fix some edge cases

api/server/structs/endpoints_validator.go

@@ -74,6 +74,18 @@ type SyncCommitteeDuty struct {
 	ValidatorSyncCommitteeIndices []string `json:"validator_sync_committee_indices"`
 }
 
+type GetPTCDutiesResponse struct {
+	DependentRoot       string     `json:"dependent_root"`
+	ExecutionOptimistic bool       `json:"execution_optimistic"`
+	Data                []*PTCDuty `json:"data"`
+}
+
+type PTCDuty struct {
+	Pubkey         string `json:"pubkey"`
+	ValidatorIndex string `json:"validator_index"`
+	Slot           string `json:"slot"`
+}
+
 // ProduceBlockV3Response is a wrapper json object for the returned block from the ProduceBlockV3 endpoint
 type ProduceBlockV3Response struct {
 	Version                 string          `json:"version"`

beacon-chain/core/gloas/payload_attestation.go

@@ -70,7 +70,7 @@ func ProcessPayloadAttestations(ctx context.Context, st state.BeaconState, body
 
 // indexedPayloadAttestation converts a payload attestation into its indexed form.
 func indexedPayloadAttestation(ctx context.Context, st state.ReadOnlyBeaconState, att *eth.PayloadAttestation) (*consensus_types.IndexedPayloadAttestation, error) {
-	committee, err := payloadCommittee(ctx, st, att.Data.Slot)
+	committee, err := PayloadCommittee(ctx, st, att.Data.Slot)
 	if err != nil {
 		return nil, err
 	}
@@ -89,7 +89,7 @@ func indexedPayloadAttestation(ctx context.Context, st state.ReadOnlyBeaconState
 	}, nil
 }
 
-// payloadCommittee returns the payload timeliness committee for a given slot for the state.
+// PayloadCommittee returns the payload timeliness committee for a given slot for the state.
 // Spec v1.7.0-alpha.0 (pseudocode):
 // get_ptc(state: BeaconState, slot: Slot) -> Vector[ValidatorIndex, PTC_SIZE]:
 //
@@ -101,7 +101,7 @@ func indexedPayloadAttestation(ctx context.Context, st state.ReadOnlyBeaconState
 //	  committee = get_beacon_committee(state, slot, CommitteeIndex(i))
 //	  indices.extend(committee)
 //	return compute_balance_weighted_selection(state, indices, seed, size=PTC_SIZE, shuffle_indices=False)
-func payloadCommittee(ctx context.Context, st state.ReadOnlyBeaconState, slot primitives.Slot) ([]primitives.ValidatorIndex, error) {
+func PayloadCommittee(ctx context.Context, st state.ReadOnlyBeaconState, slot primitives.Slot) ([]primitives.ValidatorIndex, error) {
 	epoch := slots.ToEpoch(slot)
 	seed, err := ptcSeed(st, epoch, slot)
 	if err != nil {

beacon-chain/rpc/endpoints.go

@@ -340,6 +340,17 @@ func (s *Service) validatorEndpoints(
 			handler: server.GetSyncCommitteeDuties,
 			methods: []string{http.MethodPost},
 		},
+		{
+			template: "/eth/v1/validator/duties/ptc/{epoch}",
+			name:     namespace + ".GetPTCDuties",
+			middleware: []middleware.Middleware{
+				middleware.ContentTypeHandler([]string{api.JsonMediaType}),
+				middleware.AcceptHeaderHandler([]string{api.JsonMediaType}),
+				middleware.AcceptEncodingHeaderHandler(),
+			},
+			handler: server.GetPTCDuties,
+			methods: []string{http.MethodPost},
+		},
 		{
 			template: "/eth/v1/validator/prepare_beacon_proposer",
 			name:     namespace + ".PrepareBeaconProposer",

beacon-chain/rpc/eth/validator/handlers.go

@@ -18,6 +18,7 @@ import (
 	"github.com/OffchainLabs/prysm/v7/api/server/structs"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/builder"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/cache"
+	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/gloas"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/helpers"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/rpc/core"
 	rpchelpers "github.com/OffchainLabs/prysm/v7/beacon-chain/rpc/eth/helpers"
@@ -1212,6 +1213,175 @@ func (s *Server) GetSyncCommitteeDuties(w http.ResponseWriter, r *http.Request)
 	httputil.WriteJson(w, resp)
 }
 
+// GetPTCDuties retrieves the payload timeliness committee (PTC) duties for the requested epoch.
+// The PTC is responsible for attesting to payload timeliness in ePBS (Gloas fork and later).
+func (s *Server) GetPTCDuties(w http.ResponseWriter, r *http.Request) {
+	ctx, span := trace.StartSpan(r.Context(), "validator.GetPTCDuties")
+	defer span.End()
+
+	if shared.IsSyncing(ctx, w, s.SyncChecker, s.HeadFetcher, s.TimeFetcher, s.OptimisticModeFetcher) {
+		return
+	}
+
+	_, requestedEpochUint, ok := shared.UintFromRoute(w, r, "epoch")
+	if !ok {
+		return
+	}
+	requestedEpoch := primitives.Epoch(requestedEpochUint)
+
+	// PTC duties are only available from Gloas fork onwards.
+	if requestedEpoch < params.BeaconConfig().GloasForkEpoch {
+		httputil.HandleError(w, "PTC duties are not available before Gloas fork", http.StatusBadRequest)
+		return
+	}
+
+	var indices []string
+	err := json.NewDecoder(r.Body).Decode(&indices)
+	switch {
+	case errors.Is(err, io.EOF):
+		httputil.HandleError(w, "No data submitted", http.StatusBadRequest)
+		return
+	case err != nil:
+		httputil.HandleError(w, "Could not decode request body: "+err.Error(), http.StatusBadRequest)
+		return
+	}
+	if len(indices) == 0 {
+		httputil.HandleError(w, "No data submitted", http.StatusBadRequest)
+		return
+	}
+
+	requestedValIndices := make([]primitives.ValidatorIndex, len(indices))
+	for i, ix := range indices {
+		valIx, valid := shared.ValidateUint(w, fmt.Sprintf("ValidatorIndices[%d]", i), ix)
+		if !valid {
+			return
+		}
+		requestedValIndices[i] = primitives.ValidatorIndex(valIx)
+	}
+
+	// Limit how far in the future we can query (current + 1 epoch).
+	cs := s.TimeFetcher.CurrentSlot()
+	currentEpoch := slots.ToEpoch(cs)
+	nextEpoch := currentEpoch + 1
+	if requestedEpoch > nextEpoch {
+		httputil.HandleError(w,
+			fmt.Sprintf("Request epoch %d can not be greater than next epoch %d", requestedEpoch, nextEpoch),
+			http.StatusBadRequest)
+		return
+	}
+
+	// For next epoch requests, we use the current epoch's state since PTC
+	// assignments for next epoch can be computed from current epoch's state.
+	// This mirrors the spec's get_ptc_assignment which asserts epoch <= next_epoch
+	// and uses the current state to compute assignments.
+	epochForState := requestedEpoch
+	if requestedEpoch == nextEpoch {
+		epochForState = currentEpoch
+	}
+	st, err := s.Stater.StateByEpoch(ctx, epochForState)
+	if err != nil {
+		shared.WriteStateFetchError(w, err)
+		return
+	}
+
+	// Build a set of requested validators for O(1) lookup.
+	requestedSet := make(map[primitives.ValidatorIndex]bool, len(requestedValIndices))
+	for _, idx := range requestedValIndices {
+		requestedSet[idx] = true
+	}
+
+	// Compute PTC duties for each slot in the epoch.
+	startSlot, err := slots.EpochStart(requestedEpoch)
+	if err != nil {
+		httputil.HandleError(w, "Could not get epoch start slot: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+	endSlot := startSlot + params.BeaconConfig().SlotsPerEpoch
+
+	duties := make([]*structs.PTCDuty, 0)
+	for slot := startSlot; slot < endSlot; slot++ {
+		ptc, err := gloas.PayloadCommittee(ctx, st, slot)
+		if err != nil {
+			httputil.HandleError(w,
+				fmt.Sprintf("Could not get PTC for slot %d: %s", slot, err.Error()),
+				http.StatusInternalServerError)
+			return
+		}
+
+		// Check which requested validators are in this slot's PTC.
+		for _, valIdx := range ptc {
+			if !requestedSet[valIdx] {
+				continue
+			}
+			// Validate the validator index with explicit bounds check.
+			if uint64(valIdx) >= uint64(st.NumValidators()) {
+				httputil.HandleError(w, fmt.Sprintf("Invalid validator index %d", valIdx), http.StatusBadRequest)
+				return
+			}
+			pubkey := st.PubkeyAtIndex(valIdx)
+			// Defensive check: ensure pubkey is not zero.
+			var zeroPubkey [fieldparams.BLSPubkeyLength]byte
+			if bytes.Equal(pubkey[:], zeroPubkey[:]) {
+				httputil.HandleError(w, fmt.Sprintf("Invalid validator index %d", valIdx), http.StatusBadRequest)
+				return
+			}
+			duties = append(duties, &structs.PTCDuty{
+				Pubkey:         hexutil.Encode(pubkey[:]),
+				ValidatorIndex: strconv.FormatUint(uint64(valIdx), 10),
+				Slot:           strconv.FormatUint(uint64(slot), 10),
+			})
+		}
+	}
+
+	// Get dependent root. The dependent root is the block root at start_slot(epoch) - 1.
+	// For epoch 0, this would underflow, so we use genesis block root.
+	// For next epoch requests, we use the same dependent root as current epoch since
+	// we're computing from the current epoch's state and the next epoch's RANDAO
+	// isn't finalized yet.
+	dependentEpoch := requestedEpoch
+	if requestedEpoch == nextEpoch {
+		dependentEpoch = currentEpoch
+	}
+	var dependentRoot []byte
+	if dependentEpoch == 0 {
+		r, err := s.BeaconDB.GenesisBlockRoot(ctx)
+		if err != nil {
+			httputil.HandleError(w, "Could not get genesis block root: "+err.Error(), http.StatusInternalServerError)
+			return
+		}
+		dependentRoot = r[:]
+	} else {
+		dependentRoot, err = ptcDependentRoot(st, dependentEpoch)
+		if err != nil {
+			httputil.HandleError(w, "Could not get dependent root: "+err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+
+	isOptimistic, err := s.OptimisticModeFetcher.IsOptimistic(ctx)
+	if err != nil {
+		httputil.HandleError(w, "Could not check optimistic status: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	resp := &structs.GetPTCDutiesResponse{
+		DependentRoot:       hexutil.Encode(dependentRoot),
+		ExecutionOptimistic: isOptimistic,
+		Data:                duties,
+	}
+	httputil.WriteJson(w, resp)
+}
+
+// ptcDependentRoot returns the block root that PTC assignments depend on.
+// PTC depends on the shuffling, which is determined by RANDAO at epoch boundary.
+func ptcDependentRoot(st state.BeaconState, epoch primitives.Epoch) ([]byte, error) {
+	epochStartSlot, err := slots.EpochStart(epoch)
+	if err != nil {
+		return nil, err
+	}
+	return helpers.BlockRootAtSlot(st, epochStartSlot-1)
+}
+
 // GetLiveness requests the beacon node to indicate if a validator has been observed to be live in a given epoch.
 // The beacon node might detect liveness by observing messages from the validator on the network,
 // in the beacon chain, from its API or from any other source.

beacon-chain/rpc/eth/validator/handlers_test.go

@@ -17,6 +17,7 @@ import (
 	mockChain "github.com/OffchainLabs/prysm/v7/beacon-chain/blockchain/testing"
 	builderTest "github.com/OffchainLabs/prysm/v7/beacon-chain/builder/testing"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/cache"
+	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/gloas"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/helpers"
 	"github.com/OffchainLabs/prysm/v7/beacon-chain/core/transition"
 	dbutil "github.com/OffchainLabs/prysm/v7/beacon-chain/db/testing"
@@ -2959,6 +2960,208 @@ func TestGetSyncCommitteeDuties(t *testing.T) {
 	})
 }
 
+func TestGetPTCDuties(t *testing.T) {
+	helpers.ClearCache()
+	params.SetupTestConfigCleanup(t)
+	cfg := params.BeaconConfig()
+	cfg.GloasForkEpoch = 0
+	params.OverrideBeaconConfig(cfg)
+
+	// Use fixed slot 0 for deterministic tests.
+	slot := primitives.Slot(0)
+	genesisTime := time.Now()
+	// Need enough validators for PTC selection (PTC_SIZE is 512 on mainnet, 2 on minimal)
+	numVals := uint64(fieldparams.PTCSize * 2)
+	st, _ := util.DeterministicGenesisStateFulu(t, numVals)
+	require.NoError(t, st.SetGenesisTime(genesisTime))
+
+	// Set up a genesis block root for dependent_root calculation.
+	genesisRoot := [32]byte{1, 2, 3}
+	db := dbutil.SetupDB(t)
+	require.NoError(t, db.SaveGenesisBlockRoot(t.Context(), genesisRoot))
+
+	mockChainService := &mockChain.ChainService{Genesis: genesisTime, State: st, Slot: &slot}
+	s := &Server{
+		Stater:                &testutil.MockStater{BeaconState: st},
+		SyncChecker:           &mockSync.Sync{IsSyncing: false},
+		TimeFetcher:           mockChainService,
+		HeadFetcher:           mockChainService,
+		OptimisticModeFetcher: mockChainService,
+		BeaconDB:              db,
+	}
+
+	t.Run("single validator in PTC", func(t *testing.T) {
+		// Request duties for validator index 0
+		var body bytes.Buffer
+		_, err := body.WriteString("[\"0\"]")
+		require.NoError(t, err)
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", &body)
+		request.SetPathValue("epoch", "0")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetPTCDutiesResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		assert.NotEmpty(t, resp.DependentRoot)
+	})
+
+	t.Run("verifies actual PTC membership", func(t *testing.T) {
+		// Compute expected PTC for slot 0 using the same helper.
+		expectedPTC, err := gloas.PayloadCommittee(t.Context(), st, 0)
+		require.NoError(t, err)
+		require.NotEmpty(t, expectedPTC, "PTC should not be empty")
+
+		// Request duties for all validators in the expected PTC.
+		var indices []string
+		for _, idx := range expectedPTC {
+			indices = append(indices, strconv.FormatUint(uint64(idx), 10))
+		}
+		indicesJSON, err := json.Marshal(indices)
+		require.NoError(t, err)
+
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", bytes.NewReader(indicesJSON))
+		request.SetPathValue("epoch", "0")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetPTCDutiesResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+
+		// All requested validators should have duties for slot 0.
+		assert.Equal(t, len(expectedPTC), len(resp.Data), "Should return duties for all PTC members")
+		for _, duty := range resp.Data {
+			assert.Equal(t, "0", duty.Slot, "All duties should be for slot 0")
+		}
+	})
+
+	t.Run("multiple validators", func(t *testing.T) {
+		var body bytes.Buffer
+		_, err := body.WriteString("[\"0\",\"1\",\"2\",\"3\",\"4\"]")
+		require.NoError(t, err)
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", &body)
+		request.SetPathValue("epoch", "0")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetPTCDutiesResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		assert.NotEmpty(t, resp.DependentRoot)
+		// Verify any returned duties have correct structure
+		for _, duty := range resp.Data {
+			assert.NotEmpty(t, duty.Pubkey)
+			assert.NotEmpty(t, duty.ValidatorIndex)
+			assert.NotEmpty(t, duty.Slot)
+		}
+	})
+
+	t.Run("pre-Gloas epoch returns error", func(t *testing.T) {
+		// Temporarily set GloasForkEpoch to 10
+		cfg := params.BeaconConfig()
+		cfg.GloasForkEpoch = 10
+		params.OverrideBeaconConfig(cfg)
+		defer func() {
+			cfg.GloasForkEpoch = 0
+			params.OverrideBeaconConfig(cfg)
+		}()
+
+		var body bytes.Buffer
+		_, err := body.WriteString("[\"0\"]")
+		require.NoError(t, err)
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", &body)
+		request.SetPathValue("epoch", "0")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.StringContains(t, "PTC duties are not available before Gloas fork", e.Message)
+	})
+
+	t.Run("no body", func(t *testing.T) {
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", nil)
+		request.SetPathValue("epoch", "0")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.StringContains(t, "No data submitted", e.Message)
+	})
+
+	t.Run("empty body", func(t *testing.T) {
+		var body bytes.Buffer
+		_, err := body.WriteString("[]")
+		require.NoError(t, err)
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", &body)
+		request.SetPathValue("epoch", "0")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.StringContains(t, "No data submitted", e.Message)
+	})
+
+	t.Run("invalid validator index string", func(t *testing.T) {
+		var body bytes.Buffer
+		_, err := body.WriteString("[\"foo\"]")
+		require.NoError(t, err)
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", &body)
+		request.SetPathValue("epoch", "0")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+	})
+
+	t.Run("out of bounds validator index", func(t *testing.T) {
+		// Request a validator index that's way beyond the number of validators.
+		var body bytes.Buffer
+		_, err := body.WriteString("[\"999999999\"]")
+		require.NoError(t, err)
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", &body)
+		request.SetPathValue("epoch", "0")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		// OOB validator won't be in any PTC, so request succeeds with empty duties.
+		assert.Equal(t, http.StatusOK, writer.Code)
+		resp := &structs.GetPTCDutiesResponse{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), resp))
+		assert.Equal(t, 0, len(resp.Data), "OOB validator should have no duties")
+	})
+
+	t.Run("epoch too far in future", func(t *testing.T) {
+		var body bytes.Buffer
+		_, err := body.WriteString("[\"0\"]")
+		require.NoError(t, err)
+		request := httptest.NewRequest(http.MethodPost, "http://www.example.com/eth/v1/validator/duties/ptc/{epoch}", &body)
+		request.SetPathValue("epoch", "100") // Far future epoch
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetPTCDuties(writer, request)
+		assert.Equal(t, http.StatusBadRequest, writer.Code)
+		e := &httputil.DefaultJsonError{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), e))
+		assert.StringContains(t, "can not be greater than next epoch", e.Message)
+	})
+}
+
 func TestPrepareBeaconProposer(t *testing.T) {
 	tests := []struct {
 		name    string

changelog/satushh_ptc-duties-endpoint.md

@@ -0,0 +1,3 @@
+### Added
+
+- PTC (Payload Timeliness Committee) duties endpoint: POST /eth/v1/validator/duties/ptc/{epoch} for ePBS (Gloas fork).