diff --git a/server/test/unit/services/jobScheduler.test.ts b/server/test/unit/services/jobScheduler.test.ts
new file mode 100644
index 000000000..9fd2ee0db
--- /dev/null
+++ b/server/test/unit/services/jobScheduler.test.ts
@@ -0,0 +1,46 @@
+import { describe, expect, it, jest } from "@jest/globals";
+import { JobScheduler } from "../../../src/worker/worker.job-scheduler.ts";
+import { createMockLogger } from "../../helpers/createMockLogger.ts";
+
+// ── Notes ──────────────────────────────────────────────────────────────────────
+//
+// JobScheduler is the scheduler-only primary base class: it owns the queue
+// registry/heartbeat but processes no jobs and has no buffer. drain() is therefore
+// a no-op beyond setting the stop flag — it must NOT tear down (clear timers or
+// deregister the worker); that stays in shutdown(). The real draining (wait for
+// in-flight, flush buffer) lives in DBQueueWorker and is covered separately.
+
+const createScheduler = () => {
+	const jobsRepository = {} as any;
+	const queueWorkersRepository = {
+		deleteById: jest.fn<any>().mockResolvedValue(undefined),
+	};
+	const logger = createMockLogger();
+	const scheduler = new JobScheduler(jobsRepository, queueWorkersRepository as any, "worker-1");
+	return { scheduler, mocks: { jobsRepository, queueWorkersRepository, logger } };
+};
+
+describe("JobScheduler", () => {
+	describe("drain", () => {
+		it("sets the stop flag without tearing down (no deregister)", async () => {
+			const { scheduler, mocks } = createScheduler();
+
+			await scheduler.drain();
+
+			expect((scheduler as any).stopped).toBe(true);
+			// drain must not do shutdown's teardown work
+			expect(mocks.queueWorkersRepository.deleteById).not.toHaveBeenCalled();
+		});
+
+		it("stops wake() from arming a tick once drained", async () => {
+			const { scheduler } = createScheduler();
+			const tick = jest.fn<any>();
+			(scheduler as any).tickFns.set("check", tick);
+
+			await scheduler.drain();
+			scheduler.wake("check");
+
+			expect((scheduler as any).timers.has("check")).toBe(false);
+		});
+	});
+});