Payer contract implementation

contracts/script/ComputeStorageSlot.sol

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.28;
+
+import {Script, console} from "forge-std/src/Script.sol";
+
+/*
+ * @dev   Compute the storage slot for a given namespace.
+ *        forge script script/ComputeStorageSlot.sol --sig "compute(string)" "xmtp.storage.Payer"
+ */
+contract ComputeStorageSlot is Script {
+    function compute(string calldata namespace) external view {
+        bytes32 namespaceHash = keccak256(bytes(namespace));
+        uint256 namespaceInt = uint256(namespaceHash);
+        bytes32 slot = bytes32((namespaceInt - 1) & ~uint256(0xff));
+
+        console.log("Namespace:", namespace);
+        console.logBytes32(namespaceHash);
+        console.log("Storage Slot:");
+        console.logBytes32(slot);
+    }
+
+    function run() external view {
+        this.compute("");
+    }
+}

contracts/src/Nodes.sol

@@ -364,14 +364,14 @@ contract Nodes is INodes, AccessControlDefaultAdminRules, ERC721 {
         emit ReplicationDisabled(nodeId);
     }
 
-    /// @dev Override to support ERC721, IERC165, and AccessControlEnumerable.
+    /// @dev Override to support INodes, ERC721, IERC165, and AccessControlEnumerable.
     function supportsInterface(bytes4 interfaceId)
         public
         view
         override(ERC721, IERC165, AccessControlDefaultAdminRules)
         returns (bool supported)
     {
-        return super.supportsInterface(interfaceId);
+        return interfaceId == type(INodes).interfaceId || super.supportsInterface(interfaceId);
     }
 
     /// @dev Reverts if the node does not exist.