feat(engine/ssz): add target_gas_limit to PayloadAttributesV4 wire#11647
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benaadams merged 1 commit intoMay 18, 2026
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Plumbs the new TargetGasLimit field added in this PR through the SSZ-REST wire schema for engine_forkchoiceUpdatedV4 (PR NethermindEth#764). Without this, CLs that include target_gas_limit in the SSZ body get rejected as "Malformed SSZ body" because the 8 extra trailing bytes shift the inner withdrawals offset. The wire field is a required fixed-size uint64 (per execution-apis ssz-encoding.md), so a missing value fails SSZ decode directly — the V4 null-guard in PayloadAttributes.GetInvalidPayloadAttributesMessage remains as defense-in-depth for the JSON path. Changes: - PayloadAttributesWire gains target_gas_limit at the end of the container (matches execution-apis ssz-encoding.md PayloadAttributesV4). - SszCodec.PayloadAttributesFromWire forwards the wire ulong as long to PayloadAttributes.TargetGasLimit. - DecodeFcuV4Request roundtrip test now also asserts target_gas_limit survives encode/decode, using a diverse-byte value (0x0123456789ABCDEF).
barnabasbusa
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LukaszRozmej,
Marchhill,
MarekM25,
benaadams and
flcl42
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benaadams
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May 18, 2026
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benaadams
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NethermindEth:feat/engine-payload-attrs-target-gas-limit
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Summary
Stacked on top of #11611. Plumbs the new `TargetGasLimit` field through the SSZ-REST wire schema for `engine_forkchoiceUpdatedV4` (introduced in #11611 for JSON-RPC).
Why
Without the SSZ wire counterpart, CLs that send `targetGasLimit` over the SSZ-REST transport (`POST /engine/v4/forkchoice`, advertised under execution-apis PR #764) get rejected as Malformed SSZ body — the 8 extra trailing bytes shift the inner `withdrawals` offset inside `PayloadAttributesV4`.
Spec alignment:
Fail-loud guarantee
The wire `target_gas_limit` is a required fixed-size `uint64` (per ssz-encoding.md), so a missing value fails SSZ decode directly — the V4 null-guard in `PayloadAttributes.GetInvalidPayloadAttributesMessage` (`Producers/PayloadAttributes.cs:232`) remains as defense-in-depth for the JSON path. No default-value fallback anywhere.
Sister PRs
Test plan