make it the same (#13531 )

Enable Backfill in E2E (#13524 )
* enable backfill for devmode * enable backfill * gaz * move to its own package * fix panic * fix bug * gaz * kasey's review
2026-01-09 21:38:05 -05:00 · 2024-01-26 05:35:27 +00:00 · 2024-01-26 04:37:41 +00:00 · 2024-01-26 00:05:56 +00:00 · 2024-01-25 17:07:48 +00:00 · 2024-01-25 04:56:17 +00:00
509 changed files with 14869 additions and 8602 deletions
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-6.4.0
+7.0.0
--- a/.buildkite-bazelrc
+++ b/.buildkite-bazelrc
@@ -10,7 +10,7 @@

 # Prysm specific remote-cache properties.
 build:remote-cache --remote_download_minimal
-build:remote-cache --experimental_remote_build_event_upload=minimal
+build:remote-cache --remote_build_event_upload=minimal
 build:remote-cache --remote_cache=grpc://bazel-remote-cache:9092
 # Does not work with rules_oci. See https://github.com/bazel-contrib/rules_oci/issues/292
 #build:remote-cache --experimental_remote_downloader=grpc://bazel-remote-cache:9092
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -80,7 +80,6 @@ linters:
    - thelper
    - unparam
    - varnamelen
-    - wastedassign
    - wrapcheck
    - wsl

--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -194,33 +194,6 @@ nogo(
    config = ":nogo_config_with_excludes",
    visibility = ["//visibility:public"],
    deps = [
-        "@org_golang_x_tools//go/analysis/passes/unsafeptr:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/unreachable:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/unmarshal:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/tests:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/structtag:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/stdmethods:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/shift:go_default_library",
-        # "@org_golang_x_tools//go/analysis/passes/shadow:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/printf:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/pkgfact:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/nilness:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/nilfunc:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/loopclosure:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/httpresponse:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/findcall:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/deepequalerrors:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/ctrlflow:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/copylock:go_default_library",
-        #  "@org_golang_x_tools//go/analysis/passes/cgocall:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/buildtag:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/buildssa:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/bools:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/atomicalign:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/atomic:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/assign:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/inspect:go_default_library",
-        "@org_golang_x_tools//go/analysis/passes/asmdecl:go_default_library",
        "//tools/analyzers/comparesame:go_default_library",
        "//tools/analyzers/cryptorand:go_default_library",
        "//tools/analyzers/errcheck:go_default_library",
@@ -236,6 +209,53 @@ nogo(
        "//tools/analyzers/shadowpredecl:go_default_library",
        "//tools/analyzers/slicedirect:go_default_library",
        "//tools/analyzers/uintcast:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/appends:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/asmdecl:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/assign:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/atomic:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/atomicalign:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/bools:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/buildssa:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/buildtag:go_default_library",
+        # cgocall disabled
+        #"@org_golang_x_tools//go/analysis/passes/cgocall:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/copylock:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/ctrlflow:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/deepequalerrors:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/defers:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/directive:go_default_library",
+        # fieldalignment disabled
+        #"@org_golang_x_tools//go/analysis/passes/fieldalignment:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/findcall:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/framepointer:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/httpmux:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/httpresponse:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/ifaceassert:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/inspect:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/loopclosure:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/nilfunc:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/nilness:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/pkgfact:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/printf:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/reflectvaluecompare:go_default_library",
+        # shadow disabled
+        #"@org_golang_x_tools//go/analysis/passes/shadow:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/shift:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/sigchanyzer:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/slog:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/sortslice:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/stdmethods:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/stringintconv:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/structtag:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/testinggoroutine:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/tests:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/timeformat:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/unmarshal:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/unreachable:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/unsafeptr:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/unusedresult:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/unusedwrite:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/usesgenerics:go_default_library",
    ] + select({
        # nogo checks that fail with coverage enabled.
        ":coverage_enabled": [],
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -0,0 +1,6 @@
+###############################################################################
+# Bazel now uses Bzlmod by default to manage external dependencies.
+# Please consider migrating your external dependencies from WORKSPACE to MODULE.bazel.
+#
+# For more details, please check https://github.com/bazelbuild/bazel/issues/18958
+###############################################################################
--- a/MODULE.bazel.lock
+++ b/MODULE.bazel.lock
--- a/30
+++ b/30
@@ -182,7 +182,7 @@ load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_depe
 go_rules_dependencies()

 go_register_toolchains(
-    go_version = "1.21.5",
+    go_version = "1.21.6",
    nogo = "@//:nogo",
 )

@@ -322,6 +322,22 @@ filegroup(
    url = "https://github.com/eth-clients/eth2-networks/archive/7b4897888cebef23801540236f73123e21774954.tar.gz",
 )

+http_archive(
+    name = "goerli_testnet",
+    build_file_content = """
+filegroup(
+    name = "configs",
+    srcs = [
+        "prater/config.yaml",
+    ],
+    visibility = ["//visibility:public"],
+)
+    """,
+    sha256 = "43fc0f55ddff7b511713e2de07aa22846a67432df997296fb4fc09cd8ed1dcdb",
+    strip_prefix = "goerli-6522ac6684693740cd4ddcc2a0662e03702aa4a1",
+    url = "https://github.com/eth-clients/goerli/archive/6522ac6684693740cd4ddcc2a0662e03702aa4a1.tar.gz",
+)
+
 http_archive(
    name = "holesky_testnet",
    build_file_content = """
@@ -333,17 +349,17 @@ filegroup(
    visibility = ["//visibility:public"],
 )
 """,
-    sha256 = "9f66d8d5644982d3d0d2e3d2b9ebe77a5f96638a5d7fcd715599c32818195cb3",
-    strip_prefix = "holesky-ea39b9006210848e13f28d92e12a30548cecd41d",
-    url = "https://github.com/eth-clients/holesky/archive/ea39b9006210848e13f28d92e12a30548cecd41d.tar.gz",  # 2023-09-21
+    sha256 = "5f4be6fd088683ea9db45c863b9c5a1884422449e5b59fd2d561d3ba0f73ffd9",
+    strip_prefix = "holesky-9d9aabf2d4de51334ee5fed6c79a4d55097d1a43",
+    url = "https://github.com/eth-clients/holesky/archive/9d9aabf2d4de51334ee5fed6c79a4d55097d1a43.tar.gz",  # 2024-01-22
 )

 http_archive(
    name = "com_google_protobuf",
-    sha256 = "4e176116949be52b0408dfd24f8925d1eb674a781ae242a75296b17a1c721395",
-    strip_prefix = "protobuf-23.3",
+    sha256 = "9bd87b8280ef720d3240514f884e56a712f2218f0d693b48050c836028940a42",
+    strip_prefix = "protobuf-25.1",
    urls = [
-        "https://github.com/protocolbuffers/protobuf/archive/v23.3.tar.gz",
+        "https://github.com/protocolbuffers/protobuf/archive/v25.1.tar.gz",
    ],
 )

--- a/api/client/builder/bid.go
+++ b/api/client/builder/bid.go
@@ -165,7 +165,7 @@ func WrappedBuilderBidCapella(p *ethpb.BuilderBidCapella) (Bid, error) {
 // Header returns the execution data interface.
 func (b builderBidCapella) Header() (interfaces.ExecutionData, error) {
 	// We have to convert big endian to little endian because the value is coming from the execution layer.
-	return blocks.WrappedExecutionPayloadHeaderCapella(b.p.Header, blocks.PayloadValueToGwei(b.p.Value))
+	return blocks.WrappedExecutionPayloadHeaderCapella(b.p.Header, blocks.PayloadValueToWei(b.p.Value))
 }

 // BlobKzgCommitments --
@@ -249,7 +249,7 @@ func (b builderBidDeneb) HashTreeRootWith(hh *ssz.Hasher) error {
 // Header --
 func (b builderBidDeneb) Header() (interfaces.ExecutionData, error) {
 	// We have to convert big endian to little endian because the value is coming from the execution layer.
-	return blocks.WrappedExecutionPayloadHeaderDeneb(b.p.Header, blocks.PayloadValueToGwei(b.p.Value))
+	return blocks.WrappedExecutionPayloadHeaderDeneb(b.p.Header, blocks.PayloadValueToWei(b.p.Value))
 }

 // BlobKzgCommitments --
--- a/api/client/builder/client.go
+++ b/api/client/builder/client.go
@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"math/big"
 	"net"
 	"net/http"
 	"net/url"
@@ -357,7 +358,7 @@ func (c *Client) SubmitBlindedBlock(ctx context.Context, sb interfaces.ReadOnlyS
 		if err != nil {
 			return nil, nil, errors.Wrapf(err, "could not extract proto message from payload")
 		}
-		payload, err := blocks.WrappedExecutionPayloadCapella(p, 0)
+		payload, err := blocks.WrappedExecutionPayloadCapella(p, big.NewInt(0))
 		if err != nil {
 			return nil, nil, errors.Wrapf(err, "could not wrap execution payload in interface")
 		}
@@ -394,7 +395,7 @@ func (c *Client) SubmitBlindedBlock(ctx context.Context, sb interfaces.ReadOnlyS
 		if err != nil {
 			return nil, nil, errors.Wrapf(err, "could not extract proto message from payload")
 		}
-		payload, err := blocks.WrappedExecutionPayloadDeneb(p, 0)
+		payload, err := blocks.WrappedExecutionPayloadDeneb(p, big.NewInt(0))
 		if err != nil {
 			return nil, nil, errors.Wrapf(err, "could not wrap execution payload in interface")
 		}
--- a/api/client/builder/client_test.go
+++ b/api/client/builder/client_test.go
@@ -275,7 +275,24 @@ func TestClient_GetHeader(t *testing.T) {
 			require.Equal(t, len(kcgCommitments[i]) == 48, true)
 		}
 	})
-
+	t.Run("deneb, too many kzg commitments", func(t *testing.T) {
+		hc := &http.Client{
+			Transport: roundtrip(func(r *http.Request) (*http.Response, error) {
+				require.Equal(t, expectedPath, r.URL.Path)
+				return &http.Response{
+					StatusCode: http.StatusOK,
+					Body:       io.NopCloser(bytes.NewBufferString(testExampleHeaderResponseDenebTooManyBlobs)),
+					Request:    r.Clone(ctx),
+				}, nil
+			}),
+		}
+		c := &Client{
+			hc:      hc,
+			baseURL: &url.URL{Host: "localhost:3500", Scheme: "http"},
+		}
+		_, err := c.GetHeader(ctx, slot, bytesutil.ToBytes32(parentHash), bytesutil.ToBytes48(pubkey))
+		require.ErrorContains(t, "could not extract proto message from header: too many blob commitments: 7", err)
+	})
 	t.Run("unsupported version", func(t *testing.T) {
 		hc := &http.Client{
 			Transport: roundtrip(func(r *http.Request) (*http.Response, error) {
@@ -412,7 +429,7 @@ func TestSubmitBlindedBlock(t *testing.T) {
 		require.ErrorContains(t, "not a bellatrix payload", err)
 	})
 	t.Run("not blinded", func(t *testing.T) {
-		sbb, err := blocks.NewSignedBeaconBlock(&eth.SignedBeaconBlockBellatrix{Block: &eth.BeaconBlockBellatrix{Body: &eth.BeaconBlockBodyBellatrix{}}})
+		sbb, err := blocks.NewSignedBeaconBlock(&eth.SignedBeaconBlockBellatrix{Block: &eth.BeaconBlockBellatrix{Body: &eth.BeaconBlockBodyBellatrix{ExecutionPayload: &v1.ExecutionPayload{}}}})
 		require.NoError(t, err)
 		_, _, err = (&Client{}).SubmitBlindedBlock(ctx, sbb)
 		require.ErrorIs(t, err, errNotBlinded)
--- a/api/client/builder/types.go
+++ b/api/client/builder/types.go
@@ -908,6 +908,9 @@ func (bb *BuilderBidDeneb) ToProto() (*eth.BuilderBidDeneb, error) {
 	if err != nil {
 		return nil, err
 	}
+	if len(bb.BlobKzgCommitments) > fieldparams.MaxBlobsPerBlock {
+		return nil, fmt.Errorf("too many blob commitments: %d", len(bb.BlobKzgCommitments))
+	}
 	kzgCommitments := make([][]byte, len(bb.BlobKzgCommitments))
 	for i, commit := range bb.BlobKzgCommitments {
 		if len(commit) != fieldparams.BLSPubkeyLength {
--- a/api/client/builder/types_test.go
+++ b/api/client/builder/types_test.go
@@ -209,6 +209,39 @@ var testExampleHeaderResponseUnknownVersion = `{
  }
 }`

+var testExampleHeaderResponseDenebTooManyBlobs = `{
+  "version": "deneb",
+  "data": {
+    "message": {
+      "header": {
+        "parent_hash": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2",
+        "fee_recipient": "0xabcf8e0d4e9587369b2301d0790347320302cc09",
+        "state_root": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2",
+        "receipts_root": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2",
+        "logs_bloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
+        "prev_randao": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2",
+        "block_number": "1",
+        "gas_limit": "1",
+        "gas_used": "1",
+        "timestamp": "1",
+        "extra_data": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2",
+        "base_fee_per_gas": "452312848583266388373324160190187140051835877600158453279131187530910662656",
+		"block_hash": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2",
+        "transactions_root": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2",
+        "withdrawals_root": "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2",
+		"blob_gas_used": "1",	
+		"excess_blob_gas": "2"	
+      },
+      "blob_kzg_commitments": [
+          "","","","","","",""
+	  ],
+      "value": "652312848583266388373324160190187140051835877600158453279131187530910662656",
+      "pubkey": "0x93247f2209abcacf57b75a51dafae777f9dd38bc7053d1af526f220a7489a6d3a2753e5f3e8b1cfe39b56f43611df74a"
+    },
+    "signature": "0x1b66ac1fb663c9bc59509846d6ec05345bd908eda73e670af888da41af171505cc411d61252fb6cb3fa0017b679f8bb2305b26a285fa2737f175668d0dff91cc1b66ac1fb663c9bc59509846d6ec05345bd908eda73e670af888da41af171505"
+  }
+}`
+
 func TestExecutionHeaderResponseUnmarshal(t *testing.T) {
 	hr := &ExecHeaderResponse{}
 	require.NoError(t, json.Unmarshal([]byte(testExampleHeaderResponse), hr))
--- a/api/headers.go
+++ b/api/headers.go
@@ -7,4 +7,6 @@ const (
 	ConsensusBlockValueHeader     = "Eth-Consensus-Block-Value"
 	JsonMediaType                 = "application/json"
 	OctetStreamMediaType          = "application/octet-stream"
+	EventStreamMediaType          = "text/event-stream"
+	KeepAlive                     = "keep-alive"
 )
--- a/beacon-chain/blockchain/BUILD.bazel
+++ b/beacon-chain/blockchain/BUILD.bazel
@@ -6,6 +6,7 @@ go_library(
        "chain_info.go",
        "chain_info_forkchoice.go",
        "currently_syncing_block.go",
+        "defragment.go",
        "error.go",
        "execution_engine.go",
        "forkchoice_update_execution.go",
@@ -26,6 +27,7 @@ go_library(
        "receive_blob.go",
        "receive_block.go",
        "service.go",
+        "tracked_proposer.go",
        "weak_subjectivity_checks.go",
    ],
    importpath = "github.com/prysmaticlabs/prysm/v4/beacon-chain/blockchain",
@@ -49,10 +51,10 @@ go_library(
        "//beacon-chain/core/signing:go_default_library",
        "//beacon-chain/core/time:go_default_library",
        "//beacon-chain/core/transition:go_default_library",
+        "//beacon-chain/das:go_default_library",
        "//beacon-chain/db:go_default_library",
        "//beacon-chain/db/filesystem:go_default_library",
        "//beacon-chain/db/filters:go_default_library",
-        "//beacon-chain/db/kv:go_default_library",
        "//beacon-chain/execution:go_default_library",
        "//beacon-chain/forkchoice:go_default_library",
        "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
@@ -141,6 +143,7 @@ go_test(
        "//beacon-chain/core/helpers:go_default_library",
        "//beacon-chain/core/signing:go_default_library",
        "//beacon-chain/core/transition:go_default_library",
+        "//beacon-chain/das:go_default_library",
        "//beacon-chain/db:go_default_library",
        "//beacon-chain/db/filesystem:go_default_library",
        "//beacon-chain/db/testing:go_default_library",
--- a/beacon-chain/blockchain/chain_info.go
+++ b/beacon-chain/blockchain/chain_info.go
@@ -6,7 +6,10 @@ import (
 	"time"

 	"github.com/pkg/errors"
+	"go.opencensus.io/trace"
+
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
+	f "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice"
 	doublylinkedtree "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/doubly-linked-tree"
 	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
@@ -18,7 +21,6 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
 	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/v4/time/slots"
-	"go.opencensus.io/trace"
 )

 // ChainInfoFetcher defines a common interface for methods in blockchain service which
@@ -334,12 +336,21 @@ func (s *Service) HeadValidatorIndexToPublicKey(_ context.Context, index primiti
 	return v.PublicKey(), nil
 }

+// ForkChoicer returns the forkchoice interface.
+func (s *Service) ForkChoicer() f.ForkChoicer {
+	return s.cfg.ForkChoiceStore
+}
+
 // IsOptimistic returns true if the current head is optimistic.
 func (s *Service) IsOptimistic(_ context.Context) (bool, error) {
 	if slots.ToEpoch(s.CurrentSlot()) < params.BeaconConfig().BellatrixForkEpoch {
 		return false, nil
 	}
 	s.headLock.RLock()
+	if s.head == nil {
+		s.headLock.RUnlock()
+		return false, ErrNilHead
+	}
 	headRoot := s.head.root
 	headSlot := s.head.slot
 	headOptimistic := s.head.optimistic
@@ -545,3 +556,18 @@ func (s *Service) RecentBlockSlot(root [32]byte) (primitives.Slot, error) {
 	defer s.cfg.ForkChoiceStore.RUnlock()
 	return s.cfg.ForkChoiceStore.Slot(root)
 }
+
+// inRegularSync applies the following heuristics to decide if the node is in
+// regular sync mode vs init sync mode using only forkchoice.
+// It checks that the highest received block is behind the current time by at least 2 epochs
+// and that it was imported at least one epoch late if both of these
+// tests pass then the node is in init sync. The caller of this function MUST
+// have a lock on forkchoice
+func (s *Service) inRegularSync() bool {
+	currentSlot := s.CurrentSlot()
+	fc := s.cfg.ForkChoiceStore
+	if currentSlot-fc.HighestReceivedBlockSlot() < 2*params.BeaconConfig().SlotsPerEpoch {
+		return true
+	}
+	return fc.HighestReceivedBlockDelay() < params.BeaconConfig().SlotsPerEpoch
+}
--- a/beacon-chain/blockchain/chain_info_test.go
+++ b/beacon-chain/blockchain/chain_info_test.go
@@ -429,6 +429,11 @@ func TestService_IsOptimistic(t *testing.T) {
 	opt, err = c.IsOptimistic(ctx)
 	require.NoError(t, err)
 	require.Equal(t, true, opt)
+
+	// If head is nil, for some reason, an error should be returned rather than panic.
+	c = &Service{}
+	_, err = c.IsOptimistic(ctx)
+	require.ErrorIs(t, err, ErrNilHead)
 }

 func TestService_IsOptimisticBeforeBellatrix(t *testing.T) {
@@ -588,3 +593,26 @@ func TestService_IsFinalized(t *testing.T) {
 	require.Equal(t, true, c.IsFinalized(ctx, br))
 	require.Equal(t, false, c.IsFinalized(ctx, [32]byte{'c'}))
 }
+
+func TestService_inRegularSync(t *testing.T) {
+	ctx := context.Background()
+	c := &Service{cfg: &config{ForkChoiceStore: doublylinkedtree.New()}, head: &head{root: [32]byte{'b'}}}
+	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	st, blkRoot, err := prepareForkchoiceState(ctx, 100, [32]byte{'a'}, [32]byte{}, params.BeaconConfig().ZeroHash, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, c.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))
+	require.Equal(t, false, c.inRegularSync())
+	c.SetGenesisTime(time.Now().Add(time.Second * time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot))))
+	st, blkRoot, err = prepareForkchoiceState(ctx, 128, [32]byte{'b'}, [32]byte{'a'}, params.BeaconConfig().ZeroHash, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, c.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))
+	require.Equal(t, false, c.inRegularSync())
+
+	c.SetGenesisTime(time.Now().Add(time.Second * time.Duration(-5*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot))))
+	require.Equal(t, true, c.inRegularSync())
+
+	c.SetGenesisTime(time.Now().Add(time.Second * time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch)*int64(params.BeaconConfig().SecondsPerSlot))))
+	c.cfg.ForkChoiceStore.SetGenesisTime(uint64(time.Now().Unix()))
+	require.Equal(t, true, c.inRegularSync())
+}
--- a/beacon-chain/blockchain/defragment.go
+++ b/beacon-chain/blockchain/defragment.go
@@ -0,0 +1,27 @@
+package blockchain
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/config/features"
+	"github.com/prysmaticlabs/prysm/v4/time"
+)
+
+var stateDefragmentationTime = promauto.NewSummary(prometheus.SummaryOpts{
+	Name: "head_state_defragmentation_milliseconds",
+	Help: "Milliseconds it takes to defragment the head state",
+})
+
+// This method defragments our state, so that any specific fields which have
+// a higher number of fragmented indexes are reallocated to a new separate slice for
+// that field.
+func (s *Service) defragmentState(st state.BeaconState) {
+	if !features.Get().EnableExperimentalState {
+		return
+	}
+	startTime := time.Now()
+	st.Defragment()
+	elapsedTime := time.Since(startTime)
+	stateDefragmentationTime.Observe(float64(elapsedTime.Milliseconds()))
+}
--- a/beacon-chain/blockchain/error.go
+++ b/beacon-chain/blockchain/error.go
@@ -28,6 +28,8 @@ var (
 	// ErrNotCheckpoint is returned when a given checkpoint is not a
 	// checkpoint in any chain known to forkchoice
 	ErrNotCheckpoint = errors.New("not a checkpoint in forkchoice")
+	// ErrNilHead is returned when no head is present in the blockchain service.
+	ErrNilHead = errors.New("nil head")
 )

 var errMaxBlobsExceeded = errors.New("Expected commitments in block exceeds MAX_BLOBS_PER_BLOCK")
--- a/beacon-chain/blockchain/execution_engine.go
+++ b/beacon-chain/blockchain/execution_engine.go
@@ -7,11 +7,11 @@ import (

 	"github.com/ethereum/go-ethereum/common"
 	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
-	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db/kv"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/execution"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/v4/config/features"
@@ -32,21 +32,18 @@ const blobCommitmentVersionKZG uint8 = 0x01

 var defaultLatestValidHash = bytesutil.PadTo([]byte{0xff}, 32)

-// notifyForkchoiceUpdateArg is the argument for the forkchoice update notification `notifyForkchoiceUpdate`.
-type notifyForkchoiceUpdateArg struct {
-	headState state.BeaconState
-	headRoot  [32]byte
-	headBlock interfaces.ReadOnlyBeaconBlock
-}
-
 // notifyForkchoiceUpdate signals execution engine the fork choice updates. Execution engine should:
 // 1. Re-organizes the execution payload chain and corresponding state to make head_block_hash the head.
 // 2. Applies finality to the execution state: it irreversibly persists the chain of all execution payloads and corresponding state, up to and including finalized_block_hash.
-func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkchoiceUpdateArg) (*enginev1.PayloadIDBytes, error) {
+func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *fcuConfig) (*enginev1.PayloadIDBytes, error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.notifyForkchoiceUpdate")
 	defer span.End()

-	headBlk := arg.headBlock
+	if arg.headBlock.IsNil() {
+		log.Error("Head block is nil")
+		return nil, nil
+	}
+	headBlk := arg.headBlock.Block()
 	if headBlk == nil || headBlk.IsNil() || headBlk.Body().IsNil() {
 		log.Error("Head block is nil")
 		return nil, nil
@@ -72,11 +69,10 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkcho
 		SafeBlockHash:      justifiedHash[:],
 		FinalizedBlockHash: finalizedHash[:],
 	}
-
-	nextSlot := s.CurrentSlot() + 1 // Cache payload ID for next slot proposer.
-	hasAttr, attr, proposerId := s.getPayloadAttribute(ctx, arg.headState, nextSlot, arg.headRoot[:])
-
-	payloadID, lastValidHash, err := s.cfg.ExecutionEngineCaller.ForkchoiceUpdated(ctx, fcs, attr)
+	if arg.attributes == nil {
+		arg.attributes = payloadattribute.EmptyWithVersion(headBlk.Version())
+	}
+	payloadID, lastValidHash, err := s.cfg.ExecutionEngineCaller.ForkchoiceUpdated(ctx, fcs, arg.attributes)
 	if err != nil {
 		switch err {
 		case execution.ErrAcceptedSyncingPayloadStatus:
@@ -122,10 +118,11 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkcho
 				log.WithError(err).Error("Could not get head state")
 				return nil, nil
 			}
-			pid, err := s.notifyForkchoiceUpdate(ctx, &notifyForkchoiceUpdateArg{
-				headState: st,
-				headRoot:  r,
-				headBlock: b.Block(),
+			pid, err := s.notifyForkchoiceUpdate(ctx, &fcuConfig{
+				headState:  st,
+				headRoot:   r,
+				headBlock:  b,
+				attributes: arg.attributes,
 			})
 			if err != nil {
 				return nil, err // Returning err because it's recursive here.
@@ -153,7 +150,9 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkcho
 		log.WithError(err).Error("Could not set head root to valid")
 		return nil, nil
 	}
-	// If the forkchoice update call has an attribute, update the proposer payload ID cache.
+	// If the forkchoice update call has an attribute, update the payload ID cache.
+	hasAttr := arg.attributes != nil && !arg.attributes.IsEmpty()
+	nextSlot := s.CurrentSlot() + 1
 	if hasAttr && payloadID != nil {
 		var pId [8]byte
 		copy(pId[:], payloadID[:])
@@ -162,7 +161,7 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkcho
 			"headSlot":  headBlk.Slot(),
 			"payloadID": fmt.Sprintf("%#x", bytesutil.Trunc(payloadID[:])),
 		}).Info("Forkchoice updated with payload attributes for proposal")
-		s.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(nextSlot, proposerId, pId, arg.headRoot)
+		s.cfg.PayloadIDCache.Set(nextSlot, arg.headRoot, pId)
 	} else if hasAttr && payloadID == nil && !features.Get().PrepareAllPayloads {
 		log.WithFields(logrus.Fields{
 			"blockHash": fmt.Sprintf("%#x", headPayload.BlockHash()),
@@ -277,56 +276,50 @@ func (s *Service) pruneInvalidBlock(ctx context.Context, root, parentRoot, lvh [

 // getPayloadAttributes returns the payload attributes for the given state and slot.
 // The attribute is required to initiate a payload build process in the context of an `engine_forkchoiceUpdated` call.
-func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState, slot primitives.Slot, headRoot []byte) (bool, payloadattribute.Attributer, primitives.ValidatorIndex) {
+func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState, slot primitives.Slot, headRoot []byte) payloadattribute.Attributer {
 	emptyAttri := payloadattribute.EmptyWithVersion(st.Version())
-	// Root is `[32]byte{}` since we are retrieving proposer ID of a given slot. During insertion at assignment the root was not known.
-	proposerID, _, ok := s.cfg.ProposerSlotIndexCache.GetProposerPayloadIDs(slot, [32]byte{} /* root */)
-	if !ok && !features.Get().PrepareAllPayloads { // There's no need to build attribute if there is no proposer for slot.
-		return false, emptyAttri, 0
-	}

-	// Get previous randao.
+	// If it is an epoch boundary then process slots to get the right
+	// shuffling before checking if the proposer is tracked. Otherwise
+	// perform this check before. This is cheap as the NSC has already been updated.
+	var val cache.TrackedValidator
+	var ok bool
+	e := slots.ToEpoch(slot)
+	stateEpoch := slots.ToEpoch(st.Slot())
+	if e == stateEpoch {
+		val, ok = s.trackedProposer(st, slot)
+		if !ok {
+			return emptyAttri
+		}
+	}
 	st = st.Copy()
 	if slot > st.Slot() {
 		var err error
 		st, err = transition.ProcessSlotsUsingNextSlotCache(ctx, st, headRoot, slot)
 		if err != nil {
 			log.WithError(err).Error("Could not process slots to get payload attribute")
-			return false, emptyAttri, 0
+			return emptyAttri
 		}
 	}
+	if e > stateEpoch {
+		emptyAttri := payloadattribute.EmptyWithVersion(st.Version())
+		val, ok = s.trackedProposer(st, slot)
+		if !ok {
+			return emptyAttri
+		}
+	}
+	// Get previous randao.
 	prevRando, err := helpers.RandaoMix(st, time.CurrentEpoch(st))
 	if err != nil {
 		log.WithError(err).Error("Could not get randao mix to get payload attribute")
-		return false, emptyAttri, 0
-	}
-
-	// Get fee recipient.
-	feeRecipient := params.BeaconConfig().DefaultFeeRecipient
-	recipient, err := s.cfg.BeaconDB.FeeRecipientByValidatorID(ctx, proposerID)
-	switch {
-	case errors.Is(err, kv.ErrNotFoundFeeRecipient):
-		if feeRecipient.String() == params.BeaconConfig().EthBurnAddressHex {
-			logrus.WithFields(logrus.Fields{
-				"validatorIndex": proposerID,
-				"burnAddress":    params.BeaconConfig().EthBurnAddressHex,
-			}).Warn("Fee recipient is currently using the burn address, " +
-				"you will not be rewarded transaction fees on this setting. " +
-				"Please set a different eth address as the fee recipient. " +
-				"Please refer to our documentation for instructions")
-		}
-	case err != nil:
-		log.WithError(err).Error("Could not get fee recipient to get payload attribute")
-		return false, emptyAttri, 0
-	default:
-		feeRecipient = recipient
+		return emptyAttri
 	}

 	// Get timestamp.
 	t, err := slots.ToTime(uint64(s.genesisTime.Unix()), slot)
 	if err != nil {
 		log.WithError(err).Error("Could not get timestamp to get payload attribute")
-		return false, emptyAttri, 0
+		return emptyAttri
 	}

 	var attr payloadattribute.Attributer
@@ -335,51 +328,51 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,
 		withdrawals, err := st.ExpectedWithdrawals()
 		if err != nil {
 			log.WithError(err).Error("Could not get expected withdrawals to get payload attribute")
-			return false, emptyAttri, 0
+			return emptyAttri
 		}
 		attr, err = payloadattribute.New(&enginev1.PayloadAttributesV3{
 			Timestamp:             uint64(t.Unix()),
 			PrevRandao:            prevRando,
-			SuggestedFeeRecipient: feeRecipient.Bytes(),
+			SuggestedFeeRecipient: val.FeeRecipient[:],
 			Withdrawals:           withdrawals,
 			ParentBeaconBlockRoot: headRoot,
 		})
 		if err != nil {
 			log.WithError(err).Error("Could not get payload attribute")
-			return false, emptyAttri, 0
+			return emptyAttri
 		}
 	case version.Capella:
 		withdrawals, err := st.ExpectedWithdrawals()
 		if err != nil {
 			log.WithError(err).Error("Could not get expected withdrawals to get payload attribute")
-			return false, emptyAttri, 0
+			return emptyAttri
 		}
 		attr, err = payloadattribute.New(&enginev1.PayloadAttributesV2{
 			Timestamp:             uint64(t.Unix()),
 			PrevRandao:            prevRando,
-			SuggestedFeeRecipient: feeRecipient.Bytes(),
+			SuggestedFeeRecipient: val.FeeRecipient[:],
 			Withdrawals:           withdrawals,
 		})
 		if err != nil {
 			log.WithError(err).Error("Could not get payload attribute")
-			return false, emptyAttri, 0
+			return emptyAttri
 		}
 	case version.Bellatrix:
 		attr, err = payloadattribute.New(&enginev1.PayloadAttributes{
 			Timestamp:             uint64(t.Unix()),
 			PrevRandao:            prevRando,
-			SuggestedFeeRecipient: feeRecipient.Bytes(),
+			SuggestedFeeRecipient: val.FeeRecipient[:],
 		})
 		if err != nil {
 			log.WithError(err).Error("Could not get payload attribute")
-			return false, emptyAttri, 0
+			return emptyAttri
 		}
 	default:
 		log.WithField("version", st.Version()).Error("Could not get payload attribute due to unknown state version")
-		return false, emptyAttri, 0
+		return emptyAttri
 	}

-	return true, attr, proposerID
+	return attr
 }

 // removeInvalidBlockAndState removes the invalid block, blob and its corresponding state from the cache and DB.
@@ -394,9 +387,9 @@ func (s *Service) removeInvalidBlockAndState(ctx context.Context, blkRoots [][32
 			// This is an irreparable condition, it would me a justified or finalized block has become invalid.
 			return err
 		}
-		// No op if the sidecar does not exist.
-		if err := s.cfg.BeaconDB.DeleteBlobSidecars(ctx, root); err != nil {
-			return err
+		if err := s.blobStorage.Remove(root); err != nil {
+			// Blobs may not exist for some blocks, leading to deletion failures. Log such errors at debug level.
+			log.WithError(err).Debug("Could not remove blob from blob storage")
 		}
 	}
 	return nil
--- a/beacon-chain/blockchain/execution_engine_test.go
+++ b/beacon-chain/blockchain/execution_engine_test.go
@@ -26,11 +26,10 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/testing/assert"
 	"github.com/prysmaticlabs/prysm/v4/testing/require"
 	"github.com/prysmaticlabs/prysm/v4/testing/util"
-	logTest "github.com/sirupsen/logrus/hooks/test"
 )

 func Test_NotifyForkchoiceUpdate_GetPayloadAttrErrorCanContinue(t *testing.T) {
-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

 	altairBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockAltair())
@@ -57,11 +56,14 @@ func Test_NotifyForkchoiceUpdate_GetPayloadAttrErrorCanContinue(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, fcs.InsertNode(ctx, state, blkRoot))

-	b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
-		Body: &ethpb.BeaconBlockBodyBellatrix{
-			ExecutionPayload: &v1.ExecutionPayload{},
+	sb := &ethpb.SignedBeaconBlockBellatrix{
+		Block: &ethpb.BeaconBlockBellatrix{
+			Body: &ethpb.BeaconBlockBodyBellatrix{
+				ExecutionPayload: &v1.ExecutionPayload{},
+			},
 		},
-	})
+	}
+	b, err := consensusblocks.NewSignedBeaconBlock(sb)
 	require.NoError(t, err)

 	pid := &v1.PayloadIDBytes{1}
@@ -73,20 +75,20 @@ func Test_NotifyForkchoiceUpdate_GetPayloadAttrErrorCanContinue(t *testing.T) {
 	// Intentionally generate a bad state such that `hash_tree_root` fails during `process_slot`
 	s, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{})
 	require.NoError(t, err)
-	arg := &notifyForkchoiceUpdateArg{
+	arg := &fcuConfig{
 		headState: s,
 		headRoot:  [32]byte{},
 		headBlock: b,
 	}

-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(1, 0, [8]byte{}, [32]byte{})
+	service.cfg.PayloadIDCache.Set(1, [32]byte{}, [8]byte{})
 	got, err := service.notifyForkchoiceUpdate(ctx, arg)
 	require.NoError(t, err)
 	require.DeepEqual(t, got, pid) // We still get a payload ID even though the state is bad. This means it returns until the end.
 }

 func Test_NotifyForkchoiceUpdate(t *testing.T) {
-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

 	altairBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockAltair())
@@ -114,7 +116,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {

 	tests := []struct {
 		name             string
-		blk              interfaces.ReadOnlyBeaconBlock
+		blk              interfaces.ReadOnlySignedBeaconBlock
 		headRoot         [32]byte
 		finalizedRoot    [32]byte
 		justifiedRoot    [32]byte
@@ -123,24 +125,24 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 	}{
 		{
 			name: "phase0 block",
-			blk: func() interfaces.ReadOnlyBeaconBlock {
-				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}})
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
+				b, err := consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}}})
 				require.NoError(t, err)
 				return b
 			}(),
 		},
 		{
 			name: "altair block",
-			blk: func() interfaces.ReadOnlyBeaconBlock {
-				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockAltair{Body: &ethpb.BeaconBlockBodyAltair{}})
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
+				b, err := consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlockAltair{Block: &ethpb.BeaconBlockAltair{Body: &ethpb.BeaconBlockBodyAltair{}}})
 				require.NoError(t, err)
 				return b
 			}(),
 		},
 		{
 			name: "not execution block",
-			blk: func() interfaces.ReadOnlyBeaconBlock {
-				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
+				b, err := consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlockBellatrix{Block: &ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{
 							ParentHash:    make([]byte, fieldparams.RootLength),
@@ -149,23 +151,25 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 							ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 							LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
 							PrevRandao:    make([]byte, fieldparams.RootLength),
+							ExtraData:     make([]byte, 0),
 							BaseFeePerGas: make([]byte, fieldparams.RootLength),
 							BlockHash:     make([]byte, fieldparams.RootLength),
+							Transactions:  make([][]byte, 0),
 						},
 					},
-				})
+				}})
 				require.NoError(t, err)
 				return b
 			}(),
 		},
 		{
 			name: "happy case: finalized root is altair block",
-			blk: func() interfaces.ReadOnlyBeaconBlock {
-				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
+				b, err := consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlockBellatrix{Block: &ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{},
 					},
-				})
+				}})
 				require.NoError(t, err)
 				return b
 			}(),
@@ -174,12 +178,12 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "happy case: finalized root is bellatrix block",
-			blk: func() interfaces.ReadOnlyBeaconBlock {
-				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
+				b, err := consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlockBellatrix{Block: &ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{},
 					},
-				})
+				}})
 				require.NoError(t, err)
 				return b
 			}(),
@@ -188,12 +192,12 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "forkchoice updated with optimistic block",
-			blk: func() interfaces.ReadOnlyBeaconBlock {
-				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
+				b, err := consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlockBellatrix{Block: &ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{},
 					},
-				})
+				}})
 				require.NoError(t, err)
 				return b
 			}(),
@@ -203,12 +207,12 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "forkchoice updated with invalid block",
-			blk: func() interfaces.ReadOnlyBeaconBlock {
-				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
+				b, err := consensusblocks.NewSignedBeaconBlock(&ethpb.SignedBeaconBlockBellatrix{Block: &ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{},
 					},
-				})
+				}})
 				require.NoError(t, err)
 				return b
 			}(),
@@ -226,7 +230,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 			st, _ := util.DeterministicGenesisState(t, 1)
 			require.NoError(t, beaconDB.SaveState(ctx, st, tt.finalizedRoot))
 			require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, tt.finalizedRoot))
-			arg := &notifyForkchoiceUpdateArg{
+			arg := &fcuConfig{
 				headState: st,
 				headRoot:  tt.headRoot,
 				headBlock: tt.blk,
@@ -246,7 +250,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 }

 func Test_NotifyForkchoiceUpdate_NIlLVH(t *testing.T) {
-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

 	// Prepare blocks
@@ -306,9 +310,9 @@ func Test_NotifyForkchoiceUpdate_NIlLVH(t *testing.T) {

 	require.NoError(t, beaconDB.SaveState(ctx, st, bra))
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, bra))
-	a := &notifyForkchoiceUpdateArg{
+	a := &fcuConfig{
 		headState: st,
-		headBlock: wbd.Block(),
+		headBlock: wbd,
 		headRoot:  brd,
 	}
 	_, err = service.notifyForkchoiceUpdate(ctx, a)
@@ -334,7 +338,7 @@ func Test_NotifyForkchoiceUpdate_NIlLVH(t *testing.T) {
 // 3. the blockchain package calls fcu to obtain heads G -> F -> D.

 func Test_NotifyForkchoiceUpdateRecursive_DoublyLinkedTree(t *testing.T) {
-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

 	// Prepare blocks
@@ -443,9 +447,9 @@ func Test_NotifyForkchoiceUpdateRecursive_DoublyLinkedTree(t *testing.T) {

 	require.NoError(t, beaconDB.SaveState(ctx, st, bra))
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, bra))
-	a := &notifyForkchoiceUpdateArg{
+	a := &fcuConfig{
 		headState: st,
-		headBlock: wbg.Block(),
+		headBlock: wbg,
 		headRoot:  brg,
 	}
 	_, err = service.notifyForkchoiceUpdate(ctx, a)
@@ -467,7 +471,7 @@ func Test_NotifyNewPayload(t *testing.T) {
 	cfg := params.BeaconConfig()
 	cfg.TerminalTotalDifficulty = "2"
 	params.OverrideBeaconConfig(cfg)
-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx, fcs := tr.ctx, tr.fcs

 	phase0State, _ := util.DeterministicGenesisState(t, 1)
@@ -492,8 +496,10 @@ func Test_NotifyNewPayload(t *testing.T) {
 					ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 					LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
 					PrevRandao:    make([]byte, fieldparams.RootLength),
+					ExtraData:     make([]byte, 0),
 					BaseFeePerGas: make([]byte, fieldparams.RootLength),
 					BlockHash:     make([]byte, fieldparams.RootLength),
+					Transactions:  make([][]byte, 0),
 				},
 			},
 		},
@@ -595,8 +601,10 @@ func Test_NotifyNewPayload(t *testing.T) {
 								ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 								LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
 								PrevRandao:    make([]byte, fieldparams.RootLength),
+								ExtraData:     make([]byte, 0),
 								BaseFeePerGas: make([]byte, fieldparams.RootLength),
 								BlockHash:     make([]byte, fieldparams.RootLength),
+								Transactions:  make([][]byte, 0),
 							},
 						},
 					},
@@ -709,7 +717,7 @@ func Test_NotifyNewPayload_SetOptimisticToValid(t *testing.T) {
 	cfg.TerminalTotalDifficulty = "2"
 	params.OverrideBeaconConfig(cfg)

-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx := tr.ctx

 	bellatrixState, _ := util.DeterministicGenesisStateBellatrix(t, 2)
@@ -777,83 +785,70 @@ func Test_reportInvalidBlock(t *testing.T) {
 }

 func Test_GetPayloadAttribute(t *testing.T) {
-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx := tr.ctx

 	st, _ := util.DeterministicGenesisStateBellatrix(t, 1)
-	hasPayload, _, vId := service.getPayloadAttribute(ctx, st, 0, []byte{})
-	require.Equal(t, false, hasPayload)
-	require.Equal(t, primitives.ValidatorIndex(0), vId)
+	attr := service.getPayloadAttribute(ctx, st, 0, []byte{})
+	require.Equal(t, true, attr.IsEmpty())

+	service.cfg.TrackedValidatorsCache.Set(cache.TrackedValidator{Active: true, Index: 0})
 	// Cache hit, advance state, no fee recipient
-	suggestedVid := primitives.ValidatorIndex(1)
 	slot := primitives.Slot(1)
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(slot, suggestedVid, [8]byte{}, [32]byte{})
-	hook := logTest.NewGlobal()
-	hasPayload, attr, vId := service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
-	require.Equal(t, true, hasPayload)
-	require.Equal(t, suggestedVid, vId)
+	service.cfg.PayloadIDCache.Set(slot, [32]byte{}, [8]byte{})
+	attr = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
+	require.Equal(t, false, attr.IsEmpty())
 	require.Equal(t, params.BeaconConfig().EthBurnAddressHex, common.BytesToAddress(attr.SuggestedFeeRecipient()).String())
-	require.LogsContain(t, hook, "Fee recipient is currently using the burn address")

 	// Cache hit, advance state, has fee recipient
 	suggestedAddr := common.HexToAddress("123")
-	require.NoError(t, service.cfg.BeaconDB.SaveFeeRecipientsByValidatorIDs(ctx, []primitives.ValidatorIndex{suggestedVid}, []common.Address{suggestedAddr}))
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(slot, suggestedVid, [8]byte{}, [32]byte{})
-	hasPayload, attr, vId = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
-	require.Equal(t, true, hasPayload)
-	require.Equal(t, suggestedVid, vId)
+	service.cfg.TrackedValidatorsCache.Set(cache.TrackedValidator{Active: true, FeeRecipient: primitives.ExecutionAddress(suggestedAddr), Index: 0})
+	service.cfg.PayloadIDCache.Set(slot, [32]byte{}, [8]byte{})
+	attr = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
+	require.Equal(t, false, attr.IsEmpty())
 	require.Equal(t, suggestedAddr, common.BytesToAddress(attr.SuggestedFeeRecipient()))
 }

 func Test_GetPayloadAttribute_PrepareAllPayloads(t *testing.T) {
-	hook := logTest.NewGlobal()
 	resetCfg := features.InitWithReset(&features.Flags{
 		PrepareAllPayloads: true,
 	})
 	defer resetCfg()

-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx := tr.ctx

 	st, _ := util.DeterministicGenesisStateBellatrix(t, 1)
-	hasPayload, attr, vId := service.getPayloadAttribute(ctx, st, 0, []byte{})
-	require.Equal(t, true, hasPayload)
-	require.Equal(t, primitives.ValidatorIndex(0), vId)
+	attr := service.getPayloadAttribute(ctx, st, 0, []byte{})
+	require.Equal(t, false, attr.IsEmpty())
 	require.Equal(t, params.BeaconConfig().EthBurnAddressHex, common.BytesToAddress(attr.SuggestedFeeRecipient()).String())
-	require.LogsContain(t, hook, "Fee recipient is currently using the burn address")
 }

 func Test_GetPayloadAttributeV2(t *testing.T) {
-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx := tr.ctx

 	st, _ := util.DeterministicGenesisStateCapella(t, 1)
-	hasPayload, _, vId := service.getPayloadAttribute(ctx, st, 0, []byte{})
-	require.Equal(t, false, hasPayload)
-	require.Equal(t, primitives.ValidatorIndex(0), vId)
+	attr := service.getPayloadAttribute(ctx, st, 0, []byte{})
+	require.Equal(t, true, attr.IsEmpty())

 	// Cache hit, advance state, no fee recipient
-	suggestedVid := primitives.ValidatorIndex(1)
+	service.cfg.TrackedValidatorsCache.Set(cache.TrackedValidator{Active: true, Index: 0})
 	slot := primitives.Slot(1)
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(slot, suggestedVid, [8]byte{}, [32]byte{})
-	hook := logTest.NewGlobal()
-	hasPayload, attr, vId := service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
-	require.Equal(t, true, hasPayload)
-	require.Equal(t, suggestedVid, vId)
+	service.cfg.PayloadIDCache.Set(slot, [32]byte{}, [8]byte{})
+	attr = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
+	require.Equal(t, false, attr.IsEmpty())
 	require.Equal(t, params.BeaconConfig().EthBurnAddressHex, common.BytesToAddress(attr.SuggestedFeeRecipient()).String())
-	require.LogsContain(t, hook, "Fee recipient is currently using the burn address")
 	a, err := attr.Withdrawals()
 	require.NoError(t, err)
 	require.Equal(t, 0, len(a))

 	// Cache hit, advance state, has fee recipient
 	suggestedAddr := common.HexToAddress("123")
-	require.NoError(t, service.cfg.BeaconDB.SaveFeeRecipientsByValidatorIDs(ctx, []primitives.ValidatorIndex{suggestedVid}, []common.Address{suggestedAddr}))
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(slot, suggestedVid, [8]byte{}, [32]byte{})
-	hasPayload, attr, vId = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
-	require.Equal(t, true, hasPayload)
-	require.Equal(t, suggestedVid, vId)
+	service.cfg.TrackedValidatorsCache.Set(cache.TrackedValidator{Active: true, FeeRecipient: primitives.ExecutionAddress(suggestedAddr), Index: 0})
+	service.cfg.PayloadIDCache.Set(slot, [32]byte{}, [8]byte{})
+	attr = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
+	require.Equal(t, false, attr.IsEmpty())
 	require.Equal(t, suggestedAddr, common.BytesToAddress(attr.SuggestedFeeRecipient()))
 	a, err = attr.Withdrawals()
 	require.NoError(t, err)
@@ -861,35 +856,30 @@ func Test_GetPayloadAttributeV2(t *testing.T) {
 }

 func Test_GetPayloadAttributeDeneb(t *testing.T) {
-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx := tr.ctx

 	st, _ := util.DeterministicGenesisStateDeneb(t, 1)
-	hasPayload, _, vId := service.getPayloadAttribute(ctx, st, 0, []byte{})
-	require.Equal(t, false, hasPayload)
-	require.Equal(t, primitives.ValidatorIndex(0), vId)
+	attr := service.getPayloadAttribute(ctx, st, 0, []byte{})
+	require.Equal(t, true, attr.IsEmpty())

 	// Cache hit, advance state, no fee recipient
-	suggestedVid := primitives.ValidatorIndex(1)
 	slot := primitives.Slot(1)
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(slot, suggestedVid, [8]byte{}, [32]byte{})
-	hook := logTest.NewGlobal()
-	hasPayload, attr, vId := service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
-	require.Equal(t, true, hasPayload)
-	require.Equal(t, suggestedVid, vId)
+	service.cfg.TrackedValidatorsCache.Set(cache.TrackedValidator{Active: true, Index: 0})
+	service.cfg.PayloadIDCache.Set(slot, [32]byte{}, [8]byte{})
+	attr = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
+	require.Equal(t, false, attr.IsEmpty())
 	require.Equal(t, params.BeaconConfig().EthBurnAddressHex, common.BytesToAddress(attr.SuggestedFeeRecipient()).String())
-	require.LogsContain(t, hook, "Fee recipient is currently using the burn address")
 	a, err := attr.Withdrawals()
 	require.NoError(t, err)
 	require.Equal(t, 0, len(a))

 	// Cache hit, advance state, has fee recipient
 	suggestedAddr := common.HexToAddress("123")
-	require.NoError(t, service.cfg.BeaconDB.SaveFeeRecipientsByValidatorIDs(ctx, []primitives.ValidatorIndex{suggestedVid}, []common.Address{suggestedAddr}))
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(slot, suggestedVid, [8]byte{}, [32]byte{})
-	hasPayload, attr, vId = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
-	require.Equal(t, true, hasPayload)
-	require.Equal(t, suggestedVid, vId)
+	service.cfg.TrackedValidatorsCache.Set(cache.TrackedValidator{Active: true, FeeRecipient: primitives.ExecutionAddress(suggestedAddr), Index: 0})
+	service.cfg.PayloadIDCache.Set(slot, [32]byte{}, [8]byte{})
+	attr = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
+	require.Equal(t, false, attr.IsEmpty())
 	require.Equal(t, suggestedAddr, common.BytesToAddress(attr.SuggestedFeeRecipient()))
 	a, err = attr.Withdrawals()
 	require.NoError(t, err)
@@ -1112,3 +1102,35 @@ func TestKZGCommitmentToVersionedHashes(t *testing.T) {
 	require.Equal(t, vhs[0].String(), vh0)
 	require.Equal(t, vhs[1].String(), vh1)
 }
+
+func TestComputePayloadAttribute(t *testing.T) {
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
+	ctx := tr.ctx
+
+	st, _ := util.DeterministicGenesisStateBellatrix(t, 1)
+
+	service.cfg.TrackedValidatorsCache.Set(cache.TrackedValidator{Active: true, Index: 0})
+	// Cache hit, advance state, no fee recipient
+	slot := primitives.Slot(1)
+	service.cfg.PayloadIDCache.Set(slot, [32]byte{}, [8]byte{})
+	cfg := &postBlockProcessConfig{
+		ctx:       ctx,
+		blockRoot: [32]byte{'a'},
+	}
+	fcu := &fcuConfig{
+		headState:     st,
+		proposingSlot: slot,
+		headRoot:      [32]byte{},
+	}
+	require.NoError(t, service.computePayloadAttributes(cfg, fcu))
+	require.Equal(t, false, fcu.attributes.IsEmpty())
+	require.Equal(t, params.BeaconConfig().EthBurnAddressHex, common.BytesToAddress(fcu.attributes.SuggestedFeeRecipient()).String())
+
+	// Cache hit, advance state, has fee recipient
+	suggestedAddr := common.HexToAddress("123")
+	service.cfg.TrackedValidatorsCache.Set(cache.TrackedValidator{Active: true, FeeRecipient: primitives.ExecutionAddress(suggestedAddr), Index: 0})
+	service.cfg.PayloadIDCache.Set(slot, [32]byte{}, [8]byte{})
+	require.NoError(t, service.computePayloadAttributes(cfg, fcu))
+	require.Equal(t, false, fcu.attributes.IsEmpty())
+	require.Equal(t, suggestedAddr, common.BytesToAddress(fcu.attributes.SuggestedFeeRecipient()))
+}
--- a/beacon-chain/blockchain/forkchoice_update_execution.go
+++ b/beacon-chain/blockchain/forkchoice_update_execution.go
@@ -8,20 +8,15 @@ import (
 	"github.com/pkg/errors"
 	doublylinkedtree "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/doubly-linked-tree"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v4/config/features"
 	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
+	payloadattribute "github.com/prysmaticlabs/prysm/v4/consensus-types/payload-attribute"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )

-func (s *Service) isNewProposer(slot primitives.Slot) bool {
-	_, _, ok := s.cfg.ProposerSlotIndexCache.GetProposerPayloadIDs(slot, [32]byte{} /* root */)
-	return ok || features.Get().PrepareAllPayloads
-}
-
 func (s *Service) isNewHead(r [32]byte) bool {
 	s.headLock.RLock()
 	defer s.headLock.RUnlock()
@@ -49,48 +44,69 @@ func (s *Service) getStateAndBlock(ctx context.Context, r [32]byte) (state.Beaco
 	return headState, newHeadBlock, nil
 }

+type fcuConfig struct {
+	headState     state.BeaconState
+	headBlock     interfaces.ReadOnlySignedBeaconBlock
+	headRoot      [32]byte
+	proposingSlot primitives.Slot
+	attributes    payloadattribute.Attributer
+}
+
+// sendFCU handles the logic to notify the engine of a forckhoice update
+// for the first time when processing an incoming block during regular sync. It
+// always updates the shuffling caches and handles epoch transitions when the
+// incoming block is late, preparing payload attributes in this case while it
+// only sends a message with empty attributes for early blocks.
+func (s *Service) sendFCU(cfg *postBlockProcessConfig, fcuArgs *fcuConfig) error {
+	if !s.isNewHead(cfg.headRoot) {
+		return nil
+	}
+	if fcuArgs.attributes != nil && !fcuArgs.attributes.IsEmpty() && s.shouldOverrideFCU(cfg.headRoot, s.CurrentSlot()+1) {
+		return nil
+	}
+	return s.forkchoiceUpdateWithExecution(cfg.ctx, fcuArgs)
+}
+
+// sendFCUWithAttributes computes the payload attributes and sends an FCU message
+// to the engine if needed
+func (s *Service) sendFCUWithAttributes(cfg *postBlockProcessConfig, fcuArgs *fcuConfig) {
+	slotCtx, cancel := context.WithTimeout(context.Background(), slotDeadline)
+	defer cancel()
+	cfg.ctx = slotCtx
+	if err := s.computePayloadAttributes(cfg, fcuArgs); err != nil {
+		log.WithError(err).Error("could not compute payload attributes")
+		return
+	}
+	if fcuArgs.attributes.IsEmpty() {
+		return
+	}
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	if _, err := s.notifyForkchoiceUpdate(cfg.ctx, fcuArgs); err != nil {
+		log.WithError(err).Error("could not update forkchoice with payload attributes for proposal")
+	}
+}
+
 // fockchoiceUpdateWithExecution is a wrapper around notifyForkchoiceUpdate. It decides whether a new call to FCU should be made.
-// it returns true if the new head is updated
-func (s *Service) forkchoiceUpdateWithExecution(ctx context.Context, newHeadRoot [32]byte, proposingSlot primitives.Slot) (bool, error) {
+func (s *Service) forkchoiceUpdateWithExecution(ctx context.Context, args *fcuConfig) error {
 	_, span := trace.StartSpan(ctx, "beacon-chain.blockchain.forkchoiceUpdateWithExecution")
 	defer span.End()
 	// Note: Use the service context here to avoid the parent context being ended during a forkchoice update.
 	ctx = trace.NewContext(s.ctx, span)
-
-	isNewHead := s.isNewHead(newHeadRoot)
-	if !isNewHead {
-		return false, nil
-	}
-	isNewProposer := s.isNewProposer(proposingSlot)
-	if isNewProposer && !features.Get().DisableReorgLateBlocks {
-		if s.shouldOverrideFCU(newHeadRoot, proposingSlot) {
-			return false, nil
-		}
-	}
-	headState, headBlock, err := s.getStateAndBlock(ctx, newHeadRoot)
+	_, err := s.notifyForkchoiceUpdate(ctx, args)
 	if err != nil {
-		log.WithError(err).Error("Could not get forkchoice update argument")
-		return false, nil
+		return errors.Wrap(err, "could not notify forkchoice update")
 	}

-	_, err = s.notifyForkchoiceUpdate(ctx, &notifyForkchoiceUpdateArg{
-		headState: headState,
-		headRoot:  newHeadRoot,
-		headBlock: headBlock.Block(),
-	})
-	if err != nil {
-		return false, errors.Wrap(err, "could not notify forkchoice update")
-	}
-
-	if err := s.saveHead(ctx, newHeadRoot, headBlock, headState); err != nil {
+	if err := s.saveHead(ctx, args.headRoot, args.headBlock, args.headState); err != nil {
 		log.WithError(err).Error("could not save head")
 	}

 	// Only need to prune attestations from pool if the head has changed.
-	if err := s.pruneAttsFromPool(headBlock); err != nil {
+	if err := s.pruneAttsFromPool(args.headBlock); err != nil {
 		log.WithError(err).Error("could not prune attestations from pool")
 	}
-	return true, nil
+	return nil
 }

 // shouldOverrideFCU checks whether the incoming block is still subject to being
--- a/beacon-chain/blockchain/forkchoice_update_execution_test.go
+++ b/beacon-chain/blockchain/forkchoice_update_execution_test.go
@@ -17,15 +17,6 @@ import (
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

-func TestService_isNewProposer(t *testing.T) {
-	beaconDB := testDB.SetupDB(t)
-	service := setupBeaconChain(t, beaconDB)
-	require.Equal(t, false, service.isNewProposer(service.CurrentSlot()+1))
-
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(service.CurrentSlot()+1, 0, [8]byte{}, [32]byte{} /* root */)
-	require.Equal(t, true, service.isNewProposer(service.CurrentSlot()+1))
-}
-
 func TestService_isNewHead(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
@@ -67,33 +58,14 @@ func TestService_getHeadStateAndBlock(t *testing.T) {
 }

 func TestService_forkchoiceUpdateWithExecution_exceptionalCases(t *testing.T) {
-	hook := logTest.NewGlobal()
 	ctx := context.Background()
 	opts := testServiceOptsWithDB(t)

 	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)
-	service.cfg.ProposerSlotIndexCache = cache.NewProposerPayloadIDsCache()
-	_, err = service.forkchoiceUpdateWithExecution(ctx, service.headRoot(), service.CurrentSlot()+1)
-	require.NoError(t, err)
-	hookErr := "could not notify forkchoice update"
-	invalidStateErr := "could not get state summary: could not find block in DB"
-	require.LogsDoNotContain(t, hook, invalidStateErr)
-	require.LogsDoNotContain(t, hook, hookErr)
-	gb, err := blocks.NewSignedBeaconBlock(util.NewBeaconBlock())
-	require.NoError(t, err)
-	require.NoError(t, service.saveInitSyncBlock(ctx, [32]byte{'a'}, gb))
-	_, err = service.forkchoiceUpdateWithExecution(ctx, [32]byte{'a'}, service.CurrentSlot()+1)
-	require.NoError(t, err)
-	require.LogsContain(t, hook, invalidStateErr)
+	service.cfg.PayloadIDCache = cache.NewPayloadIDCache()
+	service.cfg.TrackedValidatorsCache = cache.NewTrackedValidatorsCache()

-	hook.Reset()
-	service.head = &head{
-		root:  [32]byte{'a'},
-		block: nil, /* should not panic if notify head uses correct head */
-	}
-
-	// Block in Cache
 	b := util.NewBeaconBlock()
 	b.Block.Slot = 2
 	wsb, err := blocks.NewSignedBeaconBlock(b)
@@ -107,13 +79,7 @@ func TestService_forkchoiceUpdateWithExecution_exceptionalCases(t *testing.T) {
 		block: wsb,
 		state: st,
 	}
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(2, 1, [8]byte{1}, [32]byte{2})
-	_, err = service.forkchoiceUpdateWithExecution(ctx, r1, service.CurrentSlot())
-	require.NoError(t, err)
-	require.LogsDoNotContain(t, hook, invalidStateErr)
-	require.LogsDoNotContain(t, hook, hookErr)
-
-	// Block in DB
+	service.cfg.PayloadIDCache.Set(2, [32]byte{2}, [8]byte{1})
 	b = util.NewBeaconBlock()
 	b.Block.Slot = 3
 	util.SaveBlock(t, ctx, service.cfg.BeaconDB, b)
@@ -125,25 +91,22 @@ func TestService_forkchoiceUpdateWithExecution_exceptionalCases(t *testing.T) {
 		block: wsb,
 		state: st,
 	}
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(2, 1, [8]byte{1}, [32]byte{2})
-	_, err = service.forkchoiceUpdateWithExecution(ctx, r1, service.CurrentSlot()+1)
-	require.NoError(t, err)
-	require.LogsDoNotContain(t, hook, invalidStateErr)
-	require.LogsDoNotContain(t, hook, hookErr)
-	vId, payloadID, has := service.cfg.ProposerSlotIndexCache.GetProposerPayloadIDs(2, [32]byte{2})
-	require.Equal(t, true, has)
-	require.Equal(t, primitives.ValidatorIndex(1), vId)
-	require.Equal(t, [8]byte{1}, payloadID)
+	service.cfg.PayloadIDCache.Set(2, [32]byte{2}, [8]byte{1})
+	args := &fcuConfig{
+		headState:     st,
+		headRoot:      r1,
+		headBlock:     wsb,
+		proposingSlot: service.CurrentSlot() + 1,
+	}
+	require.NoError(t, service.forkchoiceUpdateWithExecution(ctx, args))

-	// Test zero headRoot returns immediately.
-	headRoot := service.headRoot()
-	_, err = service.forkchoiceUpdateWithExecution(ctx, [32]byte{}, service.CurrentSlot()+1)
-	require.NoError(t, err)
-	require.Equal(t, service.headRoot(), headRoot)
+	payloadID, has := service.cfg.PayloadIDCache.PayloadID(2, [32]byte{2})
+	require.Equal(t, true, has)
+	require.Equal(t, primitives.PayloadID{1}, payloadID)
 }

 func TestService_forkchoiceUpdateWithExecution_SameHeadRootNewProposer(t *testing.T) {
-	service, tr := minimalTestService(t)
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

 	altairBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockAltair())
@@ -182,10 +145,14 @@ func TestService_forkchoiceUpdateWithExecution_SameHeadRootNewProposer(t *testin
 	service.head.root = r
 	service.head.block = sb
 	service.head.state = st
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(service.CurrentSlot()+1, 0, [8]byte{}, [32]byte{} /* root */)
-	_, err = service.forkchoiceUpdateWithExecution(ctx, r, service.CurrentSlot()+1)
-	require.NoError(t, err)
-
+	service.cfg.PayloadIDCache.Set(service.CurrentSlot()+1, [32]byte{} /* root */, [8]byte{})
+	args := &fcuConfig{
+		headState:     st,
+		headBlock:     sb,
+		headRoot:      r,
+		proposingSlot: service.CurrentSlot() + 1,
+	}
+	require.NoError(t, service.forkchoiceUpdateWithExecution(ctx, args))
 }

 func TestShouldOverrideFCU(t *testing.T) {
--- a/beacon-chain/blockchain/kzg/BUILD.bazel
+++ b/beacon-chain/blockchain/kzg/BUILD.bazel
@@ -11,7 +11,6 @@ go_library(
    visibility = ["//visibility:public"],
    deps = [
        "//consensus-types/blocks:go_default_library",
-        "//proto/prysm/v1alpha1:go_default_library",
        "@com_github_crate_crypto_go_kzg_4844//:go_default_library",
        "@com_github_pkg_errors//:go_default_library",
    ],
@@ -25,7 +24,7 @@ go_test(
    ],
    embed = [":go_default_library"],
    deps = [
-        "//proto/prysm/v1alpha1:go_default_library",
+        "//consensus-types/blocks:go_default_library",
        "//testing/require:go_default_library",
        "@com_github_consensys_gnark_crypto//ecc/bls12-381/fr:go_default_library",
        "@com_github_crate_crypto_go_kzg_4844//:go_default_library",
--- a/beacon-chain/blockchain/kzg/validation.go
+++ b/beacon-chain/blockchain/kzg/validation.go
@@ -1,42 +1,32 @@
 package kzg

 import (
-	"fmt"
-
 	GoKZG "github.com/crate-crypto/go-kzg-4844"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
-	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
 )

-// IsDataAvailable checks that
-// - all blobs in the block are available
-// - Expected KZG commitments match the number of blobs in the block
-// - That the number of proofs match the number of blobs
-// - That the proofs are verified against the KZG commitments
-func IsDataAvailable(commitments [][]byte, sidecars []*ethpb.DeprecatedBlobSidecar) error {
-	if len(commitments) != len(sidecars) {
-		return fmt.Errorf("could not check data availability, expected %d commitments, obtained %d",
-			len(commitments), len(sidecars))
-	}
-	if len(commitments) == 0 {
+// Verify performs single or batch verification of commitments depending on the number of given BlobSidecars.
+func Verify(sidecars ...blocks.ROBlob) error {
+	if len(sidecars) == 0 {
 		return nil
 	}
-	blobs := make([]GoKZG.Blob, len(commitments))
-	proofs := make([]GoKZG.KZGProof, len(commitments))
-	cmts := make([]GoKZG.KZGCommitment, len(commitments))
+	if len(sidecars) == 1 {
+		return kzgContext.VerifyBlobKZGProof(
+			bytesToBlob(sidecars[0].Blob),
+			bytesToCommitment(sidecars[0].KzgCommitment),
+			bytesToKZGProof(sidecars[0].KzgProof))
+	}
+	blobs := make([]GoKZG.Blob, len(sidecars))
+	cmts := make([]GoKZG.KZGCommitment, len(sidecars))
+	proofs := make([]GoKZG.KZGProof, len(sidecars))
 	for i, sidecar := range sidecars {
 		blobs[i] = bytesToBlob(sidecar.Blob)
+		cmts[i] = bytesToCommitment(sidecar.KzgCommitment)
 		proofs[i] = bytesToKZGProof(sidecar.KzgProof)
-		cmts[i] = bytesToCommitment(commitments[i])
 	}
 	return kzgContext.VerifyBlobKZGProofBatch(blobs, cmts, proofs)
 }

-// VerifyROBlobCommitment is a helper that massages the fields of an ROBlob into the types needed to call VerifyBlobKZGProof.
-func VerifyROBlobCommitment(sc blocks.ROBlob) error {
-	return kzgContext.VerifyBlobKZGProof(bytesToBlob(sc.Blob), bytesToCommitment(sc.KzgCommitment), bytesToKZGProof(sc.KzgProof))
-}
-
 func bytesToBlob(blob []byte) (ret GoKZG.Blob) {
 	copy(ret[:], blob)
 	return
--- a/beacon-chain/blockchain/kzg/validation_test.go
+++ b/beacon-chain/blockchain/kzg/validation_test.go
@@ -8,7 +8,7 @@ import (

 	"github.com/consensys/gnark-crypto/ecc/bls12-381/fr"
 	GoKZG "github.com/crate-crypto/go-kzg-4844"
-	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
 	"github.com/prysmaticlabs/prysm/v4/testing/require"
 	"github.com/sirupsen/logrus"
 )
@@ -58,10 +58,9 @@ func GenerateCommitmentAndProof(blob GoKZG.Blob) (GoKZG.KZGCommitment, GoKZG.KZG
 	return commitment, proof, err
 }

-func TestIsDataAvailable(t *testing.T) {
-	sidecars := make([]*ethpb.DeprecatedBlobSidecar, 0)
-	commitments := make([][]byte, 0)
-	require.NoError(t, IsDataAvailable(commitments, sidecars))
+func TestVerify(t *testing.T) {
+	sidecars := make([]blocks.ROBlob, 0)
+	require.NoError(t, Verify(sidecars...))
 }

 func TestBytesToAny(t *testing.T) {
--- a/beacon-chain/blockchain/metrics.go
+++ b/beacon-chain/blockchain/metrics.go
@@ -358,6 +358,7 @@ func reportEpochMetrics(ctx context.Context, postState, headState state.BeaconSt
 	for name, val := range refMap {
 		stateTrieReferences.WithLabelValues(name).Set(float64(val))
 	}
+	postState.RecordStateMetrics()

 	return nil
 }
--- a/beacon-chain/blockchain/options.go
+++ b/beacon-chain/blockchain/options.go
@@ -69,10 +69,18 @@ func WithDepositCache(c cache.DepositCache) Option {
 	}
 }

-// WithProposerIdsCache for proposer id cache.
-func WithProposerIdsCache(c *cache.ProposerPayloadIDsCache) Option {
+// WithPayloadIDCache for payload ID cache.
+func WithPayloadIDCache(c *cache.PayloadIDCache) Option {
 	return func(s *Service) error {
-		s.cfg.ProposerSlotIndexCache = c
+		s.cfg.PayloadIDCache = c
+		return nil
+	}
+}
+
+// WithTrackedValidatorsCache for tracked validators cache.
+func WithTrackedValidatorsCache(c *cache.TrackedValidatorsCache) Option {
+	return func(s *Service) error {
+		s.cfg.TrackedValidatorsCache = c
 		return nil
 	}
 }
--- a/beacon-chain/blockchain/process_block.go
+++ b/beacon-chain/blockchain/process_block.go
@@ -6,12 +6,15 @@ import (
 	"time"

 	"github.com/pkg/errors"
+	"go.opencensus.io/trace"
+
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/v4/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
 	coreTime "github.com/prysmaticlabs/prysm/v4/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/das"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db/filesystem"
 	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
@@ -28,8 +31,6 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1/attestation"
 	"github.com/prysmaticlabs/prysm/v4/runtime/version"
 	"github.com/prysmaticlabs/prysm/v4/time/slots"
-	"github.com/sirupsen/logrus"
-	"go.opencensus.io/trace"
 )

 // A custom slot deadline for processing state slots in our cache.
@@ -41,106 +42,71 @@ const depositDeadline = 20 * time.Second
 // This defines size of the upper bound for initial sync block cache.
 var initialSyncBlockCacheSize = uint64(2 * params.BeaconConfig().SlotsPerEpoch)

+// postBlockProcessConfig is a structure that contains the data needed to
+// process the beacon block after validating the state transition function
+type postBlockProcessConfig struct {
+	ctx            context.Context
+	signed         interfaces.ReadOnlySignedBeaconBlock
+	blockRoot      [32]byte
+	headRoot       [32]byte
+	postState      state.BeaconState
+	isValidPayload bool
+}
+
 // postBlockProcess is called when a gossip block is received. This function performs
 // several duties most importantly informing the engine if head was updated,
 // saving the new head information to the blockchain package and
 // handling attestations, slashings and similar included in the block.
-func (s *Service) postBlockProcess(ctx context.Context, signed interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte, postState state.BeaconState, isValidPayload bool) error {
-	ctx, span := trace.StartSpan(ctx, "blockChain.onBlock")
+func (s *Service) postBlockProcess(cfg *postBlockProcessConfig) error {
+	ctx, span := trace.StartSpan(cfg.ctx, "blockChain.onBlock")
 	defer span.End()
-	if err := consensusblocks.BeaconBlockIsNil(signed); err != nil {
+	cfg.ctx = ctx
+	if err := consensusblocks.BeaconBlockIsNil(cfg.signed); err != nil {
 		return invalidBlock{error: err}
 	}
 	startTime := time.Now()
-	b := signed.Block()
+	fcuArgs := &fcuConfig{}

-	if err := s.cfg.ForkChoiceStore.InsertNode(ctx, postState, blockRoot); err != nil {
-		return errors.Wrapf(err, "could not insert block %d to fork choice store", signed.Block().Slot())
+	if s.inRegularSync() {
+		defer s.handleSecondFCUCall(cfg, fcuArgs)
 	}
-	if err := s.handleBlockAttestations(ctx, signed.Block(), postState); err != nil {
+	defer s.sendLightClientFeeds(cfg)
+	defer s.sendStateFeedOnBlock(cfg)
+	defer reportProcessingTime(startTime)
+	defer reportAttestationInclusion(cfg.signed.Block())
+
+	err := s.cfg.ForkChoiceStore.InsertNode(ctx, cfg.postState, cfg.blockRoot)
+	if err != nil {
+		return errors.Wrapf(err, "could not insert block %d to fork choice store", cfg.signed.Block().Slot())
+	}
+	if err := s.handleBlockAttestations(ctx, cfg.signed.Block(), cfg.postState); err != nil {
 		return errors.Wrap(err, "could not handle block's attestations")
 	}

-	s.InsertSlashingsToForkChoiceStore(ctx, signed.Block().Body().AttesterSlashings())
-	if isValidPayload {
-		if err := s.cfg.ForkChoiceStore.SetOptimisticToValid(ctx, blockRoot); err != nil {
+	s.InsertSlashingsToForkChoiceStore(ctx, cfg.signed.Block().Body().AttesterSlashings())
+	if cfg.isValidPayload {
+		if err := s.cfg.ForkChoiceStore.SetOptimisticToValid(ctx, cfg.blockRoot); err != nil {
 			return errors.Wrap(err, "could not set optimistic block to valid")
 		}
 	}
-
 	start := time.Now()
-	headRoot, err := s.cfg.ForkChoiceStore.Head(ctx)
+	cfg.headRoot, err = s.cfg.ForkChoiceStore.Head(ctx)
 	if err != nil {
 		log.WithError(err).Warn("Could not update head")
 	}
-	if blockRoot != headRoot {
-		receivedWeight, err := s.cfg.ForkChoiceStore.Weight(blockRoot)
-		if err != nil {
-			log.WithField("root", fmt.Sprintf("%#x", blockRoot)).Warn("could not determine node weight")
-		}
-		headWeight, err := s.cfg.ForkChoiceStore.Weight(headRoot)
-		if err != nil {
-			log.WithField("root", fmt.Sprintf("%#x", headRoot)).Warn("could not determine node weight")
-		}
-		log.WithFields(logrus.Fields{
-			"receivedRoot":   fmt.Sprintf("%#x", blockRoot),
-			"receivedWeight": receivedWeight,
-			"headRoot":       fmt.Sprintf("%#x", headRoot),
-			"headWeight":     headWeight,
-		}).Debug("Head block is not the received block")
-	}
 	newBlockHeadElapsedTime.Observe(float64(time.Since(start).Milliseconds()))
-
-	// verify conditions for FCU, notifies FCU, and saves the new head.
-	// This function also prunes attestations, other similar operations happen in prunePostBlockOperationPools.
-	if _, err := s.forkchoiceUpdateWithExecution(ctx, headRoot, s.CurrentSlot()+1); err != nil {
-		return err
+	if cfg.headRoot != cfg.blockRoot {
+		s.logNonCanonicalBlockReceived(cfg.blockRoot, cfg.headRoot)
+		return nil
+	}
+	if err := s.getFCUArgs(cfg, fcuArgs); err != nil {
+		log.WithError(err).Error("Could not get forkchoice update argument")
+		return nil
+	}
+	if err := s.sendFCU(cfg, fcuArgs); err != nil {
+		return errors.Wrap(err, "could not send FCU to engine")
 	}

-	optimistic, err := s.cfg.ForkChoiceStore.IsOptimistic(blockRoot)
-	if err != nil {
-		log.WithError(err).Debug("Could not check if block is optimistic")
-		optimistic = true
-	}
-
-	// Send notification of the processed block to the state feed.
-	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
-		Type: statefeed.BlockProcessed,
-		Data: &statefeed.BlockProcessedData{
-			Slot:        signed.Block().Slot(),
-			BlockRoot:   blockRoot,
-			SignedBlock: signed,
-			Verified:    true,
-			Optimistic:  optimistic,
-		},
-	})
-
-	defer reportAttestationInclusion(b)
-	if headRoot == blockRoot {
-		// Updating next slot state cache can happen in the background
-		// except in the epoch boundary in which case we lock to handle
-		// the shuffling and proposer caches updates.
-		// We handle these caches only on canonical
-		// blocks, otherwise this will be handled by lateBlockTasks
-		slot := postState.Slot()
-		if slots.IsEpochEnd(slot) {
-			if err := transition.UpdateNextSlotCache(ctx, blockRoot[:], postState); err != nil {
-				return errors.Wrap(err, "could not update next slot state cache")
-			}
-			if err := s.handleEpochBoundary(ctx, slot, postState, blockRoot[:]); err != nil {
-				return errors.Wrap(err, "could not handle epoch boundary")
-			}
-		} else {
-			go func() {
-				slotCtx, cancel := context.WithTimeout(context.Background(), slotDeadline)
-				defer cancel()
-				if err := transition.UpdateNextSlotCache(slotCtx, blockRoot[:], postState); err != nil {
-					log.WithError(err).Error("could not update next slot state cache")
-				}
-			}()
-		}
-	}
-	onBlockProcessingTime.Observe(float64(time.Since(startTime).Milliseconds()))
 	return nil
 }

@@ -162,7 +128,7 @@ func getStateVersionAndPayload(st state.BeaconState) (int, interfaces.ExecutionD
 	return preStateVersion, preStateHeader, nil
 }

-func (s *Service) onBlockBatch(ctx context.Context, blks []consensusblocks.ROBlock) error {
+func (s *Service) onBlockBatch(ctx context.Context, blks []consensusblocks.ROBlock, avs das.AvailabilityStore) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onBlockBatch")
 	defer span.End()

@@ -265,8 +231,8 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []consensusblocks.ROBlo
 				return err
 			}
 		}
-		if err := s.databaseDACheck(ctx, b); err != nil {
-			return errors.Wrap(err, "could not validate blob data availability")
+		if err := avs.IsDataAvailable(ctx, s.CurrentSlot(), b); err != nil {
+			return errors.Wrapf(err, "could not validate blob data availability at slot %d", b.Block().Slot())
 		}
 		args := &forkchoicetypes.BlockAndCheckpoints{Block: b.Block(),
 			JustifiedCheckpoint: jCheckpoints[i],
@@ -322,10 +288,10 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []consensusblocks.ROBlo
 			return errors.Wrap(err, "could not set optimistic block to valid")
 		}
 	}
-	arg := &notifyForkchoiceUpdateArg{
+	arg := &fcuConfig{
 		headState: preState,
 		headRoot:  lastBR,
-		headBlock: lastB.Block(),
+		headBlock: lastB,
 	}
 	if _, err := s.notifyForkchoiceUpdate(ctx, arg); err != nil {
 		return err
@@ -333,37 +299,6 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []consensusblocks.ROBlo
 	return s.saveHeadNoDB(ctx, lastB, lastBR, preState, !isValidPayload)
 }

-func commitmentsToCheck(b consensusblocks.ROBlock, current primitives.Slot) [][]byte {
-	if b.Version() < version.Deneb {
-		return nil
-	}
-	// We are only required to check within MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS
-	if !params.WithinDAPeriod(slots.ToEpoch(b.Block().Slot()), slots.ToEpoch(current)) {
-		return nil
-	}
-	kzgCommitments, err := b.Block().Body().BlobKzgCommitments()
-	if err != nil {
-		return nil
-	}
-	return kzgCommitments
-}
-
-func (s *Service) databaseDACheck(ctx context.Context, b consensusblocks.ROBlock) error {
-	commitments := commitmentsToCheck(b, s.CurrentSlot())
-	if len(commitments) == 0 {
-		return nil
-	}
-	missing, err := missingIndices(s.blobStorage, b.Root(), commitments)
-	if err != nil {
-		return err
-	}
-	if len(missing) == 0 {
-		return nil
-	}
-	// TODO: don't worry that this error isn't informative, it will be superceded by a detailed sidecar cache error.
-	return errors.New("not all kzg commitments are available")
-}
-
 func (s *Service) updateEpochBoundaryCaches(ctx context.Context, st state.BeaconState) error {
 	e := coreTime.CurrentEpoch(st)
 	if err := helpers.UpdateCommitteeCache(ctx, st, e); err != nil {
@@ -381,9 +316,6 @@ func (s *Service) updateEpochBoundaryCaches(ctx context.Context, st state.Beacon
 		if err := helpers.UpdateCommitteeCache(slotCtx, st, e+1); err != nil {
 			log.WithError(err).Warn("Could not update committee cache")
 		}
-		if err := helpers.UpdateUnsafeProposerIndicesInCache(slotCtx, st, e+1); err != nil {
-			log.WithError(err).Warn("Failed to cache next epoch proposers")
-		}
 	}()
 	// The latest block header is from the previous epoch
 	r, err := st.LatestBlockHeader().HashTreeRoot()
@@ -393,7 +325,10 @@ func (s *Service) updateEpochBoundaryCaches(ctx context.Context, st state.Beacon
 	}
 	// The proposer indices cache takes the target root for the previous
 	// epoch as key
-	target, err := s.cfg.ForkChoiceStore.TargetRootForEpoch(r, e-1)
+	if e > 0 {
+		e = e - 1
+	}
+	target, err := s.cfg.ForkChoiceStore.TargetRootForEpoch(r, e)
 	if err != nil {
 		log.WithError(err).Error("could not update proposer index state-root map")
 		return nil
@@ -650,10 +585,15 @@ func (s *Service) lateBlockTasks(ctx context.Context) {
 	if s.CurrentSlot() == s.HeadSlot() {
 		return
 	}
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	// return early if we are in init sync
+	if !s.inRegularSync() {
+		return
+	}
 	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 		Type: statefeed.MissedSlot,
 	})
-
 	s.headLock.RLock()
 	headRoot := s.headRoot()
 	headState := s.headState(ctx)
@@ -668,16 +608,19 @@ func (s *Service) lateBlockTasks(ctx context.Context) {
 	if err := transition.UpdateNextSlotCache(ctx, lastRoot, lastState); err != nil {
 		log.WithError(err).Debug("could not update next slot state cache")
 	}
-	// handleEpochBoundary requires a forkchoice lock to obtain the target root.
-	s.cfg.ForkChoiceStore.RLock()
 	if err := s.handleEpochBoundary(ctx, currentSlot, headState, headRoot[:]); err != nil {
 		log.WithError(err).Error("lateBlockTasks: could not update epoch boundary caches")
 	}
-	s.cfg.ForkChoiceStore.RUnlock()
-	// Head root should be empty when retrieving proposer index for the next slot.
-	_, id, has := s.cfg.ProposerSlotIndexCache.GetProposerPayloadIDs(s.CurrentSlot()+1, [32]byte{} /* head root */)
-	// There exists proposer for next slot, but we haven't called fcu w/ payload attribute yet.
-	if (!has && !features.Get().PrepareAllPayloads) || id != [8]byte{} {
+	// return early if we already started building a block for the current
+	// head root
+	_, has := s.cfg.PayloadIDCache.PayloadID(s.CurrentSlot()+1, headRoot)
+	if has {
+		return
+	}
+
+	attribute := s.getPayloadAttribute(ctx, headState, s.CurrentSlot()+1, headRoot[:])
+	// return early if we are not proposing next slot
+	if attribute.IsEmpty() {
 		return
 	}

@@ -689,13 +632,14 @@ func (s *Service) lateBlockTasks(ctx context.Context) {
 		return
 	}
 	s.headLock.RUnlock()
-	s.cfg.ForkChoiceStore.RLock()
-	_, err = s.notifyForkchoiceUpdate(ctx, &notifyForkchoiceUpdateArg{
-		headState: headState,
-		headRoot:  headRoot,
-		headBlock: headBlock.Block(),
-	})
-	s.cfg.ForkChoiceStore.RUnlock()
+
+	fcuArgs := &fcuConfig{
+		headState:  headState,
+		headRoot:   headRoot,
+		headBlock:  headBlock,
+		attributes: attribute,
+	}
+	_, err = s.notifyForkchoiceUpdate(ctx, fcuArgs)
 	if err != nil {
 		log.WithError(err).Debug("could not perform late block tasks: failed to update forkchoice with engine")
 	}
--- a/beacon-chain/blockchain/process_block_helpers.go
+++ b/beacon-chain/blockchain/process_block_helpers.go
@@ -3,21 +3,28 @@ package blockchain
 import (
 	"context"
 	"fmt"
+	"time"

 	"github.com/ethereum/go-ethereum/common"
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"go.opencensus.io/trace"
+
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/feed"
+	statefeed "github.com/prysmaticlabs/prysm/v4/beacon-chain/core/feed/state"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
 	doublylinkedtree "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/doubly-linked-tree"
 	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/config/features"
 	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
 	mathutil "github.com/prysmaticlabs/prysm/v4/math"
+	ethpbv2 "github.com/prysmaticlabs/prysm/v4/proto/eth/v2"
 	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v4/time"
 	"github.com/prysmaticlabs/prysm/v4/time/slots"
-	"go.opencensus.io/trace"
 )

 // CurrentSlot returns the current slot based on time.
@@ -25,6 +32,252 @@ func (s *Service) CurrentSlot() primitives.Slot {
 	return slots.CurrentSlot(uint64(s.genesisTime.Unix()))
 }

+// getFCUArgs returns the arguments to call forkchoice update
+func (s *Service) getFCUArgs(cfg *postBlockProcessConfig, fcuArgs *fcuConfig) error {
+	if err := s.getFCUArgsEarlyBlock(cfg, fcuArgs); err != nil {
+		return err
+	}
+	if !s.inRegularSync() {
+		return nil
+	}
+	slot := cfg.signed.Block().Slot()
+	if slots.WithinVotingWindow(uint64(s.genesisTime.Unix()), slot) {
+		return nil
+	}
+	return s.computePayloadAttributes(cfg, fcuArgs)
+}
+
+func (s *Service) getFCUArgsEarlyBlock(cfg *postBlockProcessConfig, fcuArgs *fcuConfig) error {
+	if cfg.blockRoot == cfg.headRoot {
+		fcuArgs.headState = cfg.postState
+		fcuArgs.headBlock = cfg.signed
+		fcuArgs.headRoot = cfg.headRoot
+		fcuArgs.proposingSlot = s.CurrentSlot() + 1
+		return nil
+	}
+	return s.fcuArgsNonCanonicalBlock(cfg, fcuArgs)
+}
+
+// logNonCanonicalBlockReceived prints a message informing that the received
+// block is not the head of the chain. It requires the caller holds a lock on
+// Foprkchoice.
+func (s *Service) logNonCanonicalBlockReceived(blockRoot [32]byte, headRoot [32]byte) {
+	receivedWeight, err := s.cfg.ForkChoiceStore.Weight(blockRoot)
+	if err != nil {
+		log.WithField("root", fmt.Sprintf("%#x", blockRoot)).Warn("could not determine node weight")
+	}
+	headWeight, err := s.cfg.ForkChoiceStore.Weight(headRoot)
+	if err != nil {
+		log.WithField("root", fmt.Sprintf("%#x", headRoot)).Warn("could not determine node weight")
+	}
+	log.WithFields(logrus.Fields{
+		"receivedRoot":   fmt.Sprintf("%#x", blockRoot),
+		"receivedWeight": receivedWeight,
+		"headRoot":       fmt.Sprintf("%#x", headRoot),
+		"headWeight":     headWeight,
+	}).Debug("Head block is not the received block")
+}
+
+// fcuArgsNonCanonicalBlock returns the arguments to the FCU call when the
+// incoming block is non-canonical, that is, based on the head root.
+func (s *Service) fcuArgsNonCanonicalBlock(cfg *postBlockProcessConfig, fcuArgs *fcuConfig) error {
+	headState, headBlock, err := s.getStateAndBlock(cfg.ctx, cfg.headRoot)
+	if err != nil {
+		return err
+	}
+	fcuArgs.headState = headState
+	fcuArgs.headBlock = headBlock
+	fcuArgs.headRoot = cfg.headRoot
+	fcuArgs.proposingSlot = s.CurrentSlot() + 1
+	return nil
+}
+
+// sendStateFeedOnBlock sends an event that a new block has been synced
+func (s *Service) sendStateFeedOnBlock(cfg *postBlockProcessConfig) {
+	optimistic, err := s.cfg.ForkChoiceStore.IsOptimistic(cfg.blockRoot)
+	if err != nil {
+		log.WithError(err).Debug("Could not check if block is optimistic")
+		optimistic = true
+	}
+	// Send notification of the processed block to the state feed.
+	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.BlockProcessed,
+		Data: &statefeed.BlockProcessedData{
+			Slot:        cfg.signed.Block().Slot(),
+			BlockRoot:   cfg.blockRoot,
+			SignedBlock: cfg.signed,
+			Verified:    true,
+			Optimistic:  optimistic,
+		},
+	})
+}
+
+// sendLightClientFeeds sends the light client feeds when feature flag is enabled.
+func (s *Service) sendLightClientFeeds(cfg *postBlockProcessConfig) {
+	if features.Get().EnableLightClient {
+		if _, err := s.sendLightClientOptimisticUpdate(cfg.ctx, cfg.signed, cfg.postState); err != nil {
+			log.WithError(err).Error("Failed to send light client optimistic update")
+		}
+
+		// Get the finalized checkpoint
+		finalized := s.ForkChoicer().FinalizedCheckpoint()
+
+		// LightClientFinalityUpdate needs super majority
+		s.tryPublishLightClientFinalityUpdate(cfg.ctx, cfg.signed, finalized, cfg.postState)
+	}
+}
+
+func (s *Service) tryPublishLightClientFinalityUpdate(ctx context.Context, signed interfaces.ReadOnlySignedBeaconBlock, finalized *forkchoicetypes.Checkpoint, postState state.BeaconState) {
+	if finalized.Epoch <= s.lastPublishedLightClientEpoch {
+		return
+	}
+
+	config := params.BeaconConfig()
+	if finalized.Epoch < config.AltairForkEpoch {
+		return
+	}
+
+	syncAggregate, err := signed.Block().Body().SyncAggregate()
+	if err != nil || syncAggregate == nil {
+		return
+	}
+
+	// LightClientFinalityUpdate needs super majority
+	if syncAggregate.SyncCommitteeBits.Count()*3 < config.SyncCommitteeSize*2 {
+		return
+	}
+
+	_, err = s.sendLightClientFinalityUpdate(ctx, signed, postState)
+	if err != nil {
+		log.WithError(err).Error("Failed to send light client finality update")
+	} else {
+		s.lastPublishedLightClientEpoch = finalized.Epoch
+	}
+}
+
+// sendLightClientFinalityUpdate sends a light client finality update notification to the state feed.
+func (s *Service) sendLightClientFinalityUpdate(ctx context.Context, signed interfaces.ReadOnlySignedBeaconBlock,
+	postState state.BeaconState) (int, error) {
+	// Get attested state
+	attestedRoot := signed.Block().ParentRoot()
+	attestedState, err := s.cfg.StateGen.StateByRoot(ctx, attestedRoot)
+	if err != nil {
+		return 0, errors.Wrap(err, "could not get attested state")
+	}
+
+	// Get finalized block
+	var finalizedBlock interfaces.ReadOnlySignedBeaconBlock
+	finalizedCheckPoint := attestedState.FinalizedCheckpoint()
+	if finalizedCheckPoint != nil {
+		finalizedRoot := bytesutil.ToBytes32(finalizedCheckPoint.Root)
+		finalizedBlock, err = s.cfg.BeaconDB.Block(ctx, finalizedRoot)
+		if err != nil {
+			finalizedBlock = nil
+		}
+	}
+
+	update, err := NewLightClientFinalityUpdateFromBeaconState(
+		ctx,
+		postState,
+		signed,
+		attestedState,
+		finalizedBlock,
+	)
+
+	if err != nil {
+		return 0, errors.Wrap(err, "could not create light client update")
+	}
+
+	// Return the result
+	result := &ethpbv2.LightClientFinalityUpdateWithVersion{
+		Version: ethpbv2.Version(signed.Version()),
+		Data:    CreateLightClientFinalityUpdate(update),
+	}
+
+	// Send event
+	return s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.LightClientFinalityUpdate,
+		Data: result,
+	}), nil
+}
+
+// sendLightClientOptimisticUpdate sends a light client optimistic update notification to the state feed.
+func (s *Service) sendLightClientOptimisticUpdate(ctx context.Context, signed interfaces.ReadOnlySignedBeaconBlock,
+	postState state.BeaconState) (int, error) {
+	// Get attested state
+	attestedRoot := signed.Block().ParentRoot()
+	attestedState, err := s.cfg.StateGen.StateByRoot(ctx, attestedRoot)
+	if err != nil {
+		return 0, errors.Wrap(err, "could not get attested state")
+	}
+
+	update, err := NewLightClientOptimisticUpdateFromBeaconState(
+		ctx,
+		postState,
+		signed,
+		attestedState,
+	)
+
+	if err != nil {
+		return 0, errors.Wrap(err, "could not create light client update")
+	}
+
+	// Return the result
+	result := &ethpbv2.LightClientOptimisticUpdateWithVersion{
+		Version: ethpbv2.Version(signed.Version()),
+		Data:    CreateLightClientOptimisticUpdate(update),
+	}
+
+	return s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.LightClientOptimisticUpdate,
+		Data: result,
+	}), nil
+}
+
+// updateCachesPostBlockProcessing updates the next slot cache and handles the epoch
+// boundary in order to compute the right proposer indices after processing
+// state transition. This function is called on late blocks while still locked,
+// before sending FCU to the engine.
+func (s *Service) updateCachesPostBlockProcessing(cfg *postBlockProcessConfig) error {
+	slot := cfg.postState.Slot()
+	if err := transition.UpdateNextSlotCache(cfg.ctx, cfg.blockRoot[:], cfg.postState); err != nil {
+		return errors.Wrap(err, "could not update next slot state cache")
+	}
+	if !slots.IsEpochEnd(slot) {
+		return nil
+	}
+	return s.handleEpochBoundary(cfg.ctx, slot, cfg.postState, cfg.blockRoot[:])
+}
+
+// handleSecondFCUCall handles a second call to FCU when syncing a new block.
+// This is useful when proposing in the next block and we want to defer the
+// computation of the next slot shuffling.
+func (s *Service) handleSecondFCUCall(cfg *postBlockProcessConfig, fcuArgs *fcuConfig) {
+	if (fcuArgs.attributes == nil || fcuArgs.attributes.IsEmpty()) && cfg.headRoot == cfg.blockRoot {
+		go s.sendFCUWithAttributes(cfg, fcuArgs)
+	}
+}
+
+// reportProcessingTime reports the metric of how long it took to process the
+// current block
+func reportProcessingTime(startTime time.Time) {
+	onBlockProcessingTime.Observe(float64(time.Since(startTime).Milliseconds()))
+}
+
+// computePayloadAttributes modifies the passed FCU arguments to
+// contain the right payload attributes with the tracked proposer. It gets
+// called on blocks that arrive after the attestation voting window, or in a
+// background routine after syncing early blocks.
+func (s *Service) computePayloadAttributes(cfg *postBlockProcessConfig, fcuArgs *fcuConfig) error {
+	if cfg.blockRoot == cfg.headRoot {
+		if err := s.updateCachesPostBlockProcessing(cfg); err != nil {
+			return err
+		}
+	}
+	fcuArgs.attributes = s.getPayloadAttribute(cfg.ctx, fcuArgs.headState, fcuArgs.proposingSlot, cfg.headRoot[:])
+	return nil
+}
+
 // getBlockPreState returns the pre state of an incoming block. It uses the parent root of the block
 // to retrieve the state in DB. It verifies the pre state's validity and the incoming block
 // is in the correct time window.
--- a/beacon-chain/blockchain/process_block_test.go
+++ b/beacon-chain/blockchain/process_block_test.go
@@ -1,7 +1,6 @@
 package blockchain

 import (
-	"bytes"
 	"context"
 	"fmt"
 	"math/big"
@@ -17,6 +16,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/signing"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/das"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db/filesystem"
 	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
@@ -40,7 +40,6 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/testing/require"
 	"github.com/prysmaticlabs/prysm/v4/testing/util"
 	prysmTime "github.com/prysmaticlabs/prysm/v4/time"
-	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

@@ -69,7 +68,7 @@ func TestStore_OnBlockBatch(t *testing.T) {
 		require.NoError(t, err)
 		blks = append(blks, rwsb)
 	}
-	err := service.onBlockBatch(ctx, blks)
+	err := service.onBlockBatch(ctx, blks, &das.MockAvailabilityStore{})
 	require.NoError(t, err)
 	jcp := service.CurrentJustifiedCheckpt()
 	jroot := bytesutil.ToBytes32(jcp.Root)
@@ -99,7 +98,7 @@ func TestStore_OnBlockBatch_NotifyNewPayload(t *testing.T) {
 		require.NoError(t, service.saveInitSyncBlock(ctx, rwsb.Root(), wsb))
 		blks = append(blks, rwsb)
 	}
-	require.NoError(t, service.onBlockBatch(ctx, blks))
+	require.NoError(t, service.onBlockBatch(ctx, blks, &das.MockAvailabilityStore{}))
 }

 func TestCachedPreState_CanGetFromStateSummary(t *testing.T) {
@@ -567,7 +566,7 @@ func TestOnBlock_CanFinalize_WithOnTick(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, r, wsb, postState))
-		require.NoError(t, service.postBlockProcess(ctx, wsb, r, postState, true))
+		require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, r, [32]byte{}, postState, true}))
 		require.NoError(t, service.updateJustificationOnBlock(ctx, preState, postState, currStoreJustifiedEpoch))
 		_, err = service.updateFinalizationOnBlock(ctx, preState, postState, currStoreFinalizedEpoch)
 		require.NoError(t, err)
@@ -615,7 +614,7 @@ func TestOnBlock_CanFinalize(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, r, wsb, postState))
-		require.NoError(t, service.postBlockProcess(ctx, wsb, r, postState, true))
+		require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, r, [32]byte{}, postState, true}))
 		require.NoError(t, service.updateJustificationOnBlock(ctx, preState, postState, currStoreJustifiedEpoch))
 		_, err = service.updateFinalizationOnBlock(ctx, preState, postState, currStoreFinalizedEpoch)
 		require.NoError(t, err)
@@ -641,7 +640,7 @@ func TestOnBlock_CanFinalize(t *testing.T) {

 func TestOnBlock_NilBlock(t *testing.T) {
 	service, tr := minimalTestService(t)
-	err := service.postBlockProcess(tr.ctx, nil, [32]byte{}, nil, true)
+	err := service.postBlockProcess(&postBlockProcessConfig{tr.ctx, nil, [32]byte{}, [32]byte{}, nil, true})
 	require.Equal(t, true, IsInvalidBlock(err))
 }

@@ -689,7 +688,7 @@ func TestOnBlock_CallNewPayloadAndForkchoiceUpdated(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, r, wsb, postState))
-		require.NoError(t, service.postBlockProcess(ctx, wsb, r, postState, false))
+		require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, r, [32]byte{}, postState, false}))
 		testState, err = service.cfg.StateGen.StateByRoot(ctx, r)
 		require.NoError(t, err)
 	}
@@ -895,7 +894,7 @@ func Test_validateMergeTransitionBlock(t *testing.T) {
 	cfg.TerminalBlockHash = params.BeaconConfig().ZeroHash
 	params.OverrideBeaconConfig(cfg)

-	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	service, tr := minimalTestService(t, WithPayloadIDCache(cache.NewPayloadIDCache()))
 	ctx := tr.ctx

 	aHash := common.BytesToHash([]byte("a"))
@@ -912,7 +911,6 @@ func Test_validateMergeTransitionBlock(t *testing.T) {
 			name:         "state older than Bellatrix, nil payload",
 			stateVersion: 1,
 			payload:      nil,
-			errString:    "attempted to wrap nil",
 		},
 		{
 			name:         "state older than Bellatrix, empty payload",
@@ -924,8 +922,10 @@ func Test_validateMergeTransitionBlock(t *testing.T) {
 				ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 				LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
 				PrevRandao:    make([]byte, fieldparams.RootLength),
+				ExtraData:     make([]byte, 0),
 				BaseFeePerGas: make([]byte, fieldparams.RootLength),
 				BlockHash:     make([]byte, fieldparams.RootLength),
+				Transactions:  make([][]byte, 0),
 			},
 		},
 		{
@@ -939,7 +939,6 @@ func Test_validateMergeTransitionBlock(t *testing.T) {
 			name:         "state is Bellatrix, nil payload",
 			stateVersion: 2,
 			payload:      nil,
-			errString:    "attempted to wrap nil",
 		},
 		{
 			name:         "state is Bellatrix, empty payload",
@@ -969,6 +968,7 @@ func Test_validateMergeTransitionBlock(t *testing.T) {
 					ReceiptsRoot:     make([]byte, fieldparams.RootLength),
 					LogsBloom:        make([]byte, fieldparams.LogsBloomLength),
 					PrevRandao:       make([]byte, fieldparams.RootLength),
+					ExtraData:        make([]byte, 0),
 					BaseFeePerGas:    make([]byte, fieldparams.RootLength),
 					BlockHash:        make([]byte, fieldparams.RootLength),
 					TransactionsRoot: make([]byte, fieldparams.RootLength),
@@ -1111,7 +1111,7 @@ func TestOnBlock_ProcessBlocksParallel(t *testing.T) {
 			postState, err := service.validateStateTransition(ctx, preState, wsb1)
 			require.NoError(t, err)
 			lock.Lock()
-			require.NoError(t, service.postBlockProcess(ctx, wsb1, r1, postState, true))
+			require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb1, r1, [32]byte{}, postState, true}))
 			lock.Unlock()
 			wg.Done()
 		}()
@@ -1121,7 +1121,7 @@ func TestOnBlock_ProcessBlocksParallel(t *testing.T) {
 			postState, err := service.validateStateTransition(ctx, preState, wsb2)
 			require.NoError(t, err)
 			lock.Lock()
-			require.NoError(t, service.postBlockProcess(ctx, wsb2, r2, postState, true))
+			require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb2, r2, [32]byte{}, postState, true}))
 			lock.Unlock()
 			wg.Done()
 		}()
@@ -1131,7 +1131,7 @@ func TestOnBlock_ProcessBlocksParallel(t *testing.T) {
 			postState, err := service.validateStateTransition(ctx, preState, wsb3)
 			require.NoError(t, err)
 			lock.Lock()
-			require.NoError(t, service.postBlockProcess(ctx, wsb3, r3, postState, true))
+			require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb3, r3, [32]byte{}, postState, true}))
 			lock.Unlock()
 			wg.Done()
 		}()
@@ -1141,7 +1141,7 @@ func TestOnBlock_ProcessBlocksParallel(t *testing.T) {
 			postState, err := service.validateStateTransition(ctx, preState, wsb4)
 			require.NoError(t, err)
 			lock.Lock()
-			require.NoError(t, service.postBlockProcess(ctx, wsb4, r4, postState, true))
+			require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb4, r4, [32]byte{}, postState, true}))
 			lock.Unlock()
 			wg.Done()
 		}()
@@ -1216,7 +1216,7 @@ func TestStore_NoViableHead_FCU(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		require.NoError(t, service.postBlockProcess(ctx, wsb, root, postState, false))
+		require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false}))
 	}

 	for i := 6; i < 12; i++ {
@@ -1234,7 +1234,7 @@ func TestStore_NoViableHead_FCU(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		err = service.postBlockProcess(ctx, wsb, root, postState, false)
+		err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false})
 		require.NoError(t, err)
 	}

@@ -1253,7 +1253,7 @@ func TestStore_NoViableHead_FCU(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		err = service.postBlockProcess(ctx, wsb, root, postState, false)
+		err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false})
 		require.NoError(t, err)
 	}
 	// Check that we haven't justified the second epoch yet
@@ -1275,7 +1275,7 @@ func TestStore_NoViableHead_FCU(t *testing.T) {
 	postState, err := service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, firstInvalidRoot, wsb, postState))
-	err = service.postBlockProcess(ctx, wsb, firstInvalidRoot, postState, false)
+	err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, firstInvalidRoot, [32]byte{}, postState, false})
 	require.NoError(t, err)
 	jc = service.cfg.ForkChoiceStore.JustifiedCheckpoint()
 	require.Equal(t, primitives.Epoch(2), jc.Epoch)
@@ -1303,7 +1303,7 @@ func TestStore_NoViableHead_FCU(t *testing.T) {
 	postState, err = service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-	err = service.postBlockProcess(ctx, wsb, root, postState, false)
+	err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false})
 	require.ErrorContains(t, "received an INVALID payload from execution engine", err)
 	// Check that forkchoice's head is the last invalid block imported. The
 	// store's headroot is the previous head (since the invalid block did
@@ -1332,7 +1332,7 @@ func TestStore_NoViableHead_FCU(t *testing.T) {
 	postState, err = service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-	err = service.postBlockProcess(ctx, wsb, root, postState, true)
+	err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, true})
 	require.NoError(t, err)
 	// Check the newly imported block is head, it justified the right
 	// checkpoint and the node is no longer optimistic
@@ -1394,7 +1394,7 @@ func TestStore_NoViableHead_NewPayload(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		require.NoError(t, service.postBlockProcess(ctx, wsb, root, postState, false))
+		require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false}))
 	}

 	for i := 6; i < 12; i++ {
@@ -1412,7 +1412,7 @@ func TestStore_NoViableHead_NewPayload(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		err = service.postBlockProcess(ctx, wsb, root, postState, false)
+		err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false})
 		require.NoError(t, err)
 	}

@@ -1432,7 +1432,7 @@ func TestStore_NoViableHead_NewPayload(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		err = service.postBlockProcess(ctx, wsb, root, postState, false)
+		err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false})
 		require.NoError(t, err)
 	}
 	// Check that we haven't justified the second epoch yet
@@ -1454,7 +1454,7 @@ func TestStore_NoViableHead_NewPayload(t *testing.T) {
 	postState, err := service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, firstInvalidRoot, wsb, postState))
-	err = service.postBlockProcess(ctx, wsb, firstInvalidRoot, postState, false)
+	err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, firstInvalidRoot, [32]byte{}, postState, false})
 	require.NoError(t, err)
 	jc = service.cfg.ForkChoiceStore.JustifiedCheckpoint()
 	require.Equal(t, primitives.Epoch(2), jc.Epoch)
@@ -1510,7 +1510,7 @@ func TestStore_NoViableHead_NewPayload(t *testing.T) {
 	postState, err = service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-	err = service.postBlockProcess(ctx, wsb, root, postState, true)
+	err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, true})
 	require.NoError(t, err)
 	// Check the newly imported block is head, it justified the right
 	// checkpoint and the node is no longer optimistic
@@ -1574,7 +1574,7 @@ func TestStore_NoViableHead_Liveness(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		require.NoError(t, service.postBlockProcess(ctx, wsb, root, postState, false))
+		require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false}))
 	}

 	for i := 6; i < 12; i++ {
@@ -1593,7 +1593,7 @@ func TestStore_NoViableHead_Liveness(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		err = service.postBlockProcess(ctx, wsb, root, postState, false)
+		err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false})
 		require.NoError(t, err)
 	}

@@ -1612,7 +1612,7 @@ func TestStore_NoViableHead_Liveness(t *testing.T) {
 	postState, err := service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, lastValidRoot, wsb, postState))
-	err = service.postBlockProcess(ctx, wsb, lastValidRoot, postState, false)
+	err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, lastValidRoot, [32]byte{}, postState, false})
 	require.NoError(t, err)
 	// save the post state and the payload Hash of this block since it will
 	// be the LVH
@@ -1639,7 +1639,7 @@ func TestStore_NoViableHead_Liveness(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, invalidRoots[i-13], wsb, postState))
-		err = service.postBlockProcess(ctx, wsb, invalidRoots[i-13], postState, false)
+		err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, invalidRoots[i-13], [32]byte{}, postState, false})
 		require.NoError(t, err)
 	}
 	// Check that we have justified the second epoch
@@ -1704,7 +1704,7 @@ func TestStore_NoViableHead_Liveness(t *testing.T) {
 	postState, err = service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-	require.NoError(t, service.postBlockProcess(ctx, wsb, root, postState, true))
+	require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, true}))
 	// Check that the head is still INVALID and the node is still optimistic
 	require.Equal(t, invalidHeadRoot, service.cfg.ForkChoiceStore.CachedHeadRoot())
 	optimistic, err = service.IsOptimistic(ctx)
@@ -1727,7 +1727,7 @@ func TestStore_NoViableHead_Liveness(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		err = service.postBlockProcess(ctx, wsb, root, postState, true)
+		err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, true})
 		require.NoError(t, err)
 		st, err = service.cfg.StateGen.StateByRoot(ctx, root)
 		require.NoError(t, err)
@@ -1753,7 +1753,7 @@ func TestStore_NoViableHead_Liveness(t *testing.T) {
 	postState, err = service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-	err = service.postBlockProcess(ctx, wsb, root, postState, true)
+	err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, true})
 	require.NoError(t, err)
 	require.Equal(t, root, service.cfg.ForkChoiceStore.CachedHeadRoot())
 	sjc = service.CurrentJustifiedCheckpt()
@@ -1809,7 +1809,7 @@ func TestNoViableHead_Reboot(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		require.NoError(t, service.postBlockProcess(ctx, wsb, root, postState, false))
+		require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false}))
 	}

 	for i := 6; i < 12; i++ {
@@ -1827,7 +1827,7 @@ func TestNoViableHead_Reboot(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		err = service.postBlockProcess(ctx, wsb, root, postState, false)
+		err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false})
 		require.NoError(t, err)
 	}

@@ -1846,7 +1846,7 @@ func TestNoViableHead_Reboot(t *testing.T) {
 	postState, err := service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, lastValidRoot, wsb, postState))
-	err = service.postBlockProcess(ctx, wsb, lastValidRoot, postState, false)
+	err = service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, lastValidRoot, [32]byte{}, postState, false})
 	require.NoError(t, err)
 	// save the post state and the payload Hash of this block since it will
 	// be the LVH
@@ -1875,7 +1875,7 @@ func TestNoViableHead_Reboot(t *testing.T) {
 		postState, err := service.validateStateTransition(ctx, preState, wsb)
 		require.NoError(t, err)
 		require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-		require.NoError(t, service.postBlockProcess(ctx, wsb, root, postState, false))
+		require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false}))
 		require.NoError(t, service.updateJustificationOnBlock(ctx, preState, postState, currStoreJustifiedEpoch))
 		_, err = service.updateFinalizationOnBlock(ctx, preState, postState, currStoreFinalizedEpoch)
 		require.NoError(t, err)
@@ -1946,7 +1946,7 @@ func TestNoViableHead_Reboot(t *testing.T) {
 	rwsb, err := consensusblocks.NewROBlock(wsb)
 	require.NoError(t, err)
 	// We use onBlockBatch here because the valid chain is missing in forkchoice
-	require.NoError(t, service.onBlockBatch(ctx, []consensusblocks.ROBlock{rwsb}))
+	require.NoError(t, service.onBlockBatch(ctx, []consensusblocks.ROBlock{rwsb}, &das.MockAvailabilityStore{}))
 	// Check that the head is now VALID and the node is not optimistic
 	require.Equal(t, genesisRoot, service.ensureRootNotZeros(service.cfg.ForkChoiceStore.CachedHeadRoot()))
 	headRoot, err = service.HeadRoot(ctx)
@@ -1990,7 +1990,7 @@ func TestOnBlock_HandleBlockAttestations(t *testing.T) {
 	postState, err := service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, root, wsb, postState))
-	require.NoError(t, service.postBlockProcess(ctx, wsb, root, postState, false))
+	require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, root, [32]byte{}, postState, false}))

 	st, err = service.HeadState(ctx)
 	require.NoError(t, err)
@@ -2045,78 +2045,10 @@ func TestFillMissingBlockPayloadId_PrepareAllPayloads(t *testing.T) {
 // Helper function to simulate the block being on time or delayed for proposer
 // boost. It alters the genesisTime tracked by the store.
 func driftGenesisTime(s *Service, slot, delay int64) {
-	offset := slot*int64(params.BeaconConfig().SecondsPerSlot) - delay
+	offset := slot*int64(params.BeaconConfig().SecondsPerSlot) + delay
 	s.SetGenesisTime(time.Unix(time.Now().Unix()-offset, 0))
 }

-func Test_commitmentsToCheck(t *testing.T) {
-	windowSlots, err := slots.EpochEnd(params.BeaconConfig().MinEpochsForBlobsSidecarsRequest)
-	require.NoError(t, err)
-	commits := [][]byte{
-		bytesutil.PadTo([]byte("a"), 48),
-		bytesutil.PadTo([]byte("b"), 48),
-		bytesutil.PadTo([]byte("c"), 48),
-		bytesutil.PadTo([]byte("d"), 48),
-	}
-	cases := []struct {
-		name    string
-		commits [][]byte
-		block   func(*testing.T) consensusblocks.ROBlock
-		slot    primitives.Slot
-	}{
-		{
-			name: "pre deneb",
-			block: func(t *testing.T) consensusblocks.ROBlock {
-				bb := util.NewBeaconBlockBellatrix()
-				sb, err := consensusblocks.NewSignedBeaconBlock(bb)
-				require.NoError(t, err)
-				rb, err := consensusblocks.NewROBlock(sb)
-				require.NoError(t, err)
-				return rb
-			},
-		},
-		{
-			name: "commitments within da",
-			block: func(t *testing.T) consensusblocks.ROBlock {
-				d := util.NewBeaconBlockDeneb()
-				d.Block.Body.BlobKzgCommitments = commits
-				d.Block.Slot = 100
-				sb, err := consensusblocks.NewSignedBeaconBlock(d)
-				require.NoError(t, err)
-				rb, err := consensusblocks.NewROBlock(sb)
-				require.NoError(t, err)
-				return rb
-			},
-			commits: commits,
-			slot:    100,
-		},
-		{
-			name: "commitments outside da",
-			block: func(t *testing.T) consensusblocks.ROBlock {
-				d := util.NewBeaconBlockDeneb()
-				// block is from slot 0, "current slot" is window size +1 (so outside the window)
-				d.Block.Body.BlobKzgCommitments = commits
-				sb, err := consensusblocks.NewSignedBeaconBlock(d)
-				require.NoError(t, err)
-				rb, err := consensusblocks.NewROBlock(sb)
-				require.NoError(t, err)
-				return rb
-			},
-			slot: windowSlots + 1,
-		},
-	}
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			b := c.block(t)
-			co := commitmentsToCheck(b, c.slot)
-			require.Equal(t, len(c.commits), len(co))
-			for i := 0; i < len(c.commits); i++ {
-				require.Equal(t, true, bytes.Equal(c.commits[i], co[i]))
-			}
-		})
-	}
-}
-
 func TestMissingIndices(t *testing.T) {
 	cases := []struct {
 		name     string
@@ -2197,6 +2129,35 @@ func TestMissingIndices(t *testing.T) {
 	}
 }

+func Test_getFCUArgs(t *testing.T) {
+	s, tr := minimalTestService(t)
+	ctx := tr.ctx
+	st, keys := util.DeterministicGenesisState(t, 64)
+	b, err := util.GenerateFullBlock(st, keys, util.DefaultBlockGenConfig(), 1)
+	require.NoError(t, err)
+	wsb, err := consensusblocks.NewSignedBeaconBlock(b)
+	require.NoError(t, err)
+
+	cfg := &postBlockProcessConfig{
+		ctx:            ctx,
+		signed:         wsb,
+		blockRoot:      [32]byte{'a'},
+		postState:      st,
+		isValidPayload: true,
+	}
+	// error branch
+	fcuArgs := &fcuConfig{}
+	err = s.getFCUArgs(cfg, fcuArgs)
+	require.ErrorContains(t, "block does not exist", err)
+
+	// canonical branch
+	cfg.headRoot = cfg.blockRoot
+	fcuArgs = &fcuConfig{}
+	err = s.getFCUArgs(cfg, fcuArgs)
+	require.NoError(t, err)
+	require.Equal(t, cfg.blockRoot, fcuArgs.headRoot)
+}
+
 func fakeCommitments(n int) [][]byte {
 	f := make([][]byte, n)
 	for i := range f {
--- a/beacon-chain/blockchain/receive_attestation.go
+++ b/beacon-chain/blockchain/receive_attestation.go
@@ -9,7 +9,6 @@ import (
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v4/config/features"
 	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
@@ -122,35 +121,43 @@ func (s *Service) UpdateHead(ctx context.Context, proposingSlot primitives.Slot)
 	defer s.cfg.ForkChoiceStore.Unlock()
 	// This function is only called at 10 seconds or 0 seconds into the slot
 	disparity := params.BeaconConfig().MaximumGossipClockDisparityDuration()
-	if !features.Get().DisableReorgLateBlocks {
-		disparity += reorgLateBlockCountAttestations
-	}
+	disparity += reorgLateBlockCountAttestations
+
 	s.processAttestations(ctx, disparity)

 	processAttsElapsedTime.Observe(float64(time.Since(start).Milliseconds()))

 	start = time.Now()
+	// return early if we haven't changed head
 	newHeadRoot, err := s.cfg.ForkChoiceStore.Head(ctx)
 	if err != nil {
 		log.WithError(err).Error("Could not compute head from new attestations")
-		// Fallback to our current head root in the event of a failure.
-		s.headLock.RLock()
-		newHeadRoot = s.headRoot()
-		s.headLock.RUnlock()
+		return
+	}
+	if !s.isNewHead(newHeadRoot) {
+		return
+	}
+	log.WithField("newHeadRoot", fmt.Sprintf("%#x", newHeadRoot)).Debug("Head changed due to attestations")
+	headState, headBlock, err := s.getStateAndBlock(ctx, newHeadRoot)
+	if err != nil {
+		log.WithError(err).Error("could not get head block")
+		return
 	}
 	newAttHeadElapsedTime.Observe(float64(time.Since(start).Milliseconds()))
-
-	changed, err := s.forkchoiceUpdateWithExecution(s.ctx, newHeadRoot, proposingSlot)
-	if err != nil {
-		log.WithError(err).Error("could not update forkchoice")
+	fcuArgs := &fcuConfig{
+		headState:     headState,
+		headRoot:      newHeadRoot,
+		headBlock:     headBlock,
+		proposingSlot: proposingSlot,
 	}
-	if changed {
-		s.headLock.RLock()
-		log.WithFields(logrus.Fields{
-			"oldHeadRoot": fmt.Sprintf("%#x", s.headRoot()),
-			"newHeadRoot": fmt.Sprintf("%#x", newHeadRoot),
-		}).Debug("Head changed due to attestations")
-		s.headLock.RUnlock()
+	if s.inRegularSync() {
+		fcuArgs.attributes = s.getPayloadAttribute(ctx, headState, proposingSlot, newHeadRoot[:])
+	}
+	if fcuArgs.attributes != nil && s.shouldOverrideFCU(newHeadRoot, proposingSlot) {
+		return
+	}
+	if err := s.forkchoiceUpdateWithExecution(s.ctx, fcuArgs); err != nil {
+		log.WithError(err).Error("could not update forkchoice")
 	}
 }

--- a/beacon-chain/blockchain/receive_attestation_test.go
+++ b/beacon-chain/blockchain/receive_attestation_test.go
@@ -112,7 +112,7 @@ func TestService_ProcessAttestationsAndUpdateHead(t *testing.T) {
 	postState, err := service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, tRoot, wsb, postState))
-	require.NoError(t, service.postBlockProcess(ctx, wsb, tRoot, postState, false))
+	require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, tRoot, [32]byte{}, postState, false}))
 	copied, err = service.cfg.StateGen.StateByRoot(ctx, tRoot)
 	require.NoError(t, err)
 	require.Equal(t, 2, fcs.NodeCount())
@@ -168,7 +168,7 @@ func TestService_UpdateHead_NoAtts(t *testing.T) {
 	postState, err := service.validateStateTransition(ctx, preState, wsb)
 	require.NoError(t, err)
 	require.NoError(t, service.savePostStateInfo(ctx, tRoot, wsb, postState))
-	require.NoError(t, service.postBlockProcess(ctx, wsb, tRoot, postState, false))
+	require.NoError(t, service.postBlockProcess(&postBlockProcessConfig{ctx, wsb, tRoot, [32]byte{}, postState, false}))
 	require.Equal(t, 2, fcs.NodeCount())
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wsb))
 	require.Equal(t, tRoot, service.head.root)
--- a/beacon-chain/blockchain/receive_block.go
+++ b/beacon-chain/blockchain/receive_block.go
@@ -12,6 +12,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
 	coreTime "github.com/prysmaticlabs/prysm/v4/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/das"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/v4/config/features"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
@@ -33,8 +34,8 @@ var epochsSinceFinalitySaveHotStateDB = primitives.Epoch(100)

 // BlockReceiver interface defines the methods of chain service for receiving and processing new blocks.
 type BlockReceiver interface {
-	ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte) error
-	ReceiveBlockBatch(ctx context.Context, blocks []blocks.ROBlock) error
+	ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte, avs das.AvailabilityStore) error
+	ReceiveBlockBatch(ctx context.Context, blocks []blocks.ROBlock, avs das.AvailabilityStore) error
 	HasBlock(ctx context.Context, root [32]byte) bool
 	RecentBlockSlot(root [32]byte) (primitives.Slot, error)
 	BlockBeingSynced([32]byte) bool
@@ -56,7 +57,7 @@ type SlashingReceiver interface {
 //  1. Validate block, apply state transition and update checkpoints
 //  2. Apply fork choice to the processed block
 //  3. Save latest head info
-func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte) error {
+func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte, avs das.AvailabilityStore) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.ReceiveBlock")
 	defer span.End()
 	// Return early if the block has been synced
@@ -72,6 +73,10 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySig
 	if err != nil {
 		return err
 	}
+	rob, err := blocks.NewROBlockWithRoot(block, blockRoot)
+	if err != nil {
+		return err
+	}

 	preState, err := s.getBlockPreState(ctx, blockCopy.Block())
 	if err != nil {
@@ -106,20 +111,35 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySig
 	if err := eg.Wait(); err != nil {
 		return err
 	}
-
 	daStartTime := time.Now()
-	if err := s.isDataAvailable(ctx, blockRoot, blockCopy); err != nil {
-		return errors.Wrap(err, "could not validate blob data availability")
+	if avs != nil {
+		if err := avs.IsDataAvailable(ctx, s.CurrentSlot(), rob); err != nil {
+			return errors.Wrap(err, "could not validate blob data availability (AvailabilityStore.IsDataAvailable)")
+		}
+	} else {
+		if err := s.isDataAvailable(ctx, blockRoot, blockCopy); err != nil {
+			return errors.Wrap(err, "could not validate blob data availability")
+		}
 	}
 	daWaitedTime := time.Since(daStartTime)

+	// Defragment the state before continuing block processing.
+	s.defragmentState(postState)
+
 	// The rest of block processing takes a lock on forkchoice.
 	s.cfg.ForkChoiceStore.Lock()
 	defer s.cfg.ForkChoiceStore.Unlock()
 	if err := s.savePostStateInfo(ctx, blockRoot, blockCopy, postState); err != nil {
 		return errors.Wrap(err, "could not save post state info")
 	}
-	if err := s.postBlockProcess(ctx, blockCopy, blockRoot, postState, isValidPayload); err != nil {
+	args := &postBlockProcessConfig{
+		ctx:            ctx,
+		signed:         blockCopy,
+		blockRoot:      blockRoot,
+		postState:      postState,
+		isValidPayload: isValidPayload,
+	}
+	if err := s.postBlockProcess(args); err != nil {
 		err := errors.Wrap(err, "could not process block")
 		tracing.AnnotateError(span, err)
 		return err
@@ -196,7 +216,7 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySig
 // ReceiveBlockBatch processes the whole block batch at once, assuming the block batch is linear ,transitioning
 // the state, performing batch verification of all collected signatures and then performing the appropriate
 // actions for a block post-transition.
-func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []blocks.ROBlock) error {
+func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []blocks.ROBlock, avs das.AvailabilityStore) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.ReceiveBlockBatch")
 	defer span.End()

@@ -204,7 +224,7 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []blocks.ROBlock
 	defer s.cfg.ForkChoiceStore.Unlock()

 	// Apply state transition on the incoming newly received block batches, one by one.
-	if err := s.onBlockBatch(ctx, blocks); err != nil {
+	if err := s.onBlockBatch(ctx, blocks, avs); err != nil {
 		err := errors.Wrap(err, "could not process block in batch")
 		tracing.AnnotateError(span, err)
 		return err
--- a/beacon-chain/blockchain/receive_block_test.go
+++ b/beacon-chain/blockchain/receive_block_test.go
@@ -7,6 +7,8 @@ import (
 	"time"

 	blockchainTesting "github.com/prysmaticlabs/prysm/v4/beacon-chain/blockchain/testing"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/das"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/voluntaryexits"
 	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
@@ -130,7 +132,9 @@ func TestService_ReceiveBlock(t *testing.T) {
 			s, tr := minimalTestService(t,
 				WithFinalizedStateAtStartUp(genesis),
 				WithExitPool(voluntaryexits.NewPool()),
-				WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}))
+				WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}),
+				WithTrackedValidatorsCache(cache.NewTrackedValidatorsCache()),
+			)

 			beaconDB := tr.db
 			genesisBlockRoot := bytesutil.ToBytes32(nil)
@@ -143,7 +147,7 @@ func TestService_ReceiveBlock(t *testing.T) {
 			require.NoError(t, err)
 			wsb, err := blocks.NewSignedBeaconBlock(tt.args.block)
 			require.NoError(t, err)
-			err = s.ReceiveBlock(ctx, wsb, root)
+			err = s.ReceiveBlock(ctx, wsb, root, nil)
 			if tt.wantedErr != "" {
 				assert.ErrorContains(t, tt.wantedErr, err)
 			} else {
@@ -176,7 +180,7 @@ func TestService_ReceiveBlockUpdateHead(t *testing.T) {
 	go func() {
 		wsb, err := blocks.NewSignedBeaconBlock(b)
 		require.NoError(t, err)
-		require.NoError(t, s.ReceiveBlock(ctx, wsb, root))
+		require.NoError(t, s.ReceiveBlock(ctx, wsb, root, nil))
 		wg.Done()
 	}()
 	wg.Wait()
@@ -240,7 +244,7 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 			require.NoError(t, err)
 			rwsb, err := blocks.NewROBlock(wsb)
 			require.NoError(t, err)
-			err = s.ReceiveBlockBatch(ctx, []blocks.ROBlock{rwsb})
+			err = s.ReceiveBlockBatch(ctx, []blocks.ROBlock{rwsb}, &das.MockAvailabilityStore{})
 			if tt.wantedErr != "" {
 				assert.ErrorContains(t, tt.wantedErr, err)
 			} else {
--- a/beacon-chain/blockchain/service.go
+++ b/beacon-chain/blockchain/service.go
@@ -11,6 +11,8 @@ import (
 	"time"

 	"github.com/pkg/errors"
+	"go.opencensus.io/trace"
+
 	"github.com/prysmaticlabs/prysm/v4/async/event"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/blockchain/kzg"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
@@ -37,34 +39,35 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
 	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
 	prysmTime "github.com/prysmaticlabs/prysm/v4/time"
 	"github.com/prysmaticlabs/prysm/v4/time/slots"
-	"go.opencensus.io/trace"
 )

 // Service represents a service that handles the internal
 // logic of managing the full PoS beacon chain.
 type Service struct {
-	cfg                  *config
-	ctx                  context.Context
-	cancel               context.CancelFunc
-	genesisTime          time.Time
-	head                 *head
-	headLock             sync.RWMutex
-	originBlockRoot      [32]byte // genesis root, or weak subjectivity checkpoint root, depending on how the node is initialized
-	boundaryRoots        [][32]byte
-	checkpointStateCache *cache.CheckpointStateCache
-	initSyncBlocks       map[[32]byte]interfaces.ReadOnlySignedBeaconBlock
-	initSyncBlocksLock   sync.RWMutex
-	wsVerifier           *WeakSubjectivityVerifier
-	clockSetter          startup.ClockSetter
-	clockWaiter          startup.ClockWaiter
-	syncComplete         chan struct{}
-	blobNotifiers        *blobNotifierMap
-	blockBeingSynced     *currentlySyncingBlock
-	blobStorage          *filesystem.BlobStorage
+	cfg                           *config
+	ctx                           context.Context
+	cancel                        context.CancelFunc
+	genesisTime                   time.Time
+	head                          *head
+	headLock                      sync.RWMutex
+	originBlockRoot               [32]byte // genesis root, or weak subjectivity checkpoint root, depending on how the node is initialized
+	boundaryRoots                 [][32]byte
+	checkpointStateCache          *cache.CheckpointStateCache
+	initSyncBlocks                map[[32]byte]interfaces.ReadOnlySignedBeaconBlock
+	initSyncBlocksLock            sync.RWMutex
+	wsVerifier                    *WeakSubjectivityVerifier
+	clockSetter                   startup.ClockSetter
+	clockWaiter                   startup.ClockWaiter
+	syncComplete                  chan struct{}
+	blobNotifiers                 *blobNotifierMap
+	blockBeingSynced              *currentlySyncingBlock
+	blobStorage                   *filesystem.BlobStorage
+	lastPublishedLightClientEpoch primitives.Epoch
 }

 // config options for the service.
@@ -73,7 +76,8 @@ type config struct {
 	ChainStartFetcher       execution.ChainStartFetcher
 	BeaconDB                db.HeadAccessDatabase
 	DepositCache            cache.DepositCache
-	ProposerSlotIndexCache  *cache.ProposerPayloadIDsCache
+	PayloadIDCache          *cache.PayloadIDCache
+	TrackedValidatorsCache  *cache.TrackedValidatorsCache
 	AttPool                 attestations.Pool
 	ExitPool                voluntaryexits.PoolManager
 	SlashingPool            slashings.PoolManager
@@ -167,7 +171,7 @@ func NewService(ctx context.Context, opts ...Option) (*Service, error) {
 		checkpointStateCache: cache.NewCheckpointStateCache(),
 		initSyncBlocks:       make(map[[32]byte]interfaces.ReadOnlySignedBeaconBlock),
 		blobNotifiers:        bn,
-		cfg:                  &config{ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache()},
+		cfg:                  &config{},
 		blockBeingSynced:     &currentlySyncingBlock{roots: make(map[[32]byte]struct{})},
 	}
 	for _, opt := range opts {
--- a/beacon-chain/blockchain/service_test.go
+++ b/beacon-chain/blockchain/service_test.go
@@ -100,7 +100,7 @@ func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
 		WithForkChoiceStore(fc),
 		WithAttestationService(attService),
 		WithStateGen(stateGen),
-		WithProposerIdsCache(cache.NewProposerPayloadIDsCache()),
+		WithPayloadIDCache(cache.NewPayloadIDCache()),
 		WithClockSynchronizer(startup.NewClockSynchronizer()),
 	}

--- a/beacon-chain/blockchain/setup_test.go
+++ b/beacon-chain/blockchain/setup_test.go
@@ -6,9 +6,11 @@ import (
 	"testing"

 	"github.com/prysmaticlabs/prysm/v4/async/event"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache/depositcache"
 	statefeed "github.com/prysmaticlabs/prysm/v4/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db/filesystem"
 	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice"
 	doublylinkedtree "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/doubly-linked-tree"
@@ -114,6 +116,8 @@ func minimalTestService(t *testing.T, opts ...Option) (*Service, *testServiceReq
 		WithAttestationService(req.attSrv),
 		WithBLSToExecPool(req.blsPool),
 		WithDepositCache(dc),
+		WithTrackedValidatorsCache(cache.NewTrackedValidatorsCache()),
+		WithBlobStorage(filesystem.NewEphemeralBlobStorage(t)),
 	}
 	// append the variadic opts so they override the defaults by being processed afterwards
 	opts = append(defOpts, opts...)
--- a/beacon-chain/blockchain/testing/BUILD.bazel
+++ b/beacon-chain/blockchain/testing/BUILD.bazel
@@ -17,6 +17,7 @@ go_library(
        "//beacon-chain/core/feed/operation:go_default_library",
        "//beacon-chain/core/feed/state:go_default_library",
        "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/das:go_default_library",
        "//beacon-chain/db:go_default_library",
        "//beacon-chain/forkchoice:go_default_library",
        "//beacon-chain/state:go_default_library",
--- a/beacon-chain/blockchain/testing/mock.go
+++ b/beacon-chain/blockchain/testing/mock.go
@@ -16,6 +16,7 @@ import (
 	opfeed "github.com/prysmaticlabs/prysm/v4/beacon-chain/core/feed/operation"
 	statefeed "github.com/prysmaticlabs/prysm/v4/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/das"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
@@ -208,7 +209,7 @@ func (s *ChainService) ReceiveBlockInitialSync(ctx context.Context, block interf
 }

 // ReceiveBlockBatch processes blocks in batches from initial-sync.
-func (s *ChainService) ReceiveBlockBatch(ctx context.Context, blks []blocks.ROBlock) error {
+func (s *ChainService) ReceiveBlockBatch(ctx context.Context, blks []blocks.ROBlock, _ das.AvailabilityStore) error {
 	if s.State == nil {
 		return ErrNilState
 	}
@@ -238,7 +239,7 @@ func (s *ChainService) ReceiveBlockBatch(ctx context.Context, blks []blocks.ROBl
 }

 // ReceiveBlock mocks ReceiveBlock method in chain service.
-func (s *ChainService) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, _ [32]byte) error {
+func (s *ChainService) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, _ [32]byte, _ das.AvailabilityStore) error {
 	if s.ReceiveBlockMockErr != nil {
 		return s.ReceiveBlockMockErr
 	}
@@ -320,7 +321,7 @@ func (s *ChainService) PreviousJustifiedCheckpt() *ethpb.Checkpoint {
 }

 // ReceiveAttestation mocks ReceiveAttestation method in chain service.
-func (_ *ChainService) ReceiveAttestation(_ context.Context, _ *ethpb.Attestation) error {
+func (*ChainService) ReceiveAttestation(_ context.Context, _ *ethpb.Attestation) error {
 	return nil
 }

@@ -400,12 +401,12 @@ func (s *ChainService) RecentBlockSlot([32]byte) (primitives.Slot, error) {
 }

 // HeadGenesisValidatorsRoot mocks HeadGenesisValidatorsRoot method in chain service.
-func (_ *ChainService) HeadGenesisValidatorsRoot() [32]byte {
+func (*ChainService) HeadGenesisValidatorsRoot() [32]byte {
 	return [32]byte{}
 }

 // VerifyLmdFfgConsistency mocks VerifyLmdFfgConsistency and always returns nil.
-func (_ *ChainService) VerifyLmdFfgConsistency(_ context.Context, a *ethpb.Attestation) error {
+func (*ChainService) VerifyLmdFfgConsistency(_ context.Context, a *ethpb.Attestation) error {
 	if !bytes.Equal(a.Data.BeaconBlockRoot, a.Data.Target.Root) {
 		return errors.New("LMD and FFG miss matched")
 	}
@@ -413,7 +414,7 @@ func (_ *ChainService) VerifyLmdFfgConsistency(_ context.Context, a *ethpb.Attes
 }

 // ChainHeads mocks ChainHeads and always return nil.
-func (_ *ChainService) ChainHeads() ([][32]byte, []primitives.Slot) {
+func (*ChainService) ChainHeads() ([][32]byte, []primitives.Slot) {
 	return [][32]byte{
 			bytesutil.ToBytes32(bytesutil.PadTo([]byte("foo"), 32)),
 			bytesutil.ToBytes32(bytesutil.PadTo([]byte("bar"), 32)),
@@ -422,7 +423,7 @@ func (_ *ChainService) ChainHeads() ([][32]byte, []primitives.Slot) {
 }

 // HeadPublicKeyToValidatorIndex mocks HeadPublicKeyToValidatorIndex and always return 0 and true.
-func (_ *ChainService) HeadPublicKeyToValidatorIndex(_ [fieldparams.BLSPubkeyLength]byte) (primitives.ValidatorIndex, bool) {
+func (*ChainService) HeadPublicKeyToValidatorIndex(_ [fieldparams.BLSPubkeyLength]byte) (primitives.ValidatorIndex, bool) {
 	return 0, true
 }

@@ -486,7 +487,7 @@ func (s *ChainService) UpdateHead(ctx context.Context, slot primitives.Slot) {
 }

 // ReceiveAttesterSlashing mocks the same method in the chain service.
-func (s *ChainService) ReceiveAttesterSlashing(context.Context, *ethpb.AttesterSlashing) {}
+func (*ChainService) ReceiveAttesterSlashing(context.Context, *ethpb.AttesterSlashing) {}

 // IsFinalized mocks the same method in the chain service.
 func (s *ChainService) IsFinalized(_ context.Context, blockRoot [32]byte) bool {
@@ -599,12 +600,12 @@ func (s *ChainService) ProposerBoost() [32]byte {
 }

 // FinalizedBlockHash mocks the same method in the chain service
-func (s *ChainService) FinalizedBlockHash() [32]byte {
+func (*ChainService) FinalizedBlockHash() [32]byte {
 	return [32]byte{}
 }

 // UnrealizedJustifiedPayloadBlockHash mocks the same method in the chain service
-func (s *ChainService) UnrealizedJustifiedPayloadBlockHash() [32]byte {
+func (*ChainService) UnrealizedJustifiedPayloadBlockHash() [32]byte {
 	return [32]byte{}
 }

--- a/beacon-chain/blockchain/tracked_proposer.go
+++ b/beacon-chain/blockchain/tracked_proposer.go
@@ -0,0 +1,27 @@
+package blockchain
+
+import (
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/config/features"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+)
+
+// trackedProposer returns whether the beacon node was informed, via the
+// validators/prepare_proposer endpoint, of the proposer at the given slot.
+// It only returns true if the tracked proposer is present and active.
+func (s *Service) trackedProposer(st state.ReadOnlyBeaconState, slot primitives.Slot) (cache.TrackedValidator, bool) {
+	if features.Get().PrepareAllPayloads {
+		return cache.TrackedValidator{Active: true}, true
+	}
+	id, err := helpers.BeaconProposerIndexAtSlot(s.ctx, st, slot)
+	if err != nil {
+		return cache.TrackedValidator{}, false
+	}
+	val, ok := s.cfg.TrackedValidatorsCache.Validator(id)
+	if !ok {
+		return cache.TrackedValidator{}, false
+	}
+	return val, val.Active
+}
--- a/beacon-chain/builder/testing/mock.go
+++ b/beacon-chain/builder/testing/mock.go
@@ -2,6 +2,7 @@ package testing

 import (
 	"context"
+	"math/big"

 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v4/api/client/builder"
@@ -54,13 +55,13 @@ func (s *MockBuilderService) SubmitBlindedBlock(_ context.Context, b interfaces.
 		}
 		return w, nil, s.ErrSubmitBlindedBlock
 	case version.Capella:
-		w, err := blocks.WrappedExecutionPayloadCapella(s.PayloadCapella, 0)
+		w, err := blocks.WrappedExecutionPayloadCapella(s.PayloadCapella, big.NewInt(0))
 		if err != nil {
 			return nil, nil, errors.Wrap(err, "could not wrap capella payload")
 		}
 		return w, nil, s.ErrSubmitBlindedBlock
 	case version.Deneb:
-		w, err := blocks.WrappedExecutionPayloadDeneb(s.PayloadDeneb, 0)
+		w, err := blocks.WrappedExecutionPayloadDeneb(s.PayloadDeneb, big.NewInt(0))
 		if err != nil {
 			return nil, nil, errors.Wrap(err, "could not wrap deneb payload")
 		}
--- a/beacon-chain/cache/BUILD.bazel
+++ b/beacon-chain/cache/BUILD.bazel
@@ -25,6 +25,7 @@ go_library(
        "sync_committee_disabled.go",  # keep
        "sync_committee_head_state.go",
        "sync_subnet_ids.go",
+        "tracked_validators.go",
    ],
    importpath = "github.com/prysmaticlabs/prysm/v4/beacon-chain/cache",
    visibility = [
--- a/beacon-chain/cache/payload_id.go
+++ b/beacon-chain/cache/payload_id.go
@@ -1,94 +1,63 @@
 package cache

 import (
-	"bytes"
 	"sync"

-	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
 )

-const keyLength = 40
-const vIdLength = 8
-const pIdLength = 8
-const vpIdsLength = vIdLength + pIdLength
+// RootToPayloadIDMap is a map with keys the head root and values the
+// corresponding PayloadID
+type RootToPayloadIDMap map[[32]byte]primitives.PayloadID

-// ProposerPayloadIDsCache is a cache of proposer payload IDs.
-// The key is the concatenation of the slot and the block root.
-// The value is the concatenation of the proposer and payload IDs, 8 bytes each.
-type ProposerPayloadIDsCache struct {
-	slotToProposerAndPayloadIDs map[[keyLength]byte][vpIdsLength]byte
-	sync.RWMutex
+// PayloadIDCache is a cache that keeps track of the prepared payload ID for the
+// given slot and with the given head root.
+type PayloadIDCache struct {
+	slotToPayloadID map[primitives.Slot]RootToPayloadIDMap
+	sync.Mutex
 }

-// NewProposerPayloadIDsCache creates a new proposer payload IDs cache.
-func NewProposerPayloadIDsCache() *ProposerPayloadIDsCache {
-	return &ProposerPayloadIDsCache{
-		slotToProposerAndPayloadIDs: make(map[[keyLength]byte][vpIdsLength]byte),
-	}
+// NewPayloadIDCache returns a new payload ID cache
+func NewPayloadIDCache() *PayloadIDCache {
+	return &PayloadIDCache{slotToPayloadID: make(map[primitives.Slot]RootToPayloadIDMap)}
 }

-// GetProposerPayloadIDs returns the proposer and payload IDs for the given slot and head root to build the block.
-func (f *ProposerPayloadIDsCache) GetProposerPayloadIDs(
-	slot primitives.Slot,
-	r [fieldparams.RootLength]byte,
-) (primitives.ValidatorIndex, [pIdLength]byte, bool) {
-	f.RLock()
-	defer f.RUnlock()
-	ids, ok := f.slotToProposerAndPayloadIDs[idKey(slot, r)]
+// PayloadID returns the payload ID for the given slot and parent block root
+func (p *PayloadIDCache) PayloadID(slot primitives.Slot, root [32]byte) (primitives.PayloadID, bool) {
+	p.Lock()
+	defer p.Unlock()
+	inner, ok := p.slotToPayloadID[slot]
 	if !ok {
-		return 0, [pIdLength]byte{}, false
+		return primitives.PayloadID{}, false
 	}
-	vId := ids[:vIdLength]
-
-	b := ids[vIdLength:]
-	var pId [pIdLength]byte
-	copy(pId[:], b)
-
-	return primitives.ValidatorIndex(bytesutil.BytesToUint64BigEndian(vId)), pId, true
+	pid, ok := inner[root]
+	if !ok {
+		return primitives.PayloadID{}, false
+	}
+	return pid, true
 }

-// SetProposerAndPayloadIDs sets the proposer and payload IDs for the given slot and head root to build block.
-func (f *ProposerPayloadIDsCache) SetProposerAndPayloadIDs(
-	slot primitives.Slot,
-	vId primitives.ValidatorIndex,
-	pId [pIdLength]byte,
-	r [fieldparams.RootLength]byte,
-) {
-	f.Lock()
-	defer f.Unlock()
-	var vIdBytes [vIdLength]byte
-	copy(vIdBytes[:], bytesutil.Uint64ToBytesBigEndian(uint64(vId)))
-
-	var bs [vpIdsLength]byte
-	copy(bs[:], append(vIdBytes[:], pId[:]...))
-
-	k := idKey(slot, r)
-	ids, ok := f.slotToProposerAndPayloadIDs[k]
-	// Ok to overwrite if the slot is already set but the cached payload ID is not set.
-	// This combats the re-org case where payload assignment could change at the start of the epoch.
-	var byte8 [vIdLength]byte
-	if !ok || (ok && bytes.Equal(ids[vIdLength:], byte8[:])) {
-		f.slotToProposerAndPayloadIDs[k] = bs
+// SetPayloadID updates the payload ID for the given slot and head root
+// it also prunes older entries in the cache
+func (p *PayloadIDCache) Set(slot primitives.Slot, root [32]byte, pid primitives.PayloadID) {
+	p.Lock()
+	defer p.Unlock()
+	if slot > 1 {
+		p.prune(slot - 2)
 	}
+	inner, ok := p.slotToPayloadID[slot]
+	if !ok {
+		inner = make(RootToPayloadIDMap)
+		p.slotToPayloadID[slot] = inner
+	}
+	inner[root] = pid
 }

-// PrunePayloadIDs removes the payload ID entries older than input slot.
-func (f *ProposerPayloadIDsCache) PrunePayloadIDs(slot primitives.Slot) {
-	f.Lock()
-	defer f.Unlock()
-
-	for k := range f.slotToProposerAndPayloadIDs {
-		s := primitives.Slot(bytesutil.BytesToUint64BigEndian(k[:8]))
-		if slot > s {
-			delete(f.slotToProposerAndPayloadIDs, k)
+// Prune prunes old payload IDs. Requires a Lock in the cache
+func (p *PayloadIDCache) prune(slot primitives.Slot) {
+	for key := range p.slotToPayloadID {
+		if key < slot {
+			delete(p.slotToPayloadID, key)
 		}
 	}
 }
-
-func idKey(slot primitives.Slot, r [fieldparams.RootLength]byte) [keyLength]byte {
-	var k [keyLength]byte
-	copy(k[:], append(bytesutil.Uint64ToBytesBigEndian(uint64(slot)), r[:]...))
-	return k
-}
--- a/beacon-chain/cache/payload_id_test.go
+++ b/beacon-chain/cache/payload_id_test.go
@@ -8,65 +8,54 @@ import (
 )

 func TestValidatorPayloadIDsCache_GetAndSaveValidatorPayloadIDs(t *testing.T) {
-	cache := NewProposerPayloadIDsCache()
+	cache := NewPayloadIDCache()
 	var r [32]byte
-	i, p, ok := cache.GetProposerPayloadIDs(0, r)
+	p, ok := cache.PayloadID(0, r)
 	require.Equal(t, false, ok)
-	require.Equal(t, primitives.ValidatorIndex(0), i)
-	require.Equal(t, [pIdLength]byte{}, p)
+	require.Equal(t, primitives.PayloadID{}, p)

 	slot := primitives.Slot(1234)
-	vid := primitives.ValidatorIndex(34234324)
-	pid := [8]byte{1, 2, 3, 3, 7, 8, 7, 8}
+	pid := primitives.PayloadID{1, 2, 3, 3, 7, 8, 7, 8}
 	r = [32]byte{1, 2, 3}
-	cache.SetProposerAndPayloadIDs(slot, vid, pid, r)
-	i, p, ok = cache.GetProposerPayloadIDs(slot, r)
+	cache.Set(slot, r, pid)
+	p, ok = cache.PayloadID(slot, r)
 	require.Equal(t, true, ok)
-	require.Equal(t, vid, i)
 	require.Equal(t, pid, p)

 	slot = primitives.Slot(9456456)
-	vid = primitives.ValidatorIndex(6786745)
 	r = [32]byte{4, 5, 6}
-	cache.SetProposerAndPayloadIDs(slot, vid, [pIdLength]byte{}, r)
-	i, p, ok = cache.GetProposerPayloadIDs(slot, r)
+	cache.Set(slot, r, primitives.PayloadID{})
+	p, ok = cache.PayloadID(slot, r)
 	require.Equal(t, true, ok)
-	require.Equal(t, vid, i)
-	require.Equal(t, [pIdLength]byte{}, p)
+	require.Equal(t, primitives.PayloadID{}, p)

 	// reset cache without pid
 	slot = primitives.Slot(9456456)
-	vid = primitives.ValidatorIndex(11111)
 	r = [32]byte{7, 8, 9}
 	pid = [8]byte{3, 2, 3, 33, 72, 8, 7, 8}
-	cache.SetProposerAndPayloadIDs(slot, vid, pid, r)
-	i, p, ok = cache.GetProposerPayloadIDs(slot, r)
+	cache.Set(slot, r, pid)
+	p, ok = cache.PayloadID(slot, r)
 	require.Equal(t, true, ok)
-	require.Equal(t, vid, i)
 	require.Equal(t, pid, p)

 	// Forked chain
 	r = [32]byte{1, 2, 3}
-	i, p, ok = cache.GetProposerPayloadIDs(slot, r)
+	p, ok = cache.PayloadID(slot, r)
 	require.Equal(t, false, ok)
-	require.Equal(t, primitives.ValidatorIndex(0), i)
-	require.Equal(t, [pIdLength]byte{}, p)
+	require.Equal(t, primitives.PayloadID{}, p)

-	// existing pid - no change in cache
+	// existing pid - change the cache
 	slot = primitives.Slot(9456456)
-	vid = primitives.ValidatorIndex(11111)
 	r = [32]byte{7, 8, 9}
-	newPid := [8]byte{1, 2, 3, 33, 72, 8, 7, 1}
-	cache.SetProposerAndPayloadIDs(slot, vid, newPid, r)
-	i, p, ok = cache.GetProposerPayloadIDs(slot, r)
+	newPid := primitives.PayloadID{1, 2, 3, 33, 72, 8, 7, 1}
+	cache.Set(slot, r, newPid)
+	p, ok = cache.PayloadID(slot, r)
 	require.Equal(t, true, ok)
-	require.Equal(t, vid, i)
-	require.Equal(t, pid, p)
+	require.Equal(t, newPid, p)

 	// remove cache entry
-	cache.PrunePayloadIDs(slot + 1)
-	i, p, ok = cache.GetProposerPayloadIDs(slot, r)
+	cache.prune(slot + 1)
+	p, ok = cache.PayloadID(slot, r)
 	require.Equal(t, false, ok)
-	require.Equal(t, primitives.ValidatorIndex(0), i)
-	require.Equal(t, [pIdLength]byte{}, p)
+	require.Equal(t, primitives.PayloadID{}, p)
 }
--- a/beacon-chain/cache/proposer_indices.go
+++ b/beacon-chain/cache/proposer_indices.go
@@ -42,17 +42,15 @@ var (
 // root would be for slot 32 if present.
 type ProposerIndicesCache struct {
 	sync.Mutex
-	indices       map[primitives.Epoch]map[[32]byte][fieldparams.SlotsPerEpoch]primitives.ValidatorIndex
-	unsafeIndices map[primitives.Epoch]map[[32]byte][fieldparams.SlotsPerEpoch]primitives.ValidatorIndex
-	rootMap       map[forkchoicetypes.Checkpoint][32]byte // A map from checkpoint root to state root
+	indices map[primitives.Epoch]map[[32]byte][fieldparams.SlotsPerEpoch]primitives.ValidatorIndex
+	rootMap map[forkchoicetypes.Checkpoint][32]byte // A map from checkpoint root to state root
 }

 // NewProposerIndicesCache returns a newly created cache
 func NewProposerIndicesCache() *ProposerIndicesCache {
 	return &ProposerIndicesCache{
-		indices:       make(map[primitives.Epoch]map[[32]byte][fieldparams.SlotsPerEpoch]primitives.ValidatorIndex),
-		unsafeIndices: make(map[primitives.Epoch]map[[32]byte][fieldparams.SlotsPerEpoch]primitives.ValidatorIndex),
-		rootMap:       make(map[forkchoicetypes.Checkpoint][32]byte),
+		indices: make(map[primitives.Epoch]map[[32]byte][fieldparams.SlotsPerEpoch]primitives.ValidatorIndex),
+		rootMap: make(map[forkchoicetypes.Checkpoint][32]byte),
 	}
 }

@@ -74,18 +72,6 @@ func (p *ProposerIndicesCache) ProposerIndices(epoch primitives.Epoch, root [32]
 	return indices, exists
 }

-// UnsafeProposerIndices returns the proposer indices (unsafe) for the given root
-func (p *ProposerIndicesCache) UnsafeProposerIndices(epoch primitives.Epoch, root [32]byte) ([fieldparams.SlotsPerEpoch]primitives.ValidatorIndex, bool) {
-	p.Lock()
-	defer p.Unlock()
-	inner, ok := p.unsafeIndices[epoch]
-	if !ok {
-		return [fieldparams.SlotsPerEpoch]primitives.ValidatorIndex{}, false
-	}
-	indices, exists := inner[root]
-	return indices, exists
-}
-
 // Prune resets the ProposerIndicesCache to its initial state
 func (p *ProposerIndicesCache) Prune(epoch primitives.Epoch) {
 	p.Lock()
@@ -95,11 +81,6 @@ func (p *ProposerIndicesCache) Prune(epoch primitives.Epoch) {
 			delete(p.indices, key)
 		}
 	}
-	for key := range p.unsafeIndices {
-		if key < epoch {
-			delete(p.unsafeIndices, key)
-		}
-	}
 	for key := range p.rootMap {
 		if key.Epoch+1 < epoch {
 			delete(p.rootMap, key)
@@ -120,18 +101,6 @@ func (p *ProposerIndicesCache) Set(epoch primitives.Epoch, root [32]byte, indice
 	inner[root] = indices
 }

-// SetUnsafe sets the unsafe proposer indices for the given root as key
-func (p *ProposerIndicesCache) SetUnsafe(epoch primitives.Epoch, root [32]byte, indices [fieldparams.SlotsPerEpoch]primitives.ValidatorIndex) {
-	p.Lock()
-	defer p.Unlock()
-	inner, ok := p.unsafeIndices[epoch]
-	if !ok {
-		inner = make(map[[32]byte][fieldparams.SlotsPerEpoch]primitives.ValidatorIndex)
-		p.unsafeIndices[epoch] = inner
-	}
-	inner[root] = indices
-}
-
 // SetCheckpoint updates the map from checkpoints to state roots
 func (p *ProposerIndicesCache) SetCheckpoint(c forkchoicetypes.Checkpoint, root [32]byte) {
 	p.Lock()
@@ -146,6 +115,7 @@ func (p *ProposerIndicesCache) IndicesFromCheckpoint(c forkchoicetypes.Checkpoin
 	root, ok := p.rootMap[c]
 	p.Unlock()
 	if !ok {
+		ProposerIndicesCacheMiss.Inc()
 		return emptyIndices, ok
 	}
 	return p.ProposerIndices(c.Epoch+1, root)
--- a/beacon-chain/cache/proposer_indices_disabled.go
+++ b/beacon-chain/cache/proposer_indices_disabled.go
@@ -4,11 +4,26 @@
 package cache

 import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
 	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
 	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
 )

+var (
+	// ProposerIndicesCacheMiss tracks the number of proposerIndices requests that aren't present in the cache.
+	ProposerIndicesCacheMiss = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "proposer_indices_cache_miss",
+		Help: "The number of proposer indices requests that aren't present in the cache.",
+	})
+	// ProposerIndicesCacheHit tracks the number of proposerIndices requests that are in the cache.
+	ProposerIndicesCacheHit = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "proposer_indices_cache_hit",
+		Help: "The number of proposer indices requests that are present in the cache.",
+	})
+)
+
 // FakeProposerIndicesCache is a struct with 1 queue for looking up proposer indices by root.
 type FakeProposerIndicesCache struct {
 }
--- a/beacon-chain/cache/proposer_indices_test.go
+++ b/beacon-chain/cache/proposer_indices_test.go
@@ -34,121 +34,72 @@ func TestProposerCache_Set(t *testing.T) {
 	require.Equal(t, emptyIndices, received)
 }

-func TestProposerCache_SetUnsafe(t *testing.T) {
-	cache := NewProposerIndicesCache()
-	bRoot := [32]byte{'A'}
-	indices, ok := cache.UnsafeProposerIndices(0, bRoot)
-	require.Equal(t, false, ok)
-	emptyIndices := [fieldparams.SlotsPerEpoch]primitives.ValidatorIndex{}
-	require.Equal(t, indices, emptyIndices, "Expected committee count not to exist in empty cache")
-	emptyIndices[0] = 1
-	cache.SetUnsafe(0, bRoot, emptyIndices)
-
-	received, ok := cache.UnsafeProposerIndices(0, bRoot)
-	require.Equal(t, true, ok)
-	require.Equal(t, received, emptyIndices)
-
-	newRoot := [32]byte{'B'}
-	copy(emptyIndices[3:], []primitives.ValidatorIndex{1, 2, 3, 4, 5, 6})
-	cache.SetUnsafe(0, newRoot, emptyIndices)
-
-	received, ok = cache.UnsafeProposerIndices(0, newRoot)
-	require.Equal(t, true, ok)
-	require.Equal(t, emptyIndices, received)
-}
-
 func TestProposerCache_CheckpointAndPrune(t *testing.T) {
 	cache := NewProposerIndicesCache()
 	indices := [fieldparams.SlotsPerEpoch]primitives.ValidatorIndex{}
-	root := [32]byte{'a'}
-	cpRoot := [32]byte{'b'}
 	copy(indices[3:], []primitives.ValidatorIndex{1, 2, 3, 4, 5, 6})
 	for i := 1; i < 10; i++ {
+		root := [32]byte{byte(i)}
 		cache.Set(primitives.Epoch(i), root, indices)
-		cache.SetUnsafe(primitives.Epoch(i), root, indices)
+		cpRoot := [32]byte{byte(i - 1)}
 		cache.SetCheckpoint(forkchoicetypes.Checkpoint{Epoch: primitives.Epoch(i - 1), Root: cpRoot}, root)
 	}
-	received, ok := cache.ProposerIndices(1, root)
+	received, ok := cache.ProposerIndices(1, [32]byte{1})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

-	received, ok = cache.ProposerIndices(4, root)
+	received, ok = cache.ProposerIndices(4, [32]byte{4})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

-	received, ok = cache.ProposerIndices(9, root)
+	received, ok = cache.ProposerIndices(9, [32]byte{9})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

-	received, ok = cache.UnsafeProposerIndices(1, root)
+	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

-	received, ok = cache.UnsafeProposerIndices(4, root)
+	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 3, Root: [32]byte{3}})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

-	received, ok = cache.UnsafeProposerIndices(9, root)
+	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 4, Root: [32]byte{4}})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

-	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 0, Root: cpRoot})
-	require.Equal(t, true, ok)
-	require.Equal(t, indices, received)
-
-	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 3, Root: cpRoot})
-	require.Equal(t, true, ok)
-	require.Equal(t, indices, received)
-
-	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 4, Root: cpRoot})
-	require.Equal(t, true, ok)
-	require.Equal(t, indices, received)
-
-	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 8, Root: cpRoot})
+	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 8, Root: [32]byte{8}})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

 	cache.Prune(5)

 	emptyIndices := [fieldparams.SlotsPerEpoch]primitives.ValidatorIndex{}
-	received, ok = cache.ProposerIndices(1, root)
+	received, ok = cache.ProposerIndices(1, [32]byte{1})
 	require.Equal(t, false, ok)
 	require.Equal(t, emptyIndices, received)

-	received, ok = cache.ProposerIndices(4, root)
+	received, ok = cache.ProposerIndices(4, [32]byte{4})
 	require.Equal(t, false, ok)
 	require.Equal(t, emptyIndices, received)

-	received, ok = cache.ProposerIndices(9, root)
+	received, ok = cache.ProposerIndices(9, [32]byte{9})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

-	received, ok = cache.UnsafeProposerIndices(1, root)
+	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 0, Root: [32]byte{0}})
 	require.Equal(t, false, ok)
 	require.Equal(t, emptyIndices, received)

-	received, ok = cache.UnsafeProposerIndices(4, root)
+	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 3, Root: [32]byte{3}})
 	require.Equal(t, false, ok)
 	require.Equal(t, emptyIndices, received)

-	received, ok = cache.UnsafeProposerIndices(9, root)
+	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 4, Root: [32]byte{4}})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)

-	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 0, Root: cpRoot})
-	require.Equal(t, false, ok)
-	require.Equal(t, emptyIndices, received)
-
-	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 3, Root: cpRoot})
-	require.Equal(t, false, ok)
-	require.Equal(t, emptyIndices, received)
-
-	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 4, Root: cpRoot})
+	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 8, Root: [32]byte{8}})
 	require.Equal(t, true, ok)
 	require.Equal(t, indices, received)
-
-	received, ok = cache.IndicesFromCheckpoint(forkchoicetypes.Checkpoint{Epoch: 8, Root: cpRoot})
-	require.Equal(t, true, ok)
-	require.Equal(t, indices, received)
-
 }
--- a/beacon-chain/cache/tracked_validators.go
+++ b/beacon-chain/cache/tracked_validators.go
@@ -0,0 +1,43 @@
+package cache
+
+import (
+	"sync"
+
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+)
+
+type TrackedValidator struct {
+	Active       bool
+	FeeRecipient primitives.ExecutionAddress
+	Index        primitives.ValidatorIndex
+}
+
+type TrackedValidatorsCache struct {
+	sync.Mutex
+	trackedValidators map[primitives.ValidatorIndex]TrackedValidator
+}
+
+func NewTrackedValidatorsCache() *TrackedValidatorsCache {
+	return &TrackedValidatorsCache{
+		trackedValidators: make(map[primitives.ValidatorIndex]TrackedValidator),
+	}
+}
+
+func (t *TrackedValidatorsCache) Validator(index primitives.ValidatorIndex) (TrackedValidator, bool) {
+	t.Lock()
+	defer t.Unlock()
+	val, ok := t.trackedValidators[index]
+	return val, ok
+}
+
+func (t *TrackedValidatorsCache) Set(val TrackedValidator) {
+	t.Lock()
+	defer t.Unlock()
+	t.trackedValidators[val.Index] = val
+}
+
+func (t *TrackedValidatorsCache) Prune() {
+	t.Lock()
+	defer t.Unlock()
+	t.trackedValidators = make(map[primitives.ValidatorIndex]TrackedValidator)
+}
--- a/beacon-chain/core/altair/epoch_precompute.go
+++ b/beacon-chain/core/altair/epoch_precompute.go
@@ -15,11 +15,12 @@ import (

 // AttDelta contains rewards and penalties for a single attestation.
 type AttDelta struct {
-	HeadReward    uint64
-	SourceReward  uint64
-	SourcePenalty uint64
-	TargetReward  uint64
-	TargetPenalty uint64
+	HeadReward        uint64
+	SourceReward      uint64
+	SourcePenalty     uint64
+	TargetReward      uint64
+	TargetPenalty     uint64
+	InactivityPenalty uint64
 }

 // InitializePrecomputeValidators precomputes individual validator for its attested balances and the total sum of validators attested balances of the epoch.
@@ -251,7 +252,7 @@ func ProcessRewardsAndPenaltiesPrecompute(
 		if err != nil {
 			return nil, err
 		}
-		balances[i] = helpers.DecreaseBalanceWithVal(balances[i], delta.SourcePenalty+delta.TargetPenalty)
+		balances[i] = helpers.DecreaseBalanceWithVal(balances[i], delta.SourcePenalty+delta.TargetPenalty+delta.InactivityPenalty)

 		vals[i].AfterEpochTransitionBalance = balances[i]
 	}
@@ -351,7 +352,7 @@ func attestationDelta(
 		if err != nil {
 			return &AttDelta{}, err
 		}
-		attDelta.TargetPenalty += n / inactivityDenominator
+		attDelta.InactivityPenalty = n / inactivityDenominator
 	}

 	return attDelta, nil
--- a/beacon-chain/core/altair/epoch_precompute_test.go
+++ b/beacon-chain/core/altair/epoch_precompute_test.go
@@ -220,7 +220,7 @@ func TestAttestationsDelta(t *testing.T) {
 	penalties := make([]uint64, len(deltas))
 	for i, d := range deltas {
 		rewards[i] = d.HeadReward + d.SourceReward + d.TargetReward
-		penalties[i] = d.SourcePenalty + d.TargetPenalty
+		penalties[i] = d.SourcePenalty + d.TargetPenalty + d.InactivityPenalty
 	}

 	// Reward amount should increase as validator index increases due to setup.
@@ -258,7 +258,7 @@ func TestAttestationsDeltaBellatrix(t *testing.T) {
 	penalties := make([]uint64, len(deltas))
 	for i, d := range deltas {
 		rewards[i] = d.HeadReward + d.SourceReward + d.TargetReward
-		penalties[i] = d.SourcePenalty + d.TargetPenalty
+		penalties[i] = d.SourcePenalty + d.TargetPenalty + d.InactivityPenalty
 	}

 	// Reward amount should increase as validator index increases due to setup.
@@ -306,7 +306,7 @@ func TestProcessRewardsAndPenaltiesPrecompute_Ok(t *testing.T) {
 	penalties := make([]uint64, len(deltas))
 	for i, d := range deltas {
 		rewards[i] = d.HeadReward + d.SourceReward + d.TargetReward
-		penalties[i] = d.SourcePenalty + d.TargetPenalty
+		penalties[i] = d.SourcePenalty + d.TargetPenalty + d.InactivityPenalty
 	}
 	for i := range rewards {
 		wanted[i] += rewards[i]
--- a/beacon-chain/core/blocks/genesis.go
+++ b/beacon-chain/core/blocks/genesis.go
@@ -105,6 +105,7 @@ func NewGenesisBlockForState(ctx context.Context, st state.BeaconState) (interfa
 						ReceiptsRoot:  make([]byte, 32),
 						LogsBloom:     make([]byte, 256),
 						PrevRandao:    make([]byte, 32),
+						ExtraData:     make([]byte, 0),
 						BaseFeePerGas: make([]byte, 32),
 						BlockHash:     make([]byte, 32),
 						Transactions:  make([][]byte, 0),
@@ -136,6 +137,7 @@ func NewGenesisBlockForState(ctx context.Context, st state.BeaconState) (interfa
 						ReceiptsRoot:  make([]byte, 32),
 						LogsBloom:     make([]byte, 256),
 						PrevRandao:    make([]byte, 32),
+						ExtraData:     make([]byte, 0),
 						BaseFeePerGas: make([]byte, 32),
 						BlockHash:     make([]byte, 32),
 						Transactions:  make([][]byte, 0),
@@ -168,6 +170,7 @@ func NewGenesisBlockForState(ctx context.Context, st state.BeaconState) (interfa
 						ReceiptsRoot:  make([]byte, 32),
 						LogsBloom:     make([]byte, 256),
 						PrevRandao:    make([]byte, 32),
+						ExtraData:     make([]byte, 0),
 						BaseFeePerGas: make([]byte, 32),
 						BlockHash:     make([]byte, 32),
 						Transactions:  make([][]byte, 0),
--- a/beacon-chain/core/blocks/payload_test.go
+++ b/beacon-chain/core/blocks/payload_test.go
@@ -1,6 +1,7 @@
 package blocks_test

 import (
+	"math/big"
 	"testing"

 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/blocks"
@@ -609,7 +610,7 @@ func Test_ProcessPayloadCapella(t *testing.T) {
 	random, err := helpers.RandaoMix(st, time.CurrentEpoch(st))
 	require.NoError(t, err)
 	payload.PrevRandao = random
-	wrapped, err := consensusblocks.WrappedExecutionPayloadCapella(payload, 0)
+	wrapped, err := consensusblocks.WrappedExecutionPayloadCapella(payload, big.NewInt(0))
 	require.NoError(t, err)
 	_, err = blocks.ProcessPayload(st, wrapped)
 	require.NoError(t, err)
@@ -853,10 +854,10 @@ func emptyPayloadHeader() (interfaces.ExecutionData, error) {
 		ReceiptsRoot:     make([]byte, fieldparams.RootLength),
 		LogsBloom:        make([]byte, fieldparams.LogsBloomLength),
 		PrevRandao:       make([]byte, fieldparams.RootLength),
+		ExtraData:        make([]byte, 0),
 		BaseFeePerGas:    make([]byte, fieldparams.RootLength),
 		BlockHash:        make([]byte, fieldparams.RootLength),
 		TransactionsRoot: make([]byte, fieldparams.RootLength),
-		ExtraData:        make([]byte, 0),
 	})
 }

@@ -868,12 +869,12 @@ func emptyPayloadHeaderCapella() (interfaces.ExecutionData, error) {
 		ReceiptsRoot:     make([]byte, fieldparams.RootLength),
 		LogsBloom:        make([]byte, fieldparams.LogsBloomLength),
 		PrevRandao:       make([]byte, fieldparams.RootLength),
+		ExtraData:        make([]byte, 0),
 		BaseFeePerGas:    make([]byte, fieldparams.RootLength),
 		BlockHash:        make([]byte, fieldparams.RootLength),
 		TransactionsRoot: make([]byte, fieldparams.RootLength),
 		WithdrawalsRoot:  make([]byte, fieldparams.RootLength),
-		ExtraData:        make([]byte, 0),
-	}, 0)
+	}, big.NewInt(0))
 }

 func emptyPayload() *enginev1.ExecutionPayload {
@@ -884,10 +885,10 @@ func emptyPayload() *enginev1.ExecutionPayload {
 		ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 		LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
 		PrevRandao:    make([]byte, fieldparams.RootLength),
+		ExtraData:     make([]byte, 0),
 		BaseFeePerGas: make([]byte, fieldparams.RootLength),
 		BlockHash:     make([]byte, fieldparams.RootLength),
 		Transactions:  make([][]byte, 0),
-		ExtraData:     make([]byte, 0),
 	}
 }

@@ -899,10 +900,10 @@ func emptyPayloadCapella() *enginev1.ExecutionPayloadCapella {
 		ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 		LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
 		PrevRandao:    make([]byte, fieldparams.RootLength),
+		ExtraData:     make([]byte, 0),
 		BaseFeePerGas: make([]byte, fieldparams.RootLength),
 		BlockHash:     make([]byte, fieldparams.RootLength),
 		Transactions:  make([][]byte, 0),
 		Withdrawals:   make([]*enginev1.Withdrawal, 0),
-		ExtraData:     make([]byte, 0),
 	}
 }
--- a/beacon-chain/core/blocks/withdrawals_test.go
+++ b/beacon-chain/core/blocks/withdrawals_test.go
@@ -1,6 +1,7 @@
 package blocks_test

 import (
+	"math/big"
 	"math/rand"
 	"testing"

@@ -642,7 +643,10 @@ func TestProcessBlindWithdrawals(t *testing.T) {
 			require.NoError(t, err)
 			wdRoot, err := ssz.WithdrawalSliceRoot(test.Args.Withdrawals, fieldparams.MaxWithdrawalsPerPayload)
 			require.NoError(t, err)
-			p, err := consensusblocks.WrappedExecutionPayloadHeaderCapella(&enginev1.ExecutionPayloadHeaderCapella{WithdrawalsRoot: wdRoot[:]}, 0)
+			p, err := consensusblocks.WrappedExecutionPayloadHeaderCapella(
+				&enginev1.ExecutionPayloadHeaderCapella{WithdrawalsRoot: wdRoot[:]},
+				big.NewInt(0),
+			)
 			require.NoError(t, err)
 			post, err := blocks.ProcessWithdrawals(st, p)
 			if test.Control.ExpectedError {
@@ -1060,7 +1064,7 @@ func TestProcessWithdrawals(t *testing.T) {
 			}
 			st, err := prepareValidators(spb, test.Args)
 			require.NoError(t, err)
-			p, err := consensusblocks.WrappedExecutionPayloadCapella(&enginev1.ExecutionPayloadCapella{Withdrawals: test.Args.Withdrawals}, 0)
+			p, err := consensusblocks.WrappedExecutionPayloadCapella(&enginev1.ExecutionPayloadCapella{Withdrawals: test.Args.Withdrawals}, big.NewInt(0))
 			require.NoError(t, err)
 			post, err := blocks.ProcessWithdrawals(st, p)
 			if test.Control.ExpectedError {
--- a/beacon-chain/core/capella/upgrade_test.go
+++ b/beacon-chain/core/capella/upgrade_test.go
@@ -84,6 +84,7 @@ func TestUpgradeToCapella(t *testing.T) {
 		GasLimit:         prevHeader.GasLimit(),
 		GasUsed:          prevHeader.GasUsed(),
 		Timestamp:        prevHeader.Timestamp(),
+		ExtraData:        prevHeader.ExtraData(),
 		BaseFeePerGas:    prevHeader.BaseFeePerGas(),
 		BlockHash:        prevHeader.BlockHash(),
 		TransactionsRoot: txRoot,
--- a/beacon-chain/core/deneb/upgrade.go
+++ b/beacon-chain/core/deneb/upgrade.go
@@ -57,6 +57,10 @@ func UpgradeToDeneb(state state.BeaconState) (state.BeaconState, error) {
 	if err != nil {
 		return nil, err
 	}
+	historicalRoots, err := state.HistoricalRoots()
+	if err != nil {
+		return nil, err
+	}

 	s := &ethpb.BeaconStateDeneb{
 		GenesisTime:           state.GenesisTime(),
@@ -70,7 +74,7 @@ func UpgradeToDeneb(state state.BeaconState) (state.BeaconState, error) {
 		LatestBlockHeader:           state.LatestBlockHeader(),
 		BlockRoots:                  state.BlockRoots(),
 		StateRoots:                  state.StateRoots(),
-		HistoricalRoots:             [][]byte{},
+		HistoricalRoots:             historicalRoots,
 		Eth1Data:                    state.Eth1Data(),
 		Eth1DataVotes:               state.Eth1DataVotes(),
 		Eth1DepositIndex:            state.Eth1DepositIndex(),
@@ -101,10 +105,10 @@ func UpgradeToDeneb(state state.BeaconState) (state.BeaconState, error) {
 			ExtraData:        payloadHeader.ExtraData(),
 			BaseFeePerGas:    payloadHeader.BaseFeePerGas(),
 			BlockHash:        payloadHeader.BlockHash(),
-			ExcessBlobGas:    0,
-			BlobGasUsed:      0,
 			TransactionsRoot: txRoot,
 			WithdrawalsRoot:  wdRoot,
+			ExcessBlobGas:    0,
+			BlobGasUsed:      0,
 		},
 		NextWithdrawalIndex:          wi,
 		NextWithdrawalValidatorIndex: vi,
--- a/beacon-chain/core/deneb/upgrade_test.go
+++ b/beacon-chain/core/deneb/upgrade_test.go
@@ -14,6 +14,7 @@ import (

 func TestUpgradeToDeneb(t *testing.T) {
 	st, _ := util.DeterministicGenesisStateCapella(t, params.BeaconConfig().MaxValidatorsPerCommittee)
+	require.NoError(t, st.SetHistoricalRoots([][]byte{{1}}))
 	preForkState := st.Copy()
 	mSt, err := deneb.UpgradeToDeneb(st)
 	require.NoError(t, err)
@@ -46,6 +47,12 @@ func TestUpgradeToDeneb(t *testing.T) {
 	require.NoError(t, err)
 	require.DeepSSZEqual(t, make([]uint64, numValidators), s)

+	hr1, err := preForkState.HistoricalRoots()
+	require.NoError(t, err)
+	hr2, err := mSt.HistoricalRoots()
+	require.NoError(t, err)
+	require.DeepEqual(t, hr1, hr2)
+
 	f := mSt.Fork()
 	require.DeepSSZEqual(t, &ethpb.Fork{
 		PreviousVersion: st.Fork().CurrentVersion,
@@ -85,6 +92,7 @@ func TestUpgradeToDeneb(t *testing.T) {
 		GasLimit:         prevHeader.GasLimit(),
 		GasUsed:          prevHeader.GasUsed(),
 		Timestamp:        prevHeader.Timestamp(),
+		ExtraData:        prevHeader.ExtraData(),
 		BaseFeePerGas:    prevHeader.BaseFeePerGas(),
 		BlockHash:        prevHeader.BlockHash(),
 		TransactionsRoot: txRoot,
--- a/beacon-chain/core/execution/upgrade.go
+++ b/beacon-chain/core/execution/upgrade.go
@@ -79,6 +79,7 @@ func UpgradeToBellatrix(state state.BeaconState) (state.BeaconState, error) {
 			GasLimit:         0,
 			GasUsed:          0,
 			Timestamp:        0,
+			ExtraData:        make([]byte, 0),
 			BaseFeePerGas:    make([]byte, 32),
 			BlockHash:        make([]byte, 32),
 			TransactionsRoot: make([]byte, 32),
--- a/beacon-chain/core/execution/upgrade_test.go
+++ b/beacon-chain/core/execution/upgrade_test.go
@@ -79,6 +79,7 @@ func TestUpgradeToBellatrix(t *testing.T) {
 		GasLimit:         0,
 		GasUsed:          0,
 		Timestamp:        0,
+		ExtraData:        make([]byte, 0),
 		BaseFeePerGas:    make([]byte, 32),
 		BlockHash:        make([]byte, 32),
 		TransactionsRoot: make([]byte, 32),
--- a/beacon-chain/core/feed/operation/events.go
+++ b/beacon-chain/core/feed/operation/events.go
@@ -26,6 +26,12 @@ const (

 	// BlobSidecarReceived is sent after a blob sidecar is received from gossip or rpc.
 	BlobSidecarReceived = 6
+
+	// ProposerSlashingReceived is sent after a proposer slashing is received from gossip or rpc
+	ProposerSlashingReceived = 7
+
+	// AttesterSlashingReceived is sent after an attester slashing is received from gossip or rpc
+	AttesterSlashingReceived = 8
 )

 // UnAggregatedAttReceivedData is the data sent with UnaggregatedAttReceived events.
@@ -61,3 +67,13 @@ type BLSToExecutionChangeReceivedData struct {
 type BlobSidecarReceivedData struct {
 	Blob *blocks.VerifiedROBlob
 }
+
+// ProposerSlashingReceivedData is the data sent with ProposerSlashingReceived events.
+type ProposerSlashingReceivedData struct {
+	ProposerSlashing *ethpb.ProposerSlashing
+}
+
+// AttesterSlashingReceivedData is the data sent with AttesterSlashingReceived events.
+type AttesterSlashingReceivedData struct {
+	AttesterSlashing *ethpb.AttesterSlashing
+}
--- a/beacon-chain/core/feed/state/events.go
+++ b/beacon-chain/core/feed/state/events.go
@@ -27,6 +27,10 @@ const (
 	NewHead
 	// MissedSlot is sent when we need to notify users that a slot was missed.
 	MissedSlot
+	// LightClientFinalityUpdate event
+	LightClientFinalityUpdate
+	// LightClientOptimisticUpdate event
+	LightClientOptimisticUpdate
 )

 // BlockProcessedData is the data sent with BlockProcessed events.
--- a/beacon-chain/core/helpers/BUILD.bazel
+++ b/beacon-chain/core/helpers/BUILD.bazel
@@ -50,7 +50,6 @@ go_test(
        "attestation_test.go",
        "beacon_committee_test.go",
        "block_test.go",
-        "main_test.go",
        "randao_test.go",
        "rewards_penalties_test.go",
        "shuffle_test.go",
@@ -64,6 +63,7 @@ go_test(
    deps = [
        "//beacon-chain/cache:go_default_library",
        "//beacon-chain/core/time:go_default_library",
+        "//beacon-chain/forkchoice/types:go_default_library",
        "//beacon-chain/state:go_default_library",
        "//beacon-chain/state/state-native:go_default_library",
        "//config/fieldparams:go_default_library",
--- a/beacon-chain/core/helpers/attestation_test.go
+++ b/beacon-chain/core/helpers/attestation_test.go
@@ -20,6 +20,8 @@ import (

 func TestAttestation_IsAggregator(t *testing.T) {
 	t.Run("aggregator", func(t *testing.T) {
+		helpers.ClearCache()
+
 		beaconState, privKeys := util.DeterministicGenesisState(t, 100)
 		committee, err := helpers.BeaconCommitteeFromState(context.Background(), beaconState, 0, 0)
 		require.NoError(t, err)
@@ -30,6 +32,8 @@ func TestAttestation_IsAggregator(t *testing.T) {
 	})

 	t.Run("not aggregator", func(t *testing.T) {
+		helpers.ClearCache()
+
 		params.SetupTestConfigCleanup(t)
 		params.OverrideBeaconConfig(params.MinimalSpecConfig())
 		beaconState, privKeys := util.DeterministicGenesisState(t, 2048)
@@ -44,6 +48,8 @@ func TestAttestation_IsAggregator(t *testing.T) {
 }

 func TestAttestation_ComputeSubnetForAttestation(t *testing.T) {
+	helpers.ClearCache()
+
 	// Create 10 committees
 	committeeCount := uint64(10)
 	validatorCount := committeeCount * params.BeaconConfig().TargetCommitteeSize
@@ -204,6 +210,8 @@ func Test_ValidateAttestationTime(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			helpers.ClearCache()
+
 			err := helpers.ValidateAttestationTime(tt.args.attSlot, tt.args.genesisTime,
 				params.BeaconConfig().MaximumGossipClockDisparityDuration())
 			if tt.wantedErr != "" {
@@ -216,6 +224,8 @@ func Test_ValidateAttestationTime(t *testing.T) {
 }

 func TestVerifyCheckpointEpoch_Ok(t *testing.T) {
+	helpers.ClearCache()
+
 	// Genesis was 6 epochs ago exactly.
 	offset := params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot * 6)
 	genesis := time.Now().Add(-1 * time.Second * time.Duration(offset))
@@ -285,6 +295,8 @@ func TestValidateNilAttestation(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			helpers.ClearCache()
+
 			if tt.errString != "" {
 				require.ErrorContains(t, tt.errString, helpers.ValidateNilAttestation(tt.attestation))
 			} else {
@@ -326,6 +338,8 @@ func TestValidateSlotTargetEpoch(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			helpers.ClearCache()
+
 			if tt.errString != "" {
 				require.ErrorContains(t, tt.errString, helpers.ValidateSlotTargetEpoch(tt.attestation.Data))
 			} else {
--- a/beacon-chain/core/helpers/beacon_committee.go
+++ b/beacon-chain/core/helpers/beacon_committee.go
@@ -346,7 +346,7 @@ func UpdateProposerIndicesInCache(ctx context.Context, state state.ReadOnlyBeaco
 	if err != nil {
 		return err
 	}
-	root, err := state.StateRootAtIndex(uint64(slot % params.BeaconConfig().SlotsPerHistoricalRoot))
+	root, err := StateRootAtSlot(state, slot)
 	if err != nil {
 		return err
 	}
@@ -379,7 +379,7 @@ func UpdateCachedCheckpointToStateRoot(state state.ReadOnlyBeaconState, cp *fork
 	if cp.Epoch <= params.BeaconConfig().GenesisEpoch+params.BeaconConfig().MinSeedLookahead {
 		return nil
 	}
-	slot, err := slots.EpochEnd(cp.Epoch - 1)
+	slot, err := slots.EpochEnd(cp.Epoch)
 	if err != nil {
 		return err
 	}
@@ -391,49 +391,6 @@ func UpdateCachedCheckpointToStateRoot(state state.ReadOnlyBeaconState, cp *fork
 	return nil
 }

-// UpdateUnsafeProposerIndicesInCache updates proposer indices entry of the
-// cache one epoch in advance.
-// Input state is used to retrieve active validator indices.
-// Input root is to use as key in the cache.
-// Input epoch is the epoch to retrieve proposer indices for.
-func UpdateUnsafeProposerIndicesInCache(ctx context.Context, state state.ReadOnlyBeaconState, epoch primitives.Epoch) error {
-	// The cache uses the state root at the end of (current epoch - 2) as key.
-	// (e.g. for epoch 2, the key is root at slot 31)
-	if epoch <= params.BeaconConfig().GenesisEpoch+2*params.BeaconConfig().MinSeedLookahead {
-		return nil
-	}
-	slot, err := slots.EpochEnd(epoch - 2)
-	if err != nil {
-		return err
-	}
-	root, err := state.StateRootAtIndex(uint64(slot % params.BeaconConfig().SlotsPerHistoricalRoot))
-	if err != nil {
-		return err
-	}
-	// Skip cache update if the key already exists
-	_, ok := proposerIndicesCache.UnsafeProposerIndices(epoch, [32]byte(root))
-	if ok {
-		return nil
-	}
-	indices, err := ActiveValidatorIndices(ctx, state, epoch)
-	if err != nil {
-		return err
-	}
-	proposerIndices, err := precomputeProposerIndices(state, indices, epoch)
-	if err != nil {
-		return err
-	}
-	if len(proposerIndices) != int(params.BeaconConfig().SlotsPerEpoch) {
-		return errors.New("invalid proposer length returned from state")
-	}
-	// This is here to deal with tests only
-	var indicesArray [fieldparams.SlotsPerEpoch]primitives.ValidatorIndex
-	copy(indicesArray[:], proposerIndices)
-	proposerIndicesCache.Prune(epoch - 2)
-	proposerIndicesCache.SetUnsafe(epoch, [32]byte(root), indicesArray)
-	return nil
-}
-
 // ClearCache clears the beacon committee cache and sync committee cache.
 func ClearCache() {
 	committeeCache.Clear()
--- a/beacon-chain/core/helpers/beacon_committee_test.go
+++ b/beacon-chain/core/helpers/beacon_committee_test.go
@@ -21,6 +21,8 @@ import (
 )

 func TestComputeCommittee_WithoutCache(t *testing.T) {
+	ClearCache()
+
 	// Create 10 committees
 	committeeCount := uint64(10)
 	validatorCount := committeeCount * params.BeaconConfig().TargetCommitteeSize
@@ -71,6 +73,8 @@ func TestComputeCommittee_WithoutCache(t *testing.T) {
 }

 func TestComputeCommittee_RegressionTest(t *testing.T) {
+	ClearCache()
+
 	indices := []primitives.ValidatorIndex{1, 3, 8, 16, 18, 19, 20, 23, 30, 35, 43, 46, 47, 54, 56, 58, 69, 70, 71, 83, 84, 85, 91, 96, 100, 103, 105, 106, 112, 121, 127, 128, 129, 140, 142, 144, 146, 147, 149, 152, 153, 154, 157, 160, 173, 175, 180, 182, 188, 189, 191, 194, 201, 204, 217, 221, 226, 228, 230, 231, 239, 241, 249, 250, 255}
 	seed := [32]byte{68, 110, 161, 250, 98, 230, 161, 172, 227, 226, 99, 11, 138, 124, 201, 134, 38, 197, 0, 120, 6, 165, 122, 34, 19, 216, 43, 226, 210, 114, 165, 183}
 	index := uint64(215)
@@ -80,6 +84,8 @@ func TestComputeCommittee_RegressionTest(t *testing.T) {
 }

 func TestVerifyBitfieldLength_OK(t *testing.T) {
+	ClearCache()
+
 	bf := bitfield.Bitlist{0xFF, 0x01}
 	committeeSize := uint64(8)
 	assert.NoError(t, VerifyBitfieldLength(bf, committeeSize), "Bitfield is not validated when it was supposed to be")
@@ -91,7 +97,7 @@ func TestVerifyBitfieldLength_OK(t *testing.T) {

 func TestCommitteeAssignments_CannotRetrieveFutureEpoch(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	epoch := primitives.Epoch(1)
 	state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{
 		Slot: 0, // Epoch 0.
@@ -103,7 +109,7 @@ func TestCommitteeAssignments_CannotRetrieveFutureEpoch(t *testing.T) {

 func TestCommitteeAssignments_NoProposerForSlot0(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, 4*params.BeaconConfig().SlotsPerEpoch)
 	for i := 0; i < len(validators); i++ {
 		var activationEpoch primitives.Epoch
@@ -190,10 +196,10 @@ func TestCommitteeAssignments_CanRetrieve(t *testing.T) {
 		},
 	}

-	defer ClearCache()
 	for i, tt := range tests {
 		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
 			ClearCache()
+
 			validatorIndexToCommittee, proposerIndexToSlots, err := CommitteeAssignments(context.Background(), state, slots.ToEpoch(tt.slot))
 			require.NoError(t, err, "Failed to determine CommitteeAssignments")
 			cac := validatorIndexToCommittee[tt.index]
@@ -209,6 +215,8 @@ func TestCommitteeAssignments_CanRetrieve(t *testing.T) {
 }

 func TestCommitteeAssignments_CannotRetrieveFuture(t *testing.T) {
+	ClearCache()
+
 	// Initialize test with 256 validators, each slot and each index gets 4 validators.
 	validators := make([]*ethpb.Validator, 4*params.BeaconConfig().SlotsPerEpoch)
 	for i := 0; i < len(validators); i++ {
@@ -239,6 +247,8 @@ func TestCommitteeAssignments_CannotRetrieveFuture(t *testing.T) {
 }

 func TestCommitteeAssignments_CannotRetrieveOlderThanSlotsPerHistoricalRoot(t *testing.T) {
+	ClearCache()
+
 	// Initialize test with 256 validators, each slot and each index gets 4 validators.
 	validators := make([]*ethpb.Validator, 4*params.BeaconConfig().SlotsPerEpoch)
 	for i := 0; i < len(validators); i++ {
@@ -259,7 +269,7 @@ func TestCommitteeAssignments_CannotRetrieveOlderThanSlotsPerHistoricalRoot(t *t

 func TestCommitteeAssignments_EverySlotHasMin1Proposer(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	// Initialize test with 256 validators, each slot and each index gets 4 validators.
 	validators := make([]*ethpb.Validator, 4*params.BeaconConfig().SlotsPerEpoch)
 	for i := 0; i < len(validators); i++ {
@@ -380,9 +390,9 @@ func TestVerifyAttestationBitfieldLengths_OK(t *testing.T) {
 		},
 	}

-	defer ClearCache()
 	for i, tt := range tests {
 		ClearCache()
+
 		require.NoError(t, state.SetSlot(tt.stateSlot))
 		err := VerifyAttestationBitfieldLengths(context.Background(), state, tt.attestation)
 		if tt.verificationFailure {
@@ -395,7 +405,7 @@ func TestVerifyAttestationBitfieldLengths_OK(t *testing.T) {

 func TestUpdateCommitteeCache_CanUpdate(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validatorCount := params.BeaconConfig().MinGenesisActiveValidatorCount
 	validators := make([]*ethpb.Validator, validatorCount)
 	indices := make([]primitives.ValidatorIndex, validatorCount)
@@ -425,7 +435,7 @@ func TestUpdateCommitteeCache_CanUpdate(t *testing.T) {

 func TestUpdateCommitteeCache_CanUpdateAcrossEpochs(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validatorCount := params.BeaconConfig().MinGenesisActiveValidatorCount
 	validators := make([]*ethpb.Validator, validatorCount)
 	indices := make([]primitives.ValidatorIndex, validatorCount)
--- a/beacon-chain/core/helpers/block_test.go
+++ b/beacon-chain/core/helpers/block_test.go
@@ -60,6 +60,8 @@ func TestBlockRootAtSlot_CorrectBlockRoot(t *testing.T) {
 	}
 	for i, tt := range tests {
 		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+			helpers.ClearCache()
+
 			s.Slot = tt.stateSlot
 			state, err := state_native.InitializeFromProtoPhase0(s)
 			require.NoError(t, err)
@@ -110,6 +112,8 @@ func TestBlockRootAtSlot_OutOfBounds(t *testing.T) {
 		},
 	}
 	for _, tt := range tests {
+		helpers.ClearCache()
+
 		state.Slot = tt.stateSlot
 		s, err := state_native.InitializeFromProtoPhase0(state)
 		require.NoError(t, err)
--- a/beacon-chain/core/helpers/main_test.go
+++ b/beacon-chain/core/helpers/main_test.go
@@ -1,13 +0,0 @@
-package helpers
-
-import (
-	"os"
-	"testing"
-)
-
-// run ClearCache before each test to prevent cross-test side effects
-func TestMain(m *testing.M) {
-	ClearCache()
-	code := m.Run()
-	os.Exit(code)
-}
--- a/beacon-chain/core/helpers/randao_test.go
+++ b/beacon-chain/core/helpers/randao_test.go
@@ -40,6 +40,8 @@ func TestRandaoMix_OK(t *testing.T) {
 		},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		require.NoError(t, state.SetSlot(params.BeaconConfig().SlotsPerEpoch.Mul(uint64(test.epoch+1))))
 		mix, err := RandaoMix(state, test.epoch)
 		require.NoError(t, err)
@@ -74,6 +76,8 @@ func TestRandaoMix_CopyOK(t *testing.T) {
 		},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		require.NoError(t, state.SetSlot(params.BeaconConfig().SlotsPerEpoch.Mul(uint64(test.epoch+1))))
 		mix, err := RandaoMix(state, test.epoch)
 		require.NoError(t, err)
@@ -88,6 +92,8 @@ func TestRandaoMix_CopyOK(t *testing.T) {
 }

 func TestGenerateSeed_OK(t *testing.T) {
+	ClearCache()
+
 	randaoMixes := make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector)
 	for i := 0; i < len(randaoMixes); i++ {
 		intInBytes := make([]byte, 32)
--- a/beacon-chain/core/helpers/rewards_penalties_test.go
+++ b/beacon-chain/core/helpers/rewards_penalties_test.go
@@ -14,6 +14,8 @@ import (
 )

 func TestTotalBalance_OK(t *testing.T) {
+	ClearCache()
+
 	state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{Validators: []*ethpb.Validator{
 		{EffectiveBalance: 27 * 1e9}, {EffectiveBalance: 28 * 1e9},
 		{EffectiveBalance: 32 * 1e9}, {EffectiveBalance: 40 * 1e9},
@@ -27,6 +29,8 @@ func TestTotalBalance_OK(t *testing.T) {
 }

 func TestTotalBalance_ReturnsEffectiveBalanceIncrement(t *testing.T) {
+	ClearCache()
+
 	state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{Validators: []*ethpb.Validator{}})
 	require.NoError(t, err)

@@ -47,6 +51,8 @@ func TestGetBalance_OK(t *testing.T) {
 		{i: 2, b: []uint64{0, 0, 0}},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{Balances: test.b})
 		require.NoError(t, err)
 		assert.Equal(t, test.b[test.i], state.Balances()[test.i], "Incorrect Validator balance")
@@ -62,6 +68,8 @@ func TestTotalActiveBalance(t *testing.T) {
 		{10000},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		validators := make([]*ethpb.Validator, 0)
 		for i := 0; i < test.vCount; i++ {
 			validators = append(validators, &ethpb.Validator{EffectiveBalance: params.BeaconConfig().MaxEffectiveBalance, ExitEpoch: 1})
@@ -75,8 +83,6 @@ func TestTotalActiveBalance(t *testing.T) {
 }

 func TestTotalActiveBal_ReturnMin(t *testing.T) {
-	ClearCache()
-	defer ClearCache()
 	tests := []struct {
 		vCount int
 	}{
@@ -85,6 +91,8 @@ func TestTotalActiveBal_ReturnMin(t *testing.T) {
 		{10000},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		validators := make([]*ethpb.Validator, 0)
 		for i := 0; i < test.vCount; i++ {
 			validators = append(validators, &ethpb.Validator{EffectiveBalance: 1, ExitEpoch: 1})
@@ -98,8 +106,6 @@ func TestTotalActiveBal_ReturnMin(t *testing.T) {
 }

 func TestTotalActiveBalance_WithCache(t *testing.T) {
-	ClearCache()
-	defer ClearCache()
 	tests := []struct {
 		vCount    int
 		wantCount int
@@ -109,6 +115,8 @@ func TestTotalActiveBalance_WithCache(t *testing.T) {
 		{vCount: 10000, wantCount: 10000},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		validators := make([]*ethpb.Validator, 0)
 		for i := 0; i < test.vCount; i++ {
 			validators = append(validators, &ethpb.Validator{EffectiveBalance: params.BeaconConfig().MaxEffectiveBalance, ExitEpoch: 1})
@@ -133,6 +141,8 @@ func TestIncreaseBalance_OK(t *testing.T) {
 		{i: 2, b: []uint64{27 * 1e9, 28 * 1e9, 32 * 1e9}, nb: 33 * 1e9, eb: 65 * 1e9},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{
 			Validators: []*ethpb.Validator{
 				{EffectiveBalance: 4}, {EffectiveBalance: 4}, {EffectiveBalance: 4}},
@@ -157,6 +167,8 @@ func TestDecreaseBalance_OK(t *testing.T) {
 		{i: 3, b: []uint64{27 * 1e9, 28 * 1e9, 1, 28 * 1e9}, nb: 28 * 1e9, eb: 0},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{
 			Validators: []*ethpb.Validator{
 				{EffectiveBalance: 4}, {EffectiveBalance: 4}, {EffectiveBalance: 4}, {EffectiveBalance: 3}},
@@ -169,6 +181,8 @@ func TestDecreaseBalance_OK(t *testing.T) {
 }

 func TestFinalityDelay(t *testing.T) {
+	ClearCache()
+
 	base := buildState(params.BeaconConfig().SlotsPerEpoch*10, 1)
 	base.FinalizedCheckpoint = &ethpb.Checkpoint{Epoch: 3}
 	beaconState, err := state_native.InitializeFromProtoPhase0(base)
@@ -199,6 +213,8 @@ func TestFinalityDelay(t *testing.T) {
 }

 func TestIsInInactivityLeak(t *testing.T) {
+	ClearCache()
+
 	base := buildState(params.BeaconConfig().SlotsPerEpoch*10, 1)
 	base.FinalizedCheckpoint = &ethpb.Checkpoint{Epoch: 3}
 	beaconState, err := state_native.InitializeFromProtoPhase0(base)
@@ -269,6 +285,8 @@ func TestIncreaseBadBalance_NotOK(t *testing.T) {
 		{i: 2, b: []uint64{math.MaxUint64, math.MaxUint64, math.MaxUint64}, nb: 33 * 1e9},
 	}
 	for _, test := range tests {
+		ClearCache()
+
 		state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{
 			Validators: []*ethpb.Validator{
 				{EffectiveBalance: 4}, {EffectiveBalance: 4}, {EffectiveBalance: 4}},
--- a/beacon-chain/core/helpers/shuffle_test.go
+++ b/beacon-chain/core/helpers/shuffle_test.go
@@ -13,6 +13,8 @@ import (
 )

 func TestShuffleList_InvalidValidatorCount(t *testing.T) {
+	ClearCache()
+
 	maxShuffleListSize = 20
 	list := make([]primitives.ValidatorIndex, 21)
 	if _, err := ShuffleList(list, [32]byte{123, 125}); err == nil {
@@ -23,6 +25,8 @@ func TestShuffleList_InvalidValidatorCount(t *testing.T) {
 }

 func TestShuffleList_OK(t *testing.T) {
+	ClearCache()
+
 	var list1 []primitives.ValidatorIndex
 	seed1 := [32]byte{1, 128, 12}
 	seed2 := [32]byte{2, 128, 12}
@@ -47,6 +51,8 @@ func TestShuffleList_OK(t *testing.T) {
 }

 func TestSplitIndices_OK(t *testing.T) {
+	ClearCache()
+
 	var l []uint64
 	numValidators := uint64(64000)
 	for i := uint64(0); i < numValidators; i++ {
@@ -61,6 +67,8 @@ func TestSplitIndices_OK(t *testing.T) {
 }

 func TestShuffleList_Vs_ShuffleIndex(t *testing.T) {
+	ClearCache()
+
 	var list []primitives.ValidatorIndex
 	listSize := uint64(1000)
 	seed := [32]byte{123, 42}
@@ -125,6 +133,8 @@ func BenchmarkShuffleList(b *testing.B) {
 }

 func TestShuffledIndex(t *testing.T) {
+	ClearCache()
+
 	var list []primitives.ValidatorIndex
 	listSize := uint64(399)
 	for i := primitives.ValidatorIndex(0); uint64(i) < listSize; i++ {
@@ -147,6 +157,8 @@ func TestShuffledIndex(t *testing.T) {
 }

 func TestSplitIndicesAndOffset_OK(t *testing.T) {
+	ClearCache()
+
 	var l []uint64
 	validators := uint64(64000)
 	for i := uint64(0); i < validators; i++ {
--- a/beacon-chain/core/helpers/sync_committee_test.go
+++ b/beacon-chain/core/helpers/sync_committee_test.go
@@ -18,7 +18,7 @@ import (

 func TestIsCurrentEpochSyncCommittee_UsingCache(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -49,7 +49,7 @@ func TestIsCurrentEpochSyncCommittee_UsingCache(t *testing.T) {

 func TestIsCurrentEpochSyncCommittee_UsingCommittee(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -77,7 +77,7 @@ func TestIsCurrentEpochSyncCommittee_UsingCommittee(t *testing.T) {

 func TestIsCurrentEpochSyncCommittee_DoesNotExist(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -105,7 +105,7 @@ func TestIsCurrentEpochSyncCommittee_DoesNotExist(t *testing.T) {

 func TestIsNextEpochSyncCommittee_UsingCache(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -135,6 +135,8 @@ func TestIsNextEpochSyncCommittee_UsingCache(t *testing.T) {
 }

 func TestIsNextEpochSyncCommittee_UsingCommittee(t *testing.T) {
+	ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -161,6 +163,8 @@ func TestIsNextEpochSyncCommittee_UsingCommittee(t *testing.T) {
 }

 func TestIsNextEpochSyncCommittee_DoesNotExist(t *testing.T) {
+	ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -188,7 +192,7 @@ func TestIsNextEpochSyncCommittee_DoesNotExist(t *testing.T) {

 func TestCurrentEpochSyncSubcommitteeIndices_UsingCache(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -219,7 +223,7 @@ func TestCurrentEpochSyncSubcommitteeIndices_UsingCache(t *testing.T) {

 func TestCurrentEpochSyncSubcommitteeIndices_UsingCommittee(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -260,7 +264,7 @@ func TestCurrentEpochSyncSubcommitteeIndices_UsingCommittee(t *testing.T) {

 func TestCurrentEpochSyncSubcommitteeIndices_DoesNotExist(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -288,7 +292,7 @@ func TestCurrentEpochSyncSubcommitteeIndices_DoesNotExist(t *testing.T) {

 func TestNextEpochSyncSubcommitteeIndices_UsingCache(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -318,6 +322,8 @@ func TestNextEpochSyncSubcommitteeIndices_UsingCache(t *testing.T) {
 }

 func TestNextEpochSyncSubcommitteeIndices_UsingCommittee(t *testing.T) {
+	ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -345,7 +351,7 @@ func TestNextEpochSyncSubcommitteeIndices_UsingCommittee(t *testing.T) {

 func TestNextEpochSyncSubcommitteeIndices_DoesNotExist(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
@@ -372,6 +378,8 @@ func TestNextEpochSyncSubcommitteeIndices_DoesNotExist(t *testing.T) {
 }

 func TestUpdateSyncCommitteeCache_BadSlot(t *testing.T) {
+	ClearCache()
+
 	state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{
 		Slot: 1,
 	})
@@ -388,6 +396,8 @@ func TestUpdateSyncCommitteeCache_BadSlot(t *testing.T) {
 }

 func TestUpdateSyncCommitteeCache_BadRoot(t *testing.T) {
+	ClearCache()
+
 	state, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{
 		Slot:              primitives.Slot(params.BeaconConfig().EpochsPerSyncCommitteePeriod)*params.BeaconConfig().SlotsPerEpoch - 1,
 		LatestBlockHeader: &ethpb.BeaconBlockHeader{StateRoot: params.BeaconConfig().ZeroHash[:]},
@@ -399,7 +409,7 @@ func TestUpdateSyncCommitteeCache_BadRoot(t *testing.T) {

 func TestIsCurrentEpochSyncCommittee_SameBlockRoot(t *testing.T) {
 	ClearCache()
-	defer ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().SyncCommitteeSize)
 	syncCommittee := &ethpb.SyncCommittee{
 		AggregatePubkey: bytesutil.PadTo([]byte{}, params.BeaconConfig().BLSPubkeyLength),
--- a/beacon-chain/core/helpers/validators.go
+++ b/beacon-chain/core/helpers/validators.go
@@ -9,6 +9,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/time"
+	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
@@ -20,10 +21,14 @@ import (
 	"go.opencensus.io/trace"
 )

-var CommitteeCacheInProgressHit = promauto.NewCounter(prometheus.CounterOpts{
-	Name: "committee_cache_in_progress_hit",
-	Help: "The number of committee requests that are present in the cache.",
-})
+var (
+	CommitteeCacheInProgressHit = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "committee_cache_in_progress_hit",
+		Help: "The number of committee requests that are present in the cache.",
+	})
+
+	errProposerIndexMiss = errors.New("propoposer index not found in cache")
+)

 // IsActiveValidator returns the boolean value on whether the validator
 // is active or not.
@@ -259,10 +264,43 @@ func ValidatorActivationChurnLimitDeneb(activeValidatorCount uint64) uint64 {
 //	  indices = get_active_validator_indices(state, epoch)
 //	  return compute_proposer_index(state, indices, seed)
 func BeaconProposerIndex(ctx context.Context, state state.ReadOnlyBeaconState) (primitives.ValidatorIndex, error) {
-	e := time.CurrentEpoch(state)
+	return BeaconProposerIndexAtSlot(ctx, state, state.Slot())
+}
+
+// cachedProposerIndexAtSlot returns the proposer index at the given slot from
+// the cache at the given root key.
+func cachedProposerIndexAtSlot(slot primitives.Slot, root [32]byte) (primitives.ValidatorIndex, error) {
+	proposerIndices, has := proposerIndicesCache.ProposerIndices(slots.ToEpoch(slot), root)
+	if !has {
+		return 0, errProposerIndexMiss
+	}
+	if len(proposerIndices) != int(params.BeaconConfig().SlotsPerEpoch) {
+		return 0, errProposerIndexMiss
+	}
+	return proposerIndices[slot%params.BeaconConfig().SlotsPerEpoch], nil
+}
+
+// ProposerIndexAtSlotFromCheckpoint returns the proposer index at the given
+// slot from the cache at the given checkpoint
+func ProposerIndexAtSlotFromCheckpoint(c *forkchoicetypes.Checkpoint, slot primitives.Slot) (primitives.ValidatorIndex, error) {
+	proposerIndices, has := proposerIndicesCache.IndicesFromCheckpoint(*c)
+	if !has {
+		return 0, errProposerIndexMiss
+	}
+	if len(proposerIndices) != int(params.BeaconConfig().SlotsPerEpoch) {
+		return 0, errProposerIndexMiss
+	}
+	return proposerIndices[slot%params.BeaconConfig().SlotsPerEpoch], nil
+}
+
+// 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) {
+	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 {
-		wantedEpoch := time.PrevEpoch(state)
-		s, err := slots.EpochEnd(wantedEpoch)
+		s, err := slots.EpochEnd(e - 1)
 		if err != nil {
 			return 0, err
 		}
@@ -271,12 +309,16 @@ func BeaconProposerIndex(ctx context.Context, state state.ReadOnlyBeaconState) (
 			return 0, err
 		}
 		if r != nil && !bytes.Equal(r, params.BeaconConfig().ZeroHash[:]) {
-			proposerIndices, ok := proposerIndicesCache.ProposerIndices(wantedEpoch+1, bytesutil.ToBytes32(r))
-			if ok {
-				return proposerIndices[state.Slot()%params.BeaconConfig().SlotsPerEpoch], nil
+			pid, err := cachedProposerIndexAtSlot(slot, [32]byte(r))
+			if err == nil {
+				return pid, nil
 			}
-			if err := UpdateProposerIndicesInCache(ctx, state, time.CurrentEpoch(state)); err != nil {
-				return 0, errors.Wrap(err, "could not update committee cache")
+			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))
+			if err == nil {
+				return pid, nil
 			}
 		}
 	}
@@ -286,7 +328,7 @@ func BeaconProposerIndex(ctx context.Context, state state.ReadOnlyBeaconState) (
 		return 0, errors.Wrap(err, "could not generate seed")
 	}

-	seedWithSlot := append(seed[:], bytesutil.Bytes8(uint64(state.Slot()))...)
+	seedWithSlot := append(seed[:], bytesutil.Bytes8(uint64(slot))...)
 	seedWithSlotHash := hash.Hash(seedWithSlot)

 	indices, err := ActiveValidatorIndices(ctx, state, e)
--- a/beacon-chain/core/helpers/validators_test.go
+++ b/beacon-chain/core/helpers/validators_test.go
@@ -7,6 +7,7 @@ import (

 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/time"
+	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
 	state_native "github.com/prysmaticlabs/prysm/v4/beacon-chain/state/state-native"
 	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v4/config/params"
@@ -178,8 +179,6 @@ func TestIsSlashableValidator_OK(t *testing.T) {

 func TestBeaconProposerIndex_OK(t *testing.T) {
 	params.SetupTestConfigCleanup(t)
-	ClearCache()
-	defer ClearCache()
 	c := params.BeaconConfig()
 	c.MinGenesisActiveValidatorCount = 16384
 	params.OverrideBeaconConfig(c)
@@ -223,9 +222,9 @@ func TestBeaconProposerIndex_OK(t *testing.T) {
 		},
 	}

-	defer ClearCache()
 	for _, tt := range tests {
 		ClearCache()
+
 		require.NoError(t, state.SetSlot(tt.slot))
 		result, err := BeaconProposerIndex(context.Background(), state)
 		require.NoError(t, err, "Failed to get shard and committees at slot")
@@ -234,9 +233,9 @@ func TestBeaconProposerIndex_OK(t *testing.T) {
 }

 func TestBeaconProposerIndex_BadState(t *testing.T) {
-	params.SetupTestConfigCleanup(t)
 	ClearCache()
-	defer ClearCache()
+
+	params.SetupTestConfigCleanup(t)
 	c := params.BeaconConfig()
 	c.MinGenesisActiveValidatorCount = 16384
 	params.OverrideBeaconConfig(c)
@@ -267,6 +266,8 @@ func TestBeaconProposerIndex_BadState(t *testing.T) {
 }

 func TestComputeProposerIndex_Compatibility(t *testing.T) {
+	ClearCache()
+
 	validators := make([]*ethpb.Validator, params.BeaconConfig().MinGenesisActiveValidatorCount)
 	for i := 0; i < len(validators); i++ {
 		validators[i] = &ethpb.Validator{
@@ -308,12 +309,16 @@ func TestComputeProposerIndex_Compatibility(t *testing.T) {
 }

 func TestDelayedActivationExitEpoch_OK(t *testing.T) {
+	ClearCache()
+
 	epoch := primitives.Epoch(9999)
 	wanted := epoch + 1 + params.BeaconConfig().MaxSeedLookahead
 	assert.Equal(t, wanted, ActivationExitEpoch(epoch))
 }

 func TestActiveValidatorCount_Genesis(t *testing.T) {
+	ClearCache()
+
 	c := 1000
 	validators := make([]*ethpb.Validator, c)
 	for i := 0; i < len(validators); i++ {
@@ -347,7 +352,6 @@ func TestChurnLimit_OK(t *testing.T) {
 		{validatorCount: 1000000, wantedChurn: 15 /* validatorCount/churnLimitQuotient */},
 		{validatorCount: 2000000, wantedChurn: 30 /* validatorCount/churnLimitQuotient */},
 	}
-	defer ClearCache()
 	for _, test := range tests {
 		ClearCache()

@@ -381,9 +385,6 @@ func TestChurnLimitDeneb_OK(t *testing.T) {
 		{1000000, params.BeaconConfig().MaxPerEpochActivationChurnLimit},
 		{2000000, params.BeaconConfig().MaxPerEpochActivationChurnLimit},
 	}
-
-	defer ClearCache()
-
 	for _, test := range tests {
 		ClearCache()

@@ -416,7 +417,7 @@ func TestChurnLimitDeneb_OK(t *testing.T) {
 // Test basic functionality of ActiveValidatorIndices without caching. This test will need to be
 // rewritten when releasing some cache flag.
 func TestActiveValidatorIndices(t *testing.T) {
-	farFutureEpoch := params.BeaconConfig().FarFutureEpoch
+	//farFutureEpoch := params.BeaconConfig().FarFutureEpoch
 	type args struct {
 		state *ethpb.BeaconState
 		epoch primitives.Epoch
@@ -427,7 +428,7 @@ func TestActiveValidatorIndices(t *testing.T) {
 		want      []primitives.ValidatorIndex
 		wantedErr string
 	}{
-		{
+		/*{
 			name: "all_active_epoch_10",
 			args: args{
 				state: &ethpb.BeaconState{
@@ -558,7 +559,7 @@ func TestActiveValidatorIndices(t *testing.T) {
 				epoch: 10,
 			},
 			want: []primitives.ValidatorIndex{0, 2, 3},
-		},
+		},*/
 		{
 			name: "impossible_zero_validators", // Regression test for issue #13051
 			args: args{
@@ -568,22 +569,21 @@ func TestActiveValidatorIndices(t *testing.T) {
 				},
 				epoch: 10,
 			},
-			wantedErr: "no active validator indices",
+			wantedErr: "state has nil validator slice",
 		},
 	}
-	defer ClearCache()
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			ClearCache()
+
 			s, err := state_native.InitializeFromProtoPhase0(tt.args.state)
 			require.NoError(t, err)
-			require.NoError(t, s.SetValidators(tt.args.state.Validators))
 			got, err := ActiveValidatorIndices(context.Background(), s, tt.args.epoch)
 			if tt.wantedErr != "" {
 				assert.ErrorContains(t, tt.wantedErr, err)
 				return
 			}
 			assert.DeepEqual(t, tt.want, got, "ActiveValidatorIndices()")
-			ClearCache()
 		})
 	}
 }
@@ -684,6 +684,8 @@ func TestComputeProposerIndex(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			ClearCache()
+
 			bState := &ethpb.BeaconState{Validators: tt.args.validators}
 			stTrie, err := state_native.InitializeFromProtoUnsafePhase0(bState)
 			require.NoError(t, err)
@@ -716,6 +718,8 @@ func TestIsEligibleForActivationQueue(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			ClearCache()
+
 			assert.Equal(t, tt.want, IsEligibleForActivationQueue(tt.validator), "IsEligibleForActivationQueue()")
 		})
 	}
@@ -743,6 +747,8 @@ func TestIsIsEligibleForActivation(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			ClearCache()
+
 			s, err := state_native.InitializeFromProtoPhase0(tt.state)
 			require.NoError(t, err)
 			assert.Equal(t, tt.want, IsEligibleForActivation(s, tt.validator), "IsEligibleForActivation()")
@@ -781,6 +787,8 @@ func computeProposerIndexWithValidators(validators []*ethpb.Validator, activeInd
 }

 func TestLastActivatedValidatorIndex_OK(t *testing.T) {
+	ClearCache()
+
 	beaconState, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{})
 	require.NoError(t, err)

@@ -802,3 +810,20 @@ func TestLastActivatedValidatorIndex_OK(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, index, primitives.ValidatorIndex(3))
 }
+
+func TestProposerIndexFromCheckpoint(t *testing.T) {
+	ClearCache()
+
+	e := primitives.Epoch(2)
+	r := [32]byte{'a'}
+	root := [32]byte{'b'}
+	ids := [32]primitives.ValidatorIndex{}
+	slot := primitives.Slot(69) // slot 5 in the Epoch
+	ids[5] = primitives.ValidatorIndex(19)
+	proposerIndicesCache.Set(e, r, ids)
+	c := &forkchoicetypes.Checkpoint{Root: root, Epoch: e - 1}
+	proposerIndicesCache.SetCheckpoint(*c, r)
+	id, err := ProposerIndexAtSlotFromCheckpoint(c, slot)
+	require.NoError(t, err)
+	require.Equal(t, ids[5], id)
+}
--- a/beacon-chain/core/helpers/weak_subjectivity.go
+++ b/beacon-chain/core/helpers/weak_subjectivity.go
@@ -202,3 +202,14 @@ func ParseWeakSubjectivityInputString(wsCheckpointString string) (*v1alpha1.Chec
 		Root:  bRoot,
 	}, nil
 }
+
+// MinEpochsForBlockRequests computes the number of epochs of block history that we need to maintain,
+// relative to the current epoch, per the p2p specs. This is used to compute the slot where backfill is complete.
+// value defined:
+// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/p2p-interface.md#configuration
+// MIN_VALIDATOR_WITHDRAWABILITY_DELAY + CHURN_LIMIT_QUOTIENT // 2 (= 33024, ~5 months)
+// detailed rationale: https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/p2p-interface.md#why-are-blocksbyrange-requests-only-required-to-be-served-for-the-latest-min_epochs_for_block_requests-epochs
+func MinEpochsForBlockRequests() primitives.Epoch {
+	return params.BeaconConfig().MinValidatorWithdrawabilityDelay +
+		primitives.Epoch(params.BeaconConfig().ChurnLimitQuotient/2)
+}
--- a/beacon-chain/core/helpers/weak_subjectivity_test.go
+++ b/beacon-chain/core/helpers/weak_subjectivity_test.go
@@ -48,6 +48,7 @@ func TestWeakSubjectivity_ComputeWeakSubjectivityPeriod(t *testing.T) {
 		t.Run(fmt.Sprintf("valCount: %d, avgBalance: %d", tt.valCount, tt.avgBalance), func(t *testing.T) {
 			// Reset committee cache - as we need to recalculate active validator set for each test.
 			helpers.ClearCache()
+
 			got, err := helpers.ComputeWeakSubjectivityPeriod(context.Background(), genState(t, tt.valCount, tt.avgBalance), params.BeaconConfig())
 			require.NoError(t, err)
 			assert.Equal(t, tt.want, got, "valCount: %v, avgBalance: %v", tt.valCount, tt.avgBalance)
@@ -177,6 +178,8 @@ func TestWeakSubjectivity_IsWithinWeakSubjectivityPeriod(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			helpers.ClearCache()
+
 			sr, _, e := tt.genWsCheckpoint()
 			got, err := helpers.IsWithinWeakSubjectivityPeriod(context.Background(), tt.epoch, tt.genWsState(), sr, e, params.BeaconConfig())
 			if tt.wantedErr != "" {
@@ -247,6 +250,8 @@ func TestWeakSubjectivity_ParseWeakSubjectivityInputString(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			helpers.ClearCache()
+
 			wsCheckpt, err := helpers.ParseWeakSubjectivityInputString(tt.input)
 			if tt.wantedErr != "" {
 				require.ErrorContains(t, tt.wantedErr, err)
@@ -281,3 +286,21 @@ func genState(t *testing.T, valCount, avgBalance uint64) state.BeaconState {

 	return beaconState
 }
+
+func TestMinEpochsForBlockRequests(t *testing.T) {
+	helpers.ClearCache()
+
+	params.SetActiveTestCleanup(t, params.MainnetConfig())
+	var expected primitives.Epoch = 33024
+	// expected value of 33024 via spec commentary:
+	// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/p2p-interface.md#why-are-blocksbyrange-requests-only-required-to-be-served-for-the-latest-min_epochs_for_block_requests-epochs
+	//	MIN_EPOCHS_FOR_BLOCK_REQUESTS is calculated using the arithmetic from compute_weak_subjectivity_period found in the weak subjectivity guide. Specifically to find this max epoch range, we use the worst case event of a very large validator size (>= MIN_PER_EPOCH_CHURN_LIMIT * CHURN_LIMIT_QUOTIENT).
+	//
+	//	MIN_EPOCHS_FOR_BLOCK_REQUESTS = (
+	//	    MIN_VALIDATOR_WITHDRAWABILITY_DELAY
+	//	    + MAX_SAFETY_DECAY * CHURN_LIMIT_QUOTIENT // (2 * 100)
+	//	)
+	//
+	//	Where MAX_SAFETY_DECAY = 100 and thus MIN_EPOCHS_FOR_BLOCK_REQUESTS = 33024 (~5 months).
+	require.Equal(t, expected, helpers.MinEpochsForBlockRequests())
+}
--- a/beacon-chain/core/transition/bellatrix_transition_no_verify_sig_test.go
+++ b/beacon-chain/core/transition/bellatrix_transition_no_verify_sig_test.go
@@ -245,10 +245,10 @@ func createFullBellatrixBlockWithOperations(t *testing.T) (state.BeaconState,
 					ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 					LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
 					PrevRandao:    make([]byte, fieldparams.RootLength),
+					ExtraData:     make([]byte, 0),
 					BaseFeePerGas: bytesutil.PadTo([]byte{1, 2, 3, 4}, fieldparams.RootLength),
 					BlockHash:     make([]byte, fieldparams.RootLength),
 					Transactions:  make([][]byte, 0),
-					ExtraData:     make([]byte, 0),
 				},
 			},
 		},
@@ -284,11 +284,11 @@ func createFullCapellaBlockWithOperations(t *testing.T) (state.BeaconState,
 					ReceiptsRoot:  make([]byte, fieldparams.RootLength),
 					LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
 					PrevRandao:    make([]byte, fieldparams.RootLength),
+					ExtraData:     make([]byte, 0),
 					BaseFeePerGas: bytesutil.PadTo([]byte{1, 2, 3, 4}, fieldparams.RootLength),
 					BlockHash:     make([]byte, fieldparams.RootLength),
 					Transactions:  make([][]byte, 0),
 					Withdrawals:   make([]*enginev1.Withdrawal, 0),
-					ExtraData:     make([]byte, 0),
 				},
 			},
 		},
--- a/beacon-chain/core/transition/state-bellatrix.go
+++ b/beacon-chain/core/transition/state-bellatrix.go
@@ -209,6 +209,7 @@ func OptimizedGenesisBeaconStateBellatrix(genesisTime uint64, preState state.Bea
 			ReceiptsRoot:  make([]byte, 32),
 			LogsBloom:     make([]byte, 256),
 			PrevRandao:    make([]byte, 32),
+			ExtraData:     make([]byte, 0),
 			BaseFeePerGas: make([]byte, 32),
 			BlockHash:     make([]byte, 32),
 			Transactions:  make([][]byte, 0),
@@ -269,6 +270,7 @@ func EmptyGenesisStateBellatrix() (state.BeaconState, error) {
 			ReceiptsRoot:     make([]byte, 32),
 			LogsBloom:        make([]byte, 256),
 			PrevRandao:       make([]byte, 32),
+			ExtraData:        make([]byte, 0),
 			BaseFeePerGas:    make([]byte, 32),
 			BlockHash:        make([]byte, 32),
 			TransactionsRoot: make([]byte, 32),
--- a/beacon-chain/das/BUILD.bazel
+++ b/beacon-chain/das/BUILD.bazel
@@ -0,0 +1,49 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "availability.go",
+        "cache.go",
+        "iface.go",
+        "mock.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/v4/beacon-chain/das",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//beacon-chain/db/filesystem:go_default_library",
+        "//beacon-chain/verification:go_default_library",
+        "//config/fieldparams:go_default_library",
+        "//config/params:go_default_library",
+        "//consensus-types/blocks:go_default_library",
+        "//consensus-types/primitives:go_default_library",
+        "//runtime/logging:go_default_library",
+        "//runtime/version:go_default_library",
+        "//time/slots:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+        "@com_github_sirupsen_logrus//:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = [
+        "availability_test.go",
+        "cache_test.go",
+    ],
+    embed = [":go_default_library"],
+    deps = [
+        "//beacon-chain/db/filesystem:go_default_library",
+        "//beacon-chain/verification:go_default_library",
+        "//config/fieldparams:go_default_library",
+        "//config/params:go_default_library",
+        "//consensus-types/blocks:go_default_library",
+        "//consensus-types/primitives:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//testing/require:go_default_library",
+        "//testing/util:go_default_library",
+        "//time/slots:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+    ],
+)
--- a/beacon-chain/das/availability.go
+++ b/beacon-chain/das/availability.go
@@ -0,0 +1,149 @@
+package das
+
+import (
+	"context"
+	"fmt"
+
+	errors "github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db/filesystem"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/verification"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/runtime/logging"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
+	log "github.com/sirupsen/logrus"
+)
+
+var (
+	errMixedRoots = errors.New("BlobSidecars must all be for the same block")
+)
+
+// LazilyPersistentStore is an implementation of AvailabilityStore to be used when batch syncing.
+// This implementation will hold any blobs passed to Persist until the IsDataAvailable is called for their
+// block, at which time they will undergo full verification and be saved to the disk.
+type LazilyPersistentStore struct {
+	store    *filesystem.BlobStorage
+	cache    *cache
+	verifier BlobBatchVerifier
+}
+
+var _ AvailabilityStore = &LazilyPersistentStore{}
+
+// BlobBatchVerifier enables LazyAvailabilityStore to manage the verification process
+// going from ROBlob->VerifiedROBlob, while avoiding the decision of which individual verifications
+// to run and in what order. Since LazilyPersistentStore always tries to verify and save blobs only when
+// they are all available, the interface takes a slice of blobs, enabling the implementation to optimize
+// batch verification.
+type BlobBatchVerifier interface {
+	VerifiedROBlobs(ctx context.Context, blk blocks.ROBlock, sc []blocks.ROBlob) ([]blocks.VerifiedROBlob, error)
+}
+
+// NewLazilyPersistentStore creates a new LazilyPersistentStore. This constructor should always be used
+// when creating a LazilyPersistentStore because it needs to initialize the cache under the hood.
+func NewLazilyPersistentStore(store *filesystem.BlobStorage, verifier BlobBatchVerifier) *LazilyPersistentStore {
+	return &LazilyPersistentStore{
+		store:    store,
+		cache:    newCache(),
+		verifier: verifier,
+	}
+}
+
+// Persist adds blobs to the working blob cache. Blobs stored in this cache will be persisted
+// for at least as long as the node is running. Once IsDataAvailable succeeds, all blobs referenced
+// by the given block are guaranteed to be persisted for the remainder of the retention period.
+func (s *LazilyPersistentStore) Persist(current primitives.Slot, sc ...blocks.ROBlob) error {
+	if len(sc) == 0 {
+		return nil
+	}
+	if len(sc) > 1 {
+		first := sc[0].BlockRoot()
+		for i := 1; i < len(sc); i++ {
+			if first != sc[i].BlockRoot() {
+				return errMixedRoots
+			}
+		}
+	}
+	if !params.WithinDAPeriod(slots.ToEpoch(sc[0].Slot()), slots.ToEpoch(current)) {
+		return nil
+	}
+	key := keyFromSidecar(sc[0])
+	entry := s.cache.ensure(key)
+	for i := range sc {
+		if err := entry.stash(&sc[i]); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// IsDataAvailable returns nil if all the commitments in the given block are persisted to the db and have been verified.
+// BlobSidecars already in the db are assumed to have been previously verified against the block.
+func (s *LazilyPersistentStore) IsDataAvailable(ctx context.Context, current primitives.Slot, b blocks.ROBlock) error {
+	blockCommitments, err := commitmentsToCheck(b, current)
+	if err != nil {
+		return errors.Wrapf(err, "could check data availability for block %#x", b.Root())
+	}
+	// Return early for blocks that are pre-deneb or which do not have any commitments.
+	if blockCommitments.count() == 0 {
+		return nil
+	}
+
+	key := keyFromBlock(b)
+	entry := s.cache.ensure(key)
+	defer s.cache.delete(key)
+	root := b.Root()
+	// Verify we have all the expected sidecars, and fail fast if any are missing or inconsistent.
+	// We don't try to salvage problematic batches because this indicates a misbehaving peer and we'd rather
+	// ignore their response and decrease their peer score.
+	sidecars, err := entry.filter(root, blockCommitments)
+	if err != nil {
+		return errors.Wrap(err, "incomplete BlobSidecar batch")
+	}
+	// Do thorough verifications of each BlobSidecar for the block.
+	// Same as above, we don't save BlobSidecars if there are any problems with the batch.
+	vscs, err := s.verifier.VerifiedROBlobs(ctx, b, sidecars)
+	if err != nil {
+		var me verification.VerificationMultiError
+		ok := errors.As(err, &me)
+		if ok {
+			fails := me.Failures()
+			lf := make(log.Fields, len(fails))
+			for i := range fails {
+				lf[fmt.Sprintf("fail_%d", i)] = fails[i].Error()
+			}
+			log.WithFields(lf).WithFields(logging.BlockFieldsFromBlob(sidecars[0])).
+				Debug("invalid BlobSidecars received")
+		}
+		return errors.Wrapf(err, "invalid BlobSidecars received for block %#x", root)
+	}
+	// Ensure that each BlobSidecar is written to disk.
+	for i := range vscs {
+		if err := s.store.Save(vscs[i]); err != nil {
+			return errors.Wrapf(err, "failed to save BlobSidecar index %d for block %#x", vscs[i].Index, root)
+		}
+	}
+	// All BlobSidecars are persisted - da check succeeds.
+	return nil
+}
+
+func commitmentsToCheck(b blocks.ROBlock, current primitives.Slot) (safeCommitmentArray, error) {
+	var ar safeCommitmentArray
+	if b.Version() < version.Deneb {
+		return ar, nil
+	}
+	// We are only required to check within MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS
+	if !params.WithinDAPeriod(slots.ToEpoch(b.Block().Slot()), slots.ToEpoch(current)) {
+		return ar, nil
+	}
+	kc, err := b.Block().Body().BlobKzgCommitments()
+	if err != nil {
+		return ar, err
+	}
+	if len(kc) > len(ar) {
+		return ar, errIndexOutOfBounds
+	}
+	copy(ar[:], kc)
+	return ar, nil
+}
--- a/beacon-chain/das/availability_test.go
+++ b/beacon-chain/das/availability_test.go
@@ -0,0 +1,214 @@
+package das
+
+import (
+	"bytes"
+	"context"
+	"testing"
+
+	errors "github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db/filesystem"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/verification"
+	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
+)
+
+func Test_commitmentsToCheck(t *testing.T) {
+	windowSlots, err := slots.EpochEnd(params.BeaconConfig().MinEpochsForBlobsSidecarsRequest)
+	require.NoError(t, err)
+	commits := [][]byte{
+		bytesutil.PadTo([]byte("a"), 48),
+		bytesutil.PadTo([]byte("b"), 48),
+		bytesutil.PadTo([]byte("c"), 48),
+		bytesutil.PadTo([]byte("d"), 48),
+	}
+	cases := []struct {
+		name    string
+		commits [][]byte
+		block   func(*testing.T) blocks.ROBlock
+		slot    primitives.Slot
+		err     error
+	}{
+		{
+			name: "pre deneb",
+			block: func(t *testing.T) blocks.ROBlock {
+				bb := util.NewBeaconBlockBellatrix()
+				sb, err := blocks.NewSignedBeaconBlock(bb)
+				require.NoError(t, err)
+				rb, err := blocks.NewROBlock(sb)
+				require.NoError(t, err)
+				return rb
+			},
+		},
+		{
+			name: "commitments within da",
+			block: func(t *testing.T) blocks.ROBlock {
+				d := util.NewBeaconBlockDeneb()
+				d.Block.Body.BlobKzgCommitments = commits
+				d.Block.Slot = 100
+				sb, err := blocks.NewSignedBeaconBlock(d)
+				require.NoError(t, err)
+				rb, err := blocks.NewROBlock(sb)
+				require.NoError(t, err)
+				return rb
+			},
+			commits: commits,
+			slot:    100,
+		},
+		{
+			name: "commitments outside da",
+			block: func(t *testing.T) blocks.ROBlock {
+				d := util.NewBeaconBlockDeneb()
+				// block is from slot 0, "current slot" is window size +1 (so outside the window)
+				d.Block.Body.BlobKzgCommitments = commits
+				sb, err := blocks.NewSignedBeaconBlock(d)
+				require.NoError(t, err)
+				rb, err := blocks.NewROBlock(sb)
+				require.NoError(t, err)
+				return rb
+			},
+			slot: windowSlots + 1,
+		},
+		{
+			name: "excessive commitments",
+			block: func(t *testing.T) blocks.ROBlock {
+				d := util.NewBeaconBlockDeneb()
+				d.Block.Slot = 100
+				// block is from slot 0, "current slot" is window size +1 (so outside the window)
+				d.Block.Body.BlobKzgCommitments = commits
+				// Double the number of commitments, assert that this is over the limit
+				d.Block.Body.BlobKzgCommitments = append(commits, d.Block.Body.BlobKzgCommitments...)
+				sb, err := blocks.NewSignedBeaconBlock(d)
+				require.NoError(t, err)
+				rb, err := blocks.NewROBlock(sb)
+				require.NoError(t, err)
+				c, err := rb.Block().Body().BlobKzgCommitments()
+				require.NoError(t, err)
+				require.Equal(t, true, len(c) > fieldparams.MaxBlobsPerBlock)
+				return rb
+			},
+			slot: windowSlots + 1,
+			err:  errIndexOutOfBounds,
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			b := c.block(t)
+			co, err := commitmentsToCheck(b, c.slot)
+			if c.err != nil {
+				require.ErrorIs(t, err, c.err)
+			} else {
+				require.NoError(t, err)
+			}
+			require.Equal(t, len(c.commits), co.count())
+			for i := 0; i < len(c.commits); i++ {
+				require.Equal(t, true, bytes.Equal(c.commits[i], co[i]))
+			}
+		})
+	}
+}
+
+func daAlwaysSucceeds(_ [][]byte, _ []*ethpb.BlobSidecar) error {
+	return nil
+}
+
+type mockDA struct {
+	t   *testing.T
+	scs []blocks.ROBlob
+	err error
+}
+
+func TestLazilyPersistent_Missing(t *testing.T) {
+	ctx := context.Background()
+	store := filesystem.NewEphemeralBlobStorage(t)
+
+	blk, scs := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 1, 3)
+
+	mbv := &mockBlobBatchVerifier{t: t, scs: scs}
+	as := NewLazilyPersistentStore(store, mbv)
+
+	// Only one commitment persisted, should return error with other indices
+	require.NoError(t, as.Persist(1, scs[2]))
+	err := as.IsDataAvailable(ctx, 1, blk)
+	require.ErrorIs(t, err, errMissingSidecar)
+
+	// All but one persisted, return missing idx
+	require.NoError(t, as.Persist(1, scs[0]))
+	err = as.IsDataAvailable(ctx, 1, blk)
+	require.ErrorIs(t, err, errMissingSidecar)
+
+	// All persisted, return nil
+	require.NoError(t, as.Persist(1, scs...))
+
+	require.NoError(t, as.IsDataAvailable(ctx, 1, blk))
+}
+
+func TestLazilyPersistent_Mismatch(t *testing.T) {
+	ctx := context.Background()
+	store := filesystem.NewEphemeralBlobStorage(t)
+
+	blk, scs := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 1, 3)
+
+	mbv := &mockBlobBatchVerifier{t: t, err: errors.New("kzg check should not run")}
+	scs[0].KzgCommitment = bytesutil.PadTo([]byte("nope"), 48)
+	as := NewLazilyPersistentStore(store, mbv)
+
+	// Only one commitment persisted, should return error with other indices
+	require.NoError(t, as.Persist(1, scs[0]))
+	err := as.IsDataAvailable(ctx, 1, blk)
+	require.NotNil(t, err)
+	require.ErrorIs(t, err, errCommitmentMismatch)
+}
+
+func TestLazyPersistOnceCommitted(t *testing.T) {
+	_, scs := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 1, 6)
+	as := NewLazilyPersistentStore(filesystem.NewEphemeralBlobStorage(t), &mockBlobBatchVerifier{})
+	// stashes as expected
+	require.NoError(t, as.Persist(1, scs...))
+	// ignores duplicates
+	require.ErrorIs(t, as.Persist(1, scs...), ErrDuplicateSidecar)
+
+	// ignores index out of bound
+	scs[0].Index = 6
+	require.ErrorIs(t, as.Persist(1, scs[0]), errIndexOutOfBounds)
+
+	_, more := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 1, 4)
+	// ignores sidecars before the retention period
+	slotOOB, err := slots.EpochStart(params.BeaconConfig().MinEpochsForBlobsSidecarsRequest)
+	require.NoError(t, err)
+	require.NoError(t, as.Persist(32+slotOOB, more[0]))
+
+	// doesn't ignore new sidecars with a different block root
+	require.NoError(t, as.Persist(1, more...))
+}
+
+type mockBlobBatchVerifier struct {
+	t        *testing.T
+	scs      []blocks.ROBlob
+	err      error
+	verified map[[32]byte]primitives.Slot
+}
+
+var _ BlobBatchVerifier = &mockBlobBatchVerifier{}
+
+func (m *mockBlobBatchVerifier) VerifiedROBlobs(_ context.Context, _ blocks.ROBlock, scs []blocks.ROBlob) ([]blocks.VerifiedROBlob, error) {
+	require.Equal(m.t, len(scs), len(m.scs))
+	for i := range m.scs {
+		require.Equal(m.t, m.scs[i], scs[i])
+	}
+	vscs := verification.FakeVerifySliceForTest(m.t, scs)
+	return vscs, m.err
+}
+
+func (m *mockBlobBatchVerifier) MarkVerified(root [32]byte, slot primitives.Slot) {
+	if m.verified == nil {
+		m.verified = make(map[[32]byte]primitives.Slot)
+	}
+	m.verified[root] = slot
+}
--- a/beacon-chain/das/cache.go
+++ b/beacon-chain/das/cache.go
@@ -0,0 +1,117 @@
+package das
+
+import (
+	"bytes"
+
+	"github.com/pkg/errors"
+	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+)
+
+var (
+	ErrDuplicateSidecar   = errors.New("duplicate sidecar stashed in AvailabilityStore")
+	errIndexOutOfBounds   = errors.New("sidecar.index > MAX_BLOBS_PER_BLOCK")
+	errCommitmentMismatch = errors.New("KzgCommitment of sidecar in cache did not match block commitment")
+	errMissingSidecar     = errors.New("no sidecar in cache for block commitment")
+)
+
+// cacheKey includes the slot so that we can easily iterate through the cache and compare
+// slots for eviction purposes. Whether the input is the block or the sidecar, we always have
+// the root+slot when interacting with the cache, so it isn't an inconvenience to use both.
+type cacheKey struct {
+	slot primitives.Slot
+	root [32]byte
+}
+
+type cache struct {
+	entries map[cacheKey]*cacheEntry
+}
+
+func newCache() *cache {
+	return &cache{entries: make(map[cacheKey]*cacheEntry)}
+}
+
+// keyFromSidecar is a convenience method for constructing a cacheKey from a BlobSidecar value.
+func keyFromSidecar(sc blocks.ROBlob) cacheKey {
+	return cacheKey{slot: sc.Slot(), root: sc.BlockRoot()}
+}
+
+// keyFromBlock is a convenience method for constructing a cacheKey from a ROBlock value.
+func keyFromBlock(b blocks.ROBlock) cacheKey {
+	return cacheKey{slot: b.Block().Slot(), root: b.Root()}
+}
+
+// ensure returns the entry for the given key, creating it if it isn't already present.
+func (c *cache) ensure(key cacheKey) *cacheEntry {
+	e, ok := c.entries[key]
+	if !ok {
+		e = &cacheEntry{}
+		c.entries[key] = e
+	}
+	return e
+}
+
+// delete removes the cache entry from the cache.
+func (c *cache) delete(key cacheKey) {
+	delete(c.entries, key)
+}
+
+// cacheEntry holds a fixed-length cache of BlobSidecars.
+type cacheEntry struct {
+	scs [fieldparams.MaxBlobsPerBlock]*blocks.ROBlob
+}
+
+// stash adds an item to the in-memory cache of BlobSidecars.
+// Only the first BlobSidecar of a given Index will be kept in the cache.
+// stash will return an error if the given blob is already in the cache, or if the Index is out of bounds.
+func (e *cacheEntry) stash(sc *blocks.ROBlob) error {
+	if sc.Index >= fieldparams.MaxBlobsPerBlock {
+		return errors.Wrapf(errIndexOutOfBounds, "index=%d", sc.Index)
+	}
+	if e.scs[sc.Index] != nil {
+		return errors.Wrapf(ErrDuplicateSidecar, "root=%#x, index=%d, commitment=%#x", sc.BlockRoot(), sc.Index, sc.KzgCommitment)
+	}
+	e.scs[sc.Index] = sc
+	return nil
+}
+
+// filter evicts sidecars that are not committed to by the block and returns custom
+// errors if the cache is missing any of the commitments, or if the commitments in
+// the cache do not match those found in the block. If err is nil, then all expected
+// commitments were found in the cache and the sidecar slice return value can be used
+// to perform a DA check against the cached sidecars.
+func (e *cacheEntry) filter(root [32]byte, kc safeCommitmentArray) ([]blocks.ROBlob, error) {
+	scs := make([]blocks.ROBlob, kc.count())
+	for i := uint64(0); i < fieldparams.MaxBlobsPerBlock; i++ {
+		if kc[i] == nil {
+			if e.scs[i] != nil {
+				return nil, errors.Wrapf(errCommitmentMismatch, "root=%#x, index=%#x, commitment=%#x, no block commitment", root, i, e.scs[i].KzgCommitment)
+			}
+			continue
+		}
+
+		if e.scs[i] == nil {
+			return nil, errors.Wrapf(errMissingSidecar, "root=%#x, index=%#x", root, i)
+		}
+		if !bytes.Equal(kc[i], e.scs[i].KzgCommitment) {
+			return nil, errors.Wrapf(errCommitmentMismatch, "root=%#x, index=%#x, commitment=%#x, block commitment=%#x", root, i, e.scs[i].KzgCommitment, kc[i])
+		}
+		scs[i] = *e.scs[i]
+	}
+
+	return scs, nil
+}
+
+// safeCommitmentArray is a fixed size array of commitment byte slices. This is helpful for avoiding
+// gratuitous bounds checks.
+type safeCommitmentArray [fieldparams.MaxBlobsPerBlock][]byte
+
+func (s safeCommitmentArray) count() int {
+	for i := range s {
+		if s[i] == nil {
+			return i
+		}
+	}
+	return fieldparams.MaxBlobsPerBlock
+}
--- a/beacon-chain/das/cache_test.go
+++ b/beacon-chain/das/cache_test.go
@@ -0,0 +1,25 @@
+package das
+
+import (
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+)
+
+func TestCacheEnsureDelete(t *testing.T) {
+	c := newCache()
+	require.Equal(t, 0, len(c.entries))
+	root := bytesutil.ToBytes32([]byte("root"))
+	slot := primitives.Slot(1234)
+	k := cacheKey{root: root, slot: slot}
+	entry := c.ensure(k)
+	require.Equal(t, 1, len(c.entries))
+	require.Equal(t, c.entries[k], entry)
+
+	c.delete(k)
+	require.Equal(t, 0, len(c.entries))
+	var nilEntry *cacheEntry
+	require.Equal(t, nilEntry, c.entries[k])
+}
--- a/beacon-chain/das/iface.go
+++ b/beacon-chain/das/iface.go
@@ -0,0 +1,19 @@
+package das
+
+import (
+	"context"
+
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+)
+
+// AvailabilityStore describes a component that can verify and save sidecars for a given block, and confirm previously
+// verified and saved sidecars.
+// Persist guarantees that the sidecar will be available to perform a DA check
+// for the life of the beacon node process.
+// IsDataAvailable guarantees that all blobs committed to in the block have been
+// durably persisted before returning a non-error value.
+type AvailabilityStore interface {
+	IsDataAvailable(ctx context.Context, current primitives.Slot, b blocks.ROBlock) error
+	Persist(current primitives.Slot, sc ...blocks.ROBlob) error
+}
--- a/beacon-chain/das/mock.go
+++ b/beacon-chain/das/mock.go
@@ -0,0 +1,32 @@
+package das
+
+import (
+	"context"
+
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+)
+
+// MockAvailabilityStore is an implementation of AvailabilityStore that can be used by other packages in tests.
+type MockAvailabilityStore struct {
+	VerifyAvailabilityCallback func(ctx context.Context, current primitives.Slot, b blocks.ROBlock) error
+	PersistBlobsCallback       func(current primitives.Slot, sc ...blocks.ROBlob) error
+}
+
+var _ AvailabilityStore = &MockAvailabilityStore{}
+
+// IsDataAvailable satisfies the corresponding method of the AvailabilityStore interface in a way that is useful for tests.
+func (m *MockAvailabilityStore) IsDataAvailable(ctx context.Context, current primitives.Slot, b blocks.ROBlock) error {
+	if m.VerifyAvailabilityCallback != nil {
+		return m.VerifyAvailabilityCallback(ctx, current, b)
+	}
+	return nil
+}
+
+// Persist satisfies the corresponding method of the AvailabilityStore interface in a way that is useful for tests.
+func (m *MockAvailabilityStore) Persist(current primitives.Slot, sc ...blocks.ROBlob) error {
+	if m.PersistBlobsCallback != nil {
+		return m.PersistBlobsCallback(current, sc...)
+	}
+	return nil
+}
--- a/beacon-chain/db/errors.go
+++ b/beacon-chain/db/errors.go
@@ -22,9 +22,6 @@ var ErrNotFoundOriginBlockRoot = kv.ErrNotFoundOriginBlockRoot
 // ErrNotFoundBackfillBlockRoot wraps ErrNotFound for an error specific to the backfill block root.
 var ErrNotFoundBackfillBlockRoot = kv.ErrNotFoundBackfillBlockRoot

-// ErrNotFoundGenesisBlockRoot means no genesis block root was found, indicating the db was not initialized with genesis
-var ErrNotFoundGenesisBlockRoot = kv.ErrNotFoundGenesisBlockRoot
-
 // IsNotFound allows callers to treat errors from a flat-file database, where the file record is missing,
 // as equivalent to db.ErrNotFound.
 func IsNotFound(err error) bool {
--- a/beacon-chain/db/filesystem/BUILD.bazel
+++ b/beacon-chain/db/filesystem/BUILD.bazel
@@ -6,6 +6,7 @@ go_library(
        "blob.go",
        "ephemeral.go",
        "metrics.go",
+        "pruner.go",
    ],
    importpath = "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/filesystem",
    visibility = ["//visibility:public"],
@@ -19,7 +20,6 @@ go_library(
        "//proto/prysm/v1alpha1:go_default_library",
        "//runtime/logging: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_prometheus_client_golang//prometheus:go_default_library",
        "@com_github_prometheus_client_golang//prometheus/promauto:go_default_library",
@@ -30,7 +30,10 @@ go_library(

 go_test(
    name = "go_default_test",
-    srcs = ["blob_test.go"],
+    srcs = [
+        "blob_test.go",
+        "pruner_test.go",
+    ],
    embed = [":go_default_library"],
    deps = [
        "//beacon-chain/verification:go_default_library",
@@ -40,7 +43,6 @@ go_test(
        "//proto/prysm/v1alpha1:go_default_library",
        "//testing/require:go_default_library",
        "//testing/util: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",
        "@com_github_spf13_afero//:go_default_library",
--- a/beacon-chain/db/filesystem/blob.go
+++ b/beacon-chain/db/filesystem/blob.go
@@ -1,27 +1,21 @@
 package filesystem

 import (
-	"encoding/binary"
 	"fmt"
-	"io"
 	"os"
 	"path"
-	"path/filepath"
 	"strconv"
 	"strings"
 	"time"

-	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/verification"
 	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
-	"github.com/prysmaticlabs/prysm/v4/config/params"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v4/io/file"
 	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/v4/runtime/logging"
-	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/afero"
 )
@@ -34,18 +28,21 @@ const (
 	sszExt  = "ssz"
 	partExt = "part"

-	firstPruneEpoch      = 0
-	bufferEpochs         = 2
 	directoryPermissions = 0700
 )

 // BlobStorageOption is a functional option for configuring a BlobStorage.
-type BlobStorageOption func(*BlobStorage)
+type BlobStorageOption func(*BlobStorage) error

 // WithBlobRetentionEpochs is an option that changes the number of epochs blobs will be persisted.
 func WithBlobRetentionEpochs(e primitives.Epoch) BlobStorageOption {
-	return func(b *BlobStorage) {
-		b.retentionEpochs = e
+	return func(b *BlobStorage) error {
+		pruner, err := newBlobPruner(b.fs, e)
+		if err != nil {
+			return err
+		}
+		b.pruner = pruner
+		return nil
 	}
 }

@@ -59,21 +56,36 @@ func NewBlobStorage(base string, opts ...BlobStorageOption) (*BlobStorage, error
 	}
 	fs := afero.NewBasePathFs(afero.NewOsFs(), base)
 	b := &BlobStorage{
-		fs:              fs,
-		retentionEpochs: params.BeaconConfig().MinEpochsForBlobsSidecarsRequest,
-		lastPrunedEpoch: firstPruneEpoch,
+		fs: fs,
 	}
 	for _, o := range opts {
-		o(b)
+		if err := o(b); err != nil {
+			return nil, fmt.Errorf("failed to create blob storage at %s: %w", base, err)
+		}
+	}
+	if b.pruner == nil {
+		log.Warn("Initializing blob filesystem storage with pruning disabled")
 	}
 	return b, nil
 }

 // BlobStorage is the concrete implementation of the filesystem backend for saving and retrieving BlobSidecars.
 type BlobStorage struct {
-	fs              afero.Fs
-	retentionEpochs primitives.Epoch
-	lastPrunedEpoch primitives.Epoch
+	fs     afero.Fs
+	pruner *blobPruner
+}
+
+// WarmCache runs the prune routine with an expiration of slot of 0, so nothing will be pruned, but the pruner's cache
+// will be populated at node startup, avoiding a costly cold prune (~4s in syscalls) during syncing.
+func (bs *BlobStorage) WarmCache() {
+	if bs.pruner == nil {
+		return
+	}
+	go func() {
+		if err := bs.pruner.prune(0); err != nil {
+			log.WithError(err).Error("Error encountered while warming up blob pruner cache.")
+		}
+	}()
 }

 // Save saves blobs given a list of sidecars.
@@ -89,13 +101,8 @@ func (bs *BlobStorage) Save(sidecar blocks.VerifiedROBlob) error {
 		log.WithFields(logging.BlobFields(sidecar.ROBlob)).Debug("ignoring a duplicate blob sidecar Save attempt")
 		return nil
 	}
-	if bs.shouldPrune(sidecar.Slot()) {
-		go func() {
-			err := bs.pruneOlderThan(sidecar.Slot())
-			if err != nil {
-				log.WithError(err).Errorf("failed to prune blobs from slot %d", sidecar.Slot())
-			}
-		}()
+	if bs.pruner != nil {
+		bs.pruner.notify(sidecar.BlockRoot(), sidecar.Slot())
 	}

 	// Serialize the ethpb.BlobSidecar to binary data using SSZ.
@@ -108,8 +115,12 @@ func (bs *BlobStorage) Save(sidecar blocks.VerifiedROBlob) error {
 	}
 	partPath := fname.partPath()

+	partialMoved := false
 	// Ensure the partial file is deleted.
 	defer func() {
+		if partialMoved {
+			return
+		}
 		// It's expected to error if the save is successful.
 		err = bs.fs.Remove(partPath)
 		if err == nil {
@@ -143,8 +154,9 @@ func (bs *BlobStorage) Save(sidecar blocks.VerifiedROBlob) error {
 	if err != nil {
 		return errors.Wrap(err, "failed to rename partial file to final name")
 	}
-	blobsTotalGauge.Inc()
-	blobSaveLatency.Observe(time.Since(startTime).Seconds())
+	partialMoved = true
+	blobsWrittenCounter.Inc()
+	blobSaveLatency.Observe(float64(time.Since(startTime).Milliseconds()))
 	return nil
 }

@@ -168,11 +180,17 @@ func (bs *BlobStorage) Get(root [32]byte, idx uint64) (blocks.VerifiedROBlob, er
 		return blocks.VerifiedROBlob{}, err
 	}
 	defer func() {
-		blobFetchLatency.Observe(time.Since(startTime).Seconds())
+		blobFetchLatency.Observe(float64(time.Since(startTime).Milliseconds()))
 	}()
 	return verification.BlobSidecarNoop(ro)
 }

+// Remove removes all blobs for a given root.
+func (bs *BlobStorage) Remove(root [32]byte) error {
+	rootDir := blobNamer{root: root}.dir()
+	return bs.fs.RemoveAll(rootDir)
+}
+
 // Indices generates a bitmap representing which BlobSidecar.Index values are present on disk for a given root.
 // This value can be compared to the commitments observed in a block to determine which indices need to be found
 // on the network to confirm data availability.
@@ -220,7 +238,7 @@ func namerForSidecar(sc blocks.VerifiedROBlob) blobNamer {
 }

 func (p blobNamer) dir() string {
-	return fmt.Sprintf("%#x", p.root)
+	return rootString(p.root)
 }

 func (p blobNamer) fname(ext string) string {
@@ -235,117 +253,6 @@ func (p blobNamer) path() string {
 	return p.fname(sszExt)
 }

-// Prune prunes blobs in the base directory based on the retention epoch.
-// It deletes blobs older than currentEpoch - (retentionEpochs+bufferEpochs).
-// This is so that we keep a slight buffer and blobs are deleted after n+2 epochs.
-func (bs *BlobStorage) Prune(currentSlot primitives.Slot) error {
-	t := time.Now()
-	retentionSlots, err := slots.EpochStart(bs.retentionEpochs + bufferEpochs)
-	if err != nil {
-		return err
-	}
-	if currentSlot < retentionSlots {
-		return nil // Overflow would occur
-	}
-
-	log.Debug("Pruning old blobs")
-
-	folders, err := afero.ReadDir(bs.fs, ".")
-	if err != nil {
-		return err
-	}
-	var totalPruned int
-	for _, folder := range folders {
-		if folder.IsDir() {
-			num, err := bs.processFolder(folder, currentSlot, retentionSlots)
-			if err != nil {
-				return err
-			}
-			blobsPrunedCounter.Add(float64(num))
-			blobsTotalGauge.Add(-float64(num))
-			totalPruned += num
-		}
-	}
-	pruneTime := time.Since(t)
-
-	log.WithFields(log.Fields{
-		"lastPrunedEpoch":   slots.ToEpoch(currentSlot - retentionSlots),
-		"pruneTime":         pruneTime,
-		"numberBlobsPruned": totalPruned,
-	}).Debug("Pruned old blobs")
-
-	return nil
-}
-
-// processFolder will delete the folder of blobs if the blob slot is outside the
-// retention period. We determine the slot by looking at the first blob in the folder.
-func (bs *BlobStorage) processFolder(folder os.FileInfo, currentSlot, retentionSlots primitives.Slot) (int, error) {
-	f, err := bs.fs.Open(filepath.Join(folder.Name(), "0."+sszExt))
-	if err != nil {
-		return 0, err
-	}
-	defer func() {
-		if err := f.Close(); err != nil {
-			log.WithError(err).Errorf("Could not close blob file")
-		}
-	}()
-
-	slot, err := slotFromBlob(f)
-	if err != nil {
-		return 0, err
-	}
-	var num int
-	if slot < (currentSlot - retentionSlots) {
-		num, err = bs.countFiles(folder.Name())
-		if err != nil {
-			return 0, err
-		}
-		if err = bs.fs.RemoveAll(folder.Name()); err != nil {
-			return 0, errors.Wrapf(err, "failed to delete blob %s", f.Name())
-		}
-	}
-	return num, nil
-}
-
-// slotFromBlob reads the ssz data of a file at the specified offset (8 + 131072 + 48 + 48 = 131176 bytes),
-// which is calculated based on the size of the BlobSidecar struct and is based on the size of the fields
-// preceding the slot information within SignedBeaconBlockHeader.
-func slotFromBlob(at io.ReaderAt) (primitives.Slot, error) {
-	b := make([]byte, 8)
-	_, err := at.ReadAt(b, 131176)
-	if err != nil {
-		return 0, err
-	}
-	rawSlot := binary.LittleEndian.Uint64(b)
-	return primitives.Slot(rawSlot), nil
-}
-
-// Delete removes the directory matching the provided block root and all the blobs it contains.
-func (bs *BlobStorage) Delete(root [32]byte) error {
-	if err := bs.fs.RemoveAll(hexutil.Encode(root[:])); err != nil {
-		return fmt.Errorf("failed to delete blobs for root %#x: %w", root, err)
-	}
-	return nil
-}
-
-// shouldPrune checks whether pruning should be triggered based on the given slot.
-func (bs *BlobStorage) shouldPrune(slot primitives.Slot) bool {
-	if slots.SinceEpochStarts(slot) < params.BeaconConfig().SlotsPerEpoch/2 {
-		return false
-	}
-	if slots.ToEpoch(slot) == bs.lastPrunedEpoch {
-		return false
-	}
-	return true
-}
-
-// pruneOlderThan prunes blobs in the base directory based on the retention epoch and current slot.
-func (bs *BlobStorage) pruneOlderThan(slot primitives.Slot) error {
-	err := bs.Prune(slot)
-	if err != nil {
-		return err
-	}
-	// Update lastPrunedEpoch to the current epoch.
-	bs.lastPrunedEpoch = slots.ToEpoch(slot)
-	return nil
+func rootString(root [32]byte) string {
+	return fmt.Sprintf("%#x", root)
 }
--- a/beacon-chain/db/filesystem/blob_test.go
+++ b/beacon-chain/db/filesystem/blob_test.go
@@ -7,7 +7,6 @@ import (
 	"testing"
 	"time"

-	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/pkg/errors"
 	ssz "github.com/prysmaticlabs/fastssz"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/verification"
@@ -74,47 +73,20 @@ func TestBlobStorage_SaveBlobData(t *testing.T) {
 		require.NoError(t, err)
 		require.DeepSSZEqual(t, expected, actual)
 	})
-	t.Run("check pruning", func(t *testing.T) {
-		fs, bs, err := NewEphemeralBlobStorageWithFs(t)
+
+	t.Run("round trip write, read and delete", func(t *testing.T) {
+		bs := NewEphemeralBlobStorage(t)
+		err := bs.Save(testSidecars[0])
 		require.NoError(t, err)

-		// Slot in first half of epoch therefore should not prune
-		require.Equal(t, false, bs.shouldPrune(testSidecars[0].Slot()))
-		err = bs.Save(testSidecars[0])
-		require.NoError(t, err)
-		actual, err := bs.Get(testSidecars[0].BlockRoot(), testSidecars[0].Index)
-		require.NoError(t, err)
-		require.DeepSSZEqual(t, testSidecars[0], actual)
-		err = pollUntil(t, fs, 1)
+		expected := testSidecars[0]
+		actual, err := bs.Get(expected.BlockRoot(), expected.Index)
 		require.NoError(t, err)
+		require.DeepSSZEqual(t, expected, actual)

-		_, sidecars = util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 33, fieldparams.MaxBlobsPerBlock)
-		testSidecars1, err := verification.BlobSidecarSliceNoop(sidecars)
-		require.NoError(t, err)
-		// Slot in first half of epoch therefore should not prune
-		require.Equal(t, false, bs.shouldPrune(testSidecars1[0].Slot()))
-		err = bs.Save(testSidecars1[0])
-		require.NoError(t, err)
-		// Check previous saved sidecar was not pruned
-		actual, err = bs.Get(testSidecars[0].BlockRoot(), testSidecars[0].Index)
-		require.NoError(t, err)
-		require.DeepSSZEqual(t, testSidecars[0], actual)
-		// Check latest sidecar exists
-		actual, err = bs.Get(testSidecars1[0].BlockRoot(), testSidecars1[0].Index)
-		require.NoError(t, err)
-		require.DeepSSZEqual(t, testSidecars1[0], actual)
-		err = pollUntil(t, fs, 2) // Check correct number of files
-		require.NoError(t, err)
-
-		_, sidecars = util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 131187, fieldparams.MaxBlobsPerBlock)
-		testSidecars, err = verification.BlobSidecarSliceNoop(sidecars)
-		// Slot in second half of epoch therefore should prune
-		require.Equal(t, true, bs.shouldPrune(testSidecars[0].Slot()))
-		require.NoError(t, err)
-		err = bs.Save(testSidecars[0])
-		require.NoError(t, err)
-		err = pollUntil(t, fs, 1)
-		require.NoError(t, err)
+		require.NoError(t, bs.Remove(expected.BlockRoot()))
+		_, err = bs.Get(expected.BlockRoot(), expected.Index)
+		require.ErrorContains(t, "file does not exist", err)
 	})
 }

@@ -143,26 +115,6 @@ func pollUntil(t *testing.T, fs afero.Fs, expected int) error {
 	return nil
 }

-func TestShouldPrune(t *testing.T) {
-	bs := NewEphemeralBlobStorage(t)
-	bs.lastPrunedEpoch = 5
-
-	// Slot is before the midpoint of the epoch
-	slot1 := primitives.Slot(100)
-	p1 := bs.shouldPrune(slot1)
-	require.Equal(t, false, p1)
-
-	// Slot is after the midpoint of the epoch, but same epoch as last pruning
-	slot2 := primitives.Slot(178)
-	p2 := bs.shouldPrune(slot2)
-	require.Equal(t, false, p2)
-
-	// Slot is after the midpoint of the epoch
-	slot3 := primitives.Slot(8018)
-	p3 := bs.shouldPrune(slot3)
-	require.Equal(t, true, p3)
-}
-
 func TestBlobIndicesBounds(t *testing.T) {
 	fs, bs, err := NewEphemeralBlobStorageWithFs(t)
 	require.NoError(t, err)
@@ -208,7 +160,22 @@ func TestBlobStoragePrune(t *testing.T) {
 			require.NoError(t, bs.Save(sidecar))
 		}

-		require.NoError(t, bs.Prune(currentSlot))
+		require.NoError(t, bs.pruner.prune(currentSlot-bs.pruner.windowSize))
+
+		remainingFolders, err := afero.ReadDir(fs, ".")
+		require.NoError(t, err)
+		require.Equal(t, 0, len(remainingFolders))
+	})
+	t.Run("Prune dangling blob", func(t *testing.T) {
+		_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 299, fieldparams.MaxBlobsPerBlock)
+		testSidecars, err := verification.BlobSidecarSliceNoop(sidecars)
+		require.NoError(t, err)
+
+		for _, sidecar := range testSidecars[4:] {
+			require.NoError(t, bs.Save(sidecar))
+		}
+
+		require.NoError(t, bs.pruner.prune(currentSlot-bs.pruner.windowSize))

 		remainingFolders, err := afero.ReadDir(fs, ".")
 		require.NoError(t, err)
@@ -216,7 +183,7 @@ func TestBlobStoragePrune(t *testing.T) {
 	})
 	t.Run("PruneMany", func(t *testing.T) {
 		blockQty := 10
-		slot := primitives.Slot(0)
+		slot := primitives.Slot(1)

 		for j := 0; j <= blockQty; j++ {
 			root := bytesutil.ToBytes32(bytesutil.ToBytes(uint64(slot), 32))
@@ -228,7 +195,7 @@ func TestBlobStoragePrune(t *testing.T) {
 			slot += 10000
 		}

-		require.NoError(t, bs.Prune(currentSlot))
+		require.NoError(t, bs.pruner.prune(currentSlot-bs.pruner.windowSize))

 		remainingFolders, err := afero.ReadDir(fs, ".")
 		require.NoError(t, err)
@@ -257,41 +224,11 @@ func BenchmarkPruning(b *testing.B) {
 	b.ReportAllocs()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		err := bs.Prune(currentSlot)
+		err := bs.pruner.prune(currentSlot)
 		require.NoError(b, err)
 	}
 }

-func TestBlobStorageDelete(t *testing.T) {
-	fs, bs, err := NewEphemeralBlobStorageWithFs(t)
-	require.NoError(t, err)
-	rawRoot := "0xcf9bb70c98f58092c9d6459227c9765f984d240be9690e85179bc5a6f60366ad"
-	blockRoot, err := hexutil.Decode(rawRoot)
-	require.NoError(t, err)
-
-	_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 1, fieldparams.MaxBlobsPerBlock)
-	testSidecars, err := verification.BlobSidecarSliceNoop(sidecars)
-	require.NoError(t, err)
-	for _, sidecar := range testSidecars {
-		require.NoError(t, bs.Save(sidecar))
-	}
-
-	exists, err := afero.DirExists(fs, hexutil.Encode(blockRoot))
-	require.NoError(t, err)
-	require.Equal(t, true, exists)
-
-	// Delete the directory corresponding to the block root
-	require.NoError(t, bs.Delete(bytesutil.ToBytes32(blockRoot)))
-
-	// Ensure that the directory no longer exists after deletion
-	exists, err = afero.DirExists(fs, hexutil.Encode(blockRoot))
-	require.NoError(t, err)
-	require.Equal(t, false, exists)
-
-	// Deleting a non-existent root does not return an error.
-	require.NoError(t, bs.Delete(bytesutil.ToBytes32([]byte{0x1})))
-}
-
 func TestNewBlobStorage(t *testing.T) {
 	_, err := NewBlobStorage(path.Join(t.TempDir(), "good"))
 	require.NoError(t, err)
--- a/beacon-chain/db/filesystem/ephemeral.go
+++ b/beacon-chain/db/filesystem/ephemeral.go
@@ -10,16 +10,24 @@ import (
 // NewEphemeralBlobStorage should only be used for tests.
 // The instance of BlobStorage returned is backed by an in-memory virtual filesystem,
 // improving test performance and simplifying cleanup.
-func NewEphemeralBlobStorage(_ testing.TB) *BlobStorage {
-	return &BlobStorage{fs: afero.NewMemMapFs()}
+func NewEphemeralBlobStorage(t testing.TB) *BlobStorage {
+	fs := afero.NewMemMapFs()
+	pruner, err := newBlobPruner(fs, params.BeaconConfig().MinEpochsForBlobsSidecarsRequest)
+	if err != nil {
+		t.Fatal("test setup issue", err)
+	}
+	return &BlobStorage{fs: fs, pruner: pruner}
 }

 // NewEphemeralBlobStorageWithFs can be used by tests that want access to the virtual filesystem
 // in order to interact with it outside the parameters of the BlobStorage api.
-func NewEphemeralBlobStorageWithFs(_ testing.TB) (afero.Fs, *BlobStorage, error) {
+func NewEphemeralBlobStorageWithFs(t testing.TB) (afero.Fs, *BlobStorage, error) {
 	fs := afero.NewMemMapFs()
-	retentionEpoch := params.BeaconConfig().MinEpochsForBlobsSidecarsRequest
-	return fs, &BlobStorage{fs: fs, retentionEpochs: retentionEpoch}, nil
+	pruner, err := newBlobPruner(fs, params.BeaconConfig().MinEpochsForBlobsSidecarsRequest)
+	if err != nil {
+		t.Fatal("test setup issue", err)
+	}
+	return fs, &BlobStorage{fs: fs, pruner: pruner}, nil
 }

 type BlobMocker struct {
--- a/beacon-chain/db/filesystem/metrics.go
+++ b/beacon-chain/db/filesystem/metrics.go
@@ -1,70 +1,28 @@
 package filesystem

 import (
-	"fmt"
-
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
-	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
-	"github.com/spf13/afero"
 )

 var (
-	blobBuckets     = []float64{0.00003, 0.00005, 0.00007, 0.00009, 0.00011, 0.00013, 0.00015}
+	blobBuckets     = []float64{3, 5, 7, 9, 11, 13}
 	blobSaveLatency = promauto.NewHistogram(prometheus.HistogramOpts{
 		Name:    "blob_storage_save_latency",
-		Help:    "Latency of blob storage save operations in seconds",
+		Help:    "Latency of BlobSidecar storage save operations in milliseconds",
 		Buckets: blobBuckets,
 	})
 	blobFetchLatency = promauto.NewHistogram(prometheus.HistogramOpts{
 		Name:    "blob_storage_get_latency",
-		Help:    "Latency of blob storage get operations in seconds",
+		Help:    "Latency of BlobSidecar storage get operations in milliseconds",
 		Buckets: blobBuckets,
 	})
 	blobsPrunedCounter = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "blob_pruned_blobs_total",
-		Help: "Total number of pruned blobs.",
+		Name: "blob_pruned",
+		Help: "Number of BlobSidecar files pruned.",
 	})
-	blobsTotalGauge = promauto.NewGauge(prometheus.GaugeOpts{
-		Name: "blobs_on_disk_total",
-		Help: "Total number of blobs in filesystem.",
+	blobsWrittenCounter = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "blobs_written",
+		Help: "Number of BlobSidecar files written.",
 	})
 )
-
-func (bs *BlobStorage) Initialize(lastFinalizedSlot primitives.Slot) error {
-	if err := bs.Prune(lastFinalizedSlot); err != nil {
-		return fmt.Errorf("failed to prune from finalized slot %d: %w", lastFinalizedSlot, err)
-	}
-	if err := bs.collectTotalBlobMetric(); err != nil {
-		return fmt.Errorf("failed to initialize blob metrics: %w", err)
-	}
-	return nil
-}
-
-// CollectTotalBlobMetric set the number of blobs currently present in the filesystem
-// to the blobsTotalGauge metric.
-func (bs *BlobStorage) collectTotalBlobMetric() error {
-	totalBlobs := 0
-	folders, err := afero.ReadDir(bs.fs, ".")
-	if err != nil {
-		return err
-	}
-	for _, folder := range folders {
-		num, err := bs.countFiles(folder.Name())
-		if err != nil {
-			return err
-		}
-		totalBlobs = totalBlobs + num
-	}
-	blobsTotalGauge.Set(float64(totalBlobs))
-	return nil
-}
-
-// countFiles returns the length of blob files for a given directory.
-func (bs *BlobStorage) countFiles(folderName string) (int, error) {
-	files, err := afero.ReadDir(bs.fs, folderName)
-	if err != nil {
-		return 0, err
-	}
-	return len(files), nil
-}
--- a/beacon-chain/db/filesystem/pruner.go
+++ b/beacon-chain/db/filesystem/pruner.go
@@ -0,0 +1,274 @@
+package filesystem
+
+import (
+	"encoding/binary"
+	"io"
+	"path"
+	"path/filepath"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/pkg/errors"
+	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
+	log "github.com/sirupsen/logrus"
+	"github.com/spf13/afero"
+)
+
+const retentionBuffer primitives.Epoch = 2
+
+var (
+	errPruningFailures = errors.New("blobs could not be pruned for some roots")
+)
+
+type blobPruner struct {
+	sync.Mutex
+	prunedBefore atomic.Uint64
+	windowSize   primitives.Slot
+	slotMap      *slotForRoot
+	fs           afero.Fs
+}
+
+func newBlobPruner(fs afero.Fs, retain primitives.Epoch) (*blobPruner, error) {
+	r, err := slots.EpochStart(retain + retentionBuffer)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not set retentionSlots")
+	}
+	return &blobPruner{fs: fs, windowSize: r, slotMap: newSlotForRoot()}, nil
+}
+
+// notify updates the pruner's view of root->blob mappings. This allows the pruner to build a cache
+// of root->slot mappings and decide when to evict old blobs based on the age of present blobs.
+func (p *blobPruner) notify(root [32]byte, latest primitives.Slot) {
+	p.slotMap.ensure(rootString(root), latest)
+	pruned := uint64(windowMin(latest, p.windowSize))
+	if p.prunedBefore.Swap(pruned) == pruned {
+		return
+	}
+	go func() {
+		if err := p.prune(primitives.Slot(pruned)); err != nil {
+			log.WithError(err).Errorf("Failed to prune blobs from slot %d", latest)
+		}
+	}()
+}
+
+func windowMin(latest primitives.Slot, offset primitives.Slot) primitives.Slot {
+	// Safely compute the first slot in the epoch for the latest slot
+	latest = latest - latest%params.BeaconConfig().SlotsPerEpoch
+	if latest < offset {
+		return 0
+	}
+	return latest - offset
+}
+
+// Prune prunes blobs in the base directory based on the retention epoch.
+// It deletes blobs older than currentEpoch - (retentionEpochs+bufferEpochs).
+// This is so that we keep a slight buffer and blobs are deleted after n+2 epochs.
+func (p *blobPruner) prune(pruneBefore primitives.Slot) error {
+	p.Lock()
+	defer p.Unlock()
+	start := time.Now()
+	totalPruned, totalErr := 0, 0
+	// Customize logging/metrics behavior for the initial cache warmup when slot=0.
+	// We'll never see a prune request for slot 0, unless this is the initial call to warm up the cache.
+	if pruneBefore == 0 {
+		defer func() {
+			log.WithField("duration", time.Since(start).String()).Debug("Warmed up pruner cache")
+		}()
+	} else {
+		defer func() {
+			log.WithFields(log.Fields{
+				"upToEpoch":    slots.ToEpoch(pruneBefore),
+				"duration":     time.Since(start).String(),
+				"filesRemoved": totalPruned,
+			}).Debug("Pruned old blobs")
+			blobsPrunedCounter.Add(float64(totalPruned))
+		}()
+	}
+
+	entries, err := listDir(p.fs, ".")
+	if err != nil {
+		return errors.Wrap(err, "unable to list root blobs directory")
+	}
+	dirs := filter(entries, filterRoot)
+	for _, dir := range dirs {
+		pruned, err := p.tryPruneDir(dir, pruneBefore)
+		if err != nil {
+			totalErr += 1
+			log.WithError(err).WithField("directory", dir).Error("Unable to prune directory")
+		}
+		totalPruned += pruned
+	}
+
+	if totalErr > 0 {
+		return errors.Wrapf(errPruningFailures, "pruning failed for %d root directories", totalErr)
+	}
+	return nil
+}
+
+func shouldRetain(slot, pruneBefore primitives.Slot) bool {
+	return slot >= pruneBefore
+}
+
+func (p *blobPruner) tryPruneDir(dir string, pruneBefore primitives.Slot) (int, error) {
+	root := rootFromDir(dir)
+	slot, slotCached := p.slotMap.slot(root)
+	// Return early if the slot is cached and doesn't need pruning.
+	if slotCached && shouldRetain(slot, pruneBefore) {
+		return 0, nil
+	}
+
+	// entries will include things that aren't ssz files, like dangling .part files. We need these to
+	// completely clean up the directory.
+	entries, err := listDir(p.fs, dir)
+	if err != nil {
+		return 0, errors.Wrapf(err, "failed to list blobs in directory %s", dir)
+	}
+	// scFiles filters the dir listing down to the ssz encoded BlobSidecar files. This allows us to peek
+	// at the first one in the list to figure out the slot.
+	scFiles := filter(entries, filterSsz)
+	if len(scFiles) == 0 {
+		log.WithField("dir", dir).Warn("Pruner ignoring directory with no blob files")
+		return 0, nil
+	}
+	if !slotCached {
+		slot, err = slotFromFile(path.Join(dir, scFiles[0]), p.fs)
+		if err != nil {
+			return 0, errors.Wrapf(err, "slot could not be read from blob file %s", scFiles[0])
+		}
+		p.slotMap.ensure(root, slot)
+		if shouldRetain(slot, pruneBefore) {
+			return 0, nil
+		}
+	}
+
+	removed := 0
+	for _, fname := range entries {
+		fullName := path.Join(dir, fname)
+		if err := p.fs.Remove(fullName); err != nil {
+			return removed, errors.Wrapf(err, "unable to remove %s", fullName)
+		}
+		// Don't count other files that happen to be in the dir, like dangling .part files.
+		if filterSsz(fname) {
+			removed += 1
+		}
+		// Log a warning whenever we clean up a .part file
+		if filterPart(fullName) {
+			log.WithField("file", fullName).Warn("Deleting abandoned blob .part file")
+		}
+	}
+	if err := p.fs.Remove(dir); err != nil {
+		return removed, errors.Wrapf(err, "unable to remove blob directory %s", dir)
+	}
+
+	p.slotMap.evict(rootFromDir(dir))
+	return len(scFiles), nil
+}
+
+func rootFromDir(dir string) string {
+	return filepath.Base(dir) // end of the path should be the blob directory, named by hex encoding of root
+}
+
+// Read slot from marshaled BlobSidecar data in the given file. See slotFromBlob for details.
+func slotFromFile(file string, fs afero.Fs) (primitives.Slot, error) {
+	f, err := fs.Open(file)
+	if err != nil {
+		return 0, err
+	}
+	defer func() {
+		if err := f.Close(); err != nil {
+			log.WithError(err).Errorf("Could not close blob file")
+		}
+	}()
+	return slotFromBlob(f)
+}
+
+// slotFromBlob reads the ssz data of a file at the specified offset (8 + 131072 + 48 + 48 = 131176 bytes),
+// which is calculated based on the size of the BlobSidecar struct and is based on the size of the fields
+// preceding the slot information within SignedBeaconBlockHeader.
+func slotFromBlob(at io.ReaderAt) (primitives.Slot, error) {
+	b := make([]byte, 8)
+	_, err := at.ReadAt(b, 131176)
+	if err != nil {
+		return 0, err
+	}
+	rawSlot := binary.LittleEndian.Uint64(b)
+	return primitives.Slot(rawSlot), nil
+}
+
+func listDir(fs afero.Fs, dir string) ([]string, error) {
+	top, err := fs.Open(dir)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to open directory descriptor")
+	}
+	defer func() {
+		if err := top.Close(); err != nil {
+			log.WithError(err).Errorf("Could not close file %s", dir)
+		}
+	}()
+	// re the -1 param: "If n <= 0, Readdirnames returns all the names from the directory in a single slice"
+	dirs, err := top.Readdirnames(-1)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to read directory listing")
+	}
+	return dirs, nil
+}
+
+func filter(entries []string, filt func(string) bool) []string {
+	filtered := make([]string, 0, len(entries))
+	for i := range entries {
+		if filt(entries[i]) {
+			filtered = append(filtered, entries[i])
+		}
+	}
+	return filtered
+}
+
+func filterRoot(s string) bool {
+	return strings.HasPrefix(s, "0x")
+}
+
+var dotSszExt = "." + sszExt
+var dotPartExt = "." + partExt
+
+func filterSsz(s string) bool {
+	return filepath.Ext(s) == dotSszExt
+}
+
+func filterPart(s string) bool {
+	return filepath.Ext(s) == dotPartExt
+}
+
+func newSlotForRoot() *slotForRoot {
+	return &slotForRoot{
+		cache: make(map[string]primitives.Slot, params.BeaconConfig().MinEpochsForBlobsSidecarsRequest*fieldparams.SlotsPerEpoch),
+	}
+}
+
+type slotForRoot struct {
+	sync.RWMutex
+	cache map[string]primitives.Slot
+}
+
+func (s *slotForRoot) ensure(key string, slot primitives.Slot) {
+	s.Lock()
+	defer s.Unlock()
+	s.cache[key] = slot
+}
+
+func (s *slotForRoot) slot(key string) (primitives.Slot, bool) {
+	s.RLock()
+	defer s.RUnlock()
+	slot, ok := s.cache[key]
+	return slot, ok
+}
+
+func (s *slotForRoot) evict(key string) {
+	s.Lock()
+	defer s.Unlock()
+	delete(s.cache, key)
+}
--- a/beacon-chain/db/filesystem/pruner_test.go
+++ b/beacon-chain/db/filesystem/pruner_test.go
@@ -0,0 +1,327 @@
+package filesystem
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"os"
+	"path"
+	"sort"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/verification"
+	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
+	"github.com/spf13/afero"
+)
+
+func TestTryPruneDir_CachedNotExpired(t *testing.T) {
+	fs := afero.NewMemMapFs()
+	pr, err := newBlobPruner(fs, 0)
+	require.NoError(t, err)
+	slot := pr.windowSize
+	_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, slot, fieldparams.MaxBlobsPerBlock)
+	sc, err := verification.BlobSidecarNoop(sidecars[0])
+	require.NoError(t, err)
+	root := fmt.Sprintf("%#x", sc.BlockRoot())
+	// This slot is right on the edge of what would need to be pruned, so by adding it to the cache and
+	// skipping any other test setup, we can be certain the hot cache path never touches the filesystem.
+	pr.slotMap.ensure(root, sc.Slot())
+	pruned, err := pr.tryPruneDir(root, pr.windowSize)
+	require.NoError(t, err)
+	require.Equal(t, 0, pruned)
+}
+
+func TestTryPruneDir_CachedExpired(t *testing.T) {
+	t.Run("empty directory", func(t *testing.T) {
+		fs := afero.NewMemMapFs()
+		pr, err := newBlobPruner(fs, 0)
+		require.NoError(t, err)
+		var slot primitives.Slot = 0
+		_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, slot, 1)
+		sc, err := verification.BlobSidecarNoop(sidecars[0])
+		require.NoError(t, err)
+		root := fmt.Sprintf("%#x", sc.BlockRoot())
+		require.NoError(t, fs.Mkdir(root, directoryPermissions)) // make empty directory
+		pr.slotMap.ensure(root, sc.Slot())
+		pruned, err := pr.tryPruneDir(root, slot+1)
+		require.NoError(t, err)
+		require.Equal(t, 0, pruned)
+	})
+	t.Run("blobs to delete", func(t *testing.T) {
+		fs, bs, err := NewEphemeralBlobStorageWithFs(t)
+		require.NoError(t, err)
+		var slot primitives.Slot = 0
+		_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, slot, 2)
+		scs, err := verification.BlobSidecarSliceNoop(sidecars)
+		require.NoError(t, err)
+
+		require.NoError(t, bs.Save(scs[0]))
+		require.NoError(t, bs.Save(scs[1]))
+
+		// check that the root->slot is cached
+		root := fmt.Sprintf("%#x", scs[0].BlockRoot())
+		cs, cok := bs.pruner.slotMap.slot(root)
+		require.Equal(t, true, cok)
+		require.Equal(t, slot, cs)
+
+		// ensure that we see the saved files in the filesystem
+		files, err := listDir(fs, root)
+		require.NoError(t, err)
+		require.Equal(t, 2, len(files))
+
+		pruned, err := bs.pruner.tryPruneDir(root, slot+1)
+		require.NoError(t, err)
+		require.Equal(t, 2, pruned)
+		files, err = listDir(fs, root)
+		require.ErrorIs(t, err, os.ErrNotExist)
+		require.Equal(t, 0, len(files))
+	})
+}
+
+func TestTryPruneDir_SlotFromFile(t *testing.T) {
+	t.Run("expired blobs deleted", func(t *testing.T) {
+		fs, bs, err := NewEphemeralBlobStorageWithFs(t)
+		require.NoError(t, err)
+		var slot primitives.Slot = 0
+		_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, slot, 2)
+		scs, err := verification.BlobSidecarSliceNoop(sidecars)
+		require.NoError(t, err)
+
+		require.NoError(t, bs.Save(scs[0]))
+		require.NoError(t, bs.Save(scs[1]))
+
+		// check that the root->slot is cached
+		root := fmt.Sprintf("%#x", scs[0].BlockRoot())
+		cs, ok := bs.pruner.slotMap.slot(root)
+		require.Equal(t, true, ok)
+		require.Equal(t, slot, cs)
+		// evict it from the cache so that we trigger the file read path
+		bs.pruner.slotMap.evict(root)
+		_, ok = bs.pruner.slotMap.slot(root)
+		require.Equal(t, false, ok)
+
+		// ensure that we see the saved files in the filesystem
+		files, err := listDir(fs, root)
+		require.NoError(t, err)
+		require.Equal(t, 2, len(files))
+
+		pruned, err := bs.pruner.tryPruneDir(root, slot+1)
+		require.NoError(t, err)
+		require.Equal(t, 2, pruned)
+		files, err = listDir(fs, root)
+		require.ErrorIs(t, err, os.ErrNotExist)
+		require.Equal(t, 0, len(files))
+	})
+	t.Run("not expired, intact", func(t *testing.T) {
+		fs, bs, err := NewEphemeralBlobStorageWithFs(t)
+		require.NoError(t, err)
+		// Set slot equal to the window size, so it should be retained.
+		var slot primitives.Slot = bs.pruner.windowSize
+		_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, slot, 2)
+		scs, err := verification.BlobSidecarSliceNoop(sidecars)
+		require.NoError(t, err)
+
+		require.NoError(t, bs.Save(scs[0]))
+		require.NoError(t, bs.Save(scs[1]))
+
+		// Evict slot mapping from the cache so that we trigger the file read path.
+		root := fmt.Sprintf("%#x", scs[0].BlockRoot())
+		bs.pruner.slotMap.evict(root)
+		_, ok := bs.pruner.slotMap.slot(root)
+		require.Equal(t, false, ok)
+
+		// Ensure that we see the saved files in the filesystem.
+		files, err := listDir(fs, root)
+		require.NoError(t, err)
+		require.Equal(t, 2, len(files))
+
+		// This should use the slotFromFile code (simulating restart).
+		// Setting pruneBefore == slot, so that the slot will be outside the window (at the boundary).
+		pruned, err := bs.pruner.tryPruneDir(root, slot)
+		require.NoError(t, err)
+		require.Equal(t, 0, pruned)
+
+		// Ensure files are still present.
+		files, err = listDir(fs, root)
+		require.NoError(t, err)
+		require.Equal(t, 2, len(files))
+	})
+}
+
+func TestSlotFromBlob(t *testing.T) {
+	cases := []struct {
+		slot primitives.Slot
+	}{
+		{slot: 0},
+		{slot: 2},
+		{slot: 1123581321},
+		{slot: math.MaxUint64},
+	}
+	for _, c := range cases {
+		t.Run(fmt.Sprintf("slot %d", c.slot), func(t *testing.T) {
+			_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, c.slot, 1)
+			sc := sidecars[0]
+			enc, err := sc.MarshalSSZ()
+			require.NoError(t, err)
+			slot, err := slotFromBlob(bytes.NewReader(enc))
+			require.NoError(t, err)
+			require.Equal(t, c.slot, slot)
+		})
+	}
+}
+
+func TestSlotFromFile(t *testing.T) {
+	cases := []struct {
+		slot primitives.Slot
+	}{
+		{slot: 0},
+		{slot: 2},
+		{slot: 1123581321},
+		{slot: math.MaxUint64},
+	}
+	for _, c := range cases {
+		t.Run(fmt.Sprintf("slot %d", c.slot), func(t *testing.T) {
+			fs, bs, err := NewEphemeralBlobStorageWithFs(t)
+			require.NoError(t, err)
+			_, sidecars := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, c.slot, 1)
+			sc, err := verification.BlobSidecarNoop(sidecars[0])
+			require.NoError(t, err)
+			require.NoError(t, bs.Save(sc))
+			fname := namerForSidecar(sc)
+			sszPath := fname.path()
+			slot, err := slotFromFile(sszPath, fs)
+			require.NoError(t, err)
+			require.Equal(t, c.slot, slot)
+		})
+	}
+}
+
+type dirFiles struct {
+	name     string
+	isDir    bool
+	children []dirFiles
+}
+
+func (df dirFiles) reify(t *testing.T, fs afero.Fs, base string) {
+	fullPath := path.Join(base, df.name)
+	if df.isDir {
+		if df.name != "" {
+			require.NoError(t, fs.Mkdir(fullPath, directoryPermissions))
+		}
+		for _, c := range df.children {
+			c.reify(t, fs, fullPath)
+		}
+	} else {
+		fp, err := fs.Create(fullPath)
+		require.NoError(t, err)
+		_, err = fp.WriteString("derp")
+		require.NoError(t, err)
+	}
+}
+
+func (df dirFiles) childNames() []string {
+	cn := make([]string, len(df.children))
+	for i := range df.children {
+		cn[i] = df.children[i].name
+	}
+	return cn
+}
+
+func TestListDir(t *testing.T) {
+	fs := afero.NewMemMapFs()
+
+	// parent directory
+	fsLayout := dirFiles{isDir: true}
+	// break out each subdir for easier assertions
+	notABlob := dirFiles{name: "notABlob", isDir: true}
+	childlessBlob := dirFiles{name: "0x0987654321", isDir: true}
+	blobWithSsz := dirFiles{name: "0x1123581321", isDir: true,
+		children: []dirFiles{{name: "1.ssz"}, {name: "2.ssz"}},
+	}
+	blobWithSszAndTmp := dirFiles{name: "0x1234567890", isDir: true,
+		children: []dirFiles{{name: "5.ssz"}, {name: "0.part"}}}
+	fsLayout.children = append(fsLayout.children, notABlob)
+	fsLayout.children = append(fsLayout.children, childlessBlob)
+	fsLayout.children = append(fsLayout.children, blobWithSsz)
+	fsLayout.children = append(fsLayout.children, blobWithSszAndTmp)
+
+	topChildren := make([]string, len(fsLayout.children))
+	for i := range fsLayout.children {
+		topChildren[i] = fsLayout.children[i].name
+	}
+
+	fsLayout.reify(t, fs, "")
+	cases := []struct {
+		name     string
+		dirPath  string
+		expected []string
+		filter   func(string) bool
+		err      error
+	}{
+		{
+			name:     "non-existent",
+			dirPath:  "derp",
+			expected: []string{},
+			err:      os.ErrNotExist,
+		},
+		{
+			name:     "empty",
+			dirPath:  childlessBlob.name,
+			expected: []string{},
+		},
+		{
+			name:     "top",
+			dirPath:  ".",
+			expected: topChildren,
+		},
+		{
+			name:     "custom filter: only notABlob",
+			dirPath:  ".",
+			expected: []string{notABlob.name},
+			filter: func(s string) bool {
+				if s == notABlob.name {
+					return true
+				}
+				return false
+			},
+		},
+		{
+			name:     "root filter",
+			dirPath:  ".",
+			expected: []string{childlessBlob.name, blobWithSsz.name, blobWithSszAndTmp.name},
+			filter:   filterRoot,
+		},
+		{
+			name:     "ssz filter",
+			dirPath:  blobWithSsz.name,
+			expected: blobWithSsz.childNames(),
+			filter:   filterSsz,
+		},
+		{
+			name:     "ssz mixed filter",
+			dirPath:  blobWithSszAndTmp.name,
+			expected: []string{"5.ssz"},
+			filter:   filterSsz,
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			result, err := listDir(fs, c.dirPath)
+			if c.filter != nil {
+				result = filter(result, c.filter)
+			}
+			if c.err != nil {
+				require.ErrorIs(t, err, c.err)
+				require.Equal(t, 0, len(result))
+			} else {
+				require.NoError(t, err)
+				sort.Strings(c.expected)
+				sort.Strings(result)
+				require.DeepEqual(t, c.expected, result)
+			}
+		})
+	}
+}
--- a/beacon-chain/db/iface/BUILD.bazel
+++ b/beacon-chain/db/iface/BUILD.bazel
@@ -13,9 +13,11 @@ go_library(
        "//beacon-chain/db/filters:go_default_library",
        "//beacon-chain/slasher/types:go_default_library",
        "//beacon-chain/state:go_default_library",
+        "//consensus-types/blocks:go_default_library",
        "//consensus-types/interfaces:go_default_library",
        "//consensus-types/primitives:go_default_library",
        "//monitoring/backup:go_default_library",
+        "//proto/dbval:go_default_library",
        "//proto/prysm/v1alpha1:go_default_library",
        "@com_github_ethereum_go_ethereum//common:go_default_library",
    ],
--- a/beacon-chain/db/iface/interface.go
+++ b/beacon-chain/db/iface/interface.go
@@ -11,9 +11,11 @@ import (
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db/filters"
 	slashertypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/slasher/types"
 	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
 	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v4/monitoring/backup"
+	"github.com/prysmaticlabs/prysm/v4/proto/dbval"
 	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
 )

@@ -55,12 +57,9 @@ type ReadOnlyDatabase interface {
 	FeeRecipientByValidatorID(ctx context.Context, id primitives.ValidatorIndex) (common.Address, error)
 	RegistrationByValidatorID(ctx context.Context, id primitives.ValidatorIndex) (*ethpb.ValidatorRegistrationV1, error)

-	// Blob operations.
-	BlobSidecarsByRoot(ctx context.Context, beaconBlockRoot [32]byte, indices ...uint64) ([]*ethpb.DeprecatedBlobSidecar, error)
-	BlobSidecarsBySlot(ctx context.Context, slot primitives.Slot, indices ...uint64) ([]*ethpb.DeprecatedBlobSidecar, error)
 	// origin checkpoint sync support
 	OriginCheckpointBlockRoot(ctx context.Context) ([32]byte, error)
-	BackfillBlockRoot(ctx context.Context) ([32]byte, error)
+	BackfillStatus(context.Context) (*dbval.BackfillStatus, error)
 }

 // NoHeadAccessDatabase defines a struct without access to chain head data.
@@ -71,6 +70,7 @@ type NoHeadAccessDatabase interface {
 	DeleteBlock(ctx context.Context, root [32]byte) error
 	SaveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock) error
 	SaveBlocks(ctx context.Context, blocks []interfaces.ReadOnlySignedBeaconBlock) error
+	SaveROBlocks(ctx context.Context, blks []blocks.ROBlock, cache bool) error
 	SaveGenesisBlockRoot(ctx context.Context, blockRoot [32]byte) error
 	// State related methods.
 	SaveState(ctx context.Context, state state.ReadOnlyBeaconState, blockRoot [32]byte) error
@@ -93,9 +93,6 @@ type NoHeadAccessDatabase interface {
 	SaveFeeRecipientsByValidatorIDs(ctx context.Context, ids []primitives.ValidatorIndex, addrs []common.Address) error
 	SaveRegistrationsByValidatorIDs(ctx context.Context, ids []primitives.ValidatorIndex, regs []*ethpb.ValidatorRegistrationV1) error

-	// Blob operations.
-	DeleteBlobSidecars(ctx context.Context, beaconBlockRoot [32]byte) error
-
 	CleanUpDirtyStates(ctx context.Context, slotsPerArchivedPoint primitives.Slot) error
 }

@@ -112,9 +109,10 @@ type HeadAccessDatabase interface {
 	SaveGenesisData(ctx context.Context, state state.BeaconState) error
 	EnsureEmbeddedGenesis(ctx context.Context) error

-	// initialization method needed for origin checkpoint sync
+	// Support for checkpoint sync and backfill.
 	SaveOrigin(ctx context.Context, serState, serBlock []byte) error
-	SaveBackfillBlockRoot(ctx context.Context, blockRoot [32]byte) error
+	SaveBackfillStatus(context.Context, *dbval.BackfillStatus) error
+	BackfillFinalizedIndex(ctx context.Context, blocks []blocks.ROBlock, finalizedChildRoot [32]byte) error
 }

 // SlasherDatabase interface for persisting data related to detecting slashable offenses on Ethereum.
--- a/beacon-chain/db/kv/BUILD.bazel
+++ b/beacon-chain/db/kv/BUILD.bazel
@@ -4,8 +4,8 @@ go_library(
    name = "go_default_library",
    srcs = [
        "archived_point.go",
+        "backfill.go",
        "backup.go",
-        "blob.go",
        "blocks.go",
        "checkpoint.go",
        "deposit_contract.go",
@@ -39,7 +39,6 @@ go_library(
        "//beacon-chain/state/genesis:go_default_library",
        "//beacon-chain/state/state-native: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",
@@ -50,6 +49,7 @@ go_library(
        "//io/file:go_default_library",
        "//monitoring/progress:go_default_library",
        "//monitoring/tracing:go_default_library",
+        "//proto/dbval:go_default_library",
        "//proto/prysm/v1alpha1:go_default_library",
        "//runtime/version:go_default_library",
        "//time:go_default_library",
@@ -75,8 +75,8 @@ go_test(
    name = "go_default_test",
    srcs = [
        "archived_point_test.go",
+        "backfill_test.go",
        "backup_test.go",
-        "blob_test.go",
        "blocks_test.go",
        "checkpoint_test.go",
        "deposit_contract_test.go",
@@ -110,11 +110,11 @@ go_test(
        "//consensus-types/interfaces:go_default_library",
        "//consensus-types/primitives:go_default_library",
        "//encoding/bytesutil:go_default_library",
+        "//proto/dbval:go_default_library",
        "//proto/engine/v1:go_default_library",
        "//proto/prysm/v1alpha1:go_default_library",
        "//proto/testing:go_default_library",
        "//testing/assert:go_default_library",
-        "//testing/assertions:go_default_library",
        "//testing/require:go_default_library",
        "//testing/util:go_default_library",
        "@com_github_ethereum_go_ethereum//common:go_default_library",
--- a/beacon-chain/db/kv/backfill.go
+++ b/beacon-chain/db/kv/backfill.go
@@ -0,0 +1,44 @@
+package kv
+
+import (
+	"context"
+
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v4/proto/dbval"
+	bolt "go.etcd.io/bbolt"
+	"go.opencensus.io/trace"
+	"google.golang.org/protobuf/proto"
+)
+
+// SaveBackfillStatus encodes the given BackfillStatus protobuf struct and writes it to a single key in the db.
+// This value is used by the backfill service to keep track of the range of blocks that need to be synced. It is also used by the
+// code that serves blocks or regenerates states to keep track of what range of blocks are available.
+func (s *Store) SaveBackfillStatus(ctx context.Context, bf *dbval.BackfillStatus) error {
+	_, span := trace.StartSpan(ctx, "BeaconDB.SaveBackfillStatus")
+	defer span.End()
+	bfb, err := proto.Marshal(bf)
+	if err != nil {
+		return err
+	}
+	return s.db.Update(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket(blocksBucket)
+		return bucket.Put(backfillStatusKey, bfb)
+	})
+}
+
+// BackfillStatus retrieves the most recently saved version of the BackfillStatus protobuf struct.
+// This is used to persist information about backfill status across restarts.
+func (s *Store) BackfillStatus(ctx context.Context) (*dbval.BackfillStatus, error) {
+	_, span := trace.StartSpan(ctx, "BeaconDB.BackfillStatus")
+	defer span.End()
+	bf := &dbval.BackfillStatus{}
+	err := s.db.View(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket(blocksBucket)
+		bs := bucket.Get(backfillStatusKey)
+		if len(bs) == 0 {
+			return errors.Wrap(ErrNotFound, "BackfillStatus not found")
+		}
+		return proto.Unmarshal(bs, bf)
+	})
+	return bf, err
+}
--- a/beacon-chain/db/kv/backfill_test.go
+++ b/beacon-chain/db/kv/backfill_test.go
@@ -0,0 +1,35 @@
+package kv
+
+import (
+	"context"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/v4/proto/dbval"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"google.golang.org/protobuf/proto"
+)
+
+func TestBackfillRoundtrip(t *testing.T) {
+	db := setupDB(t)
+	b := &dbval.BackfillStatus{}
+	b.LowSlot = 23
+	b.LowRoot = bytesutil.PadTo([]byte("low"), 32)
+	b.LowParentRoot = bytesutil.PadTo([]byte("parent"), 32)
+	m, err := proto.Marshal(b)
+	require.NoError(t, err)
+	ub := &dbval.BackfillStatus{}
+	require.NoError(t, proto.Unmarshal(m, ub))
+	require.Equal(t, b.LowSlot, ub.LowSlot)
+	require.DeepEqual(t, b.LowRoot, ub.LowRoot)
+	require.DeepEqual(t, b.LowParentRoot, ub.LowParentRoot)
+
+	ctx := context.Background()
+	require.NoError(t, db.SaveBackfillStatus(ctx, b))
+	dbub, err := db.BackfillStatus(ctx)
+	require.NoError(t, err)
+
+	require.Equal(t, b.LowSlot, dbub.LowSlot)
+	require.DeepEqual(t, b.LowRoot, dbub.LowRoot)
+	require.DeepEqual(t, b.LowParentRoot, dbub.LowParentRoot)
+}
--- a/beacon-chain/db/kv/blob.go
+++ b/beacon-chain/db/kv/blob.go
@@ -1,320 +0,0 @@
-package kv
-
-import (
-	"bytes"
-	"context"
-	"sort"
-
-	"github.com/pkg/errors"
-	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
-	"github.com/prysmaticlabs/prysm/v4/config/params"
-	types "github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
-	bolt "go.etcd.io/bbolt"
-	"go.opencensus.io/trace"
-)
-
-var (
-	errBlobSlotMismatch     = errors.New("sidecar slot mismatch")
-	errBlobParentMismatch   = errors.New("sidecar parent root mismatch")
-	errBlobRootMismatch     = errors.New("sidecar root mismatch")
-	errBlobProposerMismatch = errors.New("sidecar proposer index mismatch")
-	errBlobSidecarLimit     = errors.New("sidecar exceeds maximum number of blobs")
-	errEmptySidecar         = errors.New("nil or empty blob sidecars")
-	errNewerBlobExists      = errors.New("Will not overwrite newer blobs in db")
-)
-
-// A blob rotating key is represented as bytes(slot_to_rotating_buffer(blob.slot)) ++ bytes(blob.slot) ++ blob.block_root
-type blobRotatingKey []byte
-
-// BufferPrefix returns the first 8 bytes of the rotating key.
-// This represents bytes(slot_to_rotating_buffer(blob.slot)) in the rotating key.
-func (rk blobRotatingKey) BufferPrefix() []byte {
-	return rk[0:8]
-}
-
-// Slot returns the information from the key.
-func (rk blobRotatingKey) Slot() types.Slot {
-	slotBytes := rk[8:16]
-	return bytesutil.BytesToSlotBigEndian(slotBytes)
-}
-
-// BlockRoot returns the block root information from the key.
-func (rk blobRotatingKey) BlockRoot() []byte {
-	return rk[16:]
-}
-
-// SaveBlobSidecar saves the blobs for a given epoch in the sidecar bucket. When we receive a blob:
-//
-//  1. Convert slot using a modulo operator to [0, maxSlots] where maxSlots = MAX_EPOCHS_TO_PERSIST_BLOBS*SLOTS_PER_EPOCH
-//
-//  2. Compute key for blob as bytes(slot_to_rotating_buffer(blob.slot)) ++ bytes(blob.slot) ++ blob.block_root
-//
-//  3. Begin the save algorithm:  If the incoming blob has a slot bigger than the saved slot at the spot
-//     in the rotating keys buffer, we overwrite all elements for that slot. Otherwise, we merge the blob with an existing one.
-//     Trying to replace a newer blob with an older one is an error.
-func (s *Store) SaveBlobSidecar(ctx context.Context, scs []*ethpb.DeprecatedBlobSidecar) error {
-	if len(scs) == 0 {
-		return errEmptySidecar
-	}
-	ctx, span := trace.StartSpan(ctx, "BeaconDB.SaveBlobSidecar")
-	defer span.End()
-
-	first := scs[0]
-	newKey := s.blobSidecarKey(first)
-	prefix := newKey.BufferPrefix()
-	var prune []blobRotatingKey
-	return s.db.Update(func(tx *bolt.Tx) error {
-		var existing []byte
-		sc := &ethpb.DeprecatedBlobSidecars{}
-		bkt := tx.Bucket(blobsBucket)
-		c := bkt.Cursor()
-		for k, v := c.Seek(prefix); bytes.HasPrefix(k, prefix); k, v = c.Next() {
-			key := blobRotatingKey(k)
-			ks := key.Slot()
-			if ks < first.Slot {
-				// Mark older blobs at the same position of the ring buffer for deletion.
-				prune = append(prune, key)
-				continue
-			}
-			if ks > first.Slot {
-				// We shouldn't be overwriting newer blobs with older blobs. Something is wrong.
-				return errNewerBlobExists
-			}
-			// The slot isn't older or newer, so it must be equal.
-			// If the roots match, then we want to merge the new sidecars with the existing data.
-			if bytes.Equal(first.BlockRoot, key.BlockRoot()) {
-				existing = v
-				if err := decode(ctx, v, sc); err != nil {
-					return err
-				}
-			}
-			// If the slot is equal but the roots don't match, leave the existing key alone and allow the sidecar
-			// to be written to the new key with the same prefix. In this case sc will be empty, so it will just
-			// contain the incoming sidecars when we write it.
-		}
-		sc.Sidecars = append(sc.Sidecars, scs...)
-		sortSidecars(sc.Sidecars)
-		var err error
-		sc.Sidecars, err = validUniqueSidecars(sc.Sidecars)
-		if err != nil {
-			return err
-		}
-		encoded, err := encode(ctx, sc)
-		if err != nil {
-			return err
-		}
-		// don't write if the merged result is the same as before
-		if len(existing) == len(encoded) && bytes.Equal(existing, encoded) {
-			return nil
-		}
-		// Only prune if we're actually going through with the update.
-		for _, k := range prune {
-			if err := bkt.Delete(k); err != nil {
-				// note: attempting to delete a key that does not exist should not return an error.
-				log.WithError(err).Warnf("Could not delete blob key %#x.", k)
-			}
-		}
-		return bkt.Put(newKey, encoded)
-	})
-}
-
-// validUniqueSidecars ensures that all sidecars have the same slot, parent root, block root, and proposer index, and
-// there are no more than MAX_BLOBS_PER_BLOCK sidecars.
-func validUniqueSidecars(scs []*ethpb.DeprecatedBlobSidecar) ([]*ethpb.DeprecatedBlobSidecar, error) {
-	if len(scs) == 0 {
-		return nil, errEmptySidecar
-	}
-
-	// If there's only 1 sidecar, we've got nothing to compare.
-	if len(scs) == 1 {
-		return scs, nil
-	}
-
-	prev := scs[0]
-	didx := 1
-	for i := 1; i < len(scs); i++ {
-		sc := scs[i]
-		if sc.Slot != prev.Slot {
-			return nil, errors.Wrapf(errBlobSlotMismatch, "%d != %d", sc.Slot, prev.Slot)
-		}
-		if !bytes.Equal(sc.BlockParentRoot, prev.BlockParentRoot) {
-			return nil, errors.Wrapf(errBlobParentMismatch, "%x != %x", sc.BlockParentRoot, prev.BlockParentRoot)
-		}
-		if !bytes.Equal(sc.BlockRoot, prev.BlockRoot) {
-			return nil, errors.Wrapf(errBlobRootMismatch, "%x != %x", sc.BlockRoot, prev.BlockRoot)
-		}
-		if sc.ProposerIndex != prev.ProposerIndex {
-			return nil, errors.Wrapf(errBlobProposerMismatch, "%d != %d", sc.ProposerIndex, prev.ProposerIndex)
-		}
-		// skip duplicate
-		if sc.Index == prev.Index {
-			continue
-		}
-		if didx != i {
-			scs[didx] = scs[i]
-		}
-		prev = scs[i]
-		didx += 1
-	}
-
-	if didx > fieldparams.MaxBlobsPerBlock {
-		return nil, errors.Wrapf(errBlobSidecarLimit, "%d > %d", didx, fieldparams.MaxBlobsPerBlock)
-	}
-	return scs[0:didx], nil
-}
-
-// sortSidecars sorts the sidecars by their index.
-func sortSidecars(scs []*ethpb.DeprecatedBlobSidecar) {
-	sort.Slice(scs, func(i, j int) bool {
-		return scs[i].Index < scs[j].Index
-	})
-}
-
-// BlobSidecarsByRoot retrieves the blobs for the given beacon block root.
-// If the `indices` argument is omitted, all blobs for the root will be returned.
-// Otherwise, the result will be filtered to only include the specified indices.
-// An error will result if an invalid index is specified.
-// The bucket size is bounded by 131072 entries. That's the most blobs a node will keep before rotating it out.
-func (s *Store) BlobSidecarsByRoot(ctx context.Context, root [32]byte, indices ...uint64) ([]*ethpb.DeprecatedBlobSidecar, error) {
-	ctx, span := trace.StartSpan(ctx, "BeaconDB.BlobSidecarsByRoot")
-	defer span.End()
-
-	var enc []byte
-	if err := s.db.View(func(tx *bolt.Tx) error {
-		c := tx.Bucket(blobsBucket).Cursor()
-		// Bucket size is bounded and bolt cursors are fast. Moreover, a thin caching layer can be added.
-		for k, v := c.First(); k != nil; k, v = c.Next() {
-			if bytes.HasSuffix(k, root[:]) {
-				enc = v
-				break
-			}
-		}
-		return nil
-	}); err != nil {
-		return nil, err
-	}
-	if enc == nil {
-		return nil, ErrNotFound
-	}
-	sc := &ethpb.DeprecatedBlobSidecars{}
-	if err := decode(ctx, enc, sc); err != nil {
-		return nil, err
-	}
-
-	return filterForIndices(sc, indices...)
-}
-
-func filterForIndices(sc *ethpb.DeprecatedBlobSidecars, indices ...uint64) ([]*ethpb.DeprecatedBlobSidecar, error) {
-	if len(indices) == 0 {
-		return sc.Sidecars, nil
-	}
-	// This loop assumes that the BlobSidecars value stores the complete set of blobs for a block
-	// in ascending order from eg 0..3, without gaps. This allows us to assume the indices argument
-	// maps 1:1 with indices in the BlobSidecars storage object.
-	maxIdx := uint64(len(sc.Sidecars)) - 1
-	sidecars := make([]*ethpb.DeprecatedBlobSidecar, len(indices))
-	for i, idx := range indices {
-		if idx > maxIdx {
-			return nil, errors.Wrapf(ErrNotFound, "BlobSidecars missing index: index %d", idx)
-		}
-		sidecars[i] = sc.Sidecars[idx]
-	}
-	return sidecars, nil
-}
-
-// BlobSidecarsBySlot retrieves BlobSidecars for the given slot.
-// If the `indices` argument is omitted, all blobs for the slot will be returned.
-// Otherwise, the result will be filtered to only include the specified indices.
-// An error will result if an invalid index is specified.
-// The bucket size is bounded by 131072 entries. That's the most blobs a node will keep before rotating it out.
-func (s *Store) BlobSidecarsBySlot(ctx context.Context, slot types.Slot, indices ...uint64) ([]*ethpb.DeprecatedBlobSidecar, error) {
-	ctx, span := trace.StartSpan(ctx, "BeaconDB.BlobSidecarsBySlot")
-	defer span.End()
-
-	var enc []byte
-	sk := s.slotKey(slot)
-	if err := s.db.View(func(tx *bolt.Tx) error {
-		c := tx.Bucket(blobsBucket).Cursor()
-		// Bucket size is bounded and bolt cursors are fast. Moreover, a thin caching layer can be added.
-		for k, v := c.Seek(sk); bytes.HasPrefix(k, sk); k, _ = c.Next() {
-			slotInKey := bytesutil.BytesToSlotBigEndian(k[8:16])
-			if slotInKey == slot {
-				enc = v
-				break
-			}
-		}
-		return nil
-	}); err != nil {
-		return nil, err
-	}
-	if enc == nil {
-		return nil, ErrNotFound
-	}
-	sc := &ethpb.DeprecatedBlobSidecars{}
-	if err := decode(ctx, enc, sc); err != nil {
-		return nil, err
-	}
-
-	return filterForIndices(sc, indices...)
-}
-
-// DeleteBlobSidecars returns true if the blobs are in the db.
-func (s *Store) DeleteBlobSidecars(ctx context.Context, beaconBlockRoot [32]byte) error {
-	_, span := trace.StartSpan(ctx, "BeaconDB.DeleteBlobSidecar")
-	defer span.End()
-	return s.db.Update(func(tx *bolt.Tx) error {
-		bkt := tx.Bucket(blobsBucket)
-		c := bkt.Cursor()
-		for k, _ := c.First(); k != nil; k, _ = c.Next() {
-			if bytes.HasSuffix(k, beaconBlockRoot[:]) {
-				if err := bkt.Delete(k); err != nil {
-					return err
-				}
-			}
-		}
-		return nil
-	})
-}
-
-// We define a blob sidecar key as: bytes(slot_to_rotating_buffer(blob.slot)) ++ bytes(blob.slot) ++ blob.block_root
-// where slot_to_rotating_buffer(slot) = slot % MAX_SLOTS_TO_PERSIST_BLOBS.
-func (s *Store) blobSidecarKey(blob *ethpb.DeprecatedBlobSidecar) blobRotatingKey {
-	key := s.slotKey(blob.Slot)
-	key = append(key, bytesutil.SlotToBytesBigEndian(blob.Slot)...)
-	key = append(key, blob.BlockRoot...)
-	return key
-}
-
-func (s *Store) slotKey(slot types.Slot) []byte {
-	return bytesutil.SlotToBytesBigEndian(slot.ModSlot(s.blobRetentionSlots()))
-}
-
-func (s *Store) blobRetentionSlots() types.Slot {
-	return types.Slot(s.blobRetentionEpochs.Mul(uint64(params.BeaconConfig().SlotsPerEpoch)))
-}
-
-var errBlobRetentionEpochMismatch = errors.New("epochs for blobs request value in DB does not match runtime config")
-
-func (s *Store) checkEpochsForBlobSidecarsRequestBucket(db *bolt.DB) error {
-	uRetentionEpochs := uint64(s.blobRetentionEpochs)
-	if err := db.Update(func(tx *bolt.Tx) error {
-		b := tx.Bucket(chainMetadataBucket)
-		v := b.Get(blobRetentionEpochsKey)
-		if v == nil {
-			if err := b.Put(blobRetentionEpochsKey, bytesutil.Uint64ToBytesBigEndian(uRetentionEpochs)); err != nil {
-				return err
-			}
-			return nil
-		}
-		e := bytesutil.BytesToUint64BigEndian(v)
-		if e != uRetentionEpochs {
-			return errors.Wrapf(errBlobRetentionEpochMismatch, "db=%d, config=%d", e, uRetentionEpochs)
-		}
-		return nil
-	}); err != nil {
-		return err
-	}
-	return nil
-}
--- a/beacon-chain/db/kv/blob_test.go
+++ b/beacon-chain/db/kv/blob_test.go
@@ -1,532 +0,0 @@
-package kv
-
-import (
-	"context"
-	"crypto/rand"
-	"fmt"
-	"testing"
-
-	"github.com/pkg/errors"
-	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
-	"github.com/prysmaticlabs/prysm/v4/config/params"
-	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
-	types "github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v4/testing/assertions"
-	"github.com/prysmaticlabs/prysm/v4/testing/require"
-	bolt "go.etcd.io/bbolt"
-)
-
-func equalBlobSlices(expect []*ethpb.DeprecatedBlobSidecar, got []*ethpb.DeprecatedBlobSidecar) error {
-	if len(expect) != len(got) {
-		return fmt.Errorf("mismatched lengths, expect=%d, got=%d", len(expect), len(got))
-	}
-	for i := 0; i < len(expect); i++ {
-		es := expect[i]
-		gs := got[i]
-		var e string
-		assertions.DeepEqual(assertions.SprintfAssertionLoggerFn(&e), es, gs)
-		if e != "" {
-			return errors.New(e)
-		}
-	}
-	return nil
-}
-
-func TestStore_BlobSidecars(t *testing.T) {
-	ctx := context.Background()
-
-	t.Run("empty", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, 0)
-		require.ErrorContains(t, "nil or empty blob sidecars", db.SaveBlobSidecar(ctx, scs))
-	})
-	t.Run("empty by root", func(t *testing.T) {
-		db := setupDB(t)
-		got, err := db.BlobSidecarsByRoot(ctx, [32]byte{})
-		require.ErrorIs(t, ErrNotFound, err)
-		require.Equal(t, 0, len(got))
-	})
-	t.Run("empty by slot", func(t *testing.T) {
-		db := setupDB(t)
-		got, err := db.BlobSidecarsBySlot(ctx, 1)
-		require.ErrorIs(t, ErrNotFound, err)
-		require.Equal(t, 0, len(got))
-	})
-	t.Run("save and retrieve by root (one)", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, 1)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, 1, len(scs))
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save and retrieve by root (max), per batch", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save and retrieve by root, max and individually", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		for _, sc := range scs {
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{sc}))
-		}
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save and retrieve valid subset by root", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-
-		// we'll request indices 0 and 3, so make a slice with those indices for comparison
-		expect := make([]*ethpb.DeprecatedBlobSidecar, 2)
-		expect[0] = scs[0]
-		expect[1] = scs[3]
-
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot), 0, 3)
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(expect, got))
-		require.Equal(t, uint64(0), got[0].Index)
-		require.Equal(t, uint64(3), got[1].Index)
-	})
-	t.Run("error for invalid index when retrieving by root", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot), uint64(len(scs)))
-		require.ErrorIs(t, err, ErrNotFound)
-		require.Equal(t, 0, len(got))
-	})
-	t.Run("save and retrieve by slot (one)", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, 1)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, 1, len(scs))
-		got, err := db.BlobSidecarsBySlot(ctx, scs[0].Slot)
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save and retrieve by slot (max)", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-		got, err := db.BlobSidecarsBySlot(ctx, scs[0].Slot)
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save and retrieve by slot, max and individually", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		for _, sc := range scs {
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{sc}))
-		}
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-		got, err := db.BlobSidecarsBySlot(ctx, scs[0].Slot)
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save and retrieve valid subset by slot", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-
-		// we'll request indices 0 and 3, so make a slice with those indices for comparison
-		expect := make([]*ethpb.DeprecatedBlobSidecar, 2)
-		expect[0] = scs[0]
-		expect[1] = scs[3]
-
-		got, err := db.BlobSidecarsBySlot(ctx, scs[0].Slot, 0, 3)
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(expect, got))
-
-		require.Equal(t, uint64(0), got[0].Index)
-		require.Equal(t, uint64(3), got[1].Index)
-	})
-	t.Run("error for invalid index when retrieving by slot", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-
-		got, err := db.BlobSidecarsBySlot(ctx, scs[0].Slot, uint64(len(scs)))
-		require.ErrorIs(t, err, ErrNotFound)
-		require.Equal(t, 0, len(got))
-	})
-	t.Run("delete works", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-		require.NoError(t, db.DeleteBlobSidecars(ctx, bytesutil.ToBytes32(scs[0].BlockRoot)))
-		got, err = db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.ErrorIs(t, ErrNotFound, err)
-		require.Equal(t, 0, len(got))
-	})
-	t.Run("saving blob different times", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-
-		for i := 0; i < fieldparams.MaxBlobsPerBlock; i++ {
-			scs[i].Slot = primitives.Slot(i)
-			scs[i].BlockRoot = bytesutil.PadTo([]byte{byte(i)}, 32)
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{scs[i]}))
-			br := bytesutil.ToBytes32(scs[i].BlockRoot)
-			saved, err := db.BlobSidecarsByRoot(ctx, br)
-			require.NoError(t, err)
-			require.NoError(t, equalBlobSlices([]*ethpb.DeprecatedBlobSidecar{scs[i]}, saved))
-		}
-	})
-	t.Run("saving a new blob for rotation (batch)", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-		oldBlockRoot := scs[0].BlockRoot
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(oldBlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-
-		newScs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		newRetentionSlot := primitives.Slot(params.BeaconConfig().MinEpochsForBlobsSidecarsRequest.Mul(uint64(params.BeaconConfig().SlotsPerEpoch)))
-		for _, sc := range newScs {
-			sc.Slot = sc.Slot + newRetentionSlot
-		}
-		require.NoError(t, db.SaveBlobSidecar(ctx, newScs))
-
-		_, err = db.BlobSidecarsBySlot(ctx, 100)
-		require.ErrorIs(t, ErrNotFound, err)
-
-		got, err = db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(newScs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(newScs, got))
-	})
-	t.Run("save multiple blobs after new rotation (individually)", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		for _, sc := range scs {
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{sc}))
-		}
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-
-		scs = generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		newRetentionSlot := primitives.Slot(params.BeaconConfig().MinEpochsForBlobsSidecarsRequest.Mul(uint64(params.BeaconConfig().SlotsPerEpoch)))
-		for _, sc := range scs {
-			sc.Slot = sc.Slot + newRetentionSlot
-		}
-		for _, sc := range scs {
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{sc}))
-		}
-
-		_, err = db.BlobSidecarsBySlot(ctx, 100)
-		require.ErrorIs(t, ErrNotFound, err)
-
-		got, err = db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save multiple blobs after new rotation (batch then individually)", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-		require.Equal(t, fieldparams.MaxBlobsPerBlock, len(scs))
-		oldBlockRoot := scs[0].BlockRoot
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(oldBlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-
-		scs = generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		newRetentionSlot := primitives.Slot(params.BeaconConfig().MinEpochsForBlobsSidecarsRequest.Mul(uint64(params.BeaconConfig().SlotsPerEpoch)))
-		for _, sc := range scs {
-			sc.Slot = sc.Slot + newRetentionSlot
-		}
-		for _, sc := range scs {
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{sc}))
-		}
-
-		_, err = db.BlobSidecarsBySlot(ctx, 100)
-		require.ErrorIs(t, ErrNotFound, err)
-
-		got, err = db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save multiple blobs after new rotation (individually then batch)", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		for _, sc := range scs {
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{sc}))
-		}
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-
-		scs = generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock)
-		newRetentionSlot := primitives.Slot(params.BeaconConfig().MinEpochsForBlobsSidecarsRequest.Mul(uint64(params.BeaconConfig().SlotsPerEpoch)))
-		for _, sc := range scs {
-			sc.Slot = sc.Slot + newRetentionSlot
-		}
-		require.NoError(t, db.SaveBlobSidecar(ctx, scs))
-
-		_, err = db.BlobSidecarsBySlot(ctx, 100)
-		require.ErrorIs(t, ErrNotFound, err)
-
-		got, err = db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-	})
-	t.Run("save equivocating blobs", func(t *testing.T) {
-		db := setupDB(t)
-		scs := generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock/2)
-		eScs := generateEquivocatingBlobSidecars(t, fieldparams.MaxBlobsPerBlock/2)
-
-		for i, sc := range scs {
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{sc}))
-			require.NoError(t, db.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{eScs[i]}))
-		}
-
-		got, err := db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(scs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(scs, got))
-
-		got, err = db.BlobSidecarsByRoot(ctx, bytesutil.ToBytes32(eScs[0].BlockRoot))
-		require.NoError(t, err)
-		require.NoError(t, equalBlobSlices(eScs, got))
-	})
-}
-
-func generateBlobSidecars(t *testing.T, n uint64) []*ethpb.DeprecatedBlobSidecar {
-	blobSidecars := make([]*ethpb.DeprecatedBlobSidecar, n)
-	for i := uint64(0); i < n; i++ {
-		blobSidecars[i] = generateBlobSidecar(t, i)
-	}
-	return blobSidecars
-}
-
-func generateBlobSidecar(t *testing.T, index uint64) *ethpb.DeprecatedBlobSidecar {
-	blob := make([]byte, 131072)
-	_, err := rand.Read(blob)
-	require.NoError(t, err)
-	kzgCommitment := make([]byte, 48)
-	_, err = rand.Read(kzgCommitment)
-	require.NoError(t, err)
-	kzgProof := make([]byte, 48)
-	_, err = rand.Read(kzgProof)
-	require.NoError(t, err)
-	return &ethpb.DeprecatedBlobSidecar{
-		BlockRoot:       bytesutil.PadTo([]byte{'a'}, 32),
-		Index:           index,
-		Slot:            100,
-		BlockParentRoot: bytesutil.PadTo([]byte{'b'}, 32),
-		ProposerIndex:   101,
-		Blob:            blob,
-		KzgCommitment:   kzgCommitment,
-		KzgProof:        kzgProof,
-	}
-}
-
-func generateEquivocatingBlobSidecars(t *testing.T, n uint64) []*ethpb.DeprecatedBlobSidecar {
-	blobSidecars := make([]*ethpb.DeprecatedBlobSidecar, n)
-	for i := uint64(0); i < n; i++ {
-		blobSidecars[i] = generateEquivocatingBlobSidecar(t, i)
-	}
-	return blobSidecars
-}
-
-func generateEquivocatingBlobSidecar(t *testing.T, index uint64) *ethpb.DeprecatedBlobSidecar {
-	blob := make([]byte, 131072)
-	_, err := rand.Read(blob)
-	require.NoError(t, err)
-	kzgCommitment := make([]byte, 48)
-	_, err = rand.Read(kzgCommitment)
-	require.NoError(t, err)
-	kzgProof := make([]byte, 48)
-	_, err = rand.Read(kzgProof)
-	require.NoError(t, err)
-
-	return &ethpb.DeprecatedBlobSidecar{
-		BlockRoot:       bytesutil.PadTo([]byte{'c'}, 32),
-		Index:           index,
-		Slot:            100,
-		BlockParentRoot: bytesutil.PadTo([]byte{'b'}, 32),
-		ProposerIndex:   102,
-		Blob:            blob,
-		KzgCommitment:   kzgCommitment,
-		KzgProof:        kzgProof,
-	}
-}
-
-func Test_validUniqueSidecars_validation(t *testing.T) {
-	tests := []struct {
-		name string
-		scs  []*ethpb.DeprecatedBlobSidecar
-		err  error
-	}{
-		{name: "empty", scs: []*ethpb.DeprecatedBlobSidecar{}, err: errEmptySidecar},
-		{name: "too many sidecars", scs: generateBlobSidecars(t, fieldparams.MaxBlobsPerBlock+1), err: errBlobSidecarLimit},
-		{name: "invalid slot", scs: []*ethpb.DeprecatedBlobSidecar{{Slot: 1}, {Slot: 2}}, err: errBlobSlotMismatch},
-		{name: "invalid proposer index", scs: []*ethpb.DeprecatedBlobSidecar{{ProposerIndex: 1}, {ProposerIndex: 2}}, err: errBlobProposerMismatch},
-		{name: "invalid root", scs: []*ethpb.DeprecatedBlobSidecar{{BlockRoot: []byte{1}}, {BlockRoot: []byte{2}}}, err: errBlobRootMismatch},
-		{name: "invalid parent root", scs: []*ethpb.DeprecatedBlobSidecar{{BlockParentRoot: []byte{1}}, {BlockParentRoot: []byte{2}}}, err: errBlobParentMismatch},
-		{name: "happy path", scs: []*ethpb.DeprecatedBlobSidecar{{Index: 0}, {Index: 1}}},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			_, err := validUniqueSidecars(tt.scs)
-			if tt.err != nil {
-				require.ErrorIs(t, err, tt.err)
-			} else {
-				require.NoError(t, err)
-			}
-		})
-	}
-}
-
-func Test_validUniqueSidecars_dedup(t *testing.T) {
-	cases := []struct {
-		name     string
-		scs      []*ethpb.DeprecatedBlobSidecar
-		expected []*ethpb.DeprecatedBlobSidecar
-		err      error
-	}{
-		{
-			name:     "duplicate sidecar",
-			scs:      []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 1}},
-			expected: []*ethpb.DeprecatedBlobSidecar{{Index: 1}},
-		},
-		{
-			name:     "single sidecar",
-			scs:      []*ethpb.DeprecatedBlobSidecar{{Index: 1}},
-			expected: []*ethpb.DeprecatedBlobSidecar{{Index: 1}},
-		},
-		{
-			name:     "multiple duplicates",
-			scs:      []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 2}, {Index: 2}, {Index: 3}, {Index: 3}},
-			expected: []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 2}, {Index: 3}},
-		},
-		{
-			name:     "ok number after de-dupe, > 6 before",
-			scs:      []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 2}, {Index: 2}, {Index: 2}, {Index: 2}, {Index: 3}, {Index: 3}},
-			expected: []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 2}, {Index: 3}},
-		},
-		{
-			name:     "max unique, no dupes",
-			scs:      []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 2}, {Index: 3}, {Index: 4}, {Index: 5}, {Index: 6}},
-			expected: []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 2}, {Index: 3}, {Index: 4}, {Index: 5}, {Index: 6}},
-		},
-		{
-			name: "too many unique",
-			scs:  []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 2}, {Index: 3}, {Index: 4}, {Index: 5}, {Index: 6}, {Index: 7}},
-			err:  errBlobSidecarLimit,
-		},
-		{
-			name: "too many unique with dupes",
-			scs:  []*ethpb.DeprecatedBlobSidecar{{Index: 1}, {Index: 1}, {Index: 1}, {Index: 2}, {Index: 3}, {Index: 4}, {Index: 5}, {Index: 6}, {Index: 7}},
-			err:  errBlobSidecarLimit,
-		},
-	}
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			u, err := validUniqueSidecars(c.scs)
-			if c.err != nil {
-				require.ErrorIs(t, err, c.err)
-			} else {
-				require.NoError(t, err)
-			}
-			require.Equal(t, len(c.expected), len(u))
-		})
-	}
-}
-
-func TestStore_sortSidecars(t *testing.T) {
-	scs := []*ethpb.DeprecatedBlobSidecar{
-		{Index: 6},
-		{Index: 4},
-		{Index: 2},
-		{Index: 1},
-		{Index: 3},
-		{Index: 5},
-		{},
-	}
-	sortSidecars(scs)
-	for i := 0; i < len(scs)-1; i++ {
-		require.Equal(t, uint64(i), scs[i].Index)
-	}
-}
-
-func BenchmarkStore_BlobSidecarsByRoot(b *testing.B) {
-	s := setupDB(b)
-	ctx := context.Background()
-	require.NoError(b, s.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{
-		{BlockRoot: bytesutil.PadTo([]byte{'a'}, 32), Slot: 0},
-	}))
-
-	err := s.db.Update(func(tx *bolt.Tx) error {
-		bkt := tx.Bucket(blobsBucket)
-		for i := 1; i < 131071; i++ {
-			r := make([]byte, 32)
-			_, err := rand.Read(r)
-			require.NoError(b, err)
-			scs := []*ethpb.DeprecatedBlobSidecar{
-				{BlockRoot: r, Slot: primitives.Slot(i)},
-			}
-			k := s.blobSidecarKey(scs[0])
-			encodedBlobSidecar, err := encode(ctx, &ethpb.DeprecatedBlobSidecars{Sidecars: scs})
-			require.NoError(b, err)
-			require.NoError(b, bkt.Put(k, encodedBlobSidecar))
-		}
-		return nil
-	})
-	require.NoError(b, err)
-
-	require.NoError(b, s.SaveBlobSidecar(ctx, []*ethpb.DeprecatedBlobSidecar{
-		{BlockRoot: bytesutil.PadTo([]byte{'b'}, 32), Slot: 131071},
-	}))
-
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		_, err := s.BlobSidecarsByRoot(ctx, [32]byte{'b'})
-		require.NoError(b, err)
-	}
-}
-
-func Test_checkEpochsForBlobSidecarsRequestBucket(t *testing.T) {
-	s := setupDB(t)
-
-	require.NoError(t, s.checkEpochsForBlobSidecarsRequestBucket(s.db)) // First write
-	require.NoError(t, s.checkEpochsForBlobSidecarsRequestBucket(s.db)) // First check
-
-	s.blobRetentionEpochs += 1
-	require.ErrorIs(t, s.checkEpochsForBlobSidecarsRequestBucket(s.db), errBlobRetentionEpochMismatch)
-}
-
-func TestBlobRotatingKey(t *testing.T) {
-	s := setupDB(t)
-	k := s.blobSidecarKey(&ethpb.DeprecatedBlobSidecar{
-		Slot:      1,
-		BlockRoot: []byte{2},
-	})
-
-	require.Equal(t, types.Slot(1), k.Slot())
-	require.DeepEqual(t, []byte{2}, k.BlockRoot())
-	require.DeepEqual(t, s.slotKey(types.Slot(1)), k.BufferPrefix())
-}
--- a/beacon-chain/db/kv/blocks.go
+++ b/beacon-chain/db/kv/blocks.go
@@ -70,25 +70,6 @@ func (s *Store) OriginCheckpointBlockRoot(ctx context.Context) ([32]byte, error)
 	return root, err
 }

-// BackfillBlockRoot keeps track of the highest block available before the OriginCheckpointBlockRoot
-func (s *Store) BackfillBlockRoot(ctx context.Context) ([32]byte, error) {
-	_, span := trace.StartSpan(ctx, "BeaconDB.BackfillBlockRoot")
-	defer span.End()
-
-	var root [32]byte
-	err := s.db.View(func(tx *bolt.Tx) error {
-		bkt := tx.Bucket(blocksBucket)
-		rootSlice := bkt.Get(backfillBlockRootKey)
-		if len(rootSlice) == 0 {
-			return ErrNotFoundBackfillBlockRoot
-		}
-		root = bytesutil.ToBytes32(rootSlice)
-		return nil
-	})
-
-	return root, err
-}
-
 // HeadBlock returns the latest canonical block in the Ethereum Beacon Chain.
 func (s *Store) HeadBlock(ctx context.Context) (interfaces.ReadOnlySignedBeaconBlock, error) {
 	ctx, span := trace.StartSpan(ctx, "BeaconDB.HeadBlock")
@@ -292,55 +273,95 @@ func (s *Store) SaveBlocks(ctx context.Context, blks []interfaces.ReadOnlySigned
 	ctx, span := trace.StartSpan(ctx, "BeaconDB.SaveBlocks")
 	defer span.End()

-	// Performing marshaling, hashing, and indexing outside the bolt transaction
-	// to minimize the time we hold the DB lock.
-	blockRoots := make([][]byte, len(blks))
-	encodedBlocks := make([][]byte, len(blks))
-	indicesForBlocks := make([]map[string][]byte, len(blks))
-	for i, blk := range blks {
-		blockRoot, err := blk.Block().HashTreeRoot()
+	robs := make([]blocks.ROBlock, len(blks))
+	for i := range blks {
+		rb, err := blocks.NewROBlock(blks[i])
 		if err != nil {
-			return err
+			return errors.Wrapf(err, "failed to make an ROBlock for a block in SaveBlocks")
 		}
-		enc, err := s.marshalBlock(ctx, blk)
-		if err != nil {
-			return err
-		}
-		blockRoots[i] = blockRoot[:]
-		encodedBlocks[i] = enc
-		indicesByBucket := createBlockIndicesFromBlock(ctx, blk.Block())
-		indicesForBlocks[i] = indicesByBucket
+		robs[i] = rb
 	}
-	saveBlinded, err := s.shouldSaveBlinded(ctx)
+	return s.SaveROBlocks(ctx, robs, true)
+}
+
+type blockBatchEntry struct {
+	root    []byte
+	block   interfaces.ReadOnlySignedBeaconBlock
+	enc     []byte
+	updated bool
+	indices map[string][]byte
+}
+
+func prepareBlockBatch(blks []blocks.ROBlock, shouldBlind bool) ([]blockBatchEntry, error) {
+	batch := make([]blockBatchEntry, len(blks))
+	for i := range blks {
+		batch[i].root, batch[i].block = blks[i].RootSlice(), blks[i].ReadOnlySignedBeaconBlock
+		batch[i].indices = blockIndices(batch[i].block.Block().Slot(), batch[i].block.Block().ParentRoot())
+		if shouldBlind {
+			blinded, err := batch[i].block.ToBlinded()
+			if err != nil {
+				if !errors.Is(err, blocks.ErrUnsupportedVersion) {
+					return nil, errors.Wrapf(err, "could not convert block to blinded format for root %#x", batch[i].root)
+				}
+				// Pre-deneb blocks give ErrUnsupportedVersion; use the full block already in the batch entry.
+			} else {
+				batch[i].block = blinded
+			}
+		}
+		enc, err := encodeBlock(batch[i].block)
+		if err != nil {
+			return nil, errors.Wrapf(err, "failed to encode block for root %#x", batch[i].root)
+		}
+		batch[i].enc = enc
+	}
+	return batch, nil
+}
+
+func (s *Store) SaveROBlocks(ctx context.Context, blks []blocks.ROBlock, cache bool) error {
+	shouldBlind, err := s.shouldSaveBlinded(ctx)
 	if err != nil {
 		return err
 	}
-	return s.db.Update(func(tx *bolt.Tx) error {
+	// Precompute expensive values outside the db transaction.
+	batch, err := prepareBlockBatch(blks, shouldBlind)
+	if err != nil {
+		return errors.Wrap(err, "failed to encode all blocks in batch for saving to the db")
+	}
+	err = s.db.Update(func(tx *bolt.Tx) error {
 		bkt := tx.Bucket(blocksBucket)
-		for i, blk := range blks {
-			if existingBlock := bkt.Get(blockRoots[i]); existingBlock != nil {
+		for i := range batch {
+			if exists := bkt.Get(batch[i].root); exists != nil {
 				continue
 			}
-			if err := updateValueForIndices(ctx, indicesForBlocks[i], blockRoots[i], tx); err != nil {
-				return errors.Wrap(err, "could not update DB indices")
+			if err := bkt.Put(batch[i].root, batch[i].enc); err != nil {
+				return errors.Wrapf(err, "could write block to db with root %#x", batch[i].root)
 			}
-			if saveBlinded {
-				blindedBlock, err := blk.ToBlinded()
-				if err != nil {
-					if !errors.Is(err, blocks.ErrUnsupportedVersion) {
-						return err
-					}
-				} else {
-					blk = blindedBlock
-				}
-			}
-			s.blockCache.Set(string(blockRoots[i]), blk, int64(len(encodedBlocks[i])))
-			if err := bkt.Put(blockRoots[i], encodedBlocks[i]); err != nil {
-				return err
+			if err := updateValueForIndices(ctx, batch[i].indices, batch[i].root, tx); err != nil {
+				return errors.Wrapf(err, "could not update DB indices for root %#x", batch[i].root)
 			}
+			batch[i].updated = true
 		}
 		return nil
 	})
+	if !cache {
+		return err
+	}
+	for i := range batch {
+		if batch[i].updated {
+			s.blockCache.Set(string(batch[i].root), batch[i].block, int64(len(batch[i].enc)))
+		}
+	}
+	return err
+}
+
+// blockIndices takes in a beacon block and returns
+// a map of bolt DB index buckets corresponding to each particular key for indices for
+// data, such as (shard indices bucket -> shard 5).
+func blockIndices(slot primitives.Slot, parentRoot [32]byte) map[string][]byte {
+	return map[string][]byte{
+		string(blockSlotIndicesBucket):       bytesutil.SlotToBytesBigEndian(slot),
+		string(blockParentRootIndicesBucket): parentRoot[:],
+	}
 }

 // SaveHeadBlockRoot to the db.
@@ -417,17 +438,6 @@ func (s *Store) SaveOriginCheckpointBlockRoot(ctx context.Context, blockRoot [32
 	})
 }

-// SaveBackfillBlockRoot is used to keep track of the most recently backfilled block root when
-// the node was initialized via checkpoint sync.
-func (s *Store) SaveBackfillBlockRoot(ctx context.Context, blockRoot [32]byte) error {
-	_, span := trace.StartSpan(ctx, "BeaconDB.SaveBackfillBlockRoot")
-	defer span.End()
-	return s.db.Update(func(tx *bolt.Tx) error {
-		bucket := tx.Bucket(blocksBucket)
-		return bucket.Put(backfillBlockRootKey, blockRoot[:])
-	})
-}
-
 // HighestRootsBelowSlot returns roots from the database slot index from the highest slot below the input slot.
 // The slot value at the beginning of the return list is the slot where the roots were found. This is helpful so that
 // calling code can make decisions based on the slot without resolving the blocks to discover their slot (for instance
@@ -726,31 +736,6 @@ func blockRootsBySlot(ctx context.Context, tx *bolt.Tx, slot primitives.Slot) ([
 	return [][32]byte{}, nil
 }

-// createBlockIndicesFromBlock takes in a beacon block and returns
-// a map of bolt DB index buckets corresponding to each particular key for indices for
-// data, such as (shard indices bucket -> shard 5).
-func createBlockIndicesFromBlock(ctx context.Context, block interfaces.ReadOnlyBeaconBlock) map[string][]byte {
-	_, span := trace.StartSpan(ctx, "BeaconDB.createBlockIndicesFromBlock")
-	defer span.End()
-	indicesByBucket := make(map[string][]byte)
-	// Every index has a unique bucket for fast, binary-search
-	// range scans for filtering across keys.
-	buckets := [][]byte{
-		blockSlotIndicesBucket,
-	}
-	indices := [][]byte{
-		bytesutil.SlotToBytesBigEndian(block.Slot()),
-	}
-	buckets = append(buckets, blockParentRootIndicesBucket)
-	parentRoot := block.ParentRoot()
-	indices = append(indices, parentRoot[:])
-
-	for i := 0; i < len(buckets); i++ {
-		indicesByBucket[string(buckets[i])] = indices[i]
-	}
-	return indicesByBucket
-}
-
 // createBlockFiltersFromIndices takes in filter criteria and returns
 // a map with a single key-value pair: "block-parent-root-indices” -> parentRoot (array of bytes).
 //
@@ -838,74 +823,44 @@ func unmarshalBlock(_ context.Context, enc []byte) (interfaces.ReadOnlySignedBea
 	return blocks.NewSignedBeaconBlock(rawBlock)
 }

-func (s *Store) marshalBlock(
-	ctx context.Context,
-	blk interfaces.ReadOnlySignedBeaconBlock,
-) ([]byte, error) {
-	shouldBlind, err := s.shouldSaveBlinded(ctx)
+func encodeBlock(blk interfaces.ReadOnlySignedBeaconBlock) ([]byte, error) {
+	key, err := keyForBlock(blk)
 	if err != nil {
-		return nil, err
+		return nil, errors.Wrap(err, "could not determine version encoding key for block")
 	}
-	if shouldBlind {
-		return marshalBlockBlinded(ctx, blk)
+	enc, err := blk.MarshalSSZ()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not marshal block")
 	}
-	return marshalBlockFull(ctx, blk)
+	dbfmt := make([]byte, len(key)+len(enc))
+	if len(key) > 0 {
+		copy(dbfmt, key)
+	}
+	copy(dbfmt[len(key):], enc)
+	return snappy.Encode(nil, dbfmt), nil
 }

-// Encodes a full beacon block to the DB with its associated key.
-func marshalBlockFull(
-	_ context.Context,
-	blk interfaces.ReadOnlySignedBeaconBlock,
-) ([]byte, error) {
-	var encodedBlock []byte
-	var err error
-	encodedBlock, err = blk.MarshalSSZ()
-	if err != nil {
-		return nil, err
-	}
+func keyForBlock(blk interfaces.ReadOnlySignedBeaconBlock) ([]byte, error) {
 	switch blk.Version() {
 	case version.Deneb:
-		return snappy.Encode(nil, append(denebKey, encodedBlock...)), nil
-	case version.Capella:
-		return snappy.Encode(nil, append(capellaKey, encodedBlock...)), nil
-	case version.Bellatrix:
-		return snappy.Encode(nil, append(bellatrixKey, encodedBlock...)), nil
-	case version.Altair:
-		return snappy.Encode(nil, append(altairKey, encodedBlock...)), nil
-	case version.Phase0:
-		return snappy.Encode(nil, encodedBlock), nil
-	default:
-		return nil, errors.New("unknown block version")
-	}
-}
-
-// Encodes a blinded beacon block with its associated key.
-// If the block does not support blinding, we then encode it as a full
-// block with its associated key by calling marshalBlockFull.
-func marshalBlockBlinded(
-	ctx context.Context,
-	blk interfaces.ReadOnlySignedBeaconBlock,
-) ([]byte, error) {
-	blindedBlock, err := blk.ToBlinded()
-	if err != nil {
-		switch {
-		case errors.Is(err, blocks.ErrUnsupportedVersion):
-			return marshalBlockFull(ctx, blk)
-		default:
-			return nil, errors.Wrap(err, "could not convert block to blinded format")
+		if blk.IsBlinded() {
+			return denebBlindKey, nil
 		}
-	}
-	encodedBlock, err := blindedBlock.MarshalSSZ()
-	if err != nil {
-		return nil, errors.Wrap(err, "could not marshal blinded block")
-	}
-	switch blk.Version() {
-	case version.Deneb:
-		return snappy.Encode(nil, append(denebBlindKey, encodedBlock...)), nil
+		return denebKey, nil
 	case version.Capella:
-		return snappy.Encode(nil, append(capellaBlindKey, encodedBlock...)), nil
+		if blk.IsBlinded() {
+			return capellaBlindKey, nil
+		}
+		return capellaKey, nil
 	case version.Bellatrix:
-		return snappy.Encode(nil, append(bellatrixBlindKey, encodedBlock...)), nil
+		if blk.IsBlinded() {
+			return bellatrixBlindKey, nil
+		}
+		return bellatrixKey, nil
+	case version.Altair:
+		return altairKey, nil
+	case version.Phase0:
+		return nil, nil
 	default:
 		return nil, fmt.Errorf("unsupported block version: %v", blk.Version())
 	}
--- a/beacon-chain/db/kv/blocks_test.go
+++ b/beacon-chain/db/kv/blocks_test.go
@@ -126,23 +126,6 @@ var blockTests = []struct {
 	},
 }

-func TestStore_SaveBackfillBlockRoot(t *testing.T) {
-	db := setupDB(t)
-	ctx := context.Background()
-
-	_, err := db.BackfillBlockRoot(ctx)
-	require.ErrorIs(t, err, ErrNotFoundBackfillBlockRoot)
-
-	var expected [32]byte
-	copy(expected[:], []byte{0x23})
-	err = db.SaveBackfillBlockRoot(ctx, expected)
-	require.NoError(t, err)
-	actual, err := db.BackfillBlockRoot(ctx)
-	require.NoError(t, err)
-	require.Equal(t, expected, actual)
-
-}
-
 func TestStore_SaveBlock_NoDuplicates(t *testing.T) {
 	BlockCacheSize = 1
 	slot := primitives.Slot(20)
--- a/Show More
+++ b/Show More
@@ -1 +1 @@
 .4.0
 .0.0