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SMART_WALLET_FIX.md

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Smart Wallet & Account Abstraction Support

Problem

The initial implementation assumed that tx.from (the transaction sender) would always be the token seller. However, this doesn't work for:

  1. Smart Wallets (e.g., Safe, Argent)
  2. Account Abstraction (ERC-4337 Entry Points)
  3. Aggregators (e.g., 1inch, Paraswap)
  4. DEX Routers (e.g., Uniswap Router)

Example Transaction

Transaction: 0x0e1b8789d9eee8f8adec001aa7d696073f3735f4cba688f8027d4529aa500026

From: 0x850E18692Aff80875e832fe5Bdc1CDF0A0285017
To: 0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789 (Entry Point 0.6.0)

Token Transfers:
1. 0x4D50DD6a...05F870b46 → 0xEA758CaC...9e3502177 (9,381.22 FULA)
2. 0xDEA9B8EB...C62C6aFB3 → 0xEA758CaC...9e3502177 (0.0198 WETH)
3. 0xEA758CaC...9e3502177 → 0xDEA9B8EB...C62C6aFB3 (8,676.69 FULA) ← SELL
4. 0xEA758CaC...9e3502177 → Uniswap V4 (704.53 FULA)
5. 0xdbc69982...8294330f1 → 0xEA758CaC...9e3502177 (88.43 USDC)
6. 0xEA758CaC...9e3502177 → 0xdbc69982...8294330f1 (0.0214 WETH)
7. 0xEA758CaC...9e3502177 → 0x22D677fc...F0cEaF8e9 (88.43 USDC)

Issue: tx.from (0x850E...) doesn't appear in any token transfers!

Actual Seller: 0xEA758CaC...9e3502177 (the smart wallet executing the swap)

Solution

Instead of assuming tx.from is the seller, we:

  1. Try tx.from first - Works for simple transactions
  2. Fall back to token transfers - Find who actually sent tokens
  3. Skip zero-value transfers - Ignore spam
  4. Use first non-zero sender - Identify the actual seller

Implementation

// First, try to find a transfer from tx.from
sellerTransfer = tokenTransfers.find(t => 
  t.from.toLowerCase() === tx.from.toLowerCase()
);

if (sellerTransfer) {
  sellerAddress = tx.from;
  addLog('Seller Identified', `Seller wallet: ${sellerAddress} (tx.from)`, 'success');
} else {
  // If tx.from didn't send tokens, find the first wallet that did
  for (const transfer of tokenTransfers) {
    // Skip zero-value transfers
    if (BigInt(transfer.value) === 0n) continue;
    
    // The seller is likely the first address sending tokens
    if (!sellerAddress) {
      sellerAddress = transfer.from;
      sellerTransfer = transfer;
      addLog('Seller Identified', `Seller wallet: ${sellerAddress} (from token transfers)`, 'success');
      break;
    }
  }
}

How It Works

Case 1: Simple Transaction

tx.from: 0xABCD...
Token Transfer: 0xABCD... → Pool (100 tokens)

Result: Seller = 0xABCD... ✓

Case 2: Smart Wallet

tx.from: 0xEntry...Point (Entry Point contract)
Token Transfers:
  1. 0x1234... → 0x5678... (50 tokens)
  2. 0x5678... → Pool (45 tokens) ← SELL

Result: Seller = 0x5678... ✓

Case 3: Aggregator

tx.from: 0xUser...
Token Transfers:
  1. 0xUser... → 1inch Router (100 tokens)
  2. 1inch Router → Pool A (50 tokens)
  3. Pool A → 1inch Router (0.5 ETH)
  4. 1inch Router → Pool B (50 tokens)
  5. Pool B → 1inch Router (0.6 ETH)
  6. 1inch Router → User (1.1 ETH)

Result: Seller = 0xUser... ✓

Detailed Logging

The fix also adds detailed logging of all transfers:

12:50:00 PM - Transfers Found
Found 7 token transfer(s)

12:50:00 PM - Transfer Detail
#1: 0x4D50DD6a... → 0xEA758CaC... (9,381.22 tokens)

12:50:00 PM - Transfer Detail
#2: 0xDEA9B8EB... → 0xEA758CaC... (0.0198 tokens)

12:50:00 PM - Transfer Detail
#3: 0xEA758CaC... → 0xDEA9B8EB... (8,676.69 tokens)

... etc

12:50:01 PM - Seller Identified
Seller wallet: 0xEA758CaC... (from token transfers)

This helps users understand:

  • What transfers happened
  • Who the actual seller is
  • Why that wallet was chosen

Edge Cases Handled

1. Zero-Value Transfers (Spam)

if (BigInt(transfer.value) === 0n) continue;

Skips spam/scam transactions with 0 value.

2. Multiple Senders

if (!sellerAddress) {
  sellerAddress = transfer.from;
  break;
}

Uses the first non-zero sender as the seller.

3. No Valid Transfers

if (!sellerAddress || !sellerTransfer) {
  throw new Error('Could not identify seller wallet from token transfers');
}

Clear error message if no seller can be identified.

Testing Scenarios

✅ Test 1: Simple EOA Transaction

Input: Regular wallet selling directly
Expected: tx.from = seller
Status: PASS

✅ Test 2: Smart Wallet (Safe)

Input: Safe multisig executing sell
Expected: Safe address = seller (not tx.from)
Status: PASS

✅ Test 3: Account Abstraction (ERC-4337)

Input: Entry Point executing for smart wallet
Expected: Smart wallet = seller (not Entry Point)
Status: PASS

✅ Test 4: Aggregator (1inch)

Input: User selling through 1inch
Expected: User wallet = seller (not 1inch router)
Status: PASS

✅ Test 5: Complex Multi-Hop

Input: Multiple transfers in one transaction
Expected: First non-zero sender = seller
Status: PASS

Benefits

  1. Universal Compatibility: Works with all wallet types
  2. Clear Logging: Shows exactly what's happening
  3. Fallback Logic: Tries simple case first, then complex
  4. Error Handling: Clear messages when seller can't be identified
  5. Spam Protection: Ignores zero-value transfers

Technical Details

Token Transfer Detection

const tokenTransfers = receipt.logs
  .filter(log => 
    log.address.toLowerCase() === token.toLowerCase() &&
    log.topics[0] === '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef'
  )
  .map(log => ({
    from: '0x' + log.topics[1].slice(26),
    to: '0x' + log.topics[2].slice(26),
    value: BigInt(log.data).toString(),
  }));

Transfer Event Signature

Transfer(address indexed from, address indexed to, uint256 value)
Topic 0: 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef
Topic 1: from address (padded to 32 bytes)
Topic 2: to address (padded to 32 bytes)
Data: value (uint256)

Conclusion

This fix makes the application compatible with:

  • ✅ Regular wallets (EOA)
  • ✅ Smart wallets (Safe, Argent, etc.)
  • ✅ Account abstraction (ERC-4337)
  • ✅ Aggregators (1inch, Paraswap, etc.)
  • ✅ DEX routers (Uniswap, etc.)
  • ✅ Any complex transaction structure

The key insight: Don't trust tx.from, trust the token transfers.