Sessions 5-7a: 955 tests, deployment ready

src/services/mlbGrader.js

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+const HITTING_STATS = [
+  'hits', 'total_bases', 'home_runs', 'rbis', 'runs_scored',
+  'strikeouts_batter', 'walks', 'stolen_bases',
+];
+
+const PITCHING_STATS = [
+  'strikeouts', 'earned_runs', 'outs_recorded', 'walks_allowed',
+  'hits_allowed', 'pitches_thrown',
+];
+
+const ALL_MLB_STATS = [...HITTING_STATS, ...PITCHING_STATS];
+
+function isMlbStatType(statType) {
+  return ALL_MLB_STATS.includes(statType);
+}
+
+function calculateMlbEdge(playerAvg, line, direction) {
+  if (playerAvg == null || line == null) return 0;
+  if (direction === 'over') {
+    return ((playerAvg - line) / line) * 100;
+  }
+  // under
+  return ((line - playerAvg) / line) * 100;
+}
+
+function gradeMlbProp({ player, stat_type, line, direction, seasonAvg, recentAvg, killConditions = [] }) {
+  if (!isMlbStatType(stat_type)) {
+    return { grade: 'D', confidence: 30, edge_pct: 0, composite: 0 };
+  }
+
+  const seasonEdge = calculateMlbEdge(seasonAvg, line, direction);
+  const recentEdge = calculateMlbEdge(recentAvg, line, direction);
+
+  // Weighted composite: 60% season, 40% recent
+  const edge_pct = Math.round((seasonEdge * 0.6 + recentEdge * 0.4) * 100) / 100;
+
+  // Grade thresholds based on edge
+  let grade;
+  if (edge_pct >= 5) {
+    grade = 'A';
+  } else if (edge_pct >= 3) {
+    grade = 'B';
+  } else if (edge_pct >= 1) {
+    grade = 'C';
+  } else {
+    grade = 'D';
+  }
+
+  // Confidence based on edge magnitude
+  let confidence;
+  if (grade === 'A') {
+    confidence = Math.min(95, 80 + Math.floor(edge_pct));
+  } else if (grade === 'B') {
+    confidence = Math.min(79, 65 + Math.floor(edge_pct));
+  } else if (grade === 'C') {
+    confidence = Math.min(64, 50 + Math.floor(edge_pct * 2));
+  } else {
+    confidence = Math.max(30, 45 + Math.floor(edge_pct));
+  }
+
+  // Kill condition penalty: cap at C and reduce confidence by 15 per condition
+  if (killConditions.length > 0) {
+    if (grade === 'A' || grade === 'B') {
+      grade = 'C';
+    }
+    confidence -= killConditions.length * 15;
+  }
+
+  confidence = Math.max(30, Math.min(95, confidence));
+
+  const composite = Math.round(edge_pct * 100) / 100;
+
+  return { grade, confidence, edge_pct, composite };
+}
+
+module.exports = { gradeMlbProp, calculateMlbEdge, isMlbStatType, HITTING_STATS, PITCHING_STATS, ALL_MLB_STATS };