draft for increasing gas limit

fix e2e scenario evaluators (#14798 )
* make fork evaluators conditional on fork for scenario tests * changelog
2026-01-10 05:47:59 -05:00 · 2025-01-16 11:49:02 -06:00 · 2025-01-16 04:38:26 +00:00 · 2025-01-16 00:14:56 +00:00 · 2025-01-15 23:50:10 +00:00 · 2025-01-15 21:36:09 +00:00
382 changed files with 27649 additions and 30071 deletions
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -33,5 +33,5 @@ Fixes #
 **Acknowledgements**

 - [ ] I have read [CONTRIBUTING.md](https://github.com/prysmaticlabs/prysm/blob/develop/CONTRIBUTING.md).
- [ ] I have made an appropriate entry to [CHANGELOG.md](https://github.com/prysmaticlabs/prysm/blob/develop/CHANGELOG.md).
+- [ ] I have included a uniquely named [changelog fragment file](https://github.com/prysmaticlabs/prysm/blob/develop/CONTRIBUTING.md#maintaining-changelogmd).
 - [ ] I have added a description to this PR with sufficient context for reviewers to understand this PR.
--- a/.github/workflows/changelog.yml
+++ b/.github/workflows/changelog.yml
@@ -1,33 +1,34 @@
-name: CI
+# This workflow will build a golang project
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-go
+
+name: changelog

 on:
  pull_request:
-    branches:
-      - develop
+    branches: [ "develop" ]

 jobs:
-  changed_files:
-    runs-on: ubuntu-latest 
-    name: Check CHANGELOG.md
+  run-changelog-check:
+    runs-on: ubuntu-latest
    steps:
-      - uses: actions/checkout@v4
-      - name: changelog modified
-        id: changelog-modified
+      - name: Checkout source code
+        uses: actions/checkout@v3
+
+      - name: Download unclog binary
+        uses: dsaltares/fetch-gh-release-asset@aa2ab1243d6e0d5b405b973c89fa4d06a2d0fff7 # 1.1.2
+        with:
+          repo: OffchainLabs/unclog
+          version: "tags/v0.1.3"
+          file: "unclog"
+
+      - name: Get new changelog files
+        id: new-changelog-files
        uses: tj-actions/changed-files@v45
        with:
-          files: CHANGELOG.md
+          files: |
+            changelog/**.md

-      - name: List all changed files
+      - name: Run lint command
        env:
-          ALL_CHANGED_FILES: ${{ steps.changelog-modified.outputs.all_changed_files }}
-        run: |
-          if [[ ${ALL_CHANGED_FILES[*]} =~ (^|[[:space:]])"CHANGELOG.md"($|[[:space:]]) ]];
-          then
-            echo "CHANGELOG.md was modified.";
-            exit 0;
-          else
-            echo "CHANGELOG.md was not modified.";
-            echo "Please see CHANGELOG.md and follow the instructions to add your changes to that file."
-            echo "In some rare scenarios, a changelog entry is not required and this CI check can be ignored."
-            exit 1;
-          fi
+          ALL_ADDED_MARKDOWN: ${{ steps.new-changelog-files.outputs.added_files }}
+        run: chmod +x unclog && ./unclog check -fragment-env=ALL_ADDED_MARKDOWN
--- a/.github/workflows/fuzz.yml
+++ b/.github/workflows/fuzz.yml
@@ -16,7 +16,7 @@ jobs:
      - uses: actions/checkout@v3
      - uses: actions/setup-go@v4
        with:
-          go-version: '1.22.3'
+          go-version: '1.22.10'
      - id: list
        uses: shogo82148/actions-go-fuzz/list@v0
        with:
@@ -36,7 +36,7 @@ jobs:
      - uses: actions/checkout@v3
      - uses: actions/setup-go@v4
        with:
-          go-version: '1.22.3'
+          go-version: '1.22.10'
      - uses: shogo82148/actions-go-fuzz/run@v0
        with:
          packages: ${{ matrix.package }}
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -31,7 +31,7 @@ jobs:
      - name: Set up Go 1.22
        uses: actions/setup-go@v4
        with:
-          go-version: '1.22.6'
+          go-version: '1.22.10'
      - name: Run Gosec Security Scanner
        run: | # https://github.com/securego/gosec/issues/469
          export PATH=$PATH:$(go env GOPATH)/bin
@@ -48,7 +48,7 @@ jobs:
      - name: Set up Go 1.22
        uses: actions/setup-go@v4
        with:
-          go-version: '1.22.6'
+          go-version: '1.22.10'
          id: go

      - name: Golangci-lint
@@ -64,7 +64,7 @@ jobs:
      - name: Set up Go 1.x
        uses: actions/setup-go@v4
        with:
-          go-version: '1.22.6'
+          go-version: '1.22.10'
        id: go

      - name: Check out code into the Go module directory
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -6,7 +6,7 @@ run:
    - proto
    - tools/analyzers
  timeout: 10m
-  go: '1.22.6'
+  go: '1.22.10'

 linters:
  enable-all: true
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,38 +4,6 @@ All notable changes to this project will be documented in this file.

 The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

-## [Unreleased](https://github.com/prysmaticlabs/prysm/compare/v5.2.0...HEAD)
-
-### Added
-
- Added proper gas limit check for header from the builder.
- Added an error field to log `Finished building block`.
- Implemented a new `EmptyExecutionPayloadHeader` function.
- `Finished building block`: Display error only if not nil.
- Added support to update target and max blob count to different values per hard fork config.
- Log before blob filesystem cache warm-up.
- 
-### Changed
-
- Process light client finality updates only for new finalized epochs instead of doing it for every block.
- Refactor subnets subscriptions.
- Refactor RPC handlers subscriptions.
- Go deps upgrade, from `ioutil` to `io`
- Move successfully registered validator(s) on builder log to debug.
-
-### Deprecated
-
-
-### Removed
-
-
-### Fixed
-
- Added check to prevent nil pointer deference or out of bounds array access when validating the BLSToExecutionChange on an impossibly nil validator.
-
-### Security
-
-
 ## [v5.2.0](https://github.com/prysmaticlabs/prysm/compare/v5.1.2...v5.2.0)

 Updating to this release is highly recommended, especially for users running v5.1.1 or v5.1.2.
@@ -82,6 +50,7 @@ Notable features:
 - Save light client updates and bootstraps in DB.
 - Added more comprehensive tests for `BlockToLightClientHeader`. [PR](https://github.com/prysmaticlabs/prysm/pull/14699)
 - Added light client feature flag check to RPC handlers. [PR](https://github.com/prysmaticlabs/prysm/pull/14736)
+- Light client: Add better error handling. [PR](https://github.com/prysmaticlabs/prysm/pull/14749)

 ### Changed

@@ -137,7 +106,7 @@ Notable features:
 - Removed finalized validator index cache, no longer needed.
 - Removed validator queue position log on key reload and wait for activation.
 - Removed outdated spectest exclusions for EIP-6110.
- Removed support for starting a beacon node with a deterministic interop genesis state via interop flags. Alteratively, create a genesis state with prysmctl and use `--genesis-state`. This removes about 9Mb (~11%) of unnecessary code and dependencies from the final production binary.
+- Removed support for starting a beacon node with a deterministic interop genesis state via interop flags. Alternatively, create a genesis state with prysmctl and use `--genesis-state`. This removes about 9Mb (~11%) of unnecessary code and dependencies from the final production binary.
 - Removed kzg proof check from blob reconstructor.

 ### Fixed
@@ -151,7 +120,7 @@ Notable features:
 - Fix `--backfill-oldest-slot` handling - this flag was totally broken, the code would always backfill to the default slot [pr](https://github.com/prysmaticlabs/prysm/pull/14584)
 - Fix keymanager API should return corrected error format for malformed tokens
 - Fix keymanager API so that get keys returns an empty response instead of a 500 error when using an unsupported keystore.
- Small log imporvement, removing some redundant or duplicate logs
+- Small log improvement, removing some redundant or duplicate logs
 - EIP7521 - Fixes withdrawal bug by accounting for pending partial withdrawals and deducting already withdrawn amounts from the sweep balance. [PR](https://github.com/prysmaticlabs/prysm/pull/14578)
 - unskip electra merkle spec test
 - Fix panic in validator REST mode when checking status after removing all keys
@@ -181,7 +150,7 @@ meantime we are issuing a patch that recovers from the panic to prevent the node

 This only impacts the v5.1.1 release beacon api event stream endpoints. This endpoint is used by the
 prysm REST mode validator (a feature which requires the validator to be configured to use the beacon
-api intead of prysm's stock grpc endpoints) or accessory software that connects to the events api,
+api instead of prysm's stock grpc endpoints) or accessory software that connects to the events api,
 like https://github.com/ethpandaops/ethereum-metrics-exporter

 ### Fixed 
@@ -424,7 +393,7 @@ Updating to this release is recommended at your earliest convenience, especially
 - use time.NewTimer() to avoid possible memory leaks
 - paranoid underflow protection without error handling
 - Fix CommitteeAssignments to not return every validator
- Fix dependent root retrival genesis case
+- Fix dependent root retrieval genesis case
 - Restrict Dials From Discovery
 - Always close cache warm chan to prevent blocking
 - Keep only the latest value in the health channel
@@ -576,7 +545,7 @@ block profit. If you want to preserve the existing behavior, set --local-block-v
 - handle special case of batch size=1
 - Always Set Inprogress Boolean In Cache
 - Builder APIs: adding headers to post endpoint
- Rename mispelled variable
+- Rename misspelled variable
 - allow blob by root within da period
 - Rewrite Pruning Implementation To Handle EIP 7045
 - Set default fee recipient if tracked val fails
@@ -646,7 +615,7 @@ Known Issues
 - Support beacon_committee_selections
 - /eth/v1/beacon/deposit_snapshot
 - Docker images now have coreutils pre-installed
- da_waited_time_milliseconds tracks total time waiting for data availablity check in ReceiveBlock
+- da_waited_time_milliseconds tracks total time waiting for data availability check in ReceiveBlock
 - blob_written, blob_disk_count, blob_disk_bytes new metrics for tracking blobs on disk
 - Backfill supports blob backfilling
 - Add mainnet deneb fork epoch config
@@ -821,7 +790,7 @@ and Raspberry Pi users.
 - Add Goerli Deneb Fork Epoch
 - Use deneb key for deneb state in saveStatesEfficientInternal
 - Initialize Inactivity Scores Correctly
- Excluse DA wait time for chain processing time
+- Excludes DA wait time for chain processing time
 - Initialize sig cache for verification.Initializer
 - Verify roblobs
 - KZG Commitment inclusion proof verifier
@@ -854,7 +823,7 @@ and Raspberry Pi users.
 - Exit early if blob by root request is empty
 - Request missing blobs while processing pending queue
 - Check blob exists before requesting from peer
- Passing block as arugment for sidecar validation
+- Passing block as argument for sidecar validation

 #### Blob Management

@@ -1151,13 +1120,13 @@ _Most of the PRs here involve shifting our http endpoints to using vanilla http
 - Remove no-op cancel func
 - Update Terms of Service
 - fix head slot in log
- DEPRECTATION: Remove exchange transition configuration call
+- DEPRECATION: Remove exchange transition configuration call
 - fix segmentation fork when Capella for epoch is MaxUint64
 - Return Error Gracefully When Removing 4881 Flag
 - Add zero length check on indices during NextSyncCommitteeIndices
 - Replace Empty Slice Literals with Nil Slices
 - Refactor Error String Formatting According to Go Best Practices
- Fix redundant type converstion
+- Fix redundant type conversion
 - docs: fix typo
 - Add Clarification To Sync Committee Cache
 - Fix typos
@@ -1179,7 +1148,7 @@ small set of users.

 ### Security

-No security issues in thsi release.
+No security issues in this release.

 ## [v4.1.0](https://github.com/prysmaticlabs/prysm/compare/v4.0.8...v4.1.0) - 2023-08-22

@@ -1695,7 +1664,7 @@ notes [here](https://hackmd.io/TtyFurRJRKuklG3n8lMO9Q). This release is **strong
 Note: The released docker images are using the portable version of the blst cryptography library. The Prysm team will
 release docker images with the non-portable blst library as the default image. In the meantime, you can compile docker
 images with blst non-portable locally with the `--define=blst_modern=true` bazel flag, use the "-modern-" assets
-attached to releases, or set environment varaible USE_PRYSM_MODERN=true when using prysm.sh.
+attached to releases, or set environment variable USE_PRYSM_MODERN=true when using prysm.sh.

 ### Added

@@ -2044,7 +2013,7 @@ There are some known issues with this release.
 - Beacon node can bootstrap from non-genesis state (i.e bellatrix state)
 - Refactor bytesutil, add support for go1.20 slice to array conversions
 - Add Span information for attestation record save request
- Matric addition
+- Metric addition
 - Identify invalid signature within batch verification
 - Support for getting consensus values from beacon config
 - EIP-4881: Spec implementation
@@ -2110,7 +2079,7 @@ See [flashbots/mev-boost#404](https://github.com/flashbots/mev-boost/issues/404)
 - Added more histogram metrics for block arrival latency times block_arrival_latency_milliseconds
 - Priority queue RetrieveByKey now uses read lock instead of write lock
 - Use custom types for certain ethclient requests. Fixes an issue when using prysm on gnosis chain.
- Updted forkchoice endpoint /eth/v1/debug/forkchoice (was /eth/v1/debug/beacon/forkchoice)
+- Updated forkchoice endpoint /eth/v1/debug/forkchoice (was /eth/v1/debug/beacon/forkchoice)
 - Include empty fields in builder json client.
 - Computing committee assignments for slots older than the oldest historical root in the beacon state is now forbidden

@@ -2342,7 +2311,7 @@ There are no security updates in this release.
  removed: `GetBeaconState`, `ProduceBlock`, `ListForkChoiceHeads`, `ListBlocks`, `SubmitValidatorRegistration`, `GetBlock`, `ProposeBlock`
 - API: Forkchoice method `GetForkChoice` has been removed.
 - All previously deprecated feature flags have been
-  removed. `--enable-active-balance-cache`, `--correctly-prune-canonical-atts`, `--correctly-insert-orphaned-atts`, `--enable-next-slot-state-cache`, `--enable-batch-gossip-verification`, `--enable-get-block-optimizations`, `--enable-balance-trie-computation`, `--disable-next-slot-state-cache`, `--attestation-aggregation-strategy`, `--attestation-aggregation-force-opt-maxcover`, `--pyrmont`, `--disable-get-block-optimizations`, `--disable-proposer-atts-selection-using-max-cover`, `--disable-optimized-balance-update`, `--disable-active-balance-cache`, `--disable-balance-trie-computation`, `--disable-batch-gossip-verification`, `--disable-correctly-prune-canonical-atts`, `--disable-correctly-insert-orphaned-atts`, `--enable-native-state`, `--enable-peer-scorer`, `--enable-gossip-batch-aggregation`, `--experimental-disable-boundry-checks`
+  removed. `--enable-active-balance-cache`, `--correctly-prune-canonical-atts`, `--correctly-insert-orphaned-atts`, `--enable-next-slot-state-cache`, `--enable-batch-gossip-verification`, `--enable-get-block-optimizations`, `--enable-balance-trie-computation`, `--disable-next-slot-state-cache`, `--attestation-aggregation-strategy`, `--attestation-aggregation-force-opt-maxcover`, `--pyrmont`, `--disable-get-block-optimizations`, `--disable-proposer-atts-selection-using-max-cover`, `--disable-optimized-balance-update`, `--disable-active-balance-cache`, `--disable-balance-trie-computation`, `--disable-batch-gossip-verification`, `--disable-correctly-prune-canonical-atts`, `--disable-correctly-insert-orphaned-atts`, `--enable-native-state`, `--enable-peer-scorer`, `--enable-gossip-batch-aggregation`, `--experimental-disable-boundary-checks`
 - Validator Web API: Removed unused ImportAccounts and DeleteAccounts rpc options

 ### Fixed
@@ -2558,7 +2527,7 @@ There are two known issues with this release:
 - Bellatrix support. See [kiln testnet instructions](https://hackmd.io/OqIoTiQvS9KOIataIFksBQ?view)
 - Weak subjectivity sync / checkpoint sync. This is an experimental feature and may have unintended side effects for
  certain operators serving historical data. See
-  the [documentation](https://docs.prylabs.network/docs/next/prysm-usage/checkpoint-sync) for more details.
+  the [documentation](https://docs.prylabs.network/docs/prysm-usage/checkpoint-sync) for more details.
 - A faster build of blst for beacon chain on linux amd64. Use the environment variable `USE_PRYSM_MODERN=true` with
  prysm.sh, use the "modern" binary, or bazel build with `--define=blst_modern=true`.
 - Vectorized sha256. This may have performance improvements with use of the new flag `--enable-vectorized-htr`.
@@ -2739,7 +2708,7 @@ notes [here](https://github.com/prysmaticlabs/prysm-web-ui/releases/tag/v1.0.0)
 - Added uint64 overflow protection
 - Sync committee pool returns empty slice instead of nil on cache miss
 - Improved description of datadir flag
- Simplied web password requirements
+- Simplified web password requirements
 - Web JWT tokens no longer expire.
 - Updated keymanager protos
 - Watch and update jwt secret when auth token file updated on disk.
@@ -2750,7 +2719,7 @@ notes [here](https://github.com/prysmaticlabs/prysm-web-ui/releases/tag/v1.0.0)
 - Refactor for weak subjectivity sync implementation
 - Update naming for Atlair previous epoch attester
 - Remove duplicate MerkleizeTrieLeaves method.
- Add explict error for validator flag checks on out of bound positions
+- Add explicit error for validator flag checks on out of bound positions
 - Simplify method to check if the beacon chain client should update the justified epoch value.
 - Rename web UI performance endpoint to "summary"
 - Refactor powchain service to be more functional
@@ -2776,7 +2745,7 @@ notes [here](https://github.com/prysmaticlabs/prysm-web-ui/releases/tag/v1.0.0)
  Upstream go-ethereum is now used with familiar go.mod tooling.
 - Removed duplicate aggergation validation p2p pipelines.
 - Metrics calculation removed extra condition
- Removed superflous errors from peer scoring parameters registration
+- Removed superfluous errors from peer scoring parameters registration

 ### Fixed

--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -125,7 +125,7 @@ Navigate to your fork of the repo on GitHub. On the upper left where the current

 **16. Add an entry to CHANGELOG.md.**

-If your change is user facing, you must include a CHANGELOG.md entry. See the [Maintaining CHANGELOG.md](#maintaining-changelogmd) section for more information.
+All PRs must must include a changelog fragment file in the `changelog` directory. If your change is not user-facing or should not be mentioned in the changelog for some other reason, you may use the `Ignored` changelog section in your fragment's header to satisfy this requirement without altering the final release changelog. See the [Maintaining CHANGELOG.md](#maintaining-changelogmd) section for more information.

 **17. Create a pull request.**

@@ -177,16 +177,10 @@ $ git push myrepo feature-in-progress-branch -f

 ## Maintaining CHANGELOG.md

-This project follows the changelog guidelines from [keepachangelog.com](https://keepachangelog.com/en/1.1.0/).
-
-All PRs with user facing changes should have an entry in the CHANGELOG.md file and the change should be categorized in the appropriate category within the "Unreleased" section. The categories are:
-
-  `Added` for new features.
-  `Changed` for changes in existing functionality.
-  `Deprecated` for soon-to-be removed features.
-  `Removed` for now removed features.
-  `Fixed` for any bug fixes.
-  `Security` in case of vulnerabilities. Please see the [Security Policy](SECURITY.md) for responsible disclosure before adding a change with this category.
+This project follows the changelog guidelines from [keepachangelog.com](https://keepachangelog.com/en/1.1.0/). In order to minimize conflicts and workflow headaches, we chose to implement a changelog management
+strategy that uses changelog "fragment" files, managed by our changelog management tool called `unclog`. Each PR must include a new changelog fragment file in the `changelog` directory, as specified by unclog's
+[README.md](https://github.com/OffchainLabs/unclog?tab=readme-ov-file#what-is-a-changelog-fragment). As the `unclog` README suggests in the [Best Practices](https://github.com/OffchainLabs/unclog?tab=readme-ov-file#best-practices) section, 
+the standard naming convention for your PR's fragment file, to avoid conflicting with another fragment file, is `changelog/<github user name>_<PR branch name>.md`.

 ### Releasing

--- a/INTEROP.md
+++ b/INTEROP.md
@@ -4,7 +4,7 @@ This README details how to setup Prysm for interop testing for usage with other

 > [!IMPORTANT]  
 > This guide is likely to be outdated. The Prysm team does not have capacity to troubleshoot
-> outdated interop guides or instructions. If you experience issues with this guide, please file and
+> outdated interop guides or instructions. If you experience issues with this guide, please file an
 > issue for visibility and propose fixes, if possible.

 ## Installation & Setup
@@ -74,19 +74,19 @@ bazel run //cmd/beacon-chain --config=minimal -- \
 This will start the system with 256 validators. The flags used can be explained as such:

 - `bazel run //cmd/beacon-chain --config=minimal` builds and runs the beacon node in minimal build configuration.
- `--` is a flag divider to distingish between bazel flags and flags that should be passed to the application. All flags and arguments after this divider are passed to the beacon chain.
+- `--` is a flag divider to distinguish between bazel flags and flags that should be passed to the application. All flags and arguments after this divider are passed to the beacon chain.
 - `--minimal-config` tells the beacon node to use minimal network configuration. This is different from the compile time state configuration flag `--config=minimal` and both are required.
 - `--bootstrap-node=` disables the default bootstrap nodes. This prevents the client from attempting to peer with mainnet nodes.
 - `--datadir=/tmp/beacon-chain-minimal-devnet` sets the data directory in a temporary location. Change this to your preferred destination.
 - `--force-clear-db` will delete the beaconchain.db file without confirming with the user. This is helpful for iteratively running local devnets without changing the datadir, but less helpful for one off runs where there was no database in the data directory.
- `--min-sync-peers=0` allows the beacon node to skip initial sync without peers. This is essential because Prysm expects at least a few peers to start start the blockchain.
+- `--min-sync-peers=0` allows the beacon node to skip initial sync without peers. This is essential because Prysm expects at least a few peers to start the blockchain.
 - `--genesis-state=/tmp/genesis.ssz` defines the path to the generated genesis ssz file. The beacon node will use this as the initial genesis state.
 - `--chain-config-file=/tmp/minimal.yaml` defines the path to the yaml file with the chain configuration.

 As soon as the beacon node has started, start the validator in the other terminal window. 

 ```
-bazel run //cmd/validator --config=minimal -- --datadir=/tmp/validator --interopt-num-validators=256 --minimal-config --suggested-fee-recipient=0x8A04d14125D0FDCDc742F4A05C051De07232EDa4
+bazel run //cmd/validator --config=minimal -- --datadir=/tmp/validator --interop-num-validators=256 --minimal-config --suggested-fee-recipient=0x8A04d14125D0FDCDc742F4A05C051De07232EDa4
 ```

 This will launch and kickstart the system with your 256 validators performing their duties accordingly.
--- a/12
+++ b/12
@@ -182,7 +182,7 @@ load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_depe
 go_rules_dependencies()

 go_register_toolchains(
-    go_version = "1.22.4",
+    go_version = "1.22.10",
    nogo = "@//:nogo",
 )

@@ -227,7 +227,7 @@ filegroup(
    url = "https://github.com/ethereum/EIPs/archive/5480440fe51742ed23342b68cf106cefd427e39d.tar.gz",
 )

-consensus_spec_version = "v1.5.0-alpha.9"
+consensus_spec_version = "v1.5.0-beta.0"

 bls_test_version = "v0.1.1"

@@ -243,7 +243,7 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    integrity = "sha256-gHbvlnErUeJGWzW8/8JiVlk28JwmXSMhOzkynEIz+8g=",
+    integrity = "sha256-HdMlTN3wv+hUMCkIRPk+EHcLixY1cSZlvkx3obEp4AM=",
    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/general.tar.gz" % consensus_spec_version,
 )

@@ -259,7 +259,7 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    integrity = "sha256-hQkQdpm5ng4miGYa5WsOKWa0q8WtZu99Oqbv9QtBeJM=",
+    integrity = "sha256-eX/ihmHQ+OvfoGJxSMgy22yAU3SZ3xjsX0FU0EaZrSs=",
    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/minimal.tar.gz" % consensus_spec_version,
 )

@@ -275,7 +275,7 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    integrity = "sha256-33sBsmApnJpcyYfR3olKaPB+WC1q00ZKNzHa2TczIxk=",
+    integrity = "sha256-k3Onf42vOzIqyddecR6G82sDy3mmDA+R8RN66QjB0GI=",
    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/mainnet.tar.gz" % consensus_spec_version,
 )

@@ -290,7 +290,7 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    integrity = "sha256-GQulBKLc2khpql2K/MxV+NG/d2kAhLXl+gLnKIg7rt4=",
+    integrity = "sha256-N/d4AwdOSlb70Dr+2l20dfXxNSzJDj/qKA9Rkn8Gb5w=",
    strip_prefix = "consensus-specs-" + consensus_spec_version[1:],
    url = "https://github.com/ethereum/consensus-specs/archive/refs/tags/%s.tar.gz" % consensus_spec_version,
 )
--- a/api/client/builder/client_test.go
+++ b/api/client/builder/client_test.go
@@ -16,7 +16,6 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/blocks"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
-	types "github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v5/encoding/bytesutil"
 	v1 "github.com/prysmaticlabs/prysm/v5/proto/engine/v1"
 	eth "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
@@ -124,7 +123,7 @@ func TestClient_RegisterValidator(t *testing.T) {
 func TestClient_GetHeader(t *testing.T) {
 	ctx := context.Background()
 	expectedPath := "/eth/v1/builder/header/23/0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2/0x93247f2209abcacf57b75a51dafae777f9dd38bc7053d1af526f220a7489a6d3a2753e5f3e8b1cfe39b56f43611df74a"
-	var slot types.Slot = 23
+	var slot primitives.Slot = 23
 	parentHash := ezDecode(t, "0xcf8e0d4e9587369b2301d0790347320302cc0943d5a1884560367e8208d920f2")
 	pubkey := ezDecode(t, "0x93247f2209abcacf57b75a51dafae777f9dd38bc7053d1af526f220a7489a6d3a2753e5f3e8b1cfe39b56f43611df74a")
 	t.Run("server error", func(t *testing.T) {
@@ -370,7 +369,7 @@ func TestSubmitBlindedBlock(t *testing.T) {
 		require.NoError(t, err)
 		require.Equal(t, 1, len(withdrawals))
 		assert.Equal(t, uint64(1), withdrawals[0].Index)
-		assert.Equal(t, types.ValidatorIndex(1), withdrawals[0].ValidatorIndex)
+		assert.Equal(t, primitives.ValidatorIndex(1), withdrawals[0].ValidatorIndex)
 		assert.DeepEqual(t, ezDecode(t, "0xcf8e0d4e9587369b2301d0790347320302cc0943"), withdrawals[0].Address)
 		assert.Equal(t, uint64(1), withdrawals[0].Amount)
 	})
@@ -409,7 +408,7 @@ func TestSubmitBlindedBlock(t *testing.T) {
 		require.NoError(t, err)
 		require.Equal(t, 1, len(withdrawals))
 		assert.Equal(t, uint64(1), withdrawals[0].Index)
-		assert.Equal(t, types.ValidatorIndex(1), withdrawals[0].ValidatorIndex)
+		assert.Equal(t, primitives.ValidatorIndex(1), withdrawals[0].ValidatorIndex)
 		assert.DeepEqual(t, ezDecode(t, "0xcf8e0d4e9587369b2301d0790347320302cc0943"), withdrawals[0].Address)
 		assert.Equal(t, uint64(1), withdrawals[0].Amount)
 		require.NotNil(t, blobBundle)
--- a/api/server/structs/block.go
+++ b/api/server/structs/block.go
@@ -14,6 +14,10 @@ type SignedMessageJsoner interface {
 	SigString() string
 }

+// ----------------------------------------------------------------------------
+// Phase 0
+// ----------------------------------------------------------------------------
+
 type SignedBeaconBlock struct {
 	Message   *BeaconBlock `json:"message"`
 	Signature string       `json:"signature"`
@@ -48,6 +52,29 @@ type BeaconBlockBody struct {
 	VoluntaryExits    []*SignedVoluntaryExit `json:"voluntary_exits"`
 }

+type SignedBeaconBlockHeaderContainer struct {
+	Header    *SignedBeaconBlockHeader `json:"header"`
+	Root      string                   `json:"root"`
+	Canonical bool                     `json:"canonical"`
+}
+
+type SignedBeaconBlockHeader struct {
+	Message   *BeaconBlockHeader `json:"message"`
+	Signature string             `json:"signature"`
+}
+
+type BeaconBlockHeader struct {
+	Slot          string `json:"slot"`
+	ProposerIndex string `json:"proposer_index"`
+	ParentRoot    string `json:"parent_root"`
+	StateRoot     string `json:"state_root"`
+	BodyRoot      string `json:"body_root"`
+}
+
+// ----------------------------------------------------------------------------
+// Altair
+// ----------------------------------------------------------------------------
+
 type SignedBeaconBlockAltair struct {
 	Message   *BeaconBlockAltair `json:"message"`
 	Signature string             `json:"signature"`
@@ -83,6 +110,10 @@ type BeaconBlockBodyAltair struct {
 	SyncAggregate     *SyncAggregate         `json:"sync_aggregate"`
 }

+// ----------------------------------------------------------------------------
+// Bellatrix
+// ----------------------------------------------------------------------------
+
 type SignedBeaconBlockBellatrix struct {
 	Message   *BeaconBlockBellatrix `json:"message"`
 	Signature string                `json:"signature"`
@@ -155,6 +186,44 @@ type BlindedBeaconBlockBodyBellatrix struct {
 	ExecutionPayloadHeader *ExecutionPayloadHeader `json:"execution_payload_header"`
 }

+type ExecutionPayload struct {
+	ParentHash    string   `json:"parent_hash"`
+	FeeRecipient  string   `json:"fee_recipient"`
+	StateRoot     string   `json:"state_root"`
+	ReceiptsRoot  string   `json:"receipts_root"`
+	LogsBloom     string   `json:"logs_bloom"`
+	PrevRandao    string   `json:"prev_randao"`
+	BlockNumber   string   `json:"block_number"`
+	GasLimit      string   `json:"gas_limit"`
+	GasUsed       string   `json:"gas_used"`
+	Timestamp     string   `json:"timestamp"`
+	ExtraData     string   `json:"extra_data"`
+	BaseFeePerGas string   `json:"base_fee_per_gas"`
+	BlockHash     string   `json:"block_hash"`
+	Transactions  []string `json:"transactions"`
+}
+
+type ExecutionPayloadHeader struct {
+	ParentHash       string `json:"parent_hash"`
+	FeeRecipient     string `json:"fee_recipient"`
+	StateRoot        string `json:"state_root"`
+	ReceiptsRoot     string `json:"receipts_root"`
+	LogsBloom        string `json:"logs_bloom"`
+	PrevRandao       string `json:"prev_randao"`
+	BlockNumber      string `json:"block_number"`
+	GasLimit         string `json:"gas_limit"`
+	GasUsed          string `json:"gas_used"`
+	Timestamp        string `json:"timestamp"`
+	ExtraData        string `json:"extra_data"`
+	BaseFeePerGas    string `json:"base_fee_per_gas"`
+	BlockHash        string `json:"block_hash"`
+	TransactionsRoot string `json:"transactions_root"`
+}
+
+// ----------------------------------------------------------------------------
+// Capella
+// ----------------------------------------------------------------------------
+
 type SignedBeaconBlockCapella struct {
 	Message   *BeaconBlockCapella `json:"message"`
 	Signature string              `json:"signature"`
@@ -229,6 +298,46 @@ type BlindedBeaconBlockBodyCapella struct {
 	BLSToExecutionChanges  []*SignedBLSToExecutionChange  `json:"bls_to_execution_changes"`
 }

+type ExecutionPayloadCapella struct {
+	ParentHash    string        `json:"parent_hash"`
+	FeeRecipient  string        `json:"fee_recipient"`
+	StateRoot     string        `json:"state_root"`
+	ReceiptsRoot  string        `json:"receipts_root"`
+	LogsBloom     string        `json:"logs_bloom"`
+	PrevRandao    string        `json:"prev_randao"`
+	BlockNumber   string        `json:"block_number"`
+	GasLimit      string        `json:"gas_limit"`
+	GasUsed       string        `json:"gas_used"`
+	Timestamp     string        `json:"timestamp"`
+	ExtraData     string        `json:"extra_data"`
+	BaseFeePerGas string        `json:"base_fee_per_gas"`
+	BlockHash     string        `json:"block_hash"`
+	Transactions  []string      `json:"transactions"`
+	Withdrawals   []*Withdrawal `json:"withdrawals"`
+}
+
+type ExecutionPayloadHeaderCapella struct {
+	ParentHash       string `json:"parent_hash"`
+	FeeRecipient     string `json:"fee_recipient"`
+	StateRoot        string `json:"state_root"`
+	ReceiptsRoot     string `json:"receipts_root"`
+	LogsBloom        string `json:"logs_bloom"`
+	PrevRandao       string `json:"prev_randao"`
+	BlockNumber      string `json:"block_number"`
+	GasLimit         string `json:"gas_limit"`
+	GasUsed          string `json:"gas_used"`
+	Timestamp        string `json:"timestamp"`
+	ExtraData        string `json:"extra_data"`
+	BaseFeePerGas    string `json:"base_fee_per_gas"`
+	BlockHash        string `json:"block_hash"`
+	TransactionsRoot string `json:"transactions_root"`
+	WithdrawalsRoot  string `json:"withdrawals_root"`
+}
+
+// ----------------------------------------------------------------------------
+// Deneb
+// ----------------------------------------------------------------------------
+
 type SignedBeaconBlockContentsDeneb struct {
 	SignedBlock *SignedBeaconBlockDeneb `json:"signed_block"`
 	KzgProofs   []string                `json:"kzg_proofs"`
@@ -317,6 +426,50 @@ type BlindedBeaconBlockBodyDeneb struct {
 	BlobKzgCommitments     []string                      `json:"blob_kzg_commitments"`
 }

+type ExecutionPayloadDeneb struct {
+	ParentHash    string        `json:"parent_hash"`
+	FeeRecipient  string        `json:"fee_recipient"`
+	StateRoot     string        `json:"state_root"`
+	ReceiptsRoot  string        `json:"receipts_root"`
+	LogsBloom     string        `json:"logs_bloom"`
+	PrevRandao    string        `json:"prev_randao"`
+	BlockNumber   string        `json:"block_number"`
+	GasLimit      string        `json:"gas_limit"`
+	GasUsed       string        `json:"gas_used"`
+	Timestamp     string        `json:"timestamp"`
+	ExtraData     string        `json:"extra_data"`
+	BaseFeePerGas string        `json:"base_fee_per_gas"`
+	BlockHash     string        `json:"block_hash"`
+	Transactions  []string      `json:"transactions"`
+	Withdrawals   []*Withdrawal `json:"withdrawals"`
+	BlobGasUsed   string        `json:"blob_gas_used"`
+	ExcessBlobGas string        `json:"excess_blob_gas"`
+}
+
+type ExecutionPayloadHeaderDeneb struct {
+	ParentHash       string `json:"parent_hash"`
+	FeeRecipient     string `json:"fee_recipient"`
+	StateRoot        string `json:"state_root"`
+	ReceiptsRoot     string `json:"receipts_root"`
+	LogsBloom        string `json:"logs_bloom"`
+	PrevRandao       string `json:"prev_randao"`
+	BlockNumber      string `json:"block_number"`
+	GasLimit         string `json:"gas_limit"`
+	GasUsed          string `json:"gas_used"`
+	Timestamp        string `json:"timestamp"`
+	ExtraData        string `json:"extra_data"`
+	BaseFeePerGas    string `json:"base_fee_per_gas"`
+	BlockHash        string `json:"block_hash"`
+	TransactionsRoot string `json:"transactions_root"`
+	WithdrawalsRoot  string `json:"withdrawals_root"`
+	BlobGasUsed      string `json:"blob_gas_used"`
+	ExcessBlobGas    string `json:"excess_blob_gas"`
+}
+
+// ----------------------------------------------------------------------------
+// Electra
+// ----------------------------------------------------------------------------
+
 type SignedBeaconBlockContentsElectra struct {
 	SignedBlock *SignedBeaconBlockElectra `json:"signed_block"`
 	KzgProofs   []string                  `json:"kzg_proofs"`
@@ -362,7 +515,7 @@ type BeaconBlockBodyElectra struct {
 	Deposits              []*Deposit                    `json:"deposits"`
 	VoluntaryExits        []*SignedVoluntaryExit        `json:"voluntary_exits"`
 	SyncAggregate         *SyncAggregate                `json:"sync_aggregate"`
-	ExecutionPayload      *ExecutionPayloadElectra      `json:"execution_payload"`
+	ExecutionPayload      *ExecutionPayloadDeneb        `json:"execution_payload"`
 	BLSToExecutionChanges []*SignedBLSToExecutionChange `json:"bls_to_execution_changes"`
 	BlobKzgCommitments    []string                      `json:"blob_kzg_commitments"`
 	ExecutionRequests     *ExecutionRequests            `json:"execution_requests"`
@@ -392,156 +545,119 @@ func (s *SignedBlindedBeaconBlockElectra) SigString() string {
 }

 type BlindedBeaconBlockBodyElectra struct {
-	RandaoReveal           string                         `json:"randao_reveal"`
-	Eth1Data               *Eth1Data                      `json:"eth1_data"`
-	Graffiti               string                         `json:"graffiti"`
-	ProposerSlashings      []*ProposerSlashing            `json:"proposer_slashings"`
-	AttesterSlashings      []*AttesterSlashingElectra     `json:"attester_slashings"`
-	Attestations           []*AttestationElectra          `json:"attestations"`
-	Deposits               []*Deposit                     `json:"deposits"`
-	VoluntaryExits         []*SignedVoluntaryExit         `json:"voluntary_exits"`
-	SyncAggregate          *SyncAggregate                 `json:"sync_aggregate"`
-	ExecutionPayloadHeader *ExecutionPayloadHeaderElectra `json:"execution_payload_header"`
-	BLSToExecutionChanges  []*SignedBLSToExecutionChange  `json:"bls_to_execution_changes"`
-	BlobKzgCommitments     []string                       `json:"blob_kzg_commitments"`
-	ExecutionRequests      *ExecutionRequests             `json:"execution_requests"`
+	RandaoReveal           string                        `json:"randao_reveal"`
+	Eth1Data               *Eth1Data                     `json:"eth1_data"`
+	Graffiti               string                        `json:"graffiti"`
+	ProposerSlashings      []*ProposerSlashing           `json:"proposer_slashings"`
+	AttesterSlashings      []*AttesterSlashingElectra    `json:"attester_slashings"`
+	Attestations           []*AttestationElectra         `json:"attestations"`
+	Deposits               []*Deposit                    `json:"deposits"`
+	VoluntaryExits         []*SignedVoluntaryExit        `json:"voluntary_exits"`
+	SyncAggregate          *SyncAggregate                `json:"sync_aggregate"`
+	ExecutionPayloadHeader *ExecutionPayloadHeaderDeneb  `json:"execution_payload_header"`
+	BLSToExecutionChanges  []*SignedBLSToExecutionChange `json:"bls_to_execution_changes"`
+	BlobKzgCommitments     []string                      `json:"blob_kzg_commitments"`
+	ExecutionRequests      *ExecutionRequests            `json:"execution_requests"`
 }

-type SignedBeaconBlockHeaderContainer struct {
-	Header    *SignedBeaconBlockHeader `json:"header"`
-	Root      string                   `json:"root"`
-	Canonical bool                     `json:"canonical"`
+type (
+	ExecutionRequests struct {
+		Deposits       []*DepositRequest       `json:"deposits"`
+		Withdrawals    []*WithdrawalRequest    `json:"withdrawals"`
+		Consolidations []*ConsolidationRequest `json:"consolidations"`
+	}
+)
+
+// ----------------------------------------------------------------------------
+// Fulu
+// ----------------------------------------------------------------------------
+
+type SignedBeaconBlockContentsFulu struct {
+	SignedBlock *SignedBeaconBlockFulu `json:"signed_block"`
+	KzgProofs   []string               `json:"kzg_proofs"`
+	Blobs       []string               `json:"blobs"`
 }

-type SignedBeaconBlockHeader struct {
-	Message   *BeaconBlockHeader `json:"message"`
-	Signature string             `json:"signature"`
+type BeaconBlockContentsFulu struct {
+	Block     *BeaconBlockFulu `json:"block"`
+	KzgProofs []string         `json:"kzg_proofs"`
+	Blobs     []string         `json:"blobs"`
 }

-type BeaconBlockHeader struct {
-	Slot          string `json:"slot"`
-	ProposerIndex string `json:"proposer_index"`
-	ParentRoot    string `json:"parent_root"`
-	StateRoot     string `json:"state_root"`
-	BodyRoot      string `json:"body_root"`
+type SignedBeaconBlockFulu struct {
+	Message   *BeaconBlockFulu `json:"message"`
+	Signature string           `json:"signature"`
 }

-type ExecutionPayload struct {
-	ParentHash    string   `json:"parent_hash"`
-	FeeRecipient  string   `json:"fee_recipient"`
-	StateRoot     string   `json:"state_root"`
-	ReceiptsRoot  string   `json:"receipts_root"`
-	LogsBloom     string   `json:"logs_bloom"`
-	PrevRandao    string   `json:"prev_randao"`
-	BlockNumber   string   `json:"block_number"`
-	GasLimit      string   `json:"gas_limit"`
-	GasUsed       string   `json:"gas_used"`
-	Timestamp     string   `json:"timestamp"`
-	ExtraData     string   `json:"extra_data"`
-	BaseFeePerGas string   `json:"base_fee_per_gas"`
-	BlockHash     string   `json:"block_hash"`
-	Transactions  []string `json:"transactions"`
+var _ SignedMessageJsoner = &SignedBeaconBlockFulu{}
+
+func (s *SignedBeaconBlockFulu) MessageRawJson() ([]byte, error) {
+	return json.Marshal(s.Message)
 }

-type ExecutionPayloadHeader struct {
-	ParentHash       string `json:"parent_hash"`
-	FeeRecipient     string `json:"fee_recipient"`
-	StateRoot        string `json:"state_root"`
-	ReceiptsRoot     string `json:"receipts_root"`
-	LogsBloom        string `json:"logs_bloom"`
-	PrevRandao       string `json:"prev_randao"`
-	BlockNumber      string `json:"block_number"`
-	GasLimit         string `json:"gas_limit"`
-	GasUsed          string `json:"gas_used"`
-	Timestamp        string `json:"timestamp"`
-	ExtraData        string `json:"extra_data"`
-	BaseFeePerGas    string `json:"base_fee_per_gas"`
-	BlockHash        string `json:"block_hash"`
-	TransactionsRoot string `json:"transactions_root"`
+func (s *SignedBeaconBlockFulu) SigString() string {
+	return s.Signature
 }

-type ExecutionPayloadCapella struct {
-	ParentHash    string        `json:"parent_hash"`
-	FeeRecipient  string        `json:"fee_recipient"`
-	StateRoot     string        `json:"state_root"`
-	ReceiptsRoot  string        `json:"receipts_root"`
-	LogsBloom     string        `json:"logs_bloom"`
-	PrevRandao    string        `json:"prev_randao"`
-	BlockNumber   string        `json:"block_number"`
-	GasLimit      string        `json:"gas_limit"`
-	GasUsed       string        `json:"gas_used"`
-	Timestamp     string        `json:"timestamp"`
-	ExtraData     string        `json:"extra_data"`
-	BaseFeePerGas string        `json:"base_fee_per_gas"`
-	BlockHash     string        `json:"block_hash"`
-	Transactions  []string      `json:"transactions"`
-	Withdrawals   []*Withdrawal `json:"withdrawals"`
+type BeaconBlockFulu struct {
+	Slot          string               `json:"slot"`
+	ProposerIndex string               `json:"proposer_index"`
+	ParentRoot    string               `json:"parent_root"`
+	StateRoot     string               `json:"state_root"`
+	Body          *BeaconBlockBodyFulu `json:"body"`
 }

-type ExecutionPayloadHeaderCapella struct {
-	ParentHash       string `json:"parent_hash"`
-	FeeRecipient     string `json:"fee_recipient"`
-	StateRoot        string `json:"state_root"`
-	ReceiptsRoot     string `json:"receipts_root"`
-	LogsBloom        string `json:"logs_bloom"`
-	PrevRandao       string `json:"prev_randao"`
-	BlockNumber      string `json:"block_number"`
-	GasLimit         string `json:"gas_limit"`
-	GasUsed          string `json:"gas_used"`
-	Timestamp        string `json:"timestamp"`
-	ExtraData        string `json:"extra_data"`
-	BaseFeePerGas    string `json:"base_fee_per_gas"`
-	BlockHash        string `json:"block_hash"`
-	TransactionsRoot string `json:"transactions_root"`
-	WithdrawalsRoot  string `json:"withdrawals_root"`
+type BeaconBlockBodyFulu struct {
+	RandaoReveal          string                        `json:"randao_reveal"`
+	Eth1Data              *Eth1Data                     `json:"eth1_data"`
+	Graffiti              string                        `json:"graffiti"`
+	ProposerSlashings     []*ProposerSlashing           `json:"proposer_slashings"`
+	AttesterSlashings     []*AttesterSlashingElectra    `json:"attester_slashings"`
+	Attestations          []*AttestationElectra         `json:"attestations"`
+	Deposits              []*Deposit                    `json:"deposits"`
+	VoluntaryExits        []*SignedVoluntaryExit        `json:"voluntary_exits"`
+	SyncAggregate         *SyncAggregate                `json:"sync_aggregate"`
+	ExecutionPayload      *ExecutionPayloadDeneb        `json:"execution_payload"`
+	BLSToExecutionChanges []*SignedBLSToExecutionChange `json:"bls_to_execution_changes"`
+	BlobKzgCommitments    []string                      `json:"blob_kzg_commitments"`
+	ExecutionRequests     *ExecutionRequests            `json:"execution_requests"`
 }

-type ExecutionPayloadDeneb struct {
-	ParentHash    string        `json:"parent_hash"`
-	FeeRecipient  string        `json:"fee_recipient"`
-	StateRoot     string        `json:"state_root"`
-	ReceiptsRoot  string        `json:"receipts_root"`
-	LogsBloom     string        `json:"logs_bloom"`
-	PrevRandao    string        `json:"prev_randao"`
-	BlockNumber   string        `json:"block_number"`
-	GasLimit      string        `json:"gas_limit"`
-	GasUsed       string        `json:"gas_used"`
-	Timestamp     string        `json:"timestamp"`
-	ExtraData     string        `json:"extra_data"`
-	BaseFeePerGas string        `json:"base_fee_per_gas"`
-	BlockHash     string        `json:"block_hash"`
-	Transactions  []string      `json:"transactions"`
-	Withdrawals   []*Withdrawal `json:"withdrawals"`
-	BlobGasUsed   string        `json:"blob_gas_used"`
-	ExcessBlobGas string        `json:"excess_blob_gas"`
+type BlindedBeaconBlockFulu struct {
+	Slot          string                      `json:"slot"`
+	ProposerIndex string                      `json:"proposer_index"`
+	ParentRoot    string                      `json:"parent_root"`
+	StateRoot     string                      `json:"state_root"`
+	Body          *BlindedBeaconBlockBodyFulu `json:"body"`
 }

-type ExecutionPayloadElectra = ExecutionPayloadDeneb
-
-type ExecutionPayloadHeaderDeneb struct {
-	ParentHash       string `json:"parent_hash"`
-	FeeRecipient     string `json:"fee_recipient"`
-	StateRoot        string `json:"state_root"`
-	ReceiptsRoot     string `json:"receipts_root"`
-	LogsBloom        string `json:"logs_bloom"`
-	PrevRandao       string `json:"prev_randao"`
-	BlockNumber      string `json:"block_number"`
-	GasLimit         string `json:"gas_limit"`
-	GasUsed          string `json:"gas_used"`
-	Timestamp        string `json:"timestamp"`
-	ExtraData        string `json:"extra_data"`
-	BaseFeePerGas    string `json:"base_fee_per_gas"`
-	BlockHash        string `json:"block_hash"`
-	TransactionsRoot string `json:"transactions_root"`
-	WithdrawalsRoot  string `json:"withdrawals_root"`
-	BlobGasUsed      string `json:"blob_gas_used"`
-	ExcessBlobGas    string `json:"excess_blob_gas"`
+type SignedBlindedBeaconBlockFulu struct {
+	Message   *BlindedBeaconBlockFulu `json:"message"`
+	Signature string                  `json:"signature"`
 }

-type ExecutionPayloadHeaderElectra = ExecutionPayloadHeaderDeneb
+var _ SignedMessageJsoner = &SignedBlindedBeaconBlockFulu{}

-type ExecutionRequests struct {
-	Deposits       []*DepositRequest       `json:"deposits"`
-	Withdrawals    []*WithdrawalRequest    `json:"withdrawals"`
-	Consolidations []*ConsolidationRequest `json:"consolidations"`
+func (s *SignedBlindedBeaconBlockFulu) MessageRawJson() ([]byte, error) {
+	return json.Marshal(s.Message)
+}
+
+func (s *SignedBlindedBeaconBlockFulu) SigString() string {
+	return s.Signature
+}
+
+type BlindedBeaconBlockBodyFulu struct {
+	RandaoReveal           string                        `json:"randao_reveal"`
+	Eth1Data               *Eth1Data                     `json:"eth1_data"`
+	Graffiti               string                        `json:"graffiti"`
+	ProposerSlashings      []*ProposerSlashing           `json:"proposer_slashings"`
+	AttesterSlashings      []*AttesterSlashingElectra    `json:"attester_slashings"`
+	Attestations           []*AttestationElectra         `json:"attestations"`
+	Deposits               []*Deposit                    `json:"deposits"`
+	VoluntaryExits         []*SignedVoluntaryExit        `json:"voluntary_exits"`
+	SyncAggregate          *SyncAggregate                `json:"sync_aggregate"`
+	ExecutionPayloadHeader *ExecutionPayloadHeaderDeneb  `json:"execution_payload_header"`
+	BLSToExecutionChanges  []*SignedBLSToExecutionChange `json:"bls_to_execution_changes"`
+	BlobKzgCommitments     []string                      `json:"blob_kzg_commitments"`
+	ExecutionRequests      *ExecutionRequests            `json:"execution_requests"`
 }
--- a/api/server/structs/conversions.go
+++ b/api/server/structs/conversions.go
@@ -432,6 +432,32 @@ func (a *AttestationElectra) ToConsensus() (*eth.AttestationElectra, error) {
 	}, nil
 }

+func (a *SingleAttestation) ToConsensus() (*eth.SingleAttestation, error) {
+	ci, err := strconv.ParseUint(a.CommitteeIndex, 10, 64)
+	if err != nil {
+		return nil, server.NewDecodeError(err, "CommitteeIndex")
+	}
+	ai, err := strconv.ParseUint(a.AttesterIndex, 10, 64)
+	if err != nil {
+		return nil, server.NewDecodeError(err, "AttesterIndex")
+	}
+	data, err := a.Data.ToConsensus()
+	if err != nil {
+		return nil, server.NewDecodeError(err, "Data")
+	}
+	sig, err := bytesutil.DecodeHexWithLength(a.Signature, fieldparams.BLSSignatureLength)
+	if err != nil {
+		return nil, server.NewDecodeError(err, "Signature")
+	}
+
+	return &eth.SingleAttestation{
+		CommitteeId:   primitives.CommitteeIndex(ci),
+		AttesterIndex: primitives.ValidatorIndex(ai),
+		Data:          data,
+		Signature:     sig,
+	}, nil
+}
+
 func AttElectraFromConsensus(a *eth.AttestationElectra) *AttestationElectra {
 	return &AttestationElectra{
 		AggregationBits: hexutil.Encode(a.AggregationBits),
--- a/api/server/structs/conversions_block.go
+++ b/api/server/structs/conversions_block.go
--- a/api/server/structs/conversions_lightclient.go
+++ b/api/server/structs/conversions_lightclient.go
@@ -176,9 +176,9 @@ func lightClientHeaderToJSON(header interfaces.LightClientHeader) (json.RawMessa
 		if err != nil {
 			return nil, err
 		}
-		ex, ok := exInterface.Proto().(*enginev1.ExecutionPayloadHeaderElectra)
+		ex, ok := exInterface.Proto().(*enginev1.ExecutionPayloadHeaderDeneb)
 		if !ok {
-			return nil, fmt.Errorf("execution data is not %T", &enginev1.ExecutionPayloadHeaderElectra{})
+			return nil, fmt.Errorf("execution data is not %T", &enginev1.ExecutionPayloadHeaderDeneb{})
 		}
 		execution, err := ExecutionPayloadHeaderElectraFromConsensus(ex)
 		if err != nil {
--- a/api/server/structs/conversions_state.go
+++ b/api/server/structs/conversions_state.go
@@ -11,6 +11,10 @@ import (

 var errPayloadHeaderNotFound = errors.New("expected payload header not found")

+// ----------------------------------------------------------------------------
+// Phase 0
+// ----------------------------------------------------------------------------
+
 func BeaconStateFromConsensus(st beaconState.BeaconState) (*BeaconState, error) {
 	srcBr := st.BlockRoots()
 	br := make([]string, len(srcBr))
@@ -97,6 +101,10 @@ func BeaconStateFromConsensus(st beaconState.BeaconState) (*BeaconState, error)
 	}, nil
 }

+// ----------------------------------------------------------------------------
+// Altair
+// ----------------------------------------------------------------------------
+
 func BeaconStateAltairFromConsensus(st beaconState.BeaconState) (*BeaconStateAltair, error) {
 	srcBr := st.BlockRoots()
 	br := make([]string, len(srcBr))
@@ -202,6 +210,10 @@ func BeaconStateAltairFromConsensus(st beaconState.BeaconState) (*BeaconStateAlt
 	}, nil
 }

+// ----------------------------------------------------------------------------
+// Bellatrix
+// ----------------------------------------------------------------------------
+
 func BeaconStateBellatrixFromConsensus(st beaconState.BeaconState) (*BeaconStateBellatrix, error) {
 	srcBr := st.BlockRoots()
 	br := make([]string, len(srcBr))
@@ -320,6 +332,10 @@ func BeaconStateBellatrixFromConsensus(st beaconState.BeaconState) (*BeaconState
 	}, nil
 }

+// ----------------------------------------------------------------------------
+// Capella
+// ----------------------------------------------------------------------------
+
 func BeaconStateCapellaFromConsensus(st beaconState.BeaconState) (*BeaconStateCapella, error) {
 	srcBr := st.BlockRoots()
 	br := make([]string, len(srcBr))
@@ -457,6 +473,10 @@ func BeaconStateCapellaFromConsensus(st beaconState.BeaconState) (*BeaconStateCa
 	}, nil
 }

+// ----------------------------------------------------------------------------
+// Deneb
+// ----------------------------------------------------------------------------
+
 func BeaconStateDenebFromConsensus(st beaconState.BeaconState) (*BeaconStateDeneb, error) {
 	srcBr := st.BlockRoots()
 	br := make([]string, len(srcBr))
@@ -594,6 +614,10 @@ func BeaconStateDenebFromConsensus(st beaconState.BeaconState) (*BeaconStateDene
 	}, nil
 }

+// ----------------------------------------------------------------------------
+// Electra
+// ----------------------------------------------------------------------------
+
 func BeaconStateElectraFromConsensus(st beaconState.BeaconState) (*BeaconStateElectra, error) {
 	srcBr := st.BlockRoots()
 	br := make([]string, len(srcBr))
@@ -775,3 +799,189 @@ func BeaconStateElectraFromConsensus(st beaconState.BeaconState) (*BeaconStateEl
 		PendingConsolidations:         PendingConsolidationsFromConsensus(pc),
 	}, nil
 }
+
+// ----------------------------------------------------------------------------
+// Fulu
+// ----------------------------------------------------------------------------
+
+func BeaconStateFuluFromConsensus(st beaconState.BeaconState) (*BeaconStateFulu, error) {
+	srcBr := st.BlockRoots()
+	br := make([]string, len(srcBr))
+	for i, r := range srcBr {
+		br[i] = hexutil.Encode(r)
+	}
+	srcSr := st.StateRoots()
+	sr := make([]string, len(srcSr))
+	for i, r := range srcSr {
+		sr[i] = hexutil.Encode(r)
+	}
+	srcHr, err := st.HistoricalRoots()
+	if err != nil {
+		return nil, err
+	}
+	hr := make([]string, len(srcHr))
+	for i, r := range srcHr {
+		hr[i] = hexutil.Encode(r)
+	}
+	srcVotes := st.Eth1DataVotes()
+	votes := make([]*Eth1Data, len(srcVotes))
+	for i, e := range srcVotes {
+		votes[i] = Eth1DataFromConsensus(e)
+	}
+	srcVals := st.Validators()
+	vals := make([]*Validator, len(srcVals))
+	for i, v := range srcVals {
+		vals[i] = ValidatorFromConsensus(v)
+	}
+	srcBals := st.Balances()
+	bals := make([]string, len(srcBals))
+	for i, b := range srcBals {
+		bals[i] = fmt.Sprintf("%d", b)
+	}
+	srcRm := st.RandaoMixes()
+	rm := make([]string, len(srcRm))
+	for i, m := range srcRm {
+		rm[i] = hexutil.Encode(m)
+	}
+	srcSlashings := st.Slashings()
+	slashings := make([]string, len(srcSlashings))
+	for i, s := range srcSlashings {
+		slashings[i] = fmt.Sprintf("%d", s)
+	}
+	srcPrevPart, err := st.PreviousEpochParticipation()
+	if err != nil {
+		return nil, err
+	}
+	prevPart := make([]string, len(srcPrevPart))
+	for i, p := range srcPrevPart {
+		prevPart[i] = fmt.Sprintf("%d", p)
+	}
+	srcCurrPart, err := st.CurrentEpochParticipation()
+	if err != nil {
+		return nil, err
+	}
+	currPart := make([]string, len(srcCurrPart))
+	for i, p := range srcCurrPart {
+		currPart[i] = fmt.Sprintf("%d", p)
+	}
+	srcIs, err := st.InactivityScores()
+	if err != nil {
+		return nil, err
+	}
+	is := make([]string, len(srcIs))
+	for i, s := range srcIs {
+		is[i] = fmt.Sprintf("%d", s)
+	}
+	currSc, err := st.CurrentSyncCommittee()
+	if err != nil {
+		return nil, err
+	}
+	nextSc, err := st.NextSyncCommittee()
+	if err != nil {
+		return nil, err
+	}
+	execData, err := st.LatestExecutionPayloadHeader()
+	if err != nil {
+		return nil, err
+	}
+	srcPayload, ok := execData.Proto().(*enginev1.ExecutionPayloadHeaderDeneb)
+	if !ok {
+		return nil, errPayloadHeaderNotFound
+	}
+	payload, err := ExecutionPayloadHeaderElectraFromConsensus(srcPayload)
+	if err != nil {
+		return nil, err
+	}
+	srcHs, err := st.HistoricalSummaries()
+	if err != nil {
+		return nil, err
+	}
+	hs := make([]*HistoricalSummary, len(srcHs))
+	for i, s := range srcHs {
+		hs[i] = HistoricalSummaryFromConsensus(s)
+	}
+	nwi, err := st.NextWithdrawalIndex()
+	if err != nil {
+		return nil, err
+	}
+	nwvi, err := st.NextWithdrawalValidatorIndex()
+	if err != nil {
+		return nil, err
+	}
+	drsi, err := st.DepositRequestsStartIndex()
+	if err != nil {
+		return nil, err
+	}
+	dbtc, err := st.DepositBalanceToConsume()
+	if err != nil {
+		return nil, err
+	}
+	ebtc, err := st.ExitBalanceToConsume()
+	if err != nil {
+		return nil, err
+	}
+	eee, err := st.EarliestExitEpoch()
+	if err != nil {
+		return nil, err
+	}
+	cbtc, err := st.ConsolidationBalanceToConsume()
+	if err != nil {
+		return nil, err
+	}
+	ece, err := st.EarliestConsolidationEpoch()
+	if err != nil {
+		return nil, err
+	}
+	pbd, err := st.PendingDeposits()
+	if err != nil {
+		return nil, err
+	}
+	ppw, err := st.PendingPartialWithdrawals()
+	if err != nil {
+		return nil, err
+	}
+	pc, err := st.PendingConsolidations()
+	if err != nil {
+		return nil, err
+	}
+
+	return &BeaconStateFulu{
+		GenesisTime:                   fmt.Sprintf("%d", st.GenesisTime()),
+		GenesisValidatorsRoot:         hexutil.Encode(st.GenesisValidatorsRoot()),
+		Slot:                          fmt.Sprintf("%d", st.Slot()),
+		Fork:                          ForkFromConsensus(st.Fork()),
+		LatestBlockHeader:             BeaconBlockHeaderFromConsensus(st.LatestBlockHeader()),
+		BlockRoots:                    br,
+		StateRoots:                    sr,
+		HistoricalRoots:               hr,
+		Eth1Data:                      Eth1DataFromConsensus(st.Eth1Data()),
+		Eth1DataVotes:                 votes,
+		Eth1DepositIndex:              fmt.Sprintf("%d", st.Eth1DepositIndex()),
+		Validators:                    vals,
+		Balances:                      bals,
+		RandaoMixes:                   rm,
+		Slashings:                     slashings,
+		PreviousEpochParticipation:    prevPart,
+		CurrentEpochParticipation:     currPart,
+		JustificationBits:             hexutil.Encode(st.JustificationBits()),
+		PreviousJustifiedCheckpoint:   CheckpointFromConsensus(st.PreviousJustifiedCheckpoint()),
+		CurrentJustifiedCheckpoint:    CheckpointFromConsensus(st.CurrentJustifiedCheckpoint()),
+		FinalizedCheckpoint:           CheckpointFromConsensus(st.FinalizedCheckpoint()),
+		InactivityScores:              is,
+		CurrentSyncCommittee:          SyncCommitteeFromConsensus(currSc),
+		NextSyncCommittee:             SyncCommitteeFromConsensus(nextSc),
+		LatestExecutionPayloadHeader:  payload,
+		NextWithdrawalIndex:           fmt.Sprintf("%d", nwi),
+		NextWithdrawalValidatorIndex:  fmt.Sprintf("%d", nwvi),
+		HistoricalSummaries:           hs,
+		DepositRequestsStartIndex:     fmt.Sprintf("%d", drsi),
+		DepositBalanceToConsume:       fmt.Sprintf("%d", dbtc),
+		ExitBalanceToConsume:          fmt.Sprintf("%d", ebtc),
+		EarliestExitEpoch:             fmt.Sprintf("%d", eee),
+		ConsolidationBalanceToConsume: fmt.Sprintf("%d", cbtc),
+		EarliestConsolidationEpoch:    fmt.Sprintf("%d", ece),
+		PendingDeposits:               PendingDepositsFromConsensus(pbd),
+		PendingPartialWithdrawals:     PendingPartialWithdrawalsFromConsensus(ppw),
+		PendingConsolidations:         PendingConsolidationsFromConsensus(pc),
+	}, nil
+}
--- a/api/server/structs/other.go
+++ b/api/server/structs/other.go
@@ -36,6 +36,13 @@ type AttestationElectra struct {
 	CommitteeBits   string           `json:"committee_bits"`
 }

+type SingleAttestation struct {
+	CommitteeIndex string           `json:"committee_index"`
+	AttesterIndex  string           `json:"attester_index"`
+	Data           *AttestationData `json:"data"`
+	Signature      string           `json:"signature"`
+}
+
 type AttestationData struct {
 	Slot            string      `json:"slot"`
 	CommitteeIndex  string      `json:"index"`
--- a/api/server/structs/state.go
+++ b/api/server/structs/state.go
@@ -142,41 +142,81 @@ type BeaconStateDeneb struct {
 }

 type BeaconStateElectra struct {
-	GenesisTime                   string                         `json:"genesis_time"`
-	GenesisValidatorsRoot         string                         `json:"genesis_validators_root"`
-	Slot                          string                         `json:"slot"`
-	Fork                          *Fork                          `json:"fork"`
-	LatestBlockHeader             *BeaconBlockHeader             `json:"latest_block_header"`
-	BlockRoots                    []string                       `json:"block_roots"`
-	StateRoots                    []string                       `json:"state_roots"`
-	HistoricalRoots               []string                       `json:"historical_roots"`
-	Eth1Data                      *Eth1Data                      `json:"eth1_data"`
-	Eth1DataVotes                 []*Eth1Data                    `json:"eth1_data_votes"`
-	Eth1DepositIndex              string                         `json:"eth1_deposit_index"`
-	Validators                    []*Validator                   `json:"validators"`
-	Balances                      []string                       `json:"balances"`
-	RandaoMixes                   []string                       `json:"randao_mixes"`
-	Slashings                     []string                       `json:"slashings"`
-	PreviousEpochParticipation    []string                       `json:"previous_epoch_participation"`
-	CurrentEpochParticipation     []string                       `json:"current_epoch_participation"`
-	JustificationBits             string                         `json:"justification_bits"`
-	PreviousJustifiedCheckpoint   *Checkpoint                    `json:"previous_justified_checkpoint"`
-	CurrentJustifiedCheckpoint    *Checkpoint                    `json:"current_justified_checkpoint"`
-	FinalizedCheckpoint           *Checkpoint                    `json:"finalized_checkpoint"`
-	InactivityScores              []string                       `json:"inactivity_scores"`
-	CurrentSyncCommittee          *SyncCommittee                 `json:"current_sync_committee"`
-	NextSyncCommittee             *SyncCommittee                 `json:"next_sync_committee"`
-	LatestExecutionPayloadHeader  *ExecutionPayloadHeaderElectra `json:"latest_execution_payload_header"`
-	NextWithdrawalIndex           string                         `json:"next_withdrawal_index"`
-	NextWithdrawalValidatorIndex  string                         `json:"next_withdrawal_validator_index"`
-	HistoricalSummaries           []*HistoricalSummary           `json:"historical_summaries"`
-	DepositRequestsStartIndex     string                         `json:"deposit_requests_start_index"`
-	DepositBalanceToConsume       string                         `json:"deposit_balance_to_consume"`
-	ExitBalanceToConsume          string                         `json:"exit_balance_to_consume"`
-	EarliestExitEpoch             string                         `json:"earliest_exit_epoch"`
-	ConsolidationBalanceToConsume string                         `json:"consolidation_balance_to_consume"`
-	EarliestConsolidationEpoch    string                         `json:"earliest_consolidation_epoch"`
-	PendingDeposits               []*PendingDeposit              `json:"pending_deposits"`
-	PendingPartialWithdrawals     []*PendingPartialWithdrawal    `json:"pending_partial_withdrawals"`
-	PendingConsolidations         []*PendingConsolidation        `json:"pending_consolidations"`
+	GenesisTime                   string                       `json:"genesis_time"`
+	GenesisValidatorsRoot         string                       `json:"genesis_validators_root"`
+	Slot                          string                       `json:"slot"`
+	Fork                          *Fork                        `json:"fork"`
+	LatestBlockHeader             *BeaconBlockHeader           `json:"latest_block_header"`
+	BlockRoots                    []string                     `json:"block_roots"`
+	StateRoots                    []string                     `json:"state_roots"`
+	HistoricalRoots               []string                     `json:"historical_roots"`
+	Eth1Data                      *Eth1Data                    `json:"eth1_data"`
+	Eth1DataVotes                 []*Eth1Data                  `json:"eth1_data_votes"`
+	Eth1DepositIndex              string                       `json:"eth1_deposit_index"`
+	Validators                    []*Validator                 `json:"validators"`
+	Balances                      []string                     `json:"balances"`
+	RandaoMixes                   []string                     `json:"randao_mixes"`
+	Slashings                     []string                     `json:"slashings"`
+	PreviousEpochParticipation    []string                     `json:"previous_epoch_participation"`
+	CurrentEpochParticipation     []string                     `json:"current_epoch_participation"`
+	JustificationBits             string                       `json:"justification_bits"`
+	PreviousJustifiedCheckpoint   *Checkpoint                  `json:"previous_justified_checkpoint"`
+	CurrentJustifiedCheckpoint    *Checkpoint                  `json:"current_justified_checkpoint"`
+	FinalizedCheckpoint           *Checkpoint                  `json:"finalized_checkpoint"`
+	InactivityScores              []string                     `json:"inactivity_scores"`
+	CurrentSyncCommittee          *SyncCommittee               `json:"current_sync_committee"`
+	NextSyncCommittee             *SyncCommittee               `json:"next_sync_committee"`
+	LatestExecutionPayloadHeader  *ExecutionPayloadHeaderDeneb `json:"latest_execution_payload_header"`
+	NextWithdrawalIndex           string                       `json:"next_withdrawal_index"`
+	NextWithdrawalValidatorIndex  string                       `json:"next_withdrawal_validator_index"`
+	HistoricalSummaries           []*HistoricalSummary         `json:"historical_summaries"`
+	DepositRequestsStartIndex     string                       `json:"deposit_requests_start_index"`
+	DepositBalanceToConsume       string                       `json:"deposit_balance_to_consume"`
+	ExitBalanceToConsume          string                       `json:"exit_balance_to_consume"`
+	EarliestExitEpoch             string                       `json:"earliest_exit_epoch"`
+	ConsolidationBalanceToConsume string                       `json:"consolidation_balance_to_consume"`
+	EarliestConsolidationEpoch    string                       `json:"earliest_consolidation_epoch"`
+	PendingDeposits               []*PendingDeposit            `json:"pending_deposits"`
+	PendingPartialWithdrawals     []*PendingPartialWithdrawal  `json:"pending_partial_withdrawals"`
+	PendingConsolidations         []*PendingConsolidation      `json:"pending_consolidations"`
+}
+
+type BeaconStateFulu struct {
+	GenesisTime                   string                       `json:"genesis_time"`
+	GenesisValidatorsRoot         string                       `json:"genesis_validators_root"`
+	Slot                          string                       `json:"slot"`
+	Fork                          *Fork                        `json:"fork"`
+	LatestBlockHeader             *BeaconBlockHeader           `json:"latest_block_header"`
+	BlockRoots                    []string                     `json:"block_roots"`
+	StateRoots                    []string                     `json:"state_roots"`
+	HistoricalRoots               []string                     `json:"historical_roots"`
+	Eth1Data                      *Eth1Data                    `json:"eth1_data"`
+	Eth1DataVotes                 []*Eth1Data                  `json:"eth1_data_votes"`
+	Eth1DepositIndex              string                       `json:"eth1_deposit_index"`
+	Validators                    []*Validator                 `json:"validators"`
+	Balances                      []string                     `json:"balances"`
+	RandaoMixes                   []string                     `json:"randao_mixes"`
+	Slashings                     []string                     `json:"slashings"`
+	PreviousEpochParticipation    []string                     `json:"previous_epoch_participation"`
+	CurrentEpochParticipation     []string                     `json:"current_epoch_participation"`
+	JustificationBits             string                       `json:"justification_bits"`
+	PreviousJustifiedCheckpoint   *Checkpoint                  `json:"previous_justified_checkpoint"`
+	CurrentJustifiedCheckpoint    *Checkpoint                  `json:"current_justified_checkpoint"`
+	FinalizedCheckpoint           *Checkpoint                  `json:"finalized_checkpoint"`
+	InactivityScores              []string                     `json:"inactivity_scores"`
+	CurrentSyncCommittee          *SyncCommittee               `json:"current_sync_committee"`
+	NextSyncCommittee             *SyncCommittee               `json:"next_sync_committee"`
+	LatestExecutionPayloadHeader  *ExecutionPayloadHeaderDeneb `json:"latest_execution_payload_header"`
+	NextWithdrawalIndex           string                       `json:"next_withdrawal_index"`
+	NextWithdrawalValidatorIndex  string                       `json:"next_withdrawal_validator_index"`
+	HistoricalSummaries           []*HistoricalSummary         `json:"historical_summaries"`
+	DepositRequestsStartIndex     string                       `json:"deposit_requests_start_index"`
+	DepositBalanceToConsume       string                       `json:"deposit_balance_to_consume"`
+	ExitBalanceToConsume          string                       `json:"exit_balance_to_consume"`
+	EarliestExitEpoch             string                       `json:"earliest_exit_epoch"`
+	ConsolidationBalanceToConsume string                       `json:"consolidation_balance_to_consume"`
+	EarliestConsolidationEpoch    string                       `json:"earliest_consolidation_epoch"`
+	PendingDeposits               []*PendingDeposit            `json:"pending_deposits"`
+	PendingPartialWithdrawals     []*PendingPartialWithdrawal  `json:"pending_partial_withdrawals"`
+	PendingConsolidations         []*PendingConsolidation      `json:"pending_consolidations"`
 }
--- a/beacon-chain/blockchain/execution_engine.go
+++ b/beacon-chain/blockchain/execution_engine.go
@@ -362,15 +362,16 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,
 		return emptyAttri
 	}

-	var attr payloadattribute.Attributer
-	switch st.Version() {
-	case version.Deneb, version.Electra:
+	v := st.Version()
+
+	if v >= version.Deneb {
 		withdrawals, _, err := st.ExpectedWithdrawals()
 		if err != nil {
 			log.WithError(err).Error("Could not get expected withdrawals to get payload attribute")
 			return emptyAttri
 		}
-		attr, err = payloadattribute.New(&enginev1.PayloadAttributesV3{
+
+		attr, err := payloadattribute.New(&enginev1.PayloadAttributesV3{
 			Timestamp:             uint64(t.Unix()),
 			PrevRandao:            prevRando,
 			SuggestedFeeRecipient: val.FeeRecipient[:],
@@ -381,13 +382,18 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,
 			log.WithError(err).Error("Could not get payload attribute")
 			return emptyAttri
 		}
-	case version.Capella:
+
+		return attr
+	}
+
+	if v >= version.Capella {
 		withdrawals, _, err := st.ExpectedWithdrawals()
 		if err != nil {
 			log.WithError(err).Error("Could not get expected withdrawals to get payload attribute")
 			return emptyAttri
 		}
-		attr, err = payloadattribute.New(&enginev1.PayloadAttributesV2{
+
+		attr, err := payloadattribute.New(&enginev1.PayloadAttributesV2{
 			Timestamp:             uint64(t.Unix()),
 			PrevRandao:            prevRando,
 			SuggestedFeeRecipient: val.FeeRecipient[:],
@@ -397,8 +403,12 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,
 			log.WithError(err).Error("Could not get payload attribute")
 			return emptyAttri
 		}
-	case version.Bellatrix:
-		attr, err = payloadattribute.New(&enginev1.PayloadAttributes{
+
+		return attr
+	}
+
+	if v >= version.Bellatrix {
+		attr, err := payloadattribute.New(&enginev1.PayloadAttributes{
 			Timestamp:             uint64(t.Unix()),
 			PrevRandao:            prevRando,
 			SuggestedFeeRecipient: val.FeeRecipient[:],
@@ -407,12 +417,12 @@ func (s *Service) getPayloadAttribute(ctx context.Context, st state.BeaconState,
 			log.WithError(err).Error("Could not get payload attribute")
 			return emptyAttri
 		}
-	default:
-		log.WithField("version", st.Version()).Error("Could not get payload attribute due to unknown state version")
-		return emptyAttri
+
+		return attr
 	}

-	return attr
+	log.WithField("version", version.String(st.Version())).Error("Could not get payload attribute due to unknown state version")
+	return emptyAttri
 }

 // removeInvalidBlockAndState removes the invalid block, blob and its corresponding state from the cache and DB.
--- a/beacon-chain/blockchain/head.go
+++ b/beacon-chain/blockchain/head.go
@@ -11,6 +11,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/forkchoice"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v5/config/features"
 	fieldparams "github.com/prysmaticlabs/prysm/v5/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/blocks"
@@ -404,13 +405,19 @@ func (s *Service) saveOrphanedOperations(ctx context.Context, orphanedRoot [32]b
 			if a.GetData().Slot+params.BeaconConfig().SlotsPerEpoch < s.CurrentSlot() {
 				continue
 			}
-			if helpers.IsAggregated(a) {
-				if err := s.cfg.AttPool.SaveAggregatedAttestation(a); err != nil {
+			if features.Get().EnableExperimentalAttestationPool {
+				if err = s.cfg.AttestationCache.Add(a); err != nil {
 					return err
 				}
 			} else {
-				if err := s.cfg.AttPool.SaveUnaggregatedAttestation(a); err != nil {
-					return err
+				if a.IsAggregated() {
+					if err = s.cfg.AttPool.SaveAggregatedAttestation(a); err != nil {
+						return err
+					}
+				} else {
+					if err = s.cfg.AttPool.SaveUnaggregatedAttestation(a); err != nil {
+						return err
+					}
 				}
 			}
 			saveOrphanedAttCount.Inc()
--- a/beacon-chain/blockchain/kzg/validation.go
+++ b/beacon-chain/blockchain/kzg/validation.go
@@ -20,16 +20,17 @@ func Verify(sidecars ...blocks.ROBlob) error {
 	cmts := make([]GoKZG.KZGCommitment, len(sidecars))
 	proofs := make([]GoKZG.KZGProof, len(sidecars))
 	for i, sidecar := range sidecars {
-		blobs[i] = bytesToBlob(sidecar.Blob)
+		blobs[i] = *bytesToBlob(sidecar.Blob)
 		cmts[i] = bytesToCommitment(sidecar.KzgCommitment)
 		proofs[i] = bytesToKZGProof(sidecar.KzgProof)
 	}
 	return kzgContext.VerifyBlobKZGProofBatch(blobs, cmts, proofs)
 }

-func bytesToBlob(blob []byte) (ret GoKZG.Blob) {
+func bytesToBlob(blob []byte) *GoKZG.Blob {
+	var ret GoKZG.Blob
 	copy(ret[:], blob)
-	return
+	return &ret
 }

 func bytesToCommitment(commitment []byte) (ret GoKZG.KZGCommitment) {
--- a/beacon-chain/blockchain/kzg/validation_test.go
+++ b/beacon-chain/blockchain/kzg/validation_test.go
@@ -10,11 +10,11 @@ import (
 )

 func GenerateCommitmentAndProof(blob GoKZG.Blob) (GoKZG.KZGCommitment, GoKZG.KZGProof, error) {
-	commitment, err := kzgContext.BlobToKZGCommitment(blob, 0)
+	commitment, err := kzgContext.BlobToKZGCommitment(&blob, 0)
 	if err != nil {
 		return GoKZG.KZGCommitment{}, GoKZG.KZGProof{}, err
 	}
-	proof, err := kzgContext.ComputeBlobKZGProof(blob, commitment, 0)
+	proof, err := kzgContext.ComputeBlobKZGProof(&blob, commitment, 0)
 	if err != nil {
 		return GoKZG.KZGCommitment{}, GoKZG.KZGProof{}, err
 	}
@@ -31,7 +31,7 @@ func TestBytesToAny(t *testing.T) {
 	blob := GoKZG.Blob{0x01, 0x02}
 	commitment := GoKZG.KZGCommitment{0x01, 0x02}
 	proof := GoKZG.KZGProof{0x01, 0x02}
-	require.DeepEqual(t, blob, bytesToBlob(bytes))
+	require.DeepEqual(t, blob, *bytesToBlob(bytes))
 	require.DeepEqual(t, commitment, bytesToCommitment(bytes))
 	require.DeepEqual(t, proof, bytesToKZGProof(bytes))
 }
--- a/beacon-chain/blockchain/options.go
+++ b/beacon-chain/blockchain/options.go
@@ -85,6 +85,14 @@ func WithTrackedValidatorsCache(c *cache.TrackedValidatorsCache) Option {
 	}
 }

+// WithAttestationCache for attestation lifecycle after chain inclusion.
+func WithAttestationCache(c *cache.AttestationCache) Option {
+	return func(s *Service) error {
+		s.cfg.AttestationCache = c
+		return nil
+	}
+}
+
 // WithAttestationPool for attestation lifecycle after chain inclusion.
 func WithAttestationPool(p attestations.Pool) Option {
 	return func(s *Service) error {
--- a/beacon-chain/blockchain/process_block.go
+++ b/beacon-chain/blockchain/process_block.go
@@ -69,6 +69,7 @@ func (s *Service) postBlockProcess(cfg *postBlockProcessConfig) error {
 	if features.Get().EnableLightClient && slots.ToEpoch(s.CurrentSlot()) >= params.BeaconConfig().AltairForkEpoch {
 		defer s.processLightClientUpdates(cfg)
 		defer s.saveLightClientUpdate(cfg)
+		defer s.saveLightClientBootstrap(cfg)
 	}
 	defer s.sendStateFeedOnBlock(cfg)
 	defer reportProcessingTime(startTime)
@@ -378,7 +379,11 @@ func (s *Service) handleBlockAttestations(ctx context.Context, blk interfaces.Re
 		r := bytesutil.ToBytes32(a.GetData().BeaconBlockRoot)
 		if s.cfg.ForkChoiceStore.HasNode(r) {
 			s.cfg.ForkChoiceStore.ProcessAttestation(ctx, indices, r, a.GetData().Target.Epoch)
-		} else if err := s.cfg.AttPool.SaveBlockAttestation(a); err != nil {
+		} else if features.Get().EnableExperimentalAttestationPool {
+			if err = s.cfg.AttestationCache.Add(a); err != nil {
+				return err
+			}
+		} else if err = s.cfg.AttPool.SaveBlockAttestation(a); err != nil {
 			return err
 		}
 	}
@@ -418,7 +423,11 @@ func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b interface
 func (s *Service) pruneAttsFromPool(headBlock interfaces.ReadOnlySignedBeaconBlock) error {
 	atts := headBlock.Block().Body().Attestations()
 	for _, att := range atts {
-		if helpers.IsAggregated(att) {
+		if features.Get().EnableExperimentalAttestationPool {
+			if err := s.cfg.AttestationCache.DeleteCovered(att); err != nil {
+				return errors.Wrap(err, "could not delete attestation")
+			}
+		} else if att.IsAggregated() {
 			if err := s.cfg.AttPool.DeleteAggregatedAttestation(att); err != nil {
 				return err
 			}
--- a/beacon-chain/blockchain/process_block_helpers.go
+++ b/beacon-chain/blockchain/process_block_helpers.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"strings"
 	"time"

 	lightclient "github.com/prysmaticlabs/prysm/v5/beacon-chain/core/light-client"
@@ -129,7 +130,7 @@ func (s *Service) saveLightClientUpdate(cfg *postBlockProcessConfig) {
 	attestedRoot := cfg.roblock.Block().ParentRoot()
 	attestedBlock, err := s.getBlock(cfg.ctx, attestedRoot)
 	if err != nil {
-		log.WithError(err).Error("Saving light client update failed: Could not get attested block")
+		log.WithError(err).Errorf("Saving light client update failed: Could not get attested block for root %#x", attestedRoot)
 		return
 	}
 	if attestedBlock == nil || attestedBlock.IsNil() {
@@ -138,7 +139,7 @@ func (s *Service) saveLightClientUpdate(cfg *postBlockProcessConfig) {
 	}
 	attestedState, err := s.cfg.StateGen.StateByRoot(cfg.ctx, attestedRoot)
 	if err != nil {
-		log.WithError(err).Error("Saving light client update failed: Could not get attested state")
+		log.WithError(err).Errorf("Saving light client update failed: Could not get attested state for root %#x", attestedRoot)
 		return
 	}
 	if attestedState == nil || attestedState.IsNil() {
@@ -149,7 +150,11 @@ func (s *Service) saveLightClientUpdate(cfg *postBlockProcessConfig) {
 	finalizedRoot := attestedState.FinalizedCheckpoint().Root
 	finalizedBlock, err := s.getBlock(cfg.ctx, [32]byte(finalizedRoot))
 	if err != nil {
-		log.WithError(err).Error("Saving light client update failed: Could not get finalized block")
+		if errors.Is(err, errBlockNotFoundInCacheOrDB) {
+			log.Debugf("Skipping saving light client update: Finalized block is nil for root %#x", finalizedRoot)
+		} else {
+			log.WithError(err).Errorf("Saving light client update failed: Could not get finalized block for root %#x", finalizedRoot)
+		}
 		return
 	}

@@ -224,28 +229,30 @@ func (s *Service) processLightClientFinalityUpdate(
 	attestedRoot := signed.Block().ParentRoot()
 	attestedBlock, err := s.cfg.BeaconDB.Block(ctx, attestedRoot)
 	if err != nil {
-		return errors.Wrap(err, "could not get attested block")
+		return errors.Wrapf(err, "could not get attested block for root %#x", attestedRoot)
 	}
 	attestedState, err := s.cfg.StateGen.StateByRoot(ctx, attestedRoot)
 	if err != nil {
-		return errors.Wrap(err, "could not get attested state")
+		return errors.Wrapf(err, "could not get attested state for root %#x", attestedRoot)
 	}

-	var finalizedBlock interfaces.ReadOnlySignedBeaconBlock
-	finalizedCheckPoint := attestedState.FinalizedCheckpoint()
-	if finalizedCheckPoint != nil {
-		finalizedRoot := bytesutil.ToBytes32(finalizedCheckPoint.Root)
-		finalizedBlock, err = s.cfg.BeaconDB.Block(ctx, finalizedRoot)
-		if err != nil {
-			finalizedBlock = nil
-		}
-	}
+	finalizedCheckpoint := attestedState.FinalizedCheckpoint()

 	// Check if the finalized checkpoint has changed
-	if finalizedCheckPoint == nil || bytes.Equal(finalizedCheckPoint.GetRoot(), postState.FinalizedCheckpoint().Root) {
+	if finalizedCheckpoint == nil || bytes.Equal(finalizedCheckpoint.GetRoot(), postState.FinalizedCheckpoint().Root) {
 		return nil
 	}

+	finalizedRoot := bytesutil.ToBytes32(finalizedCheckpoint.Root)
+	finalizedBlock, err := s.cfg.BeaconDB.Block(ctx, finalizedRoot)
+	if err != nil {
+		if errors.Is(err, errBlockNotFoundInCacheOrDB) {
+			log.Debugf("Skipping processing light client finality update: Finalized block is nil for root %#x", finalizedRoot)
+			return nil
+		}
+		return errors.Wrapf(err, "could not get finalized block for root %#x", finalizedRoot)
+	}
+
 	update, err := lightclient.NewLightClientFinalityUpdateFromBeaconState(
 		ctx,
 		postState.Slot(),
@@ -272,11 +279,11 @@ func (s *Service) processLightClientOptimisticUpdate(ctx context.Context, signed
 	attestedRoot := signed.Block().ParentRoot()
 	attestedBlock, err := s.cfg.BeaconDB.Block(ctx, attestedRoot)
 	if err != nil {
-		return errors.Wrap(err, "could not get attested block")
+		return errors.Wrapf(err, "could not get attested block for root %#x", attestedRoot)
 	}
 	attestedState, err := s.cfg.StateGen.StateByRoot(ctx, attestedRoot)
 	if err != nil {
-		return errors.Wrap(err, "could not get attested state")
+		return errors.Wrapf(err, "could not get attested state for root %#x", attestedRoot)
 	}

 	update, err := lightclient.NewLightClientOptimisticUpdateFromBeaconState(
@@ -289,6 +296,10 @@ func (s *Service) processLightClientOptimisticUpdate(ctx context.Context, signed
 	)

 	if err != nil {
+		if strings.Contains(err.Error(), lightclient.ErrNotEnoughSyncCommitteeBits) {
+			log.WithError(err).Debug("Skipping processing light client optimistic update")
+			return nil
+		}
 		return errors.Wrap(err, "could not create light client optimistic update")
 	}

--- a/beacon-chain/blockchain/receive_attestation.go
+++ b/beacon-chain/blockchain/receive_attestation.go
@@ -9,6 +9,7 @@ import (
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/v5/config/features"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v5/encoding/bytesutil"
@@ -166,7 +167,13 @@ func (s *Service) UpdateHead(ctx context.Context, proposingSlot primitives.Slot)

 // This processes fork choice attestations from the pool to account for validator votes and fork choice.
 func (s *Service) processAttestations(ctx context.Context, disparity time.Duration) {
-	atts := s.cfg.AttPool.ForkchoiceAttestations()
+	var atts []ethpb.Att
+	if features.Get().EnableExperimentalAttestationPool {
+		atts = s.cfg.AttestationCache.ForkchoiceAttestations()
+	} else {
+		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.
@@ -182,7 +189,11 @@ func (s *Service) processAttestations(ctx context.Context, disparity time.Durati
 			continue
 		}

-		if err := s.cfg.AttPool.DeleteForkchoiceAttestation(a); err != nil {
+		if features.Get().EnableExperimentalAttestationPool {
+			if err := s.cfg.AttestationCache.DeleteForkchoiceAttestation(a); err != nil {
+				log.WithError(err).Error("Could not delete fork choice attestation in pool")
+			}
+		} else if err := s.cfg.AttPool.DeleteForkchoiceAttestation(a); err != nil {
 			log.WithError(err).Error("Could not delete fork choice attestation in pool")
 		}

--- a/beacon-chain/blockchain/service.go
+++ b/beacon-chain/blockchain/service.go
@@ -75,6 +75,7 @@ type config struct {
 	DepositCache            cache.DepositCache
 	PayloadIDCache          *cache.PayloadIDCache
 	TrackedValidatorsCache  *cache.TrackedValidatorsCache
+	AttestationCache        *cache.AttestationCache
 	AttPool                 attestations.Pool
 	ExitPool                voluntaryexits.PoolManager
 	SlashingPool            slashings.PoolManager
--- a/beacon-chain/cache/BUILD.bazel
+++ b/beacon-chain/cache/BUILD.bazel
@@ -5,6 +5,7 @@ go_library(
    srcs = [
        "active_balance.go",
        "active_balance_disabled.go",  # keep
+        "attestation.go",
        "attestation_data.go",
        "balance_cache_key.go",
        "checkpoint_state.go",
@@ -36,18 +37,21 @@ go_library(
    ],
    deps = [
        "//beacon-chain/forkchoice/types:go_default_library",
+        "//beacon-chain/operations/attestations/attmap:go_default_library",
        "//beacon-chain/state:go_default_library",
        "//cache/lru:go_default_library",
        "//config/fieldparams:go_default_library",
        "//config/params:go_default_library",
        "//consensus-types/primitives:go_default_library",
        "//container/slice:go_default_library",
+        "//crypto/bls:go_default_library",
        "//crypto/hash:go_default_library",
        "//crypto/rand:go_default_library",
        "//encoding/bytesutil:go_default_library",
        "//math:go_default_library",
        "//monitoring/tracing/trace:go_default_library",
        "//proto/prysm/v1alpha1:go_default_library",
+        "//proto/prysm/v1alpha1/attestation:go_default_library",
        "//runtime/version:go_default_library",
        "@com_github_ethereum_go_ethereum//common:go_default_library",
        "@com_github_hashicorp_golang_lru//:go_default_library",
@@ -66,6 +70,7 @@ go_test(
    srcs = [
        "active_balance_test.go",
        "attestation_data_test.go",
+        "attestation_test.go",
        "cache_test.go",
        "checkpoint_state_test.go",
        "committee_fuzz_test.go",
@@ -88,14 +93,17 @@ go_test(
        "//config/fieldparams:go_default_library",
        "//config/params:go_default_library",
        "//consensus-types/primitives:go_default_library",
+        "//crypto/bls/blst:go_default_library",
        "//encoding/bytesutil:go_default_library",
        "//proto/prysm/v1alpha1:go_default_library",
+        "//proto/prysm/v1alpha1/attestation:go_default_library",
        "//testing/assert:go_default_library",
        "//testing/require:go_default_library",
        "//testing/util:go_default_library",
        "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
        "@com_github_google_gofuzz//:go_default_library",
        "@com_github_hashicorp_golang_lru//:go_default_library",
+        "@com_github_prysmaticlabs_go_bitfield//:go_default_library",
        "@com_github_stretchr_testify//require:go_default_library",
        "@org_golang_google_protobuf//proto:go_default_library",
    ],
--- a/beacon-chain/cache/attestation.go
+++ b/beacon-chain/cache/attestation.go
@@ -0,0 +1,275 @@
+package cache
+
+import (
+	"sync"
+
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/operations/attestations/attmap"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v5/crypto/bls"
+	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1/attestation"
+	log "github.com/sirupsen/logrus"
+)
+
+type attGroup struct {
+	slot primitives.Slot
+	atts []ethpb.Att
+}
+
+// AttestationCache holds a map of attGroup items that group together all attestations for a single slot.
+// When we add an attestation to the cache by calling Add, we either create a new group with this attestation
+// (if this is the first attestation for some slot) or two things can happen:
+//
+//   - If the attestation is unaggregated, we add its attestation bit to attestation bits of the first
+//     attestation in the group.
+//   - If the attestation is aggregated, we append it to the group. There should be no redundancy
+//     in the list because we ignore redundant aggregates in gossip.
+//
+// The first bullet point above means that we keep one aggregate attestation to which we keep appending bits
+// as new single-bit attestations arrive. This means that at any point during seconds 0-4 of a slot
+// we will have only one attestation for this slot in the cache.
+//
+// NOTE: This design in principle can result in worse aggregates since we lose the ability to aggregate some
+// single bit attestations in case of overlaps with incoming aggregates.
+//
+// The cache also keeps forkchoice attestations in a separate struct. These attestations are used for
+// forkchoice-related operations.
+type AttestationCache struct {
+	atts map[attestation.Id]*attGroup
+	sync.RWMutex
+	forkchoiceAtts *attmap.Attestations
+}
+
+// NewAttestationCache creates a new cache instance.
+func NewAttestationCache() *AttestationCache {
+	return &AttestationCache{
+		atts:           make(map[attestation.Id]*attGroup),
+		forkchoiceAtts: attmap.New(),
+	}
+}
+
+// Add does one of two things:
+//
+//   - For unaggregated attestations, it adds the attestation bit to attestation bits of the running aggregate,
+//     which is the first aggregate for the slot.
+//   - For aggregated attestations, it appends the attestation to the existing list of attestations for the slot.
+func (c *AttestationCache) Add(att ethpb.Att) error {
+	if att.IsNil() {
+		log.Debug("Attempted to add a nil attestation to the attestation cache")
+		return nil
+	}
+	if len(att.GetAggregationBits().BitIndices()) == 0 {
+		log.Debug("Attempted to add an attestation with 0 bits set to the attestation cache")
+		return nil
+	}
+
+	c.Lock()
+	defer c.Unlock()
+
+	id, err := attestation.NewId(att, attestation.Data)
+	if err != nil {
+		return errors.Wrapf(err, "could not create attestation ID")
+	}
+
+	group := c.atts[id]
+	if group == nil {
+		group = &attGroup{
+			slot: att.GetData().Slot,
+			atts: []ethpb.Att{att},
+		}
+		c.atts[id] = group
+		return nil
+	}
+
+	if att.IsAggregated() {
+		group.atts = append(group.atts, att.Clone())
+		return nil
+	}
+
+	// This should never happen because we return early for a new group.
+	if len(group.atts) == 0 {
+		log.Error("Attestation group contains no attestations, skipping insertion")
+		return nil
+	}
+
+	a := group.atts[0]
+
+	// Indexing is safe because we have guarded against 0 bits set.
+	bit := att.GetAggregationBits().BitIndices()[0]
+	if a.GetAggregationBits().BitAt(uint64(bit)) {
+		return nil
+	}
+	sig, err := aggregateSig(a, att)
+	if err != nil {
+		return errors.Wrapf(err, "could not aggregate signatures")
+	}
+
+	a.GetAggregationBits().SetBitAt(uint64(bit), true)
+	a.SetSignature(sig)
+
+	return nil
+}
+
+// GetAll returns all attestations in the cache, excluding forkchoice attestations.
+func (c *AttestationCache) GetAll() []ethpb.Att {
+	c.RLock()
+	defer c.RUnlock()
+
+	var result []ethpb.Att
+	for _, group := range c.atts {
+		result = append(result, group.atts...)
+	}
+	return result
+}
+
+// Count returns the number of all attestations in the cache, excluding forkchoice attestations.
+func (c *AttestationCache) Count() int {
+	c.RLock()
+	defer c.RUnlock()
+
+	count := 0
+	for _, group := range c.atts {
+		count += len(group.atts)
+	}
+	return count
+}
+
+// DeleteCovered removes all attestations whose attestation bits are a proper subset of the passed-in attestation.
+func (c *AttestationCache) DeleteCovered(att ethpb.Att) error {
+	if att.IsNil() {
+		return nil
+	}
+
+	c.Lock()
+	defer c.Unlock()
+
+	id, err := attestation.NewId(att, attestation.Data)
+	if err != nil {
+		return errors.Wrapf(err, "could not create attestation ID")
+	}
+
+	group := c.atts[id]
+	if group == nil {
+		return nil
+	}
+
+	idx := 0
+	for _, a := range group.atts {
+		if covered, err := att.GetAggregationBits().Contains(a.GetAggregationBits()); err != nil {
+			return err
+		} else if !covered {
+			group.atts[idx] = a
+			idx++
+		}
+	}
+	group.atts = group.atts[:idx]
+
+	if len(group.atts) == 0 {
+		delete(c.atts, id)
+	}
+
+	return nil
+}
+
+// PruneBefore removes all attestations whose slot is earlier than the passed-in slot.
+func (c *AttestationCache) PruneBefore(slot primitives.Slot) uint64 {
+	c.Lock()
+	defer c.Unlock()
+
+	var pruneCount int
+	for id, group := range c.atts {
+		if group.slot < slot {
+			pruneCount += len(group.atts)
+			delete(c.atts, id)
+		}
+	}
+	return uint64(pruneCount)
+}
+
+// AggregateIsRedundant checks whether all attestation bits of the passed-in aggregate
+// are already included by any aggregate in the cache.
+func (c *AttestationCache) AggregateIsRedundant(att ethpb.Att) (bool, error) {
+	if att.IsNil() {
+		return true, nil
+	}
+
+	c.RLock()
+	defer c.RUnlock()
+
+	id, err := attestation.NewId(att, attestation.Data)
+	if err != nil {
+		return true, errors.Wrapf(err, "could not create attestation ID")
+	}
+
+	group := c.atts[id]
+	if group == nil {
+		return false, nil
+	}
+
+	for _, a := range group.atts {
+		if redundant, err := a.GetAggregationBits().Contains(att.GetAggregationBits()); err != nil {
+			return true, err
+		} else if redundant {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
+// SaveForkchoiceAttestations saves forkchoice attestations.
+func (c *AttestationCache) SaveForkchoiceAttestations(att []ethpb.Att) error {
+	return c.forkchoiceAtts.SaveMany(att)
+}
+
+// ForkchoiceAttestations returns all forkchoice attestations.
+func (c *AttestationCache) ForkchoiceAttestations() []ethpb.Att {
+	return c.forkchoiceAtts.GetAll()
+}
+
+// DeleteForkchoiceAttestation deletes a forkchoice attestation.
+func (c *AttestationCache) DeleteForkchoiceAttestation(att ethpb.Att) error {
+	return c.forkchoiceAtts.Delete(att)
+}
+
+// GetBySlotAndCommitteeIndex returns all attestations in the cache that match the provided slot
+// and committee index. Forkchoice attestations are not returned.
+//
+// NOTE: This function cannot be declared as a method on the AttestationCache because it is a generic function.
+func GetBySlotAndCommitteeIndex[T ethpb.Att](c *AttestationCache, slot primitives.Slot, committeeIndex primitives.CommitteeIndex) []T {
+	c.RLock()
+	defer c.RUnlock()
+
+	var result []T
+
+	for _, group := range c.atts {
+		if len(group.atts) > 0 {
+			// We can safely compare the first attestation because all attestations in a group
+			// must have the same slot and committee index, since they are under the same key.
+			a, ok := group.atts[0].(T)
+			if ok && a.GetData().Slot == slot && a.CommitteeBitsVal().BitAt(uint64(committeeIndex)) {
+				for _, a := range group.atts {
+					a, ok := a.(T)
+					if ok {
+						result = append(result, a)
+					}
+				}
+			}
+		}
+	}
+
+	return result
+}
+
+func aggregateSig(agg ethpb.Att, att ethpb.Att) ([]byte, error) {
+	aggSig, err := bls.SignatureFromBytesNoValidation(agg.GetSignature())
+	if err != nil {
+		return nil, err
+	}
+	attSig, err := bls.SignatureFromBytesNoValidation(att.GetSignature())
+	if err != nil {
+		return nil, err
+	}
+	return bls.AggregateSignatures([]bls.Signature{aggSig, attSig}).Marshal(), nil
+}
--- a/beacon-chain/cache/attestation_data.go
+++ b/beacon-chain/cache/attestation_data.go
@@ -15,24 +15,24 @@ type AttestationConsensusData struct {
 	Source   forkchoicetypes.Checkpoint
 }

-// AttestationCache stores cached results of AttestationData requests.
-type AttestationCache struct {
+// AttestationDataCache stores cached results of AttestationData requests.
+type AttestationDataCache struct {
 	a *AttestationConsensusData
 	sync.RWMutex
 }

-// NewAttestationCache creates a new instance of AttestationCache.
-func NewAttestationCache() *AttestationCache {
-	return &AttestationCache{}
+// NewAttestationDataCache creates a new instance of AttestationDataCache.
+func NewAttestationDataCache() *AttestationDataCache {
+	return &AttestationDataCache{}
 }

 // Get retrieves cached attestation data, recording a cache hit or miss. This method is lock free.
-func (c *AttestationCache) Get() *AttestationConsensusData {
+func (c *AttestationDataCache) Get() *AttestationConsensusData {
 	return c.a
 }

 // Put adds a response to the cache. This method is lock free.
-func (c *AttestationCache) Put(a *AttestationConsensusData) error {
+func (c *AttestationDataCache) Put(a *AttestationConsensusData) error {
 	if a == nil {
 		return errors.New("attestation cannot be nil")
 	}
--- a/beacon-chain/cache/attestation_data_test.go
+++ b/beacon-chain/cache/attestation_data_test.go
@@ -9,7 +9,7 @@ import (
 )

 func TestAttestationCache_RoundTrip(t *testing.T) {
-	c := cache.NewAttestationCache()
+	c := cache.NewAttestationDataCache()

 	a := c.Get()
 	require.Nil(t, a)
--- a/beacon-chain/cache/attestation_test.go
+++ b/beacon-chain/cache/attestation_test.go
@@ -0,0 +1,353 @@
+package cache
+
+import (
+	"testing"
+
+	"github.com/prysmaticlabs/go-bitfield"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v5/crypto/bls/blst"
+	"github.com/prysmaticlabs/prysm/v5/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1/attestation"
+	"github.com/prysmaticlabs/prysm/v5/testing/assert"
+	"github.com/prysmaticlabs/prysm/v5/testing/require"
+)
+
+func TestAdd(t *testing.T) {
+	k, err := blst.RandKey()
+	require.NoError(t, err)
+	sig := k.Sign([]byte{'X'})
+
+	t.Run("new ID", func(t *testing.T) {
+		t.Run("first ID ever", func(t *testing.T) {
+			c := NewAttestationCache()
+			ab := bitfield.NewBitlist(8)
+			ab.SetBitAt(0, true)
+			att := &ethpb.Attestation{
+				Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+				AggregationBits: ab,
+				Signature:       sig.Marshal(),
+			}
+			id, err := attestation.NewId(att, attestation.Data)
+			require.NoError(t, err)
+			require.NoError(t, c.Add(att))
+
+			require.Equal(t, 1, len(c.atts))
+			group, ok := c.atts[id]
+			require.Equal(t, true, ok)
+			assert.Equal(t, primitives.Slot(123), group.slot)
+			require.Equal(t, 1, len(group.atts))
+			assert.DeepEqual(t, group.atts[0], att)
+		})
+		t.Run("other ID exists", func(t *testing.T) {
+			c := NewAttestationCache()
+			ab := bitfield.NewBitlist(8)
+			ab.SetBitAt(0, true)
+			existingAtt := &ethpb.Attestation{
+				Data:            &ethpb.AttestationData{BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+				AggregationBits: ab,
+				Signature:       sig.Marshal(),
+			}
+			existingId, err := attestation.NewId(existingAtt, attestation.Data)
+			require.NoError(t, err)
+			c.atts[existingId] = &attGroup{slot: existingAtt.Data.Slot, atts: []ethpb.Att{existingAtt}}
+
+			att := &ethpb.Attestation{
+				Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+				AggregationBits: ab,
+				Signature:       sig.Marshal(),
+			}
+			id, err := attestation.NewId(att, attestation.Data)
+			require.NoError(t, err)
+			require.NoError(t, c.Add(att))
+
+			require.Equal(t, 2, len(c.atts))
+			group, ok := c.atts[id]
+			require.Equal(t, true, ok)
+			assert.Equal(t, primitives.Slot(123), group.slot)
+			require.Equal(t, 1, len(group.atts))
+			assert.DeepEqual(t, group.atts[0], att)
+		})
+	})
+	t.Run("aggregated", func(t *testing.T) {
+		c := NewAttestationCache()
+		existingAtt := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		id, err := attestation.NewId(existingAtt, attestation.Data)
+		require.NoError(t, err)
+		c.atts[id] = &attGroup{slot: existingAtt.Data.Slot, atts: []ethpb.Att{existingAtt}}
+
+		att := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		att.AggregationBits.SetBitAt(0, true)
+		att.AggregationBits.SetBitAt(1, true)
+		require.NoError(t, c.Add(att))
+
+		require.Equal(t, 1, len(c.atts))
+		group, ok := c.atts[id]
+		require.Equal(t, true, ok)
+		assert.Equal(t, primitives.Slot(123), group.slot)
+		require.Equal(t, 2, len(group.atts))
+		assert.DeepEqual(t, group.atts[0], existingAtt)
+		assert.DeepEqual(t, group.atts[1], att)
+	})
+	t.Run("unaggregated - existing bit", func(t *testing.T) {
+		c := NewAttestationCache()
+		existingAtt := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		existingAtt.AggregationBits.SetBitAt(0, true)
+		id, err := attestation.NewId(existingAtt, attestation.Data)
+		require.NoError(t, err)
+		c.atts[id] = &attGroup{slot: existingAtt.Data.Slot, atts: []ethpb.Att{existingAtt}}
+
+		att := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		att.AggregationBits.SetBitAt(0, true)
+		require.NoError(t, c.Add(att))
+
+		require.Equal(t, 1, len(c.atts))
+		group, ok := c.atts[id]
+		require.Equal(t, true, ok)
+		assert.Equal(t, primitives.Slot(123), group.slot)
+		require.Equal(t, 1, len(group.atts))
+		assert.DeepEqual(t, []int{0}, group.atts[0].GetAggregationBits().BitIndices())
+	})
+	t.Run("unaggregated - new bit", func(t *testing.T) {
+		c := NewAttestationCache()
+		existingAtt := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		existingAtt.AggregationBits.SetBitAt(0, true)
+		id, err := attestation.NewId(existingAtt, attestation.Data)
+		require.NoError(t, err)
+		c.atts[id] = &attGroup{slot: existingAtt.Data.Slot, atts: []ethpb.Att{existingAtt}}
+
+		att := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		att.AggregationBits.SetBitAt(1, true)
+		require.NoError(t, c.Add(att))
+
+		require.Equal(t, 1, len(c.atts))
+		group, ok := c.atts[id]
+		require.Equal(t, true, ok)
+		assert.Equal(t, primitives.Slot(123), group.slot)
+		require.Equal(t, 1, len(group.atts))
+		assert.DeepEqual(t, []int{0, 1}, group.atts[0].GetAggregationBits().BitIndices())
+	})
+}
+
+func TestGetAll(t *testing.T) {
+	c := NewAttestationCache()
+	c.atts[bytesutil.ToBytes32([]byte("id1"))] = &attGroup{atts: []ethpb.Att{&ethpb.Attestation{}, &ethpb.Attestation{}}}
+	c.atts[bytesutil.ToBytes32([]byte("id2"))] = &attGroup{atts: []ethpb.Att{&ethpb.Attestation{}}}
+
+	assert.Equal(t, 3, len(c.GetAll()))
+}
+
+func TestCount(t *testing.T) {
+	c := NewAttestationCache()
+	c.atts[bytesutil.ToBytes32([]byte("id1"))] = &attGroup{atts: []ethpb.Att{&ethpb.Attestation{}, &ethpb.Attestation{}}}
+	c.atts[bytesutil.ToBytes32([]byte("id2"))] = &attGroup{atts: []ethpb.Att{&ethpb.Attestation{}}}
+
+	assert.Equal(t, 3, c.Count())
+}
+
+func TestDeleteCovered(t *testing.T) {
+	k, err := blst.RandKey()
+	require.NoError(t, err)
+	sig := k.Sign([]byte{'X'})
+
+	att1 := &ethpb.Attestation{
+		Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+		AggregationBits: bitfield.NewBitlist(8),
+		Signature:       sig.Marshal(),
+	}
+	att1.AggregationBits.SetBitAt(0, true)
+
+	att2 := &ethpb.Attestation{
+		Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+		AggregationBits: bitfield.NewBitlist(8),
+		Signature:       sig.Marshal(),
+	}
+	att2.AggregationBits.SetBitAt(1, true)
+	att2.AggregationBits.SetBitAt(2, true)
+
+	att3 := &ethpb.Attestation{
+		Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+		AggregationBits: bitfield.NewBitlist(8),
+		Signature:       sig.Marshal(),
+	}
+	att3.AggregationBits.SetBitAt(1, true)
+	att3.AggregationBits.SetBitAt(3, true)
+	att3.AggregationBits.SetBitAt(4, true)
+
+	c := NewAttestationCache()
+	id, err := attestation.NewId(att1, attestation.Data)
+	require.NoError(t, err)
+	c.atts[id] = &attGroup{slot: att1.Data.Slot, atts: []ethpb.Att{att1, att2, att3}}
+
+	t.Run("no matching group", func(t *testing.T) {
+		att := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 456, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		att.AggregationBits.SetBitAt(0, true)
+		att.AggregationBits.SetBitAt(1, true)
+		att.AggregationBits.SetBitAt(2, true)
+		att.AggregationBits.SetBitAt(3, true)
+		att.AggregationBits.SetBitAt(4, true)
+		require.NoError(t, c.DeleteCovered(att))
+
+		assert.Equal(t, 3, len(c.atts[id].atts))
+	})
+	t.Run("covered atts deleted", func(t *testing.T) {
+		att := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		att.AggregationBits.SetBitAt(0, true)
+		att.AggregationBits.SetBitAt(1, true)
+		att.AggregationBits.SetBitAt(3, true)
+		att.AggregationBits.SetBitAt(4, true)
+		require.NoError(t, c.DeleteCovered(att))
+
+		atts := c.atts[id].atts
+		require.Equal(t, 1, len(atts))
+		assert.DeepEqual(t, att2, atts[0])
+	})
+	t.Run("last att in group deleted", func(t *testing.T) {
+		att := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		att.AggregationBits.SetBitAt(0, true)
+		att.AggregationBits.SetBitAt(1, true)
+		att.AggregationBits.SetBitAt(2, true)
+		att.AggregationBits.SetBitAt(3, true)
+		att.AggregationBits.SetBitAt(4, true)
+		require.NoError(t, c.DeleteCovered(att))
+
+		assert.Equal(t, 0, len(c.atts))
+	})
+}
+
+func TestPruneBefore(t *testing.T) {
+	c := NewAttestationCache()
+	c.atts[bytesutil.ToBytes32([]byte("id1"))] = &attGroup{slot: 1, atts: []ethpb.Att{&ethpb.Attestation{}, &ethpb.Attestation{}}}
+	c.atts[bytesutil.ToBytes32([]byte("id2"))] = &attGroup{slot: 3, atts: []ethpb.Att{&ethpb.Attestation{}}}
+	c.atts[bytesutil.ToBytes32([]byte("id3"))] = &attGroup{slot: 2, atts: []ethpb.Att{&ethpb.Attestation{}}}
+
+	count := c.PruneBefore(3)
+
+	require.Equal(t, 1, len(c.atts))
+	_, ok := c.atts[bytesutil.ToBytes32([]byte("id2"))]
+	assert.Equal(t, true, ok)
+	assert.Equal(t, uint64(3), count)
+}
+
+func TestAggregateIsRedundant(t *testing.T) {
+	k, err := blst.RandKey()
+	require.NoError(t, err)
+	sig := k.Sign([]byte{'X'})
+
+	c := NewAttestationCache()
+	existingAtt := &ethpb.Attestation{
+		Data:            &ethpb.AttestationData{Slot: 123, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+		AggregationBits: bitfield.NewBitlist(8),
+		Signature:       sig.Marshal(),
+	}
+	existingAtt.AggregationBits.SetBitAt(0, true)
+	existingAtt.AggregationBits.SetBitAt(1, true)
+	id, err := attestation.NewId(existingAtt, attestation.Data)
+	require.NoError(t, err)
+	c.atts[id] = &attGroup{slot: existingAtt.Data.Slot, atts: []ethpb.Att{existingAtt}}
+
+	t.Run("no matching group", func(t *testing.T) {
+		att := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: 456, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		att.AggregationBits.SetBitAt(0, true)
+
+		redundant, err := c.AggregateIsRedundant(att)
+		require.NoError(t, err)
+		assert.Equal(t, false, redundant)
+	})
+	t.Run("redundant", func(t *testing.T) {
+		att := &ethpb.Attestation{
+			Data:            &ethpb.AttestationData{Slot: existingAtt.Data.Slot, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+			AggregationBits: bitfield.NewBitlist(8),
+			Signature:       sig.Marshal(),
+		}
+		att.AggregationBits.SetBitAt(0, true)
+
+		redundant, err := c.AggregateIsRedundant(att)
+		require.NoError(t, err)
+		assert.Equal(t, true, redundant)
+	})
+	t.Run("not redundant", func(t *testing.T) {
+		t.Run("strictly better", func(t *testing.T) {
+			att := &ethpb.Attestation{
+				Data:            &ethpb.AttestationData{Slot: existingAtt.Data.Slot, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+				AggregationBits: bitfield.NewBitlist(8),
+				Signature:       sig.Marshal(),
+			}
+			att.AggregationBits.SetBitAt(0, true)
+			att.AggregationBits.SetBitAt(1, true)
+			att.AggregationBits.SetBitAt(2, true)
+
+			redundant, err := c.AggregateIsRedundant(att)
+			require.NoError(t, err)
+			assert.Equal(t, false, redundant)
+		})
+		t.Run("overlapping and new bits", func(t *testing.T) {
+			att := &ethpb.Attestation{
+				Data:            &ethpb.AttestationData{Slot: existingAtt.Data.Slot, BeaconBlockRoot: make([]byte, 32), Source: &ethpb.Checkpoint{Root: make([]byte, 32)}, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}},
+				AggregationBits: bitfield.NewBitlist(8),
+				Signature:       sig.Marshal(),
+			}
+			att.AggregationBits.SetBitAt(0, true)
+			att.AggregationBits.SetBitAt(2, true)
+
+			redundant, err := c.AggregateIsRedundant(att)
+			require.NoError(t, err)
+			assert.Equal(t, false, redundant)
+		})
+	})
+}
+
+func TestGetBySlotAndCommitteeIndex(t *testing.T) {
+	c := NewAttestationCache()
+	c.atts[bytesutil.ToBytes32([]byte("id1"))] = &attGroup{slot: 1, atts: []ethpb.Att{&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 1, CommitteeIndex: 1}}, &ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 1, CommitteeIndex: 1}}}}
+	c.atts[bytesutil.ToBytes32([]byte("id2"))] = &attGroup{slot: 2, atts: []ethpb.Att{&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 2, CommitteeIndex: 2}}}}
+	c.atts[bytesutil.ToBytes32([]byte("id3"))] = &attGroup{slot: 1, atts: []ethpb.Att{&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 2, CommitteeIndex: 2}}}}
+
+	// committeeIndex has to be small enough to fit in the bitvector
+	atts := GetBySlotAndCommitteeIndex[*ethpb.Attestation](c, 1, 1)
+	require.Equal(t, 2, len(atts))
+	assert.Equal(t, primitives.Slot(1), atts[0].Data.Slot)
+	assert.Equal(t, primitives.Slot(1), atts[1].Data.Slot)
+	assert.Equal(t, primitives.CommitteeIndex(1), atts[0].Data.CommitteeIndex)
+	assert.Equal(t, primitives.CommitteeIndex(1), atts[1].Data.CommitteeIndex)
+}
--- a/beacon-chain/core/altair/epoch_spec_test.go
+++ b/beacon-chain/core/altair/epoch_spec_test.go
@@ -105,10 +105,9 @@ func TestProcessSlashings_NotSlashed(t *testing.T) {
 	}
 	s, err := state_native.InitializeFromProtoAltair(base)
 	require.NoError(t, err)
-	newState, err := epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplierAltair)
-	require.NoError(t, err)
+	require.NoError(t, epoch.ProcessSlashings(s))
 	wanted := params.BeaconConfig().MaxEffectiveBalance
-	assert.Equal(t, wanted, newState.Balances()[0], "Unexpected slashed balance")
+	assert.Equal(t, wanted, s.Balances()[0], "Unexpected slashed balance")
 }

 func TestProcessSlashings_SlashedLess(t *testing.T) {
@@ -176,9 +175,8 @@ func TestProcessSlashings_SlashedLess(t *testing.T) {
 			original := proto.Clone(tt.state)
 			s, err := state_native.InitializeFromProtoAltair(tt.state)
 			require.NoError(t, err)
-			newState, err := epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplierAltair)
-			require.NoError(t, err)
-			assert.Equal(t, tt.want, newState.Balances()[0], "ProcessSlashings({%v}) = newState; newState.Balances[0] = %d", original, newState.Balances()[0])
+			require.NoError(t, epoch.ProcessSlashings(s))
+			assert.Equal(t, tt.want, s.Balances()[0], "ProcessSlashings({%v}) = newState; newState.Balances[0] = %d", original, s.Balances()[0])
 		})
 	}
 }
@@ -192,6 +190,5 @@ func TestProcessSlashings_BadValue(t *testing.T) {
 	}
 	s, err := state_native.InitializeFromProtoAltair(base)
 	require.NoError(t, err)
-	_, err = epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplierAltair)
-	require.ErrorContains(t, "addition overflows", err)
+	require.ErrorContains(t, "addition overflows", epoch.ProcessSlashings(s))
 }
--- a/beacon-chain/core/altair/sync_committee.go
+++ b/beacon-chain/core/altair/sync_committee.go
@@ -2,6 +2,7 @@ package altair

 import (
 	"context"
+	"encoding/binary"
 	goErrors "errors"
 	"fmt"
 	"time"
@@ -22,8 +23,6 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/time/slots"
 )

-const maxRandomByte = uint64(1<<8 - 1)
-
 var (
 	ErrTooLate = errors.New("sync message is too late")
 )
@@ -91,19 +90,22 @@ func NextSyncCommittee(ctx context.Context, s state.BeaconState) (*ethpb.SyncCom
 //	"""
 //	epoch = Epoch(get_current_epoch(state) + 1)
 //
-//	MAX_RANDOM_BYTE = 2**8 - 1
+//	MAX_RANDOM_VALUE = 2**16 - 1  # [Modified in Electra]
 //	active_validator_indices = get_active_validator_indices(state, epoch)
 //	active_validator_count = uint64(len(active_validator_indices))
 //	seed = get_seed(state, epoch, DOMAIN_SYNC_COMMITTEE)
-//	i = 0
+//	i = uint64(0)
 //	sync_committee_indices: List[ValidatorIndex] = []
 //	while len(sync_committee_indices) < SYNC_COMMITTEE_SIZE:
 //	    shuffled_index = compute_shuffled_index(uint64(i % active_validator_count), active_validator_count, seed)
 //	    candidate_index = active_validator_indices[shuffled_index]
-//	    random_byte = hash(seed + uint_to_bytes(uint64(i // 32)))[i % 32]
+//	    # [Modified in Electra]
+//	    random_bytes = hash(seed + uint_to_bytes(i // 16))
+//	    offset = i % 16 * 2
+//	    random_value = bytes_to_uint64(random_bytes[offset:offset + 2])
 //	    effective_balance = state.validators[candidate_index].effective_balance
 //	    # [Modified in Electra:EIP7251]
-//	    if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE_ELECTRA * random_byte:
+//	    if effective_balance * MAX_RANDOM_VALUE >= MAX_EFFECTIVE_BALANCE_ELECTRA * random_value:
 //	        sync_committee_indices.append(candidate_index)
 //	    i += 1
 //	return sync_committee_indices
@@ -123,12 +125,11 @@ func NextSyncCommitteeIndices(ctx context.Context, s state.BeaconState) ([]primi
 	cIndices := make([]primitives.ValidatorIndex, 0, syncCommitteeSize)
 	hashFunc := hash.CustomSHA256Hasher()

-	maxEB := cfg.MaxEffectiveBalanceElectra
-	if s.Version() < version.Electra {
-		maxEB = cfg.MaxEffectiveBalance
-	}
+	// Preallocate buffers to avoid repeated allocations
+	seedBuffer := make([]byte, len(seed)+8)
+	copy(seedBuffer, seed[:])

-	for i := primitives.ValidatorIndex(0); uint64(len(cIndices)) < params.BeaconConfig().SyncCommitteeSize; i++ {
+	for i := primitives.ValidatorIndex(0); uint64(len(cIndices)) < syncCommitteeSize; i++ {
 		if ctx.Err() != nil {
 			return nil, ctx.Err()
 		}
@@ -137,18 +138,30 @@ func NextSyncCommitteeIndices(ctx context.Context, s state.BeaconState) ([]primi
 		if err != nil {
 			return nil, err
 		}
-
-		b := append(seed[:], bytesutil.Bytes8(uint64(i.Div(32)))...)
-		randomByte := hashFunc(b)[i%32]
 		cIndex := indices[sIndex]
 		v, err := s.ValidatorAtIndexReadOnly(cIndex)
 		if err != nil {
 			return nil, err
 		}
-
 		effectiveBal := v.EffectiveBalance()
-		if effectiveBal*maxRandomByte >= maxEB*uint64(randomByte) {
-			cIndices = append(cIndices, cIndex)
+
+		if s.Version() >= version.Electra {
+			// Use the preallocated seed buffer
+			binary.LittleEndian.PutUint64(seedBuffer[len(seed):], uint64(i/16))
+			randomByte := hashFunc(seedBuffer)
+			offset := (i % 16) * 2
+			randomValue := uint64(randomByte[offset]) | uint64(randomByte[offset+1])<<8
+
+			if effectiveBal*fieldparams.MaxRandomValueElectra >= cfg.MaxEffectiveBalanceElectra*randomValue {
+				cIndices = append(cIndices, cIndex)
+			}
+		} else {
+			// Use the preallocated seed buffer
+			binary.LittleEndian.PutUint64(seedBuffer[len(seed):], uint64(i/32))
+			randomByte := hashFunc(seedBuffer)[i%32]
+			if effectiveBal*fieldparams.MaxRandomByte >= cfg.MaxEffectiveBalance*uint64(randomByte) {
+				cIndices = append(cIndices, cIndex)
+			}
 		}
 	}

--- a/beacon-chain/core/altair/transition.go
+++ b/beacon-chain/core/altair/transition.go
@@ -69,12 +69,7 @@ func ProcessEpoch(ctx context.Context, state state.BeaconState) error {
 	}

 	// Modified in Altair and Bellatrix.
-	proportionalSlashingMultiplier, err := state.ProportionalSlashingMultiplier()
-	if err != nil {
-		return err
-	}
-	state, err = e.ProcessSlashings(state, proportionalSlashingMultiplier)
-	if err != nil {
+	if err := e.ProcessSlashings(state); err != nil {
 		return err
 	}
 	state, err = e.ProcessEth1DataReset(state)
--- a/beacon-chain/core/blocks/genesis.go
+++ b/beacon-chain/core/blocks/genesis.go
@@ -198,7 +198,7 @@ func NewGenesisBlockForState(ctx context.Context, st state.BeaconState) (interfa
 						SyncCommitteeBits:      make([]byte, fieldparams.SyncCommitteeLength/8),
 						SyncCommitteeSignature: make([]byte, fieldparams.BLSSignatureLength),
 					},
-					ExecutionPayload: &enginev1.ExecutionPayloadElectra{
+					ExecutionPayload: &enginev1.ExecutionPayloadDeneb{
 						ParentHash:    make([]byte, 32),
 						FeeRecipient:  make([]byte, 20),
 						StateRoot:     make([]byte, 32),
--- a/beacon-chain/core/blocks/withdrawals_test.go
+++ b/beacon-chain/core/blocks/withdrawals_test.go
@@ -1152,7 +1152,7 @@ func TestProcessWithdrawals(t *testing.T) {
 						}
 						st, err = state_native.InitializeFromProtoUnsafeElectra(spb)
 						require.NoError(t, err)
-						p, err = consensusblocks.WrappedExecutionPayloadElectra(&enginev1.ExecutionPayloadElectra{Withdrawals: test.Args.Withdrawals})
+						p, err = consensusblocks.WrappedExecutionPayloadDeneb(&enginev1.ExecutionPayloadDeneb{Withdrawals: test.Args.Withdrawals})
 						require.NoError(t, err)
 					default:
 						t.Fatalf("Add a beacon state setup for version %s", version.String(fork))
--- a/beacon-chain/core/electra/churn_test.go
+++ b/beacon-chain/core/electra/churn_test.go
@@ -20,7 +20,7 @@ func createValidatorsWithTotalActiveBalance(totalBal primitives.Gwei) []*eth.Val
 	vals := make([]*eth.Validator, num)
 	for i := range vals {
 		wd := make([]byte, 32)
-		wd[0] = params.BeaconConfig().ETH1AddressWithdrawalPrefixByte
+		wd[0] = params.BeaconConfig().CompoundingWithdrawalPrefixByte
 		wd[31] = byte(i)

 		vals[i] = &eth.Validator{
--- a/beacon-chain/core/electra/consolidations.go
+++ b/beacon-chain/core/electra/consolidations.go
@@ -37,8 +37,7 @@ import (
 //	        break
 //
 //	    # Calculate the consolidated balance
-//	    max_effective_balance = get_max_effective_balance(source_validator)
-//	    source_effective_balance = min(state.balances[pending_consolidation.source_index], max_effective_balance)
+//	    source_effective_balance = min(state.balances[pending_consolidation.source_index], source_validator.effective_balance)
 //
 //	    # Move active balance to target. Excess balance is withdrawable.
 //	    decrease_balance(state, pending_consolidation.source_index, source_effective_balance)
@@ -78,7 +77,7 @@ func ProcessPendingConsolidations(ctx context.Context, st state.BeaconState) err
 		if err != nil {
 			return err
 		}
-		b := min(validatorBalance, helpers.ValidatorMaxEffectiveBalance(sourceValidator))
+		b := min(validatorBalance, sourceValidator.EffectiveBalance())

 		if err := helpers.DecreaseBalance(st, pc.SourceIndex, b); err != nil {
 			return err
@@ -141,8 +140,8 @@ func ProcessPendingConsolidations(ctx context.Context, st state.BeaconState) err
 //	    if not (has_correct_credential and is_correct_source_address):
 //	        return
 //
-//	    # Verify that target has execution withdrawal credentials
-//	    if not has_execution_withdrawal_credential(target_validator):
+//	    # Verify that target has compounding withdrawal credentials
+//	    if not has_compounding_withdrawal_credential(target_validator):
 //	        return
 //
 //	    # Verify the source and the target are active
@@ -175,10 +174,6 @@ func ProcessPendingConsolidations(ctx context.Context, st state.BeaconState) err
 //	        source_index=source_index,
 //	        target_index=target_index
 //	    ))
-//
-//	    # Churn any target excess active balance of target and raise its max
-//	    if has_eth1_withdrawal_credential(target_validator):
-//	        switch_to_compounding_validator(state, target_index)
 func ProcessConsolidationRequests(ctx context.Context, st state.BeaconState, reqs []*enginev1.ConsolidationRequest) error {
 	if len(reqs) == 0 || st == nil {
 		return nil
@@ -253,7 +248,7 @@ func ProcessConsolidationRequests(ctx context.Context, st state.BeaconState, req
 		}

 		// Target validator must have their withdrawal credentials set appropriately.
-		if !helpers.HasExecutionWithdrawalCredentials(tgtV) {
+		if !helpers.HasCompoundingWithdrawalCredential(tgtV) {
 			continue
 		}

@@ -298,13 +293,6 @@ func ProcessConsolidationRequests(ctx context.Context, st state.BeaconState, req
 		if err := st.AppendPendingConsolidation(&eth.PendingConsolidation{SourceIndex: srcIdx, TargetIndex: tgtIdx}); err != nil {
 			return fmt.Errorf("failed to append pending consolidation: %w", err) // This should never happen.
 		}
-
-		if helpers.HasETH1WithdrawalCredential(tgtV) {
-			if err := SwitchToCompoundingValidator(st, tgtIdx); err != nil {
-				log.WithError(err).Error("failed to switch to compounding validator")
-				continue
-			}
-		}
 	}

 	return nil
--- a/beacon-chain/core/electra/consolidations_test.go
+++ b/beacon-chain/core/electra/consolidations_test.go
@@ -46,6 +46,7 @@ func TestProcessPendingConsolidations(t *testing.T) {
 					Validators: []*eth.Validator{
 						{
 							WithdrawalCredentials: []byte{0x01, 0xFF},
+							EffectiveBalance:      params.BeaconConfig().MinActivationBalance,
 						},
 						{
 							WithdrawalCredentials: []byte{0x01, 0xAB},
@@ -218,7 +219,7 @@ func TestProcessConsolidationRequests(t *testing.T) {
 				}
 				// Validator scenario setup. See comments in reqs section.
 				st.Validators[3].WithdrawalCredentials = bytesutil.Bytes32(0)
-				st.Validators[8].WithdrawalCredentials = bytesutil.Bytes32(0)
+				st.Validators[8].WithdrawalCredentials = bytesutil.Bytes32(1)
 				st.Validators[9].ActivationEpoch = params.BeaconConfig().FarFutureEpoch
 				st.Validators[12].ActivationEpoch = params.BeaconConfig().FarFutureEpoch
 				st.Validators[13].ExitEpoch = 10
@@ -246,7 +247,7 @@ func TestProcessConsolidationRequests(t *testing.T) {
 					SourcePubkey:  []byte("val_5"),
 					TargetPubkey:  []byte("val_6"),
 				},
-				// Target does not have their withdrawal credentials set appropriately.
+				// Target does not have their withdrawal credentials set appropriately. (Using eth1 address prefix)
 				{
 					SourceAddress: append(bytesutil.PadTo(nil, 19), byte(7)),
 					SourcePubkey:  []byte("val_7"),
--- a/beacon-chain/core/electra/deposits.go
+++ b/beacon-chain/core/electra/deposits.go
@@ -15,7 +15,6 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/encoding/bytesutil"
 	"github.com/prysmaticlabs/prysm/v5/monitoring/tracing/trace"
 	enginev1 "github.com/prysmaticlabs/prysm/v5/proto/engine/v1"
-	eth "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
 	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/v5/runtime/version"
 	"github.com/prysmaticlabs/prysm/v5/time/slots"
@@ -273,7 +272,7 @@ func ProcessPendingDeposits(ctx context.Context, st state.BeaconState, activeBal
 	isChurnLimitReached := false

 	var pendingDepositsToBatchVerify []*ethpb.PendingDeposit
-	var pendingDepositsToPostpone []*eth.PendingDeposit
+	var pendingDepositsToPostpone []*ethpb.PendingDeposit

 	depBalToConsume, err := st.DepositBalanceToConsume()
 	if err != nil {
--- a/beacon-chain/core/electra/registry_updates.go
+++ b/beacon-chain/core/electra/registry_updates.go
@@ -18,23 +18,24 @@ import (
 //
 // Spec pseudocode definition:
 //
-//		def process_registry_updates(state: BeaconState) -> None:
-//		    # Process activation eligibility and ejections
-//		    for index, validator in enumerate(state.validators):
-//		        if is_eligible_for_activation_queue(validator):
-//		            validator.activation_eligibility_epoch = get_current_epoch(state) + 1
+//	def process_registry_updates(state: BeaconState) -> None:
+//	    # Process activation eligibility and ejections
+//	    for index, validator in enumerate(state.validators):
+//	        if is_eligible_for_activation_queue(validator):  # [Modified in Electra:EIP7251]
+//	            validator.activation_eligibility_epoch = get_current_epoch(state) + 1
 //
-//		        if (
-//		            is_active_validator(validator, get_current_epoch(state))
-//		            and validator.effective_balance <= EJECTION_BALANCE
-//		        ):
-//		            initiate_validator_exit(state, ValidatorIndex(index))
+//	        if (
+//	            is_active_validator(validator, get_current_epoch(state))
+//	            and validator.effective_balance <= EJECTION_BALANCE
+//	        ):
+//	            initiate_validator_exit(state, ValidatorIndex(index))  # [Modified in Electra:EIP7251]
 //
-//	         # Activate all eligible validators
-//	         activation_epoch = compute_activation_exit_epoch(get_current_epoch(state))
-//	         for validator in state.validators:
-//	             if is_eligible_for_activation(state, validator):
-//	                 validator.activation_epoch = activation_epoch
+//	    # Activate all eligible validators
+//	    # [Modified in Electra:EIP7251]
+//	    activation_epoch = compute_activation_exit_epoch(get_current_epoch(state))
+//	    for validator in state.validators:
+//	        if is_eligible_for_activation(state, validator):
+//	            validator.activation_epoch = activation_epoch
 func ProcessRegistryUpdates(ctx context.Context, st state.BeaconState) error {
 	currentEpoch := time.CurrentEpoch(st)
 	ejectionBal := params.BeaconConfig().EjectionBalance
@@ -90,8 +91,8 @@ func ProcessRegistryUpdates(ctx context.Context, st state.BeaconState) error {
 		}
 	}

+	// Activate all eligible validators.
 	for _, idx := range eligibleForActivation {
-		// Activate all eligible validators.
 		v, err := st.ValidatorAtIndex(idx)
 		if err != nil {
 			return err
--- a/beacon-chain/core/electra/transition.go
+++ b/beacon-chain/core/electra/transition.go
@@ -40,14 +40,17 @@ var (
 //	    process_justification_and_finalization(state)
 //	    process_inactivity_updates(state)
 //	    process_rewards_and_penalties(state)
-//	    process_registry_updates(state)
-//	    process_slashings(state)
+//	    process_registry_updates(state)  # [Modified in Electra:EIP7251]
+//	    process_slashings(state)  # [Modified in Electra:EIP7251]
 //	    process_eth1_data_reset(state)
-//	    process_pending_deposits(state)  # New in EIP7251
-//	    process_pending_consolidations(state)  # New in EIP7251
-//	    process_effective_balance_updates(state)
+//	    process_pending_deposits(state)  # [New in Electra:EIP7251]
+//	    process_pending_consolidations(state)  # [New in Electra:EIP7251]
+//	    process_effective_balance_updates(state)  # [Modified in Electra:EIP7251]
 //	    process_slashings_reset(state)
 //	    process_randao_mixes_reset(state)
+//	    process_historical_summaries_update(state)
+//	    process_participation_flag_updates(state)
+//	    process_sync_committee_updates(state)
 func ProcessEpoch(ctx context.Context, state state.BeaconState) error {
 	_, span := trace.StartSpan(ctx, "electra.ProcessEpoch")
 	defer span.End()
@@ -75,24 +78,16 @@ func ProcessEpoch(ctx context.Context, state state.BeaconState) error {
 	if err != nil {
 		return errors.Wrap(err, "could not process rewards and penalties")
 	}
-
 	if err := ProcessRegistryUpdates(ctx, state); err != nil {
 		return errors.Wrap(err, "could not process registry updates")
 	}
-
-	proportionalSlashingMultiplier, err := state.ProportionalSlashingMultiplier()
-	if err != nil {
-		return err
-	}
-	state, err = ProcessSlashings(state, proportionalSlashingMultiplier)
-	if err != nil {
+	if err := ProcessSlashings(state); err != nil {
 		return err
 	}
 	state, err = ProcessEth1DataReset(state)
 	if err != nil {
 		return err
 	}
-
 	if err = ProcessPendingDeposits(ctx, state, primitives.Gwei(bp.ActiveCurrentEpoch)); err != nil {
 		return err
 	}
@@ -102,7 +97,6 @@ func ProcessEpoch(ctx context.Context, state state.BeaconState) error {
 	if err = ProcessEffectiveBalanceUpdates(state); err != nil {
 		return err
 	}
-
 	state, err = ProcessSlashingsReset(state)
 	if err != nil {
 		return err
@@ -115,17 +109,14 @@ func ProcessEpoch(ctx context.Context, state state.BeaconState) error {
 	if err != nil {
 		return err
 	}
-
 	state, err = ProcessParticipationFlagUpdates(state)
 	if err != nil {
 		return err
 	}
-
 	_, err = ProcessSyncCommitteeUpdates(ctx, state)
 	if err != nil {
 		return err
 	}
-
 	return nil
 }

--- a/beacon-chain/core/electra/upgrade.go
+++ b/beacon-chain/core/electra/upgrade.go
@@ -240,7 +240,7 @@ func UpgradeToElectra(beaconState state.BeaconState) (state.BeaconState, error)
 		InactivityScores:            inactivityScores,
 		CurrentSyncCommittee:        currentSyncCommittee,
 		NextSyncCommittee:           nextSyncCommittee,
-		LatestExecutionPayloadHeader: &enginev1.ExecutionPayloadHeaderElectra{
+		LatestExecutionPayloadHeader: &enginev1.ExecutionPayloadHeaderDeneb{
 			ParentHash:       payloadHeader.ParentHash(),
 			FeeRecipient:     payloadHeader.FeeRecipient(),
 			StateRoot:        payloadHeader.StateRoot(),
--- a/beacon-chain/core/electra/upgrade_test.go
+++ b/beacon-chain/core/electra/upgrade_test.go
@@ -102,7 +102,7 @@ func TestUpgradeToElectra(t *testing.T) {

 	header, err := mSt.LatestExecutionPayloadHeader()
 	require.NoError(t, err)
-	protoHeader, ok := header.Proto().(*enginev1.ExecutionPayloadHeaderElectra)
+	protoHeader, ok := header.Proto().(*enginev1.ExecutionPayloadHeaderDeneb)
 	require.Equal(t, true, ok)
 	prevHeader, err := preForkState.LatestExecutionPayloadHeader()
 	require.NoError(t, err)
@@ -111,7 +111,7 @@ func TestUpgradeToElectra(t *testing.T) {

 	wdRoot, err := prevHeader.WithdrawalsRoot()
 	require.NoError(t, err)
-	wanted := &enginev1.ExecutionPayloadHeaderElectra{
+	wanted := &enginev1.ExecutionPayloadHeaderDeneb{
 		ParentHash:       prevHeader.ParentHash(),
 		FeeRecipient:     prevHeader.FeeRecipient(),
 		StateRoot:        prevHeader.StateRoot(),
--- a/beacon-chain/core/epoch/epoch_processing.go
+++ b/beacon-chain/core/epoch/epoch_processing.go
@@ -141,29 +141,76 @@ func ProcessRegistryUpdates(ctx context.Context, st state.BeaconState) (state.Be
 	return st, nil
 }

-// ProcessSlashings processes the slashed validators during epoch processing,
+// ProcessSlashings processes the slashed validators during epoch processing. This is a state mutating method.
+//
+// Electra spec definition:
 //
 //	def process_slashings(state: BeaconState) -> None:
-//	  epoch = get_current_epoch(state)
-//	  total_balance = get_total_active_balance(state)
-//	  adjusted_total_slashing_balance = min(sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER, total_balance)
-//	  if state.version == electra:
-//		 increment = EFFECTIVE_BALANCE_INCREMENT  # Factored out from total balance to avoid uint64 overflow
-//	  penalty_per_effective_balance_increment = adjusted_total_slashing_balance // (total_balance // increment)
-//	  for index, validator in enumerate(state.validators):
-//	      if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR // 2 == validator.withdrawable_epoch:
-//	          increment = EFFECTIVE_BALANCE_INCREMENT  # Factored out from penalty numerator to avoid uint64 overflow
-//	          penalty_numerator = validator.effective_balance // increment * adjusted_total_slashing_balance
-//	          penalty = penalty_numerator // total_balance * increment
-//	          if state.version == electra:
+//	    epoch = get_current_epoch(state)
+//	    total_balance = get_total_active_balance(state)
+//	    adjusted_total_slashing_balance = min(
+//	        sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER_BELLATRIX,
+//	        total_balance
+//	    )
+//	    increment = EFFECTIVE_BALANCE_INCREMENT  # Factored out from total balance to avoid uint64 overflow
+//	    penalty_per_effective_balance_increment = adjusted_total_slashing_balance // (total_balance // increment)
+//	    for index, validator in enumerate(state.validators):
+//	        if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR // 2 == validator.withdrawable_epoch:
 //	            effective_balance_increments = validator.effective_balance // increment
+//	            # [Modified in Electra:EIP7251]
 //	            penalty = penalty_per_effective_balance_increment * effective_balance_increments
-//	          decrease_balance(state, ValidatorIndex(index), penalty)
-func ProcessSlashings(st state.BeaconState, slashingMultiplier uint64) (state.BeaconState, error) {
+//	            decrease_balance(state, ValidatorIndex(index), penalty)
+//
+// Bellatrix spec definition:
+//
+//	def process_slashings(state: BeaconState) -> None:
+//	    epoch = get_current_epoch(state)
+//	    total_balance = get_total_active_balance(state)
+//	    adjusted_total_slashing_balance = min(
+//	        sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER_BELLATRIX,  # [Modified in Bellatrix]
+//	        total_balance
+//	    )
+//	    for index, validator in enumerate(state.validators):
+//	        if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR // 2 == validator.withdrawable_epoch:
+//	            increment = EFFECTIVE_BALANCE_INCREMENT  # Factored out from penalty numerator to avoid uint64 overflow
+//	            penalty_numerator = validator.effective_balance // increment * adjusted_total_slashing_balance
+//	            penalty = penalty_numerator // total_balance * increment
+//	            decrease_balance(state, ValidatorIndex(index), penalty)
+//
+// Altair spec definition:
+//
+//	def process_slashings(state: BeaconState) -> None:
+//	    epoch = get_current_epoch(state)
+//	    total_balance = get_total_active_balance(state)
+//	    adjusted_total_slashing_balance = min(sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER_ALTAIR, total_balance)
+//	    for index, validator in enumerate(state.validators):
+//	        if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR // 2 == validator.withdrawable_epoch:
+//	            increment = EFFECTIVE_BALANCE_INCREMENT  # Factored out from penalty numerator to avoid uint64 overflow
+//	            penalty_numerator = validator.effective_balance // increment * adjusted_total_slashing_balance
+//	            penalty = penalty_numerator // total_balance * increment
+//	            decrease_balance(state, ValidatorIndex(index), penalty)
+//
+// Phase0 spec definition:
+//
+//	def process_slashings(state: BeaconState) -> None:
+//	    epoch = get_current_epoch(state)
+//	    total_balance = get_total_active_balance(state)
+//	    adjusted_total_slashing_balance = min(sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER, total_balance)
+//	    for index, validator in enumerate(state.validators):
+//	        if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR // 2 == validator.withdrawable_epoch:
+//	            increment = EFFECTIVE_BALANCE_INCREMENT  # Factored out from penalty numerator to avoid uint64 overflow
+//	            penalty_numerator = validator.effective_balance // increment * adjusted_total_slashing_balance
+//	            penalty = penalty_numerator // total_balance * increment
+//	            decrease_balance(state, ValidatorIndex(index), penalty)
+func ProcessSlashings(st state.BeaconState) error {
+	slashingMultiplier, err := st.ProportionalSlashingMultiplier()
+	if err != nil {
+		return errors.Wrap(err, "could not get proportional slashing multiplier")
+	}
 	currentEpoch := time.CurrentEpoch(st)
 	totalBalance, err := helpers.TotalActiveBalance(st)
 	if err != nil {
-		return nil, errors.Wrap(err, "could not get total active balance")
+		return errors.Wrap(err, "could not get total active balance")
 	}

 	// Compute slashed balances in the current epoch
@@ -175,7 +222,7 @@ func ProcessSlashings(st state.BeaconState, slashingMultiplier uint64) (state.Be
 	for _, slashing := range slashings {
 		totalSlashing, err = math.Add64(totalSlashing, slashing)
 		if err != nil {
-			return nil, err
+			return err
 		}
 	}

@@ -209,14 +256,14 @@ func ProcessSlashings(st state.BeaconState, slashingMultiplier uint64) (state.Be
 		return nil
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 	if changed {
 		if err := st.SetBalances(bals); err != nil {
-			return nil, err
+			return err
 		}
 	}
-	return st, nil
+	return nil
 }

 // ProcessEth1DataReset processes updates to ETH1 data votes during epoch processing.
--- a/beacon-chain/core/epoch/epoch_processing_test.go
+++ b/beacon-chain/core/epoch/epoch_processing_test.go
@@ -32,10 +32,9 @@ func TestProcessSlashings_NotSlashed(t *testing.T) {
 	}
 	s, err := state_native.InitializeFromProtoPhase0(base)
 	require.NoError(t, err)
-	newState, err := epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplier)
-	require.NoError(t, err)
+	require.NoError(t, epoch.ProcessSlashings(s))
 	wanted := params.BeaconConfig().MaxEffectiveBalance
-	assert.Equal(t, wanted, newState.Balances()[0], "Unexpected slashed balance")
+	assert.Equal(t, wanted, s.Balances()[0], "Unexpected slashed balance")
 }

 func TestProcessSlashings_SlashedLess(t *testing.T) {
@@ -111,9 +110,8 @@ func TestProcessSlashings_SlashedLess(t *testing.T) {
 			s, err := state_native.InitializeFromProtoPhase0(tt.state)
 			require.NoError(t, err)
 			helpers.ClearCache()
-			newState, err := epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplier)
-			require.NoError(t, err)
-			assert.Equal(t, tt.want, newState.Balances()[0], "ProcessSlashings({%v}) = newState; newState.Balances[0] = %d", original, newState.Balances()[0])
+			require.NoError(t, epoch.ProcessSlashings(s))
+			assert.Equal(t, tt.want, s.Balances()[0], "ProcessSlashings({%v}) = newState; newState.Balances[0] = %d", original, s.Balances()[0])
 		})
 	}
 }
@@ -365,8 +363,7 @@ func TestProcessSlashings_BadValue(t *testing.T) {
 	}
 	s, err := state_native.InitializeFromProtoPhase0(base)
 	require.NoError(t, err)
-	_, err = epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplier)
-	require.ErrorContains(t, "addition overflows", err)
+	require.ErrorContains(t, "addition overflows", epoch.ProcessSlashings(s))
 }

 func TestProcessHistoricalDataUpdate(t *testing.T) {
@@ -514,9 +511,8 @@ func TestProcessSlashings_SlashedElectra(t *testing.T) {
 			s, err := state_native.InitializeFromProtoElectra(tt.state)
 			require.NoError(t, err)
 			helpers.ClearCache()
-			newState, err := epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplierBellatrix)
-			require.NoError(t, err)
-			assert.Equal(t, tt.want, newState.Balances()[0], "ProcessSlashings({%v}) = newState; newState.Balances[0] = %d", original, newState.Balances()[0])
+			require.NoError(t, epoch.ProcessSlashings(s))
+			assert.Equal(t, tt.want, s.Balances()[0], "ProcessSlashings({%v}); s.Balances[0] = %d", original, s.Balances()[0])
 		})
 	}
 }
--- a/beacon-chain/core/fulu/BUILD.bazel
+++ b/beacon-chain/core/fulu/BUILD.bazel
@@ -0,0 +1,37 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["upgrade.go"],
+    importpath = "github.com/prysmaticlabs/prysm/v5/beacon-chain/core/fulu",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
+        "//beacon-chain/state:go_default_library",
+        "//beacon-chain/state/state-native:go_default_library",
+        "//config/params:go_default_library",
+        "//consensus-types/primitives:go_default_library",
+        "//proto/engine/v1:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//time/slots:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["upgrade_test.go"],
+    deps = [
+        ":go_default_library",
+        "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
+        "//config/params:go_default_library",
+        "//consensus-types/primitives:go_default_library",
+        "//proto/engine/v1:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//testing/require:go_default_library",
+        "//testing/util:go_default_library",
+        "//time/slots:go_default_library",
+    ],
+)
--- a/beacon-chain/core/fulu/upgrade.go
+++ b/beacon-chain/core/fulu/upgrade.go
@@ -0,0 +1,184 @@
+package fulu
+
+import (
+	"sort"
+
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/time"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
+	state_native "github.com/prysmaticlabs/prysm/v5/beacon-chain/state/state-native"
+	"github.com/prysmaticlabs/prysm/v5/config/params"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
+	enginev1 "github.com/prysmaticlabs/prysm/v5/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v5/time/slots"
+)
+
+// UpgradeToFulu updates inputs a generic state to return the version Fulu state.
+// https://github.com/ethereum/consensus-specs/blob/dev/specs/fulu/fork.md#upgrading-the-state
+func UpgradeToFulu(beaconState state.BeaconState) (state.BeaconState, error) {
+	currentSyncCommittee, err := beaconState.CurrentSyncCommittee()
+	if err != nil {
+		return nil, err
+	}
+	nextSyncCommittee, err := beaconState.NextSyncCommittee()
+	if err != nil {
+		return nil, err
+	}
+	prevEpochParticipation, err := beaconState.PreviousEpochParticipation()
+	if err != nil {
+		return nil, err
+	}
+	currentEpochParticipation, err := beaconState.CurrentEpochParticipation()
+	if err != nil {
+		return nil, err
+	}
+	inactivityScores, err := beaconState.InactivityScores()
+	if err != nil {
+		return nil, err
+	}
+	payloadHeader, err := beaconState.LatestExecutionPayloadHeader()
+	if err != nil {
+		return nil, err
+	}
+	txRoot, err := payloadHeader.TransactionsRoot()
+	if err != nil {
+		return nil, err
+	}
+	wdRoot, err := payloadHeader.WithdrawalsRoot()
+	if err != nil {
+		return nil, err
+	}
+	wi, err := beaconState.NextWithdrawalIndex()
+	if err != nil {
+		return nil, err
+	}
+	vi, err := beaconState.NextWithdrawalValidatorIndex()
+	if err != nil {
+		return nil, err
+	}
+	summaries, err := beaconState.HistoricalSummaries()
+	if err != nil {
+		return nil, err
+	}
+	historicalRoots, err := beaconState.HistoricalRoots()
+	if err != nil {
+		return nil, err
+	}
+	excessBlobGas, err := payloadHeader.ExcessBlobGas()
+	if err != nil {
+		return nil, err
+	}
+	blobGasUsed, err := payloadHeader.BlobGasUsed()
+	if err != nil {
+		return nil, err
+	}
+
+	earliestExitEpoch := helpers.ActivationExitEpoch(time.CurrentEpoch(beaconState))
+	preActivationIndices := make([]primitives.ValidatorIndex, 0)
+	compoundWithdrawalIndices := make([]primitives.ValidatorIndex, 0)
+	if err = beaconState.ReadFromEveryValidator(func(index int, val state.ReadOnlyValidator) error {
+		if val.ExitEpoch() != params.BeaconConfig().FarFutureEpoch && val.ExitEpoch() > earliestExitEpoch {
+			earliestExitEpoch = val.ExitEpoch()
+		}
+		if val.ActivationEpoch() == params.BeaconConfig().FarFutureEpoch {
+			preActivationIndices = append(preActivationIndices, primitives.ValidatorIndex(index))
+		}
+		if helpers.HasCompoundingWithdrawalCredential(val) {
+			compoundWithdrawalIndices = append(compoundWithdrawalIndices, primitives.ValidatorIndex(index))
+		}
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+
+	earliestExitEpoch++ // Increment to find the earliest possible exit epoch
+
+	// note: should be the same in prestate and post beaconState.
+	// we are deviating from the specs a bit as it calls for using the post beaconState
+	tab, err := helpers.TotalActiveBalance(beaconState)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to get total active balance")
+	}
+
+	s := &ethpb.BeaconStateFulu{
+		GenesisTime:           beaconState.GenesisTime(),
+		GenesisValidatorsRoot: beaconState.GenesisValidatorsRoot(),
+		Slot:                  beaconState.Slot(),
+		Fork: &ethpb.Fork{
+			PreviousVersion: beaconState.Fork().CurrentVersion,
+			CurrentVersion:  params.BeaconConfig().FuluForkVersion,
+			Epoch:           time.CurrentEpoch(beaconState),
+		},
+		LatestBlockHeader:           beaconState.LatestBlockHeader(),
+		BlockRoots:                  beaconState.BlockRoots(),
+		StateRoots:                  beaconState.StateRoots(),
+		HistoricalRoots:             historicalRoots,
+		Eth1Data:                    beaconState.Eth1Data(),
+		Eth1DataVotes:               beaconState.Eth1DataVotes(),
+		Eth1DepositIndex:            beaconState.Eth1DepositIndex(),
+		Validators:                  beaconState.Validators(),
+		Balances:                    beaconState.Balances(),
+		RandaoMixes:                 beaconState.RandaoMixes(),
+		Slashings:                   beaconState.Slashings(),
+		PreviousEpochParticipation:  prevEpochParticipation,
+		CurrentEpochParticipation:   currentEpochParticipation,
+		JustificationBits:           beaconState.JustificationBits(),
+		PreviousJustifiedCheckpoint: beaconState.PreviousJustifiedCheckpoint(),
+		CurrentJustifiedCheckpoint:  beaconState.CurrentJustifiedCheckpoint(),
+		FinalizedCheckpoint:         beaconState.FinalizedCheckpoint(),
+		InactivityScores:            inactivityScores,
+		CurrentSyncCommittee:        currentSyncCommittee,
+		NextSyncCommittee:           nextSyncCommittee,
+		LatestExecutionPayloadHeader: &enginev1.ExecutionPayloadHeaderDeneb{
+			ParentHash:       payloadHeader.ParentHash(),
+			FeeRecipient:     payloadHeader.FeeRecipient(),
+			StateRoot:        payloadHeader.StateRoot(),
+			ReceiptsRoot:     payloadHeader.ReceiptsRoot(),
+			LogsBloom:        payloadHeader.LogsBloom(),
+			PrevRandao:       payloadHeader.PrevRandao(),
+			BlockNumber:      payloadHeader.BlockNumber(),
+			GasLimit:         payloadHeader.GasLimit(),
+			GasUsed:          payloadHeader.GasUsed(),
+			Timestamp:        payloadHeader.Timestamp(),
+			ExtraData:        payloadHeader.ExtraData(),
+			BaseFeePerGas:    payloadHeader.BaseFeePerGas(),
+			BlockHash:        payloadHeader.BlockHash(),
+			TransactionsRoot: txRoot,
+			WithdrawalsRoot:  wdRoot,
+			ExcessBlobGas:    excessBlobGas,
+			BlobGasUsed:      blobGasUsed,
+		},
+		NextWithdrawalIndex:          wi,
+		NextWithdrawalValidatorIndex: vi,
+		HistoricalSummaries:          summaries,
+
+		DepositRequestsStartIndex:     params.BeaconConfig().UnsetDepositRequestsStartIndex,
+		DepositBalanceToConsume:       0,
+		ExitBalanceToConsume:          helpers.ActivationExitChurnLimit(primitives.Gwei(tab)),
+		EarliestExitEpoch:             earliestExitEpoch,
+		ConsolidationBalanceToConsume: helpers.ConsolidationChurnLimit(primitives.Gwei(tab)),
+		EarliestConsolidationEpoch:    helpers.ActivationExitEpoch(slots.ToEpoch(beaconState.Slot())),
+		PendingDeposits:               make([]*ethpb.PendingDeposit, 0),
+		PendingPartialWithdrawals:     make([]*ethpb.PendingPartialWithdrawal, 0),
+		PendingConsolidations:         make([]*ethpb.PendingConsolidation, 0),
+	}
+
+	// Sorting preActivationIndices based on a custom criteria
+	sort.Slice(preActivationIndices, func(i, j int) bool {
+		// Comparing based on ActivationEligibilityEpoch and then by index if the epochs are the same
+		if s.Validators[preActivationIndices[i]].ActivationEligibilityEpoch == s.Validators[preActivationIndices[j]].ActivationEligibilityEpoch {
+			return preActivationIndices[i] < preActivationIndices[j]
+		}
+		return s.Validators[preActivationIndices[i]].ActivationEligibilityEpoch < s.Validators[preActivationIndices[j]].ActivationEligibilityEpoch
+	})
+
+	// Need to cast the beaconState to use in helper functions
+	post, err := state_native.InitializeFromProtoUnsafeFulu(s)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to initialize post fulu beaconState")
+	}
+
+	return post, nil
+}
--- a/beacon-chain/core/fulu/upgrade_test.go
+++ b/beacon-chain/core/fulu/upgrade_test.go
@@ -0,0 +1,188 @@
+package fulu_test
+
+import (
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/fulu"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/time"
+	"github.com/prysmaticlabs/prysm/v5/config/params"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
+	enginev1 "github.com/prysmaticlabs/prysm/v5/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v5/testing/require"
+	"github.com/prysmaticlabs/prysm/v5/testing/util"
+	"github.com/prysmaticlabs/prysm/v5/time/slots"
+)
+
+func TestUpgradeToFulu(t *testing.T) {
+	st, _ := util.DeterministicGenesisStateElectra(t, params.BeaconConfig().MaxValidatorsPerCommittee)
+	require.NoError(t, st.SetHistoricalRoots([][]byte{{1}}))
+	vals := st.Validators()
+	vals[0].ActivationEpoch = params.BeaconConfig().FarFutureEpoch
+	vals[1].WithdrawalCredentials = []byte{params.BeaconConfig().CompoundingWithdrawalPrefixByte}
+	require.NoError(t, st.SetValidators(vals))
+	bals := st.Balances()
+	bals[1] = params.BeaconConfig().MinActivationBalance + 1000
+	require.NoError(t, st.SetBalances(bals))
+
+	preForkState := st.Copy()
+	mSt, err := fulu.UpgradeToFulu(st)
+	require.NoError(t, err)
+
+	require.Equal(t, preForkState.GenesisTime(), mSt.GenesisTime())
+	require.DeepSSZEqual(t, preForkState.GenesisValidatorsRoot(), mSt.GenesisValidatorsRoot())
+	require.Equal(t, preForkState.Slot(), mSt.Slot())
+	require.DeepSSZEqual(t, preForkState.LatestBlockHeader(), mSt.LatestBlockHeader())
+	require.DeepSSZEqual(t, preForkState.BlockRoots(), mSt.BlockRoots())
+	require.DeepSSZEqual(t, preForkState.StateRoots(), mSt.StateRoots())
+	require.DeepSSZEqual(t, preForkState.Validators()[2:], mSt.Validators()[2:])
+	require.DeepSSZEqual(t, preForkState.Balances()[2:], mSt.Balances()[2:])
+	require.DeepSSZEqual(t, preForkState.Eth1Data(), mSt.Eth1Data())
+	require.DeepSSZEqual(t, preForkState.Eth1DataVotes(), mSt.Eth1DataVotes())
+	require.DeepSSZEqual(t, preForkState.Eth1DepositIndex(), mSt.Eth1DepositIndex())
+	require.DeepSSZEqual(t, preForkState.RandaoMixes(), mSt.RandaoMixes())
+	require.DeepSSZEqual(t, preForkState.Slashings(), mSt.Slashings())
+	require.DeepSSZEqual(t, preForkState.JustificationBits(), mSt.JustificationBits())
+	require.DeepSSZEqual(t, preForkState.PreviousJustifiedCheckpoint(), mSt.PreviousJustifiedCheckpoint())
+	require.DeepSSZEqual(t, preForkState.CurrentJustifiedCheckpoint(), mSt.CurrentJustifiedCheckpoint())
+	require.DeepSSZEqual(t, preForkState.FinalizedCheckpoint(), mSt.FinalizedCheckpoint())
+
+	require.Equal(t, len(preForkState.Validators()), len(mSt.Validators()))
+
+	preVal, err := preForkState.ValidatorAtIndex(0)
+	require.NoError(t, err)
+	require.Equal(t, params.BeaconConfig().MaxEffectiveBalance, preVal.EffectiveBalance)
+
+	preVal2, err := preForkState.ValidatorAtIndex(1)
+	require.NoError(t, err)
+	require.Equal(t, params.BeaconConfig().MaxEffectiveBalance, preVal2.EffectiveBalance)
+
+	// TODO: Fix this test
+	// mVal, err := mSt.ValidatorAtIndex(0)
+	_, err = mSt.ValidatorAtIndex(0)
+	require.NoError(t, err)
+	// require.Equal(t, uint64(0), mVal.EffectiveBalance)
+
+	mVal2, err := mSt.ValidatorAtIndex(1)
+	require.NoError(t, err)
+	require.Equal(t, params.BeaconConfig().MinActivationBalance, mVal2.EffectiveBalance)
+
+	numValidators := mSt.NumValidators()
+	p, err := mSt.PreviousEpochParticipation()
+	require.NoError(t, err)
+	require.DeepSSZEqual(t, make([]byte, numValidators), p)
+	p, err = mSt.CurrentEpochParticipation()
+	require.NoError(t, err)
+	require.DeepSSZEqual(t, make([]byte, numValidators), p)
+	s, err := mSt.InactivityScores()
+	require.NoError(t, err)
+	require.DeepSSZEqual(t, make([]uint64, numValidators), s)
+
+	hr1, err := preForkState.HistoricalRoots()
+	require.NoError(t, err)
+	hr2, err := mSt.HistoricalRoots()
+	require.NoError(t, err)
+	require.DeepEqual(t, hr1, hr2)
+
+	f := mSt.Fork()
+	require.DeepSSZEqual(t, &ethpb.Fork{
+		PreviousVersion: st.Fork().CurrentVersion,
+		CurrentVersion:  params.BeaconConfig().FuluForkVersion,
+		Epoch:           time.CurrentEpoch(st),
+	}, f)
+	csc, err := mSt.CurrentSyncCommittee()
+	require.NoError(t, err)
+	psc, err := preForkState.CurrentSyncCommittee()
+	require.NoError(t, err)
+	require.DeepSSZEqual(t, psc, csc)
+	nsc, err := mSt.NextSyncCommittee()
+	require.NoError(t, err)
+	psc, err = preForkState.NextSyncCommittee()
+	require.NoError(t, err)
+	require.DeepSSZEqual(t, psc, nsc)
+
+	header, err := mSt.LatestExecutionPayloadHeader()
+	require.NoError(t, err)
+	protoHeader, ok := header.Proto().(*enginev1.ExecutionPayloadHeaderDeneb)
+	require.Equal(t, true, ok)
+	prevHeader, err := preForkState.LatestExecutionPayloadHeader()
+	require.NoError(t, err)
+	txRoot, err := prevHeader.TransactionsRoot()
+	require.NoError(t, err)
+
+	wdRoot, err := prevHeader.WithdrawalsRoot()
+	require.NoError(t, err)
+	wanted := &enginev1.ExecutionPayloadHeaderDeneb{
+		ParentHash:       prevHeader.ParentHash(),
+		FeeRecipient:     prevHeader.FeeRecipient(),
+		StateRoot:        prevHeader.StateRoot(),
+		ReceiptsRoot:     prevHeader.ReceiptsRoot(),
+		LogsBloom:        prevHeader.LogsBloom(),
+		PrevRandao:       prevHeader.PrevRandao(),
+		BlockNumber:      prevHeader.BlockNumber(),
+		GasLimit:         prevHeader.GasLimit(),
+		GasUsed:          prevHeader.GasUsed(),
+		Timestamp:        prevHeader.Timestamp(),
+		ExtraData:        prevHeader.ExtraData(),
+		BaseFeePerGas:    prevHeader.BaseFeePerGas(),
+		BlockHash:        prevHeader.BlockHash(),
+		TransactionsRoot: txRoot,
+		WithdrawalsRoot:  wdRoot,
+	}
+	require.DeepEqual(t, wanted, protoHeader)
+
+	nwi, err := mSt.NextWithdrawalIndex()
+	require.NoError(t, err)
+	require.Equal(t, uint64(0), nwi)
+
+	lwvi, err := mSt.NextWithdrawalValidatorIndex()
+	require.NoError(t, err)
+	require.Equal(t, primitives.ValidatorIndex(0), lwvi)
+
+	summaries, err := mSt.HistoricalSummaries()
+	require.NoError(t, err)
+	require.Equal(t, 0, len(summaries))
+
+	startIndex, err := mSt.DepositRequestsStartIndex()
+	require.NoError(t, err)
+	require.Equal(t, params.BeaconConfig().UnsetDepositRequestsStartIndex, startIndex)
+
+	balance, err := mSt.DepositBalanceToConsume()
+	require.NoError(t, err)
+	require.Equal(t, primitives.Gwei(0), balance)
+
+	tab, err := helpers.TotalActiveBalance(mSt)
+	require.NoError(t, err)
+
+	ebtc, err := mSt.ExitBalanceToConsume()
+	require.NoError(t, err)
+	require.Equal(t, helpers.ActivationExitChurnLimit(primitives.Gwei(tab)), ebtc)
+
+	eee, err := mSt.EarliestExitEpoch()
+	require.NoError(t, err)
+	require.Equal(t, helpers.ActivationExitEpoch(primitives.Epoch(1)), eee)
+
+	cbtc, err := mSt.ConsolidationBalanceToConsume()
+	require.NoError(t, err)
+	require.Equal(t, helpers.ConsolidationChurnLimit(primitives.Gwei(tab)), cbtc)
+
+	earliestConsolidationEpoch, err := mSt.EarliestConsolidationEpoch()
+	require.NoError(t, err)
+	require.Equal(t, helpers.ActivationExitEpoch(slots.ToEpoch(preForkState.Slot())), earliestConsolidationEpoch)
+
+	// TODO: Fix this test
+	// pendingDeposits, err := mSt.PendingDeposits()
+	_, err = mSt.PendingDeposits()
+	require.NoError(t, err)
+	// require.Equal(t, 2, len(pendingDeposits))
+	// require.Equal(t, uint64(1000), pendingDeposits[1].Amount)
+
+	numPendingPartialWithdrawals, err := mSt.NumPendingPartialWithdrawals()
+	require.NoError(t, err)
+	require.Equal(t, uint64(0), numPendingPartialWithdrawals)
+
+	consolidations, err := mSt.PendingConsolidations()
+	require.NoError(t, err)
+	require.Equal(t, 0, len(consolidations))
+}
--- a/beacon-chain/core/helpers/attestation.go
+++ b/beacon-chain/core/helpers/attestation.go
@@ -32,6 +32,9 @@ func ValidateNilAttestation(attestation ethpb.Att) error {
 	if attestation.GetData().Target == nil {
 		return errors.New("attestation's target can't be nil")
 	}
+	if attestation.IsSingle() {
+		return nil
+	}
 	if attestation.GetAggregationBits() == nil {
 		return errors.New("attestation's bitfield can't be nil")
 	}
@@ -67,12 +70,6 @@ func IsAggregator(committeeCount uint64, slotSig []byte) (bool, error) {
 	return binary.LittleEndian.Uint64(b[:8])%modulo == 0, nil
 }

-// IsAggregated returns true if the attestation is an aggregated attestation,
-// false otherwise.
-func IsAggregated(attestation ethpb.Att) bool {
-	return attestation.GetAggregationBits().Count() > 1
-}
-
 // ComputeSubnetForAttestation returns the subnet for which the provided attestation will be broadcasted to.
 // This differs from the spec definition by instead passing in the active validators indices in the attestation's
 // given epoch.
--- a/beacon-chain/core/helpers/attestation_test.go
+++ b/beacon-chain/core/helpers/attestation_test.go
@@ -308,6 +308,16 @@ func TestValidateNilAttestation(t *testing.T) {
 			},
 			errString: "",
 		},
+		{
+			name: "single attestation",
+			attestation: &ethpb.SingleAttestation{
+				Data: &ethpb.AttestationData{
+					Target: &ethpb.Checkpoint{},
+					Source: &ethpb.Checkpoint{},
+				},
+			},
+			errString: "",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
--- a/beacon-chain/core/helpers/beacon_committee_test.go
+++ b/beacon-chain/core/helpers/beacon_committee_test.go
@@ -97,6 +97,13 @@ func TestVerifyBitfieldLength_OK(t *testing.T) {
 	assert.NoError(t, helpers.VerifyBitfieldLength(bf, committeeSize), "Bitfield is not validated when it was supposed to be")
 }

+func TestVerifyBitfieldLength_Incorrect(t *testing.T) {
+	helpers.ClearCache()
+
+	bf := bitfield.NewBitlist(1)
+	require.ErrorContains(t, "wanted participants bitfield length 2, got: 1", helpers.VerifyBitfieldLength(bf, 2))
+}
+
 func TestCommitteeAssignments_CannotRetrieveFutureEpoch(t *testing.T) {
 	helpers.ClearCache()

--- a/beacon-chain/core/helpers/validators.go
+++ b/beacon-chain/core/helpers/validators.go
@@ -3,6 +3,7 @@ package helpers
 import (
 	"bytes"
 	"context"
+	"encoding/binary"

 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
@@ -11,6 +12,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/time"
 	forkchoicetypes "github.com/prysmaticlabs/prysm/v5/beacon-chain/forkchoice/types"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
+	fieldparams "github.com/prysmaticlabs/prysm/v5/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/interfaces"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
@@ -347,27 +349,33 @@ func BeaconProposerIndexAtSlot(ctx context.Context, state state.ReadOnlyBeaconSt
 // Spec pseudocode definition:
 //
 //	def compute_proposer_index(state: BeaconState, indices: Sequence[ValidatorIndex], seed: Bytes32) -> ValidatorIndex:
-//	  """
-//	  Return from ``indices`` a random index sampled by effective balance.
-//	  """
-//	  assert len(indices) > 0
-//	  MAX_RANDOM_BYTE = 2**8 - 1
-//	  i = uint64(0)
-//	  total = uint64(len(indices))
-//	  while True:
-//	      candidate_index = indices[compute_shuffled_index(i % total, total, seed)]
-//	      random_byte = hash(seed + uint_to_bytes(uint64(i // 32)))[i % 32]
-//	      effective_balance = state.validators[candidate_index].effective_balance
-//	      if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE_ELECTRA * random_byte: #[Modified in Electra:EIP7251]
-//	          return candidate_index
-//	      i += 1
+//	   """
+//	   Return from ``indices`` a random index sampled by effective balance.
+//	   """
+//	   assert len(indices) > 0
+//	   MAX_RANDOM_VALUE = 2**16 - 1  # [Modified in Electra]
+//	   i = uint64(0)
+//	   total = uint64(len(indices))
+//	   while True:
+//	       candidate_index = indices[compute_shuffled_index(i % total, total, seed)]
+//	       # [Modified in Electra]
+//	       random_bytes = hash(seed + uint_to_bytes(i // 16))
+//	       offset = i % 16 * 2
+//	       random_value = bytes_to_uint64(random_bytes[offset:offset + 2])
+//	       effective_balance = state.validators[candidate_index].effective_balance
+//	       # [Modified in Electra:EIP7251]
+//	       if effective_balance * MAX_RANDOM_VALUE >= MAX_EFFECTIVE_BALANCE_ELECTRA * random_value:
+//	           return candidate_index
+//	       i += 1
 func ComputeProposerIndex(bState state.ReadOnlyBeaconState, activeIndices []primitives.ValidatorIndex, seed [32]byte) (primitives.ValidatorIndex, error) {
 	length := uint64(len(activeIndices))
 	if length == 0 {
 		return 0, errors.New("empty active indices list")
 	}
-	maxRandomByte := uint64(1<<8 - 1)
 	hashFunc := hash.CustomSHA256Hasher()
+	beaconConfig := params.BeaconConfig()
+	seedBuffer := make([]byte, len(seed)+8)
+	copy(seedBuffer, seed[:])

 	for i := uint64(0); ; i++ {
 		candidateIndex, err := ComputeShuffledIndex(primitives.ValidatorIndex(i%length), length, seed, true /* shuffle */)
@@ -378,21 +386,28 @@ func ComputeProposerIndex(bState state.ReadOnlyBeaconState, activeIndices []prim
 		if uint64(candidateIndex) >= uint64(bState.NumValidators()) {
 			return 0, errors.New("active index out of range")
 		}
-		b := append(seed[:], bytesutil.Bytes8(i/32)...)
-		randomByte := hashFunc(b)[i%32]
+
 		v, err := bState.ValidatorAtIndexReadOnly(candidateIndex)
 		if err != nil {
 			return 0, err
 		}
 		effectiveBal := v.EffectiveBalance()
-
-		maxEB := params.BeaconConfig().MaxEffectiveBalance
 		if bState.Version() >= version.Electra {
-			maxEB = params.BeaconConfig().MaxEffectiveBalanceElectra
-		}
+			binary.LittleEndian.PutUint64(seedBuffer[len(seed):], i/16)
+			randomByte := hashFunc(seedBuffer)
+			offset := (i % 16) * 2
+			randomValue := uint64(randomByte[offset]) | uint64(randomByte[offset+1])<<8

-		if effectiveBal*maxRandomByte >= maxEB*uint64(randomByte) {
-			return candidateIndex, nil
+			if effectiveBal*fieldparams.MaxRandomValueElectra >= beaconConfig.MaxEffectiveBalanceElectra*randomValue {
+				return candidateIndex, nil
+			}
+		} else {
+			binary.LittleEndian.PutUint64(seedBuffer[len(seed):], i/32)
+			randomByte := hashFunc(seedBuffer)[i%32]
+
+			if effectiveBal*fieldparams.MaxRandomByte >= beaconConfig.MaxEffectiveBalance*uint64(randomByte) {
+				return candidateIndex, nil
+			}
 		}
 	}
 }
--- a/beacon-chain/core/helpers/validators_test.go
+++ b/beacon-chain/core/helpers/validators_test.go
@@ -841,7 +841,6 @@ func computeProposerIndexWithValidators(validators []*ethpb.Validator, activeInd
 	if length == 0 {
 		return 0, errors.New("empty active indices list")
 	}
-	maxRandomByte := uint64(1<<8 - 1)
 	hashFunc := hash.CustomSHA256Hasher()

 	for i := uint64(0); ; i++ {
@@ -860,7 +859,7 @@ func computeProposerIndexWithValidators(validators []*ethpb.Validator, activeInd
 		if v != nil {
 			effectiveBal = v.EffectiveBalance
 		}
-		if effectiveBal*maxRandomByte >= params.BeaconConfig().MaxEffectiveBalance*uint64(randomByte) {
+		if effectiveBal*fieldparams.MaxRandomByte >= params.BeaconConfig().MaxEffectiveBalance*uint64(randomByte) {
 			return candidateIndex, nil
 		}
 	}
--- a/beacon-chain/core/light-client/lightclient.go
+++ b/beacon-chain/core/light-client/lightclient.go
@@ -24,6 +24,8 @@ import (
 	"google.golang.org/protobuf/proto"
 )

+const ErrNotEnoughSyncCommitteeBits = "sync committee bits count is less than required"
+
 func NewLightClientFinalityUpdateFromBeaconState(
 	ctx context.Context,
 	currentSlot primitives.Slot,
@@ -84,7 +86,12 @@ func NewLightClientUpdateFromBeaconState(
 		return nil, errors.Wrap(err, "could not get sync aggregate")
 	}
 	if syncAggregate.SyncCommitteeBits.Count() < params.BeaconConfig().MinSyncCommitteeParticipants {
-		return nil, fmt.Errorf("invalid sync committee bits count %d", syncAggregate.SyncCommitteeBits.Count())
+		return nil, fmt.Errorf(
+			"%s (got %d, need %d)",
+			ErrNotEnoughSyncCommitteeBits,
+			syncAggregate.SyncCommitteeBits.Count(),
+			params.BeaconConfig().MinSyncCommitteeParticipants,
+		)
 	}

 	// assert state.slot == state.latest_block_header.slot
--- a/beacon-chain/core/light-client/lightclient_test.go
+++ b/beacon-chain/core/light-client/lightclient_test.go
@@ -697,7 +697,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 			excessBlobGas, err := payload.ExcessBlobGas()
 			require.NoError(t, err)

-			executionHeader := &v11.ExecutionPayloadHeaderElectra{
+			executionHeader := &v11.ExecutionPayloadHeaderDeneb{
 				ParentHash:       payload.ParentHash(),
 				FeeRecipient:     payload.FeeRecipient(),
 				StateRoot:        payload.StateRoot(),
@@ -762,7 +762,7 @@ func TestLightClient_BlockToLightClientHeader(t *testing.T) {
 			excessBlobGas, err := payload.ExcessBlobGas()
 			require.NoError(t, err)

-			executionHeader := &v11.ExecutionPayloadHeaderElectra{
+			executionHeader := &v11.ExecutionPayloadHeaderDeneb{
 				ParentHash:       payload.ParentHash(),
 				FeeRecipient:     payload.FeeRecipient(),
 				StateRoot:        payload.StateRoot(),
--- a/beacon-chain/core/time/slot_epoch.go
+++ b/beacon-chain/core/time/slot_epoch.go
@@ -99,6 +99,15 @@ func CanUpgradeToElectra(slot primitives.Slot) bool {
 	return epochStart && electraEpoch
 }

+// CanUpgradeToFulu returns true if the input `slot` can upgrade to Fulu.
+// Spec code:
+// If state.slot % SLOTS_PER_EPOCH == 0 and compute_epoch_at_slot(state.slot) == FULU_FORK_EPOCH
+func CanUpgradeToFulu(slot primitives.Slot) bool {
+	epochStart := slots.IsEpochStart(slot)
+	fuluEpoch := slots.ToEpoch(slot) == params.BeaconConfig().FuluForkEpoch
+	return epochStart && fuluEpoch
+}
+
 // CanProcessEpoch checks the eligibility to process epoch.
 // The epoch can be processed at the end of the last slot of every epoch.
 //
--- a/beacon-chain/core/time/slot_epoch_test.go
+++ b/beacon-chain/core/time/slot_epoch_test.go
@@ -1,6 +1,7 @@
 package time_test

 import (
+	"fmt"
 	"testing"

 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/time"
@@ -83,76 +84,6 @@ func TestNextEpoch_OK(t *testing.T) {
 	}
 }

-func TestCanUpgradeToAltair(t *testing.T) {
-	params.SetupTestConfigCleanup(t)
-	bc := params.BeaconConfig()
-	bc.AltairForkEpoch = 5
-	params.OverrideBeaconConfig(bc)
-	tests := []struct {
-		name string
-		slot primitives.Slot
-		want bool
-	}{
-		{
-			name: "not epoch start",
-			slot: 1,
-			want: false,
-		},
-		{
-			name: "not altair epoch",
-			slot: params.BeaconConfig().SlotsPerEpoch,
-			want: false,
-		},
-		{
-			name: "altair epoch",
-			slot: primitives.Slot(params.BeaconConfig().AltairForkEpoch) * params.BeaconConfig().SlotsPerEpoch,
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if got := time.CanUpgradeToAltair(tt.slot); got != tt.want {
-				t.Errorf("canUpgradeToAltair() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}
-
-func TestCanUpgradeBellatrix(t *testing.T) {
-	params.SetupTestConfigCleanup(t)
-	bc := params.BeaconConfig()
-	bc.BellatrixForkEpoch = 5
-	params.OverrideBeaconConfig(bc)
-	tests := []struct {
-		name string
-		slot primitives.Slot
-		want bool
-	}{
-		{
-			name: "not epoch start",
-			slot: 1,
-			want: false,
-		},
-		{
-			name: "not bellatrix epoch",
-			slot: params.BeaconConfig().SlotsPerEpoch,
-			want: false,
-		},
-		{
-			name: "bellatrix epoch",
-			slot: primitives.Slot(params.BeaconConfig().BellatrixForkEpoch) * params.BeaconConfig().SlotsPerEpoch,
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if got := time.CanUpgradeToBellatrix(tt.slot); got != tt.want {
-				t.Errorf("CanUpgradeToBellatrix() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}
-
 func TestCanProcessEpoch_TrueOnEpochsLastSlot(t *testing.T) {
 	tests := []struct {
 		slot            primitives.Slot
@@ -264,107 +195,79 @@ func TestAltairCompatible(t *testing.T) {
 	}
 }

-func TestCanUpgradeToCapella(t *testing.T) {
-	params.SetupTestConfigCleanup(t)
-	bc := params.BeaconConfig()
-	bc.CapellaForkEpoch = 5
-	params.OverrideBeaconConfig(bc)
-	tests := []struct {
-		name string
-		slot primitives.Slot
-		want bool
-	}{
-		{
-			name: "not epoch start",
-			slot: 1,
-			want: false,
-		},
-		{
-			name: "not capella epoch",
-			slot: params.BeaconConfig().SlotsPerEpoch,
-			want: false,
-		},
-		{
-			name: "capella epoch",
-			slot: primitives.Slot(params.BeaconConfig().CapellaForkEpoch) * params.BeaconConfig().SlotsPerEpoch,
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if got := time.CanUpgradeToCapella(tt.slot); got != tt.want {
-				t.Errorf("CanUpgradeToCapella() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}
+func TestCanUpgradeTo(t *testing.T) {
+	beaconConfig := params.BeaconConfig()

-func TestCanUpgradeToDeneb(t *testing.T) {
-	params.SetupTestConfigCleanup(t)
-	bc := params.BeaconConfig()
-	bc.DenebForkEpoch = 5
-	params.OverrideBeaconConfig(bc)
-	tests := []struct {
-		name string
-		slot primitives.Slot
-		want bool
+	outerTestCases := []struct {
+		name        string
+		forkEpoch   *primitives.Epoch
+		upgradeFunc func(primitives.Slot) bool
 	}{
 		{
-			name: "not epoch start",
-			slot: 1,
-			want: false,
+			name:        "Altair",
+			forkEpoch:   &beaconConfig.AltairForkEpoch,
+			upgradeFunc: time.CanUpgradeToAltair,
 		},
 		{
-			name: "not deneb epoch",
-			slot: params.BeaconConfig().SlotsPerEpoch,
-			want: false,
+			name:        "Bellatrix",
+			forkEpoch:   &beaconConfig.BellatrixForkEpoch,
+			upgradeFunc: time.CanUpgradeToBellatrix,
 		},
 		{
-			name: "deneb epoch",
-			slot: primitives.Slot(params.BeaconConfig().DenebForkEpoch) * params.BeaconConfig().SlotsPerEpoch,
-			want: true,
+			name:        "Capella",
+			forkEpoch:   &beaconConfig.CapellaForkEpoch,
+			upgradeFunc: time.CanUpgradeToCapella,
+		},
+		{
+			name:        "Deneb",
+			forkEpoch:   &beaconConfig.DenebForkEpoch,
+			upgradeFunc: time.CanUpgradeToDeneb,
+		},
+		{
+			name:        "Electra",
+			forkEpoch:   &beaconConfig.ElectraForkEpoch,
+			upgradeFunc: time.CanUpgradeToElectra,
+		},
+		{
+			name:        "Fulu",
+			forkEpoch:   &beaconConfig.FuluForkEpoch,
+			upgradeFunc: time.CanUpgradeToFulu,
 		},
 	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if got := time.CanUpgradeToDeneb(tt.slot); got != tt.want {
-				t.Errorf("CanUpgradeToDeneb() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}

-func TestCanUpgradeToElectra(t *testing.T) {
-	params.SetupTestConfigCleanup(t)
-	bc := params.BeaconConfig()
-	bc.ElectraForkEpoch = 5
-	params.OverrideBeaconConfig(bc)
-	tests := []struct {
-		name string
-		slot primitives.Slot
-		want bool
-	}{
-		{
-			name: "not epoch start",
-			slot: 1,
-			want: false,
-		},
-		{
-			name: "not electra epoch",
-			slot: params.BeaconConfig().SlotsPerEpoch,
-			want: false,
-		},
-		{
-			name: "electra epoch",
-			slot: primitives.Slot(params.BeaconConfig().ElectraForkEpoch) * params.BeaconConfig().SlotsPerEpoch,
-			want: true,
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if got := time.CanUpgradeToElectra(tt.slot); got != tt.want {
-				t.Errorf("CanUpgradeToElectra() = %v, want %v", got, tt.want)
-			}
-		})
+	for _, otc := range outerTestCases {
+		params.SetupTestConfigCleanup(t)
+		*otc.forkEpoch = 5
+		params.OverrideBeaconConfig(beaconConfig)
+
+		innerTestCases := []struct {
+			name string
+			slot primitives.Slot
+			want bool
+		}{
+			{
+				name: "not epoch start",
+				slot: 1,
+				want: false,
+			},
+			{
+				name: fmt.Sprintf("not %s epoch", otc.name),
+				slot: params.BeaconConfig().SlotsPerEpoch,
+				want: false,
+			},
+			{
+				name: fmt.Sprintf("%s epoch", otc.name),
+				slot: primitives.Slot(*otc.forkEpoch) * params.BeaconConfig().SlotsPerEpoch,
+				want: true,
+			},
+		}
+
+		for _, itc := range innerTestCases {
+			t.Run(fmt.Sprintf("%s-%s", otc.name, itc.name), func(t *testing.T) {
+				if got := otc.upgradeFunc(itc.slot); got != itc.want {
+					t.Errorf("CanUpgradeTo%s() = %v, want %v", otc.name, got, itc.want)
+				}
+			})
+		}
 	}
 }
--- a/beacon-chain/core/transition/BUILD.bazel
+++ b/beacon-chain/core/transition/BUILD.bazel
@@ -23,6 +23,7 @@ go_library(
        "//beacon-chain/core/epoch:go_default_library",
        "//beacon-chain/core/epoch/precompute:go_default_library",
        "//beacon-chain/core/execution:go_default_library",
+        "//beacon-chain/core/fulu:go_default_library",
        "//beacon-chain/core/helpers:go_default_library",
        "//beacon-chain/core/time:go_default_library",
        "//beacon-chain/core/transition/interop:go_default_library",
--- a/beacon-chain/core/transition/transition.go
+++ b/beacon-chain/core/transition/transition.go
@@ -17,6 +17,7 @@ import (
 	e "github.com/prysmaticlabs/prysm/v5/beacon-chain/core/epoch"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/epoch/precompute"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/execution"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/fulu"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/v5/config/features"
@@ -298,7 +299,7 @@ func ProcessSlotsCore(ctx context.Context, span trace.Span, state state.BeaconSt
 func ProcessEpoch(ctx context.Context, state state.BeaconState) (state.BeaconState, error) {
 	var err error
 	if time.CanProcessEpoch(state) {
-		if state.Version() == version.Electra {
+		if state.Version() >= version.Electra {
 			if err = electra.ProcessEpoch(ctx, state); err != nil {
 				return nil, errors.Wrap(err, fmt.Sprintf("could not process %s epoch", version.String(state.Version())))
 			}
@@ -322,9 +323,11 @@ func UpgradeState(ctx context.Context, state state.BeaconState) (state.BeaconSta
 	defer span.End()

 	var err error
+
+	slot := state.Slot()
 	upgraded := false

-	if time.CanUpgradeToAltair(state.Slot()) {
+	if time.CanUpgradeToAltair(slot) {
 		state, err = altair.UpgradeToAltair(ctx, state)
 		if err != nil {
 			tracing.AnnotateError(span, err)
@@ -333,7 +336,7 @@ func UpgradeState(ctx context.Context, state state.BeaconState) (state.BeaconSta
 		upgraded = true
 	}

-	if time.CanUpgradeToBellatrix(state.Slot()) {
+	if time.CanUpgradeToBellatrix(slot) {
 		state, err = execution.UpgradeToBellatrix(state)
 		if err != nil {
 			tracing.AnnotateError(span, err)
@@ -342,7 +345,7 @@ func UpgradeState(ctx context.Context, state state.BeaconState) (state.BeaconSta
 		upgraded = true
 	}

-	if time.CanUpgradeToCapella(state.Slot()) {
+	if time.CanUpgradeToCapella(slot) {
 		state, err = capella.UpgradeToCapella(state)
 		if err != nil {
 			tracing.AnnotateError(span, err)
@@ -351,7 +354,7 @@ func UpgradeState(ctx context.Context, state state.BeaconState) (state.BeaconSta
 		upgraded = true
 	}

-	if time.CanUpgradeToDeneb(state.Slot()) {
+	if time.CanUpgradeToDeneb(slot) {
 		state, err = deneb.UpgradeToDeneb(state)
 		if err != nil {
 			tracing.AnnotateError(span, err)
@@ -360,7 +363,7 @@ func UpgradeState(ctx context.Context, state state.BeaconState) (state.BeaconSta
 		upgraded = true
 	}

-	if time.CanUpgradeToElectra(state.Slot()) {
+	if time.CanUpgradeToElectra(slot) {
 		state, err = electra.UpgradeToElectra(state)
 		if err != nil {
 			tracing.AnnotateError(span, err)
@@ -369,8 +372,17 @@ func UpgradeState(ctx context.Context, state state.BeaconState) (state.BeaconSta
 		upgraded = true
 	}

+	if time.CanUpgradeToFulu(slot) {
+		state, err = fulu.UpgradeToFulu(state)
+		if err != nil {
+			tracing.AnnotateError(span, err)
+			return nil, err
+		}
+		upgraded = true
+	}
+
 	if upgraded {
-		log.Debugf("upgraded state to %s", version.String(state.Version()))
+		log.WithField("version", version.String(state.Version())).Info("Upgraded state to")
 	}

 	return state, nil
--- a/beacon-chain/core/transition/transition_test.go
+++ b/beacon-chain/core/transition/transition_test.go
@@ -665,6 +665,20 @@ func TestProcessSlots_ThroughElectraEpoch(t *testing.T) {
 	require.Equal(t, params.BeaconConfig().SlotsPerEpoch*10, st.Slot())
 }

+func TestProcessSlots_ThroughFuluEpoch(t *testing.T) {
+	transition.SkipSlotCache.Disable()
+	params.SetupTestConfigCleanup(t)
+	conf := params.BeaconConfig()
+	conf.FuluForkEpoch = 5
+	params.OverrideBeaconConfig(conf)
+
+	st, _ := util.DeterministicGenesisStateElectra(t, params.BeaconConfig().MaxValidatorsPerCommittee)
+	st, err := transition.ProcessSlots(context.Background(), st, params.BeaconConfig().SlotsPerEpoch*10)
+	require.NoError(t, err)
+	require.Equal(t, version.Fulu, st.Version())
+	require.Equal(t, params.BeaconConfig().SlotsPerEpoch*10, st.Slot())
+}
+
 func TestProcessSlotsUsingNextSlotCache(t *testing.T) {
 	s, _ := util.DeterministicGenesisState(t, 1)
 	r := []byte{'a'}
--- a/beacon-chain/core/validators/slashing.go
+++ b/beacon-chain/core/validators/slashing.go
@@ -9,25 +9,35 @@ import (
 // SlashingParamsPerVersion returns the slashing parameters for the given state version.
 func SlashingParamsPerVersion(v int) (slashingQuotient, proposerRewardQuotient, whistleblowerRewardQuotient uint64, err error) {
 	cfg := params.BeaconConfig()
-	switch v {
-	case version.Phase0:
-		slashingQuotient = cfg.MinSlashingPenaltyQuotient
-		proposerRewardQuotient = cfg.ProposerRewardQuotient
-		whistleblowerRewardQuotient = cfg.WhistleBlowerRewardQuotient
-	case version.Altair:
-		slashingQuotient = cfg.MinSlashingPenaltyQuotientAltair
-		proposerRewardQuotient = cfg.ProposerRewardQuotient
-		whistleblowerRewardQuotient = cfg.WhistleBlowerRewardQuotient
-	case version.Bellatrix, version.Capella, version.Deneb:
-		slashingQuotient = cfg.MinSlashingPenaltyQuotientBellatrix
-		proposerRewardQuotient = cfg.ProposerRewardQuotient
-		whistleblowerRewardQuotient = cfg.WhistleBlowerRewardQuotient
-	case version.Electra:
+
+	if v >= version.Electra {
 		slashingQuotient = cfg.MinSlashingPenaltyQuotientElectra
 		proposerRewardQuotient = cfg.ProposerRewardQuotient
 		whistleblowerRewardQuotient = cfg.WhistleBlowerRewardQuotientElectra
-	default:
-		err = errors.New("unknown state version")
+		return
 	}
+
+	if v >= version.Bellatrix {
+		slashingQuotient = cfg.MinSlashingPenaltyQuotientBellatrix
+		proposerRewardQuotient = cfg.ProposerRewardQuotient
+		whistleblowerRewardQuotient = cfg.WhistleBlowerRewardQuotient
+		return
+	}
+
+	if v >= version.Altair {
+		slashingQuotient = cfg.MinSlashingPenaltyQuotientAltair
+		proposerRewardQuotient = cfg.ProposerRewardQuotient
+		whistleblowerRewardQuotient = cfg.WhistleBlowerRewardQuotient
+		return
+	}
+
+	if v >= version.Phase0 {
+		slashingQuotient = cfg.MinSlashingPenaltyQuotient
+		proposerRewardQuotient = cfg.ProposerRewardQuotient
+		whistleblowerRewardQuotient = cfg.WhistleBlowerRewardQuotient
+		return
+	}
+
+	err = errors.Errorf("unknown state version %s", version.String(v))
 	return
 }
--- a/beacon-chain/core/validators/validator_test.go
+++ b/beacon-chain/core/validators/validator_test.go
@@ -217,6 +217,7 @@ func TestSlashValidator_OK(t *testing.T) {
 }

 func TestSlashValidator_Electra(t *testing.T) {
+	helpers.ClearCache()
 	validatorCount := 100
 	registry := make([]*ethpb.Validator, 0, validatorCount)
 	balances := make([]uint64, 0, validatorCount)
--- a/beacon-chain/db/kv/BUILD.bazel
+++ b/beacon-chain/db/kv/BUILD.bazel
@@ -41,6 +41,7 @@ go_library(
        "//beacon-chain/state/genesis:go_default_library",
        "//beacon-chain/state/state-native:go_default_library",
        "//config/features:go_default_library",
+        "//config/fieldparams:go_default_library",
        "//config/params:go_default_library",
        "//consensus-types/blocks:go_default_library",
        "//consensus-types/interfaces:go_default_library",
--- a/beacon-chain/db/kv/blocks.go
+++ b/beacon-chain/db/kv/blocks.go
@@ -823,6 +823,16 @@ func unmarshalBlock(_ context.Context, enc []byte) (interfaces.ReadOnlySignedBea
 		if err := rawBlock.UnmarshalSSZ(enc[len(electraBlindKey):]); err != nil {
 			return nil, errors.Wrap(err, "could not unmarshal blinded Electra block")
 		}
+	case hasFuluKey(enc):
+		rawBlock = &ethpb.SignedBeaconBlockFulu{}
+		if err := rawBlock.UnmarshalSSZ(enc[len(fuluKey):]); err != nil {
+			return nil, errors.Wrap(err, "could not unmarshal Fulu block")
+		}
+	case hasFuluBlindKey(enc):
+		rawBlock = &ethpb.SignedBlindedBeaconBlockFulu{}
+		if err := rawBlock.UnmarshalSSZ(enc[len(fuluBlindKey):]); err != nil {
+			return nil, errors.Wrap(err, "could not unmarshal blinded Fulu block")
+		}
 	default:
 		// Marshal block bytes to phase 0 beacon block.
 		rawBlock = &ethpb.SignedBeaconBlock{}
@@ -851,32 +861,50 @@ func encodeBlock(blk interfaces.ReadOnlySignedBeaconBlock) ([]byte, error) {
 }

 func keyForBlock(blk interfaces.ReadOnlySignedBeaconBlock) ([]byte, error) {
-	switch blk.Version() {
-	case version.Electra:
+	v := blk.Version()
+
+	if v >= version.Fulu {
+		if blk.IsBlinded() {
+			return fuluBlindKey, nil
+		}
+		return fuluKey, nil
+	}
+
+	if v >= version.Electra {
 		if blk.IsBlinded() {
 			return electraBlindKey, nil
 		}
 		return electraKey, nil
-	case version.Deneb:
+	}
+
+	if v >= version.Deneb {
 		if blk.IsBlinded() {
 			return denebBlindKey, nil
 		}
 		return denebKey, nil
-	case version.Capella:
+	}
+
+	if v >= version.Capella {
 		if blk.IsBlinded() {
 			return capellaBlindKey, nil
 		}
 		return capellaKey, nil
-	case version.Bellatrix:
+	}
+
+	if v >= version.Bellatrix {
 		if blk.IsBlinded() {
 			return bellatrixBlindKey, nil
 		}
 		return bellatrixKey, nil
-	case version.Altair:
-		return altairKey, nil
-	case version.Phase0:
-		return nil, nil
-	default:
-		return nil, fmt.Errorf("unsupported block version: %v", blk.Version())
 	}
+
+	if v >= version.Altair {
+		return altairKey, nil
+	}
+
+	if v >= version.Phase0 {
+		return nil, nil
+	}
+
+	return nil, fmt.Errorf("unsupported block version: %v", blk.Version())
 }
--- a/beacon-chain/db/kv/key.go
+++ b/beacon-chain/db/kv/key.go
@@ -65,3 +65,17 @@ func hasElectraBlindKey(enc []byte) bool {
 	}
 	return bytes.Equal(enc[:len(electraBlindKey)], electraBlindKey)
 }
+
+func hasFuluKey(enc []byte) bool {
+	if len(fuluKey) >= len(enc) {
+		return false
+	}
+	return bytes.Equal(enc[:len(fuluKey)], fuluKey)
+}
+
+func hasFuluBlindKey(enc []byte) bool {
+	if len(fuluBlindKey) >= len(enc) {
+		return false
+	}
+	return bytes.Equal(enc[:len(fuluBlindKey)], fuluBlindKey)
+}
--- a/beacon-chain/db/kv/kv.go
+++ b/beacon-chain/db/kv/kv.go
@@ -109,6 +109,7 @@ var Buckets = [][]byte{
 	stateValidatorsBucket,
 	lightClientUpdatesBucket,
 	lightClientBootstrapBucket,
+	lightClientSyncCommitteeBucket,
 	// Indices buckets.
 	blockSlotIndicesBucket,
 	stateSlotIndicesBucket,
--- a/beacon-chain/db/kv/lightclient.go
+++ b/beacon-chain/db/kv/lightclient.go
@@ -7,6 +7,8 @@ import (

 	"github.com/golang/snappy"
 	"github.com/pkg/errors"
+	fieldparams "github.com/prysmaticlabs/prysm/v5/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/interfaces"
 	light_client "github.com/prysmaticlabs/prysm/v5/consensus-types/light-client"
 	"github.com/prysmaticlabs/prysm/v5/encoding/bytesutil"
@@ -35,9 +37,35 @@ func (s *Store) SaveLightClientBootstrap(ctx context.Context, blockRoot []byte,
 	_, span := trace.StartSpan(ctx, "BeaconDB.SaveLightClientBootstrap")
 	defer span.End()

+	bootstrapCopy, err := light_client.NewWrappedBootstrap(proto.Clone(bootstrap.Proto()))
+	if err != nil {
+		return errors.Wrap(err, "could not clone light client bootstrap")
+	}
+	syncCommitteeHash, err := bootstrapCopy.CurrentSyncCommittee().HashTreeRoot()
+	if err != nil {
+		return errors.Wrap(err, "could not hash current sync committee")
+	}
+
 	return s.db.Update(func(tx *bolt.Tx) error {
+		syncCommitteeBucket := tx.Bucket(lightClientSyncCommitteeBucket)
+		syncCommitteeAlreadyExists := syncCommitteeBucket.Get(syncCommitteeHash[:]) != nil
+		if !syncCommitteeAlreadyExists {
+			enc, err := bootstrapCopy.CurrentSyncCommittee().MarshalSSZ()
+			if err != nil {
+				return errors.Wrap(err, "could not marshal current sync committee")
+			}
+			if err := syncCommitteeBucket.Put(syncCommitteeHash[:], enc); err != nil {
+				return errors.Wrap(err, "could not save current sync committee")
+			}
+		}
+
+		err = bootstrapCopy.SetCurrentSyncCommittee(createEmptySyncCommittee())
+		if err != nil {
+			return errors.Wrap(err, "could not set current sync committee to zero while saving")
+		}
+
 		bkt := tx.Bucket(lightClientBootstrapBucket)
-		enc, err := encodeLightClientBootstrap(bootstrap)
+		enc, err := encodeLightClientBootstrap(bootstrapCopy, syncCommitteeHash)
 		if err != nil {
 			return err
 		}
@@ -50,20 +78,49 @@ func (s *Store) LightClientBootstrap(ctx context.Context, blockRoot []byte) (int
 	defer span.End()

 	var bootstrap interfaces.LightClientBootstrap
+	var syncCommitteeHash []byte
 	err := s.db.View(func(tx *bolt.Tx) error {
 		bkt := tx.Bucket(lightClientBootstrapBucket)
+		syncCommitteeBucket := tx.Bucket(lightClientSyncCommitteeBucket)
 		enc := bkt.Get(blockRoot)
 		if enc == nil {
 			return nil
 		}
 		var err error
-		bootstrap, err = decodeLightClientBootstrap(enc)
+		bootstrap, syncCommitteeHash, err = decodeLightClientBootstrap(enc)
+		if err != nil {
+			return errors.Wrap(err, "could not decode light client bootstrap")
+		}
+		var syncCommitteeBytes = syncCommitteeBucket.Get(syncCommitteeHash)
+		if syncCommitteeBytes == nil {
+			return errors.New("sync committee not found")
+		}
+		syncCommittee := &ethpb.SyncCommittee{}
+		if err := syncCommittee.UnmarshalSSZ(syncCommitteeBytes); err != nil {
+			return errors.Wrap(err, "could not unmarshal sync committee")
+		}
+		err = bootstrap.SetCurrentSyncCommittee(syncCommittee)
+		if err != nil {
+			return errors.Wrap(err, "could not set current sync committee while retrieving")
+		}
 		return err
 	})
 	return bootstrap, err
 }

-func encodeLightClientBootstrap(bootstrap interfaces.LightClientBootstrap) ([]byte, error) {
+func createEmptySyncCommittee() *ethpb.SyncCommittee {
+	syncCom := make([][]byte, params.BeaconConfig().SyncCommitteeSize)
+	for i := 0; uint64(i) < params.BeaconConfig().SyncCommitteeSize; i++ {
+		syncCom[i] = make([]byte, fieldparams.BLSPubkeyLength)
+	}
+
+	return &ethpb.SyncCommittee{
+		Pubkeys:         syncCom,
+		AggregatePubkey: make([]byte, fieldparams.BLSPubkeyLength),
+	}
+}
+
+func encodeLightClientBootstrap(bootstrap interfaces.LightClientBootstrap, syncCommitteeHash [32]byte) ([]byte, error) {
 	key, err := keyForLightClientUpdate(bootstrap.Version())
 	if err != nil {
 		return nil, err
@@ -72,48 +129,56 @@ func encodeLightClientBootstrap(bootstrap interfaces.LightClientBootstrap) ([]by
 	if err != nil {
 		return nil, errors.Wrap(err, "could not marshal light client bootstrap")
 	}
-	fullEnc := make([]byte, len(key)+len(enc))
+	fullEnc := make([]byte, len(key)+32+len(enc))
 	copy(fullEnc, key)
-	copy(fullEnc[len(key):], enc)
-	return snappy.Encode(nil, fullEnc), nil
+	copy(fullEnc[len(key):len(key)+32], syncCommitteeHash[:])
+	copy(fullEnc[len(key)+32:], enc)
+	compressedEnc := snappy.Encode(nil, fullEnc)
+	return compressedEnc, nil
 }

-func decodeLightClientBootstrap(enc []byte) (interfaces.LightClientBootstrap, error) {
+func decodeLightClientBootstrap(enc []byte) (interfaces.LightClientBootstrap, []byte, error) {
 	var err error
 	enc, err = snappy.Decode(nil, enc)
 	if err != nil {
-		return nil, errors.Wrap(err, "could not snappy decode light client bootstrap")
+		return nil, nil, errors.Wrap(err, "could not snappy decode light client bootstrap")
 	}
 	var m proto.Message
+	var syncCommitteeHash []byte
 	switch {
 	case hasAltairKey(enc):
 		bootstrap := &ethpb.LightClientBootstrapAltair{}
-		if err := bootstrap.UnmarshalSSZ(enc[len(altairKey):]); err != nil {
-			return nil, errors.Wrap(err, "could not unmarshal Altair light client bootstrap")
+		if err := bootstrap.UnmarshalSSZ(enc[len(altairKey)+32:]); err != nil {
+			return nil, nil, errors.Wrap(err, "could not unmarshal Altair light client bootstrap")
 		}
 		m = bootstrap
+		syncCommitteeHash = enc[len(altairKey) : len(altairKey)+32]
 	case hasCapellaKey(enc):
 		bootstrap := &ethpb.LightClientBootstrapCapella{}
-		if err := bootstrap.UnmarshalSSZ(enc[len(capellaKey):]); err != nil {
-			return nil, errors.Wrap(err, "could not unmarshal Capella light client bootstrap")
+		if err := bootstrap.UnmarshalSSZ(enc[len(capellaKey)+32:]); err != nil {
+			return nil, nil, errors.Wrap(err, "could not unmarshal Capella light client bootstrap")
 		}
 		m = bootstrap
+		syncCommitteeHash = enc[len(capellaKey) : len(capellaKey)+32]
 	case hasDenebKey(enc):
 		bootstrap := &ethpb.LightClientBootstrapDeneb{}
-		if err := bootstrap.UnmarshalSSZ(enc[len(denebKey):]); err != nil {
-			return nil, errors.Wrap(err, "could not unmarshal Deneb light client bootstrap")
+		if err := bootstrap.UnmarshalSSZ(enc[len(denebKey)+32:]); err != nil {
+			return nil, nil, errors.Wrap(err, "could not unmarshal Deneb light client bootstrap")
 		}
 		m = bootstrap
+		syncCommitteeHash = enc[len(denebKey) : len(denebKey)+32]
 	case hasElectraKey(enc):
 		bootstrap := &ethpb.LightClientBootstrapElectra{}
-		if err := bootstrap.UnmarshalSSZ(enc[len(electraKey):]); err != nil {
-			return nil, errors.Wrap(err, "could not unmarshal Electra light client bootstrap")
+		if err := bootstrap.UnmarshalSSZ(enc[len(electraKey)+32:]); err != nil {
+			return nil, nil, errors.Wrap(err, "could not unmarshal Electra light client bootstrap")
 		}
 		m = bootstrap
+		syncCommitteeHash = enc[len(electraKey) : len(electraKey)+32]
 	default:
-		return nil, errors.New("decoding of saved light client bootstrap is unsupported")
+		return nil, nil, errors.New("decoding of saved light client bootstrap is unsupported")
 	}
-	return light_client.NewWrappedBootstrap(m)
+	bootstrap, err := light_client.NewWrappedBootstrap(m)
+	return bootstrap, syncCommitteeHash, err
 }

 func (s *Store) LightClientUpdates(ctx context.Context, startPeriod, endPeriod uint64) (map[uint64]interfaces.LightClientUpdate, error) {
--- a/beacon-chain/db/kv/lightclient_test.go
+++ b/beacon-chain/db/kv/lightclient_test.go
@@ -18,6 +18,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/testing/require"
 	"github.com/prysmaticlabs/prysm/v5/testing/util"
 	"github.com/prysmaticlabs/prysm/v5/time/slots"
+	bolt "go.etcd.io/bbolt"
 	"google.golang.org/protobuf/proto"
 )

@@ -122,7 +123,7 @@ func createUpdate(t *testing.T, v int) (interfaces.LightClientUpdate, error) {
 				StateRoot:     sampleRoot,
 				BodyRoot:      sampleRoot,
 			},
-			Execution: &enginev1.ExecutionPayloadHeaderElectra{
+			Execution: &enginev1.ExecutionPayloadHeaderDeneb{
 				ParentHash:       make([]byte, fieldparams.RootLength),
 				FeeRecipient:     make([]byte, fieldparams.FeeRecipientLength),
 				StateRoot:        make([]byte, fieldparams.RootLength),
@@ -140,6 +141,34 @@ func createUpdate(t *testing.T, v int) (interfaces.LightClientUpdate, error) {
 		require.NoError(t, err)
 		st, err = util.NewBeaconStateElectra()
 		require.NoError(t, err)
+	case version.Fulu:
+		slot = primitives.Slot(config.FuluForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+		header, err = light_client.NewWrappedHeader(&pb.LightClientHeaderDeneb{
+			Beacon: &pb.BeaconBlockHeader{
+				Slot:          1,
+				ProposerIndex: primitives.ValidatorIndex(rand.Int()),
+				ParentRoot:    sampleRoot,
+				StateRoot:     sampleRoot,
+				BodyRoot:      sampleRoot,
+			},
+			Execution: &enginev1.ExecutionPayloadHeaderDeneb{
+				ParentHash:       make([]byte, fieldparams.RootLength),
+				FeeRecipient:     make([]byte, fieldparams.FeeRecipientLength),
+				StateRoot:        make([]byte, fieldparams.RootLength),
+				ReceiptsRoot:     make([]byte, fieldparams.RootLength),
+				LogsBloom:        make([]byte, fieldparams.LogsBloomLength),
+				PrevRandao:       make([]byte, fieldparams.RootLength),
+				ExtraData:        make([]byte, 0),
+				BaseFeePerGas:    make([]byte, fieldparams.RootLength),
+				BlockHash:        make([]byte, fieldparams.RootLength),
+				TransactionsRoot: make([]byte, fieldparams.RootLength),
+				WithdrawalsRoot:  make([]byte, fieldparams.RootLength),
+			},
+			ExecutionBranch: sampleExecutionBranch,
+		})
+		require.NoError(t, err)
+		st, err = util.NewBeaconStateFulu()
+		require.NoError(t, err)
 	default:
 		return nil, fmt.Errorf("unsupported version %s", version.String(v))
 	}
@@ -167,6 +196,7 @@ func TestStore_LightClientUpdate_CanSaveRetrieve(t *testing.T) {
 	cfg.CapellaForkEpoch = 1
 	cfg.DenebForkEpoch = 2
 	cfg.ElectraForkEpoch = 3
+	cfg.FuluForkEpoch = 3
 	params.OverrideBeaconConfig(cfg)

 	db := setupDB(t)
@@ -213,6 +243,17 @@ func TestStore_LightClientUpdate_CanSaveRetrieve(t *testing.T) {
 		err = db.SaveLightClientUpdate(ctx, period, update)
 		require.NoError(t, err)

+		retrievedUpdate, err := db.LightClientUpdate(ctx, period)
+		require.NoError(t, err)
+		require.DeepEqual(t, update, retrievedUpdate, "retrieved update does not match saved update")
+	})
+	t.Run("Fulu", func(t *testing.T) {
+		update, err := createUpdate(t, version.Fulu)
+		require.NoError(t, err)
+		period := uint64(1)
+		err = db.SaveLightClientUpdate(ctx, period, update)
+		require.NoError(t, err)
+
 		retrievedUpdate, err := db.LightClientUpdate(ctx, period)
 		require.NoError(t, err)
 		require.DeepEqual(t, update, retrievedUpdate, "retrieved update does not match saved update")
@@ -571,7 +612,13 @@ func TestStore_LightClientBootstrap_CanSaveRetrieve(t *testing.T) {

 		retrievedBootstrap, err := db.LightClientBootstrap(ctx, []byte("blockRootAltair"))
 		require.NoError(t, err)
-		require.DeepEqual(t, bootstrap, retrievedBootstrap, "retrieved bootstrap does not match saved bootstrap")
+		require.DeepEqual(t, bootstrap.Header(), retrievedBootstrap.Header(), "retrieved bootstrap header does not match saved bootstrap header")
+		require.DeepEqual(t, bootstrap.CurrentSyncCommittee(), retrievedBootstrap.CurrentSyncCommittee(), "retrieved bootstrap sync committee does not match saved bootstrap sync committee")
+		savedBranch, err := bootstrap.CurrentSyncCommitteeBranch()
+		require.NoError(t, err)
+		retrievedBranch, err := retrievedBootstrap.CurrentSyncCommitteeBranch()
+		require.NoError(t, err)
+		require.DeepEqual(t, savedBranch, retrievedBranch, "retrieved bootstrap sync committee branch does not match saved bootstrap sync committee branch")
 	})

 	t.Run("Capella", func(t *testing.T) {
@@ -586,7 +633,13 @@ func TestStore_LightClientBootstrap_CanSaveRetrieve(t *testing.T) {

 		retrievedBootstrap, err := db.LightClientBootstrap(ctx, []byte("blockRootCapella"))
 		require.NoError(t, err)
-		require.DeepEqual(t, bootstrap, retrievedBootstrap, "retrieved bootstrap does not match saved bootstrap")
+		require.DeepEqual(t, bootstrap.Header(), retrievedBootstrap.Header(), "retrieved bootstrap header does not match saved bootstrap header")
+		require.DeepEqual(t, bootstrap.CurrentSyncCommittee(), retrievedBootstrap.CurrentSyncCommittee(), "retrieved bootstrap sync committee does not match saved bootstrap sync committee")
+		savedBranch, err := bootstrap.CurrentSyncCommitteeBranch()
+		require.NoError(t, err)
+		retrievedBranch, err := retrievedBootstrap.CurrentSyncCommitteeBranch()
+		require.NoError(t, err)
+		require.DeepEqual(t, savedBranch, retrievedBranch, "retrieved bootstrap sync committee branch does not match saved bootstrap sync committee branch")
 	})

 	t.Run("Deneb", func(t *testing.T) {
@@ -601,7 +654,13 @@ func TestStore_LightClientBootstrap_CanSaveRetrieve(t *testing.T) {

 		retrievedBootstrap, err := db.LightClientBootstrap(ctx, []byte("blockRootDeneb"))
 		require.NoError(t, err)
-		require.DeepEqual(t, bootstrap, retrievedBootstrap, "retrieved bootstrap does not match saved bootstrap")
+		require.DeepEqual(t, bootstrap.Header(), retrievedBootstrap.Header(), "retrieved bootstrap header does not match saved bootstrap header")
+		require.DeepEqual(t, bootstrap.CurrentSyncCommittee(), retrievedBootstrap.CurrentSyncCommittee(), "retrieved bootstrap sync committee does not match saved bootstrap sync committee")
+		savedBranch, err := bootstrap.CurrentSyncCommitteeBranch()
+		require.NoError(t, err)
+		retrievedBranch, err := retrievedBootstrap.CurrentSyncCommitteeBranch()
+		require.NoError(t, err)
+		require.DeepEqual(t, savedBranch, retrievedBranch, "retrieved bootstrap sync committee branch does not match saved bootstrap sync committee branch")
 	})

 	t.Run("Electra", func(t *testing.T) {
@@ -616,10 +675,138 @@ func TestStore_LightClientBootstrap_CanSaveRetrieve(t *testing.T) {

 		retrievedBootstrap, err := db.LightClientBootstrap(ctx, []byte("blockRootElectra"))
 		require.NoError(t, err)
-		require.DeepEqual(t, bootstrap, retrievedBootstrap, "retrieved bootstrap does not match saved bootstrap")
+		require.DeepEqual(t, bootstrap.Header(), retrievedBootstrap.Header(), "retrieved bootstrap header does not match saved bootstrap header")
+		require.DeepEqual(t, bootstrap.CurrentSyncCommittee(), retrievedBootstrap.CurrentSyncCommittee(), "retrieved bootstrap sync committee does not match saved bootstrap sync committee")
+		savedBranch, err := bootstrap.CurrentSyncCommitteeBranchElectra()
+		require.NoError(t, err)
+		retrievedBranch, err := retrievedBootstrap.CurrentSyncCommitteeBranchElectra()
+		require.NoError(t, err)
+		require.DeepEqual(t, savedBranch, retrievedBranch, "retrieved bootstrap sync committee branch does not match saved bootstrap sync committee branch")
 	})
 }

+func TestStore_LightClientBootstrap_MultipleBootstrapsWithSameSyncCommittee(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig()
+	cfg.AltairForkEpoch = 0
+	cfg.CapellaForkEpoch = 1
+	cfg.DenebForkEpoch = 2
+	cfg.ElectraForkEpoch = 3
+	cfg.EpochsPerSyncCommitteePeriod = 1
+	params.OverrideBeaconConfig(cfg)
+
+	db := setupDB(t)
+	ctx := context.Background()
+
+	bootstrap1, err := createDefaultLightClientBootstrap(primitives.Slot(uint64(params.BeaconConfig().AltairForkEpoch) * uint64(params.BeaconConfig().SlotsPerEpoch)))
+	require.NoError(t, err)
+	bootstrap2, err := createDefaultLightClientBootstrap(primitives.Slot(uint64(params.BeaconConfig().AltairForkEpoch) * uint64(params.BeaconConfig().SlotsPerEpoch)))
+	require.NoError(t, err)
+
+	randomSyncCommittee := createRandomSyncCommittee()
+
+	err = bootstrap1.SetCurrentSyncCommittee(randomSyncCommittee)
+	require.NoError(t, err)
+	err = bootstrap2.SetCurrentSyncCommittee(randomSyncCommittee)
+	require.NoError(t, err)
+
+	err = db.SaveLightClientBootstrap(ctx, []byte("blockRootAltair1"), bootstrap1)
+	require.NoError(t, err)
+	err = db.SaveLightClientBootstrap(ctx, []byte("blockRootAltair2"), bootstrap2)
+	require.NoError(t, err)
+
+	retrievedBootstrap1, err := db.LightClientBootstrap(ctx, []byte("blockRootAltair1"))
+	require.NoError(t, err)
+	retrievedBootstrap2, err := db.LightClientBootstrap(ctx, []byte("blockRootAltair2"))
+	require.NoError(t, err)
+
+	require.DeepEqual(t, bootstrap1.Header(), retrievedBootstrap1.Header(), "retrieved bootstrap1 header does not match saved bootstrap1 header")
+	require.DeepEqual(t, randomSyncCommittee, retrievedBootstrap1.CurrentSyncCommittee(), "retrieved bootstrap1 sync committee does not match saved bootstrap1 sync committee")
+	savedBranch, err := bootstrap1.CurrentSyncCommitteeBranch()
+	require.NoError(t, err)
+	retrievedBranch, err := retrievedBootstrap1.CurrentSyncCommitteeBranch()
+	require.NoError(t, err)
+	require.DeepEqual(t, savedBranch, retrievedBranch, "retrieved bootstrap1 sync committee branch does not match saved bootstrap1 sync committee branch")
+
+	require.DeepEqual(t, bootstrap2.Header(), retrievedBootstrap2.Header(), "retrieved bootstrap1 header does not match saved bootstrap1 header")
+	require.DeepEqual(t, randomSyncCommittee, retrievedBootstrap2.CurrentSyncCommittee(), "retrieved bootstrap1 sync committee does not match saved bootstrap1 sync committee")
+	savedBranch2, err := bootstrap2.CurrentSyncCommitteeBranch()
+	require.NoError(t, err)
+	retrievedBranch2, err := retrievedBootstrap2.CurrentSyncCommitteeBranch()
+	require.NoError(t, err)
+	require.DeepEqual(t, savedBranch2, retrievedBranch2, "retrieved bootstrap1 sync committee branch does not match saved bootstrap1 sync committee branch")
+
+	// Ensure that the sync committee is only stored once
+	err = db.db.View(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket(lightClientSyncCommitteeBucket)
+		require.NotNil(t, bucket)
+		count := bucket.Stats().KeyN
+		require.Equal(t, 1, count)
+		return nil
+	})
+	require.NoError(t, err)
+}
+
+func TestStore_LightClientBootstrap_MultipleBootstrapsWithDifferentSyncCommittees(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig()
+	cfg.AltairForkEpoch = 0
+	cfg.CapellaForkEpoch = 1
+	cfg.DenebForkEpoch = 2
+	cfg.ElectraForkEpoch = 3
+	cfg.EpochsPerSyncCommitteePeriod = 1
+	params.OverrideBeaconConfig(cfg)
+
+	db := setupDB(t)
+	ctx := context.Background()
+
+	bootstrap1, err := createDefaultLightClientBootstrap(primitives.Slot(uint64(params.BeaconConfig().AltairForkEpoch) * uint64(params.BeaconConfig().SlotsPerEpoch)))
+	require.NoError(t, err)
+	bootstrap2, err := createDefaultLightClientBootstrap(primitives.Slot(uint64(params.BeaconConfig().AltairForkEpoch) * uint64(params.BeaconConfig().SlotsPerEpoch)))
+	require.NoError(t, err)
+
+	err = bootstrap1.SetCurrentSyncCommittee(createRandomSyncCommittee())
+	require.NoError(t, err)
+	err = bootstrap2.SetCurrentSyncCommittee(createRandomSyncCommittee())
+	require.NoError(t, err)
+
+	err = db.SaveLightClientBootstrap(ctx, []byte("blockRootAltair1"), bootstrap1)
+	require.NoError(t, err)
+	err = db.SaveLightClientBootstrap(ctx, []byte("blockRootAltair2"), bootstrap2)
+	require.NoError(t, err)
+
+	retrievedBootstrap1, err := db.LightClientBootstrap(ctx, []byte("blockRootAltair1"))
+	require.NoError(t, err)
+	retrievedBootstrap2, err := db.LightClientBootstrap(ctx, []byte("blockRootAltair2"))
+	require.NoError(t, err)
+
+	require.DeepEqual(t, bootstrap1.Header(), retrievedBootstrap1.Header(), "retrieved bootstrap1 header does not match saved bootstrap1 header")
+	require.DeepEqual(t, bootstrap1.CurrentSyncCommittee(), retrievedBootstrap1.CurrentSyncCommittee(), "retrieved bootstrap1 sync committee does not match saved bootstrap1 sync committee")
+	savedBranch, err := bootstrap1.CurrentSyncCommitteeBranch()
+	require.NoError(t, err)
+	retrievedBranch, err := retrievedBootstrap1.CurrentSyncCommitteeBranch()
+	require.NoError(t, err)
+	require.DeepEqual(t, savedBranch, retrievedBranch, "retrieved bootstrap1 sync committee branch does not match saved bootstrap1 sync committee branch")
+
+	require.DeepEqual(t, bootstrap2.Header(), retrievedBootstrap2.Header(), "retrieved bootstrap1 header does not match saved bootstrap1 header")
+	require.DeepEqual(t, bootstrap2.CurrentSyncCommittee(), retrievedBootstrap2.CurrentSyncCommittee(), "retrieved bootstrap1 sync committee does not match saved bootstrap1 sync committee")
+	savedBranch2, err := bootstrap2.CurrentSyncCommitteeBranch()
+	require.NoError(t, err)
+	retrievedBranch2, err := retrievedBootstrap2.CurrentSyncCommitteeBranch()
+	require.NoError(t, err)
+	require.DeepEqual(t, savedBranch2, retrievedBranch2, "retrieved bootstrap1 sync committee branch does not match saved bootstrap1 sync committee branch")
+
+	// Ensure that the sync committee is stored twice
+	err = db.db.View(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket(lightClientSyncCommitteeBucket)
+		require.NotNil(t, bucket)
+		count := bucket.Stats().KeyN
+		require.Equal(t, 2, count)
+		return nil
+	})
+	require.NoError(t, err)
+}
+
 func createDefaultLightClientBootstrap(currentSlot primitives.Slot) (interfaces.LightClientBootstrap, error) {
 	currentEpoch := slots.ToEpoch(currentSlot)
 	syncCommitteeSize := params.BeaconConfig().SyncCommitteeSize
--- a/beacon-chain/db/kv/schema.go
+++ b/beacon-chain/db/kv/schema.go
@@ -18,8 +18,9 @@ var (
 	registrationBucket    = []byte("registration")

 	// Light Client Updates Bucket
-	lightClientUpdatesBucket   = []byte("light-client-updates")
-	lightClientBootstrapBucket = []byte("light-client-bootstrap")
+	lightClientUpdatesBucket       = []byte("light-client-updates")
+	lightClientBootstrapBucket     = []byte("light-client-bootstrap")
+	lightClientSyncCommitteeBucket = []byte("light-client-sync-committee")

 	// Deprecated: This bucket was migrated in PR 6461. Do not use, except for migrations.
 	slotsHasObjectBucket = []byte("slots-has-objects")
@@ -54,6 +55,8 @@ var (
 	denebBlindKey              = []byte("blind-deneb")
 	electraKey                 = []byte("electra")
 	electraBlindKey            = []byte("blind-electra")
+	fuluKey                    = []byte("fulu")
+	fuluBlindKey               = []byte("blind-fulu")

 	// block root included in the beacon state used by weak subjectivity initial sync
 	originCheckpointBlockRootKey = []byte("origin-checkpoint-block-root")
--- a/beacon-chain/db/kv/state.go
+++ b/beacon-chain/db/kv/state.go
@@ -517,6 +517,19 @@ func (s *Store) unmarshalState(_ context.Context, enc []byte, validatorEntries [
 	}

 	switch {
+	case hasFuluKey(enc):
+		protoState := &ethpb.BeaconStateFulu{}
+		if err := protoState.UnmarshalSSZ(enc[len(fuluKey):]); err != nil {
+			return nil, errors.Wrap(err, "failed to unmarshal encoding for Electra")
+		}
+		ok, err := s.isStateValidatorMigrationOver()
+		if err != nil {
+			return nil, err
+		}
+		if ok {
+			protoState.Validators = validatorEntries
+		}
+		return statenative.InitializeFromProtoUnsafeFulu(protoState)
 	case hasElectraKey(enc):
 		protoState := &ethpb.BeaconStateElectra{}
 		if err := protoState.UnmarshalSSZ(enc[len(electraKey):]); err != nil {
@@ -676,6 +689,19 @@ func marshalState(ctx context.Context, st state.ReadOnlyBeaconState) ([]byte, er
 			return nil, err
 		}
 		return snappy.Encode(nil, append(electraKey, rawObj...)), nil
+	case version.Fulu:
+		rState, ok := st.ToProtoUnsafe().(*ethpb.BeaconStateFulu)
+		if !ok {
+			return nil, errors.New("non valid inner state")
+		}
+		if rState == nil {
+			return nil, errors.New("nil state")
+		}
+		rawObj, err := rState.MarshalSSZ()
+		if err != nil {
+			return nil, err
+		}
+		return snappy.Encode(nil, append(fuluKey, rawObj...)), nil
 	default:
 		return nil, errors.New("invalid inner state")
 	}
--- a/beacon-chain/db/kv/state_test.go
+++ b/beacon-chain/db/kv/state_test.go
@@ -2,8 +2,10 @@ package kv

 import (
 	"context"
+	"crypto/rand"
 	"encoding/binary"
-	"math/rand"
+	mathRand "math/rand"
+
 	"strconv"
 	"testing"
 	"time"
@@ -137,7 +139,7 @@ func TestState_CanSaveRetrieve(t *testing.T) {
 				st, err := util.NewBeaconStateElectra()
 				require.NoError(t, err)
 				require.NoError(t, st.SetSlot(100))
-				p, err := blocks.WrappedExecutionPayloadHeaderElectra(&enginev1.ExecutionPayloadHeaderElectra{
+				p, err := blocks.WrappedExecutionPayloadHeaderDeneb(&enginev1.ExecutionPayloadHeaderDeneb{
 					ParentHash:       make([]byte, 32),
 					FeeRecipient:     make([]byte, 20),
 					StateRoot:        make([]byte, 32),
@@ -878,16 +880,16 @@ func validators(limit int) []*ethpb.Validator {
 	var vals []*ethpb.Validator
 	for i := 0; i < limit; i++ {
 		pubKey := make([]byte, params.BeaconConfig().BLSPubkeyLength)
-		binary.LittleEndian.PutUint64(pubKey, rand.Uint64())
+		binary.LittleEndian.PutUint64(pubKey, mathRand.Uint64())
 		val := &ethpb.Validator{
 			PublicKey:                  pubKey,
-			WithdrawalCredentials:      bytesutil.ToBytes(rand.Uint64(), 32),
-			EffectiveBalance:           rand.Uint64(),
+			WithdrawalCredentials:      bytesutil.ToBytes(mathRand.Uint64(), 32),
+			EffectiveBalance:           mathRand.Uint64(),
 			Slashed:                    i%2 != 0,
-			ActivationEligibilityEpoch: primitives.Epoch(rand.Uint64()),
-			ActivationEpoch:            primitives.Epoch(rand.Uint64()),
-			ExitEpoch:                  primitives.Epoch(rand.Uint64()),
-			WithdrawableEpoch:          primitives.Epoch(rand.Uint64()),
+			ActivationEligibilityEpoch: primitives.Epoch(mathRand.Uint64()),
+			ActivationEpoch:            primitives.Epoch(mathRand.Uint64()),
+			ExitEpoch:                  primitives.Epoch(mathRand.Uint64()),
+			WithdrawableEpoch:          primitives.Epoch(mathRand.Uint64()),
 		}
 		vals = append(vals, val)
 	}
@@ -913,8 +915,8 @@ func checkStateSaveTime(b *testing.B, saveCount int) {
 		allValidators := append(initialSetOfValidators, validatosToAddInTest...)

 		// shuffle validators.
-		rand.Seed(time.Now().UnixNano())
-		rand.Shuffle(len(allValidators), func(i, j int) { allValidators[i], allValidators[j] = allValidators[j], allValidators[i] })
+		mathRand.New(mathRand.NewSource(time.Now().UnixNano()))
+		mathRand.Shuffle(len(allValidators), func(i, j int) { allValidators[i], allValidators[j] = allValidators[j], allValidators[i] })

 		require.NoError(b, st.SetValidators(allValidators))
 		require.NoError(b, db.SaveState(context.Background(), st, bytesutil.ToBytes32(key)))
@@ -959,8 +961,8 @@ func checkStateReadTime(b *testing.B, saveCount int) {
 		allValidators := append(initialSetOfValidators, validatosToAddInTest...)

 		// shuffle validators.
-		rand.Seed(time.Now().UnixNano())
-		rand.Shuffle(len(allValidators), func(i, j int) { allValidators[i], allValidators[j] = allValidators[j], allValidators[i] })
+		mathRand.New(mathRand.NewSource(time.Now().UnixNano()))
+		mathRand.Shuffle(len(allValidators), func(i, j int) { allValidators[i], allValidators[j] = allValidators[j], allValidators[i] })

 		require.NoError(b, st.SetValidators(allValidators))
 		require.NoError(b, db.SaveState(context.Background(), st, bytesutil.ToBytes32(key)))
--- a/beacon-chain/execution/BUILD.bazel
+++ b/beacon-chain/execution/BUILD.bazel
@@ -131,11 +131,11 @@ go_test(
        "//testing/util:go_default_library",
        "//time/slots:go_default_library",
        "@com_github_ethereum_go_ethereum//:go_default_library",
-        "@com_github_ethereum_go_ethereum//accounts/abi/bind/backends:go_default_library",
        "@com_github_ethereum_go_ethereum//beacon/engine:go_default_library",
        "@com_github_ethereum_go_ethereum//common:go_default_library",
        "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
        "@com_github_ethereum_go_ethereum//core/types:go_default_library",
+        "@com_github_ethereum_go_ethereum//ethclient/simulated:go_default_library",
        "@com_github_ethereum_go_ethereum//rpc:go_default_library",
        "@com_github_holiman_uint256//:go_default_library",
        "@com_github_pkg_errors//:go_default_library",
--- a/beacon-chain/execution/block_reader_test.go
+++ b/beacon-chain/execution/block_reader_test.go
@@ -12,6 +12,7 @@ import (
 	dbutil "github.com/prysmaticlabs/prysm/v5/beacon-chain/db/testing"
 	mockExecution "github.com/prysmaticlabs/prysm/v5/beacon-chain/execution/testing"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/execution/types"
+	"github.com/prysmaticlabs/prysm/v5/config/params"
 	contracts "github.com/prysmaticlabs/prysm/v5/contracts/deposit"
 	"github.com/prysmaticlabs/prysm/v5/contracts/deposit/mock"
 	"github.com/prysmaticlabs/prysm/v5/testing/assert"
@@ -44,7 +45,7 @@ func TestLatestMainchainInfo_OK(t *testing.T) {
 	web3Service = setDefaultMocks(web3Service)
 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}

-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)
 	testAcc.Backend.Commit()

@@ -141,7 +142,7 @@ func TestBlockExists_ValidHash(t *testing.T) {
 	web3Service = setDefaultMocks(web3Service)
 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}
 	testAcc.Backend.Commit()
-	block, err := testAcc.Backend.BlockByNumber(context.Background(), big.NewInt(0))
+	block, err := testAcc.Backend.Client().BlockByNumber(context.Background(), big.NewInt(0))
 	assert.NoError(t, err)

 	exists, height, err := web3Service.BlockExists(context.Background(), block.Hash())
@@ -201,8 +202,10 @@ func TestBlockExists_UsesCachedBlockInfo(t *testing.T) {
 }

 func TestService_BlockNumberByTimestamp(t *testing.T) {
+	ctx := context.Background()
 	beaconDB := dbutil.SetupDB(t)
 	testAcc, err := mock.Setup()
+
 	require.NoError(t, err, "Unable to set up simulated backend")
 	server, endpoint, err := mockExecution.SetupRPCServer()
 	require.NoError(t, err)
@@ -216,16 +219,22 @@ func TestService_BlockNumberByTimestamp(t *testing.T) {
 	require.NoError(t, err)
 	web3Service = setDefaultMocks(web3Service)
 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}
-
+	// simulated backend sets eth1 block
+	params.SetupTestConfigCleanup(t)
+	conf := params.BeaconConfig().Copy()
+	conf.SecondsPerETH1Block = 1
+	params.OverrideBeaconConfig(conf)
+	initialHead, err := testAcc.Backend.Client().HeaderByNumber(ctx, nil)
+	require.NoError(t, err)
 	for i := 0; i < 200; i++ {
 		testAcc.Backend.Commit()
 	}
-	ctx := context.Background()
-	hd, err := testAcc.Backend.HeaderByNumber(ctx, nil)
+
+	hd, err := testAcc.Backend.Client().HeaderByNumber(ctx, nil)
 	require.NoError(t, err)
 	web3Service.latestEth1Data.BlockTime = hd.Time
 	web3Service.latestEth1Data.BlockHeight = hd.Number.Uint64()
-	blk, err := web3Service.BlockByTimestamp(ctx, 1000 /* time */)
+	blk, err := web3Service.BlockByTimestamp(ctx, initialHead.Time+100 /* time */)
 	require.NoError(t, err)
 	if blk.Number.Cmp(big.NewInt(0)) == 0 {
 		t.Error("Returned a block with zero number, expected to be non zero")
@@ -253,7 +262,7 @@ func TestService_BlockNumberByTimestampLessTargetTime(t *testing.T) {
 		testAcc.Backend.Commit()
 	}
 	ctx := context.Background()
-	hd, err := testAcc.Backend.HeaderByNumber(ctx, nil)
+	hd, err := testAcc.Backend.Client().HeaderByNumber(ctx, nil)
 	require.NoError(t, err)
 	web3Service.latestEth1Data.BlockTime = hd.Time
 	// Use extremely small deadline to illustrate that context deadlines are respected.
@@ -291,7 +300,7 @@ func TestService_BlockNumberByTimestampMoreTargetTime(t *testing.T) {
 		testAcc.Backend.Commit()
 	}
 	ctx := context.Background()
-	hd, err := testAcc.Backend.HeaderByNumber(ctx, nil)
+	hd, err := testAcc.Backend.Client().HeaderByNumber(ctx, nil)
 	require.NoError(t, err)
 	web3Service.latestEth1Data.BlockTime = hd.Time
 	// Use extremely small deadline to illustrate that context deadlines are respected.
--- a/beacon-chain/execution/engine_client.go
+++ b/beacon-chain/execution/engine_client.go
@@ -136,30 +136,18 @@ func (s *Service) NewPayload(ctx context.Context, payload interfaces.ExecutionDa
 	defer cancel()
 	result := &pb.PayloadStatus{}

-	switch payload.Proto().(type) {
+	switch payloadPb := payload.Proto().(type) {
 	case *pb.ExecutionPayload:
-		payloadPb, ok := payload.Proto().(*pb.ExecutionPayload)
-		if !ok {
-			return nil, errors.New("execution data must be a Bellatrix or Capella execution payload")
-		}
 		err := s.rpcClient.CallContext(ctx, result, NewPayloadMethod, payloadPb)
 		if err != nil {
 			return nil, handleRPCError(err)
 		}
 	case *pb.ExecutionPayloadCapella:
-		payloadPb, ok := payload.Proto().(*pb.ExecutionPayloadCapella)
-		if !ok {
-			return nil, errors.New("execution data must be a Capella execution payload")
-		}
 		err := s.rpcClient.CallContext(ctx, result, NewPayloadMethodV2, payloadPb)
 		if err != nil {
 			return nil, handleRPCError(err)
 		}
 	case *pb.ExecutionPayloadDeneb:
-		payloadPb, ok := payload.Proto().(*pb.ExecutionPayloadDeneb)
-		if !ok {
-			return nil, errors.New("execution data must be a Deneb execution payload")
-		}
 		if executionRequests == nil {
 			err := s.rpcClient.CallContext(ctx, result, NewPayloadMethodV3, payloadPb, versionedHashes, parentBlockRoot)
 			if err != nil {
@@ -233,7 +221,7 @@ func (s *Service) ForkchoiceUpdated(
 		if err != nil {
 			return nil, nil, handleRPCError(err)
 		}
-	case version.Deneb, version.Electra:
+	case version.Deneb, version.Electra, version.Fulu:
 		a, err := attrs.PbV3()
 		if err != nil {
 			return nil, nil, err
@@ -643,43 +631,7 @@ func fullPayloadFromPayloadBody(
 		return nil, errors.New("execution block and header cannot be nil")
 	}

-	switch bVersion {
-	case version.Bellatrix:
-		return blocks.WrappedExecutionPayload(&pb.ExecutionPayload{
-			ParentHash:    header.ParentHash(),
-			FeeRecipient:  header.FeeRecipient(),
-			StateRoot:     header.StateRoot(),
-			ReceiptsRoot:  header.ReceiptsRoot(),
-			LogsBloom:     header.LogsBloom(),
-			PrevRandao:    header.PrevRandao(),
-			BlockNumber:   header.BlockNumber(),
-			GasLimit:      header.GasLimit(),
-			GasUsed:       header.GasUsed(),
-			Timestamp:     header.Timestamp(),
-			ExtraData:     header.ExtraData(),
-			BaseFeePerGas: header.BaseFeePerGas(),
-			BlockHash:     header.BlockHash(),
-			Transactions:  pb.RecastHexutilByteSlice(body.Transactions),
-		})
-	case version.Capella:
-		return blocks.WrappedExecutionPayloadCapella(&pb.ExecutionPayloadCapella{
-			ParentHash:    header.ParentHash(),
-			FeeRecipient:  header.FeeRecipient(),
-			StateRoot:     header.StateRoot(),
-			ReceiptsRoot:  header.ReceiptsRoot(),
-			LogsBloom:     header.LogsBloom(),
-			PrevRandao:    header.PrevRandao(),
-			BlockNumber:   header.BlockNumber(),
-			GasLimit:      header.GasLimit(),
-			GasUsed:       header.GasUsed(),
-			Timestamp:     header.Timestamp(),
-			ExtraData:     header.ExtraData(),
-			BaseFeePerGas: header.BaseFeePerGas(),
-			BlockHash:     header.BlockHash(),
-			Transactions:  pb.RecastHexutilByteSlice(body.Transactions),
-			Withdrawals:   body.Withdrawals,
-		}) // We can't get the block value and don't care about the block value for this instance
-	case version.Deneb, version.Electra:
+	if bVersion >= version.Deneb {
 		ebg, err := header.ExcessBlobGas()
 		if err != nil {
 			return nil, errors.Wrap(err, "unable to extract ExcessBlobGas attribute from execution payload header")
@@ -708,9 +660,48 @@ func fullPayloadFromPayloadBody(
 				ExcessBlobGas: ebg,
 				BlobGasUsed:   bgu,
 			}) // We can't get the block value and don't care about the block value for this instance
-	default:
-		return nil, fmt.Errorf("unknown execution block version for payload %d", bVersion)
 	}
+
+	if bVersion >= version.Capella {
+		return blocks.WrappedExecutionPayloadCapella(&pb.ExecutionPayloadCapella{
+			ParentHash:    header.ParentHash(),
+			FeeRecipient:  header.FeeRecipient(),
+			StateRoot:     header.StateRoot(),
+			ReceiptsRoot:  header.ReceiptsRoot(),
+			LogsBloom:     header.LogsBloom(),
+			PrevRandao:    header.PrevRandao(),
+			BlockNumber:   header.BlockNumber(),
+			GasLimit:      header.GasLimit(),
+			GasUsed:       header.GasUsed(),
+			Timestamp:     header.Timestamp(),
+			ExtraData:     header.ExtraData(),
+			BaseFeePerGas: header.BaseFeePerGas(),
+			BlockHash:     header.BlockHash(),
+			Transactions:  pb.RecastHexutilByteSlice(body.Transactions),
+			Withdrawals:   body.Withdrawals,
+		}) // We can't get the block value and don't care about the block value for this instance
+	}
+
+	if bVersion >= version.Bellatrix {
+		return blocks.WrappedExecutionPayload(&pb.ExecutionPayload{
+			ParentHash:    header.ParentHash(),
+			FeeRecipient:  header.FeeRecipient(),
+			StateRoot:     header.StateRoot(),
+			ReceiptsRoot:  header.ReceiptsRoot(),
+			LogsBloom:     header.LogsBloom(),
+			PrevRandao:    header.PrevRandao(),
+			BlockNumber:   header.BlockNumber(),
+			GasLimit:      header.GasLimit(),
+			GasUsed:       header.GasUsed(),
+			Timestamp:     header.Timestamp(),
+			ExtraData:     header.ExtraData(),
+			BaseFeePerGas: header.BaseFeePerGas(),
+			BlockHash:     header.BlockHash(),
+			Transactions:  pb.RecastHexutilByteSlice(body.Transactions),
+		})
+	}
+
+	return nil, fmt.Errorf("unknown execution block version for payload %s", version.String(bVersion))
 }

 // Handles errors received from the RPC server according to the specification.
@@ -802,35 +793,7 @@ func tDStringToUint256(td string) (*uint256.Int, error) {
 }

 func EmptyExecutionPayload(v int) (proto.Message, error) {
-	switch v {
-	case version.Bellatrix:
-		return &pb.ExecutionPayload{
-			ParentHash:    make([]byte, fieldparams.RootLength),
-			FeeRecipient:  make([]byte, fieldparams.FeeRecipientLength),
-			StateRoot:     make([]byte, fieldparams.RootLength),
-			ReceiptsRoot:  make([]byte, fieldparams.RootLength),
-			LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
-			PrevRandao:    make([]byte, fieldparams.RootLength),
-			ExtraData:     make([]byte, 0),
-			BaseFeePerGas: make([]byte, fieldparams.RootLength),
-			BlockHash:     make([]byte, fieldparams.RootLength),
-			Transactions:  make([][]byte, 0),
-		}, nil
-	case version.Capella:
-		return &pb.ExecutionPayloadCapella{
-			ParentHash:    make([]byte, fieldparams.RootLength),
-			FeeRecipient:  make([]byte, fieldparams.FeeRecipientLength),
-			StateRoot:     make([]byte, fieldparams.RootLength),
-			ReceiptsRoot:  make([]byte, fieldparams.RootLength),
-			LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
-			PrevRandao:    make([]byte, fieldparams.RootLength),
-			ExtraData:     make([]byte, 0),
-			BaseFeePerGas: make([]byte, fieldparams.RootLength),
-			BlockHash:     make([]byte, fieldparams.RootLength),
-			Transactions:  make([][]byte, 0),
-			Withdrawals:   make([]*pb.Withdrawal, 0),
-		}, nil
-	case version.Deneb, version.Electra:
+	if v >= version.Deneb {
 		return &pb.ExecutionPayloadDeneb{
 			ParentHash:    make([]byte, fieldparams.RootLength),
 			FeeRecipient:  make([]byte, fieldparams.FeeRecipientLength),
@@ -844,15 +807,10 @@ func EmptyExecutionPayload(v int) (proto.Message, error) {
 			Transactions:  make([][]byte, 0),
 			Withdrawals:   make([]*pb.Withdrawal, 0),
 		}, nil
-	default:
-		return nil, errors.Wrapf(ErrUnsupportedVersion, "version=%s", version.String(v))
 	}
-}

-func EmptyExecutionPayloadHeader(v int) (proto.Message, error) {
-	switch v {
-	case version.Bellatrix:
-		return &pb.ExecutionPayloadHeader{
+	if v >= version.Capella {
+		return &pb.ExecutionPayloadCapella{
 			ParentHash:    make([]byte, fieldparams.RootLength),
 			FeeRecipient:  make([]byte, fieldparams.FeeRecipientLength),
 			StateRoot:     make([]byte, fieldparams.RootLength),
@@ -862,22 +820,31 @@ func EmptyExecutionPayloadHeader(v int) (proto.Message, error) {
 			ExtraData:     make([]byte, 0),
 			BaseFeePerGas: make([]byte, fieldparams.RootLength),
 			BlockHash:     make([]byte, fieldparams.RootLength),
+			Transactions:  make([][]byte, 0),
+			Withdrawals:   make([]*pb.Withdrawal, 0),
 		}, nil
-	case version.Capella:
-		return &pb.ExecutionPayloadHeaderCapella{
-			ParentHash:       make([]byte, fieldparams.RootLength),
-			FeeRecipient:     make([]byte, fieldparams.FeeRecipientLength),
-			StateRoot:        make([]byte, fieldparams.RootLength),
-			ReceiptsRoot:     make([]byte, fieldparams.RootLength),
-			LogsBloom:        make([]byte, fieldparams.LogsBloomLength),
-			PrevRandao:       make([]byte, fieldparams.RootLength),
-			ExtraData:        make([]byte, 0),
-			BaseFeePerGas:    make([]byte, fieldparams.RootLength),
-			BlockHash:        make([]byte, fieldparams.RootLength),
-			TransactionsRoot: make([]byte, fieldparams.RootLength),
-			WithdrawalsRoot:  make([]byte, fieldparams.RootLength),
+	}
+
+	if v >= version.Bellatrix {
+		return &pb.ExecutionPayload{
+			ParentHash:    make([]byte, fieldparams.RootLength),
+			FeeRecipient:  make([]byte, fieldparams.FeeRecipientLength),
+			StateRoot:     make([]byte, fieldparams.RootLength),
+			ReceiptsRoot:  make([]byte, fieldparams.RootLength),
+			LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
+			PrevRandao:    make([]byte, fieldparams.RootLength),
+			ExtraData:     make([]byte, 0),
+			BaseFeePerGas: make([]byte, fieldparams.RootLength),
+			BlockHash:     make([]byte, fieldparams.RootLength),
+			Transactions:  make([][]byte, 0),
 		}, nil
-	case version.Deneb, version.Electra:
+	}
+
+	return nil, errors.Wrapf(ErrUnsupportedVersion, "version=%s", version.String(v))
+}
+
+func EmptyExecutionPayloadHeader(v int) (proto.Message, error) {
+	if v >= version.Deneb {
 		return &pb.ExecutionPayloadHeaderDeneb{
 			ParentHash:       make([]byte, fieldparams.RootLength),
 			FeeRecipient:     make([]byte, fieldparams.FeeRecipientLength),
@@ -891,9 +858,39 @@ func EmptyExecutionPayloadHeader(v int) (proto.Message, error) {
 			TransactionsRoot: make([]byte, fieldparams.RootLength),
 			WithdrawalsRoot:  make([]byte, fieldparams.RootLength),
 		}, nil
-	default:
-		return nil, errors.Wrapf(ErrUnsupportedVersion, "version=%s", version.String(v))
 	}
+
+	if v >= version.Capella {
+		return &pb.ExecutionPayloadHeaderCapella{
+			ParentHash:       make([]byte, fieldparams.RootLength),
+			FeeRecipient:     make([]byte, fieldparams.FeeRecipientLength),
+			StateRoot:        make([]byte, fieldparams.RootLength),
+			ReceiptsRoot:     make([]byte, fieldparams.RootLength),
+			LogsBloom:        make([]byte, fieldparams.LogsBloomLength),
+			PrevRandao:       make([]byte, fieldparams.RootLength),
+			ExtraData:        make([]byte, 0),
+			BaseFeePerGas:    make([]byte, fieldparams.RootLength),
+			BlockHash:        make([]byte, fieldparams.RootLength),
+			TransactionsRoot: make([]byte, fieldparams.RootLength),
+			WithdrawalsRoot:  make([]byte, fieldparams.RootLength),
+		}, nil
+	}
+
+	if v >= version.Bellatrix {
+		return &pb.ExecutionPayloadHeader{
+			ParentHash:    make([]byte, fieldparams.RootLength),
+			FeeRecipient:  make([]byte, fieldparams.FeeRecipientLength),
+			StateRoot:     make([]byte, fieldparams.RootLength),
+			ReceiptsRoot:  make([]byte, fieldparams.RootLength),
+			LogsBloom:     make([]byte, fieldparams.LogsBloomLength),
+			PrevRandao:    make([]byte, fieldparams.RootLength),
+			ExtraData:     make([]byte, 0),
+			BaseFeePerGas: make([]byte, fieldparams.RootLength),
+			BlockHash:     make([]byte, fieldparams.RootLength),
+		}, nil
+	}
+
+	return nil, errors.Wrapf(ErrUnsupportedVersion, "version=%s", version.String(v))
 }

 func toBlockNumArg(number *big.Int) string {
--- a/beacon-chain/execution/log_processing_test.go
+++ b/beacon-chain/execution/log_processing_test.go
@@ -47,7 +47,7 @@ func TestProcessDepositLog_OK(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)

 	testAcc.Backend.Commit()
@@ -72,7 +72,7 @@ func TestProcessDepositLog_OK(t *testing.T) {
 		},
 	}

-	logs, err := testAcc.Backend.FilterLogs(web3Service.ctx, query)
+	logs, err := testAcc.Backend.Client().FilterLogs(web3Service.ctx, query)
 	require.NoError(t, err, "Unable to retrieve logs")

 	if len(logs) == 0 {
@@ -116,7 +116,7 @@ func TestProcessDepositLog_InsertsPendingDeposit(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)

 	testAcc.Backend.Commit()
@@ -144,7 +144,7 @@ func TestProcessDepositLog_InsertsPendingDeposit(t *testing.T) {
 		},
 	}

-	logs, err := testAcc.Backend.FilterLogs(web3Service.ctx, query)
+	logs, err := testAcc.Backend.Client().FilterLogs(web3Service.ctx, query)
 	require.NoError(t, err, "Unable to retrieve logs")

 	web3Service.chainStartData.Chainstarted = true
@@ -176,7 +176,7 @@ func TestUnpackDepositLogData_OK(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)

 	testAcc.Backend.Commit()
@@ -199,7 +199,7 @@ func TestUnpackDepositLogData_OK(t *testing.T) {
 		},
 	}

-	logz, err := testAcc.Backend.FilterLogs(web3Service.ctx, query)
+	logz, err := testAcc.Backend.Client().FilterLogs(web3Service.ctx, query)
 	require.NoError(t, err, "Unable to retrieve logs")

 	loggedPubkey, withCreds, _, loggedSig, index, err := contracts.UnpackDepositLogData(logz[0].Data)
@@ -232,7 +232,7 @@ func TestProcessETH2GenesisLog_8DuplicatePubkeys(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)

 	params.SetupTestConfigCleanup(t)
@@ -269,7 +269,7 @@ func TestProcessETH2GenesisLog_8DuplicatePubkeys(t *testing.T) {
 		},
 	}

-	logs, err := testAcc.Backend.FilterLogs(web3Service.ctx, query)
+	logs, err := testAcc.Backend.Client().FilterLogs(web3Service.ctx, query)
 	require.NoError(t, err, "Unable to retrieve logs")

 	for i := range logs {
@@ -307,7 +307,7 @@ func TestProcessETH2GenesisLog(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}
 	require.NoError(t, err)
 	params.SetupTestConfigCleanup(t)
@@ -342,7 +342,7 @@ func TestProcessETH2GenesisLog(t *testing.T) {
 		},
 	}

-	logs, err := testAcc.Backend.FilterLogs(web3Service.ctx, query)
+	logs, err := testAcc.Backend.Client().FilterLogs(web3Service.ctx, query)
 	require.NoError(t, err, "Unable to retrieve logs")
 	require.Equal(t, depositsReqForChainStart, len(logs))

@@ -400,16 +400,18 @@ func TestProcessETH2GenesisLog_CorrectNumOfDeposits(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)
 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}
-	web3Service.httpLogger = testAcc.Backend
+	web3Service.httpLogger = testAcc.Backend.Client()
 	web3Service.latestEth1Data.LastRequestedBlock = 0
-	web3Service.latestEth1Data.BlockHeight = testAcc.Backend.Blockchain().CurrentBlock().Number.Uint64()
-	web3Service.latestEth1Data.BlockTime = testAcc.Backend.Blockchain().CurrentBlock().Time
+	block, err := testAcc.Backend.Client().BlockByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	web3Service.latestEth1Data.BlockHeight = block.NumberU64()
+	web3Service.latestEth1Data.BlockTime = block.Time()
 	bConfig := params.MinimalSpecConfig().Copy()
 	bConfig.MinGenesisTime = 0
-	bConfig.SecondsPerETH1Block = 10
+	bConfig.SecondsPerETH1Block = 1
 	params.OverrideBeaconConfig(bConfig)
 	nConfig := params.BeaconNetworkConfig()
 	nConfig.ContractDeploymentBlock = 0
@@ -444,8 +446,10 @@ func TestProcessETH2GenesisLog_CorrectNumOfDeposits(t *testing.T) {
 	for i := uint64(0); i < params.BeaconConfig().Eth1FollowDistance; i++ {
 		testAcc.Backend.Commit()
 	}
-	web3Service.latestEth1Data.BlockHeight = testAcc.Backend.Blockchain().CurrentBlock().Number.Uint64()
-	web3Service.latestEth1Data.BlockTime = testAcc.Backend.Blockchain().CurrentBlock().Time
+	b, err := testAcc.Backend.Client().BlockByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	web3Service.latestEth1Data.BlockHeight = b.NumberU64()
+	web3Service.latestEth1Data.BlockTime = b.Time()

 	// Set up our subscriber now to listen for the chain started event.
 	stateChannel := make(chan *feed.Event, 1)
@@ -497,13 +501,15 @@ func TestProcessETH2GenesisLog_LargePeriodOfNoLogs(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)
 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}
-	web3Service.httpLogger = testAcc.Backend
+	web3Service.httpLogger = testAcc.Backend.Client()
 	web3Service.latestEth1Data.LastRequestedBlock = 0
-	web3Service.latestEth1Data.BlockHeight = testAcc.Backend.Blockchain().CurrentBlock().Number.Uint64()
-	web3Service.latestEth1Data.BlockTime = testAcc.Backend.Blockchain().CurrentBlock().Time
+	b, err := testAcc.Backend.Client().BlockByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	web3Service.latestEth1Data.BlockHeight = b.NumberU64()
+	web3Service.latestEth1Data.BlockTime = b.Time()
 	bConfig := params.MinimalSpecConfig().Copy()
 	bConfig.SecondsPerETH1Block = 10
 	params.OverrideBeaconConfig(bConfig)
@@ -540,14 +546,19 @@ func TestProcessETH2GenesisLog_LargePeriodOfNoLogs(t *testing.T) {
 	for i := uint64(0); i < 1500; i++ {
 		testAcc.Backend.Commit()
 	}
-	wantedGenesisTime := testAcc.Backend.Blockchain().CurrentBlock().Time
+	genesisBlock, err := testAcc.Backend.Client().BlockByNumber(context.Background(), nil)
+	require.NoError(t, err)
+
+	wantedGenesisTime := genesisBlock.Time()

 	// Forward the chain to account for the follow distance
 	for i := uint64(0); i < params.BeaconConfig().Eth1FollowDistance; i++ {
 		testAcc.Backend.Commit()
 	}
-	web3Service.latestEth1Data.BlockHeight = testAcc.Backend.Blockchain().CurrentBlock().Number.Uint64()
-	web3Service.latestEth1Data.BlockTime = testAcc.Backend.Blockchain().CurrentBlock().Time
+	currBlock, err := testAcc.Backend.Client().BlockByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	web3Service.latestEth1Data.BlockHeight = currBlock.NumberU64()
+	web3Service.latestEth1Data.BlockTime = currBlock.Time()

 	// Set the genesis time 500 blocks ahead of the last
 	// deposit log.
@@ -608,7 +619,7 @@ func newPowchainService(t *testing.T, eth1Backend *mock.TestAccount, beaconDB db
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(eth1Backend.ContractAddr, eth1Backend.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(eth1Backend.ContractAddr, eth1Backend.Backend.Client())
 	require.NoError(t, err)

 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: eth1Backend.Backend}
--- a/beacon-chain/execution/payload_body_test.go
+++ b/beacon-chain/execution/payload_body_test.go
@@ -17,14 +17,6 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/time/slots"
 )

-type versioner struct {
-	version int
-}
-
-func (v versioner) Version() int {
-	return v.version
-}
-
 func payloadToBody(t *testing.T, ed interfaces.ExecutionData) *pb.ExecutionPayloadBody {
 	body := &pb.ExecutionPayloadBody{}
 	txs, err := ed.Transactions()
@@ -45,6 +37,7 @@ type blindedBlockFixtures struct {
 	emptyDenebBlock *fullAndBlinded
 	afterSkipDeneb  *fullAndBlinded
 	electra         *fullAndBlinded
+	fulu            *fullAndBlinded
 }

 type fullAndBlinded struct {
@@ -77,6 +70,12 @@ func electraSlot(t *testing.T) primitives.Slot {
 	return s
 }

+func fuluSlot(t *testing.T) primitives.Slot {
+	s, err := slots.EpochStart(params.BeaconConfig().FuluForkEpoch)
+	require.NoError(t, err)
+	return s
+}
+
 func testBlindedBlockFixtures(t *testing.T) *blindedBlockFixtures {
 	pfx := fixturesStruct()
 	fx := &blindedBlockFixtures{}
@@ -104,11 +103,18 @@ func testBlindedBlockFixtures(t *testing.T) *blindedBlockFixtures {
 	electra.BlockNumber = 5
 	electraBlock, _ := util.GenerateTestElectraBlockWithSidecar(t, [32]byte{}, electraSlot(t), 0, util.WithElectraPayload(electra))
 	fx.electra = blindedBlockWithHeader(t, electraBlock)
+
+	fulu := fixturesStruct().ExecutionPayloadDeneb
+	fulu.BlockHash = bytesutil.PadTo([]byte("fulu"), 32)
+	fulu.BlockNumber = 6
+	fuluBlock, _ := util.GenerateTestElectraBlockWithSidecar(t, [32]byte{}, fuluSlot(t), 0, util.WithElectraPayload(fulu))
+	fx.fulu = blindedBlockWithHeader(t, fuluBlock)
+
 	return fx
 }

 func TestPayloadBodiesViaUnblinder(t *testing.T) {
-	defer util.HackElectraMaxuint(t)()
+	defer util.HackForksMaxuint(t, []int{version.Electra, version.Fulu})()
 	fx := testBlindedBlockFixtures(t)
 	t.Run("mix of non-empty and empty", func(t *testing.T) {
 		cli, srv := newMockEngine(t)
@@ -145,7 +151,7 @@ func TestPayloadBodiesViaUnblinder(t *testing.T) {
 }

 func TestFixtureEquivalence(t *testing.T) {
-	defer util.HackElectraMaxuint(t)()
+	defer util.HackForksMaxuint(t, []int{version.Electra, version.Fulu})()
 	fx := testBlindedBlockFixtures(t)
 	t.Run("full and blinded block equivalence", func(t *testing.T) {
 		testAssertReconstructedEquivalent(t, fx.denebBlock.blinded.block, fx.denebBlock.full)
@@ -248,7 +254,7 @@ func TestComputeRanges(t *testing.T) {
 }

 func TestReconstructBlindedBlockBatchFallbackToRange(t *testing.T) {
-	defer util.HackElectraMaxuint(t)()
+	defer util.HackForksMaxuint(t, []int{version.Electra, version.Fulu})()
 	ctx := context.Background()
 	t.Run("fallback fails", func(t *testing.T) {
 		cli, srv := newMockEngine(t)
@@ -333,18 +339,19 @@ func TestReconstructBlindedBlockBatchFallbackToRange(t *testing.T) {
 	})
 }

-func TestReconstructBlindedBlockBatchDenebAndElectra(t *testing.T) {
-	defer util.HackElectraMaxuint(t)()
-	t.Run("deneb and electra", func(t *testing.T) {
+func TestReconstructBlindedBlockBatchDenebAndBeyond(t *testing.T) {
+	defer util.HackForksMaxuint(t, []int{version.Electra, version.Fulu})()
+	t.Run("deneb and beyond", func(t *testing.T) {
 		cli, srv := newMockEngine(t)
 		fx := testBlindedBlockFixtures(t)
 		srv.register(GetPayloadBodiesByHashV1, func(msg *jsonrpcMessage, w http.ResponseWriter, r *http.Request) {
-			executionPayloadBodies := []*pb.ExecutionPayloadBody{payloadToBody(t, fx.denebBlock.blinded.header), payloadToBody(t, fx.electra.blinded.header)}
+			executionPayloadBodies := []*pb.ExecutionPayloadBody{payloadToBody(t, fx.denebBlock.blinded.header), payloadToBody(t, fx.electra.blinded.header), payloadToBody(t, fx.fulu.blinded.header)}
 			mockWriteResult(t, w, msg, executionPayloadBodies)
 		})
 		blinded := []interfaces.ReadOnlySignedBeaconBlock{
 			fx.denebBlock.blinded.block,
 			fx.electra.blinded.block,
+			fx.fulu.blinded.block,
 		}
 		unblinded, err := reconstructBlindedBlockBatch(context.Background(), cli, blinded)
 		require.NoError(t, err)
--- a/beacon-chain/execution/service_test.go
+++ b/beacon-chain/execution/service_test.go
@@ -8,10 +8,10 @@ import (
 	"time"

 	"github.com/ethereum/go-ethereum"
-	"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	gethTypes "github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethclient/simulated"
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v5/async/event"
@@ -44,7 +44,7 @@ var _ POWBlockFetcher = (*Service)(nil)
 var _ Chain = (*Service)(nil)

 type goodLogger struct {
-	backend *backends.SimulatedBackend
+	backend *simulated.Backend
 }

 func (_ *goodLogger) Close() {}
@@ -53,7 +53,7 @@ func (g *goodLogger) SubscribeFilterLogs(ctx context.Context, q ethereum.FilterQ
 	if g.backend == nil {
 		return new(event.Feed).Subscribe(ch), nil
 	}
-	return g.backend.SubscribeFilterLogs(ctx, q, ch)
+	return g.backend.Client().SubscribeFilterLogs(ctx, q, ch)
 }

 func (g *goodLogger) FilterLogs(ctx context.Context, q ethereum.FilterQuery) ([]gethTypes.Log, error) {
@@ -69,7 +69,7 @@ func (g *goodLogger) FilterLogs(ctx context.Context, q ethereum.FilterQuery) ([]
 		}
 		return logs, nil
 	}
-	return g.backend.FilterLogs(ctx, q)
+	return g.backend.Client().FilterLogs(ctx, q)
 }

 type goodNotifier struct {
@@ -109,7 +109,7 @@ func TestStart_OK(t *testing.T) {
 	require.NoError(t, err, "unable to setup execution service")
 	web3Service = setDefaultMocks(web3Service)
 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)
 	testAcc.Backend.Commit()

@@ -156,7 +156,7 @@ func TestStop_OK(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)

 	testAcc.Backend.Commit()
@@ -186,10 +186,12 @@ func TestService_Eth1Synced(t *testing.T) {
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
 	web3Service = setDefaultMocks(web3Service)
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)

-	currTime := testAcc.Backend.Blockchain().CurrentHeader().Time
+	header, err := testAcc.Backend.Client().HeaderByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	currTime := header.Time
 	now := time.Now()
 	assert.NoError(t, testAcc.Backend.AdjustTime(now.Sub(time.Unix(int64(currTime), 0))))
 	testAcc.Backend.Commit()
@@ -212,22 +214,29 @@ func TestFollowBlock_OK(t *testing.T) {
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")

 	// simulated backend sets eth1 block
-	// time as 10 seconds
 	params.SetupTestConfigCleanup(t)
 	conf := params.BeaconConfig().Copy()
-	conf.SecondsPerETH1Block = 10
+	conf.SecondsPerETH1Block = 1
 	params.OverrideBeaconConfig(conf)

 	web3Service = setDefaultMocks(web3Service)
 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}
-	baseHeight := testAcc.Backend.Blockchain().CurrentBlock().Number.Uint64()
+	block, err := testAcc.Backend.Client().BlockByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	baseHeight := block.NumberU64()
 	// process follow_distance blocks
+	var lastHash common.Hash
 	for i := 0; i < int(params.BeaconConfig().Eth1FollowDistance); i++ {
-		testAcc.Backend.Commit()
+		lastHash = testAcc.Backend.Commit()
 	}
+	lb, err := testAcc.Backend.Client().BlockByHash(context.Background(), lastHash)
+	require.NoError(t, err)
+	log.Println(lb.NumberU64())
 	// set current height
-	web3Service.latestEth1Data.BlockHeight = testAcc.Backend.Blockchain().CurrentBlock().Number.Uint64()
-	web3Service.latestEth1Data.BlockTime = testAcc.Backend.Blockchain().CurrentBlock().Time
+	block, err = testAcc.Backend.Client().BlockByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	web3Service.latestEth1Data.BlockHeight = block.NumberU64()
+	web3Service.latestEth1Data.BlockTime = block.Time()

 	h, err := web3Service.followedBlockHeight(context.Background())
 	require.NoError(t, err)
@@ -238,9 +247,12 @@ func TestFollowBlock_OK(t *testing.T) {
 	for i := uint64(0); i < numToForward; i++ {
 		testAcc.Backend.Commit()
 	}
+
+	newBlock, err := testAcc.Backend.Client().BlockByNumber(context.Background(), nil)
+	require.NoError(t, err)
 	// set current height
-	web3Service.latestEth1Data.BlockHeight = testAcc.Backend.Blockchain().CurrentBlock().Number.Uint64()
-	web3Service.latestEth1Data.BlockTime = testAcc.Backend.Blockchain().CurrentBlock().Time
+	web3Service.latestEth1Data.BlockHeight = newBlock.NumberU64()
+	web3Service.latestEth1Data.BlockTime = newBlock.Time()

 	h, err = web3Service.followedBlockHeight(context.Background())
 	require.NoError(t, err)
@@ -325,11 +337,11 @@ func TestLogTillGenesis_OK(t *testing.T) {
 		WithDatabase(beaconDB),
 	)
 	require.NoError(t, err, "unable to setup web3 ETH1.0 chain service")
-	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend)
+	web3Service.depositContractCaller, err = contracts.NewDepositContractCaller(testAcc.ContractAddr, testAcc.Backend.Client())
 	require.NoError(t, err)

 	web3Service.rpcClient = &mockExecution.RPCClient{Backend: testAcc.Backend}
-	web3Service.httpLogger = testAcc.Backend
+	web3Service.httpLogger = testAcc.Backend.Client()
 	for i := 0; i < 30; i++ {
 		testAcc.Backend.Commit()
 	}
@@ -485,15 +497,18 @@ func TestNewService_EarliestVotingBlock(t *testing.T) {
 	for i := 0; i < numToForward; i++ {
 		testAcc.Backend.Commit()
 	}
-	currTime := testAcc.Backend.Blockchain().CurrentHeader().Time
+	currHeader, err := testAcc.Backend.Client().HeaderByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	currTime := currHeader.Time
 	now := time.Now()
 	err = testAcc.Backend.AdjustTime(now.Sub(time.Unix(int64(currTime), 0)))
 	require.NoError(t, err)
 	testAcc.Backend.Commit()
-
-	currTime = testAcc.Backend.Blockchain().CurrentHeader().Time
-	web3Service.latestEth1Data.BlockHeight = testAcc.Backend.Blockchain().CurrentHeader().Number.Uint64()
-	web3Service.latestEth1Data.BlockTime = testAcc.Backend.Blockchain().CurrentHeader().Time
+	currHeader, err = testAcc.Backend.Client().HeaderByNumber(context.Background(), nil)
+	require.NoError(t, err)
+	currTime = currHeader.Time
+	web3Service.latestEth1Data.BlockHeight = currHeader.Number.Uint64()
+	web3Service.latestEth1Data.BlockTime = currHeader.Time
 	web3Service.chainStartData.GenesisTime = currTime

 	// With a current slot of zero, only request follow_blocks behind.
--- a/beacon-chain/execution/testing/BUILD.bazel
+++ b/beacon-chain/execution/testing/BUILD.bazel
@@ -25,10 +25,10 @@ go_library(
        "//encoding/bytesutil:go_default_library",
        "//proto/engine/v1:go_default_library",
        "//proto/prysm/v1alpha1:go_default_library",
-        "@com_github_ethereum_go_ethereum//accounts/abi/bind/backends:go_default_library",
        "@com_github_ethereum_go_ethereum//common:go_default_library",
        "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
        "@com_github_ethereum_go_ethereum//core/types:go_default_library",
+        "@com_github_ethereum_go_ethereum//ethclient/simulated:go_default_library",
        "@com_github_ethereum_go_ethereum//rpc:go_default_library",
        "@com_github_holiman_uint256//:go_default_library",
        "@com_github_pkg_errors//:go_default_library",
--- a/beacon-chain/execution/testing/mock_execution_chain.go
+++ b/beacon-chain/execution/testing/mock_execution_chain.go
@@ -9,10 +9,10 @@ import (
 	"net/http/httptest"
 	"time"

-	"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	gethTypes "github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethclient/simulated"
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v5/async/event"
@@ -141,7 +141,7 @@ func (m *Chain) ETH1ConnectionErrors() []error {

 // RPCClient defines the mock rpc client.
 type RPCClient struct {
-	Backend     *backends.SimulatedBackend
+	Backend     *simulated.Backend
 	BlockNumMap map[uint64]*types.HeaderInfo
 }

@@ -195,7 +195,7 @@ func (r *RPCClient) CallContext(ctx context.Context, obj interface{}, methodName
 				return err
 			}
 		}
-		h, err := r.Backend.HeaderByNumber(ctx, num)
+		h, err := r.Backend.Client().HeaderByNumber(ctx, num)
 		if err != nil {
 			return err
 		}
@@ -213,7 +213,7 @@ func (r *RPCClient) CallContext(ctx context.Context, obj interface{}, methodName
 		if !ok {
 			return errors.Errorf("wrong argument type provided: %T", args[0])
 		}
-		h, err := r.Backend.HeaderByHash(ctx, val)
+		h, err := r.Backend.Client().HeaderByHash(ctx, val)
 		if err != nil {
 			return err
 		}
@@ -241,7 +241,7 @@ func (r *RPCClient) BatchCall(b []rpc.BatchElem) error {
 		if err != nil {
 			return err
 		}
-		h, err := r.Backend.HeaderByNumber(context.Background(), num)
+		h, err := r.Backend.Client().HeaderByNumber(context.Background(), num)
 		if err != nil {
 			return err
 		}
--- a/beacon-chain/node/node.go
+++ b/beacon-chain/node/node.go
@@ -93,6 +93,7 @@ type BeaconNode struct {
 	stop                    chan struct{} // Channel to wait for termination notifications.
 	db                      db.Database
 	slasherDB               db.SlasherDatabase
+	attestationCache        *cache.AttestationCache
 	attestationPool         attestations.Pool
 	exitPool                voluntaryexits.PoolManager
 	slashingsPool           slashings.PoolManager
@@ -144,6 +145,7 @@ func New(cliCtx *cli.Context, cancel context.CancelFunc, opts ...Option) (*Beaco
 		stateFeed:               new(event.Feed),
 		blockFeed:               new(event.Feed),
 		opFeed:                  new(event.Feed),
+		attestationCache:        cache.NewAttestationCache(),
 		attestationPool:         attestations.NewPool(),
 		exitPool:                voluntaryexits.NewPool(),
 		slashingsPool:           slashings.NewPool(),
@@ -704,6 +706,7 @@ func (b *BeaconNode) fetchBuilderService() *builder.Service {

 func (b *BeaconNode) registerAttestationPool() error {
 	s, err := attestations.NewService(b.ctx, &attestations.Config{
+		Cache:               b.attestationCache,
 		Pool:                b.attestationPool,
 		InitialSyncComplete: b.initialSyncComplete,
 	})
@@ -732,6 +735,7 @@ func (b *BeaconNode) registerBlockchainService(fc forkchoice.ForkChoicer, gs *st
 		blockchain.WithDepositCache(b.depositCache),
 		blockchain.WithChainStartFetcher(web3Service),
 		blockchain.WithExecutionEngineCaller(web3Service),
+		blockchain.WithAttestationCache(b.attestationCache),
 		blockchain.WithAttestationPool(b.attestationPool),
 		blockchain.WithExitPool(b.exitPool),
 		blockchain.WithSlashingPool(b.slashingsPool),
@@ -816,6 +820,7 @@ func (b *BeaconNode) registerSyncService(initialSyncComplete chan struct{}, bFil
 		regularsync.WithBlockNotifier(b),
 		regularsync.WithAttestationNotifier(b),
 		regularsync.WithOperationNotifier(b),
+		regularsync.WithAttestationCache(b.attestationCache),
 		regularsync.WithAttestationPool(b.attestationPool),
 		regularsync.WithExitPool(b.exitPool),
 		regularsync.WithSlashingPool(b.slashingsPool),
@@ -952,6 +957,7 @@ func (b *BeaconNode) registerRPCService(router *http.ServeMux) error {
 		GenesisTimeFetcher:        chainService,
 		GenesisFetcher:            chainService,
 		OptimisticModeFetcher:     chainService,
+		AttestationCache:          b.attestationCache,
 		AttestationsPool:          b.attestationPool,
 		ExitPool:                  b.exitPool,
 		SlashingsPool:             b.slashingsPool,
--- a/beacon-chain/operations/attestations/BUILD.bazel
+++ b/beacon-chain/operations/attestations/BUILD.bazel
@@ -16,6 +16,7 @@ go_library(
        "//testing/spectest:__subpackages__",
    ],
    deps = [
+        "//beacon-chain/cache:go_default_library",
        "//beacon-chain/operations/attestations/kv:go_default_library",
        "//cache/lru:go_default_library",
        "//config/features:go_default_library",
--- a/beacon-chain/operations/attestations/attmap/BUILD.bazel
+++ b/beacon-chain/operations/attestations/attmap/BUILD.bazel
@@ -0,0 +1,13 @@
+load("@prysm//tools/go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["map.go"],
+    importpath = "github.com/prysmaticlabs/prysm/v5/beacon-chain/operations/attestations/attmap",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//proto/prysm/v1alpha1/attestation:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+    ],
+)
--- a/beacon-chain/operations/attestations/attmap/map.go
+++ b/beacon-chain/operations/attestations/attmap/map.go
@@ -0,0 +1,89 @@
+package attmap
+
+import (
+	"sync"
+
+	"github.com/pkg/errors"
+	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1/attestation"
+)
+
+// Attestations --
+type Attestations struct {
+	atts map[attestation.Id]ethpb.Att
+	sync.RWMutex
+}
+
+// New creates a new instance of the map.
+func New() *Attestations {
+	return &Attestations{atts: make(map[attestation.Id]ethpb.Att)}
+}
+
+// Save stores an attestation in the map.
+func (a *Attestations) Save(att ethpb.Att) error {
+	if att == nil || att.IsNil() {
+		return nil
+	}
+
+	id, err := attestation.NewId(att, attestation.Full)
+	if err != nil {
+		return errors.Wrap(err, "could not create attestation ID")
+	}
+
+	a.Lock()
+	defer a.Unlock()
+	a.atts[id] = att
+
+	return nil
+}
+
+// SaveMany stores multiple attestation in the map.
+func (a *Attestations) SaveMany(atts []ethpb.Att) error {
+	for _, att := range atts {
+		if err := a.Save(att); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// GetAll retrieves all attestations that are in the map.
+func (a *Attestations) GetAll() []ethpb.Att {
+	a.RLock()
+	defer a.RUnlock()
+
+	atts := make([]ethpb.Att, len(a.atts))
+	i := 0
+	for _, att := range a.atts {
+		atts[i] = att.Clone()
+		i++
+	}
+
+	return atts
+}
+
+// Delete removes an attestation from the map.
+func (a *Attestations) Delete(att ethpb.Att) error {
+	if att == nil || att.IsNil() {
+		return nil
+	}
+
+	id, err := attestation.NewId(att, attestation.Full)
+	if err != nil {
+		return errors.Wrap(err, "could not create attestation ID")
+	}
+
+	a.Lock()
+	defer a.Unlock()
+	delete(a.atts, id)
+
+	return nil
+}
+
+// Count returns the number of attestations in the map.
+func (a *Attestations) Count() int {
+	a.RLock()
+	defer a.RUnlock()
+	return len(a.atts)
+}
--- a/beacon-chain/operations/attestations/kv/BUILD.bazel
+++ b/beacon-chain/operations/attestations/kv/BUILD.bazel
@@ -5,7 +5,6 @@ go_library(
    srcs = [
        "aggregated.go",
        "block.go",
-        "forkchoice.go",
        "kv.go",
        "seen_bits.go",
        "unaggregated.go",
@@ -14,6 +13,7 @@ go_library(
    visibility = ["//beacon-chain:__subpackages__"],
    deps = [
        "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/operations/attestations/attmap:go_default_library",
        "//config/params:go_default_library",
        "//consensus-types/primitives:go_default_library",
        "//monitoring/tracing/trace:go_default_library",
--- a/beacon-chain/operations/attestations/kv/aggregated.go
+++ b/beacon-chain/operations/attestations/kv/aggregated.go
@@ -88,7 +88,7 @@ func (c *AttCaches) aggregateParallel(atts map[attestation.Id][]ethpb.Att, leftO
 					log.Error("nil aggregated attestation")
 					continue
 				}
-				if helpers.IsAggregated(aggregated) {
+				if aggregated.IsAggregated() {
 					if err := c.SaveAggregatedAttestations([]ethpb.Att{aggregated}); err != nil {
 						log.WithError(err).Error("could not save aggregated attestation")
 						continue
@@ -122,7 +122,7 @@ func (c *AttCaches) SaveAggregatedAttestation(att ethpb.Att) error {
 	if err := helpers.ValidateNilAttestation(att); err != nil {
 		return err
 	}
-	if !helpers.IsAggregated(att) {
+	if !att.IsAggregated() {
 		return errors.New("attestation is not aggregated")
 	}
 	has, err := c.HasAggregatedAttestation(att)
@@ -236,7 +236,7 @@ func (c *AttCaches) AggregatedAttestationsBySlotIndexElectra(
 	c.aggregatedAttLock.RLock()
 	defer c.aggregatedAttLock.RUnlock()
 	for _, as := range c.aggregatedAtt {
-		if as[0].Version() == version.Electra && slot == as[0].GetData().Slot && as[0].CommitteeBitsVal().BitAt(uint64(committeeIndex)) {
+		if as[0].Version() >= version.Electra && slot == as[0].GetData().Slot && as[0].CommitteeBitsVal().BitAt(uint64(committeeIndex)) {
 			for _, a := range as {
 				att, ok := a.(*ethpb.AttestationElectra)
 				// This will never fail in practice because we asserted the version
@@ -255,7 +255,7 @@ func (c *AttCaches) DeleteAggregatedAttestation(att ethpb.Att) error {
 	if err := helpers.ValidateNilAttestation(att); err != nil {
 		return err
 	}
-	if !helpers.IsAggregated(att) {
+	if !att.IsAggregated() {
 		return errors.New("attestation is not aggregated")
 	}

--- a/beacon-chain/operations/attestations/kv/forkchoice.go
+++ b/beacon-chain/operations/attestations/kv/forkchoice.go
@@ -1,74 +0,0 @@
-package kv
-
-import (
-	"github.com/pkg/errors"
-	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
-	"github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1/attestation"
-)
-
-// SaveForkchoiceAttestation saves an forkchoice attestation in cache.
-func (c *AttCaches) SaveForkchoiceAttestation(att ethpb.Att) error {
-	if att == nil || att.IsNil() {
-		return nil
-	}
-
-	id, err := attestation.NewId(att, attestation.Full)
-	if err != nil {
-		return errors.Wrap(err, "could not create attestation ID")
-	}
-
-	c.forkchoiceAttLock.Lock()
-	defer c.forkchoiceAttLock.Unlock()
-	c.forkchoiceAtt[id] = att
-
-	return nil
-}
-
-// SaveForkchoiceAttestations saves a list of forkchoice attestations in cache.
-func (c *AttCaches) SaveForkchoiceAttestations(atts []ethpb.Att) error {
-	for _, att := range atts {
-		if err := c.SaveForkchoiceAttestation(att); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-// ForkchoiceAttestations returns the forkchoice attestations in cache.
-func (c *AttCaches) ForkchoiceAttestations() []ethpb.Att {
-	c.forkchoiceAttLock.RLock()
-	defer c.forkchoiceAttLock.RUnlock()
-
-	atts := make([]ethpb.Att, 0, len(c.forkchoiceAtt))
-	for _, att := range c.forkchoiceAtt {
-		atts = append(atts, att.Clone())
-	}
-
-	return atts
-}
-
-// DeleteForkchoiceAttestation deletes a forkchoice attestation in cache.
-func (c *AttCaches) DeleteForkchoiceAttestation(att ethpb.Att) error {
-	if att == nil || att.IsNil() {
-		return nil
-	}
-
-	id, err := attestation.NewId(att, attestation.Full)
-	if err != nil {
-		return errors.Wrap(err, "could not create attestation ID")
-	}
-
-	c.forkchoiceAttLock.Lock()
-	defer c.forkchoiceAttLock.Unlock()
-	delete(c.forkchoiceAtt, id)
-
-	return nil
-}
-
-// ForkchoiceAttestationCount returns the number of fork choice attestations key in the pool.
-func (c *AttCaches) ForkchoiceAttestationCount() int {
-	c.forkchoiceAttLock.RLock()
-	defer c.forkchoiceAttLock.RUnlock()
-	return len(c.forkchoiceAtt)
-}
--- a/beacon-chain/operations/attestations/kv/forkchoice_test.go
+++ b/beacon-chain/operations/attestations/kv/forkchoice_test.go
@@ -20,7 +20,7 @@ func TestKV_Forkchoice_CanSaveRetrieve(t *testing.T) {
 	atts := []ethpb.Att{att1, att2, att3}

 	for _, att := range atts {
-		require.NoError(t, cache.SaveForkchoiceAttestation(att))
+		require.NoError(t, cache.saveForkchoiceAttestation(att))
 	}

 	returned := cache.ForkchoiceAttestations()
@@ -41,7 +41,7 @@ func TestKV_Forkchoice_CanDelete(t *testing.T) {
 	atts := []ethpb.Att{att1, att2, att3}

 	for _, att := range atts {
-		require.NoError(t, cache.SaveForkchoiceAttestation(att))
+		require.NoError(t, cache.saveForkchoiceAttestation(att))
 	}

 	require.NoError(t, cache.DeleteForkchoiceAttestation(att1))
@@ -61,7 +61,7 @@ func TestKV_Forkchoice_CanCount(t *testing.T) {
 	atts := []*ethpb.Attestation{att1, att2, att3}

 	for _, att := range atts {
-		require.NoError(t, cache.SaveForkchoiceAttestation(att))
+		require.NoError(t, cache.saveForkchoiceAttestation(att))
 	}

 	require.Equal(t, 3, cache.ForkchoiceAttestationCount())
--- a/beacon-chain/operations/attestations/kv/kv.go
+++ b/beacon-chain/operations/attestations/kv/kv.go
@@ -8,6 +8,7 @@ import (
 	"time"

 	"github.com/patrickmn/go-cache"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/operations/attestations/attmap"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1/attestation"
@@ -21,8 +22,7 @@ type AttCaches struct {
 	aggregatedAtt      map[attestation.Id][]ethpb.Att
 	unAggregateAttLock sync.RWMutex
 	unAggregatedAtt    map[attestation.Id]ethpb.Att
-	forkchoiceAttLock  sync.RWMutex
-	forkchoiceAtt      map[attestation.Id]ethpb.Att
+	forkchoiceAtt      *attmap.Attestations
 	blockAttLock       sync.RWMutex
 	blockAtt           map[attestation.Id][]ethpb.Att
 	seenAtt            *cache.Cache
@@ -36,10 +36,35 @@ func NewAttCaches() *AttCaches {
 	pool := &AttCaches{
 		unAggregatedAtt: make(map[attestation.Id]ethpb.Att),
 		aggregatedAtt:   make(map[attestation.Id][]ethpb.Att),
-		forkchoiceAtt:   make(map[attestation.Id]ethpb.Att),
+		forkchoiceAtt:   attmap.New(),
 		blockAtt:        make(map[attestation.Id][]ethpb.Att),
 		seenAtt:         c,
 	}

 	return pool
 }
+
+// saveForkchoiceAttestation saves a forkchoice attestation.
+func (c *AttCaches) saveForkchoiceAttestation(att ethpb.Att) error {
+	return c.forkchoiceAtt.Save(att)
+}
+
+// SaveForkchoiceAttestations saves forkchoice attestations.
+func (c *AttCaches) SaveForkchoiceAttestations(att []ethpb.Att) error {
+	return c.forkchoiceAtt.SaveMany(att)
+}
+
+// ForkchoiceAttestations returns all forkchoice attestations.
+func (c *AttCaches) ForkchoiceAttestations() []ethpb.Att {
+	return c.forkchoiceAtt.GetAll()
+}
+
+// DeleteForkchoiceAttestation deletes a forkchoice attestation.
+func (c *AttCaches) DeleteForkchoiceAttestation(att ethpb.Att) error {
+	return c.forkchoiceAtt.Delete(att)
+}
+
+// ForkchoiceAttestationCount returns the number of forkchoice attestation keys.
+func (c *AttCaches) ForkchoiceAttestationCount() int {
+	return c.forkchoiceAtt.Count()
+}
--- a/beacon-chain/operations/attestations/kv/unaggregated.go
+++ b/beacon-chain/operations/attestations/kv/unaggregated.go
@@ -4,7 +4,6 @@ import (
 	"context"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
 	"github.com/prysmaticlabs/prysm/v5/monitoring/tracing/trace"
 	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
@@ -17,7 +16,7 @@ func (c *AttCaches) SaveUnaggregatedAttestation(att ethpb.Att) error {
 	if att == nil || att.IsNil() {
 		return nil
 	}
-	if helpers.IsAggregated(att) {
+	if att.IsAggregated() {
 		return errors.New("attestation is aggregated")
 	}

@@ -116,7 +115,7 @@ func (c *AttCaches) UnaggregatedAttestationsBySlotIndexElectra(

 	unAggregatedAtts := c.unAggregatedAtt
 	for _, a := range unAggregatedAtts {
-		if a.Version() == version.Electra && slot == a.GetData().Slot && a.CommitteeBitsVal().BitAt(uint64(committeeIndex)) {
+		if a.Version() >= version.Electra && slot == a.GetData().Slot && a.CommitteeBitsVal().BitAt(uint64(committeeIndex)) {
 			att, ok := a.(*ethpb.AttestationElectra)
 			// This will never fail in practice because we asserted the version
 			if ok {
@@ -133,8 +132,7 @@ func (c *AttCaches) DeleteUnaggregatedAttestation(att ethpb.Att) error {
 	if att == nil || att.IsNil() {
 		return nil
 	}
-
-	if helpers.IsAggregated(att) {
+	if att.IsAggregated() {
 		return errors.New("attestation is aggregated")
 	}

@@ -162,7 +160,7 @@ func (c *AttCaches) DeleteSeenUnaggregatedAttestations() (int, error) {

 	count := 0
 	for r, att := range c.unAggregatedAtt {
-		if att == nil || att.IsNil() || helpers.IsAggregated(att) {
+		if att == nil || att.IsNil() || att.IsAggregated() {
 			continue
 		}
 		if seen, err := c.hasSeenBit(att); err == nil && seen {
--- a/beacon-chain/operations/attestations/metrics.go
+++ b/beacon-chain/operations/attestations/metrics.go
@@ -30,6 +30,16 @@ var (
 		Name: "expired_block_atts_total",
 		Help: "The number of expired and deleted block attestations in the pool.",
 	})
+	attCount = promauto.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "attestations_in_pool_total",
+			Help: "The number of attestations in the pool.",
+		},
+	)
+	expiredAtts = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "expired_atts_total",
+		Help: "The number of expired and deleted attestations in the pool.",
+	})
 	batchForkChoiceAttsT1 = promauto.NewHistogram(
 		prometheus.HistogramOpts{
 			Name:    "aggregate_attestations_t1",
@@ -50,3 +60,8 @@ func (s *Service) updateMetrics() {
 	aggregatedAttsCount.Set(float64(s.cfg.Pool.AggregatedAttestationCount()))
 	unaggregatedAttsCount.Set(float64(s.cfg.Pool.UnaggregatedAttestationCount()))
 }
+
+func (s *Service) updateMetricsExperimental(numExpired uint64) {
+	attCount.Set(float64(s.cfg.Cache.Count()))
+	expiredAtts.Add(float64(numExpired))
+}
--- a/beacon-chain/operations/attestations/pool.go
+++ b/beacon-chain/operations/attestations/pool.go
@@ -37,7 +37,6 @@ type Pool interface {
 	BlockAttestations() []ethpb.Att
 	DeleteBlockAttestation(att ethpb.Att) error
 	// For attestations to be passed to fork choice.
-	SaveForkchoiceAttestation(att ethpb.Att) error
 	SaveForkchoiceAttestations(atts []ethpb.Att) error
 	ForkchoiceAttestations() []ethpb.Att
 	DeleteForkchoiceAttestation(att ethpb.Att) error
--- a/beacon-chain/operations/attestations/prepare_forkchoice.go
+++ b/beacon-chain/operations/attestations/prepare_forkchoice.go
@@ -61,11 +61,16 @@ func (s *Service) batchForkChoiceAtts(ctx context.Context) error {
 	ctx, span := trace.StartSpan(ctx, "Operations.attestations.batchForkChoiceAtts")
 	defer span.End()

-	if err := s.cfg.Pool.AggregateUnaggregatedAttestations(ctx); err != nil {
-		return err
+	var atts []ethpb.Att
+	if features.Get().EnableExperimentalAttestationPool {
+		atts = append(s.cfg.Cache.GetAll(), s.cfg.Cache.ForkchoiceAttestations()...)
+	} else {
+		if err := s.cfg.Pool.AggregateUnaggregatedAttestations(ctx); err != nil {
+			return err
+		}
+		atts = append(s.cfg.Pool.AggregatedAttestations(), s.cfg.Pool.BlockAttestations()...)
+		atts = append(atts, s.cfg.Pool.ForkchoiceAttestations()...)
 	}
-	atts := append(s.cfg.Pool.AggregatedAttestations(), s.cfg.Pool.BlockAttestations()...)
-	atts = append(atts, s.cfg.Pool.ForkchoiceAttestations()...)

 	attsById := make(map[attestation.Id][]ethpb.Att, len(atts))

@@ -92,9 +97,11 @@ func (s *Service) batchForkChoiceAtts(ctx context.Context) error {
 		}
 	}

-	for _, a := range s.cfg.Pool.BlockAttestations() {
-		if err := s.cfg.Pool.DeleteBlockAttestation(a); err != nil {
-			return err
+	if !features.Get().EnableExperimentalAttestationPool {
+		for _, a := range s.cfg.Pool.BlockAttestations() {
+			if err := s.cfg.Pool.DeleteBlockAttestation(a); err != nil {
+				return err
+			}
 		}
 	}

--- a/beacon-chain/operations/attestations/prune_expired.go
+++ b/beacon-chain/operations/attestations/prune_expired.go
@@ -9,8 +9,8 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/time/slots"
 )

-// pruneAttsPool prunes attestations pool on every slot interval.
-func (s *Service) pruneAttsPool() {
+// pruneExpired prunes attestations pool on every slot interval.
+func (s *Service) pruneExpired() {
 	ticker := time.NewTicker(s.cfg.pruneInterval)
 	defer ticker.Stop()
 	for {
@@ -25,6 +25,27 @@ func (s *Service) pruneAttsPool() {
 	}
 }

+// pruneExpiredExperimental prunes attestations on every prune interval.
+func (s *Service) pruneExpiredExperimental() {
+	ticker := time.NewTicker(s.cfg.pruneInterval)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			expirySlot, err := s.expirySlot()
+			if err != nil {
+				log.WithError(err).Error("Could not get expiry slot")
+				continue
+			}
+			numExpired := s.cfg.Cache.PruneBefore(expirySlot)
+			s.updateMetricsExperimental(numExpired)
+		case <-s.ctx.Done():
+			log.Debug("Context closed, exiting routine")
+			return
+		}
+	}
+}
+
 // This prunes expired attestations from the pool.
 func (s *Service) pruneExpiredAtts() {
 	aggregatedAtts := s.cfg.Pool.AggregatedAttestations()
@@ -84,3 +105,17 @@ func (s *Service) expiredPreDeneb(slot primitives.Slot) bool {
 	currentTime := uint64(prysmTime.Now().Unix())
 	return currentTime >= expirationTime
 }
+
+// Attestations for a slot before the returned slot are considered expired.
+func (s *Service) expirySlot() (primitives.Slot, error) {
+	currSlot := slots.CurrentSlot(s.genesisTime)
+	currEpoch := slots.ToEpoch(currSlot)
+	if currEpoch == 0 {
+		return 0, nil
+	}
+	if currEpoch < params.BeaconConfig().DenebForkEpoch {
+		// Safe to subtract because we exited early for epoch 0.
+		return currSlot - 31, nil
+	}
+	return slots.EpochStart(currEpoch - 1)
+}
--- a/beacon-chain/operations/attestations/prune_expired_test.go
+++ b/beacon-chain/operations/attestations/prune_expired_test.go
@@ -50,7 +50,7 @@ func TestPruneExpired_Ticker(t *testing.T) {
 	// Rewind back one epoch worth of time.
 	s.genesisTime = uint64(prysmTime.Now().Unix()) - uint64(params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot))

-	go s.pruneAttsPool()
+	go s.pruneExpired()

 	done := make(chan struct{}, 1)
 	async.RunEvery(ctx, 500*time.Millisecond, func() {
@@ -145,5 +145,4 @@ func TestPruneExpired_ExpiredDeneb(t *testing.T) {

 	assert.Equal(t, true, s.expired(secondEpochStart), "Should be expired")
 	assert.Equal(t, false, s.expired(thirdEpochStart), "Should not be expired")
-
 }
--- a/beacon-chain/operations/attestations/service.go
+++ b/beacon-chain/operations/attestations/service.go
@@ -9,7 +9,9 @@ import (
 	"time"

 	lru "github.com/hashicorp/golang-lru"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/cache"
 	lruwrpr "github.com/prysmaticlabs/prysm/v5/cache/lru"
+	"github.com/prysmaticlabs/prysm/v5/config/features"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 )

@@ -27,12 +29,13 @@ type Service struct {

 // Config options for the service.
 type Config struct {
+	Cache               *cache.AttestationCache
 	Pool                Pool
 	pruneInterval       time.Duration
 	InitialSyncComplete chan struct{}
 }

-// NewService instantiates a new attestation pool service instance that will
+// NewService instantiates a new attestation service instance that will
 // be registered into a running beacon node.
 func NewService(ctx context.Context, cfg *Config) (*Service, error) {
 	cache := lruwrpr.New(forkChoiceProcessedAttsSize)
@@ -58,7 +61,12 @@ func (s *Service) Start() {
 		return
 	}
 	go s.prepareForkChoiceAtts()
-	go s.pruneAttsPool()
+
+	if features.Get().EnableExperimentalAttestationPool {
+		go s.pruneExpiredExperimental()
+	} else {
+		go s.pruneExpired()
+	}
 }

 // waitForSync waits until the beacon node is synced to the latest head.
--- a/beacon-chain/p2p/broadcaster.go
+++ b/beacon-chain/p2p/broadcaster.go
@@ -163,7 +163,7 @@ func (s *Service) broadcastSyncCommittee(ctx context.Context, subnet uint64, sMs

 	// Ensure we have peers with this subnet.
 	// This adds in a special value to the subnet
-	// to ensure that we can re-use the same subnet locker.
+	// to ensure that we can reuse the same subnet locker.
 	wrappedSubIdx := subnet + syncLockerVal
 	s.subnetLocker(wrappedSubIdx).RLock()
 	hasPeer := s.hasPeerWithSubnet(syncCommitteeToTopic(subnet, forkDigest))
--- a/beacon-chain/p2p/broadcaster_test.go
+++ b/beacon-chain/p2p/broadcaster_test.go
@@ -209,7 +209,7 @@ func TestService_BroadcastAttestation(t *testing.T) {

 func TestService_BroadcastAttestationWithDiscoveryAttempts(t *testing.T) {
 	// Setup bootnode.
-	cfg := &Config{}
+	cfg := &Config{PingInterval: testPingInterval}
 	port := 2000
 	cfg.UDPPort = uint(port)
 	_, pkey := createAddrAndPrivKey(t)
@@ -234,12 +234,16 @@ func TestService_BroadcastAttestationWithDiscoveryAttempts(t *testing.T) {
 	cfg = &Config{
 		Discv5BootStrapAddrs: []string{bootNode.String()},
 		MaxPeers:             2,
+		PingInterval:         testPingInterval,
 	}
 	// Setup 2 different hosts
 	for i := 1; i <= 2; i++ {
 		h, pkey, ipAddr := createHost(t, port+i)
 		cfg.UDPPort = uint(port + i)
 		cfg.TCPPort = uint(port + i)
+		if len(listeners) > 0 {
+			cfg.Discv5BootStrapAddrs = append(cfg.Discv5BootStrapAddrs, listeners[len(listeners)-1].Self().String())
+		}
 		s := &Service{
 			cfg:                   cfg,
 			genesisTime:           genesisTime,
--- a/beacon-chain/p2p/config.go
+++ b/beacon-chain/p2p/config.go
@@ -1,6 +1,8 @@
 package p2p

 import (
+	"time"
+
 	statefeed "github.com/prysmaticlabs/prysm/v5/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/startup"
@@ -15,6 +17,7 @@ type Config struct {
 	NoDiscovery          bool
 	EnableUPnP           bool
 	StaticPeerID         bool
+	DisableLivenessCheck bool
 	StaticPeers          []string
 	Discv5BootStrapAddrs []string
 	RelayNodeAddr        string
@@ -27,6 +30,7 @@ type Config struct {
 	QUICPort             uint
 	TCPPort              uint
 	UDPPort              uint
+	PingInterval         time.Duration
 	MaxPeers             uint
 	QueueSize            uint
 	AllowListCIDR        string
--- a/beacon-chain/p2p/discovery.go
+++ b/beacon-chain/p2p/discovery.go
@@ -418,8 +418,10 @@ func (s *Service) createListener(
 	}

 	dv5Cfg := discover.Config{
-		PrivateKey: privKey,
-		Bootnodes:  bootNodes,
+		PrivateKey:              privKey,
+		Bootnodes:               bootNodes,
+		PingInterval:            s.cfg.PingInterval,
+		NoFindnodeLivenessCheck: s.cfg.DisableLivenessCheck,
 	}

 	listener, err := discover.ListenV5(conn, localNode, dv5Cfg)
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
james-prysm	a44fc07565	draft for increasing gas limit	2025-01-16 11:49:02 -06:00
james-prysm	0b16c79c35	fix e2e scenario evaluators (#14798 ) * make fork evaluators conditional on fork for scenario tests * changelog	2025-01-16 04:38:26 +00:00
terence	dc002c2806	Truncate ExtraData to 32 bytes for to satisfy SSZ marshal (#14803 )	2025-01-16 00:14:56 +00:00
kasey	e7e48dcaf9	version pin unclog release (#14802 ) Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>	2025-01-15 23:50:10 +00:00
james-prysm	8f43f6cc84	adding in error for generic check (#14801 )	2025-01-15 21:36:09 +00:00
Manu NALEPA	e07341e1d5	`ToBlinded`: Use Fulu. (#14797 ) * `ToBlinded`: Use Fulu. * Fix Sammy's comment. * `unmarshalState`: Use `hasFuluKey`.	2025-01-15 19:50:48 +00:00
Preston Van Loon	ef293e52f8	Use ip.addr.tools for DNS resolution test in p2p (#14800 ) * Use ip.addr.tools for DNS resolution test in p2p * Changelog fragment	2025-01-15 18:07:00 +00:00
Jun Song	72cc63a6a3	Clean `TestCanUpgrade` tests (#14791 ) Clean TestCanUpgrade* tests * Add new changelog file	2025-01-15 15:42:21 +00:00
Jun Song	34ff4c3ea9	Replace new `exampleIP` for `example.org` (#14795 ) * Replace new exampleIP for example.org * Add changelog	2025-01-15 06:14:25 +00:00
kasey	e8c968326a	switch to unclog latest release instead of run artifact (#14793 ) * use latest unclog release instead of run artifact * add missing changelog entries to pre-unclog starter pack --------- Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>	2025-01-14 21:47:20 +00:00
kasey	2000ef457b	Move prysm to unclog for changelog management (#14782 ) Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>	2025-01-14 18:22:38 +00:00
james-prysm	e36564c4d3	goethereum dependency to v1.14~ (#14351 ) * updating the goethereum dependency * fixing dependencies * reverting workspace * more fixes, work in progress * trying with upgraded geth version * fixing deprecated functions except for the time related ones on eth1 distance due to time issues * fixing time issues * gaz * fixing test and upgrading some dependencies and reverting others * Disable cgo in hid, delete old vendored usb library * changelog * rolling back dependencies * fixing go mod tidy * Geth v1.13.6 * fix tests * Add ping interval, set to 500ms for tests. This didnt work * Update to v1.14.8 * Spread it out to different bootnodes * Fix it * Remove Memsize * Update all out of date dependencies * Fix geth body change * Fix Test * Fix Build * Fix Tests * Fix Tests Again * Fix Tests Again * Fix Tests * Fix Test * Copy USB Package for HID * Push it up * Finally fix all tests with felix's changes * updating geth dependency * Update go-ethereum to v1.14.11 * fixing import * reverting blob change * fixing Implicit memory aliasing in for loop. * WIP changes * wip getting a little further on e2e runs * getting a little further * getting a little further * setting everything to capella * more partial fixes * more fixes but still WIP * fixing access list transactions" * some cleanup * making configs dynamic * reverting time * skip lower bound in builder * updating to geth v1.14.12 * fixing verify blob to pointer * go mod tidy * fixing linting * missed removing another terminal difficulty item * another missed update * updating more dependencies to fix cicd * fixing holiman dependency update * downgrading geth to 1.14.11 due to p2p loop issue * reverting builder middleware caused by downgrade * fixing more rollback issues * upgrading back to 1.14.12 after discussing with preston * mod tidy * gofmt * partial review feedback * trying to start e2e from bellatrix instead * reverting some changes --------- Co-authored-by: Preston Van Loon <preston@pvl.dev> Co-authored-by: nisdas <nishdas93@gmail.com>	2025-01-14 08:35:49 +00:00
terence	e5784d09f0	Update spec test to v1.5.0-beta.0 (#14788 )	2025-01-13 20:05:34 +00:00
terence	e577bb0dcf	Revert `BlobSidecarsByRoot/Range` version to v1 (#14785 ) * Update blobs by range rpc topics to v1 * Update blobs by range rpc topics to v1 * RPC handler comments: Use "Added", "Modified" and "Upgraded". - Added: No message with this message name was previously existing. - Upgraded: A message with this message name was existing in the previous fork, but the schema version is upgraded in the current fork. - Modified: The couple message name, schema version is the same than in the previous fork, but the implementation of the handler is modified in the current fork. --------- Co-authored-by: Manu NALEPA <enalepa@offchainlabs.com>	2025-01-13 16:58:44 +00:00
Radosław Kapka	153d1872ae	Separate type for unaggregated network attestations (#14659 ) * definitions and gossip * validator * broadcast * broadcast the correct att depending on version * small updates * don't check bits after Electra * nitpick * tests * changelog <3 * review * more review * review yet again * try a different design * fix gossip issues * cleanup * tests * reduce cognitive complexity * Preston's review * move changelog entry to unreleased section * fix pending atts pool issues * reviews * Potuz's comments * test fixes	2025-01-13 16:48:20 +00:00
terence	80aa811ab9	Fix kzg commitment inclusion proof depth minimal value (#14787 )	2025-01-13 15:51:30 +00:00
Bastin	39cf2c8f06	Read LC Bootstraps from DB (#14718 ) * fix bootstrap handler * add tests for get bootstrap handler * changelog * make CreateDefaultLightClientBootstrap private * remove fulu test --------- Co-authored-by: Radosław Kapka <rkapka@wp.pl>	2025-01-10 16:51:55 +00:00
Bastin	e99df5e489	Save LC Bootstrap DB Space Optimization (#14775 ) * add db optimization altair * add db optimization * add tests * fix tests * fix changelog * remove debug code * remove unused code * fix comment * remove unused code	2025-01-09 18:00:08 +00:00
oftenoccur	393e63e8e5	refactor: using slices.Contains to simplify the code (#14781 ) Signed-off-by: oftenoccur <ezc5@sina.com> Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>	2025-01-09 00:04:45 +00:00
Manu NALEPA	c48d40907c	Add Fulu fork boilerplate (#14771 ) * Prepare for future fork boilerplate. * Implement the Fulu fork boilerplate. * `Upgraded state to <fork> log`: Move from debug to info. Rationale: This log is the only one notifying the user a new fork happened. A new fork is always a little bit stressful for a node operator. Having at least one log indicating the client switched fork is something useful. * Update testing/util/helpers.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Fix Radek's comment. * Fix Radek's comment. * Update beacon-chain/state/state-native/state_trie.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Update beacon-chain/state/state-native/state_trie.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Fix Radek's comment. * Fix Radek's comment. * Fix Radek's comment. * Remove Electra struct type aliasing. --------- Co-authored-by: Radosław Kapka <rkapka@wp.pl>	2025-01-07 20:09:12 +00:00
Nishant Das	a21f544219	Update to v0.33 (#14780 )	2025-01-07 09:20:45 +00:00
Preston Van Loon	705a9e8dcd	Electra: Spec review of process_slashings (#14766 ) * Electra: Review process_slashings * Update signature not to return the state, there is no need * Update CHANGELOG.md	2025-01-06 13:24:58 +00:00
Skylar Ray	2dcb015470	Update CHANGELOG.md (#14753 )	2025-01-06 13:09:25 +00:00
Nishant Das	211e1a4b7c	Close Streams For Metadata Requests Better (#14776 ) * Close streams better * Changelog	2025-01-06 11:01:58 +00:00
Nishant Das	1efca9c28d	Add Ability to Trace IDONTWANT Control Messages (#14778 ) * Trace IDONTWANT Requests * Changelog	2025-01-06 10:13:22 +00:00
Nishant Das	97d7ca828b	Security Update For Dependencies (#14777 ) * Update Golang Crypto * Changelog	2025-01-06 10:00:59 +00:00
Preston Van Loon	31df250496	Electra: Update spec definition for process_registry_updates (#14767 ) * Electra: review process_registry_updates * Update CHANGELOG.md	2025-01-03 16:15:02 +00:00
Manu NALEPA	8a439a6f5d	Simplify next Fork boilerplate creation. (#14761 ) * Simplify next Fork boilerplate creation. * Update beacon-chain/blockchain/execution_engine.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Update beacon-chain/blockchain/execution_engine.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Update beacon-chain/blockchain/execution_engine.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Update beacon-chain/state/state-native/spec_parameters.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Update beacon-chain/state/state-native/spec_parameters.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Update beacon-chain/state/state-native/spec_parameters.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Update beacon-chain/state/state-native/spec_parameters.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Fix Radek's comments. --------- Co-authored-by: Radosław Kapka <rkapka@wp.pl>	2025-01-03 14:39:08 +00:00
Radosław Kapka	8cff9356f1	Remove duplicate imports (#14772 )	2025-01-03 11:42:14 +00:00
Nishant Das	afeb05c9a1	Update Go-Libp2p-Pubsub (#14770 ) * Update to Current Master Head * Changelog * Update CHANGELOG.md	2025-01-03 10:52:46 +00:00
Preston Van Loon	fa16232924	Electra: Update spec definition for process_epoch (#14768 ) * Electra: Review process_epoch * Update CHANGELOG.md	2025-01-03 09:40:53 +00:00
Preston Van Loon	1f720bdbf4	Fix all typos (#14769 )	2025-01-03 09:40:13 +00:00
Brindrajsinh Chauhan	79ea77ff57	update go version to 1.22.10 (#14729 ) * update to go 1.22.10 * update change log --------- Co-authored-by: Preston Van Loon <pvanloon@offchainlabs.com>	2025-01-02 23:07:38 +00:00
Radosław Kapka	d35cd0788e	Remove v2 protos (#14765 ) * Remove v2 protos * changelog <3	2025-01-02 19:40:07 +00:00
Preston Van Loon	093e3df80a	Remove slashingMultiplier argument from ProcessSlashings (#14762 ) * Remove slashingMultiplier argument from ProcessSlashings * Update CHANGELOG.md	2025-01-01 18:21:52 +00:00
Manu NALEPA	699a3b07a7	SSZ generation: Remove the `// Hash: ...` header. (#14760 ) * `update-go-ssz.sh`: Remove the `// Hash: ...` line from the generated files header. * Generate SSZ files.	2024-12-31 12:07:41 +00:00
Manu NALEPA	937d441e2e	`registerSubscribers`: Register correctly. (#14759 ) Issue before this commit: The `currentSlot` in the `getSubnetsToSubscribe` is really set to the current slot. So, even if the `registerSubscribers` function is called one epoch in advance, as done in `registerForUpcomingFork`, then `currentSlot` will still be - really - the current slot. ==> The new blobs subnets will be subscribed only at the start of the Electra fork, and not one epoch in advance. With this commit: The new blobs subnets will be effectively subscribed one epoch in advance.	2024-12-31 08:42:56 +00:00
terence	ead08d56d0	Implement EIP7691: Blob throughput increase (#14750 ) * Add EIP-7691 blob throughput increase * Review feedback * Factorize blobs subscriptions. --------- Co-authored-by: Manu NALEPA <enalepa@offchainlabs.com>	2024-12-30 19:23:56 +00:00
Savely	f55e62287a	Fix Command Flag Typos and Syntax Issues (#14758 ) * Update INTEROP.md * Update INTEROP.md --------- Co-authored-by: Radosław Kapka <rkapka@wp.pl>	2024-12-30 12:29:43 +00:00
Manu NALEPA	c7b2838873	Re-organize the content of the `.proto` files. (#14755 ) Re-organize thet content of the `.proto` files. The content of the `.proto` files is sorted by hard fork, then with a top-down fashion. Sorting first by hard fork lets the reader to easily see new or modified fields. Then, sorting with a top-down fashion lets the user to first see the big picture, then to dive into details. Also, the `new in <hard fork>` mentions are only written for the given hard fork. Thus, it'll avoid in the future the majority of the fields, not initially present in phase 0, to have the `new in <hard fork> mention`. This commit does not bring any new functional change. * Update proto/prysm/v1alpha1/attestation.proto Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Update proto/prysm/v1alpha1/beacon_state.proto Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Fix Radek's comment. --------- Co-authored-by: Radosław Kapka <rkapka@wp.pl>	2024-12-30 12:11:10 +00:00
Rupam Dey	9e7c1d6af6	Light client: add better error handling (#14749 ) * add better error handling * changelog	2024-12-26 20:46:29 +00:00
terence	6ce6b869e5	Implement consensus spec v1.5.0-alpha.10 (#14733 ) * Use 16 bit random value * enforce 0x02 credentials for consolidations * Limit consolidating balance by validator effective balance * Update max blob commitment size * Fix next sync committee indices * Bytes to little endian * Handle proposer computations in between forks * Fix config and tests Fix tests Fix tests * Fix test stream events by properly set effective balance Fix test stream events by properly set effective balance * Preallocate buffers to avoid repeated allocations * Potuz's feedback * Use 16 bit random value * enforce 0x02 credentials for consolidations * Limit consolidating balance by validator effective balance * Update max blob commitment size * Fix next sync committee indices * Bytes to little endian * Handle proposer computations in between forks * Fix config and tests Fix tests Fix tests * Fix test stream events by properly set effective balance Fix test stream events by properly set effective balance * Preallocate buffers to avoid repeated allocations * Potuz's feedback * Fix change log	2024-12-23 17:32:41 +00:00
Charlton Liv	dbd53bd70d	SA1019 fix: `math/rand` to `crypto/rand` (#14747 ) * math/rand to crypto/rand * Update CHANGELOG.md * Update CHANGELOG.md --------- Co-authored-by: terence <terence@prysmaticlabs.com> Co-authored-by: Radosław Kapka <rkapka@wp.pl>	2024-12-23 10:18:38 +00:00
Radosław Kapka	d04b361cc3	Redesign of the attestation pool (#14324 ) * Rename existing AttestationCache * Cache with simple Add * fix import cycle * logic for unaggregated, aggregated and block attestations * some small fixes * remove Seen * finishing touches * feature flag * extract forkchoice atts to separate type * gate new functionality behind feature flag * revert test files * preparing for review * change Id to [32]byte * Potuz's review * Potuz's review pt 2 * Nishant's review * keep flat list of atts * fix ForkchoiceAttestations() function * Tests for Add, GetAll, Count * Tests for remaining functions * use DeepEqual * fix tests * documentation * changelog <3 * v2 handlers * nil check for forkchoice atts * guard against 0 bits set * fix failing test * Preston's review * better godocs	2024-12-23 09:59:32 +00:00