feat(core-shared): IMetrics interface + NoopMetrics impl

packages/core-shared/src/instrumentation/noop-metrics.test.ts

@@ -0,0 +1,29 @@
+import { describe, it, expect } from "vitest";
+import { NoopMetrics } from "./noop-metrics";
+
+describe("NoopMetrics", () => {
+  it("counter() returns undefined without throwing", () => {
+    const metrics = new NoopMetrics();
+    expect(() => metrics.counter("my.counter")).not.toThrow();
+    expect(() => metrics.counter("my.counter", 5)).not.toThrow();
+    expect(() =>
+      metrics.counter("my.counter", 1, { feature: "auth", success: true }),
+    ).not.toThrow();
+  });
+
+  it("histogram() returns undefined without throwing", () => {
+    const metrics = new NoopMetrics();
+    expect(() => metrics.histogram("my.latency", 42)).not.toThrow();
+    expect(() =>
+      metrics.histogram("my.latency", 100, { route: "/api/me" }),
+    ).not.toThrow();
+  });
+
+  it("gauge() returns undefined without throwing", () => {
+    const metrics = new NoopMetrics();
+    expect(() => metrics.gauge("queue.depth", 7)).not.toThrow();
+    expect(() =>
+      metrics.gauge("queue.depth", 3, { queue: "emails" }),
+    ).not.toThrow();
+  });
+});