feat(events): stream Redis invalidations over SSE

lib/events/refresh.test.ts

@@ -0,0 +1,30 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { createRefreshScheduler } from "./refresh";
+
+afterEach(() => {
+  vi.useRealTimers();
+});
+
+describe("authoritative refresh scheduler", () => {
+  it("refetches on connection and coalesces duplicate notifications", async () => {
+    vi.useFakeTimers();
+    const refresh = vi.fn();
+    const scheduler = createRefreshScheduler(refresh, { delayMs: 25 });
+    const event = { type: "page.updated" as const, id: "page", version: 5 };
+
+    scheduler.connected();
+    await vi.advanceTimersByTimeAsync(25);
+    expect(refresh).toHaveBeenCalledTimes(1);
+
+    scheduler.notified(event);
+    scheduler.notified(event);
+    await vi.advanceTimersByTimeAsync(25);
+    expect(refresh).toHaveBeenCalledTimes(2);
+
+    scheduler.connected();
+    await vi.advanceTimersByTimeAsync(25);
+    expect(refresh).toHaveBeenCalledTimes(3);
+    scheduler.dispose();
+  });
+});