fix(1271): separate policyData and signature

[highskore]

There's a bug in 1271 where we pass the whole signature to both the policy and validator, meaning that both the validator and the policy would need to know how to destructure the same data, which obviously doesn't work with OwnableValidator etc.

This PR fixes this by extracting policyData from the signature before passing it to the policy and then passes the signature data to the stateless validator.

[Copilot]

Pull Request Overview

Separates concatenated policy data from the validator signature in ERC-1271 flow by introducing an explicit length-delimited policyData segment inside the aggregated signature format. Updates test construction of composite signatures and parsing logic in SmartSession to extract policy data and remaining validator signature.

• Introduces new signature layout: permissionId | policyDataLength | policyData | validatorSignature
• Adjusts isValidSignatureWithSender to parse and dispatch policyData and validator signature separately
• Refactors tests to build signatures following the new structured layout

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
test/unit/base/ERC1271Base.t.sol	Updates test helper to construct new composite signature with embedded policyData length and blob.
contracts/SmartSession.sol	Parses new signature structure: extracts policyData length, slices policyData for ERC1271 policy checks, and separates remaining validator signature.

Comments suppressed due to low confidence (1)

test/unit/base/ERC1271Base.t.sol:1

• [nitpick] Hard-coded length literal (uint256(32)) and an opaque bytes32 constant reduce clarity of the new signature structure; consider introducing named constants or helper builders (e.g., mockPolicyData(), POLICY_DATA_LENGTH) to document intent and avoid duplication across tests.

import "../../Base.t.sol";

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[zeroknots]

👍

[highskore]

added some bounds checks & consts @zeroknots