requires msg.sender own M3ter to deposit, mint, withdraw or redeem.

src/Solaxy.sol

@@ -4,6 +4,7 @@ pragma solidity ^0.8.19;
 import "./XRC20.sol";
 import "./interfaces/ISolaxy.sol";
 import {UD60x18, ud60x18} from "@prb/[email protected]/src/UD60x18.sol";
+import {IERC721} from "@openzeppelin/[email protected]/interfaces/IERC721.sol";
 
 /**
  * @title Solaxy
@@ -15,6 +16,7 @@ contract Solaxy is XRC20, ISolaxy {
     UD60x18 public constant slope = UD60x18.wrap(0.0025e18);
     UD60x18 public constant halfSlope = UD60x18.wrap(0.00125e18);
     ERC20 public constant DAI = ERC20(0x1CbAd85Aa66Ff3C12dc84C5881886EEB29C1bb9b);
+    IERC721 public constant M3ter = IERC721(0x36c042bad25f24c4Ad5391Bf52b1eA9ec811A9D3); // TODO: M3ter Address
 
     /**
      * @dev Constructs the Solaxy contract, initializing the DAI token and the fee address.
@@ -37,6 +39,7 @@ contract Solaxy is XRC20, ISolaxy {
      * @dev See {IERC4626-deposit}.
      */
     function deposit(uint256 assets, address receiver) external returns (uint256 shares) {
+        if (M3ter.balanceOf(msg.sender) < 1) revert RequiresM3ter();
         shares = computeDeposit(assets, totalSupply());
         _deposit(receiver, assets, shares);
     }
@@ -45,6 +48,7 @@ contract Solaxy is XRC20, ISolaxy {
      * @dev See {IERC4626-withdraw}.
      */
     function withdraw(uint256 assets, address receiver, address owner) external returns (uint256 shares) {
+        if (M3ter.balanceOf(msg.sender) < 1) revert RequiresM3ter();
         uint256 fee;
         (shares, fee) = computeWithdraw(assets, totalSupply());
         _withdraw(receiver, owner, assets, shares, fee);
@@ -54,6 +58,7 @@ contract Solaxy is XRC20, ISolaxy {
      * @dev See {IERC4626-mint}.
      */
     function mint(uint256 shares, address receiver) external returns (uint256 assets) {
+        if (M3ter.balanceOf(msg.sender) < 1) revert RequiresM3ter();
         assets = computeMint(shares, totalSupply());
         _deposit(receiver, assets, shares);
     }
@@ -62,6 +67,7 @@ contract Solaxy is XRC20, ISolaxy {
      * @dev See {IERC4626-redeem}.
      */
     function redeem(uint256 shares, address receiver, address owner) external returns (uint256 assets) {
+        if (M3ter.balanceOf(msg.sender) < 1) revert RequiresM3ter();
         uint256 fee;
         (shares, assets, fee) = computeRedeem(shares, totalSupply());
         _withdraw(receiver, owner, assets, shares, fee);
@@ -72,6 +78,7 @@ contract Solaxy is XRC20, ISolaxy {
      * @param minSharesOut The minimum number of shares the sender expects to receive.
      */
     function safeDeposit(uint256 assets, address receiver, uint256 minSharesOut) external returns (uint256 shares) {
+        if (M3ter.balanceOf(msg.sender) < 1) revert RequiresM3ter();
         shares = computeDeposit(assets, totalSupply());
         if (shares < minSharesOut) revert SlippageError();
         _deposit(receiver, assets, shares);
@@ -85,6 +92,7 @@ contract Solaxy is XRC20, ISolaxy {
         external
         returns (uint256 shares)
     {
+        if (M3ter.balanceOf(msg.sender) < 1) revert RequiresM3ter();
         uint256 fee;
         (shares, fee) = computeWithdraw(assets, totalSupply());
         if (shares > maxSharesIn) revert SlippageError();
@@ -96,6 +104,7 @@ contract Solaxy is XRC20, ISolaxy {
      * @param maxAssetsIn The maximum amount of assets the sender is willing to deposit.
      */
     function safeMint(uint256 shares, address receiver, uint256 maxAssetsIn) external returns (uint256 assets) {
+        if (M3ter.balanceOf(msg.sender) < 1) revert RequiresM3ter();
         assets = computeMint(shares, totalSupply());
         if (assets > maxAssetsIn) revert SlippageError();
         _deposit(receiver, assets, shares);
@@ -109,6 +118,7 @@ contract Solaxy is XRC20, ISolaxy {
         external
         returns (uint256 assets)
     {
+        if (M3ter.balanceOf(msg.sender) < 1) revert RequiresM3ter();
         uint256 fee;
         (shares, assets, fee) = computeRedeem(shares, totalSupply());
         if (assets < minAssetsOut) revert SlippageError();

src/interfaces/ISolaxy.sol

@@ -9,6 +9,7 @@ error Undersupply();
 error CannotBeZero();
 error SlippageError();
 error TransferError();
+error RequiresM3ter();
 
 interface ISolaxy is IERC4626 {
     function safeDeposit(uint256 assets, address receiver, uint256 minSharesOut) external returns (uint256 shares);

test/Solaxy.t.sol

@@ -5,13 +5,16 @@ import {Test} from "forge-std/Test.sol";
 import {Solaxy} from "../src/Solaxy.sol";
 import {PayableErr} from "../src/interfaces/ISolaxy.sol";
 import {IERC20} from "@openzeppelin/[email protected]/interfaces/IERC20.sol";
+import {IERC721} from "@openzeppelin/[email protected]/interfaces/IERC721.sol";
 
 contract SolaxyTest is Test {
     Solaxy public slx;
     IERC20 public dai;
+    IERC721 public m3ter;
     address public here;
     address public slxAddress;
     address public daiAddress;
+    address public m3terAddress;
     uint256 public constant slxAmountIn = 6.795e18;
     uint256 public constant slxAmountMinted = 10e18;
     uint256 public constant slxAmountBurned = 5e18;
@@ -29,9 +32,12 @@ contract SolaxyTest is Test {
 
         daiAddress = slx.asset();
         dai = IERC20(daiAddress);
-
         deal(daiAddress, here, oneMillionDaiBalance, true);
         dai.approve(slxAddress, oneMillionDaiBalance);
+
+        m3ter = IERC721(0x36c042bad25f24c4Ad5391Bf52b1eA9ec811A9D3);
+        m3terAddress = address(m3ter);
+        dealERC721(m3terAddress, here, 1);
     }
 
     function testInitialBalanceWithNewSolaxyContract() public {