AccountERC7579: document that isValidSignature has no native validation fallback

[BhariGowda]

AccountERC7579.isValidSignature is documented as falling back to "native" validation by the abstract signer. It does not, and it never has.

draft-AccountERC7579.sol#L185-L191:

/**
 * @dev Implement ERC-1271 through IERC7579Validator modules. If module based validation fails, fallback to
 * "native" validation by the abstract signer.
 * ...

The body (L192-L207) returns bytes4(0xffffffff) on every path that does not reach an installed validator. It calls neither super nor _rawSignatureValidation, and this same contract overrides _rawSignatureValidation at L423-L429 to return false, under the comment "By default, only use the modules for validation of userOp and signature. Disable raw signatures."

So the file states both that native validation is a fallback and that it is disabled. The code agrees with the second.

_validateUserOp (L209-L226) is the function that does have the fallback:

return
    isModuleInstalled(MODULE_TYPE_VALIDATOR, module, Calldata.emptyBytes())
        ? IERC7579Validator(module).validateUserOp(userOp, _signableUserOpHash(userOp, userOpHash))
        : super._validateUserOp(userOp, userOpHash, signature);

super._validateUserOp resolves to Account._validateUserOp, which is exactly _rawSignatureValidation(...) ? SIG_VALIDATION_SUCCESS : SIG_VALIDATION_FAILED. That makes the fallback meaningful for a derived contract that re-overrides _rawSignatureValidation (as AccountMock does), and its NatSpec ("Falls back to {Account-_validateUserOp} otherwise") is accurate.

The asymmetry between the two functions looks deliberate: the _rawSignatureValidation override states the same decision a second way. Only the description of isValidSignature is wrong, and it has been since #5657 introduced the function: that @dev block and the body have both been unchanged since, so this is a stale description rather than a behavior change that the docs missed. This PR rewrites that one @dev block to say how the validator is selected, that the module's return value is forwarded as-is, and which three paths produce 0xffffffff. _validateUserOp and the _rawSignatureValidation override are untouched.

Verification

Comment-only, and checked rather than assumed: compiled master and this branch, stripped the trailing CBOR metadata from deployedBytecode, and the runtime code of $AccountERC7579Mock, $AccountERC7579HookedMock and $AccountMock is byte-identical across the two.

npm run lint:sol clean, npm test green (8417 passing: 361 solidity, 8056 mocha, 0 failing).

Changeset

None. NatSpec only, no user-visible behavior change. Recent documentation-only PRs (#6681, #6648, #6636, #6633, #6623, #6607, #6422) all merged with no changeset and the ignore-changeset label. Happy to add one instead if you prefer.

PR Checklist

• Tests
• Documentation
• Changeset entry (run npx changeset add)

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Latest commit: d66f7a8

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• contracts/account/extensions/draft-AccountERC7579.sol

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Walkthrough

The ERC-1271 documentation now states that signature validation uses only installed validator modules. It states that successful validator results are forwarded. It also documents 0xffffffff for short signatures, uninstalled validators, and reverted validator calls. The previous native abstract-signer validation fallback description was removed.

Merge Risk: ⚪ Minimal · up to d66f7

This PR clarifies existing signature-validation behavior without changing runtime code or user-facing functionality. No actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the documentation change to remove the incorrect native validation fallback.
Description check	✅ Passed	The description directly explains the documentation correction, affected functions, verification results, and lack of behavior changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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• Create stacked PR
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• Create PR with unit tests

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