Sessions 5-7a: 955 tests, deployment ready

src/services/intelligence/consistencyScore.js

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+/**
+ * Consistency score — how predictable is this player for this stat?
+ *
+ *   cv = stddev / mean
+ *
+ * Coefficient of variation collapses sample-size differences and lets us
+ * compare a 25-point scorer with low variance to a 12-point scorer with
+ * the same absolute variance. Lower cv = more reliable.
+ *
+ * The consistency score modifies Engine 2's confidence. An "elite"
+ * consistency player gets a tighter projection range; a "boom_bust"
+ * player gets a wider one.
+ */
+
+const gameLogService = require('./gameLogService');
+
+function statFromGameLog(row, statType) {
+  if (!row) return null;
+  switch (statType) {
+    case 'pts_reb_ast':
+      return (Number(row.points) || 0) + (Number(row.rebounds) || 0) + (Number(row.assists) || 0);
+    case 'pts_reb':
+      return (Number(row.points) || 0) + (Number(row.rebounds) || 0);
+    case 'pts_ast':
+      return (Number(row.points) || 0) + (Number(row.assists) || 0);
+    case 'reb_ast':
+      return (Number(row.rebounds) || 0) + (Number(row.assists) || 0);
+    case 'stl_blk':
+      return (Number(row.steals) || 0) + (Number(row.blocks) || 0);
+    default: {
+      const v = Number(row[statType]);
+      return Number.isFinite(v) ? v : null;
+    }
+  }
+}
+
+function classify(cv) {
+  if (cv < 0.15) return { consistency: 'elite', score: 1.0 };
+  if (cv < 0.30) return { consistency: 'reliable', score: 0.7 };
+  if (cv < 0.50) return { consistency: 'volatile', score: 0.4 };
+  return { consistency: 'boom_bust', score: 0.1 };
+}
+
+function statsFor(values) {
+  const clean = values.filter((v) => Number.isFinite(v));
+  if (clean.length < 2) return null;
+  const mean = clean.reduce((a, b) => a + b, 0) / clean.length;
+  if (mean === 0) return null;
+  const variance = clean.reduce((s, v) => s + (v - mean) ** 2, 0) / (clean.length - 1);
+  const stddev = Math.sqrt(variance);
+  return { mean, stddev, cv: stddev / Math.abs(mean), games: clean.length };
+}
+
+async function getConsistency(input = {}) {
+  const { playerName, sport, statType, gameLogs: providedLogs } = input;
+  const logs = providedLogs || await gameLogService.getGameLogs(playerName, sport, 20);
+  if (!logs || logs.length < 2) {
+    return { consistency: 'unknown', score: null, games: logs?.length ?? 0 };
+  }
+  const values = logs.map((row) => statFromGameLog(row, statType)).filter((v) => v != null);
+  const s = statsFor(values);
+  if (!s) return { consistency: 'unknown', score: null, games: values.length };
+  return { ...s, ...classify(s.cv) };
+}
+
+module.exports = { getConsistency, classify, statsFor, statFromGameLog };