 2026, but will be eventually removed in favor of REST API.
+// Deprecated: The gRPC API will remain the default and fully supported through v8 (expected in 2026) but will be eventually removed in favor of REST API.
 //
 // AggregatedSigAndAggregationBits returns the aggregated signature and aggregation bits
 // associated with a particular set of sync committee messages.

beacon-chain/rpc/service.go

@@ -16,6 +16,7 @@ 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"
@@ -121,6 +122,7 @@ type Config struct {
 	BlobStorage               *filesystem.BlobStorage
 	TrackedValidatorsCache    *cache.TrackedValidatorsCache
 	PayloadIDCache            *cache.PayloadIDCache
+	LCStore                   *lightClient.Store
 }
 
 // NewService instantiates a new RPC service instance that will

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

@@ -62,9 +62,11 @@ func (b *BeaconState) NextWithdrawalValidatorIndex() (primitives.ValidatorIndex,
 //
 //			validator = state.validators[withdrawal.index]
 //			has_sufficient_effective_balance = validator.effective_balance >= MIN_ACTIVATION_BALANCE
-//			has_excess_balance = state.balances[withdrawal.index] > MIN_ACTIVATION_BALANCE
+//			total_withdrawn = sum(w.amount for w in withdrawals if w.validator_index == withdrawal.validator_index)
+//			balance = state.balances[withdrawal.validator_index] - total_withdrawn
+//			has_excess_balance = balance > MIN_ACTIVATION_BALANCE
 //			if validator.exit_epoch == FAR_FUTURE_EPOCH and has_sufficient_effective_balance and has_excess_balance:
-//				withdrawable_balance = min(state.balances[withdrawal.index] - MIN_ACTIVATION_BALANCE, withdrawal.amount)
+//				withdrawable_balance = min(balance - MIN_ACTIVATION_BALANCE, withdrawal.amount)
 //				withdrawals.append(Withdrawal(
 //					index=withdrawal_index,
 //					validator_index=withdrawal.index,
@@ -132,9 +134,19 @@ func (b *BeaconState) ExpectedWithdrawals() ([]*enginev1.Withdrawal, uint64, err
 				return nil, 0, fmt.Errorf("could not retrieve balance at index %d: %w", w.Index, err)
 			}
 			hasSufficientEffectiveBalance := v.EffectiveBalance() >= params.BeaconConfig().MinActivationBalance
-			hasExcessBalance := vBal > params.BeaconConfig().MinActivationBalance
+			var totalWithdrawn uint64
+			for _, wi := range withdrawals {
+				if wi.ValidatorIndex == w.Index {
+					totalWithdrawn += wi.Amount
+				}
+			}
+			balance, err := mathutil.Sub64(vBal, totalWithdrawn)
+			if err != nil {
+				return nil, 0, errors.Wrapf(err, "failed to subtract balance %d with total withdrawn %d", vBal, totalWithdrawn)
+			}
+			hasExcessBalance := balance > params.BeaconConfig().MinActivationBalance
 			if v.ExitEpoch() == params.BeaconConfig().FarFutureEpoch && hasSufficientEffectiveBalance && hasExcessBalance {
-				amount := min(vBal-params.BeaconConfig().MinActivationBalance, w.Amount)
+				amount := min(balance-params.BeaconConfig().MinActivationBalance, w.Amount)
 				withdrawals = append(withdrawals, &enginev1.Withdrawal{
 					Index:          withdrawalIndex,
 					ValidatorIndex: w.Index,
@@ -165,7 +177,10 @@ func (b *BeaconState) ExpectedWithdrawals() ([]*enginev1.Withdrawal, uint64, err
 					partiallyWithdrawnBalance += w.Amount
 				}
 			}
-			balance = balance - partiallyWithdrawnBalance
+			balance, err = mathutil.Sub64(balance, partiallyWithdrawnBalance)
+			if err != nil {
+				return nil, 0, errors.Wrapf(err, "could not subtract balance %d with partial withdrawn balance %d", balance, partiallyWithdrawnBalance)
+			}
 		}
 		if helpers.IsFullyWithdrawableValidator(val, balance, epoch, b.version) {
 			withdrawals = append(withdrawals, &enginev1.Withdrawal{

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

@@ -416,3 +416,37 @@ func TestExpectedWithdrawals(t *testing.T) {
 		require.DeepEqual(t, withdrawalFull, expected[1])
 	})
 }
+
+func TestExpectedWithdrawals_underflow_electra(t *testing.T) {
+	s, err := state_native.InitializeFromProtoUnsafeElectra(&ethpb.BeaconStateElectra{})
+	require.NoError(t, err)
+	vals := make([]*ethpb.Validator, 1)
+	balances := make([]uint64, 1)
+	balances[0] = 2015_000_000_000 //Validator A begins leaking ETH due to inactivity, and over time, its balance decreases to 2,015 ETH
+	val := &ethpb.Validator{
+		WithdrawalCredentials: make([]byte, 32),
+		EffectiveBalance:      params.BeaconConfig().MaxEffectiveBalanceElectra,
+		WithdrawableEpoch:     primitives.Epoch(0),
+		ExitEpoch:             params.BeaconConfig().FarFutureEpoch,
+	}
+	val.WithdrawalCredentials[0] = params.BeaconConfig().CompoundingWithdrawalPrefixByte
+	val.WithdrawalCredentials[31] = byte(0)
+	vals[0] = val
+
+	require.NoError(t, s.SetValidators(vals))
+	require.NoError(t, s.SetBalances(balances))
+	require.NoError(t, s.AppendPendingPartialWithdrawal(&ethpb.PendingPartialWithdrawal{
+		Amount:            1008_000_000_000,
+		WithdrawableEpoch: primitives.Epoch(0),
+	}))
+	require.NoError(t, s.AppendPendingPartialWithdrawal(&ethpb.PendingPartialWithdrawal{
+		Amount:            1008_000_000_000,
+		WithdrawableEpoch: primitives.Epoch(0),
+	}))
+	expected, _, err := s.ExpectedWithdrawals()
+	require.NoError(t, err)
+	require.Equal(t, 3, len(expected)) // is a fully withdrawable validator
+	require.Equal(t, uint64(1008_000_000_000), expected[0].Amount)
+	require.Equal(t, uint64(975_000_000_000), expected[1].Amount)
+	require.Equal(t, uint64(32_000_000_000), expected[2].Amount)
+}

beacon-chain/state/stategen/mock/mock.go

@@ -23,8 +23,8 @@ func NewService() *StateManager {
 }
 
 // StateByRootIfCachedNoCopy --
-func (_ *StateManager) StateByRootIfCachedNoCopy(_ [32]byte) state.BeaconState {
-	panic("implement me")
+func (m *StateManager) StateByRootIfCachedNoCopy(root [32]byte) state.BeaconState {
+	return m.StatesByRoot[root]
 }
 
 // Resume --

beacon-chain/sync/BUILD.bazel

@@ -211,6 +211,7 @@ go_test(
         "//beacon-chain/operations/attestations:go_default_library",
         "//beacon-chain/operations/blstoexec:go_default_library",
         "//beacon-chain/operations/slashings:go_default_library",
+        "//beacon-chain/operations/slashings/mock:go_default_library",
         "//beacon-chain/p2p:go_default_library",
         "//beacon-chain/p2p/encoder:go_default_library",
         "//beacon-chain/p2p/peers:go_default_library",

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

@@ -60,6 +60,7 @@ go_test(
         "blocks_fetcher_test.go",
         "blocks_fetcher_utils_test.go",
         "blocks_queue_test.go",
+        "downscore_test.go",
         "fsm_benchmark_test.go",
         "fsm_test.go",
         "initial_sync_test.go",
@@ -70,6 +71,7 @@ go_test(
     tags = ["CI_race_detection"],
     deps = [
         "//async/abool:go_default_library",
+        "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/das:go_default_library",
         "//beacon-chain/db:go_default_library",
@@ -78,6 +80,7 @@ go_test(
         "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/p2p:go_default_library",
         "//beacon-chain/p2p/peers:go_default_library",
+        "//beacon-chain/p2p/peers/peerdata:go_default_library",
         "//beacon-chain/p2p/peers/scorers:go_default_library",
         "//beacon-chain/p2p/testing:go_default_library",
         "//beacon-chain/p2p/types:go_default_library",
@@ -105,6 +108,7 @@ go_test(
         "@com_github_libp2p_go_libp2p//core/network:go_default_library",
         "@com_github_libp2p_go_libp2p//core/peer:go_default_library",
         "@com_github_paulbellamy_ratecounter//:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
         "@com_github_sirupsen_logrus//:go_default_library",
         "@com_github_sirupsen_logrus//hooks/test:go_default_library",
     ],

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

@@ -120,11 +120,20 @@ type fetchRequestParams struct {
 // fetchRequestResponse is a combined type to hold results of both successful executions and errors.
 // Valid usage pattern will be to check whether result's `err` is nil, before using `blocks`.
 type fetchRequestResponse struct {
-	pid   peer.ID
-	start primitives.Slot
-	count uint64
-	bwb   []blocks.BlockWithROBlobs
-	err   error
+	blocksFrom peer.ID
+	blobsFrom  peer.ID
+	start      primitives.Slot
+	count      uint64
+	bwb        []blocks.BlockWithROBlobs
+	err        error
+}
+
+func (r *fetchRequestResponse) blocksQueueFetchedData() *blocksQueueFetchedData {
+	return &blocksQueueFetchedData{
+		blocksFrom: r.blocksFrom,
+		blobsFrom:  r.blobsFrom,
+		bwb:        r.bwb,
+	}
 }
 
 // newBlocksFetcher creates ready to use fetcher.
@@ -314,13 +323,14 @@ func (f *blocksFetcher) handleRequest(ctx context.Context, start primitives.Slot
 		}
 	}
 
-	response.bwb, response.pid, response.err = f.fetchBlocksFromPeer(ctx, start, count, peers)
+	response.bwb, response.blocksFrom, response.err = f.fetchBlocksFromPeer(ctx, start, count, peers)
 	if response.err == nil {
-		bwb, err := f.fetchBlobsFromPeer(ctx, response.bwb, response.pid, peers)
+		pid, bwb, err := f.fetchBlobsFromPeer(ctx, response.bwb, response.blocksFrom, peers)
 		if err != nil {
 			response.err = err
 		}
 		response.bwb = bwb
+		response.blobsFrom = pid
 	}
 	return response
 }
@@ -537,20 +547,20 @@ func missingCommitError(root [32]byte, slot primitives.Slot, missing [][]byte) e
 }
 
 // fetchBlobsFromPeer fetches blocks from a single randomly selected peer.
-func (f *blocksFetcher) fetchBlobsFromPeer(ctx context.Context, bwb []blocks.BlockWithROBlobs, pid peer.ID, peers []peer.ID) ([]blocks.BlockWithROBlobs, error) {
+func (f *blocksFetcher) fetchBlobsFromPeer(ctx context.Context, bwb []blocks.BlockWithROBlobs, pid peer.ID, peers []peer.ID) (peer.ID, []blocks.BlockWithROBlobs, error) {
 	ctx, span := trace.StartSpan(ctx, "initialsync.fetchBlobsFromPeer")
 	defer span.End()
 	if slots.ToEpoch(f.clock.CurrentSlot()) < params.BeaconConfig().DenebForkEpoch {
-		return bwb, nil
+		return "", bwb, nil
 	}
 	blobWindowStart, err := prysmsync.BlobRPCMinValidSlot(f.clock.CurrentSlot())
 	if err != nil {
-		return nil, err
+		return "", nil, err
 	}
 	// Construct request message based on observed interval of blocks in need of blobs.
 	req := countCommitments(bwb, blobWindowStart).blobRange(f.bs).Request()
 	if req == nil {
-		return bwb, nil
+		return "", bwb, nil
 	}
 	peers = f.filterPeers(ctx, peers, peersPercentagePerRequest)
 	// We dial the initial peer first to ensure that we get the desired set of blobs.
@@ -573,9 +583,9 @@ func (f *blocksFetcher) fetchBlobsFromPeer(ctx context.Context, bwb []blocks.Blo
 			log.WithField("peer", p).WithError(err).Debug("Invalid BeaconBlobsByRange response")
 			continue
 		}
-		return robs, err
+		return p, robs, err
 	}
-	return nil, errNoPeersAvailable
+	return "", nil, errNoPeersAvailable
 }
 
 // requestBlocks is a wrapper for handling BeaconBlocksByRangeRequest requests/streams.

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

@@ -22,8 +22,9 @@ import (
 // Blocks are stored in an ascending slot order. The first block is guaranteed to have parent
 // either in DB or initial sync cache.
 type forkData struct {
-	peer peer.ID
-	bwb  []blocks.BlockWithROBlobs
+	blocksFrom peer.ID
+	blobsFrom  peer.ID
+	bwb        []blocks.BlockWithROBlobs
 }
 
 // nonSkippedSlotAfter checks slots after the given one in an attempt to find a non-empty future slot.
@@ -280,13 +281,13 @@ func (f *blocksFetcher) findForkWithPeer(ctx context.Context, pid peer.ID, slot
 		}
 		// We need to fetch the blobs for the given alt-chain if any exist, so that we can try to verify and import
 		// the blocks.
-		bwb, err := f.fetchBlobsFromPeer(ctx, altBlocks, pid, []peer.ID{pid})
+		bpid, bwb, err := f.fetchBlobsFromPeer(ctx, altBlocks, pid, []peer.ID{pid})
 		if err != nil {
 			return nil, errors.Wrap(err, "unable to retrieve blobs for blocks found in findForkWithPeer")
 		}
 		// The caller will use the BlocksWith VerifiedBlobs in bwb as the starting point for
 		// round-robin syncing the alternate chain.
-		return &forkData{peer: pid, bwb: bwb}, nil
+		return &forkData{blocksFrom: pid, blobsFrom: bpid, bwb: bwb}, nil
 	}
 	return nil, errNoAlternateBlocks
 }
@@ -302,13 +303,15 @@ func (f *blocksFetcher) findAncestor(ctx context.Context, pid peer.ID, b interfa
 			if err != nil {
 				return nil, errors.Wrap(err, "received invalid blocks in findAncestor")
 			}
-			bwb, err = f.fetchBlobsFromPeer(ctx, bwb, pid, []peer.ID{pid})
+			var bpid peer.ID
+			bpid, bwb, err = f.fetchBlobsFromPeer(ctx, bwb, pid, []peer.ID{pid})
 			if err != nil {
 				return nil, errors.Wrap(err, "unable to retrieve blobs for blocks found in findAncestor")
 			}
 			return &forkData{
-				peer: pid,
-				bwb:  bwb,
+				blocksFrom: pid,
+				bwb:        bwb,
+				blobsFrom:  bpid,
 			}, nil
 		}
 		// Request block's parent.

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

@@ -263,7 +263,7 @@ func TestBlocksFetcher_findFork(t *testing.T) {
 	reqEnd := testForkStartSlot(t, 251) + primitives.Slot(findForkReqRangeSize())
 	require.Equal(t, primitives.Slot(len(chain1)), fork.bwb[0].Block.Block().Slot())
 	require.Equal(t, int(reqEnd-forkSlot1b), len(fork.bwb))
-	require.Equal(t, curForkMoreBlocksPeer, fork.peer)
+	require.Equal(t, curForkMoreBlocksPeer, fork.blocksFrom)
 	// Save all chain1b blocks (so that they do not interfere with alternative fork)
 	for _, blk := range chain1b {
 		util.SaveBlock(t, ctx, beaconDB, blk)
@@ -283,7 +283,7 @@ func TestBlocksFetcher_findFork(t *testing.T) {
 	alternativePeer := connectPeerHavingBlocks(t, p2p, chain2, finalizedSlot, p2p.Peers())
 	fork, err = fetcher.findFork(ctx, 251)
 	require.NoError(t, err)
-	assert.Equal(t, alternativePeer, fork.peer)
+	assert.Equal(t, alternativePeer, fork.blocksFrom)
 	assert.Equal(t, 65, len(fork.bwb))
 	ind := forkSlot
 	for _, blk := range fork.bwb {

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

@@ -10,6 +10,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/startup"
 	beaconsync "github.com/OffchainLabs/prysm/v6/beacon-chain/sync"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	"github.com/OffchainLabs/prysm/v6/time/slots"
@@ -93,8 +94,9 @@ type blocksQueue struct {
 
 // blocksQueueFetchedData is a data container that is returned from a queue on each step.
 type blocksQueueFetchedData struct {
-	pid peer.ID
-	bwb []blocks.BlockWithROBlobs
+	blocksFrom peer.ID
+	blobsFrom  peer.ID
+	bwb        []blocks.BlockWithROBlobs
 }
 
 // newBlocksQueue creates initialized priority queue.
@@ -337,13 +339,15 @@ func (q *blocksQueue) onDataReceivedEvent(ctx context.Context) eventHandlerFn {
 			}
 			if errors.Is(response.err, beaconsync.ErrInvalidFetchedData) {
 				// Peer returned invalid data, penalize.
-				q.blocksFetcher.p2p.Peers().Scorers().BadResponsesScorer().Increment(m.pid)
-				log.WithField("pid", response.pid).Debug("Peer is penalized for invalid blocks")
+				q.blocksFetcher.p2p.Peers().Scorers().BadResponsesScorer().Increment(response.blocksFrom)
+				log.WithField("pid", response.blocksFrom).Debug("Peer is penalized for invalid blocks")
+			} else if errors.Is(response.err, verification.ErrBlobInvalid) {
+				q.blocksFetcher.p2p.Peers().Scorers().BadResponsesScorer().Increment(response.blobsFrom)
+				log.WithField("pid", response.blobsFrom).Debug("Peer is penalized for invalid blob response")
 			}
 			return m.state, response.err
 		}
-		m.pid = response.pid
-		m.bwb = response.bwb
+		m.fetched = *response
 		return stateDataParsed, nil
 	}
 }
@@ -358,19 +362,15 @@ func (q *blocksQueue) onReadyToSendEvent(ctx context.Context) eventHandlerFn {
 			return m.state, errInvalidInitialState
 		}
 
-		if len(m.bwb) == 0 {
+		if m.numFetched() == 0 {
 			return stateSkipped, nil
 		}
 
 		send := func() (stateID, error) {
-			data := &blocksQueueFetchedData{
-				pid: m.pid,
-				bwb: m.bwb,
-			}
 			select {
 			case <-ctx.Done():
 				return m.state, ctx.Err()
-			case q.fetchedData <- data:
+			case q.fetchedData <- m.fetched.blocksQueueFetchedData():
 			}
 			return stateSent, nil
 		}

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

@@ -472,8 +472,8 @@ func TestBlocksQueue_onDataReceivedEvent(t *testing.T) {
 		updatedState, err := handlerFn(&stateMachine{
 			state: stateScheduled,
 		}, &fetchRequestResponse{
-			pid: "abc",
-			err: errSlotIsTooHigh,
+			blocksFrom: "abc",
+			err:        errSlotIsTooHigh,
 		})
 		assert.ErrorContains(t, errSlotIsTooHigh.Error(), err)
 		assert.Equal(t, stateScheduled, updatedState)
@@ -495,9 +495,9 @@ func TestBlocksQueue_onDataReceivedEvent(t *testing.T) {
 		updatedState, err := handlerFn(&stateMachine{
 			state: stateScheduled,
 		}, &fetchRequestResponse{
-			pid:   "abc",
-			err:   errSlotIsTooHigh,
-			start: 256,
+			blocksFrom: "abc",
+			err:        errSlotIsTooHigh,
+			start:      256,
 		})
 		assert.ErrorContains(t, errSlotIsTooHigh.Error(), err)
 		assert.Equal(t, stateScheduled, updatedState)
@@ -517,8 +517,8 @@ func TestBlocksQueue_onDataReceivedEvent(t *testing.T) {
 		updatedState, err := handlerFn(&stateMachine{
 			state: stateScheduled,
 		}, &fetchRequestResponse{
-			pid: "abc",
-			err: beaconsync.ErrInvalidFetchedData,
+			blocksFrom: "abc",
+			err:        beaconsync.ErrInvalidFetchedData,
 		})
 		assert.ErrorContains(t, beaconsync.ErrInvalidFetchedData.Error(), err)
 		assert.Equal(t, stateScheduled, updatedState)
@@ -537,7 +537,7 @@ func TestBlocksQueue_onDataReceivedEvent(t *testing.T) {
 		wsbCopy, err := wsb.Copy()
 		require.NoError(t, err)
 		response := &fetchRequestResponse{
-			pid: "abc",
+			blocksFrom: "abc",
 			bwb: []blocks.BlockWithROBlobs{
 				{Block: blocks.ROBlock{ReadOnlySignedBeaconBlock: wsb}},
 				{Block: blocks.ROBlock{ReadOnlySignedBeaconBlock: wsbCopy}},
@@ -546,13 +546,15 @@ func TestBlocksQueue_onDataReceivedEvent(t *testing.T) {
 		fsm := &stateMachine{
 			state: stateScheduled,
 		}
-		assert.Equal(t, peer.ID(""), fsm.pid)
-		assert.Equal(t, 0, len(fsm.bwb))
+		assert.Equal(t, peer.ID(""), fsm.fetched.blocksFrom)
+		assert.Equal(t, peer.ID(""), fsm.fetched.blobsFrom)
+		assert.Equal(t, 0, fsm.numFetched())
 		updatedState, err := handlerFn(fsm, response)
 		assert.NoError(t, err)
 		assert.Equal(t, stateDataParsed, updatedState)
-		assert.Equal(t, response.pid, fsm.pid)
-		assert.DeepSSZEqual(t, response.bwb, fsm.bwb)
+		assert.Equal(t, response.blocksFrom, fsm.fetched.blocksFrom)
+		assert.Equal(t, response.blobsFrom, fsm.fetched.blobsFrom)
+		assert.DeepSSZEqual(t, response.bwb, fsm.fetched.bwb)
 	})
 }
 
@@ -635,10 +637,10 @@ func TestBlocksQueue_onReadyToSendEvent(t *testing.T) {
 		queue.smm.addStateMachine(256)
 		queue.smm.addStateMachine(320)
 		queue.smm.machines[256].state = stateDataParsed
-		queue.smm.machines[256].pid = pidDataParsed
+		queue.smm.machines[256].fetched.blocksFrom = pidDataParsed
 		rwsb, err := blocks.NewROBlock(wsb)
 		require.NoError(t, err)
-		queue.smm.machines[256].bwb = []blocks.BlockWithROBlobs{
+		queue.smm.machines[256].fetched.bwb = []blocks.BlockWithROBlobs{
 			{Block: rwsb},
 		}
 
@@ -669,10 +671,10 @@ func TestBlocksQueue_onReadyToSendEvent(t *testing.T) {
 		queue.smm.machines[256].state = stateDataParsed
 		queue.smm.addStateMachine(320)
 		queue.smm.machines[320].state = stateDataParsed
-		queue.smm.machines[320].pid = pidDataParsed
+		queue.smm.machines[320].fetched.blocksFrom = pidDataParsed
 		rwsb, err := blocks.NewROBlock(wsb)
 		require.NoError(t, err)
-		queue.smm.machines[320].bwb = []blocks.BlockWithROBlobs{
+		queue.smm.machines[320].fetched.bwb = []blocks.BlockWithROBlobs{
 			{Block: rwsb},
 		}
 
@@ -700,10 +702,10 @@ func TestBlocksQueue_onReadyToSendEvent(t *testing.T) {
 		queue.smm.machines[256].state = stateSkipped
 		queue.smm.addStateMachine(320)
 		queue.smm.machines[320].state = stateDataParsed
-		queue.smm.machines[320].pid = pidDataParsed
+		queue.smm.machines[320].fetched.blocksFrom = pidDataParsed
 		rwsb, err := blocks.NewROBlock(wsb)
 		require.NoError(t, err)
-		queue.smm.machines[320].bwb = []blocks.BlockWithROBlobs{
+		queue.smm.machines[320].fetched.bwb = []blocks.BlockWithROBlobs{
 			{Block: rwsb},
 		}
 
@@ -1199,17 +1201,17 @@ func TestBlocksQueue_stuckInUnfavourableFork(t *testing.T) {
 		firstFSM, ok := queue.smm.findStateMachine(forkedSlot)
 		require.Equal(t, true, ok)
 		require.Equal(t, stateDataParsed, firstFSM.state)
-		require.Equal(t, forkedPeer, firstFSM.pid)
+		require.Equal(t, forkedPeer, firstFSM.fetched.blocksFrom)
 		reqEnd := testForkStartSlot(t, 251) + primitives.Slot(findForkReqRangeSize())
-		require.Equal(t, int(reqEnd-forkedSlot), len(firstFSM.bwb))
-		require.Equal(t, forkedSlot, firstFSM.bwb[0].Block.Block().Slot())
+		require.Equal(t, int(reqEnd-forkedSlot), len(firstFSM.fetched.bwb))
+		require.Equal(t, forkedSlot, firstFSM.fetched.bwb[0].Block.Block().Slot())
 
 		// Assert that forked data from chain2 is available (within 64 fetched blocks).
 		for i, blk := range chain2[forkedSlot:] {
-			if i >= len(firstFSM.bwb) {
+			if i >= len(firstFSM.fetched.bwb) {
 				break
 			}
-			rootFromFSM := firstFSM.bwb[i].Block.Root()
+			rootFromFSM := firstFSM.fetched.bwb[i].Block.Root()
 			blkRoot, err := blk.Block.HashTreeRoot()
 			require.NoError(t, err)
 			assert.Equal(t, blkRoot, rootFromFSM)
@@ -1217,7 +1219,7 @@ func TestBlocksQueue_stuckInUnfavourableFork(t *testing.T) {
 
 		// Assert that machines are in the expected state.
 		startSlot = forkedEpochStartSlot.Add(1 + blocksPerRequest)
-		require.Equal(t, int(blocksPerRequest)-int(forkedSlot-(forkedEpochStartSlot+1)), len(firstFSM.bwb))
+		require.Equal(t, int(blocksPerRequest)-int(forkedSlot-(forkedEpochStartSlot+1)), len(firstFSM.fetched.bwb))
 		for i := startSlot; i < startSlot.Add(blocksPerRequest*(lookaheadSteps-1)); i += primitives.Slot(blocksPerRequest) {
 			fsm, ok := queue.smm.findStateMachine(i)
 			require.Equal(t, true, ok)

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

@@ -24,8 +24,8 @@ func (q *blocksQueue) resetFromFork(fork *forkData) error {
 		return err
 	}
 	fsm := q.smm.addStateMachine(firstBlock.Slot())
-	fsm.pid = fork.peer
-	fsm.bwb = fork.bwb
+	fsm.fetched.bwb = fork.bwb
+	fsm.fetched.blocksFrom, fsm.fetched.blobsFrom = fork.blocksFrom, fork.blobsFrom
 	fsm.state = stateDataParsed
 
 	// The rest of machines are in skipped state.

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

@@ -0,0 +1,219 @@
+package initialsync
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain"
+	mock "github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/testing"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/peers/peerdata"
+	p2pt "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/startup"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/sync"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
+	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
+	"github.com/OffchainLabs/prysm/v6/testing/assert"
+	"github.com/OffchainLabs/prysm/v6/testing/require"
+	"github.com/libp2p/go-libp2p/core/peer"
+	"github.com/pkg/errors"
+)
+
+type testDownscorePeer int
+
+const (
+	testDownscoreNeither testDownscorePeer = iota
+	testDownscoreBlock
+	testDownscoreBlob
+)
+
+func peerIDForTestDownscore(w testDownscorePeer, name string) peer.ID {
+	switch w {
+	case testDownscoreBlock:
+		return peer.ID("block" + name)
+	case testDownscoreBlob:
+		return peer.ID("blob" + name)
+	default:
+		return ""
+	}
+}
+
+func TestUpdatePeerScorerStats(t *testing.T) {
+	cases := []struct {
+		name      string
+		err       error
+		processed uint64
+		downPeer  testDownscorePeer
+	}{
+		{
+			name:      "invalid block",
+			err:       blockchain.ErrInvalidPayload,
+			downPeer:  testDownscoreBlock,
+			processed: 10,
+		},
+		{
+			name:      "invalid blob",
+			err:       verification.ErrBlobIndexInvalid,
+			downPeer:  testDownscoreBlob,
+			processed: 3,
+		},
+		{
+			name:      "not validity error",
+			err:       errors.New("test"),
+			processed: 32,
+		},
+		{
+			name:      "no error",
+			processed: 32,
+		},
+	}
+	s := &Service{
+		cfg: &Config{
+			P2P: p2pt.NewTestP2P(t),
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			data := &blocksQueueFetchedData{
+				blocksFrom: peerIDForTestDownscore(testDownscoreBlock, c.name),
+				blobsFrom:  peerIDForTestDownscore(testDownscoreBlob, c.name),
+			}
+			s.updatePeerScorerStats(data, c.processed, c.err)
+			if c.err != nil && c.downPeer != testDownscoreNeither {
+				switch c.downPeer {
+				case testDownscoreBlock:
+					// block should be downscored
+					blocksCount, err := s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Count(data.blocksFrom)
+					require.NoError(t, err)
+					require.Equal(t, 1, blocksCount)
+					// blob should not be downscored - also we expect a not found error since peer scoring did not interact with blobs
+					blobCount, err := s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Count(data.blobsFrom)
+					require.ErrorIs(t, err, peerdata.ErrPeerUnknown)
+					require.Equal(t, -1, blobCount)
+				case testDownscoreBlob:
+					// block should not be downscored - also we expect a not found error since peer scoring did not interact with blocks
+					blocksCount, err := s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Count(data.blocksFrom)
+					require.ErrorIs(t, err, peerdata.ErrPeerUnknown)
+					require.Equal(t, -1, blocksCount)
+					// blob should be downscored
+					blobCount, err := s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Count(data.blobsFrom)
+					require.NoError(t, err)
+					require.Equal(t, 1, blobCount)
+				}
+				assert.Equal(t, uint64(0), s.cfg.P2P.Peers().Scorers().BlockProviderScorer().ProcessedBlocks(data.blocksFrom))
+				return
+			}
+			// block should not be downscored - also we expect a not found error since peer scoring did not interact with blocks
+			blocksCount, err := s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Count(data.blocksFrom)
+			// The scorer will know about the the block peer because it will have a processed blocks count
+			require.NoError(t, err)
+			require.Equal(t, 0, blocksCount)
+			// no downscore, so scorer doesn't know the peer
+			blobCount, err := s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Count(data.blobsFrom)
+			require.ErrorIs(t, err, peerdata.ErrPeerUnknown)
+			require.Equal(t, -1, blobCount)
+
+			assert.Equal(t, c.processed, s.cfg.P2P.Peers().Scorers().BlockProviderScorer().ProcessedBlocks(data.blocksFrom))
+		})
+	}
+}
+
+func TestOnDataReceivedDownscore(t *testing.T) {
+	cases := []struct {
+		name     string
+		err      error
+		downPeer testDownscorePeer
+	}{
+		{
+			name:     "invalid block",
+			err:      sync.ErrInvalidFetchedData,
+			downPeer: testDownscoreBlock,
+		},
+		{
+			name:     "invalid blob",
+			err:      errors.Wrap(verification.ErrBlobInvalid, "test"),
+			downPeer: testDownscoreBlob,
+		},
+		{
+			name: "not validity error",
+			err:  errors.New("test"),
+		},
+		{
+			name: "no error",
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			data := &fetchRequestResponse{
+				blocksFrom: peerIDForTestDownscore(testDownscoreBlock, c.name),
+				blobsFrom:  peerIDForTestDownscore(testDownscoreBlob, c.name),
+				err:        c.err,
+			}
+			if c.downPeer == testDownscoreBlob {
+				require.Equal(t, true, verification.IsBlobValidationFailure(c.err))
+			}
+			ctx := context.Background()
+			p2p := p2pt.NewTestP2P(t)
+			mc := &mock.ChainService{Genesis: time.Now(), ValidatorsRoot: [32]byte{}}
+			fetcher := newBlocksFetcher(ctx, &blocksFetcherConfig{
+				chain: mc,
+				p2p:   p2p,
+				clock: startup.NewClock(mc.Genesis, mc.ValidatorsRoot),
+			})
+			q := newBlocksQueue(ctx, &blocksQueueConfig{
+				p2p:                 p2p,
+				blocksFetcher:       fetcher,
+				highestExpectedSlot: primitives.Slot(32),
+				chain:               mc})
+			sm := q.smm.addStateMachine(0)
+			sm.state = stateScheduled
+			handle := q.onDataReceivedEvent(context.Background())
+			endState, err := handle(sm, data)
+			if c.err != nil {
+				require.ErrorIs(t, err, c.err)
+			} else {
+				require.NoError(t, err)
+			}
+			// state machine should stay in "scheduled" if there's an error
+			// and transition to "data parsed" if there's no error
+			if c.err != nil {
+				require.Equal(t, stateScheduled, endState)
+			} else {
+				require.Equal(t, stateDataParsed, endState)
+			}
+			if c.err != nil && c.downPeer != testDownscoreNeither {
+				switch c.downPeer {
+				case testDownscoreBlock:
+					// block should be downscored
+					blocksCount, err := p2p.Peers().Scorers().BadResponsesScorer().Count(data.blocksFrom)
+					require.NoError(t, err)
+					require.Equal(t, 1, blocksCount)
+					// blob should not be downscored - also we expect a not found error since peer scoring did not interact with blobs
+					blobCount, err := p2p.Peers().Scorers().BadResponsesScorer().Count(data.blobsFrom)
+					require.ErrorIs(t, err, peerdata.ErrPeerUnknown)
+					require.Equal(t, -1, blobCount)
+				case testDownscoreBlob:
+					// block should not be downscored - also we expect a not found error since peer scoring did not interact with blocks
+					blocksCount, err := p2p.Peers().Scorers().BadResponsesScorer().Count(data.blocksFrom)
+					require.ErrorIs(t, err, peerdata.ErrPeerUnknown)
+					require.Equal(t, -1, blocksCount)
+					// blob should be downscored
+					blobCount, err := p2p.Peers().Scorers().BadResponsesScorer().Count(data.blobsFrom)
+					require.NoError(t, err)
+					require.Equal(t, 1, blobCount)
+				}
+				assert.Equal(t, uint64(0), p2p.Peers().Scorers().BlockProviderScorer().ProcessedBlocks(data.blocksFrom))
+				return
+			}
+			// block should not be downscored - also we expect a not found error since peer scoring did not interact with blocks
+			blocksCount, err := p2p.Peers().Scorers().BadResponsesScorer().Count(data.blocksFrom)
+			// no downscore, so scorer doesn't know the peer
+			require.ErrorIs(t, err, peerdata.ErrPeerUnknown)
+			require.Equal(t, -1, blocksCount)
+			blobCount, err := p2p.Peers().Scorers().BadResponsesScorer().Count(data.blobsFrom)
+			// no downscore, so scorer doesn't know the peer
+			require.ErrorIs(t, err, peerdata.ErrPeerUnknown)
+			require.Equal(t, -1, blobCount)
+		})
+	}
+}

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

@@ -6,11 +6,9 @@ import (
 	"sort"
 	"time"
 
-	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/primitives"
 	prysmTime "github.com/OffchainLabs/prysm/v6/time"
 	"github.com/OffchainLabs/prysm/v6/time/slots"
-	"github.com/libp2p/go-libp2p/core/peer"
 )
 
 const (
@@ -45,8 +43,7 @@ type stateMachine struct {
 	smm     *stateMachineManager
 	start   primitives.Slot
 	state   stateID
-	pid     peer.ID
-	bwb     []blocks.BlockWithROBlobs
+	fetched fetchRequestResponse
 	updated time.Time
 }
 
@@ -78,7 +75,7 @@ func (smm *stateMachineManager) addStateMachine(startSlot primitives.Slot) *stat
 		smm:     smm,
 		start:   startSlot,
 		state:   stateNew,
-		bwb:     []blocks.BlockWithROBlobs{},
+		fetched: fetchRequestResponse{},
 		updated: prysmTime.Now(),
 	}
 	smm.recalculateMachineAttribs()
@@ -90,7 +87,7 @@ func (smm *stateMachineManager) removeStateMachine(startSlot primitives.Slot) er
 	if _, ok := smm.machines[startSlot]; !ok {
 		return fmt.Errorf("state for machine %v is not found", startSlot)
 	}
-	smm.machines[startSlot].bwb = nil
+	smm.machines[startSlot].fetched = fetchRequestResponse{}
 	delete(smm.machines, startSlot)
 	smm.recalculateMachineAttribs()
 	return nil
@@ -187,6 +184,10 @@ func (m *stateMachine) isLast() bool {
 	return m.start == m.smm.keys[len(m.smm.keys)-1]
 }
 
+func (m *stateMachine) numFetched() int {
+	return len(m.fetched.bwb)
+}
+
 // String returns human-readable representation of a FSM state.
 func (m *stateMachine) String() string {
 	return fmt.Sprintf("{%d:%s}", slots.ToEpoch(m.start), m.state)

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

@@ -14,7 +14,6 @@ import (
 	"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/libp2p/go-libp2p/core/peer"
 	"github.com/paulbellamy/ratecounter"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -127,7 +126,7 @@ func (s *Service) syncToNonFinalizedEpoch(ctx context.Context) error {
 	}
 	for data := range queue.fetchedData {
 		count, err := s.processFetchedDataRegSync(ctx, data)
-		s.updatePeerScorerStats(data.pid, count, err)
+		s.updatePeerScorerStats(data, count, err)
 	}
 	log.WithFields(logrus.Fields{
 		"syncedSlot":  s.cfg.Chain.HeadSlot(),
@@ -147,7 +146,7 @@ func (s *Service) processFetchedData(ctx context.Context, data *blocksQueueFetch
 	if err != nil {
 		log.WithError(err).Warn("Skip processing batched blocks")
 	}
-	s.updatePeerScorerStats(data.pid, count, err)
+	s.updatePeerScorerStats(data, count, err)
 }
 
 // processFetchedDataRegSync processes data received from queue.
@@ -339,18 +338,19 @@ func isPunishableError(err error) bool {
 }
 
 // updatePeerScorerStats adjusts monitored metrics for a peer.
-func (s *Service) updatePeerScorerStats(pid peer.ID, count uint64, err error) {
-	if pid == "" {
-		return
-	}
+func (s *Service) updatePeerScorerStats(data *blocksQueueFetchedData, count uint64, err error) {
 	if isPunishableError(err) {
-		log.WithError(err).WithField("peer_id", pid).Warn("Incrementing peers bad response count")
-		s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Increment(pid)
+		if verification.IsBlobValidationFailure(err) {
+			log.WithError(err).WithField("peer_id", data.blobsFrom).Warn("Downscoring peer for invalid blobs")
+			s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Increment(data.blobsFrom)
+		} else {
+			log.WithError(err).WithField("peer_id", data.blocksFrom).Warn("Downscoring peer for invalid blocks")
+			s.cfg.P2P.Peers().Scorers().BadResponsesScorer().Increment(data.blocksFrom)
+		}
 		// If the error is punishable, exit here so that we don't give them credit for providing bad blocks.
 		return
 	}
-	scorer := s.cfg.P2P.Peers().Scorers().BlockProviderScorer()
-	scorer.IncrementProcessedBlocks(pid, count)
+	s.cfg.P2P.Peers().Scorers().BlockProviderScorer().IncrementProcessedBlocks(data.blocksFrom, count)
 }
 
 // isProcessedBlock checks DB and local cache for presence of a given block, to avoid duplicates.

beacon-chain/sync/rpc_blob_sidecars_by_root_test.go

@@ -156,7 +156,7 @@ func readChunkEncodedBlobsLowMax(t *testing.T, s *Service, expect []*expectedBlo
 	}
 	return func(stream network.Stream) {
 		_, err := readChunkEncodedBlobs(stream, encoding, ctxMap, vf, 1)
-		require.ErrorIs(t, err, ErrInvalidFetchedData)
+		require.ErrorIs(t, err, errMaxRequestBlobSidecarsExceeded)
 	}
 }
 

beacon-chain/sync/rpc_send_request.go

@@ -9,6 +9,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/encoder"
 	p2ptypes "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/types"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
@@ -30,14 +31,14 @@ var errBlobUnmarshal = errors.New("Could not unmarshal chunk-encoded blob")
 var (
 	// ErrInvalidFetchedData is used to signal that an error occurred which should result in peer downscoring.
 	ErrInvalidFetchedData             = errors.New("invalid data returned from peer")
-	errBlobIndexOutOfBounds           = errors.Wrap(ErrInvalidFetchedData, "blob index out of range")
-	errMaxRequestBlobSidecarsExceeded = errors.Wrap(ErrInvalidFetchedData, "peer exceeded req blob chunk tx limit")
-	errChunkResponseSlotNotAsc        = errors.Wrap(ErrInvalidFetchedData, "blob slot not higher than previous block root")
-	errChunkResponseIndexNotAsc       = errors.Wrap(ErrInvalidFetchedData, "blob indices for a block must start at 0 and increase by 1")
-	errUnrequested                    = errors.Wrap(ErrInvalidFetchedData, "received BlobSidecar in response that was not requested")
-	errBlobResponseOutOfBounds        = errors.Wrap(ErrInvalidFetchedData, "received BlobSidecar with slot outside BlobSidecarsByRangeRequest bounds")
-	errChunkResponseBlockMismatch     = errors.Wrap(ErrInvalidFetchedData, "blob block details do not match")
-	errChunkResponseParentMismatch    = errors.Wrap(ErrInvalidFetchedData, "parent root for response element doesn't match previous element root")
+	errBlobIndexOutOfBounds           = errors.Wrap(verification.ErrBlobInvalid, "blob index out of range")
+	errMaxRequestBlobSidecarsExceeded = errors.Wrap(verification.ErrBlobInvalid, "peer exceeded req blob chunk tx limit")
+	errChunkResponseSlotNotAsc        = errors.Wrap(verification.ErrBlobInvalid, "blob slot not higher than previous block root")
+	errChunkResponseIndexNotAsc       = errors.Wrap(verification.ErrBlobInvalid, "blob indices for a block must start at 0 and increase by 1")
+	errUnrequested                    = errors.Wrap(verification.ErrBlobInvalid, "received BlobSidecar in response that was not requested")
+	errBlobResponseOutOfBounds        = errors.Wrap(verification.ErrBlobInvalid, "received BlobSidecar with slot outside BlobSidecarsByRangeRequest bounds")
+	errChunkResponseBlockMismatch     = errors.Wrap(verification.ErrBlobInvalid, "blob block details do not match")
+	errChunkResponseParentMismatch    = errors.Wrap(verification.ErrBlobInvalid, "parent root for response element doesn't match previous element root")
 )
 
 // BeaconBlockProcessor defines a block processing function, which allows to start utilizing

beacon-chain/sync/rpc_send_request_test.go

@@ -12,6 +12,7 @@ import (
 	p2ptest "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
 	p2pTypes "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/types"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/startup"
+	"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"
@@ -877,3 +878,7 @@ func TestSendBlobsByRangeRequest(t *testing.T) {
 		assert.Equal(t, int(totalElectraBlobs), len(blobs))
 	})
 }
+
+func TestErrInvalidFetchedDataDistinction(t *testing.T) {
+	require.Equal(t, false, errors.Is(ErrInvalidFetchedData, verification.ErrBlobInvalid))
+}

beacon-chain/sync/subscriber.go

@@ -350,10 +350,9 @@ func (s *Service) wrapAndReportValidation(topic string, v wrappedVal) (string, p
 	}
 }
 
-// reValidateSubscriptions unsubscribe from topics we are currently subscribed to but that are
+// pruneSubscriptions unsubscribe from topics we are currently subscribed to but that are
 // not in the list of wanted subnets.
-// TODO: Rename this functions as it does not only revalidate subscriptions.
-func (s *Service) reValidateSubscriptions(
+func (s *Service) pruneSubscriptions(
 	subscriptions map[uint64]*pubsub.Subscription,
 	wantedSubs []uint64,
 	topicFormat string,
@@ -452,7 +451,7 @@ func (s *Service) subscribeToSubnets(
 			"digest":  fmt.Sprintf("%#x", digest),
 			"subnets": description,
 		}).Debug("Subnets with this digest are no longer valid, unsubscribing from all of them")
-		s.reValidateSubscriptions(subscriptions, []uint64{}, topicFormat, digest)
+		s.pruneSubscriptions(subscriptions, []uint64{}, topicFormat, digest)
 		return false
 	}
 
@@ -460,7 +459,7 @@ func (s *Service) subscribeToSubnets(
 	subnetsToSubscribeIndex := getSubnetsToSubscribe(currentSlot)
 
 	// Remove subscriptions that are no longer wanted.
-	s.reValidateSubscriptions(subscriptions, subnetsToSubscribeIndex, topicFormat, digest)
+	s.pruneSubscriptions(subscriptions, subnetsToSubscribeIndex, topicFormat, digest)
 
 	// Subscribe to wanted subnets.
 	for _, subnetIndex := range subnetsToSubscribeIndex {

beacon-chain/sync/subscriber_test.go

@@ -308,7 +308,7 @@ func TestRevalidateSubscription_CorrectlyFormatsTopic(t *testing.T) {
 	subscriptions[2], err = r.cfg.p2p.SubscribeToTopic(fullTopic)
 	require.NoError(t, err)
 
-	r.reValidateSubscriptions(subscriptions, []uint64{2}, defaultTopic, digest)
+	r.pruneSubscriptions(subscriptions, []uint64{2}, defaultTopic, digest)
 	require.LogsDoNotContain(t, hook, "Could not unregister topic validator")
 }
 

beacon-chain/sync/validate_beacon_blocks.go

@@ -21,6 +21,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/encoding/bytesutil"
 	"github.com/OffchainLabs/prysm/v6/monitoring/tracing"
 	"github.com/OffchainLabs/prysm/v6/monitoring/tracing/trace"
+	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
 	"github.com/OffchainLabs/prysm/v6/runtime/version"
 	prysmTime "github.com/OffchainLabs/prysm/v6/time"
 	"github.com/OffchainLabs/prysm/v6/time/slots"
@@ -31,8 +32,9 @@ import (
 )
 
 var (
-	ErrOptimisticParent    = errors.New("parent of the block is optimistic")
-	errRejectCommitmentLen = errors.New("[REJECT] The length of KZG commitments is less than or equal to the limitation defined in Consensus Layer")
+	ErrOptimisticParent         = errors.New("parent of the block is optimistic")
+	errRejectCommitmentLen      = errors.New("[REJECT] The length of KZG commitments is less than or equal to the limitation defined in Consensus Layer")
+	ErrSlashingSignatureFailure = errors.New("proposer slashing signature verification failed")
 )
 
 // validateBeaconBlockPubSub checks that the incoming block has a valid BLS signature.
@@ -109,6 +111,16 @@ func (s *Service) validateBeaconBlockPubSub(ctx context.Context, pid peer.ID, ms
 
 	// Verify the block is the first block received for the proposer for the slot.
 	if s.hasSeenBlockIndexSlot(blk.Block().Slot(), blk.Block().ProposerIndex()) {
+		// Attempt to detect and broadcast equivocation before ignoring
+		err = s.detectAndBroadcastEquivocation(ctx, blk)
+		if err != nil {
+			// If signature verification fails, reject the block
+			if errors.Is(err, ErrSlashingSignatureFailure) {
+				return pubsub.ValidationReject, err
+			}
+			// In case there is some other error log but don't reject
+			log.WithError(err).Debug("Could not detect/broadcast equivocation")
+		}
 		return pubsub.ValidationIgnore, nil
 	}
 
@@ -469,3 +481,74 @@ func getBlockFields(b interfaces.ReadOnlySignedBeaconBlock) logrus.Fields {
 		"version":       b.Block().Version(),
 	}
 }
+
+// detectAndBroadcastEquivocation checks if the given block is an equivocating block by comparing it with
+// the head block. If the blocks are from the same slot and proposer but have different signatures,
+// it creates and broadcasts a proposer slashing object after verification.
+func (s *Service) detectAndBroadcastEquivocation(ctx context.Context, blk interfaces.ReadOnlySignedBeaconBlock) error {
+	slot := blk.Block().Slot()
+	proposerIndex := blk.Block().ProposerIndex()
+
+	// Get head block for comparison
+	headBlock, err := s.cfg.chain.HeadBlock(ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not get head block")
+	}
+
+	// Only proceed if this block is from same slot and proposer as head
+	if headBlock.Block().Slot() != slot || headBlock.Block().ProposerIndex() != proposerIndex {
+		return nil
+	}
+
+	// Compare signatures
+	sig1 := blk.Signature()
+	sig2 := headBlock.Signature()
+
+	// If signatures match, these are the same block
+	if sig1 == sig2 {
+		return nil
+	}
+
+	// Extract headers for slashing
+	header1, err := blk.Header()
+	if err != nil {
+		return errors.Wrap(err, "could not get header from new block")
+	}
+	header2, err := headBlock.Header()
+	if err != nil {
+		return errors.Wrap(err, "could not get header from head block")
+	}
+
+	slashing := &ethpb.ProposerSlashing{
+		Header_1: header1,
+		Header_2: header2,
+	}
+
+	// Get state for verification
+	headState, err := s.cfg.chain.HeadStateReadOnly(ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not get head state")
+	}
+
+	// Verify the slashing against current state
+	if err := blocks.VerifyProposerSlashing(headState, slashing); err != nil {
+		if errors.Is(err, blocks.ErrCouldNotVerifyBlockHeader) {
+			return errors.Wrap(ErrSlashingSignatureFailure, err.Error())
+		}
+		return errors.Wrap(err, "could not verify proposer slashing")
+	}
+
+	// Broadcast if verification passes
+	if !features.Get().DisableBroadcastSlashings {
+		if err := s.cfg.p2p.Broadcast(ctx, slashing); err != nil {
+			return errors.Wrap(err, "could not broadcast slashing object")
+		}
+	}
+
+	// Insert into slashing pool
+	if err := s.cfg.slashingPool.InsertProposerSlashing(ctx, headState, slashing); err != nil {
+		return errors.Wrap(err, "could not insert proposer slashing into pool")
+	}
+
+	return nil
+}

beacon-chain/sync/validate_beacon_blocks_test.go

@@ -18,6 +18,7 @@ import (
 	dbtest "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
 	doublylinkedtree "github.com/OffchainLabs/prysm/v6/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/operations/attestations"
+	slashingsmock "github.com/OffchainLabs/prysm/v6/beacon-chain/operations/slashings/mock"
 	"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"
@@ -713,8 +714,21 @@ func TestValidateBeaconBlockPubSub_SeenProposerSlot(t *testing.T) {
 	msg.Signature, err = signing.ComputeDomainAndSign(beaconState, 0, msg.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[proposerIdx])
 	require.NoError(t, err)
 
-	chainService := &mock.ChainService{Genesis: time.Unix(time.Now().Unix()-int64(params.BeaconConfig().SecondsPerSlot), 0),
-		State: beaconState,
+	// Create a clone of the same block (same signature, not an equivocation)
+	msgClone := util.NewBeaconBlock()
+	msgClone.Block.Slot = 1
+	msgClone.Block.ProposerIndex = proposerIdx
+	msgClone.Block.ParentRoot = bRoot[:]
+	msgClone.Signature = msg.Signature // Use the same signature
+
+	signedBlock, err := blocks.NewSignedBeaconBlock(msg)
+	require.NoError(t, err)
+
+	slashingPool := &slashingsmock.PoolMock{}
+	chainService := &mock.ChainService{
+		Genesis: time.Unix(time.Now().Unix()-int64(params.BeaconConfig().SecondsPerSlot), 0),
+		State:   beaconState,
+		Block:   signedBlock, // Set the first block as the head block
 		FinalizedCheckPoint: &ethpb.Checkpoint{
 			Epoch: 0,
 			Root:  make([]byte, 32),
@@ -728,6 +742,7 @@ func TestValidateBeaconBlockPubSub_SeenProposerSlot(t *testing.T) {
 			chain:         chainService,
 			clock:         startup.NewClock(chainService.Genesis, chainService.ValidatorsRoot),
 			blockNotifier: chainService.BlockNotifier(),
+			slashingPool:  slashingPool,
 		},
 		seenBlockCache:      lruwrpr.New(10),
 		badBlockCache:       lruwrpr.New(10),
@@ -735,10 +750,15 @@ func TestValidateBeaconBlockPubSub_SeenProposerSlot(t *testing.T) {
 		seenPendingBlocks:   make(map[[32]byte]bool),
 	}
 
+	// Mark the proposer/slot as seen
+	r.setSeenBlockIndexSlot(msg.Block.Slot, msg.Block.ProposerIndex)
+	time.Sleep(10 * time.Millisecond) // Wait for cached value to pass through buffers
+
+	// Prepare and validate the second message (clone)
 	buf := new(bytes.Buffer)
-	_, err = p.Encoding().EncodeGossip(buf, msg)
+	_, err = p.Encoding().EncodeGossip(buf, msgClone)
 	require.NoError(t, err)
-	topic := p2p.GossipTypeMapping[reflect.TypeOf(msg)]
+	topic := p2p.GossipTypeMapping[reflect.TypeOf(msgClone)]
 	digest, err := r.currentForkDigest()
 	assert.NoError(t, err)
 	topic = r.addDigestToTopic(topic, digest)
@@ -748,11 +768,14 @@ func TestValidateBeaconBlockPubSub_SeenProposerSlot(t *testing.T) {
 			Topic: &topic,
 		},
 	}
-	r.setSeenBlockIndexSlot(msg.Block.Slot, msg.Block.ProposerIndex)
-	time.Sleep(10 * time.Millisecond) // Wait for cached value to pass through buffers.
+
+	// Since this is not an equivocation (same signature), it should be ignored
 	res, err := r.validateBeaconBlockPubSub(ctx, "", m)
 	assert.NoError(t, err)
-	assert.Equal(t, res, pubsub.ValidationIgnore, "seen proposer block should be ignored")
+	assert.Equal(t, pubsub.ValidationIgnore, res, "block with same signature should be ignored")
+
+	// Verify no slashings were created
+	assert.Equal(t, 0, len(slashingPool.PendingPropSlashings), "Expected no slashings for same signature")
 }
 
 func TestValidateBeaconBlockPubSub_FilterByFinalizedEpoch(t *testing.T) {
@@ -1495,3 +1518,218 @@ func Test_validateDenebBeaconBlock(t *testing.T) {
 	require.NoError(t, err)
 	require.ErrorIs(t, validateDenebBeaconBlock(bdb.Block()), errRejectCommitmentLen)
 }
+
+func TestDetectAndBroadcastEquivocation(t *testing.T) {
+	ctx := context.Background()
+	p := p2ptest.NewTestP2P(t)
+	beaconState, privKeys := util.DeterministicGenesisState(t, 100)
+
+	t.Run("no equivocation", func(t *testing.T) {
+		block := util.NewBeaconBlock()
+		block.Block.Slot = 1
+		block.Block.ProposerIndex = 0
+
+		sig, err := signing.ComputeDomainAndSign(beaconState, 0, block.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[0])
+		require.NoError(t, err)
+		block.Signature = sig
+
+		// Create head block with different slot/proposer
+		headBlock := util.NewBeaconBlock()
+		headBlock.Block.Slot = 2          // Different slot
+		headBlock.Block.ProposerIndex = 1 // Different proposer
+		signedHeadBlock, err := blocks.NewSignedBeaconBlock(headBlock)
+		require.NoError(t, err)
+
+		chainService := &mock.ChainService{
+			State:   beaconState,
+			Genesis: time.Now(),
+			Block:   signedHeadBlock,
+		}
+
+		slashingPool := &slashingsmock.PoolMock{}
+		r := &Service{
+			cfg: &config{
+				p2p:          p,
+				chain:        chainService,
+				slashingPool: slashingPool,
+			},
+			seenBlockCache: lruwrpr.New(10),
+		}
+
+		signedBlock, err := blocks.NewSignedBeaconBlock(block)
+		require.NoError(t, err)
+
+		err = r.detectAndBroadcastEquivocation(ctx, signedBlock)
+		require.NoError(t, err)
+		assert.Equal(t, 0, len(slashingPool.PendingPropSlashings), "Expected no slashings")
+	})
+
+	t.Run("equivocation detected", func(t *testing.T) {
+		// Create head block
+		headBlock := util.NewBeaconBlock()
+		headBlock.Block.Slot = 1
+		headBlock.Block.ProposerIndex = 0
+		headBlock.Block.ParentRoot = bytesutil.PadTo([]byte("parent1"), 32)
+		sig1, err := signing.ComputeDomainAndSign(beaconState, 0, headBlock.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[0])
+		require.NoError(t, err)
+		headBlock.Signature = sig1
+
+		// Create second block with same slot/proposer but different contents
+		newBlock := util.NewBeaconBlock()
+		newBlock.Block.Slot = 1
+		newBlock.Block.ProposerIndex = 0
+		newBlock.Block.ParentRoot = bytesutil.PadTo([]byte("parent2"), 32)
+		sig2, err := signing.ComputeDomainAndSign(beaconState, 0, newBlock.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[0])
+		require.NoError(t, err)
+		newBlock.Signature = sig2
+
+		signedHeadBlock, err := blocks.NewSignedBeaconBlock(headBlock)
+		require.NoError(t, err)
+
+		slashingPool := &slashingsmock.PoolMock{}
+		chainService := &mock.ChainService{
+			State:   beaconState,
+			Genesis: time.Now(),
+			Block:   signedHeadBlock,
+		}
+
+		r := &Service{
+			cfg: &config{
+				p2p:          p,
+				chain:        chainService,
+				slashingPool: slashingPool,
+			},
+			seenBlockCache: lruwrpr.New(10),
+		}
+
+		signedNewBlock, err := blocks.NewSignedBeaconBlock(newBlock)
+		require.NoError(t, err)
+
+		err = r.detectAndBroadcastEquivocation(ctx, signedNewBlock)
+		require.NoError(t, err)
+
+		// Verify slashing was inserted
+		require.Equal(t, 1, len(slashingPool.PendingPropSlashings), "Expected a slashing to be inserted")
+		slashing := slashingPool.PendingPropSlashings[0]
+		assert.Equal(t, primitives.ValidatorIndex(0), slashing.Header_1.Header.ProposerIndex, "Wrong proposer index")
+		assert.Equal(t, primitives.Slot(1), slashing.Header_1.Header.Slot, "Wrong slot")
+	})
+
+	t.Run("same signature", func(t *testing.T) {
+		// Create block
+		block := util.NewBeaconBlock()
+		block.Block.Slot = 1
+		block.Block.ProposerIndex = 0
+		sig, err := signing.ComputeDomainAndSign(beaconState, 0, block.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[0])
+		require.NoError(t, err)
+		block.Signature = sig
+
+		signedBlock, err := blocks.NewSignedBeaconBlock(block)
+		require.NoError(t, err)
+
+		slashingPool := &slashingsmock.PoolMock{}
+		chainService := &mock.ChainService{
+			State:   beaconState,
+			Genesis: time.Now(),
+			Block:   signedBlock,
+		}
+
+		r := &Service{
+			cfg: &config{
+				p2p:          p,
+				chain:        chainService,
+				slashingPool: slashingPool,
+			},
+			seenBlockCache: lruwrpr.New(10),
+		}
+
+		err = r.detectAndBroadcastEquivocation(ctx, signedBlock)
+		require.NoError(t, err)
+		assert.Equal(t, 0, len(slashingPool.PendingPropSlashings), "Expected no slashings for same signature")
+	})
+
+	t.Run("head state error", func(t *testing.T) {
+		block := util.NewBeaconBlock()
+		block.Block.Slot = 1
+		block.Block.ProposerIndex = 0
+		block.Block.ParentRoot = bytesutil.PadTo([]byte("parent1"), 32)
+		sig1, err := signing.ComputeDomainAndSign(beaconState, 0, block.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[0])
+		require.NoError(t, err)
+		block.Signature = sig1
+
+		headBlock := util.NewBeaconBlock()
+		headBlock.Block.Slot = 1                                            // Same slot
+		headBlock.Block.ProposerIndex = 0                                   // Same proposer
+		headBlock.Block.ParentRoot = bytesutil.PadTo([]byte("parent2"), 32) // Different parent root
+		sig2, err := signing.ComputeDomainAndSign(beaconState, 0, headBlock.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[0])
+		require.NoError(t, err)
+		headBlock.Signature = sig2
+
+		signedBlock, err := blocks.NewSignedBeaconBlock(block)
+		require.NoError(t, err)
+
+		signedHeadBlock, err := blocks.NewSignedBeaconBlock(headBlock)
+		require.NoError(t, err)
+
+		chainService := &mock.ChainService{
+			State:        nil,
+			Block:        signedHeadBlock,
+			HeadStateErr: errors.New("could not get head state"),
+		}
+
+		r := &Service{
+			cfg: &config{
+				p2p:          p,
+				chain:        chainService,
+				slashingPool: &slashingsmock.PoolMock{},
+			},
+			seenBlockCache: lruwrpr.New(10),
+		}
+
+		err = r.detectAndBroadcastEquivocation(ctx, signedBlock)
+		require.ErrorContains(t, "could not get head state", err)
+	})
+	t.Run("signature verification failure", func(t *testing.T) {
+		// Create head block
+		headBlock := util.NewBeaconBlock()
+		headBlock.Block.Slot = 1
+		headBlock.Block.ProposerIndex = 0
+		sig1, err := signing.ComputeDomainAndSign(beaconState, 0, headBlock.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[0])
+		require.NoError(t, err)
+		headBlock.Signature = sig1
+
+		// Create test block with invalid signature
+		newBlock := util.NewBeaconBlock()
+		newBlock.Block.Slot = 1
+		newBlock.Block.ProposerIndex = 0
+		newBlock.Block.ParentRoot = bytesutil.PadTo([]byte("different"), 32)
+		// generate invalid signature
+		invalidSig := make([]byte, 96)
+		copy(invalidSig, []byte("invalid signature"))
+		newBlock.Signature = invalidSig
+
+		signedHeadBlock, err := blocks.NewSignedBeaconBlock(headBlock)
+		require.NoError(t, err)
+		signedNewBlock, err := blocks.NewSignedBeaconBlock(newBlock)
+		require.NoError(t, err)
+
+		slashingPool := &slashingsmock.PoolMock{}
+		chainService := &mock.ChainService{
+			State:   beaconState,
+			Genesis: time.Now(),
+			Block:   signedHeadBlock,
+		}
+
+		r := &Service{
+			cfg: &config{
+				p2p:          p,
+				chain:        chainService,
+				slashingPool: slashingPool,
+			},
+			seenBlockCache: lruwrpr.New(10),
+		}
+
+		err = r.detectAndBroadcastEquivocation(ctx, signedNewBlock)
+		require.ErrorIs(t, err, ErrSlashingSignatureFailure)
+	})
+}

beacon-chain/verification/error.go

@@ -16,6 +16,11 @@ func AsVerificationFailure(err error) error {
 	return errors.Join(ErrInvalid, err)
 }
 
+// IsBlobValidationFailure checks if the given error is a blob validation failure.
+func IsBlobValidationFailure(err error) bool {
+	return errors.Is(err, ErrBlobInvalid)
+}
+
 var (
 	// ErrBlobInvalid is joined with all other blob verification errors. This enables other packages to check for any sort of
 	// verification error at one point, like sync code checking for peer scoring purposes.

changelog/bastin_add-lc-p2p-broadcasters.md

@@ -0,0 +1,3 @@
+### Added
+
+- Add light client p2p broadcaster functions.

changelog/bastin_add-lc-types-to-spectest.md

@@ -1,3 +0,0 @@
-### Added
-
-- Add light client ssz types to the spec test

changelog/bastin_add-lcstore-to-beacon-node.md

@@ -1,3 +0,0 @@
-### Added
-
-- Add light client store object to the beacon node object.

changelog/bastin_add-parameters-to-lc-testutils.md

@@ -1,3 +0,0 @@
-### Ignored
-
-- add two parameters `increaseAttestedSlotBy` and `supermajority` to the lc test utils.

changelog/bastin_lightclient-updates-ssz.md

@@ -1,3 +0,0 @@
-### Added
-
-- Add SSZ support to light client updates by range API. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15082)