Stabilize app-server test cleanup

Co-Authored-By: OpenAI Codex <noreply@openai.com>

Author: xuio

test/app-server-hardening.test.ts

@@ -42,8 +42,22 @@ async function waitFor(
   return Boolean(await predicate());
 }
 
+async function removeTempDir(dir: string): Promise<void> {
+  for (let attempt = 0; attempt < 5; attempt += 1) {
+    try {
+      await rm(dir, { recursive: true, force: true });
+      return;
+    } catch (error) {
+      const code = (error as NodeJS.ErrnoException).code;
+      if (code !== "ENOTEMPTY" && code !== "EBUSY" && code !== "EPERM") throw error;
+      await new Promise((resolve) => setTimeout(resolve, 25 * (attempt + 1)));
+    }
+  }
+  await rm(dir, { recursive: true, force: true });
+}
+
 afterEach(async () => {
-  await Promise.all(tempDirs.splice(0).map((dir) => rm(dir, { recursive: true, force: true })));
+  await Promise.all(tempDirs.splice(0).map(removeTempDir));
 });
 
 describe("app-server hardening", () => {