fix: suppress synthetic observability alert (#25)

Author: Programcode

src/lib/observability.ts

@@ -101,6 +101,7 @@ export function initializeObservability(): void {
     Sentry.init({
       dsn: sentryDsn,
       environment: import.meta.env.MODE,
+      ignoreErrors: [/^Synthetic observability verification$/],
       sendDefaultPii: false,
       beforeBreadcrumb: filterObservabilityBreadcrumb,
       dataCollection: {

src/test/observability.test.ts

@@ -209,6 +209,7 @@ describe("observability primitives", () => {
     expect(sentryInitMock).toHaveBeenCalledOnce();
     expect(sentryInitMock).toHaveBeenCalledWith(expect.objectContaining({
       dsn: "https://public-test@sentry.example/1",
+      ignoreErrors: [/^Synthetic observability verification$/],
       sendDefaultPii: false,
       beforeBreadcrumb: filterObservabilityBreadcrumb,
       dataCollection: {

src/test/sentry-event-filter.test.ts

@@ -0,0 +1,31 @@
+import * as Sentry from "@sentry/react";
+import { describe, expect, it, vi } from "vitest";
+
+describe("Sentry event filtering", () => {
+  it("drops only the exact synthetic observability verification error", async () => {
+    const send = vi.fn(async () => ({}));
+
+    Sentry.init({
+      dsn: "https://0123456789abcdef0123456789abcdef@o0.ingest.sentry.io/1",
+      ignoreErrors: [/^Synthetic observability verification$/],
+      transport: () => ({
+        send,
+        flush: async () => true,
+      }),
+    });
+
+    Sentry.captureException(new Error("Synthetic observability verification"));
+    await Sentry.flush(1_000);
+    expect(send).not.toHaveBeenCalled();
+
+    Sentry.captureException(new Error("Synthetic observability verification failed"));
+    await Sentry.flush(1_000);
+    expect(send).toHaveBeenCalledOnce();
+
+    Sentry.captureException(new Error("Real privacy route failure"));
+    await Sentry.flush(1_000);
+    expect(send).toHaveBeenCalledTimes(2);
+
+    await Sentry.close(1_000);
+  });
+});