add interface for IERC1155Metadata

src/OptionSettlement.sol

@@ -26,7 +26,7 @@ import "solmate/utils/SafeTransferLib.sol";
 
 // @notice This settlement protocol does not support rebase tokens, or fee on transfer tokens
 
-contract OptionSettlementEngine is IOptionSettlementEngine, ERC1155 {
+contract OptionSettlementEngine is ERC1155, IOptionSettlementEngine {
     // The protocol fee
     uint8 public immutable feeBps = 5;
 

src/interfaces/IERC1155Metadata.sol

@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "./IERC165.sol";
+
+/**
+ * @dev Required interface of an ERC1155 compliant contract, as defined in the
+ * https://eips.ethereum.org/EIPS/eip-1155[EIP].
+ *
+ * _Available since v3.1._
+ */
+interface IERC1155Metadata is IERC165 {
+    /**
+     * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
+     */
+    event TransferSingle(
+        address indexed operator,
+        address indexed from,
+        address indexed to,
+        uint256 id,
+        uint256 value
+    );
+
+    /**
+     * @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
+     * transfers.
+     */
+    event TransferBatch(
+        address indexed operator,
+        address indexed from,
+        address indexed to,
+        uint256[] ids,
+        uint256[] values
+    );
+
+    /**
+     * @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
+     * `approved`.
+     */
+    event ApprovalForAll(
+        address indexed account,
+        address indexed operator,
+        bool approved
+    );
+
+    /**
+     * @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
+     *
+     * If an {URI} event was emitted for `id`, the standard
+     * https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
+     * returned by {IERC1155MetadataURI-uri}.
+     */
+    event URI(string value, uint256 indexed id);
+
+    /**
+     * @dev Returns the amount of tokens of token type `id` owned by `account`.
+     *
+     * Requirements:
+     *
+     * - `account` cannot be the zero address.
+     */
+    function balanceOf(address account, uint256 id)
+        external
+        view
+        returns (uint256);
+
+    /**
+     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
+     *
+     * Requirements:
+     *
+     * - `accounts` and `ids` must have the same length.
+     */
+    function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids)
+        external
+        view
+        returns (uint256[] memory);
+
+    /**
+     * @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
+     *
+     * Emits an {ApprovalForAll} event.
+     *
+     * Requirements:
+     *
+     * - `operator` cannot be the caller.
+     */
+    function setApprovalForAll(address operator, bool approved) external;
+
+    /**
+     * @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
+     *
+     * See {setApprovalForAll}.
+     */
+    function isApprovedForAll(address account, address operator)
+        external
+        view
+        returns (bool);
+
+    /**
+     * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
+     *
+     * Emits a {TransferSingle} event.
+     *
+     * Requirements:
+     *
+     * - `to` cannot be the zero address.
+     * - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
+     * - `from` must have a balance of tokens of type `id` of at least `amount`.
+     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
+     * acceptance magic value.
+     */
+    function safeTransferFrom(
+        address from,
+        address to,
+        uint256 id,
+        uint256 amount,
+        bytes calldata data
+    ) external;
+
+    /**
+     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
+     *
+     * Emits a {TransferBatch} event.
+     *
+     * Requirements:
+     *
+     * - `ids` and `amounts` must have the same length.
+     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
+     * acceptance magic value.
+     */
+    function safeBatchTransferFrom(
+        address from,
+        address to,
+        uint256[] calldata ids,
+        uint256[] calldata amounts,
+        bytes calldata data
+    ) external;
+
+    function uri(uint256 id) external view returns (string memory);
+}

src/interfaces/IERC165.sol

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev Interface of the ERC165 standard, as defined in the
+ * https://eips.ethereum.org/EIPS/eip-165[EIP].
+ *
+ * Implementers can declare support of contract interfaces, which can then be
+ * queried by others ({ERC165Checker}).
+ *
+ * For an implementation, see {ERC165}.
+ */
+interface IERC165 {
+    /**
+     * @dev Returns true if this contract implements the interface defined by
+     * `interfaceId`. See the corresponding
+     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
+     * to learn more about how these ids are created.
+     *
+     * This function call must use less than 30 000 gas.
+     */
+    function supportsInterface(bytes4 interfaceId) external view returns (bool);
+}

src/interfaces/IOptionSettlementEngine.sol

@@ -1,6 +1,9 @@
 // SPDX-License-Identifier: BUSL 1.1
-pragma solidity 0.8.11;
+pragma solidity ^0.8.0;
 
+import "./IERC1155Metadata.sol";
+
+// TODO(The engine is IERC1155Metadata, but the solmate impl is not compatible with interface, re-implement)
 // @author 0xAlcibiades
 interface IOptionSettlementEngine {
     event FeeSwept(