create OptimistConstants library

packages/contracts-periphery/contracts/foundry-tests/OptimistInviter.t.sol

@@ -9,6 +9,7 @@ import { Optimist } from "../universal/op-nft/Optimist.sol";
 import { Strings } from "@openzeppelin/contracts/utils/Strings.sol";
 import { TestERC1271Wallet } from "../testing/helpers/TestERC1271Wallet.sol";
 import { OptimistInviterHelper } from "../testing/helpers/OptimistInviterHelper.sol";
+import { OptimistConstants } from "../universal/op-nft/libraries/OptimistConstants.sol";
 
 contract OptimistInviter_Initializer is Test {
     event InviteClaimed(address indexed issuer, address indexed claimer);
@@ -101,7 +102,7 @@ contract OptimistInviter_Initializer is Test {
         bytes memory attestation = attestationStation.attestations(
             address(optimistInviter),
             _claimer,
-            optimistInviter.CAN_MINT_FROM_INVITE_ATTESTATION_KEY()
+            OptimistConstants.OPTIMIST_CAN_MINT_FROM_INVITE_ATTESTATION_KEY
         );
         return attestation.length > 0;
     }
@@ -212,7 +213,7 @@ contract OptimistInviter_Initializer is Test {
         emit AttestationCreated(
             address(optimistInviter),
             _claimer,
-            optimistInviter.CAN_MINT_FROM_INVITE_ATTESTATION_KEY(),
+            OptimistConstants.OPTIMIST_CAN_MINT_FROM_INVITE_ATTESTATION_KEY,
             abi.encode(issuer)
         );
 
@@ -394,7 +395,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         emit AttestationCreated(
             address(optimistInviter),
             sally,
-            optimistInviter.CAN_MINT_FROM_INVITE_ATTESTATION_KEY(),
+            OptimistConstants.OPTIMIST_CAN_MINT_FROM_INVITE_ATTESTATION_KEY,
             abi.encode(bob)
         );
 
@@ -550,7 +551,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         emit AttestationCreated(
             address(optimistInviter),
             sally,
-            optimistInviter.CAN_MINT_FROM_INVITE_ATTESTATION_KEY(),
+            OptimistConstants.OPTIMIST_CAN_MINT_FROM_INVITE_ATTESTATION_KEY,
             abi.encode(address(carolERC1271Wallet))
         );
 

packages/contracts-periphery/contracts/universal/op-nft/OptimistInviter.sol

 // SPDX-License-Identifier: MIT
 pragma solidity 0.8.15;
 
+import { OptimistConstants } from "./libraries/OptimistConstants.sol";
 import { Semver } from "@eth-optimism/contracts-bedrock/contracts/universal/Semver.sol";
 import { AttestationStation } from "./AttestationStation.sol";
 import { SignatureChecker } from "@openzeppelin/contracts/utils/cryptography/SignatureChecker.sol";
@@ -63,12 +64,6 @@ contract OptimistInviter is Semver, EIP712Upgradeable {
      */
     bytes32 public constant CAN_INVITE_ATTESTATION_KEY = bytes32("optimist.can-invite");
 
-    /**
-     * @notice Attestation key allowing the attested account to mint.
-     */
-    bytes32 public constant CAN_MINT_FROM_INVITE_ATTESTATION_KEY =
-        bytes32("optimist.can-mint-from-invite");
-
     /**
      * @notice Granter who can set accounts' invite counts.
      */
@@ -297,7 +292,7 @@ contract OptimistInviter is Semver, EIP712Upgradeable {
         // The invite issuer is included in the data of the attestation.
         ATTESTATION_STATION.attest(
             _claimer,
-            CAN_MINT_FROM_INVITE_ATTESTATION_KEY,
+            OptimistConstants.OPTIMIST_CAN_MINT_FROM_INVITE_ATTESTATION_KEY,
             abi.encode(_claimableInvite.issuer)
         );
 

packages/contracts-periphery/contracts/universal/op-nft/libraries/OptimistConstants.sol

+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.15;
+
+/**
+ * @title  OptimistConstants
+ * @notice Library for storing constants related to the Optimist NFT shared in multiple contracts.
+ */
+
+library OptimistConstants {
+    /**
+     * @notice Attestation key issued by OptimistInviter allowing the attested account to mint.
+     */
+    bytes32 internal constant OPTIMIST_CAN_MINT_FROM_INVITE_ATTESTATION_KEY =
+        bytes32("optimist.can-mint-from-invite");
+}