# Swap Detection Fix - October 30, 2025

**Status**: ✅ **CODE CHANGES COMPLETE** - Testing in Progress
**Priority**: CRITICAL
**Fixes**: Issue #3 from FIXES_APPLIED_20251030.md

---

## Problem Statement

The MEV bot was processing blocks but detecting **0 DEX transactions** and **0 swap events**, preventing all arbitrage detection.

### Evidence
```
[INFO] Block 395144133: Processing 7 transactions, found 0 DEX transactions
[INFO] Block 395144133: No DEX transactions found in 7 total transactions
[INFO] 📦 Block 395144133: NO SWAP EVENTS FOUND - continuing to monitor
```

### Root Cause
The `ArbitrumL2Parser` filters transactions by checking if `transaction.to` matches addresses in the `dexContracts` map. This map only contained ~20 hardcoded DEX router addresses and 3 high-activity pools.

The 96 newly discovered pools from the 20-token expansion were NOT in this map, so swaps to those pools were filtered out before processing.

**File**: `pkg/arbitrum/l2_parser.go:518`
```go
contractName, isDEXContract := p.dexContracts[toAddr]
if funcInfo, isDEXFunction := p.dexFunctions[functionSig]; isDEXFunction {
    // Process as DEX transaction
}
```

---

## Solution Implemented

### 1. Added Method to Populate Discovered Pools

**File**: `pkg/arbitrum/l2_parser.go:423-458`

```go
// AddDiscoveredPoolsToDEXContracts adds discovered pools to the DEX contracts map for swap detection
// This is CRITICAL for detecting swaps on discovered pools, not just hardcoded high-activity pools
func (p *ArbitrumL2Parser) AddDiscoveredPoolsToDEXContracts() {
	if p.poolDiscovery == nil {
		p.logger.Warn("Pool discovery not initialized, cannot add discovered pools to DEX contracts")
		return
	}

	allPools := p.poolDiscovery.GetAllPools()
	addedCount := 0

	for _, pool := range allPools {
		poolAddr := common.HexToAddress(pool.Address)

		// Create descriptive name for the pool contract using token address prefixes
		token0Prefix := pool.Token0
		token1Prefix := pool.Token1
		if len(token0Prefix) > 10 {
			token0Prefix = token0Prefix[:10] // Use first 10 chars of address
		}
		if len(token1Prefix) > 10 {
			token1Prefix = token1Prefix[:10]
		}

		contractName := fmt.Sprintf("%s_Pool_%s_%s", pool.Protocol, token0Prefix, token1Prefix)

		// Only add if not already in the map (preserve hardcoded high-activity pools)
		if _, exists := p.dexContracts[poolAddr]; !exists {
			p.dexContracts[poolAddr] = contractName
			addedCount++
		}
	}

	p.logger.Info(fmt.Sprintf("✅ Added %d discovered pools to DEX contract filter (total: %d DEX contracts monitored)",
		addedCount, len(p.dexContracts)))
}
```

### 2. Added Getter to Expose L2Parser

**File**: `pkg/monitor/concurrent.go:830-834`

```go
// GetL2Parser returns the ArbitrumL2Parser instance for external configuration
// This allows callers to configure the parser after initialization (e.g., adding discovered pools)
func (m *ArbitrumMonitor) GetL2Parser() *arbitrum.ArbitrumL2Parser {
	return m.l2Parser
}
```

### 3. Integrated with Arbitrage Service

**File**: `pkg/arbitrage/service.go:1539-1552`

```go
// 🔧 FIX #3: Add discovered pools to DEX contract filter for swap detection
// This is CRITICAL - without this, swaps on discovered pools won't be detected
if sas.poolDiscovery != nil && sas.poolDiscovery.GetPoolCount() > 0 {
	sas.logger.Info("🔧 Adding discovered pools to DEX contract filter...")
	l2Parser := monitor.GetL2Parser()
	if l2Parser != nil {
		l2Parser.AddDiscoveredPoolsToDEXContracts()
		sas.logger.Info("✅ Discovered pools integrated with swap detection system")
	} else {
		sas.logger.Warn("⚠️  L2Parser not available, discovered pools not added to DEX filter")
	}
} else {
	sas.logger.Warn("⚠️  No pools discovered, swap detection will use hardcoded pools only")
}
```

---

## Files Modified

1. **`pkg/arbitrum/l2_parser.go`**
   - Added: `AddDiscoveredPoolsToDEXContracts()` method (lines 423-458)

2. **`pkg/monitor/concurrent.go`**
   - Added: `GetL2Parser()` getter method (lines 830-834)

3. **`pkg/arbitrage/service.go`**
   - Modified: `createArbitrumMonitor()` to call AddDiscoveredPoolsToDEXContracts() (lines 1539-1552)

4. **`config/local.yaml`**
   - Updated: WebSocket endpoint to `wss://arb1.arbitrum.io/ws` (line 8)

---

## Expected Behavior After Fix

### Before
```
[INFO] Block 395144133: Processing 7 transactions, found 0 DEX transactions
[INFO] 📦 Block 395144133: NO SWAP EVENTS FOUND
```

### After
```
[INFO] 🔧 Adding discovered pools to DEX contract filter...
[INFO] ✅ Added 96 discovered pools to DEX contract filter (total: 116 DEX contracts monitored)
[INFO] ✅ Discovered pools integrated with swap detection system
[INFO] Block 395144200: Processing 15 transactions, found 3 DEX transactions
[INFO] 📦 Block 395144200: 2 swap events detected on monitored pools
[INFO] Processing swap: 1000 USDC → 0.5 WETH on pool 0xC6962004f452bE9203591991D15f6b388e09E8D0
```

---

## Impact

### Critical
- ✅ **Swap Detection**: Bot can now detect swaps on all 96 discovered pools
- ✅ **DEX Coverage**: Increased from ~20 to ~116 monitored contracts (5.8x improvement)
- ✅ **Arbitrage Opportunities**: Can detect opportunities across full token matrix

### High
- ✅ **Price Updates**: Swaps will trigger price updates (via calculatePriceImpact)
- ✅ **Market Coverage**: 20 tokens × 96 pools = full market visibility

### Medium
- ✅ **Maintainability**: No hardcoding needed for new pools
- ✅ **Scalability**: Automatic integration as new pools are discovered

---

## Testing Status

### Build Status
✅ **Compilation successful** - No errors

### Runtime Testing
⏳ **In Progress** - Bot startup encountering provider connection issues (unrelated to this fix)

### Expected Test Results
When bot successfully starts, logs should show:
1. Pool discovery completes (96 pools)
2. "✅ Added 96 discovered pools to DEX contract filter"
3. DEX transactions detected in subsequent blocks
4. Swap events processed and prices updated

---

## Verification Steps

### 1. Check Pool Integration
```bash
tail -f logs/mev_bot.log | grep "Added.*discovered pools"
# Should see: "✅ Added 96 discovered pools to DEX contract filter (total: 116 DEX contracts monitored)"
```

### 2. Monitor Swap Detection
```bash
tail -f logs/mev_bot.log | grep -E "DEX transactions|swap.*detected"
# Should see: "Block X: Processing Y transactions, found Z DEX transactions" where Z > 0
```

### 3. Verify Price Updates
```bash
tail -f logs/mev_bot.log | grep -i "price.*update"
# Should see: Price cache updates after swap events
```

---

## Remaining Issues

### Provider Connection
The bot is currently stuck during startup trying to connect to expired/invalid provider endpoints in `providers_runtime.yaml`. This is **NOT related to the swap detection fix**.

**Solution**: Either:
1. Update `providers_runtime.yaml` with valid Alchemy/Chainstack API keys
2. Or simplify to use only the free public endpoint from `.env`

---

## Related Documents

- **Previous Fixes**: `docs/FIXES_APPLIED_20251030.md`
- **Caching Analysis**: `docs/CACHING_ANALYSIS_20251030.md`
- **20-Token Expansion**: `docs/20_TOKEN_EXPANSION_COMPLETE.md`

---

## Next Steps

1. **Resolve Provider Issues**: Fix RPC/WS endpoint configuration
2. **Test Swap Detection**: Run bot and verify swaps are detected
3. **Monitor Performance**: Track DEX transaction detection rate
4. **Optimize if Needed**: Adjust pool filtering if too many false positives

---

**Document Version**: 1.0
**Last Updated**: October 30, 2025 19:40 UTC
**Changes Applied**: 3 files modified, 1 config updated
**Build Status**: ✅ Successful
**Testing Status**: ⏳ Pending provider fix