beacon/engine: fix cell proof logic

beacon/engine/types.go

@@ -336,7 +336,7 @@ func BlockToExecutableData(block *types.Block, fees *big.Int, sidecars []*types.
 		for j := range sidecar.Blobs {
 			bundle.Blobs = append(bundle.Blobs, hexutil.Bytes(sidecar.Blobs[j][:]))
 			bundle.Commitments = append(bundle.Commitments, hexutil.Bytes(sidecar.Commitments[j][:]))
-			if len(sidecar.CellProofs[j]) == 0 {
+			if len(sidecar.CellProofs) == 0 {
 				bundle.Proofs = append(bundle.Proofs, hexutil.Bytes(sidecar.Proofs[j][:]))
 			} else {
 				for _, proof := range sidecar.CellProofs[j] {

beacon/engine/types_test.go

@@ -0,0 +1,57 @@
+// Copyright 2025 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package engine
+
+import (
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto/kzg4844"
+)
+
+func TestBlobs(t *testing.T) {
+	var (
+		emptyBlob          = new(kzg4844.Blob)
+		emptyBlobCommit, _ = kzg4844.BlobToCommitment(emptyBlob)
+		emptyBlobProof, _  = kzg4844.ComputeBlobProof(emptyBlob, emptyBlobCommit)
+		emptyCellProof, _  = kzg4844.ComputeCells(emptyBlob)
+	)
+	header := types.Header{}
+	block := types.NewBlock(&header, &types.Body{}, nil, nil)
+
+	sidecarWithoutCellProofs := &types.BlobTxSidecar{
+		Blobs:       []kzg4844.Blob{*emptyBlob},
+		Commitments: []kzg4844.Commitment{emptyBlobCommit},
+		Proofs:      []kzg4844.Proof{emptyBlobProof},
+	}
+	env := BlockToExecutableData(block, common.Big0, []*types.BlobTxSidecar{sidecarWithoutCellProofs}, nil)
+	if len(env.BlobsBundle.Proofs) != 1 {
+		t.Fatalf("Expect 1 proof in blobs bundle, got %v", len(env.BlobsBundle.Proofs))
+	}
+
+	sidecarWithCellProofs := &types.BlobTxSidecar{
+		Blobs:       []kzg4844.Blob{*emptyBlob},
+		Commitments: []kzg4844.Commitment{emptyBlobCommit},
+		Proofs:      []kzg4844.Proof{emptyBlobProof},
+		CellProofs:  [][]kzg4844.Proof{emptyCellProof},
+	}
+	env = BlockToExecutableData(block, common.Big0, []*types.BlobTxSidecar{sidecarWithCellProofs}, nil)
+	if len(env.BlobsBundle.Proofs) != 128 {
+		t.Fatalf("Expect 128 proofs in blobs bundle, got %v", len(env.BlobsBundle.Proofs))
+	}
+}