diff --git a/src/agents/session-write-lock.ts b/src/agents/session-write-lock.ts
index 3890a759338..364cc7717cd 100644
--- a/src/agents/session-write-lock.ts
+++ b/src/agents/session-write-lock.ts
@@ -221,7 +221,14 @@ function stopWatchdogTimer(): void {
   watchdogState.started = false;
 }
 
+function shouldStartBackgroundWatchdog(): boolean {
+  return process.env.VITEST !== "true" || process.env.OPENCLAW_TEST_SESSION_LOCK_WATCHDOG === "1";
+}
+
 function ensureWatchdogStarted(intervalMs: number): void {
+  if (!shouldStartBackgroundWatchdog()) {
+    return;
+  }
   const watchdogState = resolveWatchdogState();
   if (watchdogState.started) {
     return;