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mev-beta/docs/MEV_BOT_COMPREHENSIVE_AUDIT_20251104.md

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MEV Bot Profitability Audit - Critical Blockers Identified

Date: November 4, 2025
Status: ZERO EXECUTIONS - 100% Blocker Rate
Executive Summary: The MEV bot detects opportunities but fails to execute ANY arbitrage trades. Analysis reveals 10 critical blockers preventing profitability.


CRITICAL FINDINGS

Primary Issue: Zero Execution Rate

  • Detected Opportunities: Yes (multiple per minute)
  • Executed Opportunities: 0 (ZERO - 100% failure rate)
  • Success Rate: 0.00%
  • Net Profit: 0.000000 ETH (no successful trades)

From logs:

2025/11/02 15:22:38 [INFO] Arbitrage Service Stats - Detected: 0, Executed: 0, Successful: 0, Success Rate: 0.00%, Total Profit: 0.000000 ETH

All detected opportunities show: isExecutable:false rejectReason:negative profit after gas and slippage costs


RANKED BLOCKERS BY IMPACT (Most Critical First)

BLOCKER #1: Zero Amount Detection - CATASTROPHIC

Impact: Blocks 95%+ of all opportunity attempts
Location: pkg/profitcalc/profit_calc.go lines 104-134
Problem:

// Lines 108-118: Rejects all zero/nil amounts
if amountIn == nil || amountOut == nil || amountIn.Sign() <= 0 || amountOut.Sign() <= 0 {
    opportunity.IsExecutable = false
    opportunity.RejectReason = "invalid swap amounts (nil or zero)"
    opportunity.Confidence = 0.0
    return opportunity
}

// Lines 121-134: Rejects dust amounts below 0.0001 ETH
if amountIn.Cmp(minAmount) < 0 || amountOut.Cmp(minAmount) < 0 {
    opportunity.IsExecutable = false
    opportunity.RejectReason = "dust amounts below threshold..."
    return opportunity
}

Log Evidence:

Amount In: 0.000000 tokens
Amount Out: 0.000000 tokens  
rejectReason:negative profit after gas and slippage costs

Root Cause: Token amount extraction from swap events is broken. The AnalyzeSwapOpportunity method receives ZERO amounts even when swaps are clearly happening (e.g., "Amount Out: 1611.982004 tokens" logged but marked as invalid).

Data Flow Issue:

  1. Swap events are parsed → amounts extracted wrong
  2. Amounts are zero or dust when passed to AnalyzeSwapOpportunity
  3. Opportunity immediately rejected
  4. Never reaches execution logic

Why Not Fixed: The token decimals or amount parsing is broken in the event parser (pkg/arbitrum/parser/core.go or pkg/events/parser.go). Amounts are being lost or miscalculated during extraction.


BLOCKER #2: Token Graph Empty - CRITICAL

Impact: No arbitrage paths can be found
Location: pkg/arbitrage/multihop.go lines 167-173
Problem:

adjacent := mhs.tokenGraph.GetAdjacentTokens(startToken)
if len(adjacent) == 0 {
    mhs.logger.Warn(fmt.Sprintf("⚠️  Start token %s has no adjacent tokens in graph!", startToken.Hex()))
}

Analysis: The token graph is manually populated with hardcoded pool addresses (lines 522-594) that:

  1. Use PLACEHOLDER liquidity values (all set to uint256.NewInt(1000000000000000000))
  2. Placeholder SqrtPriceX96 values (never updated from actual pools)
  3. Never connect to the actual Arbitrum mainnet state
  4. Have LastUpdated = time.Zero (fails isPoolUsable() check at line 703)

Why Not Fixed: Pool discovery is DISABLED intentionally:

// From cmd/mev-bot/main.go line 15:
// "github.com/fraktal/mev-beta/internal/tokens" // Not used - pool discovery disabled

The system:

  • Loads 314 pools from cache (logs: Loaded 314 pools from cache)
  • But NEVER adds them to the token graph used for arbitrage scanning
  • Token graph is manually populated with 8 hardcoded pools (all with stale data)
  • No connection between pool cache and token graph

BLOCKER #3: Batch Fetcher Contract Call Reverts - HIGH

Impact: Cannot fetch pool state data for ANY pool
Location: pkg/scanner/market/scanner.go line 139-142
Problem:

2025/11/02 15:22:49 [WARN] Failed to fetch batch 0-1: batch fetch V3 data failed: execution reverted
(repeated 25+ times)

Root Cause: The DataFetcher contract call reverts on Arbitrum:

  • Contract address: 0xC6BD82306943c0F3104296a46113ca0863723cBD
  • Method: batchFetchV3Data() (fixed from broken batchFetchAllData)
  • Error: execution reverted (likely contract is not deployed or wrong address)

Impact Chain:

  1. Cannot fetch real pool liquidity
  2. Falls back to placeholder values
  3. Profit calculations use placeholder data
  4. All calculations are mathematically invalid

From logs:

// pkg/scanner/market/scanner.go lines 145-150:
dataFetcherAddrStr := os.Getenv("CONTRACT_DATA_FETCHER")
if dataFetcherAddrStr == "" {
    dataFetcherAddrStr = "0x42105682F819891698E76cfE6897F10b75f8aabc" // Fallback
}

The fallback address (0x421056...) doesn't match the one in config (0xC6BD82...). Contract may not be deployed at this address.


BLOCKER #4: Profit Margin Calculation Invalid - HIGH

Impact: All profitable opportunities marked as unprofitable
Location: pkg/profitcalc/profit_calc.go lines 261-294
Problem:

profitMargin:-4.466551104702248e-09  (EXTREME NEGATIVE VALUE)
profitMargin:-38365.84743877249     (EXTREME NEGATIVE VALUE)

Log Evidence from actual opportunities:

rejectReason:negative profit after gas and slippage costs
estimatedProfitETH:0.000000
gasCostETH:0.000007
netProfitETH:-0.000007
profitMargin:-330178.9776420681

Root Cause: When amounts are zero or near-zero:

  1. All calculations use zero amounts
  2. Net profit = 0 - 0 - 0.000007 = NEGATIVE
  3. Profit margin = negative / 0 = UNDEFINED EXTREME VALUE
  4. Circuit breaker rejects it

Mathematical Issue:

  • Line 264: profitMargin := new(big.Float).Quo(netProfit, amountOut)
  • When amountOut is near-zero, Quo operation produces extreme values
  • Lines 270-283: Bounds checking is BACKWARDS:
    if profitMarginFloat > 1.0 {  // reject if > 100%
        opportunity.IsExecutable = false
    } else if profitMarginFloat < -1.0 {  // reject if < -100%
        opportunity.IsExecutable = false
    }
    
    The check rejects BOTH extreme values (correct) BUT the logic doesn't prevent -330,000 from being calculated

BLOCKER #5: Unknown Token Filtering - MEDIUM-HIGH

Impact: 95% of tokens cannot be priced
Location: pkg/profitcalc/profit_calc.go lines 152-161
Problem:

if arbitrageRoute == nil {
    opportunity.IsExecutable = false
    opportunity.RejectReason = fmt.Sprintf("unknown token - cannot price %s or %s", tokenA.Hex()[:10], tokenB.Hex()[:10])
    opportunity.Confidence = 0.05  // Lower confidence for unknown token
    return opportunity
}

Analysis: The PriceFeed doesn't have pricing for most Arbitrum tokens:

  • Only 6 tokens cached: logs: Loaded 6 tokens from cache
  • Arbitrum has 100+ tradeable tokens
  • Any token pair missing from PriceFeed = immediate rejection
  • Falls back to simplified spread calculation (~30 bps, unrealistic)

Impact:

  • Cannot determine actual profitability
  • Uses fallback calculation: profit = amountOut * 0.003 - amountIn * 0.003
  • This is mathematically incorrect for arbitrage

BLOCKER #6: Execution Code Path Unreachable - CRITICAL

Impact: Even if opportunities were valid, they wouldn't execute
Location: pkg/arbitrage/service.go (ExecuteArbitrage method)
Problem: The arbitrage execution chain is:

  1. Market scanner detects opportunity → SetOpportunityForwarder routes to MultiHopScanner
  2. MultiHopScanner.ScanForArbitrage finds paths → returns paths
  3. DEAD END: Nobody calls the executor with the paths

From logs and code review:

  • No evidence of arb.Executor.Execute() or arb.FlashExecutor.Execute() being called
  • The opportunities are detected but never forwarded to actual execution
  • ExecuteArbitrage method in service.go exists but is never invoked

Missing Link: The opportunity forwarder interface is set but:

// pkg/scanner/market/scanner.go line 86-88:
func (s *MarketScanner) SetOpportunityForwarder(forwarder OpportunityForwarder) {
    s.opportunityForwarder = forwarder
    s.logger.Info("✅ Opportunity forwarder set - will route to multi-hop scanner")
}

But nothing actually calls s.opportunityForwarder.ExecuteArbitrage() with valid opportunities.


BLOCKER #7: Minimum Profit Threshold Too High - MEDIUM

Impact: Rejects legitimate opportunities
Location: pkg/arbitrage/detection_engine.go line 188-190
Problem:

engine.config.MinProfitThreshold, _ = engine.decimalConverter.FromString("0.001", 18, "ETH")
// = 0.001 ETH minimum (~$2 at current prices)

Analysis: The minimum is actually reasonable (0.001 ETH = ~$2), BUT:

  1. Gas cost on Arbitrum = 100-300k gas @ 0.1-0.5 gwei = $0.0002-0.001
  2. Minimum 0.5% spread opportunity (across DEXs) = rare
  3. With ZERO amounts being detected, threshold becomes irrelevant

Sub-blocker: Configuration also has:

# config/arbitrum_production.yaml line 263:
min_profit_wei: 1000000000000000            # $2.00 minimum profit
min_roi_percent: 0.05                       # Minimum 0.05% ROI
min_confidence_score: 0.6                   # Minimum 60% confidence

But all detected opportunities have confidence: 0.1 (10%), so they fail this check.


BLOCKER #8: RPC BatchFetch Contract Wrong/Not Deployed - MEDIUM

Impact: Cannot fetch pool state in batches (heavy RPC usage)
Location: pkg/datafetcher/batch_fetcher.go
Problem:

  • Config points to 0xC6BD82306943c0F3104296a46113ca0863723cBD
  • Code fallback: 0x42105682F819891698E76cfE6897F10b75f8aabc
  • Neither address works (contract reverts or doesn't exist)
  • System falls back to individual RPC calls for each pool

Impact:

  • RPC rate limits hit immediately
  • Cannot fetch data for 314 cached pools
  • System stalls on rate limiting

BLOCKER #9: No Live Execution Framework Integration - CRITICAL

Impact: Flash loan executor never triggers
Location: pkg/arbitrage/flash_executor.go and pkg/arbitrage/executor.go
Problem: Flash executors are initialized but NEVER called:

// pkg/arbitrage/service.go line 42-43:
flashExecutor       *FlashSwapExecutor
liveFramework       *LiveExecutionFramework

Both are initialized in NewArbitrageService() but:

  • No goroutines call their Execute methods
  • No event listeners forward opportunities to them
  • They sit dormant while opportunities pass by

Missing: The actual execution loop that should:

  1. Listen for valid opportunities
  2. Call flashExecutor.ExecuteFlashSwap()
  3. Monitor transaction result
  4. Track profit/loss

Instead, the code only logs opportunities and never executes.


BLOCKER #10: Event Parser Extracts Zero Amounts - HIGH

Impact: All swap events show 0 token amounts
Location: pkg/arbitrum/parser/core.go or pkg/events/parser.go
Problem: Swap events are being parsed with ZERO amounts when they contain data:

Log entry shows: "Amount Out: 1611.982004 tokens"
But parsed as: amount0Out:0, amount1Out:0

Evidence from logs:

Amount In: 0.000000 tokens
Amount Out: 0.000000 tokens

Yet the same transaction logs show real amounts being swapped. The parser is either:

  1. Extracting wrong event fields
  2. Not handling token decimals correctly
  3. Using wrong event signature for Swap events
  4. Losing data during amount sign conversion

This is the FIRST failure point in the entire pipeline.


SECONDARY ISSUES

Issue A: Pool Blacklist Prevents Scanning

  • Valid pools are being blacklisted due to transient RPC errors
  • Once blacklisted, never attempted again
  • System self-limits to fewer and fewer pools

Issue B: Configuration Mismatch

  • Multiple min profit thresholds at different levels
  • Different enabled/disabled features in different configs
  • Some features marked as DISABLED in code but ENABLED in config

Issue C: No Actual Wallet Funding Check

  • Bot generates keys but never verifies wallet has funds
  • Tries to execute trades with 0 balance wallet
  • Transactions fail but error handling swallows the message

Issue D: Rate Limiting Too Aggressive

  • Max 5 concurrent RPC calls (config/arbitrum_production.yaml line 336)
  • 20 requests/second on growth plan (very conservative)
  • System rate limits itself before hitting Chainstack limits

ROOT CAUSE ANALYSIS

The system has ARCHITECTURAL SEPARATION:

  1. Detection Pipeline (WORKING): Finds opportunities
  2. Data Fetch Pipeline (BROKEN): Cannot get pool state
  3. Profit Calculation (BROKEN): Uses invalid amounts
  4. Execution Pipeline (DISCONNECTED): Never triggered

Why No Executions:

Event Parsed → Amounts = ZERO → Profit Rejected → Execution Never Attempted
                ↑
          ROOT CAUSE

The token amount extraction is broken at the event parser level. Everything downstream (profit calc, execution decisions) becomes irrelevant because the input data is invalid.


RECOMMENDATIONS (Priority Order)

P0: Fix Event Parser Amount Extraction

  • Review pkg/events/parser.go - validate Swap event parsing
  • Check token decimal handling in amount conversion
  • Verify event signature matching (Uniswap V3 Swap vs V2)
  • Test with real swap transactions to verify amount extraction

P1: Connect Token Graph to Pool Cache

  • Link the 314 cached pools to the token graph
  • Implement pool discovery loop that updates token graph
  • Verify graph has minimum 20+ tokens with 50+ pools

P2: Fix Batch Fetcher Contract

  • Deploy actual DataFetcher contract or find correct address
  • Test batchFetchV3Data() call on Arbitrum
  • Implement fallback to individual RPC calls with proper caching

P3: Connect Execution Pipeline

  • Add event listener that forwards VALID opportunities to executor
  • Implement execution goroutine
  • Add transaction monitoring and result tracking

P4: Verify Wallet Funding

  • Check wallet balance before any execution attempt
  • Require minimum balance (0.05 ETH) for flash loan execution
  • Add pre-flight validation

TESTING CHECKLIST

  • Swap event parser extracts amounts correctly
  • Profit calculator receives non-zero amounts
  • 50+ opportunities marked as isExecutable:true
  • TokenGraph has 20+ tokens, 50+ pool connections
  • DataFetcher contract calls succeed
  • First profitable arbitrage executes successfully
  • Transaction confirmed on-chain
  • Profit > gas cost

ESTIMATED FIX EFFORT

Blocker Effort Time
#1 - Event Parser Fix 2-4 hours Debug + unit test + integration test
#2 - Token Graph Link 1-2 hours Wire up pool cache to graph
#3 - Batch Fetcher 2-3 hours Deploy/fix contract or remove
#6 - Execution Connection 2-3 hours Wire event → executor pipeline
#10 - Validation 1-2 hours Add amount validation in parser
Total 8-14 hours Full system operational

Expected Outcome: System should achieve first profitable execution within 24 hours of fixing blockers #1-2.