test(server): reproduce idle plugin scheduler polling

Audit and failing regression for the next migration; implementation pending.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/__tests__/plugin-scheduled-work.test.ts

@@ -0,0 +1,33 @@
+import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from "vitest";
+import { sql } from "drizzle-orm";
+import { createDb } from "@paperclipai/db";
+import { getEmbeddedPostgresTestSupport, startEmbeddedPostgresTestDatabase } from "./helpers/embedded-postgres.js";
+import { resolveExternalTestDatabaseUrl } from "./helpers/external-test-database.js";
+import { createPluginJobScheduler } from "../services/plugin-job-scheduler.js";
+import { pluginJobStore } from "../services/plugin-job-store.js";
+import type { PluginWorkerManager } from "../services/plugin-worker-manager.js";
+
+const external = resolveExternalTestDatabaseUrl("PAPERCLIP_PLUGIN_SCHEDULE_TEST_DATABASE_URL");
+const support = external ? { supported: true } : await getEmbeddedPostgresTestSupport();
+(support.supported ? describe : describe.skip)("plugin job scheduling without idle polling", () => {
+  let temporary: Awaited<ReturnType<typeof startEmbeddedPostgresTestDatabase>> | undefined;
+  let db: ReturnType<typeof createDb>;
+  let scheduler: ReturnType<typeof createPluginJobScheduler> | undefined;
+  beforeAll(async () => {
+    if (!external) temporary = await startEmbeddedPostgresTestDatabase("plugin-schedule-");
+    db = createDb(external ?? temporary!.connectionString, { idleTimeoutSeconds: 0, maxLifetimeSeconds: 0 });
+    await db.execute(sql`select 1`);
+  }, 30_000);
+  afterEach(() => { scheduler?.stop(); vi.useRealTimers(); vi.restoreAllMocks(); });
+  afterAll(async () => { await db?.$client.end({ timeout: 1 }); await temporary?.cleanup(); });
+
+  it("does not query repeatedly after an empty startup reconciliation", async () => {
+    const workerManager = { isRunning: () => false, call: vi.fn() } as unknown as PluginWorkerManager;
+    scheduler = createPluginJobScheduler({ db, jobStore: pluginJobStore(db), workerManager });
+    vi.useFakeTimers({ toFake: ["Date", "setTimeout", "clearTimeout", "setInterval", "clearInterval"], shouldAdvanceTime: true });
+    scheduler.start(); await scheduler.tick();
+    const reads = vi.spyOn(db, "select");
+    await vi.advanceTimersByTimeAsync(180_000);
+    expect(reads).not.toHaveBeenCalled();
+  });
+});