diff --git a/fluxer_api/src/api/worker/WorkerRunner.ts b/fluxer_api/src/api/worker/WorkerRunner.ts
index 37ab3acab..d48e838c4 100644
--- a/fluxer_api/src/api/worker/WorkerRunner.ts
+++ b/fluxer_api/src/api/worker/WorkerRunner.ts
@@ -11,6 +11,7 @@ import {getWorkerService} from '../middleware/ServiceRegistry';
 import {isJsonRecord, parseJsonRecord} from '../utils/JsonBoundaryUtils';
 
 const MAX_DLQ_PUBLISH_ATTEMPTS = 3;
+const MIN_ACK_HEARTBEAT_MS = 1000;
 
 interface WorkerRunnerJetStreamClient {
 	consumers: {
@@ -274,6 +275,7 @@ export class WorkerRunner {
 				}
 			},
 		};
+		const ackHeartbeat = this.startAckHeartbeat(taskType, msg);
 		try {
 			await task(jobPayload, helpers);
 			if (ledgerJobId !== null) {
@@ -351,6 +353,25 @@ export class WorkerRunner {
 				msg.nak(5000);
 			}
 			return false;
+		} finally {
+			clearInterval(ackHeartbeat);
 		}
 	}
+
+	private startAckHeartbeat(taskType: string, msg: JsMsg): ReturnType<typeof setInterval> {
+		const heartbeat = setInterval(
+			() => {
+				try {
+					msg.working();
+				} catch (err) {
+					Logger.warn({workerId: this.workerId, taskType, seq: msg.seq, err}, 'Failed to extend job ack deadline');
+				}
+			},
+			Math.max(MIN_ACK_HEARTBEAT_MS, Math.floor(this.ackWaitMs / 2)),
+		);
+		if (typeof heartbeat === 'object' && heartbeat && 'unref' in heartbeat) {
+			(heartbeat as {unref(): void}).unref();
+		}
+		return heartbeat;
+	}
 }
diff --git a/fluxer_api/src/api/worker/tests/WorkerAckHeartbeat.test.ts b/fluxer_api/src/api/worker/tests/WorkerAckHeartbeat.test.ts
new file mode 100644
index 000000000..29ab7ba18
--- /dev/null
+++ b/fluxer_api/src/api/worker/tests/WorkerAckHeartbeat.test.ts
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {JobCancelledError} from '@pkgs/worker/src/contracts/WorkerTask';
+import type {JsMsg} from 'nats';
+import {afterEach, beforeAll, describe, expect, it, vi} from 'vitest';
+import {KVScheduledJobQueueService} from '../../infrastructure/KVScheduledJobQueueService';
+import type {IJobLedgerRepository} from '../../jobs/IJobLedgerRepository';
+import {setInjectedWorkerService} from '../../middleware/ServiceRegistry';
+import {MockKVProvider} from '../../test/mocks/MockKVProvider';
+import {NoopWorkerService} from '../../test/NoopWorkerService';
+import {WorkerRunner} from '../WorkerRunner';
+
+const LANE_ACK_WAIT_MS = 120000;
+const LANE_MAX_DELIVER = 25;
+const TASK_TYPE = 'processInactivityDeletions';
+
+const queueStub = {
+	getConnectionManager: () => {
+		throw new Error('WorkerRunner tests never consume messages');
+	},
+	getStreamName: () => 'JOBS',
+	publishToDlq: vi.fn(),
+};
+
+class TestWorkerRunner extends WorkerRunner {
+	async runJob(taskType: string, msg: JsMsg): Promise<boolean> {
+		return await this.processJob(taskType, msg);
+	}
+}
+
+function createRunner(task: () => Promise<void>): TestWorkerRunner {
+	return new TestWorkerRunner({
+		tasks: {[TASK_TYPE]: task},
+		queue: queueStub,
+		scheduledJobQueue: new KVScheduledJobQueueService(new MockKVProvider()),
+		consumerName: 'workers_batch',
+		laneName: 'batch',
+		ledger: {} as IJobLedgerRepository,
+		concurrency: 12,
+		maxDeliver: LANE_MAX_DELIVER,
+		ackWaitMs: LANE_ACK_WAIT_MS,
+	});
+}
+
+function createJobMessage() {
+	const envelope = {
+		payload: {},
+		max_attempts: 5,
+		priority: 0,
+		created_at: new Date().toISOString(),
+	};
+	return {
+		seq: 1,
+		subject: `jobs.${TASK_TYPE}`,
+		redelivered: false,
+		data: new TextEncoder().encode(JSON.stringify(envelope)),
+		info: {deliveryCount: 1},
+		ack: vi.fn(),
+		nak: vi.fn(),
+		term: vi.fn(),
+		working: vi.fn(),
+	};
+}
+
+function createDeferredTask(): {task: () => Promise<void>; settle: (error?: Error) => void} {
+	let settle: (error?: Error) => void = () => {};
+	const pending = new Promise<void>((resolve, reject) => {
+		settle = (error?: Error) => {
+			if (error) {
+				reject(error);
+			} else {
+				resolve();
+			}
+		};
+	});
+	return {task: () => pending, settle: (error?: Error) => settle(error)};
+}
+
+describe('Worker ack heartbeat', () => {
+	beforeAll(() => {
+		setInjectedWorkerService(new NoopWorkerService());
+	});
+
+	afterEach(() => {
+		vi.useRealTimers();
+		queueStub.publishToDlq.mockClear();
+	});
+
+	it('holds the ack for a task running past the lane ack wait', async () => {
+		vi.useFakeTimers();
+		const {task, settle} = createDeferredTask();
+		const runner = createRunner(task);
+		const msg = createJobMessage();
+
+		const job = runner.runJob(TASK_TYPE, msg as unknown as JsMsg);
+		await vi.advanceTimersByTimeAsync(LANE_ACK_WAIT_MS * 3);
+
+		expect(msg.working.mock.calls.length).toBeGreaterThanOrEqual(1);
+		expect(msg.ack).not.toHaveBeenCalled();
+		expect(msg.nak).not.toHaveBeenCalled();
+
+		settle();
+		await expect(job).resolves.toBe(true);
+
+		expect(msg.ack).toHaveBeenCalledTimes(1);
+		const heartbeatsAtCompletion = msg.working.mock.calls.length;
+		await vi.advanceTimersByTimeAsync(LANE_ACK_WAIT_MS * 3);
+		expect(msg.working.mock.calls.length).toBe(heartbeatsAtCompletion);
+	});
+
+	it('stops the heartbeat when the task throws', async () => {
+		vi.useFakeTimers();
+		const {task, settle} = createDeferredTask();
+		const runner = createRunner(task);
+		const msg = createJobMessage();
+
+		const job = runner.runJob(TASK_TYPE, msg as unknown as JsMsg);
+		await vi.advanceTimersByTimeAsync(LANE_ACK_WAIT_MS);
+		expect(msg.working.mock.calls.length).toBeGreaterThanOrEqual(1);
+
+		settle(new Error('scan failed'));
+		await expect(job).resolves.toBe(false);
+
+		expect(msg.nak).toHaveBeenCalledTimes(1);
+		const heartbeatsAtCompletion = msg.working.mock.calls.length;
+		await vi.advanceTimersByTimeAsync(LANE_ACK_WAIT_MS * 3);
+		expect(msg.working.mock.calls.length).toBe(heartbeatsAtCompletion);
+	});
+
+	it('stops the heartbeat when the task is cancelled', async () => {
+		vi.useFakeTimers();
+		const {task, settle} = createDeferredTask();
+		const runner = createRunner(task);
+		const msg = createJobMessage();
+
+		const job = runner.runJob(TASK_TYPE, msg as unknown as JsMsg);
+		await vi.advanceTimersByTimeAsync(LANE_ACK_WAIT_MS);
+		expect(msg.working.mock.calls.length).toBeGreaterThanOrEqual(1);
+
+		settle(new JobCancelledError('cancelled by admin'));
+		await expect(job).resolves.toBe(false);
+
+		expect(msg.ack).toHaveBeenCalledTimes(1);
+		const heartbeatsAtCompletion = msg.working.mock.calls.length;
+		await vi.advanceTimersByTimeAsync(LANE_ACK_WAIT_MS * 3);
+		expect(msg.working.mock.calls.length).toBe(heartbeatsAtCompletion);
+	});
+
+	it('does not heartbeat a parked scheduled job', async () => {
+		const scheduledJobQueue = new KVScheduledJobQueueService(new MockKVProvider());
+		const runner = new TestWorkerRunner({
+			tasks: {[TASK_TYPE]: async () => {}},
+			queue: queueStub,
+			scheduledJobQueue,
+			consumerName: 'workers_batch',
+			laneName: 'batch',
+			ledger: {} as IJobLedgerRepository,
+			concurrency: 12,
+			maxDeliver: LANE_MAX_DELIVER,
+			ackWaitMs: LANE_ACK_WAIT_MS,
+		});
+		const runAt = new Date(Date.now() + 60 * 60 * 1000);
+		const envelope = {
+			payload: {},
+			run_at: runAt.toISOString(),
+			max_attempts: 5,
+			priority: 0,
+			created_at: new Date().toISOString(),
+		};
+		const msg = {
+			...createJobMessage(),
+			data: new TextEncoder().encode(JSON.stringify(envelope)),
+		};
+
+		await runner.runJob(TASK_TYPE, msg as unknown as JsMsg);
+
+		expect(msg.ack).toHaveBeenCalledTimes(1);
+		expect(msg.working).not.toHaveBeenCalled();
+		expect(await scheduledJobQueue.getQueueSize()).toBe(1);
+	});
+});