fix(ante): enforce EIP-3607 after Prague, exempting only EIP-7702 delegation designations

[randy-cro]

Issue

Our current ante handler blocks accounts who holds contract code from executing an evm transaction.

// ante/eth.go
acct := statedb.NewAccountFromSdkAccount(accountGetter(from))
if !rules.IsPrague {                          // line 93
    if acct.IsContract() {
        fromAddr := common.BytesToAddress(from)
        return errorsmod.Wrapf(errortypes.ErrInvalidType,
            "the sender is not EOA: address %s, codeHash <%s>", fromAddr, acct.CodeHash)
    }
}

However, IsPrague = true by default. Therefore this code block doesn't run.

Solution

To allow eip7702 delegated accounts to execute evm transaction

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.08%. Comparing base (db757f3) to head (878fb19).
⚠️ Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
ante/eth.go	0.00%	3 Missing ⚠️
evmd/ante/handler_options.go	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1111      +/-   ##
===========================================
- Coverage    47.09%   47.08%   -0.01%     
===========================================
  Files          200      200              
  Lines        17647    17648       +1     
===========================================
  Hits          8310     8310              
- Misses        8475     8476       +1     
  Partials       862      862              

Files with missing lines	Coverage Δ
evmd/ante/handler_options.go	62.88% <0.00%> (ø)
ante/eth.go	0.00% <0.00%> (ø)

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[JayT106]

@claude review

[github-actions]

Claude finished @JayT106's task in 1m 54s —— View job

---

Code Review

Tasks

• Gather context from PR description and changed files
• Review ante/eth.go changes
• Review evmd/ante/eth_test.go changes
• Review evmd/ante/handler_options.go changes
• Review CHANGELOG.md changes
• Post final review

---

Summary

This PR fixes a real bug: the IsPrague guard was accidentally suppressing EIP-3607 enforcement for all post-Prague chains (the default), allowing any contract-code account to send transactions. The fix correctly re-enforces EIP-3607 while carving out an exemption for EIP-7702 delegation designators.

---

Findings

✅ Correctness — logic is right

The old code:

if !rules.IsPrague {   // always false → block never ran
    if acct.IsContract() { ... }
}

The new code runs unconditionally and passes the check only for EIP-7702 delegated accounts. This is exactly the correct EIP-3607 behaviour for post-Prague chains.

⚠️ Pre-Prague behaviour change

The old code silently skipped the check on Prague-enabled chains, and also skipped it on pre-Prague chains where IsPrague=false would have been wrong too. The new code applies uniformly to all forks. On a pre-Prague chain EIP-7702 delegation codes cannot exist, so ParseDelegation always returns false, and every contract sender is rejected — identical to the intended pre-Prague behaviour. This is fine, but worth stating explicitly since the signature change (removing rules) makes the fork-awareness implicit.

⚠️ API breaking change — rules parameter removed

VerifyEthAccount is a public function. Removing rules params.Rules from its signature is a breaking change for any downstream consumer that calls it directly. The CHANGELOG entry should mention this if this library is consumed externally.

⚠️ Extra GetCode read on every transaction from a delegated account

ante/eth.go:94:

code := evmKeeper.GetCode(ctx, common.BytesToHash(acct.CodeHash))

This is an additional DB read for every ante-handler execution where the sender has a non-empty code hash (i.e., all EIP-7702 delegated accounts). It's unavoidable with the current architecture, but the hot path for regular EOA senders (acct.IsContract() == false) is not affected. Worth noting in a comment.

⚠️ Test coverage — Codecov reports 0% for new lines in ante/eth.go

Codecov's report is 2 commits behind head on develop, so the numbers may be stale. Looking at the test code directly, both new cases are exercised: the delegated-account case calls vmdb.SetCode(addr, ethtypes.AddressToDelegation(...), 0) and the contract-code case uses raw bytecode {0x60, 0x00, 0x60, 0x00, 0xfd}. The test flow (malleate → Commit → VerifyEthAccount) should reach the new code. Coverage should be re-confirmed once the report catches up.

✅ ParseDelegation import is consistent

set_code_authorizations.go uses types.ParseDelegation from "github.com/ethereum/go-ethereum/core/types". The new code aliases the same package as ethtypes — identical function, consistent package. No issue.

✅ common.BytesToHash(acct.CodeHash) is consistent

This is the same pattern used in x/evm/statedb/state_object.go:157. Correct.

✅ No consensus/state-breaking changes

This is an ante-handler change (transaction validation). It affects which transactions are accepted, not how state is written. Validators running the new code will reject non-EIP-7702 contract senders that the old code (incorrectly) allowed. This is a consensus-level tightening of rules, but it is the correct behaviour according to EIP-3607 — the old behaviour was the bug. No migration needed.

---

Minor suggestions

ante/eth.go:93-99 — consider adding a one-line comment explaining why GetCode is needed (i.e., EIP-7702 exemption), to make the intent obvious to future readers.

// EIP-3607: reject contract senders, but allow EIP-7702 delegation designators.
if acct.IsContract() {
    code := evmKeeper.GetCode(ctx, common.BytesToHash(acct.CodeHash))
    if _, delegated := ethtypes.ParseDelegation(code); !delegated {

---

Verdict

The fix is correct and necessary. The two test cases cover the key scenarios. The 0% coverage report is likely stale. Before merging:

1. Confirm coverage catches up once the CI run on head is reflected.
2. Consider whether downstream callers of VerifyEthAccount exist outside this repo and need a deprecation note.