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 2026-10-07EIP-8081: DFILayers: execution

LLM Completescore 18

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

LLM · Checklist revision 32026-10-08 · Opus 5.5 · snapshot · 18 Human · Checklist revision 2Draft PR · 12 CompareHuman vs LLM · shared criteria

Evaluated on: 2026-10-08 · Spec revision: 2026-10-07 · 6dac5e7491 · EIP-8081 list: DFI

Scope at the cutoff. EIP-7666 removes the identity precompile at 0x04. At the start of the fork block, the protocol sets that address's code to the 7-byte EVM program 0x365f5f37365ff3 (CALLDATASIZE PUSH0 PUSH0 CALLDATACOPY CALLDATASIZE PUSH0 RETURN). From that block on, 0x04 is no longer treated as a precompile. Return values are meant to stay the same, but the EIP says gas costs differ slightly. The program needs PUSH0 (EIP-3855), and the EIP cites MCOPY (EIP-5656) only as the reason the precompile is no longer needed.

18MediumMedium

Evaluator: LLMChecklist v3
Confidence: Medium
Under-specified at assessment cutoff: Yes — 5 criteria affected
Plausible range: 15–20 (Medium)
Snapshot: 2026-10-07 · EIP revision 6dac5e7491 (2026-10-07)

Score bands · Checklist revision 3

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: Yes

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

Why: The specification only says to set code at 0x04 and stop treating it as a precompile. It does not state the account's nonce or other fields after installation, whether 0x04 is still pre-warmed, whether the activation write enters the block-level access list, or exact gas expectations.

Plausible total

15–20
recorded score 18 · plausible tiers Medium

Affected criteria (5)

Modified precompiles (3)
EVM Gas rule changes (1)
State-access ordering within opcode execution (0)
Cross-EIP interactions (2)
Unspecified behavior requiring cross-client consensus (1)

Unresolved questions at the cutoff (4)

Is 0x04 removed from the set of addresses pre-warmed at transaction start?
What are the nonce and other account fields of 0x04 after installation? Must the account be created if it is absent?
Must the activation-time code write be recorded in the block-level access list?
Is the code installed before or after other start-of-block system operations, and does that ordering matter?

Notable ambiguities noted by the assessor (4)

'Should no longer be treated as a precompile' leaves 0x04's warm/cold status implicit.
Block-level access-list treatment of the activation code installation is not specified.
The EIP claims equivalent functionality but gives no exact gas formula. The new cost comes from CALLDATACOPY, memory expansion and base opcode costs in the callee.
The discussions-to URL refers to EIP-7561. This looks like a stale reference, not a behavioral dependency.

Criterion breakdown

EIP-7666 Hegotá: LLM criterion scores and rationale
Criterion	Score	Why this score	Evidence / uncertainty
Modified precompilesUnder-specified	3	Identity is complex: it takes variable-length input and has dynamic gas. Removing it as a native precompile changes its availability as a precompile and its failure rules, not just its gas. That meets level 3.	eip.md · Abstract — "Remove the identity precompile at 0x04" The identity precompile is removed from the precompile set. eip.md · Backwards Compatibility Outputs are claimed equivalent, but gas and failure (OOG) thresholds change. 0x04 also gains account code. Confidence: Medium Uncertainty: Because the returned output is meant to be identical, one could argue this is gas-only (level 1).
New fork activation mechanism	3	A one-time protocol-mandated code installation at 0x04 is an activation-specific state transition that differs from ordinary post-fork processing.	eip.md · Specification — "At the start of the block in which this fork activates, set the code of IDENTITY_PRECOMPILE_ADDRESS to EVM_CODE" The protocol installs account code once, at activation. Confidence: High
Patterns affecting pre-existing tests	2	Ordinary cases throughout the identity-precompile family need rework (gas, memory-expansion and OOG thresholds). Localized cases also need rework in several other families: EXTCODE* on precompile addresses, warm-precompile access, and tests that use 0x04 as a convenient call target. No single rewrite applies across families, so level 2 applies.	eip.md · Backwards Compatibility — "Gas costs are slightly different" Every baseline identity-precompile test with exact gas expectations needs new expected values. eip.md · Specification — "set the code of IDENTITY_PRECOMPILE_ADDRESS" 0x04 now has code, which changes expected EXTCODESIZE, EXTCODEHASH and EXTCODECOPY results and post-state for that address. It also changes cold/warm results in tests that touch precompile addresses. Confidence: Medium Uncertainty: There is no supplied test suite, so the spread is estimated from the specification.
Edge/boundary conditions	2	Two independent boundary-sensitive rules change: the input-size gas function at 0x04 and the fork-activation boundary. Neither needs an interacting matrix, so level 2 applies.	eip.md · Rationale — EVM_CODE disassembly Gas now depends on CALLDATACOPY per-word cost and quadratic memory expansion in the callee. This creates new size boundaries (empty input, word boundaries, large inputs, OOG thresholds). eip.md · Specification — "At the start of the block in which this fork activates" Behavior must be checked at the activation boundary: the last pre-fork block versus the first fork block, including the first transaction of that block. Confidence: Medium Uncertainty: Cold/warm status of 0x04 could be treated as another dimension that multiplies with input size.
Cross-EIP interactionsUnder-specified	2	Coordinated cases are needed for cold/warm access to 0x04 (with and without access-list entries) together with the new gas costs, and for code delegation targeting 0x04. These are the unnumbered interactions listed under cross_eip. PUSH0 needs only a local compatibility check, so level 2 applies.	eip.md · Specification — "should no longer be treated as a precompile" Rules that treat precompiles specially now apply differently to 0x04: precompile pre-warming and access lists, and the code-delegation special case. These need coordinated cases. supporting/eip-3855.md · Specification PUSH0 is defined. EVM_CODE depends on it. Confidence: Medium Uncertainty: The interacting precompile-related rules are not supplied, so their exact semantics could not be verified. Interacting EIPs: EIP-3855
Added system contracts	1	This is exactly one stateless protocol-designated contract with no system action.	eip.md · Specification — "set the code of IDENTITY_PRECOMPILE_ADDRESS to EVM_CODE" The protocol installs one EVM contract at 0x04. It uses no storage and triggers no system action. rubric.md · ~SC note — "Deploying a newly introduced system contract is not modifying an existing one" Installing code at an existing account is assessed under Added system contracts. Confidence: High
EVM Gas rule changesUnder-specified	1	Existing accounting rules now apply differently to 0x04: interpreter gas replaces precompile gas, and the address's warm/cold status changes. No new accounting mechanism is added, so level 1 applies.	eip.md · Backwards Compatibility — "Gas costs are slightly different" Calls to 0x04 are no longer charged by the precompile gas schedule. They are charged as ordinary EVM execution of EVM_CODE, including memory expansion in the callee frame. eip.md · Specification — "should no longer be treated as a precompile" Removing 0x04 from the precompile set implies it is no longer pre-warmed like other precompiles, so first access in a transaction becomes a cold access. Confidence: Medium Uncertainty: The EIP does not say explicitly whether 0x04 stays in the pre-warmed address set. This assessment assumes it does not, based on 'no longer treated as a precompile'.
New test-framework primitives	1	The existing fork primitives (precompile list, expected fork pre-allocation and post-state) need a local extension. No new abstraction is needed.	eip.md · Specification — "no longer be treated as a precompile" The framework's fork definition must drop 0x04 from the precompile set and model the code installed at 0x04 at activation. Confidence: Medium Uncertainty: Whether existing helpers already support this is unknown and was not assumed.
Security risks	1	The affected conditions (functional equivalence, behavior of 0x04 under DELEGATECALL, CALLCODE, STATICCALL and value transfer, and code-hash observability) can be checked locally.	eip.md · Security Considerations The EIP claims there are no security concerns. eip.md · Specification 0x04 becomes an ordinary code account, which changes its code hash and precompile status. Confidence: Medium Uncertainty: Contracts or delegations that rely on 0x04 having precompile properties could be affected. Those are application or interaction concerns.
Performance risks	1	Component benchmarks of 0x04 calls under the new gas costs, with large inputs, are enough. No end-to-end assumption changes.	eip.md · Backwards Compatibility — "Gas costs are slightly different" Identity calls now run in the interpreter and allocate memory in the callee frame instead of using a native copy. eip.md · Security Considerations — "no new functionality is introduced or made cheaper" The EIP says nothing becomes cheaper. Confidence: Low Uncertainty: No benchmark data is supplied, and level 0 is defensible.
Unspecified behavior requiring cross-client consensusUnder-specified	1	Some details are omitted: nonce after installation, block-level access-list recording, and warm status. The surrounding text mostly supports one reading: set only the code and treat 0x04 as an ordinary account.	eip.md · Specification — "set the code of IDENTITY_PRECOMPILE_ADDRESS to EVM_CODE" Only the code is specified. Nonce, balance handling, and whether the write is recorded in the block-level access list are not stated. eip.md · Specification — "should no longer be treated as a precompile" This implies, without stating it, that 0x04 is removed from pre-warmed addresses and gets non-precompile delegation semantics. Confidence: Medium Uncertainty: Block-level access-list recording of the activation write could have competing interpretations, which would make this level 2.

Show 17 zero-score criteria

Zero-score criteria (Checklist revision 3)
Criterion	Why this score	Evidence / uncertainty
Added opcodes	No new instruction is introduced.	eip.md · Rationale EVM_CODE uses only existing instructions, including PUSH0 from the prerequisite.
Modified opcodes	Instruction semantics are unchanged.	rubric.md · ~OP level 0 — "changed callee or precompile behavior through an unchanged instruction do not count" Calling different code at 0x04 does not change an instruction's semantics. eip.md · Specification No instruction semantics are redefined.
Added precompiles	Not applicable.	eip.md · Abstract A precompile is removed, not added.
Modified system contracts	Not applicable.	eip.md · Specification No existing system contract is touched.
State-access ordering within opcode executionUnder-specified	CALL-family instructions keep their specified ordering. The only change is what runs at 0x04.	eip.md · Specification No instruction's state-access or gas-charge sequence is changed. Only the callee at 0x04 changes. rubric.md · SAO note — "Changed precompile or contract internals do not modify an instruction's ordering" Changing what the callee is does not count as an ordering change. Uncertainty: The supplied text does not say whether calls to 0x04 or the activation-time code write must now appear in the block-level access list. If they must, recordable-access expectations for 0x04 change.
Blob gas accounting changes	Blob gas accounting is unchanged.	eip.md · Specification There is no blob-related content.
State gas accounting changes	No state-gas charging rule is added or changed.	eip.md · Specification — "set the code of IDENTITY_PRECOMPILE_ADDRESS to EVM_CODE" The code is installed by the protocol and no state-gas charge is specified.
New EVM gas refund	There is no new refund mechanism.	eip.md · Specification No refund is introduced.
New transaction types	Not applicable.	eip.md · Specification No new transaction type.
New or modified transaction validity mechanisms	Not applicable.	eip.md · Specification No transaction-validity or intrinsic-gas change.
New block / header fields	Not applicable.	eip.md · Specification No header field is added.
Encoding changes (RLP/SSZ)	Not applicable.	eip.md · Specification No schema or codec changes.
Block syncing changes	Only execution rules change.	eip.md · Specification No block decoding or structural validation change.
Engine API changes	Not applicable.	eip.md · Specification No Engine API change.
Transition-tool interface changes	Fork-aware behavior is handled internally and needs no interface change.	eip.md · Specification The code installation happens inside fork-aware block processing. No new input or output field is needed.
New invariant on pre-existing tests	Changed values at 0x04 are rework, not a new assertion.	eip.md · Specification No new log, header field, receipt field or recurring storage write is introduced.
Cryptography	No cryptographic mechanism changes.	eip.md · Specification The identity function is not cryptographic.

Assessment provenance

Assessed EIP revision: ethereum/EIPs@6dac5e7491 EIPS/eip-7666.md committed 2026-10-07 · information cutoff 2026-10-07T22:23:55Z
Current master · File history · blob 6b0b4a6d13 · sha256 ea392f32efc0
Rubric: Checklist revision 3 · ethspecs/pm@fe2f793b03
Evaluator: Opus 5.5 (claude-opus-5-5) at high effort, one tool-less call per EIP · isolation bubblewrap_claude_p_no_tools_v1
Source record: Frozen research record research/tasks/10-opus-v3-reassessment/prospective/outputs/assessments/hegota-2026-10-08/eip-7666.yaml · sha256 b23dac6ee4f5
Supporting documents supplied with the EIP: 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

The LLM applied checklist revision 3 and the human reviewers revision 2 to EIP-7666 in Hegotá. Revision 3 phrases the same criteria more precisely; differences cover the 28 criteria both revisions share, and each total keeps its own revision. Δ is LLM minus Human.

Using the latest scored LLM evaluation for this checklist: 2026-10-08 · spec 2026-10-07 · 6dac5e7491. The Human and LLM assessments may use different spec revisions.

LLM18Medium

Human12Medium

Δ total+6Same tier

Criteria22/28agree exactly · 6 differ by 1 · 0 differ by 2+

Complexity profiles side by side

LLM

Human

Largest disagreements: EVM Gas rule changes (+1), Patterns affecting pre-existing tests (+1), Edge/boundary conditions (+1), Modified precompiles (+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
Modified precompiles	3	2	+1	Differ by 1	Show rationale LLM Identity is complex: it takes variable-length input and has dynamic gas. Removing it as a native precompile changes its availability as a precompile and its failure rules, not just its gas. That meets level 3. 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.
EVM Gas rule changes	1	0	+1	Differ by 1	Show rationale LLM Existing accounting rules now apply differently to 0x04: interpreter gas replaces precompile gas, and the address's warm/cold status changes. No new accounting mechanism is added, so level 1 applies. 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.
Patterns affecting pre-existing tests	2	1	+1	Differ by 1	Show rationale LLM Ordinary cases throughout the identity-precompile family need rework (gas, memory-expansion and OOG thresholds). Localized cases also need rework in several other families: EXTCODE* on precompile addresses, warm-precompile access, and tests that use 0x04 as a convenient call target. No single rewrite applies across families, so level 2 applies. 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.
Performance risks	1	0	+1	Differ by 1	Show rationale LLM Component benchmarks of 0x04 calls under the new gas costs, with large inputs, are enough. No end-to-end assumption changes. 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 Two independent boundary-sensitive rules change: the input-size gas function at 0x04 and the fork-activation boundary. Neither needs an interacting matrix, so level 2 applies. 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.
Cross-EIP interactions	2	1	+1	Differ by 1	Show rationale LLM Coordinated cases are needed for cold/warm access to 0x04 (with and without access-list entries) together with the new gas costs, and for code delegation targeting 0x04. These are the unnumbered interactions listed under cross_eip. PUSH0 needs only a local compatibility check, so level 2 applies. 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).
Added opcodes	0	0	0	Agree	Show rationale LLM No new instruction is introduced. Human No rationale recorded.
Modified opcodes	0	0	0	Agree	Show rationale LLM Instruction semantics are unchanged. Human No rationale recorded.
Added precompiles	0	0	0	Agree	Show rationale LLM Not applicable. Human No rationale recorded.
Added system contracts	1	1	0	Agree	Show rationale LLM This is exactly one stateless protocol-designated contract with no 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 Not applicable. Human No rationale recorded.
State-access ordering within opcode execution	0	0	0	Agree	Show rationale LLM CALL-family instructions keep their specified ordering. The only change is what runs at 0x04. Human No rationale recorded.
Blob gas accounting changes	0	0	0	Agree	Show rationale LLM Blob gas accounting is unchanged. Human No rationale recorded.
State gas accounting changes	0	0	0	Agree	Show rationale LLM No state-gas charging rule is added or changed. Human No rationale recorded.
New EVM gas refund	0	0	0	Agree	Show rationale LLM There is no new refund mechanism. Human No rationale recorded.
New transaction types	0	0	0	Agree	Show rationale LLM Not applicable. Human No rationale recorded.
New or modified transaction validity mechanisms	0	0	0	Agree	Show rationale LLM Not applicable. Human No rationale recorded.
New block / header fields	0	0	0	Agree	Show rationale LLM Not applicable. Human No rationale recorded.
Encoding changes (RLP/SSZ)	0	0	0	Agree	Show rationale LLM Not applicable. Human No rationale recorded.
Block syncing changes	0	0	0	Agree	Show rationale LLM Only execution rules change. Human No rationale recorded.
New fork activation mechanism	3	3	0	Agree	Show rationale LLM A one-time protocol-mandated code installation at 0x04 is an activation-specific state transition that differs from ordinary post-fork processing. 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 Not applicable. Human No rationale recorded.
Transition-tool interface changes	0	0	0	Agree	Show rationale LLM Fork-aware behavior is handled internally and needs no interface change. Human No rationale recorded.
New invariant on pre-existing tests	0	0	0	Agree	Show rationale LLM Changed values at 0x04 are rework, not a new assertion. Human No rationale recorded.
New test-framework primitives	1	1	0	Agree	Show rationale LLM The existing fork primitives (precompile list, expected fork pre-allocation and post-state) need a local extension. No new abstraction is needed. Human Existing primitives suffice with minor extension: a fork precompile-list subtraction and code pre-allocation at the retired address.
Security risks	1	1	0	Agree	Show rationale LLM The affected conditions (functional equivalence, behavior of 0x04 under DELEGATECALL, CALLCODE, STATICCALL and value transfer, and code-hash observability) can be checked locally. 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 changes. Human The identity function is a memory copy; nothing cryptographic is touched.
Unspecified behavior requiring cross-client consensus	1	1	0	Agree	Show rationale LLM Some details are omitted: nonce after installation, block-level access-list recording, and warm status. The surrounding text mostly supports one reading: set only the code and treat 0x04 as an ordinary account. 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.

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 · not in checklist revision 1
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 · not in checklist revision 1
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 · not in checklist revision 1
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 · not in checklist revision 1
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 · not in checklist revision 1
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.