diff --git a/src/core/store.ts b/src/core/store.ts
index baa1cbf..f74dd1a 100644
--- a/src/core/store.ts
+++ b/src/core/store.ts
@@ -20,6 +20,7 @@ import { randomUUID } from 'node:crypto';
 import { dirname, resolve } from 'node:path';
 import type { AgentStore, LastMessageTarget } from './types.js';
 import { getDataDir } from '../utils/paths.js';
+import { sleepSync } from '../utils/time.js';
 import { createLogger } from '../logger.js';
 
 const log = createLogger('Store');
@@ -28,7 +29,6 @@ const DEFAULT_STORE_PATH = 'lettabot-agent.json';
 const LOCK_RETRY_MS = 25;
 const LOCK_TIMEOUT_MS = 5_000;
 const LOCK_STALE_MS = 30_000;
-const SLEEP_BUFFER = new Int32Array(new SharedArrayBuffer(4));
 
 interface StoreV2 {
   version: 2;
@@ -40,23 +40,6 @@ interface ParsedStore {
   wasV1: boolean;
 }
 
-let warnedAboutBusyWait = false;
-
-function sleepSync(ms: number): void {
-  if (typeof Atomics.wait === 'function') {
-    Atomics.wait(SLEEP_BUFFER, 0, 0, ms);
-    return;
-  }
-  if (!warnedAboutBusyWait) {
-    log.warn('Atomics.wait unavailable, falling back to busy-wait for lock retries');
-    warnedAboutBusyWait = true;
-  }
-  const end = Date.now() + ms;
-  while (Date.now() < end) {
-    // Busy-wait fallback -- should not be reached in standard Node.js (v8+)
-  }
-}
-
 export class Store {
   private readonly storePath: string;
   private readonly lockPath: string;
@@ -197,7 +180,9 @@ export class Store {
         if (Date.now() - start >= LOCK_TIMEOUT_MS) {
           throw new Error(`Timed out waiting for store lock: ${this.lockPath}`);
         }
-        sleepSync(LOCK_RETRY_MS);
+        sleepSync(LOCK_RETRY_MS, () => {
+          log.warn('Atomics.wait unavailable, falling back to busy-wait for lock retries');
+        });
       }
     }
   }
diff --git a/src/main.ts b/src/main.ts
index ce3701b..2487a77 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -25,6 +25,7 @@ import {
 import { isLettaApiUrl } from './utils/server.js';
 import { getDataDir, getWorkingDir, hasRailwayVolume } from './utils/paths.js';
 import { parseCsvList, parseNonNegativeNumber } from './utils/parse.js';
+import { sleep } from './utils/time.js';
 import { createLogger, setLogLevel } from './logger.js';
 
 const log = createLogger('Config');
@@ -211,10 +212,6 @@ const DISCOVERY_LOCK_TIMEOUT_MS = 15_000;
 const DISCOVERY_LOCK_STALE_MS = 60_000;
 const DISCOVERY_LOCK_RETRY_MS = 100;
 
-function sleep(ms: number): Promise<void> {
-  return new Promise(resolve => setTimeout(resolve, ms));
-}
-
 function getDiscoveryLockPath(agentName: string): string {
   const safe = agentName
     .trim()
diff --git a/src/utils/time.test.ts b/src/utils/time.test.ts
new file mode 100644
index 0000000..d3eb1b8
--- /dev/null
+++ b/src/utils/time.test.ts
@@ -0,0 +1,16 @@
+import { describe, expect, it } from 'vitest';
+import { sleep, sleepSync } from './time.js';
+
+describe('sleep', () => {
+  it('waits asynchronously', async () => {
+    const start = Date.now();
+    await sleep(10);
+    expect(Date.now() - start).toBeGreaterThanOrEqual(8);
+  });
+});
+
+describe('sleepSync', () => {
+  it('does not throw for zero delay', () => {
+    expect(() => sleepSync(0)).not.toThrow();
+  });
+});
diff --git a/src/utils/time.ts b/src/utils/time.ts
new file mode 100644
index 0000000..10cc481
--- /dev/null
+++ b/src/utils/time.ts
@@ -0,0 +1,25 @@
+/**
+ * Shared timing helpers used across startup and persistence paths.
+ */
+
+const SLEEP_BUFFER = new Int32Array(new SharedArrayBuffer(4));
+let warnedAboutBusyWait = false;
+
+export function sleep(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+export function sleepSync(ms: number, onBusyWait?: () => void): void {
+  if (typeof Atomics.wait === 'function') {
+    Atomics.wait(SLEEP_BUFFER, 0, 0, ms);
+    return;
+  }
+  if (!warnedAboutBusyWait) {
+    onBusyWait?.();
+    warnedAboutBusyWait = true;
+  }
+  const end = Date.now() + ms;
+  while (Date.now() < end) {
+    // Busy-wait fallback -- should not be reached in standard Node.js (v8+)
+  }
+}