Sessions 5-7a: 955 tests, deployment ready

src/services/processing/SteamDetector.js

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+/**
+ * Steam detection — flags lines that move 1+ points in <2 hours.
+ *
+ * Inputs: a stream of { prop_key, book, line, odds, recorded_at } samples.
+ * The orchestrator persists samples to `line_history` and calls check() with
+ * the rolling window for tonight's slate.
+ */
+
+const TWO_HOURS_MS = 2 * 60 * 60_000;
+const STEAM_THRESHOLD = 1;
+
+/**
+ * @param {Array<{prop_key:string, book:string, line:number, odds:number|null, recorded_at:string|number}>} samples
+ * @returns {Array<{prop_key:string, book:string, from_line:number, to_line:number, delta:number, duration_ms:number, started_at:string, ended_at:string}>}
+ */
+function check(samples) {
+  if (!Array.isArray(samples) || samples.length === 0) return [];
+
+  // Group samples by prop_key + book and sort chronologically.
+  const buckets = new Map();
+  for (const s of samples) {
+    const k = `${s.prop_key}|${s.book}`;
+    if (!buckets.has(k)) buckets.set(k, []);
+    buckets.get(k).push({ ...s, t: new Date(s.recorded_at).getTime() });
+  }
+
+  const flags = [];
+  for (const [key, rows] of buckets.entries()) {
+    rows.sort((a, b) => a.t - b.t);
+    for (let i = 0; i < rows.length; i++) {
+      // Walk forward in time and stop as soon as the gap > window.
+      const start = rows[i];
+      for (let j = i + 1; j < rows.length; j++) {
+        const end = rows[j];
+        if (end.t - start.t > TWO_HOURS_MS) break;
+        const delta = end.line - start.line;
+        if (Math.abs(delta) >= STEAM_THRESHOLD) {
+          const [propKey, book] = key.split('|');
+          flags.push({
+            prop_key: propKey,
+            book,
+            from_line: start.line,
+            to_line: end.line,
+            delta,
+            duration_ms: end.t - start.t,
+            started_at: new Date(start.t).toISOString(),
+            ended_at: new Date(end.t).toISOString(),
+          });
+          break; // one flag per starting sample
+        }
+      }
+    }
+  }
+  return flags;
+}
+
+module.exports = { check, TWO_HOURS_MS, STEAM_THRESHOLD };