gloas: sample PTC per committee (#16293)

This PR updates `get_ptc` construction to sample ptc
committee-by-committee instead of concatenating all beacon committees
into a large slice. No functional changes to payload attestation
verification

beacon-chain/core/gloas/payload_attestation.go

@@ -114,17 +114,32 @@ func payloadCommittee(ctx context.Context, st state.ReadOnlyBeaconState, slot pr
 	}
 
 	committeesPerSlot := helpers.SlotCommitteeCount(activeCount)
-	out := make([]primitives.ValidatorIndex, 0, activeCount/uint64(params.BeaconConfig().SlotsPerEpoch))
 
-	for i := primitives.CommitteeIndex(0); i < primitives.CommitteeIndex(committeesPerSlot); i++ {
+	selected := make([]primitives.ValidatorIndex, 0, fieldparams.PTCSize)
-		committee, err := helpers.BeaconCommitteeFromState(ctx, st, slot, i)
+	var i uint64
-		if err != nil {
+	for uint64(len(selected)) < fieldparams.PTCSize {
-			return nil, errors.Wrapf(err, "failed to get beacon committee %d", i)
+		if ctx.Err() != nil {
+			return nil, ctx.Err()
+		}
+
+		for committeeIndex := primitives.CommitteeIndex(0); committeeIndex < primitives.CommitteeIndex(committeesPerSlot); committeeIndex++ {
+			if uint64(len(selected)) >= fieldparams.PTCSize {
+				break
+			}
+
+			committee, err := helpers.BeaconCommitteeFromState(ctx, st, slot, committeeIndex)
+			if err != nil {
+				return nil, errors.Wrapf(err, "failed to get beacon committee %d", committeeIndex)
+			}
+
+			selected, i, err = selectByBalanceFill(ctx, st, committee, seed, selected, i)
+			if err != nil {
+				return nil, errors.Wrapf(err, "failed to sample beacon committee %d", committeeIndex)
+			}
 		}
-		out = append(out, committee...)
 	}
 
-	return selectByBalance(ctx, st, out, seed, fieldparams.PTCSize)
+	return selected, nil
 }
 
 // ptcSeed computes the seed for the payload timeliness committee.
@@ -148,33 +163,39 @@ func ptcSeed(st state.ReadOnlyBeaconState, epoch primitives.Epoch, slot primitiv
 //	  if compute_balance_weighted_acceptance(state, indices[next], seed, i):
 //	    selected.append(indices[next])
 //	  i += 1
-func selectByBalance(ctx context.Context, st state.ReadOnlyBeaconState, candidates []primitives.ValidatorIndex, seed [32]byte, count uint64) ([]primitives.ValidatorIndex, error) {
+func selectByBalanceFill(
-	if len(candidates) == 0 {
+	ctx context.Context,
-		return nil, errors.New("no candidates for balance weighted selection")
+	st state.ReadOnlyBeaconState,
-	}
+	candidates []primitives.ValidatorIndex,
-
+	seed [32]byte,
+	selected []primitives.ValidatorIndex,
+	i uint64,
+) ([]primitives.ValidatorIndex, uint64, error) {
 	hashFunc := hash.CustomSHA256Hasher()
 	// Pre-allocate buffer for hash input: seed (32 bytes) + round counter (8 bytes).
 	var buf [40]byte
 	copy(buf[:], seed[:])
 	maxBalance := params.BeaconConfig().MaxEffectiveBalanceElectra
 
-	selected := make([]primitives.ValidatorIndex, 0, count)
+	for _, idx := range candidates {
-	total := uint64(len(candidates))
-	for i := uint64(0); uint64(len(selected)) < count; i++ {
 		if ctx.Err() != nil {
-			return nil, ctx.Err()
+			return nil, i, ctx.Err()
 		}
-		idx := candidates[i%total]
+
 		ok, err := acceptByBalance(st, idx, buf[:], hashFunc, maxBalance, i)
 		if err != nil {
-			return nil, err
+			return nil, i, err
 		}
 		if ok {
 			selected = append(selected, idx)
 		}
+		if uint64(len(selected)) == fieldparams.PTCSize {
+			break
+		}
+		i++
 	}
-	return selected, nil
+
+	return selected, i, nil
 }
 
 // acceptByBalance determines if a validator is accepted based on its effective balance.

beacon-chain/rpc/prysm/v1alpha1/node/BUILD.bazel

@@ -48,6 +48,7 @@ go_test(
         "@com_github_ethereum_go_ethereum//crypto:go_default_library",
         "@com_github_ethereum_go_ethereum//p2p/enode:go_default_library",
         "@org_golang_google_grpc//:go_default_library",
+        "@org_golang_google_grpc//metadata:go_default_library",
         "@org_golang_google_grpc//reflection:go_default_library",
         "@org_golang_google_protobuf//types/known/emptypb:go_default_library",
         "@org_golang_google_protobuf//types/known/timestamppb:go_default_library",

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

@@ -35,18 +35,19 @@ import (
 // providing RPC endpoints for verifying a beacon node's sync status, genesis and
 // version information, and services the node implements and runs.
 type Server struct {
-	LogsStreamer         logs.Streamer
+	LogsStreamer          logs.Streamer
-	StreamLogsBufferSize int
+	StreamLogsBufferSize  int
-	SyncChecker          sync.Checker
+	SyncChecker           sync.Checker
-	Server               *grpc.Server
+	Server                *grpc.Server
-	BeaconDB             db.ReadOnlyDatabase
+	BeaconDB              db.ReadOnlyDatabase
-	PeersFetcher         p2p.PeersProvider
+	PeersFetcher          p2p.PeersProvider
-	PeerManager          p2p.PeerManager
+	PeerManager           p2p.PeerManager
-	GenesisTimeFetcher   blockchain.TimeFetcher
+	GenesisTimeFetcher    blockchain.TimeFetcher
-	GenesisFetcher       blockchain.GenesisFetcher
+	GenesisFetcher        blockchain.GenesisFetcher
-	POWChainInfoFetcher  execution.ChainInfoFetcher
+	POWChainInfoFetcher   execution.ChainInfoFetcher
-	BeaconMonitoringHost string
+	BeaconMonitoringHost  string
-	BeaconMonitoringPort int
+	BeaconMonitoringPort  int
+	OptimisticModeFetcher blockchain.OptimisticModeFetcher
 }
 
 // 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.
@@ -61,21 +62,28 @@ func (ns *Server) GetHealth(ctx context.Context, request *ethpb.HealthRequest) (
 	ctx, cancel := context.WithTimeout(ctx, timeoutDuration)
 	defer cancel() // Important to avoid a context leak
 
-	if ns.SyncChecker.Synced() {
+	// Check optimistic status - validators should not participate when optimistic
+	isOptimistic, err := ns.OptimisticModeFetcher.IsOptimistic(ctx)
+	if err != nil {
+		return &empty.Empty{}, status.Errorf(codes.Internal, "Could not check optimistic status: %v", err)
+	}
+
+	if ns.SyncChecker.Synced() && !isOptimistic {
 		return &empty.Empty{}, nil
 	}
 	if ns.SyncChecker.Syncing() || ns.SyncChecker.Initialized() {
-		if request.SyncingStatus != 0 {
+		// Set header for REST API clients (via gRPC-gateway)
-			// override the 200 success with the provided request status
-			if err := grpc.SetHeader(ctx, metadata.Pairs("x-http-code", strconv.FormatUint(request.SyncingStatus, 10))); err != nil {
-				return &empty.Empty{}, status.Errorf(codes.Internal, "Could not set custom success code header: %v", err)
-			}
-			return &empty.Empty{}, nil
-		}
 		if err := grpc.SetHeader(ctx, metadata.Pairs("x-http-code", strconv.FormatUint(http.StatusPartialContent, 10))); err != nil {
-			return &empty.Empty{}, status.Errorf(codes.Internal, "Could not set custom success code header: %v", err)
+			return &empty.Empty{}, status.Errorf(codes.Internal, "Could not set status code header: %v", err)
 		}
-		return &empty.Empty{}, nil
+		return &empty.Empty{}, status.Error(codes.Unavailable, "node is syncing")
+	}
+	if isOptimistic {
+		// Set header for REST API clients (via gRPC-gateway)
+		if err := grpc.SetHeader(ctx, metadata.Pairs("x-http-code", strconv.FormatUint(http.StatusPartialContent, 10))); err != nil {
+			return &empty.Empty{}, status.Errorf(codes.Internal, "Could not set status code header: %v", err)
+		}
+		return &empty.Empty{}, status.Error(codes.Unavailable, "node is optimistic")
 	}
 	return &empty.Empty{}, status.Errorf(codes.Unavailable, "service unavailable")
 }

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

@@ -2,6 +2,7 @@ package node
 
 import (
 	"errors"
+	"maps"
 	"testing"
 	"time"
 
@@ -21,6 +22,7 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/reflection"
 	"google.golang.org/protobuf/types/known/emptypb"
 	"google.golang.org/protobuf/types/known/timestamppb"
@@ -187,32 +189,71 @@ func TestNodeServer_GetETH1ConnectionStatus(t *testing.T) {
 	assert.Equal(t, errStr, res.CurrentConnectionError)
 }
 
+// mockServerTransportStream implements grpc.ServerTransportStream for testing
+type mockServerTransportStream struct {
+	headers map[string][]string
+}
+
+func (m *mockServerTransportStream) Method() string { return "" }
+func (m *mockServerTransportStream) SetHeader(md metadata.MD) error {
+	maps.Copy(m.headers, md)
+	return nil
+}
+func (m *mockServerTransportStream) SendHeader(metadata.MD) error { return nil }
+func (m *mockServerTransportStream) SetTrailer(metadata.MD) error { return nil }
+
 func TestNodeServer_GetHealth(t *testing.T) {
 	tests := []struct {
 		name         string
 		input        *mockSync.Sync
-		customStatus uint64
+		isOptimistic bool
 		wantedErr    string
 	}{
 		{
-			name:  "happy path",
+			name:         "happy path - synced and not optimistic",
-			input: &mockSync.Sync{IsSyncing: false, IsSynced: true},
+			input:        &mockSync.Sync{IsSyncing: false, IsSynced: true},
+			isOptimistic: false,
 		},
 		{
-			name:      "syncing",
+			name:         "returns error when not synced and not syncing",
-			input:     &mockSync.Sync{IsSyncing: false},
+			input:        &mockSync.Sync{IsSyncing: false, IsSynced: false},
-			wantedErr: "service unavailable",
+			isOptimistic: false,
+			wantedErr:    "service unavailable",
+		},
+		{
+			name:         "returns error when syncing",
+			input:        &mockSync.Sync{IsSyncing: true, IsSynced: false},
+			isOptimistic: false,
+			wantedErr:    "node is syncing",
+		},
+		{
+			name:         "returns error when synced but optimistic",
+			input:        &mockSync.Sync{IsSyncing: false, IsSynced: true},
+			isOptimistic: true,
+			wantedErr:    "node is optimistic",
+		},
+		{
+			name:         "returns error when syncing and optimistic",
+			input:        &mockSync.Sync{IsSyncing: true, IsSynced: false},
+			isOptimistic: true,
+			wantedErr:    "node is syncing",
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			server := grpc.NewServer()
 			ns := &Server{
-				SyncChecker: tt.input,
+				SyncChecker:           tt.input,
+				OptimisticModeFetcher: &mock.ChainService{Optimistic: tt.isOptimistic},
 			}
 			ethpb.RegisterNodeServer(server, ns)
 			reflection.Register(server)
-			_, err := ns.GetHealth(t.Context(), &ethpb.HealthRequest{SyncingStatus: tt.customStatus})
+
+			// Create context with mock transport stream so grpc.SetHeader works
+			stream := &mockServerTransportStream{headers: make(map[string][]string)}
+			ctx := grpc.NewContextWithServerTransportStream(t.Context(), stream)
+
+			_, err := ns.GetHealth(ctx, &ethpb.HealthRequest{})
 			if tt.wantedErr == "" {
 				require.NoError(t, err)
 				return

beacon-chain/rpc/service.go

@@ -259,18 +259,19 @@ func NewService(ctx context.Context, cfg *Config) *Service {
 	}
 	s.validatorServer = validatorServer
 	nodeServer := &nodev1alpha1.Server{
-		LogsStreamer:         logs.NewStreamServer(),
+		LogsStreamer:          logs.NewStreamServer(),
-		StreamLogsBufferSize: 1000, // Enough to handle bursts of beacon node logs for gRPC streaming.
+		StreamLogsBufferSize:  1000, // Enough to handle bursts of beacon node logs for gRPC streaming.
-		BeaconDB:             s.cfg.BeaconDB,
+		BeaconDB:              s.cfg.BeaconDB,
-		Server:               s.grpcServer,
+		Server:                s.grpcServer,
-		SyncChecker:          s.cfg.SyncService,
+		SyncChecker:           s.cfg.SyncService,
-		GenesisTimeFetcher:   s.cfg.GenesisTimeFetcher,
+		GenesisTimeFetcher:    s.cfg.GenesisTimeFetcher,
-		PeersFetcher:         s.cfg.PeersFetcher,
+		PeersFetcher:          s.cfg.PeersFetcher,
-		PeerManager:          s.cfg.PeerManager,
+		PeerManager:           s.cfg.PeerManager,
-		GenesisFetcher:       s.cfg.GenesisFetcher,
+		GenesisFetcher:        s.cfg.GenesisFetcher,
-		POWChainInfoFetcher:  s.cfg.ExecutionChainInfoFetcher,
+		POWChainInfoFetcher:   s.cfg.ExecutionChainInfoFetcher,
-		BeaconMonitoringHost: s.cfg.BeaconMonitoringHost,
+		BeaconMonitoringHost:  s.cfg.BeaconMonitoringHost,
-		BeaconMonitoringPort: s.cfg.BeaconMonitoringPort,
+		BeaconMonitoringPort:  s.cfg.BeaconMonitoringPort,
+		OptimisticModeFetcher: s.cfg.OptimisticModeFetcher,
 	}
 	beaconChainServer := &beaconv1alpha1.Server{
 		Ctx:                         s.ctx,

changelog/farazdagi_fix-hashtree-darwin-amd64.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- Fix Bazel build failure on macOS x86_64 (darwin_amd64) (adds missing assembly stub to hashtree patch).

changelog/fernantho_connect-merkle-proofs-with-endpoint.md

@@ -0,0 +1,6 @@
+### Added
+
+- Added new proofCollector type to ssz-query
+
+### Ignored
+- Added testing covering the production of Merkle proof from Phase0 beacon state and benchmarked against real Hoodi beacon state (Fulu version)

changelog/james-prysm_update-health-endpoint.md

@@ -0,0 +1,3 @@
+### Changed
+
+- gRPC health endpoint will now return an error on syncing or optimistic status showing that it's unavailable.

changelog/terencechain_gloas-ptc-sampling.md

@@ -0,0 +1,2 @@
+### Changed
+- Sample PTC per committee to reduce allocations.

encoding/bytesutil/integers.go

@@ -163,3 +163,18 @@ func Uint256ToSSZBytes(num string) ([]byte, error) {
 	}
 	return PadTo(ReverseByteOrder(uint256.Bytes()), 32), nil
 }
+
+// PutLittleEndian writes an unsigned integer value in little-endian format.
+// Supports sizes 1, 2, 4, or 8 bytes for uint8/16/32/64 respectively.
+func PutLittleEndian(dst []byte, val uint64, size int) {
+	switch size {
+	case 1:
+		dst[0] = byte(val)
+	case 2:
+		binary.LittleEndian.PutUint16(dst, uint16(val))
+	case 4:
+		binary.LittleEndian.PutUint32(dst, uint32(val))
+	case 8:
+		binary.LittleEndian.PutUint64(dst, val)
+	}
+}

encoding/ssz/query/BUILD.bazel

@@ -9,7 +9,9 @@ go_library(
         "container.go",
         "generalized_index.go",
         "list.go",
+        "merkle_proof.go",
         "path.go",
+        "proof_collector.go",
         "query.go",
         "ssz_info.go",
         "ssz_object.go",
@@ -20,7 +22,12 @@ go_library(
     importpath = "github.com/OffchainLabs/prysm/v7/encoding/ssz/query",
     visibility = ["//visibility:public"],
     deps = [
+        "//container/trie:go_default_library",
+        "//crypto/hash/htr:go_default_library",
+        "//encoding/bytesutil:go_default_library",
         "//encoding/ssz:go_default_library",
+        "//math:go_default_library",
+        "@com_github_prysmaticlabs_fastssz//:go_default_library",
         "@com_github_prysmaticlabs_go_bitfield//:go_default_library",
     ],
 )
@@ -29,15 +36,24 @@ go_test(
     name = "go_default_test",
     srcs = [
         "generalized_index_test.go",
+        "merkle_proof_test.go",
         "path_test.go",
+        "proof_collector_test.go",
         "query_test.go",
         "tag_parser_test.go",
     ],
+    embed = [":go_default_library"],
     deps = [
-        ":go_default_library",
+        "//beacon-chain/state/stateutil:go_default_library",
+        "//consensus-types/blocks:go_default_library",
+        "//consensus-types/primitives:go_default_library",
+        "//encoding/ssz:go_default_library",
         "//encoding/ssz/query/testutil:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
         "//proto/ssz_query/testing:go_default_library",
         "//testing/require:go_default_library",
+        "//testing/util:go_default_library",
+        "@com_github_prysmaticlabs_fastssz//:go_default_library",
         "@com_github_prysmaticlabs_go_bitfield//:go_default_library",
     ],
 )

encoding/ssz/query/merkle_proof.go

@@ -0,0 +1,34 @@
+package query
+
+import (
+	"fmt"
+	"reflect"
+
+	fastssz "github.com/prysmaticlabs/fastssz"
+)
+
+// Prove is the entrypoint to generate an SSZ Merkle proof for the given generalized index.
+// Parameters:
+// - gindex: the generalized index of the node to prove inclusion for.
+// Returns:
+// - fastssz.Proof: the Merkle proof containing the leaf, index, and sibling hashes.
+// - error: any error encountered during proof generation.
+func (info *SszInfo) Prove(gindex uint64) (*fastssz.Proof, error) {
+	if info == nil {
+		return nil, fmt.Errorf("nil SszInfo")
+	}
+
+	collector := newProofCollector()
+	collector.addTarget(gindex)
+
+	// info.source is guaranteed to be valid and dereferenced by AnalyzeObject
+	v := reflect.ValueOf(info.source).Elem()
+
+	// Start the merkleization and proof collection process.
+	// In SSZ generalized indices, the root is always at index 1.
+	if _, err := collector.merkleize(info, v, 1); err != nil {
+		return nil, err
+	}
+
+	return collector.toProof()
+}

encoding/ssz/query/merkle_proof_test.go

@@ -0,0 +1,163 @@
+package query_test
+
+import (
+	"testing"
+
+	"github.com/OffchainLabs/go-bitfield"
+	"github.com/OffchainLabs/prysm/v7/consensus-types/blocks"
+	"github.com/OffchainLabs/prysm/v7/consensus-types/primitives"
+	"github.com/OffchainLabs/prysm/v7/encoding/ssz/query"
+	eth "github.com/OffchainLabs/prysm/v7/proto/prysm/v1alpha1"
+	"github.com/OffchainLabs/prysm/v7/testing/require"
+	"github.com/OffchainLabs/prysm/v7/testing/util"
+	ssz "github.com/prysmaticlabs/fastssz"
+)
+
+func TestProve_FixedTestContainer(t *testing.T) {
+	obj := createFixedTestContainer()
+
+	tests := []string{
+		".field_uint32",
+		".nested.value2",
+		".vector_field[3]",
+		".bitvector64_field",
+		".trailing_field",
+	}
+
+	for _, tc := range tests {
+		t.Run(tc, func(t *testing.T) {
+			proveAndVerify(t, obj, tc)
+		})
+	}
+}
+
+func TestProve_VariableTestContainer(t *testing.T) {
+	obj := createVariableTestContainer()
+
+	tests := []string{
+		".leading_field",
+		".field_list_uint64[2]",
+		"len(field_list_uint64)",
+		".nested.nested_list_field[1]",
+		".variable_container_list[0].inner_1.field_list_uint64[1]",
+	}
+
+	for _, tc := range tests {
+		t.Run(tc, func(t *testing.T) {
+			proveAndVerify(t, obj, tc)
+		})
+	}
+}
+
+func TestProve_BeaconBlock(t *testing.T) {
+	randaoReveal := make([]byte, 96)
+	for i := range randaoReveal {
+		randaoReveal[i] = 0x42
+	}
+	root32 := make([]byte, 32)
+	for i := range root32 {
+		root32[i] = 0x24
+	}
+	sig := make([]byte, 96)
+	for i := range sig {
+		sig[i] = 0x99
+	}
+
+	att := &eth.Attestation{
+		AggregationBits: bitfield.Bitlist{0x01},
+		Data: &eth.AttestationData{
+			Slot:            1,
+			CommitteeIndex:  1,
+			BeaconBlockRoot: root32,
+			Source: &eth.Checkpoint{
+				Epoch: 1,
+				Root:  root32,
+			},
+			Target: &eth.Checkpoint{
+				Epoch: 1,
+				Root:  root32,
+			},
+		},
+		Signature: sig,
+	}
+
+	b := util.NewBeaconBlock()
+	b.Block.Slot = 123
+	b.Block.Body.RandaoReveal = randaoReveal
+	b.Block.Body.Attestations = []*eth.Attestation{att}
+
+	sb, err := blocks.NewSignedBeaconBlock(b)
+	require.NoError(t, err)
+
+	protoBlock, err := sb.Block().Proto()
+	require.NoError(t, err)
+
+	obj, ok := protoBlock.(query.SSZObject)
+	require.Equal(t, true, ok, "block proto does not implement query.SSZObject")
+
+	tests := []string{
+		".slot",
+		".body.randao_reveal",
+		".body.attestations[0].data.slot",
+		"len(body.attestations)",
+	}
+
+	for _, tc := range tests {
+		t.Run(tc, func(t *testing.T) {
+			proveAndVerify(t, obj, tc)
+		})
+	}
+}
+
+func TestProve_BeaconState(t *testing.T) {
+	st, _ := util.DeterministicGenesisState(t, 16)
+	require.NoError(t, st.SetSlot(primitives.Slot(42)))
+
+	sszObj, ok := st.ToProtoUnsafe().(query.SSZObject)
+	require.Equal(t, true, ok, "state proto does not implement query.SSZObject")
+
+	tests := []string{
+		".slot",
+		".latest_block_header",
+		".validators[0].effective_balance",
+		"len(validators)",
+	}
+
+	for _, tc := range tests {
+		t.Run(tc, func(t *testing.T) {
+			proveAndVerify(t, sszObj, tc)
+		})
+	}
+}
+
+// proveAndVerify helper to analyze an object, generate a merkle proof for the given path,
+// and verify the proof against the object's root.
+func proveAndVerify(t *testing.T, obj query.SSZObject, pathStr string) {
+	t.Helper()
+
+	info, err := query.AnalyzeObject(obj)
+	require.NoError(t, err)
+
+	path, err := query.ParsePath(pathStr)
+	require.NoError(t, err)
+
+	gi, err := query.GetGeneralizedIndexFromPath(info, path)
+	require.NoError(t, err)
+
+	proof, err := info.Prove(gi)
+	require.NoError(t, err)
+	require.Equal(t, int(gi), proof.Index)
+
+	root, err := obj.HashTreeRoot()
+	require.NoError(t, err)
+
+	ok, err := ssz.VerifyProof(root[:], proof)
+	require.NoError(t, err)
+	require.Equal(t, true, ok, "merkle proof verification failed")
+
+	require.Equal(t, 32, len(proof.Leaf))
+	for i, h := range proof.Hashes {
+		require.Equal(t, 32, len(h), "proof hash %d is not 32 bytes", i)
+	}
+
+}

encoding/ssz/query/proof_collector.go

@@ -0,0 +1,672 @@
+package query
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"math/bits"
+	"reflect"
+	"runtime"
+	"slices"
+	"sync"
+
+	"github.com/OffchainLabs/go-bitfield"
+	"github.com/OffchainLabs/prysm/v7/container/trie"
+	"github.com/OffchainLabs/prysm/v7/crypto/hash/htr"
+	"github.com/OffchainLabs/prysm/v7/encoding/bytesutil"
+	ssz "github.com/OffchainLabs/prysm/v7/encoding/ssz"
+	"github.com/OffchainLabs/prysm/v7/math"
+	fastssz "github.com/prysmaticlabs/fastssz"
+)
+
+// proofCollector collects sibling hashes and leaves needed for Merkle proofs.
+//
+// Multiproof-ready design:
+// - requiredSiblings/requiredLeaves store which gindices we want to collect (registered before merkleization).
+// - siblings/leaves store the actual collected hashes.
+//
+// Concurrency:
+// - required* maps are read-only during merkleization.
+// - siblings/leaves writes are protected by mutex.
+type proofCollector struct {
+	sync.Mutex
+
+	// Required gindices (registered before merkleization)
+	requiredSiblings map[uint64]struct{}
+	requiredLeaves   map[uint64]struct{}
+
+	// Collected hashes
+	siblings map[uint64][32]byte
+	leaves   map[uint64][32]byte
+}
+
+func newProofCollector() *proofCollector {
+	return &proofCollector{
+		requiredSiblings: make(map[uint64]struct{}),
+		requiredLeaves:   make(map[uint64]struct{}),
+		siblings:         make(map[uint64][32]byte),
+		leaves:           make(map[uint64][32]byte),
+	}
+}
+
+func (pc *proofCollector) reset() {
+	pc.Lock()
+	defer pc.Unlock()
+
+	pc.requiredSiblings = make(map[uint64]struct{})
+	pc.requiredLeaves = make(map[uint64]struct{})
+	pc.siblings = make(map[uint64][32]byte)
+	pc.leaves = make(map[uint64][32]byte)
+}
+
+// addTarget register the target leaf and its required sibling nodes for proof construction.
+// Registration should happen before merkleization begins.
+func (pc *proofCollector) addTarget(gindex uint64) {
+	pc.Lock()
+	defer pc.Unlock()
+
+	pc.requiredLeaves[gindex] = struct{}{}
+
+	// Walk from the target leaf up to (but not including) the root (gindex=1).
+	// At each step, register the sibling node required to prove inclusion.
+	nodeGindex := gindex
+	for nodeGindex > 1 {
+		siblingGindex := nodeGindex ^ 1 // flip the last bit: left<->right sibling
+		pc.requiredSiblings[siblingGindex] = struct{}{}
+
+		// Move to parent
+		nodeGindex /= 2
+	}
+}
+
+// toProof converts the collected siblings and leaves into a fastssz.Proof structure.
+// Current behavior expects a single target leaf (single proof).
+func (pc *proofCollector) toProof() (*fastssz.Proof, error) {
+	pc.Lock()
+	defer pc.Unlock()
+
+	proof := &fastssz.Proof{}
+	if len(pc.leaves) == 0 {
+		return nil, errors.New("no leaves collected: add target leaves before merkleization")
+	}
+
+	leafGindices := make([]uint64, 0, len(pc.leaves))
+	for g := range pc.leaves {
+		leafGindices = append(leafGindices, g)
+	}
+	slices.Sort(leafGindices)
+
+	// single proof resides in leafGindices[0]
+	targetGindex := leafGindices[0]
+	proofIndex, err := math.Int(targetGindex)
+	if err != nil {
+		return nil, fmt.Errorf("gindex %d overflows int: %w", targetGindex, err)
+	}
+	proof.Index = proofIndex
+
+	// store the leaf
+	leaf := pc.leaves[targetGindex]
+	leafBuf := make([]byte, 32)
+	copy(leafBuf, leaf[:])
+	proof.Leaf = leafBuf
+
+	// Walk from target up to root, collecting siblings.
+	steps := bits.Len64(targetGindex) - 1
+	proof.Hashes = make([][]byte, 0, steps)
+
+	for targetGindex > 1 {
+		sib := targetGindex ^ 1
+		h, ok := pc.siblings[sib]
+		if !ok {
+			return nil, fmt.Errorf("missing sibling hash for gindex %d", sib)
+		}
+		proof.Hashes = append(proof.Hashes, h[:])
+		targetGindex /= 2
+	}
+
+	return proof, nil
+}
+
+// collectLeaf checks if the given gindex is a required leaf for the proof,
+// and if so, stores the provided leaf hash in the collector.
+func (pc *proofCollector) collectLeaf(gindex uint64, leaf [32]byte) {
+	if _, ok := pc.requiredLeaves[gindex]; !ok {
+		return
+	}
+	pc.Lock()
+	pc.leaves[gindex] = leaf
+	pc.Unlock()
+}
+
+// collectSibling stores the hash for a sibling node identified by gindex.
+// It only stores the hash if gindex was pre-registered via addTarget (present in requiredSiblings).
+// Writes to the collected siblings map are protected by the collector mutex.
+func (pc *proofCollector) collectSibling(gindex uint64, hash [32]byte) {
+	if _, ok := pc.requiredSiblings[gindex]; !ok {
+		return
+	}
+	pc.Lock()
+	pc.siblings[gindex] = hash
+	pc.Unlock()
+}
+
+// Merkleizers and proof collection methods
+
+// merkleize recursively traverses an SSZ info and computes the Merkle root of the subtree.
+//
+// Proof collection:
+//   - During traversal it calls collectLeaf/collectSibling with the SSZ generalized indices (gindices)
+//     of visited nodes.
+//   - The collector only stores hashes for gindices that were pre-registered via addTarget
+//     (requiredLeaves/requiredSiblings). This makes the traversal multiproof-ready: you can register
+//     multiple targets before calling merkleize.
+//
+// SSZ types handled: basic types, containers, lists, vectors, bitlists, and bitvectors.
+//
+// Parameters:
+// - info: SSZ type metadata for the current value.
+// - v: reflect.Value of the current value.
+// - currentGindex: generalized index of the current subtree root.
+//
+// Returns:
+// - [32]byte: Merkle root of the current subtree.
+// - error: any error encountered during traversal/merkleization.
+func (pc *proofCollector) merkleize(info *SszInfo, v reflect.Value, currentGindex uint64) ([32]byte, error) {
+	if info.sszType.isBasic() {
+		return pc.merkleizeBasicType(info.sszType, v, currentGindex)
+	}
+	switch info.sszType {
+	case Container:
+		return pc.merkleizeContainer(info, v, currentGindex)
+	case List:
+		return pc.merkleizeList(info, v, currentGindex)
+	case Vector:
+		return pc.merkleizeVector(info, v, currentGindex)
+	case Bitlist:
+		return pc.merkleizeBitlist(info, v, currentGindex)
+	case Bitvector:
+		return pc.merkleizeBitvector(info, v, currentGindex)
+	default:
+		return [32]byte{}, fmt.Errorf("unsupported SSZ type: %v", info.sszType)
+	}
+}
+
+// merkleizeBasicType serializes a basic SSZ value into a 32-byte leaf chunk (little-endian, zero-padded).
+//
+// Proof collection:
+// - It calls collectLeaf(currentGindex, leaf) and stores the leaf if currentGindex was pre-registered via addTarget.
+//
+// Parameters:
+// - t: the SSZType (basic).
+// - v: the reflect.Value of the basic value.
+// - currentGindex: the generalized index (gindex) of this leaf.
+//
+// Returns:
+// - [32]byte: the 32-byte SSZ leaf chunk.
+// - error: if the SSZType is not a supported basic type.
+func (pc *proofCollector) merkleizeBasicType(t SSZType, v reflect.Value, currentGindex uint64) ([32]byte, error) {
+	var leaf [32]byte
+
+	// Serialize the value into a 32-byte chunk (little-endian, zero-padded)
+	switch t {
+	case Uint8:
+		leaf[0] = uint8(v.Uint())
+	case Uint16:
+		binary.LittleEndian.PutUint16(leaf[:2], uint16(v.Uint()))
+	case Uint32:
+		binary.LittleEndian.PutUint32(leaf[:4], uint32(v.Uint()))
+	case Uint64:
+		binary.LittleEndian.PutUint64(leaf[:8], v.Uint())
+	case Boolean:
+		if v.Bool() {
+			leaf[0] = 1
+		}
+	default:
+		return [32]byte{}, fmt.Errorf("unexpected basic type: %v", t)
+	}
+
+	pc.collectLeaf(currentGindex, leaf)
+
+	return leaf, nil
+}
+
+// merkleizeContainer computes the Merkle root of an SSZ container by:
+//  1. Merkleizing each field into a 32-byte subtree root
+//  2. Merkleizing the field roots into the container root (padding to the next power-of-2)
+//
+// Generalized indices (gindices): depth = ssz.Depth(uint64(N)) and field i has gindex = (currentGindex << depth) + uint64(i).
+// Proof collection: merkleize() computes each field root, merkleizeVectorAndCollect collects required siblings, and collectLeaf stores the container root if registered.
+//
+// Parameters:
+// - info: SSZ type metadata for the container.
+// - v: reflect.Value of the container value.
+// - currentGindex: generalized index (gindex) of the container root.
+//
+// Returns:
+// - [32]byte: Merkle root of the container.
+// - error: any error encountered while merkleizing fields.
+func (pc *proofCollector) merkleizeContainer(info *SszInfo, v reflect.Value, currentGindex uint64) ([32]byte, error) {
+	// If the container root itself is the target, compute directly and return early.
+	// This avoids full subtree merkleization when we only need the root.
+	if _, ok := pc.requiredLeaves[currentGindex]; ok {
+		root, err := info.HashTreeRoot()
+		if err != nil {
+			return [32]byte{}, err
+		}
+		pc.collectLeaf(currentGindex, root)
+		return root, nil
+	}
+
+	ci, err := info.ContainerInfo()
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	v = dereferencePointer(v)
+
+	// Calculate depth: how many levels from container root to field leaves
+	numFields := len(ci.order)
+	depth := ssz.Depth(uint64(numFields))
+
+	// Step 1: Compute HTR for each subtree (field)
+	fieldRoots := make([][32]byte, numFields)
+
+	for i, name := range ci.order {
+		fieldInfo := ci.fields[name]
+		fieldVal := v.FieldByName(fieldInfo.goFieldName)
+
+		// Field i's gindex: shift currentGindex left by depth, then OR with field index
+		fieldGindex := currentGindex<<depth + uint64(i)
+
+		htr, err := pc.merkleize(fieldInfo.sszInfo, fieldVal, fieldGindex)
+		if err != nil {
+			return [32]byte{}, fmt.Errorf("field %s: %w", name, err)
+		}
+		fieldRoots[i] = htr
+	}
+
+	// Step 2: Merkleize the field hashes into the container root,
+	// collecting sibling hashes if target is within this subtree
+	root := pc.merkleizeVectorAndCollect(fieldRoots, currentGindex, uint64(depth))
+
+	return root, nil
+}
+
+// merkleizeVectorBody computes the Merkle root of the "data" subtree for vector-like SSZ types
+// (vectors and the data-part of lists/bitlists).
+//
+// Generalized indices (gindices): depth = ssz.Depth(limit); leafBase = subtreeRootGindex << depth; element/chunk i gindex = leafBase + uint64(i).
+// Proof collection: merkleize() is called for composite elements; merkleizeVectorAndCollect collects required siblings at this layer.
+// Padding: merkleizeVectorAndCollect uses trie.ZeroHashes as needed.
+//
+// Parameters:
+// - elemInfo: SSZ type metadata for the element.
+// - v: reflect.Value of the vector/list data.
+// - length: number of actual elements present.
+// - limit: virtual leaf capacity used for padding/Depth (fixed length for vectors, limit for lists).
+// - subtreeRootGindex: gindex of the data subtree root.
+//
+// Returns:
+// - [32]byte: Merkle root of the data subtree.
+// - error: any error encountered while merkleizing composite elements.
+func (pc *proofCollector) merkleizeVectorBody(elemInfo *SszInfo, v reflect.Value, length int, limit uint64, subtreeRootGindex uint64) ([32]byte, error) {
+	depth := uint64(ssz.Depth(limit))
+
+	var chunks [][32]byte
+	if elemInfo.sszType.isBasic() {
+		// Serialize basic elements and pack into 32-byte chunks using ssz.PackByChunk.
+		elemSize, err := math.Int(itemLength(elemInfo))
+		if err != nil {
+			return [32]byte{}, fmt.Errorf("element size %d overflows int: %w", itemLength(elemInfo), err)
+		}
+		serialized := make([][]byte, length)
+		// Single contiguous allocation for all element data
+		allData := make([]byte, length*elemSize)
+		for i := range length {
+			buf := allData[i*elemSize : (i+1)*elemSize]
+			elem := v.Index(i)
+			if elemInfo.sszType == Boolean && elem.Bool() {
+				buf[0] = 1
+			} else {
+				bytesutil.PutLittleEndian(buf, elem.Uint(), elemSize)
+			}
+			serialized[i] = buf
+		}
+		chunks, err = ssz.PackByChunk(serialized)
+		if err != nil {
+			return [32]byte{}, err
+		}
+	} else {
+		// Composite elements: compute each element root (no padding here; merkleizeVectorAndCollect pads).
+		chunks = make([][32]byte, length)
+
+		// Fall back to per-element merkleization with proper gindices for proof collection.
+		// Parallel execution
+		workerCount := min(runtime.GOMAXPROCS(0), length)
+
+		jobs := make(chan int, workerCount*16)
+		errCh := make(chan error, 1) // only need the first error
+		stopCh := make(chan struct{})
+		var stopOnce sync.Once
+		var wg sync.WaitGroup
+
+		worker := func() {
+			defer wg.Done()
+			for idx := range jobs {
+				select {
+				case <-stopCh:
+					return
+				default:
+				}
+
+				elemGindex := subtreeRootGindex<<depth + uint64(idx)
+				htr, err := pc.merkleize(elemInfo, v.Index(idx), elemGindex)
+				if err != nil {
+					stopOnce.Do(func() { close(stopCh) })
+					select {
+					case errCh <- fmt.Errorf("index %d: %w", idx, err):
+					default:
+					}
+					return
+				}
+				chunks[idx] = htr
+			}
+		}
+
+		wg.Add(workerCount)
+		for range workerCount {
+			go worker()
+		}
+
+		// Enqueue jobs; stop early if any worker reports an error.
+	enqueue:
+		for i := range length {
+			select {
+			case <-stopCh:
+				break enqueue
+			case jobs <- i:
+			}
+		}
+		close(jobs)
+
+		wg.Wait()
+
+		select {
+		case err := <-errCh:
+			return [32]byte{}, err
+		default:
+		}
+	}
+
+	root := pc.merkleizeVectorAndCollect(chunks, subtreeRootGindex, depth)
+	return root, nil
+}
+
+// merkleizeVector computes the Merkle root of an SSZ vector (fixed-length).
+//
+// Generalized indices (gindices): currentGindex is the gindex of the vector root; element/chunk gindices are derived
+// inside merkleizeVectorBody using leafBase = currentGindex << ssz.Depth(leaves).
+//
+// Proof collection: merkleizeVectorBody performs element/chunk merkleization and collects required siblings at the
+// vector layer; collectLeaf stores the vector root if currentGindex was registered via addTarget.
+//
+// Parameters:
+// - info: SSZ type metadata for the vector.
+// - v: reflect.Value of the vector value.
+// - currentGindex: generalized index (gindex) of the vector root.
+//
+// Returns:
+// - [32]byte: Merkle root of the vector.
+// - error: any error encountered while merkleizing composite elements.
+func (pc *proofCollector) merkleizeVector(info *SszInfo, v reflect.Value, currentGindex uint64) ([32]byte, error) {
+	vi, err := info.VectorInfo()
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	length, err := math.Int(vi.Length())
+	if err != nil {
+		return [32]byte{}, fmt.Errorf("vector length %d overflows int: %w", vi.Length(), err)
+	}
+	elemInfo := vi.element
+
+	// Determine the virtual leaf capacity for the vector.
+	leaves, err := getChunkCount(info)
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	root, err := pc.merkleizeVectorBody(elemInfo, v, length, leaves, currentGindex)
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	// If the vector root itself is the target
+	pc.collectLeaf(currentGindex, root)
+
+	return root, nil
+}
+
+// merkleizeList computes the Merkle root of an SSZ list by merkleizing its data subtree and mixing in the length.
+//
+// Generalized indices (gindices): dataRoot is the left child of the list root (dataRootGindex = currentGindex*2); the length mixin is the right child (currentGindex*2+1).
+// Proof collection: merkleizeVectorBody computes the data root (collecting required siblings in the data subtree), and mixinLengthAndCollect collects required siblings at the length-mixin level; collectLeaf stores the list root if registered.
+//
+// Parameters:
+// - info: SSZ type metadata for the list.
+// - v: reflect.Value of the list value.
+// - currentGindex: generalized index (gindex) of the list root.
+//
+// Returns:
+// - [32]byte: Merkle root of the list.
+// - error: any error encountered while merkleizing the data subtree.
+func (pc *proofCollector) merkleizeList(info *SszInfo, v reflect.Value, currentGindex uint64) ([32]byte, error) {
+	li, err := info.ListInfo()
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	length := v.Len()
+	elemInfo := li.element
+
+	chunks := make([][32]byte, 2)
+	// Compute the length hash (little-endian uint256)
+	binary.LittleEndian.PutUint64(chunks[1][:8], uint64(length))
+
+	// Data subtree root is the left child of the list root.
+	dataRootGindex := currentGindex * 2
+
+	// Compute virtual leaf capacity for the data subtree.
+	leaves, err := getChunkCount(info)
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	chunks[0], err = pc.merkleizeVectorBody(elemInfo, v, length, leaves, dataRootGindex)
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	// Handle the length mixin level (and proof bookkeeping at this level).
+	// Compute the final list root: hash(dataRoot || lengthHash)
+	root := pc.mixinLengthAndCollect(currentGindex, chunks)
+
+	// If the list root itself is the target
+	pc.collectLeaf(currentGindex, root)
+
+	return root, nil
+}
+
+// merkleizeBitvectorBody computes the Merkle root of a bitvector-like byte sequence by packing it into 32-byte chunks
+// and merkleizing those chunks as a fixed-capacity vector (padding with trie.ZeroHashes as needed).
+//
+// Generalized indices (gindices): depth = ssz.Depth(chunkLimit); leafBase = subtreeRootGindex << depth; chunk i uses gindex = leafBase + uint64(i).
+// Proof collection: merkleizeVectorAndCollect collects required sibling hashes at the chunk-merkleization layer.
+//
+// Parameters:
+// - data: raw byte sequence representing the bitvector payload.
+// - chunkLimit: fixed/limit number of 32-byte chunks (used for padding/Depth).
+// - subtreeRootGindex: gindex of the bitvector data subtree root.
+//
+// Returns:
+// - [32]byte: Merkle root of the bitvector data subtree.
+// - error: any error encountered while packing data into chunks.
+func (pc *proofCollector) merkleizeBitvectorBody(data []byte, chunkLimit uint64, subtreeRootGindex uint64) ([32]byte, error) {
+	depth := ssz.Depth(chunkLimit)
+	chunks, err := ssz.PackByChunk([][]byte{data})
+	if err != nil {
+		return [32]byte{}, err
+	}
+	root := pc.merkleizeVectorAndCollect(chunks, subtreeRootGindex, uint64(depth))
+	return root, nil
+}
+
+// merkleizeBitvector computes the Merkle root of a fixed-length SSZ bitvector and collects proof nodes for targets.
+//
+// Parameters:
+// - info: SSZ type metadata for the bitvector.
+// - v: reflect.Value of the bitvector value.
+// - currentGindex: generalized index (gindex) of the bitvector root.
+//
+// Returns:
+// - [32]byte: Merkle root of the bitvector.
+// - error: any error encountered during packing or merkleization.
+func (pc *proofCollector) merkleizeBitvector(info *SszInfo, v reflect.Value, currentGindex uint64) ([32]byte, error) {
+	bitvectorBytes := v.Bytes()
+	if len(bitvectorBytes) == 0 {
+		return [32]byte{}, fmt.Errorf("bitvector field is uninitialized (nil or empty slice)")
+	}
+
+	// Compute virtual leaf capacity for the bitvector.
+	numChunks, err := getChunkCount(info)
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	root, err := pc.merkleizeBitvectorBody(bitvectorBytes, numChunks, currentGindex)
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	pc.collectLeaf(currentGindex, root)
+
+	return root, nil
+}
+
+// merkleizeBitlist computes the Merkle root of an SSZ bitlist by merkleizing its data chunks and mixing in the bit length.
+//
+// Generalized indices (gindices): dataRoot is the left child (dataRootGindex = currentGindex*2) and the length mixin is the right child (currentGindex*2+1).
+// Proof collection: merkleizeBitvectorBody computes the data root (collecting required siblings under dataRootGindex), and mixinLengthAndCollect collects required siblings at the length-mixin level; collectLeaf stores the bitlist root if registered.
+//
+// Parameters:
+// - info: SSZ type metadata for the bitlist.
+// - v: reflect.Value of the bitlist value.
+// - currentGindex: generalized index (gindex) of the bitlist root.
+//
+// Returns:
+// - [32]byte: Merkle root of the bitlist.
+// - error: any error encountered while merkleizing the data subtree.
+func (pc *proofCollector) merkleizeBitlist(info *SszInfo, v reflect.Value, currentGindex uint64) ([32]byte, error) {
+	bi, err := info.BitlistInfo()
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	bitlistBytes := v.Bytes()
+
+	// Use go-bitfield to get bytes with termination bit cleared
+	bl := bitfield.Bitlist(bitlistBytes)
+	data := bl.BytesNoTrim()
+
+	// Get the bit length from bitlistInfo
+	bitLength := bi.Length()
+
+	// Get the chunk limit from getChunkCount
+	limitChunks, err := getChunkCount(info)
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	chunks := make([][32]byte, 2)
+	// Compute the length hash (little-endian uint256)
+	binary.LittleEndian.PutUint64(chunks[1][:8], uint64(bitLength))
+
+	dataRootGindex := currentGindex * 2
+	chunks[0], err = pc.merkleizeBitvectorBody(data, limitChunks, dataRootGindex)
+	if err != nil {
+		return [32]byte{}, err
+	}
+
+	// Handle the length mixin level (and proof bookkeeping at this level).
+	root := pc.mixinLengthAndCollect(currentGindex, chunks)
+
+	pc.collectLeaf(currentGindex, root)
+
+	return root, nil
+}
+
+// merkleizeVectorAndCollect merkleizes a slice of 32-byte leaf nodes into a subtree root, padding to a virtual size of 2^depth.
+//
+// Generalized indices (gindices): at layer i (0-based), nodes have gindices levelBase = subtreeGeneralizedIndex << (depth-i) and node gindex = levelBase + idx.
+// Proof collection: for each layer it calls collectSibling(nodeGindex, nodeHash) and stores only those gindices registered via addTarget.
+//
+// Parameters:
+// - elements: leaf-level hashes (may be shorter than 2^depth; padding is applied with trie.ZeroHashes).
+// - subtreeGeneralizedIndex: gindex of the subtree root.
+// - depth: number of merkleization layers from subtree root to leaves.
+//
+// Returns:
+// - [32]byte: Merkle root of the subtree.
+func (pc *proofCollector) merkleizeVectorAndCollect(elements [][32]byte, subtreeGeneralizedIndex uint64, depth uint64) [32]byte {
+	// Return zerohash at depth
+	if len(elements) == 0 {
+		return trie.ZeroHashes[depth]
+	}
+	for i := range depth {
+		layerLen := len(elements)
+		oddNodeLength := layerLen%2 == 1
+		if oddNodeLength {
+			zerohash := trie.ZeroHashes[i]
+			elements = append(elements, zerohash)
+		}
+
+		levelBaseGindex := subtreeGeneralizedIndex << (depth - i)
+		for idx := range elements {
+			gindex := levelBaseGindex + uint64(idx)
+			pc.collectSibling(gindex, elements[idx])
+			pc.collectLeaf(gindex, elements[idx])
+		}
+
+		elements = htr.VectorizedSha256(elements)
+	}
+	return elements[0]
+}
+
+// mixinLengthAndCollect computes the final mix-in root for list/bitlist values:
+//
+//	root = hash(dataRoot, lengthHash)
+//
+// where chunks[0] is dataRoot and chunks[1] is the 32-byte length hash.
+//
+// Generalized indices (gindices): dataRoot is the left child (dataRootGindex = currentGindex*2) and lengthHash is the right child (lengthHashGindex = currentGindex*2+1).
+// Proof collection: it calls collectSibling/collectLeaf for both child gindices; the collector stores them only if they were registered via addTarget.
+//
+// Parameters:
+// - currentGindex: gindex of the parent node (list/bitlist root).
+// - chunks: two 32-byte nodes: [dataRoot, lengthHash].
+//
+// Returns:
+// - [32]byte: mixed-in Merkle root (or zero value on hashing error).
+// - error: any error encountered during hashing.
+func (pc *proofCollector) mixinLengthAndCollect(currentGindex uint64, chunks [][32]byte) [32]byte {
+	dataRoot, lengthHash := chunks[0], chunks[1]
+	dataRootGindex, lengthHashGindex := currentGindex*2, currentGindex*2+1
+
+	pc.collectSibling(dataRootGindex, dataRoot)
+	pc.collectSibling(lengthHashGindex, lengthHash)
+
+	pc.collectLeaf(dataRootGindex, dataRoot)
+	pc.collectLeaf(lengthHashGindex, lengthHash)
+
+	return ssz.MixInLength(dataRoot, lengthHash[:])
+}

encoding/ssz/query/proof_collector_test.go

@@ -0,0 +1,531 @@
+package query
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+	"reflect"
+	"slices"
+	"testing"
+
+	"github.com/OffchainLabs/go-bitfield"
+	"github.com/OffchainLabs/prysm/v7/beacon-chain/state/stateutil"
+	"github.com/OffchainLabs/prysm/v7/consensus-types/primitives"
+	ssz "github.com/OffchainLabs/prysm/v7/encoding/ssz"
+	ethpb "github.com/OffchainLabs/prysm/v7/proto/prysm/v1alpha1"
+	sszquerypb "github.com/OffchainLabs/prysm/v7/proto/ssz_query/testing"
+	"github.com/OffchainLabs/prysm/v7/testing/require"
+)
+
+func TestProofCollector_New(t *testing.T) {
+	pc := newProofCollector()
+
+	require.NotNil(t, pc)
+	require.Equal(t, 0, len(pc.requiredSiblings))
+	require.Equal(t, 0, len(pc.requiredLeaves))
+	require.Equal(t, 0, len(pc.siblings))
+	require.Equal(t, 0, len(pc.leaves))
+}
+
+func TestProofCollector_Reset(t *testing.T) {
+	pc := newProofCollector()
+	pc.requiredSiblings[3] = struct{}{}
+	pc.requiredLeaves[5] = struct{}{}
+	pc.siblings[3] = [32]byte{1}
+	pc.leaves[5] = [32]byte{2}
+
+	pc.reset()
+
+	require.Equal(t, 0, len(pc.requiredSiblings))
+	require.Equal(t, 0, len(pc.requiredLeaves))
+	require.Equal(t, 0, len(pc.siblings))
+	require.Equal(t, 0, len(pc.leaves))
+}
+
+func TestProofCollector_AddTarget(t *testing.T) {
+	pc := newProofCollector()
+	pc.addTarget(5)
+
+	_, hasLeaf := pc.requiredLeaves[5]
+	_, hasSibling4 := pc.requiredSiblings[4]
+	_, hasSibling3 := pc.requiredSiblings[3]
+	_, hasSibling1 := pc.requiredSiblings[1] // GI 1 is the root
+
+	require.Equal(t, true, hasLeaf)
+	require.Equal(t, true, hasSibling4)
+	require.Equal(t, true, hasSibling3)
+	require.Equal(t, false, hasSibling1)
+}
+
+func TestProofCollector_ToProof(t *testing.T) {
+	pc := newProofCollector()
+	pc.addTarget(5)
+
+	leaf := [32]byte{9}
+	sibling4 := [32]byte{4}
+	sibling3 := [32]byte{3}
+
+	pc.collectLeaf(5, leaf)
+	pc.collectSibling(4, sibling4)
+	pc.collectSibling(3, sibling3)
+
+	proof, err := pc.toProof()
+	require.NoError(t, err)
+
+	require.Equal(t, 5, proof.Index)
+	require.DeepEqual(t, leaf[:], proof.Leaf)
+	require.Equal(t, 2, len(proof.Hashes))
+	require.DeepEqual(t, sibling4[:], proof.Hashes[0])
+	require.DeepEqual(t, sibling3[:], proof.Hashes[1])
+}
+
+func TestProofCollector_ToProof_NoLeaves(t *testing.T) {
+	pc := newProofCollector()
+	_, err := pc.toProof()
+	require.NotNil(t, err)
+}
+
+func TestProofCollector_CollectLeaf(t *testing.T) {
+	pc := newProofCollector()
+	leaf := [32]byte{7}
+
+	pc.collectLeaf(10, leaf)
+	require.Equal(t, 0, len(pc.leaves))
+
+	pc.addTarget(10)
+	pc.collectLeaf(10, leaf)
+	stored, ok := pc.leaves[10]
+	require.Equal(t, true, ok)
+	require.Equal(t, leaf, stored)
+}
+
+func TestProofCollector_CollectSibling(t *testing.T) {
+	pc := newProofCollector()
+	hash := [32]byte{5}
+
+	pc.collectSibling(4, hash)
+	require.Equal(t, 0, len(pc.siblings))
+
+	pc.addTarget(5)
+	pc.collectSibling(4, hash)
+	stored, ok := pc.siblings[4]
+	require.Equal(t, true, ok)
+	require.Equal(t, hash, stored)
+}
+
+func TestProofCollector_Merkleize_BasicTypes(t *testing.T) {
+	testCases := []struct {
+		name     string
+		sszType  SSZType
+		value    any
+		expected [32]byte
+	}{
+		{
+			name:    "uint8",
+			sszType: Uint8,
+			value:   uint8(0x11),
+			expected: func() [32]byte {
+				var leaf [32]byte
+				leaf[0] = 0x11
+				return leaf
+			}(),
+		},
+		{
+			name:    "uint16",
+			sszType: Uint16,
+			value:   uint16(0x2211),
+			expected: func() [32]byte {
+				var leaf [32]byte
+				binary.LittleEndian.PutUint16(leaf[:2], 0x2211)
+				return leaf
+			}(),
+		},
+		{
+			name:    "uint32",
+			sszType: Uint32,
+			value:   uint32(0x44332211),
+			expected: func() [32]byte {
+				var leaf [32]byte
+				binary.LittleEndian.PutUint32(leaf[:4], 0x44332211)
+				return leaf
+			}(),
+		},
+		{
+			name:    "uint64",
+			sszType: Uint64,
+			value:   uint64(0x8877665544332211),
+			expected: func() [32]byte {
+				var leaf [32]byte
+				binary.LittleEndian.PutUint64(leaf[:8], 0x8877665544332211)
+				return leaf
+			}(),
+		},
+		{
+			name:    "bool",
+			sszType: Boolean,
+			value:   true,
+			expected: func() [32]byte {
+				var leaf [32]byte
+				leaf[0] = 1
+				return leaf
+			}(),
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			pc := newProofCollector()
+			gindex := uint64(3)
+			pc.addTarget(gindex)
+
+			leaf, err := pc.merkleizeBasicType(tc.sszType, reflect.ValueOf(tc.value), gindex)
+			require.NoError(t, err)
+			require.Equal(t, tc.expected, leaf)
+
+			stored, ok := pc.leaves[gindex]
+			require.Equal(t, true, ok)
+			require.Equal(t, tc.expected, stored)
+		})
+	}
+}
+
+func TestProofCollector_Merkleize_Container(t *testing.T) {
+	container := makeFixedTestContainer()
+
+	info, err := AnalyzeObject(container)
+	require.NoError(t, err)
+
+	pc := newProofCollector()
+	pc.addTarget(1)
+
+	root, err := pc.merkleize(info, reflect.ValueOf(container), 1)
+	require.NoError(t, err)
+
+	expected, err := container.HashTreeRoot()
+	require.NoError(t, err)
+	require.Equal(t, expected, root)
+
+	stored, ok := pc.leaves[1]
+	require.Equal(t, true, ok)
+	require.Equal(t, expected, stored)
+}
+
+func TestProofCollector_Merkleize_Vector(t *testing.T) {
+	container := makeFixedTestContainer()
+	info, err := AnalyzeObject(container)
+	require.NoError(t, err)
+
+	ci, err := info.ContainerInfo()
+	require.NoError(t, err)
+	field := ci.fields["vector_field"]
+
+	pc := newProofCollector()
+	root, err := pc.merkleizeVector(field.sszInfo, reflect.ValueOf(container.VectorField), 1)
+	require.NoError(t, err)
+
+	serialized := make([][]byte, len(container.VectorField))
+	for i, v := range container.VectorField {
+		buf := make([]byte, 8)
+		binary.LittleEndian.PutUint64(buf, v)
+		serialized[i] = buf
+	}
+	chunks, err := ssz.PackByChunk(serialized)
+	require.NoError(t, err)
+	limit, err := getChunkCount(field.sszInfo)
+	require.NoError(t, err)
+	expected := ssz.MerkleizeVector(chunks, limit)
+
+	require.Equal(t, expected, root)
+}
+
+func TestProofCollector_Merkleize_List(t *testing.T) {
+	list := []*sszquerypb.FixedNestedContainer{
+		makeFixedNestedContainer(1),
+		makeFixedNestedContainer(2),
+	}
+	container := makeVariableTestContainer(list, bitfield.NewBitlist(1))
+	info, err := AnalyzeObject(container)
+	require.NoError(t, err)
+
+	ci, err := info.ContainerInfo()
+	require.NoError(t, err)
+	field := ci.fields["field_list_container"]
+
+	pc := newProofCollector()
+	root, err := pc.merkleizeList(field.sszInfo, reflect.ValueOf(list), 1)
+	require.NoError(t, err)
+
+	listInfo, err := field.sszInfo.ListInfo()
+	require.NoError(t, err)
+	expected, err := ssz.MerkleizeListSSZ(list, listInfo.Limit())
+	require.NoError(t, err)
+
+	require.Equal(t, expected, root)
+}
+
+func TestProofCollector_Merkleize_Bitvector(t *testing.T) {
+	container := makeFixedTestContainer()
+	info, err := AnalyzeObject(container)
+	require.NoError(t, err)
+
+	ci, err := info.ContainerInfo()
+	require.NoError(t, err)
+	field := ci.fields["bitvector64_field"]
+
+	pc := newProofCollector()
+	root, err := pc.merkleizeBitvector(field.sszInfo, reflect.ValueOf(container.Bitvector64Field), 1)
+	require.NoError(t, err)
+
+	expected, err := ssz.MerkleizeByteSliceSSZ([]byte(container.Bitvector64Field))
+	require.NoError(t, err)
+	require.Equal(t, expected, root)
+}
+
+func TestProofCollector_Merkleize_Bitlist(t *testing.T) {
+	bitlist := bitfield.NewBitlist(16)
+	bitlist.SetBitAt(3, true)
+	bitlist.SetBitAt(8, true)
+
+	container := makeVariableTestContainer(nil, bitlist)
+	info, err := AnalyzeObject(container)
+	require.NoError(t, err)
+
+	ci, err := info.ContainerInfo()
+	require.NoError(t, err)
+	field := ci.fields["bitlist_field"]
+
+	pc := newProofCollector()
+	root, err := pc.merkleizeBitlist(field.sszInfo, reflect.ValueOf(container.BitlistField), 1)
+	require.NoError(t, err)
+
+	bitlistInfo, err := field.sszInfo.BitlistInfo()
+	require.NoError(t, err)
+	expected, err := ssz.BitlistRoot(bitfield.Bitlist(bitlist), bitlistInfo.Limit())
+	require.NoError(t, err)
+	require.Equal(t, expected, root)
+}
+
+func TestProofCollector_MerkleizeVectorBody_Basic(t *testing.T) {
+	container := makeFixedTestContainer()
+	info, err := AnalyzeObject(container)
+	require.NoError(t, err)
+
+	ci, err := info.ContainerInfo()
+	require.NoError(t, err)
+	field := ci.fields["vector_field"]
+	vectorInfo, err := field.sszInfo.VectorInfo()
+	require.NoError(t, err)
+	length := len(container.VectorField)
+	limit, err := getChunkCount(field.sszInfo)
+	require.NoError(t, err)
+
+	pc := newProofCollector()
+	root, err := pc.merkleizeVectorBody(vectorInfo.element, reflect.ValueOf(container.VectorField), length, limit, 2)
+	require.NoError(t, err)
+
+	serialized := make([][]byte, len(container.VectorField))
+	for i, v := range container.VectorField {
+		buf := make([]byte, 8)
+		binary.LittleEndian.PutUint64(buf, v)
+		serialized[i] = buf
+	}
+	chunks, err := ssz.PackByChunk(serialized)
+	require.NoError(t, err)
+	expected := ssz.MerkleizeVector(chunks, limit)
+
+	require.Equal(t, expected, root)
+}
+
+func TestProofCollector_MerkleizeVectorAndCollect(t *testing.T) {
+	pc := newProofCollector()
+	pc.addTarget(6)
+
+	elements := [][32]byte{{1}, {2}}
+	expected := ssz.MerkleizeVector(slices.Clone(elements), 2)
+	root := pc.merkleizeVectorAndCollect(elements, 3, 1)
+
+	storedLeaf, hasLeaf := pc.leaves[6]
+	storedSibling, hasSibling := pc.siblings[7]
+
+	require.Equal(t, true, hasLeaf)
+	require.Equal(t, true, hasSibling)
+	require.Equal(t, elements[0], storedLeaf)
+	require.Equal(t, elements[1], storedSibling)
+
+	require.Equal(t, expected, root)
+}
+
+func TestProofCollector_MixinLengthAndCollect(t *testing.T) {
+	list := []*sszquerypb.FixedNestedContainer{
+		makeFixedNestedContainer(1),
+		makeFixedNestedContainer(2),
+	}
+	container := makeVariableTestContainer(list, bitfield.NewBitlist(1))
+	info, err := AnalyzeObject(container)
+	require.NoError(t, err)
+
+	ci, err := info.ContainerInfo()
+	require.NoError(t, err)
+	field := ci.fields["field_list_container"]
+
+	// Target gindex 2 (data root) - sibling at gindex 3 (length hash) should be collected
+	pc := newProofCollector()
+	pc.addTarget(2)
+	root, err := pc.merkleizeList(field.sszInfo, reflect.ValueOf(list), 1)
+	require.NoError(t, err)
+
+	listInfo, err := field.sszInfo.ListInfo()
+	require.NoError(t, err)
+	expected, err := ssz.MerkleizeListSSZ(list, listInfo.Limit())
+	require.NoError(t, err)
+	require.Equal(t, expected, root)
+
+	// Verify data root is collected as leaf at gindex 2
+	storedLeaf, hasLeaf := pc.leaves[2]
+	require.Equal(t, true, hasLeaf)
+
+	// Verify length hash is collected as sibling at gindex 3
+	storedSibling, hasSibling := pc.siblings[3]
+	require.Equal(t, true, hasSibling)
+
+	// Verify the root is hash(dataRoot || lengthHash)
+	expectedBuf := append(storedLeaf[:], storedSibling[:]...)
+	expectedRoot := sha256.Sum256(expectedBuf)
+	require.Equal(t, expectedRoot, root)
+}
+
+func BenchmarkOptimizedValidatorRoots(b *testing.B) {
+	validators := make([]*ethpb.Validator, 1000)
+	for i := range validators {
+		validators[i] = makeTestValidator(i)
+	}
+
+	b.ResetTimer()
+	for b.Loop() {
+		_, err := stateutil.OptimizedValidatorRoots(validators)
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func BenchmarkProofCollectorMerkleize(b *testing.B) {
+	validators := make([]*ethpb.Validator, 1000)
+	for i := range validators {
+		validators[i] = makeTestValidator(i)
+	}
+
+	info, err := AnalyzeObject(validators[0])
+	require.NoError(b, err)
+
+	b.ResetTimer()
+	for b.Loop() {
+		for _, val := range validators {
+			pc := newProofCollector()
+			v := reflect.ValueOf(val)
+			_, err := pc.merkleize(info, v, 1)
+			if err != nil {
+				b.Fatal(err)
+			}
+		}
+	}
+}
+
+func makeTestValidator(i int) *ethpb.Validator {
+	pubkey := make([]byte, 48)
+	for j := range pubkey {
+		pubkey[j] = byte(i + j)
+	}
+
+	withdrawalCredentials := make([]byte, 32)
+	for j := range withdrawalCredentials {
+		withdrawalCredentials[j] = byte(255 - ((i + j) % 256))
+	}
+
+	return &ethpb.Validator{
+		PublicKey:                  pubkey,
+		WithdrawalCredentials:      withdrawalCredentials,
+		EffectiveBalance:           uint64(32000000000 + i),
+		Slashed:                    i%2 == 0,
+		ActivationEligibilityEpoch: primitives.Epoch(i),
+		ActivationEpoch:            primitives.Epoch(i + 1),
+		ExitEpoch:                  primitives.Epoch(i + 2),
+		WithdrawableEpoch:          primitives.Epoch(i + 3),
+	}
+}
+
+func makeFixedNestedContainer(value uint64) *sszquerypb.FixedNestedContainer {
+	value2 := make([]byte, 32)
+	for i := range value2 {
+		value2[i] = byte(i)
+	}
+	return &sszquerypb.FixedNestedContainer{
+		Value1: value,
+		Value2: value2,
+	}
+}
+
+func makeFixedTestContainer() *sszquerypb.FixedTestContainer {
+	fieldBytes32 := make([]byte, 32)
+	for i := range fieldBytes32 {
+		fieldBytes32[i] = byte(i)
+	}
+
+	vectorField := make([]uint64, 24)
+	for i := range vectorField {
+		vectorField[i] = uint64(i)
+	}
+
+	rows := make([][]byte, 5)
+	for i := range rows {
+		row := make([]byte, 32)
+		for j := range row {
+			row[j] = byte(i) + byte(j)
+		}
+		rows[i] = row
+	}
+
+	bitvector64 := bitfield.NewBitvector64()
+	bitvector64.SetBitAt(1, true)
+	bitvector512 := bitfield.NewBitvector512()
+	bitvector512.SetBitAt(10, true)
+
+	trailing := make([]byte, 56)
+	for i := range trailing {
+		trailing[i] = byte(i)
+	}
+
+	return &sszquerypb.FixedTestContainer{
+		FieldUint32:            1,
+		FieldUint64:            2,
+		FieldBool:              true,
+		FieldBytes32:           fieldBytes32,
+		Nested:                 makeFixedNestedContainer(3),
+		VectorField:            vectorField,
+		TwoDimensionBytesField: rows,
+		Bitvector64Field:       bitvector64,
+		Bitvector512Field:      bitvector512,
+		TrailingField:          trailing,
+	}
+}
+
+func makeVariableTestContainer(list []*sszquerypb.FixedNestedContainer, bitlist bitfield.Bitlist) *sszquerypb.VariableTestContainer {
+	leading := make([]byte, 32)
+	for i := range leading {
+		leading[i] = byte(i)
+	}
+	trailing := make([]byte, 56)
+	for i := range trailing {
+		trailing[i] = byte(255 - i)
+	}
+
+	if bitlist == nil {
+		bitlist = bitfield.NewBitlist(0)
+	}
+
+	return &sszquerypb.VariableTestContainer{
+		LeadingField:       leading,
+		FieldListContainer: list,
+		BitlistField:       bitlist,
+		TrailingField:      trailing,
+	}
+}

encoding/ssz/query/query_test.go

@@ -389,6 +389,7 @@ func TestHashTreeRoot(t *testing.T) {
 			require.NoError(t, err, "HashTreeRoot should not return an error")
 			expectedHashTreeRoot, err := tt.obj.HashTreeRoot()
 			require.NoError(t, err, "HashTreeRoot on original object should not return an error")
+			// Verify the Merkle tree root matches with the SSZ generated HashTreeRoot
 			require.Equal(t, expectedHashTreeRoot, hashTreeRoot, "HashTreeRoot from sszInfo should match original object's HashTreeRoot")
 		})
 	}

third_party/com_github_offchainlabs_hashtree.patch

@@ -1,7 +1,7 @@
 diff -urN a/BUILD.bazel b/BUILD.bazel
 --- a/BUILD.bazel	1969-12-31 18:00:00.000000000 -0600
 +++ b/BUILD.bazel	2025-01-05 12:00:00.000000000 -0600
-@@ -0,0 +1,89 @@
+@@ -0,0 +1,90 @@
 +load("@io_bazel_rules_go//go:def.bzl", "go_library")
 +
 +go_library(
@@ -32,6 +32,7 @@ diff -urN a/BUILD.bazel b/BUILD.bazel
 +        ],
 +        "@io_bazel_rules_go//go/platform:darwin_amd64": [
 +            "bindings_darwin_amd64.go",
++            "wrapper_darwin_amd64.s",
 +        ],
 +        "//conditions:default": [],
 +    }),