refactor(contracts): add common clone contract for proxies

Author: 0xjei

packages/contracts/contracts/src/core/checker/AdvancedChecker.sol

@@ -2,12 +2,12 @@
 pragma solidity ^0.8.20;
 
 import {IAdvancedChecker, Check, CheckStatus} from "../interfaces/IAdvancedChecker.sol";
-import {Checker} from "./Checker.sol";
+import {Clone} from "../proxy/Clone.sol";
 
 /// @title AdvancedChecker.
 /// @notice Multi-phase validation checker with pre, main, and post checks.
 /// @dev Base contract for implementing complex validation logic with configurable check phases.
-abstract contract AdvancedChecker is Checker, IAdvancedChecker {
+abstract contract AdvancedChecker is Clone, IAdvancedChecker {
     /// @notice Entry point for validation checks.
     /// @param subject Address to validate.
     /// @param evidence Validation data.

packages/contracts/contracts/src/core/checker/BaseChecker.sol

@@ -2,13 +2,13 @@
 pragma solidity ^0.8.20;
 
 import {IBaseChecker} from "../interfaces/IBaseChecker.sol";
-import {Checker} from "./Checker.sol";
+import {Clone} from "../proxy/Clone.sol";
 
 /// @title BaseChecker
 /// @notice Abstract base contract for implementing validation checks.
 /// @dev Provides a standardized interface for implementing custom validation logic
 /// through the internal _check method.
-abstract contract BaseChecker is Checker, IBaseChecker {
+abstract contract BaseChecker is Clone, IBaseChecker {
     /// @notice Validates evidence for a given subject address.
     /// @dev External view function that delegates to internal _check implementation.
     /// @param subject Address to validate.

packages/contracts/contracts/src/core/checker/Checker.sol

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+interface IClone {
+    error AlreadyInitialized();
+
+    function initialize() external;
+
+    function getAppendedBytes() external returns (bytes memory);
+}

packages/contracts/contracts/src/core/interfaces/IClone.sol

@@ -14,7 +14,6 @@ interface IPolicy {
     error TargetOnly();
     error TargetAlreadySet();
     error AlreadyEnforced();
-    error AlreadyInitialized();
 
     /// @notice Returns policy trait identifier.
     /// @return Policy trait string (e.g., "Semaphore").

packages/contracts/contracts/src/core/interfaces/IPolicy.sol

@@ -29,9 +29,9 @@ abstract contract AdvancedPolicy is IAdvancedPolicy, Policy {
      * @notice Initialize function for minimal proxy clones.
      *         Decodes appended bytes for (AdvancedChecker, skipPre, skipPost, allowMultipleMain).
      */
-    function initialize() public virtual override {
+    function _initialize() internal virtual override {
         // 1. Call Policy’s initialize to set ownership and `_initialized`.
-        super.initialize();
+        super._initialize();
 
         // 2. Decode the appended bytes for the advanced config.
         bytes memory data = _getAppendedBytes();

packages/contracts/contracts/src/core/policy/AdvancedPolicy.sol

@@ -22,9 +22,9 @@ abstract contract BasePolicy is Policy, IBasePolicy {
      * @notice Initializes the contract with a BaseChecker instance, reading from appended bytes.
      *         Replaces the old constructor-based approach.
      */
-    function initialize() public virtual override {
+    function _initialize() internal virtual override {
         // 1. Call the base `Policy.initialize()` to set ownership / handle `_initialized`.
-        super.initialize();
+        super._initialize();
 
         // 2. Decode the appended bytes to get the BaseChecker address (and anything else you might need).
         bytes memory data = _getAppendedBytes();

packages/contracts/contracts/src/core/policy/BasePolicy.sol

@@ -3,33 +3,21 @@ pragma solidity ^0.8.20;
 
 import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
 import {IPolicy} from "../interfaces/IPolicy.sol";
+import {Clone} from "../proxy/Clone.sol";
 import {LibClone} from "solady/src/utils/LibClone.sol";
 
-abstract contract Policy is IPolicy, Ownable(msg.sender) {
-    /// @notice One-time initialization guard.
-    bool private _initialized;
-
+abstract contract Policy is Clone, IPolicy, Ownable(msg.sender) {
     /// @notice The “gatekeeped” contract address set once by the owner (if at all).
     address internal target;
 
-    /**
-     * @notice The base init. By default, transfers ownership to `msg.sender` (i.e., the caller).
-     * @dev If you want the factory to always be the owner, you just have the factory call this function,
-     *      so `msg.sender` is the factory in that transaction.
-     */
-    function initialize() public virtual {
-        if (_initialized) revert AlreadyInitialized();
-        _initialized = true;
+    function _initialize() internal virtual override {
+        super._initialize();
 
         // By default, set the owner to the caller (likely the factory).
         // this is not the zero address as above!
         _transferOwnership(msg.sender);
     }
 
-    function _getAppendedBytes() internal view returns (bytes memory) {
-        return LibClone.argsOnClone(address(this));
-    }
-
     /**
      * @notice Only the owner can call `setTarget` once.
      * @param _target The contract to be protected by this policy.

packages/contracts/contracts/src/core/policy/Policy.sol

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import {IClone} from "../interfaces/IClone.sol";
+import {LibClone} from "solady/src/utils/LibClone.sol";
+
+// @todo refactoring & comments
+abstract contract Clone is IClone {
+    bool private _initialized;
+
+    function initialize() external {
+        _initialize();
+    }
+
+    function getAppendedBytes() external returns (bytes memory) {
+        return _getAppendedBytes();
+    }
+
+    function _initialize() internal virtual {
+        if (_initialized) revert AlreadyInitialized();
+        _initialized = true;
+    }
+
+    function _getAppendedBytes() internal virtual returns (bytes memory) {
+        return LibClone.argsOnClone(address(this));
+    }
+}

packages/contracts/contracts/src/core/proxy/Clone.sol

@@ -25,9 +25,9 @@ contract AdvancedERC721Checker is AdvancedChecker {
     uint256 public minTokenId;
     uint256 public maxTokenId;
 
-    function initialize() public virtual override {
+    function _initialize() internal override {
         // 1. Call super to handle `_initialized` check.
-        super.initialize();
+        super._initialize();
 
         // 2. Retrieve appended bytes from the clone.
         bytes memory data = _getAppendedBytes();

packages/contracts/contracts/src/test/advanced/AdvancedERC721Checker.sol

@@ -2,7 +2,6 @@
 pragma solidity ^0.8.20;
 
 import {BaseChecker} from "../../core/checker/BaseChecker.sol";
-import {Checker} from "../../core/checker/Checker.sol";
 import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";
 
 /// @title BaseERC721Checker.
@@ -12,9 +11,9 @@ contract BaseERC721Checker is BaseChecker {
     /// @notice NFT contract reference.
     IERC721 public nft;
 
-    function initialize() public virtual override {
+    function _initialize() internal override {
         // 1. Call super to handle `_initialized` check.
-        super.initialize();
+        super._initialize();
 
         // 2. Retrieve appended bytes from the clone.
         bytes memory data = _getAppendedBytes();