fix(multicall): resolve critical multicall parsing corruption issues

- Added comprehensive bounds checking to prevent buffer overruns in multicall parsing
- Implemented graduated validation system (Strict/Moderate/Permissive) to reduce false positives
- Added LRU caching system for address validation with 10-minute TTL
- Enhanced ABI decoder with missing Universal Router and Arbitrum-specific DEX signatures
- Fixed duplicate function declarations and import conflicts across multiple files
- Added error recovery mechanisms with multiple fallback strategies
- Updated tests to handle new validation behavior for suspicious addresses
- Fixed parser test expectations for improved validation system
- Applied gofmt formatting fixes to ensure code style compliance
- Fixed mutex copying issues in monitoring package by introducing MetricsSnapshot
- Resolved critical security vulnerabilities in heuristic address extraction
- Progress: Updated TODO audit from 10% to 35% complete

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

pkg/arbitrum/discovery/arbitrage.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+
 	"github.com/fraktal/mev-beta/internal/logger"
 	exchangeMath "github.com/fraktal/mev-beta/pkg/math"
 )

pkg/arbitrum/discovery/core.go

@@ -11,9 +11,10 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethclient"
+	"gopkg.in/yaml.v3"
+
 	"github.com/fraktal/mev-beta/internal/logger"
 	exchangeMath "github.com/fraktal/mev-beta/pkg/math"
-	"gopkg.in/yaml.v3"
 )
 
 // MarketDiscovery manages pool discovery and market building

pkg/arbitrum/discovery/pool_state.go

@@ -3,12 +3,14 @@ package discovery
 import (
 	"context"
 	"fmt"
+	"math"
 	"math/big"
 	"sync"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/ethclient"
+
 	"github.com/fraktal/mev-beta/internal/logger"
 )
 
@@ -162,7 +164,12 @@ func (psm *PoolStateManager) updateUniswapV3PoolState(ctx context.Context, pool
 		volumeSeed = (volumeSeed << 8) | uint64(poolAddrBytes[(i+4)%len(poolAddrBytes)])
 	}
 	// Use big.Int to avoid overflow
-	volumeBig := big.NewInt(int64(volumeSeed))
+	var volumeBig *big.Int
+	if volumeSeed > math.MaxInt64 {
+		volumeBig = big.NewInt(math.MaxInt64)
+	} else {
+		volumeBig = big.NewInt(int64(volumeSeed))
+	}
 	volumeBig.Mod(volumeBig, big.NewInt(1000000000000000000)) // Mod by 1 ETH
 	volumeBig.Mul(volumeBig, big.NewInt(100))                 // Scale to 100 ETH max
 	pool.Volume24h = volumeBig
@@ -202,7 +209,12 @@ func (psm *PoolStateManager) updateBalancerPoolState(ctx context.Context, pool *
 		volumeSeed = (volumeSeed << 8) | uint64(poolAddrBytes[(i*2)%len(poolAddrBytes)])
 	}
 	// Use big.Int to avoid overflow
-	volumeBig := big.NewInt(int64(volumeSeed))
+	var volumeBig *big.Int
+	if volumeSeed > math.MaxInt64 {
+		volumeBig = big.NewInt(math.MaxInt64)
+	} else {
+		volumeBig = big.NewInt(int64(volumeSeed))
+	}
 	volumeBig.Mod(volumeBig, big.NewInt(1000000000000000000)) // Mod by 1 ETH
 	volumeBig.Mul(volumeBig, big.NewInt(50))                  // Scale to 50 ETH max
 	pool.Volume24h = volumeBig
@@ -225,8 +237,24 @@ func (psm *PoolStateManager) updateCurvePoolState(ctx context.Context, pool *Poo
 		addrModifier += uint64(poolAddrBytes[i])
 	}
 
-	reserve0.Mul(reserve0, big.NewInt(int64(addrModifier%1000000)))
-	reserve1.Mul(reserve1, big.NewInt(int64((addrModifier*2)%1000000)))
+	// Convert uint64 to int64 safely
+	modValue := addrModifier % 1000000
+	var reserveMultiplier *big.Int
+	if modValue > math.MaxInt64 {
+		reserveMultiplier = big.NewInt(math.MaxInt64)
+	} else {
+		reserveMultiplier = big.NewInt(int64(modValue))
+	}
+	reserve0.Mul(reserve0, reserveMultiplier)
+	// Convert uint64 to int64 safely for reserve multiplier
+	multiplierValue := (addrModifier * 2) % 1000000
+	var reserve1Multiplier *big.Int
+	if multiplierValue > math.MaxInt64 {
+		reserve1Multiplier = big.NewInt(math.MaxInt64)
+	} else {
+		reserve1Multiplier = big.NewInt(int64(multiplierValue))
+	}
+	reserve1.Mul(reserve1, reserve1Multiplier)
 
 	pool.Reserve0 = reserve0
 	pool.Reserve1 = reserve1
@@ -239,7 +267,12 @@ func (psm *PoolStateManager) updateCurvePoolState(ctx context.Context, pool *Poo
 		volumeSeed = (volumeSeed << 8) | uint64(poolAddrBytes[(i*3)%len(poolAddrBytes)])
 	}
 	// Use big.Int to avoid overflow
-	volumeBig := big.NewInt(int64(volumeSeed))
+	var volumeBig *big.Int
+	if volumeSeed > math.MaxInt64 {
+		volumeBig = big.NewInt(math.MaxInt64)
+	} else {
+		volumeBig = big.NewInt(int64(volumeSeed))
+	}
 	volumeBig.Mod(volumeBig, big.NewInt(1000000000000000000)) // Mod by 1 ETH
 	volumeBig.Mul(volumeBig, big.NewInt(20))                  // Scale to 20 ETH max
 	pool.Volume24h = volumeBig