fix e2e config

feat(config): update max blobs per block to 6 (#12512 )
feat(blockchain): update payload attribute for deneb (#12509 )
2026-01-09 21:38:05 -05:00 · 2023-06-11 20:52:31 -07:00 · 2023-06-10 12:11:41 -07:00 · 2023-06-09 10:58:28 -07:00 · 2023-06-09 10:15:51 -07:00 · 2023-06-07 07:44:29 -07:00
2440 changed files with 70305 additions and 38474 deletions
--- a/.bazelrc
+++ b/.bazelrc
@@ -1,9 +1,9 @@
-# Print warnings for tests with inappropriate test size or timeout.
-test --test_verbose_timeout_warnings
-
-# Only build test targets when running bazel test //...
-test --build_tests_only
-test --test_output=errors
+# Import bazelrc presets
+import %workspace%/build/bazelrc/convenience.bazelrc
+import %workspace%/build/bazelrc/correctness.bazelrc
+import %workspace%/build/bazelrc/cross.bazelrc
+import %workspace%/build/bazelrc/debug.bazelrc
+import %workspace%/build/bazelrc/performance.bazelrc

 # E2E run with debug gotag
 test:e2e --define gotags=debug
@@ -11,21 +11,9 @@ test:e2e --define gotags=debug
 # Clearly indicate that coverage is enabled to disable certain nogo checks.
 coverage --define=coverage_enabled=1

-# Fix for rules_docker. See: https://github.com/bazelbuild/rules_docker/issues/842
-build --host_force_python=PY2
-run --host_force_python=PY2
-
-# Networking is blocked for tests by default, add "requires-network" tag to your test if networking
-# is required within the sandbox. Network sandboxing only works on linux.
-build --sandbox_default_allow_network=false
-
 # Stamp binaries with git information
 build --workspace_status_command=./hack/workspace_status.sh

-# Prevent PATH changes from rebuilding when switching from IDE to command line.
-build --incompatible_strict_action_env
-run --incompatible_strict_action_env
-
 build --define blst_disabled=false
 run --define blst_disabled=false

@@ -68,42 +56,6 @@ build:cgo_symbolizer --define=USE_CGO_SYMBOLIZER=true
 build:cgo_symbolizer -c dbg
 build:cgo_symbolizer --define=gotags=cgosymbolizer_enabled

-# multi-arch cross-compiling toolchain configs:
-----------------------------------------------
-build:cross --crosstool_top=@prysm_toolchains//:multiarch_toolchain
-build:cross --host_platform=@io_bazel_rules_go//go/toolchain:linux_amd64
-build:cross --host_crosstool_top=@prysm_toolchains//:hostonly_toolchain
-
-# linux_amd64 config for cross compiler toolchain, not strictly necessary since host/exec env is amd64
-build:linux_amd64 --platforms=@io_bazel_rules_go//go/toolchain:linux_amd64_cgo
-
-# osx_amd64 config for cross compiler toolchain
-build:osx_amd64 --config=cross
-build:osx_amd64 --platforms=@io_bazel_rules_go//go/toolchain:darwin_amd64_cgo
-build:osx_amd64 --compiler=osxcross
-
-# osx_arm64 config for cross compiler toolchain
-build:osx_arm64 --config=cross
-build:osx_arm64 --platforms=@io_bazel_rules_go//go/toolchain:darwin_arm64_cgo
-build:osx_arm64 --compiler=osxcross
-build:osx_arm64 --cpu=aarch64
-
-# windows
-build:windows_amd64 --config=cross
-build:windows_amd64  --platforms=@io_bazel_rules_go//go/toolchain:windows_amd64_cgo
-build:windows_amd64 --compiler=mingw-w64
-
-# linux_arm64 conifg for cross compiler toolchain
-build:linux_arm64 --config=cross
-build:linux_arm64 --platforms=@io_bazel_rules_go//go/toolchain:linux_arm64_cgo
-build:linux_arm64 --copt=-funsafe-math-optimizations
-build:linux_arm64 --copt=-ftree-vectorize
-build:linux_arm64 --copt=-fomit-frame-pointer
-build:linux_arm64 --cpu=aarch64
-build:linux_arm64 --compiler=clang
-build:linux_arm64 --copt=-march=armv8-a
-
-
 # toolchain build debug configs
 #------------------------------
 build:debug --sandbox_debug
@@ -111,123 +63,5 @@ build:debug --toolchain_resolution_debug
 build:debug --verbose_failures
 build:debug -s

-# windows debug
-build:windows_amd64_debug --config=windows_amd64
-build:windows_amd64_debug --config=debug
-
-# osx_amd64 debug config
-build:osx_amd64_debug --config=debug
-build:osx_amd64_debug --config=osx_amd64
-
-# osx_arm64 debug config
-build:osx_arm64_debug --config=debug
-build:osx_arm64_debug --config=osx_arm64
-
-# linux_arm64_debug
-build:linux_arm64_debug --config=linux_arm64
-build:linux_arm64_debug --config=debug
-
-# linux_amd64_debug
-build:linux_amd64_debug --config=linux_amd64
-build:linux_amd64_debug --config=debug
-
-
-# Docker Sandbox Configs
-#-----------------------
-# Note all docker sandbox configs must run from a linux x86_64 host
-# build:docker-sandbox --experimental_docker_image=gcr.io/prysmaticlabs/rbe-worker:latest
-build:docker-sandbox --spawn_strategy=docker --strategy=Javac=docker --genrule_strategy=docker
-build:docker-sandbox --define=EXECUTOR=remote
-build:docker-sandbox --experimental_docker_verbose
-build:docker-sandbox --experimental_enable_docker_sandbox
-build:docker-sandbox --crosstool_top=@rbe_ubuntu_clang//cc:toolchain 
-build:docker-sandbox --host_javabase=@rbe_ubuntu_clang//java:jdk 
-build:docker-sandbox --javabase=@rbe_ubuntu_clang//java:jdk 
-build:docker-sandbox --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8 
-build:docker-sandbox --java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8 
-build:docker-sandbox --extra_execution_platforms=@rbe_ubuntu_clang//config:platform 
-build:docker-sandbox --host_platform=@rbe_ubuntu_clang//config:platform 
-build:docker-sandbox --platforms=@rbe_ubuntu_clang//config:platform
-build:docker-sandbox --extra_toolchains=@prysm_toolchains//:cc-toolchain-multiarch
-
-# windows_amd64 docker sandbox build config
-build:windows_amd64_docker --config=docker-sandbox --config=windows_amd64
-build:windows_amd64_docker_debug --config=windows_amd64_docker --config=debug
-
-# osx_amd64 docker sandbox build config
-build:osx_amd64_docker --config=docker-sandbox --config=osx_amd64
-build:osx_amd64_docker_debug --config=osx_amd64_docker --config=debug
-
-# osx_arm64 docker sandbox build config
-build:osx_arm64_docker --config=docker-sandbox --config=osx_arm64
-build:osx_arm64_docker_debug --config=osx_arm64_docker --config=debug
-
-# linux_arm64 docker sandbox build config
-build:linux_arm64_docker --config=docker-sandbox --config=linux_arm64
-build:linux_arm64_docker_debug --config=linux_arm64_docker --config=debug
-
-# linux_amd64 docker sandbox build config
-build:linux_amd64_docker --config=docker-sandbox --config=linux_amd64
-build:linux_amd64_docker_debug --config=linux_amd64_docker --config=debug
-
-
-# Remote Build Execution
-#-----------------------
-# Originally from https://github.com/bazelbuild/bazel-toolchains/blob/master/bazelrc/bazel-2.0.0.bazelrc
-#
-# Depending on how many machines are in the remote execution instance, setting
-# this higher can make builds faster by allowing more jobs to run in parallel.
-# Setting it too high can result in jobs that timeout, however, while waiting
-# for a remote machine to execute them.
-build:remote --jobs=50
-
-# Set several flags related to specifying the platform, toolchain and java
-# properties.
-# These flags should only be used as is for the rbe-ubuntu16-04 container
-# and need to be adapted to work with other toolchain containers.
-build:remote --host_javabase=@rbe_ubuntu_clang//java:jdk
-build:remote --javabase=@rbe_ubuntu_clang//java:jdk
-build:remote --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8
-build:remote --java_toolchain=@bazel_tools//tools/jdk:toolchain_hostjdk8
-build:remote --crosstool_top=@rbe_ubuntu_clang//cc:toolchain
-build:remote --action_env=BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
-# Platform flags:
-# The toolchain container used for execution is defined in the target indicated
-# by "extra_execution_platforms", "host_platform" and "platforms".
-# More about platforms: https://docs.bazel.build/versions/master/platforms.html
-build:remote --extra_toolchains=@rbe_ubuntu_clang//config:cc-toolchain
-build:remote --extra_execution_platforms=@rbe_ubuntu_clang//config:platform
-build:remote --host_platform=@rbe_ubuntu_clang//config:platform
-build:remote --platforms=@rbe_ubuntu_clang//config:platform
-
-# Starting with Bazel 0.27.0 strategies do not need to be explicitly
-# defined. See https://github.com/bazelbuild/bazel/issues/7480
-build:remote --define=EXECUTOR=remote
-
-# Enable remote execution so actions are performed on the remote systems.
-# build:remote --remote_executor=grpcs://remotebuildexecution.googleapis.com
-
-# Enforce stricter environment rules, which eliminates some non-hermetic
-# behavior and therefore improves both the remote cache hit rate and the
-# correctness and repeatability of the build.
-build:remote --incompatible_strict_action_env=true
-
-# Set a higher timeout value, just in case.
-build:remote --remote_timeout=3600
-
-# Enable authentication. This will pick up application default credentials by
-# default. You can use --google_credentials=some_file.json to use a service
-# account credential instead.
-# build:remote --google_default_credentials=true
-
-# Enable build without the bytes
-# See: https://github.com/bazelbuild/bazel/issues/6862
-build:remote --experimental_remote_download_outputs=toplevel --experimental_inmemory_jdeps_files --experimental_inmemory_dotd_files
-
-build:remote --remote_local_fallback
-
-# Ignore GoStdLib with remote caching
-build --modify_execution_info='GoStdlib.*=+no-remote-cache'
-
 # Set bazel gotag
 build --define gotags=bazel
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-5.3.0
+6.1.0
--- a/.buildkite-bazelrc
+++ b/.buildkite-bazelrc
@@ -43,4 +43,12 @@ build --flaky_test_attempts=5

 # Better caching
 build:nostamp --nostamp
-build:nostamp --workspace_status_command=./hack/workspace_status_ci.sh
+
+# Build metadata
+build --build_metadata=ROLE=CI
+build --build_metadata=REPO_URL=https://github.com/prysmaticlabs/prysm.git
+build --workspace_status_command=./hack/workspace_status_ci.sh
+
+# Buildbuddy
+build --bes_results_url=https://app.buildbuddy.io/invocation/
+build --bes_backend=grpcs://remote.buildbuddy.io
--- a/.deepsource.toml
+++ b/.deepsource.toml
@@ -11,7 +11,7 @@ name = "go"
 enabled = true

 [analyzers.meta]
-import_paths = ["github.com/prysmaticlabs/prysm/v3"]
+import_paths = ["github.com/prysmaticlabs/prysm/v4"]

 [[analyzers]]
 name = "test-coverage"
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -26,14 +26,14 @@ jobs:
    steps:
      - name: Checkout
        uses: actions/checkout@v2
-      - name: Set up Go 1.19
+      - name: Set up Go 1.20
        uses: actions/setup-go@v3
        with:
-          go-version: 1.19
+          go-version: '1.20'
      - name: Run Gosec Security Scanner
        run: | # https://github.com/securego/gosec/issues/469
          export PATH=$PATH:$(go env GOPATH)/bin
-          go install github.com/securego/gosec/v2/cmd/gosec@v2.12.0
+          go install github.com/securego/gosec/v2/cmd/gosec@v2.15.0
          gosec -exclude=G307 -exclude-dir=crypto/bls/herumi ./...

  lint:
@@ -43,16 +43,16 @@ jobs:
      - name: Checkout
        uses: actions/checkout@v2

-      - name: Set up Go 1.19
+      - name: Set up Go 1.20
        uses: actions/setup-go@v3
        with:
-          go-version: 1.19
+          go-version: '1.20'
          id: go

      - name: Golangci-lint
        uses: golangci/golangci-lint-action@v3
        with:
-          version: v1.50.1
+          version: v1.52.2
          args: --config=.golangci.yml --out-${NO_FUTURE}format colored-line-number

  build:
@@ -62,7 +62,7 @@ jobs:
      - name: Set up Go 1.x
        uses: actions/setup-go@v2
        with:
-          go-version: 1.19
+          go-version: '1.20'
        id: go

      - name: Check out code into the Go module directory
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -17,6 +17,10 @@ linters:
    - errcheck
    - gosimple
    - gocognit
+    - dupword
+    - nilerr
+    - whitespace
+    - misspell

 linters-settings:
  gocognit:
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -12,7 +12,7 @@ exports_files([
    "LICENSE.md",
 ])

-# gazelle:prefix github.com/prysmaticlabs/prysm/v3
+# gazelle:prefix github.com/prysmaticlabs/prysm/v4
 # gazelle:map_kind go_library go_library @prysm//tools/go:def.bzl
 # gazelle:map_kind go_test go_test @prysm//tools/go:def.bzl
 # gazelle:map_kind go_repository go_repository @prysm//tools/go:def.bzl
--- a/README.md
+++ b/README.md
@@ -2,16 +2,16 @@

 [![Build status](https://badge.buildkite.com/b555891daf3614bae4284dcf365b2340cefc0089839526f096.svg?branch=master)](https://buildkite.com/prysmatic-labs/prysm)
 [![Go Report Card](https://goreportcard.com/badge/github.com/prysmaticlabs/prysm)](https://goreportcard.com/report/github.com/prysmaticlabs/prysm)
-[![Consensus_Spec_Version 1.2.0](https://img.shields.io/badge/Consensus%20Spec%20Version-v1.2.0-blue.svg)](https://github.com/ethereum/consensus-specs/tree/v1.2.0)
-[![Execution_API_Version 1.0.0-beta.1](https://img.shields.io/badge/Execution%20API%20Version-v1.0.0.beta.1-blue.svg)](https://github.com/ethereum/execution-apis/tree/v1.0.0-beta.1/src/engine)
-[![Discord](https://user-images.githubusercontent.com/7288322/34471967-1df7808a-efbb-11e7-9088-ed0b04151291.png)](https://discord.gg/CTYGPUJ)
+[![Consensus_Spec_Version 1.3.0](https://img.shields.io/badge/Consensus%20Spec%20Version-v1.3.0-blue.svg)](https://github.com/ethereum/consensus-specs/tree/v1.3.0)
+[![Execution_API_Version 1.0.0-beta.2](https://img.shields.io/badge/Execution%20API%20Version-v1.0.0.beta.2-blue.svg)](https://github.com/ethereum/execution-apis/tree/v1.0.0-beta.2/src/engine)
+[![Discord](https://user-images.githubusercontent.com/7288322/34471967-1df7808a-efbb-11e7-9088-ed0b04151291.png)](https://discord.gg/prysmaticlabs)
 [![GitPOAP Badge](https://public-api.gitpoap.io/v1/repo/prysmaticlabs/prysm/badge)](https://www.gitpoap.io/gh/prysmaticlabs/prysm)

 This is the core repository for Prysm, a [Golang](https://golang.org/) implementation of the [Ethereum Consensus](https://ethereum.org/en/eth2/) specification, developed by [Prysmatic Labs](https://prysmaticlabs.com). See the [Changelog](https://github.com/prysmaticlabs/prysm/releases) for details of the latest releases and upcoming breaking changes.

 ### Getting Started

-A detailed set of installation and usage instructions as well as breakdowns of each individual component are available in the [official documentation portal](https://docs.prylabs.network). If you still have questions, feel free to stop by our [Discord](https://discord.gg/CTYGPUJ).
+A detailed set of installation and usage instructions as well as breakdowns of each individual component are available in the [official documentation portal](https://docs.prylabs.network). If you still have questions, feel free to stop by our [Discord](https://discord.gg/prysmaticlabs).

 ### Staking on Mainnet

--- a/93
+++ b/93
@@ -4,15 +4,18 @@ load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")

 http_archive(
-    name = "bazel_toolchains",
-    sha256 = "8e0633dfb59f704594f19ae996a35650747adc621ada5e8b9fb588f808c89cb0",
-    strip_prefix = "bazel-toolchains-3.7.0",
+    name = "rules_pkg",
+    sha256 = "8c20f74bca25d2d442b327ae26768c02cf3c99e93fad0381f32be9aab1967675",
    urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/releases/download/3.7.0/bazel-toolchains-3.7.0.tar.gz",
-        "https://github.com/bazelbuild/bazel-toolchains/releases/download/3.7.0/bazel-toolchains-3.7.0.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_pkg/releases/download/0.8.1/rules_pkg-0.8.1.tar.gz",
+        "https://github.com/bazelbuild/rules_pkg/releases/download/0.8.1/rules_pkg-0.8.1.tar.gz",
    ],
 )

+load("@rules_pkg//:deps.bzl", "rules_pkg_dependencies")
+
+rules_pkg_dependencies()
+
 http_archive(
    name = "com_grail_bazel_toolchain",
    sha256 = "b210fc8e58782ef171f428bfc850ed7179bdd805543ebd1aa144b9c93489134f",
@@ -39,10 +42,6 @@ load("@prysm//tools/cross-toolchain:prysm_toolchains.bzl", "configure_prysm_tool

 configure_prysm_toolchains()

-load("@prysm//tools/cross-toolchain:rbe_toolchains_config.bzl", "rbe_toolchains_config")
-
-rbe_toolchains_config()
-
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

 http_archive(
@@ -76,9 +75,8 @@ http_archive(

 http_archive(
    name = "io_bazel_rules_docker",
-    sha256 = "1f4e59843b61981a96835dc4ac377ad4da9f8c334ebe5e0bb3f58f80c09735f4",
-    strip_prefix = "rules_docker-0.19.0",
-    urls = ["https://github.com/bazelbuild/rules_docker/releases/download/v0.19.0/rules_docker-v0.19.0.tar.gz"],
+    sha256 = "b1e80761a8a8243d03ebca8845e9cc1ba6c82ce7c5179ce2b295cd36f7e394bf",
+    urls = ["https://github.com/bazelbuild/rules_docker/releases/download/v0.25.0/rules_docker-v0.25.0.tar.gz"],
 )

 http_archive(
@@ -88,10 +86,10 @@ http_archive(
        # Expose internals of go_test for custom build transitions.
        "//third_party:io_bazel_rules_go_test.patch",
    ],
-    sha256 = "ae013bf35bd23234d1dea46b079f1e05ba74ac0321423830119d3e787ec73483",
+    sha256 = "6b65cb7917b4d1709f9410ffe00ecf3e160edf674b78c54a894471320862184f",
    urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/v0.36.0/rules_go-v0.36.0.zip",
-        "https://github.com/bazelbuild/rules_go/releases/download/v0.36.0/rules_go-v0.36.0.zip",
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/v0.39.0/rules_go-v0.39.0.zip",
+        "https://github.com/bazelbuild/rules_go/releases/download/v0.39.0/rules_go-v0.39.0.zip",
    ],
 )

@@ -122,32 +120,36 @@ load(
    "container_pull",
 )

+# Pulled gcr.io/distroless/cc-debian11:latest on 2022-02-23
 container_pull(
-    name = "cc_image_base",
-    digest = "sha256:2c4bb6b7236db0a55ec54ba8845e4031f5db2be957ac61867872bf42e56c4deb",
+    name = "cc_image_base_amd64",
+    digest = "sha256:2a0daf90a7deb78465bfca3ef2eee6e91ce0a5706059f05d79d799a51d339523",
    registry = "gcr.io",
-    repository = "distroless/cc",
+    repository = "distroless/cc-debian11",
 )

+# Pulled gcr.io/distroless/cc-debian11:debug on 2022-02-23
 container_pull(
-    name = "cc_debug_image_base",
-    digest = "sha256:3680c61e81f68fc00bfb5e1ec65e8e678aaafa7c5f056bc2681c29527ebbb30c",
+    name = "cc_debug_image_base_amd64",
+    digest = "sha256:7bd596f5f200588f13a69c268eea6ce428b222b67cd7428d6a7fef95e75c052a",
    registry = "gcr.io",
-    repository = "distroless/cc",
+    repository = "distroless/cc-debian11",
 )

+# Pulled from gcr.io/distroless/base-debian11:latest on 2022-02-23
 container_pull(
-    name = "go_image_base",
-    digest = "sha256:ba7a315f86771332e76fa9c3d423ecfdbb8265879c6f1c264d6fff7d4fa460a4",
+    name = "go_image_base_amd64",
+    digest = "sha256:34e682800774ecbd0954b1663d90238505f1ba5543692dbc75feef7dd4839e90",
    registry = "gcr.io",
-    repository = "distroless/base",
+    repository = "distroless/base-debian11",
 )

+# Pulled from gcr.io/distroless/base-debian11:debug on 2022-02-23
 container_pull(
-    name = "go_debug_image_base",
-    digest = "sha256:efd8711717d9e9b5d0dbb20ea10876dab0609c923bc05321b912f9239090ca80",
+    name = "go_debug_image_base_amd64",
+    digest = "sha256:0f503c6bfd207793bc416f20a35bf6b75d769a903c48f180ad73f60f7b60d7bd",
    registry = "gcr.io",
-    repository = "distroless/base",
+    repository = "distroless/base-debian11",
 )

 container_pull(
@@ -162,7 +164,7 @@ load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_depe
 go_rules_dependencies()

 go_register_toolchains(
-    go_version = "1.19.4",
+    go_version = "1.20.3",
    nogo = "@//:nogo",
 )

@@ -188,7 +190,22 @@ filegroup(
    url = "https://github.com/eth-clients/slashing-protection-interchange-tests/archive/b8413ca42dc92308019d0d4db52c87e9e125c4e9.tar.gz",
 )

-consensus_spec_version = "v1.3.0-rc.1"
+http_archive(
+    name = "eip4881_spec_tests",
+    build_file_content = """
+filegroup(
+    name = "test_data",
+    srcs = glob([
+        "**/*.yaml",
+    ]),
+    visibility = ["//visibility:public"],
+)
+    """,
+    sha256 = "89cb659498c0d196fc9f957f8b849b2e1a5c041c3b2b3ae5432ac5c26944297e",
+    url = "https://github.com/ethereum/EIPs/archive/5480440fe51742ed23342b68cf106cefd427e39d.tar.gz",
+)
+
+consensus_spec_version = "v1.4.0-alpha.2"

 bls_test_version = "v0.1.1"

@@ -204,7 +221,7 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    sha256 = "3d6fadb64674eb64a84fae6c2efa9949231ea91e7cb74ada9214097323e86569",
+    sha256 = "bfba887cbe043907adf884cf6d18f2e8a31e34e9245397b84af1f54ed22b706a",
    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/general.tar.gz" % consensus_spec_version,
 )

@@ -220,7 +237,7 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    sha256 = "54ffbcab1e77316a280e6f5a64c6ed62351e8f5678e6fa49340e49b9b5575e8e",
+    sha256 = "9ff77bef0ca1e39bcee2769075c89f0f91fb8f89ad38a1b3e0c31cf6732650ad",
    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/minimal.tar.gz" % consensus_spec_version,
 )

@@ -236,7 +253,7 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    sha256 = "bb06d30ca533dc97d45f2367916ba9ff1b5af52f08a9d8c33bb7b1a61254094e",
+    sha256 = "fbcc3c9898110c675e5de9c27cb667ad7cadf930db7ebb5c6bba15d7be95bf8a",
    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/mainnet.tar.gz" % consensus_spec_version,
 )

@@ -251,7 +268,7 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    sha256 = "9d22246c00ec3907ef8dc3ddccdfe6f7153ce46df73deee0a0176fe7e4aa1126",
+    sha256 = "9fff1bcdd0e5857797197800db091c3675b2c11b54f704fe4de1ba683bed7ba5",
    strip_prefix = "consensus-specs-" + consensus_spec_version[1:],
    url = "https://github.com/ethereum/consensus-specs/archive/refs/tags/%s.tar.gz" % consensus_spec_version,
 )
@@ -282,9 +299,9 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    sha256 = "82b01a48b143fe0f2fb7fb5f5dd385c1f934335a12d7954f08b1d45d77427b5e",
-    strip_prefix = "eth2-networks-674f7a1d01d9c18345456eab76e3871b3df2126b",
-    url = "https://github.com/eth-clients/eth2-networks/archive/674f7a1d01d9c18345456eab76e3871b3df2126b.tar.gz",
+    sha256 = "2701e1e1a3ec10c673fe7dbdbbe6f02c8ae8c922aebbf6e720d8c72d5458aafe",
+    strip_prefix = "eth2-networks-7b4897888cebef23801540236f73123e21774954",
+    url = "https://github.com/eth-clients/eth2-networks/archive/7b4897888cebef23801540236f73123e21774954.tar.gz",
 )

 http_archive(
@@ -315,9 +332,9 @@ filegroup(
    visibility = ["//visibility:public"],
 )
 """,
-    sha256 = "b2226874526805d64c29e5053fa28e511b57c0860585d6d59777ee81ff4859ca",
+    sha256 = "5006614c33e358699b4e072c649cd4c3866f7d41a691449d5156f6c6e07a4c60",
    urls = [
-        "https://github.com/prysmaticlabs/prysm-web-ui/releases/download/v2.0.2/prysm-web-ui.tar.gz",
+        "https://github.com/prysmaticlabs/prysm-web-ui/releases/download/v2.0.3/prysm-web-ui.tar.gz",
    ],
 )

--- a/api/client/BUILD.bazel
+++ b/api/client/BUILD.bazel
@@ -0,0 +1,20 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "client.go",
+        "errors.go",
+        "options.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/client",
+    visibility = ["//visibility:public"],
+    deps = ["@com_github_pkg_errors//:go_default_library"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["client_test.go"],
+    embed = [":go_default_library"],
+    deps = ["//testing/require:go_default_library"],
+)
--- a/api/client/beacon/BUILD.bazel
+++ b/api/client/beacon/BUILD.bazel
@@ -6,11 +6,11 @@ go_library(
        "checkpoint.go",
        "client.go",
        "doc.go",
-        "errors.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/v3/api/client/beacon",
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/client/beacon",
    visibility = ["//visibility:public"],
    deps = [
+        "//api/client:go_default_library",
        "//beacon-chain/core/helpers:go_default_library",
        "//beacon-chain/rpc/apimiddleware:go_default_library",
        "//beacon-chain/state:go_default_library",
@@ -20,6 +20,7 @@ go_library(
        "//encoding/ssz/detect:go_default_library",
        "//io/file:go_default_library",
        "//network/forks:go_default_library",
+        "//proto/eth/v1:go_default_library",
        "//proto/prysm/v1alpha1:go_default_library",
        "//runtime/version:go_default_library",
        "//time/slots:go_default_library",
@@ -38,6 +39,7 @@ go_test(
    ],
    embed = [":go_default_library"],
    deps = [
+        "//api/client:go_default_library",
        "//beacon-chain/state:go_default_library",
        "//config/params:go_default_library",
        "//consensus-types/blocks:go_default_library",
--- a/api/client/beacon/checkpoint.go
+++ b/api/client/beacon/checkpoint.go
@@ -6,25 +6,26 @@ import (
 	"path"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/ssz/detect"
-	"github.com/prysmaticlabs/prysm/v3/io/file"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	base "github.com/prysmaticlabs/prysm/v4/api/client"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/ssz/detect"
+	"github.com/prysmaticlabs/prysm/v4/io/file"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/mod/semver"
 )

-// OriginData represents the BeaconState and SignedBeaconBlock necessary to start an empty Beacon Node
+// OriginData represents the BeaconState and ReadOnlySignedBeaconBlock necessary to start an empty Beacon Node
 // using Checkpoint Sync.
 type OriginData struct {
 	sb []byte
 	bb []byte
 	st state.BeaconState
-	b  interfaces.SignedBeaconBlock
+	b  interfaces.ReadOnlySignedBeaconBlock
 	vu *detect.VersionedUnmarshaler
 	br [32]byte
 	sr [32]byte
@@ -49,7 +50,7 @@ func (o *OriginData) StateBytes() []byte {
 	return o.sb
 }

-// BlockBytes returns the ssz-encoded bytes of the downloaded SignedBeaconBlock value.
+// BlockBytes returns the ssz-encoded bytes of the downloaded ReadOnlySignedBeaconBlock value.
 func (o *OriginData) BlockBytes() []byte {
 	return o.bb
 }
@@ -103,8 +104,8 @@ func DownloadFinalizedData(ctx context.Context, client *Client) (*OriginData, er
 	}

 	log.Printf("BeaconState slot=%d, Block slot=%d", s.Slot(), b.Block().Slot())
-	log.Printf("BeaconState htr=%#xd, Block state_root=%#x", sr, b.Block().StateRoot())
-	log.Printf("BeaconState latest_block_header htr=%#xd, block htr=%#x", br, realBlockRoot)
+	log.Printf("BeaconState htr=%#x, Block state_root=%#x", sr, b.Block().StateRoot())
+	log.Printf("BeaconState latest_block_header htr=%#x, block htr=%#x", br, realBlockRoot)
 	return &OriginData{
 		st: s,
 		b:  b,
@@ -116,7 +117,7 @@ func DownloadFinalizedData(ctx context.Context, client *Client) (*OriginData, er
 	}, nil
 }

-// WeakSubjectivityData represents the state root, block root and epoch of the BeaconState + SignedBeaconBlock
+// WeakSubjectivityData represents the state root, block root and epoch of the BeaconState + ReadOnlySignedBeaconBlock
 // that falls at the beginning of the current weak subjectivity period. These values can be used to construct
 // a weak subjectivity checkpoint beacon node flag to be used for validation.
 type WeakSubjectivityData struct {
@@ -126,7 +127,7 @@ type WeakSubjectivityData struct {
 }

 // CheckpointString returns the standard string representation of a Checkpoint.
-// The format is a a hex-encoded block root, followed by the epoch of the block, separated by a colon. For example:
+// The format is a hex-encoded block root, followed by the epoch of the block, separated by a colon. For example:
 // "0x1c35540cac127315fabb6bf29181f2ae0de1a3fc909d2e76ba771e61312cc49a:74888"
 func (wsd *WeakSubjectivityData) CheckpointString() string {
 	return fmt.Sprintf("%#x:%d", wsd.BlockRoot, wsd.Epoch)
@@ -140,7 +141,7 @@ func ComputeWeakSubjectivityCheckpoint(ctx context.Context, client *Client) (*We
 	ws, err := client.GetWeakSubjectivity(ctx)
 	if err != nil {
 		// a 404/405 is expected if querying an endpoint that doesn't support the weak subjectivity checkpoint api
-		if !errors.Is(err, ErrNotOK) {
+		if !errors.Is(err, base.ErrNotOK) {
 			return nil, errors.Wrap(err, "unexpected API response for prysm-only weak subjectivity checkpoint API")
 		}
 		// fall back to vanilla Beacon Node API method
--- a/api/client/beacon/checkpoint_test.go
+++ b/api/client/beacon/checkpoint_test.go
@@ -7,24 +7,24 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"net/url"
 	"testing"

-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	blocktest "github.com/prysmaticlabs/prysm/v3/consensus-types/blocks/testing"
-	"github.com/prysmaticlabs/prysm/v3/network/forks"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/api/client"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	blocktest "github.com/prysmaticlabs/prysm/v4/consensus-types/blocks/testing"
+	"github.com/prysmaticlabs/prysm/v4/network/forks"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"

-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/ssz/detect"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/ssz/detect"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 type testRT struct {
@@ -66,11 +66,7 @@ func TestMarshalToEnvelope(t *testing.T) {
 }

 func TestFallbackVersionCheck(t *testing.T) {
-	c := &Client{
-		hc:      &http.Client{},
-		baseURL: &url.URL{Host: "localhost:3500", Scheme: "http"},
-	}
-	c.hc.Transport = &testRT{rt: func(req *http.Request) (*http.Response, error) {
+	trans := &testRT{rt: func(req *http.Request) (*http.Response, error) {
 		res := &http.Response{Request: req}
 		switch req.URL.Path {
 		case getNodeVersionPath:
@@ -88,12 +84,13 @@ func TestFallbackVersionCheck(t *testing.T) {
 		case getWeakSubjectivityPath:
 			res.StatusCode = http.StatusNotFound
 		}
-
 		return res, nil
 	}}

+	c, err := NewClient("http://localhost:3500", client.WithRoundTripper(trans))
+	require.NoError(t, err)
 	ctx := context.Background()
-	_, err := ComputeWeakSubjectivityCheckpoint(ctx, c)
+	_, err = ComputeWeakSubjectivityCheckpoint(ctx, c)
 	require.ErrorIs(t, err, errUnsupportedPrysmCheckpointVersion)
 }

@@ -170,44 +167,41 @@ func TestDownloadWeakSubjectivityCheckpoint(t *testing.T) {
 		Epoch:     epoch,
 	}

-	hc := &http.Client{
-		Transport: &testRT{rt: func(req *http.Request) (*http.Response, error) {
-			res := &http.Response{Request: req}
-			switch req.URL.Path {
-			case getWeakSubjectivityPath:
-				res.StatusCode = http.StatusOK
-				cp := struct {
-					Epoch string `json:"epoch"`
-					Root  string `json:"root"`
-				}{
-					Epoch: fmt.Sprintf("%d", slots.ToEpoch(b.Block().Slot())),
-					Root:  fmt.Sprintf("%#x", bRoot),
-				}
-				wsr := struct {
-					Checkpoint interface{} `json:"ws_checkpoint"`
-					StateRoot  string      `json:"state_root"`
-				}{
-					Checkpoint: cp,
-					StateRoot:  fmt.Sprintf("%#x", wRoot),
-				}
-				rb, err := marshalToEnvelope(wsr)
-				require.NoError(t, err)
-				res.Body = io.NopCloser(bytes.NewBuffer(rb))
-			case renderGetStatePath(IdFromSlot(wSlot)):
-				res.StatusCode = http.StatusOK
-				res.Body = io.NopCloser(bytes.NewBuffer(wsSerialized))
-			case renderGetBlockPath(IdFromRoot(bRoot)):
-				res.StatusCode = http.StatusOK
-				res.Body = io.NopCloser(bytes.NewBuffer(serBlock))
+	trans := &testRT{rt: func(req *http.Request) (*http.Response, error) {
+		res := &http.Response{Request: req}
+		switch req.URL.Path {
+		case getWeakSubjectivityPath:
+			res.StatusCode = http.StatusOK
+			cp := struct {
+				Epoch string `json:"epoch"`
+				Root  string `json:"root"`
+			}{
+				Epoch: fmt.Sprintf("%d", slots.ToEpoch(b.Block().Slot())),
+				Root:  fmt.Sprintf("%#x", bRoot),
 			}
+			wsr := struct {
+				Checkpoint interface{} `json:"ws_checkpoint"`
+				StateRoot  string      `json:"state_root"`
+			}{
+				Checkpoint: cp,
+				StateRoot:  fmt.Sprintf("%#x", wRoot),
+			}
+			rb, err := marshalToEnvelope(wsr)
+			require.NoError(t, err)
+			res.Body = io.NopCloser(bytes.NewBuffer(rb))
+		case renderGetStatePath(IdFromSlot(wSlot)):
+			res.StatusCode = http.StatusOK
+			res.Body = io.NopCloser(bytes.NewBuffer(wsSerialized))
+		case renderGetBlockPath(IdFromRoot(bRoot)):
+			res.StatusCode = http.StatusOK
+			res.Body = io.NopCloser(bytes.NewBuffer(serBlock))
+		}

-			return res, nil
-		}},
-	}
-	c := &Client{
-		hc:      hc,
-		baseURL: &url.URL{Host: "localhost:3500", Scheme: "http"},
-	}
+		return res, nil
+	}}
+
+	c, err := NewClient("http://localhost:3500", client.WithRoundTripper(trans))
+	require.NoError(t, err)

 	wsd, err := ComputeWeakSubjectivityCheckpoint(ctx, c)
 	require.NoError(t, err)
@@ -266,42 +260,39 @@ func TestDownloadBackwardsCompatibleCombined(t *testing.T) {
 	wsSerialized, err := wst.MarshalSSZ()
 	require.NoError(t, err)

-	hc := &http.Client{
-		Transport: &testRT{rt: func(req *http.Request) (*http.Response, error) {
-			res := &http.Response{Request: req}
-			switch req.URL.Path {
-			case getNodeVersionPath:
-				res.StatusCode = http.StatusOK
-				b := bytes.NewBuffer(nil)
-				d := struct {
-					Version string `json:"version"`
-				}{
-					Version: "Lighthouse/v0.1.5 (Linux x86_64)",
-				}
-				encoded, err := marshalToEnvelope(d)
-				require.NoError(t, err)
-				b.Write(encoded)
-				res.Body = io.NopCloser(b)
-			case getWeakSubjectivityPath:
-				res.StatusCode = http.StatusNotFound
-			case renderGetStatePath(IdHead):
-				res.StatusCode = http.StatusOK
-				res.Body = io.NopCloser(bytes.NewBuffer(serialized))
-			case renderGetStatePath(IdFromSlot(wSlot)):
-				res.StatusCode = http.StatusOK
-				res.Body = io.NopCloser(bytes.NewBuffer(wsSerialized))
-			case renderGetBlockPath(IdFromRoot(bRoot)):
-				res.StatusCode = http.StatusOK
-				res.Body = io.NopCloser(bytes.NewBuffer(serBlock))
+	trans := &testRT{rt: func(req *http.Request) (*http.Response, error) {
+		res := &http.Response{Request: req}
+		switch req.URL.Path {
+		case getNodeVersionPath:
+			res.StatusCode = http.StatusOK
+			b := bytes.NewBuffer(nil)
+			d := struct {
+				Version string `json:"version"`
+			}{
+				Version: "Lighthouse/v0.1.5 (Linux x86_64)",
 			}
+			encoded, err := marshalToEnvelope(d)
+			require.NoError(t, err)
+			b.Write(encoded)
+			res.Body = io.NopCloser(b)
+		case getWeakSubjectivityPath:
+			res.StatusCode = http.StatusNotFound
+		case renderGetStatePath(IdHead):
+			res.StatusCode = http.StatusOK
+			res.Body = io.NopCloser(bytes.NewBuffer(serialized))
+		case renderGetStatePath(IdFromSlot(wSlot)):
+			res.StatusCode = http.StatusOK
+			res.Body = io.NopCloser(bytes.NewBuffer(wsSerialized))
+		case renderGetBlockPath(IdFromRoot(bRoot)):
+			res.StatusCode = http.StatusOK
+			res.Body = io.NopCloser(bytes.NewBuffer(serBlock))
+		}

-			return res, nil
-		}},
-	}
-	c := &Client{
-		hc:      hc,
-		baseURL: &url.URL{Host: "localhost:3500", Scheme: "http"},
-	}
+		return res, nil
+	}}
+
+	c, err := NewClient("http://localhost:3500", client.WithRoundTripper(trans))
+	require.NoError(t, err)

 	wsPub, err := ComputeWeakSubjectivityCheckpoint(ctx, c)
 	require.NoError(t, err)
@@ -315,21 +306,16 @@ func TestGetWeakSubjectivityEpochFromHead(t *testing.T) {
 	st, expectedEpoch := defaultTestHeadState(t, params.MainnetConfig())
 	serialized, err := st.MarshalSSZ()
 	require.NoError(t, err)
-	hc := &http.Client{
-		Transport: &testRT{rt: func(req *http.Request) (*http.Response, error) {
-			res := &http.Response{Request: req}
-			switch req.URL.Path {
-			case renderGetStatePath(IdHead):
-				res.StatusCode = http.StatusOK
-				res.Body = io.NopCloser(bytes.NewBuffer(serialized))
-			}
-			return res, nil
-		}},
-	}
-	c := &Client{
-		hc:      hc,
-		baseURL: &url.URL{Host: "localhost:3500", Scheme: "http"},
-	}
+	trans := &testRT{rt: func(req *http.Request) (*http.Response, error) {
+		res := &http.Response{Request: req}
+		if req.URL.Path == renderGetStatePath(IdHead) {
+			res.StatusCode = http.StatusOK
+			res.Body = io.NopCloser(bytes.NewBuffer(serialized))
+		}
+		return res, nil
+	}}
+	c, err := NewClient("http://localhost:3500", client.WithRoundTripper(trans))
+	require.NoError(t, err)
 	actualEpoch, err := getWeakSubjectivityEpochFromHead(context.Background(), c)
 	require.NoError(t, err)
 	require.Equal(t, expectedEpoch, actualEpoch)
@@ -398,11 +384,7 @@ func populateValidators(cfg *params.BeaconChainConfig, st state.BeaconState, val
 	if err := st.SetValidators(validators); err != nil {
 		return err
 	}
-	if err := st.SetBalances(balances); err != nil {
-		return err
-	}
-
-	return nil
+	return st.SetBalances(balances)
 }

 func TestDownloadFinalizedData(t *testing.T) {
@@ -452,29 +434,24 @@ func TestDownloadFinalizedData(t *testing.T) {
 	ms, err := st.MarshalSSZ()
 	require.NoError(t, err)

-	hc := &http.Client{
-		Transport: &testRT{rt: func(req *http.Request) (*http.Response, error) {
-			res := &http.Response{Request: req}
-			switch req.URL.Path {
-			case renderGetStatePath(IdFinalized):
-				res.StatusCode = http.StatusOK
-				res.Body = io.NopCloser(bytes.NewBuffer(ms))
-			case renderGetBlockPath(IdFromRoot(br)):
-				res.StatusCode = http.StatusOK
-				res.Body = io.NopCloser(bytes.NewBuffer(mb))
-			default:
-				res.StatusCode = http.StatusInternalServerError
-				res.Body = io.NopCloser(bytes.NewBufferString(""))
-			}
-
-			return res, nil
-		}},
-	}
-	c := &Client{
-		hc:      hc,
-		baseURL: &url.URL{Host: "localhost:3500", Scheme: "http"},
-	}
+	trans := &testRT{rt: func(req *http.Request) (*http.Response, error) {
+		res := &http.Response{Request: req}
+		switch req.URL.Path {
+		case renderGetStatePath(IdFinalized):
+			res.StatusCode = http.StatusOK
+			res.Body = io.NopCloser(bytes.NewBuffer(ms))
+		case renderGetBlockPath(IdFromRoot(br)):
+			res.StatusCode = http.StatusOK
+			res.Body = io.NopCloser(bytes.NewBuffer(mb))
+		default:
+			res.StatusCode = http.StatusInternalServerError
+			res.Body = io.NopCloser(bytes.NewBufferString(""))
+		}

+		return res, nil
+	}}
+	c, err := NewClient("http://localhost:3500", client.WithRoundTripper(trans))
+	require.NoError(t, err)
 	// sanity check before we go through checkpoint
 	// make sure we can download the state and unmarshal it with the VersionedUnmarshaler
 	sb, err := c.GetState(ctx, IdFinalized)
--- a/api/client/beacon/client.go
+++ b/api/client/beacon/client.go
@@ -5,8 +5,6 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"io"
-	"net"
 	"net/http"
 	"net/url"
 	"path"
@@ -14,16 +12,17 @@ import (
 	"sort"
 	"strconv"
 	"text/template"
-	"time"

-	"github.com/prysmaticlabs/prysm/v3/network/forks"
+	"github.com/prysmaticlabs/prysm/v4/api/client"
+	"github.com/prysmaticlabs/prysm/v4/network/forks"
+	v1 "github.com/prysmaticlabs/prysm/v4/proto/eth/v1"

 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/rpc/apimiddleware"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/rpc/apimiddleware"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
 	log "github.com/sirupsen/logrus"
 )

@@ -33,6 +32,7 @@ const (
 	getForkForStatePath      = "/eth/v1/beacon/states/{{.Id}}/fork"
 	getWeakSubjectivityPath  = "/eth/v1/beacon/weak_subjectivity"
 	getForkSchedulePath      = "/eth/v1/config/fork_schedule"
+	getConfigSpecPath        = "/eth/v1/config/spec"
 	getStatePath             = "/eth/v2/debug/beacon/states"
 	getNodeVersionPath       = "/eth/v1/node/version"
 	changeBLStoExecutionPath = "/eth/v1/beacon/pool/bls_to_execution_changes"
@@ -52,8 +52,6 @@ const (
 	IdFinalized StateOrBlockId = "finalized"
 )

-var ErrMalformedHostname = errors.New("hostname must include port, separated by one colon, like example.com:3500")
-
 // IdFromRoot encodes a block root in the format expected by the API in places where a root can be used to identify
 // a BeaconState or SignedBeaconBlock.
 func IdFromRoot(r [32]byte) StateOrBlockId {
@@ -83,96 +81,22 @@ func idTemplate(ts string) func(StateOrBlockId) string {
 	return f
 }

-// ClientOpt is a functional option for the Client type (http.Client wrapper)
-type ClientOpt func(*Client)
-
-// WithTimeout sets the .Timeout attribute of the wrapped http.Client.
-func WithTimeout(timeout time.Duration) ClientOpt {
-	return func(c *Client) {
-		c.hc.Timeout = timeout
-	}
+func renderGetBlockPath(id StateOrBlockId) string {
+	return path.Join(getSignedBlockPath, string(id))
 }

 // Client provides a collection of helper methods for calling the Eth Beacon Node API endpoints.
 type Client struct {
-	hc      *http.Client
-	baseURL *url.URL
+	*client.Client
 }

-// NewClient constructs a new client with the provided options (ex WithTimeout).
-// `host` is the base host + port used to construct request urls. This value can be
-// a URL string, or NewClient will assume an http endpoint if just `host:port` is used.
-func NewClient(host string, opts ...ClientOpt) (*Client, error) {
-	u, err := urlForHost(host)
+// NewClient returns a new Client that includes functions for rest calls to Beacon API.
+func NewClient(host string, opts ...client.ClientOpt) (*Client, error) {
+	c, err := client.NewClient(host, opts...)
 	if err != nil {
 		return nil, err
 	}
-	c := &Client{
-		hc:      &http.Client{},
-		baseURL: u,
-	}
-	for _, o := range opts {
-		o(c)
-	}
-	return c, nil
-}
-
-func urlForHost(h string) (*url.URL, error) {
-	// try to parse as url (being permissive)
-	u, err := url.Parse(h)
-	if err == nil && u.Host != "" {
-		return u, nil
-	}
-	// try to parse as host:port
-	host, port, err := net.SplitHostPort(h)
-	if err != nil {
-		return nil, ErrMalformedHostname
-	}
-	return &url.URL{Host: fmt.Sprintf("%s:%s", host, port), Scheme: "http"}, nil
-}
-
-// NodeURL returns a human-readable string representation of the beacon node base url.
-func (c *Client) NodeURL() string {
-	return c.baseURL.String()
-}
-
-type reqOption func(*http.Request)
-
-func withSSZEncoding() reqOption {
-	return func(req *http.Request) {
-		req.Header.Set("Accept", "application/octet-stream")
-	}
-}
-
-// get is a generic, opinionated GET function to reduce boilerplate amongst the getters in this package.
-func (c *Client) get(ctx context.Context, path string, opts ...reqOption) ([]byte, error) {
-	u := c.baseURL.ResolveReference(&url.URL{Path: path})
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), nil)
-	if err != nil {
-		return nil, err
-	}
-	for _, o := range opts {
-		o(req)
-	}
-	r, err := c.hc.Do(req)
-	if err != nil {
-		return nil, err
-	}
-	defer func() {
-		err = r.Body.Close()
-	}()
-	if r.StatusCode != http.StatusOK {
-		return nil, non200Err(r)
-	}
-	b, err := io.ReadAll(r.Body)
-	if err != nil {
-		return nil, errors.Wrap(err, "error reading http response body from GetBlock")
-	}
-	return b, nil
-}
-
-func renderGetBlockPath(id StateOrBlockId) string {
-	return path.Join(getSignedBlockPath, string(id))
+	return &Client{c}, nil
 }

 // GetBlock retrieves the SignedBeaconBlock for the given block id.
@@ -182,7 +106,7 @@ func renderGetBlockPath(id StateOrBlockId) string {
 // The return value contains the ssz-encoded bytes.
 func (c *Client) GetBlock(ctx context.Context, blockId StateOrBlockId) ([]byte, error) {
 	blockPath := renderGetBlockPath(blockId)
-	b, err := c.get(ctx, blockPath, withSSZEncoding())
+	b, err := c.Get(ctx, blockPath, client.WithSSZEncoding())
 	if err != nil {
 		return nil, errors.Wrapf(err, "error requesting state by id = %s", blockId)
 	}
@@ -197,7 +121,7 @@ var getBlockRootTpl = idTemplate(getBlockRootPath)
 // for the named identifiers.
 func (c *Client) GetBlockRoot(ctx context.Context, blockId StateOrBlockId) ([32]byte, error) {
 	rootPath := getBlockRootTpl(blockId)
-	b, err := c.get(ctx, rootPath)
+	b, err := c.Get(ctx, rootPath)
 	if err != nil {
 		return [32]byte{}, errors.Wrapf(err, "error requesting block root by id = %s", blockId)
 	}
@@ -220,7 +144,7 @@ var getForkTpl = idTemplate(getForkForStatePath)
 // <slot>, <hex encoded blockRoot with 0x prefix>. Variables of type StateOrBlockId are exported by this package
 // for the named identifiers.
 func (c *Client) GetFork(ctx context.Context, stateId StateOrBlockId) (*ethpb.Fork, error) {
-	body, err := c.get(ctx, getForkTpl(stateId))
+	body, err := c.Get(ctx, getForkTpl(stateId))
 	if err != nil {
 		return nil, errors.Wrapf(err, "error requesting fork by state id = %s", stateId)
 	}
@@ -236,7 +160,7 @@ func (c *Client) GetFork(ctx context.Context, stateId StateOrBlockId) (*ethpb.Fo

 // GetForkSchedule retrieve all forks, past present and future, of which this node is aware.
 func (c *Client) GetForkSchedule(ctx context.Context) (forks.OrderedSchedule, error) {
-	body, err := c.get(ctx, getForkSchedulePath)
+	body, err := c.Get(ctx, getForkSchedulePath)
 	if err != nil {
 		return nil, errors.Wrap(err, "error requesting fork schedule")
 	}
@@ -252,6 +176,20 @@ func (c *Client) GetForkSchedule(ctx context.Context) (forks.OrderedSchedule, er
 	return ofs, nil
 }

+// GetConfigSpec retrieve the current configs of the network used by the beacon node.
+func (c *Client) GetConfigSpec(ctx context.Context) (*v1.SpecResponse, error) {
+	body, err := c.Get(ctx, getConfigSpecPath)
+	if err != nil {
+		return nil, errors.Wrap(err, "error requesting configSpecPath")
+	}
+	fsr := &v1.SpecResponse{}
+	err = json.Unmarshal(body, fsr)
+	if err != nil {
+		return nil, err
+	}
+	return fsr, nil
+}
+
 type NodeVersion struct {
 	implementation string
 	semver         string
@@ -263,7 +201,7 @@ var versionRE = regexp.MustCompile(`^(\w+)/(v\d+\.\d+\.\d+[-a-zA-Z0-9]*)\s*/?(.*
 func parseNodeVersion(v string) (*NodeVersion, error) {
 	groups := versionRE.FindStringSubmatch(v)
 	if len(groups) != 4 {
-		return nil, errors.Wrapf(ErrInvalidNodeVersion, "could not be parsed: %s", v)
+		return nil, errors.Wrapf(client.ErrInvalidNodeVersion, "could not be parsed: %s", v)
 	}
 	return &NodeVersion{
 		implementation: groups[1],
@@ -275,7 +213,7 @@ func parseNodeVersion(v string) (*NodeVersion, error) {
 // GetNodeVersion requests that the beacon node identify information about its implementation in a format
 // similar to a HTTP User-Agent field. ex: Lighthouse/v0.1.5 (Linux x86_64)
 func (c *Client) GetNodeVersion(ctx context.Context) (*NodeVersion, error) {
-	b, err := c.get(ctx, getNodeVersionPath)
+	b, err := c.Get(ctx, getNodeVersionPath)
 	if err != nil {
 		return nil, errors.Wrap(err, "error requesting node version")
 	}
@@ -302,7 +240,7 @@ func renderGetStatePath(id StateOrBlockId) string {
 // The return value contains the ssz-encoded bytes.
 func (c *Client) GetState(ctx context.Context, stateId StateOrBlockId) ([]byte, error) {
 	statePath := path.Join(getStatePath, string(stateId))
-	b, err := c.get(ctx, statePath, withSSZEncoding())
+	b, err := c.Get(ctx, statePath, client.WithSSZEncoding())
 	if err != nil {
 		return nil, errors.Wrapf(err, "error requesting state by id = %s", stateId)
 	}
@@ -315,7 +253,7 @@ func (c *Client) GetState(ctx context.Context, stateId StateOrBlockId) ([]byte,
 // - finds the highest non-skipped block preceding the epoch
 // - returns the htr of the found block and returns this + the value of state_root from the block
 func (c *Client) GetWeakSubjectivity(ctx context.Context) (*WeakSubjectivityData, error) {
-	body, err := c.get(ctx, getWeakSubjectivityPath)
+	body, err := c.Get(ctx, getWeakSubjectivityPath)
 	if err != nil {
 		return nil, err
 	}
@@ -346,7 +284,7 @@ func (c *Client) GetWeakSubjectivity(ctx context.Context) (*WeakSubjectivityData
 // SubmitChangeBLStoExecution calls a beacon API endpoint to set the withdrawal addresses based on the given signed messages.
 // If the API responds with something other than OK there will be failure messages associated to the corresponding request message.
 func (c *Client) SubmitChangeBLStoExecution(ctx context.Context, request []*apimiddleware.SignedBLSToExecutionChangeJson) error {
-	u := c.baseURL.ResolveReference(&url.URL{Path: changeBLStoExecutionPath})
+	u := c.BaseURL().ResolveReference(&url.URL{Path: changeBLStoExecutionPath})
 	body, err := json.Marshal(request)
 	if err != nil {
 		return errors.Wrap(err, "failed to marshal JSON")
@@ -356,7 +294,7 @@ func (c *Client) SubmitChangeBLStoExecution(ctx context.Context, request []*apim
 		return errors.Wrap(err, "invalid format, failed to create new POST request object")
 	}
 	req.Header.Set("Content-Type", "application/json")
-	resp, err := c.hc.Do(req)
+	resp, err := c.Do(req)
 	if err != nil {
 		return err
 	}
@@ -385,7 +323,7 @@ func (c *Client) SubmitChangeBLStoExecution(ctx context.Context, request []*apim
 // GetBLStoExecutionChanges gets all the set withdrawal messages in the node's operation pool.
 // Returns a struct representation of json response.
 func (c *Client) GetBLStoExecutionChanges(ctx context.Context) (*apimiddleware.BLSToExecutionChangesPoolResponseJson, error) {
-	body, err := c.get(ctx, changeBLStoExecutionPath)
+	body, err := c.Get(ctx, changeBLStoExecutionPath)
 	if err != nil {
 		return nil, err
 	}
@@ -397,23 +335,6 @@ func (c *Client) GetBLStoExecutionChanges(ctx context.Context) (*apimiddleware.B
 	return poolResponse, nil
 }

-func non200Err(response *http.Response) error {
-	bodyBytes, err := io.ReadAll(response.Body)
-	var body string
-	if err != nil {
-		body = "(Unable to read response body.)"
-	} else {
-		body = "response body:\n" + string(bodyBytes)
-	}
-	msg := fmt.Sprintf("code=%d, url=%s, body=%s", response.StatusCode, response.Request.URL, body)
-	switch response.StatusCode {
-	case 404:
-		return errors.Wrap(ErrNotFound, msg)
-	default:
-		return errors.Wrap(ErrNotOK, msg)
-	}
-}
-
 type forkResponse struct {
 	PreviousVersion string `json:"previous_version"`
 	CurrentVersion  string `json:"current_version"`
--- a/api/client/beacon/client_test.go
+++ b/api/client/beacon/client_test.go
@@ -4,7 +4,8 @@ import (
 	"net/url"
 	"testing"

-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/api/client"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 func TestParseNodeVersion(t *testing.T) {
@@ -17,17 +18,17 @@ func TestParseNodeVersion(t *testing.T) {
 		{
 			name: "empty string",
 			v:    "",
-			err:  ErrInvalidNodeVersion,
+			err:  client.ErrInvalidNodeVersion,
 		},
 		{
 			name: "Prysm as the version string",
 			v:    "Prysm",
-			err:  ErrInvalidNodeVersion,
+			err:  client.ErrInvalidNodeVersion,
 		},
 		{
 			name: "semver only",
 			v:    "v2.0.6",
-			err:  ErrInvalidNodeVersion,
+			err:  client.ErrInvalidNodeVersion,
 		},
 		{
 			name: "complete version",
@@ -91,7 +92,7 @@ func TestValidHostname(t *testing.T) {
 		{
 			name:    "hostname without port",
 			hostArg: "mydomain.org",
-			err:     ErrMalformedHostname,
+			err:     client.ErrMalformedHostname,
 		},
 		{
 			name:    "hostname with port",
@@ -132,7 +133,7 @@ func TestValidHostname(t *testing.T) {
 				return
 			}
 			require.NoError(t, err)
-			require.Equal(t, c.joined, cl.baseURL.ResolveReference(&url.URL{Path: c.path}).String())
+			require.Equal(t, c.joined, cl.BaseURL().ResolveReference(&url.URL{Path: c.path}).String())
 		})
 	}
 }
--- a/api/client/beacon/errors.go
+++ b/api/client/beacon/errors.go
@@ -1,13 +0,0 @@
-package beacon
-
-import "github.com/pkg/errors"
-
-// ErrNotOK is used to indicate when an HTTP request to the Beacon Node API failed with any non-2xx response code.
-// More specific errors may be returned, but an error in reaction to a non-2xx response will always wrap ErrNotOK.
-var ErrNotOK = errors.New("did not receive 2xx response from API")
-
-// ErrNotFound specifically means that a '404 - NOT FOUND' response was received from the API.
-var ErrNotFound = errors.Wrap(ErrNotOK, "recv 404 NotFound response from API")
-
-// ErrInvalidNodeVersion indicates that the /eth/v1/node/version api response format was not recognized.
-var ErrInvalidNodeVersion = errors.New("invalid node version response")
--- a/api/client/builder/BUILD.bazel
+++ b/api/client/builder/BUILD.bazel
@@ -8,13 +8,15 @@ go_library(
        "errors.go",
        "types.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/v3/api/client/builder",
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/client/builder",
    visibility = ["//visibility:public"],
    deps = [
+        "//consensus-types:go_default_library",
        "//consensus-types/blocks:go_default_library",
        "//consensus-types/interfaces:go_default_library",
        "//consensus-types/primitives:go_default_library",
        "//encoding/bytesutil:go_default_library",
+        "//math:go_default_library",
        "//monitoring/tracing:go_default_library",
        "//network:go_default_library",
        "//network/authorization:go_default_library",
--- a/api/client/builder/bid.go
+++ b/api/client/builder/bid.go
@@ -1,11 +1,17 @@
 package builder

 import (
+	"math/big"
+
+	"github.com/pkg/errors"
 	ssz "github.com/prysmaticlabs/fastssz"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
+	consensus_types "github.com/prysmaticlabs/prysm/v4/consensus-types"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/v4/math"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
 )

 // SignedBid is an interface describing the method set of a signed builder bid.
@@ -35,7 +41,7 @@ type signedBuilderBid struct {
 func WrappedSignedBuilderBid(p *ethpb.SignedBuilderBid) (SignedBid, error) {
 	w := signedBuilderBid{p: p}
 	if w.IsNil() {
-		return nil, blocks.ErrNilObjectWrapped
+		return nil, consensus_types.ErrNilObjectWrapped
 	}
 	return w, nil
 }
@@ -68,7 +74,7 @@ type signedBuilderBidCapella struct {
 func WrappedSignedBuilderBidCapella(p *ethpb.SignedBuilderBidCapella) (SignedBid, error) {
 	w := signedBuilderBidCapella{p: p}
 	if w.IsNil() {
-		return nil, blocks.ErrNilObjectWrapped
+		return nil, consensus_types.ErrNilObjectWrapped
 	}
 	return w, nil
 }
@@ -101,7 +107,7 @@ type builderBid struct {
 func WrappedBuilderBid(p *ethpb.BuilderBid) (Bid, error) {
 	w := builderBid{p: p}
 	if w.IsNil() {
-		return nil, blocks.ErrNilObjectWrapped
+		return nil, consensus_types.ErrNilObjectWrapped
 	}
 	return w, nil
 }
@@ -149,14 +155,19 @@ type builderBidCapella struct {
 func WrappedBuilderBidCapella(p *ethpb.BuilderBidCapella) (Bid, error) {
 	w := builderBidCapella{p: p}
 	if w.IsNil() {
-		return nil, blocks.ErrNilObjectWrapped
+		return nil, consensus_types.ErrNilObjectWrapped
 	}
 	return w, nil
 }

-// Header --
+// Header returns the execution data interface.
 func (b builderBidCapella) Header() (interfaces.ExecutionData, error) {
-	return blocks.WrappedExecutionPayloadHeaderCapella(b.p.Header)
+	if b.p == nil {
+		return nil, errors.New("builder bid is nil")
+	}
+	// We have to convert big endian to little endian because the value is coming from the execution layer.
+	v := big.NewInt(0).SetBytes(bytesutil.ReverseByteOrder(b.p.Value))
+	return blocks.WrappedExecutionPayloadHeaderCapella(b.p.Header, math.WeiToGwei(v))
 }

 // Version --
--- a/api/client/builder/client.go
+++ b/api/client/builder/client.go
@@ -11,18 +11,16 @@ import (
 	"net/url"
 	"strings"
 	"text/template"
-	"time"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/monitoring/tracing"
-	"github.com/prysmaticlabs/prysm/v3/network"
-	"github.com/prysmaticlabs/prysm/v3/network/authorization"
-	v1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
+	"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/tracing"
+	"github.com/prysmaticlabs/prysm/v4/network"
+	"github.com/prysmaticlabs/prysm/v4/network/authorization"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
 	log "github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )
@@ -37,7 +35,6 @@ const (
 var errMalformedHostname = errors.New("hostname must include port, separated by one colon, like example.com:3500")
 var errMalformedRequest = errors.New("required request data are missing")
 var errNotBlinded = errors.New("submitted block is not blinded")
-var submitBlindedBlockTimeout = 3 * time.Second

 // ClientOpt is a functional option for the Client type (http.Client wrapper)
 type ClientOpt func(*Client)
@@ -89,7 +86,7 @@ type BuilderClient interface {
 	NodeURL() string
 	GetHeader(ctx context.Context, slot primitives.Slot, parentHash [32]byte, pubkey [48]byte) (SignedBid, error)
 	RegisterValidator(ctx context.Context, svr []*ethpb.SignedValidatorRegistrationV1) error
-	SubmitBlindedBlock(ctx context.Context, sb interfaces.SignedBeaconBlock) (interfaces.ExecutionData, error)
+	SubmitBlindedBlock(ctx context.Context, sb interfaces.ReadOnlySignedBeaconBlock) (interfaces.ExecutionData, error)
 	Status(ctx context.Context) error
 }

@@ -157,6 +154,7 @@ func (c *Client) do(ctx context.Context, method string, path string, body io.Rea
 	if err != nil {
 		return
 	}
+	req.Header.Add("User-Agent", version.BuildData())
 	for _, o := range opts {
 		o(req)
 	}
@@ -245,7 +243,6 @@ func (c *Client) GetHeader(ctx context.Context, slot primitives.Slot, parentHash
 	default:
 		return nil, fmt.Errorf("unsupported header version %s", strings.ToLower(v.Version))
 	}
-
 }

 // RegisterValidator encodes the SignedValidatorRegistrationV1 message to json (including hex-encoding the byte
@@ -277,7 +274,7 @@ func (c *Client) RegisterValidator(ctx context.Context, svr []*ethpb.SignedValid

 // SubmitBlindedBlock calls the builder API endpoint that binds the validator to the builder and submits the block.
 // The response is the full execution payload used to create the blinded block.
-func (c *Client) SubmitBlindedBlock(ctx context.Context, sb interfaces.SignedBeaconBlock) (interfaces.ExecutionData, error) {
+func (c *Client) SubmitBlindedBlock(ctx context.Context, sb interfaces.ReadOnlySignedBeaconBlock) (interfaces.ExecutionData, error) {
 	if !sb.IsBlinded() {
 		return nil, errNotBlinded
 	}
@@ -293,9 +290,10 @@ func (c *Client) SubmitBlindedBlock(ctx context.Context, sb interfaces.SignedBea
 			return nil, errors.Wrap(err, "error encoding the SignedBlindedBeaconBlockBellatrix value body in SubmitBlindedBlock")
 		}

-		ctx, cancel := context.WithTimeout(ctx, submitBlindedBlockTimeout)
-		defer cancel()
-		rb, err := c.do(ctx, http.MethodPost, postBlindedBeaconBlockPath, bytes.NewBuffer(body))
+		versionOpt := func(r *http.Request) {
+			r.Header.Add("Eth-Consensus-Version", version.String(version.Bellatrix))
+		}
+		rb, err := c.do(ctx, http.MethodPost, postBlindedBeaconBlockPath, bytes.NewBuffer(body), versionOpt)

 		if err != nil {
 			return nil, errors.Wrap(err, "error posting the SignedBlindedBeaconBlockBellatrix to the builder api")
@@ -304,6 +302,9 @@ func (c *Client) SubmitBlindedBlock(ctx context.Context, sb interfaces.SignedBea
 		if err := json.Unmarshal(rb, ep); err != nil {
 			return nil, errors.Wrap(err, "error unmarshaling the builder SubmitBlindedBlock response")
 		}
+		if strings.ToLower(ep.Version) != version.String(version.Bellatrix) {
+			return nil, errors.New("not a bellatrix payload")
+		}
 		p, err := ep.ToProto()
 		if err != nil {
 			return nil, errors.Wrapf(err, "could not extract proto message from payload")
@@ -320,9 +321,10 @@ func (c *Client) SubmitBlindedBlock(ctx context.Context, sb interfaces.SignedBea
 			return nil, errors.Wrap(err, "error encoding the SignedBlindedBeaconBlockCapella value body in SubmitBlindedBlockCapella")
 		}

-		ctx, cancel := context.WithTimeout(ctx, submitBlindedBlockTimeout)
-		defer cancel()
-		rb, err := c.do(ctx, http.MethodPost, postBlindedBeaconBlockPath, bytes.NewBuffer(body))
+		versionOpt := func(r *http.Request) {
+			r.Header.Add("Eth-Consensus-Version", version.String(version.Capella))
+		}
+		rb, err := c.do(ctx, http.MethodPost, postBlindedBeaconBlockPath, bytes.NewBuffer(body), versionOpt)

 		if err != nil {
 			return nil, errors.Wrap(err, "error posting the SignedBlindedBeaconBlockCapella to the builder api")
@@ -331,39 +333,19 @@ func (c *Client) SubmitBlindedBlock(ctx context.Context, sb interfaces.SignedBea
 		if err := json.Unmarshal(rb, ep); err != nil {
 			return nil, errors.Wrap(err, "error unmarshaling the builder SubmitBlindedBlockCapella response")
 		}
+		if strings.ToLower(ep.Version) != version.String(version.Capella) {
+			return nil, errors.New("not a capella payload")
+		}
 		p, err := ep.ToProto()
 		if err != nil {
 			return nil, errors.Wrapf(err, "could not extract proto message from payload")
 		}
-		return blocks.WrappedExecutionPayloadCapella(p)
+		return blocks.WrappedExecutionPayloadCapella(p, 0)
 	default:
 		return nil, fmt.Errorf("unsupported block version %s", version.String(sb.Version()))
 	}
 }

-// SubmitBlindedBlockCapella calls the builder API endpoint that binds the validator to the builder and submits the block.
-// The response is the full ExecutionPayloadCapella used to create the blinded block.
-func (c *Client) SubmitBlindedBlockCapella(ctx context.Context, sb *ethpb.SignedBlindedBeaconBlockCapella) (*v1.ExecutionPayloadCapella, error) {
-	v := &SignedBlindedBeaconBlockCapella{SignedBlindedBeaconBlockCapella: sb}
-	body, err := json.Marshal(v)
-	if err != nil {
-		return nil, errors.Wrap(err, "error encoding the SignedBlindedBeaconBlockCapella value body in SubmitBlindedBlockCapella")
-	}
-
-	ctx, cancel := context.WithTimeout(ctx, submitBlindedBlockTimeout)
-	defer cancel()
-	rb, err := c.do(ctx, http.MethodPost, postBlindedBeaconBlockPath, bytes.NewBuffer(body))
-
-	if err != nil {
-		return nil, errors.Wrap(err, "error posting the SignedBlindedBeaconBlockBellatrix to the builder api")
-	}
-	ep := &ExecPayloadResponseCapella{}
-	if err := json.Unmarshal(rb, ep); err != nil {
-		return nil, errors.Wrap(err, "error unmarshaling the builder SubmitBlindedBlockCapella response")
-	}
-	return ep.ToProto()
-}
-
 // Status asks the remote builder server for a health check. A response of 200 with an empty body is the success/healthy
 // response, and an error response may have an error message. This method will return a nil value for error in the
 // happy path, and an error with information about the server response body for a non-200 response.
--- a/api/client/builder/client_test.go
+++ b/api/client/builder/client_test.go
@@ -6,20 +6,21 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"math/big"
 	"net/http"
 	"net/url"
 	"strconv"
 	"testing"

 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	types "github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	v1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	eth "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	types "github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	v1 "github.com/prysmaticlabs/prysm/v4/proto/engine/v1"
+	eth "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 type roundtrip func(*http.Request) (*http.Response, error)
@@ -199,6 +200,9 @@ func TestClient_GetHeader(t *testing.T) {
 		value, err := stringToUint256("652312848583266388373324160190187140051835877600158453279131187530910662656")
 		require.NoError(t, err)
 		require.Equal(t, fmt.Sprintf("%#x", value.SSZBytes()), fmt.Sprintf("%#x", bid.Value()))
+		bidValue := bytesutil.ReverseByteOrder(bid.Value())
+		require.DeepEqual(t, bidValue, value.Bytes())
+		require.DeepEqual(t, big.NewInt(0).SetBytes(bidValue), value.Int)
 	})
 	t.Run("capella", func(t *testing.T) {
 		hc := &http.Client{
@@ -225,6 +229,12 @@ func TestClient_GetHeader(t *testing.T) {
 		withdrawalsRoot, err := bidHeader.WithdrawalsRoot()
 		require.NoError(t, err)
 		require.Equal(t, true, bytes.Equal(expectedWithdrawalsRoot, withdrawalsRoot))
+		value, err := stringToUint256("652312848583266388373324160190187140051835877600158453279131187530910662656")
+		require.NoError(t, err)
+		require.Equal(t, fmt.Sprintf("%#x", value.SSZBytes()), fmt.Sprintf("%#x", bid.Value()))
+		bidValue := bytesutil.ReverseByteOrder(bid.Value())
+		require.DeepEqual(t, bidValue, value.Bytes())
+		require.DeepEqual(t, big.NewInt(0).SetBytes(bidValue), value.Int)
 	})
 	t.Run("unsupported version", func(t *testing.T) {
 		hc := &http.Client{
@@ -253,6 +263,7 @@ func TestSubmitBlindedBlock(t *testing.T) {
 		hc := &http.Client{
 			Transport: roundtrip(func(r *http.Request) (*http.Response, error) {
 				require.Equal(t, postBlindedBeaconBlockPath, r.URL.Path)
+				require.Equal(t, "bellatrix", r.Header.Get("Eth-Consensus-Version"))
 				return &http.Response{
 					StatusCode: http.StatusOK,
 					Body:       io.NopCloser(bytes.NewBufferString(testExampleExecutionPayload)),
@@ -278,6 +289,7 @@ func TestSubmitBlindedBlock(t *testing.T) {
 		hc := &http.Client{
 			Transport: roundtrip(func(r *http.Request) (*http.Response, error) {
 				require.Equal(t, postBlindedBeaconBlockPath, r.URL.Path)
+				require.Equal(t, "capella", r.Header.Get("Eth-Consensus-Version"))
 				return &http.Response{
 					StatusCode: http.StatusOK,
 					Body:       io.NopCloser(bytes.NewBufferString(testExampleExecutionPayloadCapella)),
@@ -301,6 +313,26 @@ func TestSubmitBlindedBlock(t *testing.T) {
 		assert.DeepEqual(t, ezDecode(t, "0xcf8e0d4e9587369b2301d0790347320302cc0943"), withdrawals[0].Address)
 		assert.Equal(t, uint64(1), withdrawals[0].Amount)
 	})
+	t.Run("mismatched versions, expected bellatrix got capella", func(t *testing.T) {
+		hc := &http.Client{
+			Transport: roundtrip(func(r *http.Request) (*http.Response, error) {
+				require.Equal(t, postBlindedBeaconBlockPath, r.URL.Path)
+				return &http.Response{
+					StatusCode: http.StatusOK,
+					Body:       io.NopCloser(bytes.NewBufferString(testExampleExecutionPayloadCapella)), // send a Capella payload
+					Request:    r.Clone(ctx),
+				}, nil
+			}),
+		}
+		c := &Client{
+			hc:      hc,
+			baseURL: &url.URL{Host: "localhost:3500", Scheme: "http"},
+		}
+		sbbb, err := blocks.NewSignedBeaconBlock(testSignedBlindedBeaconBlockBellatrix(t))
+		require.NoError(t, err)
+		_, err = c.SubmitBlindedBlock(ctx, sbbb)
+		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{}}})
 		require.NoError(t, err)
--- a/api/client/builder/testing/BUILD.bazel
+++ b/api/client/builder/testing/BUILD.bazel
@@ -3,7 +3,7 @@ load("@prysm//tools/go:def.bzl", "go_library")
 go_library(
    name = "go_default_library",
    srcs = ["mock.go"],
-    importpath = "github.com/prysmaticlabs/prysm/v3/api/client/builder/testing",
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/client/builder/testing",
    visibility = ["//visibility:public"],
    deps = [
        "//api/client/builder:go_default_library",
--- a/api/client/builder/testing/mock.go
+++ b/api/client/builder/testing/mock.go
@@ -3,11 +3,11 @@ package testing
 import (
 	"context"

-	"github.com/prysmaticlabs/prysm/v3/api/client/builder"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/api/client/builder"
+	"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"
 )

 // MockClient is a mock implementation of BuilderClient.
@@ -40,7 +40,7 @@ func (m MockClient) RegisterValidator(_ context.Context, svr []*ethpb.SignedVali
 }

 // SubmitBlindedBlock --
-func (MockClient) SubmitBlindedBlock(_ context.Context, _ interfaces.SignedBeaconBlock) (interfaces.ExecutionData, error) {
+func (MockClient) SubmitBlindedBlock(_ context.Context, _ interfaces.ReadOnlySignedBeaconBlock) (interfaces.ExecutionData, error) {
 	return nil, nil
 }

--- a/api/client/builder/types.go
+++ b/api/client/builder/types.go
@@ -8,10 +8,10 @@ import (

 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/pkg/errors"
-	types "github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	v1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	eth "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
+	types "github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	v1 "github.com/prysmaticlabs/prysm/v4/proto/engine/v1"
+	eth "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
 )

 type SignedValidatorRegistration struct {
@@ -346,6 +346,74 @@ func (p *ExecutionPayload) ToProto() (*v1.ExecutionPayload, error) {
 	}, nil
 }

+// FromProto converts a proto execution payload type to our builder
+// compatible payload type.
+func FromProto(payload *v1.ExecutionPayload) (ExecutionPayload, error) {
+	bFee, err := sszBytesToUint256(payload.BaseFeePerGas)
+	if err != nil {
+		return ExecutionPayload{}, err
+	}
+	txs := make([]hexutil.Bytes, len(payload.Transactions))
+	for i := range payload.Transactions {
+		txs[i] = payload.Transactions[i]
+	}
+	return ExecutionPayload{
+		ParentHash:    payload.ParentHash,
+		FeeRecipient:  payload.FeeRecipient,
+		StateRoot:     payload.StateRoot,
+		ReceiptsRoot:  payload.ReceiptsRoot,
+		LogsBloom:     payload.LogsBloom,
+		PrevRandao:    payload.PrevRandao,
+		BlockNumber:   Uint64String(payload.BlockNumber),
+		GasLimit:      Uint64String(payload.GasLimit),
+		GasUsed:       Uint64String(payload.GasUsed),
+		Timestamp:     Uint64String(payload.Timestamp),
+		ExtraData:     payload.ExtraData,
+		BaseFeePerGas: bFee,
+		BlockHash:     payload.BlockHash,
+		Transactions:  txs,
+	}, nil
+}
+
+// FromProtoCapella converts a proto execution payload type for capella to our
+// builder compatible payload type.
+func FromProtoCapella(payload *v1.ExecutionPayloadCapella) (ExecutionPayloadCapella, error) {
+	bFee, err := sszBytesToUint256(payload.BaseFeePerGas)
+	if err != nil {
+		return ExecutionPayloadCapella{}, err
+	}
+	txs := make([]hexutil.Bytes, len(payload.Transactions))
+	for i := range payload.Transactions {
+		txs[i] = payload.Transactions[i]
+	}
+	withdrawals := make([]Withdrawal, len(payload.Withdrawals))
+	for i, w := range payload.Withdrawals {
+		withdrawals[i] = Withdrawal{
+			Index:          Uint256{Int: big.NewInt(0).SetUint64(w.Index)},
+			ValidatorIndex: Uint256{Int: big.NewInt(0).SetUint64(uint64(w.ValidatorIndex))},
+			Address:        w.Address,
+			Amount:         Uint256{Int: big.NewInt(0).SetUint64(w.Amount)},
+		}
+	}
+	return ExecutionPayloadCapella{
+		ParentHash:    payload.ParentHash,
+		FeeRecipient:  payload.FeeRecipient,
+		StateRoot:     payload.StateRoot,
+		ReceiptsRoot:  payload.ReceiptsRoot,
+		LogsBloom:     payload.LogsBloom,
+		PrevRandao:    payload.PrevRandao,
+		BlockNumber:   Uint64String(payload.BlockNumber),
+		GasLimit:      Uint64String(payload.GasLimit),
+		GasUsed:       Uint64String(payload.GasUsed),
+		Timestamp:     Uint64String(payload.Timestamp),
+		ExtraData:     payload.ExtraData,
+		BaseFeePerGas: bFee,
+		BlockHash:     payload.BlockHash,
+		Transactions:  txs,
+		Withdrawals:   withdrawals,
+	}, nil
+}
+
 type ExecHeaderResponseCapella struct {
 	Data struct {
 		Signature hexutil.Bytes      `json:"signature"`
--- a/api/client/builder/types_test.go
+++ b/api/client/builder/types_test.go
@@ -14,10 +14,10 @@ import (
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/golang/protobuf/proto"
 	"github.com/prysmaticlabs/go-bitfield"
-	v1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	eth "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	v1 "github.com/prysmaticlabs/prysm/v4/proto/engine/v1"
+	eth "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 func ezDecode(t *testing.T, s string) []byte {
--- a/api/client/client.go
+++ b/api/client/client.go
@@ -0,0 +1,97 @@
+package client
+
+import (
+	"context"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+
+	"github.com/pkg/errors"
+)
+
+// Client is a wrapper object around the HTTP client.
+type Client struct {
+	hc      *http.Client
+	baseURL *url.URL
+	token   string
+}
+
+// NewClient constructs a new client with the provided options (ex WithTimeout).
+// `host` is the base host + port used to construct request urls. This value can be
+// a URL string, or NewClient will assume an http endpoint if just `host:port` is used.
+func NewClient(host string, opts ...ClientOpt) (*Client, error) {
+	u, err := urlForHost(host)
+	if err != nil {
+		return nil, err
+	}
+	c := &Client{
+		hc:      &http.Client{},
+		baseURL: u,
+	}
+	for _, o := range opts {
+		o(c)
+	}
+	return c, nil
+}
+
+// Token returns the bearer token used for jwt authentication
+func (c *Client) Token() string {
+	return c.token
+}
+
+// BaseURL returns the base url of the client
+func (c *Client) BaseURL() *url.URL {
+	return c.baseURL
+}
+
+// Do execute the request against the http client
+func (c *Client) Do(req *http.Request) (*http.Response, error) {
+	return c.hc.Do(req)
+}
+
+func urlForHost(h string) (*url.URL, error) {
+	// try to parse as url (being permissive)
+	u, err := url.Parse(h)
+	if err == nil && u.Host != "" {
+		return u, nil
+	}
+	// try to parse as host:port
+	host, port, err := net.SplitHostPort(h)
+	if err != nil {
+		return nil, ErrMalformedHostname
+	}
+	return &url.URL{Host: net.JoinHostPort(host, port), Scheme: "http"}, nil
+}
+
+// NodeURL returns a human-readable string representation of the beacon node base url.
+func (c *Client) NodeURL() string {
+	return c.baseURL.String()
+}
+
+// Get is a generic, opinionated GET function to reduce boilerplate amongst the getters in this package.
+func (c *Client) Get(ctx context.Context, path string, opts ...ReqOption) ([]byte, error) {
+	u := c.baseURL.ResolveReference(&url.URL{Path: path})
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+	for _, o := range opts {
+		o(req)
+	}
+	r, err := c.hc.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		err = r.Body.Close()
+	}()
+	if r.StatusCode != http.StatusOK {
+		return nil, Non200Err(r)
+	}
+	b, err := io.ReadAll(r.Body)
+	if err != nil {
+		return nil, errors.Wrap(err, "error reading http response body")
+	}
+	return b, nil
+}
--- a/api/client/client_test.go
+++ b/api/client/client_test.go
@@ -0,0 +1,48 @@
+package client
+
+import (
+	"net/url"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+)
+
+func TestValidHostname(t *testing.T) {
+	cases := []struct {
+		name    string
+		hostArg string
+		path    string
+		joined  string
+		err     error
+	}{
+		{
+			name:    "hostname without port",
+			hostArg: "mydomain.org",
+			err:     ErrMalformedHostname,
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			cl, err := NewClient(c.hostArg)
+			if c.err != nil {
+				require.ErrorIs(t, err, c.err)
+				return
+			}
+			require.NoError(t, err)
+			require.Equal(t, c.joined, cl.BaseURL().ResolveReference(&url.URL{Path: c.path}).String())
+		})
+	}
+}
+
+func TestWithAuthenticationToken(t *testing.T) {
+	cl, err := NewClient("https://www.offchainlabs.com:3500", WithAuthenticationToken("my token"))
+	require.NoError(t, err)
+	require.Equal(t, cl.Token(), "my token")
+}
+
+func TestBaseURL(t *testing.T) {
+	cl, err := NewClient("https://www.offchainlabs.com:3500")
+	require.NoError(t, err)
+	require.Equal(t, "www.offchainlabs.com", cl.BaseURL().Hostname())
+	require.Equal(t, "3500", cl.BaseURL().Port())
+}
--- a/api/client/errors.go
+++ b/api/client/errors.go
@@ -0,0 +1,40 @@
+package client
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/pkg/errors"
+)
+
+// ErrMalformedHostname is used to indicate if a host name's format is incorrect.
+var ErrMalformedHostname = errors.New("hostname must include port, separated by one colon, like example.com:3500")
+
+// ErrNotOK is used to indicate when an HTTP request to the API failed with any non-2xx response code.
+// More specific errors may be returned, but an error in reaction to a non-2xx response will always wrap ErrNotOK.
+var ErrNotOK = errors.New("did not receive 2xx response from API")
+
+// ErrNotFound specifically means that a '404 - NOT FOUND' response was received from the API.
+var ErrNotFound = errors.Wrap(ErrNotOK, "recv 404 NotFound response from API")
+
+// ErrInvalidNodeVersion indicates that the /eth/v1/node/version API response format was not recognized.
+var ErrInvalidNodeVersion = errors.New("invalid node version response")
+
+// Non200Err is a function that parses an HTTP response to handle responses that are not 200 with a formatted error.
+func Non200Err(response *http.Response) error {
+	bodyBytes, err := io.ReadAll(response.Body)
+	var body string
+	if err != nil {
+		body = "(Unable to read response body.)"
+	} else {
+		body = "response body:\n" + string(bodyBytes)
+	}
+	msg := fmt.Sprintf("code=%d, url=%s, body=%s", response.StatusCode, response.Request.URL, body)
+	switch response.StatusCode {
+	case 404:
+		return errors.Wrap(ErrNotFound, msg)
+	default:
+		return errors.Wrap(ErrNotOK, msg)
+	}
+}
--- a/api/client/options.go
+++ b/api/client/options.go
@@ -0,0 +1,48 @@
+package client
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+)
+
+// ReqOption is a request functional option.
+type ReqOption func(*http.Request)
+
+// WithSSZEncoding is a request functional option that adds SSZ encoding header.
+func WithSSZEncoding() ReqOption {
+	return func(req *http.Request) {
+		req.Header.Set("Accept", "application/octet-stream")
+	}
+}
+
+// WithAuthorizationToken is a request functional option that adds header for authorization token.
+func WithAuthorizationToken(token string) ReqOption {
+	return func(req *http.Request) {
+		req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
+	}
+}
+
+// ClientOpt is a functional option for the Client type (http.Client wrapper)
+type ClientOpt func(*Client)
+
+// WithTimeout sets the .Timeout attribute of the wrapped http.Client.
+func WithTimeout(timeout time.Duration) ClientOpt {
+	return func(c *Client) {
+		c.hc.Timeout = timeout
+	}
+}
+
+// WithRoundTripper replaces the underlying HTTP's transport with a custom one.
+func WithRoundTripper(t http.RoundTripper) ClientOpt {
+	return func(c *Client) {
+		c.hc.Transport = t
+	}
+}
+
+// WithAuthenticationToken sets an oauth token to be used.
+func WithAuthenticationToken(token string) ClientOpt {
+	return func(c *Client) {
+		c.token = token
+	}
+}
--- a/api/client/validator/BUILD.bazel
+++ b/api/client/validator/BUILD.bazel
@@ -0,0 +1,13 @@
+load("@prysm//tools/go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["client.go"],
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/client/validator",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//api/client:go_default_library",
+        "//validator/rpc/apimiddleware:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+    ],
+)
--- a/api/client/validator/client.go
+++ b/api/client/validator/client.go
@@ -0,0 +1,121 @@
+package validator
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v4/api/client"
+	"github.com/prysmaticlabs/prysm/v4/validator/rpc/apimiddleware"
+)
+
+const (
+	localKeysPath    = "/eth/v1/keystores"
+	remoteKeysPath   = "/eth/v1/remotekeys"
+	feeRecipientPath = "/eth/v1/validator/{pubkey}/feerecipient"
+)
+
+// Client provides a collection of helper methods for calling the Keymanager API endpoints.
+type Client struct {
+	*client.Client
+}
+
+// NewClient returns a new Client that includes functions for REST calls to keymanager APIs.
+func NewClient(host string, opts ...client.ClientOpt) (*Client, error) {
+	c, err := client.NewClient(host, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return &Client{c}, nil
+}
+
+// GetValidatorPubKeys gets the current list of web3signer or the local validator public keys in hex format.
+func (c *Client) GetValidatorPubKeys(ctx context.Context) ([]string, error) {
+	jsonlocal, err := c.GetLocalValidatorKeys(ctx)
+	if err != nil {
+		return nil, err
+	}
+	jsonremote, err := c.GetRemoteValidatorKeys(ctx)
+	if err != nil {
+		return nil, err
+	}
+	if len(jsonlocal.Keystores) == 0 && len(jsonremote.Keystores) == 0 {
+		return nil, errors.New("there are no local keys or remote keys on the validator")
+	}
+
+	hexKeys := make(map[string]bool)
+
+	for index := range jsonlocal.Keystores {
+		hexKeys[jsonlocal.Keystores[index].ValidatingPubkey] = true
+	}
+	for index := range jsonremote.Keystores {
+		hexKeys[jsonremote.Keystores[index].Pubkey] = true
+	}
+	keys := make([]string, 0)
+	for k := range hexKeys {
+		keys = append(keys, k)
+	}
+	return keys, nil
+}
+
+// GetLocalValidatorKeys calls the keymanager APIs for local validator keys
+func (c *Client) GetLocalValidatorKeys(ctx context.Context) (*apimiddleware.ListKeystoresResponseJson, error) {
+	localBytes, err := c.Get(ctx, localKeysPath, client.WithAuthorizationToken(c.Token()))
+	if err != nil {
+		return nil, err
+	}
+	jsonlocal := &apimiddleware.ListKeystoresResponseJson{}
+	if err := json.Unmarshal(localBytes, jsonlocal); err != nil {
+		return nil, errors.Wrap(err, "failed to parse local keystore list")
+	}
+	return jsonlocal, nil
+}
+
+// GetRemoteValidatorKeys calls the keymanager APIs for web3signer validator keys
+func (c *Client) GetRemoteValidatorKeys(ctx context.Context) (*apimiddleware.ListRemoteKeysResponseJson, error) {
+	remoteBytes, err := c.Get(ctx, remoteKeysPath, client.WithAuthorizationToken(c.Token()))
+	if err != nil {
+		if !strings.Contains(err.Error(), "Prysm Wallet is not of type Web3Signer") {
+			return nil, err
+		}
+	}
+	jsonremote := &apimiddleware.ListRemoteKeysResponseJson{}
+	if len(remoteBytes) != 0 {
+		if err := json.Unmarshal(remoteBytes, jsonremote); err != nil {
+			return nil, errors.Wrap(err, "failed to parse remote keystore list")
+		}
+	}
+	return jsonremote, nil
+}
+
+// GetFeeRecipientAddresses takes a list of validators in hex format and returns an equal length list of fee recipients in hex format.
+func (c *Client) GetFeeRecipientAddresses(ctx context.Context, validators []string) ([]string, error) {
+	feeRecipients := make([]string, len(validators))
+	for index, validator := range validators {
+		feejson, err := c.GetFeeRecipientAddress(ctx, validator)
+		if err != nil {
+			return nil, errors.Wrap(err, fmt.Sprintf("keymanager API failed to retrieve fee recipient for validator %s", validators[index]))
+		}
+		if feejson.Data == nil {
+			continue
+		}
+		feeRecipients[index] = feejson.Data.Ethaddress
+	}
+	return feeRecipients, nil
+}
+
+// GetFeeRecipientAddress takes a public key and calls the keymanager API to return its fee recipient.
+func (c *Client) GetFeeRecipientAddress(ctx context.Context, pubkey string) (*apimiddleware.GetFeeRecipientByPubkeyResponseJson, error) {
+	path := strings.Replace(feeRecipientPath, "{pubkey}", pubkey, 1)
+	b, err := c.Get(ctx, path, client.WithAuthorizationToken(c.Token()))
+	if err != nil {
+		return nil, err
+	}
+	feejson := &apimiddleware.GetFeeRecipientByPubkeyResponseJson{}
+	if err := json.Unmarshal(b, feejson); err != nil {
+		return nil, errors.Wrap(err, "failed to parse fee recipient")
+	}
+	return feejson, nil
+}
--- a/api/gateway/BUILD.bazel
+++ b/api/gateway/BUILD.bazel
@@ -8,7 +8,7 @@ go_library(
        "modifiers.go",
        "options.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/v3/api/gateway",
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/gateway",
    visibility = [
        "//beacon-chain:__subpackages__",
        "//validator:__subpackages__",
--- a/api/gateway/apimiddleware/BUILD.bazel
+++ b/api/gateway/apimiddleware/BUILD.bazel
@@ -10,7 +10,7 @@ go_library(
        "process_request.go",
        "structs.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/v3/api/gateway/apimiddleware",
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/gateway/apimiddleware",
    visibility = ["//visibility:public"],
    deps = [
        "//api/grpc:go_default_library",
--- a/api/gateway/apimiddleware/param_handling.go
+++ b/api/gateway/apimiddleware/param_handling.go
@@ -7,7 +7,7 @@ import (
 	"strings"

 	"github.com/gorilla/mux"
-	butil "github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
+	butil "github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
 	"github.com/wealdtech/go-bytesutil"
 )

--- a/api/gateway/apimiddleware/param_handling_test.go
+++ b/api/gateway/apimiddleware/param_handling_test.go
@@ -6,8 +6,8 @@ import (
 	"testing"

 	"github.com/gorilla/mux"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 func TestHandleURLParameters(t *testing.T) {
--- a/api/gateway/apimiddleware/process_request.go
+++ b/api/gateway/apimiddleware/process_request.go
@@ -10,7 +10,7 @@ import (
 	"strings"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/api/grpc"
+	"github.com/prysmaticlabs/prysm/v4/api/grpc"
 )

 // DeserializeRequestBodyIntoContainer deserializes the request's body into an endpoint-specific struct.
--- a/api/gateway/apimiddleware/process_request_test.go
+++ b/api/gateway/apimiddleware/process_request_test.go
@@ -8,9 +8,9 @@ import (
 	"strings"
 	"testing"

-	"github.com/prysmaticlabs/prysm/v3/api/grpc"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/api/grpc"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 	"github.com/sirupsen/logrus/hooks/test"
 )

--- a/api/gateway/gateway.go
+++ b/api/gateway/gateway.go
@@ -13,8 +13,8 @@ import (
 	"github.com/gorilla/mux"
 	gwruntime "github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/api/gateway/apimiddleware"
-	"github.com/prysmaticlabs/prysm/v3/runtime"
+	"github.com/prysmaticlabs/prysm/v4/api/gateway/apimiddleware"
+	"github.com/prysmaticlabs/prysm/v4/runtime"
 	"github.com/rs/cors"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/connectivity"
@@ -70,15 +70,16 @@ type Gateway struct {
 func New(ctx context.Context, opts ...Option) (*Gateway, error) {
 	g := &Gateway{
 		ctx: ctx,
-		cfg: &config{
-			router: mux.NewRouter(),
-		},
+		cfg: &config{},
 	}
 	for _, opt := range opts {
 		if err := opt(g); err != nil {
 			return nil, err
 		}
 	}
+	if g.cfg.router == nil {
+		g.cfg.router = mux.NewRouter()
+	}
 	return g, nil
 }

--- a/api/gateway/gateway_test.go
+++ b/api/gateway/gateway_test.go
@@ -10,10 +10,10 @@ import (
 	"testing"

 	"github.com/gorilla/mux"
-	"github.com/prysmaticlabs/prysm/v3/api/gateway/apimiddleware"
-	"github.com/prysmaticlabs/prysm/v3/cmd/beacon-chain/flags"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/api/gateway/apimiddleware"
+	"github.com/prysmaticlabs/prysm/v4/cmd/beacon-chain/flags"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 	"github.com/urfave/cli/v2"
 )
--- a/api/gateway/options.go
+++ b/api/gateway/options.go
@@ -5,16 +5,11 @@ import (

 	"github.com/gorilla/mux"
 	gwruntime "github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
-	"github.com/prysmaticlabs/prysm/v3/api/gateway/apimiddleware"
+	"github.com/prysmaticlabs/prysm/v4/api/gateway/apimiddleware"
 )

 type Option func(g *Gateway) error

-func (g *Gateway) SetRouter(r *mux.Router) *Gateway {
-	g.cfg.router = r
-	return g
-}
-
 func WithPbHandlers(handlers []*PbMux) Option {
 	return func(g *Gateway) error {
 		g.cfg.pbHandlers = handlers
--- a/api/grpc/BUILD.bazel
+++ b/api/grpc/BUILD.bazel
@@ -6,7 +6,7 @@ go_library(
        "grpcutils.go",
        "parameters.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/v3/api/grpc",
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/grpc",
    visibility = ["//visibility:public"],
    deps = [
        "@com_github_sirupsen_logrus//:go_default_library",
--- a/api/grpc/grpcutils_test.go
+++ b/api/grpc/grpcutils_test.go
@@ -7,8 +7,8 @@ import (
 	"testing"

 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/metadata"
--- a/api/pagination/BUILD.bazel
+++ b/api/pagination/BUILD.bazel
@@ -3,7 +3,7 @@ load("@prysm//tools/go:def.bzl", "go_library", "go_test")
 go_library(
    name = "go_default_library",
    srcs = ["pagination.go"],
-    importpath = "github.com/prysmaticlabs/prysm/v3/api/pagination",
+    importpath = "github.com/prysmaticlabs/prysm/v4/api/pagination",
    visibility = ["//visibility:public"],
    deps = [
        "//config/params:go_default_library",
--- a/api/pagination/pagination.go
+++ b/api/pagination/pagination.go
@@ -6,7 +6,7 @@ import (
 	"strconv"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
 )

 // StartAndEndPage takes in the requested page token, wanted page size, total page size.
--- a/api/pagination/pagination_test.go
+++ b/api/pagination/pagination_test.go
@@ -3,9 +3,9 @@ package pagination_test
 import (
 	"testing"

-	"github.com/prysmaticlabs/prysm/v3/api/pagination"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/api/pagination"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 func TestStartAndEndPage(t *testing.T) {
--- a/async/BUILD.bazel
+++ b/async/BUILD.bazel
@@ -8,7 +8,7 @@ go_library(
        "multilock.go",
        "scatter.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/v3/async",
+    importpath = "github.com/prysmaticlabs/prysm/v4/async",
    visibility = ["//visibility:public"],
    deps = ["@com_github_sirupsen_logrus//:go_default_library"],
 )
--- a/async/abool/BUILD.bazel
+++ b/async/abool/BUILD.bazel
@@ -3,7 +3,7 @@ load("@prysm//tools/go:def.bzl", "go_library", "go_test")
 go_library(
    name = "go_default_library",
    srcs = ["abool.go"],
-    importpath = "github.com/prysmaticlabs/prysm/v3/async/abool",
+    importpath = "github.com/prysmaticlabs/prysm/v4/async/abool",
    visibility = ["//visibility:public"],
 )

--- a/async/benchmark_test.go
+++ b/async/benchmark_test.go
@@ -6,8 +6,8 @@ import (
 	"sync"
 	"testing"

-	"github.com/prysmaticlabs/prysm/v3/async"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/async"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 	log "github.com/sirupsen/logrus"
 )

--- a/async/debounce_test.go
+++ b/async/debounce_test.go
@@ -7,10 +7,10 @@ import (
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/v3/async"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	"github.com/prysmaticlabs/prysm/v4/async"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
 )

 func TestDebounce_NoEvents(t *testing.T) {
--- a/async/event/BUILD.bazel
+++ b/async/event/BUILD.bazel
@@ -6,7 +6,7 @@ go_library(
        "feed.go",
        "subscription.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/v3/async/event",
+    importpath = "github.com/prysmaticlabs/prysm/v4/async/event",
    visibility = ["//visibility:public"],
    deps = ["//time/mclock:go_default_library"],
 )
--- a/async/event/example_feed_test.go
+++ b/async/event/example_feed_test.go
@@ -19,7 +19,7 @@ package event_test
 import (
 	"fmt"

-	"github.com/prysmaticlabs/prysm/v3/async/event"
+	"github.com/prysmaticlabs/prysm/v4/async/event"
 )

 func ExampleFeed_acknowledgedEvents() {
--- a/async/event/example_scope_test.go
+++ b/async/event/example_scope_test.go
@@ -20,7 +20,7 @@ import (
 	"fmt"
 	"sync"

-	"github.com/prysmaticlabs/prysm/v3/async/event"
+	"github.com/prysmaticlabs/prysm/v4/async/event"
 )

 // This example demonstrates how SubscriptionScope can be used to control the lifetime of
--- a/async/event/example_subscription_test.go
+++ b/async/event/example_subscription_test.go
@@ -19,7 +19,7 @@ package event_test
 import (
 	"fmt"

-	"github.com/prysmaticlabs/prysm/v3/async/event"
+	"github.com/prysmaticlabs/prysm/v4/async/event"
 )

 func ExampleNewSubscription() {
--- a/async/event/feed.go
+++ b/async/event/feed.go
@@ -144,6 +144,7 @@ func (f *Feed) Send(value interface{}) (nsent int) {

 	if !f.typecheck(rvalue.Type()) {
 		f.sendLock <- struct{}{}
+		f.mu.Unlock()
 		panic(feedTypeError{op: "Send", got: rvalue.Type(), want: f.etype})
 	}
 	f.mu.Unlock()
--- a/async/event/feed_test.go
+++ b/async/event/feed_test.go
@@ -23,7 +23,7 @@ import (
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
 )

 func TestFeedPanics(t *testing.T) {
@@ -32,6 +32,8 @@ func TestFeedPanics(t *testing.T) {
 		f.Send(2)
 		want := feedTypeError{op: "Send", got: reflect.TypeOf(uint64(0)), want: reflect.TypeOf(0)}
 		assert.NoError(t, checkPanic(want, func() { f.Send(uint64(2)) }))
+		// Validate it doesn't deadlock.
+		assert.NoError(t, checkPanic(want, func() { f.Send(uint64(2)) }))
 	}
 	{
 		var f Feed
--- a/async/event/subscription.go
+++ b/async/event/subscription.go
@@ -21,7 +21,7 @@ import (
 	"sync"
 	"time"

-	"github.com/prysmaticlabs/prysm/v3/time/mclock"
+	"github.com/prysmaticlabs/prysm/v4/time/mclock"
 )

 // waitQuotient is divided against the max backoff time, in order to have N requests based on the full
--- a/async/event/subscription_test.go
+++ b/async/event/subscription_test.go
@@ -23,7 +23,7 @@ import (
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 var errInts = errors.New("error in subscribeInts")
--- a/async/every_test.go
+++ b/async/every_test.go
@@ -6,7 +6,7 @@ import (
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/v3/async"
+	"github.com/prysmaticlabs/prysm/v4/async"
 )

 func TestEveryRuns(t *testing.T) {
--- a/async/scatter.go
+++ b/async/scatter.go
@@ -14,7 +14,7 @@ type WorkerResults struct {

 // Scatter scatters a computation across multiple goroutines.
 // This breaks the task in to a number of chunks and executes those chunks in parallel with the function provided.
-// Results returned are collected and presented a a set of WorkerResults, which can be reassembled by the calling function.
+// Results returned are collected and presented as a set of WorkerResults, which can be reassembled by the calling function.
 // Any error that occurs in the workers will be passed back to the calling function.
 func Scatter(inputLen int, sFunc func(int, int, *sync.RWMutex) (interface{}, error)) ([]*WorkerResults, error) {
 	if inputLen <= 0 {
--- a/async/scatter_test.go
+++ b/async/scatter_test.go
@@ -5,9 +5,9 @@ import (
 	"sync"
 	"testing"

-	"github.com/prysmaticlabs/prysm/v3/async"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/async"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 func TestDouble(t *testing.T) {
--- a/beacon-chain/blockchain/BUILD.bazel
+++ b/beacon-chain/blockchain/BUILD.bazel
@@ -4,8 +4,10 @@ go_library(
    name = "go_default_library",
    srcs = [
        "chain_info.go",
+        "chain_info_forkchoice.go",
        "error.go",
        "execution_engine.go",
+        "forkchoice_update_execution.go",
        "head.go",
        "head_sync_committee_info.go",
        "init_sync_process_block.go",
@@ -21,10 +23,9 @@ go_library(
        "receive_attestation.go",
        "receive_block.go",
        "service.go",
-        "state_balance_cache.go",
        "weak_subjectivity_checks.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/v3/beacon-chain/blockchain",
+    importpath = "github.com/prysmaticlabs/prysm/v4/beacon-chain/blockchain",
    visibility = [
        "//beacon-chain:__subpackages__",
        "//cmd/beacon-chain:__subpackages__",
@@ -57,11 +58,13 @@ go_library(
        "//beacon-chain/operations/slashings:go_default_library",
        "//beacon-chain/operations/voluntaryexits:go_default_library",
        "//beacon-chain/p2p:go_default_library",
+        "//beacon-chain/startup:go_default_library",
        "//beacon-chain/state:go_default_library",
        "//beacon-chain/state/stategen:go_default_library",
        "//config/features:go_default_library",
        "//config/fieldparams:go_default_library",
        "//config/params:go_default_library",
+        "//consensus-types:go_default_library",
        "//consensus-types/blocks:go_default_library",
        "//consensus-types/interfaces:go_default_library",
        "//consensus-types/payload-attribute:go_default_library",
@@ -104,6 +107,7 @@ go_test(
        "chain_info_test.go",
        "checktags_test.go",
        "execution_engine_test.go",
+        "forkchoice_update_execution_test.go",
        "head_sync_committee_info_test.go",
        "head_test.go",
        "init_test.go",
@@ -116,6 +120,7 @@ go_test(
        "receive_attestation_test.go",
        "receive_block_test.go",
        "service_test.go",
+        "setup_test.go",
        "weak_subjectivity_checks_test.go",
    ],
    embed = [":go_default_library"],
@@ -165,6 +170,7 @@ go_test(
        "mock_test.go",
        "receive_block_test.go",
        "service_norace_test.go",
+        "setup_test.go",
    ],
    embed = [":go_default_library"],
    gc_goopts = [
--- a/beacon-chain/blockchain/chain_info.go
+++ b/beacon-chain/blockchain/chain_info.go
@@ -6,17 +6,18 @@ import (
 	"time"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	fieldparams "github.com/prysmaticlabs/prysm/v3/config/fieldparams"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
+	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"
+	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
+	"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"
+	ethpbv1 "github.com/prysmaticlabs/prysm/v4/proto/eth/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"go.opencensus.io/trace"
 )

@@ -28,12 +29,25 @@ type ChainInfoFetcher interface {
 	CanonicalFetcher
 	ForkFetcher
 	HeadDomainFetcher
+	ForkchoiceFetcher
 }

-// HeadUpdater defines a common interface for methods in blockchain service
-// which allow to update the head info
-type HeadUpdater interface {
-	UpdateHead(context.Context) error
+// ForkchoiceFetcher defines a common interface for methods that access directly
+// forkchoice information. These typically require a lock and external callers
+// are requested to call methods within this blockchain package that takes care
+// of locking forkchoice
+type ForkchoiceFetcher interface {
+	Ancestor(context.Context, []byte, primitives.Slot) ([]byte, error)
+	CachedHeadRoot() [32]byte
+	GetProposerHead() [32]byte
+	SetForkChoiceGenesisTime(uint64)
+	UpdateHead(context.Context, primitives.Slot)
+	HighestReceivedBlockSlot() primitives.Slot
+	ReceivedBlocksLastEpoch() (uint64, error)
+	InsertNode(context.Context, state.BeaconState, [32]byte) error
+	ForkChoiceDump(context.Context) (*ethpbv1.ForkChoiceDump, error)
+	NewSlot(context.Context, primitives.Slot) error
+	ProposerBoost() [32]byte
 }

 // TimeFetcher retrieves the Ethereum consensus data that's related to time.
@@ -52,8 +66,9 @@ type GenesisFetcher interface {
 type HeadFetcher interface {
 	HeadSlot() primitives.Slot
 	HeadRoot(ctx context.Context) ([]byte, error)
-	HeadBlock(ctx context.Context) (interfaces.SignedBeaconBlock, error)
+	HeadBlock(ctx context.Context) (interfaces.ReadOnlySignedBeaconBlock, error)
 	HeadState(ctx context.Context) (state.BeaconState, error)
+	HeadStateReadOnly(ctx context.Context) (state.ReadOnlyBeaconState, error)
 	HeadValidatorsIndices(ctx context.Context, epoch primitives.Epoch) ([]primitives.ValidatorIndex, error)
 	HeadGenesisValidatorsRoot() [32]byte
 	HeadETH1Data() *ethpb.Eth1Data
@@ -66,12 +81,17 @@ type HeadFetcher interface {

 // ForkFetcher retrieves the current fork information of the Ethereum beacon chain.
 type ForkFetcher interface {
-	ForkChoicer() forkchoice.ForkChoicer
 	CurrentFork() *ethpb.Fork
 	GenesisFetcher
 	TimeFetcher
 }

+// TemporalOracle is like ForkFetcher minus CurrentFork()
+type TemporalOracle interface {
+	GenesisFetcher
+	TimeFetcher
+}
+
 // CanonicalFetcher retrieves the current chain's canonical information.
 type CanonicalFetcher interface {
 	IsCanonical(ctx context.Context, blockRoot [32]byte) (bool, error)
@@ -83,7 +103,9 @@ type FinalizationFetcher interface {
 	FinalizedCheckpt() *ethpb.Checkpoint
 	CurrentJustifiedCheckpt() *ethpb.Checkpoint
 	PreviousJustifiedCheckpt() *ethpb.Checkpoint
-	VerifyFinalizedBlkDescendant(ctx context.Context, blockRoot [32]byte) error
+	UnrealizedJustifiedPayloadBlockHash() [32]byte
+	FinalizedBlockHash() [32]byte
+	InForkchoice([32]byte) bool
 	IsFinalized(ctx context.Context, blockRoot [32]byte) bool
 }

@@ -95,25 +117,25 @@ type OptimisticModeFetcher interface {

 // FinalizedCheckpt returns the latest finalized checkpoint from chain store.
 func (s *Service) FinalizedCheckpt() *ethpb.Checkpoint {
-	cp := s.ForkChoicer().FinalizedCheckpoint()
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	cp := s.cfg.ForkChoiceStore.FinalizedCheckpoint()
 	return &ethpb.Checkpoint{Epoch: cp.Epoch, Root: bytesutil.SafeCopyBytes(cp.Root[:])}
 }

 // PreviousJustifiedCheckpt returns the current justified checkpoint from chain store.
 func (s *Service) PreviousJustifiedCheckpt() *ethpb.Checkpoint {
-	cp := s.ForkChoicer().PreviousJustifiedCheckpoint()
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	cp := s.cfg.ForkChoiceStore.PreviousJustifiedCheckpoint()
 	return &ethpb.Checkpoint{Epoch: cp.Epoch, Root: bytesutil.SafeCopyBytes(cp.Root[:])}
 }

 // CurrentJustifiedCheckpt returns the current justified checkpoint from chain store.
 func (s *Service) CurrentJustifiedCheckpt() *ethpb.Checkpoint {
-	cp := s.ForkChoicer().JustifiedCheckpoint()
-	return &ethpb.Checkpoint{Epoch: cp.Epoch, Root: bytesutil.SafeCopyBytes(cp.Root[:])}
-}
-
-// BestJustifiedCheckpt returns the best justified checkpoint from store.
-func (s *Service) BestJustifiedCheckpt() *ethpb.Checkpoint {
-	cp := s.ForkChoicer().BestJustifiedCheckpoint()
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	cp := s.cfg.ForkChoiceStore.JustifiedCheckpoint()
 	return &ethpb.Checkpoint{Epoch: cp.Epoch, Root: bytesutil.SafeCopyBytes(cp.Root[:])}
 }

@@ -157,7 +179,7 @@ func (s *Service) HeadRoot(ctx context.Context) ([]byte, error) {
 // HeadBlock returns the head block of the chain.
 // If the head is nil from service struct,
 // it will attempt to get the head block from DB.
-func (s *Service) HeadBlock(ctx context.Context) (interfaces.SignedBeaconBlock, error) {
+func (s *Service) HeadBlock(ctx context.Context) (interfaces.ReadOnlySignedBeaconBlock, error) {
 	s.headLock.RLock()
 	defer s.headLock.RUnlock()

@@ -187,6 +209,28 @@ func (s *Service) HeadState(ctx context.Context) (state.BeaconState, error) {
 	return s.cfg.StateGen.StateByRoot(ctx, s.headRoot())
 }

+// HeadStateReadOnly returns the read only head state of the chain.
+// If the head is nil from service struct, it will attempt to get the
+// head state from DB. Any callers of this method MUST only use the
+// state instance to read fields from the state. Any type assertions back
+// to the concrete type and subsequent use of it could lead to corruption
+// of the state.
+func (s *Service) HeadStateReadOnly(ctx context.Context) (state.ReadOnlyBeaconState, error) {
+	ctx, span := trace.StartSpan(ctx, "blockChain.HeadStateReadOnly")
+	defer span.End()
+	s.headLock.RLock()
+	defer s.headLock.RUnlock()
+
+	ok := s.hasHeadState()
+	span.AddAttributes(trace.BoolAttribute("cache_hit", ok))
+
+	if ok {
+		return s.headStateReadOnly(ctx), nil
+	}
+
+	return s.cfg.StateGen.StateByRoot(ctx, s.headRoot())
+}
+
 // HeadValidatorsIndices returns a list of active validator indices from the head view of a given epoch.
 func (s *Service) HeadValidatorsIndices(ctx context.Context, epoch primitives.Epoch) ([]primitives.ValidatorIndex, error) {
 	s.headLock.RLock()
@@ -254,6 +298,8 @@ func (s *Service) CurrentFork() *ethpb.Fork {

 // IsCanonical returns true if the input block root is part of the canonical chain.
 func (s *Service) IsCanonical(ctx context.Context, blockRoot [32]byte) (bool, error) {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
 	// If the block has not been finalized, check fork choice store to see if the block is canonical
 	if s.cfg.ForkChoiceStore.HasNode(blockRoot) {
 		return s.cfg.ForkChoiceStore.IsCanonical(blockRoot), nil
@@ -263,12 +309,6 @@ func (s *Service) IsCanonical(ctx context.Context, blockRoot [32]byte) (bool, er
 	return s.cfg.BeaconDB.IsFinalizedBlock(ctx, blockRoot), nil
 }

-// ChainHeads returns all possible chain heads (leaves of fork choice tree).
-// Heads roots and heads slots are returned.
-func (s *Service) ChainHeads() ([][32]byte, []primitives.Slot) {
-	return s.cfg.ForkChoiceStore.Tips()
-}
-
 // HeadPublicKeyToValidatorIndex returns the validator index of the `pubkey` in current head state.
 func (s *Service) HeadPublicKeyToValidatorIndex(pubKey [fieldparams.BLSPubkeyLength]byte) (primitives.ValidatorIndex, bool) {
 	s.headLock.RLock()
@@ -293,13 +333,8 @@ func (s *Service) HeadValidatorIndexToPublicKey(_ context.Context, index primiti
 	return v.PublicKey(), nil
 }

-// ForkChoicer returns the forkchoice interface.
-func (s *Service) ForkChoicer() forkchoice.ForkChoicer {
-	return s.cfg.ForkChoiceStore
-}
-
 // IsOptimistic returns true if the current head is optimistic.
-func (s *Service) IsOptimistic(ctx context.Context) (bool, error) {
+func (s *Service) IsOptimistic(_ context.Context) (bool, error) {
 	if slots.ToEpoch(s.CurrentSlot()) < params.BeaconConfig().BellatrixForkEpoch {
 		return false, nil
 	}
@@ -307,9 +342,8 @@ func (s *Service) IsOptimistic(ctx context.Context) (bool, error) {
 	headRoot := s.head.root
 	s.headLock.RUnlock()

-	if s.cfg.ForkChoiceStore.AllTipsAreInvalid() {
-		return true, nil
-	}
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
 	optimistic, err := s.cfg.ForkChoiceStore.IsOptimistic(headRoot)
 	if err == nil {
 		return optimistic, nil
@@ -325,21 +359,42 @@ func (s *Service) IsOptimistic(ctx context.Context) (bool, error) {
 // IsFinalized returns true if the input root is finalized.
 // It first checks latest finalized root then checks finalized root index in DB.
 func (s *Service) IsFinalized(ctx context.Context, root [32]byte) bool {
-	if s.ForkChoicer().FinalizedCheckpoint().Root == root {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	if s.cfg.ForkChoiceStore.FinalizedCheckpoint().Root == root {
 		return true
 	}
 	// If node exists in our store, then it is not
 	// finalized.
-	if s.ForkChoicer().HasNode(root) {
+	if s.cfg.ForkChoiceStore.HasNode(root) {
 		return false
 	}
 	return s.cfg.BeaconDB.IsFinalizedBlock(ctx, root)
 }

+// InForkchoice returns true if the given root is found in forkchoice
+// This in particular means that the blockroot is a descendant of the
+// finalized checkpoint
+func (s *Service) InForkchoice(root [32]byte) bool {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.HasNode(root)
+}
+
+// IsViableForkCheckpoint returns whether the given checkpoint is a checkpoint in any
+// chain known to forkchoice
+func (s *Service) IsViableForCheckpoint(cp *forkchoicetypes.Checkpoint) (bool, error) {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.IsViableForCheckpoint(cp)
+}
+
 // IsOptimisticForRoot takes the root as argument instead of the current head
 // and returns true if it is optimistic.
 func (s *Service) IsOptimisticForRoot(ctx context.Context, root [32]byte) (bool, error) {
+	s.cfg.ForkChoiceStore.RLock()
 	optimistic, err := s.cfg.ForkChoiceStore.IsOptimistic(root)
+	s.cfg.ForkChoiceStore.RUnlock()
 	if err == nil {
 		return optimistic, nil
 	}
@@ -362,7 +417,10 @@ func (s *Service) IsOptimisticForRoot(ctx context.Context, root [32]byte) (bool,
 	}

 	if ss == nil {
-		return true, errInvalidNilSummary
+		ss, err = s.recoverStateSummary(ctx, root)
+		if err != nil {
+			return true, err
+		}
 	}
 	validatedCheckpoint, err := s.cfg.BeaconDB.LastValidatedCheckpoint(ctx)
 	if err != nil {
@@ -388,7 +446,10 @@ func (s *Service) IsOptimisticForRoot(ctx context.Context, root [32]byte) (bool,
 		return false, err
 	}
 	if lastValidated == nil {
-		return false, errInvalidNilSummary
+		lastValidated, err = s.recoverStateSummary(ctx, root)
+		if err != nil {
+			return false, err
+		}
 	}

 	if ss.Slot > lastValidated.Slot {
@@ -397,12 +458,57 @@ func (s *Service) IsOptimisticForRoot(ctx context.Context, root [32]byte) (bool,
 	return !isCanonical, nil
 }

+// Ancestor returns the block root of an ancestry block from the input block root.
+//
+// Spec pseudocode definition:
+//
+//	def get_ancestor(store: Store, root: Root, slot: Slot) -> Root:
+//	 block = store.blocks[root]
+//	 if block.slot > slot:
+//	     return get_ancestor(store, block.parent_root, slot)
+//	 elif block.slot == slot:
+//	     return root
+//	 else:
+//	     # root is older than queried slot, thus a skip slot. Return most recent root prior to slot
+//	     return root
+func (s *Service) Ancestor(ctx context.Context, root []byte, slot primitives.Slot) ([]byte, error) {
+	ctx, span := trace.StartSpan(ctx, "blockChain.ancestor")
+	defer span.End()
+
+	r := bytesutil.ToBytes32(root)
+	// Get ancestor root from fork choice store instead of recursively looking up blocks in DB.
+	// This is most optimal outcome.
+	s.cfg.ForkChoiceStore.RLock()
+	ar, err := s.cfg.ForkChoiceStore.AncestorRoot(ctx, r, slot)
+	s.cfg.ForkChoiceStore.RUnlock()
+	if err != nil {
+		// Try getting ancestor root from DB when failed to retrieve from fork choice store.
+		// This is the second line of defense for retrieving ancestor root.
+		ar, err = s.ancestorByDB(ctx, r, slot)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return ar[:], nil
+}
+
 // SetGenesisTime sets the genesis time of beacon chain.
 func (s *Service) SetGenesisTime(t time.Time) {
 	s.genesisTime = t
 }

-// ForkChoiceStore returns the fork choice store in the service.
-func (s *Service) ForkChoiceStore() forkchoice.ForkChoicer {
-	return s.cfg.ForkChoiceStore
+func (s *Service) recoverStateSummary(ctx context.Context, blockRoot [32]byte) (*ethpb.StateSummary, error) {
+	if s.cfg.BeaconDB.HasBlock(ctx, blockRoot) {
+		b, err := s.cfg.BeaconDB.Block(ctx, blockRoot)
+		if err != nil {
+			return nil, err
+		}
+		summary := &ethpb.StateSummary{Slot: b.Block().Slot(), Root: blockRoot[:]}
+		if err := s.cfg.BeaconDB.SaveStateSummary(ctx, summary); err != nil {
+			return nil, err
+		}
+		return summary, nil
+	}
+	return nil, errBlockDoesNotExist
 }
--- a/beacon-chain/blockchain/chain_info_forkchoice.go
+++ b/beacon-chain/blockchain/chain_info_forkchoice.go
@@ -0,0 +1,94 @@
+package blockchain
+
+import (
+	"context"
+
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	ethpbv1 "github.com/prysmaticlabs/prysm/v4/proto/eth/v1"
+)
+
+// CachedHeadRoot returns the corresponding value from Forkchoice
+func (s *Service) CachedHeadRoot() [32]byte {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.CachedHeadRoot()
+}
+
+// GetProposerHead returns the corresponding value from forkchoice
+func (s *Service) GetProposerHead() [32]byte {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.GetProposerHead()
+}
+
+// SetForkChoiceGenesisTime sets the genesis time in Forkchoice
+func (s *Service) SetForkChoiceGenesisTime(timestamp uint64) {
+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
+	s.cfg.ForkChoiceStore.SetGenesisTime(timestamp)
+}
+
+// HighestReceivedBlockSlot returns the corresponding value from forkchoice
+func (s *Service) HighestReceivedBlockSlot() primitives.Slot {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.HighestReceivedBlockSlot()
+}
+
+// ReceivedBlocksLastEpoch returns the corresponding value from forkchoice
+func (s *Service) ReceivedBlocksLastEpoch() (uint64, error) {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.ReceivedBlocksLastEpoch()
+}
+
+// InsertNode is a wrapper for node insertion which is self locked
+func (s *Service) InsertNode(ctx context.Context, st state.BeaconState, root [32]byte) error {
+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
+	return s.cfg.ForkChoiceStore.InsertNode(ctx, st, root)
+}
+
+// ForkChoiceDump returns the corresponding value from forkchoice
+func (s *Service) ForkChoiceDump(ctx context.Context) (*ethpbv1.ForkChoiceDump, error) {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.ForkChoiceDump(ctx)
+}
+
+// NewSlot returns the corresponding value from forkchoice
+func (s *Service) NewSlot(ctx context.Context, slot primitives.Slot) error {
+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
+	return s.cfg.ForkChoiceStore.NewSlot(ctx, slot)
+}
+
+// ProposerBoost wraps the corresponding method from forkchoice
+func (s *Service) ProposerBoost() [32]byte {
+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
+	return s.cfg.ForkChoiceStore.ProposerBoost()
+}
+
+// ChainHeads returns all possible chain heads (leaves of fork choice tree).
+// Heads roots and heads slots are returned.
+func (s *Service) ChainHeads() ([][32]byte, []primitives.Slot) {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.Tips()
+}
+
+// UnrealizedJustifiedPayloadBlockHash returns unrealized justified payload block hash from forkchoice.
+func (s *Service) UnrealizedJustifiedPayloadBlockHash() [32]byte {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.UnrealizedJustifiedPayloadBlockHash()
+}
+
+// FinalizedBlockHash returns finalized payload block hash from forkchoice.
+func (s *Service) FinalizedBlockHash() [32]byte {
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
+	return s.cfg.ForkChoiceStore.FinalizedPayloadBlockHash()
+}
--- a/beacon-chain/blockchain/chain_info_norace_test.go
+++ b/beacon-chain/blockchain/chain_info_norace_test.go
@@ -4,14 +4,14 @@ import (
 	"context"
 	"testing"

-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/doubly-linked-tree"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state/stategen"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"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"
 )

 func TestHeadSlot_DataRace(t *testing.T) {
--- a/beacon-chain/blockchain/chain_info_test.go
+++ b/beacon-chain/blockchain/chain_info_test.go
@@ -5,22 +5,21 @@ import (
 	"testing"
 	"time"

-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	forkchoicetypes "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/types"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	state_native "github.com/prysmaticlabs/prysm/v3/beacon-chain/state/state-native"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	fieldparams "github.com/prysmaticlabs/prysm/v3/config/fieldparams"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	enginev1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
+	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"
+	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"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	enginev1 "github.com/prysmaticlabs/prysm/v4/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
 	"google.golang.org/protobuf/proto"
 )

@@ -71,23 +70,9 @@ func TestHeadRoot_Nil(t *testing.T) {
 	assert.DeepEqual(t, params.BeaconConfig().ZeroHash[:], headRoot, "Incorrect pre chain start value")
 }

-func TestService_ForkChoiceStore(t *testing.T) {
-	c := &Service{cfg: &config{ForkChoiceStore: doublylinkedtree.New()}}
-	p := c.ForkChoiceStore()
-	require.Equal(t, primitives.Epoch(0), p.FinalizedCheckpoint().Epoch)
-}
-
 func TestFinalizedCheckpt_GenesisRootOk(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithForkChoiceStore(fcs),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx, fcs := tr.ctx, tr.fcs

 	gs, _ := util.DeterministicGenesisState(t, 32)
 	require.NoError(t, service.saveGenesisData(ctx, gs))
@@ -96,53 +81,73 @@ func TestFinalizedCheckpt_GenesisRootOk(t *testing.T) {
 	cp = service.CurrentJustifiedCheckpt()
 	assert.DeepEqual(t, [32]byte{}, bytesutil.ToBytes32(cp.Root))
 	// check that forkchoice has the right genesis root as the node root
-	root, err := fcs.Head(ctx, []uint64{})
+	root, err := fcs.Head(ctx)
 	require.NoError(t, err)
 	require.Equal(t, service.originBlockRoot, root)

 }

 func TestCurrentJustifiedCheckpt_CanRetrieve(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithForkChoiceStore(fcs),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

-	cp := &forkchoicetypes.Checkpoint{Epoch: 6, Root: [32]byte{'j'}}
-	require.NoError(t, fcs.UpdateJustifiedCheckpoint(cp))
+	jroot := [32]byte{'j'}
+	cp := &forkchoicetypes.Checkpoint{Epoch: 6, Root: jroot}
+	bState, _ := util.DeterministicGenesisState(t, 10)
+	require.NoError(t, beaconDB.SaveState(ctx, bState, jroot))
+
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, cp))
 	jp := service.CurrentJustifiedCheckpt()
 	assert.Equal(t, cp.Epoch, jp.Epoch, "Unexpected justified epoch")
 	require.Equal(t, cp.Root, bytesutil.ToBytes32(jp.Root))
 }

+func TestFinalizedBlockHash(t *testing.T) {
+	service, tr := minimalTestService(t)
+	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs
+
+	r := [32]byte{'f'}
+	cp := &forkchoicetypes.Checkpoint{Epoch: 6, Root: r}
+	bState, _ := util.DeterministicGenesisState(t, 10)
+	require.NoError(t, beaconDB.SaveState(ctx, bState, r))
+
+	require.NoError(t, fcs.UpdateFinalizedCheckpoint(cp))
+	h := service.FinalizedBlockHash()
+	require.Equal(t, params.BeaconConfig().ZeroHash, h)
+	require.Equal(t, r, fcs.FinalizedCheckpoint().Root)
+}
+
+func TestUnrealizedJustifiedBlockHash(t *testing.T) {
+	ctx := context.Background()
+	service := &Service{cfg: &config{ForkChoiceStore: doublylinkedtree.New()}}
+	ojc := &ethpb.Checkpoint{Root: []byte{'j'}}
+	ofc := &ethpb.Checkpoint{Root: []byte{'f'}}
+	st, blkRoot, err := prepareForkchoiceState(ctx, 0, [32]byte{}, [32]byte{}, params.BeaconConfig().ZeroHash, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))
+	service.cfg.ForkChoiceStore.SetBalancesByRooter(func(_ context.Context, _ [32]byte) ([]uint64, error) { return []uint64{}, nil })
+	require.NoError(t, service.cfg.ForkChoiceStore.UpdateJustifiedCheckpoint(ctx, &forkchoicetypes.Checkpoint{Epoch: 6, Root: [32]byte{'j'}}))
+
+	h := service.UnrealizedJustifiedPayloadBlockHash()
+	require.Equal(t, params.BeaconConfig().ZeroHash, h)
+	require.Equal(t, [32]byte{'j'}, service.cfg.ForkChoiceStore.JustifiedCheckpoint().Root)
+}
+
 func TestHeadSlot_CanRetrieve(t *testing.T) {
 	c := &Service{}
 	s, err := state_native.InitializeFromProtoPhase0(&ethpb.BeaconState{})
 	require.NoError(t, err)
 	b, err := blocks.NewSignedBeaconBlock(util.NewBeaconBlock())
 	require.NoError(t, err)
-	b.Block().SetSlot(100)
+	b.SetSlot(100)
 	c.head = &head{block: b, state: s}
 	assert.Equal(t, primitives.Slot(100), c.HeadSlot())
 }

 func TestHeadRoot_CanRetrieve(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithForkChoiceStore(fcs),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx
+
 	gs, _ := util.DeterministicGenesisState(t, 32)
 	require.NoError(t, service.saveGenesisData(ctx, gs))

@@ -152,16 +157,8 @@ func TestHeadRoot_CanRetrieve(t *testing.T) {
 }

 func TestHeadRoot_UseDB(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithForkChoiceStore(fcs),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx, beaconDB := tr.ctx, tr.db

 	service.head = &head{root: params.BeaconConfig().ZeroHash}
 	b := util.NewBeaconBlock()
@@ -480,15 +477,10 @@ func TestService_IsOptimisticForRoot_DB(t *testing.T) {
 	validatedCheckpoint := &ethpb.Checkpoint{Root: br[:]}
 	require.NoError(t, beaconDB.SaveLastValidatedCheckpoint(ctx, validatedCheckpoint))

-	_, err = c.IsOptimisticForRoot(ctx, optimisticRoot)
-	require.ErrorContains(t, "nil summary returned from the DB", err)
-
-	require.NoError(t, beaconDB.SaveStateSummary(context.Background(), &ethpb.StateSummary{Root: optimisticRoot[:], Slot: 11}))
 	optimistic, err := c.IsOptimisticForRoot(ctx, optimisticRoot)
 	require.NoError(t, err)
 	require.Equal(t, true, optimistic)

-	require.NoError(t, beaconDB.SaveStateSummary(context.Background(), &ethpb.StateSummary{Root: validatedRoot[:], Slot: 9}))
 	cp := &ethpb.Checkpoint{
 		Epoch: 1,
 		Root:  validatedRoot[:],
@@ -550,12 +542,31 @@ func TestService_IsOptimisticForRoot_DB_non_canonical(t *testing.T) {

 }

+func TestService_IsOptimisticForRoot_StateSummaryRecovered(t *testing.T) {
+	beaconDB := testDB.SetupDB(t)
+	ctx := context.Background()
+	c := &Service{cfg: &config{BeaconDB: beaconDB, ForkChoiceStore: doublylinkedtree.New()}, head: &head{root: [32]byte{'b'}}}
+	c.head = &head{root: params.BeaconConfig().ZeroHash}
+	b := util.NewBeaconBlock()
+	b.Block.Slot = 10
+	br, err := b.Block.HashTreeRoot()
+	require.NoError(t, err)
+	util.SaveBlock(t, context.Background(), beaconDB, b)
+	_, err = c.IsOptimisticForRoot(ctx, br)
+	assert.NoError(t, err)
+	summ, err := beaconDB.StateSummary(ctx, br)
+	assert.NoError(t, err)
+	assert.NotNil(t, summ)
+	assert.Equal(t, 10, int(summ.Slot))
+	assert.DeepEqual(t, br[:], summ.Root)
+}
+
 func TestService_IsFinalized(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	ctx := context.Background()
 	c := &Service{cfg: &config{BeaconDB: beaconDB, ForkChoiceStore: doublylinkedtree.New()}}
 	r1 := [32]byte{'a'}
-	require.NoError(t, c.ForkChoiceStore().UpdateFinalizedCheckpoint(&forkchoicetypes.Checkpoint{
+	require.NoError(t, c.cfg.ForkChoiceStore.UpdateFinalizedCheckpoint(&forkchoicetypes.Checkpoint{
 		Root: r1,
 	}))
 	b := util.NewBeaconBlock()
--- a/beacon-chain/blockchain/error.go
+++ b/beacon-chain/blockchain/error.go
@@ -15,20 +15,21 @@ var (
 	errNilFinalizedCheckpoint = errors.New("nil finalized checkpoint returned from state")
 	// errNilJustifiedCheckpoint is returned when a nil justified checkpt is returned from a state.
 	errNilJustifiedCheckpoint = errors.New("nil justified checkpoint returned from state")
-	// errInvalidNilSummary is returned when a nil summary is returned from the DB.
-	errInvalidNilSummary = errors.New("nil summary returned from the DB")
+	// errBlockDoesNotExist is returned when a block does not exist for a particular state summary.
+	errBlockDoesNotExist = errors.New("could not find block in DB")
 	// errWrongBlockCount is returned when the wrong number of blocks or block roots is used
 	errWrongBlockCount = errors.New("wrong number of blocks or block roots")
 	// errBlockNotFoundInCacheOrDB is returned when a block is not found in the cache or DB.
 	errBlockNotFoundInCacheOrDB = errors.New("block not found in cache or db")
-	// errNilStateFromStategen is returned when a nil state is returned from the state generator.
-	errNilStateFromStategen = errors.New("justified state can't be nil")
 	// errWSBlockNotFound is returned when a block is not found in the WS cache or DB.
 	errWSBlockNotFound = errors.New("weak subjectivity root not found in db")
 	// errWSBlockNotFoundInEpoch is returned when a block is not found in the WS cache or DB within epoch.
 	errWSBlockNotFoundInEpoch = errors.New("weak subjectivity root not found in db within epoch")
-	// errNotDescendantOfFinalized is returned when a block is not a descendant of the finalized checkpoint
-	errNotDescendantOfFinalized = invalidBlock{error: errors.New("not descendant of finalized checkpoint")}
+	// ErrNotDescendantOfFinalized is returned when a block is not a descendant of the finalized checkpoint
+	ErrNotDescendantOfFinalized = invalidBlock{error: errors.New("not descendant of finalized checkpoint")}
+	// 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")
 )

 // An invalid block is the block that fails state transition based on the core protocol rules.
--- a/beacon-chain/blockchain/error_test.go
+++ b/beacon-chain/blockchain/error_test.go
@@ -4,7 +4,7 @@ import (
 	"testing"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 )

 func TestIsInvalidBlock(t *testing.T) {
--- a/beacon-chain/blockchain/execution_engine.go
+++ b/beacon-chain/blockchain/execution_engine.go
@@ -5,22 +5,23 @@ import (
 	"fmt"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/blocks"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/time"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/transition"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/db/kv"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/execution"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	consensusblocks "github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	payloadattribute "github.com/prysmaticlabs/prysm/v3/consensus-types/payload-attribute"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	enginev1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"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"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	consensusblocks "github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"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/encoding/bytesutil"
+	enginev1 "github.com/prysmaticlabs/prysm/v4/proto/engine/v1"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )
@@ -31,7 +32,7 @@ var defaultLatestValidHash = bytesutil.PadTo([]byte{0xff}, 32)
 type notifyForkchoiceUpdateArg struct {
 	headState state.BeaconState
 	headRoot  [32]byte
-	headBlock interfaces.BeaconBlock
+	headBlock interfaces.ReadOnlyBeaconBlock
 }

 // notifyForkchoiceUpdate signals execution engine the fork choice updates. Execution engine should:
@@ -60,8 +61,8 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkcho
 		log.WithError(err).Error("Could not get execution payload for head block")
 		return nil, nil
 	}
-	finalizedHash := s.ForkChoicer().FinalizedPayloadBlockHash()
-	justifiedHash := s.ForkChoicer().JustifiedPayloadBlockHash()
+	finalizedHash := s.cfg.ForkChoiceStore.FinalizedPayloadBlockHash()
+	justifiedHash := s.cfg.ForkChoiceStore.UnrealizedJustifiedPayloadBlockHash()
 	fcs := &enginev1.ForkchoiceState{
 		HeadBlockHash:      headPayload.BlockHash(),
 		SafeBlockHash:      justifiedHash[:],
@@ -69,7 +70,7 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkcho
 	}

 	nextSlot := s.CurrentSlot() + 1 // Cache payload ID for next slot proposer.
-	hasAttr, attr, proposerId := s.getPayloadAttribute(ctx, arg.headState, nextSlot)
+	hasAttr, attr, proposerId := s.getPayloadAttribute(ctx, arg.headState, nextSlot, arg.headRoot[:])

 	payloadID, lastValidHash, err := s.cfg.ExecutionEngineCaller.ForkchoiceUpdated(ctx, fcs, attr)
 	if err != nil {
@@ -88,7 +89,7 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkcho
 			if len(lastValidHash) == 0 {
 				lastValidHash = defaultLatestValidHash
 			}
-			invalidRoots, err := s.ForkChoicer().SetOptimisticToInvalid(ctx, headRoot, headBlk.ParentRoot(), bytesutil.ToBytes32(lastValidHash))
+			invalidRoots, err := s.cfg.ForkChoiceStore.SetOptimisticToInvalid(ctx, headRoot, headBlk.ParentRoot(), bytesutil.ToBytes32(lastValidHash))
 			if err != nil {
 				log.WithError(err).Error("Could not set head root to invalid")
 				return nil, nil
@@ -98,7 +99,7 @@ func (s *Service) notifyForkchoiceUpdate(ctx context.Context, arg *notifyForkcho
 				return nil, nil
 			}

-			r, err := s.cfg.ForkChoiceStore.Head(ctx, s.justifiedBalances.balances)
+			r, err := s.cfg.ForkChoiceStore.Head(ctx)
 			if err != nil {
 				log.WithFields(logrus.Fields{
 					"slot":                 headBlk.Slot(),
@@ -182,7 +183,7 @@ func (s *Service) getPayloadHash(ctx context.Context, root []byte) ([32]byte, er
 // notifyNewPayload signals execution engine on a new payload.
 // It returns true if the EL has returned VALID for the block
 func (s *Service) notifyNewPayload(ctx context.Context, postStateVersion int,
-	postStateHeader interfaces.ExecutionData, blk interfaces.SignedBeaconBlock) (bool, error) {
+	postStateHeader interfaces.ExecutionData, blk interfaces.ReadOnlySignedBeaconBlock) (bool, error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.notifyNewPayload")
 	defer span.End()

@@ -206,7 +207,18 @@ func (s *Service) notifyNewPayload(ctx context.Context, postStateVersion int,
 	if err != nil {
 		return false, errors.Wrap(invalidBlock{error: err}, "could not get execution payload")
 	}
-	lastValidHash, err := s.cfg.ExecutionEngineCaller.NewPayload(ctx, payload)
+
+	var lastValidHash []byte
+	if blk.Version() >= version.Deneb {
+		_, err = blk.Block().Body().BlobKzgCommitments()
+		if err != nil {
+			return false, errors.Wrap(invalidBlock{error: err}, "could not get blob kzg commitments")
+		}
+		// TODO: Convert kzg commitment to version hashes and feed to below
+		lastValidHash, err = s.cfg.ExecutionEngineCaller.NewPayload(ctx, payload, [][32]byte{})
+	} else {
+		lastValidHash, err = s.cfg.ExecutionEngineCaller.NewPayload(ctx, payload, [][32]byte{} /*empty version hashes before Deneb*/)
+	}
 	switch err {
 	case nil:
 		newPayloadValidNodeCount.Inc()
@@ -224,7 +236,7 @@ func (s *Service) notifyNewPayload(ctx context.Context, postStateVersion int,
 		if err != nil {
 			return false, err
 		}
-		invalidRoots, err := s.ForkChoicer().SetOptimisticToInvalid(ctx, root, blk.Block().ParentRoot(), bytesutil.ToBytes32(lastValidHash))
+		invalidRoots, err := s.cfg.ForkChoiceStore.SetOptimisticToInvalid(ctx, root, blk.Block().ParentRoot(), bytesutil.ToBytes32(lastValidHash))
 		if err != nil {
 			return false, err
 		}
@@ -250,20 +262,23 @@ func (s *Service) notifyNewPayload(ctx context.Context, postStateVersion int,

 // 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) (bool, payloadattribute.Attributer, primitives.ValidatorIndex) {
+func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState, slot primitives.Slot, headRoot []byte) (bool, payloadattribute.Attributer, primitives.ValidatorIndex) {
 	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 { // There's no need to build attribute if there is no proposer for slot.
+	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.
 	st = st.Copy()
-	st, err := transition.ProcessSlotsIfPossible(ctx, st, slot)
-	if err != nil {
-		log.WithError(err).Error("Could not process slots to get payload attribute")
-		return false, emptyAttri, 0
+	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
+		}
 	}
 	prevRando, err := helpers.RandaoMix(st, time.CurrentEpoch(st))
 	if err != nil {
@@ -301,7 +316,7 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,

 	var attr payloadattribute.Attributer
 	switch st.Version() {
-	case version.Capella:
+	case version.Capella, version.Deneb:
 		withdrawals, err := st.ExpectedWithdrawals()
 		if err != nil {
 			log.WithError(err).Error("Could not get expected withdrawals to get payload attribute")
--- a/beacon-chain/blockchain/execution_engine_test.go
+++ b/beacon-chain/blockchain/execution_engine_test.go
@@ -7,48 +7,39 @@ import (

 	"github.com/ethereum/go-ethereum/common"
 	gethtypes "github.com/ethereum/go-ethereum/core/types"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/blocks"
-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/execution"
-	mockExecution "github.com/prysmaticlabs/prysm/v3/beacon-chain/execution/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	forkchoicetypes "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/types"
-	bstate "github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	state_native "github.com/prysmaticlabs/prysm/v3/beacon-chain/state/state-native"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	fieldparams "github.com/prysmaticlabs/prysm/v3/config/fieldparams"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	consensusblocks "github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	v1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/blocks"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/execution"
+	mockExecution "github.com/prysmaticlabs/prysm/v4/beacon-chain/execution/testing"
+	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
+	bstate "github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	state_native "github.com/prysmaticlabs/prysm/v4/beacon-chain/state/state-native"
+	"github.com/prysmaticlabs/prysm/v4/config/features"
+	fieldparams "github.com/prysmaticlabs/prysm/v4/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	consensusblocks "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"
+	v1 "github.com/prysmaticlabs/prysm/v4/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"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) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
+	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs
+
 	altairBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockAltair())
 	altairBlkRoot, err := altairBlk.Block().HashTreeRoot()
 	require.NoError(t, err)
 	bellatrixBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockBellatrix())
 	bellatrixBlkRoot, err := bellatrixBlk.Block().HashTreeRoot()
 	require.NoError(t, err)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-		WithProposerIdsCache(cache.NewProposerPayloadIDsCache()),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+
 	st, _ := util.DeterministicGenesisState(t, 10)
 	service.head = &head{
 		state: st,
@@ -95,23 +86,15 @@ func Test_NotifyForkchoiceUpdate_GetPayloadAttrErrorCanContinue(t *testing.T) {
 }

 func Test_NotifyForkchoiceUpdate(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
+	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs
+
 	altairBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockAltair())
 	altairBlkRoot, err := altairBlk.Block().HashTreeRoot()
 	require.NoError(t, err)
 	bellatrixBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockBellatrix())
 	bellatrixBlkRoot, err := bellatrixBlk.Block().HashTreeRoot()
 	require.NoError(t, err)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-		WithProposerIdsCache(cache.NewProposerPayloadIDsCache()),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	st, _ := util.DeterministicGenesisState(t, 10)
 	service.head = &head{
 		state: st,
@@ -131,7 +114,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {

 	tests := []struct {
 		name             string
-		blk              interfaces.BeaconBlock
+		blk              interfaces.ReadOnlyBeaconBlock
 		headRoot         [32]byte
 		finalizedRoot    [32]byte
 		justifiedRoot    [32]byte
@@ -140,7 +123,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 	}{
 		{
 			name: "phase0 block",
-			blk: func() interfaces.BeaconBlock {
+			blk: func() interfaces.ReadOnlyBeaconBlock {
 				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}})
 				require.NoError(t, err)
 				return b
@@ -148,7 +131,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "altair block",
-			blk: func() interfaces.BeaconBlock {
+			blk: func() interfaces.ReadOnlyBeaconBlock {
 				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockAltair{Body: &ethpb.BeaconBlockBodyAltair{}})
 				require.NoError(t, err)
 				return b
@@ -156,7 +139,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "not execution block",
-			blk: func() interfaces.BeaconBlock {
+			blk: func() interfaces.ReadOnlyBeaconBlock {
 				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{
@@ -177,7 +160,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "happy case: finalized root is altair block",
-			blk: func() interfaces.BeaconBlock {
+			blk: func() interfaces.ReadOnlyBeaconBlock {
 				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{},
@@ -191,7 +174,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "happy case: finalized root is bellatrix block",
-			blk: func() interfaces.BeaconBlock {
+			blk: func() interfaces.ReadOnlyBeaconBlock {
 				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{},
@@ -205,7 +188,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "forkchoice updated with optimistic block",
-			blk: func() interfaces.BeaconBlock {
+			blk: func() interfaces.ReadOnlyBeaconBlock {
 				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{},
@@ -220,7 +203,7 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 		},
 		{
 			name: "forkchoice updated with invalid block",
-			blk: func() interfaces.BeaconBlock {
+			blk: func() interfaces.ReadOnlyBeaconBlock {
 				b, err := consensusblocks.NewBeaconBlock(&ethpb.BeaconBlockBellatrix{
 					Body: &ethpb.BeaconBlockBodyBellatrix{
 						ExecutionPayload: &v1.ExecutionPayload{},
@@ -263,8 +246,8 @@ func Test_NotifyForkchoiceUpdate(t *testing.T) {
 }

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

 	// Prepare blocks
 	ba := util.NewBeaconBlockBellatrix()
@@ -296,14 +279,8 @@ func Test_NotifyForkchoiceUpdate_NIlLVH(t *testing.T) {
 	brd, err := wbd.Block().HashTreeRoot()
 	require.NoError(t, err)

-	// Insert blocks into forkchoice
-	service := setupBeaconChain(t, beaconDB)
-	fcs := doublylinkedtree.New()
-	service.cfg.ForkChoiceStore = fcs
-	service.cfg.ProposerSlotIndexCache = cache.NewProposerPayloadIDsCache()
-
-	service.justifiedBalances.balances = []uint64{50, 100, 200}
-	require.NoError(t, err)
+	fcs.SetBalancesByRooter(func(context.Context, [32]byte) ([]uint64, error) { return []uint64{50, 100, 200}, nil })
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, &forkchoicetypes.Checkpoint{}))
 	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	state, blkRoot, err := prepareForkchoiceState(ctx, 1, bra, [32]byte{}, [32]byte{'A'}, ojc, ofc)
@@ -357,8 +334,8 @@ 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) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
+	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

 	// Prepare blocks
 	ba := util.NewBeaconBlockBellatrix()
@@ -413,18 +390,15 @@ func Test_NotifyForkchoiceUpdateRecursive_DoublyLinkedTree(t *testing.T) {
 	brg, err := wbg.Block().HashTreeRoot()
 	require.NoError(t, err)

-	// Insert blocks into forkchoice
-	service := setupBeaconChain(t, beaconDB)
-	fcs := doublylinkedtree.New()
-	service.cfg.ForkChoiceStore = fcs
-	service.cfg.ProposerSlotIndexCache = cache.NewProposerPayloadIDsCache()
-
-	service.justifiedBalances.balances = []uint64{50, 100, 200}
-	require.NoError(t, err)
+	fcs.SetBalancesByRooter(func(context.Context, [32]byte) ([]uint64, error) { return []uint64{50, 100, 200}, nil })
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, &forkchoicetypes.Checkpoint{}))
 	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	state, blkRoot, err := prepareForkchoiceState(ctx, 1, bra, [32]byte{}, [32]byte{'A'}, ojc, ofc)
 	require.NoError(t, err)
+
+	bState, _ := util.DeterministicGenesisState(t, 10)
+	require.NoError(t, beaconDB.SaveState(ctx, bState, bra))
 	require.NoError(t, fcs.InsertNode(ctx, state, blkRoot))
 	state, blkRoot, err = prepareForkchoiceState(ctx, 2, brb, bra, [32]byte{'B'}, ojc, ofc)
 	require.NoError(t, err)
@@ -450,9 +424,12 @@ func Test_NotifyForkchoiceUpdateRecursive_DoublyLinkedTree(t *testing.T) {
 	fcs.ProcessAttestation(ctx, []uint64{0}, brd, 1)
 	fcs.ProcessAttestation(ctx, []uint64{1}, brf, 1)
 	fcs.ProcessAttestation(ctx, []uint64{2}, brg, 1)
+	fcs.SetBalancesByRooter(service.cfg.StateGen.ActiveNonSlashedBalancesByRoot)
 	jc := &forkchoicetypes.Checkpoint{Epoch: 0, Root: bra}
-	require.NoError(t, fcs.UpdateJustifiedCheckpoint(jc))
-	headRoot, err := fcs.Head(ctx, []uint64{50, 100, 200})
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, jc))
+	fcs.SetBalancesByRooter(func(context.Context, [32]byte) ([]uint64, error) { return []uint64{50, 100, 200}, nil })
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, &forkchoicetypes.Checkpoint{}))
+	headRoot, err := fcs.Head(ctx)
 	require.NoError(t, err)
 	require.Equal(t, brg, headRoot)

@@ -476,7 +453,7 @@ func Test_NotifyForkchoiceUpdateRecursive_DoublyLinkedTree(t *testing.T) {
 	require.Equal(t, brf, InvalidBlockRoot(err))

 	// Ensure Head is D
-	headRoot, err = fcs.Head(ctx, service.justifiedBalances.balances)
+	headRoot, err = fcs.Head(ctx)
 	require.NoError(t, err)
 	require.Equal(t, brd, headRoot)

@@ -490,15 +467,9 @@ func Test_NotifyNewPayload(t *testing.T) {
 	cfg := params.BeaconConfig()
 	cfg.TerminalTotalDifficulty = "2"
 	params.OverrideBeaconConfig(cfg)
+	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	ctx, fcs := tr.ctx, tr.fcs

-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-	}
 	phase0State, _ := util.DeterministicGenesisState(t, 1)
 	altairState, _ := util.DeterministicGenesisStateAltair(t, 1)
 	bellatrixState, _ := util.DeterministicGenesisStateBellatrix(t, 2)
@@ -529,8 +500,6 @@ func Test_NotifyNewPayload(t *testing.T) {
 	}
 	bellatrixBlk, err := consensusblocks.NewSignedBeaconBlock(util.HydrateSignedBeaconBlockBellatrix(blk))
 	require.NoError(t, err)
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	st := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(epochsSinceFinalitySaveHotStateDB))
 	service.genesisTime = time.Now().Add(time.Duration(-1*int64(st)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
 	r, err := bellatrixBlk.Block().HashTreeRoot()
@@ -548,7 +517,7 @@ func Test_NotifyNewPayload(t *testing.T) {
 		postState      bstate.BeaconState
 		invalidBlock   bool
 		isValidPayload bool
-		blk            interfaces.SignedBeaconBlock
+		blk            interfaces.ReadOnlySignedBeaconBlock
 		newPayloadErr  error
 		errString      string
 		name           string
@@ -594,7 +563,7 @@ func Test_NotifyNewPayload(t *testing.T) {
 		{
 			name:      "altair pre state, happy case",
 			postState: bellatrixState,
-			blk: func() interfaces.SignedBeaconBlock {
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
 				blk := &ethpb.SignedBeaconBlockBellatrix{
 					Block: &ethpb.BeaconBlockBellatrix{
 						Body: &ethpb.BeaconBlockBodyBellatrix{
@@ -613,7 +582,7 @@ func Test_NotifyNewPayload(t *testing.T) {
 		{
 			name:      "not at merge transition",
 			postState: bellatrixState,
-			blk: func() interfaces.SignedBeaconBlock {
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
 				blk := &ethpb.SignedBeaconBlockBellatrix{
 					Block: &ethpb.BeaconBlockBellatrix{
 						Body: &ethpb.BeaconBlockBodyBellatrix{
@@ -639,7 +608,7 @@ func Test_NotifyNewPayload(t *testing.T) {
 		{
 			name:      "happy case",
 			postState: bellatrixState,
-			blk: func() interfaces.SignedBeaconBlock {
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
 				blk := &ethpb.SignedBeaconBlockBellatrix{
 					Block: &ethpb.BeaconBlockBellatrix{
 						Body: &ethpb.BeaconBlockBodyBellatrix{
@@ -658,7 +627,7 @@ func Test_NotifyNewPayload(t *testing.T) {
 		{
 			name:      "undefined error from ee",
 			postState: bellatrixState,
-			blk: func() interfaces.SignedBeaconBlock {
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
 				blk := &ethpb.SignedBeaconBlockBellatrix{
 					Block: &ethpb.BeaconBlockBellatrix{
 						Body: &ethpb.BeaconBlockBodyBellatrix{
@@ -678,7 +647,7 @@ func Test_NotifyNewPayload(t *testing.T) {
 		{
 			name:      "invalid block hash error from ee",
 			postState: bellatrixState,
-			blk: func() interfaces.SignedBeaconBlock {
+			blk: func() interfaces.ReadOnlySignedBeaconBlock {
 				blk := &ethpb.SignedBeaconBlockBellatrix{
 					Block: &ethpb.BeaconBlockBellatrix{
 						Body: &ethpb.BeaconBlockBodyBellatrix{
@@ -737,14 +706,10 @@ func Test_NotifyNewPayload_SetOptimisticToValid(t *testing.T) {
 	cfg := params.BeaconConfig()
 	cfg.TerminalTotalDifficulty = "2"
 	params.OverrideBeaconConfig(cfg)
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-	}
+
+	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	ctx := tr.ctx
+
 	bellatrixState, _ := util.DeterministicGenesisStateBellatrix(t, 2)
 	blk := &ethpb.SignedBeaconBlockBellatrix{
 		Block: &ethpb.BeaconBlockBellatrix{
@@ -757,8 +722,6 @@ func Test_NotifyNewPayload_SetOptimisticToValid(t *testing.T) {
 	}
 	bellatrixBlk, err := consensusblocks.NewSignedBeaconBlock(blk)
 	require.NoError(t, err)
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	e := &mockExecution.EngineClient{BlockByHashMap: map[[32]byte]*v1.ExecutionBlock{}}
 	e.BlockByHashMap[[32]byte{'a'}] = &v1.ExecutionBlock{
 		Header: gethtypes.Header{
@@ -781,19 +744,11 @@ func Test_NotifyNewPayload_SetOptimisticToValid(t *testing.T) {
 }

 func Test_GetPayloadAttribute(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, doublylinkedtree.New())),
-		WithProposerIdsCache(cache.NewProposerPayloadIDsCache()),
-	}
+	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	ctx := tr.ctx

-	// Cache miss
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	st, _ := util.DeterministicGenesisStateBellatrix(t, 1)
-	hasPayload, _, vId := service.getPayloadAttribute(ctx, st, 0)
+	hasPayload, _, vId := service.getPayloadAttribute(ctx, st, 0, []byte{})
 	require.Equal(t, false, hasPayload)
 	require.Equal(t, primitives.ValidatorIndex(0), vId)

@@ -802,7 +757,7 @@ func Test_GetPayloadAttribute(t *testing.T) {
 	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)
+	hasPayload, attr, vId := service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
 	require.Equal(t, true, hasPayload)
 	require.Equal(t, suggestedVid, vId)
 	require.Equal(t, params.BeaconConfig().EthBurnAddressHex, common.BytesToAddress(attr.SuggestedFeeRecipient()).String())
@@ -812,26 +767,36 @@ func Test_GetPayloadAttribute(t *testing.T) {
 	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)
+	hasPayload, attr, vId = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
 	require.Equal(t, true, hasPayload)
 	require.Equal(t, suggestedVid, vId)
 	require.Equal(t, suggestedAddr, common.BytesToAddress(attr.SuggestedFeeRecipient()))
 }

-func Test_GetPayloadAttributeV2(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, doublylinkedtree.New())),
-		WithProposerIdsCache(cache.NewProposerPayloadIDsCache()),
-	}
+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()))
+	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)
+	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()))
+	ctx := tr.ctx

-	// Cache miss
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	st, _ := util.DeterministicGenesisStateCapella(t, 1)
-	hasPayload, _, vId := service.getPayloadAttribute(ctx, st, 0)
+	hasPayload, _, vId := service.getPayloadAttribute(ctx, st, 0, []byte{})
 	require.Equal(t, false, hasPayload)
 	require.Equal(t, primitives.ValidatorIndex(0), vId)

@@ -840,7 +805,7 @@ func Test_GetPayloadAttributeV2(t *testing.T) {
 	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)
+	hasPayload, attr, vId := service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
 	require.Equal(t, true, hasPayload)
 	require.Equal(t, suggestedVid, vId)
 	require.Equal(t, params.BeaconConfig().EthBurnAddressHex, common.BytesToAddress(attr.SuggestedFeeRecipient()).String())
@@ -853,7 +818,43 @@ func Test_GetPayloadAttributeV2(t *testing.T) {
 	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)
+	hasPayload, attr, vId = service.getPayloadAttribute(ctx, st, slot, params.BeaconConfig().ZeroHash[:])
+	require.Equal(t, true, hasPayload)
+	require.Equal(t, suggestedVid, vId)
+	require.Equal(t, suggestedAddr, common.BytesToAddress(attr.SuggestedFeeRecipient()))
+	a, err = attr.Withdrawals()
+	require.NoError(t, err)
+	require.Equal(t, 0, len(a))
+}
+
+func Test_GetPayloadAttributeDeneb(t *testing.T) {
+	service, tr := minimalTestService(t, WithProposerIdsCache(cache.NewProposerPayloadIDsCache()))
+	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)
+
+	// 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)
+	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)
 	require.Equal(t, suggestedAddr, common.BytesToAddress(attr.SuggestedFeeRecipient()))
@@ -865,18 +866,9 @@ func Test_GetPayloadAttributeV2(t *testing.T) {
 func Test_UpdateLastValidatedCheckpoint(t *testing.T) {
 	params.SetupTestConfigCleanup(t)
 	params.OverrideBeaconConfig(params.MainnetConfig())
+	service, tr := minimalTestService(t)
+	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	stateGen := stategen.New(beaconDB, fcs)
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stateGen),
-		WithForkChoiceStore(fcs),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	var genesisStateRoot [32]byte
 	genesisBlk := blocks.NewGenesisBlock(genesisStateRoot[:])
 	util.SaveBlock(t, ctx, beaconDB, genesisBlk)
@@ -886,7 +878,7 @@ func Test_UpdateLastValidatedCheckpoint(t *testing.T) {
 	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	fjc := &forkchoicetypes.Checkpoint{Epoch: 0, Root: params.BeaconConfig().ZeroHash}
-	require.NoError(t, fcs.UpdateJustifiedCheckpoint(fjc))
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, fjc))
 	require.NoError(t, fcs.UpdateFinalizedCheckpoint(fjc))
 	state, blkRoot, err := prepareForkchoiceState(ctx, 0, genesisRoot, params.BeaconConfig().ZeroHash, params.BeaconConfig().ZeroHash, ojc, ofc)
 	require.NoError(t, err)
@@ -953,6 +945,7 @@ func Test_UpdateLastValidatedCheckpoint(t *testing.T) {
 	twentyfc := &ethpb.Checkpoint{Epoch: 20, Root: validRoot[:]}
 	state, blkRoot, err = prepareForkchoiceState(ctx, 640, validRoot, genesisRoot, params.BeaconConfig().ZeroHash, twentyjc, twentyfc)
 	require.NoError(t, err)
+	fcs.SetBalancesByRooter(func(_ context.Context, _ [32]byte) ([]uint64, error) { return []uint64{}, nil })
 	require.NoError(t, fcs.InsertNode(ctx, state, blkRoot))
 	require.NoError(t, fcs.SetOptimisticToValid(ctx, validRoot))
 	assert.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, validRoot))
@@ -980,16 +973,8 @@ func Test_UpdateLastValidatedCheckpoint(t *testing.T) {
 }

 func TestService_removeInvalidBlockAndState(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fc := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fc)),
-		WithForkChoiceStore(fc),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx

 	// Deleting unknown block should not error.
 	require.NoError(t, service.removeInvalidBlockAndState(ctx, [][32]byte{{'a'}, {'b'}, {'c'}}))
@@ -1033,18 +1018,10 @@ func TestService_removeInvalidBlockAndState(t *testing.T) {
 }

 func TestService_getPayloadHash(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fc := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fc)),
-		WithForkChoiceStore(fc),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx

-	_, err = service.getPayloadHash(ctx, []byte{})
+	_, err := service.getPayloadHash(ctx, []byte{})
 	require.ErrorIs(t, errBlockNotFoundInCacheOrDB, err)

 	b := util.NewBeaconBlock()
--- a/beacon-chain/blockchain/forkchoice_update_execution.go
+++ b/beacon-chain/blockchain/forkchoice_update_execution.go
@@ -0,0 +1,134 @@
+package blockchain
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"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"
+	"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()
+
+	currentHeadRoot := s.originBlockRoot
+	if s.head != nil {
+		currentHeadRoot = s.headRoot()
+	}
+
+	return r != currentHeadRoot || r == [32]byte{}
+}
+
+func (s *Service) getStateAndBlock(ctx context.Context, r [32]byte) (state.BeaconState, interfaces.ReadOnlySignedBeaconBlock, error) {
+	if !s.hasBlockInInitSyncOrDB(ctx, r) {
+		return nil, nil, errors.New("block does not exist")
+	}
+	newHeadBlock, err := s.getBlock(ctx, r)
+	if err != nil {
+		return nil, nil, err
+	}
+	headState, err := s.cfg.StateGen.StateByRoot(ctx, r)
+	if err != nil {
+		return nil, nil, err
+	}
+	return headState, newHeadBlock, nil
+}
+
+// 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) {
+	_, 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)
+	if err != nil {
+		log.WithError(err).Error("Could not get forkchoice update argument")
+		return false, nil
+	}
+
+	_, 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 {
+		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 {
+		log.WithError(err).Error("could not prune attestations from pool")
+	}
+	return true, nil
+}
+
+// shouldOverrideFCU checks whether the incoming block is still subject to being
+// reorged or not by the next proposer.
+func (s *Service) shouldOverrideFCU(newHeadRoot [32]byte, proposingSlot primitives.Slot) bool {
+	headWeight, err := s.cfg.ForkChoiceStore.Weight(newHeadRoot)
+	if err != nil {
+		log.WithError(err).WithField("root", fmt.Sprintf("%#x", newHeadRoot)).Warn("could not determine node weight")
+	}
+	currentSlot := s.CurrentSlot()
+	if proposingSlot == currentSlot {
+		proposerHead := s.cfg.ForkChoiceStore.GetProposerHead()
+		if proposerHead != newHeadRoot {
+			return true
+		}
+		log.WithFields(logrus.Fields{
+			"root":   fmt.Sprintf("%#x", newHeadRoot),
+			"weight": headWeight,
+		}).Infof("Attempted late block reorg aborted due to attestations at %d seconds",
+			params.BeaconConfig().SecondsPerSlot)
+		lateBlockFailedAttemptSecondThreshold.Inc()
+	} else {
+		if s.cfg.ForkChoiceStore.ShouldOverrideFCU() {
+			return true
+		}
+		secs, err := slots.SecondsSinceSlotStart(currentSlot,
+			uint64(s.genesisTime.Unix()), uint64(time.Now().Unix()))
+		if err != nil {
+			log.WithError(err).Error("could not compute seconds since slot start")
+		}
+		if secs >= doublylinkedtree.ProcessAttestationsThreshold {
+			log.WithFields(logrus.Fields{
+				"root":   fmt.Sprintf("%#x", newHeadRoot),
+				"weight": headWeight,
+			}).Infof("Attempted late block reorg aborted due to attestations at %d seconds",
+				doublylinkedtree.ProcessAttestationsThreshold)
+			lateBlockFailedAttemptFirstThreshold.Inc()
+		}
+	}
+	return false
+}
--- a/beacon-chain/blockchain/forkchoice_update_execution_test.go
+++ b/beacon-chain/blockchain/forkchoice_update_execution_test.go
@@ -0,0 +1,224 @@
+package blockchain
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
+	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
+	mockExecution "github.com/prysmaticlabs/prysm/v4/beacon-chain/execution/testing"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
+	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)
+	require.Equal(t, true, service.isNewHead([32]byte{}))
+
+	service.head = &head{root: [32]byte{1}}
+	require.Equal(t, true, service.isNewHead([32]byte{2}))
+	require.Equal(t, false, service.isNewHead([32]byte{1}))
+
+	// Nil head should use origin root
+	service.head = nil
+	service.originBlockRoot = [32]byte{3}
+	require.Equal(t, true, service.isNewHead([32]byte{2}))
+	require.Equal(t, false, service.isNewHead([32]byte{3}))
+}
+
+func TestService_getHeadStateAndBlock(t *testing.T) {
+	beaconDB := testDB.SetupDB(t)
+	service := setupBeaconChain(t, beaconDB)
+	_, _, err := service.getStateAndBlock(context.Background(), [32]byte{})
+	require.ErrorContains(t, "block does not exist", err)
+
+	blk, err := blocks.NewSignedBeaconBlock(util.HydrateSignedBeaconBlock(&ethpb.SignedBeaconBlock{Signature: []byte{1}}))
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), blk))
+
+	st, _ := util.DeterministicGenesisState(t, 1)
+	r, err := blk.Block().HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.BeaconDB.SaveState(context.Background(), st, r))
+
+	gotState, err := service.cfg.BeaconDB.State(context.Background(), r)
+	require.NoError(t, err)
+	require.DeepEqual(t, st.ToProto(), gotState.ToProto())
+
+	gotBlk, err := service.cfg.BeaconDB.Block(context.Background(), r)
+	require.NoError(t, err)
+	require.DeepEqual(t, blk, gotBlk)
+}
+
+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)
+
+	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)
+	require.NoError(t, err)
+	r1, err := b.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, service.saveInitSyncBlock(ctx, r1, wsb))
+	st, _ := util.DeterministicGenesisState(t, 1)
+	service.head = &head{
+		root:  r1,
+		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
+	b = util.NewBeaconBlock()
+	b.Block.Slot = 3
+	util.SaveBlock(t, ctx, service.cfg.BeaconDB, b)
+	r1, err = b.Block.HashTreeRoot()
+	require.NoError(t, err)
+	st, _ = util.DeterministicGenesisState(t, 1)
+	service.head = &head{
+		root:  r1,
+		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)
+
+	// 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)
+}
+
+func TestService_forkchoiceUpdateWithExecution_SameHeadRootNewProposer(t *testing.T) {
+	service, tr := minimalTestService(t)
+	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs
+
+	altairBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockAltair())
+	altairBlkRoot, err := altairBlk.Block().HashTreeRoot()
+	require.NoError(t, err)
+	bellatrixBlk := util.SaveBlock(t, ctx, beaconDB, util.NewBeaconBlockBellatrix())
+	bellatrixBlkRoot, err := bellatrixBlk.Block().HashTreeRoot()
+	require.NoError(t, err)
+	st, _ := util.DeterministicGenesisState(t, 10)
+	service.head = &head{
+		state: st,
+	}
+
+	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	state, blkRoot, err := prepareForkchoiceState(ctx, 0, [32]byte{}, [32]byte{}, params.BeaconConfig().ZeroHash, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, fcs.InsertNode(ctx, state, blkRoot))
+	state, blkRoot, err = prepareForkchoiceState(ctx, 1, altairBlkRoot, [32]byte{}, params.BeaconConfig().ZeroHash, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, fcs.InsertNode(ctx, state, blkRoot))
+	state, blkRoot, err = prepareForkchoiceState(ctx, 2, bellatrixBlkRoot, altairBlkRoot, params.BeaconConfig().ZeroHash, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, fcs.InsertNode(ctx, state, blkRoot))
+
+	service.cfg.ExecutionEngineCaller = &mockExecution.EngineClient{}
+	require.NoError(t, beaconDB.SaveState(ctx, st, bellatrixBlkRoot))
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, bellatrixBlkRoot))
+	sb, err := blocks.NewSignedBeaconBlock(util.HydrateSignedBeaconBlockBellatrix(&ethpb.SignedBeaconBlockBellatrix{}))
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveBlock(ctx, sb))
+	r, err := sb.Block().HashTreeRoot()
+	require.NoError(t, err)
+
+	// Set head to be the same but proposing next slot
+	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)
+
+}
+
+func TestShouldOverrideFCU(t *testing.T) {
+	hook := logTest.NewGlobal()
+	service, tr := minimalTestService(t)
+	ctx, fcs := tr.ctx, tr.fcs
+
+	service.SetGenesisTime(time.Now().Add(-time.Duration(2*params.BeaconConfig().SecondsPerSlot) * time.Second))
+	headRoot := [32]byte{'b'}
+	parentRoot := [32]byte{'a'}
+	ojc := &ethpb.Checkpoint{}
+	st, root, err := prepareForkchoiceState(ctx, 1, parentRoot, [32]byte{}, [32]byte{}, ojc, ojc)
+	require.NoError(t, err)
+	require.NoError(t, fcs.InsertNode(ctx, st, root))
+	st, root, err = prepareForkchoiceState(ctx, 2, headRoot, parentRoot, [32]byte{}, ojc, ojc)
+	require.NoError(t, err)
+	require.NoError(t, fcs.InsertNode(ctx, st, root))
+
+	require.Equal(t, primitives.Slot(2), service.CurrentSlot())
+	require.Equal(t, true, service.shouldOverrideFCU(headRoot, 2))
+	require.LogsDoNotContain(t, hook, "12 seconds")
+	require.Equal(t, false, service.shouldOverrideFCU(parentRoot, 2))
+	require.LogsContain(t, hook, "12 seconds")
+
+	head, err := fcs.Head(ctx)
+	require.NoError(t, err)
+	require.Equal(t, headRoot, head)
+
+	fcs.SetGenesisTime(uint64(time.Now().Unix()) - 29)
+	require.Equal(t, true, service.shouldOverrideFCU(parentRoot, 3))
+	require.LogsDoNotContain(t, hook, "10 seconds")
+	fcs.SetGenesisTime(uint64(time.Now().Unix()) - 24)
+	service.SetGenesisTime(time.Now().Add(-time.Duration(2*params.BeaconConfig().SecondsPerSlot+10) * time.Second))
+	require.Equal(t, false, service.shouldOverrideFCU(parentRoot, 3))
+	require.LogsContain(t, hook, "10 seconds")
+}
--- a/beacon-chain/blockchain/head.go
+++ b/beacon-chain/blockchain/head.go
@@ -6,21 +6,21 @@ import (
 	"fmt"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed"
-	statefeed "github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	fieldparams "github.com/prysmaticlabs/prysm/v3/config/fieldparams"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	"github.com/prysmaticlabs/prysm/v3/math"
-	ethpbv1 "github.com/prysmaticlabs/prysm/v3/proto/eth/v1"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"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"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	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/interfaces"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/v4/math"
+	ethpbv1 "github.com/prysmaticlabs/prysm/v4/proto/eth/v1"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )
@@ -28,14 +28,9 @@ import (
 // UpdateAndSaveHeadWithBalances updates the beacon state head after getting justified balanced from cache.
 // This function is only used in spec-tests, it does save the head after updating it.
 func (s *Service) UpdateAndSaveHeadWithBalances(ctx context.Context) error {
-	jp := s.CurrentJustifiedCheckpt()
-
-	balances, err := s.justifiedBalances.get(ctx, bytesutil.ToBytes32(jp.Root))
-	if err != nil {
-		msg := fmt.Sprintf("could not read balances for state w/ justified checkpoint %#x", jp.Root)
-		return errors.Wrap(err, msg)
-	}
-	headRoot, err := s.cfg.ForkChoiceStore.Head(ctx, balances)
+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
+	headRoot, err := s.cfg.ForkChoiceStore.Head(ctx)
 	if err != nil {
 		return errors.Wrap(err, "could not update head")
 	}
@@ -52,29 +47,23 @@ func (s *Service) UpdateAndSaveHeadWithBalances(ctx context.Context) error {

 // This defines the current chain service's view of head.
 type head struct {
-	root  [32]byte                     // current head root.
-	block interfaces.SignedBeaconBlock // current head block.
-	state state.BeaconState            // current head state.
+	root  [32]byte                             // current head root.
+	block interfaces.ReadOnlySignedBeaconBlock // current head block.
+	state state.BeaconState                    // current head state.
 }

 // This saves head info to the local service cache, it also saves the
 // new head root to the DB.
-func (s *Service) saveHead(ctx context.Context, newHeadRoot [32]byte, headBlock interfaces.SignedBeaconBlock, headState state.BeaconState) error {
+// Caller of the method MUST acquire a lock on forkchoice.
+func (s *Service) saveHead(ctx context.Context, newHeadRoot [32]byte, headBlock interfaces.ReadOnlySignedBeaconBlock, headState state.BeaconState) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.saveHead")
 	defer span.End()

 	// Do nothing if head hasn't changed.
-	var oldHeadRoot [32]byte
-	s.headLock.RLock()
-	if s.head == nil {
-		oldHeadRoot = s.originBlockRoot
-	} else {
-		oldHeadRoot = s.head.root
-	}
-	s.headLock.RUnlock()
-	if newHeadRoot == oldHeadRoot {
+	if !s.isNewHead(newHeadRoot) {
 		return nil
 	}
+
 	if err := blocks.BeaconBlockIsNil(headBlock); err != nil {
 		return err
 	}
@@ -100,20 +89,25 @@ func (s *Service) saveHead(ctx context.Context, newHeadRoot [32]byte, headBlock
 	newHeadSlot := headBlock.Block().Slot()
 	newStateRoot := headBlock.Block().StateRoot()

-	// A chain re-org occurred, so we fire an event notifying the rest of the services.
+	r, err := s.HeadRoot(ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not get old head root")
+	}
+	oldHeadRoot := bytesutil.ToBytes32(r)
 	if headBlock.Block().ParentRoot() != oldHeadRoot {
-		commonRoot, forkSlot, err := s.ForkChoicer().CommonAncestor(ctx, oldHeadRoot, newHeadRoot)
+		// A chain re-org occurred, so we fire an event notifying the rest of the services.
+		commonRoot, forkSlot, err := s.cfg.ForkChoiceStore.CommonAncestor(ctx, oldHeadRoot, newHeadRoot)
 		if err != nil {
 			log.WithError(err).Error("Could not find common ancestor root")
 			commonRoot = params.BeaconConfig().ZeroHash
 		}
 		dis := headSlot + newHeadSlot - 2*forkSlot
 		dep := math.Max(uint64(headSlot-forkSlot), uint64(newHeadSlot-forkSlot))
-		oldWeight, err := s.ForkChoicer().Weight(oldHeadRoot)
+		oldWeight, err := s.cfg.ForkChoiceStore.Weight(oldHeadRoot)
 		if err != nil {
 			log.WithField("root", fmt.Sprintf("%#x", oldHeadRoot)).Warn("could not determine node weight")
 		}
-		newWeight, err := s.ForkChoicer().Weight(newHeadRoot)
+		newWeight, err := s.cfg.ForkChoiceStore.Weight(newHeadRoot)
 		if err != nil {
 			log.WithField("root", fmt.Sprintf("%#x", newHeadRoot)).Warn("could not determine node weight")
 		}
@@ -131,7 +125,7 @@ func (s *Service) saveHead(ctx context.Context, newHeadRoot [32]byte, headBlock
 		reorgDistance.Observe(float64(dis))
 		reorgDepth.Observe(float64(dep))

-		isOptimistic, err := s.IsOptimistic(ctx)
+		isOptimistic, err := s.cfg.ForkChoiceStore.IsOptimistic(newHeadRoot)
 		if err != nil {
 			return errors.Wrap(err, "could not check if node is optimistically synced")
 		}
@@ -179,7 +173,7 @@ func (s *Service) saveHead(ctx context.Context, newHeadRoot [32]byte, headBlock
 // This gets called to update canonical root mapping. It does not save head block
 // root in DB. With the inception of initial-sync-cache-state flag, it uses finalized
 // check point as anchors to resume sync therefore head is no longer needed to be saved on per slot basis.
-func (s *Service) saveHeadNoDB(ctx context.Context, b interfaces.SignedBeaconBlock, r [32]byte, hs state.BeaconState) error {
+func (s *Service) saveHeadNoDB(ctx context.Context, b interfaces.ReadOnlySignedBeaconBlock, r [32]byte, hs state.BeaconState) error {
 	if err := blocks.BeaconBlockIsNil(b); err != nil {
 		return err
 	}
@@ -202,7 +196,7 @@ func (s *Service) saveHeadNoDB(ctx context.Context, b interfaces.SignedBeaconBlo
 }

 // This sets head view object which is used to track the head slot, root, block and state.
-func (s *Service) setHead(root [32]byte, block interfaces.SignedBeaconBlock, state state.BeaconState) error {
+func (s *Service) setHead(root [32]byte, block interfaces.ReadOnlySignedBeaconBlock, state state.BeaconState) error {
 	s.headLock.Lock()
 	defer s.headLock.Unlock()

@@ -222,7 +216,7 @@ func (s *Service) setHead(root [32]byte, block interfaces.SignedBeaconBlock, sta
 // This sets head view object which is used to track the head slot, root, block and state. The method
 // assumes that state being passed into the method will not be modified by any other alternate
 // caller which holds the state's reference.
-func (s *Service) setHeadInitialSync(root [32]byte, block interfaces.SignedBeaconBlock, state state.BeaconState) error {
+func (s *Service) setHeadInitialSync(root [32]byte, block interfaces.ReadOnlySignedBeaconBlock, state state.BeaconState) error {
 	s.headLock.Lock()
 	defer s.headLock.Unlock()

@@ -262,7 +256,7 @@ func (s *Service) headRoot() [32]byte {
 // This returns the head block.
 // It does a full copy on head block for immutability.
 // This is a lock free version.
-func (s *Service) headBlock() (interfaces.SignedBeaconBlock, error) {
+func (s *Service) headBlock() (interfaces.ReadOnlySignedBeaconBlock, error) {
 	return s.head.block.Copy()
 }

@@ -276,6 +270,16 @@ func (s *Service) headState(ctx context.Context) state.BeaconState {
 	return s.head.state.Copy()
 }

+// This returns a read only version of the head state.
+// It does not perform a copy of the head state.
+// This is a lock free version.
+func (s *Service) headStateReadOnly(ctx context.Context) state.ReadOnlyBeaconState {
+	ctx, span := trace.StartSpan(ctx, "blockChain.headStateReadOnly")
+	defer span.End()
+
+	return s.head.state
+}
+
 // This returns the genesis validators root of the head state.
 // This is a lock free version.
 func (s *Service) headGenesisValidatorsRoot() [32]byte {
@@ -361,7 +365,7 @@ func (s *Service) notifyNewHeadEvent(
 // This saves the Attestations and BLSToExecChanges between `orphanedRoot` and the common ancestor root that is derived using `newHeadRoot`.
 // It also filters out the attestations that is one epoch older as a defense so invalid attestations don't flow into the attestation pool.
 func (s *Service) saveOrphanedOperations(ctx context.Context, orphanedRoot [32]byte, newHeadRoot [32]byte) error {
-	commonAncestorRoot, _, err := s.ForkChoicer().CommonAncestor(ctx, newHeadRoot, orphanedRoot)
+	commonAncestorRoot, _, err := s.cfg.ForkChoiceStore.CommonAncestor(ctx, newHeadRoot, orphanedRoot)
 	switch {
 	// Exit early if there's no common ancestor and root doesn't exist, there would be nothing to save.
 	case errors.Is(err, forkchoice.ErrUnknownCommonAncestor):
@@ -399,6 +403,19 @@ func (s *Service) saveOrphanedOperations(ctx context.Context, orphanedRoot [32]b
 			}
 			saveOrphanedAttCount.Inc()
 		}
+		for _, as := range orphanedBlk.Block().Body().AttesterSlashings() {
+			if err := s.cfg.SlashingPool.InsertAttesterSlashing(ctx, s.headStateReadOnly(ctx), as); err != nil {
+				log.WithError(err).Error("Could not insert reorg attester slashing")
+			}
+		}
+		for _, vs := range orphanedBlk.Block().Body().ProposerSlashings() {
+			if err := s.cfg.SlashingPool.InsertProposerSlashing(ctx, s.headStateReadOnly(ctx), vs); err != nil {
+				log.WithError(err).Error("Could not insert reorg proposer slashing")
+			}
+		}
+		for _, v := range orphanedBlk.Block().Body().VoluntaryExits() {
+			s.cfg.ExitPool.InsertVoluntaryExit(v)
+		}
 		if orphanedBlk.Version() >= version.Capella {
 			changes, err := orphanedBlk.Block().Body().BLSToExecutionChanges()
 			if err != nil {
--- a/beacon-chain/blockchain/head_sync_committee_info.go
+++ b/beacon-chain/blockchain/head_sync_committee_info.go
@@ -5,17 +5,17 @@ import (
 	"fmt"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/async"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/altair"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/signing"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/transition"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/async"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/altair"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
+	"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/state"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 )

 // Initialize the state cache for sync committees.
@@ -53,7 +53,7 @@ func (s *Service) HeadSyncContributionProofDomain(ctx context.Context, slot prim

 // HeadSyncCommitteeIndices returns the sync committee index position using the head state. Input `slot` is taken in consideration
 // where validator's duty for `slot - 1` is used for block inclusion in `slot`. That means when a validator is at epoch boundary
-// across EPOCHS_PER_SYNC_COMMITTEE_PERIOD then the valiator will be considered using next period sync committee.
+// across EPOCHS_PER_SYNC_COMMITTEE_PERIOD then the validator will be considered using next period sync committee.
 //
 // Spec definition:
 // Being assigned to a sync committee for a given slot means that the validator produces and broadcasts signatures for slot - 1 for inclusion in slot.
--- a/beacon-chain/blockchain/head_sync_committee_info_test.go
+++ b/beacon-chain/blockchain/head_sync_committee_info_test.go
@@ -4,13 +4,13 @@ import (
 	"context"
 	"testing"

-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/signing"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 )

 func TestService_HeadSyncCommitteeIndices(t *testing.T) {
--- a/beacon-chain/blockchain/head_test.go
+++ b/beacon-chain/blockchain/head_test.go
@@ -7,22 +7,20 @@ import (
 	"testing"
 	"time"

-	mock "github.com/prysmaticlabs/prysm/v3/beacon-chain/blockchain/testing"
-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/blstoexec"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/v3/config/features"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpbv1 "github.com/prysmaticlabs/prysm/v3/proto/eth/v1"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	mock "github.com/prysmaticlabs/prysm/v4/beacon-chain/blockchain/testing"
+	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
+	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/blstoexec"
+	"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"
+	ethpbv1 "github.com/prysmaticlabs/prysm/v4/proto/eth/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

@@ -152,20 +150,6 @@ func TestSaveHead_Different_Reorg(t *testing.T) {
 	require.LogsContain(t, hook, "depth=1")
 }

-func TestCacheJustifiedStateBalances_CanCache(t *testing.T) {
-	beaconDB := testDB.SetupDB(t)
-	service := setupBeaconChain(t, beaconDB)
-	ctx := context.Background()
-
-	state, _ := util.DeterministicGenesisState(t, 100)
-	r := [32]byte{'a'}
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(context.Background(), &ethpb.StateSummary{Root: r[:]}))
-	require.NoError(t, service.cfg.BeaconDB.SaveState(context.Background(), state, r))
-	balances, err := service.justifiedBalances.get(ctx, r)
-	require.NoError(t, err)
-	require.DeepEqual(t, balances, state.Balances(), "Incorrect justified balances")
-}
-
 func Test_notifyNewHeadEvent(t *testing.T) {
 	t.Run("genesis_state_root", func(t *testing.T) {
 		bState, _ := util.DeterministicGenesisState(t, 10)
@@ -232,6 +216,48 @@ func Test_notifyNewHeadEvent(t *testing.T) {
 	})
 }

+func TestRetrieveHead_ReadOnly(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	service := setupBeaconChain(t, beaconDB)
+
+	oldBlock := util.SaveBlock(t, context.Background(), service.cfg.BeaconDB, util.NewBeaconBlock())
+	oldRoot, err := oldBlock.Block().HashTreeRoot()
+	require.NoError(t, err)
+	service.head = &head{
+		root:  oldRoot,
+		block: oldBlock,
+	}
+
+	newHeadSignedBlock := util.NewBeaconBlock()
+	newHeadSignedBlock.Block.Slot = 1
+	newHeadBlock := newHeadSignedBlock.Block
+	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+
+	wsb := util.SaveBlock(t, context.Background(), service.cfg.BeaconDB, newHeadSignedBlock)
+	newRoot, err := newHeadBlock.HashTreeRoot()
+	require.NoError(t, err)
+	state, blkRoot, err := prepareForkchoiceState(ctx, wsb.Block().Slot()-1, wsb.Block().ParentRoot(), service.cfg.ForkChoiceStore.CachedHeadRoot(), [32]byte{}, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
+
+	state, blkRoot, err = prepareForkchoiceState(ctx, wsb.Block().Slot(), newRoot, wsb.Block().ParentRoot(), [32]byte{}, ojc, ofc)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
+	headState, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, headState.SetSlot(1))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(context.Background(), &ethpb.StateSummary{Slot: 1, Root: newRoot[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveState(context.Background(), headState, newRoot))
+	require.NoError(t, service.saveHead(context.Background(), newRoot, wsb, headState))
+
+	rOnlyState, err := service.HeadStateReadOnly(ctx)
+	require.NoError(t, err)
+
+	assert.Equal(t, rOnlyState, service.head.state, "Head is not the same object")
+}
+
 func TestSaveOrphanedAtts(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
@@ -280,7 +306,7 @@ func TestSaveOrphanedAtts(t *testing.T) {
 		require.NoError(t, err)
 		state, blkRoot, err := prepareForkchoiceState(ctx, blk.Block.Slot, r, bytesutil.ToBytes32(blk.Block.ParentRoot), [32]byte{}, ojc, ofc)
 		require.NoError(t, err)
-		require.NoError(t, service.ForkChoicer().InsertNode(ctx, state, blkRoot))
+		require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
 		util.SaveBlock(t, ctx, beaconDB, blk)
 	}

@@ -298,6 +324,88 @@ func TestSaveOrphanedAtts(t *testing.T) {
 	require.DeepEqual(t, wantAtts, atts)
 }

+func TestSaveOrphanedOps(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	config := params.BeaconConfig()
+	config.ShardCommitteePeriod = 0
+	params.OverrideBeaconConfig(config)
+
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	service := setupBeaconChain(t, beaconDB)
+	service.genesisTime = time.Now().Add(time.Duration(-10*int64(1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+
+	// Chain setup
+	// 0 -- 1 -- 2 -- 3
+	//  \-4
+	st, keys := util.DeterministicGenesisState(t, 64)
+	service.head = &head{state: st}
+	blkG, err := util.GenerateFullBlock(st, keys, util.DefaultBlockGenConfig(), 0)
+	assert.NoError(t, err)
+
+	util.SaveBlock(t, ctx, service.cfg.BeaconDB, blkG)
+	rG, err := blkG.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	blk1, err := util.GenerateFullBlock(st, keys, util.DefaultBlockGenConfig(), 1)
+	assert.NoError(t, err)
+	blk1.Block.ParentRoot = rG[:]
+	r1, err := blk1.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	blk2, err := util.GenerateFullBlock(st, keys, util.DefaultBlockGenConfig(), 2)
+	assert.NoError(t, err)
+	blk2.Block.ParentRoot = r1[:]
+	r2, err := blk2.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	blkConfig := util.DefaultBlockGenConfig()
+	blkConfig.NumBLSChanges = 5
+	blkConfig.NumProposerSlashings = 1
+	blkConfig.NumAttesterSlashings = 1
+	blkConfig.NumVoluntaryExits = 1
+	blk3, err := util.GenerateFullBlock(st, keys, blkConfig, 3)
+	assert.NoError(t, err)
+	blk3.Block.ParentRoot = r2[:]
+	r3, err := blk3.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	blk4 := util.NewBeaconBlock()
+	blk4.Block.Slot = 4
+	blk4.Block.ParentRoot = rG[:]
+	r4, err := blk4.Block.HashTreeRoot()
+	require.NoError(t, err)
+	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+
+	for _, blk := range []*ethpb.SignedBeaconBlock{blkG, blk1, blk2, blk3, blk4} {
+		r, err := blk.Block.HashTreeRoot()
+		require.NoError(t, err)
+		state, blkRoot, err := prepareForkchoiceState(ctx, blk.Block.Slot, r, bytesutil.ToBytes32(blk.Block.ParentRoot), [32]byte{}, ojc, ofc)
+		require.NoError(t, err)
+		require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
+		util.SaveBlock(t, ctx, beaconDB, blk)
+	}
+
+	require.NoError(t, service.saveOrphanedOperations(ctx, r3, r4))
+	require.Equal(t, 3, service.cfg.AttPool.AggregatedAttestationCount())
+	wantAtts := []*ethpb.Attestation{
+		blk3.Block.Body.Attestations[0],
+		blk2.Block.Body.Attestations[0],
+		blk1.Block.Body.Attestations[0],
+	}
+	atts := service.cfg.AttPool.AggregatedAttestations()
+	sort.Slice(atts, func(i, j int) bool {
+		return atts[i].Data.Slot > atts[j].Data.Slot
+	})
+	require.DeepEqual(t, wantAtts, atts)
+	require.Equal(t, 1, len(service.cfg.SlashingPool.PendingProposerSlashings(ctx, st, false)))
+	require.Equal(t, 1, len(service.cfg.SlashingPool.PendingAttesterSlashings(ctx, st, false)))
+	exits, err := service.cfg.ExitPool.PendingExits()
+	require.NoError(t, err)
+	require.Equal(t, 1, len(exits))
+}
+
 func TestSaveOrphanedAtts_CanFilter(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
@@ -345,7 +453,7 @@ func TestSaveOrphanedAtts_CanFilter(t *testing.T) {
 		require.NoError(t, err)
 		state, blkRoot, err := prepareForkchoiceState(ctx, blk.Block.Slot, r, bytesutil.ToBytes32(blk.Block.ParentRoot), [32]byte{}, ojc, ofc)
 		require.NoError(t, err)
-		require.NoError(t, service.ForkChoicer().InsertNode(ctx, state, blkRoot))
+		require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
 		util.SaveBlock(t, ctx, beaconDB, blk)
 	}

@@ -357,11 +465,6 @@ func TestSaveOrphanedAtts_CanFilter(t *testing.T) {
 }

 func TestSaveOrphanedAtts_DoublyLinkedTrie(t *testing.T) {
-	resetCfg := features.InitWithReset(&features.Flags{
-		DisableForkchoiceDoublyLinkedTree: false,
-	})
-	defer resetCfg()
-
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
@@ -408,7 +511,7 @@ func TestSaveOrphanedAtts_DoublyLinkedTrie(t *testing.T) {
 		require.NoError(t, err)
 		state, blkRoot, err := prepareForkchoiceState(ctx, blk.Block.Slot, r, bytesutil.ToBytes32(blk.Block.ParentRoot), [32]byte{}, ojc, ofc)
 		require.NoError(t, err)
-		require.NoError(t, service.ForkChoicer().InsertNode(ctx, state, blkRoot))
+		require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
 		util.SaveBlock(t, ctx, beaconDB, blk)
 	}

@@ -427,11 +530,6 @@ func TestSaveOrphanedAtts_DoublyLinkedTrie(t *testing.T) {
 }

 func TestSaveOrphanedAtts_CanFilter_DoublyLinkedTrie(t *testing.T) {
-	resetCfg := features.InitWithReset(&features.Flags{
-		DisableForkchoiceDoublyLinkedTree: false,
-	})
-	defer resetCfg()
-
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
@@ -472,7 +570,7 @@ func TestSaveOrphanedAtts_CanFilter_DoublyLinkedTrie(t *testing.T) {
 		require.NoError(t, err)
 		state, blkRoot, err := prepareForkchoiceState(ctx, blk.Block.Slot, r, bytesutil.ToBytes32(blk.Block.ParentRoot), [32]byte{}, ojc, ofc)
 		require.NoError(t, err)
-		require.NoError(t, service.ForkChoicer().InsertNode(ctx, state, blkRoot))
+		require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
 		util.SaveBlock(t, ctx, beaconDB, blk)
 	}

@@ -481,18 +579,9 @@ func TestSaveOrphanedAtts_CanFilter_DoublyLinkedTrie(t *testing.T) {
 }

 func TestUpdateHead_noSavedChanges(t *testing.T) {
-	ctx := context.Background()
+	service, tr := minimalTestService(t)
+	ctx, beaconDB, fcs := tr.ctx, tr.db, tr.fcs

-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-	}
-
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	ojp := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	st, blkRoot, err := prepareForkchoiceState(ctx, 0, [32]byte{}, [32]byte{}, [32]byte{}, ojp, ojp)
 	require.NoError(t, err)
@@ -517,7 +606,9 @@ func TestUpdateHead_noSavedChanges(t *testing.T) {
 	st, blkRoot, err = prepareForkchoiceState(ctx, 0, bellatrixBlkRoot, [32]byte{}, [32]byte{}, fcp, fcp)
 	require.NoError(t, err)
 	require.NoError(t, fcs.InsertNode(ctx, st, blkRoot))
-	newRoot, err := service.cfg.ForkChoiceStore.Head(ctx, []uint64{1, 2})
+	fcs.SetBalancesByRooter(func(context.Context, [32]byte) ([]uint64, error) { return []uint64{1, 2}, nil })
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, &forkchoicetypes.Checkpoint{}))
+	newRoot, err := service.cfg.ForkChoiceStore.Head(ctx)
 	require.NoError(t, err)
 	require.NotEqual(t, headRoot, newRoot)
 	require.Equal(t, headRoot, service.headRoot())
--- a/beacon-chain/blockchain/init_sync_process_block.go
+++ b/beacon-chain/blockchain/init_sync_process_block.go
@@ -4,13 +4,13 @@ import (
 	"context"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
 )

 // This saves a beacon block to the initial sync blocks cache. It rate limits how many blocks
 // the cache keeps in memory (2 epochs worth of blocks) and saves them to DB when it hits this limit.
-func (s *Service) saveInitSyncBlock(ctx context.Context, r [32]byte, b interfaces.SignedBeaconBlock) error {
+func (s *Service) saveInitSyncBlock(ctx context.Context, r [32]byte, b interfaces.ReadOnlySignedBeaconBlock) error {
 	s.initSyncBlocksLock.Lock()
 	s.initSyncBlocks[r] = b
 	numBlocks := len(s.initSyncBlocks)
@@ -43,7 +43,7 @@ func (s *Service) hasBlockInInitSyncOrDB(ctx context.Context, r [32]byte) bool {

 // Returns block for a given root `r` from either the initial sync blocks cache or the DB.
 // Error is returned if the block is not found in either cache or DB.
-func (s *Service) getBlock(ctx context.Context, r [32]byte) (interfaces.SignedBeaconBlock, error) {
+func (s *Service) getBlock(ctx context.Context, r [32]byte) (interfaces.ReadOnlySignedBeaconBlock, error) {
 	s.initSyncBlocksLock.RLock()

 	// Check cache first because it's faster.
@@ -64,11 +64,11 @@ func (s *Service) getBlock(ctx context.Context, r [32]byte) (interfaces.SignedBe

 // This retrieves all the beacon blocks from the initial sync blocks cache, the returned
 // blocks are unordered.
-func (s *Service) getInitSyncBlocks() []interfaces.SignedBeaconBlock {
+func (s *Service) getInitSyncBlocks() []interfaces.ReadOnlySignedBeaconBlock {
 	s.initSyncBlocksLock.RLock()
 	defer s.initSyncBlocksLock.RUnlock()

-	blks := make([]interfaces.SignedBeaconBlock, 0, len(s.initSyncBlocks))
+	blks := make([]interfaces.ReadOnlySignedBeaconBlock, 0, len(s.initSyncBlocks))
 	for _, b := range s.initSyncBlocks {
 		blks = append(blks, b)
 	}
@@ -79,5 +79,5 @@ func (s *Service) getInitSyncBlocks() []interfaces.SignedBeaconBlock {
 func (s *Service) clearInitSyncBlocks() {
 	s.initSyncBlocksLock.Lock()
 	defer s.initSyncBlocksLock.Unlock()
-	s.initSyncBlocks = make(map[[32]byte]interfaces.SignedBeaconBlock)
+	s.initSyncBlocks = make(map[[32]byte]interfaces.ReadOnlySignedBeaconBlock)
 }
--- a/beacon-chain/blockchain/init_sync_process_block_test.go
+++ b/beacon-chain/blockchain/init_sync_process_block_test.go
@@ -4,10 +4,10 @@ import (
 	"context"
 	"testing"

-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
 )

 func TestService_getBlock(t *testing.T) {
--- a/beacon-chain/blockchain/init_test.go
+++ b/beacon-chain/blockchain/init_test.go
@@ -1,7 +1,7 @@
 package blockchain

 import (
-	"github.com/prysmaticlabs/prysm/v3/config/params"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
 )

 func init() {
--- a/beacon-chain/blockchain/log.go
+++ b/beacon-chain/blockchain/log.go
@@ -6,22 +6,22 @@ import (
 	"time"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/blocks"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	consensusBlocks "github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
-	prysmTime "github.com/prysmaticlabs/prysm/v3/time"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/blocks"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	consensus_types "github.com/prysmaticlabs/prysm/v4/consensus-types"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
+	prysmTime "github.com/prysmaticlabs/prysm/v4/time"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"github.com/sirupsen/logrus"
 )

 var log = logrus.WithField("prefix", "blockchain")

 // logs state transition related data every slot.
-func logStateTransitionData(b interfaces.BeaconBlock) error {
+func logStateTransitionData(b interfaces.ReadOnlyBeaconBlock) error {
 	log := log.WithField("slot", b.Slot())
 	if len(b.Body().Attestations()) > 0 {
 		log = log.WithField("attestations", len(b.Body().Attestations()))
@@ -53,20 +53,19 @@ func logStateTransitionData(b interfaces.BeaconBlock) error {
 		log = log.WithField("payloadHash", fmt.Sprintf("%#x", bytesutil.Trunc(p.BlockHash())))
 		txs, err := p.Transactions()
 		switch {
-		case errors.Is(err, consensusBlocks.ErrUnsupportedGetter):
+		case errors.Is(err, consensus_types.ErrUnsupportedField):
 		case err != nil:
 			return err
 		default:
 			log = log.WithField("txCount", len(txs))
 			txsPerSlotCount.Set(float64(len(txs)))
 		}
-
 	}
 	log.Info("Finished applying state transition")
 	return nil
 }

-func logBlockSyncStatus(block interfaces.BeaconBlock, blockRoot [32]byte, justified, finalized *ethpb.Checkpoint, receivedTime time.Time, genesisTime uint64) error {
+func logBlockSyncStatus(block interfaces.ReadOnlyBeaconBlock, blockRoot [32]byte, justified, finalized *ethpb.Checkpoint, receivedTime time.Time, genesisTime uint64) error {
 	startTime, err := slots.ToTime(genesisTime, block.Slot())
 	if err != nil {
 		return err
@@ -102,7 +101,7 @@ func logBlockSyncStatus(block interfaces.BeaconBlock, blockRoot [32]byte, justif
 }

 // logs payload related data every slot.
-func logPayload(block interfaces.BeaconBlock) error {
+func logPayload(block interfaces.ReadOnlyBeaconBlock) error {
 	isExecutionBlk, err := blocks.IsExecutionBlock(block.Body())
 	if err != nil {
 		return errors.Wrap(err, "could not determine if block is execution block")
--- a/beacon-chain/blockchain/log_test.go
+++ b/beacon-chain/blockchain/log_test.go
@@ -3,11 +3,11 @@ package blockchain
 import (
 	"testing"

-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	enginev1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
+	enginev1 "github.com/prysmaticlabs/prysm/v4/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

@@ -25,11 +25,11 @@ func Test_logStateTransitionData(t *testing.T) {
 	require.NoError(t, err)
 	tests := []struct {
 		name string
-		b    func() interfaces.BeaconBlock
+		b    func() interfaces.ReadOnlyBeaconBlock
 		want string
 	}{
 		{name: "empty block body",
-			b: func() interfaces.BeaconBlock {
+			b: func() interfaces.ReadOnlyBeaconBlock {
 				wb, err := blocks.NewBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}})
 				require.NoError(t, err)
 				return wb
@@ -37,7 +37,7 @@ func Test_logStateTransitionData(t *testing.T) {
 			want: "\"Finished applying state transition\" prefix=blockchain slot=0",
 		},
 		{name: "has attestation",
-			b: func() interfaces.BeaconBlock {
+			b: func() interfaces.ReadOnlyBeaconBlock {
 				wb, err := blocks.NewBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{Attestations: []*ethpb.Attestation{{}}}})
 				require.NoError(t, err)
 				return wb
@@ -45,7 +45,7 @@ func Test_logStateTransitionData(t *testing.T) {
 			want: "\"Finished applying state transition\" attestations=1 prefix=blockchain slot=0",
 		},
 		{name: "has deposit",
-			b: func() interfaces.BeaconBlock {
+			b: func() interfaces.ReadOnlyBeaconBlock {
 				wb, err := blocks.NewBeaconBlock(
 					&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
 						Attestations: []*ethpb.Attestation{{}},
@@ -56,7 +56,7 @@ func Test_logStateTransitionData(t *testing.T) {
 			want: "\"Finished applying state transition\" attestations=1 deposits=1 prefix=blockchain slot=0",
 		},
 		{name: "has attester slashing",
-			b: func() interfaces.BeaconBlock {
+			b: func() interfaces.ReadOnlyBeaconBlock {
 				wb, err := blocks.NewBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
 					AttesterSlashings: []*ethpb.AttesterSlashing{{}}}})
 				require.NoError(t, err)
@@ -65,7 +65,7 @@ func Test_logStateTransitionData(t *testing.T) {
 			want: "\"Finished applying state transition\" attesterSlashings=1 prefix=blockchain slot=0",
 		},
 		{name: "has proposer slashing",
-			b: func() interfaces.BeaconBlock {
+			b: func() interfaces.ReadOnlyBeaconBlock {
 				wb, err := blocks.NewBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
 					ProposerSlashings: []*ethpb.ProposerSlashing{{}}}})
 				require.NoError(t, err)
@@ -74,7 +74,7 @@ func Test_logStateTransitionData(t *testing.T) {
 			want: "\"Finished applying state transition\" prefix=blockchain proposerSlashings=1 slot=0",
 		},
 		{name: "has exit",
-			b: func() interfaces.BeaconBlock {
+			b: func() interfaces.ReadOnlyBeaconBlock {
 				wb, err := blocks.NewBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
 					VoluntaryExits: []*ethpb.SignedVoluntaryExit{{}}}})
 				require.NoError(t, err)
@@ -83,7 +83,7 @@ func Test_logStateTransitionData(t *testing.T) {
 			want: "\"Finished applying state transition\" prefix=blockchain slot=0 voluntaryExits=1",
 		},
 		{name: "has everything",
-			b: func() interfaces.BeaconBlock {
+			b: func() interfaces.ReadOnlyBeaconBlock {
 				wb, err := blocks.NewBeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
 					Attestations:      []*ethpb.Attestation{{}},
 					Deposits:          []*ethpb.Deposit{{}},
@@ -96,7 +96,7 @@ func Test_logStateTransitionData(t *testing.T) {
 			want: "\"Finished applying state transition\" attestations=1 attesterSlashings=1 deposits=1 prefix=blockchain proposerSlashings=1 slot=0 voluntaryExits=1",
 		},
 		{name: "has payload",
-			b:    func() interfaces.BeaconBlock { return wrappedPayloadBlk },
+			b:    func() interfaces.ReadOnlyBeaconBlock { return wrappedPayloadBlk },
 			want: "\"Finished applying state transition\" payloadHash=0x010203 prefix=blockchain slot=0 syncBitsCount=0 txCount=2",
 		},
 	}
--- a/beacon-chain/blockchain/metrics.go
+++ b/beacon-chain/blockchain/metrics.go
@@ -6,15 +6,15 @@ import (
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/altair"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/epoch/precompute"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/altair"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/epoch/precompute"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"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"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
 )

 var (
@@ -111,6 +111,18 @@ var (
 		Name: "beacon_reorgs_total",
 		Help: "Count the number of times beacon chain has a reorg",
 	})
+	LateBlockAttemptedReorgCount = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "beacon_late_block_attempted_reorgs",
+		Help: "Count the number of times a proposer served by this beacon has attempted a late block reorg",
+	})
+	lateBlockFailedAttemptFirstThreshold = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "beacon_failed_reorg_attempts_first_threshold",
+		Help: "Count the number of times a proposer served by this beacon attempted a late block reorg but desisted in the first threshold",
+	})
+	lateBlockFailedAttemptSecondThreshold = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "beacon_failed_reorg_attempts_second_threshold",
+		Help: "Count the number of times a proposer served by this beacon attempted a late block reorg but desisted in the second threshold",
+	})
 	saveOrphanedAttCount = promauto.NewCounter(prometheus.CounterOpts{
 		Name: "saved_orphaned_att_total",
 		Help: "Count the number of times an orphaned attestation is saved",
@@ -130,14 +142,6 @@ var (
 		Name: "sync_head_state_hit",
 		Help: "The number of sync head state requests that are present in the cache.",
 	})
-	stateBalanceCacheHit = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "state_balance_cache_hit",
-		Help: "Count the number of state balance cache hits.",
-	})
-	stateBalanceCacheMiss = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "state_balance_cache_miss",
-		Help: "Count the number of state balance cache hits.",
-	})
 	newPayloadValidNodeCount = promauto.NewCounter(prometheus.CounterOpts{
 		Name: "new_payload_valid_node_count",
 		Help: "Count the number of valid nodes after newPayload EE call",
@@ -166,10 +170,6 @@ var (
 		Name: "txs_per_slot_count",
 		Help: "Count the number of txs per slot",
 	})
-	missedPayloadIDFilledCount = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "missed_payload_id_filled_count",
-		Help: "",
-	})
 	onBlockProcessingTime = promauto.NewSummary(prometheus.SummaryOpts{
 		Name: "on_block_processing_milliseconds",
 		Help: "Total time in milliseconds to complete a call to onBlock()",
@@ -353,7 +353,7 @@ func reportEpochMetrics(ctx context.Context, postState, headState state.BeaconSt
 	return nil
 }

-func reportAttestationInclusion(blk interfaces.BeaconBlock) {
+func reportAttestationInclusion(blk interfaces.ReadOnlyBeaconBlock) {
 	for _, att := range blk.Body().Attestations() {
 		attestationInclusionDelay.Observe(float64(blk.Slot() - att.Data.Slot))
 	}
--- a/beacon-chain/blockchain/metrics_test.go
+++ b/beacon-chain/blockchain/metrics_test.go
@@ -4,9 +4,9 @@ import (
 	"context"
 	"testing"

-	eth "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	eth "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
 )

 func TestReportEpochMetrics_BadHeadState(t *testing.T) {
--- a/beacon-chain/blockchain/mock_test.go
+++ b/beacon-chain/blockchain/mock_test.go
@@ -1,23 +1,23 @@
 package blockchain

 import (
-	"context"
-	"errors"
 	"testing"

-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
+	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/doubly-linked-tree"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/startup"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state/stategen"
 )

 func testServiceOptsWithDB(t *testing.T) []Option {
 	beaconDB := testDB.SetupDB(t)
 	fcs := doublylinkedtree.New()
+	cs := startup.NewClockSynchronizer()
 	return []Option{
 		WithDatabase(beaconDB),
 		WithStateGen(stategen.New(beaconDB, fcs)),
 		WithForkChoiceStore(fcs),
+		WithClockSynchronizer(cs),
 	}
 }

@@ -25,26 +25,6 @@ func testServiceOptsWithDB(t *testing.T) []Option {
 // in your code path. this is a lightweight way to satisfy the stategen/beacondb
 // initialization requirements w/o the overhead of db init.
 func testServiceOptsNoDB() []Option {
-	return []Option{
-		withStateBalanceCache(satisfactoryStateBalanceCache()),
-	}
-}
-
-type mockStateByRooter struct {
-	state state.BeaconState
-	err   error
-}
-
-var _ stateByRooter = &mockStateByRooter{}
-
-func (m mockStateByRooter) StateByRoot(_ context.Context, _ [32]byte) (state.BeaconState, error) {
-	return m.state, m.err
-}
-
-// returns an instance of the state balance cache that can be used
-// to satisfy the requirement for one in NewService, but which will
-// always return an error if used.
-func satisfactoryStateBalanceCache() *stateBalanceCache {
-	err := errors.New("satisfactoryStateBalanceCache doesn't perform real caching")
-	return &stateBalanceCache{stateGen: mockStateByRooter{err: err}}
+	cs := startup.NewClockSynchronizer()
+	return []Option{WithClockSynchronizer(cs)}
 }
--- a/beacon-chain/blockchain/options.go
+++ b/beacon-chain/blockchain/options.go
@@ -1,21 +1,22 @@
 package blockchain

 import (
-	"github.com/prysmaticlabs/prysm/v3/async/event"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache/depositcache"
-	statefeed "github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/db"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/execution"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/attestations"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/blstoexec"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/slashings"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/voluntaryexits"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/p2p"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
+	"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/execution"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/attestations"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/blstoexec"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/slashings"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/voluntaryexits"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/p2p"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/startup"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state/stategen"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
 )

 type Option func(s *Service) error
@@ -156,13 +157,6 @@ func WithSlasherAttestationsFeed(f *event.Feed) Option {
 	}
 }

-func withStateBalanceCache(c *stateBalanceCache) Option {
-	return func(s *Service) error {
-		s.justifiedBalances = c
-		return nil
-	}
-}
-
 // WithFinalizedStateAtStartUp to store finalized state at start up.
 func WithFinalizedStateAtStartUp(st state.BeaconState) Option {
 	return func(s *Service) error {
@@ -170,3 +164,11 @@ func WithFinalizedStateAtStartUp(st state.BeaconState) Option {
 		return nil
 	}
 }
+
+func WithClockSynchronizer(gs *startup.ClockSynchronizer) Option {
+	return func(s *Service) error {
+		s.clockSetter = gs
+		s.clockWaiter = gs
+		return nil
+	}
+}
--- a/beacon-chain/blockchain/pow_block.go
+++ b/beacon-chain/blockchain/pow_block.go
@@ -10,19 +10,19 @@ import (
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/holiman/uint256"
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"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"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"github.com/sirupsen/logrus"
 )

 // validateMergeBlock validates terminal block hash in the event of manual overrides before checking for total difficulty.
 //
-// def validate_merge_block(block: BeaconBlock) -> None:
+// def validate_merge_block(block: ReadOnlyBeaconBlock) -> None:
 //
 //	if TERMINAL_BLOCK_HASH != Hash32():
 //	    # If `TERMINAL_BLOCK_HASH` is used as an override, the activation epoch must be reached.
@@ -38,7 +38,7 @@ import (
 //	assert pow_parent is not None
 //	# Check if `pow_block` is a valid terminal PoW block
 //	assert is_valid_terminal_pow_block(pow_block, pow_parent)
-func (s *Service) validateMergeBlock(ctx context.Context, b interfaces.SignedBeaconBlock) error {
+func (s *Service) validateMergeBlock(ctx context.Context, b interfaces.ReadOnlySignedBeaconBlock) error {
 	if err := blocks.BeaconBlockIsNil(b); err != nil {
 		return err
 	}
--- a/beacon-chain/blockchain/pow_block_test.go
+++ b/beacon-chain/blockchain/pow_block_test.go
@@ -1,24 +1,20 @@
 package blockchain

 import (
-	"context"
 	"fmt"
 	"math/big"
 	"testing"

 	gethtypes "github.com/ethereum/go-ethereum/core/types"
 	"github.com/holiman/uint256"
-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	mocks "github.com/prysmaticlabs/prysm/v3/beacon-chain/execution/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	enginev1 "github.com/prysmaticlabs/prysm/v3/proto/engine/v1"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	mocks "github.com/prysmaticlabs/prysm/v4/beacon-chain/execution/testing"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	enginev1 "github.com/prysmaticlabs/prysm/v4/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
 )

 func Test_validTerminalPowBlock(t *testing.T) {
@@ -108,16 +104,8 @@ func Test_validateMergeBlock(t *testing.T) {
 	cfg.TerminalTotalDifficulty = "2"
 	params.OverrideBeaconConfig(cfg)

-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx

 	engine := &mocks.EngineClient{BlockByHashMap: map[[32]byte]*enginev1.ExecutionBlock{}}
 	service.cfg.ExecutionEngineCaller = engine
@@ -158,16 +146,8 @@ func Test_validateMergeBlock(t *testing.T) {
 }

 func Test_getBlkParentHashAndTD(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx

 	engine := &mocks.EngineClient{BlockByHashMap: map[[32]byte]*enginev1.ExecutionBlock{}}
 	service.cfg.ExecutionEngineCaller = engine
@@ -239,17 +219,12 @@ func Test_validateTerminalBlockHash(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, true, ok)

-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, doublylinkedtree.New())),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx
+
 	blk, err := blocks.NewSignedBeaconBlock(util.HydrateSignedBeaconBlockBellatrix(&ethpb.SignedBeaconBlockBellatrix{}))
 	require.NoError(t, err)
-	blk.Block().SetSlot(1)
-	require.NoError(t, blk.Block().Body().SetExecution(wrapped))
+	blk.SetSlot(1)
+	require.NoError(t, blk.SetExecution(wrapped))
 	require.NoError(t, service.validateMergeBlock(ctx, blk))
 }
--- a/beacon-chain/blockchain/process_attestation.go
+++ b/beacon-chain/blockchain/process_attestation.go
@@ -5,12 +5,11 @@ import (
 	"time"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1/attestation"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1/attestation"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"go.opencensus.io/trace"
 )

@@ -37,7 +36,7 @@ import (
 //
 //	 # Update latest messages for attesting indices
 //	 update_latest_messages(store, indexed_attestation.attesting_indices, attestation)
-func (s *Service) OnAttestation(ctx context.Context, a *ethpb.Attestation) error {
+func (s *Service) OnAttestation(ctx context.Context, a *ethpb.Attestation, disparity time.Duration) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onAttestation")
 	defer span.End()

@@ -63,7 +62,7 @@ func (s *Service) OnAttestation(ctx context.Context, a *ethpb.Attestation) error
 	genesisTime := uint64(s.genesisTime.Unix())

 	// Verify attestation target is from current epoch or previous epoch.
-	if err := verifyAttTargetEpoch(ctx, genesisTime, uint64(time.Now().Unix()), tgt); err != nil {
+	if err := verifyAttTargetEpoch(ctx, genesisTime, uint64(time.Now().Add(disparity).Unix()), tgt); err != nil {
 		return err
 	}

@@ -72,11 +71,11 @@ func (s *Service) OnAttestation(ctx context.Context, a *ethpb.Attestation) error
 		return errors.Wrap(err, "could not verify attestation beacon block")
 	}

-	// Note that LMG GHOST and FFG consistency check is ignored because it was performed in sync's validation pipeline:
+	// Note that LMD GHOST and FFG consistency check is ignored because it was performed in sync's validation pipeline:
 	// validate_aggregate_proof.go and validate_beacon_attestation.go

 	// Verify attestations can only affect the fork choice of subsequent slots.
-	if err := slots.VerifyTime(genesisTime, a.Data.Slot+1, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+	if err := slots.VerifyTime(genesisTime, a.Data.Slot+1, disparity); err != nil {
 		return err
 	}

--- a/beacon-chain/blockchain/process_attestation_helpers.go
+++ b/beacon-chain/blockchain/process_attestation_helpers.go
@@ -6,19 +6,30 @@ import (
 	"strconv"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/async"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/transition"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/async"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
+	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/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/time/slots"
 )

 // getAttPreState retrieves the att pre state by either from the cache or the DB.
-func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (state.BeaconState, error) {
+func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (state.ReadOnlyBeaconState, error) {
+	// If the attestation is recent and canonical we can use the head state to compute the shuffling.
+	headEpoch := slots.ToEpoch(s.HeadSlot())
+	if c.Epoch == headEpoch {
+		targetSlot, err := s.cfg.ForkChoiceStore.Slot([32]byte(c.Root))
+		if err == nil && slots.ToEpoch(targetSlot)+1 >= headEpoch {
+			if s.cfg.ForkChoiceStore.IsCanonical([32]byte(c.Root)) {
+				return s.HeadStateReadOnly(ctx)
+			}
+		}
+	}
 	// Use a multilock to allow scoped holding of a mutex by a checkpoint root + epoch
 	// allowing us to behave smarter in terms of how this function is used concurrently.
 	epochKey := strconv.FormatUint(uint64(c.Epoch), 10 /* base 10 */)
@@ -32,7 +43,36 @@ func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (stat
 	if cachedState != nil && !cachedState.IsNil() {
 		return cachedState, nil
 	}
+	// Try the next slot cache for the early epoch calls, this should mostly have been covered already
+	// but is cheap
+	slot, err := slots.EpochStart(c.Epoch)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not compute epoch start")
+	}
+	cachedState = transition.NextSlotState(c.Root, slot)
+	if cachedState != nil && !cachedState.IsNil() {
+		if cachedState.Slot() != slot {
+			cachedState, err = transition.ProcessSlots(ctx, cachedState, slot)
+			if err != nil {
+				return nil, errors.Wrap(err, "could not process slots")
+			}
+		}
+		if err := s.checkpointStateCache.AddCheckpointState(c, cachedState); err != nil {
+			return nil, errors.Wrap(err, "could not save checkpoint state to cache")
+		}
+		return cachedState, nil
+	}

+	// Do not process attestations for old non viable checkpoints otherwise
+	ok, err := s.cfg.ForkChoiceStore.IsViableForCheckpoint(&forkchoicetypes.Checkpoint{Root: [32]byte(c.Root), Epoch: c.Epoch})
+	if err != nil {
+		return nil, errors.Wrap(err, "could not check checkpoint condition in forkchoice")
+	}
+	if !ok {
+		return nil, errors.Wrap(ErrNotCheckpoint, fmt.Sprintf("epoch %d root %#x", c.Epoch, c.Root))
+	}
+
+	// Fallback to state regeneration.
 	baseState, err := s.cfg.StateGen.StateByRoot(ctx, bytesutil.ToBytes32(c.Root))
 	if err != nil {
 		return nil, errors.Wrapf(err, "could not get pre state for epoch %d", c.Epoch)
@@ -55,7 +95,6 @@ func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (stat
 		return nil, errors.Wrap(err, "could not save checkpoint state to cache")
 	}
 	return baseState, nil
-
 }

 // verifyAttTargetEpoch validates attestation is from the current or previous epoch.
--- a/beacon-chain/blockchain/process_attestation_test.go
+++ b/beacon-chain/blockchain/process_attestation_test.go
@@ -5,46 +5,42 @@ import (
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/transition"
-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	forkchoicetypes "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/types"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	fieldparams "github.com/prysmaticlabs/prysm/v3/config/fieldparams"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
+	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/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 )

 func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
+	service, tr := minimalTestService(t)
+	ctx, beaconDB := tr.ctx, tr.db

-	fc := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithForkChoiceStore(fc),
-		WithStateGen(stategen.New(beaconDB, fc)),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
-
-	_, err = blockTree1(t, beaconDB, []byte{'g'})
+	_, err := blockTree1(t, beaconDB, []byte{'g'})
 	require.NoError(t, err)

 	blkWithoutState := util.NewBeaconBlock()
 	blkWithoutState.Block.Slot = 0
 	util.SaveBlock(t, ctx, beaconDB, blkWithoutState)
-	BlkWithOutStateRoot, err := blkWithoutState.Block.HashTreeRoot()
+
+	cp := &ethpb.Checkpoint{}
+	st, blkRoot, err := prepareForkchoiceState(ctx, 0, [32]byte{}, [32]byte{}, params.BeaconConfig().ZeroHash, cp, cp)
 	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))

 	blkWithStateBadAtt := util.NewBeaconBlock()
 	blkWithStateBadAtt.Block.Slot = 1
+	r, err := blkWithStateBadAtt.Block.HashTreeRoot()
+	require.NoError(t, err)
+	cp = &ethpb.Checkpoint{Root: r[:]}
+	st, blkRoot, err = prepareForkchoiceState(ctx, blkWithStateBadAtt.Block.Slot, r, [32]byte{}, params.BeaconConfig().ZeroHash, cp, cp)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))
 	util.SaveBlock(t, ctx, beaconDB, blkWithStateBadAtt)
 	BlkWithStateBadAttRoot, err := blkWithStateBadAtt.Block.HashTreeRoot()
 	require.NoError(t, err)
@@ -55,7 +51,7 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, BlkWithStateBadAttRoot))

 	blkWithValidState := util.NewBeaconBlock()
-	blkWithValidState.Block.Slot = 2
+	blkWithValidState.Block.Slot = 32
 	util.SaveBlock(t, ctx, beaconDB, blkWithValidState)

 	blkWithValidStateRoot, err := blkWithValidState.Block.HashTreeRoot()
@@ -70,6 +66,10 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, blkWithValidStateRoot))

+	service.head = &head{
+		state: st,
+	}
+
 	tests := []struct {
 		name      string
 		a         *ethpb.Attestation
@@ -80,11 +80,6 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
 			a:         util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: params.BeaconConfig().SlotsPerEpoch, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}}}),
 			wantedErr: "slot 32 does not match target epoch 0",
 		},
-		{
-			name:      "no pre state for attestations's target block",
-			a:         util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Target: &ethpb.Checkpoint{Root: BlkWithOutStateRoot[:]}}}),
-			wantedErr: "could not get pre state for epoch 0",
-		},
 		{
 			name: "process attestation doesn't match current epoch",
 			a: util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 100 * params.BeaconConfig().SlotsPerEpoch, Target: &ethpb.Checkpoint{Epoch: 100,
@@ -118,7 +113,7 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {

 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			err := service.OnAttestation(ctx, tt.a)
+			err := service.OnAttestation(ctx, tt.a, 0)
 			if tt.wantedErr != "" {
 				assert.ErrorContains(t, tt.wantedErr, err)
 			} else {
@@ -129,17 +124,9 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
 }

 func TestStore_OnAttestation_Ok_DoublyLinkedTree(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx

-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	genesisState, pks := util.DeterministicGenesisState(t, 64)
 	service.SetGenesisTime(time.Unix(time.Now().Unix()-int64(params.BeaconConfig().SecondsPerSlot), 0))
 	require.NoError(t, service.saveGenesisData(ctx, genesisState))
@@ -155,19 +142,12 @@ func TestStore_OnAttestation_Ok_DoublyLinkedTree(t *testing.T) {
 	state, blkRoot, err := prepareForkchoiceState(ctx, 0, tRoot, tRoot, params.BeaconConfig().ZeroHash, ojc, ofc)
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
-	require.NoError(t, service.OnAttestation(ctx, att[0]))
+	require.NoError(t, service.OnAttestation(ctx, att[0], 0))
 }

 func TestStore_SaveCheckpointState(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, doublylinkedtree.New())),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx

 	s, err := util.NewBeaconState()
 	require.NoError(t, err)
@@ -188,6 +168,9 @@ func TestStore_SaveCheckpointState(t *testing.T) {
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, bytesutil.ToBytes32([]byte{'A'})))
 	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: bytesutil.PadTo([]byte{'A'}, fieldparams.RootLength)}))

+	st, root, err := prepareForkchoiceState(ctx, 1, [32]byte(cp1.Root), [32]byte{}, [32]byte{'R'}, cp1, cp1)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, root))
 	s1, err := service.getAttPreState(ctx, cp1)
 	require.NoError(t, err)
 	assert.Equal(t, 1*params.BeaconConfig().SlotsPerEpoch, s1.Slot(), "Unexpected state slot")
@@ -195,8 +178,17 @@ func TestStore_SaveCheckpointState(t *testing.T) {
 	cp2 := &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'B'}, fieldparams.RootLength)}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, bytesutil.ToBytes32([]byte{'B'})))
 	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: bytesutil.PadTo([]byte{'B'}, fieldparams.RootLength)}))
+
 	s2, err := service.getAttPreState(ctx, cp2)
+	require.ErrorContains(t, "epoch 2 root 0x4200000000000000000000000000000000000000000000000000000000000000: not a checkpoint in forkchoice", err)
+
+	st, root, err = prepareForkchoiceState(ctx, 33, [32]byte(cp2.Root), [32]byte(cp1.Root), [32]byte{'R'}, cp2, cp2)
 	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, root))
+
+	s2, err = service.getAttPreState(ctx, cp2)
+	require.NoError(t, err)
+
 	assert.Equal(t, 2*params.BeaconConfig().SlotsPerEpoch, s2.Slot(), "Unexpected state slot")

 	s1, err = service.getAttPreState(ctx, cp1)
@@ -215,26 +207,30 @@ func TestStore_SaveCheckpointState(t *testing.T) {
 	cp3 := &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'C'}, fieldparams.RootLength)}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, bytesutil.ToBytes32([]byte{'C'})))
 	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: bytesutil.PadTo([]byte{'C'}, fieldparams.RootLength)}))
+	st, root, err = prepareForkchoiceState(ctx, 31, [32]byte(cp3.Root), [32]byte(cp2.Root), [32]byte{'P'}, cp2, cp2)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, root))
+
 	s3, err := service.getAttPreState(ctx, cp3)
 	require.NoError(t, err)
 	assert.Equal(t, s.Slot(), s3.Slot(), "Unexpected state slot")
 }

 func TestStore_UpdateCheckpointState(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, doublylinkedtree.New())),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx
+	baseState, _ := util.DeterministicGenesisState(t, 1)

 	epoch := primitives.Epoch(1)
-	baseState, _ := util.DeterministicGenesisState(t, 1)
-	checkpoint := &ethpb.Checkpoint{Epoch: epoch, Root: bytesutil.PadTo([]byte("hi"), fieldparams.RootLength)}
+	blk := util.NewBeaconBlock()
+	r1, err := blk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	checkpoint := &ethpb.Checkpoint{Epoch: epoch, Root: r1[:]}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, baseState, bytesutil.ToBytes32(checkpoint.Root)))
+	st, blkRoot, err := prepareForkchoiceState(ctx, blk.Block.Slot, r1, [32]byte{}, params.BeaconConfig().ZeroHash, checkpoint, checkpoint)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, r1))
 	returned, err := service.getAttPreState(ctx, checkpoint)
 	require.NoError(t, err)
 	assert.Equal(t, params.BeaconConfig().SlotsPerEpoch.Mul(uint64(checkpoint.Epoch)), returned.Slot(), "Incorrectly returned base state")
@@ -244,8 +240,16 @@ func TestStore_UpdateCheckpointState(t *testing.T) {
 	assert.Equal(t, returned.Slot(), cached.Slot(), "State should have been cached")

 	epoch = 2
-	newCheckpoint := &ethpb.Checkpoint{Epoch: epoch, Root: bytesutil.PadTo([]byte("bye"), fieldparams.RootLength)}
+	blk = util.NewBeaconBlock()
+	blk.Block.Slot = 64
+	r2, err := blk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	newCheckpoint := &ethpb.Checkpoint{Epoch: epoch, Root: r2[:]}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, baseState, bytesutil.ToBytes32(newCheckpoint.Root)))
+	st, blkRoot, err = prepareForkchoiceState(ctx, blk.Block.Slot, r2, r1, params.BeaconConfig().ZeroHash, newCheckpoint, newCheckpoint)
+	require.NoError(t, err)
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, blkRoot))
+	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, st, r2))
 	returned, err = service.getAttPreState(ctx, newCheckpoint)
 	require.NoError(t, err)
 	s, err := slots.EpochStart(newCheckpoint.Epoch)
@@ -325,93 +329,21 @@ func TestVerifyBeaconBlock_OK(t *testing.T) {
 	assert.NoError(t, service.verifyBeaconBlock(ctx, d), "Did not receive the wanted error")
 }

-func TestVerifyFinalizedConsistency_InconsistentRoot_DoublyLinkedTree(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
+func TestGetAttPreState_HeadState(t *testing.T) {
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx
+	baseState, _ := util.DeterministicGenesisState(t, 1)

-	fcs := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fcs)),
-		WithForkChoiceStore(fcs),
-	}
-	service, err := NewService(ctx, opts...)
+	epoch := primitives.Epoch(1)
+	blk := util.NewBeaconBlock()
+	r1, err := blk.Block.HashTreeRoot()
 	require.NoError(t, err)
-
-	b32 := util.NewBeaconBlock()
-	b32.Block.Slot = 32
-	util.SaveBlock(t, ctx, service.cfg.BeaconDB, b32)
-	r32, err := b32.Block.HashTreeRoot()
+	checkpoint := &ethpb.Checkpoint{Epoch: epoch, Root: r1[:]}
+	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, baseState, bytesutil.ToBytes32(checkpoint.Root)))
+	require.NoError(t, transition.UpdateNextSlotCache(ctx, checkpoint.Root, baseState))
+	_, err = service.getAttPreState(ctx, checkpoint)
 	require.NoError(t, err)
-
-	require.NoError(t, service.ForkChoicer().UpdateFinalizedCheckpoint(&forkchoicetypes.Checkpoint{Epoch: 1}))
-	b33 := util.NewBeaconBlock()
-	b33.Block.Slot = 33
-	b33.Block.ParentRoot = r32[:]
-	util.SaveBlock(t, ctx, service.cfg.BeaconDB, b33)
-	r33, err := b33.Block.HashTreeRoot()
-	require.NoError(t, err)
-
-	err = service.VerifyFinalizedConsistency(context.Background(), r33[:])
-	require.ErrorContains(t, "Root and finalized store are not consistent", err)
-}
-
-func TestVerifyFinalizedConsistency_OK(t *testing.T) {
-	ctx := context.Background()
-
-	opts := testServiceOptsWithDB(t)
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
-
-	b32 := util.NewBeaconBlock()
-	b32.Block.Slot = 32
-	util.SaveBlock(t, ctx, service.cfg.BeaconDB, b32)
-	r32, err := b32.Block.HashTreeRoot()
-	require.NoError(t, err)
-
-	require.NoError(t, service.ForkChoicer().UpdateFinalizedCheckpoint(&forkchoicetypes.Checkpoint{Epoch: 1, Root: r32}))
-	b33 := util.NewBeaconBlock()
-	b33.Block.Slot = 33
-	b33.Block.ParentRoot = r32[:]
-	util.SaveBlock(t, ctx, service.cfg.BeaconDB, b33)
-	r33, err := b33.Block.HashTreeRoot()
-	require.NoError(t, err)
-
-	err = service.VerifyFinalizedConsistency(context.Background(), r33[:])
-	require.NoError(t, err)
-}
-
-func TestVerifyFinalizedConsistency_IsCanonical(t *testing.T) {
-	ctx := context.Background()
-
-	opts := testServiceOptsWithDB(t)
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
-
-	b32 := util.NewBeaconBlock()
-	b32.Block.Slot = 32
-	r32, err := b32.Block.HashTreeRoot()
-	require.NoError(t, err)
-
-	b33 := util.NewBeaconBlock()
-	b33.Block.Slot = 33
-	b33.Block.ParentRoot = r32[:]
-	r33, err := b33.Block.HashTreeRoot()
-	require.NoError(t, err)
-
-	ojc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
-	ofc := &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
-	state, blkRoot, err := prepareForkchoiceState(ctx, b32.Block.Slot, r32, [32]byte{}, params.BeaconConfig().ZeroHash, ojc, ofc)
-	require.NoError(t, err)
-	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
-	state, blkRoot, err = prepareForkchoiceState(ctx, b33.Block.Slot, r33, r32, params.BeaconConfig().ZeroHash, ojc, ofc)
-	require.NoError(t, err)
-	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
-
-	jc := &forkchoicetypes.Checkpoint{Epoch: 0, Root: r32}
-	require.NoError(t, service.cfg.ForkChoiceStore.UpdateJustifiedCheckpoint(jc))
-	_, err = service.cfg.ForkChoiceStore.Head(ctx, []uint64{})
-	require.NoError(t, err)
-	err = service.VerifyFinalizedConsistency(context.Background(), r33[:])
+	st, err := service.checkpointStateCache.StateByCheckpoint(checkpoint)
 	require.NoError(t, err)
+	require.Equal(t, params.BeaconConfig().SlotsPerEpoch, st.Slot())
 }
--- a/beacon-chain/blockchain/process_block.go
+++ b/beacon-chain/blockchain/process_block.go
@@ -6,28 +6,27 @@ import (
 	"time"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/async/event"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/blocks"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed"
-	statefeed "github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	coreTime "github.com/prysmaticlabs/prysm/v3/beacon-chain/core/time"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/transition"
-	forkchoicetypes "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/types"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/config/features"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	consensusblocks "github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/crypto/bls"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	"github.com/prysmaticlabs/prysm/v3/monitoring/tracing"
-	ethpbv1 "github.com/prysmaticlabs/prysm/v3/proto/eth/v1"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1/attestation"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"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"
+	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"
+	consensusblocks "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/crypto/bls"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/v4/monitoring/tracing"
+	ethpbv1 "github.com/prysmaticlabs/prysm/v4/proto/eth/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"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"
 )
@@ -47,7 +46,7 @@ var initialSyncBlockCacheSize = uint64(2 * params.BeaconConfig().SlotsPerEpoch)
 //
 // Spec pseudocode definition:
 //
-//	def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
+//	def on_block(store: Store, signed_block: ReadOnlySignedBeaconBlock) -> None:
 //	 block = signed_block.message
 //	 # Parent block must be known
 //	 assert block.parent_root in store.block_states
@@ -93,7 +92,7 @@ var initialSyncBlockCacheSize = uint64(2 * params.BeaconConfig().SlotsPerEpoch)
 //	         ancestor_at_finalized_slot = get_ancestor(store, store.justified_checkpoint.root, finalized_slot)
 //	         if ancestor_at_finalized_slot != store.finalized_checkpoint.root:
 //	             store.justified_checkpoint = state.current_justified_checkpoint
-func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlock, blockRoot [32]byte) error {
+func (s *Service) onBlock(ctx context.Context, signed interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onBlock")
 	defer span.End()
 	if err := consensusblocks.BeaconBlockIsNil(signed); err != nil {
@@ -107,9 +106,14 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 		return err
 	}

+	// Verify that the parent block is in forkchoice
+	if !s.cfg.ForkChoiceStore.HasNode(b.ParentRoot()) {
+		return ErrNotDescendantOfFinalized
+	}
+
 	// Save current justified and finalized epochs for future use.
-	currStoreJustifiedEpoch := s.ForkChoicer().JustifiedCheckpoint().Epoch
-	currStoreFinalizedEpoch := s.ForkChoicer().FinalizedCheckpoint().Epoch
+	currStoreJustifiedEpoch := s.cfg.ForkChoiceStore.JustifiedCheckpoint().Epoch
+	currStoreFinalizedEpoch := s.cfg.ForkChoiceStore.FinalizedCheckpoint().Epoch
 	preStateFinalizedEpoch := preState.FinalizedCheckpoint().Epoch
 	preStateJustifiedEpoch := preState.CurrentJustifiedCheckpoint().Epoch

@@ -137,6 +141,7 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 			return err
 		}
 	}
+
 	if err := s.savePostStateInfo(ctx, blockRoot, signed, postState); err != nil {
 		return err
 	}
@@ -147,9 +152,6 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 	if err := s.handleBlockAttestations(ctx, signed.Block(), postState); err != nil {
 		return errors.Wrap(err, "could not handle block's attestations")
 	}
-	if err := s.handleBlockBLSToExecChanges(signed.Block()); err != nil {
-		return errors.Wrap(err, "could not handle block's BLSToExecutionChanges")
-	}

 	s.InsertSlashingsToForkChoiceStore(ctx, signed.Block().Body().AttesterSlashings())
 	if isValidPayload {
@@ -185,24 +187,18 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 		}()
 	}

-	justified := s.ForkChoicer().JustifiedCheckpoint()
-	balances, err := s.justifiedBalances.get(ctx, justified.Root)
-	if err != nil {
-		msg := fmt.Sprintf("could not read balances for state w/ justified checkpoint %#x", justified.Root)
-		return errors.Wrap(err, msg)
-	}
-
+	justified := s.cfg.ForkChoiceStore.JustifiedCheckpoint()
 	start := time.Now()
-	headRoot, err := s.cfg.ForkChoiceStore.Head(ctx, balances)
+	headRoot, err := s.cfg.ForkChoiceStore.Head(ctx)
 	if err != nil {
 		log.WithError(err).Warn("Could not update head")
 	}
 	if blockRoot != headRoot {
-		receivedWeight, err := s.ForkChoicer().Weight(blockRoot)
+		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.ForkChoicer().Weight(headRoot)
+		headWeight, err := s.cfg.ForkChoiceStore.Weight(headRoot)
 		if err != nil {
 			log.WithField("root", fmt.Sprintf("%#x", headRoot)).Warn("could not determine node weight")
 		}
@@ -212,14 +208,24 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 			"headRoot":       fmt.Sprintf("%#x", headRoot),
 			"headWeight":     headWeight,
 		}).Debug("Head block is not the received block")
+	} else {
+		// Updating next slot state cache can happen in the background. It shouldn't block rest of the process.
+		go func() {
+			// Use a custom deadline here, since this method runs asynchronously.
+			// We ignore the parent method's context and instead create a new one
+			// with a custom deadline, therefore using the background context instead.
+			slotCtx, cancel := context.WithTimeout(context.Background(), slotDeadline)
+			defer cancel()
+			if err := transition.UpdateNextSlotCache(slotCtx, blockRoot[:], postState); err != nil {
+				log.WithError(err).Debug("could not update next slot state cache")
+			}
+		}()
 	}
 	newBlockHeadElapsedTime.Observe(float64(time.Since(start).Milliseconds()))

-	if err := s.notifyEngineIfChangedHead(ctx, headRoot); err != nil {
-		return err
-	}
-
-	if err := s.pruneCanonicalAttsFromPool(ctx, blockRoot, signed); err != nil {
+	// 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
 	}

@@ -234,18 +240,6 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 		},
 	})

-	// Updating next slot state cache can happen in the background. It shouldn't block rest of the process.
-	go func() {
-		// Use a custom deadline here, since this method runs asynchronously.
-		// We ignore the parent method's context and instead create a new one
-		// with a custom deadline, therefore using the background context instead.
-		slotCtx, cancel := context.WithTimeout(context.Background(), slotDeadline)
-		defer cancel()
-		if err := transition.UpdateNextSlotCache(slotCtx, blockRoot[:], postState); err != nil {
-			log.WithError(err).Debug("could not update next slot state cache")
-		}
-	}()
-
 	// Save justified check point to db.
 	postStateJustifiedEpoch := postState.CurrentJustifiedCheckpoint().Epoch
 	if justified.Epoch > currStoreJustifiedEpoch || (justified.Epoch == postStateJustifiedEpoch && justified.Epoch > preStateJustifiedEpoch) {
@@ -258,7 +252,7 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo

 	// Save finalized check point to db and more.
 	postStateFinalizedEpoch := postState.FinalizedCheckpoint().Epoch
-	finalized := s.ForkChoicer().FinalizedCheckpoint()
+	finalized := s.cfg.ForkChoiceStore.FinalizedCheckpoint()
 	if finalized.Epoch > currStoreFinalizedEpoch || (finalized.Epoch == postStateFinalizedEpoch && finalized.Epoch > preStateFinalizedEpoch) {
 		if err := s.updateFinalized(ctx, &ethpb.Checkpoint{Epoch: finalized.Epoch, Root: finalized.Root[:]}); err != nil {
 			return err
@@ -289,7 +283,6 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 				log.WithError(err).Error("Could not insert finalized deposits.")
 			}
 		}()
-
 	}
 	defer reportAttestationInclusion(b)
 	if err := s.handleEpochBoundary(ctx, postState); err != nil {
@@ -317,7 +310,7 @@ func getStateVersionAndPayload(st state.BeaconState) (int, interfaces.ExecutionD
 	return preStateVersion, preStateHeader, nil
 }

-func (s *Service) onBlockBatch(ctx context.Context, blks []interfaces.SignedBeaconBlock,
+func (s *Service) onBlockBatch(ctx context.Context, blks []interfaces.ReadOnlySignedBeaconBlock,
 	blockRoots [][32]byte) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onBlockBatch")
 	defer span.End()
@@ -452,12 +445,22 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []interfaces.SignedBeac
 			}
 		}
 	}
+	// Save boundary states that will be useful for forkchoice
+	for r, st := range boundaries {
+		if err := s.cfg.StateGen.SaveState(ctx, r, st); err != nil {
+			return err
+		}
+	}
+	// Also saves the last post state which to be used as pre state for the next batch.
+	lastBR := blockRoots[len(blks)-1]
+	if err := s.cfg.StateGen.SaveState(ctx, lastBR, preState); err != nil {
+		return err
+	}
 	// Insert all nodes but the last one to forkchoice
-	if err := s.cfg.ForkChoiceStore.InsertOptimisticChain(ctx, pendingNodes); err != nil {
+	if err := s.cfg.ForkChoiceStore.InsertChain(ctx, pendingNodes); err != nil {
 		return errors.Wrap(err, "could not insert batch to forkchoice")
 	}
 	// Insert the last block to forkchoice
-	lastBR := blockRoots[len(blks)-1]
 	if err := s.cfg.ForkChoiceStore.InsertNode(ctx, preState, lastBR); err != nil {
 		return errors.Wrap(err, "could not insert last block in batch to forkchoice")
 	}
@@ -467,17 +470,7 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []interfaces.SignedBeac
 			return errors.Wrap(err, "could not set optimistic block to valid")
 		}
 	}
-
-	for r, st := range boundaries {
-		if err := s.cfg.StateGen.SaveState(ctx, r, st); err != nil {
-			return err
-		}
-	}
-	// Also saves the last post state which to be used as pre state for the next batch.
 	lastB := blks[len(blks)-1]
-	if err := s.cfg.StateGen.SaveState(ctx, lastBR, preState); err != nil {
-		return err
-	}
 	arg := &notifyForkchoiceUpdateArg{
 		headState: preState,
 		headRoot:  lastBR,
@@ -494,6 +487,7 @@ func (s *Service) handleEpochBoundary(ctx context.Context, postState state.Beaco
 	ctx, span := trace.StartSpan(ctx, "blockChain.handleEpochBoundary")
 	defer span.End()

+	var err error
 	if postState.Slot()+1 == s.nextEpochBoundarySlot {
 		copied := postState.Copy()
 		copied, err := transition.ProcessSlots(ctx, copied, copied.Slot()+1)
@@ -508,27 +502,27 @@ func (s *Service) handleEpochBoundary(ctx context.Context, postState state.Beaco
 			return err
 		}
 	} else if postState.Slot() >= s.nextEpochBoundarySlot {
-		s.headLock.RLock()
-		st := s.head.state
-		s.headLock.RUnlock()
-		if err := reportEpochMetrics(ctx, postState, st); err != nil {
-			return err
-		}
-
-		var err error
 		s.nextEpochBoundarySlot, err = slots.EpochStart(coreTime.NextEpoch(postState))
 		if err != nil {
 			return err
 		}

 		// Update caches at epoch boundary slot.
-		// The following updates have short cut to return nil cheaply if fulfilled during boundary slot - 1.
+		// The following updates have shortcut to return nil cheaply if fulfilled during boundary slot - 1.
 		if err := helpers.UpdateCommitteeCache(ctx, postState, coreTime.CurrentEpoch(postState)); err != nil {
 			return err
 		}
 		if err := helpers.UpdateProposerIndicesInCache(ctx, postState); err != nil {
 			return err
 		}
+
+		headSt, err := s.HeadState(ctx)
+		if err != nil {
+			return err
+		}
+		if err := reportEpochMetrics(ctx, postState, headSt); err != nil {
+			return err
+		}
 	}

 	return nil
@@ -536,7 +530,7 @@ func (s *Service) handleEpochBoundary(ctx context.Context, postState state.Beaco

 // This feeds in the block to fork choice store. It's allows fork choice store
 // to gain information on the most current chain.
-func (s *Service) insertBlockToForkchoiceStore(ctx context.Context, blk interfaces.BeaconBlock, root [32]byte, st state.BeaconState) error {
+func (s *Service) insertBlockToForkchoiceStore(ctx context.Context, blk interfaces.ReadOnlyBeaconBlock, root [32]byte, st state.BeaconState) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.insertBlockToForkchoiceStore")
 	defer span.End()

@@ -553,7 +547,7 @@ func (s *Service) insertBlockToForkchoiceStore(ctx context.Context, blk interfac

 // This feeds in the attestations included in the block to fork choice store. It's allows fork choice store
 // to gain information on the most current chain.
-func (s *Service) handleBlockAttestations(ctx context.Context, blk interfaces.BeaconBlock, st state.BeaconState) error {
+func (s *Service) handleBlockAttestations(ctx context.Context, blk interfaces.ReadOnlyBeaconBlock, st state.BeaconState) error {
 	// Feed in block's attestations to fork choice store.
 	for _, a := range blk.Body().Attestations() {
 		committee, err := helpers.BeaconCommitteeFromState(ctx, st, a.Data.Slot, a.Data.CommitteeIndex)
@@ -576,18 +570,19 @@ func (s *Service) handleBlockAttestations(ctx context.Context, blk interfaces.Be

 // InsertSlashingsToForkChoiceStore inserts attester slashing indices to fork choice store.
 // To call this function, it's caller's responsibility to ensure the slashing object is valid.
+// This function requires a write lock on forkchoice.
 func (s *Service) InsertSlashingsToForkChoiceStore(ctx context.Context, slashings []*ethpb.AttesterSlashing) {
 	for _, slashing := range slashings {
 		indices := blocks.SlashableAttesterIndices(slashing)
 		for _, index := range indices {
-			s.ForkChoicer().InsertSlashedIndex(ctx, primitives.ValidatorIndex(index))
+			s.cfg.ForkChoiceStore.InsertSlashedIndex(ctx, primitives.ValidatorIndex(index))
 		}
 	}
 }

 // This saves post state info to DB or cache. This also saves post state info to fork choice store.
 // Post state info consists of processed block and state. Do not call this method unless the block and state are verified.
-func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b interfaces.SignedBeaconBlock, st state.BeaconState) error {
+func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b interfaces.ReadOnlySignedBeaconBlock, st state.BeaconState) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.savePostStateInfo")
 	defer span.End()
 	if err := s.cfg.BeaconDB.SaveBlock(ctx, b); err != nil {
@@ -599,18 +594,9 @@ func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b interface
 	return nil
 }

-// This removes the attestations from the mem pool. It will only remove the attestations if input root `r` is canonical,
-// meaning the block `b` is part of the canonical chain.
-func (s *Service) pruneCanonicalAttsFromPool(ctx context.Context, r [32]byte, b interfaces.SignedBeaconBlock) error {
-	canonical, err := s.IsCanonical(ctx, r)
-	if err != nil {
-		return err
-	}
-	if !canonical {
-		return nil
-	}
-
-	atts := b.Block().Body().Attestations()
+// This removes the attestations in block `b` from the attestation mem pool.
+func (s *Service) pruneAttsFromPool(headBlock interfaces.ReadOnlySignedBeaconBlock) error {
+	atts := headBlock.Block().Body().Attestations()
 	for _, att := range atts {
 		if helpers.IsAggregated(att) {
 			if err := s.cfg.AttPool.DeleteAggregatedAttestation(att); err != nil {
@@ -626,7 +612,7 @@ func (s *Service) pruneCanonicalAttsFromPool(ctx context.Context, r [32]byte, b
 }

 // validateMergeTransitionBlock validates the merge transition block.
-func (s *Service) validateMergeTransitionBlock(ctx context.Context, stateVersion int, stateHeader interfaces.ExecutionData, blk interfaces.SignedBeaconBlock) error {
+func (s *Service) validateMergeTransitionBlock(ctx context.Context, stateVersion int, stateHeader interfaces.ExecutionData, blk interfaces.ReadOnlySignedBeaconBlock) error {
 	// Skip validation if block is older than Bellatrix.
 	if blocks.IsPreBellatrixVersion(blk.Block().Version()) {
 		return nil
@@ -665,66 +651,72 @@ func (s *Service) validateMergeTransitionBlock(ctx context.Context, stateVersion

 // This routine checks if there is a cached proposer payload ID available for the next slot proposer.
 // If there is not, it will call forkchoice updated with the correct payload attribute then cache the payload ID.
-func (s *Service) fillMissingPayloadIDRoutine(ctx context.Context, stateFeed *event.Feed) {
-	// Wait for state to be initialized.
-	stateChannel := make(chan *feed.Event, 1)
-	stateSub := stateFeed.Subscribe(stateChannel)
-	go func() {
+func (s *Service) runLateBlockTasks() {
+	_, err := s.clockWaiter.WaitForClock(s.ctx)
+	if err != nil {
+		log.WithError(err).Error("runLateBlockTasks encountered an error waiting for initialization")
+		return
+	}
+	attThreshold := params.BeaconConfig().SecondsPerSlot / 3
+	ticker := slots.NewSlotTickerWithOffset(s.genesisTime, time.Duration(attThreshold)*time.Second, params.BeaconConfig().SecondsPerSlot)
+	for {
 		select {
+		case <-ticker.C():
+			s.lateBlockTasks(s.ctx)
+
 		case <-s.ctx.Done():
-			stateSub.Unsubscribe()
+			log.Debug("Context closed, exiting routine")
 			return
-		case <-stateChannel:
-			stateSub.Unsubscribe()
-			break
 		}
-
-		ticker := time.NewTicker(time.Second)
-		defer ticker.Stop()
-		for {
-			select {
-			case ti := <-ticker.C:
-				if err := s.fillMissingBlockPayloadId(ctx, ti); err != nil {
-					log.WithError(err).Error("Could not fill missing payload ID")
-				}
-			case <-s.ctx.Done():
-				log.Debug("Context closed, exiting routine")
-				return
-			}
-		}
-	}()
+	}
 }

-// Returns true if time `t` is halfway through the slot in sec.
-func atHalfSlot(t time.Time) bool {
-	s := params.BeaconConfig().SecondsPerSlot
-	return uint64(t.Second())%s == s/2
-}
+// lateBlockTasks  is called 4 seconds into the slot and performs tasks
+// related to late blocks. It emits a MissedSlot state feed event.
+// It calls FCU and sets the right attributes if we are proposing next slot
+// it also updates the next slot cache to deal with skipped slots.
+func (s *Service) lateBlockTasks(ctx context.Context) {
+	if s.CurrentSlot() == s.HeadSlot() {
+		return
+	}
+	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.MissedSlot,
+	})

-func (s *Service) fillMissingBlockPayloadId(ctx context.Context, ti time.Time) error {
-	if !atHalfSlot(ti) {
-		return nil
+	headRoot := s.headRoot()
+	headState := s.headState(ctx)
+	lastRoot, lastState := transition.LastCachedState()
+	if lastState == nil {
+		lastRoot, lastState = headRoot[:], headState
 	}
-	if s.CurrentSlot() == s.cfg.ForkChoiceStore.HighestReceivedBlockSlot() {
-		return nil
+	// Copy all the field tries in our cached state in the event of late
+	// blocks.
+	lastState.CopyAllTries()
+	if err := transition.UpdateNextSlotCache(ctx, lastRoot, lastState); err != nil {
+		log.WithError(err).Debug("could not update next slot state cache")
 	}
+
 	// 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 && id == [8]byte{} {
-		missedPayloadIDFilledCount.Inc()
-		headBlock, err := s.headBlock()
-		if err != nil {
-			return err
-		} else {
-			if _, err := s.notifyForkchoiceUpdate(ctx, &notifyForkchoiceUpdateArg{
-				headState: s.headState(ctx),
-				headRoot:  s.headRoot(),
-				headBlock: headBlock.Block(),
-			}); err != nil {
-				return err
-			}
-		}
+	if (!has && !features.Get().PrepareAllPayloads) || id != [8]byte{} {
+		return
+	}
+
+	s.headLock.RLock()
+	headBlock, err := s.headBlock()
+	if err != nil {
+		s.headLock.RUnlock()
+		log.WithError(err).Debug("could not perform late block tasks: failed to retrieve head block")
+		return
+	}
+	s.headLock.RUnlock()
+	_, err = s.notifyForkchoiceUpdate(ctx, &notifyForkchoiceUpdateArg{
+		headState: headState,
+		headRoot:  headRoot,
+		headBlock: headBlock.Block(),
+	})
+	if err != nil {
+		log.WithError(err).Debug("could not perform late block tasks: failed to update forkchoice with engine")
 	}
-	return nil
 }
--- a/beacon-chain/blockchain/process_block_helpers.go
+++ b/beacon-chain/blockchain/process_block_helpers.go
@@ -1,22 +1,20 @@
 package blockchain

 import (
-	"bytes"
 	"context"
 	"fmt"

 	"github.com/pkg/errors"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	forkchoicetypes "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/types"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	mathutil "github.com/prysmaticlabs/prysm/v3/math"
-	"github.com/prysmaticlabs/prysm/v3/monitoring/tracing"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	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/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"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"go.opencensus.io/trace"
 )

@@ -28,7 +26,7 @@ func (s *Service) CurrentSlot() primitives.Slot {
 // 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.
-func (s *Service) getBlockPreState(ctx context.Context, b interfaces.BeaconBlock) (state.BeaconState, error) {
+func (s *Service) getBlockPreState(ctx context.Context, b interfaces.ReadOnlyBeaconBlock) (state.BeaconState, error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.getBlockPreState")
 	defer span.End()

@@ -59,22 +57,18 @@ func (s *Service) getBlockPreState(ctx context.Context, b interfaces.BeaconBlock
 }

 // verifyBlkPreState validates input block has a valid pre-state.
-func (s *Service) verifyBlkPreState(ctx context.Context, b interfaces.BeaconBlock) error {
+func (s *Service) verifyBlkPreState(ctx context.Context, b interfaces.ReadOnlyBeaconBlock) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.verifyBlkPreState")
 	defer span.End()

 	parentRoot := b.ParentRoot()
 	// Loosen the check to HasBlock because state summary gets saved in batches
 	// during initial syncing. There's no risk given a state summary object is just a
-	// a subset of the block object.
+	// subset of the block object.
 	if !s.cfg.BeaconDB.HasStateSummary(ctx, parentRoot) && !s.cfg.BeaconDB.HasBlock(ctx, parentRoot) {
 		return errors.New("could not reconstruct parent state")
 	}

-	if err := s.VerifyFinalizedBlkDescendant(ctx, parentRoot); err != nil {
-		return err
-	}
-
 	has, err := s.cfg.StateGen.HasState(ctx, parentRoot)
 	if err != nil {
 		return err
@@ -88,39 +82,10 @@ func (s *Service) verifyBlkPreState(ctx context.Context, b interfaces.BeaconBloc
 	return nil
 }

-// VerifyFinalizedBlkDescendant validates if input block root is a descendant of the
-// current finalized block root.
-func (s *Service) VerifyFinalizedBlkDescendant(ctx context.Context, root [32]byte) error {
-	ctx, span := trace.StartSpan(ctx, "blockChain.VerifyFinalizedBlkDescendant")
-	defer span.End()
-	finalized := s.ForkChoicer().FinalizedCheckpoint()
-	fRoot := s.ensureRootNotZeros(finalized.Root)
-	fSlot, err := slots.EpochStart(finalized.Epoch)
-	if err != nil {
-		return err
-	}
-	bFinalizedRoot, err := s.ancestor(ctx, root[:], fSlot)
-	if err != nil {
-		return errors.Wrap(err, "could not get finalized block root")
-	}
-	if bFinalizedRoot == nil {
-		return fmt.Errorf("no finalized block known for block %#x", bytesutil.Trunc(root[:]))
-	}
-
-	if !bytes.Equal(bFinalizedRoot, fRoot[:]) {
-		err := fmt.Errorf("block %#x is not a descendant of the current finalized block slot %d, %#x != %#x",
-			bytesutil.Trunc(root[:]), fSlot, bytesutil.Trunc(bFinalizedRoot),
-			bytesutil.Trunc(fRoot[:]))
-		tracing.AnnotateError(span, err)
-		return invalidBlock{error: err}
-	}
-	return nil
-}
-
 // verifyBlkFinalizedSlot validates input block is not less than or equal
 // to current finalized slot.
-func (s *Service) verifyBlkFinalizedSlot(b interfaces.BeaconBlock) error {
-	finalized := s.ForkChoicer().FinalizedCheckpoint()
+func (s *Service) verifyBlkFinalizedSlot(b interfaces.ReadOnlyBeaconBlock) error {
+	finalized := s.cfg.ForkChoiceStore.FinalizedCheckpoint()
 	finalizedSlot, err := slots.EpochStart(finalized.Epoch)
 	if err != nil {
 		return err
@@ -181,68 +146,25 @@ func (s *Service) updateFinalized(ctx context.Context, cp *ethpb.Checkpoint) err
 	return nil
 }

-// ancestor returns the block root of an ancestry block from the input block root.
-//
-// Spec pseudocode definition:
-//
-//	def get_ancestor(store: Store, root: Root, slot: Slot) -> Root:
-//	 block = store.blocks[root]
-//	 if block.slot > slot:
-//	     return get_ancestor(store, block.parent_root, slot)
-//	 elif block.slot == slot:
-//	     return root
-//	 else:
-//	     # root is older than queried slot, thus a skip slot. Return most recent root prior to slot
-//	     return root
-func (s *Service) ancestor(ctx context.Context, root []byte, slot primitives.Slot) ([]byte, error) {
-	ctx, span := trace.StartSpan(ctx, "blockChain.ancestor")
-	defer span.End()
-
-	r := bytesutil.ToBytes32(root)
-	// Get ancestor root from fork choice store instead of recursively looking up blocks in DB.
-	// This is most optimal outcome.
-	ar, err := s.ancestorByForkChoiceStore(ctx, r, slot)
-	if err != nil {
-		// Try getting ancestor root from DB when failed to retrieve from fork choice store.
-		// This is the second line of defense for retrieving ancestor root.
-		ar, err = s.ancestorByDB(ctx, r, slot)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return ar, nil
-}
-
-// This retrieves an ancestor root using fork choice store. The look up is looping through the a flat array structure.
-func (s *Service) ancestorByForkChoiceStore(ctx context.Context, r [32]byte, slot primitives.Slot) ([]byte, error) {
-	ctx, span := trace.StartSpan(ctx, "blockChain.ancestorByForkChoiceStore")
-	defer span.End()
-
-	if !s.cfg.ForkChoiceStore.HasParent(r) {
-		return nil, errors.New("could not find root in fork choice store")
-	}
-	root, err := s.cfg.ForkChoiceStore.AncestorRoot(ctx, r, slot)
-	return root[:], err
-}
-
 // This retrieves an ancestor root using DB. The look up is recursively looking up DB. Slower than `ancestorByForkChoiceStore`.
-func (s *Service) ancestorByDB(ctx context.Context, r [32]byte, slot primitives.Slot) ([]byte, error) {
+func (s *Service) ancestorByDB(ctx context.Context, r [32]byte, slot primitives.Slot) (root [32]byte, err error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.ancestorByDB")
 	defer span.End()

+	root = [32]byte{}
 	// Stop recursive ancestry lookup if context is cancelled.
 	if ctx.Err() != nil {
-		return nil, ctx.Err()
+		err = ctx.Err()
+		return
 	}

 	signed, err := s.getBlock(ctx, r)
 	if err != nil {
-		return nil, err
+		return root, err
 	}
 	b := signed.Block()
 	if b.Slot() == slot || b.Slot() < slot {
-		return r[:], nil
+		return r, nil
 	}

 	return s.ancestorByDB(ctx, b.ParentRoot(), slot)
@@ -250,12 +172,12 @@ func (s *Service) ancestorByDB(ctx context.Context, r [32]byte, slot primitives.

 // This retrieves missing blocks from DB (ie. the blocks that couldn't be received over sync) and inserts them to fork choice store.
 // This is useful for block tree visualizer and additional vote accounting.
-func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk interfaces.BeaconBlock,
+func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk interfaces.ReadOnlyBeaconBlock,
 	fCheckpoint, jCheckpoint *ethpb.Checkpoint) error {
 	pendingNodes := make([]*forkchoicetypes.BlockAndCheckpoints, 0)

 	// Fork choice only matters from last finalized slot.
-	finalized := s.ForkChoicer().FinalizedCheckpoint()
+	finalized := s.cfg.ForkChoiceStore.FinalizedCheckpoint()
 	fSlot, err := slots.EpochStart(finalized.Epoch)
 	if err != nil {
 		return err
@@ -281,10 +203,10 @@ func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk interfa
 	if len(pendingNodes) == 1 {
 		return nil
 	}
-	if root != s.ensureRootNotZeros(finalized.Root) && !s.ForkChoicer().HasNode(root) {
-		return errNotDescendantOfFinalized
+	if root != s.ensureRootNotZeros(finalized.Root) && !s.cfg.ForkChoiceStore.HasNode(root) {
+		return ErrNotDescendantOfFinalized
 	}
-	return s.cfg.ForkChoiceStore.InsertOptimisticChain(ctx, pendingNodes)
+	return s.cfg.ForkChoiceStore.InsertChain(ctx, pendingNodes)
 }

 // inserts finalized deposits into our finalized deposit trie.
@@ -308,7 +230,9 @@ func (s *Service) insertFinalizedDeposits(ctx context.Context, fRoot [32]byte) e
 	// to be included(rather than the last one to be processed). This was most likely
 	// done as the state cannot represent signed integers.
 	eth1DepositIndex -= 1
-	s.cfg.DepositCache.InsertFinalizedDeposits(ctx, int64(eth1DepositIndex))
+	if err = s.cfg.DepositCache.InsertFinalizedDeposits(ctx, int64(eth1DepositIndex)); err != nil {
+		return err
+	}
 	// Deposit proofs are only used during state transition and can be safely removed to save space.
 	if err = s.cfg.DepositCache.PruneProofs(ctx, int64(eth1DepositIndex)); err != nil {
 		return errors.Wrap(err, "could not prune deposit proofs")
--- a/beacon-chain/blockchain/process_block_test.go
+++ b/beacon-chain/blockchain/process_block_test.go
--- a/beacon-chain/blockchain/receive_attestation.go
+++ b/beacon-chain/blockchain/receive_attestation.go
@@ -7,33 +7,37 @@ import (
 	"time"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/async/event"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"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"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )

+// reorgLateBlockCountAttestations is the time until the end of the slot in which we count
+// attestations to see if we will reorg the incoming block
+const reorgLateBlockCountAttestations = 2 * time.Second
+
 // AttestationStateFetcher allows for retrieving a beacon state corresponding to the block
 // root of an attestation's target checkpoint.
 type AttestationStateFetcher interface {
-	AttestationTargetState(ctx context.Context, target *ethpb.Checkpoint) (state.BeaconState, error)
+	AttestationTargetState(ctx context.Context, target *ethpb.Checkpoint) (state.ReadOnlyBeaconState, error)
 }

 // AttestationReceiver interface defines the methods of chain service receive and processing new attestations.
 type AttestationReceiver interface {
 	AttestationStateFetcher
 	VerifyLmdFfgConsistency(ctx context.Context, att *ethpb.Attestation) error
-	VerifyFinalizedConsistency(ctx context.Context, root []byte) error
+	InForkchoice([32]byte) bool
 }

 // AttestationTargetState returns the pre state of attestation.
-func (s *Service) AttestationTargetState(ctx context.Context, target *ethpb.Checkpoint) (state.BeaconState, error) {
+func (s *Service) AttestationTargetState(ctx context.Context, target *ethpb.Checkpoint) (state.ReadOnlyBeaconState, error) {
 	ss, err := slots.EpochStart(target.Epoch)
 	if err != nil {
 		return nil, err
@@ -41,6 +45,9 @@ func (s *Service) AttestationTargetState(ctx context.Context, target *ethpb.Chec
 	if err := slots.ValidateClock(ss, uint64(s.genesisTime.Unix())); err != nil {
 		return nil, err
 	}
+	// We acquire the lock here instead than on gettAttPreState because that function gets called from UpdateHead that holds a write lock
+	s.cfg.ForkChoiceStore.RLock()
+	defer s.cfg.ForkChoiceStore.RUnlock()
 	return s.getAttPreState(ctx, target)
 }

@@ -50,7 +57,7 @@ func (s *Service) VerifyLmdFfgConsistency(ctx context.Context, a *ethpb.Attestat
 	if err != nil {
 		return err
 	}
-	r, err := s.ancestor(ctx, a.Data.BeaconBlockRoot, targetSlot)
+	r, err := s.Ancestor(ctx, a.Data.BeaconBlockRoot, targetSlot)
 	if err != nil {
 		return err
 	}
@@ -60,48 +67,14 @@ func (s *Service) VerifyLmdFfgConsistency(ctx context.Context, a *ethpb.Attestat
 	return nil
 }

-// VerifyFinalizedConsistency verifies input root is consistent with finalized store.
-// When the input root is not be consistent with finalized store then we know it is not
-// on the finalized check point that leads to current canonical chain and should be rejected accordingly.
-func (s *Service) VerifyFinalizedConsistency(ctx context.Context, root []byte) error {
-	// A canonical root implies the root to has an ancestor that aligns with finalized check point.
-	// In this case, we could exit early to save on additional computation.
-	blockRoot := bytesutil.ToBytes32(root)
-	if s.cfg.ForkChoiceStore.HasNode(blockRoot) && s.cfg.ForkChoiceStore.IsCanonical(blockRoot) {
-		return nil
-	}
-
-	f := s.FinalizedCheckpt()
-	ss, err := slots.EpochStart(f.Epoch)
-	if err != nil {
-		return err
-	}
-	r, err := s.ancestor(ctx, root, ss)
-	if err != nil {
-		return err
-	}
-	if !bytes.Equal(f.Root, r) {
-		return errors.New("Root and finalized store are not consistent")
-	}
-
-	return nil
-}
-
 // This routine processes fork choice attestations from the pool to account for validator votes and fork choice.
-func (s *Service) spawnProcessAttestationsRoutine(stateFeed *event.Feed) {
-	// Wait for state to be initialized.
-	stateChannel := make(chan *feed.Event, 1)
-	stateSub := stateFeed.Subscribe(stateChannel)
+func (s *Service) spawnProcessAttestationsRoutine() {
 	go func() {
-		select {
-		case <-s.ctx.Done():
-			stateSub.Unsubscribe()
+		_, err := s.clockWaiter.WaitForClock(s.ctx)
+		if err != nil {
+			log.WithError(err).Error("spawnProcessAttestationsRoutine failed to receive genesis data")
 			return
-		case <-stateChannel:
-			stateSub.Unsubscribe()
-			break
 		}
-
 		if s.genesisTime.IsZero() {
 			log.Warn("ProcessAttestations routine waiting for genesis time")
 			for s.genesisTime.IsZero() {
@@ -115,108 +88,78 @@ func (s *Service) spawnProcessAttestationsRoutine(stateFeed *event.Feed) {
 		}

 		st := slots.NewSlotTicker(s.genesisTime, params.BeaconConfig().SecondsPerSlot)
+		pat := slots.NewSlotTickerWithOffset(s.genesisTime, -reorgLateBlockCountAttestations, params.BeaconConfig().SecondsPerSlot)
 		for {
 			select {
 			case <-s.ctx.Done():
 				return
+			case <-pat.C():
+				s.UpdateHead(s.ctx, s.CurrentSlot()+1)
 			case <-st.C():
-				if err := s.ForkChoicer().NewSlot(s.ctx, s.CurrentSlot()); err != nil {
-					log.WithError(err).Error("Could not process new slot")
+				s.cfg.ForkChoiceStore.Lock()
+				if err := s.cfg.ForkChoiceStore.NewSlot(s.ctx, s.CurrentSlot()); err != nil {
+					log.WithError(err).Error("could not process new slot")
 				}
+				s.cfg.ForkChoiceStore.Unlock()

-				if err := s.UpdateHead(s.ctx); err != nil {
-					log.WithError(err).Error("Could not process attestations and update head")
-				}
+				s.UpdateHead(s.ctx, s.CurrentSlot())
 			}
 		}
 	}()
 }

 // UpdateHead updates the canonical head of the chain based on information from fork-choice attestations and votes.
-// It requires no external inputs.
-func (s *Service) UpdateHead(ctx context.Context) error {
-	// Only one process can process attestations and update head at a time.
-	s.processAttestationsLock.Lock()
-	defer s.processAttestationsLock.Unlock()
+// The caller of this function MUST hold a lock in forkchoice
+func (s *Service) UpdateHead(ctx context.Context, proposingSlot primitives.Slot) {
+	ctx, span := trace.StartSpan(ctx, "beacon-chain.blockchain.UpdateHead")
+	defer span.End()

 	start := time.Now()
-	s.processAttestations(ctx)
+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
+	// This function is only called at 10 seconds or 0 seconds into the slot
+	disparity := params.BeaconNetworkConfig().MaximumGossipClockDisparity
+	if !features.Get().DisableReorgLateBlocks {
+		disparity += reorgLateBlockCountAttestations
+	}
+	s.processAttestations(ctx, disparity)
+
 	processAttsElapsedTime.Observe(float64(time.Since(start).Milliseconds()))

-	justified := s.ForkChoicer().JustifiedCheckpoint()
-	balances, err := s.justifiedBalances.get(ctx, justified.Root)
-	if err != nil {
-		return err
-	}
 	start = time.Now()
-	newHeadRoot, err := s.cfg.ForkChoiceStore.Head(ctx, balances)
+	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()
 	}
 	newAttHeadElapsedTime.Observe(float64(time.Since(start).Milliseconds()))

-	s.headLock.RLock()
-	if s.headRoot() != newHeadRoot {
+	changed, err := s.forkchoiceUpdateWithExecution(s.ctx, newHeadRoot, proposingSlot)
+	if err != nil {
+		log.WithError(err).Error("could not update forkchoice")
+	}
+	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 err := s.notifyEngineIfChangedHead(ctx, newHeadRoot); err != nil {
-		return err
-	}
-	return nil
-}
-
-// This calls notify Forkchoice Update in the event that the head has changed
-func (s *Service) notifyEngineIfChangedHead(ctx context.Context, newHeadRoot [32]byte) error {
-	s.headLock.RLock()
-	if newHeadRoot == [32]byte{} || s.headRoot() == newHeadRoot {
 		s.headLock.RUnlock()
-		return nil
 	}
-	s.headLock.RUnlock()
-
-	if !s.hasBlockInInitSyncOrDB(ctx, newHeadRoot) {
-		log.Debug("New head does not exist in DB. Do nothing")
-		return nil // We don't have the block, don't notify the engine and update head.
-	}
-
-	newHeadBlock, err := s.getBlock(ctx, newHeadRoot)
-	if err != nil {
-		log.WithError(err).Error("Could not get new head block")
-		return nil
-	}
-	headState, err := s.cfg.StateGen.StateByRoot(ctx, newHeadRoot)
-	if err != nil {
-		log.WithError(err).Error("Could not get state from db")
-		return nil
-	}
-	arg := &notifyForkchoiceUpdateArg{
-		headState: headState,
-		headRoot:  newHeadRoot,
-		headBlock: newHeadBlock.Block(),
-	}
-	_, err = s.notifyForkchoiceUpdate(s.ctx, arg)
-	if err != nil {
-		return err
-	}
-	if err := s.saveHead(ctx, newHeadRoot, newHeadBlock, headState); err != nil {
-		log.WithError(err).Error("could not save head")
-	}
-	return nil
 }

 // This processes fork choice attestations from the pool to account for validator votes and fork choice.
-func (s *Service) processAttestations(ctx context.Context) {
+func (s *Service) processAttestations(ctx context.Context, disparity time.Duration) {
 	atts := s.cfg.AttPool.ForkchoiceAttestations()
 	for _, a := range atts {
 		// Based on the spec, don't process the attestation until the subsequent slot.
 		// This delays consideration in the fork choice until their slot is in the past.
 		// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/fork-choice.md#validate_on_attestation
 		nextSlot := a.Data.Slot + 1
-		if err := slots.VerifyTime(uint64(s.genesisTime.Unix()), nextSlot, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+		if err := slots.VerifyTime(uint64(s.genesisTime.Unix()), nextSlot, disparity); err != nil {
 			continue
 		}

@@ -234,7 +177,7 @@ func (s *Service) processAttestations(ctx context.Context) {
 			continue
 		}

-		if err := s.receiveAttestationNoPubsub(ctx, a); err != nil {
+		if err := s.receiveAttestationNoPubsub(ctx, a, disparity); err != nil {
 			log.WithFields(logrus.Fields{
 				"slot":             a.Data.Slot,
 				"committeeIndex":   a.Data.CommitteeIndex,
@@ -251,11 +194,11 @@ func (s *Service) processAttestations(ctx context.Context) {
 //  1. Validate attestation, update validator's latest vote
 //  2. Apply fork choice to the processed attestation
 //  3. Save latest head info
-func (s *Service) receiveAttestationNoPubsub(ctx context.Context, att *ethpb.Attestation) error {
+func (s *Service) receiveAttestationNoPubsub(ctx context.Context, att *ethpb.Attestation, disparity time.Duration) error {
 	ctx, span := trace.StartSpan(ctx, "beacon-chain.blockchain.receiveAttestationNoPubsub")
 	defer span.End()

-	if err := s.OnAttestation(ctx, att); err != nil {
+	if err := s.OnAttestation(ctx, att, disparity); err != nil {
 		return errors.Wrap(err, "could not process attestation")
 	}

--- a/beacon-chain/blockchain/receive_attestation_test.go
+++ b/beacon-chain/blockchain/receive_attestation_test.go
@@ -5,21 +5,18 @@ import (
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/transition"
-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/attestations"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
-	prysmTime "github.com/prysmaticlabs/prysm/v3/time"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
+	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
+	"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"
+	prysmTime "github.com/prysmaticlabs/prysm/v4/time"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

@@ -30,22 +27,18 @@ var (

 func TestAttestationCheckPtState_FarFutureSlot(t *testing.T) {
 	helpers.ClearCache()
-	beaconDB := testDB.SetupDB(t)
+	service, _ := minimalTestService(t)

-	chainService := setupBeaconChain(t, beaconDB)
-	chainService.genesisTime = time.Now()
+	service.genesisTime = time.Now()

 	e := primitives.Epoch(slots.MaxSlotBuffer/uint64(params.BeaconConfig().SlotsPerEpoch) + 1)
-	_, err := chainService.AttestationTargetState(context.Background(), &ethpb.Checkpoint{Epoch: e})
+	_, err := service.AttestationTargetState(context.Background(), &ethpb.Checkpoint{Epoch: e})
 	require.ErrorContains(t, "exceeds max allowed value relative to the local clock", err)
 }

 func TestVerifyLMDFFGConsistent_NotOK(t *testing.T) {
-	ctx := context.Background()
-	opts := testServiceOptsWithDB(t)
-
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx

 	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
@@ -68,11 +61,8 @@ func TestVerifyLMDFFGConsistent_NotOK(t *testing.T) {
 }

 func TestVerifyLMDFFGConsistent_OK(t *testing.T) {
-	ctx := context.Background()
-
-	opts := testServiceOptsWithDB(t)
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	ctx := tr.ctx

 	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
@@ -95,13 +85,10 @@ func TestVerifyLMDFFGConsistent_OK(t *testing.T) {
 }

 func TestProcessAttestations_Ok(t *testing.T) {
+	service, tr := minimalTestService(t)
 	hook := logTest.NewGlobal()
-	ctx := context.Background()
-	opts := testServiceOptsWithDB(t)
-	opts = append(opts, WithAttestationPool(attestations.NewPool()))
+	ctx := tr.ctx

-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	service.genesisTime = prysmTime.Now().Add(-1 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second)
 	genesisState, pks := util.DeterministicGenesisState(t, 64)
 	require.NoError(t, genesisState.SetGenesisTime(uint64(prysmTime.Now().Unix())-params.BeaconConfig().SecondsPerSlot))
@@ -119,97 +106,20 @@ func TestProcessAttestations_Ok(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.ForkChoiceStore.InsertNode(ctx, state, blkRoot))
 	require.NoError(t, service.cfg.AttPool.SaveForkchoiceAttestations(atts))
-	service.processAttestations(ctx)
+	service.processAttestations(ctx, 0)
 	require.Equal(t, 0, len(service.cfg.AttPool.ForkchoiceAttestations()))
 	require.LogsDoNotContain(t, hook, "Could not process attestation for fork choice")
 }

-func TestNotifyEngineIfChangedHead(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()
-	require.NoError(t, service.notifyEngineIfChangedHead(ctx, service.headRoot()))
-	hookErr := "could not notify forkchoice update"
-	invalidStateErr := "Could not get state from 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))
-	require.NoError(t, service.notifyEngineIfChangedHead(ctx, [32]byte{'a'}))
-	require.LogsContain(t, hook, invalidStateErr)
-
-	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)
-	require.NoError(t, err)
-	r1, err := b.Block.HashTreeRoot()
-	require.NoError(t, err)
-	require.NoError(t, service.saveInitSyncBlock(ctx, r1, wsb))
-	st, _ := util.DeterministicGenesisState(t, 1)
-	service.head = &head{
-		root:  r1,
-		block: wsb,
-		state: st,
-	}
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(2, 1, [8]byte{1}, [32]byte{2})
-	require.NoError(t, service.notifyEngineIfChangedHead(ctx, r1))
-	require.LogsDoNotContain(t, hook, invalidStateErr)
-	require.LogsDoNotContain(t, hook, hookErr)
-
-	// Block in DB
-	b = util.NewBeaconBlock()
-	b.Block.Slot = 3
-	util.SaveBlock(t, ctx, service.cfg.BeaconDB, b)
-	r1, err = b.Block.HashTreeRoot()
-	require.NoError(t, err)
-	st, _ = util.DeterministicGenesisState(t, 1)
-	service.head = &head{
-		root:  r1,
-		block: wsb,
-		state: st,
-	}
-	service.cfg.ProposerSlotIndexCache.SetProposerAndPayloadIDs(2, 1, [8]byte{1}, [32]byte{2})
-	require.NoError(t, service.notifyEngineIfChangedHead(ctx, r1))
-	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)
-
-	// Test zero headRoot returns immediately.
-	headRoot := service.headRoot()
-	require.NoError(t, service.notifyEngineIfChangedHead(ctx, [32]byte{}))
-	require.Equal(t, service.headRoot(), headRoot)
-}
-
 func TestService_ProcessAttestationsAndUpdateHead(t *testing.T) {
-	ctx := context.Background()
-	opts := testServiceOptsWithDB(t)
-	fcs := doublylinkedtree.New()
-	opts = append(opts,
-		WithAttestationPool(attestations.NewPool()),
-		WithStateNotifier(&mockBeaconNode{}),
-		WithForkChoiceStore(fcs),
-	)
+	service, tr := minimalTestService(t)
+	ctx, fcs := tr.ctx, tr.fcs

-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	service.genesisTime = prysmTime.Now().Add(-2 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second)
 	genesisState, pks := util.DeterministicGenesisState(t, 64)
 	require.NoError(t, service.saveGenesisData(ctx, genesisState))
+	ojc := &ethpb.Checkpoint{Epoch: 0, Root: service.originBlockRoot[:]}
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, &forkchoicetypes.Checkpoint{Epoch: 0, Root: service.originBlockRoot}))
 	copied := genesisState.Copy()
 	// Generate a new block for attesters to attest
 	blk, err := util.GenerateFullBlock(copied, pks, util.DefaultBlockGenConfig(), 1)
@@ -230,9 +140,10 @@ func TestService_ProcessAttestationsAndUpdateHead(t *testing.T) {
 	require.NoError(t, service.cfg.AttPool.SaveForkchoiceAttestations(atts))
 	// Verify the target is in forkchoice
 	require.Equal(t, true, fcs.HasNode(bytesutil.ToBytes32(atts[0].Data.BeaconBlockRoot)))
+	require.Equal(t, tRoot, bytesutil.ToBytes32(atts[0].Data.BeaconBlockRoot))
+	require.Equal(t, true, fcs.HasNode(service.originBlockRoot))

 	// Insert a new block to forkchoice
-	ojc := &ethpb.Checkpoint{Epoch: 0, Root: params.BeaconConfig().ZeroHash[:]}
 	b, err := util.GenerateFullBlock(genesisState, pks, util.DefaultBlockGenConfig(), 2)
 	require.NoError(t, err)
 	b.Block.ParentRoot = service.originBlockRoot[:]
@@ -246,27 +157,19 @@ func TestService_ProcessAttestationsAndUpdateHead(t *testing.T) {
 	service.head.root = r // Old head

 	require.Equal(t, 1, len(service.cfg.AttPool.ForkchoiceAttestations()))
-	require.NoError(t, err, service.UpdateHead(ctx))
-
+	service.UpdateHead(ctx, 0)
+	require.Equal(t, tRoot, service.headRoot())
 	require.Equal(t, 0, len(service.cfg.AttPool.ForkchoiceAttestations())) // Validate att pool is empty
-	require.Equal(t, tRoot, service.head.root)                             // Validate head is the new one
 }

 func TestService_UpdateHead_NoAtts(t *testing.T) {
-	ctx := context.Background()
-	opts := testServiceOptsWithDB(t)
-	fcs := doublylinkedtree.New()
-	opts = append(opts,
-		WithAttestationPool(attestations.NewPool()),
-		WithStateNotifier(&mockBeaconNode{}),
-		WithForkChoiceStore(fcs),
-	)
+	service, tr := minimalTestService(t)
+	ctx, fcs := tr.ctx, tr.fcs

-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	service.genesisTime = prysmTime.Now().Add(-2 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second)
 	genesisState, pks := util.DeterministicGenesisState(t, 64)
 	require.NoError(t, service.saveGenesisData(ctx, genesisState))
+	require.NoError(t, fcs.UpdateJustifiedCheckpoint(ctx, &forkchoicetypes.Checkpoint{Epoch: 0, Root: service.originBlockRoot}))
 	copied := genesisState.Copy()
 	// Generate a new block
 	blk, err := util.GenerateFullBlock(copied, pks, util.DefaultBlockGenConfig(), 1)
@@ -294,9 +197,8 @@ func TestService_UpdateHead_NoAtts(t *testing.T) {
 	require.Equal(t, 3, fcs.NodeCount())

 	require.Equal(t, 0, service.cfg.AttPool.ForkchoiceAttestationCount())
-	require.NoError(t, err, service.UpdateHead(ctx))
+	service.UpdateHead(ctx, 0)
+	require.Equal(t, r, service.headRoot())

 	require.Equal(t, 0, len(service.cfg.AttPool.ForkchoiceAttestations())) // Validate att pool is empty
-	require.Equal(t, r, service.head.root)                                 // Validate head is the new one
-
 }
--- a/beacon-chain/blockchain/receive_block.go
+++ b/beacon-chain/blockchain/receive_block.go
@@ -1,18 +1,20 @@
 package blockchain

 import (
+	"bytes"
 	"context"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed"
-	statefeed "github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed/state"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/monitoring/tracing"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/runtime/version"
-	"github.com/prysmaticlabs/prysm/v3/time"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"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/consensus-types/interfaces"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/v4/monitoring/tracing"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/runtime/version"
+	"github.com/prysmaticlabs/prysm/v4/time"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	"go.opencensus.io/trace"
 )

@@ -21,9 +23,10 @@ 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.SignedBeaconBlock, blockRoot [32]byte) error
-	ReceiveBlockBatch(ctx context.Context, blocks []interfaces.SignedBeaconBlock, blkRoots [][32]byte) error
+	ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte) error
+	ReceiveBlockBatch(ctx context.Context, blocks []interfaces.ReadOnlySignedBeaconBlock, blkRoots [][32]byte) error
 	HasBlock(ctx context.Context, root [32]byte) bool
+	RecentBlockSlot(root [32]byte) (primitives.Slot, error)
 }

 // SlashingReceiver interface defines the methods of chain service for receiving validated slashing over the wire.
@@ -36,7 +39,7 @@ 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.SignedBeaconBlock, blockRoot [32]byte) error {
+func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.ReceiveBlock")
 	defer span.End()
 	receivedTime := time.Now()
@@ -45,6 +48,8 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.SignedBeaco
 		return err
 	}

+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
 	// Apply state transition on the new block.
 	if err := s.onBlock(ctx, blockCopy, blockRoot); err != nil {
 		err := errors.Wrap(err, "could not process block")
@@ -52,9 +57,9 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.SignedBeaco
 		return err
 	}

-	// Handle post block operations such as attestations and exits.
-	if err := s.handlePostBlockOperations(blockCopy.Block()); err != nil {
-		return err
+	// Handle post block operations such as pruning exits and bls messages if incoming block is the head
+	if err := s.prunePostBlockOperationPools(ctx, blockCopy, blockRoot); err != nil {
+		log.WithError(err).Error("Could not prune canonical objects from pool ")
 	}

 	// Have we been finalizing? Should we start saving hot states to db?
@@ -63,11 +68,13 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.SignedBeaco
 	}

 	// Reports on block and fork choice metrics.
-	finalized := s.FinalizedCheckpt()
+	cp := s.cfg.ForkChoiceStore.FinalizedCheckpoint()
+	finalized := &ethpb.Checkpoint{Epoch: cp.Epoch, Root: bytesutil.SafeCopyBytes(cp.Root[:])}
 	reportSlotMetrics(blockCopy.Block().Slot(), s.HeadSlot(), s.CurrentSlot(), finalized)

 	// Log block sync status.
-	justified := s.CurrentJustifiedCheckpt()
+	cp = s.cfg.ForkChoiceStore.JustifiedCheckpoint()
+	justified := &ethpb.Checkpoint{Epoch: cp.Epoch, Root: bytesutil.SafeCopyBytes(cp.Root[:])}
 	if err := logBlockSyncStatus(blockCopy.Block(), blockRoot, justified, finalized, receivedTime, uint64(s.genesisTime.Unix())); err != nil {
 		log.WithError(err).Error("Unable to log block sync status")
 	}
@@ -86,10 +93,13 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.SignedBeaco
 // 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 []interfaces.SignedBeaconBlock, blkRoots [][32]byte) error {
+func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []interfaces.ReadOnlySignedBeaconBlock, blkRoots [][32]byte) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.ReceiveBlockBatch")
 	defer span.End()

+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
+
 	// Apply state transition on the incoming newly received block batches, one by one.
 	if err := s.onBlockBatch(ctx, blocks, blkRoots); err != nil {
 		err := errors.Wrap(err, "could not process block in batch")
@@ -114,14 +124,15 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []interfaces.Sig
 		})

 		// Reports on blockCopy and fork choice metrics.
-		finalized := s.FinalizedCheckpt()
+		cp := s.cfg.ForkChoiceStore.FinalizedCheckpoint()
+		finalized := &ethpb.Checkpoint{Epoch: cp.Epoch, Root: bytesutil.SafeCopyBytes(cp.Root[:])}
 		reportSlotMetrics(blockCopy.Block().Slot(), s.HeadSlot(), s.CurrentSlot(), finalized)
 	}

 	if err := s.cfg.BeaconDB.SaveBlocks(ctx, s.getInitSyncBlocks()); err != nil {
 		return err
 	}
-	finalized := s.FinalizedCheckpt()
+	finalized := s.cfg.ForkChoiceStore.FinalizedCheckpoint()
 	if finalized == nil {
 		return errNilFinalizedInStore
 	}
@@ -140,34 +151,56 @@ func (s *Service) HasBlock(ctx context.Context, root [32]byte) bool {
 	return s.hasBlockInInitSyncOrDB(ctx, root)
 }

+// RecentBlockSlot returns block slot form fork choice store
+func (s *Service) RecentBlockSlot(root [32]byte) (primitives.Slot, error) {
+	return s.cfg.ForkChoiceStore.Slot(root)
+}
+
 // ReceiveAttesterSlashing receives an attester slashing and inserts it to forkchoice
 func (s *Service) ReceiveAttesterSlashing(ctx context.Context, slashing *ethpb.AttesterSlashing) {
+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
 	s.InsertSlashingsToForkChoiceStore(ctx, []*ethpb.AttesterSlashing{slashing})
 }

-func (s *Service) handlePostBlockOperations(b interfaces.BeaconBlock) error {
+// prunePostBlockOperationPools only runs on new head otherwise should return a nil.
+func (s *Service) prunePostBlockOperationPools(ctx context.Context, blk interfaces.ReadOnlySignedBeaconBlock, root [32]byte) error {
+	headRoot, err := s.HeadRoot(ctx)
+	if err != nil {
+		return err
+	}
+	// By comparing the current headroot, that has already gone through forkchoice,
+	// we can assume that if equal the current block root is canonical.
+	if !bytes.Equal(headRoot, root[:]) {
+		return nil
+	}
+
 	// Mark block exits as seen so we don't include same ones in future blocks.
-	for _, e := range b.Body().VoluntaryExits() {
+	for _, e := range blk.Block().Body().VoluntaryExits() {
 		s.cfg.ExitPool.MarkIncluded(e)
 	}

 	// Mark block BLS changes as seen so we don't include same ones in future blocks.
-	if err := s.handleBlockBLSToExecChanges(b); err != nil {
+	if err := s.markIncludedBlockBLSToExecChanges(blk.Block()); err != nil {
 		return errors.Wrap(err, "could not process BLSToExecutionChanges")
 	}

-	//  Mark attester slashings as seen so we don't include same ones in future blocks.
-	for _, as := range b.Body().AttesterSlashings() {
+	// Mark slashings as seen so we don't include same ones in future blocks.
+	for _, as := range blk.Block().Body().AttesterSlashings() {
 		s.cfg.SlashingPool.MarkIncludedAttesterSlashing(as)
 	}
+	for _, ps := range blk.Block().Body().ProposerSlashings() {
+		s.cfg.SlashingPool.MarkIncludedProposerSlashing(ps)
+	}
+
 	return nil
 }

-func (s *Service) handleBlockBLSToExecChanges(blk interfaces.BeaconBlock) error {
-	if blk.Version() < version.Capella {
+func (s *Service) markIncludedBlockBLSToExecChanges(headBlock interfaces.ReadOnlyBeaconBlock) error {
+	if headBlock.Version() < version.Capella {
 		return nil
 	}
-	changes, err := blk.Body().BLSToExecutionChanges()
+	changes, err := headBlock.Body().BLSToExecutionChanges()
 	if err != nil {
 		return errors.Wrap(err, "could not get BLSToExecutionChanges")
 	}
@@ -179,11 +212,12 @@ func (s *Service) handleBlockBLSToExecChanges(blk interfaces.BeaconBlock) error

 // This checks whether it's time to start saving hot state to DB.
 // It's time when there's `epochsSinceFinalitySaveHotStateDB` epochs of non-finality.
+// Requires a read lock on forkchoice
 func (s *Service) checkSaveHotStateDB(ctx context.Context) error {
 	currentEpoch := slots.ToEpoch(s.CurrentSlot())
 	// Prevent `sinceFinality` going underflow.
 	var sinceFinality primitives.Epoch
-	finalized := s.FinalizedCheckpt()
+	finalized := s.cfg.ForkChoiceStore.FinalizedCheckpoint()
 	if finalized == nil {
 		return errNilFinalizedInStore
 	}
--- a/beacon-chain/blockchain/receive_block_test.go
+++ b/beacon-chain/blockchain/receive_block_test.go
@@ -6,22 +6,17 @@ import (
 	"testing"
 	"time"

-	blockchainTesting "github.com/prysmaticlabs/prysm/v3/beacon-chain/blockchain/testing"
-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/attestations"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/blstoexec"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/voluntaryexits"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	blockchainTesting "github.com/prysmaticlabs/prysm/v4/beacon-chain/blockchain/testing"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/voluntaryexits"
+	"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"
+	"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"
 )

@@ -97,7 +92,8 @@ func TestService_ReceiveBlock(t *testing.T) {
 				),
 			},
 			check: func(t *testing.T, s *Service) {
-				pending := s.cfg.ExitPool.PendingExits(genesis, 1, true /* no limit */)
+				pending, err := s.cfg.ExitPool.PendingExits()
+				require.NoError(t, err)
 				if len(pending) != 0 {
 					t.Errorf(
 						"Did not mark the correct number of exits. Got %d pending but wanted %d",
@@ -124,22 +120,15 @@ func TestService_ReceiveBlock(t *testing.T) {
 	for _, tt := range tests {
 		wg.Add(1)
 		t.Run(tt.name, func(t *testing.T) {
-			beaconDB := testDB.SetupDB(t)
+			s, tr := minimalTestService(t,
+				WithFinalizedStateAtStartUp(genesis),
+				WithExitPool(voluntaryexits.NewPool()),
+				WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}))
+
+			beaconDB := tr.db
 			genesisBlockRoot := bytesutil.ToBytes32(nil)
 			require.NoError(t, beaconDB.SaveState(ctx, genesis, genesisBlockRoot))

-			fc := doublylinkedtree.New()
-			opts := []Option{
-				WithDatabase(beaconDB),
-				WithForkChoiceStore(fc),
-				WithAttestationPool(attestations.NewPool()),
-				WithExitPool(voluntaryexits.NewPool()),
-				WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}),
-				WithStateGen(stategen.New(beaconDB, fc)),
-				WithFinalizedStateAtStartUp(genesis),
-			}
-			s, err := NewService(ctx, opts...)
-			require.NoError(t, err)
 			// Initialize it here.
 			_ = s.cfg.StateNotifier.StateFeed()
 			require.NoError(t, s.saveGenesisData(ctx, genesis))
@@ -161,25 +150,16 @@ func TestService_ReceiveBlock(t *testing.T) {
 }

 func TestService_ReceiveBlockUpdateHead(t *testing.T) {
-	ctx := context.Background()
+	s, tr := minimalTestService(t,
+		WithExitPool(voluntaryexits.NewPool()),
+		WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}))
+	ctx, beaconDB := tr.ctx, tr.db
 	genesis, keys := util.DeterministicGenesisState(t, 64)
 	b, err := util.GenerateFullBlock(genesis, keys, util.DefaultBlockGenConfig(), 1)
 	assert.NoError(t, err)
-	beaconDB := testDB.SetupDB(t)
 	genesisBlockRoot := bytesutil.ToBytes32(nil)
 	require.NoError(t, beaconDB.SaveState(ctx, genesis, genesisBlockRoot))
-	fc := doublylinkedtree.New()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithForkChoiceStore(fc),
-		WithAttestationPool(attestations.NewPool()),
-		WithExitPool(voluntaryexits.NewPool()),
-		WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}),
-		WithStateGen(stategen.New(beaconDB, fc)),
-	}

-	s, err := NewService(ctx, opts...)
-	require.NoError(t, err)
 	// Initialize it here.
 	_ = s.cfg.StateNotifier.StateFeed()
 	require.NoError(t, s.saveGenesisData(ctx, genesis))
@@ -245,23 +225,14 @@ func TestService_ReceiveBlockBatch(t *testing.T) {

 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			fc := doublylinkedtree.New()
-			beaconDB := testDB.SetupDB(t)
-			opts := []Option{
-				WithDatabase(beaconDB),
-				WithForkChoiceStore(fc),
-				WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}),
-				WithStateGen(stategen.New(beaconDB, fc)),
-			}
-			s, err := NewService(ctx, opts...)
-			require.NoError(t, err)
-			err = s.saveGenesisData(ctx, genesis)
+			s, _ := minimalTestService(t, WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}))
+			err := s.saveGenesisData(ctx, genesis)
 			require.NoError(t, err)
 			root, err := tt.args.block.Block.HashTreeRoot()
 			require.NoError(t, err)
 			wsb, err := blocks.NewSignedBeaconBlock(tt.args.block)
 			require.NoError(t, err)
-			blks := []interfaces.SignedBeaconBlock{wsb}
+			blks := []interfaces.ReadOnlySignedBeaconBlock{wsb}
 			roots := [][32]byte{root}
 			err = s.ReceiveBlockBatch(ctx, blks, roots)
 			if tt.wantedErr != "" {
@@ -275,10 +246,7 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 }

 func TestService_HasBlock(t *testing.T) {
-	opts := testServiceOptsWithDB(t)
-	opts = append(opts, WithStateNotifier(&blockchainTesting.MockStateNotifier{}))
-	s, err := NewService(context.Background(), opts...)
-	require.NoError(t, err)
+	s, _ := minimalTestService(t)
 	r := [32]byte{'a'}
 	if s.HasBlock(context.Background(), r) {
 		t.Error("Should not have block")
@@ -298,10 +266,8 @@ func TestService_HasBlock(t *testing.T) {
 }

 func TestCheckSaveHotStateDB_Enabling(t *testing.T) {
-	opts := testServiceOptsWithDB(t)
 	hook := logTest.NewGlobal()
-	s, err := NewService(context.Background(), opts...)
-	require.NoError(t, err)
+	s, _ := minimalTestService(t)
 	st := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(epochsSinceFinalitySaveHotStateDB))
 	s.genesisTime = time.Now().Add(time.Duration(-1*int64(st)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)

@@ -311,9 +277,9 @@ func TestCheckSaveHotStateDB_Enabling(t *testing.T) {

 func TestCheckSaveHotStateDB_Disabling(t *testing.T) {
 	hook := logTest.NewGlobal()
-	opts := testServiceOptsWithDB(t)
-	s, err := NewService(context.Background(), opts...)
-	require.NoError(t, err)
+
+	s, _ := minimalTestService(t)
+
 	st := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(epochsSinceFinalitySaveHotStateDB))
 	s.genesisTime = time.Now().Add(time.Duration(-1*int64(st)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
 	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
@@ -325,9 +291,7 @@ func TestCheckSaveHotStateDB_Disabling(t *testing.T) {

 func TestCheckSaveHotStateDB_Overflow(t *testing.T) {
 	hook := logTest.NewGlobal()
-	opts := testServiceOptsWithDB(t)
-	s, err := NewService(context.Background(), opts...)
-	require.NoError(t, err)
+	s, _ := minimalTestService(t)
 	s.genesisTime = time.Now()

 	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
@@ -335,19 +299,8 @@ func TestCheckSaveHotStateDB_Overflow(t *testing.T) {
 }

 func TestHandleBlockBLSToExecutionChanges(t *testing.T) {
-	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-	fc := doublylinkedtree.New()
-	pool := blstoexec.NewPool()
-	opts := []Option{
-		WithDatabase(beaconDB),
-		WithStateGen(stategen.New(beaconDB, fc)),
-		WithForkChoiceStore(fc),
-		WithStateNotifier(&blockchainTesting.MockStateNotifier{}),
-		WithBLSToExecPool(pool),
-	}
-	service, err := NewService(ctx, opts...)
-	require.NoError(t, err)
+	service, tr := minimalTestService(t)
+	pool := tr.blsPool

 	t.Run("pre Capella block", func(t *testing.T) {
 		body := &ethpb.BeaconBlockBodyBellatrix{}
@@ -356,7 +309,7 @@ func TestHandleBlockBLSToExecutionChanges(t *testing.T) {
 		}
 		blk, err := blocks.NewBeaconBlock(pbb)
 		require.NoError(t, err)
-		require.NoError(t, service.handleBlockBLSToExecChanges(blk))
+		require.NoError(t, service.markIncludedBlockBLSToExecChanges(blk))
 	})

 	t.Run("Post Capella no changes", func(t *testing.T) {
@@ -366,7 +319,7 @@ func TestHandleBlockBLSToExecutionChanges(t *testing.T) {
 		}
 		blk, err := blocks.NewBeaconBlock(pbb)
 		require.NoError(t, err)
-		require.NoError(t, service.handleBlockBLSToExecChanges(blk))
+		require.NoError(t, service.markIncludedBlockBLSToExecChanges(blk))
 	})

 	t.Run("Post Capella some changes", func(t *testing.T) {
@@ -388,7 +341,7 @@ func TestHandleBlockBLSToExecutionChanges(t *testing.T) {

 		pool.InsertBLSToExecChange(signedChange)
 		require.Equal(t, true, pool.ValidatorExists(idx))
-		require.NoError(t, service.handleBlockBLSToExecChanges(blk))
+		require.NoError(t, service.markIncludedBlockBLSToExecChanges(blk))
 		require.Equal(t, false, pool.ValidatorExists(idx))
 	})
 }
--- a/beacon-chain/blockchain/service.go
+++ b/beacon-chain/blockchain/service.go
@@ -11,54 +11,55 @@ import (
 	"time"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v3/async/event"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache/depositcache"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed"
-	statefeed "github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/transition"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/db"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/execution"
-	f "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice"
-	forkchoicetypes "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/types"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/attestations"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/blstoexec"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/slashings"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/voluntaryexits"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/p2p"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/v3/config/features"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/primitives"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	prysmTime "github.com/prysmaticlabs/prysm/v3/time"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/async/event"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache/depositcache"
+	"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"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/core/transition"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/execution"
+	f "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice"
+	forkchoicetypes "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/types"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/attestations"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/blstoexec"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/slashings"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/voluntaryexits"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/p2p"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/startup"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state/stategen"
+	"github.com/prysmaticlabs/prysm/v4/config/features"
+	"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
-	nextEpochBoundarySlot   primitives.Slot
-	boundaryRoots           [][32]byte
-	checkpointStateCache    *cache.CheckpointStateCache
-	initSyncBlocks          map[[32]byte]interfaces.SignedBeaconBlock
-	initSyncBlocksLock      sync.RWMutex
-	justifiedBalances       *stateBalanceCache
-	wsVerifier              *WeakSubjectivityVerifier
-	processAttestationsLock sync.Mutex
+	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
+	nextEpochBoundarySlot primitives.Slot
+	boundaryRoots         [][32]byte
+	checkpointStateCache  *cache.CheckpointStateCache
+	initSyncBlocks        map[[32]byte]interfaces.ReadOnlySignedBeaconBlock
+	initSyncBlocksLock    sync.RWMutex
+	wsVerifier            *WeakSubjectivityVerifier
+	clockSetter           startup.ClockSetter
+	clockWaiter           startup.ClockWaiter
 }

 // config options for the service.
@@ -85,6 +86,8 @@ type config struct {
 	ExecutionEngineCaller   execution.EngineCaller
 }

+var ErrMissingClockSetter = errors.New("blockchain Service initialized without a startup.ClockSetter")
+
 // NewService instantiates a new block service instance that will
 // be registered into a running beacon node.
 func NewService(ctx context.Context, opts ...Option) (*Service, error) {
@@ -94,21 +97,18 @@ func NewService(ctx context.Context, opts ...Option) (*Service, error) {
 		cancel:               cancel,
 		boundaryRoots:        [][32]byte{},
 		checkpointStateCache: cache.NewCheckpointStateCache(),
-		initSyncBlocks:       make(map[[32]byte]interfaces.SignedBeaconBlock),
-		cfg:                  &config{},
+		initSyncBlocks:       make(map[[32]byte]interfaces.ReadOnlySignedBeaconBlock),
+		cfg:                  &config{ProposerSlotIndexCache: cache.NewProposerPayloadIDsCache()},
 	}
 	for _, opt := range opts {
 		if err := opt(srv); err != nil {
 			return nil, err
 		}
 	}
-	var err error
-	if srv.justifiedBalances == nil {
-		srv.justifiedBalances, err = newStateBalanceCache(srv.cfg.StateGen)
-		if err != nil {
-			return nil, err
-		}
+	if srv.clockSetter == nil {
+		return nil, ErrMissingClockSetter
 	}
+	var err error
 	srv.wsVerifier, err = NewWeakSubjectivityVerifier(srv.cfg.WeakSubjectivityCheckpt, srv.cfg.BeaconDB)
 	if err != nil {
 		return nil, err
@@ -129,8 +129,8 @@ func (s *Service) Start() {
 			log.Fatal(err)
 		}
 	}
-	s.spawnProcessAttestationsRoutine(s.cfg.StateNotifier.StateFeed())
-	s.fillMissingPayloadIDRoutine(s.ctx, s.cfg.StateNotifier.StateFeed())
+	s.spawnProcessAttestationsRoutine()
+	go s.runLateBlockTasks()
 }

 // Stop the blockchain service's main event loop and associated goroutines.
@@ -207,7 +207,9 @@ func (s *Service) StartFromSavedState(saved state.BeaconState) error {
 	}

 	fRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(finalized.Root))
-	if err := s.cfg.ForkChoiceStore.UpdateJustifiedCheckpoint(&forkchoicetypes.Checkpoint{Epoch: justified.Epoch,
+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
+	if err := s.cfg.ForkChoiceStore.UpdateJustifiedCheckpoint(s.ctx, &forkchoicetypes.Checkpoint{Epoch: justified.Epoch,
 		Root: bytesutil.ToBytes32(justified.Root)}); err != nil {
 		return errors.Wrap(err, "could not update forkchoice's justified checkpoint")
 	}
@@ -242,13 +244,10 @@ func (s *Service) StartFromSavedState(saved state.BeaconState) error {
 		return errors.Wrap(err, "could not verify initial checkpoint provided for chain sync")
 	}

-	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
-		Type: statefeed.Initialized,
-		Data: &statefeed.InitializedData{
-			StartTime:             s.genesisTime,
-			GenesisValidatorsRoot: saved.GenesisValidatorsRoot(),
-		},
-	})
+	vr := bytesutil.ToBytes32(saved.GenesisValidatorsRoot())
+	if err := s.clockSetter.SetClock(startup.NewClock(s.genesisTime, vr)); err != nil {
+		return errors.Wrap(err, "failed to initialize blockchain service")
+	}

 	return nil
 }
@@ -365,15 +364,10 @@ func (s *Service) onExecutionChainStart(ctx context.Context, genesisTime time.Ti
 	}
 	go slots.CountdownToGenesis(ctx, genesisTime, uint64(initializedState.NumValidators()), gRoot)

-	// We send out a state initialized event to the rest of the services
-	// running in the beacon node.
-	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
-		Type: statefeed.Initialized,
-		Data: &statefeed.InitializedData{
-			StartTime:             genesisTime,
-			GenesisValidatorsRoot: initializedState.GenesisValidatorsRoot(),
-		},
-	})
+	vr := bytesutil.ToBytes32(initializedState.GenesisValidatorsRoot())
+	if err := s.clockSetter.SetClock(startup.NewClock(genesisTime, vr)); err != nil {
+		log.WithError(err).Fatal("failed to initialize blockchain service from execution start event")
+	}
 }

 // initializes the state and genesis block of the beacon chain to persistent storage
@@ -433,6 +427,8 @@ func (s *Service) saveGenesisData(ctx context.Context, genesisState state.Beacon
 	s.originBlockRoot = genesisBlkRoot
 	s.cfg.StateGen.SaveFinalizedState(0 /*slot*/, genesisBlkRoot, genesisState)

+	s.cfg.ForkChoiceStore.Lock()
+	defer s.cfg.ForkChoiceStore.Unlock()
 	if err := s.cfg.ForkChoiceStore.InsertNode(ctx, genesisState, genesisBlkRoot); err != nil {
 		log.WithError(err).Fatal("Could not process genesis block for fork choice")
 	}
@@ -453,6 +449,7 @@ func (s *Service) saveGenesisData(ctx context.Context, genesisState state.Beacon
 // 1.) Check fork choice store.
 // 2.) Check DB.
 // Checking 1.) is ten times faster than checking 2.)
+// this function requires a lock in forkchoice
 func (s *Service) hasBlock(ctx context.Context, root [32]byte) bool {
 	if s.cfg.ForkChoiceStore.HasNode(root) {
 		return true
--- a/beacon-chain/blockchain/service_norace_test.go
+++ b/beacon-chain/blockchain/service_norace_test.go
@@ -5,10 +5,10 @@ import (
 	"io"
 	"testing"

-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
+	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
 	"github.com/sirupsen/logrus"
 )

--- a/beacon-chain/blockchain/service_test.go
+++ b/beacon-chain/blockchain/service_test.go
@@ -8,74 +8,36 @@ import (
 	"time"

 	"github.com/ethereum/go-ethereum/common"
-	"github.com/prysmaticlabs/prysm/v3/async/event"
-	mock "github.com/prysmaticlabs/prysm/v3/beacon-chain/blockchain/testing"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/cache/depositcache"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/blocks"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed"
-	statefeed "github.com/prysmaticlabs/prysm/v3/beacon-chain/core/feed/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/transition"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/db"
-	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/execution"
-	mockExecution "github.com/prysmaticlabs/prysm/v3/beacon-chain/execution/testing"
-	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/operations/attestations"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/p2p"
-	state_native "github.com/prysmaticlabs/prysm/v3/beacon-chain/state/state-native"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/v3/config/features"
-	"github.com/prysmaticlabs/prysm/v3/config/params"
-	consensusblocks "github.com/prysmaticlabs/prysm/v3/consensus-types/blocks"
-	"github.com/prysmaticlabs/prysm/v3/consensus-types/interfaces"
-	"github.com/prysmaticlabs/prysm/v3/container/trie"
-	"github.com/prysmaticlabs/prysm/v3/encoding/bytesutil"
-	ethpb "github.com/prysmaticlabs/prysm/v3/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v3/testing/assert"
-	"github.com/prysmaticlabs/prysm/v3/testing/require"
-	"github.com/prysmaticlabs/prysm/v3/testing/util"
-	"github.com/prysmaticlabs/prysm/v3/time/slots"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/cache/depositcache"
+	"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/transition"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/db"
+	testDB "github.com/prysmaticlabs/prysm/v4/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/execution"
+	mockExecution "github.com/prysmaticlabs/prysm/v4/beacon-chain/execution/testing"
+	doublylinkedtree "github.com/prysmaticlabs/prysm/v4/beacon-chain/forkchoice/doubly-linked-tree"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/attestations"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/slashings"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/voluntaryexits"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/startup"
+	state_native "github.com/prysmaticlabs/prysm/v4/beacon-chain/state/state-native"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state/stategen"
+	"github.com/prysmaticlabs/prysm/v4/config/features"
+	"github.com/prysmaticlabs/prysm/v4/config/params"
+	consensusblocks "github.com/prysmaticlabs/prysm/v4/consensus-types/blocks"
+	"github.com/prysmaticlabs/prysm/v4/consensus-types/interfaces"
+	"github.com/prysmaticlabs/prysm/v4/container/trie"
+	"github.com/prysmaticlabs/prysm/v4/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/assert"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"github.com/prysmaticlabs/prysm/v4/testing/util"
+	"github.com/prysmaticlabs/prysm/v4/time/slots"
 	logTest "github.com/sirupsen/logrus/hooks/test"
-	"google.golang.org/protobuf/proto"
 )

-type mockBeaconNode struct {
-	stateFeed *event.Feed
-}
-
-// StateFeed mocks the same method in the beacon node.
-func (mbn *mockBeaconNode) StateFeed() *event.Feed {
-	if mbn.stateFeed == nil {
-		mbn.stateFeed = new(event.Feed)
-	}
-	return mbn.stateFeed
-}
-
-type mockBroadcaster struct {
-	broadcastCalled bool
-}
-
-func (mb *mockBroadcaster) Broadcast(_ context.Context, _ proto.Message) error {
-	mb.broadcastCalled = true
-	return nil
-}
-
-func (mb *mockBroadcaster) BroadcastAttestation(_ context.Context, _ uint64, _ *ethpb.Attestation) error {
-	mb.broadcastCalled = true
-	return nil
-}
-
-func (mb *mockBroadcaster) BroadcastSyncCommitteeMessage(_ context.Context, _ uint64, _ *ethpb.SyncCommitteeMessage) error {
-	mb.broadcastCalled = true
-	return nil
-}
-
-func (mb *mockBroadcaster) BroadcastBLSChanges(_ context.Context, _ []*ethpb.SignedBLSToExecutionChange) {
-}
-
-var _ p2p.Broadcaster = (*mockBroadcaster)(nil)
-
 func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
 	ctx := context.Background()
 	var web3Service *execution.Service
@@ -130,11 +92,15 @@ func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
 		WithDepositCache(depositCache),
 		WithChainStartFetcher(web3Service),
 		WithAttestationPool(attestations.NewPool()),
+		WithSlashingPool(slashings.NewPool()),
+		WithExitPool(voluntaryexits.NewPool()),
 		WithP2PBroadcaster(&mockBroadcaster{}),
 		WithStateNotifier(&mockBeaconNode{}),
 		WithForkChoiceStore(fc),
 		WithAttestationService(attService),
 		WithStateGen(stateGen),
+		WithProposerIdsCache(cache.NewProposerPayloadIDsCache()),
+		WithClockSynchronizer(startup.NewClockSynchronizer()),
 	}

 	chainService, err := NewService(ctx, opts...)
@@ -151,12 +117,14 @@ func TestChainStartStop_Initialized(t *testing.T) {

 	chainService := setupBeaconChain(t, beaconDB)

+	gt := time.Unix(23, 0)
 	genesisBlk := util.NewBeaconBlock()
 	blkRoot, err := genesisBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
 	util.SaveBlock(t, ctx, beaconDB, genesisBlk)
 	s, err := util.NewBeaconState()
 	require.NoError(t, err)
+	require.NoError(t, s.SetGenesisTime(uint64(gt.Unix())))
 	require.NoError(t, s.SetSlot(1))
 	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
 	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, blkRoot))
@@ -186,12 +154,14 @@ func TestChainStartStop_GenesisZeroHashes(t *testing.T) {

 	chainService := setupBeaconChain(t, beaconDB)

+	gt := time.Unix(23, 0)
 	genesisBlk := util.NewBeaconBlock()
 	blkRoot, err := genesisBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
 	wsb := util.SaveBlock(t, ctx, beaconDB, genesisBlk)
 	s, err := util.NewBeaconState()
 	require.NoError(t, err)
+	require.NoError(t, s.SetGenesisTime(uint64(gt.Unix())))
 	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, blkRoot))
 	require.NoError(t, beaconDB.SaveBlock(ctx, wsb))
@@ -258,12 +228,14 @@ func TestChainService_CorrectGenesisRoots(t *testing.T) {

 	chainService := setupBeaconChain(t, beaconDB)

+	gt := time.Unix(23, 0)
 	genesisBlk := util.NewBeaconBlock()
 	blkRoot, err := genesisBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
 	util.SaveBlock(t, ctx, beaconDB, genesisBlk)
 	s, err := util.NewBeaconState()
 	require.NoError(t, err)
+	require.NoError(t, s.SetGenesisTime(uint64(gt.Unix())))
 	require.NoError(t, s.SetSlot(0))
 	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
 	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, blkRoot))
@@ -284,14 +256,9 @@ func TestChainService_CorrectGenesisRoots(t *testing.T) {
 }

 func TestChainService_InitializeChainInfo(t *testing.T) {
-	beaconDB := testDB.SetupDB(t)
-	ctx := context.Background()
-
 	genesis := util.NewBeaconBlock()
 	genesisRoot, err := genesis.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
-	util.SaveBlock(t, ctx, beaconDB, genesis)

 	finalizedSlot := params.BeaconConfig().SlotsPerEpoch*2 + 1
 	headBlock := util.NewBeaconBlock()
@@ -303,23 +270,18 @@ func TestChainService_InitializeChainInfo(t *testing.T) {
 	require.NoError(t, headState.SetGenesisValidatorsRoot(params.BeaconConfig().ZeroHash[:]))
 	headRoot, err := headBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
+
+	c, tr := minimalTestService(t, WithFinalizedStateAtStartUp(headState))
+	ctx, beaconDB, stateGen := tr.ctx, tr.db, tr.sg
+
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
+	util.SaveBlock(t, ctx, beaconDB, genesis)
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, genesisRoot))
 	util.SaveBlock(t, ctx, beaconDB, headBlock)
 	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Epoch: slots.ToEpoch(finalizedSlot), Root: headRoot[:]}))
-	attSrv, err := attestations.NewService(ctx, &attestations.Config{})
-	require.NoError(t, err)
-	fc := doublylinkedtree.New()
-	stateGen := stategen.New(beaconDB, fc)
-	c, err := NewService(ctx,
-		WithForkChoiceStore(fc),
-		WithDatabase(beaconDB),
-		WithStateGen(stateGen),
-		WithAttestationService(attSrv),
-		WithStateNotifier(&mock.MockStateNotifier{}),
-		WithFinalizedStateAtStartUp(headState))
-	require.NoError(t, err)
 	require.NoError(t, stateGen.SaveState(ctx, headRoot, headState))
+
 	require.NoError(t, c.StartFromSavedState(headState))
 	headBlk, err := c.HeadBlock(ctx)
 	require.NoError(t, err)
@@ -339,14 +301,9 @@ func TestChainService_InitializeChainInfo(t *testing.T) {
 }

 func TestChainService_InitializeChainInfo_SetHeadAtGenesis(t *testing.T) {
-	beaconDB := testDB.SetupDB(t)
-	ctx := context.Background()
-
 	genesis := util.NewBeaconBlock()
 	genesisRoot, err := genesis.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
-	util.SaveBlock(t, ctx, beaconDB, genesis)

 	finalizedSlot := params.BeaconConfig().SlotsPerEpoch*2 + 1
 	headBlock := util.NewBeaconBlock()
@@ -358,27 +315,21 @@ func TestChainService_InitializeChainInfo_SetHeadAtGenesis(t *testing.T) {
 	require.NoError(t, headState.SetGenesisValidatorsRoot(params.BeaconConfig().ZeroHash[:]))
 	headRoot, err := headBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
+
+	c, tr := minimalTestService(t, WithFinalizedStateAtStartUp(headState))
+	ctx, beaconDB := tr.ctx, tr.db
+
+	util.SaveBlock(t, ctx, beaconDB, genesis)
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, genesisRoot))
+	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	util.SaveBlock(t, ctx, beaconDB, headBlock)
-	attSrv, err := attestations.NewService(ctx, &attestations.Config{})
-	require.NoError(t, err)
 	ss := &ethpb.StateSummary{
 		Slot: finalizedSlot,
 		Root: headRoot[:],
 	}
 	require.NoError(t, beaconDB.SaveStateSummary(ctx, ss))
 	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Root: headRoot[:], Epoch: slots.ToEpoch(finalizedSlot)}))
-	fc := doublylinkedtree.New()
-	stateGen := stategen.New(beaconDB, fc)
-	c, err := NewService(ctx,
-		WithForkChoiceStore(fc),
-		WithDatabase(beaconDB),
-		WithStateGen(stateGen),
-		WithAttestationService(attSrv),
-		WithStateNotifier(&mock.MockStateNotifier{}),
-		WithFinalizedStateAtStartUp(headState))
-	require.NoError(t, err)

 	require.NoError(t, c.StartFromSavedState(headState))
 	s, err := c.HeadState(ctx)
@@ -441,7 +392,7 @@ func TestServiceStop_SaveCachedBlocks(t *testing.T) {
 		cfg:            &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB, doublylinkedtree.New())},
 		ctx:            ctx,
 		cancel:         cancel,
-		initSyncBlocks: make(map[[32]byte]interfaces.SignedBeaconBlock),
+		initSyncBlocks: make(map[[32]byte]interfaces.ReadOnlySignedBeaconBlock),
 	}
 	bb := util.NewBeaconBlock()
 	r, err := bb.Block.HashTreeRoot()
@@ -454,17 +405,21 @@ func TestServiceStop_SaveCachedBlocks(t *testing.T) {
 }

 func TestProcessChainStartTime_ReceivedFeed(t *testing.T) {
+	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
-	stateChannel := make(chan *feed.Event, 1)
-	stateSub := service.cfg.StateNotifier.StateFeed().Subscribe(stateChannel)
-	defer stateSub.Unsubscribe()
-	service.onExecutionChainStart(context.Background(), time.Now())
-
-	stateEvent := <-stateChannel
-	require.Equal(t, int(stateEvent.Type), statefeed.Initialized)
-	_, ok := stateEvent.Data.(*statefeed.InitializedData)
-	require.Equal(t, true, ok)
+	mgs := &MockClockSetter{}
+	service.clockSetter = mgs
+	gt := time.Now()
+	service.onExecutionChainStart(context.Background(), gt)
+	gs, err := beaconDB.GenesisState(ctx)
+	require.NoError(t, err)
+	require.NotEqual(t, nil, gs)
+	require.Equal(t, 32, len(gs.GenesisValidatorsRoot()))
+	var zero [32]byte
+	require.DeepNotEqual(t, gs.GenesisValidatorsRoot(), zero[:])
+	require.Equal(t, gt, mgs.G.GenesisTime())
+	require.Equal(t, bytesutil.ToBytes32(gs.GenesisValidatorsRoot()), mgs.G.GenesisValidatorsRoot())
 }

 func BenchmarkHasBlockDB(b *testing.B) {
@@ -513,15 +468,10 @@ func TestChainService_EverythingOptimistic(t *testing.T) {
 		EnableStartOptimistic: true,
 	})
 	defer resetFn()
-	beaconDB := testDB.SetupDB(t)
-	ctx := context.Background()

 	genesis := util.NewBeaconBlock()
 	genesisRoot, err := genesis.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
-	util.SaveBlock(t, ctx, beaconDB, genesis)
-
 	finalizedSlot := params.BeaconConfig().SlotsPerEpoch*2 + 1
 	headBlock := util.NewBeaconBlock()
 	headBlock.Block.Slot = finalizedSlot
@@ -532,21 +482,17 @@ func TestChainService_EverythingOptimistic(t *testing.T) {
 	require.NoError(t, headState.SetGenesisValidatorsRoot(params.BeaconConfig().ZeroHash[:]))
 	headRoot, err := headBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
+
+	c, tr := minimalTestService(t, WithFinalizedStateAtStartUp(headState))
+	ctx, beaconDB, stateGen := tr.ctx, tr.db, tr.sg
+
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
+	util.SaveBlock(t, ctx, beaconDB, genesis)
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, genesisRoot))
 	util.SaveBlock(t, ctx, beaconDB, headBlock)
 	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Epoch: slots.ToEpoch(finalizedSlot), Root: headRoot[:]}))
-	attSrv, err := attestations.NewService(ctx, &attestations.Config{})
-	require.NoError(t, err)
-	fc := doublylinkedtree.New()
-	stateGen := stategen.New(beaconDB, fc)
-	c, err := NewService(ctx,
-		WithForkChoiceStore(fc),
-		WithDatabase(beaconDB),
-		WithStateGen(stateGen),
-		WithAttestationService(attSrv),
-		WithStateNotifier(&mock.MockStateNotifier{}),
-		WithFinalizedStateAtStartUp(headState))
+
 	require.NoError(t, err)
 	require.NoError(t, stateGen.SaveState(ctx, headRoot, headState))
 	require.NoError(t, beaconDB.SaveLastValidatedCheckpoint(ctx, &ethpb.Checkpoint{Epoch: slots.ToEpoch(finalizedSlot), Root: headRoot[:]}))
@@ -556,3 +502,19 @@ func TestChainService_EverythingOptimistic(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, true, op)
 }
+
+// MockClockSetter satisfies the ClockSetter interface for testing the conditions where blockchain.Service should
+// call SetGenesis.
+type MockClockSetter struct {
+	G   *startup.Clock
+	Err error
+}
+
+var _ startup.ClockSetter = &MockClockSetter{}
+
+// SetClock satisfies the ClockSetter interface.
+// The value is written to an exported field 'G' so that it can be accessed in tests.
+func (s *MockClockSetter) SetClock(g *startup.Clock) error {
+	s.G = g
+	return s.Err
+}
--- a/beacon-chain/blockchain/setup_test.go
+++ b/beacon-chain/blockchain/setup_test.go
@@ -0,0 +1,120 @@
+package blockchain
+
+import (
+	"context"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/v4/async/event"
+	"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"
+	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"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/attestations"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/operations/blstoexec"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/p2p"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/startup"
+	"github.com/prysmaticlabs/prysm/v4/beacon-chain/state/stategen"
+	ethpb "github.com/prysmaticlabs/prysm/v4/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v4/testing/require"
+	"google.golang.org/protobuf/proto"
+)
+
+type mockBeaconNode struct {
+	stateFeed *event.Feed
+}
+
+// StateFeed mocks the same method in the beacon node.
+func (mbn *mockBeaconNode) StateFeed() *event.Feed {
+	if mbn.stateFeed == nil {
+		mbn.stateFeed = new(event.Feed)
+	}
+	return mbn.stateFeed
+}
+
+type mockBroadcaster struct {
+	broadcastCalled bool
+}
+
+func (mb *mockBroadcaster) Broadcast(_ context.Context, _ proto.Message) error {
+	mb.broadcastCalled = true
+	return nil
+}
+
+func (mb *mockBroadcaster) BroadcastAttestation(_ context.Context, _ uint64, _ *ethpb.Attestation) error {
+	mb.broadcastCalled = true
+	return nil
+}
+
+func (mb *mockBroadcaster) BroadcastSyncCommitteeMessage(_ context.Context, _ uint64, _ *ethpb.SyncCommitteeMessage) error {
+	mb.broadcastCalled = true
+	return nil
+}
+
+func (mb *mockBroadcaster) BroadcastBlob(_ context.Context, _ uint64, _ *ethpb.SignedBlobSidecar) error {
+	mb.broadcastCalled = true
+	return nil
+}
+
+func (mb *mockBroadcaster) BroadcastBLSChanges(_ context.Context, _ []*ethpb.SignedBLSToExecutionChange) {
+}
+
+var _ p2p.Broadcaster = (*mockBroadcaster)(nil)
+
+type testServiceRequirements struct {
+	ctx     context.Context
+	db      db.Database
+	fcs     forkchoice.ForkChoicer
+	sg      *stategen.State
+	notif   statefeed.Notifier
+	cs      *startup.ClockSynchronizer
+	attPool attestations.Pool
+	attSrv  *attestations.Service
+	blsPool *blstoexec.Pool
+	dc      *depositcache.DepositCache
+}
+
+func minimalTestService(t *testing.T, opts ...Option) (*Service, *testServiceRequirements) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	fcs := doublylinkedtree.New()
+	sg := stategen.New(beaconDB, fcs)
+	notif := &mockBeaconNode{}
+	fcs.SetBalancesByRooter(sg.ActiveNonSlashedBalancesByRoot)
+	cs := startup.NewClockSynchronizer()
+	attPool := attestations.NewPool()
+	attSrv, err := attestations.NewService(ctx, &attestations.Config{Pool: attPool})
+	require.NoError(t, err)
+	blsPool := blstoexec.NewPool()
+	dc, err := depositcache.New()
+	require.NoError(t, err)
+	req := &testServiceRequirements{
+		ctx:     ctx,
+		db:      beaconDB,
+		fcs:     fcs,
+		sg:      sg,
+		notif:   notif,
+		cs:      cs,
+		attPool: attPool,
+		attSrv:  attSrv,
+		blsPool: blsPool,
+		dc:      dc,
+	}
+	defOpts := []Option{WithDatabase(req.db),
+		WithStateNotifier(req.notif),
+		WithStateGen(req.sg),
+		WithForkChoiceStore(req.fcs),
+		WithClockSynchronizer(req.cs),
+		WithAttestationPool(req.attPool),
+		WithAttestationService(req.attSrv),
+		WithBLSToExecPool(req.blsPool),
+		WithDepositCache(dc),
+	}
+	// append the variadic opts so they override the defaults by being processed afterwards
+	opts = append(defOpts, opts...)
+	s, err := NewService(req.ctx, opts...)
+
+	require.NoError(t, err)
+	return s, req
+}
--- a/beacon-chain/blockchain/state_balance_cache.go
+++ b/beacon-chain/blockchain/state_balance_cache.go
@@ -1,81 +0,0 @@
-package blockchain
-
-import (
-	"context"
-	"errors"
-	"sync"
-
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/time"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
-)
-
-type stateBalanceCache struct {
-	sync.Mutex
-	balances []uint64
-	root     [32]byte
-	stateGen stateByRooter
-}
-
-type stateByRooter interface {
-	StateByRoot(context.Context, [32]byte) (state.BeaconState, error)
-}
-
-// newStateBalanceCache exists to remind us that stateBalanceCache needs a state gen
-// to avoid nil pointer bugs when updating the cache in the read path (get())
-func newStateBalanceCache(sg *stategen.State) (*stateBalanceCache, error) {
-	if sg == nil {
-		return nil, errors.New("can't initialize state balance cache without stategen")
-	}
-	return &stateBalanceCache{stateGen: sg}, nil
-}
-
-// update is called by get() when the requested root doesn't match
-// the previously read value. This cache assumes we only want to cache one
-// set of balances for a single root (the current justified root).
-//
-// WARNING: this is not thread-safe on its own, relies on get() for locking
-func (c *stateBalanceCache) update(ctx context.Context, justifiedRoot [32]byte) ([]uint64, error) {
-	stateBalanceCacheMiss.Inc()
-	justifiedState, err := c.stateGen.StateByRoot(ctx, justifiedRoot)
-	if err != nil {
-		return nil, err
-	}
-	if justifiedState == nil || justifiedState.IsNil() {
-		return nil, errNilStateFromStategen
-	}
-	epoch := time.CurrentEpoch(justifiedState)
-
-	justifiedBalances := make([]uint64, justifiedState.NumValidators())
-	var balanceAccumulator = func(idx int, val state.ReadOnlyValidator) error {
-		if helpers.IsActiveValidatorUsingTrie(val, epoch) {
-			justifiedBalances[idx] = val.EffectiveBalance()
-		} else {
-			justifiedBalances[idx] = 0
-		}
-		return nil
-	}
-	if err := justifiedState.ReadFromEveryValidator(balanceAccumulator); err != nil {
-		return nil, err
-	}
-
-	c.balances = justifiedBalances
-	c.root = justifiedRoot
-	return c.balances, nil
-}
-
-// getBalances takes an explicit justifiedRoot so it can invalidate the singleton cache key
-// when the justified root changes, and takes a context so that the long-running stategen
-// read path can connect to the upstream cancellation/timeout chain.
-func (c *stateBalanceCache) get(ctx context.Context, justifiedRoot [32]byte) ([]uint64, error) {
-	c.Lock()
-	defer c.Unlock()
-
-	if justifiedRoot != [32]byte{} && justifiedRoot == c.root {
-		stateBalanceCacheHit.Inc()
-		return c.balances, nil
-	}
-
-	return c.update(ctx, justifiedRoot)
-}
--- a/Show More
+++ b/Show More
@@ -1 +1 @@
 .3.0
 .1.0