The Secret to Web3 Growth: Erasing the #1 Onboarding Killer!

Are You Losing Users Before They Even Start?

Let me ask you something… Have you poured your heart and soul into building an amazing decentralized application (dApp), only to watch potential users vanish the moment they face the dreaded “Connect Wallet & Get Gas” wall?

You know the one. That confusing, frustrating roadblock where users have to:

• Figure out what a “wallet” even is and install one (MetaMask? Phantom? Argh!).
• Navigate the treacherous waters of buying crypto on an exchange (KYC? Fees? Waiting?!).
• Transfer just the right amount of native tokens (like ETH) to pay for something called “gas”… before they can even do anything cool in your app!

Sound familiar? This isn’t just a little friction. This is the #1 reason Web3 struggles with mainstream adoption. It’s the conversion killer silently sabotaging your growth, turning excited prospects into frustrated drop-offs. It’s like building the world’s greatest theme park but making people solve a calculus problem just to buy a ticket!

But what if you could make all that pain disappear?

What if you could onboard users as smoothly, as instantly, as the best Web2 apps? Imagine users diving straight into your dApp’s core value, experiencing the magic without the wallet-and-gas headache.

That’s the secret we’re unlocking today.

This isn’t just another technical tutorial. This is your playbook for creating seamless, gasless onboarding experiences. We’ll take a simple, real-world scenario – giving users 100 free Platform Credits (CRED) just for signing up, which they can use to buy cool NFTs or access premium features – and dissect why the standard Web3 way makes even this simple “try before you buy” model painful. Then, step-by-step, we’ll reveal the expert patterns (from clever off-chain signatures to the power of Account Abstraction) that transform that clunky process into a smooth, invisible flow.

Who is this for?

• The Visionary Beginner: You see the potential of Web3 but are baffled by the onboarding nightmare. You need the foundational secrets to build apps people actually use.
• The Savvy Developer: You know the basics, but you’re ready for the advanced strategies – meta-transactions, ERC-2612 permits, the game-changing ERC-4337 Account Abstraction, and even a peek at the future with EIP-7702. You want the tactical edge.

Our Mission: We start with a user signing up (maybe just with an email) and instantly receiving 100 free PlatformCredits (CRED). They want to use these credits to buy an NFT from our MyNFT contract or unlock a special community channel. Sounds simple, right? Let’s expose the hidden complexities of the “standard” Web3 flow that prevent this, and then embark on a journey to eliminate them, one powerful technique at a time.

Ready to turn those onboarding hurdles into highways? Let’s dive in!

1. The Gauntlet: Why the “Standard” Web3 Flow Scares Users Away

Alright, let’s walk through the “normal” way someone might try to use their free 100 Platform Credits (CRED) to buy our NFT today. Brace yourself – this is the bumpy ride we’re about to pave over.

Imagine Sarah signs up for your awesome platform with just her email and instantly sees “100 Free Credits Added!” in her account. Fantastic! But wait… these credits are on the blockchain (as CRED tokens). To actually use them, she needs a wallet.

1. The Wallet Ritual (To Use the Credits): First hurdle? “Install MetaMask to use your credits.” Sarah navigates browser extensions, installs the wallet, nervously writes down a secret phrase she barely understands, hoping she doesn’t lose it or get hacked. The platform magically associates her email signup with this new wallet address, and the 100 CRED tokens appear. Friction Point #1: Technical setup & security anxiety just to access the free credits.
2. The Excitement… and the Wall: Awesome! Sarah now sees her 100 CRED in her wallet. She browses your NFT marketplace, finds one she likes for 100 credits, and clicks “Buy NFT”… and BAM! “Insufficient funds for gas.” Gas? She needs ETH? But she only has CRED tokens! Friction Point #2: The Gas Trap - Having the required platform credits isn’t enough.
3. The “Easy” On-Ramp Quest?: “Aha!” thinks the dApp developer, “We’ll add an on-ramp!” So, Sarah sees a button: “Buy ETH with Card”. Seems easier, right? She clicks it. Now she faces:
   • On-Ramp KYC: Depending on the provider (like Wyre, MoonPay, Onramper) and amount, she might still need KYC. Upload ID? Selfie? Ugh.
   • Minimum Purchase Madness: The real kicker – she only needs maybe $0.50 worth of ETH for gas, but the on-ramp forces her to buy a minimum of $50 or $100! She has to spend significant money just to facilitate a tiny network fee for using the token she already owns.
   • Fees & Spread: Credit card fees, network fees, provider spreads… that $50 purchase might only yield $45 worth of ETH in her wallet.
   • Waiting (Again): Card processing, fraud checks, blockchain confirmation… it’s faster than an exchange withdrawal, but still not instant.
   • Friction Point #3: On-ramps force over-purchase, add steps, and highlight the absurdity of needing ETH just for gas.
4. The Connection Dance: Assuming she grits her teeth and buys the oversized chunk of ETH, Sarah returns to your NFT site. “Connect Wallet.” Click. Pop-up. “Allow this site to see your address?” Click. Okay, connected again. Minor friction, but still a step.
5. “Approve” What Now?: Sarah clicks “Buy NFT”. But wait! Another pop-up. “Grant permission for the NFT contract to access your PlatformCredits?” Huh? She has to sign a transaction, using a fraction of the ETH she was forced to overbuy, just to allow the purchase later. Click. Wait for the blockchain… Friction Point #4: Confusing ‘approve’ step, requires ETH gas (even if overpaid for).
6. The Actual Purchase: FINALLY! The approve transaction is confirmed. Sarah clicks “Buy NFT” again. Another pop-up. Sign another transaction. Use more of that expensive ETH for gas again! Click. Wait for the blockchain… Success? Maybe? She just spent $50+ to use her free 100 credits for a transaction costing pennies in actual gas. Friction Point #5: Second transaction, more ETH gas, more waiting, feeling ripped off.

Six steps (including the initial wallet setup just to use the free credits!), multiple gas payments in a currency she had to buy separately just to use the platform credits, confusing jargon, and lots of waiting. Is it any wonder users give up?

Let’s Look Under the Hood (The Code):

Let’s define our basic contracts first.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
 
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
 
/**
 * @title PlatformCredits
 * @dev Basic ERC20 token representing credits on our platform.
 * Includes a function for the owner (platform) to grant credits.
 */
contract PlatformCredits is ERC20, Ownable {
    // Assuming 18 decimals for credits, like ETH. Adjust if needed.
    constructor(address initialOwner) ERC20("PlatformCredits", "CRED") Ownable(initialOwner) {}
 
    /**
     * @dev Grants credits to a specific address. Only callable by the owner (platform).
     * Used for simulating the initial free credits grant upon signup.
     */
    function grantCredits(address to, uint256 amount) public onlyOwner {
        _mint(to, amount); // Internally, granting credits is minting tokens
    }
 
    // Later, we will add ERC2612 permit functionality here!
}
 

How the Frontend Orchestrates the Pain (Interactive Demo):

Even with helpful libraries like viem and wagmi, the frontend code reflects this awkward two-step dance (approve then buyNFT). Let’s see it in action.

Why This Flow is Broken (The Friction Points):

Let’s hammer this home. This “standard” flow is riddled with problems:

• The Wallet Mandate: Users need a wallet before they can even receive anything of value.
• The ETH Tollbooth: Users must acquire and hold ETH, even if your dApp uses other tokens or they received tokens for free. This is often the biggest barrier to actual usage.
• The Double-Transaction Tax: The approve followed by the actual action (buyNFT) is confusing and requires two separate gas payments.
• Confusion & Delay: Multiple steps, blockchain confirmations, and unfamiliar concepts (“approve”, “gas”) create a terrible, slow user experience.

This is the baseline we must improve upon if we want Web3 to reach its potential. Now that we’ve truly felt Sarah’s pain, let’s explore the secrets to making it disappear.

2. The First Secret Weapon: Sponsoring Gas with Meta-Transactions

Remember Sarah’s nightmare? Stuck with 100 free CRED tokens but blocked by the dreaded “ETH Tollbooth”? She couldn’t even use her free gift without jumping through hoops to buy ETH just for gas. This is where countless potential users drop off, frustrated and confused.

But what if there was a way to make that tollbooth… invisible?

Imagine Sarah clicks “Buy NFT” with her credits, and it just… works. No pop-ups demanding ETH, no confusing “gas fee” messages. Behind the scenes, someone else handles the network fee. This isn’t magic; it’s the power of Meta-Transactions, our first secret weapon against the onboarding killer.

The Big Idea: The “Trusted Assistant” (Relayer)

Think of it like having a trusted assistant. Instead of Sarah going to the blockchain “post office” herself, filling out complex forms (transactions), and paying the postage (gas fee) with a special currency (ETH) she doesn’t have, she does something much simpler:

1. Sarah’s Simple Request: Sarah just writes down what she wants to do (“Use 100 CRED to buy NFT #123”) and signs it with her unique signature (using her wallet’s private key, but off-chain, costing nothing). This proves she authorized the request.
2. Handing Off to the Assistant: Her browser (the dApp frontend) sends this signed note to a special service – the “Trusted Assistant,” technically called a Relayer.
3. The Assistant Does the Work: The Relayer takes Sarah’s signed note. It verifies her signature is valid. Then, it goes to the blockchain post office, fills out the official transaction form, pays the ETH gas fee out of its own pocket, and submits the transaction.
4. The Contract Listens: The MyNFT smart contract receives the transaction from the Relayer. But how does it know it was Sarah who wanted the NFT, not the Relayer? This is where a standard called EIP-2771  comes in.

EIP-2771: The Standardized “Who’s Asking?” Protocol

EIP-2771 provides a standard way for a contract to know the original sender of a request, even when it’s submitted by a trusted Relayer (often called a “Forwarder” in EIP-2771 terminology).

Here’s how it works with our contracts:

• The Forwarder Contract: We need a trusted, on-chain “Forwarder” contract. The Relayer sends the transaction through this Forwarder. The Forwarder’s job is to verify Sarah’s signature on her original request and then call the actual target contract (MyNFT).
• Modified MyNFT Contract: Our MyNFT contract needs a small but crucial modification. Instead of checking msg.sender (which would be the Forwarder address), it needs to ask, “Who is the original sender that the trusted Forwarder verified?” OpenZeppelin provides a handy helper contract, ERC2771Context, to make this easy.

Code Transformation: Making MyNFT EIP-2771 Aware

Let’s see how our MyNFT contract changes. We need to:

1. Import and inherit ERC2771Context from OpenZeppelin.
2. Add a constructor to store the address of the trustedForwarder contract.
3. Replace all instances of msg.sender with _msgSender(). The _msgSender() function, provided by ERC2771Context, automatically checks if the call comes from the trusted forwarder and, if so, extracts the original sender’s address (Sarah’s address) from the transaction data. Otherwise, it just returns the normal msg.sender.

Here’s the modified MyNFT contract:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
 
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol"; // Still Ownable for withdrawal etc.
// Counters is no longer needed for simple increments in Solidity >=0.8.0
// Import the EIP-2771 context
import "@openzeppelin/contracts/metatx/ERC2771Context.sol"; // <--- Import
 
/**
 * @title MyNFT (EIP-2771 Enabled)
 * @dev ERC721 contract allowing NFT purchase with PlatformCredits,
 *      compatible with EIP-2771 meta-transactions.
 */
// Inherit ERC2771Context
contract MyNFT is ERC721, Ownable, ERC2771Context { // <--- Inherit
    uint256 private _tokenIdCounter; // Start from 0, first token ID will be 1
 
    IERC20 public immutable paymentCredits;
    uint256 public constant NFT_PRICE_IN_CREDITS = 100 * 10**18;
 
    event NFTMinted(address indexed buyer, uint256 indexed tokenId);
 
    // Constructor now takes the trusted forwarder address
    constructor(
        address initialOwner,
        address _paymentCreditsAddress,
        address trustedForwarder // <--- Add trusted forwarder param
    )
        ERC721("MyNFT", "MYNFT")
        Ownable(initialOwner)
        ERC2771Context(trustedForwarder) // <--- Initialize ERC2771Context
    {
        require(_paymentCreditsAddress != address(0), "MyNFT: Invalid credits token address");
        paymentCredits = IERC20(_paymentCreditsAddress);
    }
 
    /**
     * @dev Mints a new NFT after receiving payment in PlatformCredits.
     * Requires prior approval of PlatformCredits for this contract.
     * Uses _msgSender() to identify the original buyer in meta-tx scenarios.
     */
    function buyNFT() public returns (uint256) {
        uint256 currentPrice = NFT_PRICE_IN_CREDITS;
        // Use _msgSender() instead of msg.sender
        address buyer = _msgSender(); // <--- Use _msgSender()
 
        // Check allowance for PlatformCredits (still needed!)
        uint256 allowance = paymentCredits.allowance(buyer, address(this));
        require(allowance >= currentPrice, "MyNFT: Check credits allowance");
 
        // Transfer PlatformCredits from buyer to owner/treasury
        // transferFrom uses the 'buyer' address obtained via _msgSender()
        bool success = paymentCredits.transferFrom(buyer, owner(), currentPrice);
        require(success, "MyNFT: Credits transfer failed");
 
        // Mint the NFT to the original buyer
        _tokenIdCounter++; // Increment the counter
        uint256 newTokenId = _tokenIdCounter; // Assign the new ID
        _safeMint(buyer, newTokenId); // Mint to the original buyer
 
        emit NFTMinted(buyer, newTokenId);
        return newTokenId;
    }
 
    /**
     * @dev Withdraw collected credits. Only callable by the contract owner.
     * Note: Ownable's owner check uses the real msg.sender, which is fine here,
     *       but the transfer target is the owner address derived potentially
     *       from an initial deployment or transferOwnership call.
     *       If owner actions were meant to be meta-tx compatible, Ownable would
     *       also need adjustment or replacement with an EIP-2771 compatible version.
     */
    function withdrawCredits() public onlyOwner { // onlyOwner uses actual msg.sender
        uint256 balance = paymentCredits.balanceOf(address(this));
        if (balance > 0) {
            // Transfer to the owner address stored by Ownable
            bool success = paymentCredits.transfer(owner(), balance);
            require(success, "MyNFT: Credits withdrawal failed");
        }
    }
 
    // --- EIP-2771 Overrides ---
    // Optional: If you need to override the trusted forwarder later,
    // you can override the trustedForwarder() function from ERC2771Context.
    // function trustedForwarder() public view virtual override returns (address) {
    //     // return address(YOUR_NEW_FORWARDER);
    //     return super.trustedForwarder(); // Keep original if not changing
    // }
 
    // The _msgSender() and _msgData() functions are inherited from ERC2771Context.
}

Frontend: Talking to the Relayer

The frontend code changes slightly. Instead of preparing and sending a transaction directly to the blockchain using useWriteContract, it now:

1. Gets the user (Sarah) to sign the intent (the action she wants the Forwarder to execute on her behalf) using useSignTypedData. This signature is specific to the Forwarder’s requirements (EIP-712).
2. Sends this signed message and the action details to the Relayer’s API endpoint.
3. Waits for the Relayer to process the request and return a transaction hash.

Here’s the conceptual frontend code again, highlighting the interaction with the Relayer:

import { encodeFunctionData, parseAbi } from 'viem';
import { useAccount, useSignTypedData, useReadContract } from 'wagmi'; // useReadContract for nonce
 
// Assume Forwarder contract address and ABI are known
const forwarderAddress = "0x...";
const forwarderABI = parseAbi([
  'function getNonce(address from) view returns (uint256)',
  // Example EIP-2771 execute function signature (adjust based on actual Forwarder)
  'function execute(tuple(address from, address to, uint256 value, uint256 gas, uint256 nonce, bytes data) req, bytes signature) payable',
]);
// Assume MyNFT ABI and address are known
const myNFTAddress = "0x...";
const myNFTABI = [ /* ... MyNFT ABI including buyNFT ... */ ] as const;
// Assume Relayer API endpoint is known
const relayerApiEndpoint = '/api/relay'; // Your backend relayer service
 
// EIP-712 Domain and Types specific to YOUR Forwarder contract's execute function
// These define the structure the user needs to sign.
const domain = { name: "MyForwarder", version: "1", chainId: 1, verifyingContract: forwarderAddress }; // Example
const types = {
  ForwardRequest: [ // Example structure - MUST match your Forwarder's expected struct
    { name: 'from', type: 'address' },
    { name: 'to', type: 'address' },
    { name: 'value', type: 'uint256' },
    { name: 'gas', type: 'uint256' },
    { name: 'nonce', type: 'uint256' },
    { name: 'data', type: 'bytes' },
  ]
} as const;
 
 
function MetaTxButton() {
  const { address } = useAccount();
  const { signTypedDataAsync, isPending: isSigning } = useSignTypedData();
  const [isRelaying, setIsRelaying] = useState(false);
  const [status, setStatus] = useState('');
 
  // Fetch the current nonce for the user *from the Forwarder*
  const { data: nonce, isLoading: isLoadingNonce } = useReadContract({
    address: forwarderAddress,
    abi: forwarderABI,
    functionName: 'getNonce',
    args: [address!], // Ensure address is not null
    enabled: !!address, // Only run query if address exists
  });
 
  const handleMetaTxPurchase = async () => {
    if (!address || nonce === undefined) {
      setStatus("Error: Wallet not connected or nonce not loaded.");
      return;
    }
    setIsRelaying(true);
    setStatus("Preparing meta-transaction...");
 
    // 1. Craft the inner function call data (calling MyNFT.buyNFT())
    const targetCallData = encodeFunctionData({
      abi: myNFTABI,
      functionName: 'buyNFT',
      args: [],
    });
 
    // 2. Prepare the ForwardRequest message for signing
    // User signs this structure, authorizing the Forwarder to act
    const message = {
      from: address,
      to: myNFTAddress, // The target contract the Forwarder will call
      value: 0n,       // We are not sending ETH in this inner call
      gas: 150000n,    // Estimate gas needed for MyNFT.buyNFT() (Relayer might adjust)
      nonce: nonce,    // Nonce from the Forwarder to prevent replays
      data: targetCallData, // The action for the Forwarder to execute
    };
 
    try {
      // 3. Sign the typed data (EIP-712 signature)
      setStatus("Requesting signature from wallet...");
      console.log("Signing message:", message);
      const signature = await signTypedDataAsync({
        domain,
        types,
        primaryType: 'ForwardRequest',
        message,
      });
      setStatus("Signature obtained. Sending to Relayer...");
      console.log("Signature:", signature);
 
      // 4. Send the signed request and signature to YOUR Relayer backend
      console.log("Sending signed message to relayer API:", relayerApiEndpoint);
      const response = await fetch(relayerApiEndpoint, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        // The body structure depends entirely on YOUR Relayer API design
        body: JSON.stringify({
            forwardRequest: message, // The message that was signed
            signature: signature,    // The signature itself
            // You might include other info your relayer needs
         }),
      });
 
      if (!response.ok) {
        const errorBody = await response.text();
        throw new Error(`Relayer request failed: ${response.status} ${response.statusText} - ${errorBody}`);
      }
 
      const result = await response.json(); // Assuming relayer returns JSON { transactionHash: "0x..." }
      setStatus(`Relayer accepted! Tx Hash: ${result.transactionHash}. Waiting for confirmation...`);
      console.log("Relayer response:", result);
      // You would typically then use the txHash to monitor confirmation status
 
    } catch (error: any) {
      console.error("Meta-transaction failed:", error);
      setStatus(`Error: ${error.message}`);
    } finally {
      setIsRelaying(false);
    }
  };
 
  return (
    <div>
        <button
            onClick={handleMetaTxPurchase}
            disabled={!address || nonce === undefined || isLoadingNonce || isSigning || isRelaying}
        >
            {isLoadingNonce ? 'Loading Nonce...' :
             isSigning ? 'Waiting for Signature...' :
             isRelaying ? 'Relaying Transaction...' :
             'Buy NFT (Meta-Transaction)'}
        </button>
        {status && <p style={{ marginTop: '10px', wordBreak: 'break-word' }}>Status: {status}</p>}
    </div>
  );
}

The Trade-offs: Convenience Comes at a Cost

This “Trusted Assistant” model sounds great, right? Sarah gets her NFT without touching ETH! But like any powerful secret, it has important caveats:

1. The Relayer Dependency (Centralization & Trust): Your entire gasless flow depends on that Relayer service being online, funded, and trustworthy. If the Relayer goes down, your users can’t perform gasless actions. You are essentially trusting and relying on this specific off-chain infrastructure. This is a stark contrast to the ERC-4337 model (which we’ll explore later), where a decentralized network of “Bundlers” can pick up requests, removing single points of failure. You’re often locked into the specific API and requirements of your chosen Relayer.
2. Contract Modification Required (No Backwards Compatibility): This pattern only works if the target smart contract (MyNFT in our case) is specifically designed to use EIP-2771 and _msgSender(). You cannot use this method to interact with existing contracts that haven’t been built this way. If you wanted to interact with, say, a standard Uniswap router gaslessly using this pattern, it wouldn’t work because the Uniswap router isn’t EIP-2771 aware.
3. The approve Problem Still Lingers: Notice that Sarah still needs to have previously called approve on the PlatformCredits contract, granting spending permission to the MyNFT contract (or technically, the Forwarder acting on behalf of MyNFT). That approve transaction itself costs gas! So, while the buyNFT step becomes gasless for Sarah, we haven’t solved the entire flow yet. (Don’t worry, we have secrets for that too!)
4. Relayer Costs: Someone has to pay the gas. The Relayer service pays the ETH, but they aren’t a charity. They will likely pass this cost back to the dApp provider (you!) potentially with a markup, or implement logic to only relay transactions under certain conditions.

Pros:

• Hides Gas from User: The primary benefit – users with supported wallets (EOAs) don’t need native tokens (ETH) for the sponsored transaction itself.
• Works with Existing Wallets: Users don’t need a new type of wallet; their standard EOA (like MetaMask) works for signing.

Cons:

• Relayer Infrastructure: Requires building or relying on a centralized Relayer service (cost, uptime, trust, potential lock-in).
• Contract Modification: Target contracts must be EIP-2771 compatible (_msgSender()). Not backward compatible with existing, unmodified contracts.
• Doesn’t Solve approve Gas: The crucial initial token approval (PlatformCredits.approve(...)) still costs the user gas and must be done separately before this meta-transaction flow can be used for the main action.
• Complexity: Requires careful coordination between frontend, relayer backend, and EIP-2771 aware contracts.

The Gas Station Network (GSN)  was an early, more decentralized attempt at providing shared Relayer infrastructure, but implementing and using it also involves specific contract modifications and understanding its architecture.

The Problem is that the GSN is becoming more and more outdated. Many of the nodes are not working anymore according to the Status Page  and the last update to the site was in 2022/2023.

Of course, you can run your own Paymaster and Relayer service , however it somehow defeats the purpose. Our aim is to go with ready-made solutions that work out of the box and at this stage GSN does not work out of the box anymore.

Meta-transactions via EIP-2771 were a crucial first step in tackling the gas problem. They showed we could abstract gas away from the user, but the reliance on specific relayers and the need for contract changes highlighted the need for even better solutions, especially for common flows like token approvals and interacting with diverse contracts. Let’s keep digging into our arsenal of secrets!

3. The “Magic Permission Slip”: Slaying the Approve Dragon with ERC-2612 Permits!

Okay, we unveiled our first secret weapon – Meta-Transactions – and saw how it could sponsor the gas for Sarah’s buyNFT call. Pretty cool, right? But remember that nagging little problem? That annoying, separate approve transaction Sarah still had to make (and pay gas for!) before the meta-transaction could even work?

It’s like giving someone a VIP pass to the theme park (the sponsored buyNFT), but still making them wait in line and pay separately just to get a wristband allowing them to use the pass! It breaks the magic!

What if we could eliminate that approve transaction entirely? What if Sarah could grant permission without touching the blockchain, without spending a single drop of gas on approval?

Enter the Second Secret Weapon: ERC-2612 Permits – The Magic Permission Slip!

This is where things get really elegant. Imagine instead of Sarah having to go to the blockchain post office twice (once to file the “approve” form, once for the actual purchase), she could simply sign a special permission slip off-chain – like signing a piece of paper at her desk.

This “permission slip” is a digitally signed message, created using a secure standard called EIP-712. Think of EIP-712 as the universal template for creating these secure, off-chain agreements. It ensures the message is tamper-proof and clearly states: “I, Sarah (identified by my unique wallet signature), grant permission for the MyNFT contract to spend up to 100 of my CRED tokens, and this permission slip is valid until [specific time].”

The Magic: Sarah signs this message in her wallet (like MetaMask). It costs ZERO GAS because it never touches the blockchain directly. It’s just data + signature.

How the Magic Works On-Chain:

1. Sarah Signs the Slip: Sarah clicks “Buy NFT”. The dApp prepares the EIP-712 “Permit” message and asks her to sign it. Click, sign, done. No gas.
2. Frontend Bundles the Request: The dApp now takes Sarah’s main request (“Buy the NFT!”) and attaches this signed permission slip (the permit signature) to it.
3. One Transaction to Rule Them All: The dApp sends one single transaction to the MyNFT contract. This transaction calls a new function we’ll add, let’s call it buyNFTWithPermit.
4. The Contract Uses the Slip: Inside the buyNFTWithPermit function, the first thing the MyNFT contract does is take Sarah’s signed permission slip and present it to the PlatformCredits contract by calling its special permit() function.
5. PlatformCredits Verifies: The PlatformCredits contract (which we’ll upgrade slightly) looks at the signed slip. Using the magic of cryptography (specifically ecrecover on the EIP-712 signature), it verifies:
   • Was this really signed by Sarah?
   • Has this specific permission slip been used before (checking a ‘nonce’)?
   • Is it still valid (checking the ‘deadline’)?
   • If everything checks out, the PlatformCredits contract says, “Okay, permission granted!” and internally updates the allowance for the MyNFT contract without needing a separate transaction from Sarah.
6. Purchase Proceeds: Now that the allowance is set within the same transaction, the rest of the buyNFTWithPermit function in MyNFT can proceed immediately. It calls transferFrom on PlatformCredits (which now succeeds!) and mints the NFT to Sarah.

One transaction. Zero gas spent by Sarah on approval. The annoying approve step? Obliterated!

Code Transformation: Giving Our Contracts Permit Power

This requires two key changes:

1. Upgrade PlatformCredits.sol: It needs the ability to understand and process these magic permission slips. Thankfully, OpenZeppelin makes this easy! We just need to inherit their ERC20Permit contract.

   // SPDX-License-Identifier: MIT
   pragma solidity ^0.8.20;
    
   import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
   import "@openzeppelin/contracts/access/Ownable.sol";
   // Import ERC20Permit
   import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Permit.sol"; // <--- Import
    
   /**
    * @title PlatformCredits (with Permit)
    * @dev ERC20 token now including ERC-2612 permit functionality.
    */
   // Inherit ERC20Permit
   contract PlatformCredits is ERC20, Ownable, ERC20Permit { // <--- Inherit
       constructor(address initialOwner)
           ERC20("PlatformCredits", "CRED")
           Ownable(initialOwner)
           // Initialize ERC20Permit with the token name (must match ERC20 name)
           ERC20Permit("PlatformCredits") // <--- Initialize Permit
       {}
    
       function grantCredits(address to, uint256 amount) public onlyOwner {
           _mint(to, amount);
       }
    
       // The permit() function and nonce tracking are inherited from ERC20Permit!
   }

2. Add buyNFTWithPermit to MyNFT.sol: We add a new function that accepts the permit signature components (v, r, s, deadline) along with the purchase request.

   // Inside MyNFT contract...
    
   /**
    * @dev Mints a new NFT using PlatformCredits, leveraging ERC2612 permit.
    * Allows purchase without a prior separate 'approve' transaction.
    * @param deadline The permit deadline timestamp.
    * @param v The recovery byte of the permit signature.
    * @param r The r value of the permit signature.
    * @param s The s value of the permit signature.
    */
   function buyNFTWithPermit(
       uint256 deadline,
       uint8 v,
       bytes32 r,
       bytes32 s
   ) public returns (uint256) {
       uint256 currentPrice = NFT_PRICE_IN_CREDITS;
       address buyer = msg.sender; // The user sending this transaction
    
       // Step 1: Call permit on the PlatformCredits contract
       // This grants allowance if the signature is valid
       // It will revert if the signature is invalid, expired, or already used.
       paymentCredits.permit(buyer, address(this), currentPrice, deadline, v, r, s);
    
       // Step 2: Allowance is now set, proceed with transferFrom
       bool success = paymentCredits.transferFrom(buyer, owner(), currentPrice);
       require(success, "MyNFT: Credits transfer failed after permit");
    
       // Step 3: Mint the NFT
       _tokenIdCounter++; // Increment the counter
       uint256 newTokenId = _tokenIdCounter; // Assign the new ID
       _safeMint(buyer, newTokenId);
    
       emit NFTMinted(buyer, newTokenId);
       return newTokenId;
   }

Frontend: The Slight Shift

The frontend now needs to:

1. Prepare the EIP-712 Permit message.
2. Get the user to sign it using signTypedDataAsync.
3. Split the signature into v, r, s components.
4. Call the new buyNFTWithPermit function via useWriteContract, passing the signature components and deadline.

The Result? Pure Elegance!

With ERC-2612 Permits, we’ve eliminated one of the most confusing and costly steps in the standard flow. Sarah signs one message off-chain (free!), then submits one transaction on-chain. It’s smoother, cheaper, and feels much more like the seamless Web2 experiences users expect.

Pros:

• Eliminates approve Gas: The biggest win! Saves users one transaction fee.
• Better UX: Reduces the number of steps and confusing pop-ups.
• Standardized: EIP-2612 is a widely adopted standard for many tokens.
• Atomic: Approval and action happen within the same transaction.

Cons:

• Token Must Support It: The PlatformCredits token must implement ERC20Permit. You can’t use this on tokens that don’t have the permit function.
• Main Transaction Still Costs Gas: While approval is gasless, the buyNFTWithPermit transaction itself still requires gas paid by the user (Sarah, in this case).

We’ve slain the approve dragon, a massive victory! But Sarah still needs that pesky ETH in her wallet to pay gas for the main purchase. Can we do better? Can we make the entire thing gasless? Oh yes… the next secrets await!

4. Solution Pattern 3: Direct EIP-712 Signature + Permit (Gas Sponsorship)

Concept: Instead of relying on a generic Forwarder contract (like in Pattern 1), we can build the signature verification logic directly into our target contract (MyNFT). This pattern combines an off-chain signature for the main action (buyNFT using credits) with an embedded ERC-2612 permit signature for the PlatformCredits transfer, allowing a relayer to submit the transaction.

How it Works:

1. User:
   • Signs an ERC-2612 permit message for PlatformCredits, granting allowance to the MyNFT contract (off-chain, no gas).
   • Signs an EIP-712 typed data message authorizing the MyNFT contract to perform the buyNFT action on their behalf using credits. This message includes details like the function to call, parameters, a nonce, and potentially the permit signature components (v, r, s, deadline).
2. Frontend: Sends the action signature and the permit signature (or the combined signed message structure) to a Relayer backend API.
3. Relayer:
   • Verifies both signatures off-chain against the user’s address. Checks the nonce for replay protection.
   • Constructs an Ethereum transaction calling a specific function on MyNFT (e.g., buyNFTWithSignatureAndPermit).
   • Passes the user’s address, action details, permit signature components, and the action signature as arguments to the contract function.
   • Pays the gas fee using its own ETH.
   • Submits the transaction to the network.
4. Smart Contract (MyNFT):
   • Needs a new function (e.g., buyNFTWithSignatureAndPermit).
   • Implements EIP-712 domain separation and signature verification logic to validate the action signature against the provided user address and nonce.
   • Calls permit() on the PlatformCredits contract using the provided permit signature components (v, r, s, deadline).
   • If both signatures are valid and the nonce is correct, it executes the buyNFT logic (calling transferFrom on PlatformCredits which now succeeds due to the permit, and minting the NFT) on behalf of the original user. It must manage nonces for the action signature.

Implementation Changes:

• PlatformCredits.sol: Must implement ERC20Permit (EIP-2612).
• MyNFT.sol:
  • Needs to implement EIP-712 utilities (domain separator, struct hashing, ecrecover). OpenZeppelin’s EIP712 utility contract is helpful here.
  • Needs a new function like buyNFTWithSignatureAndPermit(address user, /* permit params */, /* action params */, bytes memory actionSignature).
  • Needs state to track used nonces for the action signature to prevent replays.

Frontend Interaction (Conceptual JS using viem & wagmi):

import { useAccount, useSignTypedData, useReadContract } from 'wagmi';
import { encodeFunctionData, parseAbi, recoverTypedDataAddress } from 'viem'; // For verification maybe
import { ethers } from 'ethers'; // For signature splitting (or use viem utils)
 
// Assume PlatformCredits and MyNFT ABIs, addresses are known
const platformCreditsAddress = "0x...";
const myNFTAddress = "0x...";
const nftPriceInCredits = parseEther("100");
// Assume Relayer API endpoint is known: const relayerApiEndpoint = '/api/relay-direct-sig';
 
// EIP-712 Domain/Types for PlatformCredits permit
const permitDomain = { /* ... EIP712 domain for PlatformCredits ... */ };
const permitTypes = { Permit: [ /* ... Permit fields ... */ ] };
 
// EIP-712 Domain/Types for MyNFT action signature
const nftActionDomain = { /* ... EIP712 domain for MyNFT contract ... */ };
const nftActionTypes = { BuyNFTAction: [ /* ... Fields like user, nonce, etc. ... */ ] };
 
function DirectSigButton() {
  const { address } = useAccount();
  const { signTypedDataAsync } = useSignTypedData();
  // Fetch nonces if needed (permit nonce from token, action nonce from NFT contract)
  // const { data: permitNonce } = useReadContract({...});
  // const { data: actionNonce } = useReadContract({...}); // NFT contract needs a nonce getter
 
  const handleDirectSigPurchase = async () => {
    if (!address /* || permitNonce === undefined || actionNonce === undefined */) {
      console.error("Wallet not connected or nonces not loaded");
      return;
    }
    const currentActionNonce = 0n; // Replace with actual fetched actionNonce
    const currentPermitNonce = 0n; // Replace with actual fetched permitNonce
    const deadline = BigInt(Math.floor(Date.now() / 1000) + 3600); // 1 hour
 
    try {
      // 1. Sign Permit message for PlatformCredits
      const permitMessage = {
        owner: address,
        spender: myNFTAddress, // NFT contract needs allowance
        value: nftPriceInCredits, // Use the price in credits
        nonce: currentPermitNonce,
        deadline: deadline,
      };
      console.log("Requesting permit signature...");
      const permitSignature = await signTypedDataAsync({
        domain: permitDomain,
        types: permitTypes,
        primaryType: 'Permit',
        message: permitMessage,
      });
      const { v: permitV, r: permitR, s: permitS } = ethers.Signature.from(permitSignature); // Or viem equivalent
 
      // 2. Sign Action message
      const actionMessage = {
        user: address,
        nftContract: myNFTAddress, // Could include relevant details
        nonce: currentActionNonce,
        // Include other relevant parameters if needed by the contract verification
      };
      console.log("Requesting action signature...");
      const actionSignature = await signTypedDataAsync({
        domain: nftActionDomain,
        types: nftActionTypes,
        primaryType: 'BuyNFTAction',
        message: actionMessage,
      });
 
      // 3. Send to Relayer
      console.log("Sending signatures to relayer...");
      const response = await fetch(relayerApiEndpoint, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          userAddress: address,
          permit: { value: nftPriceInCredits.toString(), deadline: deadline.toString(), v: permitV, r: permitR, s: permitS },
          action: { nonce: currentActionNonce.toString() /* ... other params ... */ },
          actionSignature: actionSignature,
        }),
      });
 
      if (!response.ok) {
        throw new Error(`Relayer request failed: ${response.statusText}`);
      }
      const result = await response.json();
      console.log("Relayer response:", result); // Should contain tx hash
 
    } catch (error) {
      console.error("Direct Signature Purchase failed:", error);
    }
  };
 
  return (
    <button onClick={handleDirectSigPurchase} disabled={!address}>
      Buy NFT (Direct Signature)
    </button>
  );
}

Pros:

• User doesn’t need ETH (if Relayer pays).
• Eliminates the separate approve transaction.
• Avoids the need for a generic, potentially complex Forwarder contract.
• Works with existing EOAs.

Cons:

• Requires Relayer infrastructure (centralization risk, cost).
• Requires significant modification and complexity within the target smart contract (MyNFT).
• User typically needs to sign two messages (permit + action), although UX can sometimes combine this.
• Less standardized than EIP-2771 or ERC-4337 approaches; signature verification logic is bespoke to the contract.

This pattern offers an alternative to generic meta-transactions when you want gas sponsorship but prefer to keep the verification logic tightly coupled with the target contract. However, the increased contract complexity is a major trade-off compared to using ERC-2612 alone or leveraging ERC-4337/EIP-7702 infrastructure.

5. Solution Pattern 4: ERC-4337 Account Abstraction

Concept: Instead of users interacting directly via their Externally Owned Accounts (EOAs), they use Smart Contract Wallets (SCWs). These SCWs act as their primary account, initiating transactions through a special mechanism defined by ERC-4337 . This standard introduces a way to achieve account abstraction without requiring consensus-layer protocol changes.

Key Components:

• Smart Contract Wallet (SCW): The user’s account, implemented as a smart contract (e.g., Safe, Kernel). It defines its own validation logic (how transactions are authorized, e.g., owner signature, multi-sig, social recovery).
• UserOperation: A data structure representing the user’s intent to perform an action (e.g., call MyNFT.buyNFT). It includes sender (SCW address), target, call data, gas limits, nonce, and potentially paymaster data. It’s like a pseudo-transaction.
• Bundler: An off-chain actor (service) that gathers UserOperation objects from users via a dedicated mempool. Bundlers package multiple UserOperations into a single standard Ethereum transaction and send it to the EntryPoint contract.
• EntryPoint: A global singleton smart contract that orchestrates the execution of UserOperations. It verifies signatures, manages gas payments, and calls the appropriate SCW to execute the transaction.
• Paymaster: An optional smart contract that can agree to pay for a user’s UserOperation gas fees, enabling sponsored transactions. Paymasters define their own sponsorship policies (e.g., free for certain actions, pay with platform credits).

How it Works (Sponsored Flow):

1. User (via dApp): Wants to execute an action (e.g., buyNFT). The dApp helps construct a UserOperation specifying the target (MyNFT), call data, and gas parameters.
2. dApp/SDK: Sends the UserOperation to a Paymaster service to request sponsorship.
3. Paymaster Service: Checks its policy. If sponsorship is granted, it returns paymasterAndData (including its signature agreeing to pay) to be added to the UserOperation.
4. User: Signs the UserOperation hash using their EOA (which owns the SCW).
5. dApp/SDK: Sends the signed UserOperation (now including paymasterAndData and the user’s signature) to a Bundler.
6. Bundler: Verifies the UserOperation, bundles it with others, and submits it to the EntryPoint contract in a single Ethereum transaction.
7. EntryPoint Contract:
   • Verifies the Paymaster’s stake and signature.
   • Verifies the SCW’s signature (by calling validateUserOp on the SCW).
   • Calls the SCW to execute the action (MyNFT.buyNFT()).
   • If successful, compensates the Bundler for gas (paid by the Paymaster).

Implementation Sketch (React Component using Candide SDK, viem, wagmi):

This example assumes you have a standard RainbowKit/Wagmi/Viem setup and want to use Candide’s SDK and infrastructure for Account Abstraction.

npm install @candide/provider viem wagmi

yarn add @candide/provider viem wagmi

import React, { useState, useEffect } from 'react';
import { useAccount, useWalletClient } from 'wagmi';
import { encodeFunctionData, parseEther, Hex } from 'viem';
import { sepolia } from 'viem/chains'; // Or your target chain
import { CandideAccount, createCandideProvider } from "@candide/provider";
 
// ABIs (ensure they are in viem format)
const platformCreditsABI = [ /* ... ERC20 ABI ... */ ] as const; // Needed if SCW needs to interact directly
const myNFTABI = [ /* ... MyNFT ABI including buyNFT ... */ ] as const;
 
// Contract Addresses and Config (Replace with your actual values)
const platformCreditsAddress = "0x..."; // Deployed PlatformCredits address
const myNFTAddress = "0x...";          // Deployed MyNFT address
const nftPriceInCredits = parseEther("100"); // Price in CRED (assuming 18 decimals)
const chain = sepolia; // Your target chain
 
// Candide Infrastructure URLs (Replace with actual Candide URLs for your chain)
const candideBundlerUrl = "https://bundler-sepolia.candide.dev"; // Example for Sepolia
const candidePaymasterUrl = "https://paymaster-sepolia.candide.dev"; // Example for Sepolia
const entryPointAddress = "0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789"; // Standard EntryPoint v0.6
 
function GaslessCandideAAPurchaseButton() {
  const { address: eoaAddress, chain: connectedChain } = useAccount();
  const { data: walletClient } = useWalletClient();
  const [candideProvider, setCandideProvider] = useState<any>(null); // Type from SDK if available
  const [smartAccount, setSmartAccount] = useState<CandideAccount | null>(null);
  const [isInitializing, setIsInitializing] = useState(false);
  const [isActing, setIsActing] = useState(false);
  const [status, setStatus] = useState('');
 
  // Initialize Candide Provider
  useEffect(() => {
    const initCandide = async () => {
      // Ensure walletClient, connectedChain exist and match our target chain
      if (walletClient && connectedChain && connectedChain.id === chain.id && !candideProvider && !isInitializing) {
        setIsInitializing(true);
        setStatus("Initializing Candide Provider...");
        console.log("Initializing Candide Provider...");
        try {
          const provider = await createCandideProvider({
            // Pass the viem WalletClient obtained from wagmi
            walletClient: walletClient,
            chain: chain, // Ensure this matches the connected chain
            entryPointAddress: entryPointAddress,
            accountAbstractionSalt: "my_unique_salt_for_user", // Important: Use a unique, deterministic salt per user/app
            bundlerUrl: candideBundlerUrl,
            paymasterUrl: candidePaymasterUrl, // Provide Paymaster URL for sponsorship
          });
          setCandideProvider(provider);
          setSmartAccount(provider.account); // Access the initialized smart account
          setStatus(`Candide Provider Initialized. SCW Address: ${provider.account.address}`);
          console.log("Candide Provider Initialized. SCW Address:", provider.account.address);
        } catch (error) {
           console.error("Failed to initialize Candide Provider:", error);
           setStatus(`Error initializing Candide: ${error.message}`);
        } finally {
           setIsInitializing(false);
        }
      } else if (connectedChain && connectedChain.id !== chain.id) {
          setStatus(`Please connect to the ${chain.name} network.`);
      }
    };
    initCandide();
  }, [walletClient, connectedChain, candideProvider, isInitializing]);
 
 
  const handlePurchase = async () => {
    if (!smartAccount || !candideProvider) {
      setStatus("Error: Candide Smart Account not initialized.");
      return;
    }
    setIsActing(true);
    setStatus("Preparing UserOperation...");
 
    try {
      // 1. Encode the call data for MyNFT.buyNFT()
      // Note: The Candide SCW (likely a Safe) must hold PlatformCredits (CRED).
      // The `prepareUserOperation` below bundles this into the SCW's execution call.
      // The SCW's internal logic (e.g., Safe's execTransaction) handles the CRED transfer.
      const callData = encodeFunctionData({
        abi: myNFTABI,
        functionName: 'buyNFT',
        args: [], // buyNFT takes no arguments in our example
      });
 
      // 2. Prepare the UserOperation using Candide SDK
      // This handles nonce, gas estimation (via bundler), etc.
      // It assumes the SCW's execute function will handle the MyToken transfer internally.
      const userOperation = await smartAccount.prepareUserOperation({
          target: myNFTAddress, // The contract the SCW should call
          data: callData,       // The data for the call
          value: 0n,            // Not sending ETH directly
          // Options for gas estimation multipliers can be added here if needed
          // e.g., { maxFeePerGasPercentageMultiplier: 130 }
      });
 
      setStatus("Sending UserOperation via Candide...");
      // 3. Send the UserOperation (Candide SDK handles Paymaster interaction if URL provided)
      // The SDK internally gets the user's signature on the userOp hash
      const userOperationResponse = await smartAccount.sendUserOperation(userOperation);
 
      setStatus(`UserOperation sent: ${userOperationResponse.userOperationHash}. Waiting for confirmation...`);
      console.log("UserOperation Hash:", userOperationResponse.userOperationHash);
 
      // 4. Wait for the transaction receipt
      const userOperationReceiptResult = await userOperationResponse.wait(); // Candide SDK helper
 
      if (userOperationReceiptResult.success) {
          setStatus(`NFT Purchased! Transaction Hash: ${userOperationReceiptResult.receipt.transactionHash}`);
          console.log("Transaction Receipt:", userOperationReceiptResult.receipt);
      } else {
          setStatus(`UserOperation failed. Reason: ${userOperationReceiptResult.receipt.revertReason || 'Unknown'}`);
          console.error("UserOperation failed:", userOperationReceiptResult);
      }
 
    } catch (error: any) {
      console.error("Candide AA Purchase failed:", error);
      setStatus(`Error: ${error.message || 'Candide AA Purchase failed.'}`);
    } finally {
      setIsActing(false);
    }
  };
 
  return (
    <div>
      <button
        onClick={handlePurchase}
        disabled={!smartAccount || isInitializing || isActing}
      >
        {isInitializing ? 'Initializing...' :
         isActing ? 'Processing...' :
         'Buy NFT (Gasless via Candide AA)'}
      </button>
      {status && <p style={{ marginTop: '10px', wordBreak: 'break-word' }}>Status: {status}</p>}
      {smartAccount && <p>SCW Address: {smartAccount.address}</p>}
    </div>
  );
}

Pros:

• True Gasless Experience: Users don’t need ETH if a Paymaster sponsors the transaction.
• Enhanced UX: Enables features like batching multiple actions into one transaction, social recovery, spending limits, etc., defined at the wallet level.
• Standardized: ERC-4337 provides a common interface for SCWs, Bundlers, and Paymasters, fostering a growing ecosystem.
• No Protocol Change: Works on existing EVM chains.

Cons:

• Infrastructure Reliance: Depends on reliable Bundler and Paymaster services (though these can be decentralized).
• Potential Cost: While users might not pay gas, the dApp/Paymaster bears the cost. Base gas costs for UserOperations can sometimes be slightly higher than simple EOA transactions due to verification overhead.
• Adoption Curve: Requires users to have or deploy an SCW. While deployment can be counterfactual (address exists before deployment) and sponsored, it’s still a different model than traditional EOAs.

ERC-4337 represents a major step towards making Web3 more user-friendly by abstracting away gas complexities and enabling richer wallet functionalities.

6. Solution Pattern 5: EIP-7702 - Empowering EOAs

Concept: A new transaction type (0x04) allows an EOA to temporarily delegate its execution logic to a smart contract for a single transaction. This enables EOA batching and sponsorship.

How it Works (Simplified):

1. User: Still uses their regular EOA (e.g., MetaMask).
2. Frontend (using an EIP-7702 compatible SDK/library):
   • Identifies the user wants to perform an action (e.g., buyNFT).
   • Needs a Delegate Contract: A pre-deployed contract designed to perform the required actions (e.g., call PlatformCredits.permit then MyNFT.buyNFT). This contract contains the logic the EOA will temporarily adopt.
   • Constructs an EIP-7702 transaction (type 0x04). This involves:
     • Specifying the delegate contract address.
     • The actual call data intended for the delegate contract.
     • Getting an authorization signature from the user’s EOA for this specific delegation + nonce (using a new eth_signTransaction mode or similar).
   • Sends this structured EIP-7702 transaction request to a Sponsor/Relayer service (similar to Bundlers/Paymasters but for EIP-7702).
3. Sponsor/Relayer Service:
   • Verifies the authorization and potentially checks sponsorship rules.
   • Submits the valid EIP-7702 transaction (type 0x04) to the network, paying the gas.
4. On-Chain Execution (Post-Pectra Hardfork):
   • The EVM recognizes the EIP-7702 transaction.
   • It verifies the user’s authorization signature.
   • It temporarily sets the user’s EOA code pointer to the delegate contract.
   • The transaction’s to field likely calls the EOA itself (or the delegate directly).
   • The delegate contract’s code executes in the context of the user’s EOA. It performs the batch (permit + buyNFT).
   • The EOA’s code pointer reverts after the transaction.

Implementation Sketch (Conceptual JS using wagmi & viem - EIP-7702):

// NOTE: This is highly conceptual as EIP-7702 SDKs/Wallet support are still emerging.
import { sepolia } from 'viem/chains';
import { encodeFunctionData, parseAbi, parseEther, Hex } from 'viem';
import { useAccount, useWalletClient, useSignTypedData } from 'wagmi';
import { ethers } from 'ethers'; // For signature splitting (or use viem utils)
 
// Assume an EIP-7702 compatible SDK/Relayer client exists
// import { sendEip7702Transaction } from 'your-eip7702-sdk';
 
// Address of the pre-deployed Delegate Contract (must be trusted)
const delegateContractAddress = "0x..."; // Replace with actual address
// ABI of the Delegate Contract
const delegateABI = parseAbi([
    // Example: Function expects permit signature components
    'function executePermitAndBuy(address creditsToken, address nftContract, uint256 price, uint256 deadline, uint8 v, bytes32 r, bytes32 s)',
]);
 
// Assume PlatformCredits implements permit
const platformCreditsAddress = "0x..."; // Replace with actual address
const myNFTAddress = "0x...";          // Replace with actual address
const nftPriceInCredits = parseEther("100"); // Example price in CRED
 
// EIP-712 Domain/Types for PlatformCredits permit signature
const permitDomain = { /* ... EIP712 domain for PlatformCredits ... */ }; // Replace with actual domain
const permitTypes = { Permit: [ /* ... Permit fields ... */ ] }; // Replace with actual types
 
function GaslessEip7702Button() {
    const { address } = useAccount();
    const { data: walletClient } = useWalletClient(); // Needed for signing EIP-7702 auth
    const { signTypedDataAsync } = useSignTypedData(); // For signing the permit
 
    const handleEip7702Purchase = async () => {
        if (!address || !walletClient) {
            console.error("Wallet not connected");
            return;
        }
        console.log("Starting gasless EIP-7702 NFT purchase...");
 
        try {
            // --- Step 1: Get Permit Signature for PlatformCredits (Off-chain) ---
            const deadline = BigInt(Math.floor(Date.now() / 1000) + 3600); // 1 hour
            // Fetch actual permit nonce from PlatformCredits contract using viem/wagmi readContract
            const permitNonce = 0n; // Replace with actual fetched nonce
            const permitMessage = {
                owner: address,
                spender: delegateContractAddress, // The delegate contract needs the allowance
                value: nftPriceInCredits, // Use price in credits
                nonce: permitNonce, // Use actual nonce
                deadline: deadline,
            };
 
            console.log("Requesting permit signature...");
            const permitSignature = await signTypedDataAsync({
                domain: permitDomain,
                types: permitTypes,
                primaryType: 'Permit',
                message: permitMessage,
            });
            console.log("Permit signature obtained:", permitSignature);
 
            // Split signature using viem/ethers utility
            const { v, r, s } = ethers.Signature.from(permitSignature); // Replace with viem equivalent if preferred
 
            // --- Step 2: Prepare the Delegate Call Data ---
            const delegateCallData = encodeFunctionData({
                abi: delegateABI,
                functionName: 'executePermitAndBuy',
                args: [
                    platformCreditsAddress,
                    myNFTAddress,
                    nftPriceInCredits,
                    deadline,
                    v, // Pass signature components
                    r,
                    s,
                ],
            });
 
            // --- Step 3: Construct and Send EIP-7702 Transaction via Sponsor/Relayer ---
            // This part is highly dependent on wallet support and SDKs which are TBD.
            // It would involve:
            // 1. Getting an authorization signature from the user via walletClient (e.g., a modified eth_signTransaction)
            //    that approves delegating to `delegateContractAddress` for this specific call (`delegateCallData`).
            // 2. Sending the transaction details (delegateAddress, delegateCallData, authorization)
            //    to a Sponsor/Relayer service.
 
            console.log("Constructing EIP-7702 transaction (Conceptual)...");
            // const authorizationSignature = await walletClient.signEip7702Authorization(...) // Speculative
 
            // Use an SDK function to send via relayer (API is speculative)
            // const relayerResponse = await sendEip7702Transaction({
            //     delegateAddress: delegateContractAddress,
            //     delegateCallData: delegateCallData,
            //     authorization: authorizationSignature, // Speculative
            //     // Potentially other params like nonce, gas limits for the relayer
            // });
 
            // console.log("EIP-7702 Transaction submitted via Relayer, Hash:", relayerResponse.transactionHash); // Speculative
 
            // // Wait for confirmation (SDK might provide a helper)
            // const receipt = await relayerResponse.wait(); // Speculative
            // console.log("EIP-7702 Transaction confirmed:", receipt.transactionHash); // Speculative
 
            console.log("Conceptual EIP-7702 flow complete. NFT Purchase initiated (if infra existed).");
            alert("EIP-7702 flow is conceptual. Transaction not actually sent.");
 
 
        } catch (error) {
            console.error("EIP-7702 Purchase failed:", error);
            alert(`Error: ${error.message}`);
        }
    };
 
     return (
        <button onClick={handleEip7702Purchase} disabled={!address || !walletClient}>
            Buy NFT (EIP-7702 - Conceptual)
        </button>
     );
}
 

Pros:

• Works directly with existing EOAs (massive user base).
• Enables native EOA batching and sponsorship.
• Potentially simpler migration path for dApps compared to full AA.
• Designed for forward compatibility with ERC-4337.

Cons:

• Very new, requires Pectra hardfork inclusion and widespread infra/wallet adoption.
• Security of delegate contracts is paramount.
• Introduces new complexities around transaction validity and state changes for EOAs.

7. Comparison and Choosing the Right Approach

When to Use What:

• Simple ERC20 approve removal (for PlatformCredits): Use ERC-2612 if the PlatformCredits token supports it. It’s clean and standard.
• Gas sponsorship for specific contract actions (EOA using credits): Consider Direct Signature + Permit if you control the target contract and prefer embedding logic there over a generic forwarder. Be mindful of complexity.
• Full gas sponsorship & advanced features (new dApp): Go with ERC-4337. Build with Account Abstraction from the start using SDKs like Candide’s.
• Need to support existing EOA users with batching/sponsorship: EIP-7702 (once available and supported) offers a powerful bridge. Requires careful delegate design.
• Basic gas sponsorship for EOAs (generic): Traditional Meta-Transactions (EIP-2771) might still be viable, especially if using existing infrastructure, but compare overhead with AA SDKs.

Conclusion: The Path to Seamless Web3

The journey from clunky, gas-heavy interactions (even for using free credits!) to smooth, potentially gasless flows is well underway. While traditional transactions remain the foundation, solutions like ERC-2612, ERC-4337, and the promising EIP-7702 provide developers with powerful tools to drastically improve the user onboarding experience.

• ERC-2612 tackles the common approve pain point for tokens like PlatformCredits.
• ERC-4337 offers a flexible, future-proof framework for gas abstraction and advanced wallet features via Smart Contract Wallets, allowing users to spend their credits without needing ETH.
• EIP-7702 aims to bring batching and sponsorship capabilities directly to the vast number of existing EOAs.

By understanding and implementing these patterns, we can build dApps that are not just powerful, but also accessible and welcoming to the next wave of Web3 users. Choose the right tool for your specific needs, prioritize user experience, and help build a more seamless decentralized future!