EIP complexity assessment

EIP-7666: EVM-ify the identity precompile

Assessed in Hegotá. The score describes the EIP text available at the snapshot, not the EIP as it stands today.

ProspectiveHegotáSnapshot 2026-08-25PFI at snapshotLayers: execution

LLM Completescore 15

Human Draft PRscore 12 · Checklist revision 2· ethspecs/pm #112 (draft)

LLM · Checklist revision 22026-08-26 · Original snapshot · 15 Human · Checklist revision 2Draft PR · 12 CompareHuman vs LLM · same checklist revision

Evaluated on: 2026-08-26 · Spec revision: 2026-08-25 · ac450a4ab2 · Inclusion status at snapshot: PFI

Scope at the cutoff. Execution-layer assessment of the Draft EIP-7666 snapshot. The proposal removes identity-precompile treatment at address 0x04 on the activation block and installs fixed stateless EVM bytecode there, preserving calldata echo functionality while changing gas behavior. Only eip.md, rubric.md, and supporting/eip-3855.md were used as scoring evidence.

15MediumMedium

Evaluator: LLMChecklist v2
Confidence: Medium
Under-specified at assessment cutoff: No
Plausible range: 15–15 (Medium)
Snapshot: 2026-08-25 · EIP revision ac450a4ab2 (2026-08-25)

Score bands · Checklist revision 2

Low <12
Medium 12–22
High ≥23

28 criteria scored 0–3 (4 in exceptional cases; cross-EIP interactions is uncapped); nominal maximum 84.

Complexity profile

Each segment is one criterion's contribution to the LLM total. Hover or focus a segment for its score and rationale.

Under-specified at assessment cutoff: No

The EIP text available at the assessment cutoff left material behavior unresolved. The affected criteria and the plausible total range record that uncertainty.

The assessor found no material behavior left unresolved by the EIP text at the cutoff.

Notable ambiguities noted by the assessor (2)

The package does not describe the test inventory or transition-tool plumbing, limiting confidence in test-breadth and interface scores without creating a textual consensus gap.
The normative instruction to set code does not separately enumerate unchanged account fields; the assessment reads it as a code-only update and does not multiply that ordinary reading across state-gas or system-contract anchors.

Criterion breakdown

EIP-7666 Hegotá: LLM criterion scores and rationale
Criterion	Score	Why this score	Evidence / uncertainty
New fork activation mechanism	3	The proposal explicitly mandates a state modification at the fork-activation block, exactly matching the score-3 anchor.	eip.md · Abstract; Specification At the start of the activation block, clients must set address 0x04 code to the specified seven-byte EVM program and stop treating the address as a precompile. Confidence: High Uncertainty: Precompile classification also changes at the same boundary, but score 3 is already the permitted non-exceptional maximum.
Modified precompiles	2	One pre-existing precompile has its behavior modified through removal of precompile handling and replacement by contract execution. It is the simple identity operation, so the complex-single-precompile score does not apply.	eip.md · Abstract; Specification; Backwards Compatibility Identity at 0x04 ceases to be treated as a precompile and its equivalent output is supplied by EVM code with slightly different gas costs. Confidence: High Uncertainty: Functional output is intended to remain equal, but execution classification and gas behavior change unambiguously.
New invariant on pre-existing tests	2	Activation-spanning post-state tests form a broad category that mechanically gains an assertion about code at 0x04. The text does not support the stronger claim that every fork test gains a dedicated assertion or that pre-fork vectors are re-derived.	eip.md · Abstract; Specification At activation, address 0x04 must contain the specified bytecode and must cease to be treated as a precompile from that block onward. Confidence: Medium Uncertainty: The exact breadth depends on how existing tests represent fork-transition post-state, which is not described in the package.
Edge/boundary conditions	2	Testing has at least two boundary-prone dimensions: before/at/after activation and calldata/memory/gas thresholds for equivalent output versus out-of-gas behavior. Neither is shown to require an elevated case count.	eip.md · Specification; Rationale; Backwards Compatibility Behavior changes exactly at the activation block, while the replacement handles variable-length calldata through copy and memory operations with different gas costs. Confidence: High Uncertainty: The EIP gives no explicit boundary test matrix, so only boundaries directly implied by the activation rule and bytecode are counted.
Added system contracts	1	One stateless protocol-installed contract is introduced, and it triggers no new system action.	eip.md · Abstract; Specification; Rationale The protocol installs fixed EVM code at address 0x04; that code only echoes calldata and contains no state-writing or system-action instruction. Confidence: High Uncertainty: The contract occupies a former precompile address, but after activation it is ordinary EVM code and fits the rubric's non-stateful system-contract anchor.
EVM Gas rule changes	1	Existing identity-precompile metering is replaced by ordinary opcode, copy, and memory-expansion metering. This updates an existing gas-accounting path without introducing a new gas-accounting mechanism.	eip.md · Specification; Backwards Compatibility The identity address stops using precompile handling and instead executes fixed EVM code; the proposal explicitly says the resulting gas costs are slightly different. Confidence: High Uncertainty: The text does not enumerate the exact gas deltas, but the fixed bytecode determines the post-activation execution path under existing EVM rules.
Patterns affecting pre-existing tests	1	A minor, localized subset of existing tests covering identity-precompile calls, their gas thresholds, or the activation boundary must be reworked. No diverse or major test category is changed by the package evidence.	eip.md · Specification; Backwards Compatibility Identity calls change from precompile execution to EVM bytecode and have slightly different gas costs beginning at one fork boundary. Confidence: Medium Uncertainty: The package contains no test inventory, so the size classification follows only the proposal's single-address scope.
Security risks	1	Correct code installation, precompile deactivation, and output equivalence are consensus-sensitive, but the mechanism is self-contained, isolatable, and does not state a change to existing security invariants.	eip.md · Specification; Security Considerations A precompile is replaced by fixed stateless code; the EIP says no functionality is made cheaper or newly introduced and identifies no security concern. Confidence: Medium Uncertainty: The package assertion of no security concern is not implementation evidence, so a minimal self-contained review burden remains.
Performance risks	1	The replacement execution path warrants isolated benchmarking across input sizes, but it is self-contained and does not alter general EVM performance behavior.	eip.md · Motivation; Specification; Rationale Native identity-precompile handling is replaced by a short EVM program that performs calldata copying and memory return at a single address. Confidence: Medium Uncertainty: The package gives no benchmark results or usage profile that would support a broader impact score.
Cross-EIP interactions	1	EIP-7666 has one narrow dependency on EIP-3855 for execution of the embedded PUSH0 instructions. The interaction is limited and most replacement behavior can be tested independently, so coordinated testing is non-critical.	eip.md · Front matter `requires`; Rationale The proposal requires EIP-3855 because its fixed bytecode uses PUSH0. supporting/eip-3855.md · Specification EIP-3855 defines PUSH0 at opcode 0x5f with a cost of 2 gas. Confidence: High Uncertainty: EIP-5656 appears only as motivation and is neither required nor used by the specified replacement bytecode, so it is not counted as an interacting EIP. Interacting EIPs: EIP-3855

Show 18 zero-score criteria

Zero-score criteria (Checklist revision 2)
Criterion	Why this score	Evidence / uncertainty
Added opcodes	No opcode is introduced by EIP-7666.	eip.md · Rationale The replacement bytecode is composed entirely of named existing opcodes. Uncertainty: PUSH0 is a dependency defined by EIP-3855, not an opcode newly introduced by this proposal.
Modified opcodes	No pre-existing opcode behavior is modified or deprecated.	eip.md · Specification; Rationale The proposal changes precompile classification and installs code, not opcode results. Uncertainty: Different gas and callee execution at address 0x04 do not constitute a specified result change to an opcode under this anchor.
Added precompiles	No new precompile is introduced.	eip.md · Abstract; Specification The proposal removes identity-precompile treatment and adds no precompile. Uncertainty: The replacement is explicitly EVM code, not another precompile.
Modified system contracts	No pre-existing system contract is modified; the precompile change is scored in its dedicated anchor and the replacement contract in the added-contract anchor.	eip.md · Specification The proposal replaces a precompile with newly installed code and identifies no pre-existing system contract whose code, state, or behavior is changed. Uncertainty: The package does not classify the identity precompile as a system contract.
State-access ordering within opcode execution	No opcode's internal state-access or gas-charge ordering is changed. The activation write is a block-boundary transition and is outside this anchor.	eip.md · Specification The change installs code at the activation boundary and removes precompile treatment; it specifies no reordering of state access or gas charging inside any opcode. Uncertainty: Calls to 0x04 take a different callee execution path, but the package does not change the within-opcode ordering measured by this anchor.
Blob gas accounting changes	No blob-gas rule or mechanism is introduced or modified.	eip.md · Specification The specification is limited to address 0x04 code and precompile treatment. Uncertainty: No blob-related behavior appears anywhere in the proposal.
State gas accounting changes	The irregular activation state change does not introduce a state-gas charging site or alter state-gas accounting; its complexity is scored under fork activation.	eip.md · Specification The proposal mandates a one-time code assignment at activation but defines no StateGasCosts, state-byte rate, state-gas budget, reservoir, or spill rule. Uncertainty: The EIP does not discuss charging the protocol-directed activation write, so no state-gas mechanism can be scored from the sealed text.
New EVM gas refund	No gas-refund mechanism is added or modified.	eip.md · Specification; Backwards Compatibility The only stated gas effect is a different execution cost for identity behavior. Uncertainty: The proposal contains no refund behavior.
New transaction types	No new transaction type is introduced.	eip.md · Specification The specification introduces no transaction envelope or type. Uncertainty: Transactions may call 0x04, but their type is unchanged.
New or modified transaction validity mechanisms	No transaction validity mechanism or intrinsic gas rule is changed.	eip.md · Specification; Backwards Compatibility The change affects execution and gas consumed at one called address, not transaction validity rules or intrinsic-gas calculation. Uncertainty: Runtime out-of-gas outcomes are covered by EVM gas behavior, not validity.
New block / header fields	No new block or block-header field is introduced.	eip.md · Specification The activation rule adds no block-body or header field. Uncertainty: Activation at a block boundary does not itself add a field.
Encoding changes (RLP/SSZ)	The proposal introduces no RLP, SSZ, or other interface-level encoding change.	eip.md · Specification No transaction, block, or interface encoding is changed. Uncertainty: The literal EVM bytecode value is contract code, not an interface encoding.
Block syncing changes	No block-RLP validation mechanism is introduced.	eip.md · Specification The block format and RLP validation are not changed. Uncertainty: The activation state transition is not a block-encoding change.
Engine API changes	No Engine API field or communication mechanism is introduced.	eip.md · Specification The proposal defines no Engine API endpoint, field, or message change. Uncertainty: No Engine API surface is present in the package evidence.
Transition-tool interface changes	No transition-tool interface modification is specified or required by the text.	eip.md · Specification The specification keys the state change to the activation block but adds no input, output, field, or communication mechanism for transition tools. Uncertainty: A tool must apply the rule at the activation block, but any implementation-specific plumbing cannot be inferred as a new interface field from this package.
New test-framework primitives	The package provides no requirement for a new expectation type, modifier, helper, or other test-framework abstraction.	eip.md · Specification; Rationale The behavior is expressed as fixed code installation plus ordinary EVM calldata copying and return operations. Uncertainty: Fork-transition tests may need ordinary setup, but the sealed evidence does not show that existing primitives are insufficient.
Cryptography	No cryptographic mechanism is introduced or modified.	eip.md · Rationale The replacement code only copies calldata to memory and returns it. Uncertainty: No cryptographic operation appears in the specified bytecode.
Unspecified behavior requiring cross-client consensus	For the specified execution-layer surface, constructible outcomes follow from the exact code and existing EVM execution semantics; no unresolved consensus choice is exposed by the sealed text.	eip.md · Specification; Rationale The address, exact bytecode, activation timing, post-activation classification, and intended calldata-return behavior are all stated explicitly. Uncertainty: External implementation, devnet, and discussion status are prohibited and unavailable; confidence is therefore limited to the textual completeness of the snapshot.

Assessment provenance

Assessed EIP revision: ethereum/EIPs@ac450a4ab2 EIPS/eip-7666.md committed 2026-08-25 · information cutoff 2026-08-25T11:56:58Z
Current master · File history · blob 6b0b4a6d13 · sha256 ea392f32efc0
Rubric: Checklist revision 2 · ethspecs/pm@3d8c0128c5
Evaluator: gpt-5.6-sol at xhigh reasoning effort · isolation bubblewrap_one_eip_capsule_v1
Source record: Frozen research record research/tasks/08-hegota-prospective-complexity-assessment/outputs/assessments/hegota-pfi-2026-08-26/eip-7666.yaml · sha256 3bc02ad8f419
Supporting documents in the sealed package: supporting/eip-3855.md

Evaluated on: Not recorded

12MediumMedium

Evaluator: HumanChecklist v2
Confidence: Not recorded
Under-specified at assessment cutoff: Not recorded in the checklist
Checklist published: 2026-08-18
Source: open ethspecs/pm pull request #112 (draft)

Score bands · Checklist revision 2

Low <12
Medium 12–22
High ≥23

28 criteria scored 0–3 (4 in exceptional cases; cross-EIP interactions is uncapped); nominal maximum 84.

Complexity profile

Each segment is one criterion's contribution to the Human total. Hover or focus a segment for its score and rationale.

Top complexity drivers

New fork activation mechanism3
Modified precompiles2
Added system contracts1
Patterns affecting pre-existing tests1

Criterion breakdown

EIP-7666 Hegotá: Human criterion scores and rationale
Criterion	Score	Why this score	Notes
New fork activation mechanism	3	Code is written to `0x04` at the start of the activation block — a protocol-mandated install with no deploying transaction, implemented in the prototype through the spec's irregular-state-transition hook (code only, nonce and balance preserved) plus a genesis pre-allocation for test fixtures.	—
Modified precompiles	2	A single pre-existing precompile's behavior changes: identity pricing moves from the precompile schedule to ordinary EVM execution, and EIP-2929 pre-warming at `0x04` is silently lost (unstated by the EIP) — first access in a transaction becomes cold.	—
Added system contracts	1	One stateless code deposit at the retired address; nothing in the protocol invokes it as a system actor. The deployment act is scored under "New fork activation mechanism".	—
Patterns affecting pre-existing tests	1	Measured: an EELS prototype flips 141 fixture executions across 11 functions — a minor, well-scoped subset, every flip diagnosed. Notably, several ported static fillers use the identity precompile as a memory-copy primitive inside unrelated harnesses (the MODEXP boundary suites), so the flips reach slightly beyond nominal identity tests.	—
New test-framework primitives	1	Existing primitives suffice with minor extension: a fork precompile-list subtraction and code pre-allocation at the retired address.	—
Security risks	1	Consensus-critical bytecode replaces a native implementation, but the program is seven bytes, specified verbatim in the EIP, and validated in isolation by differential runs against the retired implementation.	—
Edge/boundary conditions	1	A single boundary-prone mechanism: equivalence of the replacement code across calldata lengths, gas boundaries, and call contexts (STATICCALL, DELEGATECALL, EIP-7702 delegation with precompiles disabled). The 7-byte program keeps the surface small.	—
Cross-EIP interactions	1	Limited, independently testable interactions: EIP-2929 (warm-set membership at the retired address) and EIP-8200 (the shared retire-and-install mechanism, whose deployment semantics should be specified identically).	—
Unspecified behavior requiring cross-client consensus	1	The bytecode itself is pinned by the EIP, but deployment-account details are not: nonce/balance handling and interaction with any pre-existing state at `0x04` at the activation block (the prototype preserves both, installing code only), and the EIP-2929 warm-set consequence is unstated. All have an obvious intended reading.	—

Show 19 zero-score criteria

Zero-score criteria (Checklist revision 2)
Criterion	Why this score	Notes
Added opcodes	No rationale recorded.	—
Modified opcodes	No rationale recorded.	—
Added precompiles	No rationale recorded.	—
Modified system contracts	No rationale recorded.	—
EVM Gas rule changes	No gas accounting mechanism changes: the identity price constants disappear with the precompile, and the pricing shift is the "Modified precompiles" row's substance.	—
State-access ordering within opcode execution	No rationale recorded.	—
Blob gas accounting changes	No rationale recorded.	—
State gas accounting changes	No rationale recorded.	—
New EVM gas refund	No rationale recorded.	—
New transaction types	No rationale recorded.	—
New or modified transaction validity mechanisms	No rationale recorded.	—
New block / header fields	No rationale recorded.	—
Encoding changes (RLP/SSZ)	No rationale recorded.	—
Block syncing changes	No rationale recorded.	—
Engine API changes	No rationale recorded.	—
Transition-tool interface changes	No rationale recorded.	—
New invariant on pre-existing tests	No rationale recorded.	—
Performance risks	A seven-opcode copy program with gas scaling identical in shape to the precompile it replaces; nothing requires performance validation.	—
Cryptography	The identity function is a memory copy; nothing cryptographic is touched.	—

Assessment provenance

Rubric: Checklist revision 2 · ethspecs/pm@3d8c0128c5
Evaluator: STEEL team · ethspecs/pm complexity_assessments
Source record: Open draft pull request #112: Add EIP-7666 complexity assessment · checklist at 4a25f38a8f · updated 2026-08-18
blob 7e1838587c · sha256 28cc3069dff9
Research record: research/tasks/09-hegota-human-assessment-snapshot/outputs/assessments/eip-7666.yaml · sha256 dd0394a463f7

Both assessments applied Checklist revision 2 (28 criteria) to EIP-7666 in Hegotá. Δ is LLM minus Human.

Using the latest scored LLM evaluation for this checklist: 2026-08-26 · spec 2026-08-25 · ac450a4ab2. The Human and LLM assessments may use different spec revisions.

LLM15Medium

Human12Medium

Δ total+3Same tier

Criteria22/28agree exactly · 5 differ by 1 · 1 differ by 2+

Complexity profiles side by side

LLM

Human

Largest disagreements: New invariant on pre-existing tests (+2), EVM Gas rule changes (+1), New test-framework primitives (−1), Edge/boundary conditions (+1), Performance risks (+1)

Show differences only (6 criteria)

Per-criterion scores, Human versus LLM, ordered by the size of the difference
Criterion	LLM	Human	Δ	Agreement	Rationale from each source
New invariant on pre-existing tests	2	0	+2	Differ by 2+	Show rationale LLM Activation-spanning post-state tests form a broad category that mechanically gains an assertion about code at 0x04. The text does not support the stronger claim that every fork test gains a dedicated assertion or that pre-fork vectors are re-derived. Human No rationale recorded.
EVM Gas rule changes	1	0	+1	Differ by 1	Show rationale LLM Existing identity-precompile metering is replaced by ordinary opcode, copy, and memory-expansion metering. This updates an existing gas-accounting path without introducing a new gas-accounting mechanism. Human No gas accounting mechanism changes: the identity price constants disappear with the precompile, and the pricing shift is the "Modified precompiles" row's substance.
New test-framework primitives	0	1	−1	Differ by 1	Show rationale LLM The package provides no requirement for a new expectation type, modifier, helper, or other test-framework abstraction. Human Existing primitives suffice with minor extension: a fork precompile-list subtraction and code pre-allocation at the retired address.
Performance risks	1	0	+1	Differ by 1	Show rationale LLM The replacement execution path warrants isolated benchmarking across input sizes, but it is self-contained and does not alter general EVM performance behavior. Human A seven-opcode copy program with gas scaling identical in shape to the precompile it replaces; nothing requires performance validation.
Edge/boundary conditions	2	1	+1	Differ by 1	Show rationale LLM Testing has at least two boundary-prone dimensions: before/at/after activation and calldata/memory/gas thresholds for equivalent output versus out-of-gas behavior. Neither is shown to require an elevated case count. Human A single boundary-prone mechanism: equivalence of the replacement code across calldata lengths, gas boundaries, and call contexts (STATICCALL, DELEGATECALL, EIP-7702 delegation with precompiles disabled). The 7-byte program keeps the surface small.
Unspecified behavior requiring cross-client consensus	0	1	−1	Differ by 1	Show rationale LLM For the specified execution-layer surface, constructible outcomes follow from the exact code and existing EVM execution semantics; no unresolved consensus choice is exposed by the sealed text. Human The bytecode itself is pinned by the EIP, but deployment-account details are not: nonce/balance handling and interaction with any pre-existing state at `0x04` at the activation block (the prototype preserves both, installing code only), and the EIP-2929 warm-set consequence is unstated. All have an obvious intended reading.
Added opcodes	0	0	0	Agree	Show rationale LLM No opcode is introduced by EIP-7666. Human No rationale recorded.
Modified opcodes	0	0	0	Agree	Show rationale LLM No pre-existing opcode behavior is modified or deprecated. Human No rationale recorded.
Added precompiles	0	0	0	Agree	Show rationale LLM No new precompile is introduced. Human No rationale recorded.
Modified precompiles	2	2	0	Agree	Show rationale LLM One pre-existing precompile has its behavior modified through removal of precompile handling and replacement by contract execution. It is the simple identity operation, so the complex-single-precompile score does not apply. Human A single pre-existing precompile's behavior changes: identity pricing moves from the precompile schedule to ordinary EVM execution, and EIP-2929 pre-warming at `0x04` is silently lost (unstated by the EIP) — first access in a transaction becomes cold.
Added system contracts	1	1	0	Agree	Show rationale LLM One stateless protocol-installed contract is introduced, and it triggers no new system action. Human One stateless code deposit at the retired address; nothing in the protocol invokes it as a system actor. The deployment act is scored under "New fork activation mechanism".
Modified system contracts	0	0	0	Agree	Show rationale LLM No pre-existing system contract is modified; the precompile change is scored in its dedicated anchor and the replacement contract in the added-contract anchor. Human No rationale recorded.
State-access ordering within opcode execution	0	0	0	Agree	Show rationale LLM No opcode's internal state-access or gas-charge ordering is changed. The activation write is a block-boundary transition and is outside this anchor. Human No rationale recorded.
Blob gas accounting changes	0	0	0	Agree	Show rationale LLM No blob-gas rule or mechanism is introduced or modified. Human No rationale recorded.
State gas accounting changes	0	0	0	Agree	Show rationale LLM The irregular activation state change does not introduce a state-gas charging site or alter state-gas accounting; its complexity is scored under fork activation. Human No rationale recorded.
New EVM gas refund	0	0	0	Agree	Show rationale LLM No gas-refund mechanism is added or modified. Human No rationale recorded.
New transaction types	0	0	0	Agree	Show rationale LLM No new transaction type is introduced. Human No rationale recorded.
New or modified transaction validity mechanisms	0	0	0	Agree	Show rationale LLM No transaction validity mechanism or intrinsic gas rule is changed. Human No rationale recorded.
New block / header fields	0	0	0	Agree	Show rationale LLM No new block or block-header field is introduced. Human No rationale recorded.
Encoding changes (RLP/SSZ)	0	0	0	Agree	Show rationale LLM The proposal introduces no RLP, SSZ, or other interface-level encoding change. Human No rationale recorded.
Block syncing changes	0	0	0	Agree	Show rationale LLM No block-RLP validation mechanism is introduced. Human No rationale recorded.
New fork activation mechanism	3	3	0	Agree	Show rationale LLM The proposal explicitly mandates a state modification at the fork-activation block, exactly matching the score-3 anchor. Human Code is written to `0x04` at the start of the activation block — a protocol-mandated install with no deploying transaction, implemented in the prototype through the spec's irregular-state-transition hook (code only, nonce and balance preserved) plus a genesis pre-allocation for test fixtures.
Engine API changes	0	0	0	Agree	Show rationale LLM No Engine API field or communication mechanism is introduced. Human No rationale recorded.
Transition-tool interface changes	0	0	0	Agree	Show rationale LLM No transition-tool interface modification is specified or required by the text. Human No rationale recorded.
Patterns affecting pre-existing tests	1	1	0	Agree	Show rationale LLM A minor, localized subset of existing tests covering identity-precompile calls, their gas thresholds, or the activation boundary must be reworked. No diverse or major test category is changed by the package evidence. Human Measured: an EELS prototype flips 141 fixture executions across 11 functions — a minor, well-scoped subset, every flip diagnosed. Notably, several ported static fillers use the identity precompile as a memory-copy primitive inside unrelated harnesses (the MODEXP boundary suites), so the flips reach slightly beyond nominal identity tests.
Security risks	1	1	0	Agree	Show rationale LLM Correct code installation, precompile deactivation, and output equivalence are consensus-sensitive, but the mechanism is self-contained, isolatable, and does not state a change to existing security invariants. Human Consensus-critical bytecode replaces a native implementation, but the program is seven bytes, specified verbatim in the EIP, and validated in isolation by differential runs against the retired implementation.
Cryptography	0	0	0	Agree	Show rationale LLM No cryptographic mechanism is introduced or modified. Human The identity function is a memory copy; nothing cryptographic is touched.
Cross-EIP interactions	1	1	0	Agree	Show rationale LLM EIP-7666 has one narrow dependency on EIP-3855 for execution of the embedded PUSH0 instructions. The interaction is limited and most replacement behavior can be tested independently, so coordinated testing is non-critical. Human Limited, independently testable interactions: EIP-2929 (warm-set membership at the retired address) and EIP-8200 (the shared retire-and-install mechanism, whose deployment semantics should be specified identically).

Compare EIP-7666 with other assessments All Hegotá assessments

Criterion legend and glossary

Every stacked bar, comparison matrix, and criterion table on this site uses the same criterion colours, abbreviations, and order. Colour marks the criterion group; the abbreviation and name identify the criterion. Scores are 0–3 per criterion (4 is exceptional; cross-EIP interactions is uncapped).

EVM surface

Opcodes, precompiles, and system contracts that are added or modified.

OP+
Added opcodes
Introduces new opcodes
Score anchors
0
No new opcodes are introduced.
1
A new simple opcode is introduced (no data portion, no complex stack mechanics, and a constant gas cost).
2
Multiple new simple opcodes are introduced, or a single new complex opcode is introduced (has data portion, or complex stack mechanics, or a dynamic gas cost).
3
Multiple new opcodes are introduced, and at least one of them is complex (has data portion, or complex stack mechanics, or a dynamic gas cost).
- Cryptography opcodes are not considered complex by default. Refer to the "Cryptography" section for a separate assessment.
Modified opcodes
Modifies pre-existing opcodes
Score anchors
0
No pre-existing opcode modifications are introduced.
3
At least one pre-existing opcode's behavior is modified (not including gas changes) or a pre-existing opcode is deprecated.
PC+
Added precompiles
Introduces new precompiles
Score anchors
0
No new precompiles are introduced.
1
A new simple precompile is introduced (constant input length, constant gas cost).
2
Multiple new simple precompiles are introduced, or a single new complex precompile is introduced (dynamic input length or dynamic gas cost).
3
Multiple new precompiles are introduced, and at least one of them is complex (dynamic input length or dynamic gas cost).
- Cryptography precompiles are not considered complex by default. Refer to the "Cryptography" for a separate assessment.
Modified precompiles
Modifies pre-existing precompiles logic or gas-accounting
Score anchors
0
No pre-existing precompiles are modified.
1
At least one pre-existing precompile has its gas schedule modified.
2
Multiple pre-existing precompiles have their gas schedule modified, or a single pre-existing precompile has its behavior modified.
3
The behavior of multiple pre-existing precompiles, or a single complex pre-existing precompile modified.
Added system contracts
Introduces new system contract, stateful or not
Score anchors
0
No new system contracts are introduced.
1
A new system contract is introduced that is not stateful nor does it trigger a new system action (e.g. requests to the consensus layer).
2
Multiple new system contracts are introduced or a single new system contract that is either stateful or triggers a new system action (e.g. requests to the consensus layer).
3
Multiple new system contracts are introduced and at least one of them is either stateful or triggers a new system action (e.g. requests to the consensus layer).
Modified system contracts
Modifies pre-existing system contracts
Score anchors
0
No modifications to pre-existing system contracts are introduced, directly or indirectly.
1
Does not directly modify any system contract, but its behavior has minor indirect effects on one or more system contracts.
2
Does not directly modify any system contract, but its behavior has major indirect effects on one or more system contracts.
3
At least one pre-existing system contract code or state is modified, which would involve irregular state transition or a similarly complex transition methodology.

Gas and accounting

Execution, blob, and state gas rules, refunds, and where charges happen inside opcodes.

EVM Gas rule changes
New EVM gas accounting rules
Score anchors
0
No gas accounting changes.
1
Existing gas accounting mechanism is updated.
2
A new gas accounting mechanism is introduced but it does not affect existing mechanisms nor does it affect existing tests.
3
A new gas accounting mechanism is introduced and affects existing mechanisms which in turn affect existing tests.
ORD
State-access ordering within opcode execution · Checklist revision 2 only
Changes *where inside an opcode's execution* state is accessed, or where gas is charged relative to that access. Because a state access is recorded in the block-level access list only if execution had enough gas to reach it, this ordering is consensus-critical: moving it changes the BAL at every gas boundary of every affected opcode.
Score anchors
0
No change to where state is accessed, or to where gas is charged relative to a state access, within any opcode.
1
A single opcode's state-access or gas-charge ordering changes.
2
Multiple opcodes' ordering changes, or a new state-accessing operation is introduced whose position in the order must be settled.
3
The ordering rule changes for a whole class of state-accessing opcodes at once, or what counts as a recordable state access is redefined — requiring existing BAL vectors to be re-derived across opcodes and forks.
- Distinct from "Modified opcodes", which asks whether an opcode's **result** changed. This row asks about the **path to the result**, which is observable even when the result is identical. An EIP can be 0 on that row and 3 on this one.
- Score changes **to** the ordering. Do not score the fact that state accesses are observable — they always are.
- Each boundary must be re-tested against every other dimension that can change the answer (cold/warm, static/non-static, delegated/direct, revert/success), so the case count grows multiplicatively rather than additively. Note this explicitly under Special Considerations.
Blob gas accounting changes
New Blob gas accounting rules which potentially affect pre-existing tests
Score anchors
0
No blob gas accounting changes.
1
Existing blob gas accounting mechanism is updated.
2
A new blob gas accounting mechanism is introduced but it does not affect existing mechanisms nor does it affect existing tests.
3
A new blob gas accounting mechanism is introduced and affects existing mechanisms which in turn affect existing tests.
SGAS
State gas accounting changes · Checklist revision 2 only
New state gas accounting rules. State gas is the cost of *writing* state, as opposed to accessing or executing it: `StateGasCosts`, `COST_PER_STATE_BYTE`, the block-level state gas budget, and the spill path into execution gas.
Score anchors
0
No state gas accounting changes.
1
An existing state gas cost or `STATE_BYTES_PER_*` rate is adjusted.
2
A new state-gas-charging site is introduced, or the block-level state gas budget or reservoir allocation is modified.
3
A new state gas charging mechanism is introduced, or the spill interaction between state gas and execution gas is modified, affecting existing gas tests.
- Harder to test than blob gas: the spill path means state gas cannot be metered independently of execution gas, and some costs (e.g. `NEW_ACCOUNT`) are state-dependent.
New EVM gas refund
New gas-refund mechanism
Score anchors
0
No new gas-refund mechanisms are introduced.
1
A new simple gas-refund mechanism is introduced that does not affect either existing tests or existing gas-refund mechanisms.
2
A new complex gas-refund mechanism is introduced or a simple mechanism that affects existing tests or existing gas-refund mechanisms.
3
A new complex gas-refund mechanism is introduced that affects existing tests or existing gas-refund mechanisms.

Blocks, transactions, and encoding

Transaction types and validity, block and header fields, encodings, syncing, and activation-time changes.

New transaction types
Introduces a new transaction type
Score anchors
0
No new transaction types are introduced.
3
A new transaction type is introduced.
New or modified transaction validity mechanisms
Creates new or modifies pre-existing transaction types' validation mechanisms
Score anchors
0
No changes are introduced to the validity rules of existing transaction types or to their intrinsic gas cost calculation.
1
Minor adjustments are introduced to validity rules or intrinsic gas cost calculation, but they do not significantly affect existing tests.
2
Changes to validity rules or intrinsic gas cost calculation affect existing tests, but require only limited updates to test cases and no redesign of the testing infrastructure.
3
Changes to validity rules or intrinsic gas cost calculation require extensive rework or redesign of the tests or testing infrastructure.
New block / header fields
Introduces new block or block header fields
Score anchors
0
No new block or header fields are introduced.
3
A new block or header field is introduced.
ENC
Encoding changes (RLP/SSZ)
Introduces encoding changes at the transaction/block/interfaces level
Score anchors
0
No encoding changes are introduced at the transaction, block, or interfaces levels.
3
An encoding change is introduced at transaction, block or interfaces level (e.g. RLP -> SSZ).
- "Interfaces level" includes the Engine API. Score an Engine API encoding change (e.g. JSON -> SSZ) here.
Block syncing changes
Modifies block RLP validation mechanisms that require test client syncing.
Score anchors
0
No new RLP validation mechanism is introduced.
1
A single simple RLP validation mechanism is introduced.
2
Multiple simple RLP validation mechanisms are introduced or a single complex one.
3
Multiple RLP validation mechanisms are introduced and at least one of them is deemed complex.
ACT
New fork activation mechanism
Modifies state, internal variables, or similar, at the fork activation block
Score anchors
0
No state modifications, internal variables or similar are modified at the fork activation block.
3
Either a state modification or internal variables are modified at the fork activation block.
- Initialization of new internal variable is not considered a modification.

Client interfaces

Engine API and transition-tool interface changes.

Engine API changes
Introduces new fields to the Engine API directives
Score anchors
0
No new fields or communication mechanisms are introduced to the Engine API.
1
A single new field is introduced in one of the Engine API endpoints.
2
Multiple fields are introduced to one or multiple Engine API end points, or a new Engine API end-point is introduced.
3
Multiple fields are introduced to one or multiple Engine API end points and a new Engine API end-point is introduced.
Engine API encoding changes · Checklist revision 1 only
Engine API encoding changes (the revision-1 template defines no anchor text for this row).
T8N
Transition-tool interface changes
Modifies or adds new fields to the transition tool interface.
Score anchors
0
No modifications to the transition tool interface are required.
1
A single new field needs to be introduced to the transition tool interface.
2
Multiple new fields or a new mechanism has to be introduced to the transition tool interface.
3
Multiple new fields and a new mechanism has to be introduced to the transition tool interface.
- Special consideration must be paid to this section if the EIP introduces a mechanism that requires the state transition tool to be aware whether the block it is processing is the fork-activation block.

Testing impact

Rework, new invariants, and new primitives required in the test framework.

Patterns affecting pre-existing tests
Implements a new validation mechanism or rule that translates in reworking pre-existing tests
Score anchors
0
No pre-existing tests are affected by this change.
1
Minor subset of existing tests are affected by this change.
2
Considerable subset of existing tests are affected by this change but involves only a contrived category of tests.
3
Major subset of existing tests are affected, including diverse category of tests (benchmarks, static, multiple forks, etc.).
INV
New invariant on pre-existing tests · Checklist revision 2 only
Tests that are **not about this EIP** must nonetheless assert something this EIP produces. Their logic does not change; they gain a new thing to check.
Score anchors
0
Pre-existing tests assert nothing new.
1
A narrow, contrived category of pre-existing tests gains a new assertion.
2
A broad category gains a new assertion, applied mechanically.
3
Every test in the fork gains the assertion regardless of what it tests, and pre-fork vectors must be re-derived to satisfy it.
- Paired with the row above, and easy to confuse with it. "Patterns affecting pre-existing tests" asks whether existing tests must be **reworked**; this row asks whether they must **additionally assert something new**. Score both — an EIP can be low on one and high on the other.
New test-framework primitives · Checklist revision 2 only
Requires new abstractions in the test framework itself — expectation types, modifiers, helpers — beyond writing test functions with what already exists.
Score anchors
0
Existing test primitives suffice.
1
Existing primitives need minor extension.
2
New expectation or modifier primitives are required, reusable within this EIP's own test suite.
3
New framework-level primitives are required that become a permanent part of the framework and are used by other EIPs' tests.

Risk and validation

Security, performance, boundary conditions, and cryptography that need validation.

Security risks
Introduces or modifies mechanisms that could compromise the security of the chain, users, validators, or other stakeholders, if not implemented properly.
Score anchors
0
No new mechanisms are introduced that could pose a security risk.
1
The introduced mechanisms are self-contained, can be validated in isolation, and do not alter existing invariants that could pose a security risk for any stakeholders.
2
The introduced mechanisms interact with a limited number of existing components, slightly altering their security assumptions and requiring a targeted security review or fuzzing.
3
The introduced mechanisms interact with multiple existing components, including critical ones, substantially altering their security assumptions and requiring an extensive security review and fuzzing.
Performance risks
Introduces or modifies mechanisms and requires performance validation.
Score anchors
0
No new mechanisms are introduced that require performance validation.
1
The introduced mechanisms can be benchmarked in isolation and do not affect existing performance behavior.
2
The introduced mechanisms cannot be fully benchmarked in isolation, but they only have a limited impact on the existing performance benchmarks.
3
The introduced mechanisms cannot be benchmarked in isolation and have a substantial impact on existing performance benchmarks or have complex interactions with existing mechanisms.
Edge/boundary conditions
Feature contains edge/boundary conditions.
Score anchors
0
No discernible edge cases or boundary conditions are introduced.
1
A single edge-case or boundary-condition prone mechanism is introduced.
2
Multiple edge-case or boundary-condition prone mechanisms are introduced, but none of them requires an elevated number of cases to test.
3
Multiple edge-case or boundary-condition prone mechanisms are introduced and at least one of them requires an elevated number of cases to test.
Cryptography
Introduces new cryptography mechanisms or modifies existing functionality that involves cryptography
Score anchors
0
No cryptography mechanisms are introduced.
1
A new cryptography mechanism is introduced but it is a well known mechanism that is known to have vast resources to aid on its testing.
2
Multiple new cryptography mechanisms are introduced that are well-known or a single but novel mechanism is introduced that is either untested or has limited resources.
3
Multiple new cryptography mechanisms are introduced and at least one of them is a novel mechanism.

Coordination

Cross-EIP interactions and behavior that clients must agree on before tests exist.

XEIP
Cross-EIP interactions
Introduces or modifies mechanisms that affect other EIPs in either the same or past forks.
Score anchors
0
Fully self-contained EIP that does not depend on, modify, or conflict with any other EIP.
1
The EIP interacts with one or more other EIPs in a non-critical and limited way but can be tested independently for the most part.
2
The EIP depends on or modifies one or more other EIPs such that coordinated testing and consideration is required, but interactions are limited in scope and not complex.
3
The EIP has strong interdependencies with multiple EIPs, requiring extensive coordinated cross-EIP testing as well as potential re-design of existing test vectors.
- +1 for every 3 additional interacting EIPs beyond the first 3, each of which requires its own coordinated test cases. List the EIPs in the rationale.
- This row is intentionally uncapped, unlike every other anchor: each interacting EIP is another axis of the test matrix, so a ceiling would make a 12-EIP product indistinguishable from a 3-EIP one.
UNSP
Unspecified behavior requiring cross-client consensus · Checklist revision 2 only
The EIP text does not determine the answer for cases a test can construct. Clients must agree on a previously unspecified detail before tests can be baselined. The cost here is coordination and re-baselining, not test writing.
Score anchors
0
The EIP text determines the answer for every case a test could construct.
1
A few details are unspecified but have an obvious intended reading.
2
Details require client agreement before tests can be written, but they are localized.
3
A previously unspecified *and previously unobservable* behavior becomes consensus-critical; expect tests to be re-baselined on each round of EIP amendment.
- Score this from the EIP's state at assessment time: whether it has client implementations, whether it has been through a devnet, and how many open questions remain on its discussion thread.