fix(cron): tolerate unsupported directory fsync

nanobot/cron/service.py

@@ -1,6 +1,7 @@
 """Cron service for scheduling agent tasks."""
 
 import asyncio
+import errno
 import json
 import os
 import time
@@ -456,11 +457,15 @@ class CronService:
             os.replace(tmp_path, path)
             # fsync the parent directory so the rename itself is durable.
             # Skip on Windows where opening a directory raises PermissionError;
-            # NTFS journals metadata synchronously so this is a no-op there.
+            # some shared filesystems reject directory fsync with EINVAL.
             with suppress(PermissionError):
                 fd = os.open(str(path.parent), os.O_RDONLY)
                 try:
-                    os.fsync(fd)
+                    try:
+                        os.fsync(fd)
+                    except OSError as exc:
+                        if exc.errno != errno.EINVAL:
+                            raise
                 finally:
                     os.close(fd)
         except BaseException: