Feat: Add Sniper Reversal strategy

lib/strategies/sniper-reversal.js

@@ -0,0 +1,62 @@
+import { BaseStrategy } from './base.js';
+
+export class SniperReversalStrategy extends BaseStrategy {
+  constructor(config = {}) {
+    super('sniper-reversal', {
+      triggerPct: config.triggerPct || 95, // Bet against a 95% favorite
+      minsLeft: config.minsLeft || 3,      // Only in the last 3 minutes
+      betSize: config.betSize || 1,        // Cheap lotto tickets
+      cooldownMs: config.cooldownMs || 60000,
+      ...config
+    });
+    
+    this.lastTradeTime = 0;
+    this.lastTradeTicker = null;
+  }
+
+  evaluate(state) {
+    if (!state || !this.enabled || !state.closeTime) return null;
+
+    const now = Date.now();
+    if (now - this.lastTradeTime < this.config.cooldownMs) return null;
+    if (state.ticker === this.lastTradeTicker) return null;
+
+    const timeLeftMs = new Date(state.closeTime).getTime() - now;
+    const minsLeft = timeLeftMs / 60000;
+
+    // Only strike in the final minutes
+    if (minsLeft > this.config.minsLeft || minsLeft <= 0) return null;
+
+    const { yesPct, noPct } = state;
+    const trigger = this.config.triggerPct;
+
+    let signal = null;
+
+    if (yesPct >= trigger && noPct > 0) {
+      signal = {
+        strategy: this.name,
+        side: 'no',
+        price: noPct,
+        size: this.config.betSize,
+        reason: `Buzzer beater No at ${noPct}¢ (Yes is ${yesPct}%) with ${minsLeft.toFixed(1)}m left`,
+        ticker: state.ticker
+      };
+    } else if (noPct >= trigger && yesPct > 0) {
+      signal = {
+        strategy: this.name,
+        side: 'yes',
+        price: yesPct,
+        size: this.config.betSize,
+        reason: `Buzzer beater Yes at ${yesPct}¢ (No is ${noPct}%) with ${minsLeft.toFixed(1)}m left`,
+        ticker: state.ticker
+      };
+    }
+
+    if (signal) {
+      this.lastTradeTime = now;
+      this.lastTradeTicker = state.ticker;
+    }
+
+    return signal;
+  }
+}