[Phase 3] Arbitrage Detection

---
name: "Phase 3: Arbitrage Detection"
about: Find guaranteed profit opportunities across bookmakers
title: "[Phase 3] Arbitrage Detection"
labels: enhancement, phase-3, analytics, advanced
assignees: ''
---

## Overview
Detect arbitrage opportunities (guaranteed profit by betting all sides across different bookmakers) and middle opportunities (chance to win both sides of a bet).

## Business Value
- **Guaranteed Profit**: Arbitrage is risk-free money
- **Market Inefficiency**: Shows when bookmakers disagree significantly
- **User Value**: Premium feature for advanced users
- **Real-time Alerts**: Time-sensitive opportunities

## Technical Requirements

### Database Changes
```prisma
model ArbitrageOpportunity {
  id                String   @id @default(dbgenerated("gen_random_uuid()")) @db.Uuid
  gameId            String   @map("game_id") @db.Uuid
  detectedAt        DateTime @default(now()) @map("detected_at") @db.Timestamptz(6)
  expiresAt         DateTime @map("expires_at") @db.Timestamptz(6)
  
  // Opportunity type
  arbType           String   @map("arb_type") @db.VarChar(20)  // two-way, three-way, middle
  marketType        String   @map("market_type") @db.VarChar(20)
  
  // Profitability
  profitPercentage  Decimal  @map("profit_percentage") @db.Decimal(5,2)
  stake             Decimal  @db.Decimal(10,2)
  expectedProfit    Decimal  @map("expected_profit") @db.Decimal(10,2)
  
  // Legs
  legs              Json  // [{bookmaker, selection, odds, stake, toWin}]
  
  // Risk assessment
  riskLevel         String   @map("risk_level") @db.VarChar(20)  // low, medium, high
  limitRisk         Boolean  @map("limit_risk")  // Risk of hitting betting limits
  oddsDrift         Decimal? @map("odds_drift") @db.Decimal(5,2)  // How fast odds moving
  
  // Status
  status            String   @default("active") @db.VarChar(20)
  takenAt           DateTime? @map("taken_at") @db.Timestamptz(6)
  userId            String?  @map("user_id") @db.Uuid
  actualProfit      Decimal? @map("actual_profit") @db.Decimal(10,2)
  
  game Game @relation(fields: [gameId], references: [id])
  user User? @relation(fields: [userId], references: [id])
  
  @@index([gameId])
  @@index([status])
  @@index([profitPercentage])
  @@index([detectedAt])
  @@map("arbitrage_opportunities")
}
```

### Backend Services

**File**: `src/services/arbitrage.service.ts`
```typescript
class ArbitrageService {
  async scanForArbitrage(): Promise<Opportunity[]>
  async calculateStakes(odds: number[], totalStake: number): Promise<number[]>
  async assessRisk(opportunity: Opportunity): Promise<RiskAssessment>
  async trackOpportunity(id: string): Promise<void>
  async notifyUsers(opportunity: Opportunity): Promise<void>
}
```

### Arbitrage Detection Algorithm

**Two-Way Arbitrage** (moneyline, spread, total):
```typescript
function detectTwoWayArbitrage(game: Game, marketType: string): Opportunity | null {
  const allOdds = getOddsForMarket(game, marketType);
  
  // Find best odds for each side
  const bestHome = Math.max(...allOdds.map(o => o.homePrice));
  const bestAway = Math.max(...allOdds.map(o => o.awayPrice));
  
  // Convert to implied probabilities
  const homeProb = toImpliedProbability(bestHome);
  const awayProb = toImpliedProbability(bestAway);
  
  // Check if arbitrage exists
  const totalProb = homeProb + awayProb;
  
  if (totalProb < 1.0) {
    // Arbitrage exists!
    const profitPct = ((1 / totalProb) - 1) * 100;
    
    return {
      type: 'two-way',
      profitPercentage: profitPct,
      legs: [
        { side: 'home', odds: bestHome, bookmaker: findBookmaker(allOdds, 'home', bestHome) },
        { side: 'away', odds: bestAway, bookmaker: findBookmaker(allOdds, 'away', bestAway) }
      ]
    };
  }
  
  return null;
}
```

**Stake Calculation** (to guarantee equal profit):
```typescript
function calculateOptimalStakes(odds: number[], totalStake: number): number[] {
  const probs = odds.map(o => toImpliedProbability(o));
  const totalProb = probs.reduce((a, b) => a + b);
  
  return probs.map(prob => (prob / totalProb) * totalStake);
}

// Example: $100 total stake, odds: +120, -110
// Home stake: $47.62, Away stake: $52.38
// Both outcomes win: ~$4.50 profit
```

**Middle Detection** (win both sides):
```typescript
function detectMiddle(game: Game): Middle | null {
  const allSpreads = getSpreadOdds(game);
  
  // Find spread discrepancies
  for (const spread1 of allSpreads) {
    for (const spread2 of allSpreads) {
      if (spread1.bookmaker === spread2.bookmaker) continue;
      
      const gap = Math.abs(spread1.homeSpread - spread2.awaySpread);
      
      // Middle opportunity if gap >= 2 points
      if (gap >= 2.0) {
        const middleProb = estimateMiddleProbability(gap);
        
        if (middleProb > 0.10) {  // 10%+ chance both win
          return {
            type: 'middle',
            spread1: spread1,
            spread2: spread2,
            gap: gap,
            middleProb: middleProb,
            expectedValue: calculateMiddleEV(spread1, spread2, middleProb)
          };
        }
      }
    }
  }
  
  return null;
}
```

### Real-time Scanning

**Scheduled Job**: Every 30 seconds
- Scan all games with multiple bookmaker odds
- Detect arbitrage and middle opportunities
- Calculate profitability
- Assess risk level
- Store in database
- Trigger notifications

**Performance Optimization**:
```typescript
// Use parallel processing for speed
async function scanAllGames(): Promise<Opportunity[]> {
  const upcomingGames = await getGamesWithOdds();
  
  const opportunities = await Promise.all(
    upcomingGames.map(game => 
      Promise.all([
        detectTwoWayArbitrage(game, 'h2h'),
        detectTwoWayArbitrage(game, 'spreads'),
        detectTwoWayArbitrage(game, 'totals'),
        detectMiddle(game)
      ])
    )
  );
  
  return opportunities.flat().filter(o => o !== null);
}
```

### Risk Assessment

```typescript
function assessRisk(opportunity: Opportunity): RiskAssessment {
  let risk = 'low';
  const factors = [];
  
  // Check if odds are changing rapidly
  if (opportunity.oddsDrift > 5.0) {
    risk = 'medium';
    factors.push('Fast-moving odds');
  }
  
  // Check if bookmakers involved are reliable
  const suspiciousBooks = ['unknown_book', 'new_book'];
  if (opportunity.legs.some(leg => suspiciousBooks.includes(leg.bookmaker))) {
    risk = 'high';
    factors.push('Unreliable bookmaker');
  }
  
  // Check profit margin (too good to be true?)
  if (opportunity.profitPercentage > 10.0) {
    risk = 'high';
    factors.push('Suspiciously high profit');
  }
  
  // Check time to game start
  const minutesToStart = getMinutesToStart(opportunity.gameId);
  if (minutesToStart < 15) {
    risk = 'medium';
    factors.push('Very close to start time');
  }
  
  return { risk, factors, limitRisk: estimateLimitRisk(opportunity) };
}
```

### API Endpoints
- `GET /api/arbitrage/live` - Current arbitrage opportunities
- `GET /api/arbitrage/history` - Historical arbitrage opportunities
- `GET /api/arbitrage/:id` - Details for specific opportunity
- `POST /api/arbitrage/:id/take` - Mark opportunity as taken
- `GET /api/arbitrage/stats` - User's arbitrage stats
- `GET /api/arbitrage/calculator` - Arbitrage calculator tool

### Frontend Components

**Arbitrage Dashboard**: `ArbitrageDashboard.tsx`
```
┌────────────────────────────────────────────────┐
│ 🎯 Live Arbitrage Opportunities               │
├────────────────────────────────────────────────┤
│ Lakers vs Warriors | NBA                      │
│ Profit: 3.2% | Stake: $1000 | Win: $32       │
│ ├─ DraftKings: Lakers -5.5 @ -110 ($523)     │
│ └─ FanDuel: Warriors +6.5 @ -105 ($477)      │
│ [VIEW DETAILS] [BET NOW]                      │
├────────────────────────────────────────────────┤
│ ... 4 more opportunities ...                  │
└────────────────────────────────────────────────┘
```

**Arbitrage Calculator**: `ArbitrageCalculator.tsx`
- Input: Total stake, odds for each side
- Output: Individual stakes, guaranteed profit
- Support for 2-way and 3-way bets
- Export bet instructions

**Middle Finder**: `MiddleFinder.tsx`
- Show all middle opportunities
- Calculate both-win probability
- Expected value calculation
- Historical middle success rate

**Alert Settings**: `ArbitrageAlerts.tsx`
- Minimum profit percentage
- Maximum stake
- Preferred bookmakers
- Sports to monitor
- Push notification settings

### Notifications

**Real-time Alerts**:
- Browser push notifications
- Email for high-value arbs (>5% profit)
- SMS for premium users (optional)
- Webhook for integration with other tools

**Alert Format**:
```
🎯 ARBITRAGE: 4.2% Profit Available
Lakers vs Warriors - NBA
Stake $1000 → Win $42
Act now - odds changing!
[VIEW NOW]
```

## Acceptance Criteria
- [ ] Database migration completed
- [ ] Arbitrage detection algorithm implemented
- [ ] Real-time scanning every 30 seconds
- [ ] Stake calculator working correctly
- [ ] Risk assessment accurate
- [ ] Dashboard showing live opportunities
- [ ] Push notifications functional
- [ ] Calculator tool available
- [ ] API endpoints documented
- [ ] Unit tests for detection logic
- [ ] Load testing for scanning performance

## Dependencies
- Odds sync with multiple bookmakers (minimum 5)
- Fast odds updates (every 1-2 minutes)
- Market consensus calculations (Phase 2)
- Push notification service

## Estimated Effort
- Backend: 8 days
- Frontend: 6 days
- Testing & Optimization: 4 days
- **Total: 18 days**

## Success Metrics
- Detect 5-10 arbitrage opportunities per day
- 95%+ accuracy (no false positives)
- Alerts delivered within 10 seconds of detection
- Users successfully execute 50%+ of alerted arbs
- Average profit 2-5% per opportunity

## Compliance & Legal

**Important Considerations**:
- Arbitrage is legal but bookmakers may limit accounts
- Disclose risks to users
- Some bookmakers prohibit arbitrage in ToS
- Recommend using different bookmakers for each leg
- Track limit/ban reports from users

## Future Enhancements
- Machine learning for opportunity prediction
- Historical arbitrage ROI tracking
- Automated bet placement (with user approval)
- Cross-sport arbitrage detection
- Arbitrage portfolio optimization
- "Arb protection" insurance feature


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[Phase 3] Arbitrage Detection #9

name: "Phase 3: Arbitrage Detection"
about: Find guaranteed profit opportunities across bookmakers
title: "[Phase 3] Arbitrage Detection"
labels: enhancement, phase-3, analytics, advanced
assignees: ''

Overview

Business Value

Technical Requirements

Database Changes

Backend Services

Arbitrage Detection Algorithm

Real-time Scanning

Risk Assessment

API Endpoints

Frontend Components

Notifications

Acceptance Criteria

Dependencies

Estimated Effort

Success Metrics

Compliance & Legal

Future Enhancements

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

[Phase 3] Arbitrage Detection #9

Description

name: "Phase 3: Arbitrage Detection" about: Find guaranteed profit opportunities across bookmakers title: "[Phase 3] Arbitrage Detection" labels: enhancement, phase-3, analytics, advanced assignees: ''

Overview

Business Value

Technical Requirements

Database Changes

Backend Services

Arbitrage Detection Algorithm

Real-time Scanning

Risk Assessment

API Endpoints

Frontend Components

Notifications

Acceptance Criteria

Dependencies

Estimated Effort

Success Metrics

Compliance & Legal

Future Enhancements

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions

name: "Phase 3: Arbitrage Detection"
about: Find guaranteed profit opportunities across bookmakers
title: "[Phase 3] Arbitrage Detection"
labels: enhancement, phase-3, analytics, advanced
assignees: ''