chore: import upstream snapshot with attribution

tests/unit/db-compression-cache-stats.test.ts

@@ -0,0 +1,53 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+
+import {
+  recordCacheStats,
+  getCacheStatsSummary,
+} from "../../src/lib/db/compressionCacheStats.ts";
+
+describe("compressionCacheStats", () => {
+  it("getCacheStatsSummary returns summary", () => {
+    const summary = getCacheStatsSummary();
+    assert.ok(typeof summary.totalRequests === "number");
+    assert.ok(typeof summary.avgNetSavings === "number");
+    assert.ok(typeof summary.cacheHitRate === "number");
+    assert.ok(typeof summary.byProvider === "object");
+  });
+
+  it("recordCacheStats inserts and getCacheStatsSummary retrieves", () => {
+    recordCacheStats({
+      provider: "test-provider",
+      model: "test-model",
+      compressionMode: "lite",
+      cacheControlPresent: true,
+      estimatedCacheHit: true,
+      tokensSavedCompression: 100,
+      tokensSavedCaching: 50,
+      netSavings: 150,
+    });
+    const summary = getCacheStatsSummary();
+    assert.ok(summary.totalRequests >= 1, "should have at least 1 request");
+    assert.ok("test-provider" in summary.byProvider, "should have test-provider");
+  });
+
+  it("recordCacheStats handles missing model", () => {
+    recordCacheStats({
+      provider: "no-model-provider",
+      compressionMode: "standard",
+      cacheControlPresent: false,
+      estimatedCacheHit: false,
+      tokensSavedCompression: 0,
+      tokensSavedCaching: 0,
+      netSavings: 0,
+    });
+    const summary = getCacheStatsSummary();
+    assert.ok("no-model-provider" in summary.byProvider);
+  });
+
+  it("getCacheStatsSummary with since filter", () => {
+    const future = new Date(Date.now() + 86400000);
+    const summary = getCacheStatsSummary(future);
+    assert.equal(summary.totalRequests, 0, "future date should return 0");
+  });
+});