From 6036dff7f0ddeecf2f5af4d24efc9eabf4b155c0 Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Mon, 26 Feb 2024 15:58:24 +0000
Subject: [PATCH 01/15] (Hub): group mint

---
 src/circles/DiscountedBalances.sol |   3 +-
 src/groups/BaseMintPolicy.sol      |   6 ++
 src/groups/IMintPolicy.sol         |  12 ++++
 src/hub/Hub.sol                    | 102 ++++++++++++++++-------------
 4 files changed, 75 insertions(+), 48 deletions(-)
 create mode 100644 src/groups/BaseMintPolicy.sol
 create mode 100644 src/groups/IMintPolicy.sol

diff --git a/src/circles/DiscountedBalances.sol b/src/circles/DiscountedBalances.sol
index df689d1..7f71ba8 100644
--- a/src/circles/DiscountedBalances.sol
+++ b/src/circles/DiscountedBalances.sol
@@ -95,8 +95,9 @@ contract DiscountedBalances {
 
     /**
      * @dev stores the discounted balances of the accounts privately.
+     * Mapping from Circles identifiers to accounts to the discounted balance.
      */
-    mapping(uint256 id => mapping(address account => DiscountedBalance)) private discountedBalances;
+    mapping(uint256 => mapping(address => DiscountedBalance)) private discountedBalances;
 
     /**
      * @dev Store a lookup table T(n) for computing issuance.
diff --git a/src/groups/BaseMintPolicy.sol b/src/groups/BaseMintPolicy.sol
new file mode 100644
index 0000000..59393e3
--- /dev/null
+++ b/src/groups/BaseMintPolicy.sol
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity >=0.8.13;
+
+import "./IMintPolicy.sol";
+
+abstract contract MintPolicy is IMintPolicy {}
diff --git a/src/groups/IMintPolicy.sol b/src/groups/IMintPolicy.sol
new file mode 100644
index 0000000..5a3cd2b
--- /dev/null
+++ b/src/groups/IMintPolicy.sol
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity >=0.8.13;
+
+interface IMintPolicy {
+    function beforeMintPolicy(
+        address minter,
+        address group,
+        address[] calldata collateral,
+        uint256[] calldata amounts,
+        bytes calldata _data
+    ) external returns (bool);
+}
diff --git a/src/hub/Hub.sol b/src/hub/Hub.sol
index 70fcc9f..1c7ee1c 100644
--- a/src/hub/Hub.sol
+++ b/src/hub/Hub.sol
@@ -7,6 +7,7 @@ import "openzeppelin-contracts/contracts/utils/Create2.sol";
 import "../migration/IHub.sol";
 import "../migration/IToken.sol";
 import "../circles/Circles.sol";
+import "../groups/IMintPolicy.sol";
 
 /**
  * @title Hub v2 contract for Circles
@@ -208,34 +209,6 @@ contract Hub is Circles {
         emit InviteHuman(msg.sender, _human);
     }
 
-    /**
-     * @notice Invite human as organization allows to register a human avatar as an organization.
-     * @param _human address of the human to invite
-     * @param _donationReceiver address of where to send the donation to with 2300 gas (using transfer)
-     */
-    function inviteHumanAsOrganization(address _human, address payable _donationReceiver) external payable {
-        require(msg.value > MINIMUM_DONATION, "Donation must be at least 0.1 xDai.");
-        // The donation is understood to be a reputational requirement for the organization.
-        // It is obvious that one can send to self over a different address, but that is reputationally worthless.
-        // Nonetheless, we require to not directly send to self, mostly to avoid "plausible denial" arguments.
-        require(_donationReceiver != msg.sender, "Donation receiver cannot be the caller.");
-        require(isOrganization(msg.sender), "Only organizations can invite.");
-
-        _registerHuman(_human);
-
-        // set trust for a year, but organization can edit this later
-        _trust(msg.sender, _human, uint96(block.timestamp + 365 days));
-
-        // invited receives the welcome bonus in their personal Circles
-        _mint(_human, toTokenId(_human), WELCOME_BONUS, "");
-
-        // send the donation to the donation receiver but with minimal gas
-        // to avoid reentrancy attacks
-        _donationReceiver.transfer(msg.value);
-
-        emit InviteHuman(msg.sender, _human);
-    }
-
     /**
      * @notice Register group allows to register a group avatar.
      * @param _mint mint address will be called before minting group circles
@@ -287,7 +260,7 @@ contract Hub is Circles {
      * @param _cidV0Digest IPFS CIDv0 digest for the organization metadata
      */
     function registerOrganization(string calldata _name, bytes32 _cidV0Digest) external {
-        require(_isValidName(_name), "Invalid organization name.");
+        require(isValidName(_name), "Invalid organization name.");
         _insertAvatar(msg.sender);
 
         // store the name for the organization
@@ -338,22 +311,45 @@ contract Hub is Circles {
 
     // graph transfers SHOULD allow personal -> group conversion en route
 
-    // msg.sender holds collateral, and MUST be accepted by group
-    // maybe less
-    function groupMint(address _group, uint256[] calldata _collateral, uint256[] calldata _amounts) external {
-        // check group and collateral exist
-        // de-demurrage amounts
-        // loop over collateral
+    /**
+     * @notice Group mint allows to mint group Circles by providing the required collateral.
+     * @param _group address of the group avatar to mint Circles of
+     * @param _collateral array of (personal or group) avatar addresses to be used as collateral
+     * @param _amounts array of amounts of collateral to be used for minting
+     * @param _data (optional) additional data to be passed to the treasury and minter
+     */
+    function groupMint(
+        address _group,
+        address[] calldata _collateral,
+        uint256[] calldata _amounts,
+        bytes calldata _data
+    ) external {
+        require(_collateral.length == _amounts.length, "Collateral and amount arrays must have equal length");
+        require(_collateral.length > 0, "At least one collateral must be provided");
+        require(isGroup(_group), "Group is not registered as an avatar.");
+
+        // note: we don't need to check whether collateral circle ids are registered,
+        // because only for registered collateral do non-zero balances exist to transfer,
+        // so it suffices to check that all amounts are non-zero during summing.
+        uint256 sumAmounts = 0;
+        uint256[] memory collateralCirclesIds = new uint256[](_collateral.length);
+        for (uint256 i = 0; i < _amounts.length; i++) {
+            require(isTrusted(_group, _collateral[i]), "Collateral must be trusted");
+            require(_amounts[i] > 0, "Non-zero collateral must be provided.");
+            sumAmounts += _amounts[i];
+            collateralCirclesIds[i] = toTokenId(_collateral[i]);
+        }
 
-        //require(
-        //mintPolicies[_group].beforeMintPolicy(msg.sender, _group, _collateral, _amounts), "");
+        // Rely on the mint policy to determine whether the collateral is valid for minting
+        require(
+            IMintPolicy(mintPolicies[_group]).beforeMintPolicy(msg.sender, _group, _collateral, _amounts, _data),
+            "Mint policy rejected mint."
+        );
 
-        safeBatchTransferFrom(msg.sender, treasuries[_group], _collateral, _amounts, ""); // treasury.on1155Received should only implement but nothing protocol related
+        // note: treasury.on1155Received must implement but no further requirements
+        safeBatchTransferFrom(msg.sender, treasuries[_group], collateralCirclesIds, _amounts, _data);
 
-        uint256 sumAmounts;
-        // TODO sum up amounts
-        sumAmounts = _amounts[0];
-        _mint(msg.sender, toTokenId(_group), sumAmounts, "");
+        _mint(msg.sender, toTokenId(_group), sumAmounts, _data);
     }
 
     function stop() external {
@@ -389,6 +385,8 @@ contract Hub is Circles {
         //require("nett sources have approved operator");
     }
 
+    // Public functions
+
     function getDeterministicAddress(uint256 _tokenId, bytes32 _bytecodeHash) public view returns (address) {
         return Create2.computeAddress(keccak256(abi.encodePacked(_tokenId)), _bytecodeHash);
     }
@@ -469,7 +467,7 @@ contract Hub is Circles {
     }
 
     /**
-     * Checks if an avatar is registered as an organization.
+     * @notice Checks if an avatar is registered as an organization.
      * @param _organization address of the organization to check
      */
     function isOrganization(address _organization) public view returns (bool) {
@@ -477,6 +475,16 @@ contract Hub is Circles {
             && mintTimes[_organization].lastMintTime == uint256(0);
     }
 
+    /**
+     * @notice Returns true if the truster trusts the trustee.
+     * @param _truster Address of the trusting account
+     * @param _trustee Address of the trusted account
+     */
+    function isTrusted(address _truster, address _trustee) public view returns (bool) {
+        // trust up until expiry timestamp
+        return uint256(trustMarkers[_truster][_trustee].expiry) > block.timestamp;
+    }
+
     /**
      * uri returns the IPFS URI for the ERC1155 token.
      * If the
@@ -500,7 +508,7 @@ contract Hub is Circles {
      * should provide the full display name with unicode characters.
      * Names are not checked for uniqueness.
      */
-    function _isValidName(string memory _name) public pure returns (bool) {
+    function isValidName(string memory _name) public pure returns (bool) {
         bytes memory nameBytes = bytes(_name);
         if (nameBytes.length > 32 || nameBytes.length == 0) return false; // Check length
 
@@ -529,7 +537,7 @@ contract Hub is Circles {
      * the length as max 16 bytes and the allowed characters: 0-9, A-Z, a-z,
      * hyphen, underscore.
      */
-    function _isValidSymbol(string memory _symbol) public pure returns (bool) {
+    function isValidSymbol(string memory _symbol) public pure returns (bool) {
         bytes memory symbolBytes = bytes(_symbol);
         if (symbolBytes.length == 0 || symbolBytes.length > 16) {
             return false; // Check length is within range
@@ -595,9 +603,9 @@ contract Hub is Circles {
         // todo: same check treasury is an ERC1155Receiver for receiving collateral
         require(_treasury != address(0), "Treasury address can not be zero.");
         // name must be ASCII alphanumeric and some special characters
-        require(_isValidName(_name), "Invalid group name.");
+        require(isValidName(_name), "Invalid group name.");
         // symbol must be ASCII alphanumeric and some special characters
-        require(_isValidSymbol(_symbol), "Invalid group symbol.");
+        require(isValidSymbol(_symbol), "Invalid group symbol.");
 
         // insert avatar into linked list; reverts if it already exists
         _insertAvatar(_avatar);

From e245c95cd5fef37acc6393bbeafa04cf71ee916c Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Mon, 26 Feb 2024 19:08:01 +0000
Subject: [PATCH 02/15] (treasury): standard treasury

---
 src/groups/BaseMintPolicy.sol     | 20 +++++++++++++++++++-
 src/groups/IMintPolicy.sol        |  2 +-
 src/hub/Hub.sol                   |  2 +-
 src/treasury/standardTreasury.sol | 25 +++++++++++++++++++++++++
 src/treasury/standardVault.sol    |  1 +
 5 files changed, 47 insertions(+), 3 deletions(-)
 create mode 100644 src/treasury/standardTreasury.sol
 create mode 100644 src/treasury/standardVault.sol

diff --git a/src/groups/BaseMintPolicy.sol b/src/groups/BaseMintPolicy.sol
index 59393e3..d53d179 100644
--- a/src/groups/BaseMintPolicy.sol
+++ b/src/groups/BaseMintPolicy.sol
@@ -3,4 +3,22 @@ pragma solidity >=0.8.13;
 
 import "./IMintPolicy.sol";
 
-abstract contract MintPolicy is IMintPolicy {}
+abstract contract MintPolicy is IMintPolicy {
+    /**
+     * @notice Simple mint policy that always returns true
+     * @param minter Address of the minter
+     * @param group Address of the group
+     * @param collateral Array of collateral addresses
+     * @param amounts Array of collateral amounts
+     * @param data Optional data bytes passed to mint policy
+     */
+    function beforeMintPolicy(
+        address minter,
+        address group,
+        address[] calldata collateral,
+        uint256[] calldata amounts,
+        bytes calldata data
+    ) external virtual override returns (bool) {
+        return true;
+    }
+}
diff --git a/src/groups/IMintPolicy.sol b/src/groups/IMintPolicy.sol
index 5a3cd2b..a78fa78 100644
--- a/src/groups/IMintPolicy.sol
+++ b/src/groups/IMintPolicy.sol
@@ -7,6 +7,6 @@ interface IMintPolicy {
         address group,
         address[] calldata collateral,
         uint256[] calldata amounts,
-        bytes calldata _data
+        bytes calldata data
     ) external returns (bool);
 }
diff --git a/src/hub/Hub.sol b/src/hub/Hub.sol
index 1c7ee1c..69c8922 100644
--- a/src/hub/Hub.sol
+++ b/src/hub/Hub.sol
@@ -316,7 +316,7 @@ contract Hub is Circles {
      * @param _group address of the group avatar to mint Circles of
      * @param _collateral array of (personal or group) avatar addresses to be used as collateral
      * @param _amounts array of amounts of collateral to be used for minting
-     * @param _data (optional) additional data to be passed to the treasury and minter
+     * @param _data (optional) additional data to be passed to the mint policy, treasury and minter
      */
     function groupMint(
         address _group,
diff --git a/src/treasury/standardTreasury.sol b/src/treasury/standardTreasury.sol
new file mode 100644
index 0000000..89ddbbf
--- /dev/null
+++ b/src/treasury/standardTreasury.sol
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity >=0.8.13;
+
+import "@openzeppelin/contracts/token/ERC1155/utils/ERC1155Holder.sol";
+import "../proxy/ProxyFactory.sol";
+
+contract standardTreasury is ERC1155Holder, ProxyFactory {
+    function onERC1155Received(address, address, uint256, uint256, bytes memory)
+        public
+        virtual
+        override
+        returns (bytes4)
+    {
+        return this.onERC1155Received.selector;
+    }
+
+    function onERC1155BatchReceived(address, address, uint256[] memory, uint256[] memory, bytes memory)
+        public
+        virtual
+        override
+        returns (bytes4)
+    {
+        return this.onERC1155BatchReceived.selector;
+    }
+}
diff --git a/src/treasury/standardVault.sol b/src/treasury/standardVault.sol
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/src/treasury/standardVault.sol
@@ -0,0 +1 @@
+

From 54d04bd01a90e2230f09d6cc8e060f78753ced4e Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Tue, 27 Feb 2024 16:29:27 +0000
Subject: [PATCH 03/15] (Hub): treasury needs group information

---
 src/hub/Hub.sol                   | 31 ++++++++++++++++++++++++++++---
 src/hub/IHub.sol                  |  1 +
 src/treasury/standardTreasury.sol | 20 ++++++++++++++++++++
 3 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/src/hub/Hub.sol b/src/hub/Hub.sol
index 69c8922..0b0c246 100644
--- a/src/hub/Hub.sol
+++ b/src/hub/Hub.sol
@@ -8,6 +8,7 @@ import "../migration/IHub.sol";
 import "../migration/IToken.sol";
 import "../circles/Circles.sol";
 import "../groups/IMintPolicy.sol";
+import "./IHub.sol";
 
 /**
  * @title Hub v2 contract for Circles
@@ -20,7 +21,7 @@ import "../groups/IMintPolicy.sol";
  * It further allows to wrap any token into an inflationary or demurraged
  * ERC20 Circles contract.
  */
-contract Hub is Circles {
+contract Hub is Circles, IHubV2 {
     // Type declarations
 
     /**
@@ -34,6 +35,16 @@ contract Hub is Circles {
         uint96 expiry;
     }
 
+    struct Metadata {
+        MetadataType metadataType;
+        bytes metadata;
+        bytes erc1155UserData;
+    }
+
+    struct GroupMintMetadata {
+        address group;
+    }
+
     // Constants
 
     /**
@@ -53,6 +64,13 @@ contract Hub is Circles {
      */
     address public constant SENTINEL = address(0x1);
 
+    // Enums
+
+    enum MetadataType {
+        NoMetadata,
+        GroupMint // safeTransferFrom initiated from group mint, appends GroupMintMetadata
+    }
+
     // State variables
 
     /**
@@ -346,9 +364,16 @@ contract Hub is Circles {
             "Mint policy rejected mint."
         );
 
-        // note: treasury.on1155Received must implement but no further requirements
-        safeBatchTransferFrom(msg.sender, treasuries[_group], collateralCirclesIds, _amounts, _data);
+        // abi encode the group address into the data to send onwards to the treasury
+        bytes memory metadataGroup = abi.encode(GroupMintMetadata({group: _group}));
+        bytes memory dataWithGroup = abi.encode(
+            Metadata({metadataType: MetadataType.GroupMint, metadata: metadataGroup, erc1155UserData: _data})
+        );
+
+        // note: treasury.on1155Received must implement and unpack the GroupMintMetadata to know the group
+        safeBatchTransferFrom(msg.sender, treasuries[_group], collateralCirclesIds, _amounts, dataWithGroup);
 
+        // mint group Circles to the sender and send the original _data onwards
         _mint(msg.sender, toTokenId(_group), sumAmounts, _data);
     }
 
diff --git a/src/hub/IHub.sol b/src/hub/IHub.sol
index 946b1b5..ed2d01f 100644
--- a/src/hub/IHub.sol
+++ b/src/hub/IHub.sol
@@ -3,4 +3,5 @@ pragma solidity >=0.8.13;
 
 interface IHubV2 {
     function avatars(address _avatar) external view returns (address);
+    function mintPolicies(address _avatar) external view returns (address);
 }
diff --git a/src/treasury/standardTreasury.sol b/src/treasury/standardTreasury.sol
index 89ddbbf..5dab59b 100644
--- a/src/treasury/standardTreasury.sol
+++ b/src/treasury/standardTreasury.sol
@@ -5,10 +5,29 @@ import "@openzeppelin/contracts/token/ERC1155/utils/ERC1155Holder.sol";
 import "../proxy/ProxyFactory.sol";
 
 contract standardTreasury is ERC1155Holder, ProxyFactory {
+    // State variables
+
+    address public immutable hub;
+
+    // modifier
+
+    modifier onlyHub() {
+        require(msg.sender == hub, "Treasury: caller is not the hub");
+        _;
+    }
+
+    // Constructor
+
+    constructor(address _hub) {
+        require(_hub != address(0), "Hub address cannot be 0");
+        hub = _hub;
+    }
+
     function onERC1155Received(address, address, uint256, uint256, bytes memory)
         public
         virtual
         override
+        onlyHub
         returns (bytes4)
     {
         return this.onERC1155Received.selector;
@@ -18,6 +37,7 @@ contract standardTreasury is ERC1155Holder, ProxyFactory {
         public
         virtual
         override
+        onlyHub
         returns (bytes4)
     {
         return this.onERC1155BatchReceived.selector;

From c3da860ede8cec21f7c0f2580e4d70a2ff8592e7 Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Tue, 27 Feb 2024 16:33:26 +0000
Subject: [PATCH 04/15] (Definitions): move definitions to separate contract
 for use in treasury

---
 src/hub/Hub.sol                 | 26 +++++++-------------------
 src/hub/MetadataDefinitions.sol | 23 +++++++++++++++++++++++
 2 files changed, 30 insertions(+), 19 deletions(-)
 create mode 100644 src/hub/MetadataDefinitions.sol

diff --git a/src/hub/Hub.sol b/src/hub/Hub.sol
index 0b0c246..9cced90 100644
--- a/src/hub/Hub.sol
+++ b/src/hub/Hub.sol
@@ -9,6 +9,7 @@ import "../migration/IToken.sol";
 import "../circles/Circles.sol";
 import "../groups/IMintPolicy.sol";
 import "./IHub.sol";
+import "./MetadataDefinitions.sol";
 
 /**
  * @title Hub v2 contract for Circles
@@ -35,16 +36,6 @@ contract Hub is Circles, IHubV2 {
         uint96 expiry;
     }
 
-    struct Metadata {
-        MetadataType metadataType;
-        bytes metadata;
-        bytes erc1155UserData;
-    }
-
-    struct GroupMintMetadata {
-        address group;
-    }
-
     // Constants
 
     /**
@@ -64,13 +55,6 @@ contract Hub is Circles, IHubV2 {
      */
     address public constant SENTINEL = address(0x1);
 
-    // Enums
-
-    enum MetadataType {
-        NoMetadata,
-        GroupMint // safeTransferFrom initiated from group mint, appends GroupMintMetadata
-    }
-
     // State variables
 
     /**
@@ -365,9 +349,13 @@ contract Hub is Circles, IHubV2 {
         );
 
         // abi encode the group address into the data to send onwards to the treasury
-        bytes memory metadataGroup = abi.encode(GroupMintMetadata({group: _group}));
+        bytes memory metadataGroup = abi.encode(MetadataDefinitions.GroupMintMetadata({group: _group}));
         bytes memory dataWithGroup = abi.encode(
-            Metadata({metadataType: MetadataType.GroupMint, metadata: metadataGroup, erc1155UserData: _data})
+            MetadataDefinitions.Metadata({
+                metadataType: MetadataDefinitions.MetadataType.GroupMint,
+                metadata: metadataGroup,
+                erc1155UserData: _data
+            })
         );
 
         // note: treasury.on1155Received must implement and unpack the GroupMintMetadata to know the group
diff --git a/src/hub/MetadataDefinitions.sol b/src/hub/MetadataDefinitions.sol
new file mode 100644
index 0000000..8607f5e
--- /dev/null
+++ b/src/hub/MetadataDefinitions.sol
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity >=0.8.13;
+
+contract MetadataDefinitions {
+    // Type declarations
+
+    struct Metadata {
+        MetadataType metadataType;
+        bytes metadata;
+        bytes erc1155UserData;
+    }
+
+    struct GroupMintMetadata {
+        address group;
+    }
+
+    // Enums
+
+    enum MetadataType {
+        NoMetadata,
+        GroupMint // safeTransferFrom initiated from group mint, appends GroupMintMetadata
+    }
+}

From 43b15aa3331cb12d6dee90962f8f022eedd71615 Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Tue, 27 Feb 2024 19:11:45 +0000
Subject: [PATCH 05/15] (treasury): start making vault master copy

---
 src/hub/Hub.sol                   |  6 +--
 src/treasury/standardTreasury.sol | 69 ++++++++++++++++++++++++-------
 src/treasury/standardVault.sol    | 53 ++++++++++++++++++++++++
 3 files changed, 109 insertions(+), 19 deletions(-)

diff --git a/src/hub/Hub.sol b/src/hub/Hub.sol
index 9cced90..4f0e1df 100644
--- a/src/hub/Hub.sol
+++ b/src/hub/Hub.sol
@@ -1,9 +1,9 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 pragma solidity >=0.8.13;
 
-import "openzeppelin-contracts/contracts/token/ERC1155/utils/ERC1155Holder.sol";
-import "openzeppelin-contracts/contracts/token/ERC20/ERC20.sol";
-import "openzeppelin-contracts/contracts/utils/Create2.sol";
+import "@openzeppelin/contracts/token/ERC1155/utils/ERC1155Holder.sol";
+import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
+import "@openzeppelin/contracts/utils/Create2.sol";
 import "../migration/IHub.sol";
 import "../migration/IToken.sol";
 import "../circles/Circles.sol";
diff --git a/src/treasury/standardTreasury.sol b/src/treasury/standardTreasury.sol
index 5dab59b..60dc22a 100644
--- a/src/treasury/standardTreasury.sol
+++ b/src/treasury/standardTreasury.sol
@@ -2,14 +2,33 @@
 pragma solidity >=0.8.13;
 
 import "@openzeppelin/contracts/token/ERC1155/utils/ERC1155Holder.sol";
+import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
+import "@openzeppelin/contracts/token/ERC1155/IERC1155Receiver.sol";
 import "../proxy/ProxyFactory.sol";
+import "../hub/MetadataDefinitions.sol";
+
+contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
+    // Constants
+
+    /**
+     * @dev The call prefix for the setup function on the vault contract
+     */
+    bytes4 public constant STANDARD_VAULT_SETUP_CALLPREFIX = bytes4(keccak256("setup(address)"));
 
-contract standardTreasury is ERC1155Holder, ProxyFactory {
     // State variables
 
     address public immutable hub;
 
-    // modifier
+    /**
+     * @notice Mapping of group address to vault address
+     * @dev The vault is the contract that holds the group's collateral
+     * todo: we could use deterministic vault addresses as to not store them
+     * but then we still need to check whether the correct code has been deployed
+     * so we might as well deploy and store the addresses?
+     */
+    mapping(address => address) public vaults;
+
+    // Modifiers
 
     modifier onlyHub() {
         require(msg.sender == hub, "Treasury: caller is not the hub");
@@ -23,23 +42,41 @@ contract standardTreasury is ERC1155Holder, ProxyFactory {
         hub = _hub;
     }
 
-    function onERC1155Received(address, address, uint256, uint256, bytes memory)
-        public
-        virtual
-        override
-        onlyHub
-        returns (bytes4)
-    {
+    // Public functions
+
+    /**
+     * @dev See {IERC165-supportsInterface}.
+     */
+    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
+        return interfaceId == type(IERC1155Receiver).interfaceId || super.supportsInterface(interfaceId);
+    }
+
+    function onERC1155Received(
+        address, /*_operator*/
+        address, /*_from*/
+        uint256, /*_id*/
+        uint256, /*_value*/
+        bytes memory /*_data*/
+    ) public virtual override onlyHub returns (bytes4) {
         return this.onERC1155Received.selector;
     }
 
-    function onERC1155BatchReceived(address, address, uint256[] memory, uint256[] memory, bytes memory)
-        public
-        virtual
-        override
-        onlyHub
-        returns (bytes4)
-    {
+    function onERC1155BatchReceived(
+        address _operator,
+        address _from,
+        uint256[] memory _ids,
+        uint256[] memory _values,
+        bytes memory _data
+    ) public virtual override onlyHub returns (bytes4) {
+        MetadataDefinitions.Metadata memory metadata = abi.decode(_data, (MetadataDefinitions.Metadata));
+        require(metadata.metadataType == MetadataDefinitions.MetadataType.GroupMint, "Treasury: Invalid metadata type");
+        MetadataDefinitions.GroupMintMetadata memory groupMintMetadata =
+            abi.decode(metadata.metadata, (MetadataDefinitions.GroupMintMetadata));
+
         return this.onERC1155BatchReceived.selector;
     }
+
+    // Internal functions
+
+    function _getVault(address _group) internal returns (address) {}
 }
diff --git a/src/treasury/standardVault.sol b/src/treasury/standardVault.sol
index 8b13789..779e09a 100644
--- a/src/treasury/standardVault.sol
+++ b/src/treasury/standardVault.sol
@@ -1 +1,54 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity >=0.8.13;
 
+import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
+import "@openzeppelin/contracts/token/ERC1155/IERC1155Receiver.sol";
+
+contract standardVault is ERC165, IERC1155Receiver {
+    // State variables
+
+    address public standardTreasury;
+
+    // Constructor
+
+    constructor() {
+        standardTreasury = address(1);
+    }
+
+    // External functions
+
+    function setup(address _standardTreasury) external {
+        require(standardTreasury == address(0), "Vault contract has already been setup.");
+        require(_standardTreasury != address(0), "Treasury address must not be zero address");
+        standardTreasury = _standardTreasury;
+    }
+
+    // Public functions
+
+    /**
+     * @dev See {IERC165-supportsInterface}.
+     */
+    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
+        return interfaceId == type(IERC1155Receiver).interfaceId || super.supportsInterface(interfaceId);
+    }
+
+    function onERC1155Received(
+        address, /*_operator*/
+        address, /*_from*/
+        uint256, /*_id*/
+        uint256, /*_value*/
+        bytes memory /*_data*/
+    ) public virtual override returns (bytes4) {
+        return this.onERC1155Received.selector;
+    }
+
+    function onERC1155BatchReceived(
+        address, /*_operator*/
+        address, /*_from*/
+        uint256[] memory, /*_ids*/
+        uint256[] memory, /*_values*/
+        bytes memory /*_data*/
+    ) public virtual override returns (bytes4) {
+        return this.onERC1155BatchReceived.selector;
+    }
+}

From 35c20073d084f980a1cb5b11ae5fba0ea991f4a1 Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Wed, 28 Feb 2024 19:48:56 +0000
Subject: [PATCH 06/15] (treasury): complete standard treasury and vaults basic
 logic

---
 src/graph/Graph.sol               |   4 +-
 src/groups/IMintPolicy.sol        |   8 +++
 src/hub/Hub.sol                   |  16 +++++
 src/hub/IHub.sol                  |   9 ++-
 src/proxy/ProxyFactory.sol        |   2 +-
 src/treasury/IStandardVault.sol   |   7 ++
 src/treasury/standardTreasury.sol | 102 +++++++++++++++++++++++++-----
 src/treasury/standardVault.sol    |  34 ++++++++--
 8 files changed, 155 insertions(+), 27 deletions(-)
 create mode 100644 src/treasury/IStandardVault.sol

diff --git a/src/graph/Graph.sol b/src/graph/Graph.sol
index f656643..580e94f 100644
--- a/src/graph/Graph.sol
+++ b/src/graph/Graph.sol
@@ -230,7 +230,7 @@ contract Graph is ProxyFactory, IGraph {
     function registerAvatar() external notOnTrustGraph(msg.sender) {
         bytes memory avatarCircleNodeSetupData = abi.encodeWithSelector(AVATAR_CIRCLE_SETUP_CALLPREFIX, msg.sender);
         IAvatarCircleNode avatarCircleNode =
-            IAvatarCircleNode(address(createProxy(address(masterCopyAvatarCircleNode), avatarCircleNodeSetupData)));
+            IAvatarCircleNode(address(_createProxy(address(masterCopyAvatarCircleNode), avatarCircleNodeSetupData)));
 
         avatarToCircle[msg.sender] = avatarCircleNode;
         _insertAvatarCircleNode(avatarCircleNode);
@@ -246,7 +246,7 @@ contract Graph is ProxyFactory, IGraph {
         bytes memory groupCircleNodeSetupData =
             abi.encodeWithSelector(GROUP_CIRCLE_SETUP_CALLPREFIX, msg.sender, _exitFee_64x64);
         IGroupCircleNode groupCircleNode =
-            IGroupCircleNode(address(createProxy(address(masterCopyGroupCircleNode), groupCircleNodeSetupData)));
+            IGroupCircleNode(address(_createProxy(address(masterCopyGroupCircleNode), groupCircleNodeSetupData)));
 
         groupToCircle[msg.sender] = groupCircleNode;
         _insertGroupCircleNode(groupCircleNode);
diff --git a/src/groups/IMintPolicy.sol b/src/groups/IMintPolicy.sol
index a78fa78..0190e57 100644
--- a/src/groups/IMintPolicy.sol
+++ b/src/groups/IMintPolicy.sol
@@ -9,4 +9,12 @@ interface IMintPolicy {
         uint256[] calldata amounts,
         bytes calldata data
     ) external returns (bool);
+
+    function beforeRedeemPolicy(address operator, address redeemer, address group, uint256 value, bytes calldata data)
+        external
+        returns (uint256[] memory ids, uint256[] memory values);
+
+    function beforeBurnPolicy(address burner, address group, uint256 value, bytes calldata data)
+        external
+        returns (bool);
 }
diff --git a/src/hub/Hub.sol b/src/hub/Hub.sol
index 4f0e1df..f198c4f 100644
--- a/src/hub/Hub.sol
+++ b/src/hub/Hub.sol
@@ -379,6 +379,22 @@ contract Hub is Circles, IHubV2 {
         return (mintTime.lastMintTime == INDEFINITE_FUTURE);
     }
 
+    function burn(uint256 _id, uint256 _amount) external {
+        // todo: by construction we can not have an id with non-zero balance,
+        // that was not converted from a group address.
+        // for now, do a redundant check that the id is identical to the recovered address
+        address group = address(uint160(_id));
+        require(uint256(uint160(group)) == _id, "Invalid Circles identifier.");
+
+        IMintPolicy policy = IMintPolicy(mintPolicies[group]);
+        if (address(policy) != address(0) && treasuries[group] != msg.sender) {
+            // if Circles are a group Circles and if the burner is not the associated treasury,
+            // then the mint policy must approve the burn
+            require(policy.beforeBurnPolicy(msg.sender, group, _amount, ""), "Burn policy rejected burn.");
+        }
+        _burn(msg.sender, _id, _amount);
+    }
+
     // check if path transfer can be fully ERC1155 compatible
     // note: matrix math needs to consider mints, otherwise it won't add up
 
diff --git a/src/hub/IHub.sol b/src/hub/IHub.sol
index ed2d01f..c2c8b19 100644
--- a/src/hub/IHub.sol
+++ b/src/hub/IHub.sol
@@ -1,7 +1,10 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 pragma solidity >=0.8.13;
 
-interface IHubV2 {
-    function avatars(address _avatar) external view returns (address);
-    function mintPolicies(address _avatar) external view returns (address);
+import "@openzeppelin/contracts/token/ERC1155/IERC1155.sol";
+
+interface IHubV2 is IERC1155 {
+    function avatars(address avatar) external view returns (address);
+    function mintPolicies(address avatar) external view returns (address);
+    function burn(uint256 id, uint256 amount) external;
 }
diff --git a/src/proxy/ProxyFactory.sol b/src/proxy/ProxyFactory.sol
index c6e7b94..312ea11 100644
--- a/src/proxy/ProxyFactory.sol
+++ b/src/proxy/ProxyFactory.sol
@@ -14,7 +14,7 @@ contract ProxyFactory {
     ///      execute a message call to the new proxy within one transaction.
     /// @param masterCopy Address of master copy.
     /// @param data Payload for message call sent to new proxy contract.
-    function createProxy(address masterCopy, bytes memory data) internal returns (Proxy proxy) {
+    function _createProxy(address masterCopy, bytes memory data) internal returns (Proxy proxy) {
         proxy = new Proxy(masterCopy);
         if (data.length > 0) {
             // solhint-disable-next-line no-inline-assembly
diff --git a/src/treasury/IStandardVault.sol b/src/treasury/IStandardVault.sol
new file mode 100644
index 0000000..368c4b7
--- /dev/null
+++ b/src/treasury/IStandardVault.sol
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity >=0.8.13;
+
+interface IStandardVault {
+    function returnCollateral(address receiver, uint256[] calldata ids, uint256[] calldata values, bytes calldata data)
+        external;
+}
diff --git a/src/treasury/standardTreasury.sol b/src/treasury/standardTreasury.sol
index 60dc22a..189cc0d 100644
--- a/src/treasury/standardTreasury.sol
+++ b/src/treasury/standardTreasury.sol
@@ -6,6 +6,9 @@ import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
 import "@openzeppelin/contracts/token/ERC1155/IERC1155Receiver.sol";
 import "../proxy/ProxyFactory.sol";
 import "../hub/MetadataDefinitions.sol";
+import "../hub/IHub.sol";
+import "../groups/IMintPolicy.sol";
+import "./IStandardVault.sol";
 
 contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
     // Constants
@@ -13,11 +16,19 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
     /**
      * @dev The call prefix for the setup function on the vault contract
      */
-    bytes4 public constant STANDARD_VAULT_SETUP_CALLPREFIX = bytes4(keccak256("setup(address)"));
+    bytes4 public constant STANDARD_VAULT_SETUP_CALLPREFIX = bytes4(keccak256("setup()"));
 
     // State variables
 
-    address public immutable hub;
+    /**
+     * @notice Address of the hub contract
+     */
+    IHubV2 public immutable hub;
+
+    /**
+     * @notice Address of the mastercopy standard vault contract
+     */
+    address public immutable mastercopyStandardVault;
 
     /**
      * @notice Mapping of group address to vault address
@@ -26,20 +37,22 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
      * but then we still need to check whether the correct code has been deployed
      * so we might as well deploy and store the addresses?
      */
-    mapping(address => address) public vaults;
+    mapping(address => IStandardVault) public vaults;
 
     // Modifiers
 
     modifier onlyHub() {
-        require(msg.sender == hub, "Treasury: caller is not the hub");
+        require(msg.sender == address(hub), "Treasury: caller is not the hub");
         _;
     }
 
     // Constructor
 
-    constructor(address _hub) {
-        require(_hub != address(0), "Hub address cannot be 0");
+    constructor(IHubV2 _hub, address _mastercopyStandardVault) {
+        require(address(_hub) != address(0), "Hub address cannot be 0");
+        require(_mastercopyStandardVault != address(0), "Mastercopy standard vault address cannot be 0");
         hub = _hub;
+        mastercopyStandardVault = _mastercopyStandardVault;
     }
 
     // Public functions
@@ -51,32 +64,89 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
         return interfaceId == type(IERC1155Receiver).interfaceId || super.supportsInterface(interfaceId);
     }
 
-    function onERC1155Received(
-        address, /*_operator*/
-        address, /*_from*/
-        uint256, /*_id*/
-        uint256, /*_value*/
-        bytes memory /*_data*/
-    ) public virtual override onlyHub returns (bytes4) {
+    /**
+     * @dev Exclusively use single received for receiving group Circles to redeem them
+     * for collateral Circles according to the group mint policy
+     */
+    function onERC1155Received(address _operator, address _from, uint256 _id, uint256 _value, bytes memory _data)
+        public
+        virtual
+        override
+        returns (bytes4)
+    {
+        address group = _validateCirclesIdToGroup(_id);
+        IStandardVault vault = vaults[group];
+        require(address(vault) != address(0), "Treasury: Group has no vault");
+
+        // query the hub for the mint policy
+        IMintPolicy policy = IMintPolicy(hub.mintPolicies(group));
+        require(address(policy) != address(0), "Treasury: Invalid group without mint policy");
+
+        // query the mint policy for the redemption values
+        uint256[] memory redemptionIds;
+        uint256[] memory redemptionValues;
+        (redemptionIds, redemptionValues) = policy.beforeRedeemPolicy(_operator, _from, group, _value, _data);
+
+        // ensure the redemption values sum up to the correct amount
+        uint256 sum = 0;
+        for (uint256 i = 0; i < redemptionValues.length; i++) {
+            sum += redemptionValues[i];
+        }
+        require(sum == _value, "Treasury: Invalid redemption values from policy");
+
+        // burn the group Circles
+        hub.burn(_id, _value);
+
+        // return collateral Circles to the redeemer of group Circles
+        vault.returnCollateral(_from, redemptionIds, redemptionValues, _data);
+
         return this.onERC1155Received.selector;
     }
 
+    /**
+     * @dev Exclusively use batch received for receiving collateral Circles
+     * from the hub contract during group minting
+     */
     function onERC1155BatchReceived(
-        address _operator,
+        address, /*_operator*/
         address _from,
         uint256[] memory _ids,
         uint256[] memory _values,
         bytes memory _data
     ) public virtual override onlyHub returns (bytes4) {
+        // decode the data to get the group address
         MetadataDefinitions.Metadata memory metadata = abi.decode(_data, (MetadataDefinitions.Metadata));
         require(metadata.metadataType == MetadataDefinitions.MetadataType.GroupMint, "Treasury: Invalid metadata type");
         MetadataDefinitions.GroupMintMetadata memory groupMintMetadata =
             abi.decode(metadata.metadata, (MetadataDefinitions.GroupMintMetadata));
-
+        // ensure the vault exists
+        address vault = address(_ensureVault(groupMintMetadata.group));
+        // forward the Circles to the vault
+        hub.safeBatchTransferFrom(address(this), vault, _ids, _values, metadata.erc1155UserData);
         return this.onERC1155BatchReceived.selector;
     }
 
     // Internal functions
 
-    function _getVault(address _group) internal returns (address) {}
+    function _validateCirclesIdToGroup(uint256 _id) internal pure returns (address) {
+        address group = address(uint160(_id));
+        require(uint256(uint160(group)) == _id, "Treasury: Invalid group Circles id");
+        return group;
+    }
+
+    function _ensureVault(address _group) internal returns (IStandardVault) {
+        IStandardVault vault = vaults[_group];
+        if (address(vault) == address(0)) {
+            vault = _deployVault();
+            vaults[_group] = vault;
+        }
+        return vault;
+    }
+
+    // todo: this could be done with deterministic deployment, but same comment, not worth it
+    function _deployVault() internal returns (IStandardVault) {
+        bytes memory vaultSetupData = abi.encodeWithSelector(STANDARD_VAULT_SETUP_CALLPREFIX);
+        IStandardVault vault = IStandardVault(address(_createProxy(mastercopyStandardVault, vaultSetupData)));
+        return vault;
+    }
 }
diff --git a/src/treasury/standardVault.sol b/src/treasury/standardVault.sol
index 779e09a..6fd1804 100644
--- a/src/treasury/standardVault.sol
+++ b/src/treasury/standardVault.sol
@@ -3,12 +3,23 @@ pragma solidity >=0.8.13;
 
 import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
 import "@openzeppelin/contracts/token/ERC1155/IERC1155Receiver.sol";
+import "../hub/IHub.sol";
+import "./IStandardVault.sol";
 
-contract standardVault is ERC165, IERC1155Receiver {
+contract standardVault is ERC165, IERC1155Receiver, IStandardVault {
     // State variables
 
     address public standardTreasury;
 
+    IHubV2 public hub;
+
+    // Modifiers
+
+    modifier onlyTreasury() {
+        require(msg.sender == standardTreasury, "Vault: caller is not the treasury");
+        _;
+    }
+
     // Constructor
 
     constructor() {
@@ -17,10 +28,22 @@ contract standardVault is ERC165, IERC1155Receiver {
 
     // External functions
 
-    function setup(address _standardTreasury) external {
-        require(standardTreasury == address(0), "Vault contract has already been setup.");
-        require(_standardTreasury != address(0), "Treasury address must not be zero address");
-        standardTreasury = _standardTreasury;
+    function setup(IHubV2 _hub) external {
+        require(address(hub) == address(0), "Vault: already initialized");
+        standardTreasury = msg.sender;
+        hub = _hub;
+    }
+
+    function returnCollateral(
+        address _receiver,
+        uint256[] calldata _ids,
+        uint256[] calldata _values,
+        bytes calldata _data
+    ) external onlyTreasury {
+        require(_receiver != address(0), "Vault: receiver cannot be 0 address");
+
+        // return the collateral to the receiver
+        hub.safeBatchTransferFrom(address(this), _receiver, _ids, _values, _data);
     }
 
     // Public functions
@@ -49,6 +72,7 @@ contract standardVault is ERC165, IERC1155Receiver {
         uint256[] memory, /*_values*/
         bytes memory /*_data*/
     ) public virtual override returns (bytes4) {
+        // todo: register which collateral is stored in this vault?
         return this.onERC1155BatchReceived.selector;
     }
 }

From 0c3af1af406adaad444dc93a5fe68e5dfcb0c02d Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Wed, 28 Feb 2024 19:51:29 +0000
Subject: [PATCH 07/15] (MetadataDefinitions): ... why is fmt passing locally,
 but not on CI

---
 src/hub/MetadataDefinitions.sol | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/hub/MetadataDefinitions.sol b/src/hub/MetadataDefinitions.sol
index 8607f5e..2192cc0 100644
--- a/src/hub/MetadataDefinitions.sol
+++ b/src/hub/MetadataDefinitions.sol
@@ -18,6 +18,6 @@ contract MetadataDefinitions {
 
     enum MetadataType {
         NoMetadata,
-        GroupMint // safeTransferFrom initiated from group mint, appends GroupMintMetadata
+        GroupMint
     }
 }

From 40bba2d8b2c30a90a92c0e4a74bf5a41a802e3e6 Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Wed, 28 Feb 2024 20:00:18 +0000
Subject: [PATCH 08/15] (Treasury): correct vault setup calldata

---
 src/treasury/standardTreasury.sol | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/treasury/standardTreasury.sol b/src/treasury/standardTreasury.sol
index 189cc0d..a873ff3 100644
--- a/src/treasury/standardTreasury.sol
+++ b/src/treasury/standardTreasury.sol
@@ -16,7 +16,7 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
     /**
      * @dev The call prefix for the setup function on the vault contract
      */
-    bytes4 public constant STANDARD_VAULT_SETUP_CALLPREFIX = bytes4(keccak256("setup()"));
+    bytes4 public constant STANDARD_VAULT_SETUP_CALLPREFIX = bytes4(keccak256("setup(address)"));
 
     // State variables
 
@@ -145,7 +145,7 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
 
     // todo: this could be done with deterministic deployment, but same comment, not worth it
     function _deployVault() internal returns (IStandardVault) {
-        bytes memory vaultSetupData = abi.encodeWithSelector(STANDARD_VAULT_SETUP_CALLPREFIX);
+        bytes memory vaultSetupData = abi.encodeWithSelector(STANDARD_VAULT_SETUP_CALLPREFIX, hub);
         IStandardVault vault = IStandardVault(address(_createProxy(mastercopyStandardVault, vaultSetupData)));
         return vault;
     }

From 03e667e305b4054aa68a43c72547d7ad33861b04 Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Wed, 28 Feb 2024 20:03:21 +0000
Subject: [PATCH 09/15] (root): remove remappings.txt

---
 remappings.txt | 4 ----
 1 file changed, 4 deletions(-)
 delete mode 100644 remappings.txt

diff --git a/remappings.txt b/remappings.txt
deleted file mode 100644
index c36eea0..0000000
--- a/remappings.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-ds-test/=lib/forge-std/lib/ds-test/src/
-erc4626-tests/=lib/openzeppelin-contracts/lib/erc4626-tests/
-forge-std/=lib/forge-std/src/
-@openzeppelin/=lib/openzeppelin-contracts/

From 5cdac051edc6a44dca6bf0784fca3fbfa196b91a Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Thu, 29 Feb 2024 11:42:09 +0000
Subject: [PATCH 10/15] (test): probably won't work, set a commit for foundry

---
 .github/workflows/test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 91bcba0..d48aa48 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -25,7 +25,7 @@ jobs:
       - name: Install Foundry
         uses: foundry-rs/foundry-toolchain@v1
         with:
-          version: nightly
+          version: nightly-5b7e4cb3c882b28f3c32ba580de27ce7381f415a
 
       - name: Check Code Formatting
         run: |

From ab12b78ccb7cefd56c462e13b436a3765d53d7ed Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Thu, 29 Feb 2024 11:59:05 +0000
Subject: [PATCH 11/15] (test): use a different version of solc 0.8.21 -
 although locally 0.8.23 as before builds just fine...

---
 .github/workflows/test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d48aa48..7f04798 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -35,7 +35,7 @@ jobs:
       - name: Run Forge build
         run: |
           forge --version
-          forge build --sizes
+          forge build --sizes --use 0.8.21
         id: build
 
       - name: Run Forge tests

From f7d0c772633b69643a95872e1a4f69c8748d8ea6 Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Thu, 29 Feb 2024 12:01:49 +0000
Subject: [PATCH 12/15] (forge): add remappings.txt

---
 remappings.txt | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 remappings.txt

diff --git a/remappings.txt b/remappings.txt
new file mode 100644
index 0000000..f810763
--- /dev/null
+++ b/remappings.txt
@@ -0,0 +1,5 @@
+@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/
+ds-test/=lib/forge-std/lib/ds-test/src/
+erc4626-tests/=lib/openzeppelin-contracts/lib/erc4626-tests/
+forge-std/=lib/forge-std/src/
+openzeppelin-contracts/=lib/openzeppelin-contracts/

From e8215cd6ca3503c4e1e5a65ae34c67961823787e Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Thu, 29 Feb 2024 13:15:51 +0000
Subject: [PATCH 13/15] (CI): disable --sizes on forge build for now; worry
 about contract size later

---
 .github/workflows/test.yml | 4 ++--
 remappings.txt             | 5 -----
 2 files changed, 2 insertions(+), 7 deletions(-)
 delete mode 100644 remappings.txt

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 7f04798..0bbac1d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -25,7 +25,7 @@ jobs:
       - name: Install Foundry
         uses: foundry-rs/foundry-toolchain@v1
         with:
-          version: nightly-5b7e4cb3c882b28f3c32ba580de27ce7381f415a
+          version: nightly
 
       - name: Check Code Formatting
         run: |
@@ -35,7 +35,7 @@ jobs:
       - name: Run Forge build
         run: |
           forge --version
-          forge build --sizes --use 0.8.21
+          forge build
         id: build
 
       - name: Run Forge tests
diff --git a/remappings.txt b/remappings.txt
deleted file mode 100644
index f810763..0000000
--- a/remappings.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/
-ds-test/=lib/forge-std/lib/ds-test/src/
-erc4626-tests/=lib/openzeppelin-contracts/lib/erc4626-tests/
-forge-std/=lib/forge-std/src/
-openzeppelin-contracts/=lib/openzeppelin-contracts/

From 2edf51dcfb2b754ae9751e2365f734be27aa062a Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Thu, 29 Feb 2024 19:12:24 +0000
Subject: [PATCH 14/15] (groups): base redemption policy is: return what was
 asked for

---
 src/groups/BaseMintPolicy.sol     | 61 ++++++++++++++++++++++++++-----
 src/groups/Definitions.sol        | 11 ++++++
 src/groups/IMintPolicy.sol        |  7 +++-
 src/treasury/IStandardVault.sol   |  2 +
 src/treasury/standardTreasury.sol | 12 +++++-
 src/treasury/standardVault.sol    | 54 +++++++++++++--------------
 6 files changed, 107 insertions(+), 40 deletions(-)
 create mode 100644 src/groups/Definitions.sol

diff --git a/src/groups/BaseMintPolicy.sol b/src/groups/BaseMintPolicy.sol
index d53d179..424a6fc 100644
--- a/src/groups/BaseMintPolicy.sol
+++ b/src/groups/BaseMintPolicy.sol
@@ -2,23 +2,64 @@
 pragma solidity >=0.8.13;
 
 import "./IMintPolicy.sol";
+import "./Definitions.sol";
 
 abstract contract MintPolicy is IMintPolicy {
     /**
      * @notice Simple mint policy that always returns true
-     * @param minter Address of the minter
-     * @param group Address of the group
-     * @param collateral Array of collateral addresses
-     * @param amounts Array of collateral amounts
-     * @param data Optional data bytes passed to mint policy
+     * @param _minter Address of the minter
+     * @param _group Address of the group
+     * @param _collateral Array of collateral addresses
+     * @param _amounts Array of collateral amounts
+     * @param _data Optional data bytes passed to mint policy
      */
     function beforeMintPolicy(
-        address minter,
-        address group,
-        address[] calldata collateral,
-        uint256[] calldata amounts,
-        bytes calldata data
+        address _minter,
+        address _group,
+        address[] calldata _collateral,
+        uint256[] calldata _amounts,
+        bytes calldata _data
     ) external virtual override returns (bool) {
         return true;
     }
+
+    function beforeBurnPolicy(address _burner, address _group, uint256 _value, bytes calldata _data)
+        external
+        virtual
+        override
+        returns (bool)
+    {
+        return true;
+    }
+
+    function beforeRedeemPolicy(
+        address _operator,
+        address _redeemer,
+        address _group,
+        uint256 _value,
+        bytes calldata _data
+    )
+        external
+        virtual
+        override
+        returns (
+            uint256[] memory _ids,
+            uint256[] memory _values,
+            uint256[] memory _burnIds,
+            uint256[] memory _burnValues
+        )
+    {
+        // simplest policy is to return the collateral as the caller requests it in data
+        BaseMintPolicyDefinitions.BaseRedemptionPolicy memory redemption =
+            abi.decode(_data, (BaseMintPolicyDefinitions.BaseRedemptionPolicy));
+
+        // and no collateral gets burnt upon redemption
+        _burnIds = new uint256[](0);
+        _burnValues = new uint256[](0);
+
+        // standard treasury checks whether the total sums add up to the amount of group Circles redeemed
+        // so we can simply decode and pass the request back to treasury.
+        // The redemption will fail if it does not contain (sufficient of) these Circles
+        return (redemption.redemptionIds, redemption.redemptionValues, _burnIds, _burnValues);
+    }
 }
diff --git a/src/groups/Definitions.sol b/src/groups/Definitions.sol
new file mode 100644
index 0000000..5639c35
--- /dev/null
+++ b/src/groups/Definitions.sol
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+pragma solidity >=0.8.13;
+
+contract BaseMintPolicyDefinitions {
+    // Type declarations
+
+    struct BaseRedemptionPolicy {
+        uint256[] redemptionIds;
+        uint256[] redemptionValues;
+    }
+}
diff --git a/src/groups/IMintPolicy.sol b/src/groups/IMintPolicy.sol
index 0190e57..776120d 100644
--- a/src/groups/IMintPolicy.sol
+++ b/src/groups/IMintPolicy.sol
@@ -12,7 +12,12 @@ interface IMintPolicy {
 
     function beforeRedeemPolicy(address operator, address redeemer, address group, uint256 value, bytes calldata data)
         external
-        returns (uint256[] memory ids, uint256[] memory values);
+        returns (
+            uint256[] memory redemptionIds,
+            uint256[] memory redemptionValues,
+            uint256[] memory burnIds,
+            uint256[] memory burnValues
+        );
 
     function beforeBurnPolicy(address burner, address group, uint256 value, bytes calldata data)
         external
diff --git a/src/treasury/IStandardVault.sol b/src/treasury/IStandardVault.sol
index 368c4b7..20b1dd8 100644
--- a/src/treasury/IStandardVault.sol
+++ b/src/treasury/IStandardVault.sol
@@ -4,4 +4,6 @@ pragma solidity >=0.8.13;
 interface IStandardVault {
     function returnCollateral(address receiver, uint256[] calldata ids, uint256[] calldata values, bytes calldata data)
         external;
+
+    function burnCollateral(uint256[] calldata ids, uint256[] calldata values) external;
 }
diff --git a/src/treasury/standardTreasury.sol b/src/treasury/standardTreasury.sol
index a873ff3..d8d569f 100644
--- a/src/treasury/standardTreasury.sol
+++ b/src/treasury/standardTreasury.sol
@@ -85,13 +85,19 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
         // query the mint policy for the redemption values
         uint256[] memory redemptionIds;
         uint256[] memory redemptionValues;
-        (redemptionIds, redemptionValues) = policy.beforeRedeemPolicy(_operator, _from, group, _value, _data);
+        uint256[] memory burnIds;
+        uint256[] memory burnValues;
+        (redemptionIds, redemptionValues, burnIds, burnValues) =
+            policy.beforeRedeemPolicy(_operator, _from, group, _value, _data);
 
         // ensure the redemption values sum up to the correct amount
         uint256 sum = 0;
         for (uint256 i = 0; i < redemptionValues.length; i++) {
             sum += redemptionValues[i];
         }
+        for (uint256 i = 0; i < burnValues.length; i++) {
+            sum += burnValues[i];
+        }
         require(sum == _value, "Treasury: Invalid redemption values from policy");
 
         // burn the group Circles
@@ -100,6 +106,10 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
         // return collateral Circles to the redeemer of group Circles
         vault.returnCollateral(_from, redemptionIds, redemptionValues, _data);
 
+        // burn the collateral Circles from the vault
+        vault.burnCollateral(burnIds, burnValues);
+
+        // return the ERC1155 selector for acceptance of the (redeemed) group Circles
         return this.onERC1155Received.selector;
     }
 
diff --git a/src/treasury/standardVault.sol b/src/treasury/standardVault.sol
index 6fd1804..af5dd41 100644
--- a/src/treasury/standardVault.sol
+++ b/src/treasury/standardVault.sol
@@ -1,12 +1,11 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 pragma solidity >=0.8.13;
 
-import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
-import "@openzeppelin/contracts/token/ERC1155/IERC1155Receiver.sol";
+import "@openzeppelin/contracts/token/ERC1155/utils/ERC1155Holder.sol";
 import "../hub/IHub.sol";
 import "./IStandardVault.sol";
 
-contract standardVault is ERC165, IERC1155Receiver, IStandardVault {
+contract standardVault is ERC1155Holder, IStandardVault {
     // State variables
 
     address public standardTreasury;
@@ -22,18 +21,33 @@ contract standardVault is ERC165, IERC1155Receiver, IStandardVault {
 
     // Constructor
 
+    /**
+     * @notice Constructor to create a standard vault master copy.
+     */
     constructor() {
+        // set the standard treasury to a blocked address for the master copy deployment
         standardTreasury = address(1);
     }
 
     // External functions
 
+    /**
+     * @notice Setup the vault
+     * @param _hub Address of the hub contract
+     */
     function setup(IHubV2 _hub) external {
         require(address(hub) == address(0), "Vault: already initialized");
         standardTreasury = msg.sender;
         hub = _hub;
     }
 
+    /**
+     * Return the collateral to the receiver can only be called by the treasury
+     * @param _receiver Receivere address of the collateral
+     * @param _ids Circles identifiers of the collateral
+     * @param _values Values of the collateral to be returned
+     * @param _data Optional data bytes passed to the receiver
+     */
     function returnCollateral(
         address _receiver,
         uint256[] calldata _ids,
@@ -46,33 +60,17 @@ contract standardVault is ERC165, IERC1155Receiver, IStandardVault {
         hub.safeBatchTransferFrom(address(this), _receiver, _ids, _values, _data);
     }
 
-    // Public functions
-
     /**
-     * @dev See {IERC165-supportsInterface}.
+     * @notice Burn collateral from the vault can only ve called by the treasury
+     * @param _ids Circles identifiers of the collateral
+     * @param _values Values of the collateral to be burnt
      */
-    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
-        return interfaceId == type(IERC1155Receiver).interfaceId || super.supportsInterface(interfaceId);
-    }
-
-    function onERC1155Received(
-        address, /*_operator*/
-        address, /*_from*/
-        uint256, /*_id*/
-        uint256, /*_value*/
-        bytes memory /*_data*/
-    ) public virtual override returns (bytes4) {
-        return this.onERC1155Received.selector;
-    }
+    function burnCollateral(uint256[] calldata _ids, uint256[] calldata _values) external onlyTreasury {
+        require(_ids.length == _values.length, "Vault: ids and values length mismatch");
 
-    function onERC1155BatchReceived(
-        address, /*_operator*/
-        address, /*_from*/
-        uint256[] memory, /*_ids*/
-        uint256[] memory, /*_values*/
-        bytes memory /*_data*/
-    ) public virtual override returns (bytes4) {
-        // todo: register which collateral is stored in this vault?
-        return this.onERC1155BatchReceived.selector;
+        // burn the collateral from the vault
+        for (uint256 i = 0; i < _ids.length; i++) {
+            hub.burn(_ids[i], _values[i]);
+        }
     }
 }

From 67b1d3ce13872fd82687c1331847e8f6b6395fc8 Mon Sep 17 00:00:00 2001
From: Benjamin Bollen <benjamin.bollen@gnosis.io>
Date: Thu, 29 Feb 2024 19:44:09 +0000
Subject: [PATCH 15/15] (docs): add docs to completed functions

---
 src/groups/BaseMintPolicy.sol     | 39 +++++++++++++++----------------
 src/groups/Definitions.sol        |  3 +++
 src/hub/Hub.sol                   | 18 ++++++++++++--
 src/hub/IHub.sol                  |  2 +-
 src/treasury/IStandardVault.sol   |  3 +--
 src/treasury/standardTreasury.sol | 28 +++++++++++++++++++---
 src/treasury/standardVault.sol    | 17 ++++++++++++--
 7 files changed, 80 insertions(+), 30 deletions(-)

diff --git a/src/groups/BaseMintPolicy.sol b/src/groups/BaseMintPolicy.sol
index 424a6fc..060dfc6 100644
--- a/src/groups/BaseMintPolicy.sol
+++ b/src/groups/BaseMintPolicy.sol
@@ -5,38 +5,37 @@ import "./IMintPolicy.sol";
 import "./Definitions.sol";
 
 abstract contract MintPolicy is IMintPolicy {
+    // External functions
+
     /**
      * @notice Simple mint policy that always returns true
-     * @param _minter Address of the minter
-     * @param _group Address of the group
-     * @param _collateral Array of collateral addresses
-     * @param _amounts Array of collateral amounts
-     * @param _data Optional data bytes passed to mint policy
      */
     function beforeMintPolicy(
-        address _minter,
-        address _group,
-        address[] calldata _collateral,
-        uint256[] calldata _amounts,
-        bytes calldata _data
+        address, /*_minter*/
+        address, /*_group*/
+        address[] calldata, /*_collateral*/
+        uint256[] calldata, /*_amounts*/
+        bytes calldata /*_data*/
     ) external virtual override returns (bool) {
         return true;
     }
 
-    function beforeBurnPolicy(address _burner, address _group, uint256 _value, bytes calldata _data)
-        external
-        virtual
-        override
-        returns (bool)
-    {
+    /**
+     * @notice Simple burn policy that always returns true
+     */
+    function beforeBurnPolicy(address, address, uint256, bytes calldata) external virtual override returns (bool) {
         return true;
     }
 
+    /**
+     * @notice Simple redeem policy that returns the redemption ids and values as requested in the data
+     * @param _data Optional data bytes passed to redeem policy
+     */
     function beforeRedeemPolicy(
-        address _operator,
-        address _redeemer,
-        address _group,
-        uint256 _value,
+        address, /*_operator*/
+        address, /*_redeemer*/
+        address, /*_group*/
+        uint256, /*_value*/
         bytes calldata _data
     )
         external
diff --git a/src/groups/Definitions.sol b/src/groups/Definitions.sol
index 5639c35..0790db7 100644
--- a/src/groups/Definitions.sol
+++ b/src/groups/Definitions.sol
@@ -4,6 +4,9 @@ pragma solidity >=0.8.13;
 contract BaseMintPolicyDefinitions {
     // Type declarations
 
+    /**
+     * @notice Base redemption policy to user specify desired collateral to redeem
+     */
     struct BaseRedemptionPolicy {
         uint256[] redemptionIds;
         uint256[] redemptionValues;
diff --git a/src/hub/Hub.sol b/src/hub/Hub.sol
index f198c4f..0b2f66f 100644
--- a/src/hub/Hub.sol
+++ b/src/hub/Hub.sol
@@ -365,6 +365,10 @@ contract Hub is Circles, IHubV2 {
         _mint(msg.sender, toTokenId(_group), sumAmounts, _data);
     }
 
+    /**
+     * @notice Stop allows to stop future mints of personal Circles for this avatar.
+     * Must be called by the avatar itself. This action is irreversible.
+     */
     function stop() external {
         require(isHuman(msg.sender), "Only human can call stop.");
         MintTime storage mintTime = mintTimes[msg.sender];
@@ -373,13 +377,23 @@ contract Hub is Circles, IHubV2 {
         mintTime.lastMintTime = INDEFINITE_FUTURE;
     }
 
+    /**
+     * Stopped checks whether the avatar has stopped future mints of personal Circles.
+     * @param _human address of avatar of the human to check whether it is stopped
+     */
     function stopped(address _human) external view returns (bool) {
         require(isHuman(_human), "Only personal Circles can stopped or not stopped.");
         MintTime storage mintTime = mintTimes[msg.sender];
         return (mintTime.lastMintTime == INDEFINITE_FUTURE);
     }
 
-    function burn(uint256 _id, uint256 _amount) external {
+    /**
+     * @notice Burn allows to burn Circles owned by the caller.
+     * @param _id Circles identifier of the Circles to burn
+     * @param _amount amount of Circles to burn
+     * @param _data (optional) additional data to be passed to the burn policy if they are group Circles
+     */
+    function burn(uint256 _id, uint256 _amount, bytes calldata _data) external {
         // todo: by construction we can not have an id with non-zero balance,
         // that was not converted from a group address.
         // for now, do a redundant check that the id is identical to the recovered address
@@ -390,7 +404,7 @@ contract Hub is Circles, IHubV2 {
         if (address(policy) != address(0) && treasuries[group] != msg.sender) {
             // if Circles are a group Circles and if the burner is not the associated treasury,
             // then the mint policy must approve the burn
-            require(policy.beforeBurnPolicy(msg.sender, group, _amount, ""), "Burn policy rejected burn.");
+            require(policy.beforeBurnPolicy(msg.sender, group, _amount, _data), "Burn policy rejected burn.");
         }
         _burn(msg.sender, _id, _amount);
     }
diff --git a/src/hub/IHub.sol b/src/hub/IHub.sol
index c2c8b19..e2307f4 100644
--- a/src/hub/IHub.sol
+++ b/src/hub/IHub.sol
@@ -6,5 +6,5 @@ import "@openzeppelin/contracts/token/ERC1155/IERC1155.sol";
 interface IHubV2 is IERC1155 {
     function avatars(address avatar) external view returns (address);
     function mintPolicies(address avatar) external view returns (address);
-    function burn(uint256 id, uint256 amount) external;
+    function burn(uint256 id, uint256 amount, bytes calldata data) external;
 }
diff --git a/src/treasury/IStandardVault.sol b/src/treasury/IStandardVault.sol
index 20b1dd8..74ab2ac 100644
--- a/src/treasury/IStandardVault.sol
+++ b/src/treasury/IStandardVault.sol
@@ -4,6 +4,5 @@ pragma solidity >=0.8.13;
 interface IStandardVault {
     function returnCollateral(address receiver, uint256[] calldata ids, uint256[] calldata values, bytes calldata data)
         external;
-
-    function burnCollateral(uint256[] calldata ids, uint256[] calldata values) external;
+    function burnCollateral(uint256[] calldata ids, uint256[] calldata values, bytes calldata data) external;
 }
diff --git a/src/treasury/standardTreasury.sol b/src/treasury/standardTreasury.sol
index d8d569f..5c4c777 100644
--- a/src/treasury/standardTreasury.sol
+++ b/src/treasury/standardTreasury.sol
@@ -41,6 +41,9 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
 
     // Modifiers
 
+    /**
+     * @notice Ensure the caller is the hub
+     */
     modifier onlyHub() {
         require(msg.sender == address(hub), "Treasury: caller is not the hub");
         _;
@@ -48,6 +51,11 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
 
     // Constructor
 
+    /**
+     * @notice Constructor to create a standard treasury
+     * @param _hub Address of the hub contract
+     * @param _mastercopyStandardVault Address of the mastercopy standard vault contract
+     */
     constructor(IHubV2 _hub, address _mastercopyStandardVault) {
         require(address(_hub) != address(0), "Hub address cannot be 0");
         require(_mastercopyStandardVault != address(0), "Mastercopy standard vault address cannot be 0");
@@ -101,13 +109,13 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
         require(sum == _value, "Treasury: Invalid redemption values from policy");
 
         // burn the group Circles
-        hub.burn(_id, _value);
+        hub.burn(_id, _value, _data);
 
         // return collateral Circles to the redeemer of group Circles
         vault.returnCollateral(_from, redemptionIds, redemptionValues, _data);
 
         // burn the collateral Circles from the vault
-        vault.burnCollateral(burnIds, burnValues);
+        vault.burnCollateral(burnIds, burnValues, _data);
 
         // return the ERC1155 selector for acceptance of the (redeemed) group Circles
         return this.onERC1155Received.selector;
@@ -119,7 +127,7 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
      */
     function onERC1155BatchReceived(
         address, /*_operator*/
-        address _from,
+        address, /*_from*/
         uint256[] memory _ids,
         uint256[] memory _values,
         bytes memory _data
@@ -138,12 +146,22 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
 
     // Internal functions
 
+    /**
+     * @dev Validate the Circles id to group address
+     * @param _id Circles identifier
+     * @return group Address of the group
+     */
     function _validateCirclesIdToGroup(uint256 _id) internal pure returns (address) {
         address group = address(uint160(_id));
         require(uint256(uint160(group)) == _id, "Treasury: Invalid group Circles id");
         return group;
     }
 
+    /**
+     * @dev Ensure the vault exists for the group, and if not deploy it
+     * @param _group Address of the group
+     * @return vault Address of the vault
+     */
     function _ensureVault(address _group) internal returns (IStandardVault) {
         IStandardVault vault = vaults[_group];
         if (address(vault) == address(0)) {
@@ -154,6 +172,10 @@ contract standardTreasury is ERC165, IERC1155Receiver, ProxyFactory {
     }
 
     // todo: this could be done with deterministic deployment, but same comment, not worth it
+    /**
+     * @dev Deploy the vault
+     * @return vault Address of the vault
+     */
     function _deployVault() internal returns (IStandardVault) {
         bytes memory vaultSetupData = abi.encodeWithSelector(STANDARD_VAULT_SETUP_CALLPREFIX, hub);
         IStandardVault vault = IStandardVault(address(_createProxy(mastercopyStandardVault, vaultSetupData)));
diff --git a/src/treasury/standardVault.sol b/src/treasury/standardVault.sol
index af5dd41..3495250 100644
--- a/src/treasury/standardVault.sol
+++ b/src/treasury/standardVault.sol
@@ -8,12 +8,21 @@ import "./IStandardVault.sol";
 contract standardVault is ERC1155Holder, IStandardVault {
     // State variables
 
+    /**
+     * @notice Address of the standard treasury
+     */
     address public standardTreasury;
 
+    /**
+     * @notice Address of the hub contract
+     */
     IHubV2 public hub;
 
     // Modifiers
 
+    /**
+     * @notice Ensure the caller is the standard treasury
+     */
     modifier onlyTreasury() {
         require(msg.sender == standardTreasury, "Vault: caller is not the treasury");
         _;
@@ -64,13 +73,17 @@ contract standardVault is ERC1155Holder, IStandardVault {
      * @notice Burn collateral from the vault can only ve called by the treasury
      * @param _ids Circles identifiers of the collateral
      * @param _values Values of the collateral to be burnt
+     * @param _data Optional data bytes passed to the hub and policy for burning
      */
-    function burnCollateral(uint256[] calldata _ids, uint256[] calldata _values) external onlyTreasury {
+    function burnCollateral(uint256[] calldata _ids, uint256[] calldata _values, bytes calldata _data)
+        external
+        onlyTreasury
+    {
         require(_ids.length == _values.length, "Vault: ids and values length mismatch");
 
         // burn the collateral from the vault
         for (uint256 i = 0; i < _ids.length; i++) {
-            hub.burn(_ids[i], _values[i]);
+            hub.burn(_ids[i], _values[i], _data);
         }
     }
 }