Add note in MultiSignerERC7913 about adding invalid signers

[ernestognw]

Fixes #????

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Walkthrough

A documentation update was made to the _addSigners function in the MultiSignerERC7913 contract. A warning note was added to the function's docstring indicating that signers are not validated or guaranteed to be valid or controlled. The note informs integrators that they must perform their own validation to prevent security or functionality issues. This change affects only documentation; no modifications were made to the function's executable logic, control flow, or public entity declarations.

Pre-merge checks and finishing touches

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Description check	❓ Inconclusive	The PR description is minimally populated with only the contribution template and checklist, containing no substantive details about the changes or their purpose.	Provide a detailed description explaining why the warning note was added, what security/functionality issues it addresses, and any relevant context for reviewers.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding a warning note about invalid signers in the MultiSignerERC7913 contract's documentation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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🧹 Nitpick comments (1)

contracts/utils/cryptography/signers/MultiSignerERC7913.sol (1)

117-121: Excellent security documentation addition!

This NOTE provides important guidance to integrators about validation responsibilities. The warning about dead addresses, uncontrolled contracts, and self-referential addresses is particularly valuable for preventing common multisig security issues.

One optional refinement: Since ERC-7913 signers are encoded as bytes (verifier || key per line 192), you might consider clarifying that the examples refer to the verifier portion of the encoded signer. For instance, "dead verifier addresses (e.g., a signer containing address(0) as the verifier)" would be more technically precise, though the current phrasing is clear enough in context.

Optional: More precise terminology

- * NOTE: This function does not validate that signers are controlled or represent valid entities. Integrators
- * must ensure signers are properly validated before adding them. Invalid or uncontrolled addresses can compromise
- * the multisig's security or functionality. Examples include dead addresses (e.g., `address(0)`), uncontrolled
- * contracts, or the contract's own address (which may cause recursive validation loops).
+ * NOTE: This function does not validate that signers are controlled or represent valid entities. Integrators
+ * must ensure signers are properly validated before adding them. Invalid or uncontrolled signers can compromise
+ * the multisig's security or functionality. Examples include signers with dead verifier addresses (e.g., containing
+ * `address(0)` as the verifier), uncontrolled contract verifiers, or the contract's own address as verifier
+ * (which may cause recursive validation loops).

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• contracts/utils/cryptography/signers/MultiSignerERC7913.sol

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🧠 Learnings (1)

📓 Common learnings

Learnt from: ernestognw
Repo: OpenZeppelin/openzeppelin-contracts PR: 5904
File: contracts/crosschain/README.adoc:1-1
Timestamp: 2025-08-28T15:48:30.716Z
Learning: ernestognw prefers "Cross chain" without hyphenation rather than "Cross-chain" in documentation titles.

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