# Etherscan Bytecode Mismatch - Deep Analysis

**Error**: "Unable to find matching Contract Bytecode and ABI"  
**Contract**: `0x89dd12025bfCD38A168455A44B400e913ED33BE2`

---

## 🔍 Bytecode Analysis

### What Etherscan Expects (Deployed Bytecode)
```
60806040526005600155670e92596fd62900006002556710a741a462780000600355...
```

### What Our Source Code Compiles To
```
60c034620001cb57601f62001b6638819003918201601f191683019291906001600160401b038411...
```

**These are completely different bytecodes!**

---

## ⚠️ Root Cause Analysis

The bytecode mismatch indicates one of these scenarios:

### 1. Source Code Mismatch
The deployed contract was compiled from **different source code** than what we have.

**Possible reasons**:
- Contract was modified before deployment
- Different version of the contract was deployed
- Source code has changed since deployment

### 2. Compiler Settings Mismatch
Even with `viaIR: true`, the bytecode doesn't match, suggesting:
- Different optimizer settings
- Different Solidity version
- Different EVM version
- Different compilation method

### 3. Wrong Contract Address
The address `0x89dd12025bfCD38A168455A44B400e913ED33BE2` might be:
- A different contract entirely
- A proxy contract
- A modified version

---

## ✅ Solutions to Try

### Solution 1: Try Single File WITHOUT Via IR

**Settings**:
- **Compiler Type**: `SINGLE FILE / CONCATENATED METHOD`
- **Compiler Version**: `v0.8.20+commit.a1b79de6`
- **License**: `MIT License (MIT)`
- **Optimization**: `Yes` (200 runs)
- **Via IR**: `No` (or leave default)

**Contract Code**: Copy from `docs/CCIPWETH9Bridge_flattened.sol`

**Constructor Arguments**:
```
0x00000000000000000000000080226fc0ee2b096224eeac085bb9a8cba1146f7d000000000000000000000000c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2000000000000000000000000514910771af9ca656af840dff83e8264ecf986ca
```

**Why**: Even though deployment used `--via-ir`, the bytecode mismatch suggests trying without it.

---

### Solution 2: Check for Different Source Code Version

The contract may have been deployed from a modified version. Check:
- Git history for changes to `CCIPWETH9Bridge.sol`
- Different branches or commits
- Manual modifications before deployment

---

### Solution 3: Verify Contract Address

Confirm the contract address is correct:
- Check deployment transaction
- Verify it's the right network (Ethereum Mainnet)
- Ensure it's not a proxy or different contract

---

### Solution 4: Try Different Compiler Versions

Try these compiler versions in order:
1. `v0.8.20+commit.a1b79de6` (current)
2. `v0.8.19+commit.7dd6d404` (matches pragma)
3. `v0.8.20` (without commit hash)

---

### Solution 5: Check Deployment Transaction

Get the exact deployment transaction to see:
- What source code was used
- What compiler settings were used
- If there were any modifications

```bash
# Get deployment transaction
cast tx <DEPLOYMENT_TX_HASH> --rpc-url $ETHEREUM_MAINNET_RPC
```

---

## 🔍 Etherscan Output Analysis

From the error message:

**Found Contracts**:
- `CCIPWETH9Bridge.sol:CCIPWETH9Bridge` ✅
- `CCIPWETH9Bridge.sol:IERC20` ✅
- `CCIPWETH9Bridge.sol:IRouterClient` ✅

**Compiler Settings Used**:
- Compiler Version: `v0.8.20+commit.a1b79de6` ✅
- Optimization Enabled: `True` ✅
- Runs: `200` ✅

**Issue**: Bytecode doesn't match despite correct settings.

---

## 📋 Recommended Action Plan

### Step 1: Try Single File Method (No Via IR)

1. Go to Etherscan verification page
2. Select **"SINGLE FILE / CONCATENATED METHOD"**
3. Compiler: `v0.8.20+commit.a1b79de6`
4. License: `MIT License (MIT)`
5. Optimization: `Yes` (200 runs)
6. Via IR: `No` (or default)
7. Paste flattened contract code
8. Enter constructor arguments
9. Submit

### Step 2: If That Fails

Try different compiler versions:
- `v0.8.19+commit.7dd6d404`
- `v0.8.20` (no commit)

### Step 3: If Still Fails

- Check deployment transaction for exact source code
- Verify contract address is correct
- Consider the contract may have been deployed from modified source

---

## 🔧 Alternative: Manual Bytecode Comparison

Compare the deployed bytecode with compiled bytecode:

```bash
# Get deployed bytecode
cast code 0x89dd12025bfCD38A168455A44B400e913ED33BE2 --rpc-url $ETHEREUM_MAINNET_RPC > deployed.bytecode

# Compile locally
forge build --via-ir
# Compare with out/ccip/CCIPWETH9Bridge.sol/CCIPWETH9Bridge.json
```

---

## ⚠️ Important Notes

1. **The bytecode mismatch is significant** - not just a minor difference
2. **This suggests source code or settings don't match deployment**
3. **Try without via-ir first** - even though deployment used it
4. **Check if contract was modified** before deployment

---

**Last Updated**: $(date)  
**Status**: ⚠️ **BYTECODE MISMATCH - TRY WITHOUT VIA IR**

