Add SSZ list types for gloas API request bodies

api/v1/gloas/generate.yaml

@@ -7,3 +7,7 @@ types:
     output: blockcontents_ssz.go
   - name: SignedExecutionPayloadEnvelopeContents
     output: signedexecutionpayloadenvelopecontents_ssz.go
+  - name: PayloadAttestationMessages
+    output: payloadattestationmessages_ssz.go
+  - name: SignedProposerPreferencesList
+    output: signedproposerpreferenceslist_ssz.go

api/v1/gloas/lists_test.go

@@ -0,0 +1,101 @@
+// Copyright © 2026 Attestant Limited.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gloas_test
+
+import (
+	"testing"
+
+	apiv1gloas "github.com/attestantio/go-eth2-client/api/v1/gloas"
+	"github.com/attestantio/go-eth2-client/spec/gloas"
+	"github.com/attestantio/go-eth2-client/spec/phase0"
+	"github.com/stretchr/testify/require"
+)
+
+func testPayloadAttestationMessage(i byte) *gloas.PayloadAttestationMessage {
+	return &gloas.PayloadAttestationMessage{
+		ValidatorIndex: phase0.ValidatorIndex(i),
+		Data: &gloas.PayloadAttestationData{
+			BeaconBlockRoot:   phase0.Root{i},
+			Slot:              phase0.Slot(i),
+			PayloadPresent:    i%2 == 0,
+			BlobDataAvailable: true,
+		},
+		Signature: phase0.BLSSignature{i},
+	}
+}
+
+func testSignedProposerPreferences(i byte) *gloas.SignedProposerPreferences {
+	return &gloas.SignedProposerPreferences{
+		Message: &gloas.ProposerPreferences{
+			DependentRoot:  phase0.Root{i},
+			ProposalSlot:   phase0.Slot(i),
+			ValidatorIndex: phase0.ValidatorIndex(i),
+			FeeRecipient:   [20]byte{i},
+			TargetGasLimit: 60_000_000,
+		},
+		Signature: phase0.BLSSignature{i},
+	}
+}
+
+// TestPayloadAttestationMessagesSSZ asserts the List[PayloadAttestationMessage, PTC_SIZE] encoding
+// used by POST /eth/v1/beacon/pool/payload_attestations.
+func TestPayloadAttestationMessagesSSZ(t *testing.T) {
+	list := apiv1gloas.PayloadAttestationMessages{testPayloadAttestationMessage(1), testPayloadAttestationMessage(2)}
+
+	data, err := list.MarshalSSZ()
+	require.NoError(t, err)
+
+	// The list of fixed size containers is the concatenation of the elements.
+	first, err := list[0].MarshalSSZ()
+	require.NoError(t, err)
+	require.Equal(t, first, data[:len(first)])
+	require.Len(t, data, 2*len(first))
+
+	var decoded apiv1gloas.PayloadAttestationMessages
+	require.NoError(t, decoded.UnmarshalSSZ(data))
+	require.Equal(t, list, decoded)
+
+	var empty apiv1gloas.PayloadAttestationMessages
+	require.NoError(t, empty.UnmarshalSSZ(nil))
+	require.Empty(t, empty)
+
+	require.Error(t, decoded.UnmarshalSSZ(data[:len(data)-1]), "misaligned body")
+
+	tooMany := make([]byte, (512+1)*len(first))
+	require.Error(t, decoded.UnmarshalSSZ(tooMany), "over PTC_SIZE")
+}
+
+// TestSignedProposerPreferencesListSSZ asserts the
+// List[SignedProposerPreferences, (MIN_SEED_LOOKAHEAD + 1) * SLOTS_PER_EPOCH] encoding
+// used by POST /eth/v1/validator/proposer_preferences.
+func TestSignedProposerPreferencesListSSZ(t *testing.T) {
+	list := apiv1gloas.SignedProposerPreferencesList{testSignedProposerPreferences(1), testSignedProposerPreferences(2)}
+
+	data, err := list.MarshalSSZ()
+	require.NoError(t, err)
+
+	first, err := list[0].MarshalSSZ()
+	require.NoError(t, err)
+	require.Equal(t, first, data[:len(first)])
+	require.Len(t, data, 2*len(first))
+
+	var decoded apiv1gloas.SignedProposerPreferencesList
+	require.NoError(t, decoded.UnmarshalSSZ(data))
+	require.Equal(t, list, decoded)
+
+	require.Error(t, decoded.UnmarshalSSZ(data[:len(data)-1]), "misaligned body")
+
+	tooMany := make([]byte, (64+1)*len(first))
+	require.Error(t, decoded.UnmarshalSSZ(tooMany), "over (MIN_SEED_LOOKAHEAD+1)*SLOTS_PER_EPOCH")
+}

api/v1/gloas/payloadattestationmessages.go

@@ -0,0 +1,38 @@
+// Copyright © 2026 Attestant Limited.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gloas
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/attestantio/go-eth2-client/spec/gloas"
+	"github.com/pk910/dynamic-ssz/sszutils"
+)
+
+// PayloadAttestationMessages is the List[PayloadAttestationMessage, PTC_SIZE] submitted to
+// POST /eth/v1/beacon/pool/payload_attestations.
+type PayloadAttestationMessages []*gloas.PayloadAttestationMessage
+
+var _ = sszutils.Annotate[PayloadAttestationMessages](`ssz-max:"512" dynssz-max:"PTC_SIZE"`)
+
+// String returns a string version of the structure.
+func (p *PayloadAttestationMessages) String() string {
+	data, err := json.Marshal(p)
+	if err != nil {
+		return fmt.Sprintf("ERR: %v", err)
+	}
+
+	return string(data)
+}

api/v1/gloas/signedproposerpreferenceslist.go

@@ -0,0 +1,38 @@
+// Copyright © 2026 Attestant Limited.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gloas
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/attestantio/go-eth2-client/spec/gloas"
+	"github.com/pk910/dynamic-ssz/sszutils"
+)
+
+// SignedProposerPreferencesList is the List[SignedProposerPreferences, (MIN_SEED_LOOKAHEAD + 1) * SLOTS_PER_EPOCH]
+// submitted to POST /eth/v1/validator/proposer_preferences.
+type SignedProposerPreferencesList []*gloas.SignedProposerPreferences
+
+var _ = sszutils.Annotate[SignedProposerPreferencesList](`ssz-max:"64" dynssz-max:"(MIN_SEED_LOOKAHEAD+1)*SLOTS_PER_EPOCH"`)
+
+// String returns a string version of the structure.
+func (s *SignedProposerPreferencesList) String() string {
+	data, err := json.Marshal(s)
+	if err != nil {
+		return fmt.Sprintf("ERR: %v", err)
+	}
+
+	return string(data)
+}