Add Redis rolling stats for flow packets and z-score driven classifiers

services/compute/tests/rolling-stats.test.ts

@@ -0,0 +1,24 @@
+import { describe, expect, test } from "bun:test";
+import { computeSnapshot, computeStats } from "../src/rolling-stats";
+
+describe("rolling stats helpers", () => {
+  test("computeStats handles empty baseline", () => {
+    const stats = computeStats([]);
+    expect(stats.count).toBe(0);
+    expect(stats.mean).toBe(0);
+    expect(stats.stddev).toBe(0);
+  });
+
+  test("computeStats calculates mean and stddev", () => {
+    const stats = computeStats([10, 12, 14]);
+    expect(stats.count).toBe(3);
+    expect(stats.mean).toBe(12);
+    expect(stats.stddev).toBeCloseTo(1.633, 3);
+  });
+
+  test("computeSnapshot calculates z-score against baseline", () => {
+    const snapshot = computeSnapshot([10, 12, 14], 15);
+    expect(snapshot.baselineCount).toBe(3);
+    expect(snapshot.zscore).toBeCloseTo(1.84, 2);
+  });
+});