fix(pairing): restore durable atomic writes

nanobot/utils/helpers.py

@@ -2,6 +2,7 @@
 
 import base64
 import json
+import os
 import re
 import shutil
 import time
@@ -447,8 +448,17 @@ def _cleanup_tool_result_buckets(root: Path, current_bucket: Path) -> None:
 def _write_text_atomic(path: Path, content: str) -> None:
     tmp = path.with_name(f".{path.name}.{uuid.uuid4().hex}.tmp")
     try:
-        tmp.write_text(content, encoding="utf-8")
+        with open(tmp, "w", encoding="utf-8") as f:
+            f.write(content)
+            f.flush()
+            os.fsync(f.fileno())
         tmp.replace(path)
+        with suppress(OSError, NotImplementedError):
+            dfd = os.open(path.parent, os.O_RDONLY)
+            try:
+                os.fsync(dfd)
+            finally:
+                os.close(dfd)
     finally:
         if tmp.exists():
             tmp.unlink(missing_ok=True)