chore: import upstream snapshot with attribution

tests/unit/db/per-engine-breakdown-analytics.test.ts

@@ -0,0 +1,173 @@
+/**
+ * TDD: per-engine breakdown persistence.
+ *
+ * A real stacked run records ONE compression_analytics row (engine = stats.engine ??
+ * mode, e.g. "stacked") — so per-engine savings were previously lost. The
+ * compression_engine_breakdown table stores one row per engine in the stacked
+ * pipeline, and getPerEngineAnalytics aggregates breakdown + legacy single-engine
+ * rows (deduped by request_id, no double counting).
+ *
+ * DB isolation mirrors tests/unit/db/per-engine-analytics.test.ts.
+ */
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-ceb-analytics-"));
+const originalDataDir = process.env.DATA_DIR;
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const core = await import("../../../src/lib/db/core.ts");
+core.resetDbInstance();
+
+const { insertCompressionAnalyticsRow, insertCompressionEngineBreakdown, getPerEngineAnalytics } =
+  await import("../../../src/lib/db/compressionAnalytics.ts");
+
+function resetDb(): void {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+  fs.mkdirSync(TEST_DATA_DIR, { recursive: true });
+}
+
+test.beforeEach(() => {
+  resetDb();
+});
+
+test.after(() => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+  if (originalDataDir === undefined) delete process.env.DATA_DIR;
+  else process.env.DATA_DIR = originalDataDir;
+});
+
+test("per-engine breakdown from a stacked run is attributed to each engine", () => {
+  const now = new Date().toISOString();
+
+  // One aggregate row for the stacked request (engine column = mode, NOT per-engine).
+  insertCompressionAnalyticsRow({
+    timestamp: now,
+    mode: "stacked",
+    engine: "stacked",
+    request_id: "req-stacked-1",
+    original_tokens: 1000,
+    compressed_tokens: 700,
+    tokens_saved: 300,
+  });
+
+  // Per-engine breakdown for that same request: rtk (1000→800) then headroom (800→700).
+  insertCompressionEngineBreakdown([
+    {
+      timestamp: now,
+      request_id: "req-stacked-1",
+      engine: "rtk",
+      original_tokens: 1000,
+      compressed_tokens: 800,
+      tokens_saved: 200,
+    },
+    {
+      timestamp: now,
+      request_id: "req-stacked-1",
+      engine: "headroom",
+      original_tokens: 800,
+      compressed_tokens: 700,
+      tokens_saved: 100,
+    },
+  ]);
+
+  const headroom = getPerEngineAnalytics("headroom");
+  assert.equal(headroom.runs, 1, "headroom ran once (inside the stacked pipeline)");
+  assert.equal(headroom.tokensSaved, 100, "headroom's own contribution");
+  // avg = round(((800-700)/800)*1000)/10 = round(125)/10 = 12.5
+  assert.equal(headroom.avgSavingsPercent, 12.5);
+
+  const rtk = getPerEngineAnalytics("rtk");
+  assert.equal(rtk.runs, 1);
+  assert.equal(rtk.tokensSaved, 200);
+});
+
+test("legacy single-engine rows still count (no breakdown present)", () => {
+  const now = new Date().toISOString();
+  insertCompressionAnalyticsRow({
+    timestamp: now,
+    mode: "aggressive",
+    engine: "aggressive",
+    request_id: "req-single",
+    original_tokens: 500,
+    compressed_tokens: 400,
+    tokens_saved: 100,
+  });
+
+  const aggressive = getPerEngineAnalytics("aggressive");
+  assert.equal(aggressive.runs, 1, "single-engine run counted via the legacy engine column");
+  assert.equal(aggressive.tokensSaved, 100);
+});
+
+test("breakdown + legacy combine for the same engine without double counting", () => {
+  const now = new Date().toISOString();
+
+  // Stacked run where headroom contributed 100 (recorded in breakdown).
+  insertCompressionAnalyticsRow({
+    timestamp: now,
+    mode: "stacked",
+    engine: "stacked",
+    request_id: "req-A",
+    original_tokens: 1000,
+    compressed_tokens: 800,
+    tokens_saved: 200,
+  });
+  insertCompressionEngineBreakdown([
+    {
+      timestamp: now,
+      request_id: "req-A",
+      engine: "headroom",
+      original_tokens: 1000,
+      compressed_tokens: 900,
+      tokens_saved: 100,
+    },
+  ]);
+
+  // Separate single-engine headroom run (no breakdown) contributed 50.
+  insertCompressionAnalyticsRow({
+    timestamp: now,
+    mode: "headroom",
+    engine: "headroom",
+    request_id: "req-B",
+    original_tokens: 200,
+    compressed_tokens: 150,
+    tokens_saved: 50,
+  });
+
+  const headroom = getPerEngineAnalytics("headroom");
+  assert.equal(headroom.runs, 2, "one stacked contribution + one single-engine run");
+  assert.equal(headroom.tokensSaved, 150, "100 (stacked) + 50 (single), counted once each");
+});
+
+test("a stacked run does NOT double-count the aggregate row under its breakdown engines", () => {
+  const now = new Date().toISOString();
+  insertCompressionAnalyticsRow({
+    timestamp: now,
+    mode: "stacked",
+    engine: "stacked",
+    request_id: "req-X",
+    original_tokens: 1000,
+    compressed_tokens: 700,
+    tokens_saved: 300,
+  });
+  insertCompressionEngineBreakdown([
+    {
+      timestamp: now,
+      request_id: "req-X",
+      engine: "caveman",
+      original_tokens: 1000,
+      compressed_tokens: 700,
+      tokens_saved: 300,
+    },
+  ]);
+
+  // caveman gets exactly the breakdown contribution, not also the "stacked" aggregate.
+  const caveman = getPerEngineAnalytics("caveman");
+  assert.equal(caveman.runs, 1);
+  assert.equal(caveman.tokensSaved, 300);
+});