EIP complexity assessment

EIP-3651: Warm COINBASE

Assessed in Shanghai / Shapella. The score describes the EIP text available at the assessment cutoff, not the EIP as it stands today.

RetrospectiveShanghai / ShapellaAssessment cutoff 2022-03-04Included by cutoffLayers: execution

LLM Completescore 6

Human Not available· Human complexity assessments were not produced for this fork; only the LLM assessment exists.

LLM assessment

Evaluated on: 2026-10-08 · Spec revision: 2022-01-30 · a6dfa1ed7b

Scope at the cutoff. EIP-3651 (revision a6dfa1ed, Stagnant) makes one change. At the start of transaction execution, the `accessed_addresses` set from EIP-2929 also includes the address returned by `COINBASE` (0x41). Under Paris, this means access to the block's fee recipient is charged the warm cost (100) instead of the cold cost (2600) the first time it is accessed. This applies to BALANCE, EXTCODESIZE, EXTCODECOPY, EXTCODEHASH and the CALL family, and SELFDESTRUCT to the coinbase no longer pays the extra cold charge. The EIP introduces no new opcode, transaction type, header field, encoding or system contract. It states that there are no backward-compatibility or security issues.

6LowLow

Evaluator: LLMChecklist v3
Confidence: High
Under-specified at assessment cutoff: No
Plausible range: 6–6 (Low)
Assessment cutoff: 2022-03-04 · EIP revision a6dfa1ed7b (2022-01-30)

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: 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 EIP does not mention EIP-2930 access lists that explicitly include the coinbase. Whether intrinsic access-list gas is still charged depends on EIP-2930, which was not supplied.
"At the start of transaction execution" is assumed to cover contract-creation transactions as well, by analogy with EIP-2929's initialization.

Criterion breakdown

EIP-3651 Shanghai / Shapella: LLM criterion scores and rationale
Criterion	Score	Why this score	Evidence / uncertainty
Patterns affecting pre-existing tests	2	Expected gas changes only in cases where the accessed address equals the coinbase. Those localized cases span several opcode families (BALANCE, EXT*, CALL family, SELFDESTRUCT), and no common rewrite across families is needed. This is level 2.	eip.md · Abstract — "The COINBASE address shall be warm at the start of transaction execution" Any baseline test whose first access to the coinbase was cold now expects the warm cost. supporting/eip-2929.md · Storage read changes; SELFDESTRUCT changes The cold/warm rule covers BALANCE, the EXT* opcodes, the CALL family and the SELFDESTRUCT recipient. These are several families whose coinbase-target cases change their expected gas. Confidence: Medium Uncertainty: How many baseline vectors target the coinbase is not established by the supplied evidence. If such cases were confined to one family, the score would be 1.
Cross-EIP interactions	2	Coordinated cases with EIP-2929 are needed. Each EIP-2929-priced opcode targeting the coinbase must be charged warm (BALANCE, EXT*, CALL family, SELFDESTRUCT beneficiary). The coinbase must stay warm after a sub-call revert, and overlaps with tx.sender, tx.to and precompiles must be covered. No coupling across multiple EIPs is shown, so this is level 2.	eip.md · Motivation — "the address is initially cold under the access list framework introduced in EIP-2929" The target directly modifies EIP-2929's warm-set initialization. supporting/eip-2929.md · Storage read changes; SELFDESTRUCT changes Every EIP-2929-priced access path must be checked against a warm coinbase. Confidence: Medium Uncertainty: Possible interaction with EIP-2930 access lists that include the coinbase is not stated in the supplied documents. Interacting EIPs: EIP-2929
EVM Gas rule changes	1	An existing accounting rule (initialization of the warm set) changes, and the existing cold/warm mechanism is reused. This is level 1.	eip.md · Specification — "accessed_addresses shall be initialized to also include the address returned by COINBASE" Changes the initial contents of EIP-2929's warm-address set. No new accounting mechanism is added. supporting/eip-2929.md · Specification — "accessed_addresses is initialized to include" Defines the existing initialization and the cold/warm charges that the target extends. Confidence: High
Edge/boundary conditions	1	There is a single boundary-sensitive mechanism (initial warmth of the coinbase), so this is level 1.	eip.md · Specification One changed rule: the coinbase starts warm. Its edges include the coinbase coinciding with tx.sender, tx.to, a created address or a precompile, and exact-gas boundaries at 100 vs 2600. supporting/eip-2929.md · Specification — "if a scope reverts, the access lists should be in the state they were in before" Because the coinbase is in the initial set, it remains warm after a revert. This is an edge case to verify. Confidence: Medium

Show 24 zero-score criteria

Zero-score criteria (Checklist revision 3)
Criterion	Why this score	Evidence / uncertainty
Added opcodes	No new opcode.	eip.md · Specification — "COINBASE (0x41)" References the existing COINBASE opcode. No new instruction is added.
Modified opcodes	The change is gas-only, which the template excludes from ~OP.	eip.md · Specification COINBASE semantics are unchanged. Other opcodes see only gas-cost differences.
Added precompiles	None added.	eip.md · Specification No precompile is added.
Modified precompiles	None modified.	eip.md · Specification No precompile is changed.
Added system contracts	None introduced.	eip.md · Specification No system contract is introduced.
Modified system contracts	None modified.	eip.md · Specification No system contract is involved.
State-access ordering within opcode execution	No instruction's access or charge order changes, and the Paris baseline has no block-level access list. This is level 0.	eip.md · Specification Only the initial warm set changes. When an opcode accesses state or charges gas is unchanged. supporting/eip-2929.md · Storage read changes — "the gas cost is charged and the map is updated at the time that the opcode is being called" The charging order is defined by EIP-2929 and the target leaves it as is.
Blob gas accounting changes	Blob gas accounting is not affected.	eip.md · Specification There is no blob-related content.
State gas accounting changes	Cold/warm access charges belong under GAS, not state gas, so this is 0.	eip.md · Specification Only access warmth changes. State-write costs are not changed.
New EVM gas refund	There is no new refund mechanism.	eip.md · Specification No refund rule is introduced.
New transaction types	None introduced.	eip.md · Specification No transaction type is introduced.
New or modified transaction validity mechanisms	No change to validity or intrinsic gas.	eip.md · Specification — "At the start of transaction execution" Affects execution only. Intrinsic gas and validity rules are not changed.
New block / header fields	None added.	eip.md · Specification No header field is added.
Encoding changes (RLP/SSZ)	No encoding change.	eip.md · Specification No serialized schema change.
Block syncing changes	This is an execution-rule change only.	eip.md · Specification No block decoding or structural validation change.
New fork activation mechanism	No activation-specific state transition.	eip.md · Specification Only a rule selection at the fork. No state migration.
Engine API changes	No Engine API change.	eip.md · Specification No Engine API content.
Transition-tool interface changes	The coinbase is already part of the block environment, so the interface does not change.	eip.md · Specification Uses the existing coinbase value. No new input or output is required.
New invariant on pre-existing tests	No additional assertion is needed in baseline tests.	eip.md · Specification No new output, field or log is introduced.
New test-framework primitives	No new abstraction is needed beyond the gas-measurement primitives used for EIP-2929.	eip.md · Specification Testable with ordinary bytecode that accesses the coinbase and measures gas.
Security risks	Lowering one account's access price from cold to warm adds or changes no security boundary.	eip.md · Security Considerations — "There are no known security considerations" The author identifies no security risk.
Performance risks	Only one already-touched account per block gets cheaper. No changed resource bound needs performance validation.	eip.md · Rationale — "The COINBASE address should also be always be loaded" The coinbase is already loaded for fee and reward payment, so pricing it as warm matches its actual cost. Uncertainty: The claim that the coinbase is always cached is asserted by the EIP, not benchmarked. A component check could justify a score of 1.
Cryptography	No cryptographic change.	eip.md · Specification No cryptographic content.
Unspecified behavior requiring cross-client consensus	The supplied rules determine every outcome I could construct. Interaction with EIP-2930 access lists depends on a document that was not supplied, which is an evidence gap rather than an omission in the specification.	eip.md · Specification The coinbase is added to the initial set that EIP-2929 defines. Revert and duplicate-membership behavior follow from EIP-2929's set semantics. supporting/eip-2929.md · Specification — "accessed_addresses is initialized to include" Defines the initial-set semantics that make the outcomes determinable. Uncertainty: EIP-2930's text is not supplied, so its intrinsic-gas treatment when the coinbase is listed is not verified here.

Assessment provenance

Assessed EIP revision: ethereum/EIPs@a6dfa1ed7b EIPS/eip-3651.md committed 2022-01-30 · information cutoff 2022-03-04
Current master · File history · blob 9b18c45611 · sha256 1795497b5d0c
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/retrospective/outputs/assessments/shanghai/eip-3651.yaml · sha256 8ed4f280246f
Supporting documents supplied with the EIP: supporting/eip-2929.md

Compare EIP-3651 with other assessments All Shanghai / Shapella 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.