feat(engine/ssz): add target_gas_limit to PayloadAttributesV4 wire#11646
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benaadams merged 1 commit intoMay 18, 2026
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Aligns the SSZ wire schema for engine_forkchoiceUpdatedV4 with the target_gas_limit field added to PayloadAttributesV4 in execution-apis PR NethermindEth#796. 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. JSON-RPC support for TargetGasLimit landed in 4e226fd ("feat(engine): support targetGasLimit in PayloadAttributesV4"); this plumbs the same value through the SSZ-REST decoder. Changes: - PayloadAttributesWire gains target_gas_limit: uint64 at the end of the container (matches execution-apis ssz-encoding.md). - SszCodec.PayloadAttributesFromWire forwards the wire ulong as long to PayloadAttributes.TargetGasLimit. - DecodeFcuV4Request roundtrip test now also asserts target_gas_limit survives encode/decode.
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Summary
target_gas_limit: uint64to the SSZPayloadAttributesWire(V4) and plumbs it throughSszCodec.PayloadAttributesFromWireinto the existingPayloadAttributes.TargetGasLimitdomain field.DecodeFcuV4Requestround-trip test to assert the new field survives encode/decode.Context
JSON-RPC support for
targetGasLimitlanded in 4e226fd (feat(engine): support targetGasLimit in PayloadAttributesV4). The SSZ wire schema lagged behind, so CLs that include the alpha-8targetGasLimitover the SSZ-REST transport (POST /engine/v4/forkchoice) get rejected as Malformed SSZ body — the 8 trailing bytes shift the innerwithdrawalsoffset insidePayloadAttributesV4.execution-apis PR #796 added
targetGasLimitto the JSON spec (commit a22fbd4). The matching SSZ-encoding spec change was just submitted in ethereum/execution-apis#764 (commit 949d6a8 on thebbusa/sszbranch). This PR aligns Nethermind's SSZ decoder with that schema so it accepts the field on the wire.Hit in practice
Consensoor on Gloas devnet hits this every fcU at slot transition:
After this fix the EL decodes
PayloadAttributesV4with 7 fields (target_gas_limitlast) and forwards the value toPayloadAttributes.TargetGasLimit.Test plan
DecodeFcuV4Request_spec_layout_roundtrips_parent_beacon_block_root_and_slot_numbernow also assertstarget_gas_limitround-trips