fix: Do not `process.exit(0)` in the middle of a test.

src/agents/session-write-lock.ts

@@ -34,6 +34,7 @@ async function releaseAllLocks(): Promise<void> {
   }
 }
 
+if (process.env.NODE_ENV !== "test" && !process.env.VITEST) {
   // Register cleanup handlers to release locks on unexpected termination
   process.on("exit", releaseAllLocks);
   process.on("SIGTERM", () => {
@@ -43,6 +44,7 @@ process.on("SIGINT", () => {
     void releaseAllLocks().then(() => process.exit(0));
   });
   // Note: unhandledRejection handler will call process.exit() which triggers 'exit'
+}
 
 function isAlive(pid: number): boolean {
   if (!Number.isFinite(pid) || pid <= 0) {