diff --git a/src/cron/service.issue-regressions.test.ts b/src/cron/service.issue-regressions.test.ts
index 058b971943..1899f54fc8 100644
--- a/src/cron/service.issue-regressions.test.ts
+++ b/src/cron/service.issue-regressions.test.ts
@@ -5,6 +5,7 @@ import path from "node:path";
 import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import * as schedule from "./schedule.js";
 import { CronService } from "./service.js";
+import { createRunningCronServiceState } from "./service.test-harness.js";
 import { computeJobNextRunAtMs } from "./service/jobs.js";
 import { createCronServiceState, type CronEvent } from "./service/state.js";
 import { onTimer } from "./service/timer.js";
@@ -410,20 +411,12 @@ describe("Cron issue regressions", () => {
     const timeoutSpy = vi.spyOn(globalThis, "setTimeout");
     const store = await makeStorePath();
     const now = Date.parse("2026-02-06T10:05:00.000Z");
-    const state = createCronServiceState({
-      cronEnabled: true,
+    const state = createRunningCronServiceState({
       storePath: store.storePath,
       log: noopLogger,
       nowMs: () => now,
-      enqueueSystemEvent: vi.fn(),
-      requestHeartbeatNow: vi.fn(),
-      runIsolatedAgentJob: vi.fn().mockResolvedValue({ status: "ok", summary: "ok" }),
-    });
-    state.running = true;
-    state.store = {
-      version: 1,
       jobs: [createDueIsolatedJob({ id: "due", nowMs: now, nextRunAtMs: now - 1 })],
-    };
+    });
 
     await onTimer(state);
 
diff --git a/src/cron/service.rearm-timer-when-running.test.ts b/src/cron/service.rearm-timer-when-running.test.ts
index 90f7d73533..6dfb0284a1 100644
--- a/src/cron/service.rearm-timer-when-running.test.ts
+++ b/src/cron/service.rearm-timer-when-running.test.ts
@@ -1,6 +1,9 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
-import { createCronStoreHarness, createNoopLogger } from "./service.test-harness.js";
-import { createCronServiceState } from "./service/state.js";
+import {
+  createCronStoreHarness,
+  createNoopLogger,
+  createRunningCronServiceState,
+} from "./service.test-harness.js";
 import { onTimer } from "./service/timer.js";
 import type { CronJob } from "./types.js";
 
@@ -45,20 +48,10 @@ describe("CronService - timer re-arm when running (#12025)", () => {
     const store = await makeStorePath();
     const now = Date.parse("2026-02-06T10:05:00.000Z");
 
-    const state = createCronServiceState({
-      cronEnabled: true,
+    const state = createRunningCronServiceState({
       storePath: store.storePath,
       log: noopLogger,
       nowMs: () => now,
-      enqueueSystemEvent: vi.fn(),
-      requestHeartbeatNow: vi.fn(),
-      runIsolatedAgentJob: vi.fn().mockResolvedValue({ status: "ok", summary: "ok" }),
-    });
-
-    // Simulate a job that is currently running.
-    state.running = true;
-    state.store = {
-      version: 1,
       jobs: [
         createDueRecurringJob({
           id: "recurring-job",
@@ -66,7 +59,7 @@ describe("CronService - timer re-arm when running (#12025)", () => {
           nextRunAtMs: now + 5 * 60_000,
         }),
       ],
-    };
+    });
 
     // Before the fix in #12025, this would return without re-arming,
     // silently killing the scheduler.
diff --git a/src/cron/service.test-harness.ts b/src/cron/service.test-harness.ts
index 05db703d6c..641f8fd3a9 100644
--- a/src/cron/service.test-harness.ts
+++ b/src/cron/service.test-harness.ts
@@ -5,6 +5,8 @@ import { afterAll, afterEach, beforeAll, beforeEach, vi } from "vitest";
 import type { MockFn } from "../test-utils/vitest-mock-fn.js";
 import type { CronEvent } from "./service.js";
 import { CronService } from "./service.js";
+import { createCronServiceState } from "./service/state.js";
+import type { CronJob } from "./types.js";
 
 export type NoopLogger = {
   debug: MockFn;
@@ -111,3 +113,26 @@ export function createStartedCronServiceWithFinishedBarrier(params: {
   });
   return { cron, enqueueSystemEvent, requestHeartbeatNow, finished };
 }
+
+export function createRunningCronServiceState(params: {
+  storePath: string;
+  log: ReturnType<typeof createNoopLogger>;
+  nowMs: () => number;
+  jobs: CronJob[];
+}) {
+  const state = createCronServiceState({
+    cronEnabled: true,
+    storePath: params.storePath,
+    log: params.log,
+    nowMs: params.nowMs,
+    enqueueSystemEvent: vi.fn(),
+    requestHeartbeatNow: vi.fn(),
+    runIsolatedAgentJob: vi.fn().mockResolvedValue({ status: "ok", summary: "ok" }),
+  });
+  state.running = true;
+  state.store = {
+    version: 1,
+    jobs: params.jobs,
+  };
+  return state;
+}