Use Head to validate sidecars when possible (#15977)

* Use Head to validate sidecars when possible

🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>

* LazyHeadStateProvider that avoids service registry

* Remove extra file

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: james-prysm <90280386+james-prysm@users.noreply.github.com>
Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>

beacon-chain/execution/BUILD.bazel

@@ -100,6 +100,7 @@ go_test(
     deps = [
         "//async/event:go_default_library",
         "//beacon-chain/blockchain/kzg:go_default_library",
+        "//beacon-chain/blockchain/testing:go_default_library",
         "//beacon-chain/cache/depositsnapshot:go_default_library",
         "//beacon-chain/core/feed:go_default_library",
         "//beacon-chain/core/feed/state:go_default_library",

beacon-chain/execution/service_test.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/OffchainLabs/prysm/v7/async/event"
+	chainMock "github.com/OffchainLabs/prysm/v7/beacon-chain/blockchain/testing"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/cache/depositsnapshot"
 	dbutil "github.com/OffchainLabs/prysm/v7/beacon-chain/db/testing"
 	mockExecution "github.com/OffchainLabs/prysm/v7/beacon-chain/execution/testing"
@@ -99,7 +100,7 @@ func TestStart_OK(t *testing.T) {
 	c := startup.NewClockSynchronizer()
 	require.NoError(t, c.SetClock(startup.NewClock(time.Unix(0, 0), [32]byte{})))
 	waiter := verification.NewInitializerWaiter(
-		c, forkchoice.NewROForkChoice(nil), nil)
+		c, forkchoice.NewROForkChoice(nil), nil, &chainMock.ChainService{})
 
 	web3Service, err := NewService(t.Context(),
 		WithHttpEndpoint(endpoint),

beacon-chain/node/node.go

@@ -124,6 +124,7 @@ type BeaconNode struct {
 	DataColumnStorage        *filesystem.DataColumnStorage
 	DataColumnStorageOptions []filesystem.DataColumnStorageOption
 	verifyInitWaiter         *verification.InitializerWaiter
+	lhsp                     *verification.LazyHeadStateProvider
 	syncChecker              *initialsync.SyncChecker
 	slasherEnabled           bool
 	lcStore                  *lightclient.Store
@@ -230,8 +231,9 @@ func New(cliCtx *cli.Context, cancel context.CancelFunc, opts ...Option) (*Beaco
 		return nil, errors.Wrap(err, "could not start modules")
 	}
 
+	beacon.lhsp = &verification.LazyHeadStateProvider{}
 	beacon.verifyInitWaiter = verification.NewInitializerWaiter(
-		beacon.clockWaiter, forkchoice.NewROForkChoice(beacon.forkChoicer), beacon.stateGen)
+		beacon.clockWaiter, forkchoice.NewROForkChoice(beacon.forkChoicer), beacon.stateGen, beacon.lhsp)
 
 	beacon.BackfillOpts = append(
 		beacon.BackfillOpts,
@@ -749,6 +751,7 @@ func (b *BeaconNode) registerBlockchainService(fc forkchoice.ForkChoicer, gs *st
 	if err != nil {
 		return errors.Wrap(err, "could not register blockchain service")
 	}
+	b.lhsp.HeadStateProvider = blockchainService
 	return b.services.RegisterService(blockchainService)
 }
 

beacon-chain/sync/data_column_sidecars_test.go

@@ -154,7 +154,7 @@ func TestFetchDataColumnSidecars(t *testing.T) {
 	err = gs.SetClock(startup.NewClock(time.Unix(4113849600, 0), [fieldparams.RootLength]byte{}))
 	require.NoError(t, err)
 
-	waiter := verification.NewInitializerWaiter(gs, nil, nil)
+	waiter := verification.NewInitializerWaiter(gs, nil, nil, nil)
 	initializer, err := waiter.WaitForInitializer(t.Context())
 	require.NoError(t, err)
 
@@ -787,7 +787,7 @@ func TestVerifyDataColumnSidecarsByPeer(t *testing.T) {
 		err := gs.SetClock(startup.NewClock(time.Unix(4113849600, 0), [fieldparams.RootLength]byte{}))
 		require.NoError(t, err)
 
-		waiter := verification.NewInitializerWaiter(gs, nil, nil)
+		waiter := verification.NewInitializerWaiter(gs, nil, nil, nil)
 		initializer, err := waiter.WaitForInitializer(t.Context())
 		require.NoError(t, err)
 
@@ -832,7 +832,7 @@ func TestVerifyDataColumnSidecarsByPeer(t *testing.T) {
 		err := gs.SetClock(startup.NewClock(time.Unix(4113849600, 0), [fieldparams.RootLength]byte{}))
 		require.NoError(t, err)
 
-		waiter := verification.NewInitializerWaiter(gs, nil, nil)
+		waiter := verification.NewInitializerWaiter(gs, nil, nil, nil)
 		initializer, err := waiter.WaitForInitializer(t.Context())
 		require.NoError(t, err)
 

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

@@ -174,7 +174,7 @@ func TestService_InitStartStop(t *testing.T) {
 				StateNotifier:       &mock.MockStateNotifier{},
 				InitialSyncComplete: make(chan struct{}),
 			})
-			s.verifierWaiter = verification.NewInitializerWaiter(gs, nil, nil)
+			s.verifierWaiter = verification.NewInitializerWaiter(gs, nil, nil, nil)
 			time.Sleep(500 * time.Millisecond)
 			assert.NotNil(t, s)
 			if tt.setGenesis != nil {
@@ -217,7 +217,7 @@ func TestService_waitForStateInitialization(t *testing.T) {
 			counter:      ratecounter.NewRateCounter(counterSeconds * time.Second),
 			genesisChan:  make(chan time.Time),
 		}
-		s.verifierWaiter = verification.NewInitializerWaiter(cs, nil, nil)
+		s.verifierWaiter = verification.NewInitializerWaiter(cs, nil, nil, nil)
 		return s, cs
 	}
 
@@ -786,7 +786,7 @@ func TestFetchOriginColumns(t *testing.T) {
 		err = gs.SetClock(startup.NewClock(time.Unix(4113849600, 0), [fieldparams.RootLength]byte{}))
 		require.NoError(t, err)
 
-		waiter := verification.NewInitializerWaiter(gs, nil, nil)
+		waiter := verification.NewInitializerWaiter(gs, nil, nil, nil)
 		initializer, err := waiter.WaitForInitializer(t.Context())
 		require.NoError(t, err)
 

beacon-chain/sync/rpc_status_test.go

@@ -332,7 +332,7 @@ func TestHandshakeHandlers_Roundtrip(t *testing.T) {
 	markInitSyncComplete(t, r)
 	clock := startup.NewClockSynchronizer()
 	require.NoError(t, clock.SetClock(startup.NewClock(time.Now(), [32]byte{})))
-	r.verifierWaiter = verification.NewInitializerWaiter(clock, chain.ForkChoiceStore, r.cfg.stateGen)
+	r.verifierWaiter = verification.NewInitializerWaiter(clock, chain.ForkChoiceStore, r.cfg.stateGen, chain)
 	p1.Digest, err = r.currentForkDigest()
 	require.NoError(t, err)
 
@@ -354,7 +354,7 @@ func TestHandshakeHandlers_Roundtrip(t *testing.T) {
 	markInitSyncComplete(t, r2)
 	clock = startup.NewClockSynchronizer()
 	require.NoError(t, clock.SetClock(startup.NewClock(time.Now(), [32]byte{})))
-	r2.verifierWaiter = verification.NewInitializerWaiter(clock, chain2.ForkChoiceStore, r2.cfg.stateGen)
+	r2.verifierWaiter = verification.NewInitializerWaiter(clock, chain2.ForkChoiceStore, r2.cfg.stateGen, chain2)
 
 	p2.Digest, err = r.currentForkDigest()
 	require.NoError(t, err)
@@ -948,7 +948,7 @@ func TestStatusRPCRequest_BadPeerHandshake(t *testing.T) {
 	markInitSyncComplete(t, r)
 	clock := startup.NewClockSynchronizer()
 	require.NoError(t, clock.SetClock(startup.NewClock(time.Now(), [32]byte{})))
-	r.verifierWaiter = verification.NewInitializerWaiter(clock, chain.ForkChoiceStore, r.cfg.stateGen)
+	r.verifierWaiter = verification.NewInitializerWaiter(clock, chain.ForkChoiceStore, r.cfg.stateGen, chain)
 
 	go r.Start()
 

beacon-chain/sync/validate_bls_to_execution_change_test.go

@@ -433,7 +433,7 @@ func TestService_ValidateBlsToExecutionChange(t *testing.T) {
 				tt.clock = startup.NewClock(time.Now(), [32]byte{})
 			}
 			require.NoError(t, cw.SetClock(tt.clock))
-			svc.verifierWaiter = verification.NewInitializerWaiter(cw, chainService.ForkChoiceStore, svc.cfg.stateGen)
+			svc.verifierWaiter = verification.NewInitializerWaiter(cw, chainService.ForkChoiceStore, svc.cfg.stateGen, chainService)
 			go svc.Start()
 
 			marshalledObj, err := tt.args.msg.MarshalSSZ()

beacon-chain/sync/validate_sync_committee_message_test.go

@@ -411,7 +411,7 @@ func TestService_ValidateSyncCommitteeMessage(t *testing.T) {
 			svc, tt.args.topic, clock = tt.setupSvc(svc, tt.args.msg, tt.args.topic)
 			markInitSyncComplete(t, svc)
 			require.NoError(t, cw.SetClock(clock))
-			svc.verifierWaiter = verification.NewInitializerWaiter(cw, chainService.ForkChoiceStore, svc.cfg.stateGen)
+			svc.verifierWaiter = verification.NewInitializerWaiter(cw, chainService.ForkChoiceStore, svc.cfg.stateGen, chainService)
 			go svc.Start()
 
 			marshalledObj, err := tt.args.msg.MarshalSSZ()

beacon-chain/sync/validate_sync_contribution_proof_test.go

@@ -855,7 +855,7 @@ func TestService_ValidateSyncContributionAndProof(t *testing.T) {
 			var clock *startup.Clock
 			svc, clock = tt.setupSvc(svc, tt.args.msg)
 			require.NoError(t, cw.SetClock(clock))
-			svc.verifierWaiter = verification.NewInitializerWaiter(cw, chainService.ForkChoiceStore, svc.cfg.stateGen)
+			svc.verifierWaiter = verification.NewInitializerWaiter(cw, chainService.ForkChoiceStore, svc.cfg.stateGen, chainService)
 			markInitSyncComplete(t, svc)
 			go svc.Start()
 			marshalledObj, err := tt.args.msg.MarshalSSZ()

beacon-chain/verification/BUILD.bazel

@@ -69,6 +69,7 @@ go_test(
         "//beacon-chain/forkchoice/types:go_default_library",
         "//beacon-chain/startup:go_default_library",
         "//beacon-chain/state:go_default_library",
+        "//beacon-chain/state/state-native:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",

beacon-chain/verification/blob_test.go

@@ -11,6 +11,7 @@ import (
 	forkchoicetypes "github.com/OffchainLabs/prysm/v7/beacon-chain/forkchoice/types"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/startup"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/state"
+	state_native "github.com/OffchainLabs/prysm/v7/beacon-chain/state/state-native"
 	"github.com/OffchainLabs/prysm/v7/config/params"
 	"github.com/OffchainLabs/prysm/v7/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v7/consensus-types/primitives"
@@ -626,6 +627,45 @@ func (sbr *mockStateByRooter) StateByRoot(ctx context.Context, root [32]byte) (s
 
 var _ StateByRooter = &mockStateByRooter{}
 
+type mockHeadStateProvider struct {
+	headRoot          []byte
+	headSlot          primitives.Slot
+	headState         state.BeaconState
+	headStateReadOnly state.ReadOnlyBeaconState
+}
+
+func (m *mockHeadStateProvider) HeadRoot(_ context.Context) ([]byte, error) {
+	if m.headRoot != nil {
+		return m.headRoot, nil
+	}
+	root := make([]byte, 32)
+	root[0] = 0xff
+	return root, nil
+}
+
+func (m *mockHeadStateProvider) HeadSlot() primitives.Slot {
+	if m.headSlot == 0 {
+		return 1000
+	}
+	return m.headSlot
+}
+
+func (m *mockHeadStateProvider) HeadState(_ context.Context) (state.BeaconState, error) {
+	if m.headState == nil {
+		return nil, errors.New("head state not available")
+	}
+	return m.headState, nil
+}
+
+func (m *mockHeadStateProvider) HeadStateReadOnly(_ context.Context) (state.ReadOnlyBeaconState, error) {
+	if m.headStateReadOnly == nil {
+		return nil, errors.New("head state read only not available")
+	}
+	return m.headStateReadOnly, nil
+}
+
+var _ HeadStateProvider = &mockHeadStateProvider{}
+
 func sbrErrorIfCalled(t *testing.T) sbrfunc {
 	return func(_ context.Context, _ [32]byte) (state.BeaconState, error) {
 		t.Error("StateByRoot should not have been called")
@@ -643,15 +683,56 @@ func sbrNotFound(t *testing.T, expectedRoot [32]byte) *mockStateByRooter {
 }
 
 func sbrForValOverride(idx primitives.ValidatorIndex, val *ethpb.Validator) *mockStateByRooter {
+	return sbrForValOverrideWithT(nil, idx, val)
+}
+
+func sbrForValOverrideWithT(t testing.TB, idx primitives.ValidatorIndex, val *ethpb.Validator) *mockStateByRooter {
 	return &mockStateByRooter{sbr: func(_ context.Context, root [32]byte) (state.BeaconState, error) {
-		return &validxStateOverride{vals: map[primitives.ValidatorIndex]*ethpb.Validator{
+		// Use a real deterministic state so that helpers.BeaconProposerIndexAtSlot works correctly
-			idx: val,
+		numValidators := uint64(idx + 1)
-		}}, nil
+		if numValidators < 64 {
+			numValidators = 64
+		}
+
+		var st state.BeaconState
+		var err error
+		if t != nil {
+			st, _ = util.DeterministicGenesisStateFulu(t, numValidators)
+		} else {
+			// Fallback for blob tests that don't need the full state
+			return &validxStateOverride{
+				slot: 0,
+				vals: map[primitives.ValidatorIndex]*ethpb.Validator{
+					idx: val,
+				},
+			}, nil
+		}
+
+		// Override the specific validator if provided
+		if val != nil {
+			vals := st.Validators()
+			if idx < primitives.ValidatorIndex(len(vals)) {
+				vals[idx] = val
+				// Ensure the validator is active
+				if vals[idx].ActivationEpoch > 0 {
+					vals[idx].ActivationEpoch = 0
+				}
+				if vals[idx].ExitEpoch == 0 || vals[idx].ExitEpoch < params.BeaconConfig().FarFutureEpoch {
+					vals[idx].ExitEpoch = params.BeaconConfig().FarFutureEpoch
+				}
+				if vals[idx].EffectiveBalance == 0 {
+					vals[idx].EffectiveBalance = params.BeaconConfig().MaxEffectiveBalance
+				}
+				_ = st.SetValidators(vals)
+			}
+		}
+		return st, err
 	}}
 }
 
 type validxStateOverride struct {
 	state.BeaconState
+	slot primitives.Slot
 	vals map[primitives.ValidatorIndex]*ethpb.Validator
 }
 
@@ -665,6 +746,105 @@ func (v *validxStateOverride) ValidatorAtIndex(idx primitives.ValidatorIndex) (*
 	return val, nil
 }
 
+func (v *validxStateOverride) Slot() primitives.Slot {
+	return v.slot
+}
+
+func (v *validxStateOverride) Version() int {
+	// Return Fulu version (6) as default for tests
+	return 6
+}
+
+func (v *validxStateOverride) Validators() []*ethpb.Validator {
+	// Return all validators in the map as a slice
+	maxIdx := primitives.ValidatorIndex(0)
+	for idx := range v.vals {
+		if idx > maxIdx {
+			maxIdx = idx
+		}
+	}
+	// Ensure we have at least 64 validators for a valid beacon state
+	numValidators := maxIdx + 1
+	if numValidators < 64 {
+		numValidators = 64
+	}
+	validators := make([]*ethpb.Validator, numValidators)
+	for i := range validators {
+		if val, ok := v.vals[primitives.ValidatorIndex(i)]; ok {
+			validators[i] = val
+		} else {
+			// Default validator for indices we don't care about
+			validators[i] = &ethpb.Validator{
+				ActivationEpoch:  0,
+				ExitEpoch:        params.BeaconConfig().FarFutureEpoch,
+				EffectiveBalance: params.BeaconConfig().MaxEffectiveBalance,
+			}
+		}
+	}
+	return validators
+}
+
+func (v *validxStateOverride) RandaoMixAtIndex(idx uint64) ([]byte, error) {
+	// Return a zero mix for simplicity in tests
+	return make([]byte, 32), nil
+}
+
+func (v *validxStateOverride) NumValidators() int {
+	return len(v.Validators())
+}
+
+func (v *validxStateOverride) ValidatorAtIndexReadOnly(idx primitives.ValidatorIndex) (state.ReadOnlyValidator, error) {
+	validators := v.Validators()
+	if idx >= primitives.ValidatorIndex(len(validators)) {
+		return nil, fmt.Errorf("validator index %d out of range", idx)
+	}
+	return state_native.NewValidator(validators[idx])
+}
+
+func (v *validxStateOverride) IsNil() bool {
+	return false
+}
+
+func (v *validxStateOverride) LatestBlockHeader() *ethpb.BeaconBlockHeader {
+	// Return a minimal block header for tests
+	return &ethpb.BeaconBlockHeader{
+		Slot:          v.slot,
+		ProposerIndex: 0,
+		ParentRoot:    make([]byte, 32),
+		StateRoot:     make([]byte, 32),
+		BodyRoot:      make([]byte, 32),
+	}
+}
+
+func (v *validxStateOverride) HashTreeRoot(ctx context.Context) ([32]byte, error) {
+	// Return a zero hash for tests
+	return [32]byte{}, nil
+}
+
+func (v *validxStateOverride) UpdateStateRootAtIndex(idx uint64, stateRoot [32]byte) error {
+	// No-op for mock - we don't track state roots
+	return nil
+}
+
+func (v *validxStateOverride) SetLatestBlockHeader(val *ethpb.BeaconBlockHeader) error {
+	// No-op for mock - we don't track block headers
+	return nil
+}
+
+func (v *validxStateOverride) ReadFromEveryValidator(f func(idx int, val state.ReadOnlyValidator) error) error {
+	validators := v.Validators()
+	for i, val := range validators {
+		rov, err := state_native.NewValidator(val)
+		if err != nil {
+			return err
+		}
+		if err := f(i, rov); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 type mockProposerCache struct {
 	ComputeProposerCB func(ctx context.Context, root [32]byte, slot primitives.Slot, pst state.BeaconState) (primitives.ValidatorIndex, error)
 	ProposerCB        func(c *forkchoicetypes.Checkpoint, slot primitives.Slot) (primitives.ValidatorIndex, bool)

beacon-chain/verification/data_column.go

@@ -1,13 +1,16 @@
 package verification
 
 import (
+	"bytes"
 	"context"
 	"crypto/sha256"
 	"fmt"
 	"strings"
 	"time"
 
+	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/helpers"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/peerdas"
+	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/transition"
 	forkchoicetypes "github.com/OffchainLabs/prysm/v7/beacon-chain/forkchoice/types"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/state"
 	fieldparams "github.com/OffchainLabs/prysm/v7/config/fieldparams"
@@ -66,6 +69,12 @@ var (
 	errBadTopic       = errors.New("topic is not of the one expected")
 )
 
+type LazyHeadStateProvider struct {
+	HeadStateProvider
+}
+
+var _ HeadStateProvider = &LazyHeadStateProvider{}
+
 type (
 	RODataColumnsVerifier struct {
 		*sharedResources
@@ -262,14 +271,14 @@ func (dv *RODataColumnsVerifier) ValidProposerSignature(ctx context.Context) (er
 		if _, err, _ = dv.sg.Do(signatureData.concat(), func() (any, error) {
 			columnVerificationProposerSignatureCache.WithLabelValues("miss").Inc()
 
-			// Retrieve the parent state.
+			// Retrieve a state compatible with the data column for verification.
-			parentState, err := dv.state(ctx, dataColumn.ParentRoot())
+			verifyingState, err := dv.getVerifyingState(ctx, dataColumn)
 			if err != nil {
-				return nil, columnErrBuilder(errors.Wrap(err, "parent state"))
+				return nil, columnErrBuilder(errors.Wrap(err, "verifying state"))
 			}
 
 			// Full verification, which will subsequently be cached for anything sharing the signature cache.
-			if err = dv.sc.VerifySignature(signatureData, parentState); err != nil {
+			if err = dv.sc.VerifySignature(signatureData, verifyingState); err != nil {
 				return nil, columnErrBuilder(errors.Wrap(err, "verify signature"))
 			}
 
@@ -282,6 +291,61 @@ func (dv *RODataColumnsVerifier) ValidProposerSignature(ctx context.Context) (er
 	return nil
 }
 
+// getVerifyingState returns a state that is compatible with the column sidecar and can be used to verify signature and proposer index.
+// The returned state is guaranteed to be at the same epoch as the data column's epoch, and have the same randao mix and active
+// validator indices as the data column's parent state advanced to the data column's slot.
+func (dv *RODataColumnsVerifier) getVerifyingState(ctx context.Context, dataColumn blocks.RODataColumn) (state.ReadOnlyBeaconState, error) {
+	headRoot, err := dv.hsp.HeadRoot(ctx)
+	if err != nil {
+		return nil, err
+	}
+	parentRoot := dataColumn.ParentRoot()
+	dataColumnSlot := dataColumn.Slot()
+	dataColumnEpoch := slots.ToEpoch(dataColumnSlot)
+	headSlot := dv.hsp.HeadSlot()
+	headEpoch := slots.ToEpoch(headSlot)
+
+	// Use head if it's the parent
+	if bytes.Equal(parentRoot[:], headRoot) {
+		// If they are in the same epoch, then we can return the head state directly
+		if dataColumnEpoch == headEpoch {
+			return dv.hsp.HeadStateReadOnly(ctx)
+		}
+		// Otherwise, we need to process the head state to the data column's slot
+		headState, err := dv.hsp.HeadState(ctx)
+		if err != nil {
+			return nil, err
+		}
+		return transition.ProcessSlotsUsingNextSlotCache(ctx, headState, headRoot, dataColumnSlot)
+	}
+
+	// If head and data column are in the same epoch and head is compatible with the parent's target, then use head
+	if dataColumnEpoch == headEpoch {
+		headTarget, err := dv.fc.TargetRootForEpoch(bytesutil.ToBytes32(headRoot), dataColumnEpoch)
+		if err != nil {
+			return nil, err
+		}
+		parentTarget, err := dv.fc.TargetRootForEpoch(parentRoot, dataColumnEpoch)
+		if err != nil {
+			return nil, err
+		}
+		if bytes.Equal(headTarget[:], parentTarget[:]) {
+			return dv.hsp.HeadStateReadOnly(ctx)
+		}
+	}
+
+	// Otherwise retrieve the parent state and advance it to the data column's slot
+	parentState, err := dv.sr.StateByRoot(ctx, parentRoot)
+	if err != nil {
+		return nil, err
+	}
+	parentEpoch := slots.ToEpoch(parentState.Slot())
+	if dataColumnEpoch == parentEpoch {
+		return parentState, nil
+	}
+	return transition.ProcessSlotsUsingNextSlotCache(ctx, parentState, parentRoot[:], dataColumnSlot)
+}
+
 func (dv *RODataColumnsVerifier) SidecarParentSeen(parentSeen func([fieldparams.RootLength]byte) bool) (err error) {
 	if ok, err := dv.results.cached(RequireSidecarParentSeen); ok {
 		return err
@@ -482,14 +546,12 @@ func (dv *RODataColumnsVerifier) SidecarProposerExpected(ctx context.Context) (e
 			// Ensure the expensive index computation is only performed once for
 			// concurrent requests for the same signature data.
 			idxAny, err, _ := dv.sg.Do(concatRootSlot(parentRoot, dataColumnSlot), func() (any, error) {
-				// Retrieve the parent state.
+				verifyingState, err := dv.getVerifyingState(ctx, dataColumn)
-				parentState, err := dv.state(ctx, parentRoot)
 				if err != nil {
-					return nil, columnErrBuilder(errors.Wrap(err, "parent state"))
+					return nil, columnErrBuilder(errors.Wrap(err, "verifying state"))
 				}
 
-				// Compute the proposer index.
+				idx, err = helpers.BeaconProposerIndexAtSlot(ctx, verifyingState, dataColumnSlot)
-				idx, err = dv.pc.ComputeProposer(ctx, parentRoot, dataColumnSlot, parentState)
 				if err != nil {
 					return nil, columnErrBuilder(errors.Wrap(err, "compute proposer"))
 				}
@@ -514,25 +576,6 @@ func (dv *RODataColumnsVerifier) SidecarProposerExpected(ctx context.Context) (e
 	return nil
 }
 
-// state retrieves the state of the corresponding root from the cache if possible, else retrieves it from the state by rooter.
-func (dv *RODataColumnsVerifier) state(ctx context.Context, root [fieldparams.RootLength]byte) (state.BeaconState, error) {
-	// If the parent root is already in the cache, return it.
-	if st, ok := dv.stateByRoot[root]; ok {
-		return st, nil
-	}
-
-	// Retrieve the parent state from the state by rooter.
-	st, err := dv.sr.StateByRoot(ctx, root)
-	if err != nil {
-		return nil, errors.Wrap(err, "state by root")
-	}
-
-	// Store the parent state in the cache.
-	dv.stateByRoot[root] = st
-
-	return st, nil
-}
-
 func columnToSignatureData(d blocks.RODataColumn) signatureData {
 	return signatureData{
 		Root:      d.BlockRoot(),

beacon-chain/verification/data_column_test.go

@@ -1,7 +1,6 @@
 package verification
 
 import (
-	"context"
 	"reflect"
 	"sync"
 	"testing"
@@ -11,7 +10,6 @@ import (
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/peerdas"
 	forkchoicetypes "github.com/OffchainLabs/prysm/v7/beacon-chain/forkchoice/types"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/startup"
-	"github.com/OffchainLabs/prysm/v7/beacon-chain/state"
 	fieldparams "github.com/OffchainLabs/prysm/v7/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v7/config/params"
 	"github.com/OffchainLabs/prysm/v7/consensus-types/blocks"
@@ -330,7 +328,7 @@ func TestValidProposerSignature(t *testing.T) {
 			svcbError:       nil,
 			vscbShouldError: false,
 			vscbError:       nil,
-			stateByRooter:   sbrForValOverride(firstColumn.ProposerIndex(), validator),
+			stateByRooter:   sbrForValOverrideWithT(t, firstColumn.ProposerIndex(), validator),
 			isError:         false,
 		},
 		{
@@ -348,7 +346,7 @@ func TestValidProposerSignature(t *testing.T) {
 			svcbError:       nil,
 			vscbShouldError: false,
 			vscbError:       errors.New("signature, not so good!"),
-			stateByRooter:   sbrForValOverride(firstColumn.ProposerIndex(), validator),
+			stateByRooter:   sbrForValOverrideWithT(t, firstColumn.ProposerIndex(), validator),
 			isError:         true,
 		},
 	}
@@ -378,8 +376,12 @@ func TestValidProposerSignature(t *testing.T) {
 
 			initializer := Initializer{
 				shared: &sharedResources{
-					sc: signatureCache,
+					sc:  signatureCache,
-					sr: tc.stateByRooter,
+					sr:  tc.stateByRooter,
+					hsp: &mockHeadStateProvider{},
+					fc: &mockForkchoicer{
+						TargetRootForEpochCB: fcReturnsTargetRoot([fieldparams.RootLength]byte{}),
+					},
 				},
 			}
 
@@ -796,20 +798,7 @@ func TestDataColumnsSidecarProposerExpected(t *testing.T) {
 	parentRoot := [fieldparams.RootLength]byte{}
 	columns := GenerateTestDataColumns(t, parentRoot, columnSlot, blobCount)
 	firstColumn := columns[0]
-
-	newColumns := GenerateTestDataColumns(t, parentRoot, 2*params.BeaconConfig().SlotsPerEpoch, blobCount)
-	firstNewColumn := newColumns[0]
-
-	validator := &ethpb.Validator{}
-
-	commonComputeProposerCB := func(_ context.Context, root [fieldparams.RootLength]byte, slot primitives.Slot, _ state.BeaconState) (primitives.ValidatorIndex, error) {
-		require.Equal(t, firstColumn.ParentRoot(), root)
-		require.Equal(t, firstColumn.Slot(), slot)
-		return firstColumn.ProposerIndex(), nil
-	}
-
 	ctx := t.Context()
-
 	testCases := []struct {
 		name          string
 		stateByRooter StateByRooter
@@ -841,66 +830,7 @@ func TestDataColumnsSidecarProposerExpected(t *testing.T) {
 				ProposerCB: pcReturnsNotFound(),
 			},
 			columns: columns,
-			error:   "state by root",
+			error:   "verifying state",
-		},
-		{
-			name:          "Not cached, proposer matches",
-			stateByRooter: sbrForValOverride(firstColumn.ProposerIndex(), validator),
-			proposerCache: &mockProposerCache{
-				ProposerCB:        pcReturnsNotFound(),
-				ComputeProposerCB: commonComputeProposerCB,
-			},
-			columns: columns,
-		},
-		{
-			name:          "Not cached, proposer matches",
-			stateByRooter: sbrForValOverride(firstColumn.ProposerIndex(), validator),
-			proposerCache: &mockProposerCache{
-				ProposerCB:        pcReturnsNotFound(),
-				ComputeProposerCB: commonComputeProposerCB,
-			},
-			columns: columns,
-		},
-		{
-			name:          "Not cached, proposer matches for next epoch",
-			stateByRooter: sbrForValOverride(firstNewColumn.ProposerIndex(), validator),
-			proposerCache: &mockProposerCache{
-				ProposerCB: pcReturnsNotFound(),
-				ComputeProposerCB: func(_ context.Context, root [32]byte, slot primitives.Slot, _ state.BeaconState) (primitives.ValidatorIndex, error) {
-					require.Equal(t, firstNewColumn.ParentRoot(), root)
-					require.Equal(t, firstNewColumn.Slot(), slot)
-					return firstColumn.ProposerIndex(), nil
-				},
-			},
-			columns: newColumns,
-		},
-		{
-			name:          "Not cached, proposer does not match",
-			stateByRooter: sbrForValOverride(firstColumn.ProposerIndex(), validator),
-			proposerCache: &mockProposerCache{
-				ProposerCB: pcReturnsNotFound(),
-				ComputeProposerCB: func(_ context.Context, root [32]byte, slot primitives.Slot, _ state.BeaconState) (primitives.ValidatorIndex, error) {
-					require.Equal(t, firstColumn.ParentRoot(), root)
-					require.Equal(t, firstColumn.Slot(), slot)
-					return firstColumn.ProposerIndex() + 1, nil
-				},
-			},
-			columns: columns,
-			error:   errSidecarUnexpectedProposer.Error(),
-		},
-		{
-			name:          "Not cached, ComputeProposer fails",
-			stateByRooter: sbrForValOverride(firstColumn.ProposerIndex(), validator),
-			proposerCache: &mockProposerCache{
-				ProposerCB: pcReturnsNotFound(),
-				ComputeProposerCB: func(_ context.Context, root [32]byte, slot primitives.Slot, _ state.BeaconState) (primitives.ValidatorIndex, error) {
-					require.Equal(t, firstColumn.ParentRoot(), root)
-					require.Equal(t, firstColumn.Slot(), slot)
-					return 0, errors.New("ComputeProposer failed")
-				},
-			},
-			columns: columns,
-			error:   "compute proposer",
 		},
 	}
 
@@ -908,8 +838,9 @@ func TestDataColumnsSidecarProposerExpected(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			initializer := Initializer{
 				shared: &sharedResources{
-					sr: tc.stateByRooter,
+					sr:  tc.stateByRooter,
-					pc: tc.proposerCache,
+					pc:  tc.proposerCache,
+					hsp: &mockHeadStateProvider{},
 					fc: &mockForkchoicer{
 						TargetRootForEpochCB: fcReturnsTargetRoot([fieldparams.RootLength]byte{}),
 					},

beacon-chain/verification/initializer.go

@@ -33,6 +33,16 @@ type StateByRooter interface {
 	StateByRoot(ctx context.Context, blockRoot [32]byte) (state.BeaconState, error)
 }
 
+// HeadStateProvider describes a type that can provide access to the current head state and related methods.
+// This interface matches blockchain.HeadFetcher but is defined here to avoid import cycles
+// (blockchain package imports verification package).
+type HeadStateProvider interface {
+	HeadRoot(ctx context.Context) ([]byte, error)
+	HeadSlot() primitives.Slot
+	HeadState(ctx context.Context) (state.BeaconState, error)
+	HeadStateReadOnly(ctx context.Context) (state.ReadOnlyBeaconState, error)
+}
+
 // sharedResources provides access to resources that are required by different verification types.
 // for example, sidecar verification and block verification share the block signature verification cache.
 type sharedResources struct {
@@ -41,6 +51,7 @@ type sharedResources struct {
 	sc    signatureCache
 	pc    proposerCache
 	sr    StateByRooter
+	hsp   HeadStateProvider
 	ic    *inclusionProofCache
 	sg    singleflight.Group
 }
@@ -96,14 +107,15 @@ func WithForkLookup(fl forkLookup) InitializerOption {
 }
 
 // NewInitializerWaiter creates an InitializerWaiter which can be used to obtain an Initializer once async dependencies are ready.
-func NewInitializerWaiter(cw startup.ClockWaiter, fc Forkchoicer, sr StateByRooter, opts ...InitializerOption) *InitializerWaiter {
+func NewInitializerWaiter(cw startup.ClockWaiter, fc Forkchoicer, sr StateByRooter, hsp HeadStateProvider, opts ...InitializerOption) *InitializerWaiter {
 	pc := newPropCache()
 	// signature cache is initialized in WaitForInitializer, since we need the genesis validators root, which can be obtained from startup.Clock.
 	shared := &sharedResources{
-		fc: fc,
+		fc:  fc,
-		pc: pc,
+		pc:  pc,
-		sr: sr,
+		sr:  sr,
-		ic: newInclusionProofCache(defaultInclusionProofCacheSize),
+		hsp: hsp,
+		ic:  newInclusionProofCache(defaultInclusionProofCacheSize),
 	}
 	iw := &InitializerWaiter{cw: cw, ini: &Initializer{shared: shared}}
 	for _, o := range opts {

beacon-chain/verification/initializer_test.go

@@ -18,7 +18,7 @@ func TestInitializerWaiter(t *testing.T) {
 	cs := startup.NewClockSynchronizer()
 	require.NoError(t, cs.SetClock(c))
 
-	w := NewInitializerWaiter(cs, &mockForkchoicer{}, &mockStateByRooter{})
+	w := NewInitializerWaiter(cs, &mockForkchoicer{}, &mockStateByRooter{}, &mockHeadStateProvider{})
 	ini, err := w.WaitForInitializer(ctx)
 	require.NoError(t, err)
 	csc, ok := ini.shared.sc.(*sigCache)

changelog/potuz_use_head_datacolumn.md

@@ -0,0 +1,3 @@
+### Changed
+
+- Use head state readonly when possible to validate data column sidecars.

testing/spectest/shared/common/forkchoice/builder.go

@@ -41,7 +41,7 @@ func NewBuilder(t testing.TB, initialState state.BeaconState, initialBlock inter
 	getFork := func(targetEpoch primitives.Epoch) (*ethpb.Fork, error) {
 		return initialState.Fork(), nil
 	}
-	bvw := verification.NewInitializerWaiter(cw, fc, sg, verification.WithForkLookup(getFork))
+	bvw := verification.NewInitializerWaiter(cw, fc, sg, service, verification.WithForkLookup(getFork))
 	return &Builder{
 		service:  service,
 		execMock: execMock,