update to newest spec

beacon/engine/ssz/envelopes.go

@@ -22,36 +22,85 @@ import (
 	"github.com/karalabe/ssz"
 )
 
-// ExecutionPayloadEnvelopeAmsterdam is the request body of
-// POST /amsterdam/payloads.
+// ExecutionPayloadEnvelopeAmsterdam is the monolithic request body of
+// POST /{fork}/payloads spanning every fork from Paris onward. The wire shape
+// is fork-driven by the codec (see the per-fork ExecutionPayloadEnvelope
+// catalogue in refactor-ssz.md):
+//
+//   - Paris / Shanghai: bare payload, no envelope fields
+//   - Cancun+:          + ParentBeaconBlockRoot
+//   - Prague+:          + ExecutionRequests
+//
+// ParentBeaconBlockRoot is a pointer so the codec can distinguish "absent for
+// this fork" (nil, Paris/Shanghai) from "present and zero".
 type ExecutionPayloadEnvelopeAmsterdam struct {
 	Payload               *ExecutionPayload
-	ParentBeaconBlockRoot common.Hash
-	ExecutionRequests     [][]byte
+	ParentBeaconBlockRoot *common.Hash // Cancun+
+	ExecutionRequests     [][]byte     // Prague+
 }
 
 func (e *ExecutionPayloadEnvelopeAmsterdam) SizeSSZ(siz *ssz.Sizer, fixed bool) uint32 {
-	// offset(payload) + 32(root) + offset(requests)
-	size := uint32(40)
+	// offset(payload) is always present; the root and the requests offset only
+	// exist from Cancun and Prague respectively (matching the OnFork gating).
+	size := uint32(4)
+	if siz.Fork() >= ssz.ForkDencun {
+		size += 32 // ParentBeaconBlockRoot
+	}
+	if siz.Fork() >= ssz.ForkPectra {
+		size += 4 // offset(requests)
+	}
 	if fixed {
 		return size
 	}
 	size += ssz.SizeDynamicObject(siz, e.Payload)
+	if siz.Fork() >= ssz.ForkPectra {
 		size += ssz.SizeSliceOfDynamicBytes(siz, e.ExecutionRequests)
+	}
 	return size
 }
 
 func (e *ExecutionPayloadEnvelopeAmsterdam) DefineSSZ(c *ssz.Codec) {
 	ssz.DefineDynamicObjectOffset(c, &e.Payload)
-	ssz.DefineStaticBytes(c, &e.ParentBeaconBlockRoot)
-	ssz.DefineSliceOfDynamicBytesOffset(c, &e.ExecutionRequests, MaxExecutionRequestsPerPayload, MaxBytesPerExecutionRequest)
+	ssz.DefineStaticBytesPointerOnFork(c, &e.ParentBeaconBlockRoot, fromCancun)
+	ssz.DefineSliceOfDynamicBytesOffsetOnFork(c, &e.ExecutionRequests, MaxExecutionRequestsPerPayload, MaxBytesPerExecutionRequest, fromPrague)
 
 	ssz.DefineDynamicObjectContent(c, &e.Payload)
-	ssz.DefineSliceOfDynamicBytesContent(c, &e.ExecutionRequests, MaxExecutionRequestsPerPayload, MaxBytesPerExecutionRequest)
+	ssz.DefineSliceOfDynamicBytesContentOnFork(c, &e.ExecutionRequests, MaxExecutionRequestsPerPayload, MaxBytesPerExecutionRequest, fromPrague)
 }
 
-// BlobsBundleV2 is the cell-proof blob bundle carried by BuiltPayload
-// from Osaka onwards.
+// BlobsBundleV1 is the single-proof blob bundle carried by BuiltPayload for
+// Cancun and Prague: one KZG proof per blob.
+type BlobsBundleV1 struct {
+	Commitments [][48]byte
+	Proofs      [][48]byte
+	Blobs       []*Blob
+}
+
+func (b *BlobsBundleV1) SizeSSZ(siz *ssz.Sizer, fixed bool) uint32 {
+	// 3 offsets
+	size := uint32(12)
+	if fixed {
+		return size
+	}
+	size += ssz.SizeSliceOfStaticBytes(siz, b.Commitments)
+	size += ssz.SizeSliceOfStaticBytes(siz, b.Proofs)
+	size += ssz.SizeSliceOfStaticObjects(siz, b.Blobs)
+	return size
+}
+
+func (b *BlobsBundleV1) DefineSSZ(c *ssz.Codec) {
+	ssz.DefineSliceOfStaticBytesOffset(c, &b.Commitments, MaxBlobCommitmentsPerBlock)
+	ssz.DefineSliceOfStaticBytesOffset(c, &b.Proofs, MaxBlobCommitmentsPerBlock)
+	ssz.DefineSliceOfStaticObjectsOffset(c, &b.Blobs, MaxBlobCommitmentsPerBlock)
+
+	ssz.DefineSliceOfStaticBytesContent(c, &b.Commitments, MaxBlobCommitmentsPerBlock)
+	ssz.DefineSliceOfStaticBytesContent(c, &b.Proofs, MaxBlobCommitmentsPerBlock)
+	ssz.DefineSliceOfStaticObjectsContent(c, &b.Blobs, MaxBlobCommitmentsPerBlock)
+}
+
+// BlobsBundleV2 is the cell-proof blob bundle carried by BuiltPayload from Osaka
+// onwards: CellsPerExtBlob cell proofs per blob. The wire layout matches
+// BlobsBundleV1 (three slices); only the proofs-list bound differs.
 type BlobsBundleV2 struct {
 	Commitments [][48]byte
 	Proofs      [][48]byte
@@ -80,37 +129,67 @@ func (b *BlobsBundleV2) DefineSSZ(c *ssz.Codec) {
 	ssz.DefineSliceOfStaticObjectsContent(c, &b.Blobs, MaxBlobCommitmentsPerBlock)
 }
 
-// BuiltPayloadAmsterdam is the response of GET /amsterdam/payloads/{id}.
+// BuiltPayloadAmsterdam is the monolithic response of GET /{fork}/payloads/{id}
+// spanning every fork from Paris onward. The wire shape is fork-driven by the
+// codec (see the per-fork BuiltPayload catalogue in refactor-ssz.md):
+//
+//   - Paris / Shanghai: Payload, BlockValue only
+//   - Cancun:           + BlobsBundleV1, ShouldOverrideBuilder
+//   - Prague:           + ExecutionRequests (placed before ShouldOverrideBuilder)
+//   - Osaka+:           BlobsBundle revision becomes V2 (cell proofs)
+//
+// Exactly one of BlobsBundleV1 / BlobsBundleV2 is active for any given fork
+// (V1 = Cancun..Prague, V2 = Osaka+); the other is nil and contributes neither
+// an offset nor content. ShouldOverrideBuilder is a pointer so the codec can
+// distinguish "absent for this fork" (nil, Paris/Shanghai) from "present and
+// false".
 type BuiltPayloadAmsterdam struct {
 	Payload               *ExecutionPayload
 	BlockValue            *uint256.Int
-	BlobsBundle           *BlobsBundleV2
-	ExecutionRequests     [][]byte
-	ShouldOverrideBuilder bool
+	BlobsBundleV1         *BlobsBundleV1 // Cancun, Prague
+	BlobsBundleV2         *BlobsBundleV2 // Osaka+
+	ExecutionRequests     [][]byte       // Prague+
+	ShouldOverrideBuilder *bool          // Cancun+
 }
 
 func (p *BuiltPayloadAmsterdam) SizeSSZ(siz *ssz.Sizer, fixed bool) uint32 {
-	// offset(payload) + 32(value) + offset(bundle) + offset(requests) + 1(override)
-	size := uint32(4 + 32 + 4 + 4 + 1)
+	// offset(payload) + 32(value) are always present; the bundle offset and the
+	// override byte exist from Cancun, and the requests offset from Prague.
+	size := uint32(4 + 32)
+	if siz.Fork() >= ssz.ForkDencun {
+		size += 4 // offset(blobs_bundle)
+		size++    // should_override_builder
+	}
+	if siz.Fork() >= ssz.ForkPectra {
+		size += 4 // offset(execution_requests)
+	}
 	if fixed {
 		return size
 	}
 	size += ssz.SizeDynamicObject(siz, p.Payload)
-	size += ssz.SizeDynamicObject(siz, p.BlobsBundle)
+	if siz.Fork() >= forkOsaka {
+		size += ssz.SizeDynamicObject(siz, p.BlobsBundleV2)
+	} else if siz.Fork() >= ssz.ForkDencun {
+		size += ssz.SizeDynamicObject(siz, p.BlobsBundleV1)
+	}
+	if siz.Fork() >= ssz.ForkPectra {
 		size += ssz.SizeSliceOfDynamicBytes(siz, p.ExecutionRequests)
+	}
 	return size
 }
 
 func (p *BuiltPayloadAmsterdam) DefineSSZ(c *ssz.Codec) {
 	ssz.DefineDynamicObjectOffset(c, &p.Payload)
 	ssz.DefineUint256(c, &p.BlockValue)
-	ssz.DefineDynamicObjectOffset(c, &p.BlobsBundle)
-	ssz.DefineSliceOfDynamicBytesOffset(c, &p.ExecutionRequests, MaxExecutionRequestsPerPayload, MaxBytesPerExecutionRequest)
-	ssz.DefineBool(c, &p.ShouldOverrideBuilder)
+	ssz.DefineDynamicObjectOffsetOnFork(c, &p.BlobsBundleV1, cancunToOsaka)
+	ssz.DefineDynamicObjectOffsetOnFork(c, &p.BlobsBundleV2, fromOsaka)
+	ssz.DefineSliceOfDynamicBytesOffsetOnFork(c, &p.ExecutionRequests, MaxExecutionRequestsPerPayload, MaxBytesPerExecutionRequest, fromPrague)
+	ssz.DefineBoolPointerOnFork(c, &p.ShouldOverrideBuilder, fromCancun)
 
 	ssz.DefineDynamicObjectContent(c, &p.Payload)
-	ssz.DefineDynamicObjectContent(c, &p.BlobsBundle)
-	ssz.DefineSliceOfDynamicBytesContent(c, &p.ExecutionRequests, MaxExecutionRequestsPerPayload, MaxBytesPerExecutionRequest)
+	ssz.DefineDynamicObjectContentOnFork(c, &p.BlobsBundleV1, cancunToOsaka)
+	ssz.DefineDynamicObjectContentOnFork(c, &p.BlobsBundleV2, fromOsaka)
+	ssz.DefineSliceOfDynamicBytesContentOnFork(c, &p.ExecutionRequests, MaxExecutionRequestsPerPayload, MaxBytesPerExecutionRequest, fromPrague)
 }
 
 // ForkchoiceUpdateAmsterdam is the request body of POST /amsterdam/forkchoice.

beacon/engine/ssz/forkmap.go

@@ -37,6 +37,19 @@ const (
 	forkAmsterdam = ssz.ForkPectra + 2
 )
 
+// AtLeast reports whether the ssz fork sf is at or beyond the geth fork f in
+// the codec's ordering. It encapsulates the local forkOsaka/forkAmsterdam
+// aliases so callers outside this package can compare against post-Pectra forks
+// without naming the unexported constants. Pre-Engine-API forks (no SSZ wire
+// representation) compare as not-reached.
+func AtLeast(sf ssz.Fork, f forks.Fork) bool {
+	target, ok := ForkFor(f)
+	if !ok {
+		return false
+	}
+	return sf >= target
+}
+
 // ForkFor maps a geth params/forks.Fork onto the karalabe/ssz Fork value
 // the codec multiplexes on. The bool is false for forks that predate the
 // Engine API (and thus have no SSZ wire representation here).

beacon/engine/ssz/payload.go

@@ -36,6 +36,13 @@ var (
 	fromCancun = ssz.ForkFilter{Added: ssz.ForkDencun}
 	// beacon-root attribute, introduced in Cancun (Dencun).
 	// (shares the Cancun boundary but kept named for clarity at call sites)
+	// execution-requests group, introduced in Prague (Pectra).
+	fromPrague = ssz.ForkFilter{Added: ssz.ForkPectra}
+	// single-proof blobs bundle (BlobsBundleV1), active Cancun..Prague; replaced
+	// by the cell-proof BlobsBundleV2 from Osaka on.
+	cancunToOsaka = ssz.ForkFilter{Added: ssz.ForkDencun, Removed: forkOsaka}
+	// cell-proof blobs bundle (BlobsBundleV2), introduced in Osaka.
+	fromOsaka = ssz.ForkFilter{Added: forkOsaka}
 	// bal + slot group, introduced in Amsterdam.
 	fromAmsterdam = ssz.ForkFilter{Added: forkAmsterdam}
 )

beacon/engine/ssz/roundtrip_test.go

@@ -17,6 +17,7 @@
 package ssz
 
 import (
+	"encoding/binary"
 	"reflect"
 	"testing"
 
@@ -157,3 +158,157 @@ func TestForkchoiceUpdateAmsterdamRoundtrip(t *testing.T) {
 	}
 	encDecOnFork(t, bare, forkAmsterdam, func() *ForkchoiceUpdateAmsterdam { return new(ForkchoiceUpdateAmsterdam) })
 }
+
+// minimalPayload builds an ExecutionPayload carrying exactly the fields the
+// given fork's wire shape requires (BaseFeePerGas is always present; blob-gas
+// pointers from Cancun; slot from Amsterdam), so it round-trips cleanly at fork.
+func minimalPayload(fork ssz.Fork) *ExecutionPayload {
+	p := &ExecutionPayload{BaseFeePerGas: uint256.NewInt(7e9)}
+	if fork >= ssz.ForkDencun {
+		blob, excess := uint64(0), uint64(0)
+		p.BlobGasUsed, p.ExcessBlobGas = &blob, &excess
+	}
+	if fork >= forkAmsterdam {
+		slot := uint64(0)
+		p.SlotNumber = &slot
+	}
+	return p
+}
+
+// allEngineForks enumerates the codec forks the Engine API v2 spec covers
+// (Paris onward), paired with the spec's fixed-part sizes for the envelope and
+// built-payload wrappers.
+var allEngineForks = []struct {
+	name            string
+	fork            ssz.Fork
+	envelopeFixed   uint32 // ExecutionPayloadEnvelope fixed part
+	builtPayloadFix uint32 // BuiltPayload fixed part
+	hasBeaconRoot   bool   // Cancun+
+	hasRequests     bool   // Prague+
+	hasBundle       bool   // Cancun+
+	bundleIsV2      bool   // Osaka+
+}{
+	// envelope fixed: offset(payload)=4 [+root 32 from Cancun] [+offset(requests) 4 from Prague]
+	// built fixed:    offset(payload)=4 + value 32 [+offset(bundle) 4 + override 1 from Cancun] [+offset(requests) 4 from Prague]
+	{"paris", ssz.ForkParis, 4, 36, false, false, false, false},
+	{"shanghai", ssz.ForkShapella, 4, 36, false, false, false, false},
+	{"cancun", ssz.ForkDencun, 36, 41, true, false, true, false},
+	{"prague", ssz.ForkPectra, 40, 45, true, true, true, false},
+	{"osaka", forkOsaka, 40, 45, true, true, true, true},
+	{"amsterdam", forkAmsterdam, 40, 45, true, true, true, true},
+}
+
+// TestExecutionPayloadEnvelopePerFork verifies the envelope wire shape matches
+// the per-fork ExecutionPayloadEnvelope catalogue in refactor-ssz.md for every
+// fork the spec covers: bare payload for Paris/Shanghai, +parent_beacon_block_root
+// from Cancun, +execution_requests from Prague.
+func TestExecutionPayloadEnvelopePerFork(t *testing.T) {
+	for _, tc := range allEngineForks {
+		t.Run(tc.name, func(t *testing.T) {
+			env := &ExecutionPayloadEnvelopeAmsterdam{Payload: minimalPayload(tc.fork)}
+			if tc.hasBeaconRoot {
+				env.ParentBeaconBlockRoot = &common.Hash{0x55}
+			}
+			if tc.hasRequests {
+				env.ExecutionRequests = [][]byte{{0x01, 0x02}}
+			}
+			encDecOnFork(t, env, tc.fork, func() *ExecutionPayloadEnvelopeAmsterdam {
+				return new(ExecutionPayloadEnvelopeAmsterdam)
+			})
+
+			// Pre-Cancun must not carry a beacon root; pre-Prague must not carry
+			// requests — the codec drops them, so a decoded copy stays empty.
+			buf := make([]byte, ssz.SizeOnFork(env, tc.fork))
+			if err := ssz.EncodeToBytesOnFork(buf, env, tc.fork); err != nil {
+				t.Fatalf("encode: %v", err)
+			}
+			// payload is the first (dynamic) field, so its offset equals the
+			// fixed-part length — the spec's per-fork envelope size.
+			if off := readOffset(buf); off != tc.envelopeFixed {
+				t.Errorf("envelope fixed size = %d, want %d", off, tc.envelopeFixed)
+			}
+			got := new(ExecutionPayloadEnvelopeAmsterdam)
+			if err := ssz.DecodeFromBytesOnFork(buf, got, tc.fork); err != nil {
+				t.Fatalf("decode: %v", err)
+			}
+			if !tc.hasBeaconRoot && got.ParentBeaconBlockRoot != nil {
+				t.Errorf("%s: beacon root decoded but fork predates Cancun", tc.name)
+			}
+			if tc.hasBeaconRoot && got.ParentBeaconBlockRoot == nil {
+				t.Errorf("%s: beacon root missing after roundtrip", tc.name)
+			}
+			if !tc.hasRequests && len(got.ExecutionRequests) > 0 {
+				t.Errorf("%s: requests decoded but fork predates Prague", tc.name)
+			}
+		})
+	}
+}
+
+// TestBuiltPayloadPerFork verifies the BuiltPayload wire shape matches the
+// per-fork BuiltPayload catalogue in refactor-ssz.md: {payload, block_value}
+// for Paris/Shanghai, +blobs_bundle(V1)+should_override_builder from Cancun,
+// +execution_requests from Prague, blobs_bundle→V2 from Osaka.
+func TestBuiltPayloadPerFork(t *testing.T) {
+	for _, tc := range allEngineForks {
+		t.Run(tc.name, func(t *testing.T) {
+			bp := &BuiltPayloadAmsterdam{
+				Payload:    minimalPayload(tc.fork),
+				BlockValue: uint256.NewInt(1000),
+			}
+			if tc.hasBundle {
+				bundle := func() ([][48]byte, [][48]byte, []*Blob) {
+					return [][48]byte{{0x01}}, [][48]byte{{0x02}}, []*Blob{{Bytes: make([]byte, BytesPerBlob)}}
+				}
+				c, p, b := bundle()
+				if tc.bundleIsV2 {
+					bp.BlobsBundleV2 = &BlobsBundleV2{Commitments: c, Proofs: p, Blobs: b}
+				} else {
+					bp.BlobsBundleV1 = &BlobsBundleV1{Commitments: c, Proofs: p, Blobs: b}
+				}
+				override := true
+				bp.ShouldOverrideBuilder = &override
+			}
+			if tc.hasRequests {
+				bp.ExecutionRequests = [][]byte{{0xaa}}
+			}
+			encDecOnFork(t, bp, tc.fork, func() *BuiltPayloadAmsterdam { return new(BuiltPayloadAmsterdam) })
+
+			buf := make([]byte, ssz.SizeOnFork(bp, tc.fork))
+			if err := ssz.EncodeToBytesOnFork(buf, bp, tc.fork); err != nil {
+				t.Fatalf("encode: %v", err)
+			}
+			// payload is the first (dynamic) field, so its offset equals the
+			// fixed-part length — the spec's per-fork built-payload size.
+			if off := readOffset(buf); off != tc.builtPayloadFix {
+				t.Errorf("built-payload fixed size = %d, want %d", off, tc.builtPayloadFix)
+			}
+			got := new(BuiltPayloadAmsterdam)
+			if err := ssz.DecodeFromBytesOnFork(buf, got, tc.fork); err != nil {
+				t.Fatalf("decode: %v", err)
+			}
+			// Exactly the right bundle revision is populated (or neither pre-Cancun).
+			if tc.bundleIsV2 && got.BlobsBundleV1 != nil {
+				t.Errorf("%s: V1 bundle decoded for an Osaka+ fork", tc.name)
+			}
+			if tc.hasBundle && !tc.bundleIsV2 && got.BlobsBundleV2 != nil {
+				t.Errorf("%s: V2 bundle decoded for a pre-Osaka fork", tc.name)
+			}
+			if !tc.hasBundle && (got.BlobsBundleV1 != nil || got.BlobsBundleV2 != nil) {
+				t.Errorf("%s: bundle decoded but fork predates Cancun", tc.name)
+			}
+			if !tc.hasBundle && got.ShouldOverrideBuilder != nil {
+				t.Errorf("%s: should_override_builder decoded but fork predates Cancun", tc.name)
+			}
+			if !tc.hasRequests && len(got.ExecutionRequests) > 0 {
+				t.Errorf("%s: requests decoded but fork predates Prague", tc.name)
+			}
+		})
+	}
+}
+
+// readOffset reads the first 4-byte little-endian SSZ offset from buf. For a
+// container whose first field is dynamic, this offset equals the length of the
+// fixed part (where the variable region begins).
+func readOffset(buf []byte) uint32 {
+	return binary.LittleEndian.Uint32(buf[:4])
+}

beacon/engine/ssz/shared.go

@@ -34,7 +34,7 @@ func (b *Blob) DefineSSZ(c *ssz.Codec) {
 	ssz.DefineCheckedStaticBytes(c, &b.Bytes, BytesPerBlob)
 }
 
-// BlobCell wraps a single BYTES_PER_CELL = 1024 byte cell. Same wrapper
+// BlobCell wraps a single BYTES_PER_CELL = 2048 byte cell. Same wrapper
 // rationale as Blob.
 type BlobCell struct {
 	Bytes []byte
@@ -59,7 +59,7 @@ func (b *Bitvector128) DefineSSZ(c *ssz.Codec) {
 }
 
 // OptionalBlobCell models `Optional[ByteVector[BYTES_PER_CELL]]` =
-// `List[BlobCell, 1]`. Length 0 = absent, length 1 = present (1024 bytes).
+// `List[BlobCell, 1]`. Length 0 = absent, length 1 = present (2048 bytes).
 type OptionalBlobCell struct {
 	Cells []*BlobCell
 }

eth/engineapi/get_payload.go

@@ -56,42 +56,83 @@ func (rt *Router) handleGetPayload(w http.ResponseWriter, r *http.Request, fork
 }
 
 // buildBuiltPayloadAmsterdam packages an engine.ExecutionPayloadEnvelope into
-// the SSZ BuiltPayload shape. BlockValue/BlobsBundle/Requests come straight
-// across; the inner payload goes through the SSZ converter.
+// the SSZ BuiltPayload shape for the URL fork. BlockValue/Requests come straight
+// across; the inner payload goes through the SSZ converter. The blobs bundle is
+// emitted as V1 (Cancun/Prague) or V2 (Osaka+) per the fork; pre-Cancun forks
+// carry no bundle (and no should_override_builder), so those fields are left
+// nil and the codec drops them.
 func buildBuiltPayloadAmsterdam(env *engine.ExecutionPayloadEnvelope, sf ssz.Fork) *sszt.BuiltPayloadAmsterdam {
 	out := &sszt.BuiltPayloadAmsterdam{
 		Payload:    sszt.ExecutionPayloadFromEngine(env.ExecutionPayload, sf),
 		BlockValue: new(uint256.Int),
-		ExecutionRequests:     env.Requests,
-		ShouldOverrideBuilder: env.Override,
 	}
 	if env.BlockValue != nil {
 		out.BlockValue.SetFromBig(env.BlockValue)
 	}
+	// execution_requests and should_override_builder exist from Prague and
+	// Cancun respectively; the codec gates them, so it is safe to always set
+	// the values the EL produced — the gated-off forks simply ignore them.
+	if sszt.AtLeast(sf, forks.Prague) {
+		out.ExecutionRequests = env.Requests
+	}
+	if sszt.AtLeast(sf, forks.Cancun) {
+		override := env.Override
+		out.ShouldOverrideBuilder = &override
+	}
+	// Select the bundle revision. Cancun/Prague use V1 (one proof per blob);
+	// Osaka+ uses V2 (cell proofs). Pre-Cancun forks have no bundle.
+	switch {
+	case sszt.AtLeast(sf, forks.Osaka):
 		if env.BlobsBundle != nil {
-		out.BlobsBundle = convertBlobsBundle(env.BlobsBundle)
+			out.BlobsBundleV2 = convertBlobsBundleV2(env.BlobsBundle)
 		} else {
-		out.BlobsBundle = new(sszt.BlobsBundleV2)
+			out.BlobsBundleV2 = new(sszt.BlobsBundleV2)
+		}
+	case sszt.AtLeast(sf, forks.Cancun):
+		if env.BlobsBundle != nil {
+			out.BlobsBundleV1 = convertBlobsBundleV1(env.BlobsBundle)
+		} else {
+			out.BlobsBundleV1 = new(sszt.BlobsBundleV1)
+		}
 	}
 	return out
 }
 
-// convertBlobsBundle copies the JSON BlobsBundle into the SSZ V2 layout.
-// Inputs are length-validated by the caller's miner pipeline.
-func convertBlobsBundle(b *engine.BlobsBundle) *sszt.BlobsBundleV2 {
+// convertBlobsBundleV2 copies the JSON BlobsBundle into the SSZ V2 (cell-proof)
+// layout. Inputs are length-validated by the caller's miner pipeline.
+func convertBlobsBundleV2(b *engine.BlobsBundle) *sszt.BlobsBundleV2 {
 	out := &sszt.BlobsBundleV2{
 		Commitments: make([][48]byte, len(b.Commitments)),
 		Proofs:      make([][48]byte, len(b.Proofs)),
 		Blobs:       make([]*sszt.Blob, len(b.Blobs)),
 	}
-	for i, c := range b.Commitments {
-		copy(out.Commitments[i][:], c)
-	}
-	for i, p := range b.Proofs {
-		copy(out.Proofs[i][:], p)
-	}
-	for i, blob := range b.Blobs {
-		out.Blobs[i] = &sszt.Blob{Bytes: append([]byte(nil), blob...)}
-	}
+	fillBundle(out.Commitments, out.Proofs, out.Blobs, b)
 	return out
 }
+
+// convertBlobsBundleV1 copies the JSON BlobsBundle into the SSZ V1 (single-proof)
+// layout used by Cancun/Prague.
+func convertBlobsBundleV1(b *engine.BlobsBundle) *sszt.BlobsBundleV1 {
+	out := &sszt.BlobsBundleV1{
+		Commitments: make([][48]byte, len(b.Commitments)),
+		Proofs:      make([][48]byte, len(b.Proofs)),
+		Blobs:       make([]*sszt.Blob, len(b.Blobs)),
+	}
+	fillBundle(out.Commitments, out.Proofs, out.Blobs, b)
+	return out
+}
+
+// fillBundle copies the commitments/proofs/blobs from a JSON BlobsBundle into
+// the destination SSZ slices (shared by the V1 and V2 converters, whose wire
+// layout is identical).
+func fillBundle(commitments, proofs [][48]byte, blobs []*sszt.Blob, b *engine.BlobsBundle) {
+	for i, c := range b.Commitments {
+		copy(commitments[i][:], c)
+	}
+	for i, p := range b.Proofs {
+		copy(proofs[i][:], p)
+	}
+	for i, blob := range b.Blobs {
+		blobs[i] = &sszt.Blob{Bytes: append([]byte(nil), blob...)}
+	}
+}

eth/engineapi/payloads.go

@@ -50,8 +50,9 @@ func (rt *Router) handleNewPayload(w http.ResponseWriter, r *http.Request, fork
 		writeProblem(w, http.StatusUnprocessableEntity, ErrInvalidBody, err.Error())
 		return
 	}
-	root := env.ParentBeaconBlockRoot
-	status, err := rt.backend.NewPayload(r.Context(), *data, versionedHashes, &root, env.ExecutionRequests)
+	// ParentBeaconBlockRoot is absent (nil) for Paris/Shanghai and present from
+	// Cancun on; pass it through as-is so the EL sees the correct optionality.
+	status, err := rt.backend.NewPayload(r.Context(), *data, versionedHashes, env.ParentBeaconBlockRoot, env.ExecutionRequests)
 	if err != nil {
 		mapBackendErr(w, err)
 		return

eth/engineapi/router_test.go

@@ -149,7 +149,7 @@ func TestRouterNewPayload(t *testing.T) {
 			ExcessBlobGas: &excess,
 			SlotNumber:    &slot,
 		},
-		ParentBeaconBlockRoot: common.Hash{0x55},
+		ParentBeaconBlockRoot: &common.Hash{0x55},
 	}
 	resp := sszPost(t, srv, "/amsterdam/payloads", env, amsterdam)
 	if resp.StatusCode != 200 {
@@ -257,7 +257,7 @@ func TestRouterAdvertisedForkRoutable(t *testing.T) {
 			BlobGasUsed:   &blob,
 			ExcessBlobGas: &excess,
 		},
-		ParentBeaconBlockRoot: common.Hash{0x55},
+		ParentBeaconBlockRoot: &common.Hash{0x55},
 	}
 	resp = sszPost(t, srv, "/osaka/payloads", penv, osaka)
 	if resp.StatusCode != 200 {