diff --git a/src/interfaceDetection/ERC165/ERC165Facet.sol b/src/interfaceDetection/ERC165/ERC165Facet.sol
new file mode 100644
index 00000000..74e9025e
--- /dev/null
+++ b/src/interfaceDetection/ERC165/ERC165Facet.sol
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.8.30;
+
+/// @title ERC-165 Standard Interface Detection Interface
+/// @notice Interface for detecting what interfaces a contract implements
+/// @dev ERC-165 allows contracts to publish their supported interfaces
+interface IERC165 {
+    /// @notice Query if a contract implements an interface
+    /// @param _interfaceId The interface identifier, as specified in ERC-165
+    /// @dev Interface identification is specified in ERC-165. This function
+    /// uses less than 30,000 gas.
+    /// @return `true` if the contract implements `_interfaceId` and
+    /// `_interfaceId` is not 0xffffffff, `false` otherwise
+    function supportsInterface(bytes4 _interfaceId) external view returns (bool);
+}
+
+/// @title ERC165Facet — ERC-165 Standard Interface Detection Facet
+/// @notice Facet implementation of ERC-165 for diamond proxy pattern
+/// @dev Allows querying which interfaces are implemented by the diamond
+/// Each facet is a standalone source code file following SCOP principles.
+contract ERC165Facet {
+    /// @notice Storage slot identifier for ERC-165 interface detection
+    /// @dev Defined using keccak256 hash following ERC-8042 standard
+    bytes32 constant STORAGE_POSITION = keccak256("compose.erc165");
+
+    /// @notice ERC-165 storage layout using the ERC-8042 standard
+    /// @custom:storage-location erc8042:compose.erc165
+    struct ERC165Storage {
+        /// @notice Mapping of interface IDs to whether they are supported
+        mapping(bytes4 => bool) supportedInterfaces;
+    }
+
+    /// @notice Returns a pointer to the ERC-165 storage struct
+    /// @dev Uses inline assembly to bind the storage struct to the fixed storage position
+    /// @return s The ERC-165 storage struct
+    function getStorage() internal pure returns (ERC165Storage storage s) {
+        bytes32 position = STORAGE_POSITION;
+        assembly {
+            s.slot := position
+        }
+    }
+
+    /// @notice Query if a contract implements an interface
+    /// @param _interfaceId The interface identifier, as specified in ERC-165
+    /// @dev This function checks if the diamond supports the given interface ID
+    /// @return `true` if the contract implements `_interfaceId` and
+    /// `_interfaceId` is not 0xffffffff, `false` otherwise
+    function supportsInterface(bytes4 _interfaceId) external view returns (bool) {
+        ERC165Storage storage s = getStorage();
+
+        // If the ERC165 interface itself is being queried, return true
+        // since this facet implements ERC165
+        if (_interfaceId == type(IERC165).interfaceId) {
+            return true;
+        }
+
+        return s.supportedInterfaces[_interfaceId];
+    }
+}
diff --git a/src/interfaceDetection/ERC165/LibERC165.sol b/src/interfaceDetection/ERC165/LibERC165.sol
new file mode 100644
index 00000000..54fb1ced
--- /dev/null
+++ b/src/interfaceDetection/ERC165/LibERC165.sol
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.8.30;
+
+/// @title LibERC165 — ERC-165 Standard Interface Detection Library
+/// @notice Provides internal functions and storage layout for ERC-165 interface detection.
+/// @dev Uses ERC-8042 for storage location standardization
+library LibERC165 {
+    /// @notice Storage slot identifier, defined using keccak256 hash of the library diamond storage identifier.
+    bytes32 constant STORAGE_POSITION = keccak256("compose.erc165");
+
+    /// @notice ERC-165 storage layout using the ERC-8042 standard.
+    /// @custom:storage-location erc8042:compose.erc165
+    struct ERC165Storage {
+        /// @notice Mapping of interface IDs to whether they are supported
+        mapping(bytes4 => bool) supportedInterfaces;
+    }
+
+    /// @notice Returns a pointer to the ERC-165 storage struct.
+    /// @dev Uses inline assembly to bind the storage struct to the fixed storage position.
+    /// @return s The ERC-165 storage struct.
+    function getStorage() internal pure returns (ERC165Storage storage s) {
+        bytes32 position = STORAGE_POSITION;
+        assembly {
+            s.slot := position
+        }
+    }
+
+    /// @notice Register that a contract supports an interface
+    /// @param _interfaceId The interface ID to register
+    /// @dev Call this function during initialization to register supported interfaces.
+    /// For example, in an ERC721 facet initialization, you would call:
+    /// `LibERC165.registerInterface(type(IERC721).interfaceId)`
+    function registerInterface(bytes4 _interfaceId) internal {
+        ERC165Storage storage s = getStorage();
+        s.supportedInterfaces[_interfaceId] = true;
+    }
+}